Adamantyl Side Chains as Anti-Aggregating Moieties in Dyes for Dye-Sensitized Solar Cells

Designing and evaluating novel dye concepts is crucial for the development of the field of dye-sensitized solar cells (DSSCs). In our recent report, the novel concept of tethering the anti-aggregation additive chenodeoxycholic acid (CDCA) to dyes for DSSC was introduced. Based on the performance improvements seen for this modification, the aim of this study is to see if a simplified anti-aggregation unit could achieve similar results. The following study reports the synthesis and photovoltaic characterization of two novel dyes decorated with the steric ethyladamantyl moiety on the π-spacer, and on the triarylamine donor. This modification is demonstrated to be successful in increasing the photovoltages in devices employing copper-based electrolytes compared to the non-modified reference dye. The best photovoltaic performance is achieved by a device prepared with the adamantyl decorated donor dye and CDCA, this device achieves a power conversion efficiency of 6.1 % (Short-circuit current=8.3 mA cm⁻², Open-circuit voltage=1054 mV, Fill factor=0.69). The improved photovoltaic performance seen for the adamantyl decorated donor demonstrate the potential of ethyladamantyl side chains as a tool to ensure surface protection of TiO₂.     

A convenient route to 4-carboxy-4-anilidopiperidine esters and acids

The route selection and development of a convenient synthesis of 4-carboxy-4-anilidopiperidines is described. Previous routes were hampered by the low yield of the target esters as well as the inability to convert the esters to the required free acids. Considerations for large-scale production led to a modified synthesis that utilised a tert-butyl ester of 4-carboxy-4-anilidopiperidines which resulted in a dramatic increase in the overall yield of the target N-propionylated- 4-anilidopiperidine-4-carboxylic acids and their corresponding methyl esters. These compounds are now available for use as precursors and reference standards, of particular value for the production of 11C and 18F-labelled 4-carboxy-4-anilidopiperidine radiotracers.     

Is there an easy algebraic characterisation of¶universal proper G-spaces?

We shall study properties of groups having finite cohomological dimension relative to the family of all finite subgroups. We also compare these groups with those satisfying various suggested algebraic analogues to group-actions on finite dimensional proper G-spaces. Received: 15 March 2000     

Some groups of type VF

A group is of type VF if it has a finite-index subgroup which has a finite classifying space. We construct groups of type VF in which the centralizers of some elements of finite order are not of type VF and groups of type VF containing infinitely many conjugacy classes of finite subgroups. It follows that a group G of type VF need not admit a finite-type universal proper G-space. We construct groups G for which the minimal dimension of a universal proper G-space is strictly greater than the virtual cohomological dimension of G. Each of our groups embeds in GL _m (ℤ) for sufficiently large m. Some applications to K-theory are also considered. Oblatum 26-IV-2001 & 3-VII-2002?Published online: 10 October 2002     

Fixed points of finite groups acting on generalised Thompson groups

We study centralisers of finite order automorphisms of the generalised Thompson groups F _n,∞ and conjugacy classes of finite subgroups in finite extensions of F _n,∞. In particular, we show that centralisers of finite automorphisms in F _n,∞ are either of type FP_∞ or not finitely generated.     

Phototaxis in the cyanobacterium Synechocystis sp. PCC 6803: role of different photoreceptors

The second cyanobacterial phytochrome Cph2 from Synechocystis sp. PCC 6803 was suggested as a part of a light-stimulated signal transduction chain inhibiting movement toward blue light. Cph2 has the two bilin binding sites, cysteine-129 and cysteine-1022, that might be involved in sensing of red/far-red and blue light, respectively. Here, we present data on wavelength dependence of the phototaxis inhibition under blue light, indicating that Cph2 itself is the photoreceptor for this blue light response. We found that inhibition of blue-light phototaxis in wild-type cells occurred below the transition point of about 470 nm. Substitution of cysteine-1022 with valine led to photomovement of the cells toward blue light (cph2(-) mutant phenotype). Analysis of mutants lacking cysteine-129 in the N-terminal chromophore binding domain indicated that this domain is also important for Cph2 function or folding of the protein. Furthermore, putative blue-light and phytochrome-like photoreceptors encoded by the Synechocystis sp. PCC 6803 genome were inactivated in wild-type and cph2 knockout mutant background. Our results suggest that none of these potential photoreceptors interfere with Cph2 function, although inactivation of taxD1 as well as slr1694 encoding a BLUF protein led to cells that reversed the direction of movement under blue light illumination in mutant strains of cph2.     

COHOMOLOGICAL DIMENSION OF MACKEY FUNCTORS FOR INFINITE GROUPS

We consider the cohomology of Mackey functors for infinite groupsand define the Mackey-cohomological dimension cdG of a groupG. We will relate this dimension to other cohomological dimensionssuch as the Bredon-cohomological dimension cdG and the relativecohomological dimension -cdG. In particular, we show that forvirtually torsion free groups the Mackey-cohomological dimensionis equal to both -cdG and the virtual cohomological dimension.     

Katalytische Hydroperoxyd-Spaltungen durch Metallverbindungen

Ohne Zusammenfassung