540 research outputs found
Ventilação natural e temperatura da superfĂcie de pisos aquecidos em escamoteadores
This research had the objective of evaluating the influence of the natural ventilation on the surface temperature distribution of heated crates. The research used six crates from a farrowing room in a commercial swine production farm located in the state of SĂŁo Paulo, Brazil. Three crates were heated using a heat mat while the other three had the environment heated by incandescent light bulbs (200W) fixed on the lateral wall. The surface temperature of the crate's floor (1.55x0.55m) was registered in 36 points, distributed in 18 quadrants (0.26x0.18m) using an infrared thermometer in three different conditions of the room's natural ventilation: opened, semi-opened, and closed lateral curtain. The isotherms and the temperature distribution of the floor heat were processed using the SURFERÂź (1995), and the statistical analysis was done using the MINITABÂź (Statistical..., 2002). It was found that the room's natural ventilation had a significant influence on crate floor surface temperature distribution. The crate with a heat mat system provided higher temperatures and led to a more homogeneous surface temperature distribution.O objetivo deste trabalho foi avaliar a influĂȘncia da ventilação natural sobre a distribuição da temperatura na superfĂcie de pisos aquecidos em escamoteadores. Foram avaliados seis escamoteadores da maternidade de uma granja de suĂnos localizada no estado de SĂŁo Paulo. Dentre os escamoteadores avaliados, trĂȘs deles usavam piso aquecido para o acondicionamento dos leitĂ”es, e os outros usavam lĂąmpadas incandescentes (200W), fixadas na parede lateral do interior do escamoteador. A temperatura da superfĂcie do piso (1,55x0,55m) foi registrada medindo-se 36 pontos distribuĂdos em 18 quadrantes (0,26x0,18m), por meio de um termĂŽmetro infravermelho, em trĂȘs diferentes condiçÔes de ventilação natural: com cortina lateral aberta, semiaberta e totalmente fechada. As isotermas e a distribuição da temperatura sobre o piso aquecido foram processadas usando-se o software SURFERÂź. Verificou-se que a ventilação natural teve efeito sobre a distribuição da temperatura da superfĂcie do piso dos escamoteadores. O escamoteador aquecido com manta tĂ©rmica forneceu temperaturas mais altas e distribuição mais homogĂȘnea na superfĂcie de contato com os leitĂ”es.47748
A novel model of tumour formation in NF1
Neurofibromatosis type 1 (NF1) is a common genetic disorder that predisposes to the
development of heterogeneous tumours of Schwann cell origin, termed neurofibromas.
Neurofibromas are thought to arise from a combination of genetic events â loss of the
Ras-GAP neurofibromin in the Schwann cell lineage â and microenvironmental cues.
Schwann cells are specialised cells that ensheath and myelinate the axons in the
peripheral nervous system (PNS). In the adult they are present in a quiescent state,
however following damage to the PNS they have a remarkable ability to regenerate.
Distal to the site of injury, Schwann cells dedifferentiate to a progenitor-like state, in
which they contribute to nerve repair by recruiting a robust inflammatory response
and helping axons return to their targets. Work from our laboratory has shown that
activation of the Ras/Raf/ERK pathway plays a central role in driving the switch in
Schwann cell state from a fully differentiated to a proliferating, âprogenitor-likeâ cell.
Crucially, neurofibromas resemble injured nerves in that they are composed of a
mixture of inflammatory cells and Schwann cells that are found dedifferentiated and
dissociated from axons, suggesting that deregulation of Ras/ERK may trigger
tumourigenic events.
In this thesis I present work on how the Ras/Raf/ERK pathway may be regulated in
Schwann cells. I show that the phosphatase MKP3 may be involved in controlling the
levels of ERK activity in Schwann cells during differentiation and following nerve injury.
I also describe a new model for neurofibroma formation. Using transgenic mice I show
that Nf1 loss in adult, myelinating Schwann cells has no effect on peripheral nerves and
does not induce tumourigenesis. However, when coupled with an injury, the mice
developed tumours at a high frequency. Furthermore, I show that in the absence of
Nf1, ERK signalling is deregulated upon injury, implicating this pathway in the tumour
formation. This may have therapeutic relevance, which is currently being tested in our
animal model. In addition, we observed that tumours only arise at the wound site,
despite Schwann cells dedifferentiating along the length of the nerve. This strongly
implies that the microenvironment is a crucial player in the outcome of Nf1 loss and
reveals this new animal model as a promising system to further dissect molecular
events involved in tumourigenesis
Integrated utilization of grape skins from white grape pomaces
An approach for the integrated utilization of grape skins from white grape pomaces has been proposed. This consists of consecutive or simultaneous extraction of grape skins with neutral organic solvent and water under reflux. Organic extract is a valuable raw material for the isolation of oleanolic acid. The aqueous extract (ca 50%, w/w) is composed of essentially hexoses and suitable for the high yield (till 51%) bioethanol production at a maximum specific cell growth rate (ÎŒmax) of 0.29 hâ1. The remained extracted grape skins are the complex of structural polysaccharides embedded into cutinous matrix. Extracted grape skins were shown to be a prospective raw material for the production of low-density boards (d †0.40) for insulation needs. The boards produced from grape skins and bind of 8% ureaâformaldehyde resin revealed reasonable tensile strength (0.4 MPa) and a low thermal conductivity (0.09â0.12 W (m K)â1) over a wide range of temperatures (40â200 °C).info:eu-repo/semantics/publishedVersio
Hierarchy problem and the cosmological constant in a five-dimensional Brans-Dicke brane world model
We discuss a new solution, admitting the existence of dS_{4} branes, in
five-dimensional Brans-Dicke theory. It is shown that, due to a special form of
a bulk scalar field potential, for certain values of the model parameters the
effective cosmological constant can be made small on the brane, where the
hierarchy problem of gravitational interaction is solved. We also discuss new
stabilization mechanism which is based on the use of auxiliary fields.Comment: 11 page
Hydroxocobalamin Quantification In Human Plasma By High-performance Liquid Chromatography Coupled With Electrospray Tandem Mass Spectrometry In A Pharmacokinetic Study
A rapid, sensitive and specific method for quantifying hydroxocobalamin in human plasma using paracetamol as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using an organic solvent (ethanol 100%; -20°C). The extracts were analyzed by high performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-MS-MS). Chromatography was performed on Prevail C8 3 ÎŒm, analytical column (2.1Ă100 mm i.d.). The method had a chromatographic run time of 3.4 min and a linear calibration curve over the range 5-400 ng.mL -1 (r>0.9983). The limit of quantification was 5 ng.mL-1. The method was also validated without the use of the internal standard. The precision in the intra-batch validation with IS was 9.6%, 8.9%, 1.0% and 2.8% whereas without IS was 9.2%, 8.2%, 1.8% and 1.5% for 5, 15, 80 and 320 ng/mL, respectively. The accuracy in intra-batch validation with IS was 108.9%, 99.9%, 98.9% and 99.0% whereas without IS was 101.1%, 99.3%, 97.5% and 92.5% for 5, 15, 80 and 320 ng/mL, respectively. The precision in the inter-batch validation with IS was 9.4%, 6.9%, 4.6% and 5.5% whereas without IS was 10.9%, 6.4%, 5.0% and 6.2% for 5, 15, 80 and 320 ng/mL, respectively. The accuracy in inter-batch validation with IS was 101.9%, 104.1%, 103.2% and 99.7% whereas without IS was 94.4%, 101.2%, 101.6% and 96.0% for 5, 15, 80 and 320 ng/ mL, respectively. This HPLC-MS-MS procedure was used to assess the pharmacokinetics of cobalamin following intramuscular injection 5000 ÎŒg in healthy volunteers of both sexes (10 males and 10 females). The volunteers had the following clinical characteristics (according to gender and expressed as mean ± SD [range]): males: age: 32.40 ± 8.00 [23.00-46.00], height: 1.73 ± 0.07 m [1.62-1.85], body weight: 72.48 ± 10.22 [60.20-88.00]; females: age: 28.60 ± 9.54 [18.00-44.00], height: 1.60 ± 0.05 [1.54-1.70], body weight: 58.64 ± 6.09 [51.70-66.70]. The following pharmacokinetic parameters were obtained from the hydroxocobalamin plasma concentration vs. time curves: AUC last, T1/2, Tmax, Vd, Cl, C max and Clast. The pharmacokinetic parameters were 120 (± 25) ng.mL -1 for C max, 2044 (± 641) ng.hr.mL -1 for AUClast, 8 (± 3.2) ng.mL -1 for Clast, 38 (± 15.8) hr for T 1/2 and 2.5 (range 1-6) hr for Tmax. Female volunteers presented significant (p=0.0136) lower AUC (1706 ± 704) ng.hr.mL-1) and larger (p=0.0205) clearance (2.91 ± 1.41 L/hr), as compared to male 2383 ± 343 ng.hr.mL -1 and 1.76 ± 0.23 L/hr, respectively. These pharmacokinetic differences could explain the higher prevalence of vitamin B12 deficiency in female patients. The method described validated well without the use of the internal standard and this approach should be investigated in other HPLC-MS-MS methods. © 2013 Mendes GD, et al.528087Butler, C.C., Vidal-Alaball, J., Cannings-John, R., McCaddon, A., Hood, K., Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency: A systematic review of randomized controlled trials (2006) Fam Pract, 23, pp. 279-285Kuzminski, A.M., Del Giacco, E.J., Allen, R.H., Stabler, S.P., Lindenbaum, J., (1998) Blood, 92, p. 1191van Asselt, D.Z., Merkus, F.W., Russel, F.G., Hoefnagels, W.H., Nasal absorption of hydroxocobalamin in healthy elderly adults (1998) Br J Clin Pharmacol, 45, pp. 83-86Van den Berg, M.P., Merkus, P., Romeijn, S.G., Verhoef, J.C., Merkus, F.W., Hydroxocobalamin uptake into the cerebrospinal fluid after nasal and intravenous delivery in rats and humans (2003) J Drug Target, 11, pp. 325-331Merkus, P., Guchelaar, H.J., Bosch, D.A., Merkus, F.W., (2003) Neurology, 6, p. 1669Chen, J.H., Jiang, S.J., Determination of cobalamin in nutritive supplements and chlorella foods by capillary electrophoresis-inductively coupled plasma mass spectrometry (2008) J Agric Food Chem, 56, pp. 1210-1215Kelly, R.J., Gruner, T.M., Sykes, A.R., Development of a method for the separation of corrinoids in ovine tissues by HPLC (2005) Biomed Chromatogr, 19, pp. 329-333Rosin, H., Man, W.Y., Doyle, E., Bult, A., Beijnen, J.H., (2000) J Liq Chromatogr and Related Tech, 23, p. 329Wang, Y.H., Yan, F., Zhang, W.B., Ye, G., Zheng, Y.Y., (2009) Neurosci Bull, 25, p. 209Dubois, D., Dubois, E.F., (1916) Arch Intern Med, 17, p. 862Mendes, F.D., Chen, L.S., Borges, A., BabadĂłpulos, T., Ilha, J.O., Ciprofibrate quantification in human plasma by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry for pharmacokinetic studies (2011) J Chromatogr B Analyt Technol Biomed Life Sci, 879, pp. 2361-2368Uhl, W., Nolting, A., Gallemann, D., Hecht, S., Kovar, A., Changes in blood pressure after administration of hydroxocobalamin: Relationship to changes in plasma cobalamins-(III) concentrations in healthy volunteers (2008) Clin Toxicol, 46, pp. 551-559. , (Phila
Modified Brans-Dicke theory of gravity from five-dimensional vacuum
We investigate, in the context of five-dimensional (5D) Brans-Dicke theory of
gravity, the idea that macroscopic matter configurations can be generated from
pure vacuum in five dimensions, an approach first proposed in the framework of
general relativity. We show that the 5D Brans-Dicke vacuum equations when
reduced to four dimensions lead to a modified version of Brans-Dicke theory in
four dimensions (4D). As an application of the formalism, we obtain two
five-dimensional extensions of four-dimensional O'Hanlon and Tupper vacuum
solution and show that they lead two different cosmological scenarios in 4D.Comment: 9 page
Atmospheric particulate matter from an industrial area as a source of metal nanoparticle contamination in aquatic ecosystems
Air pollution legislation and control worldwide is based on the size of particulate matter (PM) to evaluate the effects on environmental and human health, in which the small diameter particles are considered more dangerous than larger sizes. This study investigates the composition, stability, size and dispersion of atmospheric settleable particulate matter (SePM) in an aqueous system. We aimed to interrogate the changes in the physical properties and characteristics that can contribute to increased metal uptake by aquatic biota. Samples collected in an area influenced by the steel and iron industry were separated into 8 fractions (425 to â€10 Όm) and analysed physically and chemically. Results from ICP-MS and X-ray showed that the PM composition was mainly hematite with 80% of Fe, followed by Al, Mn and Ti. Among 27 elements analysed we found 19 metals, showing emerging metallic contaminants such as Y, Zr, Sn, La, Ba and Bi. Scanning electron microscopy (SEM) showed that SePM fractions are formed by an agglomeration of nanoparticles. Furthermore, dynamic light scattering (DLS), zeta potential and nanoparticle tracking analysis (NTA) demonstrated that SPM were dissociated in water, forming nanoparticles smaller than 200 nm, which can also contribute to water pollution. This study highlights that SePM contamination may be substantially higher than expected under that allowed in atmospheric regulatory frameworks, thereby extending their negative effect to water bodies upon settling, which is an underexplored area of our knowledge. We therefore provide important insights for future investigations on safety regulations involving SePM in the environment, indicating the need to revise the role of SePM, not solely associated with air pollution but also considering their deleterious effects on water resources
Epidemic processes with immunization
We study a model of directed percolation (DP) with immunization, i.e. with
different probabilities for the first infection and subsequent infections. The
immunization effect leads to an additional non-Markovian term in the
corresponding field theoretical action. We consider immunization as a small
perturbation around the DP fixed point in d<6, where the non-Markovian term is
relevant. The immunization causes the system to be driven away from the
neighbourhood of the DP critical point. In order to investigate the dynamical
critical behaviour of the model, we consider the limits of low and high first
infection rate, while the second infection rate remains constant at the DP
critical value. Scaling arguments are applied to obtain an expression for the
survival probability in both limits. The corresponding exponents are written in
terms of the critical exponents for ordinary DP and DP with a wall. We find
that the survival probability does not obey a power law behaviour, decaying
instead as a stretched exponential in the low first infection probability limit
and to a constant in the high first infection probability limit. The
theoretical predictions are confirmed by optimized numerical simulations in 1+1
dimensions.Comment: 12 pages, 11 figures. v.2: minor correction
New triazine bridged triads based on BODIPY-porphyrin systems: extended absorption, efficient energy transfer and upconverted emission
Two novel triads connecting a BODIPY to ethylenediamine substituted porphyrins via triazine linker have been synthesized and characterized. One of the triads is a linear D-A structure with one BODIPY (D) and one porphyrin (A) bridged by the triazine linker and the other one is a branched A-D4 structure with the porphyrin core linked to four BODIPY units. The triads show extended absorption in the visible region with contributions from both porphyrin (Soret band centred at 410â430 nm) and BODIPY units (strong absorption at â 502 nm) in good agreement with the expected molar ratio. Both triads exhibit linear and nonlinear optical properties featuring an efficient energy transfer from the BODIPY donor to the porphyrin acceptor. The nonlinear upconverted emission properties of the triads were studied by two-photon excitation in the Near-infrared (NIR, 710â930 nm). The maximum two-photon absorption cross-section values for the triads (40â70 GM) are larger than those typically reported in this wavelength range for porphyrins and BODIPY. Both the green emission of BODIPY (â514 nm) and the red emission of porphyrins (650â750 nm) were observed under NIR excitation at 930 nm. The distinct features of triads, namely i) an extended absorption; ii) an efficient energy transfer and iii) the nonlinear upconverted emission featuring a large separation between the excitation and emission wavelengths could be beneficial for application in sensing and imaging procedures.publishe
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