Search results for "Kinetic"

Protofibril formation of amyloid beta-protein at low pH via a non-cooperative elongation mechanism.

2005

Deposition of the amyloid beta-protein (Abeta) in senile or diffuse plaques is a distinctive feature of Alzheimer's disease. The role of Abeta aggregates in the etiology of the disease is still controversial. The formation of linear aggregates, known as amyloid fibrils, has been proposed as the onset and the cause of pathological deposition. Yet, recent findings suggest that a more crucial role is played by prefibrillar oligomeric assemblies of Abeta that are highly toxic in the extracellular environment. In the present work, the mechanism of protofibril formation is studied at pH 3.1, starting from a solution of oligomeric precursors. By combining static light scattering and photon correla…

Evaluating the protecting effects of two consolidants applied on Pietra di Lecce limestone: A neutronographic study

2020

Abstract In this work a combined laboratory-based and neutronographic investigation was carried out on a type of limestone, known as Pietra di Lecce stone, widely used in Italian Baroque as construction material. The limestone was treated with two different commercially-available coatings, namely nanosilica and nanolime, and artificially weathered by salt crystallization and temperature/relative humidity jumps. The aim was to provide an experimental evidence of the protective and consolidating effectiveness of the two treatments by looking at the water absorption process occurring inside the pore network of the analyzed stones. The analysis of the wetting front position revealed significant…

The Master Equation

2009

Comparative Analysis of the Vascular Actions of Diterpenes Isolated from Euphorbia canariensis

1998

Abstract We have analysed the effects of 2,3-diepiingol 7,12-diacetate-8-isobutyrate (compound 1), ingenol-3-angelate-17-benzoate (compound 2), ingenol-3-angelate-17-benzoate-20-acetate (compound 3) and 3,5,7,8,9,15-hexahydroxyjatropha-6(17),11-dien-14-one-5,8-bis(2-methylbutyrate)-7-(2-methylpropionate) (compound 4), four diterpenes isolated from E. canariensis, on the isometric tension developed by isolated rabbit basilar and carotid arteries. Concentration-response curves to these compounds were obtained cumulatively in both arteries at resting tension and active tone (KCl, 50 mM). At resting tension a concentration-dependent contraction was induced by the four compounds. In the basilar …

Altérations neuromusculaires induites par des exercices excentriques et concentriques fatigants : emphase sur le pédalage des membres inférieurs

2021

The influence of dynamic contraction type (concentric or eccentric) on performance fatigability and associated neuromuscular alterations is partly unknown. Contraction type interacts with other exercise features such as intensity (maximal; submaximal) or modality (single-joint; locomotor). Thus, we compared eccentric with concentric exercises of similar characteristics across three experimental studies. We showed that, for the completion of a given amount of mechanical work, both contraction types impaired maximal voluntary isometric torque similarly. However, neuromuscular impairments depended on exercise features. In study 1, maximal single-joint eccentric contractions affected neural but…

Fuzzy logic approach to predict vehicle crash severity from acceleration data

2015

Vehicle crash is a complex behavior to be investigated as a challenging topic in terms of dynamical modeling. On this aim, fuzzy logic can be utilized to analyze the crash dynamics rapidly and simply. In this paper, the experimental data of the frontal crash is recorded using an accelerometer located at the centre of the gravity of the vehicle. The acceleration signal was the raw data from which the collision intensity expressed by the kinetic energy and the jerk were derived. The fuzzy logic model was then developed from the two inputs namely kinetic energy and jerk. The output variable is the crash severity expressed as the dynamic crash. The result shows that the jerk contributes much to…

Ethyl Hexanoate Transfer Modeling in Carrageenan Matrices for Determination of Diffusion and Partition Properties.

2007

 ; Aroma compound properties in food matrices, such as volatility and diffusivity, have to be determined to understand the effect of composition and structure on aroma release and perception. This work illustrates the use of mass transfer modeling to identify diffusion and partition properties of ethyl hexanoate in water and in carrageenan matrices with various degrees of structure. The comparison of results obtained with a diffusive model to those obtained with a convective model highlights the importance of considering the appropriate transfer mechanism. Modeling of the preliminary experimental steps ensures correct estimation of the conditions for the main aroma release step. The obtaine…

Two-Dimensional Modeling of a Flat-Plate Photocatalytic Reactor for Oxidation of Indoor Air Pollutants

2007

In this paper we present a two-dimensional (2-D) analysis of a narrow-slit, flat-plate, single-pass, flow-through photocatalytic reactor for air purification. The continuity equation for convection and diffusion in two dimensions, under un-steady-state conditions, was coupled with radiation field modeling and photocatalytic reaction kinetics to model the transient and steady-state behavior of the reactor. The model was applied to the photocatalytic oxidation of trichloroethylene (TCE) in humidified air streams under different experimental conditions. The kinetic parameters determined by a three-dimensional (3-D) computational fluid dynamics model of the reactor were used in the 2-D model si…

Sorting signals in the cytosolic tail of membrane proteins involved in the interaction with plant ARF1 and coatomer.

2004

Summary In mammals and yeast, a cytosolic dilysine motif is critical for endoplasmic reticulum (ER) localization of type I membrane proteins. Retrograde transport of type I membrane proteins containing dilysine motifs at their cytoplasmic carboxy (C)-terminal tail involves the interaction of these motifs with the COPI coat. The C-terminal dilysine motif has also been shown to confer ER localization to type I membrane proteins in plant cells. Using in vitro binding assays, we have analyzed sorting motifs in the cytosolic tail of membrane proteins, which may be involved in the interaction with components of the COPI coat in plant cells. We show that a dilysine motif in the −3,−4 position (rel…

Strong Cooperativity and Loose Geometry between CUB Domains Are the Basis for Procollagen C-Proteinase Enhancer Activity

2009

Procollagen C-proteinase enhancers (PCPE-1 and -2) specifically activate bone morphogenetic protein-1 (BMP-1) and other members of the tolloid proteinase family during C-terminal processing of fibrillar collagen precursors. PCPEs consist of two CUB domains (CUB1 and CUB2) and one NTR domain separated by one short and one long linker. It was previously shown that PCPEs can strongly interact with procollagen molecules, but the exact mechanism by which they enhance BMP-1 activity remains largely unknown. Here, we used a series of deletion mutants of PCPE-1 and two chimeric constructs with repetitions of the same CUB domain to study the role of each domain and linker. Out of all the forms teste…