Bibliografia

Abstract

In-situ monitoring of defects in extrusion-based bioprinting processes using visible light imaging

Tissue engineering techniques are central for the development of biomedical scaffolds, which are primarily employed in the biofabrication of various artificial human tissue and organ models. Bioprinting is a new technique of creating tissue constructs that can sustain cell proliferation. The development of printing techniques proceeds together with the development of the biomaterials to be printed, which is why studying the printability of these specific biomaterials must be explored. An appropriate hydrogel used as bioink should have numerous rheological, mechanical, and biological properties for producing appropriate tissue constructs. However, reaching the right trade-off between a desirable bioactivity and high printability is challenging, and despite numerous optimization studies for different materials, printing defects often occur during printing. Herein, methods are proposed to automatically identify these drifting processes in commonly used geometries and how they affected subsequent layers, as well as printing defects within each layer. Several structures were printed with standard commercial bioink as proof of concept. The constructs were analyzed using optical images from a coaxial camera. The images were then digitally processed to get geometrical data from which patterns of defectology to be monitored were derived. This automation should decrease the time in post-processing characterization of constructs and should provide a standardized tool to compare different bioinks

Preliminary tests on PEG-based thermoresponsive polymers for the production of 3D bioprinted constructs

In the last years, the growing demand for tissues and organs led to the development of novel techniques, such as 3D bioprinting. This technique proved to be promising for both patient-specific and custom-made applications when using autologous cells, and for the creation of standardized models that in the future could be used for instance for high-throughput drug screening. Within this context, the formulation of bioinks that could provide reliable, reproducible, and replicable structures with good mechanical properties and high biocompatibility is a crucial challenge. In this work, the use of a thermoresponsive PEG-based formulation was investigated as a bioink, allowing its use for 4D bioprinting applications triggered by thermal changes. First, the polymer was synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT), which allows for optimal control over the final properties of the polymer. Then, the printability for extrusion-based bioprinting of this formulation was assessed through in-situ imaging. Finally, the use of this polymer as bioink was tested by encapsulation of endothelial cells and evaluating cell distribution within the construct

Optogalvanic Signals From Argon Metastables In A Rf Glow-Discharge

Laser optogalvanic (LOG) signals at 667.7, 751.5, and 696.5 nm from the 3 P 1 and 3 P 2 levels of Ar were studied at a pressure of 250 mTorr in a rf glow discharge. Signals with unexpected signs and time dependences were found. The results are interpreted as being due to radiative trapping effects and collisional mixing between resonance and metastable levels. An average electron energy of 2.1 eV is derived from modeling the data

Bibliografia

Abstract

La teoria classica

Abstract

L'era di Grothendieck

Abstract

Introduzione

EnThis work is a survey on the evolution of Operator Theory from its birth up its present state.Thus,after a brief sketch of the classical theory,we examine is some detail Grothendieck's fundamental work and then show how from this the theory developed to take its modern shape through the systematic use,largely due to Pietsch,of the concept of an operator ideal.Finally.the last section is dedicated to some general open problems which are fundamental for the theory

La teoria classica

Abstract

The evaluation of tactile dysfunction in the hand in type 1 diabetes: a novel method based on haptics

Aims We present an innovative method based on haptics for the evaluation of the sense of touch in the hand, in people affected by type 1 diabetes. Methods Forty individuals affected by diabetes and 20 healthy controls took part in the study; the diabetes group was further divided into two subgroups based on vibration sensitivity in the lower limb. By means of a novel haptic device, tactile sensitivity in the fingertip was measured as the ability of the participants to discriminate slip motion speed. Results Tactile sensitivity was significantly lower in individuals affected by diabetes as compared to controls. Depending on the subgroup, the difference from the controls was equal to 0.11 (95% CI from 0.029 to 0.186) and to 0.267 (95% CI from 0.198 to 0.336). Within the diabetes group, tactile sensitivity correlated with vibration sensitivity in the upper (p = 0.001) and lower limb (p = 0.003). A significant relationship between nerve conduction parameters and tactile sensitivity was found (p = 0.03). Finally, we combined the different predictors (clinical, vibratory and electroneurography data) by using cluster analysis; tactile sensitivity was found to be significantly different between different clusters (p = 0.004). Conclusions Early signs of tactile dysfunction in the hand were found in individuals affected by diabetes, even in absence of diabetic neuropathy. The protocol presented in this study is a promising tool for the assessment of tactile dysfunction in the hand in people affected by type 1 diabetes