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- Champagne, M, et al.
(författare)
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The use of orthogonal signal correction to improve NIR readings of pulp fibre properties
- 2001
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Ingår i: Pulp & Paper-Canada. - 0316-4004. ; 102:4, s. 41-3
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Tidskriftsartikel (refereegranskat)abstract
- In 1999 Tembec Industries and the National Renewal Energy Laboratories worked together in developing a methodology to use Near-infrared (NIR). Technology of in-house pulp fibre quality properties Q99 and Q97. The initial results with dry samples of pulp were encouraging. the wet samples results were initially disappointing using the standard chemometric techniques. Svante Wold developed a new chemometric method called Orthogonal Signal correction (OSC), which was used to obtain a good correction of Q99 in the wet pulp samples.
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| 2. |
- Andersson, Per M, et al.
(författare)
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Comparison between physicochemical and calculated molecular descriptors
- 2000
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Ingår i: Journal of Chemometrics: Special Issue: Proceedings of the SSC6, August 1999, HiT/TF, Norway . Issue Edited by Kim Esbensen. ; 14:5-6, s. 629-42
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Tidskriftsartikel (refereegranskat)abstract
- It has earlier been proven that measured physicochemical properties are useful in the selection of building blocks for combinatorial chemistry as well as for investigation of the scope and limitations of organic reactions. However, measured physicochemical properties are only available for small subsets of reagents, starting materials or building blocks; therefore it is necessary to use calculated descriptors and it is essential that the descriptors are relevant. The objective was to investigate whether three different descriptor data sets contained similar information about the chemical structure, with the major aim to investigate whether calculated descriptors contain similar information as experimental data. A total of 205 heterogeneous primary amines were characterized using three different data sets of molecular descriptor variables. The first set consisted of four physicochemical variables compiled from the literature and commercially available chemicals in chemical catalogues. From these four descriptors together with molecular weight, three additional descriptors could be calculated, resulting in a total of eight descriptor variables in the first data set. The second data set consisted of 81 calculated molecular descriptor variables relating to size, connectivity, atom count, topology and electrotopology indices. The third data set consisted of 10 semi-empirical variables (AM1). All the calculated variables were generated using the software Tsar 3.11. The descriptor variable sets were compared using principal component analysis (PCA) and partial least squares projections to latent structures (PLS). The following result shows that the different descriptor sets do contain similar latent information and that the different types of calculated variables do correlate well with the experimental data, making them suitable to use for e.g. combinatorial library design.
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| 3. |
- Andersson, Per M, et al.
(författare)
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Strategies for subset selection of parts of an in-house chemical library
- 2001
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Ingår i: Journal of Chemometrics. - : Wiley. - 0886-9383. ; 15:4, s. 353-69
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Tidskriftsartikel (refereegranskat)abstract
- When a company decides to perform biological testing of their in-house library, i.e. compounds which have been synthesized or purchased over the years, it is usually not feasible or desirable to test all of them using e.g. high-throughput screening (HTS). The limitation is the usually high number of compounds to test (104-106) leading to practical limitations and high costs in terms of both material costs and disposal considerations. Therefore it is often desirable to make a selection of which compounds to include in the biological testing. A challenge is how to make this selection in order to cover the structural space of the in-house library as well as possible. Here we present and discuss different selection strategies based mainly on statistical molecular design (SMD). These methods require different prior information about the compounds under investigation, e.g. characterization of the chemical structure, affinity/biological activity data or neither of these. Which method to be used is largely problem-dependent, i.e. the composition and origin of the library, and hence the structural space, are of great importance. Chemical and biological knowledge about the system under investigation should as far as possible be considered when making the final decision on which method to apply.
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| 6. |
- Eriksson, Lennart, et al.
(författare)
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Three-block bi-focal PLS (3BIF-PLS) and its application in QSAR
- 2004
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Ingår i: SAR and QSAR in Environmental Research. - : Informa UK Limited. - 1062-936X .- 1029-046X. ; 15:5 & 6, s. 481-99
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Tidskriftsartikel (refereegranskat)abstract
- When X and Y are multivariate, the two-block partial least squares (PLS) method is often used. In this paper, we outline an extension addressing a special case of the three-block (X/Y/Z) problem, where Z sits "under" Y. We have called this approach three-block bi-focal PLS (3BIF-PLS). It views the X/Y relationship as the dominant problem, and seeks to use the additional information in Z in order to improve the interpretation of the Y-part of the X/Y association. Two data sets are used to illustrate 3BIF-PLS. Example I relates to single point mutants of haloalkane dehalogenase from Sphingomonas paucimobilis UT26 and their ability to transform halogenated hydrocarbons, some of which are found as organic pollutants in soil. Example II deals with soil remediation capability of bacteria. Whole bacterial communities are monitored over time using "DNA-fingerprinting" technology to see how pollution affects population composition. Since the data sets are large, hierarchical multivariate modelling is invoked to compress data prior to 3BIF-PLS analysis. It is concluded that the 3BIF-PLS approach works well. The paper contains a discussion of pros and cons of the method, and hints at further developmental opportunities.
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