Rheological and volumetric properties of TiO2-ethylene glycol nanofluids

Homogeneous stable suspensions obtained by dispersing dry TiO₂ nanoparticles in pure ethylene glycol were prepared and studied. Two types of nanocrystalline structure were analyzed, namely anatase and rutile phases, which have been characterized by scanning electron microscopy. The rheological behavior was determined for both nanofluids at nanoparticle mass concentrations up to 25%, including flow curves and frequency-dependent storage and loss moduli, using a cone-plate rotational rheometer. The effect of temperature over these flow curve tests at the highest concentration was also analyzed from 283.15 to 323.15 K. Furthermore, the influence of temperature, pressure, nanocrystalline structure, and concentration on the volumetric properties, including densities and isobaric thermal expansivities, were also analyzed.     

Self‐assembled nanostructures: preparation,characterization, thermal,optical and morphological characteristics of amphiphilic diblock copolymers based on poly(2‐hydroxyethyl methacrylate‐block‐N‐phenylmaleimide)

A series of well‐defined amphiphilic poly[(2‐hydroxyethyl methacrylate)‐block‐(N‐phenylmaleimide)] diblock copolymers containing hydrophilic and hydrophobic blocks of different lengths were synthesized by atom transfer radical polymerization. The properties of the diblock copolymers and their ability to form large compound spherical micelles are described. Their optical, morphological and thermal properties and self‐assembled structure were also investigated. The chemical structure and composition of these copolymers have been characterized by elemental analysis, Fourier transform infrared, ¹H NMR, UV–visible and fluorescence spectroscopy, and size exclusion chromatography. Furthermore, the self‐assembly behavior of these copolymers was investigated by transmission electron microscopy and dynamic light scattering, which indicated that the amphiphilic diblock copolymer can self‐assemble into micelles, depending on the length of both blocks in the copolymers. These diblock copolymers gave rise to a variety of microstructures, from spherical micelles, hexagonal cylinders to lamellar phases. © 2013 Society of Chemical Industry     

Fracture energy in structural adhesive joints of composite-aluminum under adverse environments conditions

This work analyzes the degradation of composite-aluminum adhesive joints when they are exposed to the weathering and environmental pollution in Madrid for a long period of time. Two adhesives (epoxy and polyurethane) and several surface treatments for adherends have been considered. End-notched flexure bending tests have been performed to evaluate the loss of mechanical properties (failure stress and fracture energy) of adhesive joints that were exposed to the weathering and environmental pollution. Tests results have shown that the environmental degradation of the adhesive leads to a loss of mechanical properties in the adhesive joints. Considering the relative percentage, the reduction of failure stress in the polyurethane is higher than in the epoxy (31.9% for the polyurethane and 21.1% for the epoxy). Similarly and considering relative percentage, fracture energy reduction is 42.0% for polyurethane and 41.5% for epoxy. Likewise, tests have shown that the loss of mechanical properties does not decrease linearly with the time when the samples have been exposed to the weathering. This reduction occurs during the first few weeks. In summary, tests results have allowed to conclude that adhesive joints with epoxy resist the environmental pollution better than the adhesive joints with polyurethane.     

Selective Inhibition of an Apicoplastic Aminoacyl‐tRNA Synthetase from Plasmodium falciparum

The resistance of malaria parasites to available drugs continues to grow, and this makes the need for new antimalarial therapies pressing. Aminoacyl‐tRNA synthetases (ARSs) are essential enzymes and well‐established antibacterial targets and so constitute a promising set of targets for the development of new antimalarials. Despite their potential as drug targets, apicoplastic ARSs remain unexplored. We have characterized the lysylation system of Plasmodium falciparum, and designed, synthesized, and tested a set of inhibitors based on the structure of the natural substrate intermediate: lysyl‐adenylate. Here we demonstrate that selective inhibition of apicoplastic ARSs is feasible and describe new compounds that that specifically inhibit Plasmodium apicoplastic lysyl‐tRNA synthetase and show antimalarial activities in the micromolar range.     

Heparin Modulates the Mitogenic Activity of Fibroblast Growth Factor by Inducing Dimerization of its Receptor. A 3D View by Using NMR

In vitro mitogenesis assays have shown that sulfated glycosaminoglycans (GAGs; heparin and heparan sulfate) cause an enhancement of the mitogenic activity of fibroblast growth factors (FGFs). Herein, we report that the simultaneous presence of FGF and the GAG is not an essential requisite for this event to take place. Indeed, preincubation with heparin (just before FGF addition) of cells lacking heparan sulfate produced an enhancing effect equivalent to that observed when the GAG and the protein are simultaneously added. A first structural characterization of this effect by analytical ultracentrifugation of a soluble preparation of the heparin‐binding domain of fibroblast growth factor receptor 2 (FGFR2) and a low molecular weight (3 kDa) heparin showed that the GAG induces dimerization of FGFR2. To derive a high resolution structural picture of this molecular recognition process, the interactions of a soluble heparin‐binding domain of FGFR2 with two different homogeneous, synthetic, and mitogenically active sulfated GAGs were analyzed by NMR spectroscopy. These studies, assisted by docking protocols and molecular dynamics simulations, have demonstrated that the interactions of these GAGs with the soluble heparin‐binding domain of FGFR induces formation of an FGFR dimer; its architecture is equivalent to that in one of the two distinct crystallographic structures of FGFR in complex with both heparin and FGF1. This preformation of the FGFR dimer (with similar topology to that of the signaling complex) should favor incorporation of the FGF component to form the final assemblage of the signaling complex, without major entropy penalty. This cascade of events is probably at the heart of the observed activating effect of heparin in FGF‐driven mitogenesis.     

Perpendicular Alignment of 2D Nanoplatelet Emitters in Electrospun Fibers: A Result of the Barus Effect?

Stable jet electrospinning (SJES) is a special form of optical fiber generation that prevents chaotic fiber whipping typical for conventional electrospinning procedures. Incorporation of highly emissive semiconductor nanoplatelets (NPLs) in such fibers has very high potential in optical data transmission, optological circuits, fiber lasers, solar light concentrators and many other fields because NPLs exhibit strongly directed emission from their surface plane due to various in-plane transition dipole moments. However, potential orientation control of 2D-NPLs in SJES is entirely unknown as electric fields and various mechanical forces contribute in a complex manner simultaneously. Here, the observation of counter-intuitive yet very beneficial orientation of rectangular CdSe/CdS 2D-NLP in SJES perpendicular to the fiber drawing axis is reported. Scanning electron microscopy, 3D-single particle excitation polarization microscopy, 3D-photogoniometry, polarized emission spectroscopy and small angle X-ray scattering (SAXS) demonstrate aggregation free perpendicular alignment of the NPLs in poly(methyl methacrylate) (PMMA) fibers, resulting in dominant emission in directions parallel to the fiber. It is suggested that the observed vertical alignment is due to normal forces resulting from viscoelastic expansion when the polymer solution leaves the cannula (Barus effect) and that using such perpendicular nano-emitter alignment forces allows for the generation of novel materials also beyond fibers.     

ACHEMA 2022 – Heat Exchanger

ACHEMA is an international exhibition for innovation and development in the process industry. Heat exchangers are necessary parts of many process engineering plants. This report intends to highlight the presented novelties in relation to heat exchangers at ACHEMA 2022. The trends and challenges of heat exchangers were explored in discussions with exhibitors and through presentations at the congress. The field of application for heat exchangers broadens as well as their performance increases. Existing designs are enhanced, traditional types of heat exchangers are combined, and software is developed based on both traditional models and artificial intelligence. An overview of relevant innovations and developments in heat exchangers is given.     

Comparative study of the consumption of virgin olive oil or seje on lipid profile and oxidation resistance of high density lipoprotein (HDL) of rat plasma

We compared the effect of the consumption of seje oil (Oenocarpus bataua), with that of olive oil, on plasma lipids and susceptibility in vitro to oxidation of high density lipoprotein (HDL) in the rat. Two groups often male Sprague Dawley rats were fed ad libitum, for a lapse of eight week, with a purified diets with 10g de seje oil or olive oil/100 g of diet (GS y GO respectively). The animals were exsanguinated at the end of the experimental after a 14 hour fast. Plasma was isolated by centrifugation, and the fractions of lipoproteins were separated from the plasma by sequential ultracentrifugation. Rats of GO had a statistically significant lower in concentration of TG (p < 0.05) compared with GS group. HDL fractions in both groups were oxidatively modified by incubation with copper ions. Differences in the fractions susceptibilities to peroxidation were studied by measuring the formation of thiobarbituric acid reactive substance (TBARS) for 3 hours. HDL in GS had a statistically significant decrease in TBARS formation (p < 0.05) relative to HDL of GO. This may be explained by the lower concentration of polyunsaturated fatty acids of HDL in GS compared with HDL in GO.     

Improvement in the cycle life of LaB5 metal hydride electrodes by addition of ZnO to alkaline electrolyte

The improvement in the cycle life of a metal-hydride electrode, LaNi_3.35Co_0.75Mn_0.4Al_0.3, brought about by the addition of ZnO to the alkaline electrolyte has been investigated using measurements based upon in situ electrical resistance, corrosion, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and inductively-coupled plasma-atomic emission spectroscopy. It was found that Zn is underpotentially deposited on and subsequently alloyed with the subject electrode upon repeated charge-and-discharge cycles. The presence of Zn extends the cycle life of the LaNi_3.35Co_0.75Mn_0.4Al_0.3 electrode by inhibiting the disintegration and lowering the corrosion rate of the alloy particles.