A new methodology for the determination of the workspace of six-DOF redundant parallel structures actuated by nine wires

The WiRo-6.3 is a six-degrees of freedom (six-DOF) robotic parallel structure actuated by nine wires, whose characteristics have been thoroughly analyzed in previous papers in reference. It is thought to be a master device for teleoperation; thus, it is moved by an operator through a handle and can convey a force reflection on the operator's hand. A completely new method for studying the workspace of this device, and of virtually any nine-wire parallel structure actuated by wire is presented and discussed, and its results are given in a graphical for

Ti and Zr amino-tris(phenolate) catalysts for the synthesis of cyclic carbonates from CO2 and epoxides

Herein, we report the application of four amino-tris(phenolate)-based metal complexes incorporating Ti(IV) or Zr(IV) centres (2a-3b) as homogeneous catalysts for the conversion of CO2 and epoxides into cyclic carbonates. The four complexes were synthesised, characterised and then evaluated in combination with tetrabutylammonium iodide, bromide or chloride as binary catalytic systems for the reaction of CO2 with 1,2-epoxyhexane as epoxide substrate at 12 bar CO2 pressure and 90 °C for 2 h. The catalytic systems comprising the two Ti(IV) complexes (2a and 2b) showed similar performance. One notable exception was the catalytic system consisting of titanium complex 2b, bearing an axial Cl-ligand, and tetrabutylammonium chloride, which displayed higher catalytic activity compared to other titanium-based systems. Even higher activity was achieved with Zr(IV) complex 3a, bearing an axial isopropoxide ligand, which reached turnover numbers (TONmetal) up to 1920 for the reaction of CO2 with 1,2-epoxyhexane at 12 bar CO2 pressure and 90 °C for 2 h. This performance is comparable with that of state-of-the-art catalysts for this reaction. The catalytic system consisting of complex 3a and tetrabutylammonium bromide was explored further by investigating its applicability with a broad substrate scope, achieving quantitative conversion of several epoxides with CO2 into cyclic carbonate products at 90 °C and 12 bar CO2 pressure for 18 h. The selectivity towards the cyclic carbonate products was ≥ 98% for all studied terminal epoxides and ≥ 80% for all examined cyclohexene-type epoxides

Role of Na+/H+ exchange in thrombin-induced platelet-activating factor production by human endothelial cells.

Thrombin-stimulated endothelial cells produce platelet-activating factor (PAF) in a dose-dependent manner: the activation of a Ca2+-dependent lyso-PAF acetyltransferase is the rate-limiting step in this process. The present study shows that acetyltransferase activation and consequent PAF production induced by thrombin in human endothelial cells are markedly inhibited in Na+-free media or after addition of the amiloride analog 5-(N-ethyl-N-isopropyl)amiloride, suggesting that a Na+/H+ antiport system is present in endothelial cells and plays a prominent role in thrombin-induced PAF synthesis. Accordingly, thrombin elicits a sustained alkalinization in 6-carboxyfluorescein-loaded endothelial cells, that is abolished in either Na+-free or 5-(N-ethyl-N-isopropyl)amiloride-containing medium. Extracellular Ca2+ influx induced by thrombin (as measured by quin2 and 45Ca methods) is completely blocked in the same experimental conditions, and monensin, a Na+/H+ ionophore mimicking the effects of the antiporter activation, evokes a dose-dependent PAF synthesis and a marked Ca2+ influx, which are abolished in Ca2+-free medium. An amiloride-inhibitable Na+/H+ exchanger is present in the membrane of human endothelial cells, its apparent Km for extracellular Na+ is 25 mM, and its activity is greatly enhanced when the cytoplasm is acidified. These results suggest that Na+/H+ exchange activation by thrombin and the resulting intracellular alkalinization play a direct role in the induction of Ca2+ influx and PAF synthesis in human endothelial cells

Electrically-Responsive Reversible Polyketone/MWCNT Network through Diels-Alder Chemistry

This study examines the preparation of electrically conductive polymer networks based on furan-functionalised polyketone (PK-Fu) doped with multi-walled carbon nanotubes (MWCNTs) and reversibly crosslinked with bis-maleimide (B-Ma) via Diels-Alder (DA) cycloaddition. Notably, the incorporation of 5 wt.% of MWCNTs results in an increased modulus of the material, and makes it thermally and electrically conductive. Analysis by X-ray photoelectron spectroscopy indicates that MWCNTs, due to their diene/dienophile character, covalently interact with the matrix via DA reaction, leading to effective interfacial adhesion between the components. Raman spectroscopy points to a more effective graphitic ordering of MWCNTs after reaction with PK-Fu and B-Ma. After crosslinking the obtained composite via the DA reaction, the softening point (tan(delta) in dynamic mechanical analysis measurements) increases up to 155 degrees C, as compared to the value of 130 degrees C for the PK-Fu crosslinked with B-Ma and that of 140 degrees C for the PK-Fu/B-Ma/MWCNT nanocomposite before resistive heating (responsible for crosslinking). After grinding the composite, compression moulding (150 degrees C/40 bar) activates the retro-DA process that disrupts the network, allowing it to be reshaped as a thermoplastic. A subsequent process of annealing via resistive heating demonstrates the possibility of reconnecting the decoupled DA linkages, thus providing the PK networks with the same thermal, mechanical, and electrical properties as the crosslinked pristine systems

Stimulation of the Na+/H+ exchanger in human endothelial cells activated by granulocyte- and granulocyte-macrophage-colony-stimulating factor. Evidence for a role in proliferation and migration.

It has been shown that human endothelial cells (HEC) are stimulated to migrate and proliferate by granulocyte (G)- and granulocyte-macrophage (GM)-colony-stimulating factor (CSF) (Bussolino, F., Wang, J. M., Defilipii, P. Turrini, F., Sanavio, F., Edgell, C.-J. S., Aglietta, M., Arese, P., and Mantovani, A. (1989) Nature 337, 471-473). The rapid intracellular events initiated by these cytokines on binding to their receptors on HEC are not defined. Addition of G- or GM-CSF to HEC produced a rapid activation of Na+/H+ exchanger resulting in an increase in intracellular pH (pHi). Both cytokines induced an alkaline displacement in the pHi dependence of the exchanger without affecting the affinity for external Na+ (Nao) and the rate of exchanger. Ethylisopropylamiloride, a selective inhibitor of the Na+/H+ exchanger, inhibited the intracellular alkalinization, the migration, and proliferation induced by G- and GM-CSF. The data indicate that G- and GM-CSF initiate a rapid exchange of Na+ and H+ by means of the Na+/H+ exchanger and that this ethylisopropylamiloride-sensitive ions flux is important to the biological effects of these cytokines on HEC

A 17-Gene Expression Signature for Early Identification of Poor Prognosis in Clear Cell Renal Cell Carcinoma

: The Identification of reliable Biomarkers able to predict the outcome after nephrectomy of patients with clear cell renal cell carcinoma (ccRCC) is an unmet need. The gene expression analysis in tumor tissues represents a promising tool for better stratification of ccRCC subtypes and patients' evaluation. Methods: In our study we retrospectively analyzed using Next-Generation expression analysis (NanoString), the expression of a gene panel in tumor tissue from 46 consecutive patients treated with nephrectomy for non-metastatic ccRCC at two Italian Oncological Centres. Significant differences in expression levels of selected genes was sought. Additionally, we performed a univariate and a multivariate analysis on overall survival according to Cox regression model. Results: A 17-gene expression signature of patients with a recurrence-free survival (RFS) < 1 year (unfavorable genomic signature (UGS)) and of patients with a RFS > 5 years (favorable genomic signature (FGS)) was identified and resulted in being significantly correlated with overall survival of the patients included in this analysis (HR 51.37, p < 0.0001). Conclusions: The identified Genomic Signatures may serve as potential biomarkers for prognosis prediction of non-metastatic RCC and could drive both follow-up and treatment personalization in RCC management

Studio e progettazione di master per teleoperazione azionati a cordini

Tesi di Dottorato di Ricerca in Meccanica Applicat