DNA based molecular motors

Most of the essential cellular processes such as polymerisation reactions, gene expression and regulation are governed by mechanical processes. Controlled mechanical investigations of these processes are therefore required in order to take our understanding of molecular biology to the next level. Single-molecule manipulation and force spectroscopy have over the last 15 years been developed into extremely powerful techniques. Applying these techniques to the investigation of proteins and DNA molecules has led to a mechanistic understanding of protein function on the level of single molecules. As examples for DNA based molecular machines we will describe single-molecule experiments on RNA polymerases as well as on the packaging of DNA into a viral capsid—a process that is driven by one of the most powerful molecular motors.     

Dispersion of nanospheres on large glass substrate by amorphous or polycrystalline silicon deposition for localized surface plasmon resonance

Nanosphere lithography is a cost-effective way to fabricate noble metal nanostructures for plasmonics. However, dispersing nanospheres on a large area of glass substrate is a difficulty encountered when transparent substrate is required in applications such as localized surface plasmon resonance or surface enhanced Raman spectroscopy. Because poly(diallyldimethyl ammonium chloride) (PDDA) on silicon surface introduces a force that can disperse nanospheres on silicon, in this article, we modify the glass surface through amorphous or polycrystalline silicon deposition and thus well disperse polystyrene or silica nanospheres over a glass area of more than 2 cm × 2 cm. Transmission loss of the glass substrate caused by amorphous or polycrystalline silicon deposition is analyzed with good agreement to experimental spectra, and localized surface plasmon resonance signals generated from the gold nanostructures fabricated on these substrates are measured and yield a sensitivity of 317 nm/RIU, which prove the feasibility and effectiveness of our method.     

Low-pump-power,short-fiber copropagating dual-pumped (800 and 1050 nm) thulium-doped fiber amplifier

Using optical frequency-domain reflectometry to reveal the gain distribution and allow us to optimize a thulium-doped fiber amplifier, we have demonstrated 18-dB gain by employing only 5 m of a 2000-parts-in-10(6)-Tm-doped fiber pumped with 145 mW of power at dual wavelengths of 800 and 1050 nm. The role of the 800-nm pump, which by itself does not permit population inversion, was clearly observed experimentally.     

Statistical inference and quantum mechanical measurement

We analyze the quantum mechanical measuring process from the standpoint of information theory. Statistical inference is used in order to define the most likely state of the measured system that is compatible with the readings of the measuring instrument and the a priori information about the correlations between the system and the instrument. This approach has the advantage that no reference to the time evolution of the combined system need be made. It must, however, be emphasized that the result is to be interpreted as the statistically inferred state of the original system rather than the state of the system after measurement. The phenomenon of “reduction of states” appears in this light as a consequence of incomplete information rather than the physical interaction between measured system and measuring instrument.     

Synthèses dans ka série des bis-indéno-fluorènes II. Le dihydro-10,15-5H-bis-indéno [1, 2-a;2′,1′-i] fluorène

The biangular bis-indeno-fluorene 10,15-dihydro-5H-diindeno [l, 2-a; 2′, 1′-i]-fluorene (XII) has been synthesised in 6 steps starting from 1-(o-carboxyphenyl)-fluorenone (overall yield 21%). As an intermediate the 5,10,15-trioxoderivative of XII and, accessorily, its 5,10-dioxoderivative were also obtained.