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Low doses of silver nitrate induce pleurodesis with a limited systemic response

MARCHI, Evaldo; VARGAS, Francisco S.; ACENCIO, Milena M. P.; ANTONANGELO, Leila; TEIXEIRA, Lisete R.; LIGHT, Richard W.
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
ENG
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Background and objective: Both talc and 0.5% silver nitrate have been shown to induce effective pleurodesis. However, acute adverse systemic inflammatory effects have been described with both agents. The aim of this study was to assess in rabbits the systemic effects associated with a new technique of pleurodesis using repeated low doses of 0.1% silver nitrate. Methods: Rabbits were injected intrapleurally through a chest tube with 0.1% silver nitrate at 0, 24 and 48 h. Other groups received a single injection of 0.5% silver nitrate or 400 mg/kg of talc. Blood samples were collected at 24, 48 and 72 h, and at 7 days, and cytological and biochemical measurements were performed. After 28 days, the presence of macroscopic pleural adhesions and microscopic pleural fibrosis in the pleural cavity were evaluated. Results: Both talc and 0.5% silver nitrate caused significant increases in blood neutrophils, serum LDH, IL-8, transforming growth factor-beta and CRP in comparison with control at almost all time points, whereas sequential doses of 0.1% silver nitrate only increased LDH and CRP in the first 24 h and transforming growth factor-beta at all time points. All groups showed efficient pleurodesis, with no differences in pleural adhesions or fibrosis. Conclusions: Sequential doses of 0.1% silver nitrate produced efficient pleurodesis in rabbits...

Synthesis and characterization of silver/alanine nanocomposites for radiation detection in medical applications: the influence of particle size on the detection properties

Guidelli, Eder Jose; Ramos, Ana Paula; Zaniquelli, Maria Elisabete D.; Nicolucci, Patricia; Baffa, Oswaldo
Fonte: ROYAL SOC CHEMISTRY; CAMBRIDGE Publicador: ROYAL SOC CHEMISTRY; CAMBRIDGE
Tipo: Artigo de Revista Científica
ENG
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Silver/alanine nanocomposites with varying mass percentage of silver have been produced. The size of the silver nanoparticles seems to drive the formation of the nanocomposite, yielding a homogeneous dispersion of the silver nanoparticles in the alanine matrix or flocs of silver nanoparticles segregated from the alanine crystals. The alanine crystalline orientation is modified according to the particle size of the silver nanoparticles. Concerning a mass percentage of silver below 0.1%, the nanocomposites are homogeneous, and there is no particle aggregation. As the mass percentage of silver is increased, the system becomes unstable, and there is particle flocculation with subsequent segregation of the alanine crystals. The nanocomposites have been analyzed by transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy and they have been tested as radiation detectors by means of electron spin resonance (ESR) spectroscopy in order to detect the paramagnetic centers created by the radiation. In fact, the sensitivity of the radiation detectors is optimized in the case of systems containing small particles (30 nm) that are well dispersed in the alanine matrix. As the agglomeration increases...

The growing importance of materials that prevent microbial adhesion: antimicrobial effect of medical devices containing silver

Monteiro, Douglas Roberto; Gorup, Luiz Fernando; Takamiya, Aline Satie; Ruvollo-Filho, Adhemar Colla; Camargo, Emerson Rodrigues; Barbosa, Debora Barros
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 103-110
ENG
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Research has clarified the properties required for polymers that resist bacterial colonisation for use in medical devices. The increase in antibiotic-resistant microorganisms has prompted interest in the use of silver as an antimicrobial agent. Silver-based polymers can protect the inner and outer surfaces of devices against the attachment of microorganisms. Thus, this review focuses on the mechanisms of various silver forms as antimicrobial agents against different microorganisms and biofilms as well as the dissociation of silver ions and the resulting reduction in antimicrobial efficacy for medical devices. This work suggests that the characteristics of released silver ions depend on the nature of the silver antimicrobial used and the polymer matrix. In addition, the elementary silver, silver zeolite and silver nanoparticles, used in polymers or as coatings could be used as antimicrobial biomaterials for a variety of promising applications. (C) 2009 Elsevier B. V. and the International Society of Chemotherapy. All rights reserved.

Formation of silver chloride nanocrystals as a corrosion product of silver in H2SO4 solution

Picon, C. A.; Fernandes, F. A P; Machado, S. A P; Tremiliosi-Filho, G.; Casteletti, L. C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 199-202
ENG
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The purpose of this study is to characterize the corrosion product on the surface of silver, employing H2SO4 (0.5M) as electrolyte. The electrochemical parameters, Ecor, Icor, V cor and Rp were obtained after analyzing the potentiodynamic polarization curve in which two peaks were observed. The smallest (passive region) is attributed to the Cl- traces from the reference electrode, with micro-cracks. The second peak (in the transpassivation region) corresponds to the polarization curve of silver in H2SO 4 without contaminants. SEM images and EDS analysis reveal images of a surface layer on silver, consisting of structures containing sulfur, oxygen, silver and chloride, as the corrosion product. On this layer silver sulfate crystals were observed, which occurs during the formation of silver chloride nanocrystals with different morphologies, when chloride ions were added to the electrolyte medium. ©The Electrochemical Society.

The adhesion control of Listeria monocytogenes on food-processing surfaces by silver ion implantation

Lima, Júnia Capua de; Schafer, Deise; Teixeira, P.; Dias, Lucas Felipe; Grande, Pedro Luís; Andrade, Nélio José de; Azeredo, Joana
Fonte: ICAR 2010 Publicador: ICAR 2010
Tipo: Conferência ou Objeto de Conferência
Publicado em //2010 ENG
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Bacterial adhesion to a solid surface is a crucial step in the biofilm process. Listeria monocytogenes can adhere to food-processing surfaces, survive and grow over a wide range of environmental conditions such as refrigeration temperatures and consequently cause severe disease. Several strategies have been developed with the aim to decrease the adherence of bacteria to surfaces, namely the silver ion implantation on surfaces. Thus, the aim of this work was to determine the Listeria monocytogenes CECT 4031 T adhesion ability onto four types of AISI 304 and AISI 430 surfaces usually used in food industry, restaurant, and kitchens, and simultaneously to evaluate the influence of the thermodynamics aspects on bacteria adhesion on these different surfaces.Coupons (1 cm-2) were cut from a 1 mm layer of AISI 304 and AISI 430 surfaces (N° 2B, 4 , 6 and 8). The silver ions (Ag+1) were implanted at 200 keV, 1.0 μA.cm-2 and a dose of 2.0×1016 ions.cm-2. All coupons were cleaned by immersion in 0.2% solution of a commercial detergent for 5 min, followed by immersion in ethanol for 15 min. The coupons were twice rising with ultrapure water and dried at 60 °C. Each strain was subcultured in trypticase soy broth (TSB) at 37 ºC in an orbital shaker (120 rpm)...

Silver activation on thin films of Ag-ZrCN coatings for antimicrobial activity

Ferreri, Isabel; Calderon Velasquez, S.; Escobar Galindo, R.; Palacio, C.; Henriques, Mariana; Piedade, Ana Paula; Carvalho, S.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica
Publicado em //2015 ENG
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Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr + Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5 % (w/v) NaClO solution for 5 minutes. The activation procedure revealed to be essential for the antimicrobial activity...

Silver nanoparticles flow in an aquatic trophic chain; O fluxo de nanopartículas da prata numa cadeia trófica aquática

Ribeiro, Fabianne de Araújo
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
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Silver nanoparticles (AgNP) have been produced and applied in a variety of products ranging from personal care products to food package containers, clothing and medicine utilities. The antimicrobial function of AgNP makes it very useful to be applied for such purposes. Silver (Ag) is a non-essential metal for organisms, and it has been historically present in the environment at low concentrations. Those concentrations of silver increased in the last century due to the use of Ag in the photographic industry and lately are expected to increase due to the use of AgNPs in consumer products. The presence of AgNP in the aquatic environment may pose a risk for aquatic species, and the effects can vary from lethal to sublethal effects. Moreover, the contact of aquatic organisms with AgNP may not cause immediately the death of individuals but it can be accumulated inside the animals and consequently transferred within the food chain. Considering this, the objective of this work was to study the transfer of silver nanoparticles in comparison to silver ions, which was used as silver nitrate, within an aquatic food chain model. To achieve this goal, this study was divided into four steps: the toxicity assessment of AgNP and AgNO3 to aquatic test-species...

Linear sweep voltammetry: a cheap and powerful technique for the identification of the silver tarnish layer constituents

Capelo, Sofia; Menino Homem, P.; Cavalheiro, J.; Fonseca, I.T. E.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
POR
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The potentialities of linear sweep voltammetry (LSV) for the characterization of the tarnish layer formed on pure and sterling silver samples exposed in the chapel and in the museum, at the Cathedral of Porto, in Portugal, are well demonstrated in this study. The technique allows the identification of the constituents of the thin tarnishing layers and also its relative abundance. A much more complex composition than the silver sulphide commonly associated with silver tarnish has been found, namely, silver chlorides, silver oxides and minor amounts of silver sulphide on the pure silver, plus copper oxides and a mixed copper-silver sulphide on the sterling silver samples. The tarnishing films were very thin mainly composed by silver chloride and silver oxides layers with thicknesses ranging between 0.22 and 9.63 nm.

Mechanism of acute silver toxicity in marine invertebrates

Bianchini, Adalto; Playle, Ricardo; Wood, Chris; Walsh, Patrick
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
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In freshwater crustaceans and in both freshwater and marine fish, the key mechanism of acute silver toxicity involves ionoregulatory impairment. An inhibition of the Na+,K+-ATPase located at the basolateral membrane of the gill epithelium seems to be the key site for silver toxicity. However, studies to determine if the same mechanism of toxicity is occurring in marine invertebrates, which also are ionoregulators, had not been done. Thus, the present study was carried out to determine acute silver effects on hemolymph osmo- and ionoregulation in three marine invertebrates: the shrimp Penaeus duorarum, the sea hare Aplysia californica, and the sea urchin Diadema antillarum. Animals were exposed to silver (1 or 10 _g/L), as silver nitrate, in seawater for 48 h. Results show that acute silver exposure did not affect hemolymph osmolality or ion concentration (Na+, Cl−, K+, Ca2+ and Mg2+) in the three species studied. However, silver induced significant changes in the water content in shrimp gill and sea hare gill and hepatopancreas. Silver also caused significant changes in Na+,K+ ATPase activity and in both total and intracellular ion (Cl−, Na+, K+,Mg2+, and Ca2+) concentrations in different tissues of the three species studied. Overall...

Silver accumulation in Daphnia magna in the presence of reactive sulfide

Bianchini, Adalto; Rouleau, Claude; Wood, Chris
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
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Previously, we demonstrated a higher silver body burden when Daphnia magna were exposed to silver in the presence of environmentally relevant concentrations (25 nM) of reactive sulfide, but the explanation was unclear. In the present study, D. magna were exposed to AgNO3 (0.93_g Ag/L = 8.6nM as a mixture of cold Ag and 110mAg) in synthetic water in either the presence or absence of 25nM sulfide as zinc sulfide clusters. After 1-h exposure, daphnids were transferred to clean water for up to 5-h depuration. At different times of Ag exposure and depuration, daphnids were randomly sampled for whole body silver burden. Also, after 1 h, daphnids were sampled for silver accumulation in “gills” (small organs on the thoracic appendages), digestive tract, and carcass. Other groups were exposed to the same silver and sulfide concentrations for 1 h and then sampled for whole-body autoradiography. Silver body burden was about two-fold higher in the presence of sulfide. A two-fold increase in silver burden in “gills” and digestive tract, but not in carcass, was also observed in the presence of sulfide. Absolute differences due to sulfide were greatest in digestive tract and explained most of the difference in whole body burden. Transfer to clean water caused a significant drop in silver concentration in whole body and all compartments to similar levels in the two groups after 5-h depuration. These results indicate that the higher silver body burden observed in the presence of sulfide is mainly due to sulfide-bound silver in the digestive tract of the daphnids. This conclusion is supported by autoradiography...

Short-term silver accumulation in tissues of three marine invertebrates: Shrimp Penaeus duorarum, sea hare Aplysia californica, and sea urchin Diadema antillarum

Bianchini, Adalto; Playle, Richard; Wood, Chris; Walsh, Patrick
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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The present study was carried out to examine possible differential silver distribution among several tissues of three marine invertebrate species: the shrimp Penaeus duorarum, the sea hare Aplysia californica, and the sea urchin Diadema antillarum. Animals were exposed to sub-lethal concentrations of silver (1 or 10 _g/L) in seawater for 48 h. In gill-breathing species (shrimp and sea hare), higher silver accumulation in gills were associated with higher hemolymph silver levels. Furthermore, sea urchin showed lower hemolymph silver concentrations than shrimp and sea hare. These findings suggest that gills are an important route for silver uptake in marine invertebrates. In both sea hare and shrimp, hepatopancreas silver accumulation was concentration-dependent and this organ accumulated the most silver after 48 h of exposure, suggesting a possible involvement of the hepatopancreas in both silver accumulation and detoxification in marine invertebrates. In shrimp and sea hare, substantial silver accumulation in nervous tissues was detected, suggesting the need for further studies on possible behavioral effects of silver in these invertebrate species. In sea urchin, egg mass accumulated more silver than other tissues analyzed, indicating the need for future studies on possible reproductive effects of silver in sea urchin. In all three species...

Evaluation of the effect of reactive sulfide on the acute toxicity of silver (i) to daphnia magna. Part 2: toxicity results

Bianchini, Adalto; Bowles, Karl; Brauner, Colin; Gorsuch, Joseph; Kramer, James; Wood, Chris
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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The protective effect of reactive sulfide against AgNO3 toxicity to Daphnia magna neonates was studied. Acute (48- h) toxicity tests were performed in the absence (,5 nM) and presence of low (;25 nM) and high (;250 nM) concentrations of zinc sulfide clusters under oxic conditions. In both the presence and the absence of sulfide, lower mean lethal concentration (LC50) values were observed when measured as opposed to nominal silver concentrations were used in calculations. This reflected the fact that measured total silver concentrations were lower than nominal concentrations due to losses of silver from solution observed during the experiment. High concentration (;250 nM) of sulfide completely protected against toxicity up to the highest silver concentration tested (2 mg/L [19 nM]) with measured silver data. In the presence of environmentally realistic levels of sulfide (;25 nM) in receiving waters, acute silver toxicity was reduced by about 5.5-fold. However, when filtered (0.45 mm) silver concentrations alone were considered, toxicity (48-h LC50) was similar in the absence (0.22 mg/L) and presence (0.28 mg/L) of sulfide. The difference between measured total and filtered silver was attributed to chemisorption of the metal sulfide onto the membrane filter and provides evidence that the toxic fraction of silver is that which is unbound to sulfide. Accumulation of silver was greater in daphnids exposed to silver in the presence of sulfide than in its absence...

Silver deposits in cutaneous burn scar tissue is a common phenomenon following application of a silver dressing

Wang, X.Q.; Chang, H.E.; Francis, R.; Olszowy, H.; Liu, P.Y.; Kempf, M.; Cuttle, L.; Kravchuk, O.; Phillips, G.; Kimble, R.
Fonte: Munksgaard Int Publ Ltd Publicador: Munksgaard Int Publ Ltd
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
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36.93539%
Background: Silver dressings have been widely and successfully used to prevent cutaneous wounds, including burns, chronic ulcers, dermatitis and other cutaneous conditions, from infection. However, in a few cases, skin discolouration or argyria-like appearances have been reported. This study investigated the level of silver in scar tissue post-burn injury following application of Acticoat™, a silver dressing. Methods: A porcine deep dermal partial thickness burn model was used. Burn wounds were treated with this silver dressing until completion of re-epithelialization, and silver levels were measured in a total of 160 scars and normal tissues. Results: The mean level of silver in scar tissue covered with silver dressings was 136 μg/g, while the silver level in normal skin was less than 0.747 μg/g. A number of wounds had a slate-grey appearance, and dissection of the scars revealed brown-black pigment mostly in the middle and deep dermis within the scar. The level of silver and the severity of the slate-grey discolouration were correlated with the length of time of the silver dressing application. Conclusions: These results show that silver deposition in cutaneous scar tissue is a common phenomenon, and higher levels of silver deposits and severe skin discolouration are correlated with an increase in the duration of this silver dressing application.; Xue-Qing Wang...

Silver absorption on burns after application of Acticoat™: data from pediatric patients and a porcine burn model; Silver absorption on burns after application of Acticoat(TM): data from pediatric patients and a porcine burn model

Wang, X.Q.; Kempf, M.; Mott, J.; Chang, H.E.; Francis, R.; Liu, P.Y.; Cuttle, L.; Olszowy, H.; Kravchuk, O.; Mill, J.; Kimble, R.
Fonte: Mosby Inc Publicador: Mosby Inc
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
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Silver dressings have been widely used to successfully prevent burn wound infection and sepsis. However, a few case studies have reported the functional abnormality and failure of vital organs, possibly caused by silver deposits. The aim of this study was to investigate the serum silver level in the pediatric burn population and also in several internal organs in a porcine burn model after the application of Acticoat. A total of 125 blood samples were collected from 46 pediatric burn patients. Thirty-six patients with a mean of 13.4% TBSA burns had a mean peak serum silver level of 114 microg/L, whereas 10 patients with a mean of 1.85% TBSA burns had an undetectable level of silver (<5.4 microg/L). Overall, serum silver levels were closely related to burn sizes. However, the highest serum silver was 735 microg/L in a 15-month-old toddler with 10% TBSA burns and the second highest was 367 microg/L in a 3-year old with 28% TBSA burns. In a porcine model with 2% TBSA burns, the mean peak silver level was 38 microg/L at 2 to 3 weeks after application of Acticoat and was then significantly reduced to an almost undetectable level at 6 weeks. Of a total of four pigs, silver was detected in all four livers (1.413 microg/g) and all four hearts (0.342 microg/g)...

The silver of the south Iberian El Argar culture: A first look at production and distribution

Bertelheim, Martin; Contreras Cort??s, Francisco; Moreno Onorato, Mar??a Auxiliadora; Murillo-Barroso, Mercedes; Pernicka, Ernst
Fonte: Consejo Superior de Investigaciones Cient??ficas (CSIC) Publicador: Consejo Superior de Investigaciones Cient??ficas (CSIC)
Tipo: Artigo de Revista Científica
ENG
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More than 700 silver objects are known from the Middle Bronze Age El Argar culture, which contrasts significantly with the rest of Bronze Age Europe, where silver is mostly rare. This has traditionally been explained by the difficulties of extracting silver from complex ores by cupellation and the relative abundance of easily accessible occurrences of native silver and silver chlorides in the south of the Iberian peninsula. However, until now in the Iberian Bronze Age the use of native silver has only been inferred by the absence of evidence of cupellation. The results of trace element analysis of a series of silver objects from several Argaric settlements reveal for the first time positive evidence for the use of native silver. Lead isotope analyses show that hardly any of the objects were made of silver from known and characterised mining districts.; Se han documentado m??s de 700 objetos de plata de la cultura arg??rica del Bronce Medio. Esta cifra contrasta con la realidad del II milenio AC europeo, donde la plata es muy escasa. Esto se ha explicado tradicionalmente por la dificultad de extraer plata de minerales complejos mediante la t??cnica de copelaci??n y la relativa abundancia de plata nativa y cloruros de plata f??cilmente accesibles en el sur de la Pen??nsula Ib??rica. Sin embargo...

Transport, Fate and Effects Of Silver In The Environment

Andren, Anders W.; Bober, Thomas W.
Fonte: Universidade de Delaware Publicador: Universidade de Delaware
Tipo: Relatório Formato: 18539481 bytes; application/pdf
EN_US
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Inorganic and organic components of water influence silver speciation in waste water effluent and may affect silver toxicity. Cationic and anionic constituents of aqueous systems control ionic strength which affect metal solubility. Organic materials such as humic and fulvic acids are capable of complexing silver and other metals in solution. It is also entirely possible that silver combines with ions and/or organic material to form suspended solids which are measured as aqueous silver. This suspended silver may be less available for bioaccumulation than are soluble forms of silver. Lower bioavailability of silver reduces the toxicity observed for silver solutions. To address silver solubility and availability questions, silver concentrations discussed in this paper were evaluated along with toxic responses of aquatic organisms to test solutions (Klaine et al., this publication).; Federal grant no. NA46RG0481, project NAS-2.

Investigation of silver catalyst for propylene epoxidation: promotion and reaction mechanism

Bedolla-Pantoja, Marco
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
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Mark A. Barteau; The gas-phase epoxidation of propylene on silver catalysts has been examined. Drawing parallels from the successful catalysts used in ethylene epoxidation, several silver-based catalysts have been tested for propylene epoxidation. However, no catalyst proved to be selective to the desired product, propylene oxide. Cadmium, copper, cesium and rhenium were tested as promoters to silver, but no catalyst achieved more than 5% selectivity to propylene oxide under the conditions tested. When the catalysts were tested at 267 ??C with a feed consisting of a gas mixture of propylene, oxygen and nitrogen at volume ratio of 1:1:8, the unpromoted silver catalyst was the least selective. The most selective catalyst was the copper-silver catalyst, which exhibited 4.3% selectivity to propylene oxide. The main limitation to selectivity is the high degree of combustion of propylene to carbon dioxide. By running the catalysts at different reaction conditions, important conclusions were drawn regarding the the kinetics of the reaction. The conversion of propylene increased as the volume ratio of oxygen to propylene fed to the reactor increased. As the oxygen fed to the reactor was increased with respect to propylene, the conversion of propylene increased but the selectivity to propylene oxide remained nearly constant for all but the rhenium-silver catalyst. For the rhenium-silver catalyst the selectivity decreased as the oxygen to propylene ratio was increased. The reaction order with respect to oxygen for propylene oxidation was deduced from these data. For the silver...

Accumulation of silver nanoparticles and its effect on the antioxidant capacity in Allium cepa L

Juárez-Maldonado,A; Rosales-Velázquez,JL; Ortega-Ortiz,H; Cabrera-De-la-Fuente,M; Ramírez,H; Benavides-Mendoza,A
Fonte: Phyton (Buenos Aires) Publicador: Phyton (Buenos Aires)
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
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Nanotechnology is currently an important worldwide study field because it provides control on matter at a nanometric scale. In food and agricultural fields, the applications of this technology are in early stages. Onion is one of the main vegetables grown in the world. Onion is a low calorie food which contains a large amount of flavonoids. In this work, silver nitrate application in onion was evaluated. An onion crop was developed at the University Antonio Narro in Saltillo, Mexico. Two methods of silver nitrate application were used (a nutritive solution: 0, 20, 40 and 80 mg/L of AgNO3; and foliar spray: 0, 20 and 40 mg/L of AgNO3). The samples were taken at 30, 60 and 90 days after transplanting. Total antioxidant capacity, silver accumulation and silver nanoparticles formation were determined. The results showed that silver nitrate had a positive effect on total antioxidant capacity when it was applied as a nutritive solution. Silver accumulation in different tissues depended on the silver nitrate application method. The silver nanoparticles formation was positive; furthermore, these nanoparticles were found at a greater extent on samples where the AgNO3 foliar spray application method was used. The average of silver nitrate nanoparticles size was from ~300 nm to ~1000 nm.

Evaluation of silver nanoparticles as a possible coccidiostat in broiler production

Chauke,N.; Siebrits,F.K.
Fonte: South African Journal of Animal Science Publicador: South African Journal of Animal Science
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
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The effect of administering low (15 mg/L) levels of silver nanoparticles in the drinking water of broilers (n = 40) was investigated as a potential replacement for antibiotic coccidiostats (Salinomycin® or Baycox®) in two trials. Four treatments were used: (1) challenged (with 3.3 x 10(5) Eimeria tenella oocysts via oral gavage in the first trial and 1.6 x 10(4) in the second trial) and medicated with silver nanoparticles in drinking water; (2) challenged and medicated with a registered ionophore coccidiostat (Salinomycin® in Trial 1 and Baycox® in Trial 2); (3) challenged and unmedicated and (4) unchallenged and unmedicated (control). Caecal lesions were scored on a scale from 0 - 4, while liver, caecal and kidney samples were taken to determine silver content. Growth performance was subjected to ANOVA using Statistica®. In Trial 1, neither the challenge (587 g vs. 561 g) nor the use of silver nanoparticles (587 vs. 555 g) had a significant effect on the weight gain of chicks from 13 to 27 days of age. The coccidiostat treatment group had a significantly lower weight gain than the unmedicated control (219 vs. 560.5 g) but had the lowest lesion score of 2.3. The silver nanoparticles group had, numerically, a slightly better score than the untreated group. The unchallenged control group had scores of 0. In the second trial there were no significant differences in growth performance between the treatments and there were no lesions...

Permeability, roughness and topography of enamel after bleaching: tracking channels of penetration with silver nitrate; Permeability, roughness and topography of enamel after bleaching: tracking channels of penetration with silver nitrate

Mendonça, Ludmila C.; Naves, Lucas Zago; Garcia, Lucas da Fonseca R.; Correr-Sobrinho, Lourenço; Soares, Carlos J.; Quagliatto, Paulo Sérgio
Fonte: UNICAMP/FOP Publicador: UNICAMP/FOP
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; Formato: application/pdf
Publicado em 12/11/2015 ENG
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Aim: This study evaluated the surface roughness, topography and permeability of bovine enamel by profilometry and scanning electron microscopy (SEM) with and without silver nitrate solution, after exposure to different bleaching agents. Methods: Fifty-two enamel samples were randomly divided into four groups (n=13): CP16% –16% carbamide peroxide - Whiteness Perfect; HP6% - 6% hydrogen peroxide - White Class; HP35% - 35% hydrogen peroxide Whiteness HP Maxx; and Control - not bleached and kept in artificial saliva. For roughness analysis, average surface roughness (Ra) and flatness coefficient (Rku) parameters were used. The topography and permeability were examined by SEM. For permeability evaluation, the samples were immersed in a 50% silver nitrate solution and analyzed using a backscattered electron and secondary electron mode. Results: For the roughness (Ra) evaluation, Kruskal-Wallis and Wilcoxon Signed Ranks Test were used, showing an increase on the surface roughness in all bleached groups. The Rku parameter suggested changes on enamel integrity. The SEM micrographs indicated changes on enamel topography and different levels of silver nitrate penetration in the samples of the bleached groups. In the overall analysis, the bleaching agents promoted surface changes and higher silver nitrate penetration when compared to the control group. Conclusions: It may be concluded that different bleaching agents might alter the topography and roughness of enamel surface. Moreover...