Search results for "bioengineering"

Drug release from alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide-based microparticles.

2004

Abstract Spherical pH-sensitive microparticles have been prepared by reverse phase suspension polymerization technique. Starting polymer has been α , β -poly( N -2-hydroxyethyl)- dl -aspartamide (PHEA) partially derivatized with glycidylmethacrylate (GMA). PHEA-GMA copolymer (PHG) has been crosslinked in the presence of acrylic acid (AA) or methacrylic acid (MA) at various concentration. The obtained microparticles have been characterized by FT-IR spectrophotometry, particle size distribution analysis and scanning electron microscopy. In order to have information about water affinity of the prepared samples, swelling measurements have been carried out in aqueous media which simulate some bi…

Preparation, characterization and in vitro antimicrobial activity of ampicillin-loaded polyethylcyanoacrylate nanoparticles.

1998

In this paper, the experimental conditions for preparing ampicillin-loaded polyethylcyanoacrylate (PECA) nanoparticles are described. The effects of drug concentration and surfactant type in the polymerization medium on the particle size distribution and loading capacity were studied. The results of these studies show that only the type of surfactant has an impact on the nanoparticle dimensions. The release rate of ampicillin from PECA nanoparticles at pH 7.4 (extracellular value pH) performed either with and without esterases, show that the drug release is considerably increased in the presence of these exzymes. The results of drug release study at pH 1.1 (simulated gastric juice) are very…

Fourier transform infrared spectroscopy as a tool for investigation of microbial response to the multi-component organic contamination

2014

Interfacial States Cause Equal Decay of Plasmons and Hot Electrons at Gold-Metal Oxide Interfaces.

2020

We compare the decay of plasmons and "conventional" hot electrons within the same series of gold/metal oxide interfaces. We found an accelerated decay of hot electrons at gold-metal oxide interfaces with decreasing band gap of the oxide material. The decay is accelerated by the increased phase space for electron scattering caused by additional interfacial states. Since plasmons decay faster within the same series of gold-metal oxide interfaces, we propose plasmons are able to decay into the same interfacial states as hot electrons. The similarity of plasmon damping to conventional hot electron decay implies that many classical surface analysis techniques and theoretical concepts are transfe…

Three-dimensional poroelastic metamaterials with extremely negative or positive effective static volume compressibility

2018

Abstract Recently, three-dimensional poroelastic metamaterials have been introduced that show an unusual isotropic increase of their effective volume when increasing the hydrostatic pressure of the surrounding air. This behavior corresponds to a negative effective static volume compressibility. Here, we present significantly simplified metamaterial architectures, which are composed of just one rather than eight hollow sealed functional elements within each cubic unit cell. On cubic symmetry microstructured polymer samples made by 3D laser printing, we measure a negative effective compressibility of about κ eff = − 4 . 7 % ∕ bar under pressure control. This value is six times larger than pre…

Ab initio thermodynamics for the growth of ultra-thin Cu film on a perfect MgO(001) surface

2005

Controlled growth of thin metallic films on oxide substrates is important for numerous micro-and nanoelectronic applications. Our ab initio study is devoted to the periodic slab simulations for a series of ordered 2D Cu superlattices on the regular MgO(001) substrate. Submonolayer and monolayer substrate Cu coverages were calculated using the DFT-GGA method, as implemented into the CRYSTAL-98 code. The results of ab initio calculations have been combined with thermodynamic theory which allows us to predict the growth mode of ultra-thin metal films (spinodal decomposition vs. nucleation-and-growth regime) as a function of the metal coverage and the temperature, and to estimate the metal dens…

Biological oxygen apparent transmissibility of hydrogel contact lenses with and without organosilicon moieties.

2003

The instrument oxygen transmissibility (IOT) of organosilicon hydrogels, measured by electrochemical procedures, is 5-10 times larger than that of conventional hydrogels. A method is described that allows the estimation of the oxygen tension at the lens-cornea interface for closed- and open-eyelids situations by combining the IOT of the hydrogels and corneal parameters such as corneal thickness, corneal permeability and oxygen flux across the cornea. From these results the biological oxygen apparent transmissibility (BOAT) is obtained, an important parameter which an multiplication with the pressure of oxygen on the external part of the lens gives the oxygen flux onto the cornea. Contact le…

Structural and Vibrational Properties of Corundum-type In2O3 Nanocrystals under Compression

2017

[EN] This work reports the structural and vibrational properties of nanocrystals of corundum-type In2O3 (rh-In2O3) at high pressures by using angle-dispersive x-ray diffraction and Raman scattering measurements up to 30 GPa. The equation of state and the pressure dependence of the Raman-active modes of the corundum phase in nanocrystals are in good agreement with previous studies on bulk material and theoretical simulations on bulk rh-In2O3. Nanocrystalline rh-In2O3 showed stability under compression at least up to 20 GPa, unlike bulk rh-In2O3 which gradually transforms to the orthorhombic Pbca (Rh2O3-III-type) structure above 12 14 GPa. The different stability range found in nanocrystallin…

Porous materials applied to biomarker sensing in exhaled breath for monitoring and detecting non-invasive pathologies

2020

International audience; Overview of the use of porous materials for gas sensing to analyze the exhaled breath of patients for disease identification.The quantification of specific gases among thousand of VOCs (Volatile Organic Compounds) present in the human breath at the ppm/ppb level can be used to evidence the presence of diseases in the human body. The detection of these biomarkers in human exhaled breath through a noninvasive approach is an important field of research which is still attracting important attention to this day. A portable device working at room temperature and usable directly on exhaled breath samples is still a challenge requiring a sensing material with high performanc…

Development of curcumin loaded sodium hyaluronate immobilized vesicles (hyalurosomes) and their potential on skin inflammation and wound restoring.

2015

In the present work new highly biocompatible nanovesicles were developed using polyanion sodium hyaluronate to form polymer immobilized vesicles, so called hyalurosomes. Curcumin, at high concentration was loaded into hyalurosomes and physico-chemical properties and in vitro/in vivo performances of the formulations were compared to those of liposomes having the same lipid and drug content. Vesicles were prepared by direct addition of dispersion containing the polysaccharide sodium hyaluronate and the polyphenol curcumin to a commercial mixture of soy phospholipids, thus avoiding the use of organic solvents. An extensive study was carried out on the physico-chemical features and properties o…