G-banding

Growing cells are treated with colcemid (0.4 /ig/ml) for 3 h at 37°C and if they are growing as a monolayer, they are then harvested by trypsinisation. 

Alternatively, the air-dried slide may be transferred to a solution of quinacrine mustard dihydrochloride (50 ju.g/ml in Macllvaine s buffer — 6.5 ml 0.2 M Na2HP04, 43.6 ml 0.1 M citric acid and H20 to 100 ml pH 7.0). After 20 min the slides are washed three times with Macllvaine s buffer and sealed wet for visualisation with a fluorescence microscope. 

Analysing karyotypes by hand is extremely tedious and the increasing demands of the health service have led to the development of several computer operated systems which automatically locate and analyse metaphase spreads (Zeidler, 1988). A manual of chromosome techniques has recently been published (Verma and Babu, 1989). 

Metaphase chromosomes can be sorted by flow cytometry in the same way that cells can be sorted (see 10.7.5). Usually separation is based on the DNA content of ethidium bromide or propidium iodide stained chromosomes but Hoechst 33258 (which preferentially stains AT rich segments) and chromomycin A3 (which stains CG rich regions) can also be used (Davies et al., 1981). 

In a few cases (e.g. yeast) small chromosomes can be fractionated by pulsed field gel electrophoresis. 

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Molecular-dynamics simulations also showed that spherical gold clusters is stable in the form of FCC crystal structure in a size range of = 13-555 [191]. This is more likely a key factor in developing extremely high catalytic activity on reducible Ti02 as a support material. Thus, it controls the electronic structure of Au nanoparticles (e.g. band gap and BE shift of Au 4f7/2 band) and thereby the catalytic activity. 

Fig. 19. Energy level diagram for a photoelectrochemi-cal cell decomposing water. The semiconductor is on the left-hand side (E,g band gap)...

D to the G band intensities /d//g was found to be inversely proportional to the crystal size across the basal plane. 

FIG. 23. Variation of the integrated intensity ratio Id/Iq. the maximum position of the G band, rue-and its width Fq against film nitrogen content. (Reproduced from [78].)... 

This broad band at 1500 cm was ascribed by Kaufman. Metin, and Saper-stein [10], to an IR observation of the amorphous carbon Raman D and G bands. This is forbidden by the selection rules, and has been attributed to the symmetry breaking introduced by the presence of CN bonds in the amorphous network. As carbon and nitrogen have different electronegativities, the formation of CN bonds gives the necessary charge polarity to allow the IR observation of the collective C=C vibrations in the IR spectrum. This conclusion was stated by the comparison of spectra taken from films deposited from N2 and N2. In the N2-film spectrum, no shift was observed for the 1500-cm band, whereas all other bands shifted as expected from the mass difference of the isotopes. Figure 25 compares... 

Figure 2 Data cube generation in mapping and imaging. The four-dimensional hyperspectral data cube contains the full spectral information, absorbance vs. wavenumber (v, cm ), for each x,y pixel from the imaged area, as is shown above. A horizontal slice through that cube contains a chemical image (e.g., band intensity at selected v for each x,y pixel of the image) as is shown below. The latter result could be obtained by Global Imaging (in which only the intensity distribution of a certain band over the imaged area would be recorded).

Although the D and G bands are the most prominent features in Raman spectra of CDC, the actual Raman scattering data cannot be fitted with 2 peaks in the case of highly amorphous structures. Such difficulties were observed for Fe3C-derived CDCs produced below 500°C. Instead, for an adequate representation of these spectra, three additional broad peaks of... 

FWHM = 16 cm 1) G band at 1582 cm"1 suggests that graphite crystals are formed under these conditions. 

Recent surveys of metal-deficient stars have discovered a large number of carbon-rich objects, with a marked increase in their frequency at [Fe/H] < —2.5. In order to constrain the origin(s) of their carbon excesses, we have performed elemental abundance analyses for 40 objects selected from candidate metal-poor stars with strong CH G bands identified in the HK and Hamburg/ESO surveys. High-resolution spectroscopy has been obtained with AAT/UCLES and Subaru/HDS a portion of these studies have already been published [1—3]. 

FIGURE 15.18 Schematic picture showing the atomic vibrations for (a) the RBM and (b) the G band modes. (Reprinted with permission from [128]. Copyright (2003) IOP Publishing Ltd.)... 

The D band, the disorder induced mode, normally appears between 1250 and 1450 cm. This band is activated in the first-order scattering process of sp2 carbons by the presence of in-plane substitutional hetero-atoms, vacancies, grain boundaries or other defects and by finite-size effects [134], The G band is the second-order overtone of the D band. 

A 9 cm-1 upshift of the tangential mode (G band) vibrational frequency as well as a 90% decrease in intensity was observed by applying 1.0 V between an individual nanotube and a silver reference electrode in a dilute sulfuric acid solution. 

Optical Properties. The double-decker complexes of porphyrazines have characteristic electronic absorption spectra (Table V). The intense Soret bands of the double-decker complexes are blue shifted with respect to the single pz ligand as a consequence of the strong n-n interactions. Another characteristic of sandwich compounds is the additional appearance of absorption bands shifted to the red (termed Q ) and to the blue (termed Q") of the normal g-band region. These new transitions are thought to result from orbitals delocalized over the two macrocyclic ligands (33, 82). 

Metal-Binding Titrations. Titrations of 81a with AgC104 and HgC104 resulted in a blue shift and broadening of the Q band from 675 to 668 nm. No change in absorbance was seen with addition of up to 2 equiv of Ag+, after which a decrease of the g-band absorbtion occurred up to addition of 5 equiv, at which point no change was observed. In contrast, addition of Hg+ resulted in... 

Peripheral Metalation. Metal ions can be peripherally coordinated to the dimethylamino units. The peripheral metal binding is evident in the UV-vis spectrum by the disappearance of the n—tz absorbance and a sharpening of the g band, thus the metal-binding capabilities of aminoporphyrazines can be monitored by UV-vis titrations. Reaction of Ni[pz(NMe2)g] (102) with PdCl2 results in the formation of the peripherally metalated star-pz (142, 70%) (Scheme 26) (137). Porphyrazines 118,119, and 125 chelate the heavy metal ions Co(II), Cu(II), Zn(II), Ag(I), Cd(II), and Hg(II) (136). 

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