Search

The ensuing pilot investigation sheds new light on characterizing tumoral and non-tumoral human skin mechanical properties that will not only assist the dermatologist’s diagnosis but also could constitute the creation of an Artificial Intelligence database for upcoming research. A modern, non-invasive, and contact-free methodology—UNDERSKIN—was developed, and hinges upon Fourier transform computations that permit the analysis of surface wave dispersion with a specific skin inversion model and viscoelastic model. It yields a detailed look at how particle movements of the medium propagate throughout its near sub-surface, hence a novel knowledge of the mechanical responses of skin tumors. The research results display the tumors’ viscoelastic responses alongside their respective healthy skin outcomes for each skin layer as well as the dermatologist’s touch analysis. Although dermatologists are capable of sensing and having a fair overall assessment of what they are palpating, they are unable heretofore to quantify it and inform where the firmness or softness derives from, which it is necessary to be acquainted with so as to perform an accurate diagnosis, prognosis, treatment, future surgery, and teledermatology.

Although the human finger is the interface used for the touch process, very few studies have used its properties to provide a description of tactile perception regarding age and gender effects. Age and gender effects on the biophysical properties of the human finger were the main topics of our previous study. Correlating tactile perception with each parameter proved very complex. We expand on that work to assess the static and dynamic touch in addition to the touch gestures. We also investigate the age and gender effects on tactile perception by studying the finger size and the real contact area (static and dynamic) of forty human fingers of different ages and gender. The size of the finger and the real contact area (static and dynamic) define the density of the mechanoreceptors. This density is an image of the number of mechanoreceptors solicited and therefore of tactile perception (static and dynamic). In addition, the touch gestures used to perceive an object's properties differ among people. Therefore, we seek to comprehend the tactile perception of different touch gestures due to the anisotropy of mechanical properties, and we study two different directions (top to bottom and left to right).

The human finger plays an extremely important role in tactile perception, but little is known about the role of its biophysical properties (mechanical properties, contact properties and surface topography) in tactile perception. In addition, the touch gestures used to perceive an object’s properties differ among people. We combined studies on the biophysical properties and the vibrations measured from the human finger to understand the age and gender effects on the tactile perception and the difference between the touch gestures. In addition, a new algorithm, Mel-frequency cepstral coefficients (MFCCs), was used to analyze the vibratory signal obtained from the physical contact of the finger, and a surface is proposed and validated. The values obtained regarding the correlation between the tribohaptic system results and the biophysical properties show that the Young’s modulus and the surface topography are the most important. An inverse correlation was observed between the MFCC and the tactile perception. This last observation explained the results of better tactile perception with left to right touch gestures. It also demonstrated a better tactile perception for women.

The effect of contaminants has been overlooked and yet plays a significant role in driver safety and road maintenance. A laboratory test method is developed to reproduce the deposit of contaminant particles on the road surface and measure the friction coefficient on dry and wet-contaminated surfaces. It simulates in this way the variation of skid resistance of the road surface due to contaminants during a dry period–precipitation event and the washoff effect of the rain. Protocols are described with respect to the contaminant collection on site and the subsequent preparation in the laboratory, the spreading of contaminant particles on the road specimen and their compaction to simulate the effect of the traffic, the wetting of the test surface to simulate precipitations, and the friction measurement. Values of friction coefficient on clean and dirty dry surfaces as well as during the surface wetting (simulation of precipitations) are plotted. Comparison with the literature shows that the developed test method reproduces remarkably well qualitative graphs used to highlight the loss of skid resistance with time during a rain preceded by a long dry period. The effect of contaminant concentrations and traffic is shown. Explanations are given in terms of the masking of the road surface microtexture; they are supported by visual observation of the road surface before and after the contaminant deposit.

Nowadays, archaeology is a multidisciplinary science, aware of the possibilities which advanced technologies can bring about. Thus tribology, the science of wear and friction, has been for some time one of the analysing techniques leading to a better knowledge of our past. It studies the mechanisms of wear, abrasion and friction which took place during the manufacturing or the use of an object. Recently, two hoards of bronze objects, dating from the middle phase of the Final Bronze Age (1100–900 BC), were discovered on the site of les Feuilly in Saint-Priest (Rhone, France). These bronzes which reached us are the last markers of the techniques of former craftsmen: their surfaces reveal many traces, which are the memory of their manufacturing skills and their ‘social life’. The archaeological and tribological study was conceived to raise questions about gestures and processes used particularly for the decoration of bronze objects, in order to have a better knowledge of the crafstman’s know-how. We ...

La dermocosmetologia riveste un ruolo leader da 30 anni nello sviluppo di nuove tecnologie di esplorazione e di valutazione della superficie cutanea. Tutte le tecniche di imaging, come risonanza magnetica, tomografia a fibre ottiche coerenti, ecografia ad alta risoluzione, microscopia confocale, risonanza Raman ecc., sono utilizzate oggi negli studi farmacoclinici di oggettivazione dell’efficacia dei prodotti. L’ambito della dermatologia e sempre piu interessato a queste tecniche, che migliorano la presa in carico dei pazienti e il loro follow-up grazie a una migliore osservazione dei fenomeni cutanei. Il rilievo cutaneo e sicuramente il campo piu studiato della dermocosmetica. E, in effetti, estremamente sensibile alle aggressioni e un riflesso dell’invecchiamento. All’origine, i parametri di caratterizzazione del rilievo cutaneo provenivano dall’industria della lamiera e dallo studio delle rigature. I lavori condotti da diversi decenni hanno portato a molti metodi di acquisizione, nonche a molti metodi di caratterizzazione piu adatti a questa materia vivente che e la pelle. In questo articolo presentiamo velocemente un insieme di tecniche che permettono di acquisire l’informazione 3D in vivo o su replica. I principali tipi di rilievo illustrati di seguito. I metodi di caratterizzazione di questo rilievo sono presentati in particolare insieme all’analisi dell’anisotropia, parametro realmente intrinseco al rilievo cutaneo rispetto ai parametri di rugosita. Infine, per dimostrarne l’interesse, noi ci basiamo su alcuni esempi di applicazioni di queste tecniche negli studi clinici di oggettivazione dell’effetto della radioterapia sul rilievo, di un laser di rimodellamento, di prodotti antirughe.

In this work we have studied the effect of adhesion forces on the mechanical parameters between a spherical indenter and human skin surface with an indentation test. To take into account the effect of adhesion on Hertzian contact radius, pressure and strain, a theory of adhesion contact, like that of Johnson, Kendall and Roberts (JKR) or Derjaguin, Muller and Toporov (DMT) must be used. These theories correct the errors induced by the adhesion forces on contact parameters. The change in skin surface lipid film during hydration by water is assessed by analyzing the evolution of the adhesion energy and skin stiffness.

This study shows that if we are to carry out a plastic deformation of a surface, which is of interest in problems of shaping and molding for example, then a higher roughness value is desirable; this explains why, at the time of lamination and molding, efforts are made to increase the roughness of sheet metal which is to be pressed. On the other hand, if we want to limit the elastic deformations of a surface, which is necessary in the field of power transmission for example, then the surface roughness value should be very low, in other words, the surface should be as smooth as possible.

Lysyl oxidase-like (LOXL) is an extracellular enzyme that catalyses the cross-linking between microfibrils and tropoelastin (TE), thereby ensuring elastic fibre functionality. With ageing, LOXL expression decreases, thus participating in the loss of skin elasticity. In a previous study, we showed that a dill seed extract [INCI name: Peucedanum graveolens (Dill) extract] could increase LOXL expression in cultured dermal fibroblasts. Besides, we showed a good correlation between the measurements of skin elasticity obtained in vitro and in vivo using a fully automated bio-tribometer designed to measure the biomechanical properties of soft and complex materials like skin. The aim of this study was to evaluate the ability of the dill extract to improve skin elasticity in vitro and in vivo using different models. Using the bio-tribometer, we first showed that the lateral elasticity of dermis equivalents (DEs) treated with the dill extract at 1% was significantly increased by +29% (P0.01) when compared to untreated DEs. In vivo, skin firmness and elastic recovery measured using cutometry methods were also significantly improved compared to placebo in volunteers treated for 56 days with a formula containing 1% of dill extract. Moreover, the clinical evaluation evidenced significant improvements in 'skin elasticity' compared to placebo. A majority of subjects treated with the dill extract also noted significant improvements in skin elasticity, firmness and slackness of the jaw line. Finally, mean wrinkle area and length were also significantly reduced compared to placebo after 84 days as measured using silicone replicas taken from the crow's feet. In summary, this study showed that the dill extract could improve elasticity of DEs in vitro as well as skin biomechanical properties and appearance in vivo. It also highlights the relevance of using the bio-tribometer as an exploratory tool for the measurement of skin elasticity in vitro.

Until now, the wettability of the skin has been only estimated through the measurement of its critical surface tension (Zisman), or surface free energy. These methods give information on the behaviour of the surface with water, but cannot quantify its behaviour with other polar liquids. In this paper we propose to express both the hydrophilia of the skin (Hi) by the ratio of its critical surface tension (gamma(c)) to the water surface tension (gamma(H(2)O)), and its hydrophobia (Ho) by the ratio of the difference between the critical surface tension (gamma(c)), and the value of the water surface tension (gamma(H(2)O)) normalized by the latter. By using this proposed parameter, it should be possible to classify skin surfaces according to their affinities to water, which is of major importance in Cosmetology as well as in biology. We also discuss the relationship between surface hydrophilia (Hi) and polarity (P) as defined by Wu, and water adhesion tension (tau(o)) as described by Vogler. The gamma(c) of untreated skin was 27.3 +/- 3.6 mJ m(-2), confirming previous data, and consequently basal Hi was 38%. Either cleaning with ether or hydration by occlusion induced a diminution of the wetting capacity of the surface and consequently a decrease of Hi to 29% and 33%, respectively. In contrast, washing the skin surface with soap and water increased surface Hi to 43%.

We report the case of a 51-year-old woman who presented with a progressive elevation of the border of an old varicella scar. The lesion which was clinically diagnosed as a basal cell carcinoma turned out to be a typical desmoplastic trichoepithelioma. The development of desmoplastic trichoepithelioma in an area of scarring has not been previously reported. The nosology of this tumor is discussed with particular emphasis on its possible relationship to morphoeic basal cell carcinoma, thus questioning it as a true tumor sui generis.

We report the case of a 51-year-old woman who presented with a progressive elevation of the border of an old varicella scar. The lesion which was clinically diagnosed as a basal cell carcinoma turned out to be a typical desmoplastic trichoepithelioma. The development of desmoplastic trichoepithelioma in an area of scarring has not been previously reported. The nosology of this tumor is discussed with particular emphasis on its possible relationship to morphoeic basal cell carcinoma, thus questioning it as a true tumor sui generis.