169,857 research outputs found
Polyamide modified with green tea extract for fresh minced meat active packaging applications
No full textNew antioxidant polyamide was prepared by total immersion in active extract for 48 h. Its antioxidant performance was tested using DPPH (IC50 = 270 ± 21 μg/g) and ORAC (1.52 μmol Trolox/g). In vivo study was done using fresh minced meat stored at 4 °C and analysed after 0, 6, 13, 19, 23 days. After 23 days metmyoglobin (MetMbBK = 31.3 ± 2.9% and MetMbAOX = 25.9 ± 0.8%), CIE L*a*b* (a*BK = 15.0 ± 0.4 and a*AOX = 16.6 ± 0.3) and TBARS (MDABK = 0.0060 ± 0.0003 μg/g and MDAAOX = 0.0044 ± 0.0002 μg/g) showed an improvement of meat shelf life. The results showed that this active film protected meat during 23 days. Migration study to food simulants was done by UPLC®-QqQ-MS and UPLC®-ESI-Q-TOF-MSE. A decrease of oligomers migration (for caprolactam n = 3: BK = 0.050 ± 0.004 mg/Kg; AOX = 0.019 ± 0.001 mg/Kg) was found. Industrial relevance: Nowadays, food industry is focused on improving shelf life of products by controlling its lipid oxidation using natural antioxidants. The obtained results let us design a new active packaging based on natural antioxidants for extending the shelf life of fresh minced meat at industrial scale
Development and validation of a LC–MS/MS method for the analysis of bisphenol a in polyethylene terephthalate
No full textBisphenol A (BPA) is widely recognized being an endocrine disrupter and it is employed in many food packaging applications. Although it is not intended to take part in the manufacture of polyethylene terephthalate (PET) food grade, the presence of BPA in recycled PET should not be neglected. To satisfy the increasing need to ensure “BPA-free” articles, a liquid chromatography-tandem mass spectrometry method was developed. The crucial step in the sample preparation was the total dissolution/reprecipitation of the polymer. The repeatability of the method (RSD%, n = 6) was lower than 7.6%, while HorRat values ranged between 0.3 and 0.5. Limits of detection and quantitation were 1.0 and 3.3 ng g−1, respectively. Recovery ranged from 89 to 107%. The method was applied to 23 samples of virgin and recycled pellets, preforms and bottles. Migration tests were also carried out. Results shown significantly higher levels of BPA in recycled PET
Supercritical fluid extraction of energetic nitroaromatic compounds and their degradation products in soil samples
No full textThis paper explores the use of supercritical fluid extraction (SFE), in combination with various analyte collection strategies, for extracting energetic nitroaromatic compounds and their degradation products from soil samples. The required selectivity has been achieved by a combination of an SFE program and active trapping. Several different collection strategies were tested, using a selection of liquids (methanol, toluene, methyl tert-butyl ether, acetonitrile), inert and solid-phase extraction materials (Nexus, Oasis, LiChrolut), and 1-cm, liquid chromatography precolumns (porous graphitic carbon, PGC). The best results were obtained using SFE in combination with a PGC precolumn. This setup allows on-line cleanup of the extract, and comparable results were obtained using either GG-ECD or GC-chemical ionization-MS for confirmatory analysis. The time required for a complete analysis was less than 60 min, and only 1 mL of toluene was needed for a 0.5-g representative sample. In contrast, the EPA standard method 8330 required 18-h sonication and 20 mL of acetonitrile for a 4.0-g sample and further time for sample cleanup and HPLC analysis. The method presented here provides method detection limits in the low-nanogram range, with relative standard deviations lower than 7%. The optimized method has been compared and validated with EPA method 8330 in terms of efficiency parameters such as robustness, accuracy (trueness and precision), and capability of detection. The validation demonstrated that the two analytical methodologies give comparable performance for the determination of nitroaromatic compounds, but SFE is superior for analyzing amine degradation products
Diffusional behaviour of essential oil components in active packaging polypropylene films by Multiple Head-Space-Solid Phase Microextraction-Gas Chromatography (MHS-SPME-GC-MS)
No full textEssential oils (EOs) are promising substances to be incorporated in food packaging materials as antioxidant and/or antimicrobial agents in active packaging systems. Once incorporated into the materials, their constituent compounds diffuse through the material. However, there is little information about the diffusion behaviour of EOs in plastics, and this is one of the major drawbacks in the design of active packaging relying on EOs as active agents. This study presents a new method for studying the diffusion of basil, citronella, oregano and rosemary EOs into plastic films. Diffusion assays of EOs from a coated polypropylene (PP) film into a stack of virgin PP films were conducted by the Moisan method using up to 10 layers of PP. Direct quantification of diffused analytes from the plastic sheets was performed by multiple headspace solid phase microextraction–gas chromatography–mass spectrometry. The fitting of experimental data for the main EO components with a Fickian model gave diffusion and partition (between active and virgin PP) coefficients, which are discussed under the light of some intrinsic factors contributing to the diffusion process. The results demonstrate the dependence of diffusion and partition coefficients on the initial concentration of EO components in the coated films, on their molecular weight and on their polarity. In particular, for similar molecular weight and initial concentration, a higher polarity is responsible for a faster diffusion, whereas lower polarity determines the retention of the EO component in the coating layer
Antioxidant activity of coatings containing eugenol for flexible aluminium foils to preserve food shelf-life
No full textActive food packaging is an innovative system that avoids food deterioration ensuring quality, safety and shelf life extension of food. Herein, two novel eugenol vinyl-based resins were used for coating flexible aluminium foils with potential packaging applications. Coatings were prepared with single eugenol or loaded eugenol in Santa Barbara Amorphous15 (SBA-15) mesoporous silica nanoparticles, and their antioxidant activity was investigated by DPPH, ABTS, ORAC, TBARS assays and by the hydroxyl free radicals' generator method with HPLC analysis. Antioxidant activity was also evaluated exposing the coatings to various food simulants. Both coatings revealed adequate antioxidant capacity when exposed to fatty food simulants and to vapour phase hydroxyl free radicals (scavenging > 50%). The incorporation of eugenol in SBA-15 reduced its release to 65%, promoting eugenol beneficial antioxidant effects over time. The release of eugenol from the coatings into food simulants is not required for the activity of free radical scavenging
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
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