Search results for "delay"
showing 10 items of 814 documents
Electrophysiological Correlates of Change Detection during Delayed Matching Task: A Comparison of Different References
2017
Detecting the changed information between memory representation and incoming sensory inputs is a fundamental cognitive ability. By offering the promise of excellent temporal resolution, event-related potential (ERP) technique has served as a primary tool for studying this process with reference of the linked mastoid (LM). However, given that LM may distort the ERP signals, it is still undetermined whether LM is the best reference choice. The goal of the current study was to systematically compare LM, reference electrode standardization technique (REST) and average reference (AR) for assessing the ERP correlates of change detection during a delayed matching task. Colored shapes were adopted …
Influence of different parameters on drug release from hydrogel systems to a biomembrane model. Evaluation by differential scanning calorimetry techn…
2000
A comparative study on the drug release capacity of four water swellable polymeric systems was carried out by differential scanning calorimetry (DSC). The polymeric systems chosen were alpha,beta-polyaspartahydrazide (PAHy) crosslinked by glutaraldehyde (GLU) (PAHy-GLU) or by ethyleneglycoldiglycidylether (EGDGE), (PAHy-EGDGE), polyvinylalcohol (PVA) crosslinked by glutaraldehyde (PVA-GLU) and alpha,beta-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) by gamma irradiation (PHEA-gamma matrices). The degree of crosslinking for PAHy-GLU, PAHy-EGDGE and PVA-GLU samples was about 0.4 and 0.8. These hydrogels were characterized as free of drugs and were loaded with diflunisal (DFN) (approximately 2.5%…
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…
Development and analysis of a model based on chirped fiber Bragg gratings employed for cracks characterization in materials
2018
In this work a model was developed that allows to understand the behavior of a chirped fiber Bragg grating for the detection and characterization of cracks in materials. In addition to the amplitude response, we show that the group delay of the grating provides useful information for the characterization of the crack. The position of the crack can be determined thanks to the linear chirp of the grating that fixes a correlation between the spatial position and both, the wavelength and the group delay. However, our analysis shows that this simple approach has a source of error, which can be overcome if a controllable external strain can be applied to the embedded grating, additional to the st…
Immobilization and controlled release of prostaglandin E2 from poly-L-lactide-co-glycolide microspheres.
2009
Prostaglandin E(2) (PGE(2)) is an arachidonic acid metabolite involved in physiological homeostasis and numerous pathophysiological conditions. Furthermore, it has been demonstrated that prostaglandins have a stimulating effect not only on angiogenesis in situ and in vitro but also on chondrocyte proliferation in vitro. Thus, PGE(2) represents an interesting signaling molecule for various tissue engineering strategies. However, under physiological conditions, PGE(2) has a half-life time of only 10 min, which limits its use in biomedical applications. In the present study, we investigated if the incorporation of PGE(2) into biodegradable poly-L-lactide-co-glycolide microspheres results in a …
Beta-delayed neutron spectroscopy by the TOF technique at IGISOL: 95Rb as a test case
2003
Nuclides with a large neutron excess have high Q β values, making it possible to extract the β-strength function (SF) over a large energy range using β-decay spectroscopy. However, because of the low neutron binding energies, neutron emission from excited states will occur and β-delayed neutron spectroscopy is required to determine the SF over the full Q β window.
Continuous Broadband MWP True-Time Delay with PbS-PMMA and -SU8 waveguides
2016
[EN] A new microwave true-time delay (TTD) photonic unit based on the dispersion of PbS colloidal quantum dots (QDs) in a Polymethyl methacrylate (PMMA) and the SU8 photoresist is presented. With this aim, the PbS-PMMA and PbS-SU8 nanocomposites are integrated on a silicon platform in the form of a planar and ridge waveguides, respectively. When PbS QDs on those structures are pumped below their band-gap, a phase shift and a temporal delay in an optically conveyed (at 1550 nm) microwave signal is performed. The results of these devices show potential benefits over current TTD technologies, since the proposed photonic waveguide structures allows real-time adjustment of the temporal delay by …
An asymmetric electrospun membrane for the controlled release of ciprofloxacin and FGF-2: Evaluation of antimicrobial and chemoattractant properties.
2021
Here, an asymmetric double-layer membrane has been designed and fabricated by electrospinning as a tool for a potential wound healing application. A hydrophobic layer has been produced by using a polyurethane-polycaprolactone (PU-PCL) copolymer and loaded with the antibacterial ciprofloxacin whereas an ion responsive hydrophilic layer has been produced by using an octyl derivative of gellan gum (GG-C8) and polyvinyl alcohol (PVA) and loaded with the growth factor FGF-2. This study investigated how the properties of this asymmetric membrane loaded with actives, were influenced by the ionotropic crosslinking of the hydrophilic layer. In particular, the treatment in DPBS and the crosslinking i…
Incorporation of an antibiotic in poly(lactic acid) and polypropylene by melt processing
2016
Purpose In this work an antibiotic, ciprofloxacin (CFX), was incorporated into 2 different polymeric matrices, poly(lactic acid) (PLA) and polypropylene (PP), to provide them with antimicrobial properties. The influence of CFX content on release kinetics and on antimicrobial and mechanical properties was evaluated. Methods CFX was incorporated into both the polymers by melt mixing. Results The effect of CFX incorporation was found to strongly depend on which polymer matrix was used. In particular, the antimicrobial tests revealed that PLA samples containing CFX produced no inhibition zone and only a slight antibacterial activity was observed when the highest concentration of CFX was added t…