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1.
Environ Pollut ; 265(Pt B): 115086, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32806464

RESUMO

In recent years, the Chinese government has made great efforts to jointly control and prevent air pollution, especially fine particulate matter (PM2.5). However, these efforts are challenged by technical constraints due to the significant temporal and spatial heterogeneity of PM2.5 across China. In this study, the Affinity Zone Identification Approach (AZIA), which combines rotated principal component analysis (RPCA) with revised clustering analysis, was developed and employed to regionalize PM2.5 pollution in China based on data from 1496 air quality monitoring sites recorded from 2013 to 2017. Two clustering methods, cluster analysis with statistical test (CAST) and K-center-point (K-medoids) clustering, were compared and revised to eliminate unspecified sites. Site zonation was finally extended to the municipality scale for the convenience of the controlling measures. The results revealed that 17 affinity zones with 5 different labels from clean to heavily polluted areas could be identified in China. The heavily polluted areas were mainly located in central and eastern China as well as Xinjiang Province, with regional average annual PM2.5 concentrations higher than 66 µg/m3. The new approach provided more comprehensive and detailed affinity zones than obtained in a previous study (Wang et al., 2015b). The North China Plain and Northeastern China were both further divided into northern and southern parts based on different pollution levels. In addition, five affinity zones were first recognized in western China. The findings provide not only a theoretical basis to further display the temporal and spatial variations in PM2.5 but also an effective solution for the cooperative control of air pollution in China.


Assuntos
Poluição do Ar , Poluição Ambiental , China , Humanos , Material Particulado , Fenômenos Físicos
2.
Environ Pollut ; 265(Pt B): 115122, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32806468

RESUMO

Current practices employed by most wastewater treatment plants (WWTP) are unable to completely remove endocrine disrupting compounds (EDCs) from reclaimed waters, and consistently discharge these substances to receiving systems. Effluent-dominated and dependent surface waters, especially during low instream flows, can increase exposure and risks to aquatic organisms due to adverse biological effects associated with EDCs. Given the ecological implications that may arise from exposure to such compounds, the present a multi-approach study examined spatio-temporal estrogenic potential of wastewater effluent to fish in East Canyon Creek (ECC), Utah, USA, a unique urban river with instream flows seasonally influenced by snowmelt. Juvenile rainbow trout (Oncorhynchus mykiss) were caged at different upstream and downstream sites from an effluent discharge during the summer and fall seasons. In the summer, where approximately 50% of the streamflow was dominated by effluent, fish from the upstream and a downstream site, located 13 miles away from the effluent discharge, presented significantly elevated concentrations of plasma vitellogenin (VTG). Similarly, significantly high 17ß-estradiol to 11-ketotestosterone ratios were measured in the summer across all sites and time points, compared to the fall. In the laboratory, juvenile fish and primary hepatocytes were exposed to concentrated effluent and surface water samples. Quantification of VTG, although in significantly lower levels, resembled response patterns observed in fish from the field study. Furthermore, analytical quantification of common EDCs in wastewater revealed the presence of estriol and estrone, though these did not appear to be related to the observed biological responses, as these were more significant in sites were no EDCs were detected. These combined observations suggest potential estrogenicity for fish in ECC under continuous exposures and highlight the advantages of following weight-of-evidence (WoE) approaches for environmental monitoring, as targeted analytically-based assessments may or may not support the identification of causative contaminants for adverse biological effects.


Assuntos
Disruptores Endócrinos , Estrona , Animais , Fenômenos Físicos , Utah , Vitelogeninas
3.
Nat Commun ; 11(1): 3289, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620890

RESUMO

The spatial organization of chromosomes has key functional roles, yet how chromosomes fold remains poorly understood at the single-molecule level. Here, we employ models of polymer physics to investigate DNA loci in human HCT116 and IMR90 wild-type and cohesin depleted cells. Model predictions on single-molecule structures are validated against single-cell imaging data, providing evidence that chromosomal architecture is controlled by a thermodynamics mechanism of polymer phase separation whereby chromatin self-assembles in segregated globules by combinatorial interactions of chromatin factors that include CTCF and cohesin. The thermodynamics degeneracy of single-molecule conformations results in broad structural and temporal variability of TAD-like contact patterns. Globules establish stable environments where specific contacts are highly favored over stochastic encounters. Cohesin depletion reverses phase separation into randomly folded states, erasing average interaction patterns. Overall, globule phase separation appears to be a robust yet reversible mechanism of chromatin organization where stochasticity and specificity coexist.


Assuntos
Cromatina/química , Conformação Molecular , Fenômenos Físicos , Polímeros/química , Análise de Célula Única/métodos , Fator de Ligação a CCCTC/química , Fator de Ligação a CCCTC/metabolismo , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular , Cromatina/metabolismo , Montagem e Desmontagem da Cromatina , Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/metabolismo , Células HCT116 , Humanos , Ligação Proteica , Processos Estocásticos , Termodinâmica
4.
Nature ; 583(7814): 35-36, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32612219
5.
Waste Manag ; 115: 25-35, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32717549

RESUMO

Prediction of methane (CH4) generation and settlement of biodegrading municipal solid waste (MSW) is of primary interest to landfills aiming at biogas recovery for energy generation and MSW stabilization. We investigate these two concurring processes using datasets from 35 laboratory column tests and 8 pilot- and full-scale landfill cells available in the literature. We fit the datasets using three CH4 generation models, i.e., conventional first-order decay (FOD) model, coupled FOD model, and coupled Gompertz model. The latter two models are proposed in this study which couple CH4 generation with biological settlement strain (εB) instead of elapsed time. Each model requires only four to five input parameters which can be reasonably estimated a priori based on the initial conditions of the MSW and landfills. The performances of the models are compared using jackknife resampling approach and normalized root-mean-square error (NRMSE) values. The coupled Gompertz model results in on average 50% lower NRMSE when predicting the time-dependent CH4 generation in all the datasets compared to the other two models. Thus, we demonstrate that CH4 generation from biodegrading MSW in landfills can be better predicted using the corresponding εB than the elapsed time.


Assuntos
Eliminação de Resíduos , Resíduos Sólidos/análise , Metano , Fenômenos Físicos , Instalações de Eliminação de Resíduos
6.
Nature ; 582(7811): 189-190, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32528089
7.
Chemosphere ; 255: 127007, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32416396

RESUMO

Chiral organophosphorus pollutants are existed ubiquitously in the ecological environment, but the enantioselective toxicities of these nerve agents to humans and their molecular bases have not been fully elucidated. Using experimental and computational approaches, this story was to explore the neurotoxic response process of the target acetylcholinesterase (AChE) to chiral phenthoate and further decipher the microscopic mechanism of such toxicological effect at the enantiomeric level. The results showed that the toxic reaction of AChE with chiral phenthoate exhibited significant enantioselectivity, and (R)-phenthoate (K=1.486 × 105 M-1) has a bioaffinity for the nerve enzyme nearly three times that of (S)-phenthoate (K=4.503 × 104 M-1). Dynamic research outcomes interpreted the wet experiments, and the inherent conformational flexibility of the target enzyme has a great influence on the enantioselective neurotoxicological action processes, especially reflected in the conformational changes of the three key loop regions (i.e. residues His-447, Gly-448, and Tyr-449; residues Gly-122, Phe-123, and Tyr-124; and residues Thr-75, Leu-76, and Tyr-77) around the reaction patch. This was supported by the quantitative results of conformational studies derived from circular dichroism spectroscopy (α-helix: 34.7%→30.2%/31.6%; ß-sheet: 23.6%→19.5%/20.7%; turn: 19.2%→22.4%/21.9%; and random coil: 22.5%→27.9%/25.8%). Meanwhile, via analyzing the modes of toxic action and free energies, we can find that (R)-phenthoate has a strong inhibitory effect on the enzymatic activity of AChE, as compared with (S)-phenthoate, and electrostatic energy (-23.79/-17.77 kJ mol-1) played a critical role in toxicological reactions. These points were the underlying causes of chiral phenthoate displaying different degrees of enantioselective neurotoxicity.


Assuntos
Acetilcolinesterase/química , Poluentes Ambientais/química , Poluentes Ambientais/toxicidade , Síndromes Neurotóxicas/etiologia , Compostos Organotiofosforados/química , Compostos Organotiofosforados/toxicidade , Dicroísmo Circular , Humanos , Modelos Teóricos , Simulação de Dinâmica Molecular , Fenômenos Físicos , Estrutura Secundária de Proteína , Estereoisomerismo
8.
Chemosphere ; 250: 126325, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32234625

RESUMO

Atmospheric carbon dioxide (CO2) imbalance due to anthropogenic emissions has direct impact in climate change. Recent advancements in the mitigation of industrial CO2 emissions have been brought about by a paradigm shift from mere CO2 capture onto various adsorbents to CO2 conversion into high value products. The present study proposes a system which involves the conversion of CO2 into high purity, low moisture, compact and large CaCO3 solids through homogeneous granulation in a fluidized-bed reactor (FBR). In the present study, synthetic solutions of potassium carbonate (K2CO3) and calcium hydroxide (Ca(OH)2) were used as sources of carbonate and precipitant, respectively. The effects of the degree of supersaturation (S) as chemical loading and influx flow rate (QT) as hydraulic loading on CaCO3 granulation efficiency were investigated. In the study, S was varied from 10.2 to 10.8 and QT from 40 to 80 mL min-1 while the operating pH and calcium-is-to-carbonate molar ratio ([Ca2+]/[CO32-]) were set at 10 ± 0.2 and 1.50, respectively. Results showed that carbonate ions end product distribution had a highest carbonate granulation efficiency at [Carbonate]G of 95-96% using S of 10.6 and QT of 60 mL min-1. Characterization of the granules confirmed high purity calcium carbonate. Overall, the transformation of industrial CO2 emissions into a valuable solid product can be a significant move towards the mitigation of climate change from anthropogenic emissions.


Assuntos
Carbonato de Cálcio/química , Dióxido de Carbono/química , Sequestro de Carbono , Carbonatos , Fenômenos Físicos , Potássio
9.
Chemosphere ; 254: 126795, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32334253

RESUMO

In this work, the use in fuel cell mode of three electro-absorbers is evaluated for the chloralkaline process and performance is compared with that of a conventional PEMFC operated at the same operation conditions (room temperature). To do this, four cells have been in-house manufactured and compared, in order to determine which electrolyte (solution containing the active species or the membrane) is the best and which is the influence of the absorption stage on the operation of the cell. Because of the high solubility of chlorine, only the hydrogen absorption has been considered in order to evaluate relevant differences in the performance. Results demonstrate that design of the cell has a superb significance on the performances obtained. Cells with membrane-electrode assemblies are more efficient than those in which the membrane is used only as an electrodic compartment separator and utilization of devices which produce tiny bubbles of gas into the electrolyte is also very advantageous in order to obtain higher efficiencies. Results are of a great significance for the design of electro-absorbers and this paper is a first approach to face the design of reversible electrochemical cells for the chloralkaline process.


Assuntos
Fontes de Energia Elétrica , Eletrodos , Eletrólitos , Hidrogênio , Fenômenos Físicos
10.
Proc Natl Acad Sci U S A ; 117(19): 10585-10592, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32341168

RESUMO

The anterior body of many fishes is shaped like an airfoil turned on its side. With an oscillating angle to the swimming direction, such an airfoil experiences negative pressure due to both its shape and pitching movements. This negative pressure acts as thrust forces on the anterior body. Here, we apply a high-resolution, pressure-based approach to describe how two fishes, bluegill sunfish (Lepomis macrochirus Rafinesque) and brook trout (Salvelinus fontinalis Mitchill), swimming in the carangiform mode, the most common fish swimming mode, generate thrust on their anterior bodies using leading-edge suction mechanics, much like an airfoil. These mechanics contrast with those previously reported in lampreys-anguilliform swimmers-which produce thrust with negative pressure but do so through undulatory mechanics. The thrust produced on the anterior bodies of these carangiform swimmers through negative pressure comprises 28% of the total thrust produced over the body and caudal fin, substantially decreasing the net drag on the anterior body. On the posterior region, subtle differences in body shape and kinematics allow trout to produce more thrust than bluegill, suggesting that they may swim more effectively. Despite the large phylogenetic distance between these species, and differences near the tail, the pressure profiles around the anterior body are similar. We suggest that such airfoil-like mechanics are highly efficient, because they require very little movement and therefore relatively little active muscular energy, and may be used by a wide range of fishes since many species have appropriately shaped bodies.


Assuntos
Fenômenos Biomecânicos/fisiologia , Peixes/fisiologia , Natação/fisiologia , Animais , Peixes/anatomia & histologia , Movimento , Perciformes/fisiologia , Fenômenos Físicos , Truta/fisiologia
11.
PLoS One ; 15(4): e0232136, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32330188

RESUMO

Determining the East-West position was a classical problem in human sea navigation until accurate clocks were manufactured and sailors were able to measure the difference between local time and a fixed reference to determine longitude. Experienced night-migratory songbirds can correct for East-West physical and virtual magnetic displacements to unknown locations. Migratory birds do not appear to possess a time-different clock sense; therefore, they must solve the longitude problem in a different way. We showed earlier that experienced adult (but not juvenile) Eurasian reed warblers (Acrocephalus scirpaceus) can use magnetic declination (the difference in direction between geographic and magnetic North) to solve this problem when they were virtually displaced from Rybachy on the eastern Baltic coast to Scotland. In this study, we aimed to test how general this effect was. Adult and juvenile European robins (Erithacus rubecula) and adult garden warblers (Sylvia borin) under the same experimental conditions did not respond to this virtual magnetic displacement, suggesting significant variation in how navigational maps are organised in different songbird migrants.


Assuntos
Migração Animal/fisiologia , Aves Canoras/fisiologia , Navegação Espacial/fisiologia , Animais , Campos Magnéticos , Magnetismo , Orientação , Passeriformes/fisiologia , Fenômenos Físicos , Escócia
12.
Nature ; 580(7801): 37-38, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32238936
13.
Nature ; 580(7803): 323-324, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32296186
14.
Nature ; 580(7803): 305, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32296194
15.
Environ Monit Assess ; 192(5): 289, 2020 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-32297020

RESUMO

River discharge is one of the important hydraulic data to evaluate and manage the regional water resources. Estimating river discharge is generally based on field measurements. The measurement data are then applied to construct water level-discharge rating curves. However, it is sometimes difficult to obtain accurate discharge data due to the high uncertainty of flow. A commonly used technique is the propeller-type flowmeters (PTF), which average the results of 1-, 2-, or 3-point methods to obtain a vertical mean velocity. In this study, three types of flowmeters were employed to compare the accuracy of flow measured. The devices were calibrated using a tow tank testing: PTF, acoustic Doppler profiler (ADP), and radar surface velocimeter (RSV). To assess the applicability of the non-contact observation method, a series of 16 experiments in channels were conducted. Surface velocity measurement using the RSV was compared with the measurements obtained by PTF. The relationship between measured surface velocity of RSV and measured vertical mean velocity of PTF was established. The results show that the RSV can effectively estimate the river discharge in the open channel flow.


Assuntos
Monitoramento Ambiental , Rios , Acústica , Fenômenos Físicos , Água , Movimentos da Água
16.
PLoS One ; 15(3): e0229532, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32191717

RESUMO

In this study, research on a pile group system was conducted using shaking table tests under four working conditions: a natural foundation and pile-spacing conditions of 3D, 3.5D, and 4D (D is the diameter of the pile). The time histories of the excess pore pressure ratio and settlement were analyzed. It was determined that pile foundations improved the anti-liquefaction performance of the soil, and the effect was much greater when the pile spacing was 3D. In addition, the settlement dynamic amplification factor (SDAF) was proposed and calculated at different vibration times. The result was fitted with a linear relationship, and the correlation coefficient was relatively high. During the aseismic design of the pile foundation bearing capacity, the SDAF was multiplied by the static load, and the results showed that in the dynamic design of the pile foundation, the dynamic problem can be transformed into a static analysis, which can provide a reference for the design of the vertical bearing capacity of pile foundations under seismic force.


Assuntos
Areia/química , Colapso Estrutural/prevenção & controle , Vibração/efeitos adversos , Terremotos , Fenômenos Mecânicos , Modelos Teóricos , Fenômenos Físicos , Solo/química , Estresse Mecânico
18.
Waste Manag ; 105: 550-559, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32146416

RESUMO

In the South-Tyrol region (Italy), 46 gasifiers are currently operating and €200,000 are annually paid to dispose of as a waste 1300 tons of char. Therefore, there is a considerable interest in finding alternatives for the valorization of this solid by-product. The aim of this work is to assess the potential of char as energy source and to compare two scenarios. The first scenario considers the possibility of exploiting char in a dedicated burner integrated in the gasification plant. The second scenario assumes that all the char is collected from South-Tyrol and co-fired with biomass in an existing combustion-ORC plant. An economic analysis was performed evaluating the discounted payback time and both scenarios were modeled using Aspen Plus®. The results reveal that substantial savings in the operating costs of the plants can be achieved. In the first scenario the owners of the gasification plants could save from 50% to 94% of the char disposal costs with a payback time ranging between 3 and 7 years. In the second scenario, the owner of the plant could save approximately €235 k per year with a payback time of approximately 7 years. The present study provides a basis for further techno-economic studies on char combustion. The results can be helpful for the owners of the gasification plants in determining the most cost-effective way to dispose char and to avoid disposing it of as a waste. Furthermore, it is demonstrated how char could be used as a renewable fuel, with better performance than raw biomass.


Assuntos
Fontes Geradoras de Energia , Biomassa , Análise Custo-Benefício , Itália , Fenômenos Físicos
20.
Chemosphere ; 249: 126160, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32065996

RESUMO

Graphene oxide (GO) is widely used in different applications, however once released into the environment it can change its structure and affect the transport of important contaminants such as arsenic. In this work we show that UV radiation, even in the range of 28-74 µW/cm2 of irradiance up to 120 h of exposure, can induce important changes in the structure of graphene oxide, by eliminating -OH and CO functional groups. This reduction affected the stability of graphene oxide in water by decreasing its zeta potential from -41 to -37 mV at pH=7 with the increase of the exposure time. Our results showed that after 24 and 120 h of UV exposure, As(III) adsorption capacity decreased from 5 mg/g to 4.7 and 3.8 mg/g, respectively, suggesting a lower capacity to transport contaminants with time. Computer modelling showed that even a degraded GO structure can have an interaction energy of 223.84 kJ/mol with H3AsO3. Furthermore, we observed that the cytotoxicity of graphene oxide changed after being irradiated at 74 µW/cm2 for 120 h, showing 20% more cell viability compared to as-produced GO. Our results stress the importance of considering the microstructural and compositional changes that GO undergoes even under low irradiance and short periods, when studying its fate and behavior in the environment and possible applications in water treatment.


Assuntos
Arsênico/toxicidade , Grafite/química , Raios Ultravioleta , Poluentes Químicos da Água/toxicidade , Adsorção , Arsênico/química , Modelos Químicos , Óxidos/química , Fenômenos Físicos , Água , Poluentes Químicos da Água/química , Purificação da Água
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