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1.
Pediatr. aten. prim ; 24(95)jul.- sept. 2022. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-212660

RESUMO

Introducción: la miositis aguda benigna de la infancia (MAB) es una enfermedad benigna y autolimitada, considerada en la actualidad como una secuela de enfermedades víricas. Su manifestación clínica típica son las mialgias en las extremidades inferiores acompañadas de rechazo a caminar. Pacientes y métodos: realizamos una revisión retrospectiva de los casos de MAB atendidos en nuestro servicio de urgencias pediátricas durante un periodo de 25 años. Obtuvimos datos demográficos, clínicos y de laboratorio a través de la revisión sistemática de historias clínicas. Se elaboraron estadísticas descriptivas y se efectuaron comparaciones entre grupos a través del test U de Mann-Whitney. Las correlaciones entre variables cuantitativas se realizaron mediante el análisis de rangos de Spearman. Resultados: se identificaron 139 casos de MAB (74,8% varones). La mayor incidencia se produjo en los meses de invierno y en niños de 4-8 años. Las mialgias bilaterales en miembros inferiores fueron el principal motivo de consulta. El 86,3% referían fiebre acompañada de síntomas respiratorios (88,5%), confirmándose en urgencias la infección por virus influenza en 37 casos (75,6% del serotipo B). En el momento del diagnóstico, la mediana de creatincinasa (CK) fue 1794 U/l, no existiendo diferencias significativas en función del sexo (p = 0,687). La función renal fue normal en todos los pacientes, ninguno necesitó hospitalización. Conclusiones: la MAB es una entidad fácilmente reconocible teniendo en cuenta sus manifestaciones clínicas y analíticas. A pesar de las masivas elevaciones de CK, sus complicaciones son excepcionales y la mayoría de los pacientes pueden ser dados de alta con tratamiento conservador (AU)


Introduction: benign acute childhood myositis (BACM) is a benign, self-limiting disease currently believed to be a sequela of viral infections. The typical clinical presentation is myalgia in the lower extremities accompanied by refusal to walk.Patients and methods: we did a retrospective review of all the cases of BACM managed in our paediatric emergency department over a 25-year period. We collected data on demographic, clinical and laboratory variables through the systematic review of health records. We performed a descriptive statistical analysis, followed by comparison of groups with the Mann-Whitney U test. The correlation between quantitative variables was assessed by means of the Spearman rank coefficient.Results: we identified 139 cases of BACM (74.8% in male patients). The highest incidence corresponded to children aged 4 to 8 years and the winter months. Bilateral lower limb myalgia was the most frequent presenting complaint. Fever was reported in 86.3% of cases, accompanied by respiratory symptoms (88.5%); influenza virus infection was confirmed in 37 cases (75.6% serotype B). At diagnosis, the median creatine kinase (CK) level was 1794 U/l, with no significant differences between the sexes (p=0.687). All patients had normal renal function, and none required hospitalization.Conclusions: based on its clinical and analytical manifestations, BACM is easy to recognise. Although massive elevation of CK is common, complications are rare, and most patients can be discharged with conservative treatment. (AU)


Assuntos
Humanos , Masculino , Feminino , Recém-Nascido , Lactente , Pré-Escolar , Criança , Adolescente , Miosite/diagnóstico , Emergências , Estatísticas não Paramétricas , Estudos Retrospectivos , Miosite/epidemiologia , Doença Aguda , Espanha/epidemiologia
2.
Pediatr Rheumatol Online J ; 20(1): 64, 2022 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-35964130

RESUMO

BACKGROUND: Data about safety and efficacy of the mRNA SARS-CoV-2 vaccine in adolescents with rheumatic diseases (RD) is scarce and whether these patients generate a sufficient immune response to the vaccine remains an outstanding question. OBJECTIVE: To evaluate safety and humoral and cellular immunity of the BNT162b2 vaccine in adolescents 12 to 18 years with RD and immunosuppressive treatment compared with a healthy control group. METHODS: Adolescents from 12 to 18 years with RD followed at Hospital La Paz in Madrid (n = 40) receiving the BNT162b2 mRNA vaccination were assessed 3 weeks after complete vaccination. Healthy adolescents served as controls (n = 24). Humoral response was measured by IgG antiSpike antibodies, and cellular response by the quantity of IFN-γ and IL-2 present in whole blood stimulated with SARS-CoV-2 Spike and M proteins. RESULTS: There were no differences in spike-specific humoral or cellular response between groups (median IFN-γ response to S specific protein; 528.80 pg/ml in controls vs. 398.44 in RD patients, p 0.78, and median IL-2 response in controls: 635.68 pg/ml vs. 497.30 in RD patients, p 0.22. The most frequent diagnosis was juvenile idiopathic arthritis (26/40, 65%) followed by Lupus (6/40, 15%). 60% of cases (23/40) received TNF inhibitors and 35% (14/40) methotrexate. 40% of patients (26/64) had previous SARS-CoV-2 infection, 9 in the control group and 17 in the RD patients without differences. Of note, 70% of infections were asymptomatic. A higher IFN-γ production was found in COVID-19 recovered individuals than in naive subjects in both groups (controls: median 859 pg/ml in recovered patients vs. 450 in naïve p 0.017, and RD patients: 850 in recovered vs. 278 in naïve p 0.024). No serious adverse events or flares were reported following vaccination. CONCLUSIONS: We conclude that standard of care treatment for adolescents with RD including TNF inhibitors and methotrexate did not affect the humoral and the cellular immunity to BNT162b2 mRNA vaccination compared to a healthy control group. The previous contact with SARS-CoV-2 was the most relevant factor in the immune response.


Assuntos
COVID-19 , Doenças Reumáticas , Vacinas Virais , Adolescente , Vacina BNT162 , COVID-19/prevenção & controle , Vacinas contra COVID-19 , Humanos , Imunidade Celular , Interleucina-2 , Metotrexato , RNA Mensageiro , Doenças Reumáticas/tratamento farmacológico , SARS-CoV-2 , Inibidores do Fator de Necrose Tumoral , Vacinas Virais/genética
3.
Clin Rheumatol ; 41(6): 1779-1784, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35489011

RESUMO

SARS-CoV-2 infections in children are frequently asymptomatic or mild and can go unnoticed. This study aimed to describe the seroprevalence and clinical course of SARS-CoV-2 in a cohort of children with rheumatic diseases in a real-life setting and assess possible risk factors. A cross-sectional study was performed in a paediatric rheumatology unit (September 2020 to February 2021). At inclusion, a specific questionnaire was completed and SARS-CoV-2 serology was performed. Demographics, treatment and disease activity of patients with and without laboratory-confirmed SARS-CoV-2 infection were compared. A total of 105 children were included. SARS-CoV-2 infection was demonstrated in 27 patients (25.7%). The mean age was 11.8 years, and most patients were females (72.4%). The most frequent underlying condition was juvenile idiopathic arthritis (70.3%; 19/27). Patients received immunosuppressive treatment in 78% of cases (21/27). Overall, 44.4% (12/27) of infected patients were asymptomatic. A total of 66.7% (18/27) of patients did not require medical assistance. Three patients required hospital admission because of COVID-19. Children with confirmed SARS-CoV-2 infection were less frequently in remission (52% vs 72%; p 0.014). Moderate disease activity and treatment with oral corticosteroids were associated with higher risk for SARS-CoV-2 (OR 5.05; CI 95%: 1.56-16.3 and OR 4.2; CI 95%: 1.26-13.9, respectively). In a cohort of Spanish paediatric patients with rheumatic diseases, clinical course of COVID-19 was mild, with more than one third of asymptomatic cases. Higher disease activity and oral corticosteroids appear to be risk factors for SARS-CoV-2 infection. Key Points • We aimed to investigate the seroprevalence of SARS-CoV-2 infection in a cohort of Spanish paediatric patients with RD, testing both symptomatic and asymptomatic patients. We also compared treatment and disease activity of patients with and without laboratory-confirmed SARS-CoV-2 infection. • In our cohort of 105 paediatric patients with rheumatic diseases, the clinical course of COVID-19 was mild and 44% of cases were asymptomatic. Three cases required hospital admission with no complications. Seroprevalence was 20%. • No association was found between disease activity or treatment with corticosteroids and symptomatic or asymptomatic infection. Higher disease activity and treatment with oral corticosteroids appeared to be risk factors for laboratory-confirmed SARS-CoV-2 infection.


Assuntos
COVID-19 , Doenças Reumáticas , COVID-19/epidemiologia , Criança , Estudos Transversais , Feminino , Humanos , Masculino , Doenças Reumáticas/tratamento farmacológico , Doenças Reumáticas/epidemiologia , SARS-CoV-2 , Estudos Soroepidemiológicos , Espanha/epidemiologia
4.
Pediatr Rheumatol Online J ; 19(1): 162, 2021 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-34838054

RESUMO

BACKGROUND: This study aimed to assess the baseline characteristics and clinical outcomes of coronavirus disease 2019 (COVID-19) in pediatric patients with rheumatic and musculoskeletal diseases (RMD) and identify the risk factors associated with symptomatic or severe disease defined as hospital admission, intensive care admission or death. METHODS: An observational longitudinal study was conducted during the first year of the SARS-CoV-2 pandemic (March 2020-March 2021). All pediatric patients attended at the rheumatology outpatient clinics of six tertiary referral hospitals in Madrid, Spain, with a diagnosis of RMD and COVID-19 were included. Main outcomes were symptomatic disease and hospital admission. The covariates were sociodemographic and clinical characteristics and treatment regimens. We ran a multivariable logistic regression model to assess associated factors for outcomes. RESULTS: The study population included 77 pediatric patients. Mean age was 11.88 (4.04) years Of these, 30 patients (38.96%) were asymptomatic, 41 (53.25%) had a mild-moderate COVID-19 and 6 patients (7.79%) required hospital admission. The median length of hospital admission was 5 (2-20) days, one patient required intensive care and there were no deaths. Previous comorbidities increased the risk for symptomatic disease and hospital admission. Compared with outpatients, the factor independently associated with hospital admission was previous use of glucocorticoids (OR 3.51; p = 0.00). No statistically significant risk factors for symptomatic COVID-19 were found in the final model. CONCLUSION: No differences in COVID-19 outcomes according to childhood-onset rheumatic disease types were found. Results suggest that associated comorbidities and treatment with glucocorticoids increase the risk of hospital admission.


Assuntos
Antirreumáticos/uso terapêutico , COVID-19/fisiopatologia , Glucocorticoides/uso terapêutico , Hospitalização/estatística & dados numéricos , Doenças Reumáticas/tratamento farmacológico , Adolescente , Artrite Juvenil/tratamento farmacológico , Artrite Juvenil/epidemiologia , Asma/epidemiologia , COVID-19/epidemiologia , Portador Sadio/epidemiologia , Criança , Estudos de Coortes , Comorbidade , Feminino , Cardiopatias/epidemiologia , Doenças Hereditárias Autoinflamatórias/tratamento farmacológico , Doenças Hereditárias Autoinflamatórias/epidemiologia , Humanos , Unidades de Terapia Intensiva Pediátrica , Tempo de Internação , Modelos Logísticos , Estudos Longitudinais , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Lúpus Eritematoso Sistêmico/epidemiologia , Masculino , Análise Multivariada , Obesidade/epidemiologia , Insuficiência Renal Crônica/epidemiologia , Doenças Reumáticas/epidemiologia , Fatores de Risco , SARS-CoV-2 , Índice de Gravidade de Doença , Espanha/epidemiologia
5.
ACS Appl Mater Interfaces ; 13(28): 32865-32875, 2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34251184

RESUMO

A little-studied p-type ternary oxide semiconductor, copper(I) tungstate (Cu2WO4), was assessed by a combined theoretical/experimental approach. A detailed computational study was performed to solve the long-standing debate on the space group of Cu2WO4, which was determined to be triclinic P1. Cu2WO4 was synthesized by a time-efficient, arc-melting method, and the crystalline reddish particulate product showed broad-band absorption in the UV-visible spectral region, thermal stability up to ∼260 °C, and cathodic photoelectrochemical activity. Controlled thermal oxidation of copper from the Cu(I) to Cu(II) oxidation state showed that the crystal lattice could accommodate Cu2+ cations up to ∼260 °C, beyond which the compound was converted to CuO and CuWO4. This process was monitored by powder X-ray diffraction and X-ray photoelectron spectroscopy. The electronic band structure of Cu2WO4 was contrasted with that of the Cu(II) counterpart, CuWO4 using spin-polarized density functional theory (DFT). Finally, the compound Cu2WO4 was determined to have a high-lying (negative potential) conduction band edge underlining its promise for driving energetic photoredox reactions.

6.
ACS Omega ; 5(14): 8097-8107, 2020 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-32309719

RESUMO

A novel series of complexes of the formula [Ru(4,4'-X2-bpy)2(Mebpy-CN)](PF6)2 (X = -CH3, -OCH3, -N(CH3)2; Mebpy-CN = 4-methyl-2,2'-bipyridine-4'-carbonitrile) have been synthesized and characterized by spectroscopic, electrochemical, and photophysical techniques. Inclusion of the electron-withdrawing substituent -CN at one bpy ligand and different electron-donor groups -X at the 4,4'-positions of the other two bpy ligands produce a fine tuning of physicochemical properties. Redox potentials, electronic absorption maxima, and emission maxima correlate well with Hammett's σp parameters of X. Quantum mechanical calculations are consistent with experimental data. All the complexes can be anchored through the nitrile moiety of Mebpy-CN over ZnO nanowires in dye-sensitized solar cells that exhibit an improvement of light to electrical energy conversion efficiency as the electronic asymmetry increases in the series.

8.
Reumatol. clín. (Barc.) ; 15(5): 271-276, sept.-oct. 2019. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-189403

RESUMO

OBJETIVO: En el tratamiento de las uveítis no infecciosas se emplean corticoides y fármacos inmunomoduladores. Su uso ha aumentado en los últimos años y se ha enriquecido con la aparición de nuevos tratamientos. Sin embargo, no existen guías ni protocolos claros de actuación. El objetivo es analizar la respuesta a los fármacos empleados y las características de los pacientes atendidos en una consulta multidisciplinaria de uveítis. MATERIAL Y MÉTODOS: Estudio observacional retrospectivo de los pacientes atendidos desde enero de 2012 hasta diciembre de 2015. Se excluyen las uveítis infecciosas, posquirúrgicas, postraumáticas y los síndromes de enmascaramiento. RESULTADOS: Se incluyeron 216 pacientes. El 58,80% son uveítis sin afectación sistémica, la mayoría idiopáticas, y el 35,65% uveítis con afectación sistémica, asociadas principalmente a espondiloartritis. Las uveítis sin afectación sistémica y las uveítis anteriores se controlaron mejor que el resto con tratamiento local (p = 0,002 y p < 0,001, respectivamente). El 49,76% de los pacientes requirió tratamiento sistémico. De los pacientes tratados con inmunomoduladores, el 53,26% precisó un segundo fármaco y el 31,52%, un tercero. Las mujeres necesitaron inmunomoduladores con más frecuencia que los varones (p = 0,042). El inmunomodulador más empleado fue metotrexato. Las uveítis posteriores respondieron al segundo inmunomodulador peor que las anteriores (p = 0,006). CONCLUSIONES: Casi la mitad de los pacientes necesitaron un fármaco inmunomodulador y algunos precisaron varios cambios sucesivos de fármaco. Las uveítis intermedias resultaron las más refractarias al tratamiento


OBJECTIVE: The treatment of noninfectious uveitis includes steroids and immunomodulatory drugs, the use of which has increased in the last few years, and the options have been enriched with the development of new treatments. However, clear therapeutic guidelines and protocols have not been developed. The purpose is to analyze the response to the drugs used and the characteristics of the patients treated at a multidisciplinary uveitis clinic. MATERIAL AND METHODS: Observational and retrospective study of the patients attended to from January 2012 to December 2015. Infectious, posttraumatic and postoperative uveitis, as well as masquerade syndrome, were excluded. RESULTS: Two hundred six patients were included. Overall, 58.80% had uveitis without association of systemic disease, mostly idiopathic uveitis, and 35.65% had uveitis with systemic involvement, mainly related to spondyloarthritis. Uveitis without systemic association and anterior uveitis achieved disease control with local treatment more frequently than others (p=.002 and p <.001, respectively). In all, 49.76% of the patients required systemic treatment. Among those treated with immunomodulators, 53.26% needed a second drug and 31.52% needed a third drug. Women required immunomodulators more often than men (P=.042). Methotrexate was the most widely used immunomodulator. Posterior uveitis responded less favorably to the second immunomodulator than anterior uveitis (p=.006). CONCLUSIONS: Almost half of the patients needed an immunomodulatory drug and some of them required successive drug changes. Intermediate uveitis was the most treatment-refractory uveitis


Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Imunossupressores/uso terapêutico , Uveíte/tratamento farmacológico , Corticosteroides/uso terapêutico , Quimioterapia Combinada , Metotrexato/uso terapêutico , Estudos Retrospectivos , Fatores Sexuais , Espondilartrite/complicações , Estatísticas não Paramétricas , Resultado do Tratamento , Uveíte/etiologia
9.
Inorg Chem ; 58(7): 4553-4560, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30888802

RESUMO

This study focuses on a solid solution series, Ca(La1- xCe x)2S4 (0 ≤ x ≤ 1), where the f electron density is absent in CaLa2S4 and is progressively increased until it is maximized in CaCe2S4. Correspondingly, these samples, synthesized by a sealed ampule method, showed progressive variations in color ranging from gray for CaLa2S4 to orange-red for CaCe2S4. The crystal structural nuances of both the end members and three solid solutions with x = 0.25, 0.50, and 0.75 were established with the complementary use of synchrotron X-ray diffraction and neutron scattering. Interestingly, these data were consistent with a two-phase composition centered around each nominal solid solution stoichiometry. Optical characterization via diffuse reflectance spectroscopy and Tauc analyses showed a shrinking of the energy band gap (from the UV to vis range) when Ce was progressively introduced into the host CaLa2S4 structure. These data were in concert with electronic band structure calculations, using density functional theory, which showed the progressive formation of an intermediate f band when Ce was introduced intro the structure. Photoelectrochemical measurements in an aqueous redox electrolyte, as well as surface photovoltage and Kelvin probe measurements, revealed all samples to be n-type semiconductors. The valence and conduction band edge positions of the end members and the three solid solutions could be mapped, on both the redox and vacuum reference energy scales, by combining these measurements with the optical data.

11.
Reumatol Clin (Engl Ed) ; 15(5): 271-276, 2019.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-29132749

RESUMO

OBJECTIVE: The treatment of noninfectious uveitis includes steroids and immunomodulatory drugs, the use of which has increased in the last few years, and the options have been enriched with the development of new treatments. However, clear therapeutic guidelines and protocols have not been developed. The purpose is to analyze the response to the drugs used and the characteristics of the patients treated at a multidisciplinary uveitis clinic. MATERIAL AND METHODS: Observational and retrospective study of the patients attended to from January 2012 to December 2015. Infectious, posttraumatic and postoperative uveitis, as well as masquerade syndrome, were excluded. RESULTS: Two hundred six patients were included. Overall, 58.80% had uveitis without association of systemic disease, mostly idiopathic uveitis, and 35.65% had uveitis with systemic involvement, mainly related to spondyloarthritis. Uveitis without systemic association and anterior uveitis achieved disease control with local treatment more frequently than others (p=.002 and p <.001, respectively). In all, 49.76% of the patients required systemic treatment. Among those treated with immunomodulators, 53.26% needed a second drug and 31.52% needed a third drug. Women required immunomodulators more often than men (P=.042). Methotrexate was the most widely used immunomodulator. Posterior uveitis responded less favorably to the second immunomodulator than anterior uveitis (p=.006). CONCLUSIONS: Almost half of the patients needed an immunomodulatory drug and some of them required successive drug changes. Intermediate uveitis was the most treatment-refractory uveitis.


Assuntos
Imunossupressores/uso terapêutico , Uveíte/tratamento farmacológico , Corticosteroides/uso terapêutico , Adulto , Idoso , Quimioterapia Combinada , Feminino , Humanos , Masculino , Metotrexato/uso terapêutico , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores Sexuais , Espondilartrite/complicações , Estatísticas não Paramétricas , Resultado do Tratamento , Uveíte/etiologia
12.
Phys Chem Chem Phys ; 18(4): 2608-16, 2016 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-26698605

RESUMO

Nanocrystalline TiO2 and reduced graphene oxide (TiO2/RGO) composite films were prepared by combining a sol-gel method with hydrothermal treatment, employing titanium isopropoxide (Ti(O(i)Pr)4) and graphene oxide (GO) as starting materials. Although several reports in the literature have explored the benefits of RGO addition in titania films for photocatalysis and water splitting reactions, the role of RGO in the composite is always described as that of a material that is able to act as an electron acceptor and transport electrons more efficiently. However, in most of these reports, no clear evidence for this "role" is presented, and the main focus is deviated to the improved efficiency and not to the reasons for said efficiency. In this study, we employed several techniques to definitively present our understanding of the role of RGO in titania composite films. The TiO2/RGO composite films were characterized by X ray diffraction, Raman spectroscopy, microscopy and electrochemical techniques. In photoelectrochemical water splitting studies, the TiO2/RGO(0.1%) photoelectrodes showed the highest photocurrent density values (0.20 mA cm(-2) at 1.23 VRHE) compared to other electrodes, with an increase of 78% in relation to pristine TiO2 film (0.11 mA cm(-2) at 1.23 VRHE). The transient absorption spectroscopy (TAS) results indicated increases in the lifetime and yield of both the photogenerated holes and electrons. Interestingly, the TiO2/RGO(0.1%) film exhibited the best charge generation upon excitation, corroborating the photoelectrochemical data. We proposed that in films with lower concentrations (<0.1 wt%), the RGO sheets are electron acceptors, and a decrease in the charge recombination processes is the immediate consequence. Thus, both holes and electrons live longer and contribute more effectively to the photocurrent density.

13.
Faraday Discuss ; 183: 389-400, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26434540

RESUMO

The ionic liquid trihexyltetradecylphosphonium 1,2,4-triazolide, [P66614][124Triz], has been shown to chemisorb CO2 through equimolar binding of the carbon dioxide with the 1,2,4-triazolide anion. This leads to a possible new, low energy pathway for the electrochemical reduction of carbon dioxide to formate and syngas at low overpotentials, utilizing this reactive ionic liquid media. Herein, an electrochemical investigation of water and carbon dioxide addition to the [P66614][124Triz] on gold and platinum working electrodes is reported. Electrolysis measurements have been performed using CO2 saturated [P66614][124Triz] based solutions at -0.9 V and -1.9 V on gold and platinum electrodes. The effects of the electrode material on the formation of formate and syngas using these solutions are presented and discussed.

14.
Angew Chem Int Ed Engl ; 54(47): 14164-8, 2015 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-26403938

RESUMO

A new low-energy pathway is reported for the electrochemical reduction of CO2 to formate and syngas at low overpotentials, utilizing a reactive ionic liquid as the solvent. The superbasic tetraalkyl phosphonium ionic liquid [P66614][124Triz] is able to chemisorb CO2 through equimolar binding of CO2 with the 1,2,4-triazole anion. This chemisorbed CO2 can be reduced at silver electrodes at overpotentials as low as 0.17 V, forming formate. In contrast, physically absorbed CO2 within the same ionic liquid or in ionic liquids where chemisorption is impossible (such as [P66614][NTf2]) undergoes reduction at significantly increased overpotentials, producing only CO as the product.

17.
Water Res ; 72: 305-14, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25238917

RESUMO

TiO2 and TiO2/WO3 electrodes, irradiated by a solar simulator in configurations for heterogeneous photocatalysis (HP) and electrochemically-assisted HP (EHP), were used to remediate aqueous solutions containing 10 mg L(-1) (34 µmol L(-1)) of 17-α-ethinylestradiol (EE2), active component of most oral contraceptives. The photocatalysts consisted of 4.5 µm thick porous films of TiO2 and TiO2/WO3 (molar ratio W/Ti of 12%) deposited on transparent electrodes from aqueous suspensions of TiO2 particles and WO3 precursors, followed by thermal treatment at 450 (°)C. First, an energy diagram was organized with photoelectrochemical and UV-Vis absorption spectroscopy data and revealed that EE2 could be directly oxidized by the photogenerated holes at the semiconductor surfaces, considering the relative HOMO level for EE2 and the semiconductor valence band edges. Also, for the irradiated hybrid photocatalyst, electrons in TiO2 should be transferred to WO3 conduction band, while holes move toward TiO2 valence band, improving charge separation. The remediated EE2 solutions were analyzed by fluorescence, HPLC and total organic carbon measurements. As expected from the energy diagram, both photocatalysts promoted the EE2 oxidation in HP configuration; after 4 h, the EE2 concentration decayed to 6.2 mg L(-1) (35% of EE2 removal) with irradiated TiO2 while TiO2/WO3 electrode resulted in 45% EE2 removal. A higher performance was achieved in EHP systems, when a Pt wire was introduced as a counter-electrode and the photoelectrodes were biased at +0.7 V; then, the EE2 removal corresponded to 48 and 54% for the TiO2 and TiO2/WO3, respectively. The hybrid TiO2/WO3, when compared to TiO2 electrode, exhibited enhanced sunlight harvesting and improved separation of photogenerated charge carriers, resulting in higher performance for removing this contaminant of emerging concern from aqueous solution.


Assuntos
Técnicas Eletroquímicas/métodos , Etinilestradiol/química , Óxidos/química , Luz Solar , Titânio/química , Tungstênio/química , Catálise/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Eletrodos , Fluorescência , Microscopia Eletrônica de Varredura , Soluções , Espectrofotometria Ultravioleta , Termodinâmica
18.
ACS Appl Mater Interfaces ; 4(10): 5555-61, 2012 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-23020290

RESUMO

Iron-doped TiO(2) (Fe:TiO(2)) nanoparticles were synthesized by the sol-gel method (with Fe/Ti molar ratio corresponding to 1, 3, and 5%), followed by hydrothermal treatment, drying, and annealing. A similar methodology was used to synthesize TiO(2) and α-Fe(2)O(3) nanoparticles. For comparison, a mixture hematite/titania, with Fe/Ti = 4% was also investigated. Characterization of the samples using Rietveld refinement of X-ray diffraction data revealed that TiO(2) consisted of 82% anatase and 18% brookite; for Fe:TiO(2), brookite increased to 30% and hematite was also identified (0.5, 1.0, and 1.2 wt % for samples prepared with 1, 3, and 5% of Fe/Ti). For hematite/titania mixture, Fe/Ti was estimated as 4.4%, indicating the Rietveld method reliability for estimation of phase composition. Because the band gap energy, estimated as 3.2 eV for TiO(2), gradually ranged from 3.0 to 2.7 eV with increasing Fe content at Fe:TiO(2), it can be assumed that a Fe fraction was also inserted as dopant in the TiO(2) lattice. Extended X-ray absorption fine structure spectra obtained for the Ti K-edge and Fe K-edge indicated that absorbing Fe occupied a Ti site in the TiO(2) lattice, but hematite features were not observed. Hematite particles also could not be identified in the images obtained by transmission electron microscopy, in spite of iron identification by elemental mapping, suggesting that hematite can be segregated at the grain boundaries of Fe:TiO(2).

19.
Santos; SMS; abr. 2011. 1 p.
Não convencional em Português | Sec. Munic. Saúde SP, CRSSUL-Producao, Sec. Munic. Saúde SP, Sec. Munic. Saúde SP | ID: sms-6842
20.
Santos; SMS; abr. 2011. 1 p.
Não convencional em Português | LILACS, Coleciona SUS, CRSSUL-Producao, Sec. Munic. Saúde SP, Sec. Munic. Saúde SP | ID: biblio-938761
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