Search results for "SCALE"
showing 10 items of 5180 documents
Chemical Approach to Functional Artificial Opals
2007
Artificial opals are self-assembled colloidal crystals, which consist of a cubic dense packing (fcc) of hard (not film-forming) colloids with diameters ranging from 200 to 900 nm. Because of their periodic nanostructure the assemblies are able to reflect light that matches their periodicity, i.e., UV- to IR-radiation depending on the size of the colloids. Thus, they present a subgroup of 'photonic crystals'. While, originally, the chemistry inside the colloids and the resulting opals was of minor significance, nowadays the chemical variation of opals is becoming more and more important for the preparation of functional and patterned opals. The search for functional opals is, therefore, espe…
Nanostructure carbon black-polyisoprene composites as prospective strain sensor materials: macro- and nanoscale studies
2002
Nanostructured carbon black-polyisoprene composite is prepared and investigated. A giant reversible tensoresistive effect -- dependence of electrical resistance vs. uniaxial tension deformation - is found. A new application of the conductive atomic force microscope for the carbon black network mapping in a nonconducting matrix is reported.
Dielectrophoresis as a tool for nanoscale DNA manipulation
2005
The use of the dielectrophoresis as a tool for DNA manipulation is demonstrated experimentally, using both unmodified 48,500 base pairs long bacteriophage lambda dsDNA (λ-DNA), ∼16 μm in length and 414 base pairs long thiol modified natural dsDNA (avDNA), ∼140 nm in length. We show that both the dsDNA types used, are effectively directed between the planar gold electrodes by the positive dielectrophoresis while applying an AC voltage at frequencies between 500 kHz and 1 MHz. With high concentrations of dsDNA in buffer the attached dsDNA molecules are shown to form bundles or clumps (both λ-DNA and avDNA). Furthermore, we demonstrate the attaching of a single avDNA molecule to an electrode v…
Static and dynamic properties of supercooled thin polymer films
2004
The dynamic and static properties of a supercooled (non-entangled) polymer melt are investigated via molecular-dynamics (MD) simulations. The system is confined between two completely smooth and purely repulsive walls. The wall-to-wall separation (film thickness), D, is varied from about 3 to about 14 times the bulk radius of gyration. Despite the geometric confinement, the supercooled films exhibit many qualitative features which were also observed in the bulk and could be analyzed in terms of mode-coupling theory (MCT). Examples are the two-step relaxation of the incoherent intermediate scattering function, the time-temperature superposition property of the late time alpha-process and the…
ChemInform Abstract: Polymeric Janus Particles
2010
Since de Gennes' Nobel lecture in 1991, in which he coined the term "Janus grains", research into asymmetric particles has boomed. Macroscopic, microscopic and nanoscopic particles have been prepared in which certain parts of their surface differ in chemical composition, polarity, color, or any other property. Spherical, cylindrical, disc-like, snowman-, hamburger-, and raspberry-like structures have been synthesized from organic or inorganic materials or even as hybrids of both. Synthetic strategies towards such particles vary greatly from simple polymer mixtures to the bulk self-assembly of sophisticated terpolymers to immobilization methods of symmetric particles. Polymeric Janus particl…
Embryotoxicity studies of tri-n-butyltin(IV) complexes of 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoic acid and 2-[(E)-2-(3-formyl-4-hydroxyphenyl)-1…
2005
The toxicity studies of free 5-[(E)-2-(aryl)-1-diazenyll-2-hydroxybenzoic acid and 2-[(E)-2-(3-formyl-4-hydroxyphenyl)-1-diazenyllbenzoic acid and their tri-n-butyltin(IV) complexes were evaluated by using sea urchin early developmental stages as recommended model organisms for toxicity tests. The novel complexes, as the parent tri-n-butyltin(IV) chloride (TBTCl), caused mitosis block and induced high embryonic mortality in sea urchin. Copyright (c) 2005 John Wiley & Sons, Ltd.
Theory and Simulation of Multiphase Polymer Systems
2010
The theory of multiphase polymer systems has a venerable tradition. The 'classical' theory of polymer demixing, the Flory-Huggins theory, was developed already in the forties of the last century. It is still the starting point for most current approaches -- be they improved theories for polymer (im)miscibility that take into account the microscopic structure of blends more accurately, or sophisticated field theories that allow to study inhomogeneous multicomponent systems of polymers with arbitrary architectures in arbitrary geometries. In contrast, simulations of multiphase polymer systems are relatively young. They are still limited by the fact that one must simulate a large number of lar…
Eye Cataract Simulation Using Polymer Dispersed Liquid Crystal Scattering Obstacles
2004
Polymer dispersed liquid crystals with electrically induced variations of light scattering extent similar to that of transparent PLZT ceramics are used for simulation of different development stages of eye cataract. Wavelength dependencies of scattering are determined in the visible spectral range, and human visual response looking through the scattering obstacle to the onset of various spatial frequency stimuli is determined psychophysically and electrophysiologically in order to find correlation between the scattering extent, visual acuity and visual evoked potential VEP chromatic characteristics.
Evaluation of a pilot-scale biotrickling filter as a VOC control technology for the plastic coating sector
2011
Abstract The performance and feasibility of a biotrickling filter (BTF) pilot unit for the treatment of exhaust gases from two robotic spray paint booths at a plastic coating facility were investigated. The volatile organic compound (VOC) concentrations in the emissions of the exhaust gases from the paint booths were relatively stable, although the VOC composition depended on the applied solvent-paint formulation in the booths. The pilot plant was operated for one year at empty bed residence times (EBRTs) ranging from 30 to 93 s. The performance of the system was affected by the solvent-paint formulations. An EBRT between 30 and 40 s was enough to meet legal requirements for products contai…
Enzymatic Resolution of 3-oxodicyclopentadiene on a Decagram Scale
2018
The chiral building block 3-oxodicyclopentadiene (1) can be readily resolved on a decagram scale by a short sequence consisting of (1) reduction to the corresponding endo-alcohol, (2) enzymatic oxidative resolution with a ketoreductase enzyme to give (+)-1 and the (+)-form of the endo-alcohol, and (3) reoxidation of the (+)-endo-alcohol with another ketoreductase to give (–)-1. With a selectivity factor of 310, the enantiomeric ratios of the resolved (+)-endo-alcohol and (+)-ketone are both >99:1. Both enzymatic oxidations could be performed with a at least 300:1 substrate/catalyst ratio (w/w).