Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 422
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Environ Sci Pollut Res Int ; 26(35): 35978-35987, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31709485

RESUMO

Biochar has been considered as a promising soil amendment for improving fertility and mitigating N2O emission from the arable land. However, biochar's effectiveness in acidic tea soil and underlying mechanisms are largely unknown. We conducted a short-term microcosm experiment using two biochars (1% w/w, LB, generated from legume and NLB, non-legume biomass, respectively) to investigate the effects of biochar amendments on soil chemical properties, N2O emission, and microbial community in an acidic soil. Soil and headspace gas samples were taken on 1, 10, and 30 day's incubation. Biochar amendment increased soil pH and DOC, however, significantly reduced soil inorganic N. Both biochars at ~ 1% addition had little effect on microbial CO2 respiration but suppressed soil N2O emission by ~ 40% during the incubation. The divergence in N2O efflux rates between soils with and without biochar addition aligned to some degree with changes in soil pH, inorganic N, and dissolved organic C (DOC). We also found that biochar addition significantly modified the fungal community structure, in particular the relative abundance of members of Ascomycota, but not the bacterial community. Furthermore, the copy number of nosZ, the gene encoding N2O reductase, was significantly greater in biochar-amended soils than the soil alone. Our findings contribute to better understanding of the impact of biochar on the soil chemical properties, soil N2O emission, and microbial community and the consequences of soil biochar amendment for improving the health of acidic tea soil.


Assuntos
Poluentes Atmosféricos/análise , Carvão Vegetal/química , Dióxido de Nitrogênio/análise , Microbiologia do Solo , Ácidos , Poluentes Atmosféricos/química , Bactérias , Biomassa , Microbiota , Dióxido de Nitrogênio/química , Solo/química , Chá
2.
Environ Sci Process Impacts ; 21(10): 1729-1735, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31478540

RESUMO

Soot is an important carbonaceous nanoparticle (CNP) frequently found in natural environments. Its entry into surface waters can occur directly via surface runoff or infiltration, as well as via atmospheric deposition. Pristine soot is likely to rapidly undergo aggregation and subsequent sedimentation in aquatic environments. Further, soot can sorb a variety of organic contaminants, such as S-metolachlor (log KD = 3.25 ± 0.12). During atmospheric transport, soot can be chemically transformed by reactive oxygen species including NO2. The presence of natural organic matter (NOM) in surface waters can further affect the aquatic fate of soot. To better understand the processes driving the fate of soot and its interactions with contaminants, pristine and NO2-transformed model soot suspensions were investigated in the presence and absence of NOM. NO2-oxidized soot showed a smaller particle size, a higher number of particles remaining in suspension, and a decreased sorption of S-metolachlor (log KD = 2.47 ± 0.40). In agreement with findings for other CNPs, soot stability against aggregation was increased for both pristine and NO2 transformed soot in the presence of NOM.


Assuntos
Acetamidas/química , Dióxido de Nitrogênio/química , Fuligem/química , Acetamidas/análise , Nanopartículas , Tamanho da Partícula , Fuligem/análise , Suspensões
3.
Environ Sci Pollut Res Int ; 26(31): 32029-32039, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31493084

RESUMO

Small for gestational age (SGA) is defined as intrauterine growth retardation or small sample, referring to the 10th percentile of birth weight lower or two standard deviations less than the average weight at the same gestational age. SGA infants bring great economic and psychological burdens to families and society. The association between exposure to air pollution and SGA in underdeveloped cities with poor air quality remains unclear. Thus, this study is conducted to estimate the effects of maternal exposure to air pollutants on SGA numbers. Birth information was collected from the Huangshi Maternity and Children's Health Hospital from January 1st to December 31st in 2017. Data of pregnancy exposure were accessed using stationary monitors. These data included particulate matter less than or equal to 10 µm in aerodynamic diameter (PM10), particulate matter less than or equal to 2.5 µm in aerodynamic diameter (PM2.5), nitrogen dioxide (NO2), and sulfur dioxide (SO2). Multivariate logistic regression models were performed to estimate the association between ambient air pollution and the risk of SGA during different exposure windows. It was found that a 1 µg/m3 increase in air pollution concentrations during the entire pregnancy was associated with a higher risk of SGA, with an adjusted odds ratio (OR) and 95% confidence interval (CI) of 1.055 (1.035-1.076), 1.084 (1.053-1.116), 1.000 (0.953-1.049), and 1.051 (0.968-1.141) for PM10, PM2.5, NO2, and SO2, respectively. Thus, it is suggested that exposure to air pollution is associated with an increased risk of SGA. The effects of PM10 and PM2.5 were more stable than NO2 and SO2.


Assuntos
Poluentes Atmosféricos/química , Poluição do Ar/efeitos adversos , Exposição Materna/efeitos adversos , Dióxido de Nitrogênio/química , Material Particulado/análise , Dióxido de Enxofre/química , Poluentes Atmosféricos/análise , Peso ao Nascer , Criança , China , Estudos Transversais , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Recém-Nascido Pequeno para a Idade Gestacional , Razão de Chances , Gravidez , Dióxido de Enxofre/efeitos adversos
4.
Int J Mol Sci ; 20(15)2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31370230

RESUMO

Effect of H2O and NH3 on the synergistic oxidation reaction of SO2 and NO2 is investigated by theoretical calculation using the molecule system SO2-2NO2-nH2O (n = 0, 1, 2, 3) and SO2-2NO2-nH2O-mNH3 (n = 0, 1, 2; m = 1, 2). Calculated results show that SO2 is oxidized to SO3 by N2O4 intermediate. The additional H2O in the systems can reduce the energy barrier of oxidation step. The increasing number of H2O molecules in the systems enhances the effect and promotes the production of HONO. When the proportion of H2O to NH3 is 1:1, with NH3 included in the system, the energy barrier is lower than two pure H2O molecules in the oxidation step. The present study indicates that the H2O and NH3 have thermodynamic effects on promoting the oxidation reaction of SO2 and NO2, and NH3 has a more significant role in stabilizing product complexes. In these hydrolysis reactions, nethermost barrier energy (0.29 kcal/mol) can be found in the system SO2-2NO2-H2O. It is obvious that the production of HONO is energetically favorable. A new reaction mechanism about SO2 oxidation in the atmosphere is proposed, which can provide guidance for the further study of aerosol surface reactions.


Assuntos
Amônia/química , Dióxido de Nitrogênio/química , Dióxido de Enxofre/química , Água/química , Aerossóis , Cinética , Oxirredução , Termodinâmica
5.
Biosens Bioelectron ; 143: 111606, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466049

RESUMO

A disposable gas-sensing paper-based device (gPAD) was fabricated in origami design which integrates the gas adsorbent and the electrochemical detection zone in a single device. The gPAD for the determination of NOx gas uses a screen-printed graphene electrode modified with copper nanoparticles (CuNP/SPGE) to achieve high sensitivity and selectivity. The gPAD detects both, NO and NO2 (as NOx) with same current responses. The measurement could be performed directly through differential pulse voltammetry (DPV) with a detection limit as low as 0.23 vppm and 0.03 vppm with exposure times of 25 min and 1 h, respectively. The reproducibility in terms of relative standard deviation was less than 5.1% (n = 7 devices) at 25, 75 and 125 vppm NO2 and the life-time of this device was more than 30 days. The gPAD was applied to detect NOx in air and exhaust gases from cars. In comparison with spectrophotometry, there are no significant differences between both methods using a paired t-test of the results on a 95% confidence level. The designed gPAD can provide a new template model for other gas sensors with features of disposability and portability for fieldwork analysis at low cost.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Óxido Nítrico/isolamento & purificação , Dióxido de Nitrogênio/isolamento & purificação , Cobre/química , Grafite/química , Humanos , Nanopartículas Metálicas/química , Óxido Nítrico/química , Dióxido de Nitrogênio/química , Papel
6.
Artigo em Inglês | MEDLINE | ID: mdl-31362448

RESUMO

Guangxi Zhuang Autonomous Region, located in the southwest of China, has rapidly developed since the late 2000s. Similar to other regions, economic development has been accompanied by environmental problems, especially air pollution, which can adversely affect the health of residents in the area. In this study, we estimated the negative health effects of three major ambient pollutants, Particulate Matter with a diameter of 10 µm or less (PM10), Sulfur Dioxide (SO2) and Nitrogen Dioxide (NO2) in Guangxi from 2011 to 2016 using a log-linear exposure-response function. We monetarized the economic loss using the value of statistical life (VSL) and the cost of illness (COI) methods. The results show that the total possible short-term all-cause mortality values due to PM10, SO2, and NO2 were 28,396, with the confidence intervals from 14,664 to 42,014 (14,664-42,014), 24,618 (15,480-33,371), and 46,365 (31,158-61,423), respectively. The mortality from the three pollutants was 48,098 (19,972-75,973). The economic loss of the health burden from the three pollutants was 40,555 (24,172-57,585), which was 2.86% (1.70-4.06%) of the regional gross domestic product. The result of the comparative analysis among different cities showed that urbanization, industrialization, and residents' income are important factors in air-pollution-caused health damage and subsequent economic loss. We conclude that the health burden caused by ambient pollutants in developing regions, accompanied by its rapid socio-economic growth, is significant and tighter regulation is needed in the future to alleviate air pollution and mitigate the related health damage.


Assuntos
Poluentes Atmosféricos/toxicidade , Poluição do Ar/efeitos adversos , Dióxido de Nitrogênio/química , Material Particulado/química , Dióxido de Enxofre/química , Poluentes Atmosféricos/análise , Poluição do Ar/análise , China , Cidades , Exposição Ambiental , Humanos , Urbanização
7.
Chem Biol Interact ; 309: 108708, 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31199928

RESUMO

Colon cancer is one of the most lethal cancers worldwide even with the significant progress made in screening techniques and therapeutic agents. Genetic mutations in tumors complicated the treatments, and the survival rate remains low for patients at late or metastatic stages. KRAS gene mutation which leads to failure of the EGFR targeted therapies stands for an example of the challenges in clinical sites. Therefore, development of novel agents for colon cancer treatment is in need. Natural and synthetic coumarin derivatives have been suggested with various biological activities with pharmacologic potential including anti-cancer capacity. Here in this study, five coumarin derivatives, include trifluoromethyl-, dimethoxy-, and/or nitro-substitutions at different positions, were synthesized. Their cancer inhibition potential was investigated in various cancer cell lines. Our data demonstrated that one nitro-coumarin derivate, 5,7-Dimethoxy-4-methyl-6-nitro-chromen-2-one, exhibits cytotoxicity specifically towards colon cancer cells under competitive EC50. Our results showed that this compound can effectively suppress colon cancer cells harboring either wild type or mutant KRAS genes, and that it could inhibit short-term proliferation, long term proliferation, and migration capacities of cancer cells. Finally, we demonstrated that this coumarin derivate facilitates cancer cell death through activation of apoptosis pathway. Our results suggest that this coumarin derivate is a promising lead drug worth further investigation and development for future cancer treatment.


Assuntos
Apoptose/efeitos dos fármacos , Cumarínicos/farmacologia , Dióxido de Nitrogênio/química , Proteínas Proto-Oncogênicas p21(ras)/genética , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Cumarínicos/química , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Mutação
8.
Environ Sci Pollut Res Int ; 26(19): 19220-19227, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31069654

RESUMO

The influence of flue gas composition on the specific resistance of coal-fired fly ash is studied in this paper. We conclude that the negative electrons of NO2 and SO2 gases are strong. The probabilities of electron desorption on SO2 and NO2 negative ions are lower than that in air atmosphere at high temperature. Therefore, the introduction of SO2 causes NO2 to reduce the specific resistance value of coal-fired fly ash. When the pores on the surface of fly ash particles are filled with SO2, no change will occur in NO2, average pore size, pore volume, and specific surface area of fly ash particles, thereby resulting in fly ash that remains unchanged from the resistance value. When humidity increases, the surface conduction effect is greatly enhanced, and the specific resistance value is lowered considerably. Therefore, the specific resistance of dust can be reduced by humidification.


Assuntos
Poluentes Atmosféricos/análise , Cinza de Carvão/análise , Carvão Mineral , Poeira/análise , Dióxido de Nitrogênio/química , Dióxido de Enxofre/química , Propriedades de Superfície
9.
Epilepsy Res ; 152: 52-58, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30909052

RESUMO

BACKGROUND: We aimed to study the short-term association between air pollutants and hospitalization for epilepsy in 47 hospitals from 10 cities in eastern China. METHOD: We identified hospital epilepsy admissions in 2014 and 2015. A conditional Poisson regression model was used to examine the association between air pollutants and hospital admission, with temperature and relative humidity adjusted using the natural spline (ns) function. Pollutants included sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and particulate matter (PM). The association was stratified by sex, age, and geographic region in single-pollutant and two-pollutant models. RESULTS: An interquartile (IQR) increase of NO2 and CO on the concurrent day is correlated with an increased admission of 2.0% (0.5%, 3.6%) and 1.1% (0.1%, 2.1%), respectively. The association is stronger in children (≤18 years) and in northern China, but did not vary with sex. A positive association was also observed on the previous day for CO [1.5%, 95% confidence interval (CI): 0.3%, 2.6%], NO2 (2.5%, 95% CI: 0.6%, 4.3%), and PM2.5 (1.32%, 95% CI: 0.16%, 2.48%). Moving average concentration of 7 days for all pollutants was associated with decreased admission (CO: -1.29%, NO2: -0.4.69%, SO2:-2.12%, PM2.5:-0.98%, PM10:-1.70%). CONCLUSION: Exposures to NO2 and CO on concurrent days, and PM2.5 on the previous day, are associated with increased epilepsy hospitalization, whereas cumulative exposure appeared protective.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Poluição do Ar/efeitos adversos , Poluição do Ar/estatística & dados numéricos , Epilepsia/induzido quimicamente , Epilepsia/epidemiologia , Hospitalização/estatística & dados numéricos , Adolescente , Adulto , Fatores Etários , Monóxido de Carbono/efeitos adversos , Monóxido de Carbono/análise , Criança , Pré-Escolar , China/epidemiologia , Feminino , Humanos , Lactente , Modelos Logísticos , Masculino , Dióxido de Nitrogênio/análise , Dióxido de Nitrogênio/química , Estudos Retrospectivos , Dióxido de Enxofre/efeitos adversos , Dióxido de Enxofre/análise , Adulto Jovem
10.
J Environ Sci (China) ; 79: 67-73, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30784465

RESUMO

Mercury (Hg) is a toxic and bio-accumulating heavy metal that is predominantly released via the combustion of coal. Due to its toxicity, the Environmental Protection Agency (EPA) has introduced Mercury and Air Toxics Standards (MATS) Rule regarding allowable Hg emissions. In order to reduce emissions, power plants have widely adopted activated carbon (AC) injection. AC injection has proven to be an effective method to reduce Hg emissions, but the re-emission of previously adsorbed Hg during unit operation, likely due to changing temperature or flue gas composition, could be problematic. This study specifically examined the effects of temperature and sulfur trioxide (SO3) concentration, by ramping temperature and SO3 concentration independently and simultaneously, on AC samples that are already exposed to flue gas and saturated in presence of Hg, sulfur dioxide (SO2) and nitric oxide (NO). Of these two suspected factors to cause re-emission, temperature had the greater impact and resulted in re-emission of both elemental and oxidized Hg with a greater fraction of oxidized Hg, which can be attributed to elemental Hg being more strongly bonded to the AC surface. Surprisingly, exposing the samples to increasing concentrations of SO3 had nearly no effect under the conditions examined in this study, possibly as a result of the samples being already saturated with sulfur prior to the SO3 ramp tests to simulate transient conditions in the plant.


Assuntos
Poluentes Atmosféricos/química , Carbono/química , Mercúrio/química , Centrais Elétricas , Óxidos de Enxofre/química , Carvão Mineral , Dióxido de Nitrogênio/química , Dióxido de Enxofre/química , Temperatura Ambiente
11.
ACS Sens ; 4(3): 678-686, 2019 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-30799610

RESUMO

In order to develop high performance chemoresistive gas sensors for Internet of Everything applications, low power consumption should be achieved due to the limited battery capacity of portable devices. One of the most efficient ways to reduce power consumption is to lower the operating temperature to room temperature. Herein, we report superior gas sensing properties of SnS2 nanograins on SiO2 nanorods toward NO2 at room temperature. The gas response is as high as 701% for 10 ppm of NO2 with excellent recovery characteristics and the theoretical detection limit is evaluated to be 408.9 ppb at room temperature, which has not been reported for SnS2-based gas sensors to the best of our knowledge. The SnS2 nanograins on the template used in this study have excessive sulfur component (Sn:S = 1:2.33) and exhibit p-type conduction behavior. These results will provide a new perspective of nanostructured two-dimensional materials for gas sensor applications on demand.


Assuntos
Técnicas de Química Analítica/instrumentação , Limite de Detecção , Dióxido de Nitrogênio/análise , Dióxido de Silício/química , Sulfetos/química , Temperatura Ambiente , Compostos de Estanho/química , Modelos Moleculares , Conformação Molecular , Dióxido de Nitrogênio/química , Porosidade
12.
Food Chem ; 284: 303-311, 2019 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-30744862

RESUMO

This study examined high voltage atmospheric cold plasma (HVACP) technology as a non-thermal intervention for inactivating Salmonella enterica serovar Typhimurium LT2 (ST2) in tender coconut water (TCW). Treatment with HVACP in air at 90 kV for 120 s inactivated 1.30 log10 of ST2. Development of a TCW stimulant suggested an interfering role of magnesium and phosphate salts with HVACP inactivation. Generation of reactive gas species, viz. ozone and hydrogen peroxides were found to be responsible for microbial inactivation. The addition of 400 ppm citric acid to the TCW effectively reduced ST2 by 5 log10 during HVACP treatment. Under these conditions, higher cellular leakage and morphological damage were observed in ST2. Minimal physico-chemical changes in TCW were observed with HVACP treatment, except for an 84.35% ascorbic acid loss (added externally). These results demonstrate a potential pathway for developing highly effective cold plasma treatments to preserve fruit and vegetable juices.


Assuntos
Cocos/química , Sucos de Frutas e Vegetais/análise , Gases em Plasma/farmacologia , Salmonella typhimurium/efeitos dos fármacos , Ácido Ascórbico/farmacologia , Ácido Cítrico/farmacologia , Microbiologia de Alimentos , Viabilidade Microbiana/efeitos dos fármacos , Dióxido de Nitrogênio/química , Dióxido de Nitrogênio/farmacologia , Ozônio/química , Ozônio/farmacologia
13.
ACS Sens ; 3(12): 2558-2565, 2018 12 28.
Artigo em Inglês | MEDLINE | ID: mdl-30431256

RESUMO

It is well-known that the applicability of phthalocyanine chemiresistors suffers from long recovery time after NO2 exposure. This circumstance enforces the necessity to operate the sensors at elevated temperatures (150-200 °C), which shortens the sensor lifetime and increases its power consumption (regardless, a typical measurement period is longer than 15 min). In this paper, we propose a new method for fast and effective recovery by UV-vis illumination at a low temperature (55 °C). The method is based on short illumination following short NO2 exposure. To support and optimize the method, we investigated the effects of light in the wavelength and intensity ranges of 375-850 nm and 0.2-0.8 mW/mm2, respectively, on the rate of NO2 desorption from the phthalocyanine sensitive layer during the recovery period. This investigation was carried out for a set of phthalocyanine materials (ZnPc, CuPc, H2Pc, PbPc, and FePc) operating at slightly elevated temperatures (55-100 °C) and was further supported by the analysis of UV-vis and FTIR spectral changes. We found out that the light with the wavelength shorter than 550 nm significantly accelerates the NO2 desorption from ZnPc, CuPc, and FePc, and allows bringing the measurement period under 2 min and decreasing the sensor power consumption by 75%. Possible mechanisms of the light-stimulated desorption are discussed.


Assuntos
Isoindóis/química , Isoindóis/efeitos da radiação , Luz , Dióxido de Nitrogênio/química , Temperatura Ambiente
14.
ACS Sens ; 3(12): 2629-2636, 2018 12 28.
Artigo em Inglês | MEDLINE | ID: mdl-30456951

RESUMO

Black and blue phosphorus (both allotropes of elementary phosphorus) have recently been widely explored as an active material for electronic devices, and their potential in gas sensing applications has been demonstrated. On the other hand, amorphous red phosphorus (a-RP), a much cheaper and readily available phosphorus allotrope, has seldom been investigated as an electronic material, and its gas sensing properties have never been studied. In this work we have investigated these properties of a-RP by combining experimental characterizations with theoretical calculations. We found that a-RP exhibited an amphoteric character for detecting both commonly regarded reducing and oxidizing gas molecules, featuring a negative correlation between the electrical resistance of a-RP and the gas concentration. Interestingly, the a-RP based sensors appear to be particularly suitable for room-temperature NO2 detection, exhibiting excellent sensitivity and selectivity, as well as fast temporal response and recovery. A unique sensing feature of a-RP toward NO2 was identified, which is associated with the expansion of P-P bonds upon NO2 chemisorption. Based on density functional theory calculations we proposed a physiochemical model to elaborate the synergistic effects of the P-P bond expansion and Langmuir isotherm adsorption on the electronic properties and gas sensing processes of a-RP.


Assuntos
Dióxido de Nitrogênio/análise , Fósforo/química , Semicondutores , Adsorção , Teoria da Densidade Funcional , Técnicas Eletroquímicas/métodos , Gases/análise , Gases/química , Modelos Químicos , Dióxido de Nitrogênio/química , Oxirredução , Temperatura Ambiente
15.
ACS Sens ; 3(9): 1666-1674, 2018 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-30073834

RESUMO

We demonstrate proof-of-concept graphene sensors for environmental monitoring of ultralow concentration NO2 in complex environments. Robust detection in a wide range of NO2 concentrations, 10-154 ppb, was achieved, highlighting the great potential for graphene-based NO2 sensors, with applications in environmental pollution monitoring, portable monitors, automotive and mobile sensors for a global real-time monitoring network. The measurements were performed in a complex environment, combining NO2/synthetic air/water vapor, traces of other contaminants, and variable temperature in an attempt to fully replicate the environmental conditions of a working sensor. It is shown that the performance of the graphene-based sensor can be affected by coadsorption of NO2 and water on the surface at low temperatures (≤70 °C). However, the sensitivity to NO2 increases significantly when the sensor operates at 150 °C and the cross-selectivity to water, sulfur dioxide, and carbon monoxide is minimized. Additionally, it is demonstrated that single-layer graphene exhibits two times higher carrier concentration response upon exposure to NO2 than bilayer graphene.


Assuntos
Poluentes Atmosféricos/análise , Grafite/química , Dióxido de Nitrogênio/análise , Adsorção , Poluentes Atmosféricos/química , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Fenômenos Magnéticos , Dióxido de Nitrogênio/química , Estudo de Prova de Conceito , Temperatura Ambiente
16.
Sci Total Environ ; 642: 155-167, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29894875

RESUMO

The urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT), has been proposed to reduce synthetic fertilizer-N losses, including nitrous oxide (N2O) emissions from agricultural soils. However, the response of N2O emission to NBPT amendment is inconsistent across soils and associated microbial mechanisms remain largely unknown. Here we performed a meta-analysis of the effects of NBPT on N2O emissions and found NBPT significantly reduced N2O emissions in alkaline soils whereas no obvious effects exhibited in acid soils. Based on the finding of meta-analysis that pH was a key modifier in regulating the effect of NBPT on N2O emissions, we selected two arable soils differing in pH and conducted a microcosm study. In conjunction with measurement of N2O emission, community structure and abundance of functional guilds were assessed using T-RFLP and qPCR. Our results showed NBPT retarded urea hydrolysis and inhibited nitrification, but stimulated N2O emission in alkaline soil, whereas it exhibited no remarkable effects in acid soil, thereby only partly confirming the results of meta-analysis. Abundances of AOB and ureC-containing bacteria decreased, while abundance of AOA increased in both soils with NBPT addition. For acid soil, N2O emissions were significantly correlated with both abundances and community structures of AOA and ureC-containing bacteria, as well as abundance of AOB; for alkaline soil, abundances and community structures of AOB were correlated with N2O emission, as well as community structures of ureC-containing bacteria and archaea, indicating an inconsistent response pattern of community traits of N2O emissions-related functional guilds to NBPT between alkaline soil and acid soil. Our findings suggest that (i) efficacy of NBPT in N2O emission was mainly influenced by soil pH and (ii) variable effects of NBPT on N2O emission might originate not only from the direct effect of NBPT on community traits of urease-positive microbes, but from the indirect effect on ammonia oxidizers.


Assuntos
Fertilizantes , Dióxido de Nitrogênio/química , Compostos Organofosforados/química , Microbiologia do Solo , Amônia , Concentração de Íons de Hidrogênio , Nitrificação , Dióxido de Nitrogênio/análise , Solo
17.
Anal Biochem ; 550: 132-136, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29729279

RESUMO

The most widely recognized activity of the large family of the metalloenzyme carbonic anhydrases (CAs) is the diffusion-controlled hydration of CO2 to HCO3- and one proton, and the less rapid dehydration of HCO3- to CO2: CO2 + H2O ⇆ HCO3- + H+. CAs also catalyze the reaction of water with other electrophiles such as aromatic esters, sulfates and phosphates, thus contributing to lending to CAs esterase, sulfatase and phosphatase activity, respectively. Renal CAII and CAIV are involved in the reabsorption of nitrite, the autoxidation product of the signalling molecule nitric oxide (NO): 4 NO + O2 + 2 H2O → 4 ONO- + 4 H+. Bovine and human CAII and CAIV have been reported to exert nitrite reductase and nitrous anhydride activity: 2 NO2- + 2 H+ ⇆ [2 HONO] ⇆ N2O3 + H2O. In the presence of L-cysteine, NO may be formed. In the literature, these issues are controversial, mainly due to analytical shortcomings, i.e., the inability to detect authentic HONO and N2O3. Here, we present a gas chromatography-mass spectrometry (GC-MS) assay to unambiguously detect and quantify the nitrous anhydrase activity of CAs. The assay is based on the hydrolysis of N2O3 in H218O to form ON18O- and 18ON18O-. After pentafluorobenzyl bromide derivatization and electron capture negative-ion chemical ionization of the pentafluorobenzyl nitro derivatives, quantification is performed by selected-ion monitoring of the anions with mass-to-charge (m/z) ratios of 46 (ONO-), m/z 48 (ON18O- and 18ONO-), m/z 50 (18ON18O-) and m/z 47 (O15NO-, internal standard).


Assuntos
Anidrase Carbônica II/química , Anidrase Carbônica IV/química , Óxido Nítrico/química , Nitrito Redutases/química , Dióxido de Nitrogênio/química , Animais , Bovinos , Humanos
18.
ACS Sens ; 3(5): 1048-1055, 2018 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-29737152

RESUMO

Stretchable gas sensors that accommodate the shape and motion characteristics of human body are indispensable to a wearable or attachable smart sensing system. However, these gas sensors usually have poor response and recovery kinetics when operated at room temperature, and especially suffer from humidity interference and mechanical robustness issues. Here, we demonstrate the first fully stretchable gas sensors which are operated at room temperature with enhanced stability against humidity. We created a crumpled quantum dot (QD) sensing layer on elastomeric substrate with flexible graphene as electrodes. Through the control over the prestrain of the flexible substrate, we achieved a 5.8 times improvement in NO2 response at room temperature with desirable stretchability even under 1000 stretch/relax cycles mechanism deformation. The uniformly wavy structural configuration of the crumpled QD gas-sensing layer enabled an improvement in the antihumidity interference. The sensor response shows a minor vibration of 15.9% at room temperature from relative humidity of 0 to 86.7% compared to that of the flat-film sensors with vibration of 84.2%. The successful assembly of QD solids into a crumpled gas-sensing layer enabled a body-attachable, mechanically robust, and humidity-resistant gas sensor, opening up a new pathway to room-temperature operable gas sensors which may be implemented in future smart sensing systems such as stretchable electronic nose and multipurpose electronic skin.


Assuntos
Gases/análise , Umidade , Pontos Quânticos , Eletrodos , Grafite/química , Humanos , Cinética , Microscopia Eletrônica de Varredura , Dióxido de Nitrogênio/química , Temperatura Ambiente , Dispositivos Eletrônicos Vestíveis
19.
Environ Sci Pollut Res Int ; 25(18): 17726-17734, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29671231

RESUMO

This study was conducted to quantify, by an approach proposed by the World Health Organization (WHO), the daily hospital admissions for chronic obstructive pulmonary disease (COPD) related to exposure to particulate matter (PM10) and oxidants such as ozone (O3), sulfur dioxide (SO2), and nitrogen dioxide (NO2) in a heavily polluted city in Iran. For the health impact assessment, in terms of COPD, the current published relative risk (RR) and baseline incidence (BI) values, suggested by the WHO, and the 1-h O3 concentrations and daily PM10, NO2, and SO2 concentrations were compiled. The results showed that 5.9, 4.1, 1.2, and 1.9% of the COPD daily hospitalizations in 2011 and 6.6, 1.9, 2.3, and 2.1% in 2012 were attributed to PM10, O3, SO2, and NO2 concentrations exceeding 10 µg/m3, respectively. This study indicates that air quality and the high air pollutant levels have an effect on COPD morbidity. Air pollution is associated with visits to emergency services and hospital admissions. A lower relative risk can be achieved if some stringent control strategies for reducing air pollutants or emission precursors are implemented.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Dióxido de Nitrogênio/análise , Ozônio/análise , Material Particulado/análise , Doença Pulmonar Obstrutiva Crônica/epidemiologia , Dióxido de Enxofre/análise , Poluentes Atmosféricos/química , Cidades , Poluentes Ambientais , Hospitalização , Humanos , Incidência , Irã (Geográfico) , Dióxido de Nitrogênio/química , Risco , Dióxido de Enxofre/química
20.
J Air Waste Manag Assoc ; 68(7): 755-762, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29652218

RESUMO

Some metal etching operations emit limited flow rates of waste gases with reddish-brown NO2 fume, which may cause visual and acidic-odor complaints, as well as negative health effects. In this study, tests were performed by passing caustic-treated waste gases vented from Al-etching operations through columns packed either with virgin or regenerated granular activated carbon (GAC) to test their adsorptive conversion performance of NO2 in the gases. The gases contained 5-55 ppm NO2 and acetic and nitric acids of below 3 ppm. Exhausted carbon was regenerated by scrubbing it with caustic solution and water, and dried for further adsorption tests. Results indicate that with an (empty bed residence time (EBRT) of 0.15 sec for the gas through the GAC-packed space, around 60% of the influent NO2 of 54 ppm could be removed, and 47% of the removed NO2 was converted by and desorbed from the carbon as NO. GAC used in the present study could be regenerated at least twice to restore its capacity for NO2 adsorption. Within EBRTs of 0.076-0.18 sec, the adsorptive conversion capacity was linearly varied with EBRT. In practice, with an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO2 (kg GAC)-1 with an influent NO2 of 40 ppm can be used as a basis for system design. IMPLICATIONS: Some metal etching operations emit waste gases with reddish-brown (yellow when diluted) NO2 fume which may cause visual and acidic-odor complaints, as well as negative health effects. This study provides a simple process for the adsorptive conversion of NO2 in caustic-treated waste gases vented from metal-etching operations through a GAC column. With an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO2 (kg GAC)-1 with an influent NO2 of 40 ppm can be used as a basis for system design. Saturated GAC can be regenerated at least twice by simply scrubbing it with aqueous caustic solution.


Assuntos
Poluentes Atmosféricos/química , Carbono/química , Carvão Vegetal/química , Dióxido de Nitrogênio/química , Adsorção , Poluentes Atmosféricos/análise , Gases , Metalurgia , Dióxido de Nitrogênio/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA