A molecular-level abacus-like system driven by light inputs has been designed in the form of a [2]rotaxane, comprising the pi-electron-donating macrocyclic polyether bis-p-phenylene-34-crown-10 (BPP34C10) and a dumbbell-shaped component that contains 1) a Ru(II) polypyridine complex as one of its stoppers in the form of a photoactive unit, 2) a p-terphenyl-type ring system as a rigid spacer, 3) a 4,4'-bipyridinium unit and a 3,3'-dimethyl-4,4'-bipyridinium unit as pi-electron-accepting stations, and 4) a tetraarylmethane group as the second stopper. The synthesis of the [2]rotaxane was accomplished in four successive stages. First of all, the dumbbell-shaped component of the [2]rotaxane was constructed by using conventional synthetic methodology to make 1) the so-called "west-side" comprised of the Ru(II) polypyridine complex linked by a bismethylene spacer to the p-terphenyl-type ring system terminated by a benzylic bromomethyl function and 2) the so-called "east-side" comprised of the tetraarylmethane group, attached by a polyether linkage to the bipyridinium unit, itself joined in turn by a trismethylene spacer to an incipient 3,3'-dimethyl-4,4'-bipyridinium unit. Next, 3) the "west-side" and "east-side" were fused together by means of an alkylation to give the dumbbell-shaped compound, which was 4) finally subjected to a thermodynamically driven slippage reaction, with BPP34C10 as the ring, to afford the [2]rotaxane. The structure of this interlocked molecular compound was characterized by mass spectrometry and NMR spectroscopy, which also established, along with cyclic voltammetry, the co-conformational behavior of the molecular shuttle. The stable translational isomer is the one in which the BPP34C10 component encircles the 4,4'-bipyridinium unit, in keeping with the fact that this station is a better pi-electron acceptor than the other station. This observation raises the question- can the BPP34C10 macrocycle be made to shuttle between the two stations by a sequence of photoinduced electron transfer processes? In order to find an answer to this question, the electrochemical, photophysical, and photochemical (under continuous and pulsed excitation) properties of the [2]rotaxane, its dumbbell-shaped component, and some model compounds containing electro- and photoactive units have been investigated. In an attempt to obtain the photoinduced abacus-like movement of the BPP34C10 macrocycle between the two stations, two strategies have been employed-one was based fully on processes that involved only the rotaxane components (intramolecular mechanism), while the other one required the help of external reactants (sacrificial mechanism). Both mechanisms imply a sequence of four steps (destabilization of the stable translational isomer, macrocyclic ring displacement, electronic reset, and nuclear reset) that have to compete with energy-wasteful steps. The results have demonstrated that photochemically driven switching can be performed successfully by the sacrificial mechanism, whereas, in the case of the intramolecu...

In the clinical setting, the Easyshade and Ikam systems were the most reliable. The other devices tested were more reliable in vitro than in vivo.

Available evidence on the safety of cranioplasty materials is limited due to a large diversity in study conduct, patients included, and outcomes reported. Autografts appear to carry a greater failure risk than allografts. Future publications concerning cranioplasties will benefit by a standardized reporting of surgical procedures, outcomes, and graft materials used.

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Two novel Ru(II)-Rh(III) polypyridine dyads, containing carboxylic functions at the Rh(III) unit, Rh III (dcb) 2 -(BL)-Ru II (dmp) 2 and Rh III (dcb) 2 -(BL)-Ru II (bpy) 2 (bpy ) 2,2′-bipyridine; dcb ) 4,4′-dicarboxy-2,2′-bipyridine; dmp ) 4,7-dimethyl-1,10-phenanthroline; BL ) 1,2-bis[4-(4′-methyl-2,2′-bipyridyl)]ethane), have been synthesized. Their photophysical behavior in solution, compared with that of the mononuclear Ru II (dcb) 2 (dmb) model (dmb ) 4,4′-dimethyl-2,2′-bipyridine), indicates the occurrence of fast (10 8 -10 9 s -1 ) and efficient (>95%) Rh(III)-*Ru(II) f Rh(II)-Ru(III) photoinduced electron transfer. These species adsorb firmly on nanoporous TiO 2 films, via the dcb ligands of the Rh(III) units. The behavior of the adsorbed species has been studied by means of nanosecond time-resolved emission and absorption measurements, as well as by photocurrent measurements. Photocurrent action spectra demonstrate that light absorption by the Ru(II) chromophore leads to electron injection into the semiconductor. A detailed analysis of the transient behavior of the TiO 2 -Rh III (dcb) 2 -(BL)-Ru II (bpy) 2 system indicates that about one-third of the adsorbed dyads (probably because of different orientation at the surface or accidental contacts in small cavities) undergo direct electron injection from the excited state of the Ru(II) chromophore. The remaining dyads display stepwise charge injection processes, i.e., intramolecular electron transfer, TiO 2 -Rh(III)-*Ru(II) f TiO 2 -Rh(II)-Ru(III), followed by charge separation by electron injection,TiO 2 -Rh(II)-Ru(III) f TiO 2 (e -)-Rh(III)-Ru(III). The first process has comparable rates and efficiencies as for the free dyads in solution. The second step is 40% efficient, because of competing primary recombination, TiO 2 -Rh(II)-Ru(III) f TiO 2 -Rh(III)-Ru(II). When the final recombination between injected electrons and oxidized Ru(III) centers is studied, a remarkable slowing down is obtained for the supramolecular systems, e.g., TiO 2 -Rh III (dcb) 2 -(BL)-Ru II (bpy) 2 , relative to analogous systems containing simple mononuclear sensitizers, e.g., TiO 2 -Ru II (dcb) 2 (dmb). Stepwise charge separation and slow recombination between remote sites are distinctive features that suggest the labeling of these systems as "heterotriads".