Self-assembling peptide-enriched electrospun polycaprolactone scaffolds promote the h-osteoblast adhesion and modulate differentiation-associated gene expression

Electrospun polycaprolactone (PCL) is able to support the adhesion and growth of h-osteoblasts and to delay their degradation rate to a greater extent with respect to other polyesters. The drawbacks linked to its employment in regenerative medicine arise fromits hydrophobic nature and the lack of biochemical signals linked to it. This work reports on the attempt to add five different self-assembling (SA) peptides to PCL solutions before electrospinning. The hybrid scaffolds obtained had regular fibers (SEM analysis) whose diameters were similar to those of the extracellularmatrix, more stable hydrophilic (contact angle measurement) surfaces, and anamorphous phase constrained by peptides (DSC analysis). They appeared to have a notable capacity to promote the h-osteoblast adhesion and differentiation process by increasing the gene expression of alkaline phosphatase, bone sialoprotein, and osteopontin. Adding an Arg-Gly-Asp (RGD) motif to a self-assembling sequence was found to enhance cell adhesion, while the same motif condensed with a scrambled sequence did not, indicating that there is a cooperative effect between RGD and 3D architecture created by the self-assembling peptides. The study demonstrates that self-assembling peptide scaffolds are still able to promote beneficial effects on h-osteoblasts even after they have been included in electrospun polycaprolactone. The possibility of linking biochemical messages to self-assembling peptides could lead the way to a 3D decoration of fibrous scaffolds

Stress, Overstress and Strain on AlGaN/GaN HEMT Devices

Defence radar and wireless communication systems have a drastic need for increased rf performance for high power, high efficiency, high linearity and low-cost monolithic amplifiers operating in the 1-40 GHz frequency range. Semiconductor devices based on Silicon (Si) or Gallium Arsenide (GaAs) are currently used for the fabrication of communication systems but they are not able to deal with the continuous increase in demand for microwave power performances: those devices are very close to their limit, working with a poor efficiency and requiring large cooling systems. Therefore Gallium nitride-based devices are becoming extremely attractive for a wide range of applications, from optoelectronics to power electronics. In particular, High Electron Mobility Transistors (HEMT) are emerging as a key technology for rf and microwave amplifiers, but their stability and reliability is still one of the main issue that has to be solved in order to achieve production level quality devices.I sistemi di comunicazione di ultima generazione, basati su amplificatori che operano a frequenze tra gli 1 ed i 40 GHz, necessitano di prestazioni rf sempre più spinte per quel che riguarda la potenza, l’efficienza, la linearità ed il basso costo. I semiconduttori basati sul Silicio (Si) o sull’ Arseniuro di Gallio (GaAs) che sono abitualmente utilizzati per la costruzione di sistemi di comunicazione non sono in grado di soddisfare la domanda continua e crescente di prestazioni di potenza alle microonde. Questo tipo di dispositivi sono vicini al limite delle proprie prestazioni, lavorano con bassa efficienza e richiedono sistemi di raffreddamento di grandi dimensioni. I dispositivi basati su Nitruro di Gallio stanno quindi diventando interessanti per un gran numero di applicazioni: dalla optoelettronica all’ elettronica di potenza. In particolare i transistor ad alta mobilità elettronica (HEMT) si sono rivelati promettenti per gli amplificatori a microonde ma la loro stabilità e affidabilità sono ancora uno dei problemi da risolvere per ottenere un prodotto commercializzabile e pronto per il mercato

ESD Robustness of AlGaN/GaN HEMT Devices

We have investigated the robustness of GaN-HEMT devices submitted to ESD events in different configurations. A good scaling of the failure current with the device width has been observed for both drain and gate TLP stresses. We have identified two failure mechanisms, related to the gate-source diode degradation and drain to gate filaments formation. Filaments formation was identified by means of emission microscopy, both while applying DC bias and during the TLP measurement itself. We have also found that the traditional TLP leakage measurement can not be used as a valid failure criterion. On the contrary, the gate-source diode measurement can provide interesting information on the device life-state

Financial Decision-Making in Neurological Patients

Financial abilities (FA) are a multi-dimensional domain comprising a wide range of conceptual, pragmatical, and judgmental skills ranging from basic abilities, such as bill payment, to high level abilities, such as financial decision-making (FDM). Preserved FDM abilities include the capacity to recognize fraud attempts, and they are fundamental for a person’s independence. Previous studies have reported decreased FDM in older adults and in patients with mild cognitive impairment (MCI), who consequently become more susceptible to fraud attempts. However, FDM has scarcely been investigated in other neurological populations, and it is unclear whether FDM may be predicted by more basic FA. The aim of the present study was to investigate FDM across patients with MCI, Parkinson’s disease (PD), or stroke, as well as healthy controls (HC), and to explore to what extent FDM could be inferred by other FA. We collected FDM and FA performances using the NADL-F short battery. Performances in the NADL-F short subtests were compared among groups. Additionally, the relationship between the scores at the FDM subtest and the performance obtained in other financial subtests of the NADL-F short were investigated for each group of participants. MCI patients performed worse than HC in FDM and in several FA domains. Conversely, FDM was relatively preserved in our sample of PD and stroke patients. In HC, FDM was associated with numeracy and financial knowledge applied to everyday situations, whereas this was true with some basic FA in both MCI and PD patients. No significant association was observed in stroke patients. Our results suggest that FDM is a complex ability, only partially inferable from other FA

Dataset related to article "Financial Decision-Making in Neurological Patients"

Il dataset contiene i seguenti dati: colonna B: gruppo di appartenenza di ciascun soggetto (controllo vs diagnosi di malattie neurologiche specifiche); colonne C, D, E: i dati sociodemografici dei partecipanti, riportati nell’articolo in Tabella 1; colonna F: punteggi al test MMSE corretti secondo i dati normativi, riportati in tabella 1; colonne dalla G alla M: punteggi ottenuti nei vari domini del test NADL-F short, utilizzati per le analisi riportate nelle tabella 2, 3 e 4

Investigation on charge trapping phenomena leading to kink effect on AlGaN/GaN HEMTs

We have carried out DC and transient measurements in order to investigate the kink effect in AlGaN/GaN HEMTs. A correlation between kink and threshold voltage shift has been found. Kink is possible due to negative charge build-up, taking place at low VDS values followed by negative charge detrapping or compensation, occurring for high VDS values. Dynamic measurements strongly suggests carrier trapping and detrapping as possible explanation. Photo-stimulated measurements have been also carried out in order to verify whether charge build-up and removal were due to trapping/detrapping mechanisms

Biomimetic Peptide-Enriched Electrospun Polymers: A Photoelectron and Infrared Spectroscopy Study

Biomimetic polymer nanofibers of poly(ε-caprolactone) and poly(L-lactide–caprolactone) copolymer were prepared by electrospinning. Modifications of the polymer nanofibers aimed at improving their biomimetic properties were performed by two different routes: (1) immobilization of an adhesion peptide, which mimicked the adhesion sequence of the extracellular matrix protein fibronectin, on the polymer surface and (2) incorporation of self-complementary oligopeptides, which showed alternated hydrophilic and hydrophobic side chain groups and was capable of generating extended ordered structures by self-assembling, into the polymer nanofibers. The structure of the polymer/peptide nanofibers was investigated by X-ray photoelectron and Fourier transform infrared spectroscopies

Dataset related to article "Numerical activities of daily living: a short version"

Il dataset contiene i seguenti dati: colonne B, C, D: i dati socio-demografici dei soggetti, riportati nell’articolo in Tabella 1; colonna E: gruppo di appartenenza di ciascun soggetto (controllo vs diagnosi di malattie neurologiche specifiche) colonne F, G, H: punteggi grezzi dei soggetti ai test MoCA, MMSE e IADL, utilizzati nelle analisi riportate in Tabella 6; colonne dalla I alla ED: punteggi ottenuti alle varie sezioni del test NADL originale e ai relativi sub-item, utilizzati per le analisi riportate nelle tabelle 2, 3, 4. colonne dalla EF alla ES: punteggi ottenuti alle varie sezioni del test NADL short e relativi sub-item, utilizzati per le analisi riportate nelle tabelle 4, 5,

Functional changes in brain oscillations in dementia: A review

A growing body of evidence indicates that several characteristics of electroencephalography (EEG) and magnetoencephalography (MEG) play a functional role in cognition and could be linked to the progression of cognitive decline in some neurological diseases such as dementia. The present paper reviews previous studies investigating changes in brain oscillations associated to the most common types of dementia, namely Alzheimer's disease (AD), frontotemporal degeneration (FTD), and vascular dementia (VaD), with the aim of identifying pathology-specific patterns of alterations and supporting differential diagnosis in clinical practice. The included studies analysed changes in frequency power, functional connectivity, and event-related potentials, as well as the relationship between electrophysiological changes and cognitive deficits. Current evidence suggests that an increase in slow wave activity (i.e., theta and delta) as well as a general reduction in the power of faster frequency bands (i.e., alpha and beta) characterizes AD, VaD, and FTD. Additionally, compared to healthy controls, AD exhibits alteration in latencies and amplitudes of the most common event related potentials. In the reviewed studies, these changes generally correlate with performances in many cognitive tests. In conclusion, particularly in AD, neurophysiological changes can be reliable early markers of dementia

Light emission in GaN HEMTs: a powerful characterization and reliability tool

GaN-based high electron mobility transistors (HEMTs) are nowadays of major interest due to their high frequency and high-power performances. Although power densities up to 32 W/mm have been recently demonstrated, reliability is still one of the issue that has to be addressed in order to move toward commercially available devices. Sub-micrometer gate-length GaN HEMTs, which typically operate at very high drain-source voltages, VDS, may be prone to the same degradation mechanisms. Experimental methods capable of characterizing hot carrier effects should therefore be developed, in order to compare different device structures, or quantitatively assess lifetime accelerating factors corresponding to different bias conditions. In this paper we propose a methodology for the characterization of hot carrier effects and their dependence on bias conditions based on electro-luminescence (EL) measurements. It will also been shown that EL measurements can be used as a powerful characterization failure analysis tool, in order to study degradation and breakdown mechanisms in GaN HEMTs