Separation of racemic mixtures of sn-1(3)-monoacylglycerols by enantioselective-HPLC/ELSD

Enantiomeric separations were performed on five modified polysaccharide-based chiral stationary phases (CSPs) containing cellulose tris(3,5-dimethylphenylcarbamate) (Lux Cellulose-1), cellulose tris(3-chloro-4-methylphenylcarbamate) (Lux Cellulose-2), cellulose tris(4-methylbenzoate) (Lux Cellulose-3), cellulose tris(4-chloro-3-methylphenylcarbamate) (Lux Cellulose-4), amylose tris(5-chloro-2-methylphenylcarbamate) (Lux Amylose-2) by high-performance liquid chromatography and evaporative light scattering detector. A method for direct separation of pairs of sn-1(3)-monoacylglycerols (MAGs) was established using n-hexane/2-propanol as the mobile phase. The washing of CSPs with mobile phases based on n-hexane/2-propanol, containing small amount of acids, improved considerably the efficiency of separations. Racemic mixtures of sn-1(3)-MAGs with different acyl chains could not be directly separated using only one of the columns tested; employing a tandem column system that consisted of a very short silver-loaded column connected downstream with Lux Cellulose-1 the method allowed, for the first time, the separation of four enantiomeric pairs of standard in a single chromatographic run.     

Neuroinflammation and Hypothalamo-Pituitary Dysfunction: Focus of Traumatic Brain Injury

The incidence of traumatic brain injury (TBI) has increased over the last years with an important impact on public health. Many preclinical and clinical studies identified multiple and heterogeneous TBI-related pathophysiological mechanisms that are responsible for functional, cognitive, and behavioral alterations. Recent evidence has suggested that post-TBI neuroinflammation is responsible for several long-term clinical consequences, including hypopituitarism. This review aims to summarize current evidence on TBI-induced neuroinflammation and its potential role in determining hypothalamic-pituitary dysfunctions.     

Computational Evolution of Beta-2-Microglobulin Binding Peptides for Nanopatterned Surface Sensors

The bottom-up design of smart nanodevices largely depends on the accuracy by which each of the inherent nanometric components can be functionally designed with predictive methods. Here, we present a rationally designed, self-assembled nanochip capable of capturing a target protein by means of pre-selected binding sites. The sensing elements comprise computationally evolved peptides, designed to target an arbitrarily selected binding site on the surface of beta-2-Microglobulin (β2m), a globular protein that lacks well-defined pockets. The nanopatterned surface was generated by an atomic force microscopy (AFM)-based, tip force-driven nanolithography technique termed nanografting to construct laterally confined self-assembled nanopatches of single stranded (ss)DNA. These were subsequently associated with an ssDNA–peptide conjugate by means of DNA-directed immobilization, therefore allowing control of the peptide’s spatial orientation. We characterized the sensitivity of such peptide-containing systems against β2m in solution by means of AFM-based differential topographic imaging and surface plasmon resonance (SPR) spectroscopy. Our results show that the confined peptides are capable of specifically capturing β2m from the surface–liquid interface with micromolar affinity, hence providing a viable proof-of-concept for our approach to peptide design.     

Synthesis and characterisation of a nematic homo-polyurethane

The presence of hydrogen bonds in the chemical structure of polymers promotes and stabilises the crystalline phase. For liquid crystalline (LC) polymers, the side insertion of aliphatic units to the mesogenic unit is a suitable artifice to decrease the crystalline stability, without significantly affecting the stability of the LC phases. Here, we report on the synthesis of a LC homo-polyurethane with high hydrogen bond concentration along the chain and bearing an n-pentyl side-chain. Rheological behaviour, thermal analysis, and X-ray diffraction show that the stable LC phase is the nematic.     

Reactive compatibilization of PA6/LDPE blends with an ethylene-acrylic acid copolymer and a low molar mass bis-oxazoline

A sample of polyamide-6 (PA) was blended with low density polyethylene (LDPE) in the 80/20 wt/wt ratio, either without and with 2 phr of an ethylene-acrylic acid copolymer (EAA), Which was known to behave as a compatibilizer precursor, and the effect of the addition of small amounts (0.2 or 0.35 phr) of a fourth component, 2,2′-(1,3-phenylene)-bis(2-oxazoline) (PBO), was investigated. The reactions of PBO with EAA, PA and their blends were studied by recording as a function of time the torque applied to the blending apparatuses and by studying the solubility behavior of the products in formic acid. The PALDPE blends were prepared in a co-rotating twin screw extruder and were characterized by Molau tests, differential scanning calorimetry, scanning electron microscopy, rheology, and determination of the ultimate mechanical properties, including impact tests. The results indicate that the effectiveness of EAA as a compatibilizer precursor is considerably enhanced when PBO is added into the blends. It is thought that the reactions of PBO with the free carboxyl groups of EAA and with the amine or carboxyl end groups of PA run, at least in part, toward the formation of PA-g-EAA copolymers acting as the true compatibilizers for these blends.     

Exciton Recombination in Formamidinium Lead Triiodide: Nanocrystals versus Thin Films

The optical properties of the newly developed near‐infrared emitting formamidinium lead triiodide (FAPbI₃) nanocrystals (NCs) and their polycrystalline thin film counterpart are comparatively investigated by means of steady‐state and time‐resolved photoluminescence. The excitonic emission is dominant in NC ensemble because of the localization of electron–hole pairs. A promisingly high quantum yield above 70%, and a large absorption cross‐section (5.2 × 10^?13 cm^?2) are measured. At high pump fluence, biexcitonic recombination is observed, featuring a slow recombination lifetime of 0.4 ns. In polycrystalline thin films, the quantum efficiency is limited by nonradiative trap‐assisted recombination that turns to bimolecular at high pump fluences. From the temperature‐dependent photoluminescence (PL) spectra, a phase transition is clearly observed in both NC ensemble and polycrystalline thin film. It is interesting to note that NC ensemble shows PL temperature antiquenching, in contrast to the strong PL quenching displayed by polycrystalline thin films. This difference is explained in terms of thermal activation of trapped carriers at the nanocrystal's surface, as opposed to the exciton thermal dissociation and trap‐mediated recombination, which occur in thin films at higher temperatures.     

Auto-adaptive robot-aided therapy using machine learning techniques

This paper presents an application of a classification method to adaptively and dynamically modify the therapy and real-time displays of a virtual reality system in accordance with the specific state of each patient using his/her physiological reactions. First, a theoretical background about several machine learning techniques for classification is presented. Then, nine machine learning techniques are compared in order to select the best candidate in terms of accuracy. Finally, first experimental results are presented to show that the therapy can be modulated in function of the patient state using machine learning classification techniques.     

Sr-containing hydroxyapatite: morphologies of HA crystals and bioactivity on osteoblast cells

A series of Sr-substituted hydroxyapatites (HA), of general formula Ca_(10 ? x)Sr_x(PO₄)₆(OH)₂, where x = 2 and 4, were synthesized by solid state methods and characterized extensively. The reactivity of these materials in cell culture medium was evaluated, and the behavior towards MG-63 osteoblast cells (in terms of cytotoxicity and proliferation assays) was studied. Future in vivo studies will give further insights into the behavior of the materials.A paper by Lagergren et al. (1975), concerning Sr-substituted HA prepared by a solid state method, reports that the presence of Sr in the apatite composition strongly influences the apatite diffraction patterns. Zeglinsky et al. (2012) investigated Sr-substituted HA by ab initio methods and Rietveld analyses and reported changes in the HA unit cell volume and shape due to the Sr addition.To further clarify the role played by the addition of Sr on the physico-chemical properties of these materials we prepared Sr-substituted HA compositions by a solid state method, using different reagents, thermal treatments and a multi-technique approach. Our results indicated that the introduction of Sr at the levels considered here does influence the structure of HA. There is also evidence of a decrease in the crystallinity degree of the materials upon Sr addition. The introduction of increasing amounts of Sr into the HA composition causes a decrease in the specific surface area and an enrichment of Sr-apatite phase at the surface of the samples. Bioactivity tests show that the presence of Sr causes changes in particle size and/or morphology during soaking in MEM solution; on the contrary the morphology of pure HA does not change after 14 days of reaction. The presence of Sr, as Sr-substituted HA and SrCl_2, in cultures of human MG-63 osteoblasts did not produce any cytotoxic effect. In fact, Sr-substituted HA increased the proliferation of osteoblast cells and enhanced cell differentiation: Sr in HA has a positive effect on MG-63 cells. In contrast, Sr ions alone, at the concentrations released by Sr-HA (1.21–3.24 ppm), influenced neither cell proliferation nor differentiation. Thus the positive effects of Sr in Sr-HA materials are probably due to the co-action of other ions such as Ca and P.     

Upon the characterization of semi-synthetic hydrogels based on poly (NIPAM) inserted onto collagen sponge

The preparation of a semi-synthetic hydrogel based on poly(N-isopropyl acrylamide-co-diethylene glycol diacrylate) inserted onto a collagen porous membrane, it was previous presented. The synthesis of the hydrogels was performed through radical copolymerization of N-isopropyl acrylamide (NIPAM) with diethylene glycol diacrylate (DEGDA) also as crosslinking agent, using ammonium persulfate as initiator and N,N,N′,N′-tetramethylethylene diamine activator, and it was achieved in the presence of the collagen matrix. In this paper the thus prepared hydrogels are characterized by Differential Scanning Calorimetry, Scanning Electron Microscopy and for their swelling capacities. A kinetic model was studied to investigate the swelling mechanism of the semi-interpenetrated polymeric network. The swelling behavior was found dependent on the hydrogel composition and to the external stimuli such as temperature and pH of environment. This manner of acting recommends these materials as smart materials with potential applications in tissue engineering and pharmaceutical field as for example bioproducts carrier matrices.     

Supercritical carbon dioxide extraction of oil and α‐tocopherol from almond seeds

The objective of this study was to extract oil and tocopherols from almond seeds using supercritical carbon dioxide and to compare this extraction with a traditional solvent method. Oil and tocopherol extraction rates were determined as functions of the pressure (350–550 bar), temperature (35–50 °C) and CO₂ flow rate (10–30 kg h⁻¹), using a 10‐l vessel. The effects of matrix particle size on extraction yield were also studied and it was demonstrated that extraction yield is greatly influenced by particle size. Maximum recovery was obtained in the first 2–3 h of extraction at a pressure of 420 bar, a temperature of 50 °C and a flow rate of 30 kg h⁻¹ CO₂. These results suggest that the elevated initial oil and tochopherol solubility is related to the increased proportion of fatty acids in the initial extract. The results were compared with those obtained when hexane/methanol was used as a solvent. Copyright © 2005 Society of Chemical Industry