Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Ultrason Sonochem ; 58: 104630, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31450336

RESUMO

Graphene is a two-dimensional material with unique structure and excellent properties. After first being successfully prepared in 2004, it rapidly became a research hotspot in the fields of materials, chemistry, physics, and engineering. Currently, there are many methods for preparing graphene, such as ball milling method, chemical oxidation-reduction, chemical vapor deposition, and liquid-phase exfoliation. Among these methods, liquid-phase exfoliation is the most important preparation method. In this paper, ultrasound-assisted liquid-phase exfoliation is systematically studied. The output power and frequency of the ultrasonic crusher used in the experiment are 100 W and 20 kHz, respectively. Results show that ultrasonic waves can affect the size and thickness distribution of graphene sheets; ultrasound-assisted deoxycholic acid sodium aqueous solution has a good exfoliation effect. In addition, the effects of the 3 liquid-phase systems on preparing graphene are studied, including organic solvent system, aqueous surfactant system, and ionic liquids system; the improvement efforts for ultrasound-assisted liquid-phase exfoliation method are discussed including the exploration of new solvents and optimization of exfoliation process. The application of auxiliary agent-assisted liquid-phase exfoliation method is also discussed.

2.
Environ Res ; 175: 221-227, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31146094

RESUMO

BACKGROUND: It is not known whether environmental gamma radiation measured in US cities has detectable adverse health effects. We assessed whether short-term exposure to gamma radiation emitted from ambient air particles [gamma particle activity (PRγ)] is associated with reduced pulmonary function in chronic obstructive pulmonary disease (COPD) patients. OBJECTIVE: We hypothesize that the inhalation of gamma radiation emitted from ambient air particles may be associated with reduced pulmonary function in individuals with COPD. METHODS: In 125 patients with COPD from Eastern Massachusetts who had up to 4 seasonal one-week assessments of particulate matter ≤2.5 µm (PM2.5), black carbon (BC), and sulfur followed by spirometry. The US EPA continuously monitors ambient gamma (γ) radiation including γ released from radionuclides attached to particulate matter that is recorded as 9 γ-energy spectra classes (i = 3-9) in counts per minute (CPMγ) in the Boston area (USA). We analyzed the associations between ambient and indoor PRγi (up to one week) and pre and post-bronchodilator (BD) forced expiratory volume in 1 s (FEV1) and with forced vital capacity (FVC) using mixed-effects regression models. We estimated indoor PRγi using the ratio of the indoor-to-outdoor sulfur in PM2.5 as a proxy for infiltration of ambient radionuclide-associated particles. RESULTS: Overall, exposures to ambient and indoor PRγi were associated with a similar decrease in pre- and post-BD FEV1 and FVC. For example, ambient PRγ3 exposure averaged from the day of pulmonary function testing through the previous 3 days [IQR of 55.1 counts per minute (CPMγ)] was associated with a decrease in pre-BD FEV1 of 21.0 ml (95%CI: -38.5 to -3.0 ml; p < 0.01) and pre-BD FVC of 27.5 ml [95% confidence interval (CI): -50.7 to -5.0 ml; p < 0.01] with similar effects adjusting for indoor and outdoor BC and PM2.5. CONCLUSION: Our results show that short-term ambient and indoor exposures to environmental gamma radiation associated with particulate matter are associated with reduced pre- and post-BD pulmonary function in patients with COPD.

3.
Ultrason Sonochem ; 55: 273-278, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30712850

RESUMO

The application of ultrasonic technology in the treatment of organic pollutants in water has attracted more and more attention in recent years. Compared with conventional treatment, ultrasonic treatment is more efficient and time saving. Ultrasonic technology is effective for the degradation of many refractory organic pollutants. In this paper, the principle, influencing factors and various methods of ultrasonic degradation of organic pollutants are studied in view of ultrasonic treatment alone, ultrasound treatment methods combined with biocatalysts, chemical oxidation and adsorption techniques, respectively. In addition, the problems existing in the treatment of organic pollutants in water by ultrasonic technology are analyzed and the development direction is put forward.

4.
J Air Waste Manag Assoc ; 69(3): 266-276, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30230977

RESUMO

Numerous studies have reported a positive association between ambient fine particles and daily mortality, but little is known about the particle properties or environmental factors that may contribute to these effects. This study assessed potential modification of radon on PM2.5 (particulate matter with an aerodynamic diameter <2.5 µm)-associated daily mortality in 108 U.S. cities using a two-stage statistical approach. First, city- and season-specific PM2.5 mortality risks were estimated using over-dispersed Poisson regression models. These PM2.5 effect estimates were then regressed against mean city-level residential radon concentrations to estimate overall PM2.5 effects and potential modification by radon. Radon exposure estimates based on measured short-term basement concentrations and modeled long-term living-area concentrations were both assessed. Exposure to PM2.5 was associated with total, cardiovascular, and respiratory mortality in both the spring and the fall. In addition, higher mean city-level radon concentrations increased PM2.5-associated mortality in the spring and fall. For example, a 10 µg/m3 increase in PM2.5 in the spring at the 10th percentile of city-averaged short-term radon concentrations (21.1 Bq/m3) was associated with a 1.92% increase in total mortality (95% CI: 1.29, 2.55), whereas the same PM2.5 exposure at the 90th radon percentile (234.2 Bq/m3) was associated with a 3.73% increase in total mortality (95% CI: 2.87, 4.59). Results were robust to adjustment for spatial confounders, including average planetary boundary height, population age, percent poverty and tobacco use. While additional research is necessary, this study suggests that radon enhances PM2.5 mortality. This is of significant regulatory importance, as effective regulation should consider the increased risk for particle mortality in cities with higher radon levels. Implications: In this large national study, city-averaged indoor radon concentration was a significant effect modifier of PM2.5-associated total, cardiovascular, and respiratory mortality risk in the spring and fall. These results suggest that radon may enhance PM2.5-associated mortality. In addition, local radon concentrations partially explain the significant variability in PM2.5 effect estimates across U.S. cities, noted in this and previous studies. Although the concept of PM as a vector for radon progeny is feasible, additional research is needed on the noncancer health effects of radon and its potential interaction with PM. Future air quality regulations may need to consider the increased risk for particle mortality in cities with higher radon levels.

5.
Environ Int ; 121(Pt 2): 1210-1216, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30376999

RESUMO

BACKGROUND: Decay products of radioactive materials may attach to ambient fine particles and form radioactive aerosol. Internal ionizing radiation source from inhaled radioactive aerosol may contribute to the fine particulate matter (PM2.5)-inflammation pathway. However, few studies in humans have examined the associations. OBJECTIVES: To examine the associations between particle radioactivity and biomarkers of oxidative stress and inflammation among participants from the Framingham Offspring and Third Generation cohorts. METHODS: We included 3996 participants who were not current smokers and lived within 50 km from our central air pollution monitoring station. We estimated regional mean gross beta radioactivity from monitors in the northeastern U.S. as a surrogate for ambient radioactive particles, and calculated the 1- to 28-day moving averages. We used linear regression models for fibrinogen, tumor necrosis factor α, interleukin-6, and myeloperoxidase which were measured once, and linear mixed effect models for 8-epi-prostaglandin F2α, C-reactive protein, intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein-1 (MCP-1), P-selectin, and tumor necrosis factor receptor-2 that were measured up to twice, adjusting for demographics, individual- and area-level socioeconomic positions, time, meteorology, and PM2.5. We also examined whether the associations differed by median age, sex, diabetes status, PM2.5 levels, and black carbon levels. RESULTS: The mean age was 54 years and 54% were women. An interquartile range (3 × 10-3 pCi/m3) higher beta radioactivity level at the 7-day moving average was associated with 5.09% (95% CI: 0.92, 9.43), 2.65% (1.10, 4.22), and 4.71% (95% CI: 3.01, 6.44) higher levels of interleukin-6, MCP-1, and P-selectin, but with 7.01% (95% CI: -11.64, -2.15) and 2.70% (95% CI: -3.97, -1.42) lower levels of 8-epi-prostaglandin F2α and ICAM-1, respectively. CONCLUSIONS: Regional mean particle radioactivity was positively associated with interleukin-6, MCP-1, and P-selectin, but negatively with ICAM-1 and 8-epi-prostaglandin F2α among our study participants.


Assuntos
Poluentes Radioativos do Ar/toxicidade , Biomarcadores/sangue , Inflamação/induzido quimicamente , Estresse Oxidativo , Aerossóis , Exposição Ambiental , Feminino , Humanos , Inflamação/sangue , Modelos Lineares , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Material Particulado/toxicidade , Fuligem
6.
Arq Bras Cardiol ; 109(3 Supl 1): 1-104, 2017.
Artigo em Inglês, Português | MEDLINE | ID: mdl-29044300
7.
Arq. bras. cardiol ; 109(3,supl.1): 1-104, Sept. 2017. tab, graf
Artigo em Inglês | LILACS-Express | ID: biblio-887936
8.
J Am Soc Hypertens ; 10(5): 413-9, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27039160

RESUMO

The aim of this cross-sectional study was to evaluate the association between dental infections and systemic diseases in the Indigenous population of Brazil. A representative sample of 225 Indigenous (≥19 years) was assessed. The T-test and bivariate and logistic models were used to assess the associations of diabetes, hypertension, and obesity with dental caries and destructive periodontal disease. After adjustments for covariates, dental caries were associated with hypertension (odds ratio = 1.95; 95% confidence interval: 1.03-3.66; P = .04). Individuals with destructive periodontal disease had a higher systolic blood pressure (124 ± 20.34 mm Hg) than those without destructive periodontal disease (117.52 ± 16.54 mm Hg; P = .01). In conclusion, dental infections were found to be associated with hypertension in the present population. Thus, patients diagnosed with hypertension should be referred for dental evaluation and vice versa.


Assuntos
Cárie Dentária/complicações , Diabetes Mellitus/epidemiologia , Hipertensão/complicações , Obesidade/complicações , Doenças Periodontais/complicações , Adulto , Idoso , Brasil/epidemiologia , Estudos Transversais , Cárie Dentária/epidemiologia , Sacarose na Dieta/efeitos adversos , Feminino , Inquéritos Epidemiológicos , Humanos , Hipertensão/epidemiologia , Masculino , Pessoa de Meia-Idade , Obesidade/epidemiologia , Doenças Periodontais/epidemiologia , Grupos Populacionais , Prevalência , Adulto Jovem
9.
J Periodontol ; 82(5): 683-8, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21054230

RESUMO

BACKGROUND: This pilot study evaluates the association of severe periodontitis with pulse wave velocity (PWV), carotid artery intima-medial thickness (IMT), and clinical, metabolic, and atherogenic inflammatory markers in 79 subjects with heterozygous familial hypercholesterolemia (hFH). All subjects were free of previous vascular disease manifestations. METHODS: The body mass index (in kilograms per square meter), plasma lipids, glucose, C-reactive protein, and white blood cell counts were evaluated. After full-mouth periodontal examinations, patients were categorized into the severe periodontitis group (SPG) or non-severe periodontitis group (NSPG). RESULTS: The SPG showed significantly higher values of cholesterol-year scores, triglycerides, glucose, PWV, IMT, and diastolic blood pressure (DBP) (P ≤0.05) than the NSPG. After adjustment for traditional risk factors for atherosclerosis, only the association between severe periodontitis and DBP (odds ratio: 3.1; 95% CI: 1.1 to 8.5; P = 0.03) was confirmed. CONCLUSION: In individuals with hFH, severe periodontitis was associated with a higher DBP, which suggests that severe periodontitis, itself, may contribute to the increased cardiovascular risk profile in this population.


Assuntos
Hiperlipoproteinemia Tipo II/complicações , Hipertensão/complicações , Periodontite/complicações , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Perda do Osso Alveolar/classificação , Aterosclerose/patologia , Biomarcadores/análise , Velocidade do Fluxo Sanguíneo/fisiologia , Glicemia/análise , Pressão Sanguínea/fisiologia , Índice de Massa Corporal , Proteína C-Reativa/análise , Artéria Carótida Primitiva/patologia , Colesterol/sangue , Feminino , Heterozigoto , Humanos , Hiperlipoproteinemia Tipo II/genética , Contagem de Leucócitos , Masculino , Pessoa de Meia-Idade , Bolsa Periodontal/classificação , Projetos Piloto , Triglicerídeos/sangue , Túnica Íntima/patologia , Túnica Média/patologia , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA