2,863 research outputs found
Calculation of the electric field in GaAs particle detectors
No full textIn this work a numerical approach has been used to investigate some properties of semi-insulating GaAs detectors. In particular the electric field has been obtained by solving transport and Poisson equations. A comparison with the results obtained in a previous work by another group has been carried out
Designing novel hybrid hydrogel scaffolds for driving the fate of human cardiac MSC
No full textThe design of appropriate scaffolds remains one of the most important challenges for regenerative medicine. Current idea is that the interaction between stem cells and scaffold could drive cell fate by regulating gene expression and protein organization. In this study, the combination of biochemical and mechanical properties was optimized in order to produce novel 3D protein hydrogels able to favors cell-structure interactions, cell alignment and to promote differentiation of human cardiac mesenchymal stem cells (cMSCs). Firstly, novel injectable hybrid hydrogels (PSFHy) were produced by combining the bio-functionality of silk fibroin protein with the structural versatility of poly(ethylene glycol) diacrylate. Functionalization of the 3D-PSFHy with protein microspheres was required to increase the porosity and cell-adhesive properties of the material. MSembedding PSFHy were able to sustain a good viability of cMSCs – far beyond what reported for unfunctionalized hydrogels – and cMSCs exhibited the expression of proteins that are characteristic of the initial phases of cardiac muscle differentiation process. A cell-preconditioning of the scaffold was also performed, suggesting a potential application of these sponge-like hydrogels for analysing the effects of several extracellular microenvironments, produced by different kinds of cells, on the stem cells fate. In the context of 3D-bioprinting developments, novel 3D Scaffold-in-scaffold were designed revealing able to provide a multitextured 3D environment to the cells and to guide cMSCs alignment and promote their differentiation inducing the development of a cardiac phenotype. Finally, a novel formulation of diallyl disulfide (DADS) and αlinolenic acid (ALA) as protein nanoemulsions (BAD-NEs) was produced. BAD-NEs ability to release the bioactive molecule H2S, their antioxidant and radical scavenging property and their effects in stimulating cMSCs growth were demonstrated. Studies aimed at limiting hydrogel photopolymerization damage on embedded cells – among others in 3Dbioprinting technologies – were carried out and to this purpose cMSCs pretreatment with BAD-NEs was proven effective
Photo-Polymerization Damage Protection by Hydrogen Sulfide Donors for 3D-Cell Culture Systems Optimization
No full textPhoto-polymerized hydrogels are ideally suited for stem-cell based tissue regeneration and three dimensional (3D) bioprinting because they can be highly biocompatible, injectable, easy to use, and their mechanical and physical properties can be controlled. However, photo-polymerization involves the use of potentially toxic photo-initiators, exposure to ultraviolet light radiation, formation of free radicals that trigger the cross-linking reaction, and other events whose effects on cells are not yet fully understood. The purpose of this study was to examine the effects of hydrogen sulfide (H2S) in mitigating cellular toxicity of photo-polymerization caused to resident cells during the process of hydrogel formation. H2S, which is the latest discovered member of the gasotransmitter family of gaseous signalling molecules, has a number of established beneficial properties, including cell protection from oxidative damage both directly (by acting as a scavenger molecule) and indirectly (by inducing the expression of anti-oxidant proteins in the cell). Cells were exposed to slow release H2S treatment using pre-conditioning with glutathione-conjugated-garlic extract in order to mitigate toxicity during the photo-polymerization process of hydrogel formation. The protective effects of the H2S treatment were evaluated in both an enzymatic model and a 3D cell culture system using cell viability as a quantitative indicator. The protective effect of H2S treatment of cells is a promising approach to enhance cell survival in tissue engineering applications requiring photo-polymerized hydrogel scaffolds
Survival kinase-dependent pathways contribute to gender difference in the response to myocardial ischemia–reperfusion and ischemic post-conditioning
No full textThe response to ischemia/reperfusion and the effects of ischemic post-conditioning (IPC) are sex-dependent, but the mechanisms have not been clarified. Male (M) and female (F) rat hearts isolated and perfused using the Langendorff technique were subject to 30 min of global ischemia (GI) and 60 min reperfusion (R). In IPC hearts, three cycles of 30-sec GI/30-sec R were applied at the beginning of R. Infarct size and myocardial function were assessed. Superoxide production, antioxidant systems, and expressions of phosphorylated forms of serine/threonine kinase (Akt), glycogen synthase kinase 3β (GSK-3β), protein kinase C ε (PKCε), endothelial nitric oxide synthase (eNOS), and apoptosis were measured. In the basal state, superoxide production and apoptosis were lower, and antioxidant systems and phospho-kinase expressions were higher in F rather than in M hearts. After ischemia–reperfusion, infarct size was less in F hearts, and post-ischemic recovery of myocardial function was higher in F rather than in M hearts. Superoxide production, phospho-kinase activity, phospho-eNOS, and apoptosis increased in both sexes while antioxidants decreased in both sexes. After IPC, infarct size, superoxide production, and apoptosis decreased and phospho-eNOS increased in F and M hearts but phospho-kinase expressions and post-ischemic recovery of myocardial function improved only in M hearts. These results show that Akt/GSK-3β/PKCε/eNOS-dependent pathways-mediated superoxide production and apoptosis appear as important factors involved in the observed gender differences.Fil: Ciocci Pardo, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani". Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani"; ArgentinaFil: Scuriatti, Luis Emiliano. Universidad Nacional de La Plata. Facultad de Ciencias Médicas; ArgentinaFil: González Arbeláez LF. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani". Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani"; ArgentinaFil: Caldiz, CI. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani". Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani"; ArgentinaFil: Fantinelli JC. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani". Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani"; ArgentinaFil: Mosca SM. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani". Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Centro de Investigaciones Cardiovasculares "Dr. Horacio Eugenio Cingolani"; Argentin
A study of the electrical and charge-collection properties of semi-insulating GaAs detectors
No full textIn this work a numerical approach has been used to investigate some properties of semi-insulating GaAs detectors. In particular, the electric field and the carriers mean free path distributions have been obtained, by solving transport and Poisson equations. The knowledge of these quantities allows us to determine the charge-collection efficiency and other detector characteristics. A comparison with the experimental results of X-ray irradiated detectors of different thicknesses has been carried out
Injectable silk fibroin hydrogels functionalized with microspheres as adult stem cells-carrier systems
No full textHydrogels are good candidate materials for cell delivery scaffolds because they can mimic the physical, chemical, electrical and biological properties of most of the native tissues. In this study, composite biosynthetic hydrogels were produced by combining the bio-functionality of silk fibroin (SF) with the structural versatility of polyethylene-glycol-diacrylated (PEGDa). The formation of a photopolymerizable PEGDa-SF hydrogel (PSFHy) was optimized for 3D-cell culture. Functionalization of the 3D-PSFHy with protein microspheres (MS) was required to increase the porosity and cell-adhesive properties of the material. Cardiac mesenchymal stem cells, which were cultured within the MS-embedding PSFHy, exhibited good viability and expression of proteins that are characteristic of the initial phases of the cardiac muscle differentiation process. Further, the addition of chondroitin sulfate into the scaffolds improved the cell viability. A cell-preconditioning of the scaffold was also performed, suggesting a potential application of these sponge-like scaffolds for analysing the effects of several extracellular microenvironments, produced by different kinds of cells, on the stem cells fate. The results presented herein highlight on the possibility to use the PSFHys functionalized with MS as stem cell-carrier systems with sponge-like properties, potential ultrasound-imaging contrast agents and controlled biochemical factor delivery
Biblioteche e AI Literacy: alcune riflessioni sulle nuove competenze per la mediazione informativa
No full textIl tradizionale ruolo di mediazione informativa svolto dai/dalle bibliotecari/bibliotecarie, si arricchisce oggi di nuovi
contenuti che riguardano la divulgazione della conoscenza sull’uso il più possibile esperto degli strumenti basati
sull’intelligenza artificiale generativa. Questa nuova tecnologia, infatti, lungi da escludere i mediatori informativi,
quali sono i/le bibliotecari/e, e aggravare definitivamente le conseguenze del fenomeno della disintermediazione,
che ha caratterizzato questi decenni e ha messo in crisi la professione bibliotecaria, soprattutto nelle aree STEM e
Bio-Medical, può rappresentare un elemento di “riscatto” nei termini dell’evoluzione della professione verso una
dimensione spiccatamente divulgativa. A nostro avviso non esiste, o quasi, categoria professionale più adatta a
sanare i grandi vuoti di competenza e di conoscenza di un fenomeno così complesso, ma nello stesso tempo così
pervasivo come la diffusione dei tools di intelligenza artificiale, soprattutto nell’ambito frequentato dai/lle bibliotecari/
e, cioè l’informazione. Pensiamo a quanto possa essere utile “guidare” i ricercatori attraverso strumenti
che permettano loro di affidare all’AI gli aspetti più compilativi della loro attività di studio e ricerca, e permettere
loro di concentrarsi solo sugli aspetti speculativi e creativi, anche grazie ai suggerimenti delle macchine intelligenti.
E questo facendo solo il nostro consueto lavoro di fact checking e di verifica delle fonti informative, indipendentemente
dal contesto bibliotecario in cui ci si trovi a operare, oltre che dei contenuti proposti dall’AI che
possono essere falsati da bias e/o allucinazioni (che comunque dipendono sempre dall’interazione con gli umani).
La conoscenza dei tools - di cui ragioniamo nell’ultima parte di questo lavoro per dare concretezza ad un tema che
altrimenti rischia di essere troppo astratto per le nostre comunità di riferimento - si affianca così alla tradizionale
information literacy, una competenza che si pratica nelle nostre biblioteche e che trova così nuovi spunti per
aggiornarsi e continuare ad essere di supporto alla crescita informativa e intellettuale dei nostri utenti, per una
partecipazione sempre più consapevole ed esperta alla vita del XXI secolo
Interdisciplinary rehabilitation of a root-fractured maxillary central incisor: A 12-year follow-up case report
No full textSingle-tooth implantation has become a common treatment solution for replacement of a root-fractured maxillary incisor in adults, but the long-term esthetic results can be unfavorable due to progressive marginal bone loss, resulting in gingival recession. In this case report, a maxillary central incisor with a root fracture in its apical one-third was orthodontically extruded and extracted in a 21-year-old female. Implant surgery was performed after a 3-month healing period, and the final crown was placed about 12 months after extraction. After 12 years, favorable osseous and gingival architectures were visible with adequate bone height and thickness at the buccal cortical plate, and no gingival recession was seen around the implant-supported crown. Although modern dentistry has been shifting toward simplified, clinical procedures and shorter treatment times, both general dentists and orthodontists should be aware of the possible long-term esthetic advantages of orthodontic extrusion of hopelessly fractured teeth for highly esthetically demanding areas and should educate and motivate patients regarding the choice of this treatment solution, if necessary
Seeded free electron laser operating with two colors: Comments on experimental results
No full textFree electron lasers operating with two colors are promising devices for applications. The relevant modelization has provided a good understanding of the underlying physics. In this paper we present an analysis of the experimental results obtained at SPARC-LAB concerning seeded two-colors free electron laser (FEL) operation. The use of an ad hoc developed semi-analytical model based on the small-signal FEL integral equation reproduces most of the observed phenomenology. The paper discusses the reliability of the proposed method, the range of validity and its possible improvement. © 2016, American Physical Society. All rights reserved
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