Streak phase

Three of these phases are shown in Fig,7. The common structural elements are long H-zig-zag chains along the Ni close- packed rows with H near threefold sites. Up to monolayer coverage the substrate Ni atoms do not change their position. Further H, however, induces a substrate reconstruction and at 1.5ML coverage probably 1/2ML H is adsorbed on the second Ni layer. On the reconstructed surface three distinct desorption states (a, 3] and 32) observed by thermal desorption spectroscopy. The a peak is particularly sharp and can only be observed when the reconstructed 1x2 phase is present. Apparently it corresponds to H on the second Ni layer. The reconstructed 1x2 phase can be regarded as a surface hydride (Christmann et al, 1985). A reconstructed streak phase is formed upon... 

Plenary 10. Hiro-o Hamaguchi, e-mail address lilrama ,chem.s.u-tokvo.ac.ip (time and polarization resolved multiplex 2D-CARS). Two-dimensional (tune and frequency) CARS using broadband dye source and streak camera timing. Studies dynamic behaviour of excited (pumped) electronic states. Follows energy flow within excited molecules. Polarization control of phase of signal (NR background suppression). 

The detection of Hquid crystal is based primarily on anisotropic optical properties. This means that a sample of this phase looks radiant when viewed against a light source placed between crossed polarizers. An isotropic solution is black under such conditions (Fig. 12). Optical microscopy may also detect the Hquid crystal in an emulsion. The Hquid crystal is conspicuous from its radiance in polarized light (Fig. 13). The stmcture of the Hquid crystalline phase is also most easily identified by optical microscopy. Lamellar Hquid crystals have a pattern of oil streaks and Maltese crosses (Fig. 14a), whereas ones with hexagonal arrays of cylinders give a different optical pattern (Fig. 14b). 

Diffraction is usefiil whenever there is a distinct phase relationship between scattering units. The greater the order, the better defined are the diffraction features. For example, the reciprocal lattice of a 3D crystal is a set of points, because three Laue conditions have to be exactly satisfied. The diffraction pattern is a set of sharp spots. If disorder is introduced into the structure, the spots broaden and weaken. Two-dimensional structures give diffraction rods, because only two Laue conditions have to be satisfied. The diffraction pattern is again a set of sharp spots, because the Ewald sphere cuts these rods at precise places. Disorder in the plane broadens the rods and, hence, the diffraction spots in x and y. The existence of streaks, broad spots, and additional diffuse intensity in the pattern is a common... 

Figure 8.4.5 presents the streak, direct photograph illustrating the stages of transition to detonation after a weak ignition and flame acceleration phase. Four main regions may be identified ... 

Figure 7. Proposed structure model of the cne-dlnEnsicaially ordered streak jhase, the second reconstructed phase observed with the H/Ni(110) system. Again, shaded circles represent Ni atoms of the second layer.

Application of the sample as a continuous streak is also possible using commercially available simple instruments (sample applicators), which give a sample zone for preparative separation less than 3 to 4 mm wide. It is also advisable to apply the streak across the plate starting 2 cm from both edges to avoid the edge effect, which may cause the motion of the mobile phase to be faster or slower at the edges than across the center of the plate. 

Fig. 5.5.5 1 D CSI datasets showing the extent of conversion during a batch reaction. The form of the feature identified as peak B is associated with a single chemical shift i.e., it is of constant form at all positions across the bed, and therefore shows that the extent of conversion is uniform throughout the bed. The low intensity horizontal streaking" effect observed in these datasets and that shown in Figure 5.5.6 are artifacts arising from the automatic phase correction applied to the data ...

The components in the organic phase were separated first using thin-layer chromatography (TLC). The organic phase (80 ml) was streaked onto 20 plates of 1000 ym silica GF (Analtech, Inc.,... 

Signs and Symptoms Has a highly variable clinical picture. It has acute and chronic forms, and virulence varies from severe, with high mortality, to mild or even subclinical. The severe acute form is characterized by fever, lack of appetite, depression, constipation followed by diarrhea. May progress to incoordination or convulsions. Conjunctivitis is frequent and is manifested by encrustation of the eyelids and the presence of dirty streaks below the eyes caused by the accumulation of dust and feed particles. In the chronic form of the disease, pigs often survive more than 30 days. After an initial acute febrile phase, pigs may show apparent recovery but then relapse, with anorexia, depression, fever, and progressive loss of condition. 

In TLC, the sample is applied as a small spot or streak to the marked origin of stationary phase supported on a glass, plastic, or metal plate. The sample solvent is allowed to evaporate from the plate that is then placed in a closed chamber containing a shallow pool of mobile phase at... 

Fig. 11. Simulation of the physical model by means of two sources of Marangoni effect generation. The upper phase is paraffin oil and the lower phase is ethylene glycol. Through the two capillaries (the two vertical black streaks) ethyl acetate is fed.

Add 200 pi water to the cell pellet and sonicate briefly at low power. Use 50 pi homogenate for a protein determination and 100 pi for lipid extraction. To 100 pi homogenate add 4 ml chloroform/methanol 2/1 (v/v). Leave for 1 h at room temperature and add 0.8 ml of 0.73% NaCl. Vortex and centrifuge for 5 min at 1000xg to separate the phases. Remove the lower chloroform phase and add 10 nmol cho-lesteryl oleate and 10 nmol triolein as a cold carrier. Dry the sample under nitrogen. Take the sample up in 25 pi chloroform/methanol 2/1 (v/v) and spot the sample on a silica gel plate (0.5 cm streak). Rinse the tube with 25 pi chloroform/methanol 2/1 (v/v) and spot the sample on a silica gel plate. Develop the plate with hexane/diethyl-ether/acetic acid, 70/30/1 (v/v/v). Remove the plate from the tank when the solvent front almost reaches the top, dry the plate, and expose briefly to iodine vapor to localize the cholesteryl oleate. Scrape the spots into scintillation vials, mix thoroughly, and count in a scintillation counter. 

Turning to the low temperature transition of the homopolymer of PHBA at 350 °C, it is generally accepted that the phase below this temperature is orthorhombic and converts to an approximate pseudohexagonal phase with a packing closely related to the orthorhombic phase (see Fig. 6) [27-29]. The fact that a number of the diffraction maxima retain the sharp definition at room temperature pattern combined with the streaking of the 006 line suggests both vertical and horizontal displacements of the chains [29]. As mentioned earlier, Yoon et al. has opted to describe the new phase as a smectic E whereas we prefer to interpret this new phase as a one dimensional plastic crystal where rotational freedom is permitted around the chain axis. This particular question is really a matter of semantics since both interpretations are correct. Perhaps the more important issue is which of these terminologies provides a more descriptive picture as to the nature of the molecular motions of the polymer above the 350 °C transition. As will be seen shortly in the case of the aromatic copolyesters, similar motions can be identified well below the crystal-nematic transition. 

Eadie, in Ref 69, reports on a considerable amount of work done on the ability of beeswax and paraffin wax to remain coated on HMX surfaces when immersed in liq TNT. Thru measurements of contact angles, a technique used earlier on RDX/wax systems reported on by Rubin in Ref 23, it was determined that the TNT preferentially wets the HMX and the wax is stripped away. He concludes that the most important property of a desensitizing wax is that it should be readily dispersed uniformly thruout the TNT phase. He also suggests that a better desensitizer for investigation for use would be a wax or substituted hydrocarbon having a low interfacial tension with TNT. The smaller the wax droplet size the more efficiently it will be distributed and the more effectively it should desensitize. Williamson (Ref 64) in his examination of the microstructures of PETN/TNT/wax fusion-casts detected that wax is dispersed thru the cast as isolated descrete globules which he refers to as blebs or irregular or streak-like areas, surrounded by TNT (see also Ref 54)... 

Samples thus analyzed had two phase-velocity regions, the normal high-order detonation and an intermediate velocity region. The two abrupt changes in phase velocity are read from the streak records to give the distance to the intermediate region and the distance to detonation. 

The textures in homeotropic lamellar phases of lecithin are studied in lecithin-water phases by polarizing microscopy and in dried phases by electron microscopy. In the former, we observe the La phase (the chains are liquid, the polar heads disordered)—the texture displays classical FriedeVs oily streaks, which we interpret as clusters of parallel dislocations whose core is split in two disclinations of opposite sign, with a transversal instability of the confocal domain type. In the latter case, the nature of the lamellar phase is less understood. However, the elementary defects (negative staining) are quenched from the La phase they are dislocations or Grandjean terraces, where the same transversal instability can occur. We also observed dislocations with an extended core these defects seem typical of the phase in the electron microscope. 

Although many solvent developers are applicable to the acids and lactones, those containing acid have been favored. Acidic solvents, by a swamping effect, 129 suppress ionization of the sugar acids and thus prevent streaking of the acid spots.82 27 Otherwise, the ionized acids would be preferentially held by the stationary aqueous phase in the chromatogram, or would be adsorbed with resulting low RF values. In basic... 

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