Search results for "engineering.material"

Gold nanostar–polymer hybrids for siRNA delivery: Polymer design towards colloidal stability and in vitro studies on breast cancer cells

2017

To overcome the low bioavailability of siRNA (small interfering RNA) and to improve their transfection efficiency, the use of non-viral delivery carriers is today a feasible approach to transform the discovery of these incredibly potent and versatile drugs into clinical practice. Polymer-modified gold nanoconstructs (AuNCs) are currently viewed as efficient and safe intracellular delivery carriers for siRNA, as they have the possibility to conjugate the ability to stably entrap and deliver siRNAs inside cells with the advantages of gold nanoparticles, which can act as theranostic agents and radiotherapy enhancers through laser-induced hyperthermia. In this study, AuNCs were prepared by coat…

Green Composites Based on PLA and Agricultural or Marine Waste Prepared by FDM

2021

Three dimensional-printability of green composites is recently growing in importance and interest, especially in the view of feasibility to valorize agricultural and marine waste to attain green fillers capable of reducing bioplastic costs, without compromising their processability and performance from an environmental and mechanical standpoint. In this work, two lignocellulosic fillers, obtained from Opuntia ficus indica and Posidonia oceanica, were added to PLA and processed by FDM. Among the 3D printed biocomposites investigated, slight differences could be found in terms of PLA molecular weight and filler aspect ratio. It was shown that it is possible to replace up to 20% of bioplastic …

Magnetic dichroism in angle-resolved hard x-ray photoemission from buried layers

2011

This work reports the measurement of magnetic dichroism in angular-resolved photoemission from in-plane magnetized buried thin films. The high bulk sensitivity of hard x-ray photoelectron spectroscopy (HAXPES) in combination with circularly polarized radiation enables the investigation of the magnetic properties of buried layers. HAXPES experiments with an excitation energy of 8 keV were performed on exchange-biased magnetic layers covered by thin oxide films. Two types of structures were investigated with the IrMn exchange-biasing layer either above or below the ferromagnetic layer: one with a CoFe layer on top and another with a Co${}_{2}$FeAl layer buried beneath the IrMn layer. A pronou…

Hydrogenolysis of hydroxymatairesinol on Y derived catalysts: a computational study

2010

Hydrogenolysis of 7-hydroxymatairesinol (HMR) to matairesinol (MAT) occurs on palladium supported acidic catalysts. HMR has three stereochemical centres and naturally exists as a mixture of two diastereoisomers, namely RRR-HMR and SRR-HMR. The latter is significantly more reactive than the former, in the reaction above. In order to elucidate the hydrogenolysis mechanism, simple surface events involving HMR derivatives on aluminated faujasite (H-Y) fragments were simulated by quantum chemical calculations. The metallic function of a Pd/H-Y acidic catalyst was also mimicked by a minimal palladium cluster. Stereochemical evidences pointed already out that water β-elimination on the epimeric ce…

Quantum well intermixing in GaInNAs/GaAs structures

2003

We report on the characteristics of quantum well intermixing in GaInNAs/GaAs structures of differing N content. Rapid thermal annealing combined with SiO2 caps deposited on the surface of the samples is used to disorder 1.3 mum GaInNAs/GaAs multiquantum wells which have been preannealed in-situ to the stage of blueshift saturation. The different effects of two capping layer deposition techniques on the interdiffusion of In-Ga have been compared, particular regarding the role of sputtering processes. The dependence of quantum well intermixing-induced photoluminescence blueshift on N concentration has provided extra information on the intrinsic properties of the GaInNAs/GaAs material system. …

In Vitro Evaluation of Enteric-Coated HPMC Capsules—Effect of Formulation Factors on Product Performance

2020

A comparative study on different enteric-coated hard capsules was performed. The influence of different formulation factors like choice of enteric polymer, triethyl citrate (TEC) concentration (plasticizer), talc concentrations (anti-tacking agent), and different coating process parameters on the sealing performance of the capsule and the disintegration time were investigated. Furthermore, the influence of different disintegration test methods (with disc vs. without disc and 50 mM U.S. Pharmacopoeia (USP) buffer pH 6.8 vs. biopredictive 15 mM phosphate buffer pH 6.5) was evaluated. All formulations showed sufficient but not equivalent acid resistance when tested. Polymer type was the main f…

Corrosion and wear resistance of coatings produced on AZ31 Mg alloy by plasma electrolytic oxidation in silicate-based K2TiF6 containing solution: Ef…

2022

Abstract In this research, plasma electrolytic oxidation coatings were prepared on AZ31 Mg alloy in a silicate-based solution containing K2TiF6 using bipolar and soft sparking waveforms with 10, 20, and 30% cathodic duty cycles. The coatings displayed a net-like surface morphology consisted of irregular micro-pores, micro-cracks, fused oxide particles, and a sintered structure. Due to the incorporation of TiO2 colloidal particles and the cathodic pulse repair effect, most of the micro-pores were sealed. Long-term corrosion performance of the coatings was investigated using electrochemical impedance spectroscopy during immersion in 3.5 wt.% NaCl solution up to 14 days. The coating grown by t…

Reply to Comment on “Mixed Grotthuss and Vehicle Transport Mechanism in Proton Conducting Polymers from Ab initio Molecular Dynamics Simulations”

2011

Crystal structure of sinhalite MgAlBO4 under high pressure

2015

We report on high-pressure angle-dispersive X-ray diffraction data up to 27 GPa for natural MgAlBO4 sinhalite mineral and ab initio total energy calculations. The experimental bulk modulus of sinhalite is B-0 = 171(3) GPa with a first-pressure derivative of B-0' = 4.2(3). A comparison with other olivine-type compounds shows that the value for B0 is 27% larger than that of Mg2SiO4 forsterite and 29% smaller than that of Al2BeO4 chrysoberyl. These differences are interpreted, on the basis of our ab initio calculations, in terms of the relative incompressibility of Al-O bonds in AlO6 octahedra (with a calculated bulk modulus of 250(1) GPa) as compared to Mg-O bonds in MgO6 octahedra (with a ca…

Synthesis and Physical Stability of Novel Au-Ag@SiO<SUB>2</SUB> Alloy Nanoparticles

2012

The present study describes the synthesis of nanoparticles of silver-gold alloys and with their electrokinetic and spectroscopic characterisation. The synthesis was made in two steps. In the first step silver nanoparticles coated with silica (Ag@SiO2) were synthesised using a novel method assisted by laser ablation. The second step consisted on the introduction of KAuCl4 in the colloidal solution of Ag@ SiO2 nanoparticles in order to obtain silica-coated silver-gold alloy nanoparticles. The changes of colour and mean diameter of Ag@SiO2 nanoparticles caused by the introduction of the gold salt were found dependent on its concentration. Upon increasing (KAuCl4) the diameter of nanoparticles …