Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
1.
Environ Manage ; 73(2): 425-442, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37864753

RESUMEN

The potential of pyrolyzed Mytella falcata shells as an adsorbent for removing methylene blue dye molecules from aqueous solutions was investigated. The study found that the adsorbent produced at 600 °C of pyrolysis temperature, with an adsorbent mass of 0.5 g, particle diameter of 0.297-0.149 mm, and pH 12.0, demonstrated the highest dye molecule removal efficiency of 82.41%. The material's porosity was observed through scanning electron microscopy, which is favorable for adsorption, while Fourier-transform infrared spectroscopy and X-Ray diffraction analysis analyses confirmed the presence of calcium carbonate in the crystalline phases. The pseudo-second order model was found to be the best fit for the data, suggesting that the adsorption mechanism involves two steps: external diffusion and diffusion via the solid pores. The Redlich-Peterson isotherm model better represented the equilibrium data, and the methylene blue adsorption was found to be spontaneous, favorable, and endothermic. The hydrogen peroxide with UV oxidation was found to be the most efficient method of regeneration, with a regeneration percentage of 63% achieved using 600 mmol.L-1 of oxidizing agents. The results suggest that pyrolyzed Mytella falcata shells could serve as an ecologically viable adsorbent alternative, reducing the amount of waste produced in the local environment and at the same time removing pollutants from the water. The material's adsorption capacity remained almost constant in the first adsorption-oxidation cycles, indicating its potential for repeated use.


Asunto(s)
Azul de Metileno , Contaminantes Químicos del Agua , Termodinámica , Azul de Metileno/química , Fotólisis , Concentración de Iones de Hidrógeno , Temperatura , Cinética , Adsorción , Agua , Contaminantes Químicos del Agua/química
2.
Chem Biodivers ; 19(11): e202200256, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36174042

RESUMEN

An increasing morbidity and mortality rate has been related to arboviruses transmitted by Aedes aegypti. Compounds with cinnamoyl moiety represent an alternative against mosquitos, considering their larvicidal activity. This study aimed to assess the larvicidal activity of cinnamic ester derivates against Aedes aegypti larvae, along with evaluating their toxicity effect to assess its safety as a larvicide. Ethyl cinnamate demonstrated larvicidal activity (LC50 =48.59 µg/mL). Morphological changes in larvae were detected, as a degenerative response in the thorax. Through molecular docking, the molecular binding mode between 3b, 3c, and acetylcholinesterase showed strong hydrogen bond interactions. Preliminary in vitro cell viability revealed the non-cytotoxicity of 3c. Ecotoxicity results indicated a sensitivity of Artemia salina to cinnamic esters. The phytotoxicity bioassays show potential for cinnamic compounds to enhance germination and root development. These findings suggest that compound 3c is more suitable as a larvicide since it demonstrated low toxicity.


Asunto(s)
Aedes , Insecticidas , Animales , Insecticidas/toxicidad , Insecticidas/química , Ésteres/farmacología , Acetilcolinesterasa , Simulación del Acoplamiento Molecular , Extractos Vegetales/química , Larva
3.
Water Sci Technol ; 74(5): 1143-54, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27642834

RESUMEN

This study aimed to determine the best method to treat a textile effluent containing the dye basic blue 99 (BB). Treatments by the electrochemical and the Fenton processes were compared by means of a 2(3) experimental design, and the interaction of experimental conditions for BB oxidation were determined. The electrochemical treatment gave better results in the presence of NaCl as electrolyte and high current density (30 mA cm(-2)); the Fenton reaction provided better results at H2O2 and Fe(2+) concentrations of 10 mg L(-1) and 0.5 mmol L(-1), respectively. Electrochemical treatment was 23 times faster than the Fenton reaction because formation of chlorinated species during electrooxidation significantly contributed to dye oxidation. Although the electrochemical process was more efficient, the resulting treated effluent was more toxic to Lactuca sativa germination and growth, which indicated some biotoxicity. Results demonstrated that both processes efficiently remediated effluents containing the dye BB, but they need to be combined with other processes to ensure complete adequacy of the effluent for disposal.


Asunto(s)
Técnicas Electroquímicas/métodos , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Peróxido de Hidrógeno , Residuos Industriales , Oxidación-Reducción , Industria Textil , Purificación del Agua
4.
J Contemp Dent Pract ; 16(10): 800-4, 2015 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-26581460

RESUMEN

AIM: The purpose of this study was to determine the effect of different solutions cola soft drink (CSD) and coffee on roughness and microleakage of composite resin restorations. MATERIALS AND METHODS: Sixty bovine incisors were prepared and restored using Filtek Z350 XT (3M/ESPE) nanoparticulate resin. The samples were divided into three groups (n = 20): A (control)-Immersion in artificial saliva (14 days); B: Immersion in coffee (14 days), for 15 minutes (3x/day) and C: Immersion in CSD for 14 days (3x/day). Then the samples were analyzed for microleakage (dye penetration) and surface roughness (atomic force microscope). The one-way analysis of variance (ANOVA) was applied to assess the surface roughness and microleakage. The Tukey's test was set at 0.05. RESULTS: Group A (roughness-GAR) presented significantly the lowest average surface roughness. Group C (microleakage-GCM) showed significantly the highest average microleakage. CONCLUSION: It was concluded that CSD and coffee change the surface roughness and increase the microleakage of restorations. CLINICAL SIGNIFICANCE: Nowadays there is a high consumption of artificially sweetened soft drinks, sports drinks, high-energy beverages and coffee products by people that cause problems in composite resin restorations.


Asunto(s)
Bebidas Gaseosas , Resinas Compuestas , Restauración Dental Permanente , Edulcorantes , Animales , Bovinos , Filtración Dental , Ensayo de Materiales , Propiedades de Superficie
5.
Water Sci Technol ; 69(11): 2258-64, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24901620

RESUMEN

The coconut processing industry generates a significant amount of liquid waste. New technologies targeting the treatment of industrial effluents have emerged, including advanced oxidation processes, the Fenton reaction, and electrochemical processes, which produce strong oxidizing species to remove organic matter. In this study we combined the Fenton reaction and electrochemical process to treat wastewater generated by the coconut industry. We prepared a synthetic wastewater consisting of a mixture of coconut milk and water and assessed how the Fenton reagents' concentration, the cathode material, the current density, and the implementation of associated technologies affect its treatment. Electrochemical treatment followed by the Fenton reaction diminished turbidity and chemical oxygen demand (COD) by 85 and 95%, respectively. The Fenton reaction followed by the electrochemical process reduced turbidity and COD by 93 and 85%, respectively. Therefore, a combination of the Fenton and electrochemical technologies can effectively treat the effluent from the coconut processing industry.


Asunto(s)
Cocos , Técnicas Electroquímicas/métodos , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Reactores Biológicos , Residuos Industriales , Factores de Tiempo , Purificación del Agua
6.
Artículo en Inglés | MEDLINE | ID: mdl-37510665

RESUMEN

Non-communicable diseases (NCDs) are the major cause of death worldwide and have economic, psychological, and social impacts. Air pollution is the second, contributing to NCDs-related deaths. Metabolomics are a useful diagnostic and prognostic tool for NCDs, as they allow the identification of biomarkers linked to emerging pathologic processes. The aim of the present study was to review the scientific literature on the application of metabolomics profiling in NCDs and to discuss environmental planning actions to assist healthcare systems and public managers based on early metabolic diagnosis. The search was conducted following PRISMA guidelines using Web of Science, Scopus, and PubMed databases with the following MeSH terms: "metabolomics" AND "noncommunicable diseases" AND "air pollution". Twenty-nine studies were eligible. Eleven involved NCDs prevention, eight addressed diabetes mellitus, insulin resistance, systemic arterial hypertension, or metabolic syndrome. Six studies focused on obesity, two evaluated nonalcoholic fatty liver disease, two studied cancer, and none addressed chronic respiratory diseases. The studies provided insights into the biological pathways associated with NCDs. Understanding the cost of delivering care where there will be a critical increase in NCDs prevalence is crucial to achieving universal health coverage and improving population health by allocating environmental planning and treatment resources.


Asunto(s)
Diabetes Mellitus , Hipertensión , Síndrome Metabólico , Enfermedades no Transmisibles , Humanos , Enfermedades no Transmisibles/epidemiología , Enfermedades no Transmisibles/prevención & control , Diabetes Mellitus/epidemiología , Atención a la Salud
7.
Environ Sci Pollut Res Int ; 29(23): 35061-35072, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35048348

RESUMEN

Advanced oxidation processes have been used for wastewater treatment due to their capacity to reduce the organic loading and for their fast reactions. In this paper, we explore the viability of isolated and sequential use of electrochemical oxidation and Fenton processes into treatment of real raw urban sewage. The electrochemical process was carried out using DSA®-Cl2 electrodes and factorial planning in order to investigate the influence of pH, current density, and electrolyte. Fenton reaction was also used and H2O2 and Fe2+ concentration effects were investigated. The efficiency was estimated by chemical oxygen demand (COD) removal and in the optimized conditions the effluent was characterized by turbidity, suspended/dissolved/total solids, ammonia, chloride ions, free chlorine, nitrite, and potassium analysis and bioassays with Artemia ssp. and Lactuca sativa. The study demonstrated that the use of electrochemical technique followed by Fenton allowed an improvement in the degradation of organic matter and reduction of turbidity and solid content, reaching reductions of 86.8, 96.4, 99.4, 56.1, and 66.7% for COD, turbidity, SS, DS, and TS, respectively. The associated treatment also contributed to the reduction of energy consumption by 74.9%, from the 23.9 kWh m-3 observed during the electrochemical treatment isolated to the 6 kWh m-3 during the associated process. All the treatments presented toxicity reduction, with the electrochemical process achieving the best results.


Asunto(s)
Aguas del Alcantarillado , Contaminantes Químicos del Agua , Descontaminación , Técnicas Electroquímicas , Peróxido de Hidrógeno , Oxidación-Reducción , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química
8.
Sci Total Environ ; 802: 149779, 2022 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-34525680

RESUMEN

The importance of evaluating how natural organic matter influences the mobility of arsenic species in an ecosystem is an environmental concern. This work aimed to evaluate the interaction between humic substances (HS) and four arsenic species of high toxicity [As(III), As(V), MMA(V), and DMA(V)] (HS-As) under the influence of HS concentration and pH. Next, the complexing capacity (CC) of HS by As(III) was determined in function of pH, ionic strength and co-existing ions. The free arsenic (Asfree) was determined after a tangential flow ultrafiltration procedure by hydride generation atomic fluorescence spectrometry. The better HS-As interactions for As(III) and As(V) at pH 10.5 reached 52% and 61%, respectively. The increase in pH and ionic strength, as well as co-existing ions increased the CC, which reached 1.57 mg of As(III) g-1 HS. We proposed a HS-As interaction model based on the inner and outer binding sites of HS from these results. The inner sites were occupied through hydrogen bonds, Pearson acid-base, hydrophobic, and van der Waals interactions for trivalent arsenic species, while the interactions through the outer sites for pentavalent arsenic species were mostly by hydrogen bonds and electrostatic forces. According to ecotoxicological studies against Artemia salina, the presence of HS decreased the toxicity of As(III) and As(V) as the lethal concentration increased from 5.81 to 8.82 mg L-1 and from 8.82 to 13.37 mg L-1, respectively. From the results through the proposed model, it was possible to successfully understand the interaction dynamic between soil HS and As(III), As(V), MMA(V) and DMA(V) under simulated environmental conditions.


Asunto(s)
Arsénico , Arsenicales , Ecosistema , Sustancias Húmicas , Espectrometría de Fluorescencia
9.
Microsc Microanal ; 17(3): 446-51, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21492501

RESUMEN

The objective of this study was to evaluate the influence of a cola soft drink (CSD) and coffee on the microhardness and surface roughness of composite resin. Fifty cavities were prepared on the vestibular surface of bovine incisors and restored with nanoparticulate resin. The teeth were divided into five groups (n = 10): group A (control), immersion in artificial saliva (AS) for 14 days; group B, immersion in coffee for 15 min (3×/day) for 7 days followed by immersion in AS for another 7 days; group C, immersion in CSD for 15 min (3×/day) for 7 days followed by immersion in AS for another 7 days; group D, immersion in AS for 7 days, immersion in coffee for 15 min (3×/day) for 7 days; group E, immersion in AS for 7 days, immersion in CSD for 15 min (3×/day) for 7 days. After the immersion periods the specimens were analyzed for their microhardness and surface roughness. The data were subjected to analysis of variance (ANOVA) followed by t-test with 5% significance. Group A presented the highest average microhardness and lowest surface roughness, so it was possible to conclude that the consumption of CSD and coffee alters the microhardness and surface roughness of new restorations.


Asunto(s)
Resinas Acrílicas , Resinas Compuestas , Dureza/efectos de los fármacos , Microscopía de Fuerza Atómica/métodos , Poliuretanos , Propiedades de Superficie/efectos de los fármacos , Animales , Bebidas Gaseosas , Bovinos , Café/metabolismo
10.
Environ Sci Pollut Res Int ; 28(19): 23595-23609, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-32661961

RESUMEN

Tetracycline hydrochloride (TCH) electro-oxidation by commercial DSA® and commercial DSA® modified by platinum electrodeposition was evaluated. The electrodeposition was carried out at constant potential (E = - 0.73 V vs RHE) in different times (1200, 2400, and 4800 s). Scanning electron microscopy (SEM) images show that Pt electrodeposits have elongated shape particle forming a uniform surface, and energy dispersive spectroscopy (EDS) data confirms the presence of Pt on the surface. The electrochemical characterization by cyclic voltammetry showed an increase of the electrochemically active area (EAA) in function of the Pt electrodeposition time. The electro-oxidation of the TCH 0.45 mmol L-1 in H2SO4 0.1 mol L-1 solution was evaluated according to the applied current densities (j = 25, 50, 100 mA cm-2). Both the amount of platinum deposited and j showed a slight improvement in the efficiency of TCH removal, reaching 97.2% of TCH removal to DSA®/Pt4800 and 100 mA cm-2. The TCH mineralization (TOC removal), the percentage of mineralization current efficiency (MCE%), and energy consumption were 15.8%, 0.2649%, and 7.4138 kWh (g TOC)-1, respectively. The DSA®/Pt electrodes showed higher stability to TCH electro-oxidation, indicating to be a promising material for the electro-oxidation of organic pollutants.


Asunto(s)
Platino (Metal) , Contaminantes Químicos del Agua , Electrodos , Oxidación-Reducción , Tetraciclina , Contaminantes Químicos del Agua/análisis
11.
Artículo en Inglés | MEDLINE | ID: mdl-33950424

RESUMEN

Agricultural practices and industrial and human discharges play an important role in the generation of highly contaminated effluents, which becomes a threat to the environment. The persistence of many of these compounds to conventional treatments in recent years has meant that numerous efforts have been devoted to the proposal of new selective materials that allow the removal of these contaminants by adsorption. In addition, bibliometric studies have grown as powerful tools to indicate trends in innovation. In this way, the present study consisted of evaluating the potential interest to use activated carbon as adsorbent through a prospection study in scientific and technological databases. The number of records obtained for the use of activated carbon in effluent remediation processes is equivalent to 4898, which corresponds to approximately 2.5% of the total documents (articles/patents) found for the use of carbon with no defined purpose. A total of 2275 works that used the adsorptive property of activated carbon were recovered. According to the data recovered, Brazil is the leader in scientific publications among Latin American countries and the 12th worldwide, according to the SciELO and Scopus databases, respectively. In general, a significant number of patents have been recovered for this theme, in the Derwent database, 1167 documents were recovered. The results obtained in this work evidenced the growing interest in developing technologies in this area.

12.
Front Pharmacol ; 12: 787633, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34912230

RESUMEN

The aim of this study was to obtain a Brazilian red propolis (BRP) enriched composite resin and to perform the characterization of its antibacterial activity, mechanical, and physical-chemical properties. Brazilian red propolis ethyl acetate extract (EABRP) was characterized by LC-ESI-Orbitrap-FTMS, UPLC-DAD, antibacterial activity, total flavonoids content, and radical scavenging capacity. BRP was incorporated to a commercial composite resin (RC) to obtain BRP enriched composite at 0.1, 0.15 and 0.25% (RP10, RP15 and RP25, respectively). The antibacterial activity RPs was evaluated against Streptococcus mutans by contact direct test and expressed by antibacterial ratio. The RPs were characterized as its cytotoxicity against 3T3 fibroblasts, flexural strength (FS), Knoop microhardness (KHN), post-cure depth (CD), degree of conversion (DC%), water sorption (Wsp), water solubility (Wsl), average roughness (Ra), and thermal analysis. Were identified 50 chemical compounds from BRP extract by LC-ESI-Orbitrap-FTMS. EABRP was bacteriostatic and bactericide at 125 and 500 µg/ml, respectively. The RP25 exhibited antibacterial ratio of 90.76% after 1 h of direct contact with S. mutans (p < 0.0001) while RC no showed significative antibacterial activity (p = 0.1865), both compared with cell control group. RPs and RC no showed cytotoxicity. RPs exhibited CD from 2.74 to 4.48 mm, DC% from 80.70 to 83.96%, Wsp from 17.15 to 21.67 µg/mm3, Wsl from 3.66 to 4.20 µg/mm3, Ra from 14.48 to 20.76 nm. RPs showed thermal resistance between 448-455°C. The results support that propolis can be used on development of modified composite resins that show antibacterial activity and that have compatible mechanical and physical-chemical properties to the indicate for composite resins.

13.
Microsc Microanal ; 16(6): 779-84, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20920378

RESUMEN

This in vitro study evaluated the marginal gap at the composite tooth/resin interface in class V cavities under the influence of two insertion techniques and a curing system by means of atomic force microscopy (AFM). Forty enamel and dentin cavities were prepared on the buccal surface in bovine teeth with quadratic forms measuring 2 mm × 2 mm and depth of 1.5 mm. The teeth were then divided into four groups: group A, 10 cavities were restored in one increment, light cured by halogen light; group B, 10 cavities filled with bulk filling, light cured by the light emitting diodes (LED); group C, 10 cavities were restored by the incremental technique, light cured by halogen light; group D, 10 cavities were restored by the incremental technique, light cured by the LED. The teeth underwent the polishing procedure and were analyzed by AFM for tooth/restoration interface evaluation. The data were compared between groups using the nonparametric Kruskall-Wallis and Mann-Whitney tests (p < 0.05). The results showed a statistically significant difference between groups A and B and groups A and C. It was concluded that no insertion and polymerization technique was able to completely seal the cavity.


Asunto(s)
Sustitutos de Huesos/administración & dosificación , Resinas Compuestas/administración & dosificación , Restauración Dental Permanente/métodos , Animales , Sustitutos de Huesos/química , Bovinos , Resinas Compuestas/química , Microscopía de Fuerza Atómica
14.
J Contemp Dent Pract ; 11(6): E017-24, 2010 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-21203733

RESUMEN

AIM: This study evaluated the surface roughness patterns of two resin-based composite restorative materials, a microhybrid (Filtek Z250, 3M ESPE) and a nanofilled (Filtek Supreme, 3M ESPE), subjected to a regimen that simulated dynamic pH-cycling and toothbrushing. METHODS AND MATERIALS: Twelve standardized cylindrical specimens of each resin-based composite material were prepared, finished, and mechanically polished. The experimental units were submitted to a pH-cycling regimen followed by 50,000 toothbrushing cycles, after which the surface roughness was measured using an atomic force microscope (AFM). AFM surface roughness was evaluated at three intervals: (1) immediately after specimen preparation (baseline), (2) after pH-cycling, and (3) after simulated toothbrushing. The results were then analyzed using a split-plot design and followed by linear regression and a Tukey's test at a significance level of p<0.05. RESULTS: The results obtained indicated that simulated toothbrushing provoked a remarkable increase in surface roughness for both types of composite resins tested (p=0.0031). However, pH-cycling did not alter the surface of the composite under the conditions of this experiment. CONCLUSION: Based on the results obtained, it was concluded that simulated toothbrushing was capable of increasing the surface roughness of the microhybrid (Filtek Z250) and the nanofilled (Filtek Supreme) composites tested. CLINICAL SIGNIFICANCE: Surface roughness of nanofilled and microhybrid composites is significantly increased after toothbrushing, although pH-cycling, as tested in this study, does not appear to affect the morphology of either composite material.


Asunto(s)
Resinas Compuestas/química , Materiales Dentales/química , Nanocompuestos/química , Cepillado Dental , Pulido Dental/métodos , Humanos , Concentración de Iones de Hidrógeno , Ensayo de Materiales , Microscopía de Fuerza Atómica , Propiedades de Superficie , Temperatura , Factores de Tiempo , Pastas de Dientes/química , Agua/química
15.
Carbohydr Polym ; 205: 371-376, 2019 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-30446117

RESUMEN

Biodegradability and ecotoxicity of products used in oil industry are of great relevance and corrosion inhibitor could not be an exception. In earlier reports, chitosan and some derivatives were evaluated as corrosion inhibitors at acid pH, mainly due to polymer solubility. An eco-friendly corrosion inhibitor with water solubility in all pH range should be ideal, as well as that could act under the high salinity of oil field environment. Thus, herein is presented the performance of a water-soluble carboxymethylchitosan (CMC) as corrosion inhibitor in presence of chlorides (3.5% NaCl) in 1020 carbon steel, without any addition of acid or base. CMC showed good properties as corrosion inhibitor in media containing Cl-, and behaved as an anodic inhibitor. CMC exhibited inhibitory efficiency of about 80% and 67%, according to Tafel curve and electrochemical impedance, respectively, which was attributed to chemisorption mechanism (ΔGads ≈ -45 kJ/mol).

16.
Sci Rep ; 9(1): 18293, 2019 12 04.
Artículo en Inglés | MEDLINE | ID: mdl-31797960

RESUMEN

The standardization of apiceutical products like as propolis extracts has been widely debated worldwide and variations in the propolis chemical composition are still very relevant topics for use-standardized of different propolis-type as medication by much of the world's population. The present manuscript discuss important issues related to the climate effect and variations in propolis metabolite-profiling changes, antioxidant capacity and variations of the antibacterial activity of the Brazilian red propolis metabolites using comprehensive multivariate correlations. It was observed the increasing of guttiferones concentrations during the intense drought period and drastic decreasing in rainy period. The climate variation induced the high concentration of flavonoids in rainy period with pronounced dropped in some rainy months. The Pearson´s analysis demonstrated correlation between IC50 from DPPH and guttiferones and flavonoids concentrations. The PCA-X and Hotelling T2 test showed outliers during the months with lowest concentrations of formononetin and isoliquiritigenin was observed in antibacterial tests. The PLS-DA, OPLS-DA and VIP analysis demonstrate guttiferone E, guttiferone B, liquiritigenin, naringenin are considered important substances responsible by anti-staphylococcal activity in red propolis composition during the rainy season and drought period, but a synergistic effect with other flavonoids and isoflavonoids are not ruled out.


Asunto(s)
Antiinfecciosos/química , Antioxidantes/química , Benzofenonas/análisis , Flavonoides/análisis , Própolis/química , Cambio Climático , Estaciones del Año
17.
Chemosphere ; 64(3): 393-9, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16473394

RESUMEN

The successful application of electrochemical technology, employing a dimensionally stable anode (DSA((R))), for the remediation of wastewater from the oil extraction industry has been demonstrated. Samples from the oil-water separation box of an effluent treatment plant were submitted to voltammetry, chronoamperometry and electrolysis studies using a DSA anode of nominal composition Ti/Ru(0.34)Ti(0.66)O(2). Electrolysis of the oily wastewater lead to a time-dependent reduction in chemical oxygen demand (COD) in the sample that could be attributed to: (i) the direct oxidation of oil components at the electrode, by the metal oxide itself or by OH() radicals available at the electrode surface, (ii) the indirect oxidation of oil components by intermediate oxidising agents formed in parallel reactions (ex. ClO(-)), and (iii) the aggregation of suspended oil droplets by electroflotation. The largest reduction (57%) in COD was obtained following electrolysis of an oily sample for 70 h at 50 degrees C with a current density of 100 mA cm(-2). The stability of DSA electrodes for use in oily wastewater remediation has been assessed.


Asunto(s)
Electrólisis , Petróleo/análisis , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Brasil , Electrodos , Purificación del Agua/instrumentación
18.
Dent Mater J ; 35(4): 621-6, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27477228

RESUMEN

The aim of this study was to evaluate the microhardness and surface roughness of composite resins immersed in alcoholic beverages. Three composite resins were used: Durafill (Heraeus Kulzer), Z250 (3M-ESPE) and Z350 XT (3M-ESPE). The inital surface roughness and microhardness were measured. The samples were divided into four groups (n=30): G1-artificial saliva; G2-beer; G3-vodka; G4-whisky. The samples were immersed in the beverages 3× a day for 15 min and 30 days. The surface roughness and microhardness assays were repeated after immersion period. The data were statistically analyzed by two-way ANOVA and Tukey-HSD test (p<0.05). Surface roughness increased for all composite resins immersed in beer and whisky. Microhardness of all groups decreased after immersion in alcoholic beverages. The effect of these beverages on dental composites is depended upon the chemical composition, immersion time, alcohol content and pH of solutions.


Asunto(s)
Bebidas Alcohólicas , Resinas Compuestas , Bebidas , Materiales Dentales , Dureza , Ensayo de Materiales , Propiedades de Superficie
19.
Microsc Microanal ; 13(4): 245-50, 2007 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-17637073

RESUMEN

The regular periodontal practice of scaling and root planing produces a smear layer on the root surface that is detrimental to the readhesion of tissues during subsequent regeneration therapy. Although it has been demonstrated that gels containing the chelating agent ethylenediaminetetraacetic acid (EDTA) can assist in the removal of this contaminating layer, no quantitative method is yet available by which to evaluate the efficiency of the treatment. In this article, the power of atomic force microscopy (AFM) as a technique for monitoring and mapping the surfaces of dentinal roots is demonstrated. Roughness parameters of teeth that had been scaled and root planed were determined from AFM images acquired both before and after treatment with EDTA. The results confirmed that EDTA is an efficient cleaning agent and that dentinal samples free from a smear layer are significantly rougher than the same samples covered by a contaminating layer. AFM analysis is superior to alternative methods involving scanning electron microscopy because the same sample section can be analyzed many times, thus permitting it to be used as both the control and the treatment surface.


Asunto(s)
Quelantes/química , Dentina/química , Ácido Edético/química , Microscopía de Fuerza Atómica/métodos , Capa de Barro Dentinario , Raíz del Diente/química , Dentina/ultraestructura , Humanos , Técnicas In Vitro , Aplanamiento de la Raíz/métodos , Raíz del Diente/ultraestructura
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA