خيارات البحث
النتائج 3511 - 3520 من 4,308
Green synthesis of gold nanoparticles using fungus Mariannaea sp. HJ and their catalysis in reduction of 4-nitrophenol النص الكامل
2017
Pei, Xiaofang | Qu, Yuanyuan | Shen, Wenli | Li, Huijie | Zhang, Xuwang | Li, Shuzhen | Zhang, Zhaojing | Li, Xuanying
In the present study, biosynthesis of gold nanoparticles (AuNPs) by the cells (cells-AuNPs) and cell-free extracts (extracts-AuNPs) of a new fungus Mariannaea sp. HJ was reported. The as-synthesized particles were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The effects of different parameters on AuNP biosynthesis were investigated, and initial gold ion concentration of 2 mM, pH 7, was demonstrated to be suitable for both cells-AuNP and extracts-AuNP syntheses. The cells-AuNPs were of various shapes, including sphere, hexagon, and irregular shapes, with an average size of 37.4 nm, while the extracts-AuNPs were almost spherical and pseudo-spherical with an average size of 11.7 nm. XRD pattern suggested that the crystal structure of both AuNPs was face-centered cubic. FTIR spectra implied that some biomolecules from the fungal cell walls or cell-free extracts were involved in the formation of AuNPs. The as-synthesized AuNPs were demonstrated to have excellent catalytic activities for the reduction of 4-nitrophenol with the catalytic rate constants of 5.7 × 10⁻³/s for cells-AuNPs and 24.7 × 10⁻³/s for extracts-AuNPs. To the best of our knowledge, this is the first report on AuNP biosynthesis by Mariannaea sp.
اظهر المزيد [+] اقل [-]Effects of an oil spill on the leaf anatomical characteristics of a beach plant (Terminalia catappa L.) النص الكامل
2017
Punwong, Paramita | Juprasong, Yotin | Traiperm, Paweena
This study investigated the short-term impacts of an oil spill on the leaf anatomical structures of Terminalia catappa L. from crude oil leakage in Rayong province, Thailand, in 2013. Approximately 3 weeks after the oil spill, leaves of T. catappa were collected along the coastline of Rayong from one affected site, five adjacent sites, and a control site. Slides of the leaf epidermis were prepared by the peeling method, while leaf and petiole transverse sections were prepared by paraffin embedding. Cell walls of adaxial epidermal cell on leaves in the affected site were straight instead of the jigsaw shape found in leaves from the adjacent and control sites. In addition, the stomatal index of the abaxial leaf surface was significantly lower in the affected site. Leaf and petiole transverse sections collected from the affected site showed increased cuticle thickness, epidermal cell diameter on both sides, and palisade mesophyll thickness; in contrast, vessel diameter and spongy mesophyll thickness were reduced. These significant changes in the leaf anatomy of T. catappa correspond with previous research and demonstrate the negative effects of oil spill pollution on plants. The anatomical changes of T. catappa in response to crude oil pollution are discussed as a possible indicator of pollution and may be used in monitoring crude oil pollution.
اظهر المزيد [+] اقل [-]Cancer risk from gaseous carbonyl compounds in indoor environment generated from household coal combustion in Xuanwei, China النص الكامل
2017
Lui, Ka-Hei | Dai, Wen-Ting | Chan, Chi-Sing | Tian, Linwei | Ning, Bo-Fu | Zhou, Yiping | Song, Xiaolin | Wang, Bei | Li, Jinwen | Cao, Jun-Ji | Lee, Shun-Cheng | Ho, Kin-Fai
Airborne carbonyls were characterized from emitted indoor coal combustion. Samples were collected in Xuanwei (Yunnan Province), a region in China with a high rate of lung cancer. Eleven of 19 types of samples (58%) demonstrated formaldehyde concentrations higher than the World Health Organization exposure limit (a 30-min average of 100 μg m⁻³). Different positive significant correlations between glyoxal/methylglyoxal and formaldehyde/acetaldehyde concentrations were observed, suggesting possible different characteristics in emissions between two pairs of carbonyl compounds. A sample in the highest inhalation risk shows 29.2 times higher risk than the lowest sample, suggesting different coal sampling locations could contribute to the variation of inhalation risk. Inhabitants in Xuanwei also tend to spend more time cooking and more days per year indoors than the national average. The calculated cancer risk ranged from 2.2–63 × 10⁻⁵, which shows 13 types of samples at high-risk level. Cumulative effect in combination with different carbonyls could have contributed to the additive actual inhalation cancer risk. There is a need to explicitly address the health effects of environmentally relevant doses, considering life-long exposure in indoor dwellings.
اظهر المزيد [+] اقل [-]Valuing health risk in agriculture: a choice experiment approach to pesticide use in China النص الكامل
2017
Jin, Jianjun | Wang, Wenyu | He, Rui | Gong, Haozhou
This paper presents a choice experiment approach to investigate farmers’ valuations for health risk changes associated with pesticide use in Anqiu County, China. An empirical comparison on the disparity between farmers’ willingness to pay (WTP) for a health risk reduction and willingness to accept (WTA) for the same risk increase is also conducted. Respondents were randomly assigned into the WTP group or the WTA group. Four attributes (health consequence, baseline risk, risk change size, and price) were identified and included. The results show that cancer consequence due to pesticide use decreases the utility of the farmer. A higher baseline risk has a higher WTP to reduce the risk and a higher probability of receiving compensation. If the health risk change size is bigger, it will result in a higher WTP and higher compensation. Household income, education, and age have significant and positive impacts on farmers’ WTP. Farmers who are more educated or female are more likely to accept the compensation scheme if health risks increase. The marginal WTA for the same risk change is about two times higher than the marginal WTP. The findings of this study can contribute to the literature comparing people’s WTP and WTA in a discrete choice experiment on valuing health risk changes associated with pesticide use.
اظهر المزيد [+] اقل [-]Method for quantifying NSAIDs and clofibric acid in aqueous samples, lumpfish (Cyclopterus lumpus) roe, and zebrafish (Danio rerio) eleutheroembryos and evaluation of their bioconcentration in zebrafish eleutheroembryos النص الكامل
2017
Molina-Fernandez, N. | Perez-Conde, C. | Rainieri, S. | Sanz-Landaluze, J.
Pharmaceuticals such as nonsteroidal anti-inflammatory drugs (NSAIDs) and lipid regulators are being repeatedly detected at low concentrations (pg · mL⁻¹–ng · mL⁻¹) in the environment. A large fraction of these compounds are ionizable. Ionized compounds show different physico-chemical properties and environmental behavior in comparison to their neutral analogs; as a consequence, the quantification methods currently available, based on the neutral molecules, might not be suitable to detect the corresponding ionized compounds. To overcome this problem, we developed a specific analytical method to quantify NSAIDs and lipid regulators (i.e., ibuprofen, diclofenac, naproxen, and clofibric acid) and their ionized compounds. This method is based on three steps: (1) the extraction of the organic compounds with an organic solvent assisted with an ultrasonic probe, (2) the cleaning of the extracts with a dispersive SPE with C₁₈, and (3) the determination of the chemical compounds by GC-MS (prior derivatization of the analytes). We demonstrated that the proposed method can successfully quantify the pharmaceuticals and their ionized compounds in aqueous samples, lumpfish eggs, and zebrafish eleutheroembryos. Additionally, it allows the extraction and the cleanup of extracts from small samples (0.010 g of wet weight in pools of 20 larvae) and complex matrixes (due to high lipid content) and can be used as a basis for bioaccumulation assays performed with zebrafish eleutheroembryos in alternative to OECD test 305.
اظهر المزيد [+] اقل [-]Biofilms in bioremediation and wastewater treatment: characterization of bacterial community structure and diversity during seasons in municipal wastewater treatment process النص الكامل
2017
Yousra Turki, | Mehri, Ines | Lajnef, Rim | Rejab, Asma Ben | Khessairi, Amel | Cherif, Hanene | Ouzari, Hadda | Hassen, Abdennaceur
The bacterial community structure and diversity were assessed at the scale of rotating biodisk procedure (RB) in a semi-industrial pilot plant. As well, the Salmonella community was particularly monitored, and the effects of ultraviolet (UV-C₂₅₄) on the bacterial community were studied. The identification of dominant bacteria revealed the presence of beneficial and useful species that could play an important role in the process of wastewater purification. Several species as Enterobacter agglomerans, Cronobacter sakazakii, and Pantoea agglomerans known for their bioremediation activities were revealed in the majority of biofilm samples. Common detection of Salmonella community provides evidence that the RB system did not seriously affect Salmonella. Furthermore, the investigation on the (UV)-C₂₅₄ inactivation of the whole bacterial community, in secondary treated wastewater, showed variable UV resistance results. No Salmonella detection was registered at a dose of around 1440 mW s cm⁻² since a total disappearance of Salmonella was recorded.
اظهر المزيد [+] اقل [-]Plasticizers and bisphenol A, in packaged foods sold in the Tunisian markets: study of their acute in vivo toxicity and their environmental fate النص الكامل
2017
Beltifa, Asma | Feriani, Anouar | Machreki, Monia | Ghorbel, Asma | Ghazouani, Lakhdar | Di Bella, Giuseppa | Van Loco, Joris | Reyns, Tim | Mansour, HediBen
Today, processed and packaged foods are considered as among the major sources of human exposure to plasticizers and bisphenol which migrate from plastic packing. In the present study, a wide range of food products sold on the Tunisian market such as grain and grain products, milk and dairy products, fats and oil, drink, fish, and sweets have been analyzed firstly in order to identify the presence of phthalates and bisphenol. Then, the identified chemical molecules were studied for their environmental fate and tested in vivo for its toxicity in mice models. The food products analyzed using GC-MS/MS indicated the presence of the benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), bis(2-ethylhexyl) phthalate (DEHP), diisodecyl phthalate (DiDP), diisononyl phthalate (DiNP), and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINC) and which using UPLC-MS/MS demonstrated the presence of bisphenol A of all food products. However, compared to other phthalates, BBP was found at high concentrations in the puff pastry (123 mg/kg), milk (2.59 mg/kg), butter (1.5 mg/kg), yogurt (2.23 mg/kg), oil (6.94 mg/kg), water (0.57 mg/kg), candy 1 (2.35 mg/kg), candy 2 (0.81 mg/kg), orange juice (1.25 mg/kg), peach juice (1.26 mg/kg), fruit juices (0.4 mg/kg), and chocolate (0.884 mg/kg). The obtained data in vivo clearly showed that the acute administration of BBP caused hepatic and renal damage as demonstrated by an increase in biochemical parameters as well as the activities of plasma marker enzymes such as alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, blood urea nitrogen, glucose, urea, creatinine, and uric acid when compared to the control group. By the same occurrence, the histopathological study revealed that BBP strongly modified the structure of hepatic and renal tissues. In addition, the plasticizers and BBP will therefore discharge via wastewater treatment plants in aquatic system and could reach marine organisms such as fish. We have followed the fate of BBP in bream Sparus aurata. In fact, chemical analysis showed the contamination of wild S. aurata by BBP from Sousse Coast (1.5 mg/kg) and wild S. aurata from Monastir Coast (0.33 mg/kg).
اظهر المزيد [+] اقل [-]Effect of small proportion of butanol additive on the performance, emission, and combustion of Australian native first- and second-generation biodiesel in a diesel engine النص الكامل
2017
Rahman, MdMofijur | Rasul, MohammadGolam | Hassan, NurMd Sayeed | Ācāt, Apulkalām | Uddin, MdNasir
This paper aims to investigate the effect of the addition of 5% alcohol (butanol) with biodiesel-diesel blends on the performance, emissions, and combustion of a naturally aspirated four stroke multi-cylinder diesel engine at different engine speeds (1200 to 2400 rpm) under full load conditions. Three types of local Australian biodiesel, namely macadamia biodiesel (MB), rice bran biodiesel (RB), and waste cooking oil biodiesel (WCB), were used for this study, and the data was compared with results for conventional diesel fuel (B0). Performance results showed that the addition of butanol with diesel-biodiesel blends slightly lowers the engine efficiency. The emission study revealed that the addition of butanol additive with diesel-biodiesel blends lowers the exhaust gas temperature (EGT), carbon monoxide (CO), nitrogen oxide (NOx), and particulate matter (PM) emissions whereas it increases hydrocarbon (HC) emissions compared to B0. The combustion results indicated that in-cylinder pressure (CP) for additive added fuel is higher (0.45–1.49%), while heat release rate (HRR) was lower (2.60–9.10%) than for B0. Also, additive added fuel lowers the ignition delay (ID) by 23–30% than for B0. Finally, it can be recommended that the addition of 5% butanol with Australian biodiesel-diesel blends can significantly lower the NOx and PM emissions.
اظهر المزيد [+] اقل [-]Cork boiling wastewater treatment and reuse through combination of advanced oxidation technologies النص الكامل
2017
Ponce-Robles, L. | Miralles-Cuevas, S. | Oller, I. | Agüera, A. | Trinidad-Lozano, M. J. | Yuste, F. J. | Malato, S.
Industrial preparation of cork consists of its immersion for approximately 1 hour in boiling water. The use of herbicides and pesticides in oak tree forests leads to absorption of these compounds by cork; thus, after boiling process, they are present in wastewater. Cork boiling wastewater shows low biodegradability and high acute toxicity involving partial inhibition of their biodegradation when conventional biological treatment is applied. In this work, a treatment line strategy based on the combination of advanced physicochemical technologies is proposed. The final objective is the reuse of wastewater in the cork boiling process; thus, reducing consumption of fresh water in the industrial process itself. Coagulation pre-treatment with 0.5 g/L of FeCl₃ attained the highest turbidity elimination (86 %) and 29 % of DOC elimination. Similar DOC removal was attained when using 1 g/L of ECOTAN BIO (selected for ozonation tests), accompanied of 64 % of turbidity removal. Ozonation treatments showed less efficiency in the complete oxidation of cork boiling wastewater, compared to solar photo-Fenton process, under the studied conditions. Nanofiltration system was successfully employed as a final purification step with the aim of obtaining a high-quality reusable permeate stream. Monitoring of unknown compounds by LC-QTOF-MS allowed the qualitative evaluation of the whole process. Acute and chronic toxicity as well as biodegradability assays were performed throughout the whole proposed treatment line.
اظهر المزيد [+] اقل [-]Does the use of distiller’s dried grains with solubles (DDGS) in layer diets affect the nutrients digestibility and manure pollution by nitrogen and phosphorous? النص الكامل
2017
Abd El-Hack, Mohamed E. | El-Hindawy, Mohamed M. | Attia, Adel I. | Mahrose, Khalid M.
The objective of the current study was to examine the effect of the inclusion levels of distiller’s dried grains with solubles (DDGS) which partially and fully replaced soybean meal (SBM) in laying hen diets with or without enzyme or vitamin E supplementation on nutrients digestibility and excreted nitrogen and phosphorous. For these purposes, a total of 180 Hisex Brown laying hens at 22 weeks of age were randomly distributed into 15 treatment groups in a 5 × 3 factorial design experiment including five levels of DDGS (0, 5.5, 11, 16.5 and 22% replaced for the same percent of SBM which represents 0, 25, 50, 75 and 100% respectively in the diet) and three levels of feed additives (without, 250 mg enzyme/kg diet or 200 mg vitamin E/kg diet) through 22–42 weeks of age. Results revealed that digestion coefficient values of nutrients including DM, OM, CP, EE, NFE and CF were more preferable in hens fed diets involved 25% DDGS instead of SBM than that of the control diet and other treatment groups. In contrast, hens fed 100% substitution of DDGS caused significant (P ≤ 0.01) decrease in digestibility coefficients of all nutrients. The amount of daily excreted N was decreased in hens fed 25 or 50% DDGS substitution, whilst feeding 75 or 100% DDGS led to an elevation in N excretion. The proportion of excreted phosphorous was statistically (P ≤ 0.01) decreased as the level of DDGS increased. Generally, neither enzyme nor vitamin E supplementation had any significant effect on the studied parameters. It could be concluded that DDGS could be used up to 50% as a replacement of SBM (11% of the diet) without any adverse effects on nutrients digestibility. Laying hen farms using DDGS up to 25 or 50% substituted for SBM in its diets (5.5 or 11% of the diet) will have clearer environment of nitrogen and phosphorous pollution than others whose diets free of DDGS.
اظهر المزيد [+] اقل [-]