Particle agglomeration study in rf silane plasmas: In situ study by polarization-sensitive laser light scattering

To determine self‐consistently the time evolution of particle size and their number density in situ multi‐angle polarization‐sensitive laser light scattering was used. Cross‐polarization intensities (incident and scattered light intensities with opposite polarization) measured at 135° and ex situ transmission electronic microscopy analysis demonstrate the existence of nonspherical agglomerates during the early phase of agglomeration. Later in the particle time development both techniques reveal spherical particles again. The presence of strong cross‐polarization intensities is accompanied by low‐frequency instabilities detected on the scattered light intensities and plasma emission. It is found that the particle radius and particle number density during the agglomeration phase can be well described by the Brownian free molecule coagulation model. Application of this neutral particle coagulation model is justified by calculation of the particle charge whereby it is shown that particles of a few tens of nanometer can be considered as neutral under our experimental conditions. The measured particle dispersion can be well described by a Brownian free molecule coagulation model including a log‐normal particle size distribution.

In vitro antitumor activity of methotrexate via pH-sensitive chitosan nanoparticles

Nanoparticles with pH-sensitive behavior may enhance the success of chemotherapy in many cancers by efficient intracellular drug delivery. Here, we investigated the effect of a bioactive surfactant with pH-sensitive properties on the antitumor activity and intracellular behavior of methotrexate-loaded chitosan nanoparticles (MTX-CS-NPs). NPs were prepared using a modified ionotropic complexation process, in which was included the surfactant derived from Nα,Nε-dioctanoyl lysine with an inorganic lithium counterion. The pH-sensitive behavior of NPs allowed accelerated release of MTX in an acidic medium, as well as membrane-lytic pH-dependent activity, which facilitated the cytosolic delivery of endocytosed materials. Moreover, our results clearly proved that MTX-CSNPs were more active against the tumor HeLa and MCF-7 cell lines than the free drug. The feasibilty of using NPs to target acidic tumor extracellular pH was also shown, as cytotoxicity against cancer cells was greater in a mildly acidic environment. Finally, the combined physicochemical and pH-sensitive properties of NPs generally allowed the entrapped drug to induce greater cell cycle arrest and apoptotic effects. Therefore, our overall results suggest that pH-sensitive MTX-CS-NPs could be potentially useful as a carrier system for tumor and intracellular drug delivery in cancer therapy.

pH Sensitive surfactants from lysine: assessment of their cytotoxicity and environmental behavior

The toxicity and environmental behavior of new pH-sensitive surfactants from lysine are presented. Three different chemical structures are studied: surfactants with one amino acid and one alkyl chain, surfactants with two amino acids on the polar head and one alkyl chain, and gemini surfactants. The pH sensitivity of these compounds can be tuned by modifying their chemical structures. Cytotoxicity has been evaluated using erythrocytes and fibroblast cells. The toxic effects against these cells depend on the hydrophobicity of the molecules as well as their cationic charge density. The effect of hydrophobicity and cationic charge density on toxicity is different for each type of cells. For erythrocytes, the toxicity increases as hydrophobicity and charge density increases. Nevertheless, for fibroblasts cationic charge density affects cytotoxicity in the opposite way: the higher charge density, the lower the toxicity. The effect of the pH on hemolysis has been evaluated in detail. The aquatic toxicity was established using Daphnia magna. All surfactants yielded EC50 values considerably higher than that reported for cationic surfactants based on quaternary ammonium groups. Finally, their biodegradability was evaluated using the CO2 headspace test (ISO 14593). These lysine derivatives showed high levels of biodegradation under aerobic conditions and can be classified as"readily biodegradable compounds".

Spectrum of gluten sensitive enteropathy in first degree relatives of patients with coeliac disease: clinical relevance of lymphocytic enteritis.

Background: Limited data on a short series of patients suggest that lymphocytic enteritis (classically considered as latent coeliac disease) may produce symptoms of malabsorption, although the true prevalence of this situation is unknown. Serological markers of coeliac disease are of little diagnostic value in identifying these patients. Aims: To evaluate the usefulness of human leucocyte antigen-DQ2 genotyping followed by duodenal biopsy for the detection of gluten-sensitive enteropathy in first-degree relatives of patients with coeliac disease and to assess the clinical relevance of lymphocytic enteritis diagnosed with this screening strategy. Patients and methods: 221 first-degree relatives of 82 DQ2+ patients with coeliac disease were consecutively included. Duodenal biopsy (for histological examination and tissue transglutaminase antibody assay in culture supernatant) was carried out on all DQ2+ relatives. Clinical features, biochemical parameters and bone mineral density were recorded. Results: 130 relatives (58.8%) were DQ2+, showing the following histological stages: 64 (49.2%) Marsh 0; 32 (24.6%) Marsh I; 1 (0.8%) Marsh II; 13 (10.0%) Marsh III; 15.4% refused the biopsy. 49 relatives showed gluten sensitive enteropathy, 46 with histological abnormalities and 3 with Marsh 0 but positive tissue transglutaminase antibody in culture supernatant. Only 17 of 221 relatives had positive serological markers. Differences in the diagnostic yield between the proposed strategy and serology were significant (22.2% v 7.2%, p<0.001). Relatives with Marsh I and Marsh II¿III were more often symptomatic (56.3% and 53.8%, respectively) than relatives with normal mucosa (21.1%; p=0.002). Marsh I relatives had more severe abdominal pain (p=0.006), severe distension (p=0.047) and anaemia (p=0.038) than those with Marsh 0. The prevalence of abnormal bone mineral density was similar in relatives with Marsh I (37%) and Marsh III (44.4%). Conclusions: The high number of symptomatic patients with lymphocytic enteritis (Marsh I) supports the need for a strategy based on human leucocyte antigen-DQ2 genotyping followed by duodenal biopsy in relatives of patients with coeliac disease and modifies the current concept that villous atrophy is required to prescribe a gluten-free diet.

Qüestionari de percepció de recolzament social. Context comunitari, educatiu i familiar

Projecte de recerca (EDU2011-25960) Ministerio de Ciencia e Innovación.

Assessorar o dirigir. El paper de l'assessor col·laboratiu en una formació permanent centrada en el professorat i en el context

En el artículo se realiza un análisis del campo de la formación del profesorado y del modelo de formación permanente de los últimos tiempos, atendiendo los nuevos elementos que actuaron como fuerzas ocultas e impulsoras de un pensamiento formativo innovador. Se analizan también las condiciones para un cambio en la manera de ver la formación permanente del profesorado que, progresivamente, ha pasado de una visión de producto formativo que el profesorado debía asimilar acríticamente, a otra etapa con visiones diversificadas. A continuación, se profundiza la función asesora y los modelos que esta nueva concepción de la formación exigen. Se necesitan asesores, formadores que de manera colaborativa ayuden a reconstruir la práctica educativa.

Polítiques docents en el context de l'EEES: oportunitats, dificultats i dilemes

El procés de convergència cap a l'Espai Europeu d' Educació Superior ha fet que les universitats s'hagin plantejat el repte de millorar la docència. Que amb l'EEES es vulgui fomentar un nou model d'ensenyança, ha suscitat opinions divergents, però hagués estat irresponsable no aprofitar el procés de canvi per anar al fons del tema docent. En el context actual, cercar com millorar els processos d'aprenentatge dels i de les estudiants suposa la necessitat de reflexionar col·lectivament sobre què i sobre com s'ha d'ensenyar a la universitat. Per tal d'afavorir un canvi de model que dugui a focalitzar la mirada en el procés d'aprenentatge de l'estudiant, cal debatre sobre els dilemes que sorgeixen quan els requeriments del nou model xoquen amb la cultura tradicionalment predominant entre el professorat universitari. En l'article es comenten alguns d'aquests dilemes.

Activitat conjunta i influència educativa en el context familiar

Encara que actualment sembla llunyana una explicació integrada dels processos d'influència educativa en la família, han estat importants els progressos fets en els darrers anys sobre aquest tema (Lacasa, 1997; Rodrigo, 1998; Vila, 1998). En aquest article es presenten algunes reflexions sobre la família com a context educatiu. La concepció constructivista de l'ensenyament i l'aprenentatge escolar, marc psicològic de referència per a la comprensió dels processos de canvi educatiu que es produeixen en les situacions educatives escolars (Coll, 1990; 1999), s'utilitza com a punt de referència per a aquestes reflexions. Les característiques de la intervenció educativa en les activitats a la família es presenten a partir de la tesi nuclear que qualsevol aproximació a la comprensió de la influència educativa requereix tenir en compte les característiques, naturalesa i funcions del context institucional en què té lloc.

Rapid and sensitive hormonal profiling of complex plant samples by liquid chromatography coupled to electrospray ionization tandem mass spectrometry

Background Plant hormones play a pivotal role in several physiological processes during a plant's life cycle, from germination to senescence, and the determination of endogenous concentrations of hormones is essential to elucidate the role of a particular hormone in any physiological process. Availability of a sensitive and rapid method to quantify multiple classes of hormones simultaneously will greatly facilitate the investigation of signaling networks in controlling specific developmental pathways and physiological responses. Due to the presence of hormones at very low concentrations in plant tissues (10-9 M to 10-6 M) and their different chemistries, the development of a high-throughput and comprehensive method for the determination of hormones is challenging. Results The present work reports a rapid, specific and sensitive method using ultrahigh-performance liquid chromatography coupled to electrospray ionization tandem spectrometry (UPLC/ESI-MS/MS) to analyze quantitatively the major hormones found in plant tissues within six minutes, including auxins, cytokinins, gibberellins, abscisic acid, 1-amino-cyclopropane-1-carboxyic acid (the ethylene precursor), jasmonic acid and salicylic acid. Sample preparation, extraction procedures and UPLC-MS/MS conditions were optimized for the determination of all plant hormones and are summarized in a schematic extraction diagram for the analysis of small amounts of plant material without time-consuming additional steps such as purification, sample drying or re-suspension. Conclusions This new method is applicable to the analysis of dynamic changes in endogenous concentrations of hormones to study plant developmental processes or plant responses to biotic and abiotic stresses in complex tissues. An example is shown in which a hormone profiling is obtained from leaves of plants exposed to salt stress in the aromatic plant, Rosmarinus officinalis.

Risc i seguretat en el context educatiu: un debat necessari en el marc d'una educació orientada al desenvolupament de la ciutadania

En aquest article se profunditza en torna a les repercusions dels nous escenaris teòrics relacionats amb el desenvolupament del concepte de risc en la segona modernitat. Les tradicions d'anàlisi de la violència escolar o de la gestió positiva del conflicte, han constituït-del fet encara avui dia constitueixen- referents importants per a l'anàlisi de la seguretat en els centres educatius, però el desenvolupament d'un nou concepte de seguretat humana sorgit a partir dels Programes de les Nacions Unides pel Desenvolupament (PNUD) proporciona un marc de reflexió més ampli. Partint d'aquesta perspectiva, se pretèn operativitzar un model que permeti comprendre com es construeix la percepció de risc en el context escolar.

A comparison of mean phase difference and generalized least squares for analyzing single-case data

The present study focuses on single-case data analysis and specifically on two procedures for quantifying differences between baseline and treatment measurements The first technique tested is based on generalized least squares regression analysis and is compared to a proposed non-regression technique, which allows obtaining similar information. The comparison is carried out in the context of generated data representing a variety of patterns (i.e., independent measurements, different serial dependence underlying processes, constant or phase-specific autocorrelation and data variability, different types of trend, and slope and level change). The results suggest that the two techniques perform adequately for a wide range of conditions and researchers can use both of them with certain guarantees. The regression-based procedure offers more efficient estimates, whereas the proposed non-regression procedure is more sensitive to intervention effects. Considering current and previous findings, some tentative recommendations are offered to applied researchers in order to help choosing among the plurality of single-case data analysis techniques.

The influence of work context on demand for master's studies: a comparative analysisi between Brasil and Spain

The communication presents the results of an investigation of exploratory and comparative character which objective is to analyze the influence of the actual labour situation into the demand of official master studies in the field of education. The study has been developed in two countries with a very different labour situation: Brasil, country of economic expansion and Spain, in recession due to the actual economic crisis. In that sense, the study provides data for deep thinking about the influence of the constriction or expansion of employment on the behaviour and demand of the students who access master studies and on how the previous formative and labour trajectory affects their expectations, demands and future projects. The working methodology is qualitative and the strategy for data collection the “focus group”. As a first approach, two groups of discussion have been formed with master students. A first one with students from Universidad de Barcelona- España and another one with members of Universidade do Vale do Itajaí- Brasil. Then, we constituted a mixed group of discussion in order to analyze differences and similarities.

El professorat d'Educació Física a l'escola multicultural. Percepcions del context i necessitats de formació

El present article se centra en la situació del professorat d'Educació Física i les seves necessitats formatives per actuar adequadament en entorns d'escola multicultural. Amb aquesta finalitat es presenta la importància de l'educació física com a agent socialitzador per a l'alumnat immigrant, les diferents tendències de les investigacions específiques sobre formació del professorat d'Educació Física en temes d'immigració, i les dades obtingudes a través d'una investigació específica realitzada amb una mostra de 230 centres escolars de tot Catalunya. Com a aspectes més remarcables, cal assenyalar que encara que l'educació física i l'esport poden representar un espai de trobada molt valuós per a la interculturalitat, és important no deixar de banda una educació orientada cap a la convivència, i que la formació del professorat sigui coherent amb les necessitats reals que s'observen en i des dels centres escolars.

The influence of work context on demand for master's studies: a comparative analysisi between Brasil and Spain

The communication presents the results of an investigation of exploratory and comparative character which objective is to analyze the influence of the actual labour situation into the demand of official master studies in the field of education. The study has been developed in two countries with a very different labour situation: Brasil, country of economic expansion and Spain, in recession due to the actual economic crisis. In that sense, the study provides data for deep thinking about the influence of the constriction or expansion of employment on the behaviour and demand of the students who access master studies and on how the previous formative and labour trajectory affects their expectations, demands and future projects. The working methodology is qualitative and the strategy for data collection the “focus group”. As a first approach, two groups of discussion have been formed with master students. A first one with students from Universidad de Barcelona- España and another one with members of Universidade do Vale do Itajaí- Brasil. Then, we constituted a mixed group of discussion in order to analyze differences and similarities.

Qüestionari de percepció de recolzament social. Context comunitari, educatiu i familiar

Projecte de recerca (EDU2011-25960) Ministerio de Ciencia e Innovación.