Ontologies versus relational databases: are they so different? A comparison

Two main data models are currently used for representing knowledge and information in computer systems. Database models, especially relational databases, have been the leader in last few decades, enabling information to be efficiently stored and queried. On the other hand, ontologies have appeared as an alternative to databases in applications that require a more ‘enriched’ meaning. However, there is controversy regarding the best information modeling technique, as both models present similar characteristics. In this paper, we present a review of how ontologies and databases are related, of what their main differences are and of the mechanisms used to communicate with each other.     

Production of fungal lipases using wheat bran and soybean bran and incorporation of sugarcane bagasse as a co-substrate in solid-state fermentation

Fungal strains were screened for lipase producing activities and 10 strains were classified as good producers. Aspergillus sp., Fusarium sp., and Penicillium sp. exhibited the highest activities when fermented in wheat bran (WB) and soybean bran (SB). No fungal growth was observed using sugarcane bagasse (CB). An experimental design was applied to incorporate CB into the fermentation process for lipase production by Aspergillus sp. and Penicillium sp., and to evaluate the best moisture content for the substrate. Strains studied achieved maximum lipase activities with 25% CB combined with 75% WB or SB at 40% moisture content. The highest lipase activities were observed for WB and SB, and for SB combined with CB using Aspergillus sp. Fermentation of 96 h was the optimum period for enzyme production.     

Calcium dosing for the simultaneous control of biomass retention and the enhancement of fermentative biohydrogen production in an innovative fixed-film bioreactor

Biohydrogen (bioH₂) production via dark fermentation is an attractive approach to overcome the drawbacks of conventional hydrogen production methods and represents a preliminary alternative for the management of organic wastes. Fundamental studies are still required to enhance the performance of bioH₂ production systems, with emphasis on the development of novel reactor configurations. The anaerobic structured-bed reactor (ASTBR) is a recently developed configuration with great potential for bioH₂ production, although operating strategies are still required to minimize biomass washout in such systems. In this context, calcium dosing has been investigated as a strategy to enhance both biomass retention and bioH₂ production rates in the ASTBR. The present study employed varying COD/calcium ratios (4423, 2079, 1357, 1012, 884, and 632) in continuous experiments under mesophilic conditions (25 °C). Calcium dosing effectively enhanced biomass retention within the ASTBR, directly increasing the availability of metabolic energy for different metabolic pathways rather than cell synthesis. An optimal COD/calcium ratio of 1360 was mathematically estimated for bioH₂ production, which is consistent with the results obtained experimentally. The specific organic loading rate (SOLR) was better controlled at this ratio, indicating the establishment of balanced conditions in terms of substrate availability and biomass concentration. Conversely, bioH₂ production was severely impaired at COD/calcium values below and above the optimal range, most likely due to enhancement of the homoacetogenic pathway as a result of unbalanced conditions in the SOLR. Furthermore, biomass accumulation did not strongly affect the mean residence time of the ASTBR, facilitating its robust and enhanced solid retention.     

Chain flexibility versus molecular entanglement response to rubbing deformation in designing poly(oxadiazole-naphthylimide)s as liquid crystal orientation layers

Four poly(oxadiazole-imide)s containing naphthalene rings, with different flexibility and molecular weight, are investigated with respect to their rheological properties to establish the optimal processing conditions from solution phase to film state for liquid crystal orientation purposes. The film uniformity and strength are determined by monitoring the flow behavior and chain entanglements. The solution rheological data are in agreement with film tensile testing, revealing that higher molecular weight favors chain entanglements and implicitly the film mechanical resistance. In order to analyze the suitability of these films as alignment layers their surface is patterned by rubbing with two types of velvet. Liquid crystal alignment of 4′-pentyl-4-biphenylcarbonitrile nematic is tested by polarized light microscopy. The resulting behavior is correlated with the polyimide malleability and characteristics of the textile fibers, namely their polarity, size, and mechanical features. The competitive effects between chain flexibility and entanglements, together with the interactions occurring between the polymer and velvet are analyzed in order to explain the surface regularity, which influences the uniformity of the liquid crystal alignment. The contrast between dark and bright states recorded on the liquid crystal cell indicates that some of these polynaphthalimides are promising candidates for liquid crystal display devices.     

Ethanol reforming and partial oxidation with Cu/Nb2O5 catalyst

Ethanol reforming and partial oxidation were studied on Cu/Nb₂O₅ and Ni/Al₂O₃ catalysts. Compared to the Ni/Al₂O₃ catalyst, the Cu/Nb₂O₅ catalyst presents conversion as high as Ni/Al₂O₃ catalyst, however, for the same level of formation of hydrogen it occurs at much lower temperature on the Cu/Nb₂O₅ catalyst, 200 °C lower than for the Ni/Al₂O₃ catalyst, with remarkable little formation of CO, which can be attributed to the strong interaction between copper and niobia. Temperature-programmed desorption (TPD-ethanol) and surface reactions (TPSR) of partial oxidation of ethanol showed formation of ethylene, acetaldehyde, ethane and mainly H₂ and CO₂ besides little methane. DRIFTS results are in accordance with TPD analysis and the formation of acetate species at room temperature suggests reactivity of the surface and its oxidative dehydrogenation capacity. The adsorption of ethanol gives rise to ethoxide species, which form acetate and acetaldehyde that can be oxidized to CO₂ via carbonate. A comparison with reported results for Cu/Al₂O₃ this catalyst is promising, yielding high level of H₂ with little CO production during reforming and partial oxidation reaction. The maximum H₂ formation for the partial oxidation of ethanol was 41% at ratio (O₂/Et) 0.8, increasing to 50% at ratio 1.5. The H₂/CO is around 10 for the partial oxidation and 7 for steam reforming, which is excellent, compared to the Ni/Al₂O₃ catalyst with a factor 4–8 lower.     

Biocompatibility and cutaneous reactivity of cellulosic polysaccharide film in induced skin wounds in rats

The development of a skin substitute suitable for immediately performing the function of the lost dermis and epidermis could result in a positive impact on the treatment of patients with extensive skin lesions. A biopolymer film was applied to skin wounds to investigate the biocompatibility and cutaneous reaction and to test its activity as a mechanical barrier and conductor in the healing process. Forty Wistar rats of both sexes were used in the present study. Two excisions were performed in the dorsal part of the skin flaps. The polysaccharide film was applied over one of the incisions and other incision was washed with saline. The time spent for complete healing of both lesions was virtually the same in both groups, during 21 days of observation. The film remained attached to the bed of the exposed wound for an average period of 6 days. There were no statistically significant differences with regard to lesion measurement area at assessment times of 2nd, 7th and 14th postoperative days. At day 21, the scar area showed a significant difference (0.0229). After 40 days, all wounds were completely healed. No statistically significant differences were found between the histological parameters assessed in the experimental and control groups. The cellulosic polysaccharide film integrated well with the tissue showing high biocompatibility and low skin reactivity.     

Removal of heavy metals from wastewater using magnetic nanocomposites: Analysis of the experimental conditions

This contribution provides insight on the elimination of heavy metals from water resources using magnetic separation. Nanocomposites based on magnetite and chitosan were prepared. An exhaustive characterization of the magnetic adsorbents was developed. Adsorption assays were performed in batch using Cu, Zn, Cd, and Cr as model heavy metals. The efficiency of magnetic adsorbents followed the order: Cu > Cd > Zn > Cr, with maximum values of 188, 159, 72, and 46 mg of Me/g of nanocomposite, respectively. Kinetics and mechanistic issues were studied. The magnetic materials were efficient for five to eight cycles using Cu(II),Cd(II), and Cr(VI).