Diffusion peak

Similarly to the fully labelled stars [150], the peak structure in the generalized Kratky plot for core and average contrast conditions is also quite well reproduced by calculating S(Q) on the basis of an ideal (v = 1/2) star conformation. The swollen conformation calculations predict a more diffuse peak in both cases. 

HBCD can be determined by GC-MS, using methods similar to those developed for PBDE determinations. As the response factors of the three diastereomers do not appear to differ very much, HBCD can be quantified as total HBCD. However, the different isomers have not so far been separated by this technique. Moreover, because isomers of HBCD are thermally labile (it is known that HBCD decomposition takes place between 240°C and 270°C), elution from a GC column usually results in a broad, diffuse peak. In addition, a number of chromatographic peaks corresponding to different breakdown products were detected. These peaks could interfere with some BFR congeners (e.g., BDE-99) [102,110]. TBBPA can be also determined by GC-MS however, a derivatization step must be carried out prior to injection on the GC system. 

It is noted that on increasing the scan rate the intensity of the adsorption peak (which linearly increases with v) tends to become larger than that of the diffusive peak (which linearly increases with v1/2), such that at high scan rates the diffusive peak may completely disappear. 

Note This explains the occurence of diffuse peaks due to metastable ion dissociations at fractional m/z values in the B scan spectra of B and EB instruments (Chap. 2.7.1). [83,84] In turn, the mass spectra obtained from BE instruments do not show any metastable ion peaks in normal operation. 

X-ray diffraction (Shimadzu XRD-6000) measurements are carried out using a Cu Ka 1.54060 A radiation source. Figure 2 shows comparative X-ray diffraction patterns of the NPyc along with Nafion 417 membrane and Pyc powder control systems. As can be seen, the Pyc powder shows a broad XRD 20 peak centered at 30° and other diffuse peaks are in the range of 40-60°. 

According to MS data, volatile products of thermal degradation contain HCl. The mass spectra exhibit two diffuse peaks in the ranges of the highest weight loss rate. 

A test for the sensitivity of a fluorimeter is to measure the intensity of fluorescence of the Raman diffusion peak of a cell filled with water and with an optical pathlength of 1 cm. If the wavelength of excitation is regulated to 250 nm, at which wavelength must the measurement be made (the Raman displacement of water is 3 380 cm-1) ... 

Because of the mathematical relationship involved, the mass of a metastable peak m, called the diffuse peak, will seldom be at a nominal mass. It will usually appear at fractional values (Fig. 16.29). 

Dead time, 7 Dead volume, 13 DEAE cellulose, 88 Deconvolution (spectrum), 215 Deflection equation, 297 Degrees of freedom, 168 Derivative spectrometry 215 Deshielding, 139 Deuterium arc lamp, 199 Diffuse peak, 324 Diffuse reflection, 180 Diffusion coefficient, 5, 102 Diffusion current, 362 Diode array, 200 Distribution isotherm, 9 Double beam, 169 DTGS, 175... 

Generally, lipids forming lamellar phase by themselves, form lamellar lipoplexes in most of these cases, lipids forming Hn phase by themselves tend to form Hn phase lipoplexes. Notable exceptions to this rule are the lipids forming cubic phase. Their lipoplexes do not retain the cubic symmetry and form either lamellar or inverted hexagonal phase [20, 24], The lamellar repeat period of the lipoplexes is typically 1.5 nm higher than that of the pure lipid phases, as a result of DNA intercalation between the lipid bilayers. In addition to the sharp lamellar reflections, a low-intensity diffuse peak is also present in the diffraction patterns (Fig. 23a) [81]. This peak has been ascribed to the in-plane positional correlation of the DNA strands arranged between the lipid lamellae [19, 63, 64, 82], Its position is dependent on the lipid-DNA ratio. The presence of DNA between the bilayers has been verified by the electron density profiles of the lipoplexes [16, 62-64] (Fig. 23b). 

The information from the oriented glasses is not redundant since it suggests in broad terms the different origins of the diffuse peaks in the scattering curve. Those which are weighted... 

The roots of tandem mass spectrometry can be traced back to fundamental studies conducted by McLafferty and coworkers in the late 1960 s on metastable ion analysis (19-21). Metastable ions are ions which undergo decompositions in the field free regions of mass spectrometers giving rise to unusual diffuse peaks in the resulting... 

The part of the distribution function that includes the nonmetal interactions only, is the dominant part, as shown by the comparison in Fig. 10, but has much less distinct features than the part involving the metal atom interactions. It shows diffuse peaks in the region around 3.0 A, which can be related to H20—H20, Cl—H20, and Cl—Cl dis-... 

Our support precursor having a Mg Al molar ratio of about 3 1 shows an x-ray diffraction pattern typical of hydrotalcite (see Figure la) (10). After calcination at 873 K the resulting diffraction pattern exhibits diffuse peaks corresponding to MgO (Figure lb). No evidence for separate crystalline aluminum phases was found so A1 cations probably remain closely associated with or dissolved in the MgO structure. However, it is possible that amorphous alumina phases, not detectable by x-ray diffraction, may be present in our mixed oxide. 

Fig. 8.3. Typical TG signals (circles) after photoexcitation of PYP (a) in a buffer solution and (b) in the buffer with an eluted fraction from the bacterium. The rise-decay components in a few milliseconds to a few hundred milliseconds range represent the protein diffusion signal. The enhancement of the diffusion peak of (b) is due to the intermolecular interaction between the pB species and DNA of the bacterium. The best-fitted curves by (8.9) are shown by the solid lines. The assignments of the signal components are shown...

To examine these possibilities, the TG signals at various AppABLUF concentrations were examined. If the dimerization were the main cause of the difference in D, this reaction rate should be slower at a lower concentration. On the other hand, if a conformational change was responsible for the reduction in D, the temporal profile of the TG signal should not depend on concentration, besides the absolute intensity. Under a low q2 condition (q2 = 3.9 x 1010 m 2), the temporal profile of the diffusion signal was relatively similar at any concentration. At this low q2, the diffusion peak was reproduced by a bi-exponential function with Dr = 8.8 x 10 11m2s 1 and Dp = 7.2 x 10-11m2s-1 after 80 ms at any concentration. Therefore the final product should be the same at all concentrations after a sufficiently long time. 

Fig. 5.6 shows the XRD powder pattern of a 23-year-old paste of (f-CjS. Patterns of fully reacted CjS pastes are similar, except that the CH peaks are relatively more intense. The only effects definitely attributable to C-S-H are the diffuse peak at 0.27-0.31 nm and the somewhat sharper one at 0.182 nm. Attempts to obtain selected area electron diffraction patterns from the C-S- H of calcium silicate or cement pastes have usually failed, but, occasionally,. particles present in ground and redispersed samples have yielded poorly defined patterns (G41,C25) (Section 5.4.6). A later study by this method (M48) has been severely, and in the writer s opinion justifiably, criticized (G45).. 1... 

Besides the stable ions, metastable ions are also known to be formed in the ionization process. These ions have a short half-life. Some start dissociating in the ionization chamber, but a significant number will still be able to leave it, continuing to dissociate during their passage to the detector. They generate diffuse peaks in the mass spectra. 

The simultaneous wide-angle XRD pattern recorded at -8°C in emulsion (Fig. 1, insert) shows a single peak with a SS of 4.21 A on a diffuse peak centered at about 4.5 A corresponding to the X-ray signature of hydrocarbon chains in the liquid state (5). The single peak corresponds to the crystallization of the alkyl chains... 

Ammonia gives a broad and diffuse peak. Only traces of pyrazine and dimethylpyrazine are more easily identified. These compounds probably result from the cyclization of the radical fragments formed from the thermal decomposition of the polymer. 

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