Modeling the flow over superhydrophobic and liquid-impregnated surfaces

Superhydrophobic (SH) and liquid-impregnated surfaces (LIS) represent an interesting technique for the possible reduction of drag in applications involving the flow of liquids over solid surfaces, for a wide range of Reynolds number, from laminar to turbulent conditions. Such coatings work by the interposition of a gas/oil layer between the liquid and the solid wall, trapped by distributed microscopic roughness elements present at the wall; over the gas layer the liquid can flow with negligible friction. The present activity is focused on the numerical modeling of the slippage over such coatings and on their drag reduction performance in the turbulent regime. The problem is subdivided into two parts: a microscopic problem, accounting for the flow in the proximity of the roughness elements and a macroscopic problem, accounting for the turbulent flow over SHS/LIS, where the effect of the slippage at the wall is modeled through a proper boundary condition. The near-wall, microscopic problem, governed by the Stokes equation, is recast into an integral form and then solved using a boundary element method. The aim of the microscopic calculations, performed by varying the viscosity ratio between the fluids, is to obtain the values of the slip lengths, used to quantify slippage. The slip length are then used in the definition of Navier boundary condition, applied at the walls of a turbulent channel flow at moderate Reynolds number, solved by direct numerical simulations. The results are in excellent agreement with a theoretical model available in the literature

Analytical approaches for discriminating native lard from other animal fats

Establishing the distinguishable characteristics of lard from other common animal fats might be helpful for authentication initiatives in foods and feeds. In this study, fatty acid and triacylglycerol compositions, thermal and spectroscopic characteristics of native lard (NL), respectively, were compared with those of beef tallow (BT), mutton tallow (MT), and chicken fat (CF) by using gas liquid chromatography (GLC), high-performance liquid chromatography (HPLC), and differential scanning calorimetry (DSC). GLC analysis showed that the comparison of the overall fatty acid data might not be suitable for the discrimination of different animal fats, but the use of the principal component analysis and the percent palmitic acid enrichment factor [PAEF (%)] calculations were useful. HPLC analysis showed that NL displayed a TAG profile, which was quite different from those of either BT or MT, but appeared to be closely similar to that of CF. Results of DSC thermal analysis showed that both melting and crystallization curves of NL were remarkably different from those of other animal fats

Las dos discusiones : (Una ponencia sui generis sobre el rol de la ciencia en la discusión pública sobre mega minería)

Según entiendo, estamos pensando en el contexto de una discusión acerca de la mega minería, que en términos brutales es dicotómica: mega minería sí o no. Ese debate puede ser desconcertante para el neófito. A primera vista parece haber hombres de valía que apoyan esos emprendimientos, y hombres de valía que no. Esa observación invalida la utilización de un argumento que hoy suele esgrimirse en los foros de la discusión política, y del que tiendo a desconfiar porque equivale a una suspensión mecánica del juicio crítico, y es también una declaración de impotencia argumentativa, que es aquel del antialineamiento automático: me basta saber quiénes se oponen para estar a favor. Es un argumento peligroso, porque supone que los opositores nunca se equivocan. Si se aplica a rajatabla, basta con que uno se equivoque para que haya dos extraviados.Cátedra Libre Ciencia, Política y Socieda

Stabilization of Arthrospira platensis with high-pressure processing and thermal treatments: Effect on physico-chemical and microbiological quality

Arthrospira platensis (Spirulina) is a cyanobacterium that has been recently studied for food applications due to its high biological and nutritional value. When A. platensis is used as an ingredient in food applications, proper treatments have to be applied in order to reduce microbial contamination. This work compared the effect of thermal treatments (sterilization at 121℃ and pasteurization at 90℃) and high-pressure processing (400, 600 MPa) on the chemical, physico-chemical, and microbial quality of 5% (wt/vol) A. platensis aqueous suspensions. Total antioxidant capacity, total polyphenols content, color, and pigments content were not strongly lowered/modified by the high-pressure processing (HPP) treatments. HPP at 400 MPa even improved the release of C-phycocyanin from the biomass because of the breakage of cell walls. HPP treatments were comparable to pasteurization in reducing yeasts, coliforms, Staphylococci, and total bacterial count. Conversely, sterilization was the only treatment that guaranteed the inactivation of spore-forming species but affecting the final quality. Novelty impact statement: High-pressure processing (HPP) treatments were found to be a good strategy to preserve or even improve some physical and chemical properties of Arthrospira platensis (Spirulina), in particular antioxidant capacity, polyphenols, color, and pigments content. Furthermore, HPP treatments were comparable to pasteurization in reducing microbial cell count, while sterilization was the only treatment able to ensure the inhibition of spore-forming species

Lactobacillus paracasei 4341 as adjunct culture to enhance flavor in short ripened Caciotta-type cheese

Caciotta is the name used to define a type of Italian semi-hard cheese Caciotta-type cheese. Due to the short ripening time, pasteurization is necessary to eliminate the potential pathogenic bacteria, which may be present in raw milk, causing also the reduction of ripened cheese flavor. The purpose of this research was to evaluate the effect of a selected wild Lactobacillus paracasei strain experimentally used as adjunct culture to enhance the flavour formation in a short-ripened caciotta-type cheese. An integrated polyphasic approach was used to compare the experimental and control Caciotta produced in a company located in Emilia Romagna region (Italy). It was demonstrated how the L. paracasei 4341 was able to develop in curd and cheese interacting with the acidifying commercial starter. The main acidifying starter species, were differently affected by the presence of the adjunct culture. Streptococcus thermophilus shown comparable behavior in all cheese-making step of control and experimental Caciotta, while Lactobacillus delbrueckii subsp bulgaricus, growth was slowed down by the presence of the adjunct culture during the whole ripening time. The higher amount of volatile compounds and organic acids due to the adjunct L. paracasei 4341 lead to a clear differentiation of the experimental Caciotta respect to the control, in terms of aromatic profile, color, texture and sensorial perception

A New Photoactivatable Ruthenium(II) Complex with an Asymmetric Bis-Thiocarbohydrazone: Chemical and Biological Investigations

The synthesis, photoactivation and biological activity of a new piano-stool Ru(II) complex is herein reported. The peculiarity of this complex is that its monodentate ligand which undergoes the photodissociation is an asymmetric bis-thiocarbohydrazone ligand that possesses a pyridine moiety binding to Ru(II) and the other moiety contains a quinoline that endows the ligand with the capacity of chelating other metal ions. In this way, upon dissociation, the ligand can be released in the form of a metal complex. In this article, the double ability of this new Ru(II) complex to photorelease the ligand and to chelate copper and nickel is explored and confirmed. The biological activity of this compound is studied in cell line A549 revealing that, after irradiation, proliferation inhibition is reached at very low half maximal inhibitory concentration (IC50) values. Further, biological assays reveal that the dinuclear complex containing Ni is internalized in cells