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1.
Sci Total Environ ; 926: 171846, 2024 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-38513867

RESUMO

Chlorinated paraffins (CPs) are industrial chemicals that have potential adverse effects in the environment and on human health. This study investigated CPs in apiary environment, honeybees, and bee products from two rural areas of Beijing, China. The median concentrations of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) were 22 and 1.6 ng/m3 in the ambient air, 1350 and 708 ng/g dry mass (dw) in bees, 1050 and 427 ng/g dw in flowers, 37 and 54 ng/g in honey, 78 and 53 ng/g dw in bee pollen, 36 and 30 ng/g dw in soil, and 293 and 319 ng/g dw in bee wax. C10Cl6-7 and C14Cl7-8 dominated SCCPs and MCCPs in these samples, respectively. The concentrations and distributions of CPs in samples from apiaries located in the two regions varied. Long-range transportation of air masses was identified as an important source of CPs in apiaries. A close relationship between CPs in bees and the apiary environment indicated that bees could act as bioindicators for CP contamination in the environment. A human health risk assessment found that there were low risks for adults and children exposed to CPs through consumption of honey and pollen from the studied regions.


Assuntos
Hidrocarbonetos Clorados , Parafina , Criança , Abelhas , Humanos , Animais , Parafina/análise , Monitoramento Ambiental , Hidrocarbonetos Clorados/análise , China , Pequim
2.
Environ Res ; 252(Pt 1): 118768, 2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38521355

RESUMO

Chlorinated paraffins (CPs) are hazardous to humans, and dietary intake acts as the primary pathway for human exposure to CPs. Takeout food is popular worldwide, but the presence of CPs in takeout food and its packaging is unclear. In this study, the concentrations and distributions of short- and median-chain CPs (SCCPs and MCCPs, respectively) were measured in 97 samples of four categories of takeout food and 33 samples of three types of takeout packaging. The SCCP and MCCP median concentrations for the takeout food samples were 248 and 339, 77.2 and 98.2, 118 and 258, 42.9 and 64.4 ng/g wet weight in meat, starch, half meat/half starch, and vegetables, respectively. Takeout food contained higher concentrations of SCCPs than MCCPs. The dominant SCCP and MCCP congener groups in takeout food were C10Cl6-7 and C14Cl7-8, respectively. The CP concentrations in takeout food were lower than those in packaging. The SCCP and MCCP median concentrations, respectively, in packaging were 9750 and 245 ng/g in polypropylene, 2830 and 135 ng/g in paper, and 2060 and 119 ng/g in aluminum foil. The concentrations of SCCPs and MCCPs were comparable in aluminum foil, whereas the concentrations of SCCPs were higher than those of MCCPs in polypropylene and paper. Correlations between CP concentrations in the takeout food and packaging indicated that CPs in packaging were potentially an important source of CPs in the takeout food. A dietary exposure risk assessment showed the takeout food posed a low risk for human exposure to CPs; however, high-frequency consumption may pose a health risk. This study clarified the current contamination situation in takeout food in Beijing, China. The resulting data could be used to prevent human exposure to CPs through dietary intake and to facilitate the market's control over the quality of takeout food.

3.
Sci Total Environ ; 917: 170605, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38307290

RESUMO

Fish are an important source of human dietary exposure to polychlorinated naphthalenes (PCNs). The occurrence and sources of PCNs in different species of freshwater fish are unknown, and few studies have assessed human exposure risks to PCNs through freshwater fish. In this study, 140 freshwater fish samples from 10 species were collected from Beijing markets, China. The Σ75CNs concentration range in the fish was 20.7-1310 pg/g wet weight (ww). The highest median Σ75PCNs concentration (80.4 pg/g ww) was found in mandarin fish (Siniperca chuatsi), and the lowest (29.6 pg/g ww) in snakehead (Channa argus). Di- and tri-CNs were the dominant PCN homologues with contributions of 35.3 % and 30.8 %, respectively. Unintentionally produced PCNs from metal smelting might be the source of PCN contamination in freshwater fish. The cooking temperature and time did not significantly affect the PCN concentrations in fish or the PCN homologue profiles. The highest toxic equivalent (TEQ) value was observed in sturgeon (Acipenser sinensis), followed by mandarin fish. Hexa-CNs were the most abundant homologue for the PCN TEQs. A risk assessment indicated that the dietary exposure risks for local residents to PCNs through freshwater fish were low. However, the relatively high concentrations of PCNs in the samples deserve attention to avoid PCNs exposure risks for groups with high fish consumption rates. Furthermore, freshwater fish likely contain a mixture of contaminants including dioxin and furans which also display a similar mode of toxicity as the PCNs and could enhance the risk to fish consumers.


Assuntos
Naftalenos , Dibenzodioxinas Policloradas , Animais , Humanos , Pequim , Naftalenos/análise , Dibenzodioxinas Policloradas/análise , Água Doce , Medição de Risco , Monitoramento Ambiental
4.
Environ Res ; 246: 118109, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38185221

RESUMO

Chlorinated paraffins (CPs) in poultry feed and the farm environment might bioaccumulate in poultry eggs. Unlike chickens, which are mostly raised in cages, ducks are commonly raised free range. This would expose ducks to CPs in the environment. However, information on the presence of CPs on duck farms is scarce. In the present study, samples of duck eggs, duck feathers, poultry feed, and soil were collected from 25 duck farms in South China. Forty-eight congener groups of short- and medium-chain CPs (SCCPs and MCCPs) were detected in the samples. Interestingly, relatively high concentrations of SCCPs and MCCPs were found in the duck feathers. The median concentrations of SCCPs and MCCPs in the duck eggs, feathers, feed and soil were: 46 and 18 ng/g wet weight, 2460 and 992 ng/g, 103 and 47 ng/g, and 24 and 10 ng/g dry weight, respectively. The dominant groups of SCCPs and MCCPs were C10Cl6-7 and C14Cl7-8, respectively. The close relationship between duck feathers and poultry feed indicated that the duck feathers might act as a bioindicator for the exposure of ducks to CPs. The margin of exposure approach was used to assess the health risk, with the results showing that the consumption of duck eggs posed a low risk to different age groups from exposure to SCCPs and MCCPs.


Assuntos
Patos , Hidrocarbonetos Clorados , Animais , Parafina/análise , Fazendas , Exposição Dietética , Monitoramento Ambiental/métodos , Hidrocarbonetos Clorados/análise , Galinhas , China , Solo
5.
Sci Rep ; 13(1): 5009, 2023 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-36973537

RESUMO

In this work, we proposed a method of extracting feature parameters for deep neural network prediction based on the vectorgraph storage format, which can be applied to the design of electromagnetic metamaterials with sandwich structures. Compared to current methods of manually extracting feature parameters, this method can automatically and precisely extract the feature parameters of arbitrary two-dimensional surface patterns of the sandwich structure. The position and size of surface patterns can be freely defined, and the surface patterns can be easily scaled, rotated, translated, or transformed in other ways. Compared to the pixel graph feature extraction method, this method can adapt to very complex surface pattern design in a more efficient way. And the response band can be easily shifted by scaling the designed surface pattern. To illustrate and verify the method, a 7-layer deep neural network was built to design a metamaterial broadband polarization converter. Prototype samples were fabricated and tested to verify the accuracy of the prediction results. In general, the method is potentially applicable to the design of different kinds of sandwich-structure metamaterials, with different functions and in different frequency bands.

6.
Oncol Lett ; 25(3): 119, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36844629

RESUMO

Acquired resistance to Taxol (TAX) contributes to clinical treatment failure and significantly reduces the survival rate of patients. The present study aimed to explore the effects of exosomal microRNA (miR)-187-5p on TAX resistance in breast cancer cells and its underlying mechanisms. Exosomes were isolated from MCF-7 and TAX-resistant MCF-7/TAX cells, and the miR-187-5p and miR-106a-3p levels of the cells and exosomes were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Next, MCF-7 cells were treated with TAX for 48 h and either treated with exosomes or transfected with miR-187-5p mimics. Cell viability, apoptosis, migration, invasion and colony formation were determined using Cell Counting Kit-8, flow cytometry, Transwell and colony formation assays, and the expression levels of associated genes and proteins were detected by RT-qPCR and western blotting, respectively. Finally, a dual-luciferase reporter gene assay was performed to confirm the target of miR-187-5p. The results showed that miR-187-5p expression levels increased significantly in TAX-resistant MCF-7 cells and exosomes compared with normal MCF-7 cells and exosomes (P<0.05). However, miR-106a-3p was not detected in the cells or exosomes. Therefore, miR-187-5p was selected for subsequent experiments. A series of cell assays showed that TAX inhibited the viability, migration, invasion and colony formation of MCF-7 cells and promoted their apoptosis; however, these changes were reversed by resistant cell exosomes and miR-187-5p mimics. Additionally, TAX significantly upregulated ABCD2 and downregulated ß-catenin, c-Myc and cyclin D1, whereas resistant exosomes and miR-187-5p mimics reversed the TAX-induced changes in expression. Finally, ABCD2 was confirmed to directly bind with miR-187-5p. It may be concluded that TAX-resistant cell-derived exosomes delivering miR-187-5p may affect the growth of TAX-induced breast cancer cells by targeting ABCD2 and c-Myc/Wnt/ß-catenin signaling.

7.
BMC Microbiol ; 22(1): 286, 2022 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-36447140

RESUMO

BACKGROUND: Pulmonary tuberculosis is a chronic infectious disease of the respiratory system. It is still one of the leading causes of death from a single infectious disease, but it has been stuck in the study of a single pathogen. Recent studies have shown that many diseases are associated with disruption of the native microbiota. In this study we investigated the occurrence of tuberculosis and the correlation between drug resistance and respiratory flora. High-throughput 16 S rRNA gene sequencing was used to characterize the respiratory microbiota composition of 30 tuberculosis (TB) affected patients and compared with 30 healthy (H) controls. According to their Gene Xpert results, 30 pulmonary tuberculosis patients were divided into 12 persons in the drug-sensitive group (DS0) and 18 persons in the drug-resistant group (DR0). The microbial flora of the two were compared with the H group. RESULTS: The data generated by sequencing showed that Firmicutes, Proteus, Bacteroides, Actinomyces and Fusobacterium were the five main bacterial phyla detected, and they constituted more than 96% of the microbial community. The relative abundances of Fusobacterium, Haemophilus, Porphyromonas, Neisseria, TM7, Spirochetes, SR1, and Tenericutes in the TB group was lower than that of the H group, and Granulicatella was higher than the H group. The PcoA diagrams of the two groups had obvious clustering differences. The Alpha diversity of the TB group was lower than that of the H group, and the Beta diversity was higher than that of the H group (P < 0.05). The relative abundance of Streptococcus in the DS0 group was significantly higher than that in the DR0 group (P < 0.05). CONCLUSION: Pulmonary tuberculosis can cause disorders of the respiratory tract microbial flora, in which the relative abundance of Streptococcus was significantly different between rifampicin-sensitive and rifampicin-resistant patients.


Assuntos
Microbiota , Tuberculose Pulmonar , Humanos , Rifampina/farmacologia , Tuberculose Pulmonar/tratamento farmacológico , Sistema Respiratório , Fusobacterium
8.
Vet Microbiol ; 275: 109593, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36323175

RESUMO

Porcine sapelovirus (PSV) is an important emerging swine pathogen that causes diarrhoea, respiratory distress, severe reproductive system and neurological disorders in pigs, posing huge threat to swine industry. However, there are no effective serological diagnostic products and the epitope characterization of PSV VP1 protein is still largely unknown. In current study, we successfully expressed recombinant His-VP1 protein by prokaryotic expression system and the recombinant VP1 protein had good immunogenicity. BALB/C mice were then selected and immunized with purified recombinant VP1 protein, and two monoclonal antibodies (Mabs) 9F10 and 15E4 against VP1 were successfully prepared by hybrioma technology. The isotype of these two Mabs were identified and showed that Mab 9F10 with the heavy chain subtype was IgG1 and the light chain subtype was kappa. Mab 15E4 was identified as IgG2 for the heavy chain subtype and Kappa for the light chain subtype. The antigen epitopes of prepared two VP1 Mabs were clearly identified. The minimal unit of B cell specific epitope recognized by Mab 15E4 was 203YDGDG207 and conserved in different strain genotypes of PSV, indicating this epitope may be a good target for serological detection of PSV. However, the epitope recognized by Mab 9F10 was 8QAIVNRT14 and varied greatly among different PSV strains. Structural modeling analysis showed that the identified two novel B cell epitopes were located on the surface of VP1. Our study provides useful tool for the establishment the serological detection methods of PSV and may support the study of VP1 protein function.


Assuntos
Anticorpos Monoclonais , Anticorpos Antivirais , Epitopos de Linfócito B , Picornaviridae , Proteínas Virais , Animais , Camundongos , Anticorpos Monoclonais/biossíntese , Anticorpos Monoclonais/imunologia , Anticorpos Antivirais/biossíntese , Anticorpos Antivirais/imunologia , Epitopos de Linfócito B/imunologia , Imunoglobulina G , Camundongos Endogâmicos BALB C , Picornaviridae/imunologia , Suínos , Proteínas Virais/imunologia
9.
Sci Total Environ ; 847: 157587, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-35882323

RESUMO

Polychlorinated naphthalenes (PCNs) were added to the Stockholm Convention list of persistent organic pollutants in 2015. PCNs are mainly unintentionally produced during industrial processes nowadays, and can be widely found in environmental media and foodstuffs. Dietary intake is the primary pathway for human exposure to PCNs. PCNs in different categories of foodstuffs have been reported. However, little information on PCN concentrations in green tea, a popular beverage worldwide is available. In this study, all 75 PCN congener concentrations and distributions in green tea samples (n = 102) from 11 regions in China were determined, and risk assessment of human exposure to PCNs through tea consumption was conducted. The PCN concentrations in all the green tea samples were 3.62-175 pg/g dry weight (mean 36.1 pg/g dry weight). Similar PCN homolog and congener profiles were found in green tea samples from different areas. The dominant PCN homologs in all of the green tea samples were di-CNs, tetra-CNs, and tri-CNs. No direct relationships were found between PCN emission sources and PCN concentrations in the green tea samples. The brewing technique could affect the PCN concentrations and homolog profiles in tea leaves. PCNs in green tea from China were found to pose little risk to humans.


Assuntos
Monitoramento Ambiental , Naftalenos , Humanos , China , Naftalenos/análise , Poluentes Orgânicos Persistentes , Medição de Risco , Chá
10.
Chemosphere ; 307(Pt 1): 135674, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35835238

RESUMO

Porewater is the primary carrier of sediment nitrogen and a crucial source of overlying water nitrogen; its separation thus is essential for restraining nitrogen release from sediment to overlying water. We developed a novel device using electrokinetic geosynthetics to drain porewater with nitrogen and restrain nitrogen release. A batch experiment lasted 1120 h (about 47 days) was conducted with 20 cm depth of overlying water under three conditions, i.e., undrained at 0 V/cm voltage gradient (control), drained at 0 V/cm, and drained at 0.5 V/cm. Under the pulsed direct current, once porewater drained, overlying water replenished sediment pore space and supplied porewater. Along with porewater drainage, sediment nitrogen concentration was reduced by 11%-30%, decreasing nitrogen release from sediment to overlying water from 83 mg/m2 in the first 100 h to -95 mg/m2 after about 600 h. Processes such as electroosmosis, electromigration, and redox reaction contributed to the restraint on nitrogen release. This research revealed the potentiality of applying electrokinetic geosynthetics to in-situ restraint on sediment nitrogen release in eutrophic waterbodies such as fishponds.


Assuntos
Nitrogênio , Poluentes Químicos da Água , Sedimentos Geológicos , Nitrogênio/análise , Fósforo , Água , Poluentes Químicos da Água/análise
11.
Environ Sci Pollut Res Int ; 29(26): 40110-40122, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35112261

RESUMO

In recent years, China had released various environmental regulations in order to respond climate change and corresponding environmental issues. However, due to imbalanced economic development and industrial structure, different Chinese regions had different enforcement levels on environmental regulations, which led to the regional transfer of pollution-intensive industries. To study the regional disparities on carbon emission transfer, this paper used the propensity score matching-difference in differences method (hereinafter abbreviated as "PSM-DID") to evaluate the mechanism between carbon trading pilot policies and the transfer of pollution-intensive industries. Panel data on 30 Chinese provinces were used to test the validity of the "pollution haven hypothesis," covering the period of 2010-2018. The empirical results showed that under the constraints of established environmental regulation, the pilot policy promoted the transfer of pollution-intensive industries to a certain extent and verified the "pollution haven hypothesis"; the proportion of the secondary sector and energy industry in the pilot areas had been reduced after the pilot policy; on the contrary, the technical level and the economic development level of the pilot provinces and cities had been further improved.


Assuntos
Carbono , Gases de Efeito Estufa , Carbono/análise , Dióxido de Carbono/análise , China , Desenvolvimento Econômico , Indústrias
12.
J Hazard Mater ; 427: 128192, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-35007805

RESUMO

Chlorinated paraffins (CPs) have been found to occur ubiquitously in foodstuff of both animal and plant origin. However, limited information is available on the content of CPs in green tea, one of the most commonly consumed beverages worldwide. Herein, 107 commercial green tea samples originating from 11 provinces of China, were collected to study the occurrence of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively). The concentration of SCCPs in all green tea samples ranged from 4.99 to 717 ng/g (mean: 55.7 ng/g), while MCCPs ranged from 2.55 to 543 ng/g (mean: 33.5 ng/g). CP profiles in green tea samples from different provinces exhibited no regional differences. To identify the potential sources of CPs in green tea, 19 tea packaging samples were collected and analyzed, showing that SCCPs and MCCPs existed at much higher concentrations in the tea packaging material than in the teas. Migration tests indicated that CPs could migrate from packaging into teas during storage, with the migration velocity and efficiency of SCCPs being higher than MCCPs.


Assuntos
Hidrocarbonetos Clorados , Parafina , Animais , China , Monitoramento Ambiental , Hidrocarbonetos Clorados/análise , Parafina/análise , Chá
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 265: 120358, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34509892

RESUMO

In this study, a novel FONs-based sensor P-M(w) was synthesized using 1-Pyrenecarboxaldehyde and L-methionine through facile hydrothermal strategy. The fluorescence emission peaks of the acquired P-M(w) would show specific changes after the addition of Hg2+ due to interfering the PET process and inducing nano-structure conformational rigidification of P-M(w). Notably, the water-soluble FONs-based sensor was firstly used to detect Hg2+ in tea samples providing a new material choice for the fluorescence sensor construction of metal ion detection. Besides, the qualitative and quantitative analysis of Hg2+ could be carried out with P-M (w) at a very low concentration (1 µg/mL) meaning that the acquired P-M(w) synthesized by few grams of reactants may satisfy the detection of approximate fifty thousand samples.


Assuntos
Mercúrio , Nanopartículas , Corantes Fluorescentes , Mercúrio/análise , Espectrometria de Fluorescência , Chá , Água
14.
J Hazard Mater ; 411: 125111, 2021 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-33485223

RESUMO

Urea is one of the most important nitrogenous organic pollutants in water, and its removal attracts attention because of a growing concern related to water eutrophication. Urea has previously been considered to be largely unaffected by the UV-chlorine process. However, N-chlorourea, an intermediate of urea chlorination, has been shown to absorb ultraviolet radiation, and as such its photolysis is possible. Experiments were conducted to quantify the kinetics of N-chlorourea degradation under UV254 irradiation. The results showed that about 92% of N-chlorourea was degraded under UV254 irradiation. Ammonia and nitrate were detected as the primary nitrogen containing products of the photolysis of N-chlorourea. Solution pH ranging from 3.0 to 7.5 influenced the distribution of these products but not on the degradation rate. Based on these data, a possible pathway of photodegradation of N-chlorourea under UV254 is proposed. The degradation of urea was also achieved by the photolysis of N-chlorourea during the combined pre-chlorination and UV254 process. Insights gained in this study may be useful for exploring the potential of combined pre-chlorination and UV254 process on urea removal in water treatment.

15.
Environ Pollut ; 266(Pt 2): 115210, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32693325

RESUMO

Pore water is a crucial storage medium and a key source of sediment phosphorus. A novel equipment based on electrokinetic geosynthetics (EKGs) was used for isolating phosphorus from eutrophic lake sediments through pore water drainage. Three mutually independent indoor group experiments (A, B, and C) were conducted to investigate the effects of voltage gradient (0.00, 0.25, and 0.50 V/cm) on pore water drainage capacity, phosphorus removal performance, sediment physicochemical properties, and phosphorus storage dynamics. The average reduction in the sediment moisture and total phosphorus content was 2.5%, 4.3%, and 4.6% and 28.15, 75.95, and 112.65 mg/kg after 6 days of treatment for A, B and C, respectively. Efficient pore water drainage through gravity and electroosmotic flow and electromigration of phosphate were the main drivers of sediment-dissolved and mobilized phosphorus separation. A high voltage gradient facilitated the migration of pore water and the phosphorus in it. The maximal effluent total phosphorous (TP) concentration was up to 27.9 times that in the initial pore water samples, and negligible effluent TP was detected when the pore water pH was less than 2.5. The TP concentration was exponentially and linearly related to the pH and electronic conductivity of the electroosmotic flow, respectively. The migration of H+ within the sediment matrix promoted the liberation of metals bounded to phosphorus, particularly of Ca-P and Fe-P. Pore water drainage through an EKG resulted in Ex-P separation of up to 87.50% and a 13.84 mg/kg decrease in Ca-P and 125.35 mg/kg accumulation of low mobile Fe-P in the weak acid anode zone.


Assuntos
Fósforo/análise , Poluentes Químicos da Água/análise , China , Sedimentos Geológicos , Lagos , Água
16.
BMC Public Health ; 19(1): 1093, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31409316

RESUMO

BACKGROUND: Urban green open space is a valuable resource for physical activities of urban inhabitants and has the potential to reduce chronic illness and improve health. Research on the relationships between green open space and physical activity is incomplete and limited in China. Thus, the study examines how the urban green open space contributes to physical activity. METHODS: A questionnaire was designed based on the social ecology theory to investigate the physical activity of 513 residents in urban green open space. We use the time and frequency of residents exercising in urban green space to measure physical activity, and use the factor analysis to synthesize a large number of original factors (i.e., infrastructure, safety, accessibility, landscape quality, and space environment) into relatively few composite indicators. Based on the collected data of the cross-sectional population, the Order Probit regression model was constructed to analyze how urban green open space affects the residents' physical activity from the perspective of social ecology. RESULTS: ① in community factors: accessibility is significantly positive correlation with residents' physical activity, and there is no significant correlation between safety and physical activity; ②in natural factors: space environment and landscape quality are not significantly correlated with residents' physical activity; ③ in built environmental factors: infrastructures, the area of green space, the size of open space, and entertainment facilities are significantly correlated to residents' activity. Basketball courts, volleyball courts, swimming pools, and sports equipment will promote physical activity; ④ apart from the attributes of green open space, other factors are significantly correlated to physical activity in the green open space, e.g. having a companion. CONCLUSIONS: Urban green open space plays an important role in promoting physical activity especially among the women and the old, and improving the attributes (such as accessibility, infrastructures, the area of green space, the size of open space and entertainment facilities) of the urban green open space and trying to set up group sports proper to play with companion (like "square dancing" and "Tai Chi") can promote Chinese residents' physical activity so as to improve public health. The results are significant to facilitate environment health.


Assuntos
Planejamento Ambiental/estatística & dados numéricos , Exercício Físico , Parques Recreativos/estatística & dados numéricos , População Urbana/estatística & dados numéricos , Adulto , China , Estudos Transversais , Feminino , Humanos , Masculino , Meio Social , Teoria Social , Inquéritos e Questionários
17.
Nanoscale ; 9(38): 14467-14475, 2017 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-28926077

RESUMO

A bimetallic CoCu alloy thin-film catalyst is developed that enables the growth of uniform, high-quality graphene at 750 °C in 3 min by chemical vapour deposition. The growth outcome is found to vary significantly as the Cu concentration is varied, with ∼1 at% Cu added to Co yielding complete coverage single-layer graphene growth for the conditions used. The suppression of multilayer formation is attributable to Cu decoration of high reactivity sites on the Co surface which otherwise serve as preferential nucleation sites for multilayer graphene. X-ray photoemission spectroscopy shows that Co and Cu form an alloy at high temperatures, which has a drastically lower carbon solubility, as determined by using the calculated Co-Cu-C ternary phase diagram. Raman spectroscopy confirms the high quality (ID/IG < 0.05) and spatial uniformity of the single-layer graphene. The rational design of a bimetallic catalyst highlights the potential of catalyst alloying for producing two-dimensional materials with tailored properties.

18.
ACS Appl Mater Interfaces ; 9(22): 18410-18416, 2017 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-28452224

RESUMO

This paper presents a flexible graphene/polyvinylidene difluoride (PVDF)/graphene sandwich for three-dimensional touch interactivity. Here, x-y plane touch is sensed using graphene capacitive elements, while force sensing in the z-direction is by a piezoelectric PVDF/graphene sandwich. By employing different frequency bands for the capacitive- and force-induced electrical signals, the two stimuli are detected simultaneously, achieving three-dimensional touch sensing. Static force sensing and elimination of propagated stress are achieved by augmenting the transient piezo output with the capacitive touch, thus overcoming the intrinsic inability of the piezoelectric material in detecting nontransient force signals and avoiding force touch mis-registration by propagated stress.

19.
Nanoscale ; 8(36): 16427-16434, 2016 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-27722630

RESUMO

The domain boundaries of polycrystalline graphene produced by chemical vapor deposition (CVD) adversely influence the graphene transporting properties. The existing domain visualisation methods for large area graphene always cause detrimental damage or contamination. Here we report a nondestructive method for spatial visualisation of the domains and boundaries of large area continuous graphene grown on Cu foils (Gr/Cu) by CVD. Using a rationally modified optical microscope, we can directly observe novel star-like bright line sets of Gr/Cu in an enhanced dark field mode. Each set of the bright lines is identified as the ridges of one Cu surface pyramid which arises beneath one enlarging graphene domain due to slower evaporation of graphene-covered Cu than that of graphene-free Cu. This one to one correspondence thereby enables nondestructive visualisation. This method offers an advantageous pathway for monitoring the spatial distribution of the graphene domains and boundaries. We have further discovered for the first time various types of star-like ridge structures which are governed by the underlying Cu crystallographic orientations. This gives rise to a new phenomenon for research on the complex 2D material-metal interfacing.

20.
Electrophoresis ; 37(22): 2963-2969, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27494422

RESUMO

This paper aimed to build up a sensitive CE method for the analysis of tetracyclines (TCs) antibiotics (including tetracycline, chlorotetracycline, oxytetracycline, and doxycycline) with conventional UV detection. Here, the large volume sample stacking was applied to achieve in capillary preconcentration of the targets. To achieve large volume sample stacking, the essential step was a large volume of sample (around 83.3% of total capillary length from inlet to detection window) hydrodynamically loaded. Then, the reserved voltage was added in order to push the sample matrix out of the capillary. Due to different pH between sample solution (pH 4.6) and BGE (pH 11.0), the cationic TCs would turn into negatively charged while the sample matrix was removing from the capillary. Finally, the anionic TCs were stacked at the inlet for the subsequent separation. Although the loss of sample existed during their charge transformation, the LODs could be improved around 40 times than that obtained by normal hydrodynamic injection CE method. Here, the LODs were in the range of 8.1-14.5 µg/L, around 10 ppb that close to the level by electrochemiluminescence or laser-induced fluorescence detection of TCs by CE. The precision was characterized by RSDs of migration times and peak areas, which were in the range of 0.19-0.24% and 0.97-2.54%, respectively. The recoveries of the developed method were in the range of 95-112% by spiking TCs in the tap water. The proposed inline preconcentration CE method could be a simple, speed, and sensitive method for the quantitative analysis of TCs.


Assuntos
Eletroforese Capilar/métodos , Tetraciclinas/análise , Cátions , Concentração de Íons de Hidrogênio , Limite de Detecção , Reprodutibilidade dos Testes , Tetraciclinas/química , Tetraciclinas/isolamento & purificação , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
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