Dimensional synthesis of the optimal RSSR mechanism for a set of variable design parameters

This paper deals with the dimensional synthesis of the RSSR mechanism, also known as spatial four-bar linkage (R and S stand for revolute and spherical kinematic pairs respectively). To univocally describe the geometry of the RSSR mechanism a specific set of geometry parameters is necessary. Generally speaking, in a synthesis problem a subset of these parameters, defined as design parameters, is usually considered as assigned whereas the remaining ones, defined as design variables, have to be found by the synthesis procedure. That is, the goal of the synthesis procedure is to find the values of the design variables, while satisfying both functional requirements of the mechanism and constraints on the design parameters. In this paper each design parameter is assigned as variable within a given range rather than being assigned as a single value. In general, varying a design parameter means obtaining a different mechanism which has different functional performances as a consequence. This feature gives raise to a novel synthesis problem, which has not been treated in the literature yet. In particular, the RSSR mechanism synthesis presented in this paper takes the optimization of the force transmission as an objective function, while referring to a given range of values of each design parameter. In addition, prescribed constraints on given extreme angular positions for both the input and the output links, on the upper and lower bounds for the transmission ratio, and on the upper and lower bounds for the design variable values have to be satisfied. The synthesis problem, set as a constrained minimization problem, is solved numerically in two steps by means of a Genetic algorithm followed by a quasi-Newton algorithm. As an example of application, a dimensional synthesis of an RSSR mechanism used in a hand exoskeleton is reported.     

Nutraceutical Potential of Leaf Hydro-Ethanolic Extract of the Edible Halophyte Crithmum maritimum L.

Aromatic halophytes represent an exceptional source of natural bioactive compounds for the food industry. Crithmum maritimum L., also known as sea fennel, is a halophyte plant colonizing cliffs and coastal dunes along Mediterranean and Atlantic coasts. It is well known to produce essential oils and polyphenols endowed with antioxidant and biological effects. The present work reports the phytochemical profile, as well as antioxidant, antimicrobial and antimutagenic properties of C. maritimum leaf hydro-alcoholic extract. From LC-ESI-MS analysis, eighteen phenolic compounds were depicted in sea fennel extract and the amount of total phenolic content exceeds 3% DW. Accordingly, C. maritimum extract showed strong antioxidant activities, as evidenced by in vitro (DPPH, ORAC, FRAP) and ex vivo (CAA-RBC and hemolysis) assays. An important antimicrobial activity against pathogenic strains was found as well as a strong capacity to inhibit Staphylococcus aureus (ATCC 35556) biofilm formation. Sea fennel extracts showed a significant decrease of mutagenesis induced by hydrogen peroxide (H₂O₂) and menadione (ME) in Saccharomyces cerevisiae D7 strain. In conclusion, our results show that C. maritimum is an exceptional source of bioactive components and exert beneficial effects against oxidative or mutagenic mechanisms, and pathogenic bacteria, making it a potential functional food.     

The quantitative Faber–Krahn inequality for the Robin Laplacian

We prove a quantitative form of the Faber–Krahn inequality for the first eigenvalue of the Laplace operator with Robin boundary conditions. The asymmetry term involves the square power of the Fraenkel asymmetry, multiplied by a constant depending on the Robin parameter, the dimension of the space and the measure of the set.     

On the Existence of Weak Solutions for a 1-D Free-Boundary Concrete Carbonation Problem

In this paper we deal with a one-dimensional free-boundary problem arising in the modeling of concrete carbonation process. More precisely, we investigate global existence, uniqueness and large-time behavior of weak solutions for the problem under consideration. We also obtain the existence of a weak solution when the measure of the initial domain vanishes.     

<Emphasis Type="Italic">b</Emphasis>-Generalized Skew Derivations on Lie Ideals

Let R be a non-commutative prime ring, Z(R) its center, Q its right Martindale quotient ring, C its extended centroid, \(F\ne 0\) an b-generalized skew derivation of R, L a non-central Lie ideal of R, \(0\ne a\in R\) and \(n\ge 1\) a fixed integer. In this paper, we prove the following two results:

1. 1.
   If R has characteristic different from 2 and 3 and \(a[F(x),x]^n=0\), for all \(x\in L\), then either there exists an element \(\lambda \in C\), such that \(F(x)=\lambda x\), for all \(x\in R\) or R satisfies \(s_4(x_1,\ldots ,x_4)\), the standard identity of degree 4, and there exist \(\lambda \in C\) and \(b\in Q\), such that \(F(x)=bx+xb+\lambda x\), for all \(x\in R\).
    
2. 2.
   If \(\mathrm{{char}}(R)=0\) or \(\mathrm{{char}}(R) > n\) and \(a[F(x),x]^n\in Z(R)\), for all \(x\in R\), then either there exists an element \(\lambda \in C\), such that \(F(x)=\lambda x\), for all \(x\in R\) or R satisfies \(s_4(x_1,\ldots ,x_4)\).
    

     

Non-symmetrical composite-based path modeling

Partial least squares path modeling presents some inconsistencies in terms of coherence with the predictive directions specified in the inner model (i.e. the path directions), because the directions of the links in the inner model are not taken into account in the iterative algorithm. In fact, the procedure amplifies interdependence among blocks and fails to distinguish between dependent and explanatory blocks. The method proposed in this paper takes into account and respects the specified path directions, with the aim of improving the predictive ability of the model and to maintain the hypothesized theoretical inner model. To highlight its properties, the proposed method is compared to the classical PLS path modeling in terms of explained variability, predictive relevance and interpretation using artificial data through a real data application. A further development of the method allows to treat multi-dimensional blocks in composite-based path modeling.     

Artificial nanomachines based on interlocked molecular species: recent advances

The bottom-up construction and operation of nanoscale machines and motors, that is, supramolecular systems wherein the molecular components can be set in motion in a controlled manner for ultimately accomplishing a function, is a topic of great interest in nanoscience and a fascinating challenge of nanotechnology. The field of artificial molecular machines and motors is growing at an astonishing rate and is attracting a great deal of interest. Research in the last decade has shown that species made of interlocked molecular components like rotaxanes, catenanes and related systems are most attractive candidates. In recent times, the evolution of the structural and functional design of such systems has led to the construction and operation of complex molecular machines that, in some cases, are able to do specific tasks. This tutorial review is intended to discuss the design principles for nanomachines based on interlocked molecules, and to provide a timely overview on representative prototype systems.     

Cocentralizing derivations and nilpotent values on Lie ideals

Let R be a prime ring with char R ≠ 2, L a non-central Lie ideal of R, d, g non-zero derivations of R, n ≥ 1 a fixed integer. We prove that if (d(x)x − xg(x)) ⁿ = 0 for all x ∈ L, then either d = g = 0 or R satisfies the standard identity s ₄ and d, g are inner derivations, induced respectively by the elements a and b such that a + b ∈ Z(R).     

Harnack type estimates and Hölder continuity for non-negative solutions to certain sub-critically singular parabolic partial differential equations

A two-parameter family of Harnack type inequalities for non-negative solutions of a class of singular, quasilinear, homogeneous parabolic equations is established, and it is shown that such estimates imply the Hölder continuity of solutions. These classes of singular equations include p-Laplacean type equations in the sub-critical range ${1 < p \le\frac{2N}{N+1}}$ and equations of the porous medium type in the sub-critical range ${0 < m \le\frac{(N-2)_+}{N}}$ .     

Polyphenolic characterisation of plant mixture (Lisosan® Reduction) and its hypocholesterolaemic effect in high fat diet-fed mice

Lisosan® Reduction is a plant mixture produced from powder of fermented Triticum aestivum (Lisosan® G), Desmodium adscendens, Malus domestica, Picrorhiza kurroa and Hordeum vulgare. The aim of this study was to characterise the phenolic profile of Lisosan® Reduction and to evaluate the effects of aqueous extract on mice fed a high fat diet (HFD). Syringic acid, trans sinapic acid and neochlorogenic acid were identified by HPLC-DAD to be the dominant polyphenols of Lisosan® Reduction, followed by vitexin, trans p-coumeric acid and trans ferulic acid. Mice treated with aqueous extract of Lisosan® Reduction (60 mg/kg b.w.) showed a significant decrease of serum cholesterol, glucose and triglycerides level and a significant increase of CYP7A1 gene expression, compared to HFD group.