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Результаты 1301-1310 из 1,552
Inactivation of bacteria under visible light and in the dark by Cu films. Advantages of Cu-HIPIMS-sputtered films Полный текст
2012
Ehiasarian, A. | Pulgarin, Cesar | Kiwi, John
INTRODUCTION: The Cu polyester thin-sputtered layers on textile fabrics show an acceptable bacterial inactivation kinetics using sputtering methods. MATERIALS AND METHODS: Direct current magnetron sputtering (DCMS) for 40 s of Cu on cotton inactivated Escherichia coli within 30 min under visible light and within 120 min in the dark. For a longer DCMS time of 180 s, the Cu content was 0.294% w/w, but the bacterial inactivation kinetics under light was observed within 30 min, as was the case for the 40-s sputtered sample. RESULTS AND DISCUSSION: This observation suggests that Cu ionic species play a key role in the E. coli inactivation and these species were further identified by X-ray photoelectron spectroscopy (XPS). The 40-s sputtered samples present the highest amount of Cu sites held in exposed positions interacting on the cotton with E. coli. Cu DC magnetron sputtering leads to thin metallic semi-transparent gray–brown Cu coating composed by Cu nanoparticulate in the nanometer range as found by electron microscopy (EM). Cu cotton fabrics were also functionalized by bipolar asymmetric DCMSP. CONCLUSION: Sputtering by DCMS and DCMSP for longer times lead to darker and more compact Cu films as detected by diffuse reflectance spectroscopy and EM. Cu is deposited on the polyester in the form of Cu2O and CuO as quantified by XPS. The redox interfacial reactions during bacterial inactivation involve changes in the Cu oxidation states and in the oxidation intermediates and were followed by XPS. High-power impulse magnetron sputtering (HIPIMS)-sputtered films show a low rugosity indicating that the texture of the Cu nanoparticulate films were smooth. The values of R q and R a were similar before and after the E. coli inactivation providing evidence for the stability of the HIPIMS-deposited Cu films. The Cu loading percentage required in the Cu films sputtered by HIPIMS to inactivate E. coli was about three times lower compared to DCMS films. This indicates a substantial Cu metal savings within the preparation of antibacterial films.
Показать больше [+] Меньше [-]Analytical improvements of hybrid LC-MS/MS techniques for the efficient evaluation of emerging contaminants in river waters: a case study of the Henares River (Madrid, Spain) Полный текст
2012
Pérez-Parada, Andrés | Gómez-Ramos, María del Mar | Martínez Bueno, María Jesús | Uclés, Samanta | Uclés, Ana | Fernández-Alba, Amadeo R.
PURPOSE: Instrumental capabilities and software tools of modern hybrid mass spectrometry (MS) instruments such as high-resolution mass spectrometry (HRMS), quadrupole time-of-flight (QTOF), and quadrupole linear ion trap (QLIT) were experimentally investigated for the study of emerging contaminants in Henares River water samples. METHODS: Automated screening and confirmatory capabilities of QTOF working in full-scan MS and tandem MS (MS/MS) were explored when dealing with real samples. Investigations on the effect of sensitivity and resolution power influence on mass accuracy were studied for the correct assignment of the amoxicillin transformation product 5(R) amoxicillin-diketopiperazine-2′,5′ as an example of a nontarget compound. On the other hand, a comparison of quantitative and qualitative strategies based on direct injection analysis and off-line solid-phase extraction sample treatment were assayed using two different QLIT instruments for a selected group of emerging contaminants when operating in selected reaction monitoring (SRM) and information-dependent acquisition (IDA) modes. RESULTS AND DISCUSSION: Software-aided screening usually needs a further confirmatory step. Resolving power and MS/MS feature of QTOF showed to confirm/reject most findings in river water, although sensitivity-related limitations are usually found. Superior sensitivity of modern QLIT-MS/MS offered the possibility of direct injection analysis for proper quantitative study of a variety of contaminants, while it simultaneously reduced the matrix effect and increased the reliability of the results. Confirmation of ethylamphetamine, which lacks on a second SRM transition, was accomplished by using the IDA feature. CONCLUSION: Hybrid MS instruments equipped with high resolution and high sensitivity contributes to enlarge the scope of targeted analytes in river waters. However, in the tested instruments, there is a margin of improvement principally in required sensitivity and data treatment software tools devoted to reliable confirmation and improved automated data processing.
Показать больше [+] Меньше [-]Laboratory assessment of uptake and toxicity of lanthanum (La) in the leaves of Hydrocharis dubia (Bl.) Backer Полный текст
2012
Xu, Qinsong | Fu, Yongyang | Min, Haili | Cai, Sanjuan | Sha, Sha | Cheng, Guangyu
Increasing amounts of lanthanum (La) is released into aquatic environments. However, little information is available on the influence of La on aquatic plants. In this study, physiological and ultrastructural responses of Hydrocharis dubia (Bl.) Backer leaves to elevated concentrations of La (up to 160 μM) were investigated. The accumulation of La was found to be increased in a concentration-dependent manner. La disturbed the intrinsic balance of nutrient elements (P, Mg, Ca, Fe, K, and Zn). Pigment content decreased with the rise of the La concentrations and the EC50 value for chlorophyll was 20 μM on day 7. The antioxidants (superoxide dismutase, peroxidase, catalase, reduced ascorbate, and reduced glutathione) exhibited varied response to the La treatments. Malondialdehyde content enhanced gradually at all La concentrations. The enhancement in proline content was found in a concentration-dependent manner. The amounts of three polypeptides with apparent molecular weights of 61.9, 51.5, and 16.7 kDa, respectively, were gradually diminished, as well as one existing polypeptides with apparent molecular weight of 22.3 kDa, elevating in response to increasing La concentrations. Significant damage to the chloroplast, mitochondrion, and nucleus was imposed by La indicated a general disarray in the cellular functions. The negative effects of La on H. dubia unequivocally indicate that La could exert an adverse influence on aquatic ecosystem and should lead to a more careful discharge of such elements into water environment.
Показать больше [+] Меньше [-]Genotoxicity associated with oxidative damage in the liver and kidney of mice exposed to dimethoate subchronic intoxication Полный текст
2012
Ayed-Boussema, Imen | Rjiba, Karima | Moussa, Amal | Mnasri, Nourhène | Bacha, Hassen
BACKGROUND AND AIMS: Because of the widespread use of pesticides for domestic and industrial applications, the evaluation of their toxic effects is of major concern to public health. The aim of the present study was to investigate the propensity of dimethoate (DM), an organophosphorus pesticide, to cause oxidative damage in the liver and kidney of mice and its associated genotoxic effect. METHODS: DM was administered intraperitoneally at doses of 1, 5, 10, 15, and 30 mg/kg body weight for 30 consecutive days in BALB/c mice. Oxidative stress was monitored in the kidney and liver by measuring malondialdehyde level, protein carbonyl concentration, and the catalase activity. The genotoxicity of DM was assessed by the comet assay in vivo. RESULTS AND DISCUSSION: Our results indicated that DM inhibited acetylcholinesterase activities in the liver and kidney of treated mice. DM increased lipid peroxidation and protein carbonyl levels in the liver and kidney in a dose-dependent manner. Catalase activity was found to be significantly increased in the liver and kidney at doses higher than 5 mg/kg body weight. CONCLUSIONS: Our study demonstrated that DM induced DNA damage in the liver and kidney of treated mice in a dose-dependent manner; this induction was associated to DM-induced oxidative stress. Further investigations are needed to prove the implication of oxidative stress in genotoxicity induced by DM.
Показать больше [+] Меньше [-]Copper chitosan nanocomposite: synthesis, characterization, and application in removal of organophosphorous pesticide from agricultural runoff Полный текст
2012
Jaiswal, Meha | Chauhan, Divya | Sankararamakrishnan, Nalini
PURPOSE: Removal of malathion from agricultural runoff was studied using novel copper-coated chitosan nanocomposite (CuCH)—a biopolymeric waste obtained from marine industry. METHODS: Synthesis and characterization of the adsorbent using different spectral techniques like Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer, Emmett, and Teller surface analyzer have been carried out. Equilibrium studies have been carried out to optimize the dose rate, pH, and the reaction time. Parathion and methyl parathion removal were also evaluated by CuCH in the batch mode. Using gas chromatography–mass spectrometry (GC–MS) and FTIR studies suitable mechanism for adsorption has been suggested. RESULTS: The particle size of the adsorbent ranged from 700 to 750 nm. The surface area was found to be 20 m2 g-1 with a pore volume of 0.11 cc g-1. The maximum adsorption capacity of malathion by CuCH was found to be 322.6 ± 3.5 mg g-1 at an optimum pH of 2.0. Presence of copper ions enhanced the adsorption capacity of the adsorbent. The reaction was found to follow pseudo second-order kinetics with a rate constant of 0.53 g mg-1 min-1. Evidence from FTIR indicated that copper ions form a dithionate complex with malathion during the adsorption stage. The adsorbent was found to remove malathion completely from spiked concentration of 2 mg l-1 in the agricultural run-off samples. It was also found that CuCH removed other organophospurous pesticides like methyl parathion and parathion under prevailing conditions. CONCLUSIONS: The results indicated that CuCH could be applied for the removal of organophosphorous pesticides.
Показать больше [+] Меньше [-]Volatile organic compounds and bioaerosols in the vicinity of a municipal waste organic fraction treatment plant. Human health risks Полный текст
2012
Vilavert, Lolita | Nadal, Martí | Figueras, María J. | Domingo, José L.
PURPOSE: The aim of this study was to analyze air concentrations of chemical and microbiological pollutants in the vicinity of an organic waste treatment plant, Ecoparc-2, located in Montcada i Reixac (Catalonia, Spain), as well as to determine the seasonal trends. The human health risks due to the presence of those agents were also assessed. METHODS: Air samples were collected at different distances and wind directions from the Ecoparc-2 in two campaigns (winter and summer of 2010). The levels of 19 volatile organic compounds (VOCs) were analyzed by GC-MS or HPLC-UV. In turn, the airborne amount of total bacteria, gram-negative bacteria, and fungi (including Aspergillus fumigatus) was also determined. RESULTS: Mean VOC concentrations were found to be 32.4 and 15.7 μg/m3 in winter and summer, respectively. Fungi at 25°C presented the highest geometric mean (1,126 and 863 cfu/m3 in winter and summer, respectively), while the concentrations of fungi at 37°C and total bacteria were also important in the hot season (332 and 250 cfu/m3, respectively). These results are in agreement with data obtained from the scientific literature. Anyhow, no significant differences were observed between both campaigns including those related to distances and wind directions. The current pollutant levels in the surrounding environment were also various orders of magnitude lower than those recently observed inside the facility. CONCLUSIONS: The human exposure to VOCs near the Ecoparc-2 was estimated to be low. Furthermore, the current environmental concentrations of those chemical and microbiological agents were clearly below threshold values recommended by regulatory organizations.
Показать больше [+] Меньше [-]Oxidative transformation of carbamazepine by manganese oxides Полный текст
2012
He, Yan | Xu, Jian | Zhang, Yuan | Guo, Changsheng | Li, Lei | Wang, Yuqiu
This study presents oxidative transformation of carbamazepine by synthetic manganese oxide (δ-MnO2) as well as impact of variables including initial MnO2 loading, pH, coexisting metal ions, and humic acid (HA) on transformation. Manganese oxide (δ-MnO2) was synthesized and stored in the form of suspension. The oxidative reactions were conducted in 50 mL polyethylene (PE) centrifuge tubes with constant pH maintained by buffers. The kinetic experiment was carried out in the solution of pH 2.72 containing 5.0 mg/L of carbamazepine and 130.5 mg/L of MnO2. Effects of initial MnO2 loading (0–130.5 mg/L), pH (2.72–8.58) and 0.01 M of coexisting solutes (metal ions and HA) on carbamazepine oxidation were also determined. Reaction kinetics indicated that carbamazepine was rapidly degraded in the first 5 min, and approximately 95 % of carbamazepine was eliminated within 60 min. The reaction exhibited pronounced pH dependence and increased with decreasing pH values. The transformation of carbamazepine was also accelerated with increasing MnO2 loadings. Coexisting metal ions competed with carbamazepine for reactive sites leading to reduced carbamazepine removal, and the inhibitive capacity followed the order of Mn2+ > Fe3+ > Ca2+ ≈ Mg2+. Presence of HA in aqueous solution caused a significant reduction on the magnitude of carbamazepine transformation. This study indicated that carbamazepine can be effectively degraded by δ-MnO2, and transformation efficiency was strongly dependent on reaction conditions. It suggests that amendment of soil with MnO2 be a potential alternative to solve carbamazepine pollution.
Показать больше [+] Меньше [-]Daily, seasonal and monthly variations in ozone levels recorded at the Turia river basin in Valencia (Eastern Spain) Полный текст
2012
Castell-Balaguer, Nuria | Téllez, Laura | Mantilla, Enrique
INTRODUCTION: The Turia river basin, located in the east of the Iberian Peninsula, drains into the Mediterranean Sea near the city of Valencia (population, 814,208). The predominance of sea-breeze fluxes favours the inland transport of pollutants from the city up the basin where ozone concentrations exceeding the threshold for protection of human health are systematically recorded during the summer months. METHODS: This work analyses the variability in ozone levels by examining their spatial and temporal distribution in a Mediterranean river basin downwind from a city within the period 2005–2008. Orographic determinants and atmospheric fluxes induce strong variations in ozone measurements, even on relatively close locations. CONCLUSIONS: Results show a different behaviour of the monthly means and the daily cycles depending on the season of the year and the measuring environment, with summer/winter ratios ranging from 2.4 in cities to 1.6 inland, and mean values always higher in the interior of the basin. Daily cycles show significant summer/winter differences related to the predominant situations of anticyclonic stability in winter, which limit ventilation, and the predominant breeze circulations in summer. Results also show a “weekend effect” at urban and medium-distance stations. At the most inland station, the weekend/weekday behaviour differs according to the season of the year; weekend ozone levels are higher in spring, autumn and winter, and lower in summer, coinciding with the predominance of local wind cycles that favour air mass penetration inland from the coast.
Показать больше [+] Меньше [-]Enhancement of natural radioactivity in fertilized soil of Faisalabad, Pakistan Полный текст
2012
Ak̲h̲tar, Nasīm | Sabiha-Javied, | Tufail, M.
BACKGROUND, GOAL, AND SCOPE: Natural radioactivity in phosphate rock (PR) is transferred to phosphate fertilizer (PF) during the manufacturing process of the PF. The continuous addition of the PF to the cultivated soil accumulates the radionuclides in the land and increases the level of radioactivity in the soil. The purpose of the present study was to investigate the enhanced level of accumulated radioactivity due to the continuous addition of the PF in the farmlands of Nuclear Institute of Agriculture and Biology (NIAB) at Faisalabad in Pakistan. The selected study area consisted of the highly fertilized farmlands and an unfertilized barren land of the NIAB. INTRODUCTION: The understudy area is very fertile for the growth of various types of crops; therefore, four agricultural research institutes have been established at Faisalabad and NIAB is one of those. The NIAB has developed various research farmlands at different places in Pakistan. The crop yield has been increased by adding various fertilizers in the farmlands. The addition of the PF accompanied with the radionuclides enhances radioactivity in the fields. Human being is exposed directly or indirectly to this radiological hazard. A prolong exposure may become a cause of health risk. MATERIALS AND METHODS: The area of study consisted of three types of lands: the land under cultivation for the last 40 and 30 years called Site 1 and Site 2, respectively, and the barren land was called Site 3. A total of 75 soil samples were collected within the crop rooting zone (up to 25 cm deep) of the soil of the NIAB farms. The samples were dried, pulverized to powder, sealed in plastic containers, and stored to achieve equilibrium between 226Ra and 222Rn. Activity concentrations of the radionuclides 238U (226Ra), 232Th, and 40K in soil samples were determined by using a high resolution gamma ray spectrometry system, consisting of an high purity germanium detector coupled through a spectroscopy amplifier with a PC based MCA installed with Geni-2000 software. RESULTS: The measured activity concentration levels of 40K were 662 ± 15, 615 ± 17, and 458 ± 20 Bq kg−1, 226Ra were 48 ± 6, 43 ± 5, and 26 ± 4 Bq kg−1, and that of 232Th were 39 ± 5, 37 ± 5, 35 ± 5 Bq kg−1, respectively, in the soil of the Sites 1, 2, and 3. Gamma dose rate 1 m above the soil surface was 55, 51, and 40 nGy h−1 from Sites 1, 2, and 3, respectively. External dose rates in the rooms constructed of the bricks made of the soil from Sites 1, 2, and 3 were 161, 149, and 114 nGyh−1, respectively. DISCUSSIONS: Activity concentration values of 40K and 226Ra in the soil of Sites 1 and 2 were higher than that in the soil of Site 3. The relative rise of 40K was 43 % and 34 % and that of 226Ra was 85 % and 65 % respectively in these sites. Activity concentrations of 232Th in all these sites were in the background range. Gamma dose rate 1 m above soil surface of Sites 1 and 2 was 40 % and 30 % respectively higher than that from the soil of Site 3. The rise in activity of 40K and 226Ra and gamma dose from the Site 1 was greater than that from the Site 2. The least activity and dose were observed from the Site 3. Gamma dose in the dwellings made of fertilized soil bricks of Site 1 and Site 2 were respectively calculated to be 41 % and 32 % higher than that in the abodes made of unfertilized soil bricks of Site 3. CONCLUSIONS: Activity concentrations of 226Ra and 40K were observed to be enhanced in the fertilized farmlands of the NIAB. Outdoor and indoor gamma dose as radiological hazard were found to be increasing with the continuous addition of PF in the understudy farmlands. RECOMMENDATIONS: It is recommended that naturally occurring radioactive metal should be removed during the process of manufacturing of the PF from the PR. PROSPECTIVE: The rise in radioactivity in the farmlands due to the addition of the PF can be a source of direct or indirect exposure to radiation that may enhance cancer risk of the exposed individuals.
Показать больше [+] Меньше [-]Possible use of Serratia marcescens in toxic metal biosorption (removal) Полный текст
2012
Cristani, Mariateresa | Naccari, Clara | Nostro, Antonia | Pizzimenti, Alessia | Trombetta, Domenico | Pizzimenti, Francesco
BACKGROUND, AIM AND SCOPE: Metal pollution is a serious problem for environmental safety and programmes of monitoring and bioremediation are needed. Among the processes of bioremediation, the use of microbes to remove and degrade contaminants is considered a biotechnological approach to clean up polluted environments. AIM: The aim of this study was to evaluate the ability of Serratia marcescens in Pb, Cd and Cr removal and the potential use of these bacteria in toxic metal bioremediation from polluted environments. METHODS: A short-term study (120 min) was carried out to study the bacterial growth in the presence of sub-inhibitory concentrations of each metal analysed and the kinetics of metal biosorption in S. marcescens strain. In addition, metal influence on the biosynthesis of the red pigment ‘prodigiosina’ by S. marcescens was monitored. RESULTS: The results obtained in this study show metals biosorption by S. marcescens (range: 0.0133–0.213 μg/g for Pb; 0.097–0.1853 μg/g for Cd; and 0.105–0.176 μg/g for Cr) and confirm the possible use of this bacterium to realize bioremediation processes, especially for Pb removal, and as a bioindicator of metal pollution.
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