Two novel reports of semidry stigmatic surface in Asteraceae

Research documents related to the morphology and function of style branches and stigmatic surface of Asteraceae are still rather few, and the literature reports are thus controversial. We report in the present study that the stigmatic surfaces of two non-related species of Asteraceae (Lessingianthus grandiflorus and Lucilia lycopodioides) have features of semidry stigmas. Sporodermis of both species was also analyzed so that we could understand how the stigmatic surface works during pollen deposition and rehydration. Stylar branches and pollen grains (sporodermis) were studied using scanning and transmission electron microscopy (SEM and TEM) and histochemistry techniques. The inner and marginal bands of stylar branches in these species display intermediary features between the dry and wet types of stigma: the cuticle characterizes the dry stigma and cells with secretory activity characterize the wet stigma; these showed differences from what has been described to the Asteraceae family, where stigmatic surface of species from several tribes is considered dry. Pollen grains are medium-size to large with exine ornamentation (echinate and echinolophate) and abundant secretion which latter characterizes pollenkitt. We can assume that two processes might help pollen grain hydration on stigmatic surface in Lessingianthus grandiflorus and Lucilia lycopodioides: (1) the presence of pollenkitt, as observed in the secretory content inside exine cavities and around pollen grains; and (2) the secretory activity of stigmatic surface cells, whose secretion accumulates among intercellular and subcuticular spaces and leads to cuticle disruption during the floral receptive phase. Our results suggest that ultrastructural and histochemical studies should be considered when describing stigmatic surface and that the ""semidry"" feature within Asteraceae should be investigated still more in detail, so that the taxonomic or adaptation value of this trait in the family can be verified. (C) 2010 Elsevier GmbH. All rights reserved.

Quantification and source identification of atmospheric particulate polycyclic aromatic hydrocarbons and their dry deposition fluxes at three sites in Salvador Basin, Brazil, impacted by mobile and stationary sources

The present work has aimed to determine the 16 US EPA priority PAH atmospheric particulate matter levels present in three sites around Salvador, Bahia: (i) Lapa bus station, strongly impacted by heavy-duty diesel vehicles; (ii) Aratu harbor, impacted by an intense movement of goods, and (iii) Bananeira village on Maré Island, a non vehicle-influenced site with activities such as handcraft work and fisheries. Results indicated that BbF (0.130-6.85 ng m-3) is the PAH with highest concentration in samples from Aratu harbor and Bananeira and CRY (0.075-6.85 ng m-3) presented higher concentrations at Lapa station. PAH sources from studied sites were mainly of anthropogenic origin such as gasoline-fueled light-duty vehicles and diesel-fueled heavy-duty vehicles, discharges in the port, diesel burning from ships, dust ressuspension, indoor soot from cooking, and coal and wood combustion for energy production.

Bovine gene polymorphisms related to fat deposition and meat tenderness

Leptin, thyroglobulin and diacylglycerol O-acyltransferase play important roles in fat metabolism. Fat deposition has an influence on meat quality and consumers' choice. The aim of this study was to determine allele and genotype frequencies of polymorphisms of the bovine genes, which encode leptin (LEP), thyroglobulin (TG) and diacylglycerol O-acyltransferase (DGAT1). A further objective was to establish the effects of these polymorphisms on meat characteristics. We genotyped 147 animals belonging to the Nelore (Bos indicus), Canchim (5/8 Bos taurus + 3/8 Bos indicus), Rubia Gallega X Nelore (1/2 Bos taurus + 1/2 Bos indicus), Brangus Three-way cross (9/16 Bos taurus + 7/16 Bos indicus) and Braunvieh Three-way cross (3/4 Bos taurus + 1/4 Bos indicus) breeds. Backfat thickness, total lipids, marbling score, ribeye area and shear force were fitted, using the General Linear Model (GLM) procedure of the SAS software. The least square means of genotypes and genetic groups were compared using Tukey's test. Allele frequencies vary among the genetic groups, depending on Bos indicus versus Bos taurus influence. The LEP polymorphism segregates in pure Bos indicus Nelore animals, which is a new finding. The T allele of TG is fixed in Nelore, and DGAT1 segregates in all groups, but the frequency of allele A is lower in Nelore animals. The results showed no association between the genotypes and traits studied, but a genetic group effect on these traits was found. So, the genetic background remains relevant for fat deposition and meat tenderness, but the gene markers developed for Bos taurus may be insufficient for Bos indicus.

Pollen sources of the orchid bee Euglossa annectans Dressler 1982 (Hymenoptera: Apidae, Euglossini) analyzed from larval provisions

In order to analyze the pollen resources used by the orchid bee Euglossa annectans, samples of larval provisions from cells under construction were taken from 12 different trap nests (wooden boxes) on Santa Catarina Island, southern Brazil. The 43 samples collected between 2002 and 2005 represented all months except December. Overall, 74 pollen types from 24 families were distinguished. Among the 26 pollen types that reached more than 10% in monthly means, the families Melastomataceae, Bromeliaceae, Ochnaceae, Fabaceae, and Myrtaceae were most frequently represented. The Shannon-Weaver diversity index H' for the 43 brood cells varied from 0.10-1.65 and the annual diversity was 0.98. Similarity indices ranged from 0 to 0.87 and were highest during spring and summer. The results characterize E. annectans as a polylectic species. Based on these data, we can conclude that Euglossa females may act as pollinators of many forest species.

Abnormal collagen deposition in synovia after collagen type V immunization in rabbits

Sinovitis in Scleroderma (SSc) is rare, usually aggressive and fully resembles rheumatoid arthritis. Experimental models of SSc have been used in an attempt to understand its pathogenesis. Previous studies done in our laboratory had already revealed the presence of a synovial remodeling process in rabbits immunized with collagen V. To validate the importance of collagen type V and to explore the quantitative relationship between this factor and synovia remodeling as well as the relationship between collagen type V and other collagens, we studied the synovial tissue in immunized rabbits. Rabbits (N= 10) were immunized with collagen V plus Freund's adjuvant and compared with animals inoculated with adjuvant only (N= 10). Synovial tissues were submitted to histological analysis, immunolocalization to collagen I, III and V and biochemical analysis by eletrophoresis, immunoblot and densitometric method. The synovial tissue presented an intense remodeling process with deposits of collagen types I, III and V after 75 and 120 days of immunization, mainly distributed around the vessels and interstitium of synovial extracellular matrix. Densitometric analysis confirmed the increased synthesis of collagen I, III and V chains (407.69 +/- 80.31; 24.46 +/- 2.58; 70.51 +/- 7.66, respectively) in immunized rabbits when compared with animals from control group (164.91 +/- 15.67; 12.89 +/- 1.05; 32 +/- 3.57) (p<0.0001). We conclude that synovial remodeling observed in the experimental model can reflect the articular compromise present in patients with scleroderma. Certainly, this experimental model induced by collagen V immunization will bring new insights in to pathogenic mechanisms and allow the testing of new therapeutic strategies to ameliorate the prognosis for scleroderma patients.

Pollen foraging in colonies of Melipona bicolor (Apidae, Meliponini): effects of season, colony size and queen number

We evaluated the ratio between the number of pollen foragers and the total number of bees entering colonies of Melipona bicolor, a facultative polygynous species of stingless bees. The variables considered in our analysis were: seasonality, colony size and the number of physogastric queens in each colony. The pollen forager ratios varied significantly between seasons; the ratio was higher in winter than in summer. However, colony size and number of queens per colony had no significant effect. We conclude that seasonal differences in pollen harvest are related to the production of sexuals and to the number of individuals and their body size.

Comparative analysis of two sampling techniques for pollen gathered by Nannotrigona testaceicornis Lepeletier (Apidae, Meliponini)

Pollen counts from samples taken from storage pots throughout one year (from October to September) were adjusted by Tasei's volumetric correction coefficient for the determination of pollen sources exploited by two colonies of Nannotrigona testaceicornis in Sao Paulo, Brazil. The results obtained by this sampling technique for seven months (December to June) were compared with those from corbicula load samples taken within the same period. This species visited a large variety of plant species, but few of them were frequently used. As a rule, pollen sources that appeared at frequencies greater than 1% were found with both sampling methods and significant positive correlations (Spearman correlation coefficient) were found between their values. The pollen load sample data showed that N. testaceicornis gathered pollen throughout the external activity period.

A high voltage pulse power supply for metal plasma immersion ion implantation and deposition

We describe the design and implementation of a high voltage pulse power supply (pulser) that supports the operation of a repetitively pulsed filtered vacuum arc plasma deposition facility in plasma immersion ion implantation and deposition (Mepiiid) mode. Negative pulses (micropulses) of up to 20 kV in magnitude and 20 A peak current are provided in gated pulse packets (macropulses) over a broad range of possible pulse width and duty cycle. Application of the system consisting of filtered vacuum arc and high voltage pulser is demonstrated by forming diamond-like carbon (DLC) thin films with and without substrate bias provided by the pulser. Significantly enhanced film/substrate adhesion is observed when the pulser is used to induce interface mixing between the DLC film and the underlying Si substrate. (C) 2010 American Institute of Physics. [doi:10.1063/1.3518969]

Emission and dry deposition of accumulation mode particles in the Amazon Basin

Size-resolved vertical aerosol number fluxes of particles in the diameter range 0.25-2.5 mu m were measured with the eddy covariance method from a 53 m high tower over the Amazon rain forest, 60 km NNW of Manaus, Brazil. This study focuses on data measured during the relatively clean wet season, but a shorter measurement period from the more polluted dry season is used as a comparison. Size-resolved net particle fluxes of the five lowest size bins, representing 0.25-0.45 mu m in diameter, were in general dominated by deposition in more or less all wind sectors in the wet season. This is an indication that the source of primary biogenic aerosol particles may be small in this particle size range. Transfer velocities within this particle size range were observed to increase linearly with increasing friction velocity and increasing particle diameter. In the diameter range 0.5-2.5 mu m, vertical particle fluxes were highly dependent on wind direction. In wind sectors where anthropogenic influence was low, net upward fluxes were observed. However, in wind sectors associated with higher anthropogenic influence, deposition fluxes dominated. The net upward fluxes were interpreted as a result of primary biogenic aerosol emission, but deposition of anthropogenic particles seems to have masked this emission in wind sectors with higher anthropogenic influence. The net emission fluxes were at maximum in the afternoon when the mixed layer is well developed, and were best correlated with horizontal wind speed according to the equation log(10)F = 0.48.U + 2.21 where F is the net emission number flux of 0.5-2.5 mu m particles [m(-2) s(-1)] and U is the horizontal wind speed [ms(-1)] at the top of the tower.

Ethanol electrooxidation onto stepped surfaces modified by Ru deposition: electrochemical and spectroscopic studies

Oxidation of ethanol on ruthenium-modified Pt(775) and Pt(332) stepped electrodes has been studied using electrochemical and FTIR techniques. It has been found that the oxidation of ethanol on these electrodes takes place preferentially on the step sites yielding CO(2) as the major final product. The cleavage of the C-C bond, which is the required step to yield CO(2), occurs only on this type of site. The presence of low ruthenium coverages on the step sites promotes the complete oxidation of ethanol since it facilitates the oxidation of CO formed on the step from the cleavage of the C-C bond. However, high ruthenium coverages have an important inhibiting effect since the adatoms block the step sites, which are required for the cleavage of the C-C bond. Under these conditions, the oxidation current diminishes and the major product in the oxidation process is acetic acid, which is the product formed preferentially on the (111) terrace sites.

Spatio-temporal patterns of throughfall and solute deposition in an open tropical rain forest

The brief interaction of precipitation with a forest canopy can create a high spatial variability of both throughfall and solute deposition. We hypothesized that (i) the variability in natural forest systems is high but depends on system-inherent stability, (ii) the spatial variability of solute deposition shows seasonal dynamics depending on the increase in rainfall frequency, and (iii) spatial patterns persist only in the short-term. The study area in the north-western Brazilian state of Rondonia is subject to a climate with a distinct wet and dry season. We collected rain and throughfall on an event basis during the early wet season (n = 14) and peak of the wet season (n = 14) and analyzed the samples for pH and concentrations of NH4+, Na+, K+, Ca2+ Mg2+,, Cl-, NO3-, SO42- and DOC. The coefficient 3 4 cient of variation for throughfall based on both sampling intervals was 29%, which is at the lower end of values reported from other tropical forest sites, but which is higher than in most temperate forests. Coefficients of variation of solute deposition ranged from 29% to 52%. This heterogeneity of solute deposition is neither particularly high nor particularly tow compared with a range of tropical and temperate forest ecosystems. We observed an increase in solute deposition variability with the progressing wet season, which was explained by a negative correlation between heterogeneity of solute deposition and antecedent dry period. The temporal stability of throughfall. patterns was Low during the early wet season, but gained in stability as the wet season progressed. We suggest that rapid plant growth at the beginning of the rainy season is responsible for the lower stability, whereas less vegetative activity during the later rainy season might favor the higher persistence of ""hot"" and ""cold"" spots of throughfall. quantities. The relatively high stability of throughfall patterns during later stages of the wet season may influence processes at the forest floor and in the soil. Solute deposition patterns showed less clear trends but all patterns displayed a short-term stability only. The weak stability of those patterns is apt to impede the formation of solute deposition -induced biochemical microhabitats in the soil. (C) 2008 Elsevier B.V. All rights reserved.

Residual stresses in titanium nitride thin films obtained with step variation of substrate bias voltage during deposition

In this work, a series of depositions of titanium nitride (TiN) films on M2 and D2 steel substrates were conducted in a Triode Magnetron Sputtering chamber. The temperature; gas flow and pressure were kept constant during each run. The substrate bias was either decreased or increased in a sequence of steps. Residual stress measurements were later conducted through the grazing X-ray diffraction method. Different incident angles were used in order to change the penetration depth and to obtain values of residual stress at different film depths. A model described by Dolle was adapted as an attempt to calculate the values of residual stress at each incident angle as a function of the value from each individual layer. Stress results indicated that the decrease in bias voltage during the deposition has produced compressive residual stress gradients through the film thickness. On the other hand, much less pronounced gradients were found in one of the films deposited with increasing bias voltage. (C) 2010 Elsevier B.V. All rights reserved.

Electrophoretic deposition of ZrO(2)-Y(2)O(3): a bi-component study concerning self-assemblies

There are many industrial advantages of using mechanical multi-oxides mixtures to obtain ceramic parts by electrophoretic deposition (EPD). This is mainly because one could avoid complex chemical synthesis routes to achieve a desirable composition. However, EPD of these suspensions is not an easy task as well since many different surfaces are present, leading to unexpected suspension behavior. The particles surface potentials and interactions can, however, be predicted by an extension of the DLVO theory. Using this theory, one can control the suspension properties and particles distribution. The objective of this work was to apply the colloidal chemistry theories to promote the formation of a heterocoagulation between ZrO(2) and Y(2)O(3) particles in ethanol suspension to achieve a suitable condition for EPD. After identifying a condition where those particles had opposite surface charges and adequate relative sizes, heterocoagulation was observed at operational pH 7.5, generating an organized agglomerate with ZrO(2) particles surrounding Y(2)O(3), with a net zeta potential of -16.6 mV. Since the agglomerates were stable, EPD could be carried out and homogeneous deposits were obtained. The deposited bodies were sintered at 1600 A degrees C for 4 h and partially stabilized ZrO(2) could be obtained without traces of Y(2)O(3) second phases.

Influence of substrate surface topography in the deposition of nanostructured diamond-like carbon films by high density plasma chemical vapor deposition

In this work, we have studied the influence of the substrate surface condition on the roughness and the structure of the nanostructured DLC films deposited by High Density Plasma Chemical Vapor Deposition. Four methods were used to modify the silicon wafers surface before starting the deposition processes of the nanostructured DLC films: micro-diamond powder dispersion, micro-graphite powder dispersion, and roughness generation by wet chemical etching and roughness generation by plasma etching. The reference wafer was only submitted to a chemical cleaning. It was possible to see that the final roughness and the sp(3) hybridization degree strongly depend on the substrate surface conditions. The surface roughness was observed by AFM and SEM and the hybridization degree of the DLC films was analyzed by Raman Spectroscopy. In these samples, the final roughness and the sp(3) hybridization quantity depend strongly on the substrate surface condition. Thus, the effects of the substrate surface on the DLC film structure were confirmed. These phenomena can be explained by the fact that the locally higher surface energy and the sharp edges may induce local defects promoting the nanostructured characteristics in the DLC films. (C) 2008 Elsevier B.V. All rights reserved.

Low-temperature deposition of silicon oxide and silicon nitride by reactive magnetron sputtering

In this study, oxide and nitride films were deposited at room temperature through the reaction of silicon Sputtered by argon and oxygen ions or argon and nitrogen ions at 250 and 350 W with 0.67 Pa pressure. It was observed that for both thin films the deposition rates increase with the applied RF power and decrease with the increase of the gas concentration. The Si/O and Si/N ratio were obtained through RBS analyses and for silicon oxide the values changed from 0.42 to 0.57 and for silicon nitride the Values changed from 0.4 to 1.03. The dielectric constants were calculated through capacitance-voltage curves with the silicon oxide values varying from 2.4 to 5.5, and silicon nitride values varying from 6.2 to 6.7, which are good options for microelectronic dielectrics. (c) 2008 Elsevier Ltd. All rights reserved.