61 research outputs found

    The Usability of E-learning Platforms in Higher Education: A Systematic Mapping Study

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    The use of e-learning in higher education has increased significantly in recent years, which has led to several studies being conducted to investigate the usability of the platforms that support it. A variety of different usability evaluation methods and attributes have been used, and it has therefore become important to start reviewing this work in a systematic way to determine how the field has developed in the last 15 years. This paper describes a systematic mapping study that performed searches on five electronic libraries to identify usability issues and methods that have been used to evaluate e-learning platforms. Sixty-one papers were selected and analysed, with the majority of studies using a simple research design reliant on questionnaires. The usability attributes measured were mostly related to effectiveness, satisfaction, efficiency, and perceived ease of use. Furthermore, several research gaps have been identified and recommendations have been made for further work in the area of the usability of online learning

    High-Throughput Quantification of 32 Bioactive Antioxidant Phenolic Compounds in Grapes, Wines and Vinification Byproducts by LC–MS/MS

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    The well-established, health-benefitting effects of grapevines and derivatives (wines and vinification byproducts) are attributed to their antioxidant phenolic content. The dearth of an efficient method for the simultaneous quantitation of antioxidant phenolics prompted us to develop a novel method utilizing triple quadrupole LC–MS/MS for the accurate, fast, simultaneous quantitation of the 32 most abundant grapevine phenolics. The fully validated, novel method is capable to simultaneously record the quantitative presence of 12 phenolic acids, 19 polyphenols and coniferyl aldehyde (a phenolic compound extracted from cork stoppers into wines) and is applicable for the determination of antioxidant phenolics content of grape berries, pomace, stems and wines. Its utility was demonstrated for three native Greek grapevine varieties, two red (Mandilaria and Aidani mavro) and one white (Monemvassia). Results herein highlighted the stems of the Monemvassia white variety as particularly rich in antioxidant phenolics such as the flavonol monomer (+)-catechin (387 mg/kg) and the dimer procyanidin B1 (400 mg/kg) along with stilbene phytoalexin trans-resveratrol (24 mg/kg). These results are in line with the TPC, TFC and TTC content of stems and the determined antioxidant capacities, highlighting the stems of this Vitis vinifera variety as potentially exploitable source of antioxidant phenolics

    Bioactivity of Wild and Cultivated Legumes: Phytochemical Content and Antioxidant Properties

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    The global demand for increased meat production has brought to the surface several obstacles concerning environmental impacts, animals’ welfare, and quality features, revealing the need to produce safe foodstuffs with an environmentally acceptable procedure. In this regard, the incorporation of legumes into animal diets constitutes a sustainable way out that prevents these apprehensions. Legumes are plant crops belonging to the Fabaceae family and are known for their rich content of secondary metabolites., displaying significant antioxidant properties and a series of health and environmental benefits. The study herein aims to investigate the chemical composition and antioxidant activities of indigenous and cultivated legume plants used for food and feed. The respective results indicate that the methanolic extract of Lathyrus laxiflorus (Desf.) Kuntze displayed the highest phenolic (64.8 mg gallic acid equivalents/g extract) and tannin (419.6 mg catechin equivalents/g extract) content, while the dichloromethane extract of Astragalus glycyphyllos L., Trifolium physodes Steven ex M.Bieb. and Bituminaria bituminosa (L.) C.H.Stirt. plant samples exhibited the richest content in carotenoids lutein (0.0431 mg/g A. glycyphyllos extract and 0.0546 mg/g B. bituminosa extract), α-carotene (0.0431 mg/g T. physodes extract) and β-carotene (0.090 mg/g T. physodes extract and 0.3705 mg/g B. bituminosa extract) establishing their potential role as vitamin A precursor sources. Results presented herein verify the great potential of Fabaceae family plants for utilization as pasture plants and/or dietary ingredients, since their cultivation has a positive impact on the environment, and they were found to contain essential nutrients capable to improve health, welfare, and safety

    The current status of positron emission mammography in breast cancer diagnosis

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    Mammography is currently the standard breast cancer screening procedure, even though it is constrained by low specificity in the detection of malignancy and low sensitivity in women with dense breast tissue. Modern imaging modalities, such as magnetic resonance imaging (MRI), have been developed in an effort to replace or complement mammography, because the early detection of breast cancer is critical for efficient treatment and long-term survival of patients. Nuclear medicine imaging technology has been introduced in the field of oncology with the development of positron emission tomography (PET), positron emission tomography/computed tomography (PET/CT) and, ultimately, positron emission mammography (PEM). PET offers the advantage of precise diagnosis, by measuring metabolism with the use of a radiotracer and identifying changes at the cellular level. PET/CT imaging allows for a more accurate assessment by merging the anatomic localization to the functional image. However, both techniques have not yet been established as diagnostic tools in early breast cancer detection, primarily because of low sensitivity, especially for sub-centimeter and low-grade tumors. PEM, a breast-specific device with increased spatial resolution, has been developed in order to overcome these limitations. It has demonstrated higher detectability than PET/CT and comparable or better sensitivity than MRI. The ability to target the lesions visible in PEM with PEM-guided breast biopsy systems adds to its usability in the early diagnosis of breast cancer. The results from recent studies summarized in this review indicate that PEM may prove to be a useful first-line diagnostic tool, although further evaluation and improvement are required. © 2012 The Japanese Breast Cancer Society

    Asymmetric Synthesis of γ

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    Retrieval of High Added Value Natural Bioactive Coumarins from Mandarin Juice-Making Industrial Byproduct

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    Cold pressed essential oil (CPEO) of mandarin (Citrus reticulata Blanco), a by-product of the juice-making industrial process known to contain large amounts of polymethoxyflavones, was exploited for its content in high added value natural coumarins. The study herein afforded a method referring to the evaporation of CPEO volatile fraction under mild conditions (reduced pressure and temperature below 35 °C) as azeotrope with isopropanol. This allowed the isolation of high added value coumarins from the non-volatile fragment using preparative High Performance Liquid Chromatography (HPLC). Pilot-scale application of this procedure afforded for each kg of CPEO processed the following natural bioactive coumarins in chemically pure forms: heraclenol (38–55 mg), 8-gerayloxypsoralen (35–51 mg), auraptene (22–33 mg), and bergamottin (14–19 mg). The structures of coumarins were verified by Nuclear Magnetic Resonance (NMR) spectroscopy and HPLC co-injection with authentic standards. Thus, the low market value mandarin CPEO with current value of 17 to 22 EUR/kg can be valorized through the production of four highly bioactive natural compounds worth 3479 to 5057 EUR/kg, indicating the great potentials of this methodology in the terms of the circular economy
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