Search results for "exclusion"

Relevant factors for the eco-design of polylactide/sisal biocomposites to control biodegradation in soil in an end-of-life scenario

2017

[EN] The eco-design considers the factors to prepare biocomposites under an end-of-life scenario. PLA/sisal biocomposites were obtained from amorphous polylactide and sisal loadings of 10, 20 and 30 wt% with and without coupling agent, and subjected to biodegradation in soil according to standard IS0846. Mass loss, differential scanning calorimetry and size-exclusion chromatography were used for monitoring biodegradation. A statistical factorial analysis based on the molar mass M-n, and crystallinity degree X-c pointed out the relevance and interaction of amount of fibre and use of coupling agent with the time of burial in soil., During the preparation of biocomposites, chain scission provo…

Evaluation of a Multidimensional Solid-Phase Extraction Platform for Highly Selective On-Line Cleanup and High-Throughput LC−MS Analysis of Triazines…

2001

A novel highly selective sample cleanup procedure based on the use of molecularly imprinted polymers (MIPs) as solid-phase extraction materials has been evaluated with respect to its applicability and routine use in environmental analysis. The method comprises the combination of a restricted access material (RAM) and a MIP allowing a selective sample preparation to be achieved in the online mode. This combination is called the size-selective sample separation and solvent switch (six-SPE). The RAM column combines size exclusion and adsorption chromatography, reducing the concentration of matrix molecules by a cutoff of 15 kDa. The MIP column selectively retains the triazine analytes whereas …

Invisalign treatment from the patient perspective: A Twitter content analyses

2021

Background: Understanding patient perspective is a key factor in improving treatment satisfaction. The aim of the present study is to qualitatively describe the content of Twitter posts related to the treatment with Invisalign in order to get a better understanding of patient experience. Material and Methods: Tweets were prospectively collected during a period of four weeks from public available posts on Twitter using Awario™ a bespoke social media monitoring tool. After applying the pertinent inclusion and exclusion criteria the selected posts were analysed by three investigators using thematic analysis. Specific themes and subthemes were developed. Results: A total of 1564 tweets were ana…

Hacia la transformación de la escuela. Valoración de un programa de convivencia a partir de la voz del alumnado y del profesorado

2016

<p class="AbstractText">Learning to coexist continues to be one of the challenges faced by the current educational system, especially for those schools located in contexts at risk of social exclusion where the violence rate increases on a daily basis. The main aim sought by the present study consists in assessing the impact of a program developed at an educational center located in a vulnerable neighborhood of the city of Valencia (Spain). It is a quasi-experimental, pretest-posttest research with a control group that involved a total of 109 teachers and students. It deserves to be highlighted that this paper forms part of a broader research initiative, for which reason the results ob…

Structural Investigations: Heavy Metal and Halogen Interactions with Fractions of Refractory Organic Substances Separated by Size-exclusion Chromatog…

2007

Design, Implementation and Students' Emotional Assessment of a Software for the Learning of Rational Numbers through Music Metaphors in Chilean Prima…

2019

Using sound and music as a metaphor to approach curricular mathematical contents in Primary Education seems an interesting field that deserves some research. Both music and sound can synergically act as scaffolding for learning, intervening as part of situated knowledge, and they could offer a new perspective for learning mathematics at schools, giving pupils opportunities to develop their own mental representations. Also, the incorporation of an affective/emotional analysis, as criteria for evaluation, seems pertinent and complementary to other criteria in the production of multimedia material with educational purposes both in formal and non-formal domains of education. These are the inten…

On the molecular structure of human neuroserpin polymers

2012

The polymerization of serpins is at the root of a large class of diseases; the molecular structure of serpin polymers has been recently debated. In this work, we study the polymerization kinetics of human neuroserpin by Fourier Transform Infra Red spectroscopy and by time-lapse Size Exclusion Chromatography. First, we show that two distinct neuroserpin polymers, formed at 45 and 85°C, display the same isosbestic points in the Amide I' band, and therefore share common secondary structure features. We also find a concentration independent polymerization rate at 45°C suggesting that the polymerization rate-limiting step is the formation of an activated monomeric species. The polymer structures…

Structure, interdomain dynamics, and pH-dependent autoactivation of pro-rhodesain, the main lysosomal cysteine protease from African trypanosomes

2021

AbstractRhodesain is the lysosomal cathepsin L-like cysteine protease ofT. brucei rhodesiense, the causative agent of Human African Trypanosomiasis. The enzyme is essential for the proliferation and pathogenicity of the parasite as well as its ability to overcome the blood-brain barrier of the host. Lysosomal cathepsins are expressed as zymogens with an inactivating pro-domain that is cleaved under acidic conditions. A structure of the uncleaved maturation intermediate from a trypanosomal cathepsin L-like protease is currently not available. We thus established the heterologous expression ofT. brucei rhodesiensepro-rhodesain inE. coliand determined its crystal structure. The trypanosomal pr…

Molecular characterization of α,β-poly[( N -hydroxyethyl)- dl –aspartamide] by light scattering and viscometry studies

2000

Abstract α,β-poly[(N-hydroxyethyl)- dl -aspartamide] (PHEA) is a new synthetic polymer which is of interest in biomedical applications. In this paper, the molecular characterization of PHEA by multi-angle laser light scattering and viscometry off-line and on-line to a size exclusion chromatography system is reported. These techniques furnish an exhaustive and consistent characterization of the PHEA polymer. The fractionation of the PHEA macromolecules was relatively simple. Using an aqueous mobile phase of medium ionic strength, the elution was substantially regular and the macromolecules were not aggregate. The molar mass M of four PHEA samples approximately ranges from 46 to 53 K g/mol, t…

Size-Exclusion Chromatographic Determination of Polymer Molar Mass Averages Using a Fractal Calibration

2005

The characterization of polymers by size-exclusion chromatography basically consists of the determination of the weight-average molar mass (Mw), number-average molar mass (Mn), and polydispersity index (I). An accurate estimation of these magnitudes requires the use of a reliable and trusted calibration curve. Three procedures for building up a calibration curve are analyzed in this work. The first is the classical universal calibration (UC), based on the elution of tetrahydrofuran-polystyrene in a system as reference. The second is based on the proper calibration curve made with standards of the sample under study. However, two main drawbacks arise when using these methodologies: the nonfu…