Evaluation of the surface properties of hair with acoustic emission analysis.

OBJECTIVE: The tactile sensation of hair is an important consumer-perceivable attribute. There are limited instrumental options to measure the haptic properties of hair. In this study, we introduce a novel technique using the acoustic emissions produced when skin comes in contact with dry hair in a stroking motion. METHODS: Using a free-field microphone with a frequency response of 8-12,500 Hz, we recorded acoustic emission data of the interaction of skin with hair. Data were captured with Electroacoustics Toolbox software and analysed with Matlab. Acoustic emission profiles were generated allowing us to monitor the acoustic response at distinct frequencies. RESULTS: Various experiments were conducted to develop this novel technique as a suitable measure to monitor the surface properties of hair. Increasing the normal force and velocity of the interaction led to an increase in acoustic emissions. We also examined the acoustic profile of hair that underwent chemical treatment. For example, bleached hair produced a much higher magnitude acoustic response than the corresponding virgin hair. On the other hand, hair conditioner systems mitigated the acoustic response. Finally, investigations of textured hair revealed that the three-dimensional structure of the hair fibre assembly and its ability to return to its original state when perturbed produce the most dominant acoustic response for this type of hair. CONCLUSION: We introduce a cutting-edge method to reproducibly evaluate the surface properties of hair. Different types of hair geometry produce unique acoustic profiles as do hair types that experience harsh damaging treatments. This is also a very practical and efficient way to evaluate the degree of protection or conditioning of the fibre.

OBJECTIF: La sensation tactile des cheveux est un attribut important perceptible par le consommateur. Il existe des options instrumentales limitées pour mesurer les propriétés haptiques des cheveux. Dans cette étude, nous introduisons une nouvelle technique utilisant les émissions acoustiques produites lorsque la peau entre en contact avec les cheveux secs dans un mouvement de caresses. MÉTHODES: En utilisant un microphone champ libre avec une réponse en fréquence de 8 à 12 500 Hz, nous avons enregistré des données d'émission acoustique de l'interaction de la peau avec les cheveux. Les données ont été capturées avec le logiciel Electroacoustics Toolbox et analysées avec Matlab. Nous avons généré des profils d'émission acoustique. De cette manière nous pourrions surveiller la réponse acoustique à des fréquences distinctes. RÉSULTATS: Nous avons fait diverses expériences pour développer cette nouvelle technique comme mesure appropriée pour surveiller les propriétés de surface des cheveux. L'augmentation de la force normale et de la vitesse de l'interaction entre la peau et les cheveux ont causé une augmentation des émissions acoustiques. Nous avons également examiné le profil acoustique des cheveux ayant subi un traitement chimique. Par exemple, les cheveux décolorés ont produit une réponse acoustique de beaucoup plus grande amplitude que les cheveux vierges correspondants. D'autre part, les systèmes d'après shampooing ont atténué la réponse acoustique. Enfin, des investigations sur des cheveux texturés ont révélé que la structure tridimensionnelle de l'ensemble de fibres capillaires et sa capacité à revenir à son état d'origine lorsqu'il est perturbé produisent la réponse acoustique la plus dominante pour ce type de cheveux. CONCLUSION: Nous introduisons une méthode de pointe pour évaluer de manière reproductible les propriétés de surface des cheveux. Différents types de géométrie de cheveux produisent des profils acoustiques uniques, tout comme les types de cheveux qui subissent des traitements agressifs. C'est également une manière très pratique et efficace d'évaluer le degré de protection ou de conditionnement des cheveux.

Rheological fingerprinting as an effective tool to guide development of personal care formulations.

OBJECTIVE: Conventional rheological techniques in the linear viscoelastic region provide insights about the spatial configuration of the microstructural components of personal care formulations in their 'at-rest' state. However, they fail to describe the textural experience associated with large and fast deformations during daily consumer application. In this study we present a non-conventional rheological technique-large amplitude oscillatory shear (LAOS)-for probing the transformation of a material during its application. This technique is proposed a practical tool for formulators in their efforts to design products with desired textural attributes. METHODS: A non-linear rheological technique termed LAOS was utilized to capture the textural expression perceived by consumers. Lissajous plots (stress vs. strain or strain rate) provide a fingerprint of the formula and are utilized to both analyse the thickening mechanism and monitor the influence of various parameters, such as the chemistry, molecular properties, colloidal parameters and processing conditions. RESULTS: In this study, we showcased several approaches for modifying the texture of personal care formulations and show the influence of various parameters on the characteristics of the Lissajous curves and their relation to sensorial perception. This fingerprinting technique shows that increasing the molecular weight or hydrophobic modification boosts the elasticity and thickening efficiency of a given polymer. Differences in the chemistry of rheological ingredients also influence the characteristic Lissajous fingerprint. In high concentration surfactant systems, which tend to form worm-like micelles, their unique Lissajous fingerprints indicate structure rebuild because of fast kinetics at large but slow deformations. Analysis of lamellar gel-based hair conditioner formulations demonstrates the unique high yield stress of these types of materials, accompanied by the fast breakdown transition from a solid to viscous structure because of their crystalline lamellar gel structure. CONCLUSION: The LAOS technique presented in this article is intended to better capture the textural expression perceived by consumers. Lissajous plots-generated from the LAOS experimental data-provide a fingerprint of the tested formula and are utilized to both analyse the thickening mechanism and monitor the influence of various parameters, such as the chemistry and molecular weight of the thickener, pH of the formula medium and influence of other ingredients in the formula (surfactants, emulsifiers, etc.).

OBJECTIF: Les techniques rhéologiques conventionnelles dans la région viscoélastique linéaire fournissent des informations sur la configuration spatiale des composants microstructurels des formulations de produits cosmétiques dans leur état « au repos ¼. Mais elles ne décrivent pas l'expérience de texture associée à des déformations importantes et rapides lors de l'application quotidienne par les consommateurs. Dans cette étude, nous présentons une technique rhéologique non conventionnelle, le cisaillement oscillatoire à grande amplitude (Large Amplitude Oscillatory Shear, LAOS), pour examiner la transformation d'un matériau pendant son application. Cette technique est proposée comme outil pratique pour aider les formulateurs dans leurs efforts pour concevoir des produits qui ont les attributs texturaux désirés. MÉTHODES: Une technique rhéologique non linéaire appelée LAOS a été utilisée pour capturer le style textural perçu par les consommateurs. Les courbes de Lissajous (stress vs contrainte ou taux de déformation) fournissent une empreinte de la formule et sont utilisées pour analyser le comportement épaississant et surveiller l'influence de divers paramètres, tels que les propriétés moléculaires et chimiques, les paramètres colloïdaux et les conditions de traitement. RÉSULTATS: Dans cette étude, nous avons présenté plusieurs approches pour modifier la texture des formulations cosmétiques et montrer l'influence de divers paramètres sur les caractéristiques des courbes de Lissajous et leur relation avec la perception sensorielle. Cette technique d'empreintes montre que l'augmentation du poids moléculaire ou la modification hydrophobe stimule l'élasticité et l'épaississement d'un polymère donné. Les différences dans la chimie des ingrédients rhéologiques influencent également l'empreinte caractéristique de Lissajous. Dans les systèmes de tensioactifs à haute concentration, qui ont tendance à former des micelles semblables à des vers, leurs empreintes Lissajous uniques indiquent une reconstruction de la structure à cause de cinétiques rapides dans leur ensemble mais des déformations lentes. L'analyse des des formulations lamellaires d'après-shampooing à base de gel démontre le stress unique à haut rendement de ces types de matériaux, accompagnés par la transition de répartition rapide d'une structure solide à visqueuse à cause de leur structure lamellaire cristalline. CONCLUSION: La technique LAOS présentée dans cet article vise à mieux appréhender le style de texture perçu par les consommateurs. Les graphiques de Lissajous, générées à partir de données LAOS expérimentales, fournissent une empreinte de la formule testée et sont utilisés pour analyser le mécanisme épaississant et surveiller l'influence de divers paramètres, tels que la chimie et le poids moléculaire de l'épaississant, le Ph moyen et l'influence des autres ingrédients (tensioactifs, émulsifiants, etc.) dans la formule.

Investigation of corneal autoantibodies in horses with immune mediated keratitis (IMMK).

Immune mediated keratitis (IMMK) is primarily a non-ulcerative keratitis in horses causing intermittent ocular pain, eventually resulting in visual impairment. Affected horses typically respond to immunomodulatory treatment. However, the underlying cause of the disease remains enigmatic. The current study was undertaken to investigate the presence of autoantibodies in horses with immune mediated keratitis. Using 28 horses with IMMK and 27 healthy controls screening for serum autoantibodies against the corneal proteome using indirect immunofluorescence, one-dimensional (1DE) and two-dimensional electrophoresis (2DE) with subsequent western blot analysis was performed followed by mass spectrometric identification of bands or spots of interest. Indirect immunofluorescence did not reveal a difference in immune response towards corneal proteins between healthy horses and those with IMMK. Using western blot analysis some horses affected by IMMK (4/28) showed a single band (1D) or a single spot (2DE) (5/28) not detected in healthy controls. The corresponding spot was identified as maspin (SERPINB5), a protein responsible for the inhibition of corneal vascularisation, cell migration and cell adhesion to the extracellular matrix. Tests with a recombinant human protein commercially available did not verify blot findings, but the human protein may not be fully cross-reactive. Still, maspin might play a role in some cases of equine IMMK. Further research is needed to clarify the etiology of this disease.

Spectrofluorescence of skin and hair.

There are numerous chromophores present throughout the strata of human skin, which present many challenges and opportunities to probe molecular events. Fluorescence spectroscopy is principally employed to identify important biochemical components of the skin including endogenous tryptophan, tyrosine, pepsin-digestible collagen cross-links, collagenase-digestible collagen cross-links, NADH, etc. Over the last 15 years, many advances in instrument technology have been introduced allowing for much faster data acquisition with spectrofluorometers. As a result, a series of spectrofluorescence emission scans can be generated for a range of excitation wavelengths, or vice versa (excitation scans for a range of emission wavelengths), quickly to generate excitation-emission matrices. In this work, we constructed an endogenous fingerprint of fluorescent compounds present in skin, hair and nail tissues by employing a range of excitation wavelengths from 270 to 450 nm with a resolution of 2 nm. As a result, we generated surface plots of fluorescence emission as a function of excitation and emission wavelengths. From these data, we identified the predominant fluorescent chromophores in each tissue. We examined several sources of skin including in vivo human and ex vivo pig, sheep, goat and cow skin. We also analysed various types of mature hair characterized by the degree of melanin content. These analyses provided us with a fundamental understanding of the effects of melanin distribution in hair fibres and aided with the identification of fluorophores present in hair.

Current developments in equine cataract surgery.

The purpose of this review is to discuss the evolution of equine cataract surgery over the past 50 years to its current stage. Equine cataract surgery is performed similarly compared with the techniques used in human ophthalmology and in other veterinary species. However, enough differences exist to make surgical lens removal and intraocular lens implantation in the horse an intrinsically unique endeavour. Due to the size of the adult equine globe, the introduction of species-specific instrumentation has provided the cornerstone to many of the changes made regarding surgical technique over the last 15-20 years. The continuing development of an equine specific, foldable intraocular lens implant (IOL) has provided much needed data supporting the use of such lenses in the horse to improve upon the post operative visual outcome. Finally, the methods utilised to assess visual capacity and the effects of intraocular lens implantation on the globe (e.g. ocular ultrasonography, electroretinography and streak retinoscopy) are gradually becoming more important in preoperative patient assessment and IOL development in the horse. It is the hope of the authors that a broader group of equine veterinarians will become aware of the many changes that have taken place in equine cataract surgery over the last half-century. Although aspiration was implemented nearly 40 years ago in foals for the treatment of congenital cataracts, phacofragmentation (phacoemulsification) techniques have only recently become routine in mature horses undergoing lens extraction.

Image analysis to quantify histological and immunofluorescent staining of ex vivo skin and skin cell cultures.

Image processing steps and analysis techniques were developed for the quantification of photomicrographs obtained from light and fluorescence microscopy. The substrates examined were either skin cell cultures, such as normal human keratinocytes (NHK) or fibroblasts, or ex vivo skin sections. Examples of the analyses are provided for the comparison of skincare active ingredient treated samples vs. placebo to demonstrate the utility of the methods to quantify and provide numerical data for a procedure that is typically qualitative in nature and based on observations by a histologist. Quantifiable experiments that are discussed include: Fontana Masson staining for melanin expression; Nile red staining to detect cellular lipid droplets; nuclei staining with diamidino-phenylindole (DAPI); and immunofluorescent staining of protein expression with a primary antibody directed against the protein (antigen) and a secondary antibody tagged with a fluorescent dye (Alexa Fluor 488) against the primary antibody.

Indentometric analysis of in vivo skin and comparison with artificial skin models.

BACKGROUND/PURPOSE: The mechanical properties of the skin have been previously analyzed by a number of different techniques including torsional analysis, cutometery, gas-bearing electrodynamometry, etc. The objective of this work is to present quantitative analysis of skin rheology by a technique termed indentometry. METHODS: The instrument used was a texture analyzer, which is a mechanical tensiometer simulating the process of touch. The experiments were carried out on human subjects as well as on artificial skin models. They included indentometry tests performed by using spherical probes with various geometrical dimensions as well as stress relaxation and creep experiments. The experimental data were interpreted by using the Hertz theory of contact mechanics and by calculation of fundamental parameters such as the modulus of elasticity. RESULTS: The calculated Young's modulae for skin models ranged from 5.5 x 10(4) to 17.7 x 10(4) N/m(2), while the corresponding values for forearm and facial skin of ten panelists were found to be in the range of 0.7 x 10(4) -3.3 x 10(4) N/m(2). In addition, stress relaxation and creep experiments were conducted, which permitted the assessment of the viscoelastic properties of skin. The results of these measurements were interpreted within the framework of the Kelvin-Voigt model of delayed elasticity leading to the calculation of viscosities and relaxation times. Indentomeric data, obtained by varying the diameter of the indentor and the indentation depth, are also discussed. CONCLUSION: The indentometric analysis for both in vivo skin and artificial skin models could be interpreted by using the Hertz theory of contact mechanics. The loading and unloading indentometric curves could be used to assess the viscoelasticity of the investigated materials while creep and stress relaxation processes were analyzed quantitatively by the Kelvin-Voigt model with one relaxation time.

Optical properties of hair--detailed examination of specular reflection patterns in various hair types.

Details of the specular reflection of curved hair tresses, resulting from illumination with a collimated incident light source, were examined both qualitatively and quantitatively using high-resolution photography and image analysis. The reflections were found to consist of a multitude of light dots aligned with the fibers and typically separated by a distance of 81-145 microm. The contrast between the dots (specular reflection) and the darker regions (diffuse reflection) of the entire reflection band was found to increase with increasing pigmentation of hair. Highly pigmented Oriental hair provided more contrast within the specular reflection band than unpigmented natural white hair. A quantitative description of the light reflection patterns within the specular reflection band included two-dimensional distribution of luminosity, histograms of the frequency of appearance for peak maxima and minima in luminosity distribution plots, and histograms of absolute maxima and minima of luminosity along the length of the fibers. Specular reflection from African hair, which consists of many curls that provide multiple and randomly distributed reflection centers, have also been investigated. Using microscopy software, Image Tool 2.0, and a method termed image threshold, the number of reflection sites and their shapes could be quantified. For example, treatment of African hair with synthetic sebum was shown to significantly affect the reflection patterns, resulting in a decrease in the overall hair luster. Comparison of reflection patterns from Caucasian frizzy, very curly, and curly hair is also discussed.

Hydroxyapatite accelerates differentiation and suppresses growth of MC3T3-E1 osteoblasts.

Hydroxyapatite describes both the natural mineral phase of bone as well as the widely used calcium-phosphate implant substitute. Given that hydroxyapatite is a major component of the in vivo surface with which osteoblasts interact, it is surprising that most studies examining the regulation of osteoblast growth and differentiation utilize plastic surfaces. Here we demonstrate that the phenotype of mouse MC3T3-E1 osteoblasts is significantly altered on hydroxyapatite compared with plastic surfaces. Specifically, alkaline phosphatase activity and messenger RNA levels, markers of early stages of osteoblast differentiation, are increased in osteoblasts cultured on hydroxyapatite. The precocious appearance of alkaline phosphatase activity on the hydroxyapatite surface suggests that osteoblast differentiation is activated earlier compared with plastic surfaces. Osteocalcin expression, a marker of late-stage differentiation, is also increased on hydroxyapatite and further demonstrates enhanced differentiation. Cell counts indicate that fewer osteoblasts are present on hydroxyapatite versus plastic surfaces 24 h after plating. Measurement of osteoblast attachment, apoptosis, and necrosis indicated no differences between surfaces. In contrast, the number of bromodeoxyuridine-incorporating cells was significantly decreased on hydroxyapatite compared with plastic surfaces. Taken together, our findings indicate that hydroxyapatite enhances osteoblast differentiation while also suppressing growth.

Optical properties of hair: effect of treatments on luster as quantified by image analysis.

Image analysis has been employed to measure the luster of hair simulated by light reflected from a curved hair tress. Hair samples (up to four) were mounted side-by-side in a special sample holder in the form of a cylinder and illuminated by a uniform beam of white light. Digital images of hair tresses were captured with a high-resolution camera and were analyzed by scanning across highlighted and dark areas of the resultant image using image analysis software with developed macros. Plots, similar to goniophotometric scattering curves, were used to calculate luster values according to previously published work by Nickerson, Stamm, and Reich-Robbins. Both the Stamm and Reich-Robbins approaches were found to give similar results, while the Nickerson gloss parameter exhibited less sensitivity to hair modification with cosmetic ingredients. The procedure was employed to assess the luster of natural white, light blonde, light brown, medium brown, and dark brown hair, and revealed an increase in luster indices in proportion to an increase in fiber pigmentation. Cosmetic oils such as phenyl trimethicone, amodimethicone, and castor oil were also found to increase the luster of hair as a result of the change in contrast between specular and diffuse reflection. Styling resins such as butyl ester of PVM/MA copolymer, vinyl caprolactam/PVP/dimethylaminoethyl methacrylate copolymer, and isobutylene/ethylmaleimide/hydroxyethylmaleimide copolymer were shown to increase hair gloss by a similar mechanism, as evidenced by calculated higher values of the Stamm and Reich-Robbins luster parameters. An effect of hair dulling by deposition of micronized ZnO at various concentrations, as well as by synthetic sebum, is also discussed.

Mechanical analysis of elasticity and flexibility of virgin and polymer-treated hair fiber assemblies.

The elasticity and flexibility of virgin and polymer-treated hair fiber assemblies were investigated by employing straight hair tresses or hair shaped into omega loops. Polymer treatment was accomplished by saturating fibers with polymeric solutions, resulting in a deposition of 10-90 mg of polymer per gram of hair. The mechanical testing procedure consisted of subjecting omega-loop-shaped hair or straight hair tresses to multiple bending deformations at 25% strain in a texture analyzer. A total of ten deformations were typically carried out, and elasticity or flexibility parameters were evaluated from data such as (a). the force at 8% deformation, i.e., within the elastic region of bending deformation for hair shaped into an omega loop, (b). maximum force in the first (F(1)) and tenth (F(10)) deformation cycles, (c). elastic modulus in the first (E(1)) and tenth (E(10)) deformation cycles, and (d). the change in hair sample dimensions between the first (H(1)) and tenth (H(10)) deformation cycles. Parameters such as stiffness ratio (1), F(10)/F(1), E(10)/E(1), and H(10)/H(1) were employed to characterize hair tress rigidity, flexibility or resistance to breakage, and plasticity. Untreated hair was found to be almost perfectly elastic and flexible at 50% RH, evident by the linear dependence of force vs deformation. Flexibility parameters F(10)/F(1), E(10)/E(1), and H(10)/H(1) were in the range of 0.95 to 1.0 at low humidity, while the parameters F(10)/F(1) and E(10)/E(1) and were 10% lower at 90% RH. Examination of polymer-modified hair allowed for classification of treatments into categories termed brittle, quite flexible and nonplastic, flexible and plastic, very flexible and very plastic, and very flexible and nonplastic. Poly(vinyl pyrrolidone) is shown as an example of a quite flexible and nonplastic material, with its flexibility and stiffness dependent upon its molecular weight. The effect of plasticizers on polymer behavior is also discussed.

Investigation of human hair fibers using lateral force microscopy.

Atomic force microscopy (AFM) and lateral force microscopy (LFM) were used to investigate the morphologic and surface changes associated with various surface modifications to human hair. These included extraction with a series of solvents, bleaching, and treatment with a cationic copolymer. The study assessed the ability of these techniques to distinguish the changes in surface properties, including morphology and friction coefficient, as manifested in changes brought about by the indicated surface modifications. While topographic morphology can easily be investigated with contact AFM. LFM offers an additional tool for probing the surface distribution of oils and waxes. The removal of surface lipids from the fiber surface was accomplished using soxhlet extraction with t-butanol and n-hexane, while the free internal lipids (within the fiber structure) were removed by extraction with a mixture of chloroform and methanol (70:30, v/v). In addition, the surface of hair was modified with the cationic polymer, co(vinyl pyrrolidone-methacrylamidopropyl trimethylammonium chloride [PVP/MAPTAC]), and its distribution on the surface was monitored. Ambient AFM and LFM studies of surface modified and native fibers clearly indicate that when investigated as a function of tip loading force, the different modifications result in changes of the friction coefficient, which increase in this order: native, bleached, solvent extracted, and polymer-treated hair. Friction images show surface variations that are interpreted as areas of varying lipid film coverage. In addition, topographic images of the fibers show the presence of small pores, which become increasingly prevalent upon solvent extraction.

Travel medicine problems encountered in emergency departments.

This article reviews some common illnesses and conditions that prompt traveling patients to seek medical care in the emergency department in the United States. It also presents an emergency department approach to the initial diagnosis and treatment of travelers who are experiencing adverse side effects from pretravel immunizations and returned travelers who fear unusual, serious or exotic conditions and want immediate medical attention.

General advice for the international traveler.

Medical concerns of the traveling patient may be organized into pre-travel medical advice and preparation, maintenance of health and behavioral modification during travel, and post-travel diagnosis and treatment for travelers returning with illness or a significant change in their general health. Pre-travel medical advice and preparation may be done in large part by well-informed primary-care providers, although patients with special health conditions or unusually complicated or high-risk itineraries may be best referred to a travel medicine specialist. Although diagnosis and treatment of exotic and tropical diseases usually falls within the area of expertise of the infectious diseases specialist, primary physicians should be familiar with the geographic distribution and presentation of the more common of these diseases, so that appropriate referrals will be made.

Reduced progesterone and altered cotyledonary prostaglandin values induced by locoweed (Astragalus lentiginosus) in sheep.

Feeding 300 or 400 g of dried spotted locoweed, Astragalus lentiginosus per day to 11 pregnant Columbia ewes from the 20th to the 50th days of their gestations resulted in dead and edematous fetuses. Aspartate aminotransferase values were increased, whereas serum progesterone values were significantly diminished (P less than 0.05) in a dose-dependent manner by locoweed ingestion. Cotyledonary 6-keto-prostaglandin (PG)F1 alpha (400 g/day only) and PGF2 alpha (300 and 400 g/day) values were significantly increased (P less than 0.05), whereas PGE values were not affected by the treatment. Alterations in PG values in these sheep may be a mechanism for altering corpus luteum function and inducing fetal death, which would ultimately result in abortion.