12,920 research outputs found
Vulnus Vb 4.0: Procedura automatica per analisi di vulnerabilità sismica di edifici in muratura
No full textAggiornamento ed estensione in Visual basic della procedura VULNUS, di Bernardini-Gori-Modena, 1988. A cura di M.R. Valluzzi, con contributi di Benincà G., Barbetta E., Munari M
L'esperienza della Fondazione Cariplo: la valorizzazione attraverso i distretti culturali
No full textThis chapter describes the implementation of an experimental program aimed at realizing cultural districts in Italy
Microcredito e Microfinanza: il Rischio di una Bolla?
No full textThe paper is a short survey on microcredit activities and microfinance institutions (MFI), that in the last few decades obtained outstanding results in the fight to poverty. The extremely positive track record has generated high expectations on two different sides: the first related to the sustainability of this business; the second related to the exportability of this business to advanced economies, in order to fight the increasing social exclusion. We argue that both statements can be easily criticized, since most microcredit activities and MFI are still not sustainable; moreover several elements limit the exportability of this peculiar business model to risch countries
Lo schizofrenico della famiglia. Un saggio su Bateson e Foucault
No full textVolume convegno su Gregory Bateson. Il volume è a cura di Marco Bianciardi e Paolo Bertrando, il nome di Marco Bianciardi non è stato inserito perché veniva stranamente rifiutato dal programma inserimento dati
6 - Gas foaming technologies for 3D scaffold engineering
No full textThe effect of scaffold pore size and interconnectivity as well as porosity are undoubtedly crucial factors for most tissue engineering applications. This premise is the basis of worldwide efforts that have been spent to develop increasingly sophisticate fabrication techniques to control the scaffold microarchitecture and build efficient synthetic analogues of extracellular matrix. Among the plethora of techniques developed for this purpose, gas-in-liquid foam templating has emerged as one that conjugates simplicity of the technology involved, use of inert gases as the templating phase (thus avoiding the use of potentially toxic organic solvents), employment of a large variety of biocompatible and often bioactive biopolymers, and obtainment of highly porous and interconnected scaffolds. Experience gained in cell culturing pointed out the main limits of gas-foamed scaffolds, that is the polydispersed nature of both pores and interconnects dimension that cause an uneven distribution of seeded cells within the enclosed 3D space. The awareness of such a limit and increasing demands of more reliable in vitro cellular models stimulated researchers to exploit the potentials offered by microfluidics in the generation of monodisperse gas-in-liquid foam templates. Foam templating through microfluidics gives the opportunity to finely tune the porous texture of the scaffolds, i.e., the dimension of pores and interconnect, eventually independently one from the other, thus responding to the morphological requirements posed by a particular cell type. © 2018 Elsevier Ltd. All rights reserved
Low Viscous Bioinks for Extrusion-Based 3D Bioprinting
No full text3D bioprinting is an emerging field that can be described as a robotic additive biofabrication technology that has the potential to build tissues or organs. In general, bioprinting uses a computer controlled printing device to accurately deposit cells and biomaterials into precise architectures with the goal of creating on demand organized multicellular tissue structures and eventually intra-organ vascular networks. Progress in bioprinting have been following two interdependent pathways:
1. development of more precise and versatile bioink deposition techniques;
2. development of bioinks that provide a growth and function-supportive medium to the cells and promote their proper organization and function while minimizing the effect of printing on cell viability and without compromising printing fidelity and stability of the construct.
Many bioinks have been formulated for various cells types, but those currently used for 3D printing still have challenges and limitations, mainly low cell viability during printing and limited resolution.
To overcome these limitations, we developed a new concept of extrusion-based bioprinting technique, which implements a microfluidic control in the dispensation of the bioink. The coupling of microfluidic platforms with the dispensing system is made possible by the use of a coaxial extrusion head that induces the solidification of the bioink in the form of a hydrogel simultaneously to its deposition.
In particular, among other components, the bioink contains alginate, whose gelation is induced by exposing it to a crosslinking solution containing calcium ions. The bioink and the crosslinking solution are delivered respectively through the internal and external needles of a coaxial-needles system. At the ending tip of the dispensing head the two solutions meet causing the immediate solidification of the bioink due to the ionic crosslinking of alginate. In this way, it is possible to deposit hydrogel fibers with dimensions ranging between 150 and 300 μm. The printing conditions described above are mild since bioink viscosity is low and crosslinking conditions can be tuned to be harmless toward encapsulated cells.3D bioprinting is an emerging field that can be described as a robotic additive biofabrication technology that has the potential to build tissues or organs. In general, bioprinting uses a computer controlled printing device to accurately deposit cells and biomaterials into precise architectures with the goal of creating on demand organized multicellular tissue structures and eventually intra-organ vascular networks. Progress in bioprinting have been following two interdependent pathways:
1. development of more precise and versatile bioink deposition techniques;
2. development of bioinks that provide a growth and function-supportive medium to the cells and promote their proper organization and function while minimizing the effect of printing on cell viability and without compromising printing fidelity and stability of the construct.
Many bioinks have been formulated for various cells types, but those currently used for 3D printing still have challenges and limitations, mainly low cell viability during printing and limited resolution.
To overcome these limitations, we developed a new concept of extrusion-based bioprinting technique, which implements a microfluidic control in the dispensation of the bioink. The coupling of microfluidic platforms with the dispensing system is made possible by the use of a coaxial extrusion head that induces the solidification of the bioink in the form of a hydrogel simultaneously to its deposition.
In particular, among other components, the bioink contains alginate, whose gelation is induced by exposing it to a crosslinking solution containing calcium ions. The bioink and the crosslinking solution are delivered respectively through the internal and external needles of a coaxial-needles system. At the ending tip of the dispensing head the two solutions meet causing the immediate solidification of the bioink due to the ionic crosslinking of alginate. In this way, it is possible to deposit hydrogel fibers with dimensions ranging between 150 and 300 μm. The printing conditions described above are mild since bioink viscosity is low and crosslinking conditions can be tuned to be harmless toward encapsulated cells
Nuovo metodo di stampa 3D di bioinks a bassa viscosità
No full texttecnologia che nell’ambito di quella branca della scienza e tecnologia nota come ingegneria tissutale (TE) si sta imponendo in misura crescente grazie alla potenzialità che offre di replicare la complessità isto-morfologica dei tessuti umani. Il bioprinting rappresenta l’aspetto più moderno delle tecnologie di prototipazione rapida (RP) applicate al TE. Il RP in generale prevede la progettazione dell’oggetto da replicare al computer utilizzando software dedicati e la generazione di un file di istruzioni che viene tradotto nell’oggetto reale attraverso la macchina di prototipazione, strato dopo strato. Lo sviluppo di questa tecnologia sta attualmente seguendo due direttrici strettamente correlate tra di loro: lo sviluppo di nuove tecniche di deposizione che consentano la stampa di nuovi bioink con elevata risoluzione; lo sviluppo di nuovi bioinks che forniscano un mezzo adeguato per l’adesione e proliferazione delle cellule incapsulate e ne promuovano la loro organizzazione tridimensionale minimizzando al tempo stesso gli effetti negativi del processo di stampa sulla sopravvivenza delle cellule.
Molti bioinks sono stati formulati per i vari fenotipi cellulari, ma quelli che sono in uso corrente nella stampa 3D soffrono di bassa risoluzione e garantiscono solo un basso grado di sopravvivenza cellulare spesso a causa della loro elevata viscosità. Per ovviare a questi limiti, recentemente abbiamo sviluppato una nuova tecnologia di estrusione di bioinks caratterizzati da una bassa viscosità ed elevata bioattività. Il dispositivo di deposizione consiste nell’accoppiamento di un sistema microfluidico con un estrusore costituito da due aghi coassiali che consente la manipolazione spazio-temporale del bioink usato e la sua solidificazione sotto forma di un gel contestualmente alla sua deposizione. Il componente essenziale del bioink alla base di questa tecnica di deposizione è rappresentato dall’alginato la cui gelazione è indotta dalla presenza di ioni calcio. In particolare, il bioink contenente alginato, cellule ed altri biopolimeri viene estruso attraverso l’ago interno del sistema di agi coassiali mente la soluzione contenente ioni calcio attraverso quella esterno. Quando le due soluzioni si incontrano all’estremità del sistema di aghi coassiali il bioink gela istantaneamente permettendo la deposizione di una fibra di gel del diametro compreso tra i 150 e 300 mm contenente le cellule. Questa tecnologia è stata applicata con successo nella stampa di strutture simile ai vasi sanguigni, tessuto cartilagineo e muscolare liscio
Small airways dysfunction: is there any involvement in patients with atopy?
No full textatopy and asthm
Polysaccharide based scaffolds obtained by freezing the external phase of gas-in-liquid foams
No full textIn this article it is demonstrated how the combination of a novel gas-in-liquid-templating method followed by foam freezing in liquid nitrogen can be exploited for the synthesis of polysaccharide based porous materials endowed with characteristics particularly suited for tissue engineering applications. The model polysaccharides taken into consideration for illustrating this new approach to scaffolds synthesis are hyaluronic acid, chitosan, and alginate vastly used in biomedical applications. In practice, the method consists of preparing a concentrated solution of a polysaccharide and employing it as the continuous phase of a gas-in-water foam stabilized by a proper surfactant. In order to bypass the inherently low kinetic stability of such foams they were frozen immediately after their formation in liquid nitrogen. Afterwards, they were cross-linked in order to preserve the scaffold structure in an aqueous environment typical of cell culture. Scaffolds are characterized by an excellent, interconnected morphology consisting of voids of a few hundreds of mm in dimension and present on scaffold walls a fine, directional porous or fibrillar sub-structure derived from the freezing process which should be beneficial for cell attachments
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