The role of rainfall intensity and soil in determining rates of flow through cryoturbated chalk

The effects of different water application rates (3, 10, 15 and 30 mm/h) and of topsoil removal on the rate of downward water movement through the cryoturbated chalk zone in southern England were investigated in situ. During and after each application of water, changes in water content and matric potential of the profile were monitored and percolate was collected in troughs. The measured water breakthrough time showed that water moved to 1.2 m depth quickly (in 8.2 h) even with application rate as low as 3 mm/h and that the time was only 3 h when water was applied at a rate of 15 mm/ h. These breakthrough times were about 150 and 422 fold shorter, respectively, than those expected if the water had been conducted by the matrix alone. Percolate was collected in troughs within 3.5 h at 1.2 m depth when water was applied at 30 mm/h and the quantity collected indicated that a significant amount of the surface applied water moved downward through inter-aggregate pores. The small increase in volumetric water content (about 3%) in excess of matrix water content resulted in a large increase in pore water velocities, from 0.20 to 5.3 m/d. The presence of soil layer had effect on the time taken for water to travel through the cryoturbated chalk layer and in the soil layer, water took about 1-2 h to pass thorough, depending on the intensity.

Padé approximants for the acoustical properties of rigid frame porous media with pore size distributions

Expressions for the viscosity correction function, and hence bulk complex impedance, density, compressibility, and propagation constant, are obtained for a rigid frame porous medium whose pores are prismatic with fixed cross-sectional shape, but of variable pore size distribution. The lowand high-frequency behavior of the viscosity correction function is derived for the particular case of a log-normal pore size distribution, in terms of coefficients which can, in general, be computed numerically, and are given here explicitly for the particular cases of pores of equilateral triangular, circular, and slitlike cross-section. Simple approximate formulae, based on two-point Pade´ approximants for the viscosity correction function are obtained, which avoid a requirement for numerical integration or evaluation of special functions, and their accuracy is illustrated and investigated for the three pore shapes already mentioned

Oxidized alginate hydrogels as niche environments for corneal epithelial cells

Chemical and biochemical modification of hydrogels is one strategy to create physiological constructs that maintain cell function. The aim of this study was to apply oxidised alginate hydrogels as a basis for development of a biomimetic niche for limbal epithelial stem cells that may be applied to treating corneal dysfunction. The stem phenotype of bovine limbal epithelial cells (LEC) and the viability of corneal epithelial cells (CEC) were examined in oxidised alginate gels containing collagen IV over a 3-day culture period. Oxidation increased cell viability (P pores (diameter: 0.2 - 0.8 microm) than unmodified gels (pore diameter: 0.05 - 0.1 microm) and were significantly less stiff (P

In vivo study of the biocompatibility of a novel compressed collagen hydrogel scaffold for artificial corneas

The experiments were designed to evaluate the biocompatibility of a plastically compressed collagen scaffold (PCCS). The ultrastructure of the PCCS was observed via scanning electron microscopy. Twenty New Zealand white rabbits were randomly divided into experimental and control groups that received corneal pocket transplantation with PCCS and an amniotic membrane, respectively. And the contralateral eye of the implanted rabbit served as the normal group. On the 1st, 7th, 14th, 21st, 30th, 60th, 90th, and 120th postoperative day, the eyes were observed via a slit lamp. On the 120th postoperative day, the rabbit eyes were enucleated to examine the tissue compatibility of the implanted stroma. The PCCS was white and translucent. The scanning electron microscopy results showed that fibers within the PCCS were densely packed and evenly arranged. No edema, inflammation, or neovascularization was observed on ocular surface under a slit lamp and few lymphocytes were observed in the stroma of rabbit cornea after histological study. In conclusion, the PCCS has extremely high biocompatibility and is a promising corneal scaffold for an artificial cornea. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.

Effect of aluminium on migratory and invasive properties of MCF-7 human breast cancer cells in culture

Aluminium (Al) has been measured in human breast tissue, nipple aspirate fluid and breast cyst fluid, and recent studies have shown that at tissue concentrations, aluminium can induce DNA damage and suspension growth in human breast epithelial cells. This paper demonstrates for the first time that exposure to aluminium can also increase migratory and invasive properties of MCF-7 human breast cancer cells. Long-term (32 weeks) but not short-term (1 week) exposure of MCF-7 cells to 10-4M aluminium chloride or 10-4M aluminium chlorohydrate increased motility of the cells as measured by live cell imaging (cumulative length moved by individual cells), by a wound healing assay and by migration in real time through 8m pores of a membrane using xCELLigence technology. Long-term exposure (37weeks) to 10-4M aluminium chloride or 10-4M aluminium chlorohydrate also increased the ability of MCF-7 cells to invade through a matrigel layer as measured in real time using the xCELLigence system. Although molecular mechanisms remain to be characterized, the ability of aluminium salts to increase migratory and invasive properties of MCF-7 cells suggests that the presence of aluminium in the human breast could influence metastatic processes. This is important because mortality from breast cancer arises mainly from tumour spread rather than from the presence of a primary tumour in the breast.

Interaction of adult human neural crest-derived stem cells with a nanoporous titanium surface is sufficient to induce their osteogenic differentiation

Osteogenic differentiation of various adult stem cell populations such as neural crest-derived stem cells is of great interest in the context of bone regeneration. Ideally, exogenous differentiation should mimic an endogenous differentiation process, which is partly mediated by topological cues. To elucidate the osteoinductive potential of porous substrates with different pore diameters (30 nm, 100 nm), human neural crest-derived stem cells isolated from the inferior nasal turbinate were cultivated on the surface of nanoporous titanium covered membranes without additional chemical or biological osteoinductive cues. As controls, flat titanium without any topological features and osteogenic medium was used. Cultivation of human neural crest-derived stem cells on 30 nm pores resulted in osteogenic differentiation as demonstrated by alkaline phosphatase activity after seven days as well as by calcium deposition after 3 weeks of cultivation. In contrast, cultivation on flat titanium and on membranes equipped with 100 nm pores was not sufficient to induce osteogenic differentiation. Moreover, we demonstrate an increase of osteogenic transcripts including Osterix, Osteocalcin and up-regulation of Integrin β1 and α2 in the 30 nm pore approach only. Thus, transplantation of stem cells pre-cultivated on nanostructured implants might improve the clinical outcome by support of the graft adherence and acceleration of the regeneration process.

Predicting sizes of hexagonal and gyroid metal nanostructures from liquid crystal templating

We describe a method to predict and control the lattice parameters of hexagonal and gyroid mesoporous materials formed by liquid crystal templating. In the first part, we describe a geometric model with which the lattice parameters of different liquid crystal mesophases can be predicted as a function of their water/surfactant/oil volume fractions, based on certain geometric parameters relating to the constituent surfactant molecules. We demonstrate the application of this model to the lamellar (LR), hexagonal (H1), and gyroid bicontinuous cubic (V1) mesophases formed by the binary Brij-56 (C16EO10)/water system and the ternary Brij-56/hexadecane/water system. In this way, we demonstrate predictable and independent control over the size of the cylinders (with hexadecane) and their spacing (with water). In the second part, we produce mesoporous platinum using as templates hexagonal and gyroid phases with different compositions and show that in each case the symmetry and lattice parameter of the metal nanostructure faithfully replicate those of the liquid crystal template, which is itself in agreement with the model. This demonstrates a rational control over the geometry, size, and spacing of pores in a mesoporous metal.

Effects of natural weathering on microstructure and mineral composition of cementitious roofing tiles reinforced with fique fibre

The objective of the present work was to evaluate the effects of 14 years of weathering exposition on the microstructure and mineral composition of cementitious roofing tiles, still in service, reinforced with fique fibres (Furcrae gender). The results show that tiles under weathering exposition presented higher water absorption and apparent void volume than tiles under laboratory exposition. The continuous hydration of cement and natural carbonation filled the smaller pores but contrarily the large pores remained in the porous fibre to matrix interface in the samples exposed to weathering. On the other hand, their microstructure presented lower air permeability than samples aged in the internal environment of the laboratory. Besides, in the weathering aged tiles takes place a more intensive hydration process as it was identified greater amount of hydrated phases than in the laboratory aged specimens. The present results contribute to understanding the consequences of tropical weathering on the fibre-cement degradation. (C) 2010 Elsevier Ltd. All rights reserved.

The use of spray drying technology to reduce bitter taste of casein hydrolysate

The utilization of protein hydrolysates in food systems is frequently hindered due to their bitterness and hygroscopicity. Spray drying technology could be an alternative for reducing these problems. The aim of this work was to reduce or to mask the casein hydrolysate bitter taste using spray drying and mixtures of gelatin and soy protein isolate (SPI) as carriers. Six formulations were studied: three with 20% of hydrolysate and 80% of mixture (gelatine/SPI at proportions of 50/50, 40/60 and 60/40%) and three with 30% of hydrolysate and 70% of mixture (gelatine/SPI at proportions of 50/50, 40/60 and 60/40%). The spray-dried formulations were evaluated by SEM, hygroscopicity, thermal behavior (DSC), dissolution, and bitter taste, by a trained sensory panel using a paired-comparison test (free samples vs. spray-dried samples); all samples were presented in powder form. SEM analysis showed mostly spherically shaped particles, with many concavities and some particles with pores. All formulations were oil and water compatible and showed lower hygroscopicity values than free casein hydrolysate. At Aw 0.83, the free hydrolysate showed Tg about 25 degrees C lower than the formulations, indicating that the formulations may be more stable at Aw >= 0.65 since the glass transition should be prevented. The sensory panel found the formulations, tasted in the powder form, to be less bitter (P < 0.05) than the free casein hydrolysate. These results indicated that spray drying of casein hydrolysate with mixtures of gelatin and SPI was successful to attenuate the bitterness of casein hydrolysate. Thus, spray drying widens the possibilities of application of casein hydrolysates. (C) 2009 Elsevier Ltd. All rights reserved.

Near-infrared integral field spectroscopy of the Homunculus nebula around eta Carinae using Gemini/CIRPASS

This work presents the first integral field spectroscopy of the Homunculus nebula around eta Carinae in the near-infrared spectral region (J band). We confirmed the presence of a hole on the polar region of each lobe, as indicated by previous near-IR long-slit spectra and mid-IR images. The holes can be described as a cylinder of height (i.e. the thickness of the lobe) and diameter of 6.5 and 6.0 x 10(16) cm, respectively. We also mapped the blue-shifted component of He I lambda 10830 seen towards the NW lobe. Contrary to previous works, we suggested that this blue-shifted component is not related to the Paddle but it is indeed in the equatorial disc. We confirmed the claim of N. Smith and showed that the spatial extent of the Little Homunculus matches remarkably well the radio continuum emission at 3 cm, indicating that the Little Homunculus can be regarded as a small H II region. Therefore, we used the optically thin 1.3 mm radio flux to derive a lower limit for the number of Lyman-continuum photons of the central source in eta Car. In the context of a binary system, and assuming that the ionizing flux comes entirely from the hot companion star, the lower limit for its spectral type and luminosity class ranges from O5.5 III to O7 I. Moreover, we showed that the radio peak at 1.7 arcsec NW from the central star is in the same line-of-sight of the `Sr-filament` but they are obviously spatially separated, while the blue-shifted component of He I lambda 10830 may be related to the radio peak and can be explained by the ultraviolet radiation from the companion star.

Breaks in the radial oxygen abundance and corotation radius of three spiral galaxies

The correlation between the breaks in the metallicity distribution and the corotation radius of spiral galaxies has been already advocated in the past and is predicted by a chemodynamical model of our Galaxy that effectively introduces the role of spiral arms in the star formation rate. In this work, we present photometric and spectroscopic observations made with the Gemini Telescope for three of the best candidates of spiral galaxies to have the corotation inside the optical disc: IC 0167, NGC 1042 and NGC 6907. We observed the most intense and well-distributed H ii regions of these galaxies, deriving reliable galactocentric distances and oxygen abundances by applying different statistical methods. From these results, we confirm the presence of variations in the gradients of metallicity of these galaxies that are possibly correlated with the corotation resonance.

Nuclear and extended spectra of NGC 1068-I. Hints from near-infrared spectroscopy

We report the first simultaneous zJHK spectroscopy on the archetypical Seyfert 2 galaxy NGC 1068 covering the wavelength region 0.9-2.4 mu m. The slit, aligned in the north-south direction and centred in the optical nucleus, maps a region 300 pc in radius at subarcsec resolution, with a spectral resolving power of 360 km s-1. This configuration allows us to study the physical properties of the nuclear gas including that of the north side of the ionization cone, map the strong excess of continuum emission in the K band and attributed to dust and study the variations, both in flux and profile, in the emission lines. Our results show the following. (1) Mid- to low-ionization emission lines are split into two components, whose relative strengths vary with the position along the slit and seem to be correlated with the jet. (2) The coronal lines are single-peaked and are detected only in the central few hundred of pc from the nucleus. (3) The absorption lines indicate the presence of intermediate age stellar population, which might be a significant contributor to the continuum in the near-IR spectra. (4) Through some simple photoionization models we find photoionization as the main mechanism powering the emitting gas. (5) Calculations using stellar features point to a mass concentration inside the 100-200 pc of about 1010 M(circle dot).

An analysis of the composite stellar population in M32

We obtained long-slit spectra of high signal-to-noise ratio of the galaxy M32 with the Gemini Multi-Object Spectrograph at the Gemini-North telescope. We analysed the integrated spectra by means of full spectral fitting in order to extract the mixture of stellar populations that best represents its composite nature. Three different galactic radii were analysed, from the nuclear region out to 2 arcmin from the centre. This allows us to compare, for the first time, the results of integrated light spectroscopy with those of resolved colour-magnitude diagrams from the literature. As a main result we propose that an ancient and an intermediate-age population co-exist in M32, and that the balance between these two populations change between the nucleus and outside one effective radius (1r(eff)) in the sense that the contribution from the intermediate population is larger at the nuclear region. We retrieve a smaller signal of a young population at all radii whose origin is unclear and may be a contamination from horizontal branch stars, such as the ones identified by Brown et al. in the nuclear region. We compare our metallicity distribution function for a region 1 to 2 arcmin from the centre to the one obtained with photometric data by Grillmair et al. Both distributions are broad, but our spectroscopically derived distribution has a significant component with [Z/Z(circle dot)] <= -1, which is not found by Grillmair et al.

Lithothamnion superpositum (Corallinales; Rhodophyta): First description for the Western Atlantic or rediscovery of a species?

P>Nongeniculate Corallinaceae are poorly known in Brazil. In our endeavor to identify this group of seaweeds along the Brazilian coast we came across some specimens that fit well into the accepted circumscription of Litothamnion Heydrich. Within this genus they could be identified to what has been called L. superpositum Foslie. The specimens were represented by nongeniculate, free living specimens (rhodoliths); lumpy to fruticose growth-form, presenting flared epithallial cells in transversal section; multiporate tetrasporangial conceptacles, with roof protruding above or flush with the surrounding thallus surface; chambers 250-525 mu m in diameter and 150-230 mu m high, roof structured by filaments with 3-5 cells long; and pores in depression. Among the species described from the Brazilian coast, L. heteromorphum (Foslie) Foslie presented anatomical and reproductive characteristics similar to the referred species described from southern Africa and Australia. Therefore, we propose to consider L. heteromorphum as a heterotypic synonym of L. superpositum and extending its distribution to the Western Atlantic.

Two new species of Cnemidophorus (Squamata: Teiidae) of the C. ocellifer group, from Bahia, Brazil

Two new species of Cnemidophorus are described from the right bank of the Sao Francisco river, in the northwestern part of state of Bahia, Brazil. Both species are assigned to the Cnemidophorus ocellifer group and are distinguished from all other congeners on the basis of lepidosis and color pattern. One of them, Cnemidophorus cyanurus, shares with the species of the subgroup of C. littoralis (C. abaetensis, C. littoralis and C. venetacaudus), a bluish green tail, spurs on the heels of males, 6-7 supraciliaries, a high number of femoral pores (27-45), a row of enlarged scales in the dorsal part of the humerus, and 8 to 10 rows of ventral scales. The second species, Cnemidophorus nigrigula, shares with the C. ocellifer subgroup (composed of C. ocellifer, C. mumbuca, C. jalapensis and C. confusionibus) a low number of femoral pores (1421), enlarged scales in the temporal region posterior to the third subocular, 5 supraciliaries, 6 to 8 rows of ventral scales, and a brown tail color. It is also characterized by males being conspicuously larger than females and by females retaining the juvenile color pattern, which is lost in adult males. The latter characteristic has not been reported in any species of the C. ocellifer group before now. The two new species occur sympatrically at Santo Inacio.