Principal component analysis in studies of substituent-induced chemical shifts of 1,4-disubstituted benzenes

2001 ◽  
Vol 39 (6) ◽  
pp. 316-322 ◽  
Author(s):  
Eduardo L. Canto ◽  
Ljubica Tasic ◽  
Roy E. Bruns ◽  
Roberto Rittner
Keyword(s):  
Principal Component Analysis ◽  
Chemical Shifts ◽  
Principal Component ◽  
Component Analysis

Principal Component Analysis and Target Testing of Substituent Effect Using Carbonyl Stretching Frequency and 13C NMR Chemical Shift Data Matrices

1993 ◽  
Vol 58 (2) ◽  
pp. 385-394 ◽  
Author(s):  
Ghazwan F. Fadhil
Keyword(s):  
Principal Component Analysis ◽  
Substituent Effect ◽  
Chemical Shifts ◽  
Linear Regression Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Multiple Linear Regression Analysis ◽  
Probe Site ◽  
C Nmr ◽  
Data Matrices

Principal component analysis technique has been applied to analyse the substituent effect on carbonyl stretching frequency and 13C NMR chemical shifts. The general formula for the investigated molecules is X-G-Y, where X represents the set of substituent (OMe, Me, F, Cl, Br, CN and NO2), Y is the probe site and G is benzene ring. According to the indicator function two significant components are responsible for the substituent effect. The validity of several substituent parameters have been investigated by target testing technique. Invariabily substituent parameters derived by iterative multiple linear regression analysis viz. σR (Reynolds), σF (Reynolds) and σR (NMR) have lower SPOIL values when compared with other substituent parameters. Model designing f IR and 13C NMR data matrices separately have shown that models which incorporate σR (Reynolds) and σF (Reynolds) or σR (NMR) and a substituent field parameters have the lowest root mean square error RMSE. Substituent effect on several properties are better correlated with Reynolds' σR and σF than with other commonly used substituent parameter(s). The orthogonality of substituent parameters used in the model can be achieved by including the methyl group in the substituent set.

scholarly journals Use of 13C-NMR Chemical Shifts; Application of Principal Component Analysis for Categorizing Structurally Similar Methoxyflavones and Correlation Analysis between Chemical Shifts and Cytotoxicity

2021 ◽  
Vol 69 (2) ◽  
pp. 199-202
Author(s):  
Ryuichiro Suzuki ◽  
Yoshihiro Uesawa ◽  
Yoshihito Okada ◽  
Takumi Horikawa ◽  
Yui Okabe ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Correlation Analysis ◽  
Chemical Shifts ◽  
Principal Component ◽  
Component Analysis ◽  
Nmr Chemical Shifts ◽  
C Nmr

scholarly journals Structural Polymorphism of Chitin and Chitosan in Fungal Cell Walls From Solid-State NMR and Principal Component Analysis

2021 ◽  
Vol 8 ◽  
Author(s):  
Liyanage D. Fernando ◽  
Malitha C. Dickwella Widanage ◽  
Jackson Penfield ◽  
Andrew S. Lipton ◽  
Nancy Washton ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Cell Wall ◽  
Cell Walls ◽  
Chemical Shifts ◽  
Principal Component ◽  
Component Analysis ◽  
Antifungal Drugs ◽  
Fungal Cell ◽  
Structural Resistance ◽  
Chitin And Chitosan

Chitin is a major carbohydrate component of the fungal cell wall and a promising target for novel antifungal agents. However, it is technically challenging to characterize the structure of this polymer in native cell walls. Here, we recorded and compared 13C chemical shifts of chitin using isotopically enriched cells of six Aspergillus, Rhizopus, and Candida strains, with data interpretation assisted by principal component analysis (PCA) and linear discriminant analysis (LDA) methods. The structure of chitin is found to be intrinsically heterogeneous, with peak multiplicity detected in each sample and distinct fingerprints observed across fungal species. Fungal chitin exhibits partial similarity to the model structures of α- and γ-allomorphs; therefore, chitin structure is not significantly affected by interactions with other cell wall components. Addition of antifungal drugs and salts did not significantly perturb the chemical shifts, revealing the structural resistance of chitin to external stress. In addition, the structure of the deacetylated form, chitosan, was found to resemble a relaxed two-fold helix conformation. This study provides high-resolution information on the structure of chitin and chitosan in their cellular contexts. The method is applicable to the analysis of other complex carbohydrates and polymer composites.

A German version of the Intermittent Claudication Questionnaire (ICQ): cultural adaptation and validation

VASA ◽  
2012 ◽  
Vol 41 (5) ◽  
pp. 333-342 ◽  
Author(s):  
Kirchberger ◽  
Finger ◽  
Müller-Bühl
Keyword(s):  
Principal Component Analysis ◽  
Intermittent Claudication ◽  
Completion Time ◽  
Short Form ◽  
Principal Component ◽  
Component Analysis ◽  
German Version ◽  
Average Completion Time ◽  
Sf 36 ◽  
Related Quality

Background: The Intermittent Claudication Questionnaire (ICQ) is a short questionnaire for the assessment of health-related quality of life (HRQOL) in patients with intermittent claudication (IC). The objective of this study was to translate the ICQ into German and to investigate the psychometric properties of the German ICQ version in patients with IC. Patients and methods: The original English version was translated using a forward-backward method. The resulting German version was reviewed by the author of the original version and an experienced clinician. Finally, it was tested for clarity with 5 German patients with IC. A sample of 81 patients were administered the German ICQ. The sample consisted of 58.0 % male patients with a median age of 71 years and a median IC duration of 36 months. Test of feasibility included completeness of questionnaires, completion time, and ratings of clarity, length and relevance. Reliability was assessed through a retest in 13 patients at 14 days, and analysis of Cronbach’s alpha for internal consistency. Construct validity was investigated using principal component analysis. Concurrent validity was assessed by correlating the ICQ scores with the Short Form 36 Health Survey (SF-36) as well as clinical measures. Results: The ICQ was completely filled in by 73 subjects (90.1 %) with an average completion time of 6.3 minutes. Cronbach’s alpha coefficient reached 0.75. Intra-class correlation for test-retest reliability was r = 0.88. Principal component analysis resulted in a 3 factor solution. The first factor explained 51.5 of the total variation and all items had loadings of at least 0.65 on it. The ICQ was significantly associated with the SF-36 and treadmill-walking distances whereas no association was found for resting ABPI. Conclusions: The German version of the ICQ demonstrated good feasibility, satisfactory reliability and good validity. Responsiveness should be investigated in further validation studies.

Review of Three-Mode Principal Component Analysis: Theory and Applications, Vol. 2.

1984 ◽  
Vol 29 (11) ◽  
pp. 915-916
Author(s):  
William R Koch
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Analysis Theory
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