Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 683
Filtrar
1.
Carbohydr Polym ; 216: 189-196, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31047056

RESUMO

In this study, the composite of carboxymethyl cellulose (CMC) film modified with gelatin and TiO2-Ag nanoparticles (CMC/Gel/TiO2-Ag) was prepared and some properties of synthesized film including physicochemical and photocatalytic properties were investigated. FT-IR results showed that new interactions between the film components were created. Scanning electron microscopy (SEM) results showed that the TiO2-Ag particles with 50-100 nm distributed in the CMC/Gelatin film. The results of the mechanical test showed that the TiO2-Ag nanoparticles at low concentrations increased tensile strength (TS) and decreased strain to break (STB), but with increasing nanoparticles concentrations, TS decreased and STB increased. Photocatalytic study showed that the prepared CMC/Gel/TiO2-Ag film has good photocatalytic property. Gas chromatography was used to study photocatalytic effects of film. Increasing TiO2-Ag nano particles on the film increases the photocatalytic activity of films against NH3, ethanol and benzene.


Assuntos
Plásticos Biodegradáveis/química , Carboximetilcelulose Sódica/química , Gelatina/química , Nanopartículas Metálicas/química , Prata/química , Titânio/química , Amônia/química , Benzeno/química , Plásticos Biodegradáveis/síntese química , Plásticos Biodegradáveis/efeitos da radiação , Carboximetilcelulose Sódica/síntese química , Carboximetilcelulose Sódica/efeitos da radiação , Catálise , Módulo de Elasticidade , Etanol/química , Gelatina/síntese química , Gelatina/efeitos da radiação , Luz , Membranas Artificiais , Nanopartículas Metálicas/efeitos da radiação , Nanocompostos/química , Nanocompostos/efeitos da radiação , Permeabilidade , Prata/efeitos da radiação , Vapor , Resistência à Tração , Titânio/efeitos da radiação , Água/química
2.
Environ Monit Assess ; 191(4): 206, 2019 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-30838462

RESUMO

Titania nanoparticles with two crystalline structures (anatase-rutile) and coated titania with different amount of tin dioxide (A-R-S#1 and A-R-S#2) are prepared through hydrolysis method. X-ray diffraction analysis (XRD) confirmed the presence of both anatase and rutile structures in the synthesized titania nanoparticles. In addition, the characteristic peak of tin dioxide in A-R-S#2 was higher than that of A-R-S#1. The photocatalytic activity of the prepared photocatalysts was evaluated using a vapor mercury lamp (150 W) for decomposition of methylene blue. The results of the photocatalytic activity variation showed that the photocatalytic activity of all the synthesized photocatalysts increases by increasing the UV irradiation time (in the range of 5 min to 20 min) and weight fraction of photocatalysts (pH = 4, pH = 8, pH = 12). The pH of suspension had negative effect on photocatalytic activity. The least and most photocatalytic activity belonged to the synthesized anatase-rutile titania and A-R-S#2, respectively. Increasing the amount of tin dioxide nanoparticles on the surface of titania leads to the enhancement of photocatalytic activity. The results of the analysis of variance showed that all the main factors and their binary and triple interactions significantly affect photocatalytic activity.


Assuntos
Azul de Metileno/química , Nanopartículas , Compostos de Estanho , Titânio , Poluentes Químicos da Água/química , Catálise , Nanopartículas/química , Nanopartículas/efeitos da radiação , Fotólise , Compostos de Estanho/química , Compostos de Estanho/efeitos da radiação , Titânio/química , Titânio/efeitos da radiação , Raios Ultravioleta
3.
J Environ Sci (China) ; 79: 153-160, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30784440

RESUMO

Various methods for shifting the optical response of TiO2 into the visible (Vis) range have been reported. Herein, we reported the application of a TiO2/H2O2/Vis process and the effects of TiO2 crystalline structure on the degradation of terbuthylazine. The results indicated that TiO2 crystalline structure and H2O2 addition had significant effects on terbuthylazine degradation: its degradation rate could be increased from 7% to 70% with H2O2 addition after 180 min of reaction, the synergistic degradation of terbuthylazine by TiO2-Fe3+ was substantially accelerated, with the degradation rate reaching up to 100% after 20 min of reaction, and rutile TiO2 showed better photocatalytic activity and a more obvious synergistic effect than anatase TiO2. The addition of free-radical scavengers (tert-butyl alcohol or methanol) inhibited the degradation efficiency of rutile TiO2, but had a relatively minor effect on anatase TiO2. Fluorescence spectrophotometry analysis indicated that hydroxyl free radicals could be continuously produced when using rutile TiO2 as the photocatalyst. Degradation of terbuthylazine catalyzed by rutile TiO2 occurred mainly in solution, but occurred on the particle surface of the photocatalyst when catalyzed by anatase TiO2. This study provides new insight into the role of TiO2 crystalline structure on the degradation of terbuthylazine and its photocatalytic degradation mechanism.


Assuntos
Peróxido de Hidrogênio/química , Titânio/química , Triazinas/química , Poluentes Químicos da Água/química , Catálise , Cristalização , Peróxido de Hidrogênio/efeitos da radiação , Luz , Fotólise , Titânio/efeitos da radiação
4.
J Environ Sci (China) ; 79: 213-224, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30784444

RESUMO

In this study, a baffled photocatalytic reactor was used for the treatment of colored wastewater containing the azo dye of Acid Orange 52 (AO52). A study on the active species of the photocatalytic process using TiO2 nanoparticles indicated that hydroxyl radical and superoxide have the greatest contribution to the dye degradation process respectively. Given that a level of biological oxygen demand/chemical oxygen demand (BOD5/COD) equal to 0.4 was achieved after about 5 hr from the beginning of the experiment, the reactor seems to be capable of purifying the wastewater containing AO52 dye after this time in order to discharge into a biological treatment system to continue the treatment process. The results of the liquid chromatography-mass spectrometry (LC-MS) test showed that during the first 4 hr of the experiment, with the breakdown of the azo bond, the contaminant was decomposed into the benzene annular compounds with less toxicity indicating a reduction in the toxicity of wastewater after removing the dye agent. The study on the kinetics of these reactions followed the pseudo-first-order kinetic model in all conditions and corresponded well to Langmuir-Hinshelwood model. According to the kinetic model for the simultaneous occurrence of possible pathways, the kinetic constant of production and degradation of intermediate products in optimal conditions was estimated to be between 0.0029 and 0.0391 min-1.


Assuntos
Compostos Azo/química , Corantes/química , Nanopartículas/efeitos da radiação , Titânio/efeitos da radiação , Poluentes Químicos da Água/química , Catálise , Cinética , Luz , Nanopartículas/química , Fotólise , Titânio/química , Eliminação de Resíduos Líquidos/métodos
5.
Talanta ; 196: 293-299, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30683366

RESUMO

A sensitive photoelectrochemical (PEC) biosensor for determination of alkaline phosphatase (ALP) activity was constructed based on a photo-excited electron transfer strategy. Immobilization of CdTe quantum dots (QDs) on TiO2 nanotube arrays (TNAs), addition of iron (III) and adenosine triphosphate (ATP) in turn can effectively adjust the photocurrent response of TNAs under visible light irradiation due to a photo-excited electron transfer process, and alkaline phosphatase (ALP) activity can be determined for its catalysis toward dephosphorylation of ATP. The preparation of CdTe QDs, construction of TNA/QD PEC biosensor and the mechanism of photo-excited electron transfer are investigated in the present work. Under the optimal experimental conditions, the TNA/QD PEC biosensor shows a low limits of detection (LODs) (0.05 U L-1) and limits of quantification detection (LOQs) (0.15 U L-1), wide linear range from 0.2 to 15 U L-1, and good selectivity towards ALP determination, which has been successfully applied for human serum analysis with good precision (RSD ≤ 5.4%) and high accuracy (recovery rate, 91-112%).


Assuntos
Fosfatase Alcalina/química , Técnicas Biossensoriais , Trifosfato de Adenosina/química , Compostos de Cádmio/química , Técnicas Eletroquímicas , Transporte de Elétrons , Ferro/química , Luz , Nanotubos/química , Nanotubos/efeitos da radiação , Pontos Quânticos/química , Telúrio/química , Titânio/química , Titânio/efeitos da radiação
6.
J Photochem Photobiol B ; 190: 137-145, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30529924

RESUMO

Over the past decades, nanotechnology has received great attention and brought revolutionary solutions for a number of challenges in scientific fields. Industrial, agricultural and medical applications of engineered nanomaterials have increased intensively. The ability of titanium dioxide nanoparticles (TiO2 NPs) to produce reactive oxygen species (ROS), when excited by ultra-violet (UV) light, makes them useful for effectively inactivate various pathogens. It is known that ROS also have signalling role in living organisms, therefore, TiO2 NPs-induced ROS can influence both enzymatic and non-enzymatic defence systems, and could play a role in the resistance of plants to pathogens. Herein, we studied the photocatalytic stress responses of grapevine (Vitis vinifera L.) as model plant, when exposed to a well-known photocatalyst, Degussa P25 TiO2 NPs. The photocatalytically produced ROS such as superoxide anion, hydroxyl radical and singlet oxygen were confirmed by electron paramagnetic resonance spectroscopy. Foliar exposure of five red cultivars (Cabernet sauvignon, Cabernet franc, Merlot, Kékfrankos and Kadarka) was carried out in blooming phenophase under field condition where plants are exposed to natural sunlight with relatively high UV radiation (with a maximum of ~ 45 W m-2). After two weeks of exposure, the effects of photogenerated ROS on the total phenolic content, antioxidant capacity, flavonol profile and the main macro-, microelements of the leaves were studied in detail. We found that foliar application of TiO2 NPs boosted the total phenolic content and biosynthesis of the leaf flavonols depending on the grapevine variety. Photocatalytically active TiO2 NPs also increased K, Mg, Ca, B and Mn levels in the leaves as shown by ICP-AES measurements.


Assuntos
Folhas de Planta/efeitos dos fármacos , Titânio/farmacologia , Vitis/química , Antioxidantes/análise , Flavonóis/análise , Nanoestruturas/química , Nanoestruturas/efeitos da radiação , Fenóis/análise , Folhas de Planta/química , Folhas de Planta/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Titânio/efeitos da radiação , Raios Ultravioleta
7.
Talanta ; 192: 360-367, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30348403

RESUMO

A novel composite monolithic column based on graphene oxide-trimethyl-2-methacroyloxyethylammonium chloride-titania (GO-META-TiO2) was developed for the enrichment of phosphopeptides. META was proposed as a "bridge" to connect GO and TiO2 species to prepare GO-META-TiO2 composite. This high surface area composite (surface area = 196.93 m2 g-1) was fixed in the monolithic column via an in situ UV polymerization process. In-tube solid phase microextraction (IT-SPME) using this composite was coupled with matrix-assisted laser desorption ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) for the enrichment and detection of phosphorylated peptides from a digestion mixture of α-casein, ß-casein, and bovine serum albumin (BSA) in molar ratios of 1:1:1, 1:1:10, and 1:1:100. The key factors affecting the IT-SPME of the phosphopeptides, such as the elution solution concentrations, the extraction flow rate, and the elution flow rate were comprehensively investigated. For further demonstration, this method was employed for the enrichment and detection of phosphorylated peptides from digested chicken egg white. The obtained results indicated that the GO-META-TiO2 composite monolithic column rapidly and efficiently captured the phosphopeptides present in these complex biological samples, even in the 10 fmol ß-casein tryptic digest. We therefore propose that the reported GO-META-TiO2 composite monolithic column possesses a suitable affinity for the selective extraction of phosphopeptides from biological samples. This method paves a way in extending the application of nanomaterials.


Assuntos
Nanocompostos/química , Fosfopeptídeos/análise , Microextração em Fase Sólida/instrumentação , Animais , Sequência de Bases , Caseínas/química , Bovinos , Galinhas , Colina/análogos & derivados , Colina/síntese química , Colina/química , Colina/efeitos da radiação , Clara de Ovo/química , Grafite/síntese química , Grafite/química , Grafite/efeitos da radiação , Metacrilatos/síntese química , Metacrilatos/química , Metacrilatos/efeitos da radiação , Nanocompostos/efeitos da radiação , Polimerização/efeitos da radiação , Soroalbumina Bovina/química , Microextração em Fase Sólida/métodos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Titânio/química , Titânio/efeitos da radiação , Tripsina/química , Raios Ultravioleta
8.
J Oral Sci ; 60(4): 567-573, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30587689

RESUMO

Titanium mesh plate (Ti mesh) used for bone augmentation inadvertently comes into contact with medical gloves during trimming and bending. We tested the hypotheses that glove contact degrades the biological capability of Ti mesh and that ultraviolet treatment (UV) can restore this capability. Three groups of Ti mesh specimens were prepared: as-received (AR), after glove contact (GC), and after glove contact followed by UV treatment. The AR and GC meshes were hydrophobic, but GC mesh was more hydrophobic. AR and GC meshes had significant amounts of surface carbon, and Si content was higher for GC mesh than for AR mesh. UV mesh was hydrophilic, and carbon and silicon content values were significantly lower in this group than in the AR and GC groups. The number, alkaline phosphatase activity, and mineralization ability of attached osteoblasts were significantly lower in the GC group than in the AR group and markedly higher in the UV group than in the AR group. In conclusion, glove contact caused chemical contamination of Ti mesh, which significantly reduced its bioactivity. UV treatment restored bioactivity in contaminated Ti mesh, which outperformed even the baseline Ti mesh.


Assuntos
Luvas Cirúrgicas , Osteoblastos/citologia , Titânio/química , Titânio/efeitos da radiação , Raios Ultravioleta , Fosfatase Alcalina/metabolismo , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/efeitos da radiação , Adesão Celular , Proliferação de Células , Células Cultivadas , Ensaio de Imunoadsorção Enzimática , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Microscopia Eletrônica de Varredura , Espectroscopia Fotoeletrônica , Ratos , Ratos Sprague-Dawley , Propriedades de Superfície , Telas Cirúrgicas
9.
Ecotoxicol Environ Saf ; 162: 272-286, 2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-29990740

RESUMO

The photolytic and photocatalytic transformation of an antipsychotic drug asenapine with the use of H2O2 and TiO2 was studied. A method employing irradiation with a simulated full solar spectrum in the photostability chamber was applied, then the reverse-phase ultra high performance liquid chromatography with diode array detector, coupled with electrospray quadrupole time-of-flight mass spectrometer (RP-UHPLC-DAD - ESI-Q-TOF) was used for the quantitative and qualitative analysis of the processes. The developed quantitative method was fully validated, according to the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines, and the kinetic parameters of asenapine photodecomposition were compared. Nineteen phototransformation products were detected, and their probable structures - mainly hydroxylated and oxidized asenapine derivatives - were suggested. On the basis of the elucidated structures the computational prediction of their toxicity at the various endpoints, as well as bioconcentration factors and biodegradability was performed. The obtained results were then subjected to the principal component analysis (PCA). This chemometric technique facilitated comparison of the applied models, calculated properties of the TPs, and enabled visualization of relationships between them.


Assuntos
Antipsicóticos/química , Compostos Heterocíclicos de 4 ou mais Anéis/química , Peróxido de Hidrogênio/efeitos da radiação , Luz Solar , Titânio/efeitos da radiação , Poluentes Químicos da Água/química , Catálise , Cromatografia Líquida de Alta Pressão/métodos , Simulação por Computador , Peróxido de Hidrogênio/química , Cinética , Espectrometria de Massas , Oxirredução , Fotólise , Titânio/química
10.
Chemosphere ; 209: 182-190, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29929124

RESUMO

In the present work, we report on a facile UV treatment approach for enhancing the electrocatalytic activity of TiO2 nanotubes. The TiO2 nanotubes were prepared using an anodization oxidation method by applying a voltage of 40 V for 8 h in a DMSO + 2% HF solution, and further treated under UV light irradiation. Compared with Pt and untreated TiO2 nanotubes, the UV treated electrode exhibited a superior electrocatalytic activity toward the oxidation of 4-chlorophenol (4-ClPh). The effects of current density and temperature on the electrochemical oxidation of the 4-ClPh were also systematically investigated. The high electrocatalytic activity of the UV treated TiO2 nanotubes was further confirmed by the electrochemical oxidation of other persistent organic pollutants including phenol, 2-, 3-, 4-nitrophenol, and 4-aminophenol. The total organic carbon (TOC) analysis revealed that over 90% 4-ClPh was removed when the UV treated TiO2 electrode was employed and the rate constant was 16 times faster than that of the untreated TiO2 electrode; whereas only 60% 4-ClPh was eliminated at the Pt electrode under the same conditions. This dramatically improved electrocatalytic activity might be attributed to the enhanced donor density, conductivity, and high overpotential for oxygen evolution. Our results demonstrated that the application of the UV treatment to the TiO2 nanotubes enhanced their electrochemical activity and energy consumption efficiency significantly, which is highly desirable for the abatement of persistent organic pollutants.


Assuntos
Clorofenóis/química , Técnicas Eletroquímicas/métodos , Nanotubos/química , Titânio/química , Águas Residuárias/química , Purificação da Água/métodos , Oxirredução , Titânio/efeitos da radiação , Raios Ultravioleta
11.
Water Res ; 142: 26-45, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-29859390

RESUMO

The high concentrations of pharmaceuticals and personal care products (PPCP) that found in water in many locations are of concern. Among the available water treatment methods, heterogeneous photocatalysis using TiO2 is an emerging and viable technology to overcome the occurrence of PPCP in natural and waste water. The combination of carbonaceous materials (e.g., activated carbon, carbon nanotubes and graphene nanosheets) with TiO2, a recent development, gives significantly improved performance. In this article, we present a critical review of the development and fabrication of carbonaceous-TiO2 and its application to PPCP removal including its influence on water chemistry, and the relevant operational parameters. Finally, we present an analysis of current priorities in the ongoing research and development of carbonaceous-TiO2 for the photodegradation of PPCP.


Assuntos
Carbono/química , Cosméticos/química , Preparações Farmacêuticas/química , Titânio/química , Titânio/efeitos da radiação , Poluentes Químicos da Água/química , Purificação da Água/métodos , Catálise , Fotólise
12.
Water Res ; 139: 281-290, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29656193

RESUMO

Both nanoparticulate (nZnO and nTiO2) and organic chemical ultraviolet (UV) filters are active ingredients in sunscreen and protect against skin cancer, but limited research exists on the environmental effects of sunscreen release into aquatic systems. To examine the trade-offs of incorporating nanoparticles (NPs) into sunscreens over the past two decades, we targeted endpoints sensitive to the potential risks of different UV filters: solar reactive oxygen production in water and disruption of zebrafish embryo development. First, we developed methodology to extract nanoparticles from sunscreens with organic solvents. Zebrafish embryos exposed to parts-per-million NPs used in sunscreens displayed limited toxicological effects; nZnO particles appeared to be slightly more toxic than nTiO2 at the highest concentrations. In contrast, seven organic UV filters did not affect zebrafish embryogenesis at or near aqueous solubility. Second, to simulate potent photo-initiated reactions upon release into water, we examined methylene blue (MB) degradation under UV light. nTiO2 from sunscreen caused 10 times faster MB loss than nZnO and approached the photocatalytic degradation rate of a commercial nTiO2 photocatalysts (P25). Organic UV filters did not cause measurable MB degradation. Finally, we estimated that between 1 and 10 ppm of sunscreen NPs in surface waters could produce similar steady state hydroxyl radical concentrations as naturally occurring fluvic acids under sunlight irradiation. Incorporation of NPs into sunscreen may increase environmental concentrations of reactive oxygen, albeit to a limited extent, which can influence transformation of dissolved substances and potentially affect ecosystem processes.


Assuntos
Nanopartículas/toxicidade , Compostos Orgânicos/toxicidade , Protetores Solares/toxicidade , Titânio/toxicidade , Poluentes Químicos da Água/toxicidade , Óxido de Zinco/toxicidade , Animais , Ecossistema , Embrião não Mamífero/efeitos dos fármacos , Desenvolvimento Embrionário/efeitos dos fármacos , Nanopartículas/química , Nanopartículas/efeitos da radiação , Compostos Orgânicos/química , Compostos Orgânicos/efeitos da radiação , Espécies Reativas de Oxigênio/química , Protetores Solares/química , Protetores Solares/efeitos da radiação , Titânio/química , Titânio/efeitos da radiação , Raios Ultravioleta , Poluentes Químicos da Água/química , Poluentes Químicos da Água/efeitos da radiação , Peixe-Zebra , Óxido de Zinco/química , Óxido de Zinco/efeitos da radiação
13.
Water Sci Technol ; 77(3-4): 788-799, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29431724

RESUMO

Crotamiton, a scabicide and antipruritic agent persistent during biological treatment processes, is frequently detected in secondary effluent. In this study, titanium dioxide (TiO2) and high-silica zeolite (HSZ-385) composites were synthesized and applied for the treatment of crotamiton in secondary effluent. Crotamiton was rapidly adsorbed by HSZ-385, and the adsorption performance of crotamiton in the secondary effluent was quite close to that in the test using ultrapure water. Even though the TiO2-zeolite composites showed lower adsorption rates than that of HSZ-385, similar crotamiton adsorption capacities were revealed using both test materials. The photocatalytic decomposition of crotamiton was significantly inhibited by the water matrix at low initial concentrations. The TiO2-zeolite composites rapidly adsorbed crotamiton from secondary effluent, and then the crotamiton was gradually decomposed under ultraviolet irradiation. Importantly, when using TiO2-zeolite composites, coexisting material in the secondary effluent did not markedly inhibit crotamiton removal at low initial crotamiton concentration. The behaviors of the main intermediates during treatment demonstrated that the main degradation intermediates of crotamiton were also captured by the composites.


Assuntos
Praguicidas/química , Titânio/química , Toluidinas/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Zeolitas/química , Adsorção , Catálise , Dióxido de Silício , Titânio/efeitos da radiação , Raios Ultravioleta , Zeolitas/efeitos da radiação
14.
Acta Cir Bras ; 33(1): 14-21, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29412229

RESUMO

PURPOSE: To compare the influence of two metallic implants in the diagnosis of periprosthetic infection using 99m technetium-labeled ceftizoxime. METHODS: Twenty rats were randomly divided into four groups, which received sterile and contaminated titanium and stainless steel implants. After 3 weeks, scintilographic images were obtained using a gamma chamber. Radioactivity counts were obtained for the region of interest (ROI) on the operated and non-operated paws. RESULTS: Groups A, B, and C showed homogenous distribution of the radiopharmaceutical. Hyper uptake was observed in the operated paw from group D. The ROI target count was higher in the two groups with stainless steel implants. Among the control groups, the count was higher in the stainless steel group. Furthermore, among the contaminated groups, the uptake was higher in the stainless steel group, with a significant difference. The target: non-target ratio was significantly lower in the control and contaminated groups with both titanium and stainless steel, but the comparison between control groups and contaminated groups was only significant in the former. The cpm/g observed after a decay of 48h showed statistically significant differences between groups. CONCLUSION: Different biomaterials used in implants have an influence on the results of scintigraphy with 99mTc-CFT.


Assuntos
Ceftizoxima/análogos & derivados , Compostos de Organotecnécio , Infecções Relacionadas à Prótese/diagnóstico por imagem , Compostos Radiofarmacêuticos , Aço Inoxidável/efeitos da radiação , Titânio/efeitos da radiação , Animais , Materiais Biocompatíveis/química , Infecções Relacionadas à Prótese/microbiologia , Radioatividade , Cintilografia , Distribuição Aleatória , Ratos Wistar , Valores de Referência , Reprodutibilidade dos Testes , Aço Inoxidável/química , Fatores de Tempo , Titânio/química
15.
Water Res ; 132: 177-189, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29331640

RESUMO

Over the last decade, ultraviolet light-emitting diodes (UV LEDs) have attracted considerable attention as alternative mercury-free UV sources for water treatment purposes. This review is a comprehensive analysis of data reported in recent years (mostly, post 2014) on the application of UV LED-induced advanced oxidation processes (AOPs) to degrade organic pollutants, primarily dyes, phenols, pharmaceuticals, insecticides, estrogens and cyanotoxins, in aqueous media. Heterogeneous TiO2-based photocatalysis in lab grade water using UVA LEDs is the most frequently applied method for treating organic contaminants. The effects of controlled periodic illumination, different TiO2-based nanostructures and reactor types on degradation kinetics and mineralization are discussed. UVB and UVC LEDs have been used for photo-Fenton, photo-Fenton-like and UV/H2O2 treatment of pollutants, primarily, in model aqueous solutions. Notably, UV LED-activated persulfate/peroxymonosulfate processes were capable of providing degradation in DOC-containing waters. Wall-plug efficiency, energy-efficiency of UV LEDs and the energy requirements in terms of Electrical Energy per Order (EEO) are discussed and compared. Despite the overall high degradation efficiency of the UV LED-based AOPs, practical implementation is still limited and at lab scale. More research on real water matrices at more environmentally relevant concentrations, as well as an estimation of energy requirements providing fluence-based kinetic data are required.


Assuntos
Peróxido de Hidrogênio/química , Titânio/efeitos da radiação , Raios Ultravioleta , Poluentes Químicos da Água/química , Purificação da Água/métodos , Oxirredução , Titânio/química
16.
J Hazard Mater ; 343: 285-297, 2018 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-28988054

RESUMO

Flexible organic fabrics coated with titania find wide applications in pollutant degradations and antibiosis. Because of the enhanced charge separations, TiO2 with one-dimensional nanostructures exhibits photocatalytic activity superior to that of nanoparticulate films; however, only the later has been achieved on organic substrates through commonly sol-gel techniques till now. In this study, radially aligned TiO2 nanowires were precipitated on polyester fabrics through multi-steps of surface roughening, sol-gel TiO2 seeding, hydrogen titanate nanobelts precipitation, and finally sulfuric acid treatment. Both mesoporous anatase TiO2 nanowires and single-crystalline rutile TiO2 nanorods have been achieved, which, together with some unchanged titanate nanobelts, exhibited an overall narrowed band gap of ca. 2.50eV. The TiO2 nanowires on flexible PET fabrics showed higher photocatalytic activity towards degradations of not only rhodamine B in water but also toluene gas in air under UV light illumination, when compared with either TiO2 nanotube array or commercial Degussa P25 nanoparticulate films on metallic Ti substrates. Remarkable sterilization of E. coli and S. epidermidis under visible light irradiation was also achieved. The excellent photocatalytic and antibacterial performances were attributed to the unique mixed 1D nanostructures, phase junctions, abundant surface hydroxyl groups, and the narrowed band gap.


Assuntos
Antibacterianos/química , Nanofios/química , Poliésteres/química , Têxteis , Titânio/química , Antibacterianos/efeitos da radiação , Catálise , Corantes/química , Escherichia coli/crescimento & desenvolvimento , Nanofios/efeitos da radiação , Processos Fotoquímicos , Poliésteres/efeitos da radiação , Rodaminas/química , Staphylococcus epidermidis/crescimento & desenvolvimento , Têxteis/efeitos da radiação , Titânio/efeitos da radiação , Raios Ultravioleta , Poluentes Químicos da Água/química
17.
Radiat Prot Dosimetry ; 179(2): 184-188, 2018 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-29145646

RESUMO

The literature describing the experimental investigations of possible dose-rate effects in the thermoluminescence (TL) of LiF:Mg,Ti (Harshaw) is reviewed. The total lack of glow curve analysis, coupled with inclusion of all or part of the high temperature TL and absence of parallel measurements of possible dose-rate effects in the irradiation stage severely limit the scientific and technical level of the experiments. In addition, the experimental procedures are far from sufficient to warrant any conclusion concerning the presence or absence of dose-rate effects in the TL of LiF:Mg,Ti. This decision is contrary to the widely held belief that there are no dose-rate effects in the TL of LiF:Mg,Ti. In addition, the literature on dose-rate effects in the optical absorption (irradiation stage) of LiF is reviewed and is found contradictory. No dose-rate studies have been carried out on optical absorption in LiF:Mg,Ti. Kinetic simulations demonstrating the possibility, even likelihood, of dose-rate effects are also reviewed. Dose-rate effects are shown to be likely due to competition between excitation and recombination in the irradiation stage. Some other possible mechanisms involving multiple charge carrier trapping are suggested. Further definitive experiments are sorely needed, but the interested researcher should beware, it is not an easy task.


Assuntos
Relação Dose-Resposta à Radiação , Fluoretos/efeitos da radiação , Compostos de Lítio/efeitos da radiação , Compostos de Magnésio/efeitos da radiação , Titânio/efeitos da radiação , Doses de Radiação , Dosimetria Termoluminescente/métodos
18.
Stem Cell Res Ther ; 8(1): 269, 2017 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-29179738

RESUMO

BACKGROUND: Titanium surfaces have been modified by various approaches with the aim of improving the stimulation of osseointegration. Laser beam (Yb-YAG) treatment is a controllable and flexible approach to modifying surfaces. It creates a complex surface topography with micro and nano-scaled patterns, and an oxide layer that can improve the osseointegration of implants, increasing their usefulness as bone implant materials. METHODS: Laser beam irradiation at various fluences (132, 210, or 235 J/cm2) was used to treat commercially pure titanium discs to create complex surface topographies. The titanium discs were investigated by scanning electron microscopy, X-ray diffraction, and measurement of contact angles. The surface generated at a fluence of 235 J/cm2 was used in the biological assays. The behavior of mesenchymal stem cells from an umbilical cord vein was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, a mineralization assay, and an alkaline phosphatase activity assay and by carrying out a quantitative real-time polymerase chain reaction for osteogenic markers. CHO-k1 cells were also exposed to titanium discs in the MTT assay. RESULTS: The best titanium surface was that produced by laser beam irradiation at 235 J/cm2 fluence. Cell proliferation analysis revealed that the CHO-k1 and mesenchymal stem cells behaved differently. The laser-processed titanium surface increased the proliferation of CHO-k1 cells, reduced the proliferation of mesenchymal stem cells, upregulated the expression of the osteogenic markers, and enhanced alkaline phosphatase activity. CONCLUSIONS: The laser-treated titanium surface modulated cellular behavior depending on the cell type, and stimulated osteogenic differentiation. This evidence supports the potential use of laser-processed titanium surfaces as bone implant materials, and their use in regenerative medicine could promote better outcomes.


Assuntos
Diferenciação Celular/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , Osteoblastos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Titânio/efeitos da radiação , Fosfatase Alcalina/genética , Fosfatase Alcalina/metabolismo , Biomarcadores/metabolismo , Proteína Morfogenética Óssea 2/genética , Proteína Morfogenética Óssea 2/metabolismo , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Expressão Gênica , Humanos , Lasers , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Microscopia Eletrônica de Varredura , Osteoblastos/citologia , Osteoblastos/metabolismo , Osteocalcina/genética , Osteocalcina/metabolismo , Osteogênese/genética , Osteopontina/genética , Osteopontina/metabolismo , Cultura Primária de Células , Próteses e Implantes , Propriedades de Superfície , Titânio/farmacologia , Cordão Umbilical/citologia , Cordão Umbilical/efeitos dos fármacos , Cordão Umbilical/metabolismo
19.
J Agric Food Chem ; 65(45): 9893-9901, 2017 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29058433

RESUMO

Although nanosized ingredients, including TiO2 nanoparticles (NPs), can be found in a wide range of consumer products, little is known about the effects these particles have on other active compounds in product matrices. These NPs can interact with reactive oxygen species (ROS), potentially disrupting or canceling the benefits expected from antioxidants. We used electron spin resonance spectrometry to assess changes in the antioxidant capacities of six dietary antioxidants (ascorbic acid, α-tocopherol, glutathione, cysteine, epicatechin, and epicatechin gallate) during exposure to P25 TiO2 and/or simulated sunlight. Specifically, we determined the ability of these antioxidants to scavenge 1-diphenyl-2-picryl-hydrazyl radical, superoxide radical, and hydroxyl radical. Exposure to simulated sunlight alone did not lead to noticeable changes in radical-scavenging abilities; however, in combination with P25 TiO2 NPs, the scavenging abilities of most antioxidants were weakened. We found glutathione to be the most resistant to treatment with sunlight and NPs among these six antioxidants.


Assuntos
Depuradores de Radicais Livres/química , Radicais Livres/química , Nanopartículas/química , Titânio/química , Depuradores de Radicais Livres/efeitos da radiação , Nanopartículas/efeitos da radiação , Luz Solar , Titânio/efeitos da radiação
20.
J Hazard Mater ; 340: 160-170, 2017 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-28715739

RESUMO

A photocatalytic sol of TiO2 nanoparticles has been used for creating self-cleaning antimicrobial flat and porous glass surfaces. The substrates were irradiated to study their photocatalytic properties and behavior in the presence of biofilm-forming bacteria. Smooth glass surfaces and glass microfiber filters were covered with 1.98×10-3±1.5×10-4gcm-2 and 8.55×10-3±3.0×10-4gcm-2 densities, respectively. Self-cleaning properties were analyzed using the methylene blue 365nm UV-A photodegradation test. TiO2-coated filters achieved rapid and complete photodegradation of methylene blue because of the better TiO2 dispersion with respect to the glass slides. The effect of functionalized surfaces on the growth and viability of bacteria was studied using the strains Staphylococcus aureus and Pseudomonas putida. After irradiation (2h, 11.2Wm-2, 290-400nm), the initially hydrophobic surface turned hydrophilic. The antibacterial effect led to extensive membrane damage and significant production of intracellular reactive oxygen species in all TiO2-loaded irradiated specimens. The reduction of cell viability was over 99.9% (>3-log) for TiO2 on glass surfaces. However, the polymeric extracellular matrix formed before the irradiation treatment was not removed. This study highlights the importance of bacterial colonization during dark periods and the difficulty of removing the structure of biofilms.


Assuntos
Antibacterianos , Biofilmes/efeitos dos fármacos , Nanopartículas , Pseudomonas putida/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Titânio , Raios Ultravioleta , Antibacterianos/química , Antibacterianos/farmacologia , Antibacterianos/efeitos da radiação , Catálise , Matriz Extracelular/efeitos dos fármacos , Azul de Metileno/química , Nanopartículas/química , Nanopartículas/efeitos da radiação , Fotólise , Pseudomonas putida/crescimento & desenvolvimento , Pseudomonas putida/fisiologia , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/fisiologia , Propriedades de Superfície , Titânio/química , Titânio/farmacologia , Titânio/efeitos da radiação
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA