Compatibility of polysaccharide/maleic copolymer blends. IV. Thermal behavior of hydroxypropyl cellulose‐containing blends

The compatibility of the hydroxypropyl cellulose (HPC) with maleic acid–vinyl acetate copolymer in the solid state was studied by thermogravimetry, thermo‐optical analysis, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and optical microscopy. It was established that physical interactions are prevalent in blends with a high content of HPC, whereas chemical interactions predominate in blends with a medium and low content of HPC. By increasing the temperature, the thermochemical reactions are favored. Thermal properties are dependent on the mixing ratio of the components. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2585–2597, 2003     

Effect of iron on the setting properties of α-TCP bone cements

New ceramic materials with the ability to set like cement, after mixing a powder phase made of one and/or several of these new reactants and a liquid phase, have been obtained within the ternary system “CaO-P₂O₅-FeO”. These new reactants have magnetic properties, i.e. cement made from them maintains its magnetic property during the whole setting and hardening. These new materials can be of use, for example, in dental applications, in the treatment of certain types of bone cancer and, in general, in the fields of Biomaterials and Bone Tissue Engineering. In this article, we report on the effect of iron-modified α -tricalcium phosphate, which is the main reactant of commercial calcium phosphate bone cements, on their new setting and hardening properties.     

The long road from performing word sense disambiguation to successfully using it in information retrieval: An overview of the unsupervised approach

The issue of whether or not word sense disambiguation (WSD) can improve information retrieval (IR) results has been intensely debated over the years, with many inconclusive or contradictory results and a majority of skeptical opinions. All three classes of WSD methods (supervised, unsupervised, and knowledge-based) have been considered by the literature with respect to IR. We hereby survey the unsupervised approach which, although relatively rarely used, has provided positive results at a large scale. Unsupervised WSD has already made proof of its utility in IR and it is our belief that it still holds a promise for this field. The two main existing types of unsupervised methods for IR, which are of completely different natures, are presented, within the scientific context in which they were born, and are compared. Regardless of the gap in time between these central approaches, we are of the opinion that the unsupervised solution to the discussed problem remains the most significant for IR applications. By surveying what we consider the most promising existing approach to usage of WSD in IR, and by discussing its possible extensions, we hope to stimulate continuation of this line of research, possibly at an even more successful level.     

Low density polyethylene composites containing cellulose pulp fibers

Unbleached and bleached Kraft cellulose pulp fibers modified with a long chain carboxylic acid, i.e. oleic acid in cold plasma conditions have been used as reinforcements in low density polyethylene (LDPE). The purpose of the modification is to enhance the interfacial adhesion between cellulose and matrix and to increase the dispersability. Composites containing up to 10 wt.% of untreated and modified cellulose pulp fibers with LDPE were prepared by melt mixing. The samples were characterized by processing behavior, mechanical and rheological properties, SEM, contact angle measurements, TGA and DSC. It was found that when the modified pulp fibers were incorporated into composites matrix, most of the properties have been improved.     

Performing word sense disambiguation at the border between unsupervised and knowledge-based techniques

This paper aims to fully present a new word sense disambiguation method that has been introduced in Hristea and Popescu (Fundam Inform 91(3–4):547–562, 2009) and so far tested in the case of adjectives (Hristea and Popescu in Fundam Inform 91(3–4):547–562, 2009) and verbs (Hristea in Int Rev Comput Softw 4(1):58–67, 2009). We hereby extend the method to the case of nouns and draw conclusions regarding its performance with respect to all these parts of speech. The method lies at the border between unsupervised and knowledge-based techniques. It performs unsupervised word sense disambiguation based on an underlying Naïve Bayes model, while using WordNet as knowledge source for feature selection. The performance of the method is compared to that of previous approaches that rely on completely different feature sets. Test results for all involved parts of speech show that feature selection using a knowledge source of type WordNet is more effective in disambiguation than local type features (like part-of-speech tags) are.     

State of the art versus classical clustering for unsupervised word sense disambiguation

This paper ultimately discusses the importance of the clustering method used in unsupervised word sense disambiguation. It illustrates the fact that a powerful clustering technique can make up for lack of external knowledge of all types. It argues that feature selection does not always improve disambiguation results, especially when using an advanced, state of the art method, hereby exemplified by spectral clustering. Disambiguation results obtained when using spectral clustering in the case of the main parts of speech (nouns, adjectives, verbs) are compared to those of the classical clustering method given by the Naïve Bayes model. In the case of unsupervised word sense disambiguation with an underlying Naïve Bayes model feature selection performed in two completely different ways is surveyed. The type of feature selection providing the best results (WordNet-based feature selection) is equally being used in the case of spectral clustering. The conclusion is that spectral clustering without feature selection (but using its own feature weighting) produces superior disambiguation results in the case of all parts of speech.     

Investigation of Poly(vinyl alcohol)/Pluronic F127 Physical Gels

The application of Pluronic F127 as injectable gel-forming solution is limited by poor mechanical properties. The purpose of this study was to develop low viscosity formulations at ambient temperature that undergo a transition to gel under physiological conditions. Mixtures of Pluronic F127 and poly(vinyl alcohol) with different compositions were prepared in aqueous solutions and their in-situ gelation was investigated by dynamic light scattering and rheology. The results obtained for different formulations showed synergistic effects of polymer mixtures in aqueous media and their properties can be tuned by varying polymer concentration, system composition or changing temperature.     

Partial demineralization of maple sap by electrodialysis: impact on syrup sensory and physicochemical characteristics

In this project, samples of osmosed maple saps were demineralized to 12.5 and 25% levels by electrodialysis (ED). The effect of this treatment on the composition and the physicochemical and sensory properties of maple syrups obtained from demineralized maple sap was evaluated. The ED technology was efficient to decrease levels of malic acid and calcium in osmosed maple saps. Effectively, 38% and 24% decreases in malic acid and calcium respectively were reached for ED with a demineralization level of 25% without any changes in the other measured components of osmosed maple saps. The demineralization process had no effect on the yield of syrups produced and on their characteristics: no significant difference was observed during sensory analysis and viscosity. Moreover, the percentage of light transmission of syrups produced from demineralized osmosed saps was higher than for the control. This work suggests that ED could be a potential technology to decrease or avoid sugar sand formation during maple syrup production. Copyright © 2007 Society of Chemical Industry     

Perturbed Angular Correlations Studies in the HgBa<Subscript>2</Subscript>CaCu<Subscript>2</Subscript>O<Subscript>6+<Emphasis Type="Italic">δ</Emphasis></Subscript> high-T<Subscript><Emphasis Type="Italic">C</Emphasis></Subscript> Superconductor

The electric field gradients at ^199mHg nuclei have been measured via the perturbed angular correlation (PAC) technique, allowing a full characterization of the Hg neighborhood charge distribution at high oxygen doping on the Hg planes. The PAC technique has been applied to investigate the effect of high oxygen pressure during the measurement. Polycrystalline HgBa₂CaCu₂O_6+δ (Hg-1212) samples have been annealed at 152 bar pressurized oxygen. The influence of oxygen pressure during the experiment was then investigated by measuring the samples at atmospheric pressure and under 152 bar oxygen pressure.     

Synthesis and characterization of polyvinyl alcohol/cellulose cryogels and their testing as carriers for a bioactive component

Novel physically cross-linked cryogels containing polyvinyl alcohol (PVA) and various amounts of microcrystalline cellulose were obtained by freezing/thawing technique. The main goal of this study was to improve the properties and the performances of the pure PVA cryogels. The morphological aspects of the cryogels were studied by scanning electron microscopy (SEM). The Fourier transform infrared spectroscopy (FT-IR) was used to reveal the presence of the interactions between the two polymers. Changes in crystallinity of the samples were confirmed by X-ray diffraction (XRD) and by FT-IR spectroscopy. The modification of the thermal behavior induced by cellulose was studied by thermogravimetry. Rheological analysis revealed higher values of storage modulus (G′) for the cryogels containing higher amounts of cellulose. The degree and rate of swelling were controlled by the presence of the natural polymer in the network. The potential application as bioactive compound carriers was tested, using vanillin as an active agent.