Base composition analysis

S. A. Base composition analysis of human mitochondrial DNA using electrospray ionization mass spectrometry a novel tool for the identification and differentiation of humans. Anal Biochem 2005, 344, 53-69. 

Base Composition Analysis of Phosphorothioate-Modified Oligonucleotides by HPLC of an Enzyme Digest... 

Surface composition analysis by LEIS is based on the use of noble gas ions as projectiles, making use of the superb surface sensitivity of LEIS under these conditions. A consequence of this surface sensitivity is that the LEIS energy spectrum consists of lines, one per element, if the masses differ sufficiently. The lines are narrow, because inelastic energy losses play a minor role here. Thus, the information on the atomic species present is deduced from the energy of the back-scattered ions, which can be converted to the mass of the scattering center. (Eig. 3.55 [3.141]). In Eig. 3.55 it is shown that the mass range, where LEIS is sensitive, depends on the projectile mass. 

A clue to the chemical basis of base pairing in DNA came from the analysis of the base composition of various DNAs by Erwin Chargaff in the late 1940s. His data showed that the four bases commonly found in DNA (A, C, G, and T) do not occur in equimolar amounts and that the relative amounts of each vary from species to species (Table 11.3). Nevertheless, Chargaff noted that certain pairs of bases, namely, adenine and thymine, and guanine and cytosine, are... 

D, W. Blair, CombustFlame 20 (1), 105—9 (1973) CA 78, 113515 (1973) A simple heat-transfer model is coupled with an Arrhenius-type pyrolysis law to study the effect of solid-state heat-transfer losses on burning rates of solid rocket-proplnt strands. Such heat-transfer losses materially affect the burning rates and also cause extinction phenomena similar to some that had been observed exptly. Strand diam and compn, adiabatic burning rate, and the heat-transfer film coeff at the strand surface are important variables. Results of theoretical analysis are applied to AP-based composite solid proplnts... 

For the orientation-based structure analysis of MAPs, uniformly oriented lipid bilayers are typically prepared on solid supports as illustrated in Fig. 2 [23, 47, 55]. These mechanically oriented membranes are advantageous for static ssNMR experiments, as they provide a robust way to orient a sample with any desired lipid composition, peptide concentration, and at any desired temperature. The lipids... 

We are grateful to the American Museum of Natural History and the Metropolitan Museum of Art for permission to sample specimens for compositional analysis. This material is based upon work supported by the National Science Foundation under Grant No. BNS76--3397. Aspects of the investigation were carried out under the auspices of the U. S. Department of Energy. 

In addition to providing the means for calculating the isotopic compositions of ancient fluids based on analysis of minerals, mineral-fluid isotope fractionation factors provide an opportunity to combine fractionation factors when there is a common substance such as water. A fundamental strategy for compiling databases for isotopic fractionation factors is to reference such factors to a common substance (e.g., Friedman and O Neil 1977). For example, the quartz-water fractionation factor may be combined with the calcite-water fractionation factor to obtain the quartz-calcite fractionation factor at some temperature. It is now recognized, however, that the isotopic activity ratio of water in a number of experimental determinations of mineral-fluid fractionation factors has been variable, in part due to dissolution of... 

Near infrared spectroscopy (NIRS), a technique based on absorption and reflectance of monochromatographic radiation by samples over a wavelength range of 400-2500 run, has been successfully applied for food composition analysis, for food quality assessment, and in pharmaceutical production control. NIRS can be used to differentiate various samples via pattern recognitions. The technique is fast and nondestructive method that does not require sample preparation and is very simple to use compared too many other analytical methods such as HPLC. The drawback of NIRS, however, is that the instrument has to be calibrated using a set of samples typically 20-50 with known analyte concentrations obtained by suitable reference methods such as FIPLC in order to be used for quantitative analyses. Simultaneous quantification of the... 

Ohkoshi, M. and Kato, A. (1992). Distribution of substituents in acetylated wood as determined by nuclear magnetic resonance analysis. In Pacific Rim Bio-Based Composites Symposium Chemical Modification of Lignocellulosics, Plackett, D.V. and Dunningham, E.A. (Eds.). ERl Bulletin, 176, pp. 25-32. 

In the pmr data for the terpolymer, overlap between the CH3 absorption of the oxime ester and the backbone absorption is greater than in the copolymer pointed out in Figure k. Thus, while the agreement between the Raman and pmr data for the terpolymer is not very good, (lT-32 difference), it is completely within the experimental error of the pmr data. This large error and the fact that pmr can only distinguish two of the components of the terpolymer demonstrate that it is unsuited for compositional analysis of this system. Based on the agreement with published reactivity ratios and with the elemental analysis of the P(M-CN) copolymer, it is assumed that the Raman data are more accurate. 

IQiowledge of parameters such as reactivity ratios, is necessary for synthesis of polymer based resists, and an accurate method of analysis should be useful in various areas associated with resist development such as quality control. Raman spectroscopy provides a convenient, absolute, nondestructive method for compositional analysis of polymer systems which, if an internal standard is present, does not require standards of known composition or ancillary calibration curves. The accuracy, with appropriate selection of experimental conditions such as slit width and integration time, is limited only by the instrumentation. 

A TGA curve has limited ability to identify the sample or determine its composition if its nature is unknown. However, there are still many unique analytical applications based on TGA. Two primary applications are qualitative identification and compositional analysis. 

A quantitative surface compositional analysis requires the comparison of the experimental yield of the individual clusters with corresponding yields obtained theoretically this may be done by numerical simulation of the complex collision process but the accuracy of the result cannot yet be ascertained. The accuracy of the compositional analysis depends to some extent on such poorly known factors as the interatomic potential, ionization cross-sections and quantum-mechanical corrections to a treatment based on classical trajectories. 

However, there is not enough information available to determine the effect of montmorillonite 2 1 layer compositions on ion selectivity. We can only base our analysis upon the observation that in rocks where potassium is available, an interlayered illite-montmorillonite phase appears near 100°C at depths greater than 2Km. 

Zeolites (3 were treated with a NaBO, solution, and the porous properties of boronated samples were investigated by sorption measurements with benzene and nitrogen as adsorbate, TEM, SEM and composition analysis. It is shown that the micropores are converted into the mesopores and the mesopores are developed into larger mesopores due to the extraction of framework silicon by base. The small atom size of boron and the poor stability of boron in framework should be responsible for the silicon removal in a large amount. The dissolution of silicon also causes the corrosion of outer surface of particles and the decrease of particle size. 

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