21,589 research outputs found
DigitalPinDirector: A digital pinscreen editor for images and realtime animation in low cost personal computers
This paper presents the main characteristics of the traditional Pinscreen, the way it works, its problems and results achieved. The first Digital Pinscreen system is presented, along with its main characteristics and limitations. The rest of the paper describes and presents the DigitalPinDirector: a system that enables a full and true creative access to
the unique visual and animation characteristics of the Pinscreen.info:eu-repo/semantics/publishedVersio
Impact of biofilms in simulated drinking water and urban heat supply systems
Biofouling and biocorrosion were studied in drinking water
and heating water systems by forming biofilms on steel and on
polymethylmetacrylate. In the drinking water system, biofilm development
was more significant on corroded surfaces, suggesting that in these conditions
they were largely protected from disinfection, probably because of sheltering
and chlorine demand by corrosion products. In the urban heat supply system,
results suggest a higher biofilm activity at lower pH. Sulphate-reducing
bacteria were detected in the urban heating biofilms, but little corrosion
was observed on steel coupons. Results indicate that surface and bulk
medium properties, as well as bacterial diversity are determinant parameters
when studying biofouling and biocorrosion.Cirius – Danish Centre for
International Cooperation and Mobility in Education and Trainin
Differential mesenteric fat deposition in bovines fed on silage or concentrate is independent of glycerol membrane permeability
© The Animal Consortium 2011In the meat industry, the manipulation of fat deposition in cattle is of pivotal importance to improve production efficiency, carcass composition and ultimately meat quality. There is an increasing interest in the identification of key factors and molecular mechanisms responsible for the development of specific fat depots. This study aimed at elucidating the influence of breed and diet on adipose tissue membrane permeability and fluidity and their interplay on fat deposition in bovines. Two Portuguese autochthonous breeds, Alentejana and Barrosã, recognized as late- and early-maturing breeds, respectively, were chosen to examine the effects of breed and diet on fat deposition and on adipose membrane composition and permeability. Twenty-four male bovines from these breeds were fed on silage-based or concentrate-based diets for 11 months. Animals were slaughtered to determine their live slaughter and hot carcass weights, as well as weights of subcutaneous and visceral adipose depots. Mesenteric fat depots were excised and used to isolate adipocyte membrane vesicles where cholesterol content, fatty acid profile as well as permeability and fluidity were determined. Total accumulation of neither subcutaneous nor visceral fat was influenced by breed. In contrast, mesenteric and omental fat depots weights were higher in concentrate-fed bulls relative to silage-fed animals. Membrane fluidity and permeability to water and glycerol in mesenteric adipose tissue were found to be independent of breed and diet. Moreover, the deposition of cholesterol and unsaturated fatty acids, which may influence membrane properties, were unchanged among experimental groups. Adipose membrane lipids from the mesenteric fat depot of ruminants were rich in saturated fatty acids, and unaffected by polyunsaturated fatty acids dietary levels. Our results provide evidence against the involvement of cellular membrane permeability to glycerol on fat accumulation in mesenteric fat tissue of concentrate-fed bovines, which is consistent with the unchanged membrane lipid profile found among experimental groups.This study was supported by Fundação para a Ciência e a Tecnologia (FCT) through grant PTDC/CVT/2006/66114 and individual fellowships to Ana P. Martins (SFRH/BD/2009/65046), Ana S. H. Costa (SFRH/BD/2009/61068) and Susana V. Martins (SFRH/BPD/2009/63019). Paula A. Lopes is a researcher from the program ‘‘Ciência 2008’’ from FC
The influence of surface material on the development of Desulfovibrio desulfuricans biofilms
Sulphate reducing bacteria have an important role in the sulphur cycle, and therefore in wastewater treatment
systems. They are able to form biofilms on metallic surfaces, leading to fouling and corrosion problems.
Additionally, hydrogen sulphide that is a product of their metabolism can cause serious health risks. In this study,
sulphate reducing bacteria (SRB) biofilms were developed on stainless steel 304 and on polycarbonate in order to
evaluate surface effect on biofilm formation.
Results showed that the biofilm formed on stainless steel presented higher metabolic activity, confirmed by lactate
and sulfate removals. Metal elements present in stainless steel may affect SRB activity. This can be the case of
nickel that represents around 8% of stainless steel 304. Studies performed with suspended cultures of Desulfovibrio
desulfuricans also showed that the presence of nickel in the media had a positive impact on bacterial activity
The influence of nickel on the adhesion ability of Desulfovibrio desulfuricans
The build-up of biofilms on metals surfaces may lead to severe corrosion, especially in the presence of sulphate-reducing bacteria (SRB). To prevent the deterioration of material caused by biofilms it is necessary to understand the processes governing biofilm development including mechanisms of cell adhesion. Additionally, corrosion of metallic surfaces due to bacteria may lead to the dissolution of metallic elements that may
further affect adhesion and biofilm development. A study was carried out to evaluate how the presence of nickel in the substrata affects the adhesion
ability of Desulfovibrio desulfuricans. The substrata tested were stainless steel 304 (SS), metallic nickel (Ni) and polymethylmetacrylate (PMMA), a non-metallic material used as control. The influence of nickel on SRB growth and its relation to adhesion was also checked. A statistically
significant difference in the number of adhered cells to the materials tested was detected, with higher bacterial number on nickel, followed by SS and finally by PMMA. The higher number of SRB adhered to steel compared with PMMA may be explained by differences in hydrophobicity, in
roughness and in the electron-acceptor character of the substrata. Additionally, bacterial growth was found to be positively affected by the presence of nickel as revealed by a significant increase in the specific growth rate of SRB in the presence of increased nickel concentrations.Programme Praxis XXI
The effect of dissolved stainless steel alloy elements on the activity and growth of SRB
Sulphate reducing bacteria have an important role in the sulphur cycle, and therefore in
wastewater treatment systems. They are able to form biofilms on metallic surfaces, leading to
fouling and corrosion problems. These bacteria are among the micro-organisms most
frequently implicated in microbial corrosion of iron and ferrous alloys.
Alloying elements added to steels for the improvement of their corrosion resistance such as
molybdenum and nickel can be dissolved in bulk liquid during the corrosion processes and
therefore available to the micro-organisms. That may affect bacterial metabolism and adhesion.
In this study, suspended cultures of sulphate reducing bacteria (SRB) were subjected to several
nickel concentrations in order to evaluate the effect of the dissolved metal on bacterial
metabolism. Simultaneously, SRB biofilms were developed on stainless steel 304 and on polymethylmethacrylate
(PMMA) in order to study surface effect on biofilm formation. Results
showed that nickel (Ni) in all tested concentrations between 0.006 and 5 mg/L had a positive
effect on the growth of Desuljovibrio desulfuricans. Additionally, biofilms formed on stainless
steel presented higher metabolic activity, confirmed by sulphate removal and acetate
concentration in the effluent stream. Metal elements present in stainless steel may affect SRB
activity. This can be the case of nickel that represents around 8% of stainless steel 304 and that
had a positive impact on suspended SRB cultures, under the tested concentrations
Instanton Corrected Non-Supersymmetric Attractors
We discuss non-supersymmetric attractors with an instanton correction in Type
IIA string theory compactified on a Calabi-Yau three-fold at large volume. For
a stable non-supersymmetric black hole, the attractor point must minimize the
effective black hole potential. We study the supersymmetric as well as
non-supersymmetric attractors for the D0-D4 system with instanton corrections.
We show that in simple models, like the STU model, the flat directions of the
mass matrix can be lifted by a suitable choice of the instanton parameters.Comment: Minor modifications, Corrected typos, 38 pages, 1 figur
The role of bacteria in pine wilt disease: insights from microbiome analysis.
Pine Wilt Disease (PWD) has a significant impact on Eurasia pine forests. The microbiome of the nematode (the primary cause of the disease), its insect vector, and the host tree may be relevant for the disease mechanism. The aim of this study was to characterize these microbiomes, from three PWD-affected areas in Portugal, using Denaturing Gradient Gel Electrophoresis, 16S rRNA gene pyrosequencing, and a functional inference-based approach (PICRUSt). The bacterial community structure of the nematode was significantly different from the infected trees but closely related to the insect vector, supporting the hypothesis that the nematode microbiome might be in part inherited from the insect. Sampling location influenced mostly the tree microbiome (P < 0.05). Genes related both with plant growth promotion and phytopathogenicity were predicted for the tree microbiome. Xenobiotic degradation functions were predicted in the nematode and insect microbiomes. Phytotoxin biosynthesis was also predicted for the nematode microbiome, supporting the theory of a direct contribution of the microbiome to tree-wilting. This is the first study that simultaneously characterized the nematode, tree and insect-vector microbiomes from the same affected areas, and overall the results support the hypothesis that the PWD microbiome plays an important role in the disease's development
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