Sliding Dynamics of Parallel Graphene Sheets: Effect of Geometry and Van Der Waals Interactions on Nano-Spring Behavior

Graphene and carbon nanotubes are promising materials for nanoelectromechanical systems. Among other aspects, a proper understanding of the sliding dynamics of parallel graphene sheets or concentric nanotubes is of crucial importance for the design of nano-springs. Here, we analytically investigate the sliding dynamics between two parallel, rigid graphene sheets. In particular, the analysis focuses on configurations in which the distance between the sheets is kept constant and lower than the equilibrium interlayer spacing of graphite (unstable configurations). The aim is to understand how the interlayer force due to van der Waals interactions along the sliding direction changes with the geometrical characteristics of the configuration, namely size and interlayer spacing. Results show metastable equilibrium positions with completely faced sheets, namely a null force along the sliding direction, whereas net negative/positive forces arise when the sheets are approaching/leaving each other. This behavior resembles a molecular spring, being able to convert kinetic into potential energy (van der Waals potential), and viceversa. The amplitude of both storable energy and entrance/exit forces is found to be proportional to the sheet size, and inversely proportional to their interlayer spacing. This model could also be generalized to describe the behavior of configurations made of concentric carbon nanotubes, therefore allowing a rational design of some elements of carbon-based nanoelectromechanical systems

Thermally triggered nanorocket from double-walled carbon nanotube in water

In this work, we propose and investigate the use of double-walled carbon nanotubes (DWCNTs) as nanosized rockets. The nanotubes are immersed in water, and the propulsion of inner nanotube is achieved by heating the water encapsulated within the DWCNT. Considering a setup made of (5,5)(8,8) DWCNT, molecular dynamics simulations for different water temperatures show that the trajectory can be divided into four phases: trigger, expulsion, damping and final equilibrium. After analysing the dynamics and the involved forces, we find out that the inner nanotube expulsion is mainly controlled by van der Waals interactions between the nanotubes; whereas, the damping role is predominantly played by the external aqueous environment. Based on these results, we propose an analytical model able to predict both the triggering time for a given water temperature and the whole dynamics of nanorocket. The validity of such dynamical model can be extended also to a broader variety of DWCNT configurations, once the different forces acting on the inner nanotube are provided. The proposed model may contribute to assist the design of nanorockets in several nanotechnology applications, such as triggered drug delivery, cell membrane piercing, or colloids with thermophoretic properties

Pharmacogenetics of Antidepressant Drugs: An Update

SUMMARY Pharmacological treatment of depressive disorders is characterized by poor predictability of individual response. In recent years, the increasing evidence has demonstrated that genetic factors play a critical role in determining the differences in treatment outcome to antidepressant drugs. A number of pharmacogenetic studies on antidepressant drugs has been conducted, and genetic variations at level of drug metabolizing enzymes, drug transporters and drug targets, possibly influencing the clinical response, have been identified. Pharmacogenetics may hopefully provide the basis for individualized pharmacotherapy of depressive disorders in order to maximize the probability of a favorable response and minimize the risk of adverse drug reactions. In this article, the major findings related to the pharmacogenetics of genes involved in the pharmacokinetics and pharmacodynamics of antidepressant drugs are critically reviewed

Real World Use of Antidiabetic Drugs in the Years 2011-2017: A Population-Based Study from Southern Italy

Diabetes mellitus is a metabolic disease characterized by chronic hyperglycemia. The availability of new antidiabetic drugs (ADs) has led to complex treatment patterns and to changes in the patterns of specific drug utilization. The aim of this population-based study was to describe the pattern of antidiabetic drugs (ADs) use in Southern Italy in the years 2011-2017, in relation to the updated type 2 diabetes mellitus (T2DM) therapy guidelines. A retrospective cohort study was conducted on T2DM patients using data from the Palermo Local Health Unit (LHU) claims database and diabetologist registry. The first-line treatment was investigated and incident treatments were identified and characterized at baseline in terms of demographics, complications, comorbidities, concomitant drugs and clinical parameters. Persistence to AD treatment was also evaluated. During the study period, one-third of first ever ADs users started the treatment with ADs other than metformin, in contrast to guideline recommendations. Among 151,711 incident AD treatments, the male to female ratio was 1.0 and the median age was 66 (57-75) years. More than half (55.0%) of incident treatments discontinued the therapy during the first year of treatment. In Italy, general practitioners (GPs) can only prescribe first-generation ADs, while the prescription of more recently marketed ADs, such as GLP-1RA, DPP4i and SGLT2i, is restricted to diabetologists only, based on a therapeutic plan. The role of GPs in the management of T2DM in Italy should be re-evaluated

Global and Regional IUCN Red List Assessments: 5

In this contribution, the conservation status of four vascular plants according to IUCN categories and criteria are presented. It includes the assessment of Arceuthobium oxycedri (DC.) M.Bieb., Ionopsidium albiflorum Durieu, Trifolium latinum Sebast., and Vicia incisa M.Bieb. at a Regional level (Italy)

Taxonomic and ecological remarks on Solenopsis bivonae species complex (Campanulaceae)

The populations usually attributed to Solenopsis bivonae (Tineo) M.B.Crespo, Serra & A.Juan are investigated from a taxonomical and morphological viewpoint. Within this species complex, four new subspecies occurring in Sicily and Calabria are recognized, such as subsp. bivonae, subsp. madoniarum, subsp. peloritana and subsp. brutia. In addition, a new species from Cyprus described as S. meikleana and S. bacchettae from Sardinia must be included in this group. The synonymy, typification, description, seed testa morphology, chorology, ecology, illustrations, conservation status, and examined specimens for each taxon are provided. Besides, the analytical keys, distribution maps, and phytosociological arrangement regarding these taxa are given too

Correction to: Psychiatric disorders and SLC6A4 gene variants: possible effects on alcohol dependence and alzheimer's disease

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New national and regional Annex I Habitat records: from #60 to #82

New Italian data on the distribution of the Annex I Habitats are reported in this contribution. Specifically, 8 new occurrences in Natura 2000 sites are presented and 49 new cells are added in the EEA 10 km × 10 km reference grid. The new data refer to the Italian administrative regions of Campania, Calabria, Marche, Piedmont, Sardinia, Sicily, Tuscany and Umbria. Relevés and figures are provided as Supplementary material respectively 1 and 2