Search results for "penetration"

Polyanion–tobramycin nanocomplexes into functional microparticles for the treatment of Pseudomonas aeruginosa infections in cystic fibrosis

2016

Aim: Efficacy of antibiotics in cystic fibrosis (CF) is compromised by the poor penetration through mucus barrier. This work proposes a new ‘nano-into-micro’ approach, used to obtain a combinatorial effect: achieve a sustained delivery of tobramycin and overcome mucus barrier. Methods: Mannitol microparticles (MPs) were loaded with a tobramycin polymeric nanocomplex and characterized in presence of CF artificial mucus. Results & discussion: MPs are able to alter the rheological properties of CF artificial mucus, enhancing drug penetration into it and allowing a prolonged drug release. MPs resulted to be effective in Pseudomonas aeruginosa infections if compared with free tobramycin. Co…

Stretching of Free Chains Confined in Concave Brush-Coated Nanocylinders

2012

The structure of a free flexible macromolecule confined in a cylindrical nanopore whose wall is coated by a polymer brush is studied by Monte Carlo simulation, varying the grafting density as well as the radius of the cylindrical pore. Because of this confinement, the free chain is stretched in axial direction; while for small grafting densities of the brush the end-to-end distance increases monotonously with decreasing pore radius, a nonmonotonic variation occurs for larger grafting densities. We show that this effect is due to strong interpenetration of the free chain and the brush chains; for very narrow pores a strong layering of cylindrical shells is found, and comparison with self-con…

Ocular Drug Delivery Systems per la veicolazione di molecole bioattive al segmento posteriore dell'occhio

A Study of Power-Frequency Dynamics in Isolated Power Networks with 100% Converter-Interfaced Generation

2020

The operation of a system with 100% converter-interfaced generation poses several questions and challenges regarding various aspects of the dynamic characteristics of the system. The effects related to the power-frequency control are among the most relevant issues which need to be investigated. The paper takes into examination the case of an existing isolated power network of a geographical island assuming a completely converter-interfaced generation. The factors playing a fundamental role in the assessment of which sources should be designated to be grid-forming are identified with a small signal model formulation of a generic multiple oscillators system. Simulations and analysis performed…

Shade effects on overseeded bermudagrass athletic fields: I. Turfgrass coverage and growth rate

2019

Shade from athletic stadium structures can be a significant deterrent to turfgrass performance. The objective of this study was to determine the daily light requirements of an overseeded or non-overseeded bermudagrass (Cynodon spp.) turf maintained to simulate an athletic field. An experiment was established in 2013 on a mature bermudagrass [Cynodon dactylon (L.) Pers. cv. Riviera] turf that was either overseeded with perennial ryegrass (Lolium perenne L.) or non-overseeded. Plots were re-seeded with ryegrass each fall, but ryegrass was allowed to transition without chemical removal. Shade structures were installed to create four light level treatments including a full-sun control (0% shade…

Bioadhesive monolayer film for the in vitro transdermal delivery of sumatriptan

2006

The work presented here aims to develop a bioadhesive monolayer film containing sumatriptan as adjuvant for the treatment of headache pain in a severe migraine attack. Permeation experiments were performed from the films prepared and from the respective solution, to evaluate the relevant permeation parameters. The effect of the penetration enhancers Transcutol, 2-pyrrolidone, and polyethylene glycol 600 was evaluated. The results obtained show that Transcutol and 2-pyrrolidone decreased sumatriptan permeation from solution, whereas a modest increase was produced by polyethylene glycol 600. The enhancers produced the same effects when they were included in the film. Compared to solution, the…

Transdermal and Skin-Targeted Drug Delivery

1997

Background: The application of therapeutic agents to the skin addresses three general objectives: (a) the treatment of a variety of dermatologic diseases; (b) the “targeted” delivery of drugs to deeper subcutaneous tissues, with a concomitant reduction in systemic exposure; and (c) socalled transdermal administration to elicit a systemic pharmacologic effect. Objective: Recently, significant progress towards all three goals has been recorded and the level of research and development activity remains high. We aim to discuss these advances from mechanistic and clinical standpoints. Results: For the topical treatment of skin disease, novel vehicles (e.g., stabilized, supersaturated systems and…

Voltage Profile Improvement for Soc Son's Low-Voltage Grid with High Penetration of PV Systems by Optimizing the Location of SVC Devices

2018

This paper presents a method that is applied to optimize the placement of Static VAR compensators in a real low-voltage grid in the Vietnamese territory. In this way, the voltage profile of the distribution grid turns to be improved. A heuristic method, the Binary Particle Swarm Optimization, is used to find a solution to this problem within the Matlab environment. A case study that considers a high penetration of rooftop PV systems in a branch of Soc Son distribution grid is implemented to show the efficiency of the optimization method for this specific application.

Nanoporosity, Inclusion Chemistry, and Spin Crossover in Orthogonally Interlocked Two-Dimensional Metal-Organic Frameworks

2015

[Fe(tvp)(2)(NCS)(2)] (1) (tvp=trans-(4,4-vinylenedipyridine)) consists of two independent perpendicular stacks of mutually interpenetrated two-dimensional grids. This uncommon supramolecular conformation defines square-sectional nanochannels (diagonal approximate to 2.2nm) in which inclusion molecules are located. The guest-loaded framework 1@guest displays complete thermal spin-crossover (SCO) behavior with the characteristic temperature T-1/2 dependent on the guest molecule, whereas the guest-free species 1 is paramagnetic whatever the temperature. For the benzene-guest derivatives, the characteristic SCO temperature T-1/2 decreases as the Hammet sigma(p) parameter increases. In general, …

Microparticles derived from marine sponge collagen (SCMPs): preparation, characterization and suitability for dermal delivery of all-trans retinol.

2002

Abstract Collagen microparticles were prepared using marine sponge collagen. For this purpose a previous method by Rossler et al. (J. Microencapsul. 12 (1995) 49) of emulsification and cross-linking of native calf collagen was modified. The modified method for sponge collagen microparticles (SCMPs) achieved a yield of 10%. Scanning electromicroscopic photographs showed spherical particles with a diameter of 120–300 nm and photon correlation spectroscopic measurements indicated particle size range from 126 (±2.9) to 2179 (±342) nm. This broad size distribution was caused by some agglomerates that could not be destroyed by ultrasonication. The surface charge was measured as a function of pH. …