A new spin-2 self-dual model in D=2+1D=2+1

There are three self-dual models of massive particles of helicity +2 (or -2) in $D=2+1$. Each model is of first, second, and third-order in derivatives. Here we derive a new self-dual model of fourth-order, \cL {SD}^{(4)}, which follows from the third-order model (linearized topologically massive gravity) via Noether embedment of the linearized Weyl symmetry. In fact, each self-dual model can be obtained from the previous one \cL {SD}^{(i)} \to \cL {SD}^{(i+1)}, i=1,2,3 by the Noether embedment of an appropriate gauge symmetry, culminating in \cL {SD}^{(4)}. The new model may be identified with the linearized version of \cL {HDTMG} = \epsilon^{\mu\nu\rho} \Gamma_{\mu\gamma}^\epsilon (\p_\nu\Gamma_{\epsilon\rho}^\gamma + (2/3)\Gamma_{\nu\delta}^\gamma \Gamma_{\rho\epsilon}^\delta) /8 m + \sqrt{-g}(R_{\mu\nu} R^{\nu\mu} - 3 R^2/8) /2 m^2 . We also construct a master action relating the third-order self-dual model to \cL {SD}^{(4)} by means of a mixing term with no particle content which assures spectrum equivalence of \cL {SD}^{(4)} to other lower-order self-dual models despite its pure higher derivative nature and the absence of the Einstein-Hilbert action. The relevant degrees of freedom of \cL {SD}^{(4)} are encoded in a rank-two tensor which is symmetric, traceless and transverse due to trivial (non-dynamic) identities, contrary to other spin-2 self-dual models. We also show that the Noether embedment of the Fierz-Pauli theory leads to the new massive gravity of Bergshoeff, Hohm and Townsend.Comment: 14 pages, no figures, typos fixed, reference (19) modifie

Dimensionamento de sistemas de aquecimento em pisos elétricos para frangos de corte.

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A comparative study of extraction apparatus in HPLC analysis of ochratoxin A in muscle

Abstract Ochratoxin A (OTA) is a secondary fungal metabolite produced by several moulds, mainly by Aspergillus ochraceus and by Penicillium verrucosum, that occurs in meat products. The aim of this work was to optimize an efficient extraction procedure for the determination of OTA in muscle tissue in order to assess its occurrence in meat samples. Three different apparatus, a Waring blender, a switching apparatus, and an ultrasonic processor, were evaluated to verify the efficiency of extraction. The analytical methods proposed involve the extraction with chloroform-orthophosphoric acid, cleanup through an immunoaffinity column, high-performance liquid chromatography/fluorescence detection for separation and identification of OTA, and confirmation with liquid chromatography/FD after methylation of OTA in muscle tissue. The limit of quantification of the proposed method was 0.04 µg kg-1. Recoveries of OTA, using switching apparatus, ranged from 90.3 to 103.2% for chicken muscle spiked at 2.4 and 0.48 µg kg-1, respectively, with a within-day relative standard deviation of 17 and 15.3%. The proposed method was applied to 38 chicken, swine, and turkey muscle samples and the presence of OTA was confirmed in five samples. Finally, the estimated daily intake of OTA in this study was between 23 pg kg-1 body weight per day for swine samples and 18 pg kg-1 body weight per day for turkey samples

Ethanol production from enzymatically pretreated wheat straw

Lignocellulosic biomass can be utilized to produce ethanol, a promising alternative energy source for the limited crude oil. Wheat straw is an abundant agricultural residue which can be used as lignocellulosic raw material for bioconversion. There are mainly two processes involved in the bioconversion: hydrolysis of cellulose in the lignocellulosic biomass to produce reducing sugars, and fermentation of the sugars to ethanol. The current study involved the optimization of enzymatic hydrolysis of a wheat straw pretreated by acid hydrolysis, using a mixture of commercial cellulases: celluclast 1.5L + Novozym 188, with further fermentation of the hydrolisate’ sugar content by three ethanologenic strains, namely two yeast of Saccharomyces cerevisiae (strains F and K) and a bacterial strain, Zymomonas mobilis (strain CP4). The fermentation assays, using undiluted hydrolisate with or without nutrient supplements, were monitored by the evaluation of glucose and ethanol yields. In the assays using no supplemented hydrolisate the results obtained for the two yeasts strains F and K, and Zymomonas mobilis were 74%, 79% and 58% of ethanol yield, respectively. However, when the hydrolisate was supplemented the fermentation results showed a better bioconversion process by the Z. mobilis, reaching 98% ethanol yield while the two strains of S. cerevisiae used maintained their behaviour. So, the fermentation results showed the necessity of the addition of nutrients for a good bioconversion process by the Z. mobilis, resulting in better ethanol yield than S. cerevisiae strains (F and K) from WSP hydrolisate

Kinetics of a packed-bed bacth reactor for the treatment of olive oil wastewaters from a Portuguese mill

Olive oil production is a traditional agricultural industry in Mediterranean countries and Portugal is one of the ten major producers. This industry generates an effluent, olive mill wastewater. This effluent does not undergo any treatment and is usually stored in evaporation lagoons or spread on the land. This can have a negative impact in the environment since this effluent has a high level of organic matter leading to a high chemical oxygen demand. In addition it has also a high content of polyphenols that contributes to the ecotoxicity of this effluent.Different techniques for the treatment of these wastewaters have been studied. In this work a 60 litre vessel was filled with a packaging of plastic material consisting of a cubic geometry (Biological Carrier Media from Rauschert). The non-inoculated reactor was filled with effluent from an olive mill farm (from Alfândega da Fé, Trás-os-Montes) and the effluent was re-circulated daily for homogeneity. COD, colour, nitrogen, solids and phosphorous were measured to follow the evolution of the system. Microbial composition and polyphenols were also evaluated. As an indicator of the microbial activity in the reactor, lipase activities were measured. Ecotoxicity tests were carried out to follow the detoxification capacity of the system as well as its potential for using in the treatment of this type of agroindustrial effluent

Comportamento de frangos de corte em sistemas de aquecimento.

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TGGE-monitoring of the microbial community along the olive mill wastewaters anaerobic treatment

Monitoring the microbial community present during the olive mill wastewater (OMW) anaerobic treatment was carried out using PCR-TGGE analysis. Phase-contrast microscopy was used in order to directly examine microbial cells morphology. Samples were collected from the anaerobic digester bottom along the successive increases of OMW loading rate. TGGE banding patterns showed a significant diversity of OTUs. Cluster analysis of TGGE banding patterns shows two major groups: one cluster composed of samples belonging to the initial phases of treatment and a second cluster that encloses the other two samples. According to BLAST results, four sequences affiliated with group Cytophaga-Flexibacter-Bacteroidetes (CFB), one with sub-class Epsilon-Proteobacteria and other with phylum Firmicutes. The sequences obtained from each band were used to construct phylogenetic trees, and also using bacterial 16S rDNA sequences from environmental clones and reference taxa. Archaeal 16SrDNA PCR detection analysis revealed the presence of Archaea only in the initial sample of the digester start-up suggesting that methanogenesis along the treatment process occurs at an upper level of the unit. Concerning microscopic observations, the more representative morphological forms found in the bottom of digester were Clostridium spp. and Clostridium spp. sarcina-like forms

Olive Mill wastewater bioremediation towards detoxification

Olive oil production is a traditional agricultural industry in Mediterranean countries and Portugal is one of the ten major producers. This industry generates an effluent, olive mill wastewater (OMW), which does not undergo any treatment and, usually, is stored in evaporation lagoons or spread on the land. Disposal of olive oil mill wastewaters is a serious environmental problem due to its high organic loading, presence of polyphenols and tannins, high content in suspended solids and acidity, which contributes to its ecotoxicity. In this work it was intended to study the biodegradation of OMW by microrganisms naturally present in these wastewaters. Thus, an aerobic biological treatment system: a packed-bed batch reactor was applied to a OMW from a mill on northern of Portugal, exploring its autochthon microbial population as inoculum. The biodegradation ability of OMW by microrganisms naturally present in these wastewaters was assessed, by following the evolution of the process and monitoring several of its physico-chemical parameters. Furthermore, an ecotoxicological evaluation, using chronic toxicity tests (Pseudomonas putida growth inhibition test and Vibrio fischeri growth inhibition test), was performed to follow the detoxification capacity of the system as well as its potential to be used in the treatment of this type of agroindustrial effluent