| 1. |
- An, Wei, et al.
(författare)
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Mechanistic Study of CO Titration on CuxO/Cu(111) (x <= 2) Surfaces
- 2014
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Ingår i: ChemCatChem. - : Wiley-VCH Verlagsgesellschaft. - 1867-3880 .- 1867-3899. ; 6:8, s. 2364-2372
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Tidskriftsartikel (refereegranskat)abstract
- The reducibility of metal oxides is of great importance to their catalytic behavior. Herein, we combined ambient-pressure scanning tunneling microscopy (AP-STM), X-ray photoemission spectroscopy (AP-XPS), and DFT calculations to study the CO titration of CuxO thin films supported on Cu(111) (CuxO/Cu(111)) aiming to gain a better understanding of the roles that the Cu(111) support and surface defects play in tuning catalytic performances. Different conformations have been observed during the reduction, namely, the 44 structure and a recently identified (5-7-7-5) Stone-Wales defects (5-7 structure). The DFT calculations revealed that the Cu(111) support is important to the reducibility of supported CuxO thin films. Compared with the case for the Cu2O(111) bulk surface, at the initial stage CO titration is less favorable on both the 44 and 5-7 structures. The strong CuxO <-> Cu interaction accompanied with the charge transfer from Cu to CuxO is able to stabilize the oxide film and hinder the removal of O. However, with the formation of more oxygen vacancies, the binding between CuxO and Cu(111) is weakened and the oxide film is destabilized, and Cu2O(111) is likely to become the most stable system under the reaction conditions. In addition, the surface defects also play an essential role. With the proceeding of the CO titration reaction, the 5-7 structure displays the highest activity among all three systems. Stone-Wales defects on the surface of the 5-7 structure exhibit a large difference from the 44 structure and Cu2O(111) in CO binding energy, stability of lattice oxygen, and, therefore, the reduction activity. The DFT results agree well with the experimental measurements, demonstrating that by adopting the unique conformation, the 5-7 structure is the active phase of CuxO, which is able to facilitate the redox reaction and the Cu2O/Cu(111)<-> Cu transition.
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| 2. |
- Guo, Jing, et al.
(författare)
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Pulmonary toxicity and adjuvant effect of di-(2-exylhexyl) phthalate in ovalbumin-immunized BALB/c mice
- 2012
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Ingår i: PLOS ONE. - : PLOS. - 1932-6203. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Asthma is a complex pulmonary inflammatory disease, which is characterized by airway hyperresponsiveness, variable airflow obstruction and inflammation in the airways. The majority of asthma is allergic asthma, which is a disease caused by type I hypersensitivity mediated by IgE. Exposures to a number of environmental chemicals are suspected to lead to asthma, one such pollutant is di-(2-ethylheyl) phthalate (DEHP). DEHP is a manufactured chemical that is commonly added in plastic products to make them flexible. Epidemiological studies have revealed a positive association between DEHP exposure and asthma prevalence.METHODOLOGY/PRINCIPAL FINDINGS: The present study was aimed to determine the underlying role of DEHP exposure in airway reactivity, especially when combined with allergen exposure. The biomarkers include pulmonary histopathology, airway hyperresponsiveness (lung function), IgE, IL-4, IFN-γ and eosinophils. Healthy balb/c mice were randomly divided into eight exposure groups (n = 8 each): (1) saline control, (2) 30 µg/(kg•d) DEHP, (3) 300 µg/(kg•d) DEHP, (4) 3000 µg/(kg•d) DEHP, and (5) ovalbumin (OVA)-sensitized group, (6) OVA-combined with 30 µg/(kg•d) DEHP, (7) OVA-combined with 300 µg/(kg•d) DEHP, and (8) OVA-combined with 3000 µg/(kg•d) DEHP. Experimental tests were conducted after 52-day DEHP exposure and subsequently one week of challenge with aerosolized OVA. The principal findings include: (1) Strong postive associations exist between OVA-combined DEHP exposure and serum total IgE (T-IgE), as well as histological findings. These positive associations show a dose-dependent low dose sensitive effect of DEHP. (2) IL-4, eosinophil recruitment and lung function are also indicators for adjuvant effect of DEHP.CONCLUSIONS/SIGNIFICANCE: Our results suggest that except the significant changes of immunological and inflammatory biomarkers (T-IgE, IL-4, IFN-γ and eosinophils), the pulmonary histological (histopathological examination) and physiological (lung function) data also support that DEHP may promote and aggravate allergic asthma by adjuvant effect.
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| 3. |
- Tang, Jiaqi, et al.
(författare)
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Neurobehavioral changes induced by di(2-ethylhexyl) phthalate and the protective effects of vitamin E in Kunming mice
- 2015
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Ingår i: Toxicology Research. - : Royal Society of Chemistry. - 2045-452X .- 2045-4538. ; 4:4, s. 1006-1015
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Tidskriftsartikel (refereegranskat)abstract
- Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer commonly used in PVC that may leach into the environment, and has been shown to adversely affect the health of humans and animals. We undertook a study to ascertain the neurotoxicity of DEHP in Kunming mice. This study included three rounds of testing. In the first round, Kunming mice were exposed to different concentrations of DEHP (0, 5, 50, 500 mg kg(-1) per day) after which their cognitive ability was assessed using the Morris water maze (MWM) test. The reactive oxygen species (ROS) content in tissue and the malondialdehyde (MDA) content of brains were also measured. In the second round, vitamin E (50 mg kg(-1) per day) was given daily as an anti-oxidant via the intragastric route. Cognitive deficits and locomotor activity, as well as ROS and MDA contents were tested employing the same methods. In the third round, the depressive mood of mice after DEHP exposure (500 mg kg(-1) per day) was measured using the open field test, the tail suspension test, and the forced swim test. The main findings of this study include: (1) a statistical association exists between DEHP oral exposure and spatial learning (DEHP 500 mg kg(-1) per day) and memory (DEHP 50 mg kg(-1) per day) dysfunction as ascertained by an MWM test of Kunming mice. (2) A statistical association was also found between DEHP oral exposure (50 and 500 mg kg(-1) per day) and oxidative stress (ROS and MDA) of mouse brain tissue. (3) Co-administration of vitamin E (50 mg kg(-1) per day) diminishes the elevation of ROS and MDA induced by DEHP (50 mg kg(-1) per day) from significant levels to non-significant levels. (4) Co-administration of vitamin E (50 mg kg(-1) per day) protects against mouse memory dysfunction induced by DEHP (50 mg kg(-1) per day) from being significant to being not significant. (5) In the 5 mg kg(-1) per day DEHP exposure groups, oxidative stress in brain tissue, and neurobehavioral changes were not found. (6) High dose DEHP exposure (500 mg kg(-1) per day) may induce behavioral despair in mice. Conclusions: These data suggest that DEHP is neurotoxic with regard to cognitive ability and locomotor activity.
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| 4. |
- Zhang, Yinping, et al.
(författare)
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Ten cities cross-sectional questionnaire survey of children asthma and other allergies in China
- 2013
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Ingår i: Chinese Science Bulletin. - : Springer Science and Business Media LLC. - 1001-6538 .- 1861-9541. ; 58:34, s. 4182-4189
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Tidskriftsartikel (refereegranskat)abstract
- Asthma, rhinitis and eczema (allergic or non-allergic) have increased throughout the world during the last decades, especially among children. Changes in the indoor environment are suspected to be important causes. China has experienced a dramatic change in indoor environmental exposures during the past two decades. However, such changes and their associations with children's asthma and other health aspects have not been thoroughly studied. China, Children, Homes, Health (CCHH), Phase I, was a cross-sectional questionnaire survey of 48219 children 1-8 years old in 10 Chinese cities during 2010-2012. The questionnaire includes the International Study of Asthma and Allergies in Childhood (ISAAC) core health questions and additional questions regarding housing, life habits and outdoor environment. In health analyses, children aged 3-6 years old were included. The prevalences of doctor diagnosed asthma varied from 1.7% to 9.8% (mean 6.8%), a large increase from 0.91% in 1999 and 1.50% in 2000. The prevalence of wheeze, rhinitis and atopic eczema (last 12 months) varied from 13.9% to 23.7%, 24.0% to 50.8% and 4.8% to 15.8%, respectively. Taiyuan had the lowest prevalences of all illnesses and Shanghai the highest, except for wheezewhere the highest value was for Urumqi. We found (1) no obvious association between disease prevalences and ambient PM10 concentrations and (2) higher prevalences of disease in humid climates with hot summers and cold winters, but with no centrally heated buildings. Associations between the diseases and economic status as indexed by Gross Domestic Product (GDP) requires further study.
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