Characterisation of pressure fluctuations on the leeward and side faces of rectangular buildings and accuracy of the quasi-steady loads

Equivalent static loads on buildings are usually evaluated following the quasi-steady approach, assuming that instantaneous approaching wind velocities are directly translated into surface pressures at all points on the building faces. Such an approach is in contrast with the actual nature of pressures, acting on the faces, exposed to a separated flow. For these, mean and fluctuating pressures are not directly related to the characteristics of the oncoming flow and, to an even lesser extent are fully correlated to those acting at corresponding points on the windward surfaces. To investigate the characteristics of the pressure fluctuations on the leeward and side faces of medium-rise, rectangular plan buildings and to quantify the error associated with the quasi-steady assumption, in this paper the results of wind tunnel pressure measurements are discussed. The characteristics of fluctuating pressures and the equivalent static load are compared with those arising from the application of the quasi-steady approach and from the use of codes of practice.     

Synthesis of Alkyl‐Functionalized Hyperbranched Polymers and Their Use as Additives in Cationic Photopolymerization of Epoxy Resins

Summary: An alkyl‐functionalized hyperbranched polymer, HBP(OH)–C16, was synthesized by partial modification with fatty acid of an aromatic‐aliphatic OH‐terminated hyperbranched polyester HBP? OH. This product was used as additive in the cationic photopolymerization of an epoxy resin. The alkyl‐modified polyester takes part in the photopolymerization process thanks to the residual OH groups by means of chain‐transfer reactions. An increase of the epoxy conversion is observed by increasing the amount of the HBP additive in the photocurable resin with a modification of the bulk properties of the final ultraviolet‐cured films. The presence of HBP(OH)–C16 induces an increase in glass transition temperature, thermal stability, and solvent resistance. Moreover the surface properties of the films are modified achieving highly hydrophobic surfaces in the presence of even very low amounts of HBP(OH)–C16.

Structure of HBP–C16.     

Hypergravity effects on myoblast proliferation and differentiation

This study aimed at the investigation of behavior of myoblasts in conditions of altered gravity. C2C12 cells underwent stimulations by different hypergravity intensities (2 h at 5 g, 10 g, and 20 g) in the Large Diameter Centrifuge of the European Space Agency (ESA), highlighting positive effects on both proliferation and differentiation.     

Laminated composite rectangular and annular plates: A GDQ solution for static analysis with a posteriori shear and normal stress recovery

The Generalized Differential Quadrature (GDQ) Method is applied to study laminated composite degenerate shell panels such as rectangular and annular plates. The theoretical treatment is maintained general in order to expose in a unique way the procedure adopted to obtain the stress profiles through the thickness of plates without specifying the equations for rectangular and annular plates. By simply imposing some geometrical relations the equations governing the problem of plates under consideration, that are degenerate shells, are inferred from the theory of shells of revolution. The mechanical model is based on the so called First-order Shear Deformation Theory (FSDT) deduced from the three-dimensional theory in order to analyse the above moderately thick structural elements. The solution is given in terms of generalized displacement components of points lying on the middle surface of the plate. After the solution of the fundamental system of equations in terms of displacements and rotations, the generalized strains and stress resultants are evaluated by applying the Differential Quadrature rule to the generalized displacements. The transverse shear and normal stress profiles through the laminate thickness are reconstructed a posteriori by using local three-dimensional elasticity equilibrium equations. No preliminary recovery or regularization procedure on the extensional and flexural strain fields is needed when the Differential Quadrature technique is used. By using GDQ procedure through the thickness, the reconstruction procedure needs only to be corrected to properly account for the boundary equilibrium conditions. In order to verify the accuracy of the present method, GDQ results are compared with the ones obtained with semi-analytical formulations and with 3D finite element methods. Stresses of several composite plates are evaluated. Very good agreement is observed without using mixed formulations and higher order kinematical models. Various examples of stress profiles for rectangular and annular plate elements are presented to illustrate the validity and the accuracy of GDQ method.     

ZnO nanowire arrays as substrates for cell proliferation and differentiation

In the latest years, the use of zinc oxide (ZnO) nanostructures has been proposed in different biomedical applications, however, to date, only a few contrasting results concerning their biocompatibility can be found in the literature. In particular, the application of the extraordinary piezoelectric properties of ZnO nanostructures has poorly been explored for the culture of electrically excitable cells, and, for this reason, systematic investigations of their interactions with these living systems appear to be necessary. In this paper, we report about adhesion, proliferation and differentiation of two mammalian cell lines (PC12, as model of neuronal cells, and H9c2, as model of muscle cells) over ZnO nanowire arrays. We demonstrate suitability of these arrays in sustaining cellular functions, and their potential in applications that range from tissue engineering to minimally invasive sensing and/or stimulation.     

Evaluation of the sensory and physical properties of meat and fish derivatives containing grape pomace powders

The wine industry produces tons of pomace that, in a circular economy model, should be valorised. The phenols fraction of grape pomace represents a source of food colorants, but also of natural food preservatives. Furthermore, the pomace contains dietary fibre, unsaturated lipids, antioxidants and minerals that have been recognised as wholesome and technologically useful. The main drawback of using grape pomace is represented by its chemical and microbiological instability. Different authors proposed strategies to overcome these limitations, and different approaches for the use of grape pomace as an ingredient have been described. Here, we sum up the chemical and microbiological solutions for the stabilisation of grape pomace, describing the approaches used to transform this waste in a functional ingredient, and comparing the physiochemical characteristics of the resulting products. We further describe the studies concerning sensory aspects of the products by enriching animal fleshes with different pomace powder preparations.     

Characterization and Discrimination of Ancient Grains: A Metabolomics Approach

Hulled, or ancient, wheats were the earliest domesticated wheats by mankind and the ancestors of current wheats. Their cultivation drastically decreased during the 1960s; however, the increasing demand for a healthy and equilibrated diet led to rediscovering these grains. Our aim was to use a non-targeted metabolomic approach to discriminate and characterize similarities and differences between ancient Triticum varieties. For this purpose, 77 hulled wheat samples from three different varieties were collected: Garfagnana T. turgidum var. dicoccum L. (emmer), ID331 T. monococcum L. (einkorn) and Rouquin T. spelta L. (spelt). The ultra high performance liquid chromatography coupled to high resolution tandem mass spectrometry (UHPLC-QTOF) metabolomics approach highlighted a pronounced sample clustering according to the wheat variety, with an excellent predictability (Q²), for all the models built. Fifteen metabolites were tentatively identified based on accurate masses, isotopic pattern, and product ion spectra. Among these, alkylresorcinols (ARs) were found to be significantly higher in spelt and emmer, showing different homologue composition. Furthermore, phosphatidylcholines (PC) and lysophosphatidylcholines (lysoPC) levels were higher in einkorn variety. The results obtained in this study confirmed the importance of ARs as markers to distinguish between Triticum species and revealed their values as cultivar markers, being not affected by the environmental influences.     

Soap film analogy for anisotropically stretched membranes and cable nets

Analogical physical models are a preferred technique to intuitively grasp complex engineering problems. It is well-known that the equilibrium minimal-surface configuration of membranes under equibiaxial tension can be visually represented by the surface of a soap film under equivalent boundary conditions, but this analogy fails when the stress state is not uniform equibiaxial. We extend to this situation the analogy with soap films. The equilibrium state of an orthotropically tensioned membrane is found by geometrically stretching the shape of a soap film, in a precise manner depending upon the applied state of stress. The procedure is easily done by elaborating digital pictures. The method is mathematically justified under the kinematic hypotheses of small strains and large rotations, and further verified in a parametric design environment. It can also provide an insight into the equilibrium configuration of cable-nets, when the stresses in the warp and weft directions are considerably different. Furthermore, this visualization favors implementing transformable shapes for membranes or orthogonal cable nets, as a consequence of a modification of the ratio of the principal stress components.