Natural Frequencies of Triple-Walled Carbon Nanotubes

none3noIn this paper, the linear vibrations of Triple-Walled Carbon Nanotubes (TWNTs) are analysed. A multiple elastic shell model is considered. The shell dynamics is studied in the framework of the Sanders-Koiter shell theory. The van der Waals (vdW) interaction between two layers of the TWNT is modelled by a radius-dependent function. The circular cylindrical shell deformation is described in terms of longitudinal, circumferential and radial displacements. Simply supported, clamped and free boundary conditions are considered. The three displacement fields are expanded by means of a double mixed series based on Chebyshev orthogonal polynomials for the longitudinal variable and harmonic functions for the circumferential variable. The Rayleigh-Ritz method is applied to obtain approximate natural frequencies and mode shapes. The present model is validated in linear field by means of data derived from the literature. This study is focused on determining the effect of the geometry and boundary conditions on the natural frequencies of TWNTs.openAndrisano, Angelo O.; Pellicano, Francesco; Strozzi, MatteoAndrisano, Angelo O.; Pellicano, Francesco; Strozzi, Matte

A Testbed About Priority-Based Dynamic Connection Profiles in QoS Wireless Multimedia Networks

The ever-growing demand of high-quality broadband connectivity in mobile scenarios, as well as the Digital Divide discrimination, are boosting the development of more and more efficient wireless technologies. Despite their adaptability and relative small installation costs, wireless networks still lack a full bandwidth availability and are also subject to interference problems. In context of a Metropolitan Area Network serving a large number of users, a bandwidth increase can turn out to be neither feasible nor justified. In consequence, and in order to meet the needs of multimedia applications, bandwidth optimization techniques were designed and developed, such as Traffic Shaping, Policy-Based Traffic Management and Quality of Service (QoS). In this paper, QoS protocols are adopted and, in particular, priority-based dynamic profiles in a QoS wireless multimedia network. This technique allows to asssign different priorities to distinct applications, so as to rearrange service quality in a dynamic way and guarantee the desired performance to a given data flow

Editorial: Evolution in respiratory pharmacology

This collection of Research Topics entitled “Evolution in respiratory pharmacology,” involving authors from several countries, confirms that “Respiratory Pharmacology” is a current topic in clinical and research settings. All articles focused on contributions that explore the changing context and emerging new perspectives within Respiratory Pharmacology (Kim et al., Cerqua et al., Li et al., Lin et al., Zhang et al.). The emphasis of this Research Topic is on the dynamics of change and the evolution of the latest progress made in the field of Respiratory Pharmacology. This collection of articles aims to inform, inspire, and provide direction and guidance to researchers in the field

How Equalization Techniques Affect the TCP Performance of MC-CDMA Systems in Correlated Fading Channels

This paper investigates the impact of several equalization techniques for multicarrier code division multiple access systems on the performance at both lower and upper layers (i.e., physical and TCP layers). Classical techniques such as maximal ratio combining, equal gain combining, orthogonality restoring combining, minimum mean square error, as well as a partial equalization (PE) are investigated in time- and frequency-correlated fading channels with various numbers of interferers. Their impact on the performance at upper level is then studied. The results are obtained through an integrated simulation platform carefully reproducing all main aspects affecting the quality of service perceived by the final user, allowing an investigation of the real gain produced by signal processing techniques at TCP level

From the dual function lead AP2238 to AP2469, a multi-target-directed ligand for the treatment of Alzheimer\u2019s disease

The development of drugs with different pharmacological properties appears to be an innovative therapeutic approach for Alzheimer\u2019s disease. In this article, we describe a simple structural modification of AP2238, a first dual function lead, in particular the introduction of the catechol moiety performed in order to search for multi-target ligands. The new compound AP2469 retains antiacetylcholinesterase (AChE) and beta-site amyloid precursor protein cleaving enzyme (BACE)1 activities compared to the reference, and is also able to inhibit Ab42 self aggregation, Ab42 oligomer-binding to cell membrane and subsequently reactive oxygen species formation in both neuronal and microglial cells. The ability of AP2469 to interfere with Ab42 oligomer-binding to neuron and microglial cell membrane gives this molecule both neuroprotective and antiinflammatory properties. These findings, together with its strong chain-breaking antioxidant performance, make AP2469 a potential drug able to modify the course of the diseas

Natural products as novel scaffolds for the design of glycogen synthase kinase 3β inhibitors

Introduction: The different and relevant roles of GSK-3 are of critical importance since they deal with development, metabolic homeostasis, cell polarity and fate, neuronal growth and differentiation as well as modulation of apoptotic potential. Given their involvement with different diseases, many investigations have been undertaken with the aim of discovering new and promising inhibitors for this target. In this context, atural products represent an invaluable source of active molecules. Areas covered: In order to overcome issues such as poor pharmacokinetic properties or efficacy, frequently associated with natural compounds, different GSK-3β inhibitors belonging to alkaloid or flavonoid classes have been subjected to structural modifications in order to obtain more potent and safer compounds. Herein, the authors report the results obtained from studies where natural compounds have been used as hits with the aim of providing new kinase inhibitors endowed with a better inhibitory profile. Expert opinion: Structurally modification of natural scaffolds is a proven approach taking advantage of their pharmacological characteristics. Indeed, whatever the strategy adopted is and, despite the limitations associated with the structural complexity of natural products, the authors recommend the use of natural scaffolds as a promising strategy for the discovery of novel and potent GSK-3β inhibitors

Trasformazioni sociali, affettivizzazione della sfera pubblica e ricerca di senso

Western societies are crossed by a plurality of critical phenomena. The perception is that of being grappled with an uncontrollable anthropological drift, which make us powerless, leading towards a point of no return. A constitutive character of such a drift is the enslaving of the public spheres to the affects (i.e. affectivization). Any public affair and discussion is less and less addressed in terms of functional criteria (i.e. in terms of optimization of utility in reason of objective data) and more and more as the trigger as well as the target of affective acting-out. Such a dynamics challenges all individuals and institutions that think that civilization and progress are a matter of the human efforts to enslave the affective exercise of the present moment to the capacity of the reason to draw futurables. Education – and higher education within it – is at the front line of this challenge, because it is up to it the effort of promoting the symbolic resources that enables people to succeed in the twofold task of valorizing subjectivity and enslaving its affective substance to aims of social and civic progress. The present paper intends to contribute to address such a challenge. To this end, it proposes an interpretation of the affectivization spreading the contemporary social landscape, based on current debate in cognitive sciences. On this grounds, the general idea that such a phenomenon is something different from and more than a mere epidemy of irrationality – as it is more or less implicitly treated by observers and analysts – is deepened. Following that, strategic and methodological implications for higher education are discussed. It is called for an extension of the function of higher education, in the direction of taking charge of the demand of symbolic resources required to address the uncertainty generated by the contemporary socio-institutional turmoil