Search results for "layer"

Antimicrobial beeswax coated polylactide films with silver control release capacity.

2013

Although the application of silver based antimicrobial systems is a widespread technology, its implementation in areas such as food packaging is still challenging. The present paper describes the fabrication of poly(lactic acid) (PLA) coated with beeswax with controlled release properties for sustained antimicrobial performance. Release of silver ions from the polymers was monitored voltammetrically under various conditions (surface contact, immersion in various liquid media and at different pH values) throughout at least 7days. A higher release was noted with decreasing pH while surface release was much slower than the release when immersed in liquid medium. While uncoated films demonstrat…

Controlled iontophoretic release of glucocorticoids through epithelial cell monolayers

1998

In the present study the iontophoretic transdermal delivery of three different glucocorticoids through a confluent monolayer of MDCK cells, mimicking biological barriers, was studied. For this experiment an in vitro model with platinum electrodes for iontophoresis and MDCK cells was developed. With this model investigations concerning the biocompatibility of the cells depending on different current densities and the iontophoretic permeation of the three glucocorticoids through the cell monolayer were carried out. The permeation behavior of this living biological barrier should be very similar to the non-living barrier, human stratum corneum. Different current densities (12.74-38.22 microA/c…

Seasonal benthic nepheloid layer in the Gulf of Riga, Baltic Sea: Sources, structure and geochemical interactions

2005

Abstract The sources of particles, as well as the geochemical structure and interfacial exchange were studied for the summer benthic nepheloid layer of the shallow (50 m) Gulf of Riga. The material was sampled at nine stations during three cruises of August 2001–2003 with a main focus on the deep waters. Suspended particulate matter (SPM) and its major (N, Si, P, Al, Fe, Mn, Ca) elements were determined as the principal parameters. The results indicate the summer benthic nepheloid layer as an important component of the environmental regime of the Gulf of Riga. The nepheloid layer develops as a result of the near-bottom hydrodynamics and a corresponding saline structure below the thermocline…

Self-Assembled Monolayers: Bioinspired Catechol-Terminated Self-Assembled Monolayers with Enhanced Adhesion Properties (Small 8/2014)

2014

Analytical characterisation of the biodeterioration of diterpenoid labdanic varnishes used in pictorial techniques: Sandarac and Manila copal

2014

Abstract The deterioration produced by fungal and bacterial growth on the sandarac and Manila copal, diterpenoid varnishes traditionally used as art materials, was evaluated by gas chromatography–mass spectrometry (GC–MS), and pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS). Test specimens, coated with a solidified thin layer of the studied varnishes, were inoculated and incubated with selected fungi and bacteria obtained from collections and oil paintings affected by biodeterioration, and analysed by the above mentioned techniques. Significant changes were detected, showing evidence of deterioration processes caused or favoured by some of the studied microorganisms.

Low-fouling, mixed-charge poly-L-lysine polymers with anionic oligopeptide side-chains

2018

Biosensors and biomedical devices require antifouling surfaces to prevent the non-specific adhesion of proteins or cells, for example, when aiming to detect circulating cancer biomarkers in complex natural media (e.g., in blood plasma or serum). A mixed-charge polymer was prepared by the coupling of a cationic polyelectrolyte and an anionic oligopeptide through a modified "grafting-to" method. The poly-l-lysine (PLL) backbone was modified with different percentages (y%) of maleimide-NHS ester chains (PLL-mal(y%), from 13% to 26%), to produce cationic polymers with specific grafting densities, obtaining a mixed-charge polymer. The anionic oligopeptide structure (CEEEEE) included one cysteine…

The Application of Machine Learning Algorithms to the Analysis of Electromyographic Patterns From Arthritic Patients

2009

The main aim of our study was to investigate the possibility of applying machine learning techniques to the analysis of electromyographic patterns (EMG) collected from arthritic patients during gait. The EMG recordings were collected from the lower limbs of patients with arthritis and compared with those of healthy subjects (CO) with no musculoskeletal disorder. The study involved subjects suffering from two forms of arthritis, viz, rheumatoid arthritis (RA) and hip osteoarthritis (OA). The analysis of the data was plagued by two problems which frequently render the analysis of this type of data extremely difficult. One was the small number of human subjects that could be included in the in…

Variability of shell repair in the Manila clam Ruditapes philippinarum affected by the Brown Ring Disease: A microstructural and biochemical study

2011

11 pages; International audience; For more than two decades, the Manila clam Ruditapes philippinarum has been regularly affected by Brown Ring Disease (BRD), an epizootic event caused by the bacterium Vibrio tapetis and characterized by the development of a brown deposit on the inner face of valves. Although BRD infection is often lethal, some clams recover by mineralizing a new repair shell layer, which covers the brown deposit and fully isolates it from living tissues. In order to understand this specific shell repair process, the microstructures of repaired zones were compared to those of shells unaffected by BRD. In addition, the organic matrix associated with unaffected shells and to r…

A photoswitchable helical peptide with light-controllable interface/transmembrane topology in lipidic membranes

2021

Summary The spontaneous insertion of helical transmembrane (TM) polypeptides into lipid bilayers is driven by three sequential equilibria: solution-to-membrane interface (MI) partition, unstructured-to-helical folding, and MI-to-TM helix insertion. A bottleneck for understanding these three steps is the lack of experimental approaches to perturb membrane-bound hydrophobic polypeptides out of equilibrium rapidly and reversibly. Here, we report on a 24-residues-long hydrophobic α-helical polypeptide, covalently coupled to an azobenzene photoswitch (KCALP-azo), which displays a light-controllable TM/MI equilibrium in hydrated lipid bilayers. FTIR spectroscopy reveals that trans KCALP-azo folds…

Direct investigation of viscosity of an atypical inner membrane of Bacillus spores: A molecular rotor/FLIM study

2013

Abstract We utilize the fluorescent molecular rotor Bodipy-C12 to investigate the viscoelastic properties of hydrophobic layers of bacterial spores Bacillus subtilis. The molecular rotor shows a marked increase in fluorescence lifetime, from 0.3 to 4 ns, upon viscosity increase from 1 to 1500 cP and can be incorporated into the hydrophobic layers within the spores from dormant state through to germination. We use fluorescence lifetime imaging microscopy to visualize the viscosity inside different compartments of the bacterial spore in order to investigate the inner membrane and relate its compaction to the extreme resistance observed during exposure of spores to toxic chemicals. We demonstr…