Integrating supercomputing clusters into education: a case study in biotechnology

The Journal of Supercomputing - The integration of a Supercomputer in the educational process improves student’s technological skills. The aim of the paper is to study the interaction between...     

Pessimists and optimists: Improving collaborative filtering through sentiment analysis

This work presents a novel application of Sentiment Analysis in Recommender Systems by categorizing users according to the average polarity of their comments. These categories are used as attributes in Collaborative Filtering algorithms. To test this solution a new corpus of opinions on movies obtained from the Internet Movie Database (IMDb) has been generated, so both ratings and comments are available. The experiments stress the informative value of comments. By applying Sentiment Analysis approaches some Collaborative Filtering algorithms can be improved in rating prediction tasks. The results indicate that we obtain a more reliable prediction considering only the opinion text (RMSE of 1.868), than when apply similarities over the entire user community (RMSE of 2.134) and sentiment analysis can be advantageous to recommender systems.     

Lipolytic Enzyme Production by Immobilized Rhizopus oryzae

In this paper, a suitable technique as well as an adequate material for the immobilization of the fungus Rhizopus oryzae were investigated. This organism has been shown to have potential in the field of food aroma due to the production of extracellular lipolytic enzymes. However, an efficient production system at bioreactor scale for its application to the flavor compounds production is still needed. Among the supports studied, alginate beads were the best carrier materials, leading to the highest lipolytic activities of up to 400 U/L after 3 days of cultivation. Repeated batch cultures were carried out to improve cell concentration and lipolytic activity. The gel beads produced lipolytic enzyme under optimized conditions for consecutive batch fermentations without marked activity loss and deformation attained a maximum level of 715 U/L after three batches. The production of lipolytic enzyme by immobilized Rhizopus oryzae in a 2‐litre airlift bioreactor with the optimized conditions was evaluated. Lipolytic activities of 487 U/L were attained, operating in successive batches without operational problems and the bioparticles (the fungus grows in alginate beads) maintained their shape throughout fermentation.     

Preparation of stearidonic acid‐enriched triacylglycerols from Echium plantagineum seed oil

HPLC analysis of Echium plantagineum seed oil shows a complex triacylglycerol (TAG) profile. TAG species were separated on an analytical scale by HPLC and their fatty acid (FA) composition is reported. GLC analyses showed that some TAG fractions reached a stearidonic acid (SDA, 18:4n‐3) percentage significantly higher than that in the original oil. TAG separation on a bigger scale was also essayed, by means of a gravimetric normal‐phase chromatographic column, using silver ion‐silica gel as stationary phase. Gradient elution with solvents of increasing polarity was applied, allowing the separation of valuable TAG species containing γ‐linolenic acid (GLA, 18:3n‐6), α‐linolenic acid (ALA, 18:3n‐3) and SDA as the main constituents (more than 85% of the total FA). An enzymatic hydrolysis reaction showed the distribution of FA in the isolated species of TAG. SDA was the major FA in the sn‐2 position (more than 50% of total FA), followed by ALA (19%) and GLA (18.5%).     

Technological innovation and regional economic growth in Mexico: a spatial perspective

The aim of this investigation is to analyze the effect of technological innovation on Mexico’s regional economic growth during 1995–2007. It is argued that the inclusion of the spatial dimension in empirical analysis is still a rare practice in Mexico and even in international studies. Such inclusion allows studying the pattern of spatial interaction, the possible effects of spatial diffusion and the estimation of robust parameters. We apply the spatial data analysis methodology that has three components: (a) exploratory analysis, (b) visualization and (c) spatial econometric modeling. The main result suggests that technological innovation has a positive effect on Mexico’s regional economic growth. The empirical evidence also suggests that there is a positive effect coming from cross-border diffusion effects of technological knowledge. It also implies that states with stronger innovation activity benefited from spatial technological externalities and hence faster economic growth.     

The relationship between the corrosion resistance and impurity content of aluminium oxide layers

In the last few years there has been an increased production and application of aluminium foil of under 20 μm thickness all over the world. Household foil is often stored in a wet environment, where the surface is only protected against corrosion by an aluminium oxide layer produced during manufacturing. In this study it has been shown that the aluminium-water vapour reaction is greatly affected by the composition and structure of the amorphous oxide layer on the surface and this depends on the composition of base metal and on the annealing of the foil. The incubation period of aluminium hydroxide nucleation is shortened and its growth rate accelerated by alkali and alkaline earth metal cations incorporated in the oxide layer. In particular the corrosion resistance is decreased by the presence of alkali (Li) and alkaline earth metal (Mg) cations in the oxide layers.     

The influence of some alloying additions (Cr,Cu and Li) on the thermal oxidation of AlZnMg alloys

The influence of some alloying additions (Cr, Cu and Li) on the thermal oxidation of AlZnMg alloy was clarified by means of various techniques (in situ HVEM, electron diffraction, X-ray diffraction, SEM, SIMS and AES). It was found that due to the Zn content, the oxidation of the Mg content of the alloy is inhibited at low temperatures (673 K) but is enhanced at higher temperatures (> 723 K). At low temperature in the presence of Zn the oxidation is only slightly influenced by Cr addition whereas it is remarkably decreased by Cu addition. At higher temperatures Cu impede by a great extent magnesium oxide formation. The oxidation is highly accelerated by Li at both low and high temperatures, respectively. During the formation of primary lithium oxide crystals the segregation and oxidation at the air-amorphous oxide boundary is also promoted. The effect of the additives is closely related to their diffusion in both the metal and the amorphous oxide, and their influence on the oxygen diffusion towards the metal.