FORCED CONVECTION TO LAMINAR FLOW OF LIQUID EGG YOLK IN CIRCULAR AND ANNULAR DUCTS

The steady-state heat transfer in laminar flow of liquid egg yolk - an important pseudoplastic fluid food - in circular and concentric annular ducts was experimentally investigated. The average convection heat transfer coefficients, determined by measuring temperatures before and after heating sections with constant temperatures at the tube wall, were used to obtain simple new empirical expressions to estimate the Nusselt numbers for fully established flows at the thermal entrance of the considered geometries. The comparisons with existing correlations for Newtonian and non-Newtonian fluids resulted in excellent agreement. The main contribution of this work is to supply practical and easily applicable correlations, which are, especially for the case of annulus, rather scarce and extensively required in the design of heat transfer operations dealing with similar shear-thinning products. In addition, the experimental results may support existing theoretical analyses.

Efficiency of uniparental male and female care against egg predators in two closely related syntopic harvestmen

Although the benefits of maternal care have been investigated in many species, the caring role of males in species with exclusive paternal care has received less attention. We experimentally quantified the protective role of paternal care in the harvestman Iporangaia pustulosa. Additionally, we compared the effectiveness of paternal care against predation in this species with a syntopic harvestman with maternal care, Acutisoma proximum. We demonstrated that nearly one-third of the unprotected Iporangaia clutches disappeared entirely in 12 days, while the other two-thirds suffered a mean reduction of 55% in egg number. Conversely, 50% of the control clutches did not suffer any reduction, and only one was entirely consumed by predators. We also demonstrated that the mucus coat that covers Iporangaia clutches has an important deterrent role against predation by conspecifics: 58.3% of the clutches without mucus were attacked and three of them were entirely consumed, whereas only three clutches with mucus were attacked, suffering a reduction of up to three eggs. Iporangaia males were as efficient as Acutisoma females in protecting eggs. However, unattended Acutisoma eggs were attacked 20% more frequently than unattended Iporangaia eggs. Unattended Iporangaia eggs are protected by a mucus coat that prevents or decreases predation rate, whereas Acutisoma eggs are more susceptible to predation, probably because they lack this mucus coat. Thus, besides the fact that Iporangaia males efficiently protect the offspring against egg predators, females also contribute to egg protection by providing a mucus coat that deters egg predators. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Histological and functional renal alterations caused by Bothrops alternatus snake venom: Expression and activity of Na(+)/K(+)-ATPase

Background: Acute renal failure is a serious complication of human envenoming by Bothrops snakes. The ion pump Na(+)/K(+)-ATPase has an important role in renal tubule function, where it modulates sodium reabsorption and homeostasis of the extracellular compartment. Here, we investigated the morphological and functional renal alterations and changes in Na(+)/K(+)-ATPase expression and activity in rats injected with Bothrops alternatus snake venom. Methods: Male Wistar rats were injected with venom (0.8 mg/kg, iv.) and renal function was assessed 6.24, 48 and 72 h and 7 days post-venom. The rats were then killed and renal Na(+)/K(+)-ATPase activity was assayed based on phosphate release from ATP; gene and protein expressions were assessed by real time PCR and immunofluorescence microscopy, respectively. Results: Venom caused lobulation of the capillary tufts, dilation of Bowman`s capsular space. F-actin disruption in Bowman`s capsule and renal tubule brush border, and deposition of collagen around glomeruli and proximal tubules that persisted seven days after envenoming. Enhanced sodium and potassium excretion, reduced proximal sodium reabsorption, and proteinuria were observed 6 h post-venom, followed by a transient decrease in the glomerular filtration rate. Gene and protein expressions of the Na(+)/K(+)-ATPase alpha(1) subunit were increased 6 h post-venom, whereas Na(+)/K(+)-ATPase activity increased 6 h and 24 h post-venom. Conclusions: Bothrops alternatus venom caused marked morphological and functional renal alterations with enhanced Na(+)/K(+)-ATPase expression and activity in the early phase of renal damage. General significance: Enhanced Na(+)/K(+)-ATPase activity in the early hours after envenoming may attenuate the renal dysfunction associated with venom-induced damage. (C) 2011 Elsevier B.V. All rights reserved.

Numerical simulation of the liquid phase in SnO(2) thin film deposition by sol-gel-dip-coating

The fluid flow of the liquid phase in the sol-gel-dip-coating process for SnO(2) thin film deposition is numerically simulated. This calculation yields useful information on the velocity distribution close to the substrate, where the film is deposited. The fluid modeling is done by assuming Newtonian behavior, since the linear relation between shear stress and velocity gradient is observed. Besides, very low viscosities are used. The fluid governing equations are the Navier-Stokes in the two dimensional form, discretized by the finite difference technique. Results of optical transmittance and X-ray diffraction on films obtained from colloidal suspensions with regular viscosity, confirm the substrate base as the thickest part of the film, as inferred from the numerical simulation. In addition, as the viscosity increases, the fluid acquires more uniform velocity distribution close to the substrate, leading to more homogenous and uniform films.

Combustion iron distribution and deposition

[1] Iron is hypothesized to be an important micronutrient for ocean biota, thus modulating carbon dioxide uptake by the ocean biological pump. Studies have assumed that atmospheric deposition of iron to the open ocean is predominantly from mineral aerosols. For the first time we model the source, transport, and deposition of iron from combustion sources. Iron is produced in small quantities during fossil fuel burning, incinerator use, and biomass burning. The sources of combustion iron are concentrated in the industrialized regions and biomass burning regions, largely in the tropics. Model results suggest that combustion iron can represent up to 50% of the total iron deposited, but over open ocean regions it is usually less than 5% of the total iron, with the highest values (< 30%) close to the East Asian continent in the North Pacific. For ocean biogeochemistry the bioavailability of the iron is important, and this is often estimated by the fraction which is soluble ( Fe(II)). Previous studies have argued that atmospheric processing of the relatively insoluble Fe(III) occurs to make it more soluble ( Fe( II)). Modeled estimates of soluble iron amounts based solely on atmospheric processing as simulated here cannot match the variability in daily averaged in situ concentration measurements in Korea, which is located close to both combustion and dust sources. The best match to the observations is that there are substantial direct emissions of soluble iron from combustion processes. If we assume observed soluble Fe/black carbon ratios in Korea are representative of the whole globe, we obtain the result that deposition of soluble iron from combustion contributes 20-100% of the soluble iron deposition over many ocean regions. This implies that more work should be done refining the emissions and deposition of combustion sources of soluble iron globally.

Chemical bonding and composition of silicon nitride films prepared by inductively coupled plasma chemical vapor deposition

Thin silicon nitride films were prepared at 350 degrees C by inductively coupled plasma chemical vapor deposition on Si(100) substrates under different NH(3)/SiH(4) or N(2)/SiH(4) gas mixture. The chemical composition and bonding structure of the deposited films were investigated as a function of the process parameters, such as the gas flow ratio NH(3)/SiH(4) or N(2)/SiH(4) and the RF power, using X-ray photoelectron spectroscopy (XPS). The gas flow ratio was 1.4, 4.3, 7.2 or 9.5 and the RF power, 50 or 100 W. Decomposition results of Si 2p XPS spectra indicated the presence of bulk Si, under-stoichiometric nitride, stoichiometric nitride Si(3)N(4), oxynitride SiN(x)O(y), and stoichiometric oxide SiO(2), and the amounts of these compounds were strongly influenced by the two process parameters. These results were consistent with those obtained from N 1s XPS spectra. The chemical composition ratio N/Si in the film increased with increasing the gas flow ratio until the gas flow ratio reached 4.3, reflecting the high reactivity of nitrogen, and stayed almost constant for further increase in gas flow ratio, the excess nitrogen being rejected from the growing film. A considerable and unexpected incorporation of contaminant oxygen and carbon into the depositing film was observed and attributed to their high chemical reactivity. (C) 2010 Elsevier B.V. All rights reserved.

X-ray photoelectron spectroscopy analysis of zirconium nitride-like films prepared on Si(100) substrates by ion beam assisted deposition

Thin zirconium nitride films were prepared on Si(l 00) substrates at room temperature by ion beam assisted deposition with a 2 keV nitrogen ion beam. Arrival rate ratios ARR(N/Zr) used were 0.19, 0.39, 0.92, and 1.86. The chemical composition and bonding structure of the films were analyzed with X-ray photoelectron spectroscopy (XPS). Deconvolution results for Zr 3d, Zr 3p(3/2), N 1s, O 1s, and C 1s XPS spectra indicated self-consistently the presence of metal Zr-0, nitride ZrN, oxide ZrO2, oxymnide Zr2N2O, and carbide ZrC phases, and the amounts of these compounds were influenced by ARR(N/Zr). The chemical composition ratio N/Zr in the film increased with increasing ARR(N/Zr) until ARR(N/Zr) reached 0.92, reflecting the high reactivity of nitrogen in the ion beam, and stayed almost constant for ARR(N/Zr) >= 1, the excess nitrogen being rejected from the growing film. A considerable incorporation of contaminant oxygen and carbon into the depositing film was attributed to the getter effect of zirconium. (C) 2007 Elsevier B.V. All rights reserved.

Classical simulation of deposition of thiophene oligomers on TiO(2)-anatase: Relevance of long-range electrostatic interactions

We performed classical molecular dynamics simulations of the vapor-deposition of alpha-T4 oligomers on the TiO(2)-anatase (101) surface, comparing different sets of charges associated with the atoms of the model. The potential energy surfaces for alpha-T4 and TiO(2) were described by re-parametrizations of the Universal force field with charges given by the charge equilibration (QEq) scheme, or with fixed charges obtained by an ab initio method using the Hirshfeld partition. The two sets of charges lead to completely different results for the interface formation, and for the characteristics of the organic film, with a clearly defined alpha-T4 contact layer in the QEq case, and a more homogeneous molecular distribution when using Hirshfeld charges. The main reason for the discrepancy was found to be the incorrect charge assignment given by QEq to the sulfur and alpha-carbon atoms in thiophenes, and highlight the relevance of long-range interactions in the organization of molecular films. (C) 2009 Elsevier B.V. All rights reserved.

Ion beam assisted deposition of an organic light emitting diode electrode

This work presents the electro-optical characterization of metal-organic interfaces prepared by the Ion Beam Assisted Deposition (IBAD) method. IBAD applied in this work combines simultaneously metallic film deposition and bombardment with an independently controlled ion beam, allowing different penetration of the ions and the evaporated metallic elements into the polymer. The result is a hybrid, non-abrupt interface, where polymer, metal and ion coexists. We used an organic light emitting diode, which has a typical vertical-architecture, for the interface characterization: Glass/Indium Tin Oxide (ITO)/Poly[ethylene-dioxythiophene/poly{styrenesulfonicacid}]) (PEDOT:PSS) /Emitting Polymer/Metal. The emitting polymer layer comprised of the Poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-co-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] (PFO) and the metal layer of aluminum prepared with different Ar(+) ion energies varying in the range from 0 to 1000 eV. Photoluminescence, Current-Voltage and Electroluminescence measurements were used to study the emission and electron injection properties. Changes of these properties were related with the damage caused by the energetic ions and the metal penetration into the polymer. Computer simulations of hybrid interface damage and metal penetration were confronted with experimental data. (C) 2010 Elsevier B.V. All rights reserved.

Electrophoretic deposition of Ba0.77Ca0.23TiO3 nanopowders

Ba0.77Ca0.23TiO3 (BCT23) nanometric powders, synthesized by the modified Pechini method, were used as precursor to produce thick films (50-130 mu m) employing the electrophoretic deposition (EPD) technique. The BCT23 powder presented a single crystalline phase with an average particle size and a crystallite size of similar to 60 nm and similar to 20 nm, respectively, when calcined at 800 degrees C/2h. BCT23 thick films were deposited on platinum substrates starting from different suspensions prepared by dispersion of the powder into: isopropyl alcohol (IPA) or a mixture of acetylacetone (Acac) and ethanol (EtOH) (1:1, volumetric ratio). A milling process was used to deagglomerate the powders in order to increase the suspension stability and improving the deposition. Dense and crack free thick films with uniform microstructure were obtained after sintering at 1300 degrees C/2 h from Acac+EtOH solution. (C) 2007 Elsevier B.V. All rights reserved.

P-T-Fluid evolution and graphite deposition during retrograde metamorphism in Ribeira Fold Belt, SE Brazil: Oxygen fugacity, fluid inclusions and C-O-H isotopic evidence

Combined fluid inclusion (FI) microthermometry, Raman spectroscopy, X-ray diffraction, C-O-H isotopes and oxygen fugacities of granulites from central Ribeira Fold Belt, SE Brazil, provided the following results: i) Magnetite-Hematite fO(2) estimates range from 10(-11.5) bar (QFM + 1) to 10(-18.3) bar (QFM - 1) for the temperature range of 896 degrees C-656 degrees C, implying fO(2) decrease from metamorphic peak temperatures to retrograde conditions; ii) 5 main types of fluid inclusions were observed: a) CO(2) and CO(2)-N(2) (0-11 mol%) high to medium density (1.01-0.59 g/cm(3)) FI; b) CO(2) and CO(2)-N(2) (0-36 mol%) low density (0.19-0.29 g/cm(3)) FI; c) CO(2) (94-95 mol%)-N(2) (3 mol%)-CH(4) (2-3 mol%)-H(2)O (water phi(v) (25 degrees C) = 0.1) FI; d) low-salinity H(2)O-CO(2) FI; and e) late low-salinity H(2)O FI; iii) Raman analyses evidence two graphite types in khondalites: an early highly ordered graphite (T similar to 450 degrees C) overgrown by a disordered kind (T similar to 330 degrees C); iv) delta(18)O quartz results of 10.3-10.7 parts per thousand, imply high-temperature CO(2) delta(18)O values of 14.4-14.8 parts per thousand, suggesting the involvement of a metamorphic fluid, whereas lower temperature biotite delta(18)O and delta D results of 7.5-8.5 parts per thousand and -54 to -67 parts per thousand respectively imply H(2)O delta(18)O values of 10-11 parts per thousand and delta D(H2O) of -23 to -36 parts per thousand suggesting delta(18)O depletion and increasing fluid/rock ratio from metamorphic peak to retrograde conditions. Isotopic results are compatible with low-temperature H(2)O influx and fO(2) decrease that promoted graphite deposition in retrograde granulites, simultaneous with low density CO(2), CO(2)-N(2) and CO(2)-N(2)-CH(4)-H(2)O fluid inclusions at T = 450-330 degrees C. Graphite delta(13)C results of -10.9 to -11.4 parts per thousand imply CO(2) delta(13)C values of -0.8 to -1.3 parts per thousand suggesting decarbonation of Cambrian marine carbonates with small admixture of lighter biogenic or mantle derived fluids. Based on these results, it is suggested that metamorphic fluids from the central segment of Ribeira Fold Belt evolved to CO(2)-N(2) fluids during granulitic metamorphism at high fO(2), followed by rapid pressure drop at T similar to 400-450 degrees C during late exhumation that caused fO(2) reduction induced by temperature decrease and water influx, turning carbonic fluids into CO(2)-H(2)O (depleting biotite delta(18)O and delta D values), and progressively into H(2)O. When fO(2) decreased substantially by mixture of carbonic and aqueous fluids, graphite deposited forming khondalites. (C) 2010 Elsevier Ltd. All rights reserved.

DMSO-Induced Denaturation of Hen Egg White Lysozyme

We report on the size, shape, structure, and interactions of lysozyme in the ternary system lysozyme/DMSO/water at low protein concentrations. Three structural regimes have been identified, which we term the ""folded"" (0 < phi(DMSO) < 0.7), ""unfolded"" (0.7 <= phi(DMSO) < 0.9), and ""partially collapsed"" (0.9 <= phi(DMSO) < 1.0) regime. Lysozyme resides in a folded conformation with an average radius of gyration of 1.3 +/- 0.1 nm for phi(DMSO) < 0.7 and unfolds (average R(g) of 2.4 +/- 0.1 nm) above phi(DMSO) > 0.7. This drastic change in the protein`s size coincides with a loss of the characteristic tertiary structure. It is preceded by a compaction of the local environment of the tryptophan residues and accompanied by a large increase in the protein`s overall flexibility. In terms of secondary structure, there is a gradual loss of alpha-helix and concomitant increase of beta-sheet structural elements toward phi(DMSO) = 0.7, while an increase in phi(DMSO) at even higher DMSO volume fractions reduces the presence of both a-helix and beta-sheet secondary structural elements. Protein-protein interactions remain overall repulsive for all values of phi(DMSO) An attempt is made to relate these structural changes to the three most important physical mechanisms that underlie them: the DMSO/water microstructure is strongly dependent on the DMSO volume fraction, DMSO acts as a strong H-bond acceptor, and DMSO is a bad solvent for the protein backbone and a number of relatively polar side groups, but a good solvent for relatively apolar side groups, such as tryptophan.

Platinum nanoparticle-modified electrodes, morphologic, and electrochemical studies concerning electroactive materials deposition

The present work describes the synthesis of platinum nanoparticles followed by their electrophoretic deposition onto transparent fluorine-doped tin oxide electrodes. The nano-Pt-modified electrodes were characterized by voltammetric studies in acidic solutions showing a great electrocatalytic behavior towards H(+) reduction being very interesting for fuel cell applications. Morphological characterization was performed by atomic force microscopy on different modified electrodes showing a very rough surface which can be tuned by means of time of deposition. Also, nickel hydroxide thin films were galvanostatically grown onto these electrodes showing an interesting electrochemical behavior as sharper peaks, indicating a faster ionic exchange from the electrolyte to the film.

Development of Highly Selective Enzymatic Devices Based on Deposition of Permselective Membranes on Aligned Nanowires

We describe a simple and efficient strategy to fabricate enzymatic devices based on the deposition of glucose oxidase on aligned and highly oriented CoNiMo metallic nanowires. CoNiMo nanowires with an average diameter of 200 nm and length of 50 mu m were electrodeposited on Au-covered alumina substrates via electrodeposition, using alumina membranes as templates. Enzyme-modified electrodes were fabricated via enzyme immobilization using a cross-linker. To minimize nonspecific reactions in the presence of interfering agents, a permselective membrane composed of poly(vinylsulfonic acid) and polyamidoamine dendrimer was deposited via electrostatic interaction. The formation of hydrogen peroxide as a product of the enzymatic reaction was monitored at low overpotential, 0.0 V (vs Ag/AgCl). The detection limit was estimated at 22 mu M under an applied potential of 0.0 V. The apparent Michaelis-Menten constant determined from the Lineweaver-Burke plot was 2 mM.

Electrostatic layer-by-layer deposition and electrochemical characterization of thin films composed of MnO(2) nanoparticles in a room-temperature ionic liquid

Thin films of MnO(2) nanoparticles were grown using the layer-by-layer method with poly (diallyldimetylammonium) as the intercalated layer. The film growth was followed by UV-vis, electrochemical quartz crystal microbalance (EQCM), and atomic force microscopy. Linear growth due to electrostatic immobilization of layers was observed up to 30 bilayers, but electrical connectivity was maintained only for 12 MnO(2)/PPDA bilayers. The electrochemical characterization of this film in 1-butyl-2,3-dimethyl-imidazolium (BMMI) bis(trifluoromethanesulfonyl)imide (TFSI) (BMMITFSI) with and without addition of a lithium salt indicated a higher electrochemical response of the nanostructured electrode in the lithium-containing electrolyte. On the basis of EQCM experiments, it was possible to confirm that the charge compensation process is achieved mainly by the TFSI anion at short times (<2 s) and by BMMI and lithium cations at longer times. The fact that large ions like TFSI and BMMI participate in the electroneutrality is attributed to the redox reaction that occurs at the superficial sites and to the high concentration of these species compared to that of lithium cations.