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Substituição do óleo de peixe por óleos vegetais em dietas para Jundiá Rhamdia quelen; efeito no desempenho e no perfil de ácidos graxos da composição corporal; Effect of replacement of fish oil with vegetable oils in diets for Silver Catfish Ramdia quelen; effects on whole-body fatty acid composition

Anido, Rodrigo Javier Vargas
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
25.66%
Um incremento constante na piscicultura no sul do Brasil vem sendo observado; este crescimento é ocasionado, em grande parte, pelo cultivo de espécies nativas de interesse comercial como o Jundiá (Rhamdia quelen). A farinha e o óleo de peixe são ingredientes comumente utilizados como fontes lipídicas na elaboração de rações para peixes. Com a estagnação dos recursos pesqueiros, estes ingredientes tornam-se cada vez mais caros, sendo interessante a utilização de fontes alternativas. As principais fontes de óleos vegetais utilizadas como substitutos são: milho, soja, girassol e canola. Estes óleos apresentam altos conteúdos de ácidos graxos da serie n-6, podendo produzir um peixe com uma relação n-3:n-6 baixa e portanto de menor qualidade sob o ponto de vista do consumo humano. O óleo de linhaça (OL), por outro lado, apresenta um alto conteúdo de ácido linolênico (C18:3 n-3, ALN) na sua composição, representando uma alternativa interessante. Dentro dos Siluriformes, o Ictalurus punctatus apresentou uma reduzida capacidade de dessaturação de precursores do tipo ALN para obtenção de concentrações adequadas de ácidos graxos altamente insaturados (HUFAs). Nada se conhece a respeito desta capacidade no Jundiá. Assim...

Propriedades magnéticas e ópticas de nanopartículas; Magnetic and optical properties of nanoparticles

Guilherme Gorgen Lesseux
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/05/2013 Português
Relevância na Pesquisa
25.66%
Compostos nanoestruturados têm atraído cada vez mais atenção do ponto de vista tecnológico devido às inúmeras possibilidades em termos de aplicação nas mais diversas áreas. Além da motivação em termos de aplicação, o aumento da proporção de átomos na superfície em relação ao volume e a redução da dimensionalidade nestes compostos trazem consigo novas questões em física. Com base nisso, o estudo científico sistemático destas questões é fundamental para o desenvolvimento da nanociência e da nanotecnologia de forma geral. No presente trabalho são estudadas propriedades magnéticas de três tipos de nanopartículas (NPs): i) NPs de Au assistidas por óxidos do tipo R2O3 (R = Er e Y) que exibem propriedades ferromagnéticas; ii) NPs metálicas, Au e Ag, com a impureza magnética Er3+ diluída permitindo assim a sondagem microscópica de propriedades físicas por Ressonância de Spin Eletrônico; iii) E, por fim, NPs de NaYF4 mono e codopadas com os íons de terras raras RE = Yb3+, Er3+ e Tm3+ nas quais foi possível verificar o fenômeno de upconversion. Com base em adaptação de métodos estabelecidos na literatura, [1_3] foi desenvolvida uma rota química para a obtenção de NPs de Au com propriedades ferromagnéticas acentuadas pela incorporação de óxidos. A partir da magnetização de saturação em 2 K e baseado em uma análise termogravimétrica (TGA) estimou-se um momento magnético efetivo de aproximadamente 0.2 µB por átomos de Au na superfície das NPs. Além da caracterização magnetometrica típica...

Effect assessment of nanoparticles toxicity in the terrestrial compartment; Avaliação de efeitos de toxicidade de nanopartículas no compartimento terrestre

Gomes, Susana Isabel Lopes
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
25.77%
Over 11 million tons of nanomaterials (NMs) have been produced in 2012 and predictions point the increase in production. Despite predictions and extended usage via consumer products and industry, the understanding of the potential impact of these materials on the environment is virtually absent. The main aim of this thesis is to understand how a selected group of nanomaterials (metal based particles) may impact soil invertebrates, with special focus on the mechanisms of response. Since a case-by-case Environmental Risk Assessment (ERA) of all the emerging contaminants (particularly NMs) is impossible, among others due to time and cost reasons, to gain understanding on the mechanism of action and response is very important to reach a common paradigm. Understanding the modes of action provides predictive characters in cross particle extrapolation. Besides, it also provides insight for the production of new and sustainable materials. Overall, the effects of the selected NMs (Copper and Silver, Titanium and Zirconium oxides) and the respective salt forms, were investigated at the gene expression (using high-throughput tools, microarray and qPCR technology), biochemical (using enzymatic assays for analysis of oxidative stress markers) and organism (survival and reproduction as in OECD test guidelines) levels...

Spatial attention improves reliability of fMRI retinotopic mapping signals in occipital and parietal cortex

Bressler, David W.; Silver, Michael A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.72%
Spatial attention improves visual perception and increases the amplitude of neural responses in visual cortex. In addition, spatial attention tasks and fMRI have been used to discover topographic visual field representations in regions outside visual cortex. We therefore hypothesized that requiring subjects to attend to a retinotopic mapping stimulus would facilitate the characterization of visual field representations in a number of cortical areas. In our study, subjects attended either a central fixation point or a wedge-shaped stimulus that rotated about the fixation point. Response reliability was assessed by computing coherence between the fMRI time series and a sinusoid with the same frequency as the rotating wedge stimulus. When subjects attended to the rotating wedge instead of ignoring it, the reliability of retinotopic mapping signals increased by approximately 50% in early visual cortical areas (V1, V2, V3, V3A/B, V4) and ventral occipital cortex (VO1) and by approximately 75% in lateral occipital (LO1, LO2) and posterior parietal (IPS0, IPS1 and IPS2) cortical areas. Additionally, one 5-minute run of retinotopic mapping in the attention-to-wedge condition produced responses as reliable as the average of three to five (early visual cortex) or more than five (lateral occipital...

Inhibition of experimental auto-immune uveitis by the A3 adenosine receptor agonist CF101

BAR-YEHUDA, SARA; LUGER, DROR; OCHAION, AVIVIT; COHEN, SHIRA; PATOKAA, RENANA; ZOZULYA, GALINA; SILVER, PHYLLIS B.; DE MORALES, JOSE MARIA GARCIA RUIZ; CASPI, RACHEL R.; FISHMAN, PNINA
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.66%
Uveitis is an inflammation of the middle layer of the eye with a high risk of blindness. The Gi protein associated A3 adenosine receptor (A3AR) is highly expressed in inflammatory cells whereas low expression is found in normal cells. CF101 is a highly specific agonist at the A3AR known to induce a robust anti-inflammatory effect in different experimental animal models. The CF101 mechanism of action entails down-regulation of the NF-κB-TNF-α signaling pathway, resulting in inhibition of pro-inflammatory cytokine production and apoptosis of inflammatory cells. In this study the effect of CF101 on the development of retinal antigen interphotoreceptor retinoid-binding protein (IRBP)-induced experimental autoimmune uveitis (EAU) was assessed. Oral treatment with CF101 (10 μg/kg, twice daily), initiated upon disease onset, improved uveitis clinical score measured by fundoscopy and ameliorated the pathological manifestations of the disease. Shortly after treatment with CF101 A3AR expression levels were down-regulated in the lymph node and spleen cells pointing towards receptor activation. Downstream events included a decrease in PI3K and STAT-1 and proliferation inhibition of IRBP auto-reactive T cells ex vivo. Inhibition of interleukin-2...

Observation of Coalescence Process of Silver Nanospheres During Shape Transformation to Nanoprisms

Yu, Pyng; Huang, Jane; Tang, Jau
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 28/09/2010 Português
Relevância na Pesquisa
25.94%
In this report, we observed the growth mechanism and the shape transformation from spherical nanoparticles (diameter ~6 nm) to triangular nanoprisms (bisector length ~100 nm). We used a simple direct chemical reduction method and provided evidences for the growth of silver nanoprisms via a coalescence process. Unlike previous reports, our method does not rely upon light, heat, or strong oxidant for the shape transformation. This transformation could be launched by fine-tuning the pH value of the silver colloidal solution. Based on our extensive examination using transmission electron microscopy, we propose a non-point initiated growth mechanism, which is a combination of coalescence and dissolution–recrystallization process during the growth of silver nanoprisms.

Lifetime analysis of individual-atom contacts and crossover to geometric-shell structures in unstrained silver nanowires

Obermair, Christian; Kuhn, Holger; Schimmel, Thomas
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 03/11/2011 Português
Relevância na Pesquisa
25.84%
We study the crossover of quantum point contacts from (i) individual-atom contacts to (ii) electronic-shell effects and finally to (iii) geometric-shell effects in electrochemically deposited silver contacts. The method allows the fabrication of mechanically unstrained structures, which is a requirement for determining the individual atomic configuration by means of a detailed lifetime analysis of their conductance. Within the geometric-shell model, the sequence of conductance maxima is explained quantitatively based on the crystal structure data of silver, and the growth mechanism of the nanowires is discussed.

A facile approach to a silver conductive ink with high performance for macroelectronics

Tao, Yu; Tao, Yuxiao; Wang, Biaobing; Wang, Liuyang; Tai, Yanlong
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 25/06/2013 Português
Relevância na Pesquisa
25.87%
An unusual kind of transparent and high-efficiency organic silver conductive ink (OSC ink) was synthesized with silver acetate as silver carrier, ethanolamine as additive, and different kinds of aldehyde-based materials as reduction agents and was characterized by using a thermogravimetric analyzer, X-ray diffraction, a scanning electron microscope, and a four-point probe. The results show that different reduction agents all have an important influence on the conductive properties of the ink through a series of complex chemical reactions, and especially when formic acid or dimethylformamide was used as the reduction agent and sintered at 120°C for 30 s, the resistivity can be lowered to 6 to 9 μΩ·cm. Furthermore, formula mechanism, conductive properties, temperature, and dynamic fatigue properties were investigated systematically, and the feasibility of the OSC ink was also verified through the preparation of an antenna pattern.

Surface Defects on Plate-Shaped Silver Nanoparticles Contribute to Its Hazard Potential in a Fish Gill Cell Line and Zebrafish Embyos

George, Saji; Lin, Sijie; Ji, Zhaoxia; Thomas, Courtney; Li, LinJiang; Mecklenburg, Mathew; Meng, Huan; Wang, Xiang; Zhang, Haiyuan; Xia, Tian; Lin, Shuo; Hohman, J. Nathan; Zink, Jeffrey I.; Weiss, Paul; Nel, André E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.66%
We investigated and compared nano-size Ag spheres, plates, and wires in a fish gill epithelial cell line (RT-W1) and in zebrafish embryos to understand the mechanism of toxicity of an engineered nanomaterial raising considerable environmental concern. While most of the Ag nanoparticles induced N-acetyl cysteine sensitive toxic oxidative stress effects in RT-W1, Ag nanoplates were considerably more toxic than other particle shapes. Interestingly, while Ag ion shedding and bioavailability failed to explain the high toxicity of the nanoplates, cellular injury required direct particle contact, resulting in cell membrane lysis in RT-W1 as well as red blood cells (RBC). Ag nanoplates were also considerably more toxic in zebrafish embryos in spite of their lesser ability to shed Ag into the exposure medium. In order to elucidate the “surface reactivity” of Ag nanoplates, high-resolution transmission electron microscopy was performed and demonstrated a high level of crystal defects (stacking faults and point defects) on the nanoplate surfaces. Surface coating with cysteine was used to passivate the surface defects and demonstrated a reduction of toxicity in RT-W1 cells, RBC, and zebrafish embryos. This study demonstrates the important role of crystal defects in contributing to Ag nanoparticle toxicity in addition to the established roles of Ag ion shed from spherical nanoparticles. The excellent correlation between the in vitro and in vivo toxicological assessment illustrates the utility of using a fish cell line in parallel with zebrafish embryos to perform a predictive environmental toxicological paradigm.

Genetic Analysis of the Cardiac Methylome at Single Nucleotide Resolution in a Model of Human Cardiovascular Disease

Johnson, Michelle D.; Mueller, Michael; Adamowicz-Brice, Martyna; Collins, Melissa J.; Gellert, Pascal; Maratou, Klio; Srivastava, Prashant K.; Rotival, Maxime; Butt, Shahena; Game, Laurence; Atanur, Santosh S.; Silver, Nicholas; Norsworthy, Penny J.; Lan
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/12/2014 Português
Relevância na Pesquisa
25.66%
Epigenetic marks such as cytosine methylation are important determinants of cellular and whole-body phenotypes. However, the extent of, and reasons for inter-individual differences in cytosine methylation, and their association with phenotypic variation are poorly characterised. Here we present the first genome-wide study of cytosine methylation at single-nucleotide resolution in an animal model of human disease. We used whole-genome bisulfite sequencing in the spontaneously hypertensive rat (SHR), a model of cardiovascular disease, and the Brown Norway (BN) control strain, to define the genetic architecture of cytosine methylation in the mammalian heart and to test for association between methylation and pathophysiological phenotypes. Analysis of 10.6 million CpG dinucleotides identified 77,088 CpGs that were differentially methylated between the strains. In F1 hybrids we found 38,152 CpGs showing allele-specific methylation and 145 regions with parent-of-origin effects on methylation. Cis-linkage explained almost 60% of inter-strain variation in methylation at a subset of loci tested for linkage in a panel of recombinant inbred (RI) strains. Methylation analysis in isolated cardiomyocytes showed that in the majority of cases methylation differences in cardiomyocytes and non-cardiomyocytes were strain-dependent...

Two Novel Motifs of Watermelon Silver Mottle Virus NSs Protein Are Responsible for RNA Silencing Suppression and Pathogenicity

Huang, Chung-Hao; Hsiao, Weng-Rong; Huang, Ching-Wen; Chen, Kuan-Chun; Lin, Shih-Shun; Chen, Tsung-Chi; Raja, Joseph A. J.; Wu, Hui-Wen; Yeh, Shyi-Dong
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 20/05/2015 Português
Relevância na Pesquisa
25.88%
The NSs protein of Watermelon silver mottle virus (WSMoV) is the RNA silencing suppressor and pathogenicity determinant. In this study, serial deletion and point-mutation mutagenesis of conserved regions (CR) of NSs protein were performed, and the silencing suppression function was analyzed through agroinfiltration in Nicotiana benthamiana plants. We found two amino acid (aa) residues, H113 and Y398, are novel functional residues for RNA silencing suppression. Our further analyses demonstrated that H113 at the common epitope (CE) (109KFTMHNQ117), which is highly conserved in Asia type tospoviruses, and the benzene ring of Y398 at the C-terminal β-sheet motif (397IYFL400) affect NSs mRNA stability and protein stability, respectively, and are thus critical for NSs RNA silencing suppression. Additionally, protein expression of other six deleted (ΔCR1-ΔCR6) and five point-mutated (Y15A, Y27A, G180A, R181A and R212A) mutants were hampered and their silencing suppression ability was abolished. The accumulation of the mutant mRNAs and proteins, except Y398A, could be rescued or enhanced by co-infiltration with potyviral suppressor HC-Pro. When assayed with the attenuated Zucchini yellow mosaic virus vector in squash plants, the recombinants carrying individual seven point-mutated NSs proteins displayed symptoms much milder than the recombinant carrying the wild type NSs protein...

Acute silver toxicity in aquatic animals is a function of sodium uptake rate

Bianchini, Adalto; Grosell, Martin; Gregory, Sean; Wood, Chris
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.87%
On the basis of these facts about freshwater fish and invertebrates: (i) the Na+ turnover is a physiological process associated with the gill membranes; (ii) the key mechanism of acute silver toxicity consists of reduction in Na+ uptake by blockade of gill Na+,K+-ATPase; (iii) the massspecific surface area of the gills depends on animal body mass; and (iv) the gill surface is also the major site of Na+ loss by diffusion, we hypothesized that whole body Na+ uptake rate (i.e., turnover rate) and secondarily body mass would be good predictors of acute silver toxicity. Results obtained from toxicological (LC50 of AgNO3) and physiological (22Na uptake rate) tests performed on juvenile fish (rainbow trout, Oncorhynchus mykiss), early juvenile and adult crayfish (Cambarus diogenes diogenes), and neonate and adult daphnids (Daphnia magna) in moderately hard water of constant quality support the above hypothesis. Therefore, sensitivity to AgNO3, in terms of either total measured silver or free Ag+, was reliably predicted from the whole body Na+ uptake rate in animals with body mass ranging over 6 orders of magnitude (from micrograms to grams). A positive log-log correlation between acute AgNO3 toxicity and body mass of the same species was also observed. Furthermore...

The microeconomics of bullionism : arbitrage, smuggling and silver outflows in Spain in the early 18th century

Nogues-Marco, Pilar
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: info:eu-repo/semantics/draft; info:eu-repo/semantics/workingPaper Formato: application/pdf
Publicado em /06/2011 Português
Relevância na Pesquisa
66%
In the Early Modern period, there was a systematic flow of precious metals from the American colonies to Spain and Portugal and, from there, throughout the world. In this paper, I use newly discovered data on the black market for silver in Cadiz to reconstruct a picture of Castilian smuggling and international silver flows in the Age of Bullionism (1729-1741). The arbitrage equation shows persistent violations of the silver-point that made arbitrage systematically profitable until devaluation pegged the exchange rate to the arbitrated parity. Market structure explains the persistent violations. The Cadiz shadow price was lower than the international market price because bullionist regulations configured an oligopsonistic structure. The price gap was the reason for the Castilian silver outflows to Europe

Mass spectrometry as a tool to dissect the role of chromatin assembly factors in regulating nucleosome assembly

Gharib, Marlène
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
Relevância na Pesquisa
25.9%
L'assemblage des nucléosomes est étroitement couplée à la synthèse des histones ainsi qu’à la réplication et la réparation de l’ADN durant la phase S. Ce processus implique un mécanisme de contrôle qui contribue soigneusement et de manière régulée à l’assemblage de l’ADN en chromatine. L'assemblage des nucléosomes durant la synthèse de l’ADN est crucial et contribue ainsi au maintien de la stabilité génomique. Cette thèse décrit la caractérisation par spectrométrie de masse(SM) des protéines jouant un rôle critique dans l’assemblage et le maintien de la structure chromatinienne. Plus précisément, la phosphorylation de deux facteurs d’assemblage des nucléosome, le facteur CAF-1, une chaperone d’histone qui participe à l'assemblage de la chromatine spécifiquement couplée à la réplication de l'ADN, ainsi que le complexe protéique Hir, jouant de plus un rôle important dans la régulation transcriptionelle des gènes d’histones lors de la progression normale du cycle cellulaire et en réponse aux dommages de l'ADN, a été examiné. La caractérisation des sites de phosphorylation par SM nécéssite la séparation des protéines par éléctrophorèse suivi d’une coloration a l’argent. Dans le chapitre 2...

Nanopartículas de prata : biossíntese, investigação das atividades antibacteriana, antifúngica e citotoxicidade; Silver nanoparticles : biosynthesis, investigation of antibacterial and antifungal activity and cytotoxicity

Juliana de Cassia Silva Prado
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/01/2014 Português
Relevância na Pesquisa
35.96%
Com o objetivo de entender melhor a toxicidade das nanopartículas de prata biogênicas, estas foram preparadas utilizando a rota biotecnológica e extracelular com o fungo Fusarium oxysporum. As nanopartículas de prata biogênicas foram caracterizadas por microscopia eletrônica de transmissão (TEM) e absorbância na região do UV/Visível. O tamanho das nanopartículas foi determinado pela a técnica de análise de rastreamento de nanopartículas (NTA) utilizando o equipamento NanoSight, e por espectroscopia de correlação de fótons utilizando o equipamento ZetaSizer. O potencial zeta das partículas também foi avaliado no ZetaSizer. A atividade antimicrobiana, a citotoxicidade e os mecanismos de ação das nanopartículas de prata biogênicas em células V79 também foram investigados. A produção de nanopartículas de prata foi evidenciada pela presença da banda de absorção de plasma ('lâmbda' = 450 nm) e por TEM sendo observadas partículas esféricas com o tamanho de 15-22 nm. A atividade antibacteriana e antifúngica das nanopartículas de prata foi avaliada contra Staphylococcus aureus (MIC 1,47 µg mL-1), Salmonella typhymurium (MIC 0,36 µg mL-1), Escherichia coli (MIC 0,73 µg mL-1), Aspergillus niger (MIC 5,90 µg mL-1) e Trichophytum rubrum (MIC 2...

Atomistic simulation of single crystal copper nanowires under tensile stress: Influence of silver impurities in the emission of dislocations

Ignat Deleanu, Mihail Theodor; Gutiérrez, G.; Amigo, N.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo de revista
Português
Relevância na Pesquisa
25.94%
Artículo de publicación ISI; The transition from elastic to plastic behaviour in single crystal copper nanowires under uniaxial tensile stress at different concentrations of silver (0.0–0.5 at.% Ag) and at different temperatures (0.1, 100, and 300 K) using the molecular dynamics method is investigated. The tensile stress is applied along h100i crystallographic orientation and the silver atoms are placed randomly on the surface of the nanowire, as substitutional point defect. The simulations indicate that silver atoms lower slightly the unstable stacking fault energy, making them act as sources of partial dislocation nucleation, due to the local strain field they produce in the lattice structure. The defects generated in the material also act as sources for nucleation, giving rise to a competition of two mechanism. Also, it is observed that the yield point decreases with the temperature and the presence of impurities.; This work is supported by a Codelco-IM2 Grant. NA thanks Conicyt fellowship and GG acknowledges partial support from Fondecyt- Chile 1120603.

Holographic Point-of-Care Diagnostic Devices

Yetisen, Ali Kemal
Fonte: Springer; University of Cambridge; Department of Chemical Engineering and Biotechnology Publicador: Springer; University of Cambridge; Department of Chemical Engineering and Biotechnology
Tipo: Thesis; doctoral; PhD
Português
Relevância na Pesquisa
35.9%
Developing non-invasive and accurate diagnostics that are easily manufactured, robust and reusable will provide monitoring of high-risk individuals in any clinical or point-of-care environment, particularly in the developing world. There is currently no rapid, low-cost and generic sensor fabrication technique capable of producing narrow-band, uniform, reversible colorimetric readouts with a high-tuneability range. This thesis aims to present a theoretical and experimental basis for the rapid fabrication, optimisation and testing of holographic sensors for the quantification of pH, organic solvents, metal cations, and glucose in solutions. The sensing mechanism was computationally modelled to optimise its optical characteristics and predict the readouts. A single pulse of a laser (6 ns, 532 nm, 350 mJ) in holographic ?Denisyuk? reflection mode allowed rapid production of sensors through silver-halide chemistry, in situ particle size reduction and photopolymerisation. The fabricated sensors consisted of off-axis Bragg diffraction gratings of ordered silver nanoparticles and localised refractive index changes in poly(2-hydroxyethyl methacrylate) and polyacrylamide films. The sensors exhibited reversible Bragg peak shifts, and diffracted the spectrum of narrow-band light over the wavelength range ?peak ? 500-1100 nm. The application of the holographic sensors was demonstrated by sensing pH in artificial urine over the physiological range (4.5-9.0)...

A Study of the effect of coating variations on resolution performance in the single-phase association product plates

Chen, Te-Chung
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
25.79%
Most people conceive of lithography as a planographic method of printing. In point of fact, only some of the original lithographic plates had truly planographic surfaces. Most lithographic plates used in industry today do not have the same material in the image and non-image areas, so they are called double-phase plates . Because of light undercutting and the roughness of the grain structure of the carrier, the use of conventional double-phase plates for fine image reproduction, where resolution is the main concern, has been limited. The purpose of this study was to determine the image formation mechanism of single-phase plates (i.e. plates with image and non-image areas on the same plane and made of the same material . ) by investigating the resolution performance of Association Product plates. There are good reasons to believe that Association Product plates give better resolution than conventional double-phase plates. A comparative study of the resolving power of Association Product plates and commonly used double phase plates provides information about the quantitative difference of resolution between these two types of plates. In choosing to study the image-forming mechanism from the coating variations point-of-view, it was hoped to arrive at a demonstrable independence of plate resolving power from plate coating thickness in the single-phase plate. Results of the experiment showed that coating thickness and grain structure of the plate base does not affect the resolving power of this type of plate. The main factor which directly affects the resolving power is the exposure time.

A Study of the effect of coating variations on resolution performance in the single-phase association product plates

Chen, Te-Chung
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
25.79%
Most people conceive of lithography as a planographic method of printing. In point of fact, only some of the original lithographic plates had truly planographic surfaces. Most lithographic plates used in industry today do not have the same material in the image and non-image areas, so they are called double-phase plates . Because of light undercutting and the roughness of the grain structure of the carrier, the use of conventional double-phase plates for fine image reproduction, where resolution is the main concern, has been limited. The purpose of this study was to determine the image formation mechanism of single-phase plates (i.e. plates with image and non-image areas on the same plane and made of the same material . ) by investigating the resolution performance of Association Product plates. There are good reasons to believe that Association Product plates give better resolution than conventional double-phase plates. A comparative study of the resolving power of Association Product plates and commonly used double phase plates provides information about the quantitative difference of resolution between these two types of plates. In choosing to study the image-forming mechanism from the coating variations point-of-view, it was hoped to arrive at a demonstrable independence of plate resolving power from plate coating thickness in the single-phase plate. Results of the experiment showed that coating thickness and grain structure of the plate base does not affect the resolving power of this type of plate. The main factor which directly affects the resolving power is the exposure time.

Shape transformation from silver triangular nanoprisms to nanodisks: Raman characterization and sculpturing mechanism

López,I.A.; Ceballos,M.; Hernández,G.; Acosta,L.; Gómez,I.
Fonte: Sociedad Mexicana de Física Publicador: Sociedad Mexicana de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 Português
Relevância na Pesquisa
35.92%
The sculpturing action of chloride ions on silver nanoplates is investigated. Recent reports show that the shape transformation from silver triangular nanoprisms to nanodisks by addition of chloride ion occurs after a threshold concentration. In this work, a chemical study of this threshold concentration is presented. There is theoretical and experimental evidence that the morphological change only depends on the chloride ion concentration and not on the Cl-/Ag molar ratio. Besides, the chloride ion etching ability is attributed to the (AgCl)° complex, which controls the morphology change through a stepwise process where a silver atom is removed from the (110) plane, and is subsequently deposited on the (111) plane (i.e. from the nanoplate vertex to the basal plane). The threshold chloride ion concentration in the shape transformation coincides with the point where Ag+ ion and (AgCl)° concentrations are the same. On the other hand, the quantitative formation of AgCl-2 avoids the stepwise process, and then the colloidal system is destabilized. Furthermore, the analysis of the Raman spectra supports the transformation mechanisms.