[article]
| Titre : |
A consumer cross-over trial suggests that there are significant seasonal changes of the tensile properties (wet) of human hair |
| Type de document : |
texte imprimé |
| Auteurs : |
Franz J. Wortmann, Auteur ; Gabriele Wortmann, Auteur |
| Année de publication : |
2024 |
| Article en page(s) : |
p. 153-161 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Analyse de variance En statistique, l'analyse de la variance (terme souvent abrégé par le terme anglais ANOVA : ANalysis Of VAriance) est un ensemble de modèles statistiques utilisés pour vérifier si les moyennes des groupes proviennent d'une même population. Les groupes correspondent aux modalités d'une variable qualitative (p. ex. variable : traitement; modalités : programme d'entrainement sportif, suppléments alimentaires ; placebo) et les moyennes sont calculés à partir d'une variable continue (p. ex. gain musculaire).
Ce test s'applique lorsque l'on mesure une ou plusieurs variables explicatives catégorielles (appelées alors facteurs de variabilité, leurs différentes modalités étant parfois appelées "niveaux") qui ont de l'influence sur la loi d'une variable continue à expliquer. On parle d'analyse à un facteur lorsque l'analyse porte sur un modèle décrit par un seul facteur de variabilité, d'analyse à deux facteurs ou d'analyse multifactorielle sinon. (Wikipedia)
Cheveux -- Croissance
Cheveux -- Propriétés mécaniques
Cheveux -- Variations saisonnières
Cheveux humides
FilamentsFibre de longueur infinie ou extrême comme celle qu'on trouve dans la soie à l'état naturel. Les fibres manufacturées sont extrudées en filaments qui sont transformés en fils continus, en fibres courtes ou en câbles.
Justification de l'allégation
Traction (mécanique)
|
| Index. décimale : |
668.5 Parfums et cosmétiques |
| Résumé : |
- Objectives : Through the cooperation with an industrial partner, we gained a set of data for the tensile properties (wet) of human hair. The hair samples originated from a cross-over study with two groups of individuals, using for a topical application sequentially two products (A and B). Each phase of the study lasted 6 months. The phases of the study by chance covered first largely the winter and then the summer period. Initially, tensile variables were chosen, which not only reflect the mechanical properties of hair (modulus, break strain, and break stress) but which are also considered to have a good connection to practice-relevant hair properties. The initial analysis of the data showed that changes were observed for the variables due to the treatment phases. However, these were either small or difficult to interpret.
- Methods : Against this background and using two-factor analysis of variance, we investigated the hypothesis that the tensile properties of hair (wet) may show significant seasonal changes. For this, we chose those two independent variables, which reflect the properties of the intermediate filaments (modulus) and the matrix (break strain) in the composite structure of the hair cortex.
- Results : The results support the ‘seasonal’ hypothesis and clearly show that the variables show significant changes from Winter to Summer (modulus: 10% increase; break strain: 3% decrease). The seasonal effect was thus a major reason, why the first stage of the analysis of the data was inconclusive.
- Conclusions : The tensile properties of the main morphological components of the cortex show distinct seasonal changes. Towards the summer, the hair becomes stiffer and more brittle. Furthermore, the results suggest that seasonal effects may need to be taken into account when conducting studies on lengths of hair grown during different seasons. |
| Note de contenu : |
- MATERIALS AND METHODS : Study design and sets of hair samples - Hair fibre testing - Sample preparation and diameter determination - Tensile testing and choice of variables - Two-factor ANOVA
- RESULTS AND DISCUSSION : Modulus (wet) - Break strain
- Table 1 : Overall sample acquisition through the trial, arranged with respect to the two factors Phase (1, 2) and Treatment (A, B)
- Table 2 : Results of the 2F-ANOVA for modulus
- Table 3 : Results of the 2F-ANOVA for break strain |
| DOI : |
https://doi.org/10.1111/ics.12917 |
| En ligne : |
https://drive.google.com/file/d/1UpsnG9LvkT28wvy8MirS8SkpQU2pHrtG/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40735 |
in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 46, N° 2 (04/2024) . - p. 153-161
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A consumer cross-over trial suggests that there are significant seasonal changes of the tensile properties (wet) of human hair in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 46, N° 2 (04/2024)
