197 research outputs found
RuCl3 supported on N-doped graphene as reusable catalyst for one-step glucose oxidation to succinic acid
No full text[EN] Impregnation of RuCl3 on N-doped graphenes results in the formation of well-dispersed, small ruthenium oxyhydroxide nanoparticles supported on N-doped graphene that may exhibit high selectivity (87%) for the conversion of glucose into succinic acid under wet oxidation conditions (160 degrees C, 18atm O-2 pressure). Ruthenium loading and N-atom distribution on graphene influence the catalytic activity, the best performing catalyst having 1wt.% Ru loading on a graphene having a large population of graphenic N atoms. The high catalytic selectivity to succinic acid was correlated with the presence of small ruthenium nanoparticles. The present catalyst improves the best one previously reported because it does not require the continuous addition of an excess of amine to reach high succinic acid selectivity and reusability.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, Grapas and TQ2015-69563-CO2-R1) and by the Generalitat Valenciana (Prometeo 2013-014) is gratefully acknowledged. J.A. also thanks the Universitat Politecnica de Valencia for a postdoctoral scholarship. Prof. Simona M. Coman kindly acknowledges UEFISCDI for financial support (project PN-II-PT-PCCA-2013-4-1090, Nr. 44/2014).Rizescu, C.; Podolean, I.; Cojocaru, B.; Parvulescu, VI.; Coman, SM.; Albero-Sancho, J.; García Gómez, H. (2017). RuCl3 supported on N-doped graphene as reusable catalyst for one-step glucose oxidation to succinic acid. ChemCatChem. 9(17):3314-3321. https://doi.org/10.1002/cctc.201700383S3314332191
FORMULAS AND POLYNOMIALS WHICH GENERATE PRIMES AND FERMAT PSEUDOPRIMES (COLLECTED PAPERS)
No full textThis book brings together fifty-two papers regarding primes and Fermat pseudoprimes, submitted by the author to the scientific database Research Gate. Part One of this book, “Sequences of primes and conjectures on them”, contains papers on sequences of primes, squares of primes, semiprimes, pairs, triplets and quadruplets of primes and conjectures on them. This part also contains papers on possible methods to obtain large primes, some of them based on concatenation, some of them on other arithmetical operations. It is also introduced a new notion, “Smarandache-Coman sequences of primes”, defined as “all sequences of primes obtained from the Smarandache sequences using any arithmetical operation”. Part Two of this book, “Sequences of Fermat pseudoprimes and conjecture on them”, contains sequences of Poulet and Carmichael numbers. Among these papers there is a list of thirty-six polynomials and formulas that generate sequences of Fermat pseudoprimes. Part Three of this book, “Prime producing quadratic polynomials”, contains three papers which list few already known such polynomials, that generate more than 20, 30 or even 40 primes in a row, and few such polynomials discoverd by the author himself (in a review of records in the field of prime generating polynomials, written by Dress and Landreau, two mathematicians well known for their contributions in this field, the author is mentioned with 18 prime producing quadratic polynomials). One of these three papers proposes 17 generic formulas that may generate prime producing quadratic polynomials
Covalent Graft of Lipopeptides and Peptide Dendrimers to Cellulose Fibers
No full textIntroduction: Bacterial proliferation in health environments may lead to the development of specific pathologies, but can be highly dangerous under particular conditions, such as during chemotherapy. To limit the spread of infections, it is helpful to use gauzes and clothing containing antibacterial agents. As cotton tissues are widespread in health care environments, in this contribution we report the preparation of cellulose fibers characterized by the covalent attachment of lipopeptides as possible antimicrobial agents. Aim: To covalently link peptides to cotton samples and characterize them. Peptides are expected to preserve the features of the fabrics even after repeated washing and use. Peptides are well tolerated by the human body and do not induce resistance in bacteria. Materials and Methods: A commercially available cotton tissue (specific weight of 150 g/m2, 30 Tex yarn fineness, fabric density of 270/230 threads/10 cm in the warp and weft) was washed with alkali and bleached and died. A piece of this tissue was accurately weighed, washed with methanol (MeOH) and N,N-dimethylformamide (DMF), and air-dried. Upon incubation with epibromohydrin, followed by treatment with Fmoc-NH-CH2CH2-NH2 and Fmoc removal, the peptides were synthesized by incorporating one amino acid at a time, beginning with the formation of an amide bond with the free NH2 of 1,2–diaminoethane. We also linked to the fibers a few peptide dendrimers, because the mechanism of action of these peptides often requires the formation of clusters. We prepared and characterized seven peptide-cotton samples. Results: The new peptide-cotton conjugates were characterized by means of FT-IR spectroscopy and X-ray Photoelectron Spectroscopy (XPS). This latter technique allows for discriminating among different amino acids and thus different peptide-cotton samples. Some samples maintain a pretty good whiteness degree even after peptide functionalization. Interestingly, these samples also display encouraging activities against a Gram positive strain. Conclusions: Potentially antimicrobial lipopeptides can be covalently linked to cotton fabrics, step-by-step. It is also possible to build on the cotton Lys-based dendrimers. XPS is a useful technique to discriminate among different types of nitrogen. Two samples displaying some antibacterial potency did also preserve their whiteness index
Effects of in vitro altered microflora on immunolocalization of ladderlectin and intelectin in trout intestine
No full textLectins are carbohydrate-binding proteins or glycoproteins present in all types of organisms. They serve different biological functions including the roles in the innate immune system by recognizing carbohydrates that are found on the surface of potential pathogens. Soluble lectins have been identified from the plasma and mucus of various fish species. Rainbow trout ladderlectin (RTLL) and intelectin (RTInt) are two plasma proteins implicated in innate immune surveillance and pathogen elimination based upon their ability to bind Gram-negative bacteria and chitin. The present work, by using an in vitro model, was aimed to evaluate the expression of RTLL and RTInt, as visualized by specific antibodies, in the trout intestine
exposed to distinct experimental conditions. The removed intestines were separately exposed to a mixture of the probiotic bacteria Lactobacillus rhamnosus, e Lactobacillus paracasei (group 1), a suspension of the pathogen bacteria Vibrio anguillarum (group 2), a mixture of the probiotics above, followed by the pathogens V. anguillarum (group 3). In the control group (group 4), the intestines were exposed to sterile
saline solution and TSBgs in the same conditions, as above.
Following exposure to V. anguillarum, a higher lectin reactivity was found, as compared with the controls, at the apical cell membrane of the epithelium, probably as a consequence of a stronger secretion induced by the pathogen. Consistently, the
intestinal goblet cells, which in the controls proved to be the main site of the lectin expression, in the group 2 appeared unstained and nearly devoid of their contents. An increased immunostaining was observed also within inflammatory leucocytes, club cells and SP-positive cells. Notably, in the group 3, both the immunohistochemical pattern and the Western blotting analysis indicated that exposure of intestine to
probiotics prior to V.anguillarum affects positively the RTInt expression, by reducing the pathogen-induced effect. These preliminary findings support a role for both RTLL and RTInt as putative innate defence molecules on intestinal mucosal surfaces. Further studies are required to confirm a possible involvement of probiotics in the RTInt-mediated immunomodulation.
Keywords: Trout ladderlectin, trout intelectin, probiotics, immunohistochemistry
Unprecedented Catalytic Wet Oxidation of Glucose to Succinic Acid Induced by the Addition of n-Butylamine to a Ru-III Catalyst
No full text[EN] A new pathway for the catalytic wet oxidation (CWO) of glucose is described. Employing a cationic Ru@MNP catalyst, succinic acid is obtained in unprecedently high yield (87.5%) for a >99.9% conversion of glucose, most probably through a free radical mechanism combined with catalytic didehydroxylation of vicinal diols and hydrogenation of the resulted unsaturated intermediate.The work was supported by the strategic grant POSDRU/159/1.5/S/137750, Project "Postdoctoral programme for training scientific researchers" co-financed by the European Social Foundation within the Sectorial Operational Program Human Resources Development 2007-2013. Prof. Simona Coman kindly acknowledges UEFISCDI for financial support (project PN-II-PT-PCCA-2013-4-1090, Nr. 44/2014). Also, we thank Prof. Curt Reimann for critical reading and helpful suggestions related to manuscript preparation.Podolean, I.;Rizescu, C.;Bala, C.;Rotariu, L.;Parvulescu, VI.;Coman, SM.;García Gómez, Hermenegildo (2016). Unprecedented Catalytic Wet Oxidation of Glucose to Succinic Acid Induced by the Addition of n-Butylamine to a Ru-III Catalyst. ChemSusChem. 9(17):2307-2311. https://doi.org/10.1002/cssc.201600474S23072311917Kamm, B. (2007). Production of Platform Chemicals and Synthesis Gas from Biomass. Angewandte Chemie International Edition, 46(27), 5056-5058. doi:10.1002/anie.200604514Kamm, B. (2007). Produktion von Plattformchemikalien und Synthesegas aus Biomasse. Angewandte Chemie, 119(27), 5146-5149. doi:10.1002/ange.200604514Hu, X., & Li, C.-Z. (2011). Levulinic esters from the acid-catalysed reactions of sugars and alcohols as part of a bio-refinery. Green Chemistry, 13(7), 1676. doi:10.1039/c1gc15272fAnastas, P. T., Bartlett, L. B., Kirchhoff, M. M., & Williamson, T. C. (2000). The role of catalysis in the design, development, and implementation of green chemistry. Catalysis Today, 55(1-2), 11-22. doi:10.1016/s0920-5861(99)00222-9Podolean, I., Kuncser, V., Gheorghe, N., Macovei, D., Parvulescu, V. I., & Coman, S. M. (2013). Ru-based magnetic nanoparticles (MNP) for succinic acid synthesis from levulinic acid. Green Chemistry, 15(11), 3077. doi:10.1039/c3gc41120fCorma, A., Iborra, S., & Velty, A. (2007). Chemical Routes for the Transformation of Biomass into Chemicals. Chemical Reviews, 107(6), 2411-2502. doi:10.1021/cr050989dMallat, T., Brönnimann, C., & Baiker, A. (1997). Modification of supported Pt catalysts by preadsorbed phosphines: enhanced selectivity in the oxidation ofl-sorbose. Applied Catalysis A: General, 149(1), 103-112. doi:10.1016/s0926-860x(96)00252-9Smith, A. B., & Scarborough, R. M. (1980). Ruthenium Tetroxide Oxidation of Simple Ethers: A Systematic Study. Synthetic Communications, 10(3), 205-211. doi:10.1080/00397918008064223Arceo, E., Ellman, J. A., & Bergman, R. G. (2010). Rhenium-Catalyzed Didehydroxylation of Vicinal Diols to Alkenes Using a Simple Alcohol as a Reducing Agent. Journal of the American Chemical Society, 132(33), 11408-11409. doi:10.1021/ja103436vFellay, Cã©., Dyson, P., & Laurenczy, Gã¡. (2008). A Viable Hydrogen-Storage System Based On Selective Formic Acid Decomposition with a Ruthenium Catalyst. Angewandte Chemie International Edition, 47(21), 3966-3968. doi:10.1002/anie.200800320Fellay, C., Dyson, P. J., & Laurenczy, G. (2008). A Viable Hydrogen-Storage System Based On Selective Formic Acid Decomposition with a Ruthenium Catalyst. Angewandte Chemie, 120(21), 4030-4032. doi:10.1002/ange.200800320Dowson, G. R. M., Haddow, M. F., Lee, J., Wingad, R. L., & Wass, D. F. (2013). Catalytic Conversion of Ethanol into an Advanced Biofuel: Unprecedented Selectivity forn-Butanol. Angewandte Chemie International Edition, 52(34), 9005-9008. doi:10.1002/anie.201303723Dowson, G. R. M., Haddow, M. F., Lee, J., Wingad, R. L., & Wass, D. F. (2013). Catalytic Conversion of Ethanol into an Advanced Biofuel: Unprecedented Selectivity forn-Butanol. Angewandte Chemie, 125(34), 9175-9178. doi:10.1002/ange.201303723Hamid, M. H. S. A., Allen, C. L., Lamb, G. W., Maxwell, A. C., Maytum, H. C., Watson, A. J. A., & Williams, J. M. J. (2009). Ruthenium-CatalyzedN-Alkylation of Amines and Sulfonamides Using Borrowing Hydrogen Methodology. Journal of the American Chemical Society, 131(5), 1766-1774. doi:10.1021/ja807323aImamura, S. (1999). Catalytic and Noncatalytic Wet Oxidation. Industrial & Engineering Chemistry Research, 38(5), 1743-1753. doi:10.1021/ie980576
“Do As Your Teacher Tells You!” How Is AI Use Regulated in Nordic Higher Education Institutions?
No full textThis paper explores the AI policies, frameworks, and guidelines established by Nordic universities (from Denmark, Finland, Iceland, Norway, and Sweden). The Nordic countries share characteristics such as a strong infrastructure supporting educational technology integration. The aim is to find similarities, differences, and gaps between the guidelines of Nordic universities in order to make the guidelines more practical and valuable for teachers and students. The theoretical framework focuses on guidelines and principles based on AI ethics, especially in higher education.
A content analysis was conducted on 39 documents from 12 universities. The analysis reveals two major themes in the documents: (1) Use of AI in Higher Education and (2) Ethical principles of AI in Higher Education guidelines.
Nordic universities are committed to leveraging AI responsibly while maintaining ethical, pedagogical, and institutional integrity. The results of this study give valuable insights into what kind of issues should be considered in guidelines of ethical AI in higher education and how, in addition to principles, practical examples are also needed for both teaching and learning. The results show that more research, common discussion, and collaboration are required. Additionally, the absence of societal and environmental well-being factors indicates room for continuous development of the policies.peerReviewe
The Edifying Impact of Blending Game-Based Learning with Educational Robotics: A Systematic Review of Empirical Evidence
No full textGame-based learning is an effective pedagogical approach with a demonstrated capacity to activate learner engagement, inspire motivation, and enhance the overall learning experience. The application of educational robotics has also attracted a lot of attention in recent years across educational levels and domains. Despite their appeal and the positive learning outcomes associated with such innovative pedagogies, the synergistic edifying impact of blending them remains largely unexplored. The aim of this study is to present a synthesis of empirical evidence on game-based learning and educational robotics. A systematic literature review is conducted focusing on empirical research published between 2019 and 2023. The analysis reveals prevalent methodological approaches and pedagogical theories framing learning and instruction, as well as the most widely employed robotics and gaming platforms. The study sheds light not only on the benefits of embracing game-based learning and educational robotics, but also on the barriers and challenges associated with adopting such innovative pedagogies. Ultimately, the study attempts to portray the impact of these approaches on learning and transferable skills development
Generative AI in Education:Exploring EAP Faculty Perspectives at a Multicultural UAE University
No full textThis study examines the perceptions and readiness of English for Academic Purposes (EAP) faculty at a multicultural university in the UAE to integrate Generative Artificial Intelligence (GenAI) into their teaching practices. Employing a qualitative case study approach, the research explores faculty perspectives through digital written interviews to understand the complex interplay between technological acceptance and pedagogical integration within a diverse educational setting. The findings reveal a spectrum of faculty attitudes towards GenAI, categorised into three main themes: Optimistic Integration, Cautious Acceptance, and Resistance and Scepticism. Faculty demonstrating Optimistic Integration perceive GenAI as a transformative tool that enhances educational delivery, personalises student learning, and automates routine tasks. Conversely, those with Cautious Acceptance recognise GenAI′s potential benefits but express concerns about ethical implications and the potential for technology to undermine academic integrity. The third group, exhibiting Resistance and Scepticism, focuses on the potential negative impacts of GenAI, including depersonalisation of education and loss of faculty jobs. The study underscores the need for robust faculty development programmes that address both the technological and pedagogical dimensions of GenAI. These programmes should promote understanding and skills necessary for the effective integration of GenAI, considering the institution′s multicultural and diverse linguistic backdrop. By aligning GenAI implementation with educational goals and ethical standards, the findings aim to guide policymakers, curriculum developers, and educational technology designers in fostering environments that leverage AI to enhance teaching effectiveness while respecting diverse academic needs.<br/
From Glucose Direct to Succinic Acid: an Optimized Recyclable Bi-functional Ru@MNP-MWCNT Catalyst
No full text[EN] Ru@MNP-MWCNT catalysts were obtained via functionalization of nanostructured carbon-based carriers (ie, MWCNT) with base molecules (ie, 2-aminophenol and ethylenediamine) followed by the complexation with RuCl3. These structures demonstrated a highly efficient behavior for the selective wet oxidation of levulinic acid and glucose to succinic acid. However, to ensure an easy recovery and high recyclability the MWCNTs nanotubes were modified by incorporation of super-paramagnetic Fe3O4 nanoparticles into porous structure. Besides the catalytic performances the resulted composites showed a good mechanical resistance.Authors are gratefully to Giuliana Aquilanti and Luca Olivi, Elettra Sincrotrone Trieste, S.S. 14km 163,5, Area Science Park, 34149 Basovizza-Trieste, Italy for XANES measurements. Vasile I. Parvulescu kindly acknowledges UEFISCDI for financial support (project PN-III-P4-ID-PCE-2016-0146, Nr. 121/2017Podolean, I.;Cojocaru, B.;García Gómez, Hermenegildo;Teodorescu, C.;Parvulescu, VI.;Coman, SM. (2018). From Glucose Direct to Succinic Acid: an Optimized Recyclable Bi-functional Ru@MNP-MWCNT Catalyst. Topics in Catalysis. 61(18-19):1866-1876. https://doi.org/10.1007/s11244-018-1012-4S186618766118-19Kamm B (2007) Production of platform chemicals and synthesis gas from biomass. Angew Chem Int Ed 46:5056–5058Corma A, Iborra S, Velty A (2007) Chemical routes for the transformation of biomass into chemicals. Chem Rev 107(6):2411–2502Shylesh S, Schünemann V, Thiel WR (2010) Magnetically separable nanocatalysts: bridges between homogeneous and heterogeneous catalysis. Angew Chem Int Ed 49:3428–3459McCafferty E, Wightman JP (1998) Determination of the concentration of surface hydroxyl groups on metal oxide films by a quantitative XPS method. 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Shared aperture array antennas composed of differently sized
No full textA novel solution for conceiving wide band (multi-band) array antennas is presented. The solution is based on the concept of interleaving sparse, sub-arrays operating at separate frequencies. Sparse array antennas offer two major advantages, namely: they have non-uniformly distributed elements, with possibly large distances between elements (this providing the necessary space for interleaving different sub-arrays), and they do not require the amplitude tapering of the elements for controlling the array radiation pattern.Electrical Engineering, Mathematics and Computer Scienc
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