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Functionally graded materials raise considerable interest in the biomedical research. In particular, gyroid structures are suitable for bone tissue engineering applications, allowing to emulate the porosity of the inner part of the bone. In this frame, the mechanical properties of 17–4 PH steel gyroids made by additive manufacturing have been investigated. Three design methods have been implemented, i.e., thickness graded, size graded, and uniform, to address the lack of knowledge in the area of stainless-steel scaffolds aiming at providing a map of the mechanical properties. Compressive mechanical properties absorbed energy and absorption efficiency have been found for the aforementioned design methods. Furthermore, defects and collapse behavior have been analyzed: imperfections have been detected in the thin-walled areas of the graded samples. Nevertheless, under given conditions, the graded samples have mechanical properties comparable to those of uniform ones, exhibiting a controlled layer-by-layer collapse mechanism and consequent weight reduction. The Gibson-Ashby models have been implemented, and the calibration coefficients have been compared with other research works. A FEM-based numerical model has been proposed to reproduce the mechanical properties of the mentioned structures finding critical issues in the representation of defects. In this frame, the resulting Gibson Ashby calibration coefficients are in good agreement with the literature and reveal the graded samples have a bending-dominating behavior sustaining larger strains than the uniform case, giving the ground for high energy absorption applications. Furthermore, the FEM analyses are in good agreement with the literature providing a reliable tool to further investigate the metal functionally graded gyroid field.

Many problems related to the efficiency of tribological steel substrates have been improved by theintroduction of ceramic coatings based on nitrides of transition metals, as applied by physical vapordeposition (PVD) [1]. Multilayer PVD coatings are currently being developed so as to achieve a furtherincrease in performance from both tribological and corrosion resistance. The principle of the method is tocreate a coating characterized by a high number of layers stacked in such a way as to block the growth of thecolumnar structure with high porosity. In this work a series of mono-and multilayer coatings were taken intoaccount. These consist of CrN and Cr multilayers coatings made in a deposition chamber using cathodic arcPVD at the company CRT. As steel substrate AISI H11was chosen in the following surface state conditions:mirror finish, electroeroded, ground and sandblasted

Clinical and biological studies have proved that compounds of pomegranate juice reduce blood pressure and low density lipoprotein (LDL) oxidation and exhibit anticarcinogenic, antimicrobial, antiviral and antiatherosclerotic activity. These activities have been attributed to its phenolic fraction containing a significantly high level of hydrolyzable tannins, as well as anthocyanins (delphinidin, cyanidin, pelargonidin 3-glucoside and pelargonidin 3,5-diglucoside), which exhibit a high antioxidant activity. Consequently, industries producing pomegranate juice have increased significantly in recent years, as well as pharmaceutical companies, which extract health-beneficial compounds from the fruit. Besides, recent interest in anthocyanins has arisen not only due to their potential health benefits but also to their use as natural colorants. Fractionation and purification of anthocyanins using membrane technologies is of interest because the low temperatures involved imply that thermal degradation of these compounds can be avoided. This study aimed at determining the feasibility of using ultrafiltration (UF) to separate and purify anthocyanin compounds from the clarified pomegranate juice. Various UF membranes (Desal GK, from GE Water & Process Technologies, PES 004 from Microdyn Nadir, Etna 01 PP from Alfa Laval and MPF 36 from Koch) with different molecular weight cut-off (1, 2 and 4 kDa) and membrane material (fluoropolymer, polyamide and polyethersulphone) were evaluated in terms of productivity, fouling index and retention coefficients towards anthocyanins (delphinidin, cyanidin, pelargonidin-3-glucosides and 3,5-diglucosides), glucose, fructose, total phenolics and total antioxidant activity (TAA). All selected membranes exhibited a high retention of anthocyanins (in the range 72-98%); however, the Desal GK membrane (polyamide, 2 kDa) exhibited the lowest retention towards glucose and fructose (in the range 1-4%) when compared with the other investigated membranes. Operating at a transmembrane pressure (TMP) of 15 bar and a temperature of 27 °C according to a batch concentration mode, steady-state permeate fluxes of about 17 kg/m2h were obtained. In these conditions retentions towards different anthocyanins were in the range 82-90%. For phenolic compounds and total antioxidant activity (TAA) rejections were of 87 and 79%, respectively. This membrane was characterized by a steady increase of permeate flux and a higher retention of total soluble solids and phenolic compounds when TMP increased (Figure 1). An improved separation of anthocyanins from glucose and fructose was achieved through a diafiltration of the UF retentate.

On the welding of different materials by a diode laser

Poland

Barcelona, Spain