Raman studies

Delivery of the nanoparticles into the cell interior can be carried out in two ways, sonication or fluid-phase uptake. The fluid-phase uptake method 

More recent phenotyping studies by Chan et and Harvey et have 

The early work of Fox et al. investigating the binding time of formalin to tissue, may be of significance to those vibrational spectroscopists presently 

There have been encouraging results reported within the context of live cell experiments using FTIR. The collective demonstration of biochemical stability for different cell types (T-1, HeLa and fibroblasts) by the various research groups working within this field, together with the suggestion of Moss et that correction for water absorbance may not be necessary, suggests that future FTIR studies may be able to measure early biochemical responses of 

In summary, for spectroscopic analysis of tissue samples, fresh or carefully prepared frozen tissue would be considered ideal, but FFPP tissue can be used successfully if deparaffinized using hexane. Other dewaxing agents and protocols can also be used successfully if the paraffin signals do not overlap with the spectral regions of interest. For analysis of cell samples, live cells would be considered ideal, but in cases where this is not possible or practical, fixed cells can be used. Formalin has been shown to provide good cellular preservation for spectroscopic analysis in many studies but some experimentation may be necessary to find the optimum fixative for each particular cell sample. For this optimization, fixed cell samples should be compared with live cell samples where possible. 

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The Fe-N mode is at 222 in the R state and 207 cnY in the T state for the a subunits, but only shifted to 218 T state for the (3 subunits. This is consistent with the interpretation that the Fe-imidazole interations are weakened more in the T state of the a subunits than p subunits. Time-resolved resonance Raman studies have shown that the R T switch is complete on a 10 ps tuuescale [38]. Finally, UV excitation of the aromatic protein side chains yields... 

Asher S A and Chi Z H 1998 UV resonance Raman studies of protein folding in myoglobin and other proteins Biophys. 

Zhong Y and McHale J L 1997 Resonance Raman study of solvent dynamics in electron transfer. II. Betaine-30 in... 

Scott T W and Friedman J M 1984 Tertiary-structure relaxation in haemoglobin—a transient Raman-study J. Am. Chem. Soc. 106 5677-87... 

The general task is to trace the evolution of the third order polarization of the material created by each of the above 12 Raman field operators. For brevity, we choose to select only the subset of eight that is based on two colours only—a situation that is connnon to almost all of the Raman spectroscopies. Tliree-coloiir Raman studies are rather rare, but are most interesting, as demonstrated at both third and fifth order by the work in Wright s laboratory [21, 22, 23 and 24]- That work anticipates variations that include infrared resonances and the birth of doubly resonant vibrational spectroscopy (DOVE) and its two-dimensional Fourier transfomi representations analogous to 2D NMR [25]. 

Pinan J P, Ouillon R, Ranson P, Becucci M and Califano S 1998 High resolution Raman study of phonon and vibron bandwidths in isotropically pure and natural benzene crystal J. Chem. Phys. 109 1-12... 

Asher S A, Chi Z, Holtz J S W, Lednev I K, Karnoup A S and Sparrow M C 1998 UV resonance Raman studies of protein structure and dynamics XWf/r int. Conf on Raman Spectroscopy ed A M Heyns (New York Wley) pp 11-14... 

The most powerful teclmique for studying VER in polyatomic molecules is the IR-Raman method. Initial IR-Raman studies of a few systems appeared more than 20 years ago [16], but recently the teclmique has taken on new life with newer ultrafast lasers such as Ti sapphire [39]. With more sensitive IR-Raman systems based on these lasers, it has become possible to monitor VER by probing virtually every vibration of a polyatomic molecule, as illustrated by recent studies of chlorofonn [40], acetonitrile [41, 42] (see example C3.5.6.6 below) and nitromethane [39, 43]. 

Lingle R J, Xu X, Zhu H, Yu S-C and Hopkins J B 1991 Piooseoond Raman study of energy flow in a photoexoited heme protein J. Phys. Chem. 95 9320-31... 

From a recent Raman study of thiazole on a laser Raman Spectrometer it appears that the actual data differ somewhat from those of Ref. 203. 

The infrared and Raman studies of thiazole derivatives are numerous (111,173,197-226) though often only fragmentary. The only studies leading to a complete assignment of the observed bands are those of Chouteau and Davidovics et al. (201,203.204,227,228). 

More recently, Raman spectroscopy has been used to investigate the vibrational spectroscopy of polymer Hquid crystals (46) (see Liquid crystalline materials), the kinetics of polymerization (47) (see Kinetic measurements), synthetic polymers and mbbers (48), and stress and strain in fibers and composites (49) (see Composite materials). The relationship between Raman spectra and the stmcture of conjugated and conducting polymers has been reviewed (50,51). In addition, a general review of ft-Raman studies of polymers has been pubUshed (52). 

The possibihty of six-coordinate sihcon species in aqueous solution has been suggested. Raman studies have indicated, however, that monosilicic acid in solution contains a tetracoordinate sihcon species (37). 

The repeat distance along the chain axis (0.468 nm) is significantly less than that calculated for a planar zigzag stmcture. Therefore, the polymer must be in some other conformation (65—67). Based on k and Raman studies of PVDC single crystals and normal vibration analysis, the best conformation appears to be where the skeletal angle, is 120°, and the torsional of opposite sign) is 32.5°. This conformation is in... 

IR and Raman studies of heterocycles today cover two different fields. For simple and symmetrical molecules very elaborate experiments (argon matrices, isotopic labelling) and complex calculations lead to the complete assignment of the fundamentals, tones and harmonics. However, the description of modes ought to be only approximate, since in a molecule like pyrazole there are no pure ones. This means that it is not correct to write that the band at 878 cm is y(CH), and the only correct assertion is that the y(CH) mode contributes to the band. On the other hand, IR spectroscopy is used as an analytical tool for identifying structures, and in this case, bands are assigned to r-iCO) or 5(NH) on the basis of a simple Nujol mull spectrum and conventional tables. Both atttitudes, almost antagonistic to each other, are discussed in this section. 

The question whieh then arises is What do we call a defect in a nanotube To answer this question, we need to define what would be a perfeet nanotube. Nanotubes are mieroerystals whose properties are mainly defined by the hexagonal network that forms the eentral cylindrical part of the tube. After all, with an aspect ratio (length over diameter) of 100 to 1000, the tip structure will be a small perturbation except near the ends. This is clear from Raman studies[4] and is also the basis for calculations on nanotube proper-ties[5-7]. So, a perfect nanotube would be a cylindrical graphene sheet composed only of hexagons having a minimum of defects at the tips to form a closed seamless structure. 

Several Raman studies have been carried out on nested nanotubes [23-26]. The first report was by Hiura et al. [23], who observed a strong first-order band at 1574 cm and a weaker, broader D-band at 1346... 

Kastner et al. [25] also reported Raman spectra of cathode core material containing nested tubules. The spectral features were all identified with tubules, including weak D-band scattering for which the laser excitation frequency dependence was studied. The authors attribute some of the D-band scattering to curvature in the tube walls. As discussed above, Bacsa et al. [26] reported recently the results of Raman studies on oxidatively purified tubes. Their spectrum is similar to that of Hiura et al. [23], in that it shows very weak D-band scattering. Values for the frequencies of all the first- and second-order Raman features reported for these nested tubule studies are also collected in Table 1. 

Solvolysis of phosphoric acids in the system HF/P2O5/H2O gave successively H2PO3F, HPO2F2 and H30+PFfi , as shown by F and P nmr spectroscopy. Raman studies show that KNO3 solvolyses according to the reaction... 

K. Lagarec and S. Desgreniers, Raman study of single crystal anatase Ti02 up to 70 GPa, Sol. Si. Comm. 

Bullock, K. R., Trischan, G.M. and Burrow, R. G., Photoelectrochemical and Microprobe Laser Raman Studies of Lead Corrosion in Sulphuric Acid , J. Electrochem. Soc., 130, 1283 (1983)... 

Bratos S., Marechal E. Raman study of liquids. I. Theory of Raman spectra of diatomic molecules in inert solutions, Phys. Rev. A4,1078-92 (1971). 

Snider S., McClung R. E. D. Raman studies of molecular reorientation in liquid sulfur hexafluoride, Can. J. Phys. 52, 1209-14 (1974). 

K.J. Maynard, and M. Moskovits, A surface enhanced Raman study of carbon dioxide coadsorption with oxygen and alkali metals on silver surfaces,/. Chem. Phys. 90(11), 6668-6679 (1989). 

This result together with the preferred formation of para-products suggests that the attacking species is electrophilic and that consecutively are involved formation of a charge transfer complex, addition of Br" ", and elimination of H" ". This picture is supported by Raman studies (ref. 24) of the system Br2-benzene-NaX. 

Insoluble sulfur obtained by CS2 extraction of commercial Crystex N data taken from conventional Raman studies using an Ar laser [177]... 

Fig. 21. Cluster conversions involving [Fe3S4]+ clusters. The cluster conversion in (c) has been proposed on the basis of EPR, VTMCD, and resonance Raman studies, but has yet to be confirmed by Mossbauer or more direct structural techniques.

Resonance Raman studies on the putative prismane protein would provide other important information. In the frequency region of 200-430 cm the putative prismane protein showed bands that at first sight seemed to be typical for Fe-S clusters, but at a closer look appeared to be broader than those observed in basic Fe-S proteins. Also, the resonance frequencies were slightly different from known Fe-S clusters, and it was contended that A prismane-type [6Fe-6S] core is clearly an excellent candidate in light of the available analytical and biophysical data [28]. 

Resonance Raman studies of the recombinant proteins showed vibrational bands at the 200-430 cm region characteristic of iron-sulfur clusters (124). Most interestingly, on Fe and O isotope sensitive band was detected at 801 cm which could be attributed to either a Fe(IV)=0 species or a monobridged Fe-O-Fe structure. This observation, together with Mossbauer analysis, which indicated a mixed N, 0, and S ligand environment for cluster 2, suggests a Fe-O-Fe or Fe=0 unit as part of the structure for cluster 2. 

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