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The extracellular matrix (ECM) of the meniscus is a gel-like water solution of proteoglycans embedding bundles of collagen fibers mainly oriented circumferentially. Collagen fibers significantly contribute to meniscal mechanics, however little is known about their mechanical properties. The objective of this study was to propose a constitutive model for collagen fibers embedded in the ECM of the meniscus and to characterize the tissue's pertinent mechanical properties. It was hypothesized that a linear fiber reinforced viscoelastic constitutive model is suitable to describe meniscal mechanical behavior in shear. It was further hypothesized that the mechanical properties governing the model depend on the tissue's composition. Frequency sweep tests were conducted on eight porcine meniscal specimens. A first cohort of experimental data resulted from tissue specimens where collagen fibers oriented parallel with respect to the shear plane were used. This was done to eliminate the contribution of collagen fibers from the mechanical response and characterize the mechanical properties of the ECM. A second cohort with fibers orthogonally oriented with respect to the shear plane that were used to determine the elastic properties of the collagen fibers via inverse finite element analysis. Our testing protocol revealed that tissue ECM mechanical behavior could be described by a generalized Maxwell model with 3 relaxation times. The inverse finite element analysis suggested that collagen fibers can be modeled as linear elastic elements having an average elastic modulus of 287.5 ± 62.6 MPa. Magnitudes of the mechanical parameters governing the ECM and fibers were negatively related to tissue water content.

Improvements in living conditions and progress in medical management have resulted in better quality of life and longer life expectancy. Therefore, the number of older people undergoing surgery is increasing. Frailty is often described as a syndrome in aged patients where there is augmented vulnerability due to progressive loss of functional reserves. Studies suggest that frailty predisposes elderly to worsening outcome after surgery. Since emergency surgery is associated with higher mortality rates, it is paramount to have an accurate stratification of surgical risk in such patients. The aim of our study is to characterize the clinicopathological findings, management, and short-term outcome of elderly patients undergoing emergency surgery. The secondary objectives are to evaluate the presence and influence of frailty and analyze the prognostic role of existing risk-scores. The final FRAILESEL protocol was approved by the Ethical Committee of “Sapienza” University of Rome, Italy. The FRAILESEL study is a nationwide, Italian, multicenter, observational study conducted through a resident-led model. Patients over 65years of age who require emergency surgical procedures will be included in this study. The primary outcome measures are 30-day postoperative mortality and morbidity rates. The Clavien-Dindo classification system is used to categorize complications. The secondary outcome measures include length of hospital stay, length of stay in intensive care unit, and predictive value for morbidity and mortality of several frailty and surgical risk-scores. The results of the FRAILESEL study will be disseminated through national and international conference presentations and peer-reviewed journals. The study is also registered at ClinicalTrials.gov (ClinicalTrials.gov identifier: NCT02825082).

L’articolo descrive i vari aspetti dei sistemi di misura wireless delle scariche parziali (PD). In particolare, sul problema della sincronizzazione dell’angolo di fase della tensione per il rilevamento e la classificazione delle PD.

Negli ultimi anni la poliammide 11 (PA11) ha suscitato un notevole interesse in svariati settori industriali industriali.Per ottimizzare la comprensione dei meccanismi che governano la termo e foto ossidazione della PA11, sono stati studiati mediante Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) , cromatografia ad esclusione sterica (SEC) e viscosimetria, i processi di degradazione termo e foto-ossidativi che interessano il PA11 ed in particolare i nanocompositi formulati con Cloisite30B

We aim to investigate both thermal degradation processes (non oxidative and oxidative) occurring in PA11 nanocomposites and establish the eventual contribution of organo nanoclay modifier on degradation mechanisms.

In this work, the thermo- and photo-oxidation stability of functional nitroxide grafted polyethylene (PE) samples was tested.

In recent years there has been a growing interest in developing sustainable alternatives to oil-based plastics. In particular, biodegradable aliphatic polyesters, such as poly(lactic acid) (PLA) and poly(butylene succinate) (PBS), are becoming increasingly important due to their valuable properties including thermoplastic processability and thermo-mechanical properties. Nonetheless, these materials present several drawbacks, such as the lack of reactive functionalities that are limiting their applications, versatility and successful use as commodity plastics. In this work it was investigated for the first time a new method of preparation of functionalized PBS by a post-polymerization approach based on the radical coupling between PBS macroradicals and TEMPO derivatives carrying different functionalities. Our method turned out to be successful in promoting grafting by limiting the radical-induced crosslinking/branching of the polymer substrate (Fig. 1). In particular, two different series of functionalized PBS samples were obtained by grafting the 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (BzO-TEMPO), and the pro-fluorescent 4-(1-naphtoate)-2,2,6,6-tetramethylpiperidine-1-oxyl (NfO-TEMPO). The grafting was clearly evidenced by MALDI-TOF MS, UV-Vis and 1H-NMR spectroscopy from which it was estimated the functionalization degree Moreover, by electron spinning resonance (EPR) experiments it was accurately determined the grafting site. Finally, the exploitation of a pro-fluorescent nitroxide to form functionalized PBS samples represents a significant step toward the unambiguous demonstration of the radical grafting on this type of polymers, proving also the possibility of tailoring a well-defined fluorescently labeled biodegradable polyester via a feasible process

La modifica di nanotubi di carbonio (CNT) attraverso innesto (grafting) di catene polimeriche sulla loro superficie è un metodo efficace per promuovere la dispersione di queste cariche a livello nanometrico in una matrice polimerica. La funzionalizzazione covalente di CNT con catene polimeriche viene generalmente ottenuta sia attraverso crescita controllata di polimeri a partire dalle pareti della nanocarica mediante metodi "grafting from" sia attraverso metodi di "grafting to" che si basano sulla reazione di condensazione tra polimeri preformati e CNT opportunamente modificati. In questo lavoro viene proposto un nuovo approccio di tipo "grafting to" per innestare catene polimeriche su CNT basato sulla reazione di accoppiamento tra il radicale nitrossilico opportunamente legato ai CNT e radicali del polimero. Ispirati da nostri precedenti studi [1,2] in cui nitrossidi funzionali derivati del TEMPO sono stati innestati su catene polimeriche (sia poliolefine che poliesteri alifatici) mediante reazione di accoppiamento tra il radicale TEMPO e il macroradicale generato per estrazione di idrogeno dalla catena polimerica, in questo lavoro il poli(butilene succinato) (PBS) è stato legato covalentemente a MWCNT con ancorate in superficie delle funzionalità nitrossiliche (MWCNT-g-TEMPO). I MWCNT-g-TEMPO sono stati preparati mediante click chemistry tra il derivato alchinico del TEMPO e MWCNT modificati in superficie con gruppi azidici. Il PBS è stato legato ai MWCNT-g-TEMPO attraverso reazione di accoppiamento tra radicali nitrossilici e il macroradicali generati mediante addizione di perossido. La presenza del radicale nitrossilico sulla superficie dei MWCNT-g-TEMPO così come l'avvenuto innesto delle catene di PBS sui nanotubi è stato dimostrato mediante analisi EPR. Le proprietà strutturali, reologiche, morfologiche e termiche del nanocomposito sono state confrontate con quelle di un campione preparato per miscelazione fisica tra i due componenti. I risultati evidenziano che il metodo è efficace nel promuovere l'innesto di catene polimeriche sui CNT immobilizzando la nanocarica e promuovendone la dispersione nella matrice polimerica.

Objectve: Metalloproteinases (MMPs) are endopeptidases involved in extracellular matrix remodelling, associated with both physiopatological processes of several human tissues and systems, such as vascular system. It is well known their involvement in mediating both beneficial and pathological aorta effects, such as abdominal orta aneurysms and its complcations. On the contrary, unclear data exist about their role in the pathophysiology of sporadic thoracic aneurysm (TAA) and its complications. Thus, the aim of this study was to nalyse the role of MMPs in TAA complications, i.e. rupture and dissection.Methods: Aortic specimens obtained from 73 patients (51 men and 22 women, age 61.7 years) affected by TAAs, 18 patients with type A aortic dissection (TAD) and 30 controls were utilised for histopathological and immne-histochemical analyses. In addition, a second group of 128 subjects (61men and 67 womem, age 61.7 years) was enrolled to examine the role of single nucleotide polymorphirms (SNPs) of MMP-9 and MMP-2 genes in disease risk. Results: Three different patterns of MMPs(extracellular, intracellular, and mixed) with different concentration (low, moderate, elevated) have been observed in case aorta samples. The pattern with elevated MMP amount in aorta samples from TAD cases was also characterised by increased cystic medial degeneration, whitout substitutive fibrosis, and plurifocal apoptosis. In the context of TAA aorta samples, we identified three phenotypes. In particular, the phenotype III mainly observed in case samples showed the same histological features of TAD with elevated MMP concentration with a mixed pattern. in addition, significant associations were obserbved between the -1562C/T MMP9, -735C/T MMP2 SNPs and the risk of both TAA and TAD. Conclusions: OUR data suggest a crucial role of both MMP-2 and -9 in both TAA and its complications. such as TAD. in future they might be considered as new criteria in TAA surgical indications.