In vitro and in vivo Staining Characteristics of Small,Fluorescent, Aβ42‐Binding D‐Enantiomeric Peptides in Transgenic AD Mouse Models

Plaque visualisation : We identified three different D ‐enantiomeric peptides that bind to Alzheimer's amyloid β (Aβ1‐42). As there is currently no definitive pre‐mortem diagnosis for Alzheimer's disease, we investigated the peptides' suitability as molecular probes for in vivo imaging in transgenic mouse models.

     

Design,Synthesis, and Biological Evaluation of Levoglucosenone‐Derived Ras Activation Inhibitors

A panel of new potential Ras ligands was generated by decorating a tricyclic levoglucosenone‐derived scaffold with aromatic moieties. Some members of the panel show in vitro inhibitory activity toward the nucleotide exchange process on Ras and are toxic to some human cancer cell lines.

     

Quantitative proof of liquid penetration-involved granule formation in a high shear mixer

Previous work of the authors [K. van den Dries, H. Vromans, Qualitative proof of liquid penetration-involved nucleation in a high shear mixer, Eur. J. Pharm. Sci. 58 (2004), 551–559.] revealed that the granule formation in a high shear mixer depends on a balance between the rate of liquid penetration and binder dispersion. Three distinct nucleation mechanisms could be qualified; (I) granule formation by liquid penetration followed by granule breakage or (II) absence of granule breakage and (III) complete dispersion of the binder liquid. The aim of this study was to quantify the mechanisms of granule formation. A substandard amount (1.5% w/w) of binder liquid was added to a lactose mixture, while the mixer was operating. The powder mixture was frozen with liquid nitrogen after 15 s and analysed by sieving. The results show that, despite the minimal liquid amount, granules are formed under most conditions. It is argued granules are being formed by a liquid penetration process. These freshly formed granules are broken down at low viscosity (< 1 Pa s) and remain intact at higher viscosity (> 1 Pa s). Only at extreme conditions (viscosity > 30 Pa s) hardly any granules are formed. In this case penetration of the liquid becomes practically impossible and the binder is completely dispersed. A model based on the processes of liquid penetration, binder dispersion and granule breakage, confirms the observed nucleation behaviour. It is conclusively shown that an increase in viscosity results in a transition from nucleation mechanism I→II→III.     

Synthesis and Evaluation of New Thiodigalactoside‐Based Chemical Probes to Label Galectin‐3

Light up galectin: Photoprobes based on thiodigalactoside were prepared for galectin‐3, a lectin linked to cancer. The probes contained either benzophenone or acetophenone moieties as the photolabel for covalent attachment to the protein. One particular probe labeled galectin‐3 selectively, even in the presence of cell lysate.

     

Discovery of Selective Luteinizing Hormone Receptor Agonists Using the Bivalent Ligand Method

Two series of dimeric ligands for a G‐protein‐coupled receptor were prepared that differ by the interconnecting spacer system. Biological evaluation revealed that both dimeric series exhibit unique biological properties relative to their monomeric counterparts.

     

Nanostructured polystyrene-block-poly(4-vinyl pyridine)(pentadecylphenol) thin films as templates for polypyrrole synthesis

Polypyrrole has been chemically synthesized on thin film nanostructures obtained from comb-shaped supramolecules of polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP) hydrogen bonded with pentadecylphenol (PDP). PDP was washed from thin films of cylindrical and lamellar self-assembled comb-copolymer systems, which resulted in removal of the upper layers of microdomains, leaving single cylindrical and lamellar layers covering a substrate, with P4VP segregated at the bottom as well as at the free air interface. This P4VP was complexed with Cu²⁺ ions, after which chemical oxidation polymerization of pyrrole resulted in a thin polypyrrole layer covering the nanostructured block copolymer. The use of a catalytic amount of bipyrrole greatly improved the quality of the obtained product. The conductivity was measured to be ∼0.7 S cm⁻¹.     

Direct numerical simulation of complex multi-fluid flows using a combined front tracking and immersed boundary method

In this paper a simulation model is presented for the Direct Numerical Simulation (DNS) of complex multi-fluid flows in which simultaneously (moving) deformable (drops or bubbles) and non-deformable (moving) elements (particles) are present, possibly with the additional presence of free surfaces. Our model combines a Front Tracking (FT) model developed by van Sint Annaland et al. (2008. Numerical simulation of dense gas-solid fluidized beds: a multiscale modeling strategy. Ann. Rev. Fluid Mech. 40, 47-70.) and an Immersed Boundary (IB) model developed by van der Hoef et al. (2008. Numerical simulation of dense gas-solid fluidized beds: a multiscale modeling strategy. Ann. Rev. Fluid Mech. 40, 47-70.) The FT part circumvents the explicit computation of the interface curvature. The IB part incorporates both particle-fluid and particle-particle interaction via a direct forcing method and a hard sphere Discrete Particle (DP) approach. In our model a fixed (Eulerian) grid is utilised to solve the Navier-Stokes equations for the entire computational domain. The no-slip condition at the surface of the moving particles is enforced via a momentum source term that only acts in the vicinity of the particle surface. For the enforcement of the no-slip condition Lagrangian force points are used, which are distributed evenly over the surface of the particle. Dissipative particle-particle and/or particle-wall collisions are accounted via a hard sphere DP approach using a three-parameter particle-particle interaction model accounting for normal and tangential restitution and tangential friction. The capabilities of the hybrid FT-IB model are demonstrated with a number of examples in which complex topological changes in the interface are encountered.     

Non-isothermal drying of fired-clay brick, an NMR study

Nuclear magnetic resonance (NMR) was used to measure moisture profiles during non-isothermal drying of fired-clay brick. Drying was induced by a temperature gradient resulting from one-sided heating. A saturated fired-clay brick sample which was closed and isolated on all sides except for the front surface was heated with a halogen lamp of variable intensity. By measuring the moisture profiles in time it was possible to identify two distinct drying stages. In the first drying stage homogeneous drying is observed. When the critical moisture content is reached a drying front enters the sample. The characteristic time t₀ after which this drying front develops depends on the applied heat flux.The total amount of energy needed for evaporation of the moisture in the first drying stage is found to be independent of the heat flux from the lamp. As a result the total amount of moisture as a function of time can be scaled to one master curve using the time t₀. The data from these measurements provided an interesting view on drying processes, not only under isothermal conditions but also under influence of a thermal gradient. By using the power input as a scaling parameter it is shown that both the total mass and the drying front positions as a function of time show the same behaviour in all experiments.     

玻璃纤维增强尼龙66长期老化性能研究

针对玻璃纤维增强尼龙长期耐热老化性影响因素过多、测试结果很难重复的问题,提出利用试验设计技术,设计了一个4因子多水平的试验,因子包括玻璃纤维、基体树脂、试样放置方式和老化时间。发现不同基体树脂、不同的试样放置方式对长期老化具有非常显著的影响。根据实际结果,指出利用旋转试样来消除热老化烘箱中温度不均等因素,可获得具有对比意义的试验数据。     

Towards anti-corrosion coatings from surfactant-free latexes based on maleic anhydride containing polymers

We report on the film formation of surfactant-free, artificial latexes based on copolymers containing maleic anhydride. Different metallic substrates, such as aluminum, steel and magnesium alloys, were coated with three different latexes. A commercial polyester based coating was used as a comparative sample. Two of the latexes were based on polymer with a high T_g (resp. 100 and 130 °C), and one on a polymer with a T_g of −70 °C. The wetting of the substrates could be optimized by etching the metal substrate, acidic or alkaline, leading to homogenous film formation and improved adhesion. For aluminum substrates an alkaline pretreatment improved the adhesion with the polymer films, whereas for magnesium the acidic pretreatment improved the adhesion. Furthermore, acid pretreatment increased the corrosion resistance of the coated magnesium substrate, when compared to an alkaline pretreatment. The films formed from latex displayed comparable or better anti-corrosive properties when compared to the commercial polyester.