Surface enhanced Raman spectroscopy (SERS) based detection schemes for food analysis

The development of food industry over the last century broadened the range of available food products and increased the awareness of society regarding the importance of a healthy diet. As a direct consequence of this, norms and regulation regarding the composition of different products were formulated and are enforced. Still, different food products have a very short shelf-life (i.e. fruits and vegetable) and accordingly, their analysis should be performed in a time and price effective way, while maintaining a high standard for the quality and reliability of the analysis. The current gold standard analytical technique for most of the food products is high performance liquid chromatography (HPLC) combined with different detection schemes such as UV-Vis spectroscopy, fluorescence spectroscopy or mass spectrometry. There are, however, analytes where HPLC-based measurements encounter difficulties and research is still needed in order to overcome these. For those molecules, analysis based on biological assays are applied as reference analytical method. The objective of the present thesis was to investigate the applicability of surface enhanced Raman spectroscopy (SERS) for the analysis of food products. In order to evaluate the potential and limitations of SERS toward these applications, the thesis is divided in two parts. First, different SERS-active substrates were tested and characterized in order to decide on the best-suited substrate for the development of the analytical procedure. While doing this, the substrates’ homogeneity and not their enhancement properties was prioritized. This is thoughtfully discussed in the first part of the results section of the thesis. Second, two selected applications, with increasing degree of complexity, were developed. In both situations a complete analytical procedure is introduced, starting from a thoughtfully understanding of the molecules fingerprint and ending with the measurements and analysis of food extracts. In the first application the tested food product was a market-available fortified cereal and in the second application, different garden-grown tomatoes were analyzed.Neben der stetig wachsenden Lebensmittelindustrie und dem damit verbundenen Anstieg der Vielfalt von Lebensmitteln, erhöhte sich in der jüngeren Geschichte auch das Bewusstsein für eine gesunde Ernährung in der Bevölkerung. Dies führte zur Formulierung von Normen und Vorschriften, die die Zusammensetzung unterschiedlicher Produkte festlegt. Um deren Einhaltung zu überwachen, werden kostengünstige und, unter dem Gesichtspunkt der kurzen Haltbarkeit vieler Lebensmittel, schnelle analytische Methoden benötigt. Dabei muss die Methode dennoch hohen Qualitätsstandards genügen und zuverlässige Resultate liefern. Der derzeitige Goldstandard zur analytischen Untersuchung von Lebensmitteln ist die Hochleistungsflüssigkeitschromatographie (englisch high performance liquid chromatography, HPLC) in Kombination mit unterschiedlichen Detektionsmethoden, wie der UV-Vis-Spektroskopie, Fluoreszenzspektroskopie oder Massenspektrometrie. Für gewisse Analyte sind die Ergebnisse HPLC-basierter Messungen allerdings nicht aussagekräftig genug und weiterer Forschungsaufwand ist vonnöten, um dort Fortschritte zu erzielen. Daher sind für diese Fälle nach wie vor biologische Assays der Goldstandard. Die vorliegenden Arbeit beschäftigt sich mit der Frage nach der Anwendbarkeit der oberflächenverstärkten Raman-Spektroskopie (englisch surface enhanced Raman spectroscopy, SERS) zur Untersuchung von Lebensmitteln. Um das Potential von SERS diesbezüglich beurteilen zu können, wurde die Arbeit in zwei wesentliche Abschnitte unterteilt. Zuerst wurden unterschiedliche SERS-aktive Substrate getestet und charakterisiert, um das geeignetste Substrat zur Analyse von Lebensmitteln zu finden. Hier lag der Fokus allen voran auf der Homogenität der Substrate und weniger auf deren Verstärkungseigenschaften. Auf dieses Vorgehen wird zu Beginn des Ergebnisteils ausführlich eingegangen. Anschließend wurden zwei konkrete Applikationen, mit steigender Komplexität, entwickelt. Das erste Anwendungsbeispiel bezieht sich auf angereicherte Cornflakes, die auf dem Markt frei erhältlich sind. Tomaten aus Gartenanbau wurden als zweite Applikation untersucht. Beginnend mit der Bestimmung des molekularen Fingerabdrucks, bis hin zur Messung von Lebensmittelextrakten und der Datenanalyse, werden hierfür vollständige Analyseverfahren vorgestellt

IMPORTANCE AND OPPORTUNITIES OF SENTIMENT ANALYSIS IN DEVELOPING E-LEARNING SYSTEMS THROUGH SOCIAL MEDIA

The means of communication and interaction have benefited from incredible changes over the past decade, Social Media increasingly replacing traditional environments. Considering the collaborative nature of the learning sector and consequently the importance of communication and interaction within it, we intuitively realize that Social Media represents the future of educational systems, the research in this field pointing towards the integration of e-Learning with Social Media. However, in order to deliver efficient educational systems, it is not enough to identify the technological means that are conducive to their development, but is also important to shape these means depending on the needs of the target group. When we discuss about Social Media and learning, it is noticed that individuals are the direct beneficiaries and the main force of these environments. Therefore, it is important to understand their behavior, their needs and wants. Analyzing students\u27 attitudes, identifying their positive or negative reactions, or even the refined emotions they have towards learning, can be an extremely difficult task due to their diversity in countless ways. In this regard, an increasingly used tool whose accuracy cannot be challenged is the Sentiment Analysis. The inherent nature of Social Media tools offers multiple areas of application of Sentiment Analysis. Therefore, this paper will discuss the importance of Sentiment Analysis towards e-Learning development through Social Media, considering current evidence. Secondly, the paper aims to identify the opportunities offered by Social Media with regards to Sentiment Analysis implementation and how feedback on educational data can be collected via such online environments to help improve educational processes in an e-Learning context

IMPORTANCE AND OPPORTUNITIES OF SENTIMENT ANALYSIS IN DEVELOPING E-LEARNING SYSTEMS THROUGH SOCIAL MEDIA

The means of communication and interaction have benefited from incredible changes over the past decade, Social Media increasingly replacing traditional environments. Considering the collaborative nature of the learning sector and consequently the importance of communication and interaction within it, we intuitively realize that Social Media represents the future of educational systems, the research in this field pointing towards the integration of e-Learning with Social Media. However, in order to deliver efficient educational systems, it is not enough to identify the technological means that are conducive to their development, but is also important to shape these means depending on the needs of the target group. When we discuss about Social Media and learning, it is noticed that individuals are the direct beneficiaries and the main force of these environments. Therefore, it is important to understand their behavior, their needs and wants. Analyzing students\u27 attitudes, identifying their positive or negative reactions, or even the refined emotions they have towards learning, can be an extremely difficult task due to their diversity in countless ways. In this regard, an increasingly used tool whose accuracy cannot be challenged is the Sentiment Analysis. The inherent nature of Social Media tools offers multiple areas of application of Sentiment Analysis. Therefore, this paper will discuss the importance of Sentiment Analysis towards e-Learning development through Social Media, considering current evidence. Secondly, the paper aims to identify the opportunities offered by Social Media with regards to Sentiment Analysis implementation and how feedback on educational data can be collected via such online environments to help improve educational processes in an e-Learning context

European Efficiency or Inefficiency in Economic Growth Through Digital Transformation

The current global changes bring to the fore the importance of the innovation and digital transformation for economic development. Under the previous assumption, an objective evaluation of the economic growth discrepancies, considering the digitalization process, is required. The main goal of the present research is to analyse the economic growth of the European countries, based to the digitalization process, by using an input-output method. Under these circumstances, a Data Envelopment Analysis (DEA) was performed, considering the digitalization dimensions of DESI Index as input and the economic growth (annual %) as output. Based on the proposed model, the results highlighted the bidirectional relationship between economic growth and digitalization. Consistent with the research results, the European countries can be divided in two main categories: the efficient and the inefficient. On one hand, we can find the relatively efficient European states in terms of achieving the economic growth through digitalization (Ireland, Romania, Croatia and Greece). On the other hand, there is a numerous list of the inefficient ones, including important countries like Finland, Germany or France. Obviously, a remarkable aspect related to their situation is that, considering the national available inputs, an output maximization will be possible. According to the proposed model, the efficient countries can serve as peers or optimal benchmarks for solving the issue of relative inefficiency, by adapting and implementing their good practices

Toward food analytics: fast estimation of lycopene and β-carotene content in tomatoes based on surface enhanced Raman spectroscopy (SERS)

Carotenoids are molecules that play important roles in both plant development and in the well-being of mammalian organisms. Therefore, various studies have been performed to characterize carotenoids’ properties, distribution in nature and their health benefits upon ingestion. Nevertheless, there is a gap regarding a fast detection of them at the plant phase. Within this contribution we report the results obtained regarding the application of surface enhanced Raman spectroscopy (SERS) toward the differentiation of two carotenoid molecules (namely, lycopene and β-carotene) in tomato samples. To this end, an e-beam lithography (EBL) SERS-active substrate and a 488 nm excitation source were employed, and a relevant simulated matrix was prepared (by mixing the two carotenoids in defined percentages) and measured. Next, carotenoids were extracted from tomato plants and measured as well. Finally, a combination of principal component analysis and partial least squares regression (PCA-PLSR) was applied to process the data, and the obtained results were compared with HPLC measurements of the same extracts. A good agreement was obtained between the HPLC and the SERS results for most of the tomato samples

Dentists, members of the French Resistance movement during the World War II

The Resistance was a reaffirmation of France's independence and individuality, as well as a struggle to regain freedom and, above all, national integrity. In fact, many historians appreciate that the French Resistance could have achieved more if it had been more effectively integrated into Allied plans and strategies. Thus, in this material we tried to present some short biographies of dentists who worked in the French Resistance against the German occupation troops, some of them even paying with their lives for the courage they showed

Bohr Hamiltonian with a potential having spherical and deformed minima at the same depth

A solution for the Bohr-Mottelson Hamiltonian with an anharmonic oscillator potential of sixth order, obtained through a diagonalization in a basis of Bessel functions, is presented. The potential is consid- ered to have simultaneously spherical and deformed minima of the same depth separated by a barrier (a local maximum). This particular choice is appropriate to describe the critical point of the nuclear phase transition from a spherical vibrator to an axial rotor. Up to a scale factor, which can be cancelled by a corresponding normalization, the energy spectra and the electromagnetic E2 transition probabilities depend only on a single free parameter related to the height of the barrier. Investigations of the numerical data revealed that the model represents a good tool to describe this critical point

The geographical distribution of the Romanian churches abroad the country. A valuable source of information on the international migrations of our fellow country men

The quantification and analysis of international migrations have always represented difficult approaches especially because of the lack of some reliable statistical data. Consequently, alternative sources of information (such as religious institutions and administrative boards of different Christian cults) are not to be neglected. However, from this point of view, significant differentiations can be highlighted: the Catholic Church has always been keen on good quality statistical registrations (more or less Neoprotestant cults fit this pattern, too); in its turn, Orthodoxy tries to catch up on the lost ground by means of a considerable administrative organization. Thus, from the different incidence of religion-triggered emigration to the geographical distribution of the cult edifices abroad the country, the connection between migration and religion is a very powerful one. In this sense, our analysis is meant to spot the most important features of the Romanian diaspora