131,416 research outputs found
Development of rapid and simple methods for aflatoxins determination for food safety and control
No full textLe aflatossine si possono trovare come contaminanti naturali in una varietà di prodotti alimentari tra cui: cereali, noccioline,arachidi, pistacchi, patate dolci, burro di arachidi, banane, vino, spezie, latte e latticini, ecc. Perciò è molto importante avere metodi semplici e abbastanza rapidi per l’analisi di queste sostanze.
Le tecniche immunologiche hanno il vantaggio rispetto alle tecniche classiche (cromatografia) di non richiedere elevata purificazione e concentrazione, inoltre sono rapidi, semplici da adoperare, sensibili e specific. La loro specificità è dovuta all’uso di anticorpi monoclonali o policlonali selettivi per quellla tossina.
Lo scopo di questa tesi di dottorato è stato quello di realizzare metodi per la determinazione del’aflatossina M1 e B1, che possano essere semplici da adoperare, rapidi e privi della necessità di una procedura di estrazione molto complicata/elaborata.
La tesi è stata strutturata nei sequenti capitoli:
Capitolo I. Descrive alcuni aspetti generali riguardanti la tossicità, struttura chimica, la contaminazione, la legislazione e metodi di detossificazione delle aflatossine.
Capitolo II. Presenta lo stato del arte nel campo dei metodi analitici della determinazione di aflatossine, tra cui un sottocapitolo dedicato ai kit comerciali disponibili al momento.
Capitolo III. Descrive le applicazioni sperimentali realizzate durante questa tesi, divise in due metodi per la determinazione dell’aflatossina M1 in latte (un metodo immunologico accopiato con l’analisi amperometrica in flusso e un altro metodo che utilizza delle piastre a 96-pozzetti elettrochimiche accopiate con la tecnica amperometrica ad impulsi intermitenti). La seconda parte è stata focalizzata sull’ottimizzazione di un metodo spettrofotometrico immunoenzimatico per la determinazione dell’aflatossina B1 in campioni di mais utilizzando un nuovo coniugato AflatossinaB1-fosfatasi alcalina (AFB1-AP) realizzato nel nostro laboratorio, non essendo comercialmente disponibile. In più, è stato realizzato anche uno studio della stabilità dell’aflatossina M1 in campioni freschi di latte contaminati artificialmente e conservati a 4°C (latte liofilizzato) ed a -30°C (latte liquido) per 3 mesi. Questo studio è stato realizzato applicando la tecnica amperometrica ad impulsi intermitenti accopiata con l’utilizzo delle piastre a 96-pozzetti elettrochimiche.
Capitolo IV. Sottolinea tutte le applicazioni analitiche per la determinazione dell’aflatossina M1 e B1 in campioni reali con le loro charatteristiche, vantaggi e svantaggi.Aflatoxins can be found as natural contaminants in a variety of food ingredients such as, cereals and cereals products, peanuts, nuts, almonds, pistachios, hazelnut and other dried fruits, coconut, cocoa, sweet potato, peanut butter, bananas, wine, spices, milk and milk products, etc. It is, therefore, important to have available, simple and quantitative methods for aflatoxin analysis.
Rapid methods based on immunochemical techniques usually have the advantage of not requiring clean-up or analyte-enrichment steps, are speed, ease of operation, sensitive and specific by using the specific monoclonal or polyclonal antibodies produced against the toxin.
The aim of this Ph.D. thesis was to develop methods for AFM1 and AFB1 determination which should be simple of operation, rapid and not requiring a complex clean-up procedure.
The thesis has been structured in the following chapters:
• Chapter I describes some general aspects regarding the toxicity, chemical structure, contamination, legislation and detoxification methods regarding aflatoxins.
• Chapter II presents the state of the art in the field of analytical methods for aflatoxins determination, including commercial kits available at the moment of the writing of this thesis.
• Chapter III describes the experimental applications carried out during this thesis, which are divided in two methods for AFM1 determination in milk samples (a Flow Injection Immunoassay with amperometric detection and an electrochemical multichannel microplate coupled with Intermittent Pulse Amperometry) and a second part which is focused on a spectrophotometric enzyme immunoassay for AFB1 determination in corn samples using a new conjugate Aflatoxin B1-alkaline phosphatase (AFB1-AP) prepared in our laboratory, being not commercial available. Moreover, a study of stability of AFM1 in raw milk samples stored at 4°C (lyophilized milk) and -30°C (liquid milk) for 3 months, was carried out. The study was realized with the electrochemical multichannel plate with IPA technique.
• Chapter IV underlines all analytical applications for AFM1 and AFB1 determination in real samples with its performance, advantages and drawbacks
Inflammation in Cancer: Part of the Problem or Part of the Solution?
No full text[abstract not available
Carbon black-based disposable sensor for an on-site detection of freechlorine in swimming pool water
No full textChlorine is the most common chemical compound used for treatment of water at ppm levels, although at higher concentration it can generate harmful disinfection by-products. To easily monitor the correct level of free chlorine, cost-effective and miniaturized devices for fast and on-site detection are required. Herein, we report the development of a novel miniaturized and cost-effective screen-printed electrode modified with carbon black nanomaterial for an effective amperometric detection of free chlorine in swimming pool water. The carbon black was used as working electrode modifier for chlorine quantification at low applied potential, overcoming the fouling problem. In addition, the use of stable and cost-effective carbon black dispersion allows for a mass-production of the modified sensor by an automatable drop casting method. This sensor has demonstrated the capability to detect free chlorine in a linear range of 0.05–200 ppm with a detection limit of 0.01 ppm in standard solution as well as in swimming pool water. The achieved results demonstrated for the first time the suitability of the carbon black as electrode nanomodifier for free chlorine detection, and the possibility to produce a miniaturized and cost-effective carbon black-based printed sensor for reliable free chlorine quantification in water samples
Study of a toxin-alkaline phosphatase conjugate for the development of an immunosensor for tetrodotoxin determination
No full textThis paper describes a direct competitive immunoenzymatic spectrophotometric assay (ELISA) for tetrodotoxin (TTX) determination and the adaptation of this method for use in an electrochemical assay format. The novelty of this work involves the use of the antigen labelled with alkaline phosphatase (AP); this conjugate was prepared in our laboratory as there is no commercially available conjugate of any kind for TTX. The new conjugate was characterized in terms of its affinity for the specific antibody as well as the residual concentration and the residual activity of the enzyme (AP) incorporated as label. The proposed method based on the new conjugate showed satisfactory results for TTX determination: for the spectrophotometric method the dynamic range was 4-15 ng mL(-1) with a limit of detection (LOD) of 2 ng mL(-1) (R=0.9247), whereas for the electrochemical protocol the dynamic range was 2-50 ng mL(-1) and the LOD was1 ng mL(-1)
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
NEETs and the process of Transition from School-to-the Labor Market: A Comparative Analysis of Italy, Romania and Bulgaria
No full textThe aim of this article is to identify the main mechanisms leading to the NEET status in Italy, Romania, and Bulgaria. It does so by highlighting the differences amongst them and verifying how place of residence effectively affects the connected propensity to this status after having controlled for many personal characteristics through a series of probit models. Furthermore, multiple correspondence analyses produce profound understanding of the NEET phenomenon and associated determinants. The results highlight the need to plan support actions tailored to specific NEET characteristics. Whilst the degree of urbanization impacts upon the NEET status throughout Romania and Bulgaria, Italy shows a strong divide between the North and the South. However, in all three countries there is a need to improve the education system and stimulate higher levels of education as the main measure of NEET prevention
A Miniaturized Carbon Black-based Electrochemical Sensor for Chlorine Dioxide Detection in Swimming Pool Water
No full textThe recent trend of using sustainable disinfectants in water treatment sector boosted the employment of chlorine dioxide (ClO2) as green disinfectant. Indeed, this disinfectant is characterised by several attractive features such as the working capability in a wide range of pH and the absence of harmful by-products. These characteristics confer to chlorine dioxide a prominent position between the disinfectants, thus analytical tools for on-site detection are needed to customize the water treatment. Herein, we described the development of an innovative and cost-effective carbon black modified screen-printed electrode for amperometric quantification of chlorine dioxide in standard solution and in swimming pool water. The carbon black as working electrode nanomodifier allowed for the detection of chlorine dioxide at low applied potential, with linear range of 0.05-20 ppm, and a detection limit of 0.01 ppm. The matrix effect evaluation as well as the recovery study demonstrated the capability of this sensor for a cost-effective detection of chlorine dioxide in swimming pool water, paving the way for the use of miniaturised electrochemical sensors in water treatment field
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
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