Hydrodynamic fluctuations in the presence of one parameter Mittag-Leffler friction

The effects of hydrodynamic fluctuations on the subdiffusive motion of a particle subject to one parameter Mittag-Leffler friction are examined by means of the fractional Langevin equation. The particle experiences an overall additive colored noise formed by, on the one hand, the hydrodynamic back flow effects and, on the other hand, an additional contribution predicted by fluctuation dissipation relation. Particle motion may or may not be subject to a restoring force. All possible combinations of forces exerted on the test particle are being studied, and for each of them the generalized response function in terms of multinomial Mittag-Leffler functions is provided. Mean square displacement, normalized velocity and position auto-correlation functions are furnished as special cases of the generalized response function, and their short and long time limits are analytically given. In addition, for the same measures analytical expressions valid for time windows much broader than the usual asymptotic limit are provided, and can be used to fit real life data. We demonstrate that normalized velocity and position auto-correlation functions are the main sources providing information on the effect of hydrodynamic fluctuations on particle motion. Actually, they oppose to friction and to restoring force, and smooth out the anti-persistent character of the motion

Daughter Coloured Noises: The Legacy of Their Mother White Noises Drawn from Different Probability Distributions

White noise is fundamentally linked to many processes; it has a flat power spectral density and a delta-correlated autocorrelation. Operators acting on white noise can result in coloured noise, whether they operate in the time domain, like fractional calculus, or in the frequency domain, like spectral processing. We investigate whether any of the white noise properties remain in the coloured noises produced by the action of an operator. For a coloured noise, which drives a physical system, we provide evidence to pinpoint the mother process from which it came. We demonstrate the existence of two indices, that is, kurtosis and codifference, whose values can categorise coloured noises according to their mother process. Four different mother processes are used in this study: Gaussian, Laplace, Cauchy, and Uniform white noise distributions. The mother process determines the kurtosis value of the coloured noises that are produced. It maintains its value for Gaussian, never converges for Cauchy, and takes values for Laplace and Uniform that are within a range of its white noise value. In addition, the codifference function maintains its value for zero lag-time essentially constant around the value of the corresponding white noise

Dissecting the supramolecular dispersion of fullerenes by proteins/peptides: Amino acid ranking and driving forces for binding to c60

Molecular dynamics simulations were used to quantitatively investigate the interactions between the twenty proteinogenic amino acids and C60. The conserved amino acid backbone gave a constant energetic interaction ~5.4 kcal mol−1, while the contribution to the binding due to the amino acid side chains was found to be up to ~5 kcal mol−1 for tryptophan but lower, to a point where it was slightly destabilizing, for glutamic acid. The effects of the interplay between van der Waals, hydrophobic, and polar solvation interactions on the various aspects of the binding of the amino acids, which were grouped as aromatic, charged, polar and hydrophobic, are discussed. Although π–π interactions were dominant, surfactant‐like and hydrophobic effects were also observed. In the molecular dynamics simulations, the interacting residues displayed a tendency to visit configura-tions (i.e., regions of the Ramachandran plot) that were absent when C60 was not present. The amino acid backbone assumed a “tepee‐like” geometrical structure to maximize interactions with the fullerene cage. Well‐defined conformations of the most interactive amino acids (Trp, Arg, Met) side chains were identified upon C60 binding

Effectiveness of synthetic calcite doped with Fe-EDDHSA as a slow-release Fe source: In-vitro experiment on kiwifruit (Actinidia chinensis var. deliciosa) plants

Doped calcite (Fe-EDDHSA/CaCO3) was experimentally produced. The hypothesis of the present experiment is that, when roots get in contact with Fe-EDDHSA/CaCO3, the extrusion of H+ decreases the pH and dissolves calcite with subsequent release of Fe that becomes available for roots. The aim of the experiment was to determine whether doped calcite might represent a slow-release Fe source for in-vitro grown kiwifruit plantlets. The root elongation media used in the experiment had pH 8.0 and differed from each other for Fe supply as follow: Control medium that contained complete Murashige and Skoog salt mixture, including FeSO4 and Na(2)EDTA; calcite medium enriched with Fe-EDDHSA/CaCO3 as the only Fe source; -Fe medium without Fe. The absence of FeSO4 in the medium caused a reduction of plantlet growth. The final pH was higher with calcite medium than in control and -Fe. The addition of Fe-EDDHSA/CaCO3 increased Fe shoot concentration when compared with the -Fe medium. The data of the present experiment show the potential Fe slow release ability of Fe-EDDHSA/CaCO3; however, further investigation on Fe containing fertilizers should be conducted on potted plants to validate our result

Experimental and theoretical study of the adsorption of fumaramide [2]rotaxane on Au(111) and Ag(111) surfaces

Thin films of fumaramide [2] rotaxane, a mechanically interlocked molecule composed of a macrocycle and a thread in a "bead and thread" configuration, were prepared by vapor deposition on both Ag(111) and Au(111) substrates. X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy were used to characterize monolayer and bulklike multilayer films. XPS determination of the relative amounts of carbon, nitrogen, and oxygen indicates that the molecule adsorbs intact. On both metal surfaces, molecules in the first adsorbed layer show an additional component in the C 1s XPS line attributed to chemisorption via amide groups. Molecular-dynamics simulation indicates that the molecule orients two of its eight phenyl rings, one from the macrocycle and one from the thread, in a parallel bonding geometry with respect to the metal surfaces, leaving three amide groups very close to the substrate. In the case of fumaramide [2]rotaxane adsorption on Au(111), the presence of certain out-of-plane phenyl ring and Au-O vibrational modes points to such bonding and a preferential molecular orientation. The theoretical and experimental results imply that the three-dimensional intermolecular configuration permits chemisorption at low coverage to be driven by interactions between the three amide functions of fumaramide [2]rotaxane and the Ag(111) or Au(111) surface. (c) 2005 American Institute of Physics.</p

No evidence of sars-cov-2 circulation in rome (Italy) during the pre-pandemic period. Results of a retrospective surveillance

In March 2020, the World Health Organization (WHO) declared that the COVID-19 outbreak recorded over the previous months could be characterized as a pandemic. The first known Italian SARS-CoV-2 positive case was reported on 21 February. In some countries, cases of suspected “COVID-19-like pneumonia” had been reported earlier than those officially accepted by health authorities. This has led many investigators to check preserved biological or environmental samples to see whether the virus was detectable on dates prior to those officially stated. With regard to Italy, the results of a microbiological screening in sewage samples collected between the end of February and the beginning of April 2020 from wastewaters in Milan (Northern Italy) and Rome (Central Italy) showed presence of SARS-CoV-2. In the present study, we evaluated, by means of a standardized diagnostic method, the SARS-CoV-2 infection prevalence amongst patients affected by severe acute respiratory syndrome (SARI) in an academic hospital located in Central Italy during the period of 1 November 2019–1 March 2020. Overall, the number of emergency room (ER) visits during the investigated period was 13,843. Of these, 1208 had an influenza-like syndrome, but only 166 matched the definition of SARI as stated in the study protocol. A total of 52 SARI cases were laboratory confirmed as influenza: 26 as a type B virus, 25 as a type A, and 1 as both viruses. Although about 17% of the total sample had laboratory or radiological data compatible with COVID-19, all the nasopharyngeal swabs stored underwent SARS-CoV-2 RT-PCR and tested negative. Based on our result, it is confirmed that the COVID-19 pandemic spread did not start prior to the “official” onset in central Italy. Routine monitoring of SARI causative agents at the local level is critical for reporting epidemiologic and etiologic trends that may differ from one country to another and also among different influenza seasons. This has a practical impact on prevention and control strategies

Hydroxyl vacancies in single-walled aluminosilicate and aluminogermanate nanotubes

We report the first theoretical study of hydroxyl vacancies in aluminosilicate and aluminogermanate single-walled metal-oxide nanotubes. The defects are modeled on both sides of the tube walls and lead to occupied and empty states in the band gap which are highly localized both in energy and in real space. We find different magnetization states depending on both the chemical composition and the specific side with respect to the tube cavity. The defect-induced perturbations to the pristine electronic structure are related to the electrostatic polarization across the tube walls and the ensuing change in Br{\o}nsted acid-base reactivity. Finally, the capacity to counterbalance local charge accumulations, a characteristic feature of these systems, is discussed in view of their potential application as insulating coatings for one-dimensional conducting nanodevices.Comment: manuscript: 4 pages, 4 figure

Macroscopic transport by synthetic molecular machines

Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with—and perform physical tasks in—the macroscopic world represents a significant hurdle for molecular nanotechnology. Here we describe a wholly synthetic molecular system that converts an external energy source (light) into biased brownian motion to transport a macroscopic cargo and do measurable work. The millimetre-scale directional transport of a liquid on a surface is achieved by using the biased brownian motion of stimuli-responsive rotaxanes (‘molecular shuttles’) to expose or conceal fluoroalkane residues and thereby modify surface tension. The collective operation of a monolayer of the molecular shuttles is sufficient to power the movement of a microlitre droplet of diiodomethane up a twelve-degree incline.

Clay-fulleropyrrolidine nanocomposites

In this work, we describe the insertion of a water-soluble bisadduct fulleropyrrolidine derivative into the interlayer space of three layered smectite clays. The composites were characterized by a combination of powder X-ray diffraction, transmission electron microscopy, X-ray photoemission and FTIR spectroscopies, and laser flash photolysis measurements. The experiments, complemented by computer simulations, give insight into the formation process, structural details, and properties of the fullerene/clay nanocomposites. The reported composite materials constitute a new hybrid system, where C-60 differs from its crystals or its solutions, and open new perspectives for the design and construction of novel C-60-based organic/clay hybrid materials.</p