Direct Synthesis of Bienzyme-like Carbide-derived Carbons via Mild Electrochemical Oxidation of Ti 3AlC 2 MAX / 生物医学与环境科学（英文）

Objective@#To develop effective alternatives to natural enzymes, it is crucial to develop nanozymes that are economical, resource efficient, and environmentally conscious. Carbon nanomaterials that have enzyme-like activities have been extensively developed as substitutes for traditional enzymes.@*Methods@#Carbide-derived carbons (CDCs) were directly synthesized via a one-step electrochemical method from a MAX precursor using an ammonium bifluoride electrolyte at ambient conditions. The CDCs were characterized by systematic techniques.@*Results@#CDCs showed bienzyme-like activities similar to that of peroxidase and superoxide dismutase. We systematically studied the dependence of CDC enzyme-like activity on different electrolytes and electrolysis times to confirm activity dependence on CDC content. Additionally, the synthesis mechanism and CDC applicability were elaborated and demonstrated, respectively.@*Conclusion@#The demonstrated synthesis strategy eliminates tedious intercalation and delamination centrifugation steps and avoids using high concentrations of HF, high temperatures, and halogen gases. This study paves the way for designing two-dimensional material-based nanocatalysts for nanoenzyme and other applications.

Simple synthesis of photoluminescent carbon dots from a marine polysaccharide found in shark cartilage

BACKGROUND: For more than a decade, water-soluble, eco-friendly, biocompatible, and low-toxicity fluorescent nanomaterials have received considerable attention for their numerous in vivo and in vitro applications in biomedical imaging, disease diagnostics, and environmental monitoring. Owing to their tunable photoluminescence properties, carbon-based luminescent nanomaterials have shown great potential in bioimaging, photocatalysis, and biosensing among other applications. RESULTS: Marine environments provide excellent resources for the fabrication of these nanomaterials, because many marine organisms contain interesting trigger organic compounds that can be used as precursors. Herein, we synthesize multi-color emissive carbon dots (CDs) with an intrinsic photoluminescence quantum yield of 20.46%. These nanostructures were achieved through the one-step hydrothermal treatment of marine polysaccharide chondroitin sulfate, obtained from shark cartilage, in aqueous solution. CONCLUSIONS: We successfully demonstrate the low toxicity of our marine resource-derived CDs in zebrafish, and provide an initial assessment of their possible use as a bioimaging agent. Notably, the newly synthesized CDs localize in the intestines of zebrafish larvae, thereby indicating their biocompatibility and potential use as in vivo dyes.

Soil Carbon and Structural Quality in Crop Rotations under No-tillage System

Abstract The no-tillage system associated with crops rotation affects the dynamics of soil organic matter, influencing the formation, reorganization and stabilization of aggregates and the carbon content (C) into soil aggregates. The aim of this study was to evaluate the effect of crop rotations under no-tillage system on C content and soil aggregation. The experiment was conducted at the Paraná Agronomic Institute in Ponta Grossa, PR, Brazil. The treatments consisted of six crop rotations, in a 3-year cycle, arranged in a randomized block design with four replications. Soil samples were collected at layers of 0-5, 5-10 and 10-20 cm. The aggregate classification was determined by the wet sieving methodology, and the Weighted Mean Diameter (WMD), Geometric Mean Diameter (GMD) and Aggregate Stability Index (ASI) were calculated. The C content in the aggregates was determined by wet oxidation. The results were submitted to analysis of variance and Tukey test at 5% probability. There was no difference among crop rotations for aggregate classes and aggregation indexes, but were higher in surface, decreasing in depth. The carbon content in the aggregates did not differ among crop rotations, but presented stratification in the soil profile, decreasing in depth. The cycle of three years with crop rotation was insufficient to express possible changes in soil C content and aggregation.

Ash content, carbon and C/N ratio in paricá in function of NPK fertilization

ABSTRACT Fertilization in areas of forest plantations is needed to supplement plants´ nutritional needs until harvest. An experiment was performed to check the influence of fertilization on levels of ash, carbon and C/N relation in Schizolobium amazonicum. Soil liming was performed and fertilization occurred after 15 days of incubation. S. amazonicum seedlings were produced and submitted to fertilization with N, P and K: N = 0, 40, 80 and 120 kg ha-1; P2O5 = 0, 50, 100 and 200 kg ha-1; K2O = 0, 50, 100 and 200 kg ha-1. The plants were measured after 180 days. The seedlings of 20 treatments with the highest increase in height and diameter were transplanted to the field. Soil was fertilized and limestone was spread; seedlings were distributed into randomized blocks, with six replications. After 12 months, the plants were removed to determine ash, organic carbon, C/N relation contents. The ashes were submitted to digestion to determine nutrient concentrations. Fertilization influenced the levels of ash and organic carbon and C/N relation in S. amazonicum. Results indicate that the species has a potential for energy production.

Global patterns of aboveground carbon stock and sequestration in mangroves

ABSTRACT In order to contribute to understand the factors that control the provisioning of the ecosystem service of carbon storage by mangroves, data on carbon stock and sequestration in the aboveground biomass (AGB) from 73 articles were averaged and tested for the dependence on latitude, climatic parameters, physiographic types and age. Global means of carbon stock (78.0 ± 64.5 tC.ha-1) and sequestration (2.9 ± 2.2 tC.ha-1.yr-1) showed that mangroves are among the forest ecosystems with greater capacity of carbon storage in AGB per area. On the global scale, carbon stock increases toward the equator (R²=0.22) and is dependent on 13 climatic parameters, which can be integrated in the following predictive equation: Carbon Stock in AGB = -16.342 + (8.341 x Isothermality) + (0.021 x Annual Precipitation) [R²=0.34; p < 0.05]. It was shown that almost 70% of carbon stock variability is explained by age. Carbon stock and sequestration also vary according to physiographic types, indicating the importance of hydroperiod and edaphic parameters to the local variability of carbon stock. By demonstrating the contribution of local and regional-global factors to carbon stock, this study provides information to the forecast of the effects of future climate changes and local anthropogenic forcings on this ecosystem service.

Degradation of polynuclear aromatic hydrocarbons by two strains of Pseudomonas

ABSTRACT The goal of this investigation was to isolate competent polynuclear aromatic hydrocarbons degraders that can utilize polynuclear aromatic hydrocarbons of former industrial sites at McDoel Switchyard in Bloomington, Indiana. Using conventional enrichment method based on soil slurry, we isolated, screened and purified two bacterial species strains PB1 and PB2. Applying the ribotyping technique using the 16S rRNA gene analysis, the strains were assigned to the genus Pseudomonas (Pseudomonas plecoglossicida strain PB1 and Pseudomonas sp. PB2). Both isolates showed promising metabolic capacity on pyrene sprayed MS agar plates during the preliminary investigations. Using time course studies in the liquid cultures at calculated concentrations 123, 64, 97 and 94 ppm for naphthalene, chrysene, fluroanthene and pyrene, P. plecoglossicida strain PB1 and Pseudomonas sp. PB2 showed partial utilization of the polynuclear aromatic hydrocarbons. Naphthalene was degraded between 26% and 40%, chrysene 14% and 16%, fluroanthene 5% and 7%; pyrene 8% and 13% by P. plecoglossicida strain PB1 and Pseudomonas sp. PB2 respectively. Based on their growth profile, we developed a model R2 = 1 to predict the degradation rate of slow polynuclear aromatic hydrocarbon-degraders where all the necessary parameters are constant. From this investigation, we confirm that the former industrial site soil microbial communities may be explored for the biorestoration of the industrial site.

Percepção dos enfermeiros gestores da atenção primária sobre o processo de enfermagem / Percepción de directores de la enfermera de salud primaria en el proceso de enfermería / Perception of primary healthcare management nurses on the nursing process

RESUMO Objetivo: analisar a percepção dos enfermeiros gestores da atenção primária à saúde sobre o processo de enfermagem. Método: estudo qualitativo em que os dados foram coletados por meio de entrevistas e analisados a partir da Análise de Conteúdo proposta por Bardin. Resultados: os gestores reconhecem a importância do processo de enfermagem, embora sua implementação não seja prioridade no momento. Existe dificuldade conceitual e não compreensão de que a implementação da metodologia de assistência deva perpassar pela gestão municipal. Conclusão: necessita-se de ampliação da visão dos gestores quanto à importância do processo de enfermagem e qualificação dos profissionais. Acredita-se na participação ativa dos órgãos legisladores de enfermagem, gestão local de saúde e governo federal para que a implementação do processo de enfermagem seja viabilizada. .

RESUMEN Objetivo: analizar las percepciones de los gerentes de enfermería de atención primaria de salud en el proceso de enfermería. Métodos: estudio cualitativo; los datos fueron recolectados a través de entrevistas y analizados desde el Análisis de Contenido propuesta por Bardin referencial teórico. Resultados: los gerentes reconocen la importancia del proceso de enfermería, aunque su aplicación no es la prioridad en este momento. No hay ninguna dificultad conceptual y la comprensión de que la ejecución de la ayuda metodología debe impregnar la gestión municipal. Conclusión: es necesario ampliar la visión de los administradores en cuanto a la importancia del proceso y la calificación de enfermería. Cree en la participación activa de los órganos legislativos de enfermería, administración de salud local y el gobierno federal para la aplicación del proceso de enfermería es factible. .

ABSTRACT Objective: this qualitative study aimed to analyze the perceptions of primary health care management nurses on the nursing process. Method: data were collected through interviews and analyzed by the Content Analysis proposed by Bardin’s theoretical framework. Results: managers recognize the importance of the nursing process, although its implementation was not a priority at the time of the interviews. A conceptual diffi culty and a lack of understanding that the implementation of the care methodology should be a cross-departmental action in the local healthcare management were clearly observed. Conclusion: managers should have their perspectives broadened concerning the relevance of the nursing process and the professional training. The active participation of legislative nursing bodies, local healthcare management and the federal government may open the way for the effective implementation of the nursing process. .

One-pot synthesis of graphene-chitosan nanocomposite modified carbon paste electrode for selective determination of dopamine

Background A simple, rapid, low-cost and environmentally friendly method was developed to determine dopamine (DA) in the presence of ascorbic (AA) and uric acid (UA) based on a novel technique to prepare a graphene-chitosan (GR-CS) nanocomposite and modify it on the surface of carbon paste electrode (CPE). For our design, CS acts as a media to disperse and stabilize GR, and then GR plays a key role to selective and sensitive determination of DA. Results Under physiological conditions, the linear range for dopamine was determined from 1 × 10- 4 to 2 × 10- 7 mol/L with a good correlation coefficient of 0.9961 in the presence of 1000-fold interference of AA and UA. The detection limit was estimated to be 9.82 × 10- 8 mol/L (S/N = 3). In order to study the stability and reproducibility, GR/CS/CPE underwent successive measurements in 10 times and then tested once a d for 30 d. The result exhibited 98.25% and 91.62% activities compared with the original peak current after 10-time measurements and 30-d storage. Conclusion The GR/CS/CPE has wide linear concentration range, low detection limit, and good reproducibility and stability, which suggests that our investigations provide a promising alternative for clinic DA determination.

Influence of type of bur and acid etching on dentin hydraulic conductance

El objetivo de este estudio fue comparar la tasa de filtración ex vivo (conductancia hidráulica) en discos de dentina humana tratados mecánicamente con fresas de diamante de diferente granulometría y carbide con o sin grabado ácido. Método: 60terceros molares sanos recientemente extraídos de pacientes entre 18-30 años, fueron limpiados, desinfectados (0.1% timol) e incluidos en bloques de resina epóxica. Los discos de dentinase obtuvieron mediante la reducción de la superficie oclusal con instrumentos rotativos cilíndricos, formando los siguientes nueve grupos de 12 muestras c/u: 1: grano fino (FG); 2: granomedio (MG); 3: grano grueso (CG); 4: fresas de carburotungsteno (C); 5: FG con grabado ácido (AO); 6: GM con AO;7: GG con AO; 8: C con AO; 9: sólo grabado ácido. Se determinó la conductancia hidráulica en el modelo experimental bajo presión constante de 200 mm de altura de H2O. No seobservaron diferencias entre la conductancia hidráulica entre los diferentes tipos de fresas (p = 0,5).Se encontraron diferencias en la conductancia hidráulica de discos de dentina con y sin grabado ácido (p < 0,001). El tipo de fresa no afecta la conductacia hidráulica dentinaria.El grabado ácido aumenta significativamente la conductanciahidráulica dentinaria

Biodiesel production from marine cyanobacteria cultured in plate and tubular photobioreactors.

Carbon (neutral) based renewable liquid biofuels are alternative to petroleum derived transport fuels that contribute to global warming and are of a limited availability. Microalgae based biofuels are considered as promising source of energy. Lyngbya sp. and Synechococcus sp. were studied for the possibility of biodiesel production in different media such as ASNIII, sea water enrichment medium and BG11. The sea water enrichment medium was found superior in enhancing the growth rate of these microalgae. Nitrogen depletion has less effect in total chlorophyll a content, at the same time the lipid content was increased in both Lyngbya sp. and Synechococcus sp. by 1.4 and 1.2 % respectively. Increase in salinity from 0.5-1.0 M also showed an increase in the lipid content to 2.0 and 0.8 % in these strains; but a salinity of 1.5 M has a total inhibitory effect in the growth. The total biomass yield was comparatively higher in tubular LED photobioreactor than the fluorescent flat plated photobioreactor. Lipid extraction was obtained maximum at 60 ºC in 1:10 sample: solvent ratio. GC-MS analysis of biodiesel showed high content of polyunsaturated fatty acids (PUFA; 4.86 %) than saturated fatty acid (SFA; 4.10 %). Biodiesel production was found maximum in Synechococcus sp. than Lyngbya sp. The viscosity of the biodiesel was closely related to conventional diesel. The results strongly suggest that marine microalgae could be used as a renewable energy source for biodiesel production.

Clinical Implication of Microscopic Anthracotic Pigment in Mediastinal Staging of Non-Small Cell Lung Cancer by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration

Microscopic anthracotic pigment (MAP) is frequently observed in endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) specimen in non-small cell lung cancer, but its clinical interpretation is not well-known. The aim of this study was to evaluate the clinical implication of MAP in mediastinal staging of non-small cell lung cancer. From May 2010 to July 2011, consecutive potentially operable non-small cell lung cancer patients who underwent EBUS-TBNA for mediastinal staging were recruited. Of the total 133 patients, 102 (76.7%) were male patients. Median age was 68 yr. Total 279 mediastinal lymph nodes were sampled by EBUS-TBNA; station 4R (100, 35.8%) and station 7 (86, 30.8%) were the most common sites. Malignant lymph nodes were 100 (35.8%). MAP was observed in 61 (21.7%) lymph nodes, and among them only 3 were malignant lymph nodes (P < 0.001). The lymph nodes with MAP were smaller (9.0 vs 10.8 mm, P = 0.001) and showed low standard uptake values on FDG-PET (4.4 vs 4.7, P = 0.256). In multivariate analysis, MAP was negatively associated with malignant lymph node (adjusted OR, 0.12; 95% CI, 0.03-0.42; P < 0.001). In potentially operable non-small cell lung cancer patients, MAP in endobronchial ultrasound-guided transbronchial needle aspiration specimens is strongly associated with benign mediastinal and hilar lymph nodes.

[Producing activated carbon from scrap tires by thermo-chemical method and evaluation its efficiency at removal racid black1 dye]

The disposal of waste tires has become an increasingly important issue worldwide in recent years. Tires not only take up large amounts of valuable landfill space, but also create fire hazards and provide a refuge for disease- carrying creatures. The goal of this study was to produce activated carbon from scrap tires .Adsorption of Acid Black1 [AB1] in aqueous solution as a pollutant by the activated carbon was also investigated. Activated carbon was prepared from scrap vehicle tires using a thermo-chemical activation method. The chemical composition and solid structure of prepared activated carbon were analyzed using Scanning Electron Microscopy [SEM] coupled with energy dispersive spectrometry [EDS] and Nitrogen Sas. Micro pore volumes of the sample were determined by the application of the BET and BJH. Predominant composition of prepared activated carbon was C [83.274%] and with area surface of 44.226 and 35.747 m2/gr observed by BET and BJH methods, respectively. Mean pore diameter was 52 nm. The result of this study showed that increasing of initial dye concentration and pH would lead to decrease of adsorption/removal of dye but by increasing of sorbent dosage and contact time, adsorption/removal of dye increased. As the results of present study it can be concluded that the production of the activated carbon from scrap tires, can provide a two-fold environmental and economic benefit; a recycling path is created for scrap tires of vehicles, and a new suitable adsorbent is produced for pollutants removal

Silicosis Caused by Chronic Inhalation of Snail Shell Powder

A 70-yr-old woman visited our hospital for shortness of breath. Chest CT showed ground glass opacity and traction bronchiectasis at right middle, lower lobe and left lingular division. Video-assisted thoracic surgical biopsy at right lower lobe and pathologic examination revealed mixed dust pneumoconiosis. Polarized optical microscopy showed lung lesions were consisted of silica and carbon materials. She was a housewife and never been exposed to silica dusts occupationally. She has taken freshwater snails as a health-promoting food for 40 yr and ground shell powder was piled up on her backyard where she spent day-time. Energy dispersive X-ray spectroscopy of snail shell and scanning electron microscopy with energy dispersive x-ray spectroscopy of lung lesion revealed that silica occupies important portion. Herein, we report the first known case of silicosis due to chronic inhalation of shell powder of freshwater snail.

Características biogeoquímicas da interação atmosfera - criosfera na Antártica ocidental / Biogeochemical characteristics of the interaction atmosphere - cryosphere in the occidental Antarctic

Atualmente a comunidade científica discute as diferenças de padrões climáticos entre o leste e o oeste antártico. Enquanto de forma geral observa-se instabilidade no setor oeste, o clima da antártica oriental demonstra relativa estabilidade climática. Abordando este contexto, neste estudo analisamos dois testemunhos de gelo recente de duas regiões com características climáticas diferentes do continente Antártico. No Platô Detroit situado na Península Antártica (64o10'S/060o0'O), analisamos a variabilidde de Black Carbon (BC) ao longo de 20 metros de neve. O BC encontrado na Península Antártica apresentou baixas concentrações comparáveis as encontradas no gelo do Artico período pré-industrial. Nossos resultados sugerem que sua variabilidade corresponde à sazonalidade dos períodos de queimada nos continentes do Hemisfério Sul. No interior do continente Antártico, analisamos o particulado em geral por um processo de microanálise ao longo de um testemunho de 40 metros extraído em Mont Johns (79o55'S/094o23'O). Encontramos uma tendência negativa na deposição de poeira mineral (AISi) entre 1967 e 2007. Nossos resultados sugerem que esta tendência seja resultado de um crescente isolamento dos ventos ao redor da Antártica. Este aumento na intensidade dos ventos reflete por sua vez o resfriamento da alta atmosfera no centro antártico causado pela depleção da camada de ozônio na região. Adicionalmente, amostras de diferentes microambientes de Patriot Hills (80o18'S/081o21'O) foram coletadas de maneira asséptica para análise microbiológica. As amostras foram cultivadas em meio R2 e paralelamente o DNA total extraído foi sequenciado pela técnica de pirosequenciamento. Os resultados preliminares desta análise mostram grande riqueza de espécies dos mais variados grupos. Os resultados deste trabalho caracterizam três diferentes parâmetros relacionados a deposição atmosférica em duas áreas do continente antártico pouco exploradas e de grande interesse científico...

The antarctic ice cap stores paleoclimatological information within layers of snow and ice. Antarctic ice has revealed the higher resolution paleoclimactic database for the last 800 kyr. Atmospheric transport plays a fundamental role on the composition and sources of particulate matter found in the Antarctic ice. It has been related to several climatic processes that changes the quantity and quality of exogenous aerosols reaching Antarctica. Therefore, studies of the particulate matter deposits along the snow/ice layers may suggest changes on atmospheric transport patterns. This work, analyze two recent ice cores from two climatic distinct regions of the Antarctic continent. One retrieved from Detroit Plateau/Antarctic Peninsula (64o10'S/060o0'W), in which we have analyze Black Carbon (BC) deposition and variability along 20 meters of snow. BC found in the Antarctic Peninsula showed low concentrations (varing between 0,014 and 3,733ppb), comparable to the concentrations found on Arctic ice dated from before the industrial revolution period. Our results suggest that peaks of BC detected correspond, mostly, to biomass burning seasons in the South Hemosphere, not speficically from South America. The second one, of 40 m, was retrieved from Central-West Antarctica, Mont Johns (79o55'S/094o23'W), in which we analyzed the mineral dust abundance thought M.E.V. - E.D.X. technique. In this study we found negative trends in mineral dust (inferred from Fe, Ti and AISi) deposition between 1967 and 2007, in contrast to similar works in Sub-antarctic regions. We demonstrate that this trend is a consequence of the persistent "atmospheric isolation" that encloses the Central and East Antarctic regions due to the increasing winds around Antarctica within this period. It has been documented that westerlies intensification reflect the upper atmosphere cooling above Central Antarctica caused by the stratospherical ozone layer depletion. As part of the polar site...

Evaluation of cytochrome P-450 concentration in Saccharomyces cerevisiae strains / Avaliação do citocromo P-450 na concentração de estirpes de Saccharomyces cerevisiae

Saccharomyces cerevisiae has been widely used in mutagenicity tests due to the presence of a cytochrome P-450 system, capable of metabolizing promutagens to active mutagens. There are a large number of S. cerevisiae strains with varying abilities to produce cytochrome P-450. However, strain selection and ideal cultivation conditions are not well defined. We compared cytochrome P-450 levels in four different S. cerevisiae strains and evaluated the cultivation conditions necessary to obtain the highest levels. The amount of cytochrome P-450 produced by each strain varied, as did the incubation time needed to reach the maximum level. The highest cytochrome P-450 concentrations were found in media containing fermentable sugars. The NCYC 240 strain produced the highest level of cytochrome P-450 when grown in the presence of 20 percent (w/v) glucose. The addition of ethanol to the media also increased cytochrome P-450 synthesis in this strain. These results indicate cultivation conditions must be specific and well-established for the strain selected in order to assure high cytochrome P-450 levels and reliable mutagenicity results.

Linhagens de Saccharomyces cerevisiae tem sido amplamente empregadas em testes de mutagenicidade devido à presença de um sistema citocromo P-450 capaz de metabolizar substâncias pró-mutagênicas à sua forma ativa. Devido à grande variedade de linhagens de S. cerevisiae com diferentes capacidades de produção de citocromo P-450, torna-se necessária a seleção de cepas, bem como a definição das condições ideais de cultivo. Neste trabalho, foram comparados os níveis de citocromo P-450 em quatro diferentes linhagens de S. cerevisiae e avaliadas as condições de cultivo necessárias para obtenção de altas concentrações deste sistema enzimático. O maior nível enzimático foi encontrado na linhagem NCYC 240 em presença de 20 por cento de glicose (p/v). A adição de etanol ao meio de cultura também produziu um aumento na síntese de citocromo P-450. Estes resultados indicam que as condições de cultivo devem ser específicas e bem definidas para a linhagem selecionada, garantindo assim elevados níveis de citocromo P-450 e, conseqüentemente, a confiabilidade nos testes de mutagenicidade.

Characterization and in vitro cytocompatibility of an acid-etched titanium surface

The aims of this study were to characterize the microstructure of a commercially pure titanium (cpTi) surface etched with HCl/H2SO4 (AE-cpTi) and to investigate its in vitro cytocompatibility compared to turned cpTi (T-cpTi). T-cpTi showed a grooved surface and AE-cpTi revealed a surface characterized by the presence of micropits. Surface parameters indicated that the AE-cpTi surface is more isotropic and present a greater area compared to T-cpTi. The oxide film thickness was similar between both surfaces; however, AE-cpTi presented more Ti and O and less C. Osteoblastic cell proliferation, alkaline phosphatase activity, and bone-like nodule formation were greater on T-cpTi than on AE-cpTi. These results show that acid etching treatment produced a surface with different topographical and chemical features compared to the turned one, and such surface modification affected negatively the in vitro cytocompatibility of cpTi as demonstrated by decreasing culture growth and expression of osteoblastic phenotype.

O objetivo deste estudo foi caracterizar a microestrutura de uma superfície de titânio comercialmente puro (cpTi) condicionada com HCl/H2SO4 (acid etched) (AE-cpTi) e investigar sua citocompatibilidade in vitro, comparada à do cpTi usinado (turned) (T-cpTi). O T-cpTi apresentou uma superfície com sulcos e o AE-cpTi exibiu uma superfície caracterizada pela presença de micro-vales. Os parâmetros de superfície indicaram que a superfície AE-cpTi é mais isotrópica e apresenta uma área maior quando comparada à superfície T-cpTi. A espessura da camada de óxido foi similar para as duas superfícies; no entanto, a AE-cpTi apresentou maiores quantidades de Ti e O e menor, de C. A proliferação de células osteoblásticas, a atividade de fosfatase alcalina e a formação de matriz mineralizada foram maiores na superfície T-cpTi que na AE-cpTi. Esses resultados mostram que o condicionamento ácido produziu uma superfície com características topográficas e químicas diferentes quando comparadas às da superfície usinada. Além disso, observou-se que essas modificações de superfície afetaram de forma negativa a citocompatibilidade in vitro do cpTi como demonstrado pela inibição da proliferação celular e da expressão do fenótipo osteoblástico.

Influence of microwave sterilization on the cutting capacity of carbide burs

OBJECTIVE: This study compared the cutting capacity of carbide burs sterilized with microwaves and traditional sterilization methods. MATERIAL AND METHODS: Sixty burs were divided into 5 groups according to the sterilization methods: dry heat (G1), autoclave (G2), microwave irradiation (G3), glutaraldehyde (G4) or control - no sterilization (G5). The burs were used to cut glass plates in a cutting machine set for twelve 2.5-min periods and, after each period, they were sterilized (except G5) following the protocol established for each group. The cutting capacity of the burs was determined by a weight-loss method. Data were analyzed statistically by Kruskal-Wallis and Dunn's test. RESULTS: The means of the cutting amount performed by each group after the 12 periods were G1 = 0.2167 ± 0.0627 g; G2 = 0.2077 ± 0.0231 g; G3 = 0.1980 ± 0.0326 g; G4 = 0.1203 ± 0.0459 g; G5 = 0.2642 ± 0.0359 g. There were statistically significant differences among the groups (p<0.05); only dry heat sterilization was similar to the control. CONCLUSION: Sterilization by dry heat was the method that least affected the cutting capacity of the carbide burs and microwave sterilization was not better than traditional sterilization methods.

Morphological analysis of glass, carbon and glass/carbon fiber posts and bonding to self or dual-cured resin luting agents

OBJECTIVE: The aim of this study was to evaluate the morphology of glass (GF), carbon (CF) and glass/carbon (G/CF) fiber posts and their bond strength to self or dual-cured resin luting agents. MATERIAL AND METHODS: Morphological analysis of each post type was conducted under scanning electron microscopy (SEM). Bond strength was evaluated by microtensile test after bisecting the posts and re-bonding the two halves with the luting agents. Data were subjected to two-way ANOVA and Tukey's test (α=0.05). Failure modes were evaluated under optical microscopy and SEM. RESULTS: GF presented wider fibers and higher amount of matrix than CF, and G/CF presented carbon fibers surrounded by glass fibers, and both involved by matrix. For CF and GF, the dual-cured material presented significantly higher (p<0.05) bond strength than the self-cured agent. For the dual agent, CF presented similar bond strength to GF (p>0.05), but higher than that of G/CF (p<0.05). For the self-cured agent, no significant differences (p>0.05) were detected, irrespective of the post type. For GF and G/CF, all failures were considered mixed, while a predominance of adhesive failures was detected for CF. CONCLUSION: The bonding between fiber posts and luting agents was affected by the type of fibers and polymerization mode of the cement. When no surface treatment of the post is performed, the bonding between glass fiber post and dual-cured agent seems to be more reliable.

Synthesis and characterization of porous carbons by the sol-gel method from resorcinol-formaldehyde resin

Nine carbon xerogels were synthesized from resorcinol formaldehyde resin [RF], under increasing resorcinol/catalyst, Na2CO3, [R/C] molar ratios [50, 500. 1000], followed by pyrolysis at temperatures of 500, 600 and 700°C, under no external flow of gases. One organic xerogel was included for the sake of comparison. Drying of the RF hydrogels was carried out by the conventional evaporation technique in static air to get the RF xerogel Obtained carbons were characterized by CHO content, TEM, and N2/77K adsorption. Porosity characteristics were calculated by applying the well established alpha s plots to get various textural parameters. It was found that an increase in surface area, and pore volume was associated with corresponding rise in the R/C molar ratios. Most porosity, mainly, existed within the micropore size range, particularly for xerogels developed at 600 or 700°C, Thus. well-developed porous activated carbons could be obtained from an organic RF-xerogel by pyrolysis at 700°C and at high R/C-precursor ratios [500 and 1000]. The described simple conditions of preparation might encourage the pilot-scale production of porous carbon xerogels, suitable as adsorbents in liquid-phase environmental treatment processes

Minimizing water pollution via removal of hazardous organics onto biomass-activated carbons

Liquid-phase adsorption of phenol [P], para-nitrophenol [PNP], 2, 4-dinitrophenol [DNP], 4-aminophenol [PAP] and 2,4-dichlorophenol [DCP] onto a series or activated carbons were measured under equilibrium conditions, at room temperature. Three carbon samples were obtained from maize stalks by impregnation with different concentrations of H3PO4. One activated carbon sample was obtained by the one-step steam pyrolysis at 700°C, the last fifth carbon sample was the non activated carbon and was prepared by carbonizing the raw material at 500°C for 3 hr. The adsorption capacity of mthelyene blue [MB], rhodamine B [RB] and Congo red [CR] dyes onto the investigated adsorbents was determined via one point bottle test as mg/g. The raw material and their carbon adsorbents showed high adsorption capacity towards both categories of pollutants, phenolics and dyes. Linear form or Langmuir and Freundlich equations were employed to analyze the equilibrium adsorption data which show a satisfactory fit in most cases. The results indicate that Langmuir isotherm was more favorable for the removal of these phenolic derivatives in most cases whereas the Freundlich isotherm is better for the high porosity sample of medium acid concentration which adsorbed the biggest amounts of these pollutants. The sequence of phenolic uptake was DCP>DNP> PNP>P> PAP and was found to be related to both nature or the carbon-surface and porosity besides the solubility and molecular dimensions of the solutes. Low affinity towards phenol may be associated with its competition with water molecules which are more favorably attracted to the acidic surface that are charged with oxygen functional groups. The dye uptake onto the studied sorbents follows the order MB>RB>CR which was attributed to the fact that MB are more accessible to a significant fraction of the pore system which is not available for both others bulky molecules of RB and CR. Dye uptake was found to be controlled by surface chemical nature rater than porosity. The adsorption or both phenolic derivatives and dyes from their aqueous solutions were found to be controlled by both the surface chemical nature and porosity besides the solute nature