Search results for "aggregation."

Quantitative description of temperature induced self-aggregation thermograms determined by differential scanning calorimetry

2012

A novel thermodynamic approach for the description of differential scanning calorimetry (DSC) experiments on self-aggregating systems is derived and presented. The method is based on a mass action model where temperature dependence of aggregation numbers is considered. The validity of the model was confirmed by describing the aggregation behavior of poly(ethylene oxide)-poly(propylene oxide) block copolymers, which are well-known to exhibit a strong temperature dependence. The quantitative description of the thermograms could be performed without any discrepancy between calorimetric and van 't Hoff enthalpies, and moreover, the aggregation numbers obtained from the best fit of the DSC exper…

Review: "Thermal aggregation of proteins in the presence of metal ions"

2008

Role of copper and zinc ions on the heat- induced aggregation

2007

Characterization of protofibrillar aggregates of bovine serum albumin by tryptophans fluorescence lifetime

2010

We report an experimental study on the thermally induced aggregation of Bovine Serum Albumin at basic pH. In these conditions, we observe the growth of simple protofibrillar structures via the formation of intermolecular beta-sheets promoted by the increased electrostatic repulsion. Here we present a study on the time resolved fluorescence of Tryptophans (Trp) along the aggregation kinetics in the above reported conditions. We use the lifetimes distribution approach as a useful tool for the interpretation of the fluorescence decay in terms of protein conformational substates and interconversion dynamics. Trp fluorescence lifetime depends from protein conformations, also in relation with sol…

DEMAND Project: An algorithm for the assessment of the prosumers’ flexibility

2020

Demand side aggregation represents an important opportunity for ancillary services provision due to the potential that the coordinated management of distributed resources has on affecting power systems' operation. In this framework, the Aggregator has a main role and takes on different relationships with the other actors of the power system, usually becoming a mediator between the prosumers and the distribution system operator. The DEMAND project introduces a new point of view in demand side aggregation by proposing a new framework where the Aggregator is no more needed and prosumers can share and combine their flexibility in a new aggregation platform called Virtual Aggregation Environment…

DEMAND Project: Bottom-Up Aggregation of Prosumers in Distribution Networks

2018

The paper explains the concept of the DEMAND project, whose aim is to develop a technical framework for allowing a Bottom-Up aggregation of prosumers connected to the distribution grid. Load and generation aggregation is a very current issue given the great potential that the coordinated management of distributed resources has on power systems operation and design. The novelty in DEMAND is the absence of a physical aggregator and the recourse to a virtual aggregation environment (VAE) for allowing the exchange of information among the prosumers in order to provide a service to the DSO. After a general description of the research project, the paper presents the services that the aggregated c…

Antagonistic effects of fluconazole and 5-fluorocytosine on candidacidal action of amphotericin B in human serum

1994

This study addressed the effects of fluconazole and 5-fluorocytosine on the candidacidal activity of amphotericin B in the presence of human serum. A Candida albicans isolate that was susceptible to all three agents according to standard testing procedures was employed. Fungicidal activity was estimated by using a flow cytometric procedure that exploited the fact that yeast cells killed by amphotericin B diminish in size and take up propidium iodide. The following findings were made. (i) Fluconazole and 5-fluorocytosine each failed to inhibit pseudohyphal formation and cell aggregation even when applied at 10 and 50 micrograms/ml, respectively, for up to 10 h. Hence, these agents were not f…

A Methodology for Exploiting Smart Prosumers’ Flexibility in a Bottom-Up Aggregation Process

2022

The electrical power system is evolving in a way that requires new measures for ensuring its secure and reliable operation. Demand-side aggregation represents one of the more interesting ways to provide ancillary services by the coordinated management of a multitude of different distributed resources. In this framework, aggregators play the main role in ensuring the effectiveness of the coordinated action of the distributed resources, usually becoming mediators in the relation between distribution system operators and smart prosumers. The research project DEMAND recently introduced a new concept in demand-side aggregation by proposing a scheme without a central aggregator where prosumers ca…

Probing ensemble polymorphism and single aggregate structural heterogeneity in insulin amyloid self-assembly.

2020

Ensembles of protein aggregates are characterized by a nano- and micro-scale heterogeneity of the species. This diversity translates into a variety of effects that protein aggregates may have in biological systems, both in connection to neurodegenerative diseases and immunogenic risk of protein drug products. Moreover, this naturally occurring variety offers unique opportunities in the field of protein-based biomaterials. In the above-mentioned fields, the isolation and structural analysis of the different amyloid types within the same ensemble remain a priority, still representing a significant experimental challenge. Here we address such complexity in the case of insulin for its relevance…

Phasor-FLIM analysis of Thioflavin T self-quenching in Concanavalin amyloid fibrils

2020

The formation of amyloid structures has traditionally been related to human neurodegenerative pathologies and, in recent years, the interest in these highly stable nanostructures was extended to biomaterial sciences. A common method to monitor amyloid growth is the analysis of Thioflavin T fluorescence. The use of this highly selective dye, diffused worldwide, allows mechanistic studies of supramolecular assemblies also giving back important insight on the structure of these aggregates. Here we present experimental evidence of self-quenching effect of Thioflavin T in presence of amyloid fibrils. A significant reduction of fluorescence lifetime of this dye which is not related to the propert…