Effect of mass transfer on biodesulfurization kinetics of alkylated forms of dibenzothiophene by Pseudomonas putida CECT5279

BACKGROUND: An important problem exists for the implementation of biodesulfurization technology of fuels related to the influence of mass transfer on the overall reaction rate and process yield. Pseudomonas putida CECT5279 has been shown to be one of the most promising biocatalysts, but most kinetic studies were done at small scale and their capability for the transformation of alkyl substituted forms (Cx–DBTs) has not yet been reported. RESULTS: Conversion yields and kinetic parameters were calculated under aqueous and biphasic resting cell conditions in a 2 L stirred tank reactor. In aqueous reaction media, 100% conversion of DBT, 4MDBT and 4,6DMDBT was achieved while the conversions in the presence of an organic liquid were 38% for DBT, 19.5% for 4MDBT and 16.5% for 4,6DMDBT, showing that the process is strongly affected by mass transfer between liquids. Laboratory scale–up of P. putida CECT5279 growing step was successfully carried out using a 15 L stirred tank, on the basis of the volumetric mass transfer coefficient (k_La). CONCLUSIONS: P. putida CECT5279 is capable of removing Cx–DBT compounds successfully in aqueous resting cell conditions using stirred tank reactors, but in biphasic media, mass transfer between liquids controls the process, increasing time of reaction and lowering process yield. © 2012 Society of Chemical Industry     

Characterization and reactivity of aerogel sulfated zirconia-ceria catalyst for n-hexane isomerization

Sulfated zirconia doped with cerium has been prepared by sol gel process using the supercritical evacuation way of the solvent. The physicochemical and catalytic properties of aerogel solids AZC were compared as a function of both the Ce/Zr molar ratio and the calcination temperature. The samples were characterized by N₂ adsorption desorption, XRD, FTIR, RAMAN, XPS spectroscopy and TPD of NH₃. The catalyst prepared with molar ratio Ce/Zr = 0.4 exhibits the high activity and selectivity toward isomerization product in the n-hexane isomerization reaction. This result is probably due to its important total acidity.     

Chemical Scarification and Ozone in Seed Dormancy Alleviation of Wild and Domesticated Opuntia,Cactaceae

Protocols for seed germination in the Opuntia genus are different and unsuitable for all their species. Dormancy of Opuntia seeds can be modified by the combination of scarification and an oxidizing agent such as O₃, which could induce antioxidant and DNA-repair mechanisms or dormancy-breaking effects in hydrated seeds. The objective of this study was to evaluate the effects that the combination of mechanical and chemical scarification with exposition to sub-lethal O₃ doses have on seed germination and seedling growth of O. streptacantha Lem., O. megacantha Salm-Dyck, and O. ficus-indica (L.) Mill. Our hypothesis was that O₃ favors germination on scarified seeds and that the magnitude of the effect is species-dependent. Water uptake and germination were quantified in seeds every 48 h, until their roots reached a 5-mm length. The results were analyzed with an analysis of variance and multiple means comparisons with the Tukey test. Accelerated water uptake was observed during the first 48 h; the maximum average was 33.5% in all species. The combination of acid scarification and imbibition in the presence of O₃ increased (P ≤ 0. 05) germination (between 17.8 and 44.4%), mainly in O. streptacantha. O₃ increased germination, regardless of the species. O₃ can be used in sublethal doses to increase seed germination and seedling development in Opuntia genus.     

Biological tolerance of different materials in bulk and nanoparticulate form in a rat model: sarcoma development by nanoparticles.

In order to study the pathobiological impact of the nanometre-scale of materials, we evaluated the effects of five different materials as nanoparticulate biomaterials in comparison with bulk samples in contact with living tissues. Five groups out of 10 rats were implanted bilaterally for up to 12 months with materials of the same type, namely TiO2, SiO2, Ni, Co and polyvinyl chloride (PVC), subcutaneously with bulk material on one side of the vertebral column and intramuscularly with nanoparticulate material on the contralateral side. At the end of each implantation time, the site was macroscopically examined, followed by histological processing according to standard techniques. Malignant mesenchymal tumours (pleomorphic sarcomas) were obtained in five out of six cases of implanted Co nanoparticle sites, while a preneoplastic lesion was observed in an animal implanted with Co in bulk form. In the Ni group, all animals rapidly developed visible nodules at the implanted sites between 4 and 6 months, which were diagnosed as rhabdomyosarcomas. Since the ratio of surface area to volume did not show significant differences between the Ni/Co group and the TiO2/SiO2/PVC group, we suggested that the induction of neoplasia was not mediated by physical effects, but was mediated by the well-known carcinogenic impact of Ni and Co. The data from the Co group show that the physical properties (particulate versus bulk form) could have a significant influence on the acceleration of the neoplastic process.     

Mineralogy and Microstructure of Hydrated Phases During the Pozzolanic Reaction in the Sanitary Ware Waste/Ca(OH)2 System

Despite technological improvements in its production process, the sanitary ware industry inevitably generates a certain volume of discards, products whose quality is not up to standard. The present paper is the first to scientifically explore clay‐based sanitary ware waste (SW) with a view to its valorization as an addition in the design of new, more environmentally friendly cements. The focus is on characterization of the waste and its pozzolanicity, as well as the structural and microstructural changes taking place in the pozzolan/Ca(OH)₂ system in the first 90 d of reaction. The findings show that pozzolanicity in clay‐based waste is comparable to the activity observed in silica fume (SF) and higher than that found in other clay‐based materials and fly ash (FA). The microstructural study of the clay‐based waste/Ca(OH)₂ system, in turn, reveals that the proportion of C–S–H gels rises with hydration time. These gels are characterized by long mean chain lengths (MCL) and low Ca/Si ratios. The intrinsic characteristics of this thermally activated clay‐based waste qualify it as a type Q pozzolans as defined in the European cement standards, making it apt for use in the manufacture of CEM II, IV, and V cements.     

A Transfformation Grammar for Housing Rehabilitation

Existing housing stock must be rehabilitated to meet the new needs of dwellers in the current information society. Consequently, Information and Communications and Automation Technologies (ICAT) must be integrated in living areas. Both shape grammar and space syntax can be used as tools to identify and encode the principles and rules behind the adaptation of existing houses to new requirements. The research proceeds by first identifying the dwellers’ demands and determine how the use of technology influences them. The second step is to identify the functional, spatial, and constructive transformations performed manually by human designers in order to infer the corresponding transformation rules and encode them into a grammar. The third step aims to test the grammar in other dwellings that are part of the corpus of the study.     

Numerical analysis of sand/solids production in boreholes considering fluid-mechanical coupling in a Cosserat continuum

Sand/solids production is a serious problem faced by the petroleum industry during production stages. Particles/groups of particles of the formation rock are produced together with pumped oil or gas causing highly damaging effects on pipes and valves. This phenomena can be caused by several factors including the stresses developed around the boreholes/perforations and fluid flow, which break and erode the rock, respectively. Numerical simulation of sand/solids production presents a considerable challenge as intricacies of failure processes must be correctly simulated. This paper presents a finite element based procedure for simulating the process of sand/solids production, considering fluid-mechanical coupling in an elasto-plastic Cosserat continuum. It is believed that the enhanced deformation modes included into Cosserat continua may contribute for proper modeling of the deformational behavior and failure modes of the cemented/non-cemented granular materials involved. Bogdanova-Bontcheva and Lippmann's constitutive model was implemented in order to model the granular materials involved. Finally, the work presents the analysis of sand/solids production in a hypothetical borehole. For comparison purposes, different characteristic lengths of the material are adopted and analysis is also performed using standard continua.     

Effect of Dietary Stilbenes on 5-Lipoxygenase and Cyclooxygenases Activities In Vitro

Stilbenes contained in various foods are associated with health beneficial effects. In this study six natural and one synthetic stilbene were tested for their potential to regulate the activity of lipoxygenase and cyclooxygenase in vitro. The most potent inhibitor of 5-lipoxygenase was pterostilbene (IC₅₀ = 9.32 μM), whereas the strongest inhibitor of cyclooxygenase-1 and cyclooxygenase-2 was pinostilbene (IC_50s = 1.90 and 0.35 μM, respectively). Pterostilbene (IC_50s = 11.70 and 27.04 μM for cyclooxygenase-1 and cyclooxygenase-2, respectively) and oxyresveratrol (IC_50s = 18.49; 2.79 and 14.71 μM for 5-lipoxygenase, cyclooxygenase-1, and cyclooxygenase-2, respectively) were capable to inhibit catalytic activity of all three tested enzymes. Isorhapontigenin (IC_50s = 8.81 and 24.00 μM for cyclooxygenase-1 and cyclooxygenase-2, respectively) and rhapontigenin (IC_50s = 24.55 and 36.12 μM for cyclooxygenase-1 and cyclooxygenase-2, respectively) were only moderate or weak inhibitors of both cyclooxygenase forms. In summary, these results indicated that besides the known cyclooxygenase inhibitor resveratrol also other natural stilbenes could be potent inhibitors of the arachidonic acid pathway and deserve further attention as compounds with promising health benefits.     

Fluorescence in situ hybridization for detection of classical propionibacteria with specific 16S rRNA-targeted probes and its application to enumeration in Gruyère cheese

The classical or dairy propionibacteria have well-documented industrial applications and have been proposed for probiotic applications. Given their industrial importance it is necessary to employ fast and reliable techniques to monitor the growth during products elaboration, industrial fermentations or the intestinal transit. Therefore, the aim of this investigation was to design oligonucleotide probes targeting the 16S rRNA of dairy propionibacteria and optimise the fluorescence in situ hybridization (FISH) protocol to detect these bacteria. Two specific probes were in silico designed to detect Propionibacterium freudenreichii and P. jensenii, named Pfr435 and Pj446 respectively. The FISH protocol was optimised for the hybridisation of propionibacteria cells with the universal probe Eub338 and the designed probes. These probes were assayed in situ for their specificity to hybridise species of propionibacteria by observation using fluorescence microscopy and results were compared with the probe Pap446 previously designed for P. acidipropionici. Probes Pap446, Pfr435 and Pj446 were also evaluated by fluorescence spectrophotometry to assess the influence of cells physiological state during growth in batch culture in the fluorescence intensity. The maximum fluorescence intensity was observed at the onset of the stationary phase of growth and was then reduced. However, changes on the cells permeability did not reduce the efficiency of 16S rRNA hybridisation with the fluorescence-labelled probes. Propionibacteria counts obtained by FISH and plate count methods were compared in a commercial Gruyère cheese. The results showed that this method can be used as a rapid technique for the enumeration of these bacteria in cheese samples.     

Gastrointestinal myoelectrical activity during the postoperative period in man

Myoelectrical activity of the gastrointestinal tract has been studied in the postoperative period of 13 patients who underwent cholecystectomy. The recordings have been performed by means of extracellular electrodes which were implanted at the levels of stomach, jejunum, ileum and colon during the surgical procedure. The records showed that fast activity is always persistent while the basic electrical rhythm is greatly disorganized during the immediate postoperative period. Such a characteristic pattern of the electrical activity suggested that the lack of peristaltic and propulsive movements, always noted during this period, is not correlated with a disappearance of gastrointestinal contractions, but only with a disturbance in their coordination.