Yield characteristics

By using a laser with less power and the beam spread over a larger area, it is possible to sample a surface. In this approach, after each laser shot, the laser is directed onto a new area of surface, a technique known as surface profiling (Figure 2.4c). At the low power used, only the top few nanometers of surface are removed, and the method is suited to investigate surface contamination. The normal surface yields characteristic ions but, where there are impurities on the surface, additional ions appear. 

Heating inorganic substances to a high temperature on a metal filament yields characteristic positive ions that can be mass analyzed for m/z value and abundance to obtain accurate isotope ratios. 

The three alkaloids all yield characteristic products on treatment with hydrochloric acid. In this way morphine yields ajjomorphine, apparently by loss of water codeine also yields ajjomorphine, accompanied by other products, but thebaine yields, with dilute hydrochloric acid, thebenine, and with strong hydrochloric acid, morphothebaine. These two are respectively secondary and tertiary bases, so that in the formation of thebenine a heterocyclic ring has been opened and a tertiary... 

Even before heating steroids frequently yield characteristic, pale yellow to dark purple colored zones, whose colors generally change on heating [4] and which are usually excited to fluorescence in long-wavelength UV light (X = 365 nm) [6]. 

None of the elemental data show any correlation with collagen yield. When compared to yield, the correlation coefficients are non-significant for C N (r = 0.4), %C (r = 0.4) and %N (r = 0.2). All samples with low elemental values are from layers of bone that showed poor histological preservation. While low values tend to come from bone with poor histological preservation, many samples from bone of equally poor preservation produced acceptable values. Lipid removal generally improved both the yield characteristics and elemental values. 

In addition, our results suggest that removal of hpids improves both yield characteristics and elemental characteristics. Recent work by Liden et al. (1995) suggests that the methanol-chloroform method used here is more effective than other methods, such as treatment with NaOH solution, or the maintenance of an acidic environment and ultrafiltration of products during collagen extraction. It is speculated that the presence of hpids in archaeological bone samples may interfere with the acid hydrolysis of protein during... 

The problem in predicting the yield characteristics of a grass/white clover sward is that the relationship between yield and proportion of white clover in the sward is not linear. Grass/white clover swards yield more dry matter than either grass or white clover swards on their own, but the point where increasing the amount of white clover in the sward actually decreases total yield has not been defined experimentally. 

The enormous temperatures attained on resistively heated sample holders can also be used to intentionally enforce the decomposition of non-volatile samples, thereby yielding characteristic pyrolysis products. Pyrolysis mass spectrometry (Py-MS) can be applied to synthetic polymers, [54] fossil biomaterial, [55] food [56] and soil [57] analysis and even to characterize whole bacteria. [58]... 

In the ARS-picture again we have to consider the q-dependence of C(q) (Eqs. 5.2 and 5.3). After Fourier transformation and considering again periodic bounding conditions, Eq. 5.17 yields characteristic relaxation rates ... 

In the last decade, LC-MS system manufacturers have commercialized hybrid instruments that can operate in the ESI or the APCI mode with just a few simple modifications. Such instrumentation, based on Bajic s first prototype [49], is able to protonate compounds in the ESI mode together with those yielding characteristic APCI signature. Castoro [50] and Fischer et al. [51] first provided the utility of the dual atmospheric pressure ionization source. 

Other similar lipase/esterase resolution processes have been developed such as the use of Bacillus that esterase to produce the substituted propanoic acids that are precursors of non-steroidal anti-inflammatory drags, snch as naproxen and ibuprofen etc., and the formation of chiral amines by Celgene. Other methods start from prochiral precursors and have the advantage that enantioselective synthesis allows the production of particular isomers in yields approaching 100%, rather than the 50% yields characteristic of resolution processes. For instance Hoechst have patented the production of enantiomers using Pseudomonas fluorescens lipase to either acylate diols or hydrolyse diacetate esters. 

We have seen that in the statistical limit simultaneous nonradiative and radiative processes proceed independently. The lifetimes and quantum yields characteristic of these several processes are then defined in terms of the relevant densities of states and matrix coupling elements connecting the initial state with the appropriate con tin ua and quasicontinua. 

Heating with an equivalent amount of phenylhydrazine often yields characteristic derivatives. Thus /f-keto esters afford 1-phenylpyrazalones (cf. Expt 8.15), while 1,3-diketones yield 1-phenylpyrazoles (cf. Expt 8.14). 

It is interesting to notice that similar effects on yielding characteristics have been reported [54] when increasing pressure to 80 kbar, as shown in Fig. 69. Here too, the decrease of strain softening with increasing pressure is opposite to behaviour observed for PMMA (Sect. 3.1.1.3). 

Iodoacetylenes as well as iodine cyanide are soft Lewis acids (Laurence etal. 1981), which interact with basic solvents yielding characteristic wavenumber shifts Av (C-I) (e g., for ICN relative to the wavenumber in CCI4 solutions). These shifts differ for soft solvents, with sulfur or selenium donor atoms or n systems, and hard solvents, with oxygen or nitrogen donor atoms. However, these authors have not converted this observation and their data to a solvent softness scale. In fact, if prorated values of A v (O-H), for phenol, relative to CCI4 solutions, see B0 H above, representing the hard basicity of the solvents, are subtracted, the remainder measures the solvent softness. Quantitatively,... 

Orcinol A mixture consisting of 0.6% ethanolic orcinol and 1% ferric chloride in dilute sulfuric acid is sprayed on the plate, which is further heated (100°C, 10 min) to yield characteristic spots. 

Like the analogous ferri- and cobalti-cyanides it is decomposed by potassium hydroxide, and also by concentrated hydrochloric acid, in the latter case with evolution of hydrocyanic acid. With certain metallic salts it yields characteristic precipitates. Thus, with ferrous salts a white precipitate is obtained with ferric, a bright yellow. 

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