Förster resonance energy transfer imaging in vivo with approximated radiative transfer equation

We describe a new light transport model, which was applied to three-dimensional lifetime imaging of F?rster resonance energy transfer in mice in vivo. The model is an approximation to the radiative transfer equation and combines light diffusion and ray optics. This approximation is well adopted to wide-field time-gated intensity-based data acquisition. Reconstructed image data are presented and compared with results obtained by using the telegraph equation approximation. The new approach provides improved recovery of absorption and scattering parameters while returning similar values for the fluorescence parameters.     

Nonlinear plasmonics at planar metal surfaces

We investigate the nonlinear optical response of a noble metal surface. We derive the components of the third-order nonlinear susceptibility and determine an absolute value of χ((3))≈0.2 nm(2) V(-2), a value that is more than two orders of magnitude larger than the values found for typical nonlinear laser crystals. Using nonlinear four-wave mixing (4WM) with incident laser pulses of frequencies ω(1) and ω(2), we generate fields oscillating at the nonlinear frequency ω(4WM)=2ω(1)-ω(2). We identify and discuss three distinct regimes: (i) a regime where the 4WM field is propagating, (ii) a regime where it is evanescent, and (iii) a regime where the nonlinear response couples to surface plasmon polaritons.     

Statistical analysis of effects of industrial processing steps on functional properties of pasteurised liquid egg white

Egg white is widely used as an ingredient in the food industry owing to its excellent functional properties. The transformation of shell eggs into safe liquid, frozen, or spray‐dried egg white with extended shelf life requires many technological operations that result in modifications to the egg white's functional properties. The present study highlights the critical steps affecting foaming and gelling properties during a classical pasteurised liquid egg white process. The main source of variation in functional properties was raw material quality, accounting for 70% of the variability. Part of the remaining 30% was explained by mechanical egg white–yolk separation, tank storage, pasteurisation and homogenisation that resulted in damage to the functional properties, whereas initial flow through pipes and pumping resulted in their improvement. The effects of these steps could be grouped according to the type of treatment undertaken. Dry matter content, pH and treatment intensity at each step contributed about 30% of the variability in functional properties due to processing steps. Relationships between the modifications of egg white functional properties and protein conformation were established. Between 46 and 78% of the variability in functional properties can be explained by protein denaturation, temperature and enthalpy changes. Copyright © 2004 Society of Chemical Industry     

A Novel Thermoplastic Composite for Marine Applications: Comparison of the Effects of Aging on Mechanical Properties and Diffusion Mechanisms

Applied Composite Materials - This article investigates and compares the effects of hydrothermal aging on carbon fibre / Elium? thermoplastic composite and on carbon fibre / vinylester...     

Towards Molecular Understanding of the Functional Role of UbiJ-UbiK2 Complex in Ubiquinone Biosynthesis by Multiscale Molecular Modelling Studies

Ubiquinone (UQ) is a polyisoprenoid lipid found in the membranes of bacteria and eukaryotes. UQ has important roles, notably in respiratory metabolisms which sustain cellular bioenergetics. Most steps of UQ biosynthesis take place in the cytosol of E. coli within a multiprotein complex called the Ubi metabolon, that contains five enzymes and two accessory proteins, UbiJ and UbiK. The SCP2 domain of UbiJ was proposed to bind the hydrophobic polyisoprenoid tail of UQ biosynthetic intermediates in the Ubi metabolon. How the newly synthesised UQ might be released in the membrane is currently unknown. In this paper, we focused on better understanding the role of the UbiJ-UbiK₂ heterotrimer forming part of the metabolon. Given the difficulties to gain functional insights using biophysical techniques, we applied a multiscale molecular modelling approach to study the UbiJ-UbiK₂ heterotrimer. Our data show that UbiJ-UbiK₂ interacts closely with the membrane and suggests possible pathways to enable the release of UQ into the membrane. This study highlights the UbiJ-UbiK₂ complex as the likely interface between the membrane and the enzymes of the Ubi metabolon and supports that the heterotrimer is key to the biosynthesis of UQ₈ and its release into the membrane of E. coli.     

TNF-α and IL-1β Modulate Blood-Brain Barrier Permeability and Decrease Amyloid-β Peptide Efflux in a Human Blood-Brain Barrier Model

The blood-brain barrier (BBB) is a selective barrier and a functional gatekeeper for the central nervous system (CNS), essential for maintaining brain homeostasis. The BBB is composed of specialized brain endothelial cells (BECs) lining the brain capillaries. The tight junctions formed by BECs regulate paracellular transport, whereas transcellular transport is regulated by specialized transporters, pumps and receptors. Cytokine-induced neuroinflammation, such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), appear to play a role in BBB dysfunction and contribute to the progression of Alzheimer’s disease (AD) by contributing to amyloid-β (Aβ) peptide accumulation. Here, we investigated whether TNF-α and IL-1β modulate the permeability of the BBB and alter Aβ peptide transport across BECs. We used a human BBB in vitro model based on the use of brain-like endothelial cells (BLECs) obtained from endothelial cells derived from CD34+ stem cells cocultivated with brain pericytes. We demonstrated that TNF-α and IL-1β differentially induced changes in BLECs’ permeability by inducing alterations in the organization of junctional complexes as well as in transcelluar trafficking. Further, TNF-α and IL-1β act directly on BLECs by decreasing LRP1 and BCRP protein expression as well as the specific efflux of Aβ peptide. These results provide mechanisms by which CNS inflammation might modulate BBB permeability and promote Aβ peptide accumulation. A future therapeutic intervention targeting vascular inflammation at the BBB may have the therapeutic potential to slow down the progression of AD.     

On invariance in canonical analysis with applications to covariate discriminant analysis

We give a result about the invariance of canonical analysis of Euclidean subspaces, so improving a known property. Furthermore, we apply this result to determine conditions for invariance of covariate discriminant analysis when the original variables are linearly transformed. That permits us to introduce a test for this invariance for which we only suppose that the variable admits fourth order moments. A test for redundancy of subcomponents’ variables is obtained as a particular case.      

Identifying Small‐Molecule Binding Sites for Epigenetic Proteins at Domain–Domain Interfaces

Epigenetics is a rapidly growing field in drug discovery. Of particular interest is the role of post‐translational modifications to histones and the proteins that read, write, and erase such modifications. The development of inhibitors for reader domains has focused on single domains. One of the major difficulties of designing inhibitors for reader domains is that, with the notable exception of bromodomains, they tend not to possess a well‐enclosed binding site amenable to small‐molecule inhibition. As many of the proteins in epigenetic regulation have multiple domains, there are opportunities for designing inhibitors that bind at a domain–domain interface which provide a more suitable interaction pocket. Examination of X‐ray structures of multiple domains involved in recognising and modifying post‐translational histone marks using the SiteMap algorithm identified potential binding sites at domain–domain interfaces. For the tandem plant homeodomain–bromodomain of SP100C, a potential inter‐domain site identified computationally was validated experimentally by the discovery of ligands by X‐ray crystallographic fragment screening.     

Classification of global fluid-phase equilibrium behaviors in binary systems

The study of phase equilibria is one of the most important sources of information about the nature of intermolecular forces in liquids and their mixtures and is of the highest importance for designing and optimizing processes. Many of the main features of vapor–liquid and liquid–liquid phase behavior were well characterized experimentally during the early part of the 20th century, and many equations of state were developed to reproduce the many types of phase diagrams observed for binary systems. In spite of the quasi-infinite number of possible configurations and rearrangements of fluid–fluid equilibrium phase diagrams, this paper presents a near-exhaustive classification scheme of fluid phase equilibria in binary systems. It starts from the one proposed by Van Konynenburg and Scott and brings it up-to-date by detailing the progress carried out on this topic since their classification scheme was first proposed. The second part of this paper is devoted to describing the transitions between the various types of systems.