1,487 research outputs found
Thermal analysis and synergistic tools for the development of a semi-permanent hair straightening technology
No full textThis research was carried out with the objective to develop a thermal analysis protocol into a method of damage assessment and claims support for a new semi-permanent hair straightening technology. The investigation determined the effects of the treatment on hair fibre composition and properties using Modulated Differential Scanning Calorimetry (MDSC) [1], Fourier Transform Infrared Spectroscopy (FTIR) [2], Gel Electrophoresis (SDS-PAGE) [3] and curl retention tests [4]. The effects of the new cysteamine treatment are compared with effects of a standard thioglycolate treatment and the daily use of straightening irons. Virgin, Caucasian hair was treated once with each chemical treatment and washed every day for 84 days. In a parallel study, hair was washed and straightened repeatedly using a standardised protocol at 190oC for 84 days. Samples were taken after 2, 28, 56 and 84 days for analysis by MDSC in water, ATR- and Trans-FTIR. Separate samples were treated once and subjected to curl retention tests and protein analysis. DSC measurements in water yield the keratin denaturation enthalpy (ΔHD), which relates to the thermal stability of the keratin intermediate filaments (KIFs), and the denaturation temperature (TD), which relates to the properties of the keratin associated-proteins (KAPs). The results show that chemical and thermal straightening cause a reduction in α-helix content and matrix viscosity. FTIR measurements give information on the formation of cysteic acid in the cuticle cells and the cortex. ATR-FTIR showed that the cysteamine–based treatment produces less cysteic acid in the cuticle layers than the standard treatment. Curl retention and SDS-PAGE were used to show the variability in the efficacy of the cysteamine treatment related to the heterogeneity of human hair. The results from both tests show that an individual’s hair will react with the product to a different extent, depending on the extractability of the keratin protein groups.In conclusion, we deduce that all straightening techniques, chemical and thermal, have a pronounced effect on the structural and chemical properties of hair fibres. These effects can be used to further develop and optimize this and related products. DSC has been shown to be an integral synergistic technique for the investigation of changes to hair morphology.This research was supported by the UK Technology Strategy Board under the Knowledge Transfer Partnership scheme.Cyril Keattch Award, Thermal Methods Group, Royal Society of Chemistry, 2014.[1] F.J. Wortmann, G. Wortmann, J. Marsh, K. Meinert. J. Struct. Biol., 177 (2012) 553. [2] V. Signori, D. Lewis. Int. J. Cosmet. Sci., 19 (1997) 1-13.[3] A.M. Zalfen, G. Wortmann, F.J. Wortmann. SOEFW Journal, 131 (2005) 40.[4] F.J. Wortmann, M. Stapels, L. Chandra. J Appl.Polym.Sci., 113 (2009) 3336
Thermal analysis and synergistic tools for the development of a semi-permanent hair straightening technology
No full textThis research was carried out with the objective to develop a thermal analysis protocol into a method of damage assessment and claims support for a new semi-permanent hair straightening technology. The investigation determined the effects of the treatment on hair fibre composition and properties using Modulated Differential Scanning Calorimetry (MDSC) [1], Fourier Transform Infrared Spectroscopy (FTIR) [2], Gel Electrophoresis (SDS-PAGE) [3] and curl retention tests [4]. The effects of the new cysteamine treatment are compared with effects of a standard thioglycolate treatment and the daily use of straightening irons. Virgin, Caucasian hair was treated once with each chemical treatment and washed every day for 84 days. In a parallel study, hair was washed and straightened repeatedly using a standardised protocol at 190oC for 84 days. Samples were taken after 2, 28, 56 and 84 days for analysis by MDSC in water, ATR- and Trans-FTIR. Separate samples were treated once and subjected to curl retention tests and protein analysis. DSC measurements in water yield the keratin denaturation enthalpy (ΔHD), which relates to the thermal stability of the keratin intermediate filaments (KIFs), and the denaturation temperature (TD), which relates to the properties of the keratin associated-proteins (KAPs). The results show that chemical and thermal straightening cause a reduction in α-helix content and matrix viscosity. FTIR measurements give information on the formation of cysteic acid in the cuticle cells and the cortex. ATR-FTIR showed that the cysteamine–based treatment produces less cysteic acid in the cuticle layers than the standard treatment. Curl retention and SDS-PAGE were used to show the variability in the efficacy of the cysteamine treatment related to the heterogeneity of human hair. The results from both tests show that an individual’s hair will react with the product to a different extent, depending on the extractability of the keratin protein groups.In conclusion, we deduce that all straightening techniques, chemical and thermal, have a pronounced effect on the structural and chemical properties of hair fibres. These effects can be used to further develop and optimize this and related products. DSC has been shown to be an integral synergistic technique for the investigation of changes to hair morphology.This research was supported by the UK Technology Strategy Board under the Knowledge Transfer Partnership scheme.Cyril Keattch Award, Thermal Methods Group, Royal Society of Chemistry, 2014.[1] F.J. Wortmann, G. Wortmann, J. Marsh, K. Meinert. J. Struct. Biol., 177 (2012) 553. [2] V. Signori, D. Lewis. Int. J. Cosmet. Sci., 19 (1997) 1-13.[3] A.M. Zalfen, G. Wortmann, F.J. Wortmann. SOEFW Journal, 131 (2005) 40.[4] F.J. Wortmann, M. Stapels, L. Chandra. J Appl.Polym.Sci., 113 (2009) 3336
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Supplementary Materials S1
No full textSupplementary Materials for:
Anomalous 13C-enrichment in Mesozoic vertebrate enamel reflects environmental conditions in a ‘vanished world’ and not a unique dietary physiology
Cullen, T.M., Longstaffe, F.J., Wortmann, U.G., Huang, L., Evans, D.C.
Includes:
Supplementary Methods S1. Expanded details of analytical procedures
Supplementary Figure S1. Representative examples of specimens from RDS locality
Supplementary Figure S2. Additional tests for potential of diagenetic overprinting.
Supplementary Table S1. Measured stable carbon isotope compositions and specimen data
Supplementary Table S2. TEF source data used in δ13Cdiet calculations
Supplementary Table S3. Preservational, pretreatment, and FTIR data
Supplementary Table S4: Isotopic comparisons of dentine and enamel samples
Supplementary Table S5. Mean δ13Cdiet for studied taxa.</p
CHARACTERISTICS OF ANGORA RABBIT FIBRE 1 - THE INFLUENCE OF FIBRE ORIGIN ON FIBRE AND MEDULLA DIAMETER IN ANGORA WOOL
No full text[EN] The quality of Angora rabbit fibre is known to vary
between the countries in which it is produced. A study was made to
quantify various parameters of angora fibre quality, including fibre
and medulla diameter, and the proportion of medullated fibres, in
samples of angora wool obtained from Germany, France and China.
The mean fibre diameter of the French angora fleeces (19.8 μm) is
significantly higher than in German (12.8 μm) which is related to the
higher proportion of coarser hairs in the pelage of French Angora
rabbits. French Angora rabbits have a characteristic fleece structure.
The down fibres (mean fibre diameter: 14.1 μm) are coarser than in
German (12.4 μm) and Chinese (11.8 μm) wool and the degree of
medullation in awns and bristles is lower compared to the German and Chinese samples. The characteristics of the German and
Chinese Angora coats appear to be very similar. The highest
proportion of medullated fibres is observed in the French angora
wool (99.9 %). Values of 90.5 % and 96.8 % in the German and
Chinese samples are obtained, respectively. The samples of
Chinese angora fibre are found to have the highest medulla content
(down: 39.2 %; awn: 52.2 %; bristle: 71.9 %). The French angora, in
contras!, has a comparatively low medulla content (down: 36.7 %;
awn: 29.7 %; bristle: 36.6 %). The medulla content of awns and
bristles for German fibres are intermediate to the values obtained
from the other samples; the medulla content in the down fibres is
relatively low (down: 33.4 %; awn: 41.4 %; bristle: 52.5 %).[FR] La qualité du poi/ angora varíe se/on le pays oü elle est produite.
Cette étude tend a définir divers paramétres de qualité des fibres -
diamétre de la fibre et diametre médullaíre, quantité de fibres
médullées - dans des échantillons provenant d'Allemagne, de
France et de Chine. Le diamétre mayen du poi/ d'une toison
d'Angora fram;ais (19.8 μm) est significativement plus é/evé que
celuí d'une toison d'Angora allemand (12.8 μm) ceci résultant de la
part plus importante de poi/ grossier contenu dans la toison
fram¡aise. La structure de la toison d'Angora franc;ais est tres
part1culiére : le duvet ( diamétre mayen de la fibre : 14.1μm) est
plus grossier que chez l'allemand (12.4μm) ou Je chinois (11.8 μm) et le degré de médullation du duvet et des jarres est plus faible
comparé aux échantillons a/lemands ou chinois. Les
caractéristiques des fourrures allemandes et chinoises sont trés
similaires. La plus forte proportion de fibres médul/ées est observée
chez /'Angora franc;ais (99.9 %) ; les échantillons allemands et
chinois atteignent respectivement 90. 5% et 96. 8%. Le contenu
médullaire Je plus é/evé a été trouvé dans l'échantillon d'Angora
chinois (duvet: 39.2%, barbes: 52.2%, jarre: 71.9%). Au contraire,
/'Angora franc;ais a un contenu médullaire relativement faible (duvet:
36. 7%, barbe : 29. 7%, jarre : 36. 6%). Les va/eurs du contenu
médullaire des barbes et des jarres des toisons allemandes sont
intermédiaires (duvet 33.4%, valeur relativement faible ; barbe
41.4% ;jarre: 52.5%)Herrmann, S.; Wortmann, G.; Wortmann, F. (1996). CHARACTERISTICS OF ANGORA RABBIT FIBRE 1 - THE INFLUENCE OF FIBRE ORIGIN ON FIBRE AND MEDULLA DIAMETER IN ANGORA WOOL. World Rabbit Science. 04(3). https://doi.org/10.4995/wrs.1996.287SWORD04
Thermal Analysis of Human Hair, Modified by Disulphide Bond Breakage and Variable Alkylation
No full textThermal analysis of human hair, modified by disulphide bond breakage and variable alkylation Ian Jinks1, Gabriele Wortmann1, Prem Paul2, Franz J. Wortmann11School of Materials, University of Manchester, Manchester M13 9PL, UK.2Unilever Research and Development, Port Sunlight, Wirral, CH63 3JW, UK.Human hair, like other α-keratinous fibres, is a highly complex biomaterial. For the analysis of its mechanical and thermal properties it is, however, well described by a two-phase structure, which contains as morphological components the highly-ordered, crystalline intermediate filaments (IFs) and the less-ordered, amorphous matrix. Unique to α-keratin fibres are disulphide bonds, predominately found within the fibre matrix, which are known to play an important role in the stability and often are responsible for the unique mechanical properties exhibited by α-keratin fibres when compared to similar biomaterials. These bonds are, for instance, the chemical and structural basis for permanent waving and straightening treatments.Breaking of disulphide bonds through reduction and their modification through variable alkylation were carried out on untreated, brown, European human hair using a sequential ‘one-bath’ procedure established by Maclaren and Sweetman [1,2,3]. The subsequent alkylation of the reduced disulphide bonds is designed to prevent re-oxidation to reform the bonds, allowing fibre properties to be analysed. This modification was also intended to further investigate the premise put forward by Hall and Wolfram [4] that hair fibre stability could be restored after disulphide bond reduction through high molecular weight alkylation. This study attempts to determine the effects of disulphide bond reduction and alkylation with groups of different sizes and shapes on the thermal properties of human hair using differential scanning calorimetry (DSC) by, namely, investigating the humidity-dependent glass transition temperature Tg [5] as well as denaturation temperatures TD and enthalpies, ΔHD in water [6].Disulphide reduction and alkylation are shown to have a severe effect on the matrix, where both disulphide bond cleavage and plasticisation by the introduced alkyl chains contribute to the observed decrease in the humidity-dependent glass transition. The effect increases with the alkyl group chain length. Sizeable changes in the IF stability and integrity are shown by substantial reductions in denaturation enthalpies. However, it appears that at high water contents hydrophobic interactions between the alkyl chains are sufficient to kinetically impede the unfolding of the IFs to a similar extent as an untreated matrix. This is shown by a largely unchanged denaturation temperature after modification.[1] B. J. Sweetman and J. A. Maclaren, “Reduction of Wool Keratin by Tertiary Phosphines” Aust. J. Chem., 19 (1966) 2347–2354.[2] J. A. Maclaren, D. J. Kilpatrick, and A. Kirkpatrick, “Reduced Wool Fibres, their Preparation and Alkylation” Aust. J. Biol. Sci., 21 (1968) 805–813.[3] J. A. Maclaren and B. J. Sweetman, “Preparation of Reduced and S-Alkylated Wool Keratins Using Tri-N-Butylphosphine” Aust. J. Chem., 19 (1966) 2355–2360.[4] K. E. Hall and L. J. Wolfram, “Application of Theory of Hydrophobic Bonds to Hair Treatments” J. Soc. Cosmet. Chem., 28 (1977) 231–241. [5] F.J. Wortmann, M. Stapels, R. Elliot, and L. Chandra, “The Effect of Water on the Glass Transition of Human Hair” Biopolymers 81 (2006) 371-375.[6] F.J. Wortmann, C. Popescu, and G. Sendelbach, “Effects of Reduction on the Denaturation Kinetics of Human Hair” Biopolymers 89 (2008) 600-605
Thermal Analysis of Human Hair, Modified by Disulphide Bond Breakage and Variable Alkylation
No full textThermal analysis of human hair, modified by disulphide bond breakage and variable alkylation Ian Jinks1, Gabriele Wortmann1, Prem Paul2, Franz J. Wortmann11School of Materials, University of Manchester, Manchester M13 9PL, UK.2Unilever Research and Development, Port Sunlight, Wirral, CH63 3JW, UK.Human hair, like other α-keratinous fibres, is a highly complex biomaterial. For the analysis of its mechanical and thermal properties it is, however, well described by a two-phase structure, which contains as morphological components the highly-ordered, crystalline intermediate filaments (IFs) and the less-ordered, amorphous matrix. Unique to α-keratin fibres are disulphide bonds, predominately found within the fibre matrix, which are known to play an important role in the stability and often are responsible for the unique mechanical properties exhibited by α-keratin fibres when compared to similar biomaterials. These bonds are, for instance, the chemical and structural basis for permanent waving and straightening treatments.Breaking of disulphide bonds through reduction and their modification through variable alkylation were carried out on untreated, brown, European human hair using a sequential ‘one-bath’ procedure established by Maclaren and Sweetman [1,2,3]. The subsequent alkylation of the reduced disulphide bonds is designed to prevent re-oxidation to reform the bonds, allowing fibre properties to be analysed. This modification was also intended to further investigate the premise put forward by Hall and Wolfram [4] that hair fibre stability could be restored after disulphide bond reduction through high molecular weight alkylation. This study attempts to determine the effects of disulphide bond reduction and alkylation with groups of different sizes and shapes on the thermal properties of human hair using differential scanning calorimetry (DSC) by, namely, investigating the humidity-dependent glass transition temperature Tg [5] as well as denaturation temperatures TD and enthalpies, ΔHD in water [6].Disulphide reduction and alkylation are shown to have a severe effect on the matrix, where both disulphide bond cleavage and plasticisation by the introduced alkyl chains contribute to the observed decrease in the humidity-dependent glass transition. The effect increases with the alkyl group chain length. Sizeable changes in the IF stability and integrity are shown by substantial reductions in denaturation enthalpies. However, it appears that at high water contents hydrophobic interactions between the alkyl chains are sufficient to kinetically impede the unfolding of the IFs to a similar extent as an untreated matrix. This is shown by a largely unchanged denaturation temperature after modification.[1] B. J. Sweetman and J. A. Maclaren, “Reduction of Wool Keratin by Tertiary Phosphines” Aust. J. Chem., 19 (1966) 2347–2354.[2] J. A. Maclaren, D. J. Kilpatrick, and A. Kirkpatrick, “Reduced Wool Fibres, their Preparation and Alkylation” Aust. J. Biol. Sci., 21 (1968) 805–813.[3] J. A. Maclaren and B. J. Sweetman, “Preparation of Reduced and S-Alkylated Wool Keratins Using Tri-N-Butylphosphine” Aust. J. Chem., 19 (1966) 2355–2360.[4] K. E. Hall and L. J. Wolfram, “Application of Theory of Hydrophobic Bonds to Hair Treatments” J. Soc. Cosmet. Chem., 28 (1977) 231–241. [5] F.J. Wortmann, M. Stapels, R. Elliot, and L. Chandra, “The Effect of Water on the Glass Transition of Human Hair” Biopolymers 81 (2006) 371-375.[6] F.J. Wortmann, C. Popescu, and G. Sendelbach, “Effects of Reduction on the Denaturation Kinetics of Human Hair” Biopolymers 89 (2008) 600-605
Thermal Analysis of Human Hair, Modified by Disulphide Bond Breakage and Variable Alkylation
No full textThermal analysis of human hair, modified by disulphide bond breakage and variable alkylation Ian Jinks1, Gabriele Wortmann1, Prem Paul2, Franz J. Wortmann11School of Materials, University of Manchester, Manchester M13 9PL, UK.2Unilever Research and Development, Port Sunlight, Wirral, CH63 3JW, UK.Human hair, like other α-keratinous fibres, is a highly complex biomaterial. For the analysis of its mechanical and thermal properties it is, however, well described by a two-phase structure, which contains as morphological components the highly-ordered, crystalline intermediate filaments (IFs) and the less-ordered, amorphous matrix. Unique to α-keratin fibres are disulphide bonds, predominately found within the fibre matrix, which are known to play an important role in the stability and often are responsible for the unique mechanical properties exhibited by α-keratin fibres when compared to similar biomaterials. These bonds are, for instance, the chemical and structural basis for permanent waving and straightening treatments.Breaking of disulphide bonds through reduction and their modification through variable alkylation were carried out on untreated, brown, European human hair using a sequential ‘one-bath’ procedure established by Maclaren and Sweetman [1,2,3]. The subsequent alkylation of the reduced disulphide bonds is designed to prevent re-oxidation to reform the bonds, allowing fibre properties to be analysed. This modification was also intended to further investigate the premise put forward by Hall and Wolfram [4] that hair fibre stability could be restored after disulphide bond reduction through high molecular weight alkylation. This study attempts to determine the effects of disulphide bond reduction and alkylation with groups of different sizes and shapes on the thermal properties of human hair using differential scanning calorimetry (DSC) by, namely, investigating the humidity-dependent glass transition temperature Tg [5] as well as denaturation temperatures TD and enthalpies, ΔHD in water [6].Disulphide reduction and alkylation are shown to have a severe effect on the matrix, where both disulphide bond cleavage and plasticisation by the introduced alkyl chains contribute to the observed decrease in the humidity-dependent glass transition. The effect increases with the alkyl group chain length. Sizeable changes in the IF stability and integrity are shown by substantial reductions in denaturation enthalpies. However, it appears that at high water contents hydrophobic interactions between the alkyl chains are sufficient to kinetically impede the unfolding of the IFs to a similar extent as an untreated matrix. This is shown by a largely unchanged denaturation temperature after modification.[1] B. J. Sweetman and J. A. Maclaren, “Reduction of Wool Keratin by Tertiary Phosphines” Aust. J. Chem., 19 (1966) 2347–2354.[2] J. A. Maclaren, D. J. Kilpatrick, and A. Kirkpatrick, “Reduced Wool Fibres, their Preparation and Alkylation” Aust. J. Biol. Sci., 21 (1968) 805–813.[3] J. A. Maclaren and B. J. Sweetman, “Preparation of Reduced and S-Alkylated Wool Keratins Using Tri-N-Butylphosphine” Aust. J. Chem., 19 (1966) 2355–2360.[4] K. E. Hall and L. J. Wolfram, “Application of Theory of Hydrophobic Bonds to Hair Treatments” J. Soc. Cosmet. Chem., 28 (1977) 231–241. [5] F.J. Wortmann, M. Stapels, R. Elliot, and L. Chandra, “The Effect of Water on the Glass Transition of Human Hair” Biopolymers 81 (2006) 371-375.[6] F.J. Wortmann, C. Popescu, and G. Sendelbach, “Effects of Reduction on the Denaturation Kinetics of Human Hair” Biopolymers 89 (2008) 600-605
Roughness Induced Boundary Layer Transition in Incompressible Flow
No full textThe fluid dynamics process leading to laminar-turbulent transition behind an isolated roughness element is investigated in the incompressible regime using particle image velocimetry. The study covers the effect of roughness size and geometry on the promotion of transition. The measurement domain covers a large streamwise range from the near wake to the onset of the turbulent regime. Planar PIV measurements reveal the basic flow pattern and the turbulent structure of the flow characterizing by the velocity fluctuation statistics (RMS of the streamwise and wall-normal velocity component and Reynolds shear stress). The high Reynolds shear stress level reaching the region near the wall in the downstream area indicates the onset of turbulent boundary layer
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