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1.
Int J Cardiol Cardiovasc Risk Prev ; 21: 200259, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38525097

RESUMEN

Background: Rheumatic valvular disease (RVD) represents a significant health concern in developing countries, yet a scarcity of detailed data exists. This study conducts a comprehensive examination of RVD patients in China, exploring aspects of the disease's spectrum, characteristics, investigation, management, and outcomes. Methods: The China Valvular Heart Disease (China-VHD) study, a nationwide, multicenter, prospective observational study, enrolled 13,917 adults with moderate-to-severe valvular heart disease from April to June 2018. Among these, 2402 patients with native RVD (19.7% of native VHD patients) were analyzed. Results: Among the RVD patients, the median age was 57 years (interquartile range 50-65), with 82.5% falling within the 40-70 age range; females were notably predominant (63.9%). Rheumatic etiology prevailed, particularly in southern regions (48.8%). Multivalvular involvement was observed in 47.4% of RVD cases, and atrial fibrillation emerged as the most common comorbidity (43.2%). Severe RVD affected 64.2% of patients. Valvular interventions were undertaken by 66.9% of RVD patients, predominantly involving surgical valve replacement (90.8%). Adverse events, encompassing all-cause mortality and heart failure hospitalization, occurred in 7.3% of patients during the 2-year follow-up. Multivariable analysis identified factors such as age, geographical region, low body mass index, renal insufficiency, left atrial diameter, and left ventricular ejection fraction <50% (all P < 0.05) associated with adverse events, with valvular intervention emerging as a protective factor (HR: 0.201; 95%CI: 0.139 to 0.291; p < 0.001). Conclusions: This study delivers a comprehensive evaluation of RVD patients in China, shedding light on the spectrum, characteristics, investigation, management, and outcomes of this prevalent condition.

2.
iScience ; 27(3): 109084, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38375234

RESUMEN

This study aimed to investigate the prevalence of diabetes in valvular heart disease (VHD), as well as the relationship of diabetes with severity of valvular lesions and clinical outcome. A total of 11,862 patients with significant (≥moderate) VHD from the China Valvular Heart Disease study were included in the analysis. The primary outcome was the composite of all-cause death, hospitalization for heart failure, and myocardial infarction during two-year follow-up. The prevalence of diabetes was 14.5% (1,721/11,862) in VHD. After adjusting for patients' demographics, diabetes was associated with a significantly lower risk of severe valvular lesion in aortic regurgitation and mitral regurgitation (MR). In multivariable analysis, diabetes was identified as an independent predictor of two-year outcome in patients with MR (hazard ratio: 1.345, 95% confidence interval: 1.069-1.692, p = 0.011). More efforts should be made to enhance our understanding and improve outcomes of concomitant VHD and diabetes.

3.
ESC Heart Fail ; 11(1): 349-365, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38012105

RESUMEN

AIMS: Valvular heart disease (VHD) is one of the leading causes of heart failure. Clinically significant VHD can induce different patterns of cardiac remodelling, and risk stratification is challenging in patients with various degrees of cardiac dysfunction. The study aimed to investigate the prognostic implications of Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) score in patients with VHD. METHODS AND RESULTS: This study used data from the China Valvular Heart Disease (China-VHD) registry, which was a multicentre, prospective, observational cohort study for patients with significant (at least moderate) VHD. In total, 10 446 patients with moderate or greater VHD from the China-VHD study were included in the present analysis. The primary outcome of interest was all-cause mortality within 2 years. Among 10 446 patients with VHD, the mean age was 61.98 ± 13.47 years, and 5819 (55.7%) were male. During 2 years of follow-up, 895 (8.6%) patients died. The MAGGIC score was monotonically and independently associated with mortality in both total cohort [adjusted hazard ratio: 1.095, 95% confidence interval (CI): 1.084-1.107, P < 0.001] and most types of VHD (aortic regurgitation, mitral stenosis, mitral regurgitation, tricuspid regurgitation, mixed aortic stenosis and aortic regurgitation, and multiple VHD). The score was also an independent prognostic factor in patients with or without symptoms or preserved left ventricular ejection fraction (LVEF) and exhibited both satisfactory discrimination and calibration properties in predicting mortality. The prognostic value of MAGGIC score was robust in most quartiles of N-terminal pro-brain natriuretic peptide level, with no significant interaction observed (Pinteraction  = 0.498). Compared with the EuroSCORE II, the MAGGIC score achieved significantly better predictive performance in overall population [C index: 0.769 vs. 0.727; net reclassification improvement index (95% CI): 0.354 (0.313-0.396), P < 0.001; integrated discrimination improvement index (95% CI): 0.069 (0.052-0.085), P < 0.001] and in subgroups of patients divided by therapeutic strategy, LVEF, symptomatic status, stage of VHD, and aetiology of VHD. CONCLUSIONS: The MAGGIC score is a reliable prognostic factor across the range of cardiac dysfunction in VHD and may assist in risk stratification and guide clinical decision-making.


Asunto(s)
Insuficiencia Cardíaca , Enfermedades de las Válvulas Cardíacas , Humanos , Masculino , Persona de Mediana Edad , Anciano , Femenino , Medición de Riesgo/métodos , Volumen Sistólico , Estudios Prospectivos , Función Ventricular Izquierda , Enfermedades de las Válvulas Cardíacas/complicaciones , Enfermedad Crónica , Insuficiencia Cardíaca/diagnóstico , Estudios Observacionales como Asunto , Estudios Multicéntricos como Asunto
4.
J Geriatr Cardiol ; 20(8): 577-585, 2023 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-37675263

RESUMEN

OBJECTIVE: To develop and validate a user-friendly risk score for older mitral regurgitation (MR) patients, referred to as the Elder-MR score. METHODS: The China Senile Valvular Heart Disease (China-DVD) Cohort Study functioned as the development cohort, while the China Valvular Heart Disease (China-VHD) Study was employed for external validation. We included patients aged 60 years and above receiving medical treatment for moderate or severe MR (2274 patients in the development cohort and 1929 patients in the validation cohort). Candidate predictors were chosen using Cox's proportional hazards model and stepwise selection with Akaike's information criterion. RESULTS: Eight predictors were identified: age ≥ 75 years, body mass index < 20 kg/m2, NYHA class III/IV, secondary MR, anemia, estimated glomerular filtration rate < 60 mL/min per 1.73 m2, albumin < 35 g/L, and left ventricular ejection fraction < 60%. The model displayed satisfactory performance in predicting one-year mortality in both the development cohort (C-statistic = 0.73, 95% CI: 0.69-0.77, Brier score = 0.06) and the validation cohort (C-statistic = 0.73, 95% CI: 0.68-0.78, Brier score = 0.06). The Elder-MR score ranges from 0 to 15 points. At a one-year follow-up, each point increase in the Elder-MR score represents a 1.27-fold risk of death (HR = 1.27, 95% CI: 1.21-1.34, P < 0.001) in the development cohort and a 1.24-fold risk of death (HR = 1.24, 95% CI: 1.17-1.30, P < 0.001) in the validation cohort. Compared to EuroSCORE II, the Elder-MR score demonstrated superior predictive accuracy for one-year mortality in the validation cohort (C-statistic = 0.71 vs. 0.70, net reclassification improvement = 0.320, P < 0.01; integrated discrimination improvement = 0.029, P < 0.01). CONCLUSIONS: The Elder-MR score may serve as an effective risk stratification tool to assist clinical decision-making in older MR patients.

5.
Am J Cardiol ; 205: 473-480, 2023 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-37677854

RESUMEN

Low total cholesterol (TC) levels have been found to significantly increase mortality risk in patients experiencing heart failure. However, it is unclear whether the same relation applies specifically to patients with valvular heart disease (VHD). This study included patients with significant VHD from the China Valvular Heart Disease Study. Patients with atherosclerotic cardiovascular disease were excluded. The primary end point of this study was a combined indicator of either all-cause mortality or rehospitalization because of heart failure (HF). The association between TC and the primary outcome was evaluated using Cox proportional hazard models. The cut-off value of TC for predicting mortality or rehospitalization was determined by the maximally selected rank test. The study population comprised 6,235 patients with VHD. Over a 2-year follow-up period, there were 393 deaths and 265 HF rehospitalizations. The adjusted hazard models showed that for every 1 mmol/L decrease in TC, there was a 1.19-fold increased risk of death or HF rehospitalization (adjusted hazard ratio 1.19, 95% confidence interval 1.09 to 1.30, p <0.001). The optimal cut-off value of TC was 3.53 mmol/L; patients at or below this level had significantly higher mortality and HF rehospitalization rates. After adjustment for confounding factors, low TC levels (≤3.53 mmol/L) remained a significant risk factor for patients with aortic regurgitation, mitral regurgitation, and tricuspid regurgitation. Decreased TC levels are associated with an increased risk of death or HF rehospitalization among patients with VHD.


Asunto(s)
Insuficiencia Cardíaca , Enfermedades de las Válvulas Cardíacas , Insuficiencia de la Válvula Mitral , Humanos , Readmisión del Paciente , Enfermedades de las Válvulas Cardíacas/complicaciones , Enfermedades de las Válvulas Cardíacas/epidemiología , Insuficiencia Cardíaca/epidemiología , Colesterol
6.
BMC Med ; 21(1): 257, 2023 07 17.
Artículo en Inglés | MEDLINE | ID: mdl-37455313

RESUMEN

BACKGROUND: Valvular heart disease (VHD) can cause damage to extra-cardiac organs, and lead to multi-organ dysfunction. However, little is known about the cardio-renal-hepatic co-dysfunction, as well as its prognostic implications in patients with VHD. The study sought to develop a multi-biomarker index to assess heart, kidney, and liver function in an integrative fashion, and investigate the prognostic role of cardio-renal-hepatic function in VHD. METHODS: Using a large, contemporary, prospective cohort of 6004 patients with VHD, the study developed a multi-biomarker score for predicting all-cause mortality based on biomarkers reflecting heart, kidney, and liver function (N-terminal pro-B-type natriuretic peptide [NT-proBNP], creatinine, and albumin). The score was externally validated in another contemporary, prospective cohort of 3156 patients with VHD. RESULTS: During a median follow up of 731 (704-748) days, 594 (9.9%) deaths occurred. Increasing levels of NT-proBNP, creatinine, and albumin were independently and monotonically associated with mortality, and a weighted multi-biomarker index, named the cardio-renal-hepatic (CRH) score, was developed based on Cox regression coefficients of these biomarkers. The CRH score was a strong and independent predictor of mortality, with 1-point increase carrying over two times of mortality risk (overall adjusted hazard ratio [95% confidence interval]: 2.095 [1.891-2.320], P < 0.001). The score provided complementary prognostic information beyond conventional risk factors (C index: 0.78 vs 0.81; overall net reclassification improvement index [95% confidence interval]: 0.255 [0.204-0.299]; likelihood ratio test P < 0.001), and was identified as the most important predictor of mortality by the proportion of explainable log-likelihood ratio χ2 statistics, the best subset analysis, as well as the random survival forest analysis in most types of VHD. The predictive performance of the score was also demonstrated in patients under conservative treatment, with normal left ventricular systolic function, or with primary VHD. It achieved satisfactory discrimination (C index: 0.78 and 0.72) and calibration in both derivation and validation cohorts. CONCLUSIONS: A multi-biomarker index was developed to assess cardio-renal-hepatic function in patients with VHD. The cardio-renal-hepatic co-dysfunction is a powerful predictor of mortality and should be considered in clinical management decisions.


Asunto(s)
Insuficiencia Cardíaca , Enfermedades de las Válvulas Cardíacas , Humanos , Estudios Prospectivos , Creatinina , Medición de Riesgo , Biomarcadores , Pronóstico , Enfermedades de las Válvulas Cardíacas/diagnóstico , Riñón , Hígado , Albúminas
7.
Environ Sci Pollut Res Int ; 30(19): 56148-56160, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36913021

RESUMEN

In view of the possible dust pollution of atmospheric caused by large open-air piles, a scheme of using butterfly porous fences is proposed. Based on the actual cause of large open-air piles, this study makes an in-depth study on the wind shielding effect of butterfly porous fences. The effects of hole shape and bottom gap on the flow characteristics are investigated behind the butterfly porous fence with the porosity of 0.273 through the combined methods of computational fluid dynamics and validating PIV experiments. The streamlines distribution and X-velocity behind the porous fence of numerical simulation are in good agreement with the experimental results and based on the research group's previous work, the numerical model is feasible. The concept of the wind reduction ratio is proposed to quantitatively evaluate the wind shielding effect of the porous fence. The results show that the butterfly porous fence with circular holes provided the best shelter effect with the wind reduction ratio of 78.34%, and the optimal bottom gap ratio is about 0.075 with the highest wind reduction ratio of 80.1%. When a butterfly porous fence is applied on site, the diffusion range of dust in open-air piles is significantly reduced compared with that without a fence. In conclusion, the circular holes with the bottom gap ratio of 0.075 are suitable for the butterfly porous fence in practical applications and provide a solution for wind-induced control in large open-air piles.


Asunto(s)
Contaminación del Aire , Mariposas Diurnas , Animales , Polvo/análisis , Porosidad , Contaminación del Aire/análisis , Simulación por Computador , Viento
8.
Eur Heart J Qual Care Clin Outcomes ; 9(3): 227-239, 2023 04 26.
Artículo en Inglés | MEDLINE | ID: mdl-35612991

RESUMEN

AIMS: Tricuspid regurgitation (TR) may cause damage to liver and kidney function. The Model for End-Stage Liver Disease excluding international normalized ratio (MELD-XI) and the model with albumin replacing international normalized ratio (MELD-Albumin) scores, which include both liver and kidney function indexes, may predict mortality in patients with TR. The study aimed to analyse the prognostic value of MELD-XI and MELD-Albumin scores in patients with significant TR. METHODS AND RESULTS: A total of 1825 patients with at least moderate pure native TR from the China Valvular Heart Disease study between April and June 2018, were included in this analysis. The primary outcome was all-cause death within 2 years. Of 1825 patients, 165 (9.0%) died during follow-up. Restricted cubic splines revealed that hazard ratio for death increased monotonically with greater modified MELD scores. The MELD-XI and MELD-Albumin scores, as continuous variables or categorized using thresholds determined by maximally selected rank statistics, were independently associated with 2-year mortality (all adjusted P < 0.001). Both scores provided incremental value over prognostic model without hepatorenal indexes {MELD-XI score: net reclassification index [95% confidence interval (95% CI), 0.237 (0.138-0.323)]; MELD-Albumin score: net reclassification index (95% CI), 0.220 (0.122-0.302)}. Results were similar in clinically meaningful subgroups, including but not limited to patients under medical treatment and those with normal left ventricular ejection fraction. Models including modified MELD scores were established for prognostic evaluation of significant TR. CONCLUSION: Both MELD-XI and MELD-Albumin scores provided incremental prognostic information and could play important roles in risk assessment in patients with significant TR.


Asunto(s)
Enfermedad Hepática en Estado Terminal , Insuficiencia de la Válvula Tricúspide , Humanos , Pronóstico , Enfermedad Hepática en Estado Terminal/complicaciones , Enfermedad Hepática en Estado Terminal/diagnóstico , Insuficiencia de la Válvula Tricúspide/complicaciones , Insuficiencia de la Válvula Tricúspide/diagnóstico , Volumen Sistólico , Índice de Severidad de la Enfermedad , Función Ventricular Izquierda , Albúminas
9.
Front Cardiovasc Med ; 9: 937412, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35990948

RESUMEN

Background: The prognostic value of blood pressure (BP) and resting heart rate (RHR) in tricuspid regurgitation (TR) patients is unknown. Aims: This study aimed to investigate the associations of BP and RHR with all-cause mortality in patients with TR. Methods: A total of 2,013 patients with moderate or severe TR underwent echocardiography and BP measurement. The associations of routinely measured BP and RHR with 2-year all-cause mortality were analyzed. Results: The cohort had 45.9% male patients and a mean age of 62.5 ± 15.9 years. At the 2-year follow-up, 165 patient deaths had occurred. The risk of death decreased rapidly, negatively correlating with systolic blood pressure (SBP) up to 120 mmHg and diastolic blood pressure (DBP) up to 70 mmHg. For RHR, the risk increased in direct proportion, starting at 80 beats per min. After adjusting for age, sex, body mass index (BMI), diabetes, coronary heart disease, pulmonary hypertension, estimated glomerular filtration rate (eGFR), and NYHA class, SBP [hazard ratio (HR):0.89; 95% CI:0.823-0.957 per 10 mmHg increase; P =0.002], DBP (HR:0.8; 95% CI:0.714-0.908 per 10 mmHg increase; P < 0.001), and RHR (HR: 1.1; 95% CI: 1.022-1.175 per 10 beats per min increase; P = 0.011) were independently associated with all-cause mortality. These associations persisted after further adjustments for echocardiographic indices, medications, serological tests, and etiologies. Conclusion: In this cohort of patients with TR, routinely measured BP and RHR were associated with all-cause mortality independently. However, further large-scale, high-quality studies are required to validate our findings.

10.
Front Public Health ; 10: 844832, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35651861

RESUMEN

Eczema, one of the most prevalent inflammatory skin diseases among children, is potentially influenced by genetic, environmental and social factors. However, few studies have investigated the effect of residential environment and lifestyle on childhood eczema. Therefore, this study conducted a cross-sectional study based on 2,781 preschool children in Shenzhen, China, during 2015-2016. Logistic regression models were employed to analyze the associations between residential/household environment, lifestyle, dietary habits and eczema in children. The prevalence of eczema among children in Shenzhen was 24.6%. Significant associations (increased odds >50%, P < 0.05) were found between childhood eczema and the factors of using composite wood floors (adjusted OR = 1.777 for doctor-diagnosed eczema, 1.911 for eczema-like symptoms), living in a villa/townhouse (aOR = 3.102, 2.156), the presence of mold or damp stains in the child's room (aOR = 1.807, 2.279), and rarely cleaning the child's room (aOR = 1.513, 1.540). In addition, watching TV/playing computer games for more than one hour per day was significantly associated with eczema (aOR = 1.172, 1.174). Notably, we found that eating rice/pasta one to three times per week may elevate the risk of eczema-like symptoms (aOR = 1.343), which warrants further investigation. In addition, ambient air pollution, in the covariates, may also affect childhood eczema. Therefore, avoiding these adverse factors and creating a low-risk environment are crucial to prevent childhood eczema.


Asunto(s)
Dermatitis Atópica , Eccema , Niño , Preescolar , China/epidemiología , Estudios Transversales , Dermatitis Atópica/epidemiología , Eccema/epidemiología , Humanos , Estilo de Vida , Factores de Riesgo
11.
Environ Sci Pollut Res Int ; 28(34): 47182-47195, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33890211

RESUMEN

A large amount of dust particles produced by the wind in an open-air pile is one of the important reasons for air pollution. Studying the law of dust diffusion in local areas is of great significance for the atmospheric particulate control. In this study, a pile of sodium carbonate in a large open-air pile in Weifang, China, is regarded as the research object. The dispersion characteristics of dust particles around the pile under the action of unidirectional wind are studied through wind tunnel test and numerical simulation. The complex atmospheric environment is simplified as unidirectional wind, and the influence of different wind speeds on the dispersion of particles with diverse sizes in the pile is studied. Although a large gap exists between the assumption and the real atmospheric environment, this study provides a reference for the evaluation of the pollution scope of blowing dust and prevention and control of pollution. Results show that a high-concentration range of the dust exists near the pile behind the wind direction and may continue to spread to the height due to the influence of a whirlpool, and the dispersion distance and width can increase with the increase in wind speed. The increase in particle diameter increases the kinetic energy loss of particles for the fluid. Under the same starting speed, the dispersion distance of dust decreases with the increase in particle diameter. With the increase in particle diameter, the dust concentration distribution presents the trend of interior hollowing and high-concentration area fragmenting.


Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , China , Difusión , Polvo/análisis , Monitoreo del Ambiente , Tamaño de la Partícula
12.
Front Cardiovasc Med ; 8: 800961, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-35111828

RESUMEN

BACKGROUND: The prognostic impact and optimal treatment of left ventricular systolic dysfunction in patients with moderate aortic regurgitation (AR) remain unknown. We aimed to assess the prognostic value of left ventricular ejection fraction (LVEF) in patients with moderate AR and explore the potential benefits of aortic valve intervention (AVI). METHODS: In total, 1,211 consecutive patients with moderate AR (jet width, 25-64% of LV outflow tract; vena contracta, 0.3-0.6 cm; regurgitant volume, 30-59 mL/beat; regurgitant fraction, 30-49%; effective regurgitation orifice, 0.10-0.29 cm2) prospectively registered between April and June 2018 at 46 academic hospitals were included. The primary outcome was a composite of death or hospitalization for heart failure (HHF). The optimal LVEF threshold for predicting the primary outcome was determined through the penalized spline shape and maximally selected rank statistics. RESULTS: During the 2-year follow-up, 125 deaths or HHF occurred. In the penalized splines, the relative hazard of death or HHF monotonically increased with decreasing LVEF. In the multivariate analysis, LVEF ≤55% was identified as the best threshold for independently predicting death or HHF under medical treatment (adjusted hazard ratio [HR]: 2.18; 95% confidence interval [CI] 1.38-3.42; P = 0.001), with substantial incremental values (integrated discrimination improvement index = 0.018, P = 0.030; net reclassification improvement index = 0.225, P = 0.006; likelihood ratio test P < 0.001). Among patients with LVEF 35-55%, AVI within 6 months of diagnosis was associated with a reduced risk of death or HHF compared with medical treatment alone (adjusted HR: 0.15; 95% CI: 0.04-0.50; P = 0.002), whereas this benefit was markedly attenuated when LVEF was ≤35% (adjusted HR: 0.65; 95% CI: 0.21-1.97; P = 0.441, P-interaction = 0.010) or >55% (adjusted HR: 0.40; 95% CI: 0.14-1.15; P = 0.089, P-interaction = 0.723). CONCLUSIONS: LVEF is an independent and incremental prognostic factor in patients with moderate AR, with LVEF ≤55% being a robust marker of poor prognosis. Patients with LVEF 35-55% may benefit from early surgical correction of moderate AR. Further studies are warranted to validate our findings in a randomized setting. REGISTRATION: China Valvular Heart Disease Study (China-VHD study, NCT03484806); clinicaltrials.gov/ct2/show/NCT03484806.

13.
Environ Sci Technol ; 52(4): 1940-1945, 2018 02 20.
Artículo en Inglés | MEDLINE | ID: mdl-29338215

RESUMEN

This study tested the mercury emission characteristics of six municipal solid waste incinerators (MSWIs) and recommended future mercury control via adjusting operational parameters. The results indicated that over 99% of the mercury in solid wastes ended in fly ash and flue gas, of which 3.3-66.3% was emitted to air through stack gas. Mercury in the stack gas was mainly in the form of oxidized mercury (Hg2+), the proportion (65.4-89.0%) of which was far higher than previous estimation (15%). Mercury removal efficiencies (MRE) of the tested incinerators were in the range of 33.6-95.2%. The impact of waste incineration capacity, gas flow, fly ash yield, and activated carbon (AC) injection on MRE were analyzed. We found that the MRE was significantly linearly correlated to the ratio of AC injection and fly ash yield (correlation coefficient = 0.98, significance <0.01). AC injection value is determined based on the control of dioxin emissions without considering mercury control in traditional design. To increase MRE of MSWIs, the AC injection should increase from around 100 mg·Nm-3 to 135 mg·Nm-3 for grate furnace combustor and 170 mg·Nm-3 for circulation fluidized bed combustor, so as to reach a MRE of 90%.


Asunto(s)
Incineración , Mercurio , Carbono , Ceniza del Carbón , Residuos Sólidos
14.
J Nanosci Nanotechnol ; 17(4): 2515-519, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29652118

RESUMEN

A facile In Situ growth method was presented here for the preparation of graphitic carbon nitride (g-C3N4)/graphene composites, in which the direct growth and deposition of g-C3N4 nanosheets from organic N and C sources on the graphene surfaces was achieved to form the 3D contacted structure. The resulting 3D architecture possessed multilevel porous structure and efficient g-C3N4/graphene interfaces, which facilitated the fast electron transfer at the interfaces. Photoluminescence spectra showed that the recombination of photogenerated electrons and holes in the g-C3N4/graphene composites was greatly inhibited by the introduction of graphene, indicating the more efficient separation of electrons and hole in the g-C3N4/graphene composites than in pure g-C3N4. The catalytic activity of g-C3N4/graphene composite photocatalyst was enhanced by over two fold compared to pure g-C3N4 for removal of Rhodamine B under simulated sun light irradiation. This work indicates that the metal-free g-C3N4/graphene composite photocatalyst is a promising nanomaterial for further applications in water treatment.

15.
Huan Jing Ke Xue ; 37(2): 459-65, 2016 Feb 15.
Artículo en Chino | MEDLINE | ID: mdl-27363131

RESUMEN

Waste incineration is one of the important atmospheric mercury emission sources. The aim of this article is to explore the atmospheric mercury pollution level of waste incineration industry from Chongqing. This study investigated the mercury emissions from a municipal solid waste incineration plant and a medical waste incineration plant in Chongqing. The exhaust gas samples in these two incineration plants were obtained using USA EPA 30B method. The mercury concentrations in the fly ash and bottom ash samples were analyzed. The results indicated that the mercury concentrations of the municipal solid waste and medical waste incineration plant in Chongqing were (26.4 +/- 22.7) microg x m(-3) and (3.1 +/- 0.8) microg x m(-3) in exhaust gas respectively, (5279.2 +/- 798.0) microg x kg(-1) and (11,709.5 +/- 460.5) microg x kg(-1) in fly ash respectively. Besides, the distribution proportions of the mercury content from municipal solid waste and medical waste in exhaust gas, fly ash, and bottom ash were 34.0%, 65.3%, 0.7% and 32.3%, 67.5%, 0.2% respectively; The mercury removal efficiencies of municipal solid waste and medical waste incineration plants were 66.0% and 67.7% respectively. The atmospheric mercury emission factors of municipal solid waste and medical waste incineration plants were (126.7 +/- 109.0) microg x kg(-1) and (46.5 +/- 12.0) microg x kg(-1) respectively. Compared with domestic municipal solid waste incineration plants in the Pearl River Delta region, the atmospheric mercury emission factor of municipal solid waste incineration plant in Chongqing was lower.


Asunto(s)
Contaminantes Atmosféricos/análisis , Atmósfera/análisis , Incineración , Mercurio/análisis , China , Ceniza del Carbón/análisis , Residuos Industriales , Residuos Sanitarios , Residuos Sólidos
16.
Huan Jing Ke Xue ; 37(10): 3766-3773, 2016 Oct 08.
Artículo en Chino | MEDLINE | ID: mdl-29964407

RESUMEN

Municipal solid waste (MSW) incineration is one of the most important atmospheric mercury emission sources. To investigate the mercury concentrations of MSW and mercury emission characteristics in incineration plants, this study analyzed the MSW sampled in 3 typical MSW incineration plants in Shanghai, Guangzhou and Wuhu respectively. The exhaust gas samples in incineration plants were sampled by using OH (Ontario Hydro) method. The mercury concentrations in fly ash, and bottom ash samples were also analyzed. The results indicated that mercury concentrations of MSW in Shanghai, Guangzhou, and Wuhu incineration plants were (0.39±0.04) mg·kg-1, (0.57±0.05) mg·kg-1, and (0.27±0.08) mg·kg-1 respectively. The mercury concentrations of exhaust gas in Guangzhou, Wuhu MSW incineration plants were (9.5±3.9) µg·m-3 and (24.1±6.0) µg·m-3 respectively; Particulate mercury (Hgp), gaseous oxidized mercury (Hg2+), and gaseous elemental mercury (Hg0) represented (0.9±0.8)%, (89.0±5.4)%, (10.1±4.6)% in Guangzhou MSW incineration plant, and (1.0±0.8)%, (65.4±27.6)%, (33.6±27.5)% in Wuhu MSW incineration plant, respectively. Gaseous oxidized mercury (Hg2+) of exhaust gas in different incineration process showed different distribution proportions. Besides, mercury removal efficiency of Guangzhou, Wuhu MWS incineration plants was 96.7% and 33.7%, respectively. The atmospheric mercury emission factors of Shanghai, Guangzhou, and Wuhu MSW incineration plants were (0.156±0.016) mg·kg-1, (0.019±0.002) mg·kg-1, (0.178±0.027) mg·kg-1 respectively. Compared with MSW incineration plants in Japan and Korea, the atmospheric mercury emission factor of Guangzhou incineration plant was slightly lower; Atmospheric mercury emission factors of Shanghai and Wuhu MSW incineration plants were close to those of domestic fractional MSW incineration plants.

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