Characteristic Roots of a Class of Fractional Oscillators

The fundamental theorem of algebra determines the number of characteristic roots of an ordinary differential equation of integer order. Thismay cease to be true for a differential equation of fractional order.Theresults given in this paper suggest that the number of the characteristic roots of a class of oscillators of fractional order may in general be infinitely great. Further, we infer that it may also be the case for the characteristic roots of a differential equation of fractional order greater than 1.The relationship between the range of the fractional order and the locations of characteristic roots of oscillators in the complex plane is considered

Development of a Vessel Scheduling Optimization Model to improve Maritime Transport sustainability

The social and economic development of the islands is generally dependent on the interconnection level with the mainland obtained through maritime transport services. When connecting many islands, the route planning is essential and typically a variety of constraints must be considered. Various optimization methods have been established to improve cost-efficiency but today environmental concerns, like the reduction of CO2 emissions, have become mandatory. This paper proposes a vessel scheduling optimization model able to simultaneously consider compulsory and optional tasks and vehicle-dependent profits. The algorithm was applied to seven islands of the Tyrrhenian Sea located in front of Sicily, named “Aeolian Islands”. Considering the regional requirements in terms of minimum number of routes and maximum fare prices for each season, this research compared the optimal vessels option obtained maximizing the profit with the one obtained minimizing the emissions. In particular, we have conducted three different analyses, in the first one we have considered only the mandatory routes while the second one was carried out identifying a series of potentially attractive additional activities based on historical demand data provided by the company that currently manages the service. Finally, the third analysis addresses a scenario where older fuel-powered vessels were replaced with hybrid electric ones

Microstructural and morphological properties of homoepitaxial (001)ZnTe layers investigated by x-ray diffuse scattering

The microstructural and morphological properties of homoepitaxial (001)ZnTe layers are investigated by x-ray diffuse scattering. High resolution reciprocal space maps recorded close to the ZnTe (004) Bragg peak show different diffuse scattering features. One kind of cross-shaped diffuse scattering streaks along directions can be attributed to stacking faults within the epilayers. Another kind of cross-shaped streaks inclined at an angle of about 80deg with respect to the in-plane direction arises from the morphology of the epilayers. (abridged version

A spectroscopic study of the open cluster NGC 6250

We present the chemical abundance analysis of 19 upper main-sequence stars of the young open cluster NGC 6250 (log t∼7.42 yr). Thiswork is part of a project aimed at setting observational constraints on the theory of atomic diffusion in stellar photospheres, by means of a systematic study of the abundances of the chemical elements of early F-, A- and late B-type stars of well-determined age. Our data set consists of low-, medium- and high-resolution spectra obtained with the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument of the ESO Very Large Telescope (VLT). To perform our analysis, we have developed a new suite of software tools for the chemical abundance analysis of stellar photospheres in local thermodynamical equilibrium. Together with the chemical composition of the stellar photospheres, we have provided new estimates of the cluster mean radial velocity, proper motion, refined the cluster membership, and we have given the stellar parameters including masses and fractional age. We find no evidence of statistically significant correlation between any of the parameters, including abundance and cluster age, except perhaps for an increase in Ba abundance with cluster age.We have proven that our new software tool may be successfully used for the chemical abundance analysis of large data sets of stellar spectra

A flexible and portable harvesting-storage device by quasi-solid-state supercapacitor and dye-sensitized solar cell integration

In recent years the utilization of power in off grid conditions is dramatically increasing. For this reason research is putting much effort in obtaining improvements in energy storage devices efficiencies and in discovering alternatives concerning easiness of fabrication that can be industrially implemented. In this framework, integration of energy storage devices with energy harvesting systems is obtaining more and more significance since the amount of energy that can be stored especially in Electrochemical Double Layer Capacitors (EDLCs) is limited. To this purpose, herein we present an innovative flexible integrated device composed by a symmetrical aqueous EDLC and a TiO2 nanotubes-based Dye Sensitized Solar cell (DSSC). A UV photo-polymerized quasi-solid electrolyte was used in both sections. At first a self-standing flexible polymer matrix was fabricated starting from Bisphenol A ethoxylate dimethacrylate (BEMA) and poly (ethylene glycol) methyl ether methacrylate (PEGMA), adding a 3% by weight of 2hydroxy-2-methyl-1-phenyl-1-propanone (Darocur 1173) as photoinitiator. Then, the matrix was soaked in two different liquid electrolytes, a 2 M NaCl aqueous solution for the energy storage section and an Iodine-based liquid electrolyte for the DSSC unit. This is the first work in which this type of polymer electrolyte membrane is used for an EDLC. The electrodes were fabricated onto Stainless-steel and Titanium grids, for EDLC and DSSC respectively. TiO2 nanotubes were grown by means of anodic oxidation as photoanode semiconductor material, while EDLC active material was composed by 85% of graphene nanoplatelets and 15% of Acetylene Black. The harvesting-storage device (HSD) was sealed by a light-cured photo-polymerization method. The measured overall photon-to-electrical conversion and storage efficiency for the HSD was 1.02% under standard test conditions. This value increases for lower illumination conditions reaching 1.46% at 0.3 Sun

New tools in percutaneous minimally invasive chronic subdural hematomas evacuation

Background: Incidence of chronic subdural hematomas (cSDH) is expected to progressive rise in the next decades. There is no univocal indication of the approach to be used. Furthermore, there is no data about the efficacy of twist drill craniostomy (TDC) in hematomas with membranes. Objective: To describe our modified technique for TDC in patients affected by cSDH with membranes and in treatment with antiplatelets. Methods: We analyzed a group of 37 patients, affected by cSDH with membrane (type D laminar membrane and type G trabecular membrane according to Nakaguchi classification), treated with mushroom TDC using a modified technique. Results: After surgery the average maximum thickness of the common postoperative liquoral subdural collection decreased from 18.8 to 6.21 mm. We documented one acute subdural hematoma (2.7%), asymptomatic and not treated, and one recurrence of cSDH (2.7%) after 2 months that needed re-intervention with single burr hole. Conclusions: We presented a modified twist drill technique, characterized by the introduction of an application of a new device that optimizes both surgical results, clinical outcome and surgical procedure time. The presence of membrane type D and G does not affect the efficacy of drainage, that is negatively related to the presence of clots or acute hematoma. This modified technique is safe, fast, effective and represents a valid first line treatment of an unstable and unpredictable pathology such as cSDH. We suggest performing such technique on a larger patients’ cohort to further validate its effectiveness

Generation of cytocompatible superhydrophobic Zr–Cu–Ag metallic glass coatings with antifouling properties for medical textiles

Zirconium–Copper-based metallic glass thin films represent promising coatings in the biomedical sector for their combination of antibacterial property and wear resistance. However, finding a Zr–Cu metallic glass composition with desirable cytocompatibility and antibacterial property is extremely challenging. In this work, we have created a cytocompatible and (super-)hydrophobic Zr–Cu–Ag metallic glass coating with ≈95% antifouling properties. First, a range of different chemical compositions were prepared via Physical Vapor Deposition magnetron by co-sputtering Zr, Cu, and Ag onto a Polybutylene terephthalate (PBT) substrate among which Zr93·5Cu6·2Ag0.2, Zr76·7Cu22·7Ag0.5, and Zr69·3Cu30·1Ag0.6 were selected to be further investigate for their surface properties, antibacterial activity, and cytocompatibility. Scanning electron microscopy (SEM) images revealed a micro-roughness fibrous structure holding superhydrophobic properties demonstrated by specimens' static and dynamic contact angle measurements ranging from 130° to 150°. The dynamic contact angle measurements have shown hysteresis below 10° for all coated samples which indicated the superhydrophobicity of the samples. To distinguish between antifouling and bactericidal effect of the coating, ions release from coatings into Luria Bertani Broth (LB), and Dulbecco's Modified Eagle Medium (DMEM) solutions were evaluated by inductively coupled plasma mass spectrometry (ICP-MS) measurements after 24 ​h and 5 days. Antifouling properties were evaluated by infecting the specimens' surface with the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli strain reporting a ≈95% reduction of bacteria adhesion as visually confirmed by FESEM and fluorescent live/dead staining. Human mesenchymal stem cells (hMSC) were used for direct cytocompatibility evaluation of coated samples and their metabolic activity was evaluated via relative fluorescence unit after 24 ​h and 5 days confirming that it was comparable to the controls (>97% viable cells). The results were further visualized by FESEM, fluorescent staining by Live/Dead Viability/Cytotoxicity Kit and confirmed the cytocompatibility of all coated samples. Finally, hMSC′ cytoplasm was stained by May Grunwald and Giemsa after 5days to detect and visualize the released ions which have diffused through the cells' membrane

Comment on Shadow model for sub-barrier fusion applied to light systems

We demonstrate that the cross sections derived from the "shadow model" for reactions between light nuclei disagree with low-energy laboratory data and exhibit unphysical behavior at energies below those for which data exist. As a consequence, the large thermonuclear reaction rates obtained by Scalia and Figuera [Phys. Rev. C46, 2610 (1992)] are wrong.Comment: 6 pages (1 figure not included, available upon request) Formatted in REVTEX (January 1993