Isomorphism of subshifts is a universal countable borel equivalence relation

We use the theory of Borel equivalence relations to analyze the equivalence relation of isomorphism among one-dimensional subshifts. We show that this equivalence relation is a universal countable Borel equivalence relation, so that it admits no definable complete invariants fundamentally simpler than the equivalence classes. We also see that the classification of higher dimensional subshifts up to isomorphism has the same complexity as for the one-dimensional case.     

Preparative size exclusion chromatography combined with detergent removal as a versatile tool to prepare unilamellar and spherical liposomes of highly uniform size distribution

Detergent removal from mixed micelles was combined with preparative size exclusion chromatography (SEC) on Sephacryl S 500 HR to prepare unilamellar and spherical liposomes of defined sizes between 50 and 100 nm with a very narrow size distribution (RSD of vesicle diameter between 13% and 25%). For neutral phosphatidylcholine and negatively charged phosphatidylcholine/phosphatidylglycerol liposome preparations, efficient sizing at the preparative scale was demonstrated by analyzing isolated SEC peak fractions with cryo-transmission electron microscopy and dynamic light scattering. The number-weighted average vesicle diameters obtained using both methods are in very good agreement for fractions of low polydispersity.     

Boundary element tearing and interconnecting methods in unbounded domains

Finite element tearing and interconnecting (FETI) methods and boundary element tearing and interconnecting (BETI) methods are special iterative substructuring methods with Lagrange multipliers. For elliptic boundary value problems on bounded domains, the condition number of these methods can be rigorously bounded by C(1+log(H/h))², where H is the subdomain diameter and h the mesh size. The constant C is independent of H, h and possible jumps in the coefficients of the partial differential equation.In certain situations, e.g., in electromagnetic field computations, instead of imposing artificial boundary conditions one may be interested in modelling the real physical behaviour in an exterior domain with a radiation condition. In this work we analyze one-level BETI methods for such unbounded domains and show explicit condition number estimates similar to the one above. Our theoretical results are confirmed in numerical experiments.     

Epitaxy of rodlike organic molecules on sheet silicates--a growth model based on experiments and simulations

During the last years, self-assembled organic nanostructures have been recognized as a proper fundament for several electrical and optical applications. In particular, phenylenes deposited on muscovite mica have turned out to be an outstanding material combination. They tend to align parallel to each other forming needlelike structures. In that way, they provide the key for macroscopic highly polarized emission, waveguiding, and lasing. The resulting anisotropy has been interpreted so far by an induced dipole originating from the muscovite mica substrate. Based on a combined experimental and theoretical approach, we present an alternative growth model being able to explain molecular adsorption on sheet silicates in terms of molecule-surface interactions only. By a comprehensive comparison between experiments and simulations, we demonstrate that geometrical changes in the substrate surface or molecule lead to different molecular adsorption geometries and needle directions which can be predicted by our growth model.     

The unique role of nanoparticles in nanomedicine: imaging, drug delivery and therapy

This critical review will present the role of nanoparticles (NPs) in the directions that are vital to the new field of nanomedicine, including imaging and drug delivery. We reflect on the physical properties that make NPs advantageous for in vivo efficacy, and review recent advances in major NP based biomedical applications. Critical questions of transport, uptake, and clearance will be discussed and illustrated through the success and opportunities of NP imaging and therapy on a photodynamic therapy (PDT) based NP system that has been developed in our lab over the past decade (540 references).     

Cellulose microfibril angles and cell-wall polymers in different wood types of Pinus radiata

Four corewood types were examined from sapling trees of two clones of Pinus radiata grown in a glasshouse. Trees were grown either straight to produce normal corewood, tilted at 45° from the vertical to produce opposite corewood and compression corewood, or rocked to produce flexure corewood. Mean cellulose microfibril angle of tracheid walls was estimated by X-ray diffraction and longitudinal swelling measured between an oven dry and moisture saturated state. Lignin and acetyl contents of the woods were measured and the monosaccharide compositions of the cell-wall polysaccharides determined. Finely milled wood was analysed using solution-state 2D NMR spectroscopy of gels from finely milled wood in DMSO-d ₆/pyridine-d ₅. Although there was no significant difference in cellulose microfibril angle among the corewood types, compression corewood had the highest longitudinal swelling. A lignin content >32 % and a galactosyl residue content >6 % clearly divided severe compression corewood from the other corewood types. Relationships could be drawn between lignin content and longitudinal swelling, and between galactosyl residue content and longitudinal swelling. The 2D NMR spectra showed that the presence of H-units in lignin was exclusive to compression corewood, which also had a higher (1 → 4)-β-d-galactan content, defining a unique composition for that corewood type.     

Effect of graphite pore former on oxygen electrodes prepared with La0.6Sr0.4CoO3−δ nanoparticles

This study aimed at fabricating porous crack-free and delamination-free La_0.6Sr_0.4CoO_3?δ electrodes using nanopowders and investigating oxygen reduction (occurring at solid oxide fuel cell cathodes) and oxygen evolution (occurring at solid oxide electrolysis cell anodes) at 600 °C in air. The electrodes were deposited by screen-printing on Ce_0.8Gd_0.2O_1.9 substrates. The pastes were prepared with nanoparticles synthesised by flame spray synthesis and graphite pore former. Without graphite, the electrodes sintered at 1000 °C exhibit relatively low porosity and significant densification which led to partial delamination and large overpotentials. The addition of graphite, which was removed by combustion at ca. 650 °C during sintering, markedly improves electrode performance by increasing porosity and reducing densification. A minimal overpotential for both the oxygen reduction and oxygen evolution was reached for a layer porosity of ca. 50–60 vol.%.     

Ru9Zn7Sb8: a structure with a 2 × 2 × 2 supercell of the half-Heusler phase

The title compound Ru(9)Zn(7)Sb(8) was synthesized via a high-temperature reaction from the elements in a stoichiometric ratio, and its structure was solved by a single-crystal X-ray diffraction method. The structure [cubic, space group Fm3m, Pearson symbol cF96, a = 11.9062(14) ? (293 K), and Z = 4] adopts a unique 2a(hh) × 2a(hh) × 2a(hh) supercell of a normal half-Heusler phase and shows abnormal features of atomic coordination against the Pauling rule. The formation of this superstructure was discussed in light of the valence electron concentration per unit cell. It is a metallic conductor [ρ(300 K) = 16 μΩ·m], and differential scanning calorimetry revealed that Ru(9)Zn(7)Sb(8) undergoes a transformation at 1356(1) K and melts, by all indications, congruently at 1386 K. At room temperature, its thermal conductivity is about 3 W/m·K, which is only one-quarter of that of most normal half-Heusler phases. Ru(9)Zn(7)Sb(8) as well as its analogues of iron-, cobalt-, rhodium-, and iridium-containing compounds are expected to serve as a new structure type for exploring new thermoelectric materials.