Free energy and states of fractional-order hereditariness

Complex materials, often encountered in recent engineering and material sciences applications, show no complete separations between solid and fluid phases. This aspect is reflected in the continuous relaxation time spectra recorded in cyclic load tests. As a consequence the material free energy cannot be defined in a unique manner yielding a significative lack of knowledge of the maximum recoverable work that can extracted from the material. The non-uniqueness of the free energy function is removed in the paper for power-laws relaxation/creep function by using a recently proposed mechanical analogue to fractional-order hereditariness.     

Stochastic time-dependent current-density-functional theory

A time-dependent current-density-functional theory for many-particle systems in interaction with arbitrary external baths is developed. We prove that, given the initial quantum state |Psi0> and the particle-bath interaction operator, two external vector potentials A(r,t) and A'(r,t) that produce the same ensemble-averaged current density, j(r,t), must necessarily coincide up to a gauge transformation. This result greatly expands the applicability of time-dependent density-functional theory to open quantum systems, and allows for first-principles calculations of many-particle time evolution beyond Hamiltonian dynamics.     

Berechnung der dreidimensionalen laminaren Grenzschicht an schrägangeströmten Rotationskörpern mit Ablösung

Übersicht Es wird ein numerisches Verfahren zur Berechnung der dreidimensionalen laminaren Grenzschicht an schrägangeströmten Rotationskörpern beschrieben. Die reibungslose Geschwindigkcitsverteilung, die als äußere Randbedingung für die Grenzschichtrechnung dient, wird numerisch mittels eines Singularitätenverfahrens bestimmt. Die Grenzschichtrechnung wird in einem Stromlinienkoordinatensystem durchgeführt, d. h. die Koordinaten sind den Strom- und Potentiallinien der reibungsfreien Strömung angepaßt. Die allgemeinen Grenzschichtgleichungen werden numerisch mittels eines impliziten Differenzenverfahrens integriert. Als Ergebnis der numerischen Rechnung liegen die Grenzschicht-Geschwindigkeitsprofile in Primär- und Sekundärströmungsrichtung in allen Netzpunkten vor. Es wird dargelegt, daß mit diesem Verfahren die Bestimmung der dreidimensionalen Ablöselinie möglich ist. Die Ergebnisse der Grenzschichtrechnung und die Bestimmung der Ablöselinien stimmen sehr gut mit numerischen und analytischen Ergebnissen anderer Autoren überein.

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Summary A numerical method is presented to calculate the three dimensional laminar incompressible boundary layer over bodies of revolution at incidence. The inviscid flow velocities used for the boundary condition at the outer edge of the boundary layer are determined numerically by a singularity method. The boundary layer calculation is carried out in a streamline coordinate system; the coordinates are fixed to the streamlines and equipotential lines of the inviscid flow. The boundary layer equations are integrated by an implicit finite difference method. As a result of the numerical calculation process the velocity profiles in directions of streamlines and equipotential lines are known for each mesh point of the coordinate system. It is shown that this method can be used to determine the separation lines on the body surface. The results of the boundary layer calculation and the determination of flow separation arc in very good agreement with numerical and analytical results of other investigators.

     

Quasi-periodic water waves

We present the result and the ideas of the recent paper (Berti and Montalto, Quasi-periodic standing wave solutions of gravity-capillary water waves, http://arxiv.org/abs/1602.02411, 2016) concerning the existence of Cantor families of small-amplitude time quasi-periodic standing wave solutions (i.e. periodic and even in the space variable x) of a 2-dimensional ocean, with infinite depth, in irrotational regime, under the action of gravity and surface tension at the free boundary. These quasi-periodic solutions are linearly stable.     

Spatio-Temporal Variation of the Bacterial Communities along a Salinity Gradient within a Thalassohaline Environment (Saline di Tarquinia Salterns,Italy)

The “Saline di Tarquinia” salterns have been scarcely investigated regarding their microbiological aspects. This work studied the structure and composition of their bacterial communities along the salinity gradient (from the nearby sea through different ponds). The communities showed increasing simplification of pond bacterial diversity along the gradient (particularly if compared to those of the sea). Among the 38 assigned phyla, the most represented were Proteobacteria, Actinobacteria and Bacteroidetes. Differently to other marine salterns, where at the highest salinities Bacteroidetes dominated, preponderance of Proteobacteria was observed. At the genus level the most abundant taxa were Pontimonas, Marivita, Spiribacter, Bordetella, GpVII and Lentibacter. The α-diversity analysis showed that the communities were highly uneven, and the Canonical Correspondence Analysis indicated that they were structured by various factors (sampling site, sampling year, salinity, and sampling month). Moreover, the taxa abundance variation in relation to these significant parameters were investigated by Generalized Linear Models. This work represents the first investigation of a marine saltern, carried out by a metabarcoding approach, which permitted a broad vision of the bacterial diversity, covering both a wide temporal span (two years with monthly sampling) and the entire salinity gradient (from the nearby sea up to the crystallisation ponds).     

Natural Compounds and Products from an Anti-Aging Perspective

Aging is a very complex process that is accompanied by a degenerative impairment in many of the major functions of the human body over time. This inevitable process is influenced by hereditary factors, lifestyle, and environmental influences such as xenobiotic pollution, infectious agents, UV radiation, diet-borne toxins, and so on. Many external and internal signs and symptoms are related with the aging process and senescence, including skin dryness and wrinkles, atherosclerosis, diabetes, neurodegenerative disorders, cancer, etc. Oxidative stress, a consequence of the imbalance between pro- and antioxidants, is one of the main provoking factors causing aging-related damages and concerns, due to the generation of highly reactive byproducts such as reactive oxygen and nitrogen species during the metabolism, which result in cellular damage and apoptosis. Antioxidants can prevent these processes and extend healthy longevity due to the ability to inhibit the formation of free radicals or interrupt their propagation, thereby lowering the level of oxidative stress. This review focuses on supporting the antioxidant system of the organism by balancing the diet through the consumption of the necessary amount of natural ingredients, including vitamins, minerals, polyunsaturated fatty acids (PUFA), essential amino acids, probiotics, plants’ fibers, nutritional supplements, polyphenols, some phytoextracts, and drinking water.     

Embedding a novel objective function in a two-phased local search for robust vertex coloring

In this paper, we propose a two-phased local search for vertex coloring. The algorithm alternately executes two closely interacting functionalities, i.e., a stochastic and a deterministic local search. The stochastic phase is basically based on biased random sampling that, according to a probability matrix storing the probability a vertex can be assigned to a color, iteratively constructs feasible colorings. The deterministic phase, instead, consists in assigning sequentially, according to a given ordering, each vertex to the color which causes the lowest increase of the solution penalty, and then, when the schedule is constructed, swap operations are executed to improve the performance. The interaction between the two phases is implemented by tunnelling information of what happened during a phase to the successive ones. Beyond the algorithm scheme, the novelty of the approach stems from the fact that the objective function is not minimizing the number of colors but a new penalty function. The proposed approach is tested on known benchmarks for the studied problem available on the public domain. From a comparison to the state of the art it appears that the proposed approach is robust and is able to achieve best known results.     

Determination of cobalt in the presence of high concentrations of zinc by differential pulse polarography

Summary Cobalt(II) can be determined in 0.1 mol/l Na₃citrate + 0.1 mol/l NH₄Cl + 0.08% dimethylglyoxime as supporting electrolyte in the presence of a 50 000-fold excess of zinc by differential pulse polarography. The limit of determination is 4.2×10^–5 mol/l Co (2.5 mg/l). Linear calibration curves are obtained within the range of 1×10^–7 to 5×10^–6 mol/l cobalt without zinc and in the presence of 5×10^–3 mol/l Zn. The analytical method developed is suitable for the determination of cobalt in zinc plant solutions.

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Cobaltbestimmung in Gegenwart hoher Zinkkonzentrationen mit Hilfe der Differential-Puls-Polarographie