Search results for "ROMA"
showing 10 items of 13919 documents
Intercomparison of spanish advanced lidars in the framework of EARLINET
2007
To extend and reinforce the action of the EARLINET- ASOS project, a nucleus of Spanish advanced lidars was created. Four systems were intercompared satisfactorily in terms of backscatter coefficients at two elastic wavelengths. Peer Reviewed
Application of time-of-flight aerosol mass spectrometry for the online measurement of gaseous molecular iodine.
2012
Here we present a new application of a time-of-flight aerosol mass spectrometer (TOF-AMS) for the measurement of atmospheric trace gases in real-time. Usually, TOF-AMS instruments are not sensitive to gas-phase species due to the aerodynamic particle focusing inlet system which reduces the gas phase species by a factor of about 10(7) relative to the particle phase. This efficient removal of the gas phase and the resulting high relative enrichment of particles is one reason for the very high sensitivity of TOF-AMS instruments for particle phase compounds (detection limits in the sub-μg/m(3)-range for online measurements with 1 min integration time), which allows application of the instrument…
Dissolution and hydrolysis of fibre sludge using hydroxyalkylimidazolium hydrogensulphate ionic liquids
2014
Abstract The dissolution and hydrolysis of wet fibre sludge in ionic liquids (ILs) with different reaction conditions are performed in this study. Novel types of hydroxyalkylimidazolium hydrogensulphate ILs, [glymim]HSO 4 , [hemim]HSO 4 and [hpmim]HSO 4 , are especially designed and aimed to combine the dissolution and hydrolysis of wet fibre sludge in a one-step pretreatment. The results were obtained based on the analysis of total reducing sugars (TRS) with the DNS method. The dissolution and hydrolysis of fresh wild horse chestnut fruit ( Aesculus hippocastanum ) with the same ILs were also carried out as a comparison reference. Since fibre sludge is cellulose based and horse chestnut fr…
Cytogenetic effects of promutagens in genetically engineered V79 Chinese hamster cells expressing cytochromes P450.
1993
Abstract V79 Chinese hamster cell lines genetically engineered to express rat CYP2B1, CYP1A1, CYP1A2, and their parental cell lines V79-MZ, without acetyltransferase, and V79-NH, with acetyltransferase, were studied for chromosome aberrations and sister chromatid exchange induced by aflatoxin B 1 , cyclophosphamide, benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene and dimethylnitrosamine. The parental V79 cell lines did not show clastogenic effects. Significant clastogenic effects were observed after an 18 h exposure to aflatoxin B 1 and cyclophosphamide in CYP2B1 expressing cells, to benzo[a]pyrene in CYP1A1 and CYP1A2 expressing cells, to 7,12-dimethylbenz[a]anthracene and dimethylnitrosami…
Dominant contribution of P450 3A4 to the hepatic carcinogenic activation of aflatoxin B1.
2006
The hepatic carcinogen aflatoxin B1 (AFB1) is metabolized in the liver by at least four different P450s, all of which exhibit large interindividual differences in the expression levels. These differences could affect the individual risk of hepatocellular carcinoma (HCC). We investigated the metabolism of AFB1 in a panel of 13 human liver microsomal preparations using a hepatic abundance model, which takes into account the specific kinetic parameters and the expression levels of these P450s. We found a 12-fold variability in the production rate of the carcinogenic metabolite AFB1-8,9-epoxide (AFBO) and a 22-fold variability in the production of the detoxification product AFQ1. The ratio betw…
Bimodal porous silica nanomaterials as sorbents for an efficient and inexpensive determination of aflatoxin M1 in milk and dairy products
2020
Abstract An extraction procedure was developed for the determination of aflatoxin M1 in milk and dairy products. A sorbent based on UVM-7 mesoporous silica was used as solid phase for the sample clean-up, and the analyte determination was carried out by HPLC coupled to a fluorescence detector. The material architecture was characterized by transmission electronic microscopy, X-ray diffraction, 29Si NMR and nitrogen adsorption-desorption. After the optimization of extraction parameters, the influence of the matrix has been evaluated, obtaining recoveries in the range 78–105% for whole and skimmed milk and yogurt matrix. The reusability of the material was also proved. The sensitivity of the …
Occurrence of Aflatoxins in Tigernuts and Their Beverages Commercialized in Spain
2010
A method based on matrix solid phase dispersion extraction was applied to determine aflatoxins B(1), B(2), G(1), and G(2) from tigernuts and tigernut beverages. Recoveries of each aflatoxin from tigernut (spiked at 10 microg/kg level) and from tigernut beverages (spiked at 10 microg/L level) ranged from 72.3 to 82.1% and from 74.0 to 86.3%, respectively. The limits of quantification ranged from 0.21 to 1.49 microg/kg (for tigernuts) and from 0.13 to 0.57 microg/L (for tigernut beverages) studied using liquid chromatography with fluorescence detection. The proposed extraction method followed by liquid chromatography-fluorescence detection determination was applied to 37 and 25 samples of tig…
Determination of aflatoxins in peanuts by matrix solid-phase dispersion and liquid chromatography
2003
A new method based on matrix solid-phase dispersion (MSPD) extraction was studied to determine aflatoxin B1, B2, G1 and G2 from peanuts. Optimization of different parameters, such as type of solid supports for matrix dispersion and elution solvents were carried out. The method used 2 g of peanut sample, 2 g of C18 bonded silica as MSPD sorbent and acetonitrile as eluting solvent. Recoveries of each aflatoxin spiked to peanut samples at 2.5 ng/g (5 ng/g for aflatoxin G2) level were between 78 and 86% with relative standard deviations ranging from 4 to 7%. The limits of quantification ranged from 0.125 to 2.5 ng/g for the four studied aflatoxins using liquid chromatography (LC) with fluoresce…
Limited survey for the presence of aflatoxins in foods from local markets and supermarkets in Valencia, Spain.
2004
Aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) were extracted by matrix solid-phase dispersion with C18 silica and acetonitrile as the eluting solvent, analysed by liquid chromatography with fluorescence detection and confirmed by liquid chromatography with mass spectrometry using an electrospray interface in 58 samples grouped as cereals, dried fruits, herbs and spices, pulses, snacks, and nuts and nut products collected from local markets and supermarkets in Valencia, Spain. All samples analysed by the proposed method were previously studied with an enzyme-linked immunosorbent assay as a screening protocol for the fast detection of mycotoxins. The samples containing residues (3/5…
Presence of aflatoxin M1 in pasteurized milk from Morocco
2007
Fifty four samples of pasteurized milk produced by five different dairies from Morocco were surveyed for the presence of aflatoxin M1 (AFM1) using immunoaffinity columns and liquid chromatography coupled to fluorescence detection. Confirmation of AFM1 identity in positive samples was based on the formation of AFM1 hemi-acetal derivative (AFM2a) after derivatization with trifluoracetic acid. Analytical results showed that 88.8% of the samples were contaminated with AFM1; 7.4% being above the maximum level of 0.05 microg/L set by the Moroccan and European regulations for AFM1 in liquid milk. The incidence of AFM1 in milk from these dairies was 100, 92.3, 90, 83.3 and 77.7% respectively, with …