Olga Pieroni

Enhancing CaP Biomimetic Growth on TiO2 Cuboids Nanoparticles via Highly Reactive Facets

Pure decahedral anatase TiO(2) particles with high content of reactive {001} facets were obtained from titanium(IV) tetrachloride (TiCl(4)) using a microemulsions droplet system at specific conditions as chemical microreactor. The product was systematically characterized by X-ray diffraction, field-emission scanning and transmission electron microscopy (FE-SEM, TEM), N(2) adsorption-desorption isotherms, FT-IR and UV-vis spectroscopy, and photoluminescence studies. The obtained cuboids around 90 nm in size have a uniform and dense surface morphology with a BET specific surface area of 11.91 m(2) g(-1) and a band gap energy (3.18 eV) slightly inferior to the anatase dominated by the less-reactive {101} surface (3.20 eV). The presence of reactive facets on titania anatase favors the biomimetic growth of amorphous tricalcium phosphate after the first day of immersion in simulated human plasma. The results presented here can facilitate and improve the integration of anchored implants and enhance the biological responses to the soft tissues.

Role of interfacial elasticity of microemulsions on the morphology of TiO2 nanostructures: stiff templates versus flexible templates

The effects of temperature and interfacial elasticity on nanostructured titanium dioxide (TiO2) microemulsions templated materials have been investigated. The aim was to establish a simple and rapid selection of the best experimental conditions for achieving some required material property. TiO2 materials have been prepared through reactive microemulsion precipitation. The effect of microemulsion process parameters (temperature and oil phase density) on the final material characteristics has been investigated. The titania nanopowders were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and N2 adsorption–desorption isotherms. The results obtained by different process conditions show that the nonpolar phase density and temperature of microemulsions have a great influence on the final characteristics of the obtained material. A reduction of the microemulsion oil density causes a significant decrease in the particle agglomeration and an augment of the material-specific surface area and pore volume. At the same time, rutile is favored over anatase phase. The increase of template microemulsion temperature produces, in some systems, a morphology change from granular to a bicontinuous structure.

Biomimetic formation of crystalline bone-like apatite layers on spongy materials templated by bile salts aggregates

Since the trabecular bone exhibit sponge-like bicontinuity there is a growing interest in the synthesis of spongy-like sieves for the construction of bio-active implantable materials. Here, we propose a one step sol–gel method for the synthesis of bicontinuous pore silica materials using different bile salts aqueous mixtures as templates. The influences of the type and amount of bile salt on the synthesis processes are investigated and correlated with the final material morphology. As a final point, their structural properties are interrelated with their ability to induce a bone-like apatite layer in contact with simulated body fluid (SBF). We have confirmed that under specific template conditions, the synthesized material has an open bio-active macropore structure that is blanched in a 3D-disordered sponge-like network similar than those existed in trabecular bone.

Thermal reaction of cinnamic acid and of β-styrylphosphonic acid with urea

The thermal reaction of b-styrylphosphonic acid under experimental conditions similar to those applied to cinnamic acid and to methyl cinnamate to provide 6-phenyl-5,6-dihydrouracil, led to the formation of the novel 6-phenyl-5,6-dihydro-4-phosphorylamide-(1H,3H)-2-pyrimidinone.

Photoluminescent SBA-16 Rhombic Dodecahedral Particles: Assembly, Characterization, and ab Initio Modeling

Nowadays, the use of polyhedral instead of spherical particles as building blocks of engineering new materials has become an area of particular effort in the scientific community. Therefore, fabricating in a reproducible manner large amounts of uniform crystal-like particles is a huge challenge. In this work we report a low reagent-consuming binary surfactant templated method mediated by a hydrothermal treatment as a facile and controllable route for the synthesis of crystal-like rombdodecahedral particles exhibiting SBA-16 mesoporosity. It was determined that the hydrothermal treatment conditions were a key point upon the final material morphology, surface area, microporosity, wall thickness, and mesopore width. As a consequence of their internal mesoporosity order, rhombic dodecahedral synthesized particles exhibited highly efficient ultraviolet absorptions and photoluminescence emissions at room temperature. Conducting experimental and theoretical comparative studies allowed us to infer that the presence of intrinsic defects confined into an ordered mesoporous structure plays a very important role in semiconductor materials. The information presented here is expected to be useful, giving new, accurate information, for the construction of novel technological devices.

Rapid characterisation of agro-industrial effluents for environmental fate by UV–visible and infrared spectroscopy from fractions obtained by centrifugation

ABSTRACT Agro-industrial systems (e.g. dairy farms, feed lot, pig breeding and food processing plants) provide large quantity of organic wastes that could be recycled within the productive systems. However, the basic chemical characterisation is not enough to predict the effect that they may generate on the environment. In this study, a centrifugation process was applied at various speeds between 3000 and 15,000 rpm and carried out separately on two different livestock effluents (dairy farm and pig anaerobic digestate), in order to obtain supernatants and precipitates, which were studied separately. The more water soluble fractions, with lighter components and/or simpler structures, remained as liquid supernatants, while the more complex fractions, with higher molecular weight and/or water insoluble fractions, constituted the solid precipitates. An increase in the centrifugation rate did not produce the differential precipitation of dissimilar functional groups. Hence, 5000 rpm was the most adequate velocity since it generated clear supernatants without denaturation of the organic matter. A basic cost-effective chemical analysis, complemented with ultraviolet–visible and Fourier transform infrared spectroscopy, enables a set of properties to be established qualitatively and quickly for the multiple components of the organic matter for its later use as fertilisers or amendments. This rapid and economical technique allows for a characterisation prior to the reuse of the effluents, which is necessary to optimise their application and avoid environmental problems.

Assessment of synergistic interactions on self-assembled sodium alginate/nano-hydroxyapatite composites: to the conception of new bone tissue dressings

The aim of this work is to assess the behavior of biocomposites (CPSs) in regard to the generation of biogenic hydroxyapatite and also their degradation depending on the concentration of cross-linker agent, pH, and ionic strength. The development of these composites with potential application in bone tissue regeneration is based on alginate and synthetic nano-hydroxyapatite (nano-HA), which was used as a cross-linker agent. The CPSs showed the capability to develop biogenic hydroxyapatite when they were incubated in simulated body fluid (SBF) depending on the incubation time and concentration of the linker. These results were analyzed by x-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM). Furthermore, the CPSs have shown resistance to the degradation (demonstrated by swelling and dissolution tests) when the mentioned conditions were modified. Finally, the development of a liquid crystalline phase within the composites, which contributes to reinforce their structure, is a novel finding in this study. This behavior has been shown by means of optical microscopy (OM) with crossed polaroids. Thus, these composites displayed promising results to be used as bone filling materials in the future.

Effect of ionization on the behavior of n-eicosanephosphonic acid monolayers at the air/water interface. Experimental determinations and molecular dynamics simulations.

Monolayers of n-eicosanephosphonic acid, EPA, were studied using a Langmuir balance and a Brewster angle microscope at different subphase pH values to change the charge of the polar headgroups (Zav) from 0 to -2. Molecular dynamics simulations (MDS) results for |Zav| = 0, 1, and 2 were compared with the experimental ones. EPA monolayers behave as mixtures of mutually miscible species (C20H41-PO3H2, C20H41-PO3H(-), and C20H41-PO3(2-), depending on the subphase pH). The order and compactness of the monolayers decrease when increasing |Zav|, while go from strongly interconnected by phosphonic-phosphonic hydrogen bonds (|Zav| = 0-0.03) through an equilibrium between the total cohesive energy and the electrostatic repulsion between the charged polar groups (0.03 < |Zav| < 1.6) to an entirely ionic monolayer (|Zav| ≈ 2). MDS reveal for |Zav| = 0 that the chains form spiralled nearly rounded structures induced by the hydrogen-bonded network. When |Zav| ≈ 1 fingering domains were identified. When Z ≈ 2, the headgroups are more disordered and distanced, not only in the xy plane but also in the z direction, forming a rough layer and responding to compression with a large plateau in the isotherm. The monolayers collapse behavior is consistent with the structures and domains founds in the different ionization states and their consequent in-plane rigidity: there is a transition from a solid-like response at low pH subphases to a fluid-like response at high pH subphases. The film area in the close-packed state increases relatively slow when the polar headgroups are able to form hydrogen bonds but increases to near twice that this value when |Zav| ≈ 2. Other nanoscopic properties of monolayers were also determined by MDS. The computational results confirm the experimental findings and offer a nanoscopic perspective on the structure and interactions in the phosphonate monolayers.

A Serendipitous Extension for Illustrating Newman Projections

The idea of using overhead Newman projections for understanding conformational analysis was extended, making possible the construction of an inexpensive, very simple hand-pocket model from two transparencies of about 100 cm2, a small piece of chalk, and two thumbtacks.