The thickness of 18-MEA on an ultra-high-sulfur protein surface by molecular modeling.

The use of computational chemistry techniques via molecular modeling software provides additional support to the hair surface model by Negri et al. (1) and refines the thickness of the 18-methyl eicosanoic acid (18-MEA) lipid layer attached by thioester linkages to an ultra-high-sulfur protein (UHSP) at 1.08 ± 0.

The cell membrane complex: three related but different cellular cohesion components of mammalian hair fibers.

The structure, chemistry and physical properties of the cell membrane complex (CMC) of keratin fibers are reviewed, highlighting differences in the three types of CMC. Starting with Rogers' initial description of the CMC in animal hairs, several important developments have occurred that will be described, adding new details to this important structure in mammalian hair fibers. These developments show that essentially all of the covalently bound fatty acids of the beta layers are in the cuticle and exist as monolayers.

Hair breakage during combing. IV. Brushing and combing hair.

During combing of hair, longer fiber breaks (>2.5 cm) occur principally by impact loading of looped crossover hairs, while short segment breaks (<2.5 cm) occur primarily by end wrapping.

Hair breakage during combing. III. The effects of bleaching and conditioning on short and long segment breakage by wet and dry combing of tresses.

A recent publication (1), provided evidence for two types of hair breakage during combing, short segment breakage (approximately less than 1.27 cm) and longer segment breakage. We have confirmed these results and refined the separation distance between short and long segment breakage at about 2.

Hair breakage during combing. II. Impact loading and hair breakage.

During combing of hair, short fiber fragmentation (less than 2.5 cm) and longer segment breaks occur by different pathways. Longer fiber breaks most likely occur principally by impact loading.

Hair breakage during combing. I. Pathways of breakage.

Hair breakage during combing was evaluated by combing tresses and examining photographs of snags of hair fibers in combs. The resultant hair fiber arrangements suggest that breakage likely involves hair-on-hair interactions, and broken fragment size suggests that breakage occurs primarily at or near the hair-comb interface. Compression forces during combing were also measured, and impact loading of a hair fiber over another hair versus a hair fiber over a comb tooth shows that compression and abrasion are important to breakage during combing and that impact loading of one hair fiber over another during snagging is a probable and important pathway for hair breakage.

Failure of intercellular adhesion in hair fibers with regard to hair condition and strain conditions.

Although adhesion failure in hair fibers can occur inside cells, it occurs more frequently in the cell membrane complex (CMC), often involving the rupture of interlayer bonds. Therefore, a model of the CMC is presented, based on prior research in which we propose interconnecting bonds between the layers to assist in our interpretation of hair-fracturing mechanisms for cuticle chipping, deep transverse cuticle cracks, cracks during heat drying, scale lifting by surfactants, and catastrophic failure. Failure in the wet state generally involves hydrophilic layers, e.

Scalp hair length. II. Estimating the percentages of adults in the USA and larger populations by hair length.

Scalp hair length assessments by anatomical site, previously made in Florida theme parks on adults, are related to anatomical measurements to obtain estimates of free-hanging hair lengths in centimeters. A plot of the natural logarithm of the percent population versus these hair lengths provides a straight line and an equation that permits the estimation of the numbers of persons in the USA and larger populations with hair lengths up to 183 cm (just beyond ankle-length). Data were also collected via a literature search for even longer hair lengths (ankle-length or longer) to provide an equation to estimate the numbers of persons with exceptionally long hair.

Scalp hair length. I. Hair length in Florida theme parks: an approximation of hair length in the United States of America.

Ten hair length studies were conducted (January through May of 2001) at theme parks in central Florida, by observing and counting people with different lengths of hair with reference to specific anatomical sites. We observed 13.20% of the 24,300 males and females with hair shoulder-length or longer and 2.