1,720,987 research outputs found
STRATEGIE TERAPEUTICHE INNOVATIVE DI RIGENERAZIONE IN OFTALMOLOGIA VETERINARIA E COMPARATA
No full textThis veterinary research project focuses on developing innovative techniques for tissue regeneration, particularly in ophthalmology, with an emphasis on corneal tissue repair. The cornea is highly resistant to microbial invasion due to the ocular surface's complex structure and the antimicrobial peptides in the tear film. However, when this barrier is compromised (e.g., by trauma or infection), pathogens can invade, leading to conditions like corneal ulcers.
Collagenolytic corneal ulcers are a serious condition that can result in vision loss or blindness and are typically treated with medical therapy or keratoplasty. However, the growing problem of bacterial resistance limits the effectiveness of antibiotics. Therefore, there is ongoing research into alternative therapies, including regenerative approaches that stimulate tissue repair and reduce microbial load.
One such therapy is corneal cross-linking, which uses UVA light and riboflavin to strengthen the cornea and reduce liquefaction in collagenolytic ulcers. Another promising approach is plasma medicine, which uses low-frequency, low-temperature ionized gases (such as helium) to disinfect tissues and promote healing. Cold plasmas have been shown to reduce bacterial loads and enhance tissue repair without causing significant damage to cells.
This study aimed to evaluate the effects of helium plasma on the mechanical properties of pig corneas (ex vivo), comparing the results with those of corneas treated with cross-linking. The study found that helium plasma treatment significantly improved the viscoelasticity of the corneas, restoring damaged tissue to a state similar to healthy tissue, even after just 2 minutes of exposure. This suggests that helium plasma may be a more effective treatment than cross-linking for strengthening the cornea and reducing collagenolytic damage.
The findings support helium plasma treatment as a promising new regenerative therapy for collagenolytic corneal ulcers and provide a foundation for further studies to correlate mechanical and histological changes in corneal tissue after treatment
Tunable nanosystems for sensing and catalysis
Full text linkAu NP have emerged as versatile scaffolds for applications in sensing and catalysis due to their unique features such as high stability, biocompatibility, ease of preparation, size- and shape-dependent optical and electronic properties and high surface area to volume ratio. The surface of Au NP can be readily modified with ligands containing functional groups such as thiols, phosphines and amines, which exhibit strong affinity for gold surfaces. The cooperative and collective effects achieved by the organization of organic components on the particle provide all the characteristics of a multivalent surface. Multivalent interactions on the monolayer surface can, hence, be applied to strengthen an interaction between the surface and small molecules. In particular, the self-assembly of small molecules on the multivalent surface of Au NP permits the realization of dynamic complex chemical systems that can be applied in the fields of catalysis, sensing and for the creation of tunable materials.
In the first part of this Thesis, the catalytic abilities of mixed monolayer gold nanoparticles composed of 8-trimethylammonium-octanethiol and different length thiols bearing the 4'-methyl-2,2'-bipyridine•Cu2+ complex has been studied. In particular, the influence of the geometry of the mixed monolayer gold nanoparticles on the efficiency and selectivity of the Diels-Alder reaction between cinnamoyl-1-methyl-1H-imidazole and cyclopentadiene has been studied. At the same time, the effect of the chiral environment obtained through the self-assembly of chiral peptide (Ac-(LLLL)-Leu-Leu-Gly-Trp-Ser(PO3H2)) on the enantioselection was evaluated. The results indicated in one case the formation of additional products. This can be justified considering the steric interactions between the alkyl chains and the catalysts when the catalytic headgroup is level with the monolayer surface. Furthermore, it was demonstrated that the self-assembly of a chiral enviroment on the surface of the Au NP can induce enantioselectivity, although only modestly.
In the second part of the thesis, a modular indicator-displacement-assay is presented. Small molecules with biological relevance are selectively recognized under competitive conditions by using Au NP functionalized with thiols terminating with 1,4,7-triazacyclononane (TACN)•Zn2+. The assay relies on the change in affinity of macrocyclic receptors, such as cavitands, cyclodextrins or calixarenes, for monolayer protected gold nanoparticles upon complexation of the respective target analyte. This change affects the equilibrium between the nanoparticles and a fluorescent reporter molecule leading towards a change in intensity of the fluorescent output signal. The recognition modules can be changed in order to tune the selectivity of the assay without affecting the nature of the output signal. The combined use of recognition modules results in an assay able to detect multiple analytes simultaneously and with high selectivity. A study of the orthogonality of the different receptor-analyte couples led to the demonstration of the possible exploitation of these kinds of arrays within the context of molecular computing.
In the third part, the possibility to self-assemble the molecular switch 4-(phenylazo)benzoic acid on the surface of Au NP functionalized with thiols terminating with 1,4,7-triazacyclononane (TACN)•Zn2+ was studied in order to reversibly modulate by light, the affinity of small molecules for the surface. The displacement studies of both probes 343Coumarin-GDDD and 6,8-dihydroxy-1,3-pyrenedisulfonic acid by cis/trans 4-(phenylazo)benzoic acid revealed that the two isomers have different affinities for the surface.This key point was then exploited to use light for the reversible up- and downregulation of the catalytic activity of the nanoparticle under investigation.L’ importanza delle Au NP come supporto versatile per applicazioni nell’ambito della catalisi e dei sensori nasce dalle loro esclusive caratteristiche come, ad esempio, alta stabilità, biocompatibilità, facilità di preparazione, specifiche proprietà ottiche and elettroniche dipendenti dalla forma e dalle dimensioni e dal loro alto rapporto area/volume. Inoltre, la superficie delle Au NP può essere facilmente funzionalizzata mediante leganti contenenti vari gruppi funzionali, come tioli, fosfine e ammine che presentano alta affinità per la superficie d’oro.
Gli effetti collettivi e cooperativi ottenuti grazie all’organizzazione di componenti organici sulla particella, fornisce multivalenza alla superficie. Le interazioni multivalenti sul monostrato possono, quindi, essere applicate per rafforzare un’interazione tra la superficie funzionalizzata e piccole molecole. In particolare l’auto assemblaggio di piccole molecole su una superficie multivalente permette la realizzazione di sistemi chimici dinamici che possono essere applicati nel campo della catalisi, dei sensori e per la creazione di sistemi regolabili.
Nella prima parte della Tesi, viene studiata la capacità catalitica di nanoparticelle composte da un monostrato misto (in particolare composte da 8-trimetilammonio-octiltiolo e tioli di diversa lunghezza contenenti il complesso metallico 4’-metil-2,2’-bipiridina•Cu2+ . In particolare viene studiata l’influenza della geometria indotta dal monostrato misto sulla efficienza e selettività della reazione di Diels-Alder tra cinnamoil-1-metil-1H- imidazolo e il ciclopentadiene.
Allo stesso tempo, viene studiato l’effetto dell’ambiente chirale ottenuto grazie all’autoassemblaggio di un peptide chirale (Ac-(LLLL)-Leu-Leu-Gly-Trp-Ser(PO3H2)) sulla enantioselettività della reazione.
I risultati dimostrano che in alcuni casi la geometria può influenzare la formazione di prodotti addizionali. Questo può essere giustificato come il risultato di interazioni steriche tra catene alchiliche e catalizzatore, quando quest’ultimo si trova alla pari della superficie del monostrato. Inoltre, è stato dimostrato che, assemblando un peptide chirale sulla superficie delle Au NP, è possibile indurre enantioselettività, sebbene limitata.
Nella seconda parte della Tesi viene presentato un saggio modulare basato sullo spiazzamento di un indicatore. Piccole molecole con rilevanza biologica sono selettivamente riconosciute utilizzando Au NP funzionalizzate con tioli che presentano come gruppo terminale il 1,4,7-triazaciclononano (TACN)•Zn2+. Il saggio si basa sul cambio di affinità di recettori macrociclici come, ad esempio cavitandi, ciclodestrine o calixareni, per le nanoparticelle, dopo avere formato il complesso con la loro rispettiva molecola bersaglio. Questo cambio influenza l’equilibrio tra nanoparticelle e una sonda fluorescente e provoca, di conseguenza, un cambio nel segnale di fluorescenza. I moduli di riconoscimento possono essere cambiati in modo da poter controllare la selettività del saggio senza influenzare la natura del segnale in uscita. L’ utilizzo contemporaneo di tre moduli permette di creare un sistema capace di rivelare più analiti simultaneamente e con alta selettività. Lo studio dell’ortogonalità delle differenti coppie recettore/analita permette di dimostrare la possibilità di utilizzo di questo tipo di sistemi nel campo dei computer molecolari.
Nella terza parte viene studiata la possibilità di auto assemblare l’interruttore molecolare acido 4-(fenilazo)benzoico sulla superficie di Au NP funzionalizzate con tioli che presentano come gruppo terminale il
1,4,7-triazaciclononano (TACN)•Zn2+, con lo scopo di modulare con la luce (in modo reversibile) l’affinità di piccole molecole per la superficie. Gli studi di spiazzamento di entrambi i probe cumarina343-GDDD e l’acido 6,8-diidrossi-1,3-pirenedisulfonico promosso dal cis/trans acido 4-(fenilazo)benzoico rivelano che i due isomeri hanno diverse affinità per la superficie delle nanoparticelle. Questo punto chiave viene sfruttato per permettere la regolazione tramite luce dell’attività delle nanoparticelle in esame
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Orthogonal Sensing of Small Molecules Using a Modular Nanoparticle-Based Assay
No full textHerein, we present a modular indicator-displacement assay able to selectively recognize small molecules with biological relevance under competitive conditions. The assay relies on the change in affinity of macrocyclic receptors, such as cavitands, cyclodextrins or calixarenes, for monolayer-protected gold nanoparticles upon complexation of the respective target analyte. This change affects the equilibrium between the nanoparticles and a fluorescent reporter leading to a change in intensity of the fluorescent output signal. The recognition modules can be changed in order to tune the selectivity of the assay without affecting the nature of the output signal. The combined use of recognition modules results in an assay able to detect multiple analytes simultaneously with high selectivity
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