细化搜索
结果 3731-3740 的 6,535
Citizens’ preferences and attitudes towards urban waterfront spaces: a case study of Qiantang riverside development
2020
Wang, Yuan | Dewancker, Bart Julien | Qi, Qianlong
Many cities are facing various environmental problems, where performance-based planning and nature-based solutions have been proposed to address such problems. As a natural landscape in the city, urban waterfront space has efficient ecological benefits, high-quality landscape vision and environment, and it is an important carrier of citizens’ activities. However, existing studies have mainly focused on coping with environmental problems, while social functions and strategies have been neglected. Therefore, this study aims to fill such research gaps by understanding the social performance of urban waterfront spaces. Field observation and questionnaire survey were conducted in a famous urban waterfront space, Qiantang riverside walkway, in Hangzhou, China. The results indicate that the Qiantang riverside walkway serves as a space for tourism, leisure and entertainment, as the visitors who lived more than 5 km away from here accounted for about 50% and the local people also accounted for about 50%. People’s activities exhibited significantly temporal differences, where the occupation of the Qiantang riverside walkway reached a peak at night. For the people who lived far from here, they mainly depended on self-driving, which led to two critical problems relevant to transport linkage with the city and parking lot. Results also indicate that the landscape, supporting facilities and road functions could perform well among the mind of 102 respondents. However, public service and main facilities should be improved to meet more people’s requirements. Moreover, importantly, the results indicate the phenomenon of stratification and agglomeration so that the similar aspects (e.g. rest seat quantity, rest seat style) could be merged into the same cluster (e.g. rest seat) for consideration in the urban waterfront space planning and design. This study also generates some implications for the renovation of urban waterfront spaces. Overall, this study provides people with basic understanding of the social performance of existing urban waterfront spaces, which can further promote urban planners and designers to comprehensively build sustainable, resilient and healthy water-based living environments.
显示更多 [+] 显示较少 [-]Enhanced Gas Chromatography-Mass Spectrometry (GC-MS)-Based Analysis of Metformin and Guanylurea in Water Samples
2020
Tao, Yunwen | Zhang, Baiyu | Zhao, Yuming | Zhu, Zhiwen | Chen, Bing
Metformin is widely used as one of the most effective first-line oral drugs for type 2 diabetes. It is difficult to be metabolized by the human body thus commonly exists in both urine and feces samples. Guanylurea is metformin’s main biotransformation product with increased concentrations in the aquatic environments. Liquid chromatography-tandem mass spectrometry (LC-MS)-based methods used for measuring the two compounds have been well developed, but extremely limited studies have tracked gas chromatography-mass spectrometry (GC-MS)-based analysis. To help better track the occurrence of the two non-volatile biguanide compounds in liquid samples, the improvement of existing GC-MS based methods for reliable metformin and guanylurea analysis is conducted. Derivatization of metformin and guanylurea is the key pretreatment procedure before the associated GC-MS analysis. Four selected factors affecting for the derivatization were evaluated, and the optimal factors include temperature (90°C), reacting time (40 min), solvent (1,4-dioxane), and ratio (1.5:1) of reagent to target component. Buformin and N-methyl-bis(trifluoroacetamide) (MBTFA) were used as the internal standard and the derivatization reagent, respectively. Calibration curves were made based on the optimal conditions of derivatization for metformin and guanylurea with the R² values of calibration linearity achieved as 99.35% and 99.2%, respectively. The values of relative standard deviation (RSD%) of metformin and guanylurea based on seven repeated trails are 2.67% and 15.37%, respectively. The optimal conditions for enhancing the sensitization of metformin and guanylurea derivatization performance were obtained. The improved GC-MS analysis method was eventually applied for metformin and guanylurea analysis in real water samples.
显示更多 [+] 显示较少 [-]Modeling smallholder livestock herders’ intentions to adopt climate smart practices: An extended theory of planned behavior
2020
Faisal, Muhammad | Chunping, Xia | Akhtar, Shoaib | Raza, Muhammad Haseeb | Khan, Muhammad Tariq Iqbal | Ajmal, Muhammad Arslan
Climate change is persistently causing adverse effects to the agriculture sector of developing countries, specifically in Asia. Pakistan is no exception to this effect and is ranked among the top 10 countries, which are most vulnerable to climate change. A huge upcoming challenge is to sustain an equilibrium among production and environmental protection. In this context, adaptation to climate change is considered as a win-win strategy for agriculture sectors in developing countries. However, numerous studies have focused on current farm-level adaptation while a scant interest has been shown on the role of physiological factors in the process of shaping small livestock herders’ intentions towards environmental enrichment measures. A possible explanation of their lagging intentions is particular significance as they may comply with requisite climate adaptation measures or not. For deeper understanding, the current study investigates different psychological factors that affect the small livestock herder’s intentions on adopting climate smart practices by using theory of planned behavior (TPB) with additional constructs (moral norms, risk perception, and social attributes). To this end, 405 small livestock herders from Punjab, Pakistan, were selected on the basis of multistage random sampling. The results of structural equation model showed that all constructs accounted for 57% of the variances in small livestock herders’ adoption intentions. The outcome of this research offers a new indication regarding the interrelationship of numerous variables which are crucial to understand behavioral changes and psychological interventions. Overall attitude was the most prominent construct in the extended TPB model, which is mainly influenced by risk perception awareness. The results suggest that veterinary experts and extension agents should focus on psychological factors to explore different prospects to increase the involvement of livestock herders in environmental enrichment measures with little effort rather than tackling with traditional practices because it will be more likely to affect people’s consideration of the external obstructions to act. Findings also offer public and private intervention for enabling technical and policy environment and strengthen social networks to keep livestock herders on track of updates of running government policies to ensure them to adopt climate change measures for their prosperous future.
显示更多 [+] 显示较少 [-]Modelling tyramine extraction from wastewater using a non-dispersive solvent extraction process
2020
Ghadiri, Mahdi | Himmatī, ʻAlī Riz̤ā | Nakhjiri, Ali Taghvaie | Shirazian, Saeed
Wastewater effluent from alkaloid processing plants has the potential adverse environmental influences. Mathematical modelling and simulations were carried out using computational fluid dynamics of mass and momentum transfer in a hollow fibre membrane extractor. Conservation equations were derived for tyramine extraction in the membrane extractor and solved based on the finite element method. Model findings based on the computational fluid dynamics validated well with the experimental data. The results showed that increase in organic-phase flow rate, as well as the fibre length and its porosity, has a positive impact on the performance of the extractor, whereas the enhancement of aqueous-phase flow rate led to the reduction of tyramine extraction.
显示更多 [+] 显示较少 [-]Recycled moisture in an enclosed basin, Guanzhong Basin of Northern China, in the summer: Contribution to precipitation based on a stable isotope approach
2020
Li, Xiaofei | Lu, Aigang | Feng, Qi | Li, Zhi | Liu, Weiguo | Wang, Shengjie | Tripathee, Lekhendra | Wang, Xiaoyan | Cao, Junji
Recycled moisture, mainly originated from evapotranspiration (surface evaporation and transpiration), is the main sources of precipitation. Influenced on the different regional/local environments, the contributions of recycled moisture to precipitation present as different proportions. Recycled moisture has an important impact on the hydrological cycle, further occurred a series of environmental effect for regional/local. Aimed to estimate the contribution of recycled moisture to precipitation in an enclosed basin, Guanzhong Basin of northern China, precipitation and lake/reservoir samples were collected. The isotope ratio analysis was done for the summer season, and a three-component mixing model based on the stable hydrogen and oxygen isotopes was applied. The results indicated that the averaged contribution of recycled moisture to precipitation was 17.44% in Guanzhong Basin of northern China, while the mean proportions of surface evaporation moisture and transpiration moisture were found to be 0.38% and 16.97%, respectively. Comparatively, most of the recycled moisture mainly comes from transpiration moisture rather than evaporation moisture, suggesting that transpiration moisture from cropland, vegetation, and plants instead of evaporation is dominant in moisture recycling of the Guanzhong Basin.
显示更多 [+] 显示较少 [-]Agrobacterium tumefaciens C58 presence affects Bacillus velezensis 32a ecological fitness in the tomato rhizosphere
2020
Abdallah, Dorra Ben | Krier, François | Jacques, Philippe | Tounsi, Slim | Frikha-Gargouri, Olfa
The persistence of pathogenic Agrobacterium strains as soil-associated saprophytes may cause an inconsistency in the efficacy of the biocontrol inoculants under field condition. The study of the interaction occurring in the rhizosphere between the beneficial and the pathogenic microbes is thus interesting for the development of effective biopesticides for the management of crown gall disease. However, very little is still known about the influence of these complex interactions on the biocontrol determinants of beneficial bacteria, especially Bacillus strains. This study aimed to evaluate the effect of the soil borne pathogen Agrobacterium tumefaciens C58 on root colonization and lipopeptide production by Bacillus velezensis strain 32a during interaction with tomato plants. Results show that the presence of A. tumefaciens C58 positively impacted the root colonization level of the Bacillus strain. However, negative impact on surfactin production was observed in Agrobacterium-treated seedling, compared with control. Further investigation suggests that these modulations are due to a modified tomato root exudate composition during the tripartite interaction. Thus, this work contributes to enhance the knowledge on the impact of interspecies interaction on the ecological fitness of Bacillus cells living in the rhizosphere.
显示更多 [+] 显示较少 [-]Concentrations of toxic metals and essential elements in raw cow milk from areas with potentially undisturbed and highly disturbed environment in Slovakia
2020
Pšenková, Martina | Toman, Róbert | Tančin, Vladimír
Dietary composition and husbandry practices largely determine the essential trace element status and the toxic metal exposure of livestock and consequently their concentrations in animal products. The main objective of this study was to determine the real contamination of selected areas of Slovakia compared with existing Environmental regionalization of the Slovak Republic (SR) created by the Ministry of the Environment SR. Another aim of this study was to determine the content of essential and toxic metals in feed and milk of dairy cows on selected farms in Slovakia referred to the suitability of the use of milk from these areas to other food processing. This article deals with the analysis of the content of selected elements in feed and milk of dairy cows in the area of Novoť (Northern Slovakia; area with undisturbed environment) and Čečejovce (Eastern Slovakia; highly disturbed environment). Eleven elements have been analyzed (essential elements: calcium, zinc, magnesium, selenium, iron, copper; toxic elements: arsenic, cadmium, mercury, lead, nickel). Samples of feed and milk were collected five times during the spring season and five times during the autumn season in 2016. Analysis of samples was performed in Eurofins Bel/Novamann (Nové Zámky, Slovak Republic). Analyses were performed by atomic absorption spectroscopy and atomic emission spectrometry. The obtained values of the individual elements in the feed and milk were evaluated by Student’s t test. Significantly higher contents of essential elements Ca, Zn, Fe, Mg, and Cu were found in the feed of dairy cows in Čečejovce (P < 0.001). Significantly higher (P < 0.001) As and Ni content in feed in Čečejovce in autumn season was also recorded. However, the content of these elements in feed did not affect their milk content. The content of Ca, Zn, and Mg in milk was significantly (P < 0.001) higher in Novoť in both investigated seasons. Some essential elements and toxic elements in feed and milk were below the LOQ (limit of quantification). Reduced content of Ca and Zn in milk in both farms compared with optimal limits, decreased Ca and Mg content in feed in Novoť, and a significant increase of Ca and Mg in feed in Čečejovce in autumn season were found. It can be concluded, due to the low content of toxic elements on these farms, that the use of milk of dairy cows from these areas for direct use or for dairy product processing is appropriate and poses no health risk to the consumers.
显示更多 [+] 显示较少 [-]Seasonal variation and secondary formation of size-segregated aerosol water-soluble inorganic ions in a coast megacity of North China Plain
2020
Yao, Qing | Liu, Zirui | Han, Suqin | Cai, Ziying | Liu, Jingle | Hao, Tianyi | Liu, Jinyun | Huang, Xiaojuan | Wang, Yuesi
The aerosol samples of water-soluble inorganic ions (WSIs), including SO₄²⁻, NO₃⁻, NH₄⁺, Cl⁻, K⁺, Na⁺, Ca²⁺, and Mg²⁺ in size-segregated particulate matter (PM), were collected by an Anderson sampler (with 8 nominal cut-sizes ranged from 0.43 to 9.0 μm) in urban Tianjin during 2013–2014. The results showed that particulate matters in the fine mode (PM₂.₁, Dp < 2.1 μm) comprised large part of mass concentrations of aerosols, and the water-soluble ionic species in the fine mode were 47.07 ± 14.29 μg m⁻³ (spring), 67.87 ± 28.74 μg m⁻³ (summer), 86.60 ± 48.53 μg m⁻³ (autumn), and 104.16 ± 51.76 μg m⁻³ (winter), respectively, which accounted for 59.5%, 63.3%, 71.9%, and 71.4% of the PM₂.₁ mass concentrations. Secondary pollutants of SO₄²⁻, NO₃⁻, and NH₄⁺ (SNA) were the dominant contributors of WSIs, which showed a bimodal size distribution in each season, with the larger peak appeared in the size fraction of 0.65–1.1 μm and the smaller one in 3.3–5.8 μm fraction. SNA concentrations in lightly polluted days (LPD) and heavily polluted days (HPD) were observably higher than non-polluted days (NPD), especially in the fine mode, with the peak diameter moving from 0.43–0.65 μm on NPD to 0.65–1.1 μm on LPD and HPD. The correlation analysis between NH₄⁺, NO₃⁻, and SO₄²⁻ suggested that almost all SO₄²⁻ and NO₃⁻ for fine particles had been completely neutralized by NH₄⁺, and primarily existed in the forms of (NH₄)₂SO₄ and NH₄NO₃. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) on LPD and HPD in fine mode were observably higher than those on NPD, especially in the range of 0.65–1.1 μm and 1.1–2.1 μm. Furthermore, SOR and NOR values in the size fraction of 0.43–3.3 μm increase as the RH elevated, especially in 0.43–2.1 μm, where RH was significantly positive correlated with SOR and NOR, indicating the significant contributions of heterogeneous processes to the secondary formation of SO₄²⁻ and NO₃⁻. These results suggested an enhanced formation ability of secondary pollutants under high RH in the coast city. Therefore, controlling the precursors of SNA, such as SO₂ and NOx, would be more effective to reduce the fine particulate pollution in the coast megacity of Tianjin.
显示更多 [+] 显示较少 [-]The association between dioxins and steroid hormones in general adult males: a cross-sectional study in an e-waste region of China
2020
Shi, Li Li | Wang, Mei Qin | Nakayama, Shoji F. | Jung, Chau-Ren | Wang, Yue Hua | Dong, Jing Jian | Ma, Chao Chen | Kido, Teruhiko | Sun, Xian Liang | Feng, Hao
As observed among residents in electronic waste (e-waste) recycling areas, dioxins can disrupt the homeostasis of endocrine hormones and the balance of thyroid hormones. Few studies, however, have examined whether e-waste recycling activities influence steroid hormone equilibrium in the general adult male population. This study evaluated the association between steroid hormones and the physical burdens of dioxins in the general adult male population residing in an e-waste region. In September 2017, 74 adult males residing in an e-waste dismantling region were enrolled in the current study. Approximately 10 mL of blood was collected from each adult male, and the serum samples were separated through centrifugation. Then, the levels of dioxin and steroid hormones in the serum of the participants were measured. We treated dioxin levels as categorical variables in the general linear model according to quartiles (25, 50, and 75 percentile). Comparing the findings with a reference group (< 25th percentile), we noted significantly higher dehydroepiandrosterone (DHEA) level in men with low serum polychlorinated dibenzofuran-toxic equivalent (PCDFs-TEQ) level between 3.80 and 6.31 pg/g lipid (1933 vs. 1447 pg/ml) and low polychlorinated dibenzo-p-dioxins and dibenzofurans-TEQ (PCDD/PCDFs-TEQ) between 8.57 and 15.11 pg/g lipid (1996 vs. 1360 pg/ml). Moreover, a significantly higher androstenedione (A-dione) level was found in men whose serum PCDFs-TEQ ≥ 11.34 pg/g lipd (2404 vs. 1848). What’s more, there were significantly higher 3β-hydroxysteroid dehydrogenase (3β-HSD) concentrations in low- and high-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) groups (1.30–1.67 and ≥ 2.64 pg-TEQ/g lipid, respectively with 719 and 807 vs. 496, respectively). Our findings suggest that specific dioxin exposure may disturb normal DHEA, A-dione levels, and enzyme activity in the general adult male population in an e-waste region of China.
显示更多 [+] 显示较少 [-]Innovative application of helium-neon laser: enhancing the germination of Adansonia digitata and evaluating the hepatoprotective activities in mice
2020
Khamis, Galal | Hassan, Manar | Morsy, Mona | Ibrahim, Marwa A. | Abd-Elsalam, Reham M. | El Badawy, Shymaa Ahmed | Azouz, Asmaa A. | Galal, Mona
The laser pretreatment of seed is drawing pronounced attention from the scientific community for its positive impact in boosting germination, seedling , and growth of plants. In this study, the laser pretreatment of Adansonia digitata (A. digitata) seeds was evaluated. Eight laser treatments were conducted at different powers, 10, 20, 40, and 80 mW, with the two-time interval for each power at 2 and 4 min. The outcomes indicated that the most efficient irradiation was 10 mW/2 min which induces the highest germination rate and polyphenolic contents for seeds. Based on these results, the animal experimental design was processed to assess the hepatoprotective activity of A. digitata extracts obtained through the optimum laser preillumination to enhance the resistance of liver damage in mice. The total phenol and flavonoid contents and the antioxidant properties of the methanolic extracts were estimated in vitro. The CCl4 was used to induce hepatotoxicity in mice. The animals were divided into five groups. The sera of the treated animals were used for the determination of transaminases, and the liver homogenates were used for the determination of antioxidant status, and further liver tissues were subjected to verify the anti-apoptotic effect of A. digitata methanolic extract. The in vivo results showed that the methanolic extract exposed to laser treatment at 10 mW/2 min provided better hepatoprotective capacity than the other treatments. Administration of A. digitata extract not only offered a significant decrease in liver enzyme activity but also markedly improved the antioxidant status and reduced the apoptotic progression induced by CCl4 toxicity in liver tissue.
显示更多 [+] 显示较少 [-]