Shuttle trap

The sensitizers display a crucial role in harvesting of sunlight. To trap solar radiation efficiently in the visible and the near IR region of the solar spectrum requires engineering of sensitizers at a molecular level (see Section 9.16.3).26 The electrochemical and photophysical properties of the ground and the excited states of the sensitizer have a significant influence on the charge transfer (CT) dynamics at the semiconductor interface (see Section 9.16.4). The open-circuit potential of the cell depends on the redox couple, which shuttles between the sensitizer and the counter electrode (for details see Section 9.16.5). 

The Orbitrap. The Orbitrap analyzer, [26] invented by Alexander Makarov, has been defined by the company that commercially produces it as the first totally new mass analyzer to be introduced to the market in more than 20 years . Its name recalls the concept of trapping ions. Indeed, ions are trapped in an electrostatic field produced by two electrodes a central spindle-shaped and an outer barrel-like electrode. Ions are moving in harmonic, complex spiral-like movements around the central electrode while shuttling back and forth over its long axis in harmonic motion with frequencies... 

It appears at this time that one of the most important mechanisms involved in the luminescence of rare earth ions is energy exchange between them. One may clearly differentiate between two distinct mechanisms (a) radiative exchange and (b) nonradiative exchange. In the radiative mechanism, a photon emitted by ion A is captured by ion B. Since the photon has left the A system, the capture of it by B cannot decrease the lifetime of A. However, f the photon is shuttled back and forth between similar or dissimilar ions, the fluorescent lifetime could well be increased by radiation trapping. This is an interesting phenomenon and warrants further discussion. 

Roberts et al. (523) emphasized that the in-line mechanism almost requires that two different groups deprotonate the 2 0H and protonate 05 since they are on opposite sides of the basal plane. They are physically removed from each other with a negative P-0- between them to trap any shuttle. Since they observed 3 -CMP interactions with His 12 and 119 by NMR with the greater effect on His 119 and both histidines protonated and since the X-ray structure shows the phosphate between the two histidines, they believed that both histidines are directly involved. Furthermore, the interaction of His 119 is more sensitive to the specific... 

These ideas have been illustrated in a recent study of the co-crystalline complex of l-MethylCytosine 5-FluoroUracil [34], Using model calculations it was shown how the hydrogen bonding network of the crystal is able to sustain a proton shuttle which leads to the selective formation of certain radicals. Calculations were able to predict that the site of reduction would be the cytosine base (yielding the N3 protonated cytosine anion C(N3+H) ), while the uracil base would be the site of oxidation (yielding the N1 deprotonated uracil cation U(N1-H) ). These are indeed the primary radiation induced species observed experimentally [34, 88], The results also nicely agree with the model proposed for radical trapping by Bernhard [11],... 

A rotaxane is a supramolecular system composed of a macrocyclic and a dumbbellshaped component. The macrocycle encircles the linear rod-like portion of the dumbbell-shaped component and is trapped mechanically around it by two bulky stoppers. Thus, the two components cannot dissociate, but the ring component can shuttle along the axis component (Fig. 15). 

We observed (Fig. 3) that in the absence of surface quinones, the relaxation of QD absorption bleach band (A,ex=528 nm) corresponding to 1 lSelSh> state reflects the trapping excited charge carriers at the surface. The picosecond kinetic analysis shows that in the presence of tCl-l,2-BQ the short time component of the transient bleach formation at A.reg=530 nm is additionally shortened from 93 ps down to 27 ps. It reflects the appearance of the additional non-radiative relaxation channel for electrons from QD conduction band to the lowest unoccupied molecular orbitals of quinone (LUMO). These results are in an agreement with calculations presented in [4]. We believe that long component (r> 3 ns) may reflect the electron shuttling from LUMO of the quinone to the QD valence band. 

It is worthwhile to note that the charged Bose gas trapped in the double well potential Ua of Eq. 50 behaves as an inverted Josephson junction (N-S-S-N). The super-current, which accompanies the matter wave coherence, is induced between the degenerate resonance states of the adjacent wells at the frequency of the tunnel splitting A response time, as is typical of tunnel junctions (whose frequency cutoff is much smaller than the vibrational frequency even for nano junctions). The coherent oscillations of the Josephson current can be observed by virtue of their slow frequency A V which is robustly controlled by the bias voltage. 

Finally, a protein has been identified that is unique from the previously discussed ABC proteins. This protein, called lung resistance protein or major vault protein, has a molecular weight of 110 kD and is found not in the cell membrane but rather the nuclear membrane or the cytoplasm. The role of this protein is to prevent the drug from accessing the nucleus by trapping the drug in vesicles called vaults. The vaults then shuttle... 

Pumice is a natural porous ceramic. It is produced by volcano eruptions and the gas is trapped inside the solid as it rapidly cools. The matrix is mainly glass, but it can contain small crystals. Synthetic ceramic foam is illustrated in Eigure 15.15. Uses for ceramic foam are summarized in Table 15.3. One of the best-known applications for a porous ceramic is the space shuttle tile. An SEM image of such a tile is shown in Eigure 15.16. Notice that in this case, the ceramic consists mainly of fiber (pressed not woven), so the principle is the same as for ceramic (glass) fiber for house insulation. 

While still improving the earth-clock, the JPL group prepared a clock for ultra-stable deep-space applications. A breadboard ion-clock package, based once more on Hg ions shuttled between a quadru and a 16-pole RF trap, has attained an accuracy of 2 x 10" at the 1 s (10" d" ) stability level. The system is in a sealed vacuum configuration of about 2 L in preparation for flight, see Figure 11.19 [47]. 

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