Tb systems

The Trench Bio-Sparge (TBS) system is an in situ technology for the treatment of groundwater contaminated with organic compounds. The system employs diversion walls to direct the contaminant plume to a subsurface trench reactor, where treatment is achieved by physical and/or biological means. The technology has been field tested at the pilot scale but is not yet commercially available. 

An alternative shorter four-step procedure to prepare bis-TBs 41, 42, 43 and 44 has been reported (Scheme 9), and also tris-TB 51 from diaminobenzenes 45, 46 and 47 and from 1,3,5-triaminobenzene 49 (02CCC609, 05MI1) (Scheme 10). Moreover, the simultaneous formation of the TB units on a central core may also be used for the preparation of multi-TB systems. It may seem that this methodology is limited only to the preparation of symmetrical oligo-TB derivatives. However, another report demonstrated that the simultaneous approach is also applicable to unsymme-trical bis-TB (04EJ01097) (see Scheme 8, pathway B). The overall yield in the preparation of 40 (Ri = CH3, R2 = N02) was lower than that of the original stepwise method. 

The Tb ion may not only emit from D4 (green), but also from (blue). AE is about 5000 cm", much larger than in the case of Eu. Diluted Tb systems, therefore, always show some blue Tb emission, unless comax is very high. 

Sulhvan TB, System and method for generation of high pressure air in an integrated gasiiication combined cycle system. U.S. Patent Appl., US 2008115478. Al 2008 05/22Publ2008. 

The Tb ion may not only emit from 04 (green), but also from 03 (blue). AE is about 5000 cm", much larger than in the case of Eu . Diluted Tb + systems show, therefore, always some blue Tb " emission, unless Vmm is very high. Please note that in these examples we consider only ions interacting with their immediate surroundings and not with other luminescent ions. In Chapter 5 the quenching of higher level emission due to interaction with another centre of the same kind will be discussed (cross relaxation). 

The structure of the Y-B-C phase (Bauer and Nowotny 1971) consists of the B-B zigzag chains with C-branches and trigonal metal prisms, which is similar to that of the phases U-B-C (Toth et al. 1961) and MojBC (Jeitschko et al. 1963). Later work by Bauer and Debuigne (1972, 1975) also found phases with this type of structure in the R-B-C (R = Dy, Gd, Tb) systems. The Dy-B-C phase has lattice parameters a = 3.384 A, fe = 13.727 A and c = 3.647 A. The positions of atoms in the Djh-Cmmm space groups are four dysprosium atoms at 4i sites, y = 0.135 four boron atoms at 4j sites, y = 0.711 and four carbon atoms at 4j sites, y = 0.591. 

Quantum cutting based on the fourth concept is demonstrated in a combination of Er VGd /Tb in LiGdF4 [31]. Figure 16.14 shows flie simplified energy-level diagram of the Er k-Gd -Tb system. In this model, on VUV excitation in the Af 5d levels of Ei % part of the excitation energy is transferred to Gd by... 

Fig. 16.14 Simplified eneigy-level diagram of the Er - -Gd -Tb " system showing the visible quanmm...

According to Achiwa and Kawano (1972, 1973), a Pr-80at% Tb alloy had Sm-type structure. This does not agree with the work of Speight et al. (1968) nor does it agree with the criteria proposed by Harris and Raynor (1969) for the prediction of the crystal structure of an alloy based on the mean atomic number. On the basis of the Harris-Raynor method the Sm-type structure in the Pr-Tb system would be expected to exist between 50 and 66.5 at% Tb (range of mean atomic numbers from about 62 to 63). 

Savitskii et al. (1965) also discussed this system in a review article but did not reveal details of the investigation or show the phase diagram. They did present a diagram for the Gd-Tb system, which they stated was similar to the Gd-Er system. 

Metal-oxygen phase diagram studies show a great similarity to analogous Pu, Pr, and Tb systems, and indicate the possible existence of two additional Cm203 phases which have not yet been isolated [8,170]. Two intermediate oxides, CmOi.72 and CmOi.82, and two other non-stoichiometric phases close to the composition of Cm02 and CmOi.5 have also been detected [88]. A cubic (fee) phase, CmO, was reported in an early preparation of the metal [27]. 

A similar phenomenon occurs in the TBS copolymer system described above ((26, 27), cf. Eq. 3) in which a dramatic e-beam sensitivity decrease is observed whereas the TBS system is a very sensitive x-ray resist, its e-beam speed of 90 mC/cm 30 keV is at best moderate. The ratio of e-beam to x-ray sensitivity is thus very different for this resist (cf. Figure 2). One may speculate that lack of water and evaporation of SOj result in reduced acid formation, and hence lower sensitivity. 

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