Biological activities of flavonoids from Nitraria retusa (Forssk.) Asch. and their acylated derivatives

The antioxidant activity and antiproliferative property towards Caco2 cells of water and methanol extracts/fractions of Nitraria retusa were investigated. The total phenolic and flavonoid contents of the extracts/fractions were determined, and the four major flavonoids were identified as isorhamnetin, isorhamnetin-3-O-glucoside, isorhamnetin-3-O-rutinoside and isorhamnetin-3-O-robinobioside. The results showed a relationship between the extracts/fractions activities and their flavonoid contents. Moreover, the chloroform extract which was enriched with the aglycone flavonoid isorhamnetin exhibited the highest activities. The activities of N. retusa flavonoids were compared to those of model flavonoids, quercetin, isoquercitrin and rutin. In all cases, the aglycone compounds were more active than their glycosylated derivatives. Isorhamnetin-based flavonoids presented higher antiproliferative activities than quercetin-based ones, while similar antioxidant properties were observed. The enzymatic acylation of isorhamnetin-3-O-glucoside with ethyl laurate and ethyl butyrate enhanced its capacity to inhibit xanthine oxidase and its antiproliferative activity but decreased its radical scavenging activity.     

Preparation of double layered shell microparticles containing an acid dye by a melt dispersion–coacervation technique

Two types of microparticles with a double layered shell containing an acid dye were prepared by using a melt dispersion–coacervation process. The surface morphology and the composition of the microcapsules were investigated using scanning electron microscope (SEM), and Fourier-transform infrared spectroscope (FTIR) respectively. The results showed that the loading content and morphologies strongly depend on the composition, the protective colloid, as well as on the outer polymeric shell and the way the solvent solubilizes it. The thermo-physical properties strongly depend on the nature of the core content and the synthesis conditions. Factors affecting the release performance of the microcapsules were investigated and the results are presented in this paper.     

Corpus d'extraits musicaux: indices relatifs à la familiarité, à l'age d'acquisition et aux évocations verbales.

Studied the degree of familiarity, the age of acquisition, and verbal associations with regard to 144 musical excerpts drawn from the repertory of tunes that is expected to be shared by all French-speaking Quebec university students. Human Ss: 60 normal male and female Canadian adults (aged 21–45 yrs) (university students) (Group 1). 60 normal male and female Canadian adults (aged 19–43 yrs) (university students) (Group 2). The excerpts were presented to all Ss in synthesized, monophonic recordings. Ss in Group 1 were asked to indicate their degree of familiarity with each excerpt and the age at which they learned the excerpt. Ss in Group 2 were asked to indicate whether the original tune was vocal or instrumental and to provide verbal associations for the excerpts. The degree of familiarity, developmental period of acquisition, frequency of verbal associations, and dominant verbal association were determined for each excerpt. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stereotype threat among schoolgirls in quasi-ordinary classroom circumstances.

There is ample evidence today in the stereotype threat literature that women and girls are influenced by gender-stereotyped expectations on standardized math tests. Despite its high relevance to education, this phenomenon has not received much attention in school settings. The present studies offer the 1st evidence to date indicating that middle school girls exhibit a performance deficit in quasi-ordinary classroom circumstances when they are simply led to believe that the task at hand measures mathematical skills. This deficit occurred in girls working alone or in mixed-gender groups (i.e., presence of regular classmates) but not in same-gender groups (i.e., presence of only same-gender classmates). Compared with the mixed-gender groups, the same-gender groups were also associated for girls in the stereotype threat condition with greater accessibility of positive role models (i.e., female classmates who excel in math), at the expense of both stereotypic in-group and out-group members (i.e., low-math-achievement girls and high-math-achievement boys). Finally, the greater accessibility of positive role models mediated the impact of the activated stereotype on girls' performance, exactly as one would expect from C. M. Steele's (1997) stereotype threat theory. Taken together, these findings clearly show that reducing stereotype threat in the classroom is a crucial challenge for both scientists and teachers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

PAC-Membrane Filtration Process.?II: Model Application

The models developed in the first part of this study are applied to predict the removal of 4-nitrophenol by powdered activated carbon (PAC) in a bench-scale reactor. A series of continuous-flow filtration experiments were conducted with different carbon doses to verify the modeling approach when the activated carbon was added directly to the membrane reactor, either as step or pulse input, and when the carbon was dosed as a step input to a continuous-flow stirred tank reactor followed by the membrane reactor. The models predicted well the experimental data for all cases investigated. The verified model was used to investigate the effect of various operating parameters on the efficiency of the adsorption process. This analysis included the effect of filtration time, membrane reactor volume, dosing procedure, and the effect of dosing the carbon in reactors installed in series upstream of the membrane reactor.     

Synthesis of a Mullite Precursor from Aluminum Nitrate and Tetraethoxysilane via Aqueous Homogeneous Precipitation: An 27Al and 29Si Liquid- and Solid-State NMR Spectroscopic Study

A simple aqueous process is described for the preparation of aluminosilicate colloids and chemically homogeneous mullite precursor gel. Starting from a solution of aluminum nitrate and silicic acid, aluminum is slowly hydrolyzed at 80–100°C by in situ generation of ammonia. A silica gel is rapidly made, probably by a catalytic effect of urea, the base generator. This gel is then slowly digested by partially hydrolyzed aluminum species which break the Si-O-Si bonds and link to the gel by Si-O-Al bonds. Progressively a clear colloidal sol is obtained and the colloidal particle size continues to decrease toward aluminosilicate species where the silicon atoms are in a single environment and may be linked to three hexacoordinated aluminum atoms and a hydroxyl group, by reference to natural imogolite. When the hydrolysis of aluminum is nearly complete, these particles are cross-linked and a final gel precursor of mullite is obtained. This gel is chemically very homogeneous and crystallizes to mullite at 980°C. The structural evolution, from the first gel to the ceramic, has been followed by ²⁷Al and ²⁹Si liquid- and solid-state MAS NMR spectroscopy.     

Le premier vocabulaire de sciences cognitives en langue fran?aise.

Reviews the book, Vocabulaire de sciences cognitives by O. Houdé, D. Kayser, O. Koenig, J. Proust, and F. Rastier (1998). The Vocabulaire de sciences cognitives contains 130 alphabetically ordered entries, each entry corresponding to a different word or expression used in cognitive science. The entries are treated from the point of view of each of the five main disciplines contributing to cognitive science: artificial intelligence, neuroscience, linguistics, philosophy, and psychology. The texts concerning a given entry form distinct sections labeled with the name of the discipline concerned. Numerous cross-references to related entries are given. Overall, the Vocabulaire contains about 200 different texts, a third of which have been authored by the members of the editorial board, each of whom is specialized in one of the disciplines mentioned; the remaining texts were written by 54 other authors from these various fields. Of the 130 entries, only 2 very pivotal terms in cognitive science (FUNCTION and REPRESENTATION) receive complete multidisciplinary treatment; 15 entries referring mostly to major cognitive functions (e.g., LANGUAGE, LEARNING, MEMORY, PERCEPTION, REASONING) are covered by three or four disciplines, and 31 others receive a bidisciplinary treatment. Analysis of the 144 pairs of disciplines found in these 48 entries shows the neighborhood among disciplines to be fairly evenly distributed except in the case of psychology and neuroscience, whose greater conceptual proximity is explained by the fact that most neuroscience texts have been written by neuropsychologists. The contributions of the various disciplines were reviewed by one specialist and by at least one nonspecialist. Although predictably more critical, the specialists did not identify many serious problems or errors. However, the reviewers expressed some reservations concerning the choice of the terms deemed worth of an entry, the limited number of disciplines contributing to some entries, the variable length and nature of the texts, as well as the exaggerated place sometimes given to secondary research. If the Vocabulaire de sciences cognitives does not constitute a monumental achievement, it is nonetheless an impressive piece of work, especially considering the breadth and state of the domain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Photocontrol of Protein Activity in Cultured Cells and Zebrafish with One‐ and Two‐Photon Illumination

We have implemented a noninvasive optical method for the fast control of protein activity in a live zebrafish embryo. It relies on releasing a protein fused to a modified estrogen receptor ligand binding domain from its complex with cytoplasmic chaperones, upon the local photoactivation of a nonendogenous caged inducer. Molecular dynamics simulations were used to design cyclofen‐OH, a photochemically stable inducer of the receptor specific for 4‐hydroxy‐tamoxifen (ER^T2). Cyclofen‐OH was easily synthesized in two steps with good yields. At submicromolar concentrations, it activates proteins fused to the ER^T2 receptor. This was shown in cultured cells and in zebrafish embryos through emission properties and subcellular localization of properly engineered fluorescent proteins. Cyclofen‐OH was successfully caged with various photolabile protecting groups. One particular caged compound was efficient in photoinducing the nuclear translocation of fluorescent proteins either globally (with 365 nm UV illumination) or locally (with a focused UV laser or with two‐photon illumination at 750 nm). The present method for photocontrol of protein activity could be used more generally to investigate important physiological processes (e.g., in embryogenesis, organ regeneration and carcinogenesis) with high spatiotemporal resolution.     

Enhancement of polylactide nucleation by montmorillonites intercalated with a green seaweed byproduct

Polylactide (PLA) nanocomposites with improved mechanical and barrier properties are of growing industrial interest and therefore required green modified montmorillonites (gm‐MMTs) to meet the expectation of totally biosourced material. In this study, ulvans that are polysaccharides and glycoproteins extracted from seaweed are used as surfactants to achieve intercalated clays. The effect of this gm‐MMT (ALL350) on the crystallization kinetics of PLA was compared to Cloisite 30B, and pristine MMT was taken as a reference. Rheology, differential scanning calorimetry, and transmission electronic microscopy experiments were performed to better understand the effects that dominate the so‐called nucleating effect observed in PLA nanocomposites. It was found that two major driving forces explain the efficiency of the ALL350 that enhances PLA nucleation. The first one is the decrease of the interfacial energy and the second is a reduction of the complex viscosity that acts on the induction period. Reduction of both the interfacial energy and the surface friction forces between PLA chains and polysaccharides‐treated clay platelets is assumed to facilitate the induction process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013