Deconvolution methods reference

Both methods are also limited in accuracy of secondary structure determinations because spectral peaks must be deconvolved estimates are made of the overlapping contributions of different structural regions. These estimates may introduce error based on the reference spectra used and because deconvolution methods equate crystallographic secondary structure with the secondary structure of the protein in solution (Pelton and McLean, 2000). As amyloid fibrils are neither crystalline nor soluble, there may be even greater error in estimates of secondary structure. To compound the problem, estimates of /f-sheet content are less reliable than those of a-helix, because of the flexibility and variable twist of / -structure (Pelton and McLean, 2000). In addition, / -sheet and turn bands overlap in FTIR spectroscopy (Jackson and Mantsch, 1995 Pelton and McLean, 2000). Side chains also contribute to spectral peaks in both methods, and they can skew estimates of secondary structure if not properly accounted for. In FTIR spectra, up to 10-15% of the amide I band may arise from side chain contributions (Jackson and Mantsch, 1995). 

UV examination has been proved to be a relevant method for the study of water and wastewater quality using deconvolution methods of UV spectra. The absorbency spectrum of water can be decomposed from a few number of characteristic spectra (reference spectra). Therefore, a given spectrum can be reconstructed with a linear combination of reference spectra and all additive parameters can be computed with the same linear combination. Qualitative and quantitative results in terms of classical parameters such as TOC, COD, BOD5, TSS, nitrate,... can be provided. 

The deconvolution methods are multi-wavelength procedures which can be classified with regard to the selection procedure of reference spectra. These spectra can be chosen from specific compounds (Maier, 1981), from independent spectra of real samples (Thomas et al., 1993), statistically selected (Gallot and Thomas, 1993) or from a mixed choice of spectra of specific compounds and of real samples. Reference spectra are not universal recently, according to the complexity of the composition of wastewater, SECOMAM has developed UVPro software based on advanced UV spectral deconvolution (Patent 00402038-4, 17 July 2000) which allows creating dedicated models and determination of reference spectra from a set of studied water and wastewater UV spectra an automatic calibration step is carried using parameters values obtained by standard or reference method. Deconvolution is used in order to find a linear relation between measured and UV estimated values for any parameter. 

As described previously, the deconvolution method of UV spectra allows to measure quantitative parameters (nitrates, surfactants for example) as well as to estimate some physico-chemical parameters (TOC, COD, BOD5, TSS). The obtained information (qualitative and quantitative) are enough relevant and robust to be integrated in the decision making process and water resources management. Indeed, the performances of Portable UV spectrophotometer have been evaluated and compared to a reference method and have shown good correlation (Gonzalez et al., 2007). In addition, performance criteria have been verified in field conditions in order to assess the impact of these conditions and to demonstrate the portability of the instrument. 

Starting from the recent development of the UV multiwavelength deconvolution method designed for natural and wastewater examination [12] previously described (Chapter 2), several defined reference spectra, and different combinations of them, lead actually to the constitution of three basis of reference spectra, used for the restitution of spectra of natural and urban wastewater samples [25], These three bases allow restituting, respectively, raw or biologically treated sewage, physico-chemically treated sewage, and natural water. In this approach, the type of reference spectra is not all related to specific compounds. Notice that the spectrum related to LAS appears in each basis, as these compounds can be present in natural water or wastewater. 

As with all aromatic compounds, aromatic amines absorb relatively strongly in the UV region (see Chapter 11). A first study [33], based on the use of the deconvolution method, has been applied to the estimation of aniline derivative concentrations in industrial wastewater. For the purpose, a basis of reference spectra (see Chapter 2) has been defined by including characteristic average spectra for global and chlorinated aniline mixtures. 

The in vivo release rate or input function is first determined. For drugs with a linear disposition kinetics this may be done using the LSA-based deconvolution methods previously discussed. Step 1 requires a suitable reference administration for the deconvolution. Dual-step methods are also denoted as reference-based methods. Three scenarios exist depending on the references given below. 

An IV reference is available. The absorption rate may be determined by deconvolution using a direct deconvolution method or a prescribed input function method as described above. 

An IR reference is available. If the absorption from an immediate-release (IR) formulation is a simple first-order process (i.e., described by a first-order absorption rate constant then it is possible by a relative deconvolution method or other means to obtain the shape of the absorption profile. ... 

It is obvious that the Boehm titration method is the most popular one for the determination of various types of acidic (and basic) surface functionalities in carbon materials. From 1966 until 2002, when Boehm himself published a critical assessment of the analysis of surface oxides on carbon [201], an exhaustive utilization of this method has been desaibed by many authors. They underlined its simplicity, but pointed out also the need for using other complementary methods such as potentiometric titration, tanperature-programmed desorption (TPD), spectroscopic methods (mainly XPS and FTIR), and thermodynamic approaches such as calorimetry. The case of TPD is of special interest, to identify oxygenated functionalities. However, the CO and CO2 peaks must certainly be deconvo-luted before the surface composition can be estimated. Thus, a quantitative TPD analysis of surface functional groups is sensitive to the deconvolution method and to experimental conditions. The results are generally discussed in relation to those of DRIFTS and XPS analysis, as can be seen from the references listed in Table 3.1. 

Morris GA, Barjat H and Horne TJ (1997) Reference deconvolution methods. Progress in NMR Spectroscopy 31 197-257. 

The major impetus for the development of solid phase synthesis centers around applications in combinatorial chemistry. The notion that new drug leads and catalysts can be discovered in a high tiuoughput fashion has been demonstrated many times over as is evidenced from the number of publications that have arisen (see references at the end of this chapter). A number of )proaches to combinatorial chemistry exist. These include the split-mix method, serial techniques and parallel methods to generate libraries of compounds. The advances in combinatorial chemistry are also accompani by sophisticated methods in deconvolution and identification of compounds from libraries. In a number of cases, innovative hardware and software has been developed tor these purposes. 

If we consider only a few of the general requirements for the ideal polymer/additive analysis techniques (e.g. no matrix interferences, quantitative), then it is obvious that the choice is much restricted. Elements of the ideal method might include LD and MS, with reference to CRMs. Laser desorption and REMPI-MS are moving closest to direct selective sampling tandem mass spectrometry is supreme in identification. Direct-probe MS may yield accurate masses and concentrations of the components contained in the polymeric material. Selective sample preparation, efficient separation, selective detection, mass spectrometry and chemometric deconvolution techniques are complementary rather than competitive techniques. For elemental analysis, LA-ICP-ToFMS scores high. 

Reference Deconvolution, Phase Correction and Line Listing of NMR Spectra by the ID Filter Diagonalization Method. 

Reference deconvolution is unusual among data processing methods in using internal evidence to repair the damage done to the spectral data by instrumental imperfections parenthetically, it may be noted that the form of the correction function R t) itself can be a useful guide to instrumental fault-finding. The principal uses of reference deconvolution are in the pro-... 

Although a number of effective deconvolution algorithms do not use Fourier methods, these methods shed considerable light on the performance of the algorithms. For this reason, we introduce the Fourier transform and outline some of its most-useful properties. Only a brief treatment is given here. For additional detail, we again refer the reader to the excellent practical text on this subject by Bracewell (1978). 

Mathematically speaking, deconvolution refers to the method or methods used to solve the convolution integral equation... 

In the literature Raman spectroscopy has been used to characterize protein secondary structure using reference intensity profile method (Alix et al. 1985). A set of 17 proteins was studied with this method and results of characterization of secondary structures were compared to the results obtained by x-ray crystallography methods. Deconvolution of the Raman Amide I band, 1630-1700 cm-1, was made to quantitatively analyze structures of proteins. This method was used on a reference set of 17 proteins, and the results show fairly good correlations between the two methods (Alix et al. 1985). 

One method of reducing the effects of the line-broadening due to the z-gradient present during data acquisition is to use reference deconvolution ... 

Figure 8.2.7 Reference deconvolution applied to the methanol peak (a) original peak (b) methanol peak deconvolved to a 2 Hz Lorenzian lineshape (c) gradient-shifted methanol peak (d) gradient-shifted methanol peak deconvolved to the same 2 Hz Lorenzian lineshape (e) comparison of the sub-spectrum of the methanol sample using the subtraction algorithm with (sharp peak) and without (flattened peak) reference deconvolution. Reprinted from Hou, T., MacNamara, E. and Raftery, D., NMR analysis of multiple samples using parallel coils improved performance using reference deconvolution and multi-dimensional methods , Anal. Chem. Acta, 400, 297-305, copyright (1999), with permission of Elsevier Science...

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