Search results for "Dispersion"

Multidisciplinary Approach for Evaluating the Geochemical Degradation of Building Stone Related to Pollution Sources in the Historical Center of Napl…

2020

Natural stones have represented one of the main building materials since ancient times. In recent decades, a worsening in degradation phenomena related mostly to environmental pollution was observed, threatening their conservation. The present work is focused on the minero-petrographic and geochemical characterization of black crust (BC) samples taken from the historical center of Naples, after selecting two pilot monumental areas. The latter were chosen based on their historical importance, type of material, state of preservation and position in the urban context (i.e., high vehicular traffic area, limited traffic area, industrial area, etc.). The building materials used and their interact…

Rotationsdispersion bei monomeren und polymeren L-bornylestern

1962

L-Bornylacrylat und -methacrylat wurden unter verschiedenen Bedingungen radikalisch und ionisch polymerisiert. Die Wellenlangenabhangigkeit der Drehwerte last sich durch eine eintermige DRUDE-Gleichung beschreiben. Die DRUDE-Konstanten fur Poly-L-bornylacrylat hangen nur wenig vom Losungsmittel ab. Sie werden aber, ebenso wie die Lage der COTTON-Effekte, vom Polymerisationsmechanismus beeinflust. The radical and ionic polymerization of L-bornylacrylate and -methacrylate was studied under varying conditions. The optical rotatory dispersion is represented by a simple one-term DRUDE equation. The solvents have little effect on the DRUDE constants for poly-L-bornylacrylate. However, these const…

Pyrene Containing Polymers for the Non-Covalent Functionalization of Carbon Nanotubes

2009

Pyrene containing diblock copolymers based on poly(methyl methacrylate) were synthesized and investigated regarding their adsorption on carbon nanotubes (CNT). The pyrene units were introduced using a reactive ester monomer for the build up of the second block which later on was reacted polymer-analogously with amine functionalized pyrene derivatives. As we started from the same reactive ester intermediate, full block length identity is given. We varied the length of the anchor block to find an optimal block length and used pyren-1-yl-methylamine as well as 4-pyren-1-yl-butylamine as anchor units. For both anchor units a maximal adsorption was found for 13 and 20 anchor units, respectively.…

Surface charge, effective charge and dispersion/aggregation properties of nanoparticles

2003

A careful investigation of the relationship between surface properties and colloidal behaviour of nanometric particles in concentrated media has shed some light on the important parameters that must be controlled in order to improve the dispersion of mineral particles. Experimental methods such as rheology and osmometry reveal that the aggregation/dispersion process is not only a matter of electrostatics as stated by classical theories. In practice, the relationship between the surface charge and the state of dispersion is probably much less straightforward than generally assumed by the classical argument stating that the higher the surface charge, the higher the electrostatic repulsion bet…

Polymeric nanoparticles of different sizes overcome the cell membrane barrier.

2012

Abstract Polymeric nanoparticles have tremendous potential either as carriers or markers in treatment for diseases or as diagnostics in biomedical applications. Finding the optimal conditions for effective intracellular delivery of the payload to the location of interest is still a big challenge. The particles have to overcome the barrier of the cell membrane. Here, we investigated the uptake in HeLa cells of fluorescent polystyrene particles with different size and surface charge. Particles stabilized with the nonionic surfactant Lutensol AT50® (132 nm, 180 nm, 242 nm, 816 nm, 846 nm diameter) were synthesized via dispersion polymerization. Cationic particles (120 nm, 208 nm, 267 nm, 603 n…

On the dependence of magnetic stochastic resonance features on the features of magnetic hysteresis

2005

Numerical study of magnetic stochastic resonance (SR) in several magnetic systems having different hysteresis loops was performed. The various hysteresis loops were modeled by using Preisach model in which several identification functions were used. The results showed the dependence of SR on the parameters of Preisach function. The results also showed how the field H/sub 0/ shifted the onset of SR and how a large dispersion of the distribution of hysterons degraded the SR.

Price dispersion in the Italian airline industry: the role of competition and online travel agents

2013

Price dispersion and competition in business routes: An empirical analysis

2014

In vitro models for the prediction of in vivo performance of oral dosage forms: Recent progress from partnership through the IMI OrBiTo collaboration

2019

The availability of in vitro tools that are constructed on the basis of a detailed knowledge of key aspects of gastrointestinal (GI) physiology and their impact on formulation performance and subsequent drug release behaviour is fundamental to the success and efficiency of oral drug product development. Over the last six years, the development and optimization of improved, biorelevant in vitro tools has been a cornerstone of the IMI OrBiTo (Oral Biopharmaceutics Tools) project. By bringing together key industry and academic partners, and by linking tool development and optimization to human studies to understand behaviour at the formulation/GI tract interface, the collaboration has enabled …

Usefulness of QT dispersion in clinical practice

2016

The measurement of QT dispersion in the surface electrocardiogram has been proposed as a non invasive method for assessing inhomogeneity of myocardial repolarization and has been linked to an increased risk of arrhythmic cardiac death. Several studies have evaluated the use of QTd in a wide variety of cardiac diseases and have reached conflicting conclusions regarding its clinical significance.