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Abstract 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.

Abstract 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 how age and gender affect its biophysical properties and their role in tactile perception. We combined studies on contact characteristics, mechanical properties and surface topography to understand age and gender effects on the human finger. The values obtained regarding contact characteristics (i.e. adhesive force) were significantly higher for women than for men. As for mechanical properties (i.e. Young's modulus E), a significant and positive correlation with age was observed and found to be higher for women. A positive correlation was observed between age and the arithmetic mean of surface roughness for men. However, an inverse age effect was highlighted for women. The age and gender effects obtained have never been reported previously in the literature. These results open new perspectives for understanding the weakening of tactile perception across ages and how it differs between men and women.

Abstract  This study intended to investigate the effect of tribological parameters on wear mechanisms and friction coefficient for homogeneous and heterogeneous materials. Particularly, effects of particle geometry and normal load on the tribological behaviour of an aluminium alloy and nodular cast iron have been developed. These materials are used in two industrial applications. The first one is used to transport granular material. It has been shown that damage of used truck’s buckets is produced. However, the nodular cast iron is used in automobile industry thanks to its lower density, good wear resistance and its low friction coefficient. A scratch test was used and the wear mechanisms were observed for different attack angles. The normal load was also varied and correlation between wear mechanisms, tribological parameters and friction coefficient was highlighted. [ABSTRACT FROM AUTHOR]

Natural skin tension plays an important role during surgical procedures and during the healing process. Existing studies performed ex vivo give only a qualitative map of skin tension. In this study, we propose a quantitative characterization of skin tension in vivo using a new model. This model consists in calculating the tension indices based on the equilibrium equation, and uses the Fourier transform. The study was carried out on 42 volunteers. Tension indices are calculated primarily from skin topology images performed on seven body areas: forearm, thigh, cheek, belly, upper chest, and arm (front and back face). A feasibility study of applying the model to LC-OCT and confocal microscopy images was then carried out. The results show that the skin tension is higher in the family of tension lines, and lower in the family of lines perpendicular to the tension lines. The tension indices quantify the state of the skin tension forces and allow to classify body areas according to their state of tension. With age, the skin loses its tension, leading to an imbalance of tension forces between the two families of lines. The results also show that the model can be used on deep skin images to study fiber tension., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

In the context of the oral cavity, an organic layer known as the mucosal pellicle (MP) adheres to the surface of the oral epithelium, playing a pivotal role in lubricating and safeguarding oral tissues. The formation of the MP is driven by interactions between a transmembrane mucin known as MUC1, located on the oral epithelium, and salivary secreted mucin, namely MUC5B and MUC7. This study aimed to investigate the function of MUC1 and the influence of its structure on MP lubrication properties. We proposed a novel methodology to study oral lubrication based on four different models of oral epithelium on which we conducted in vitro tribological studies. These models expressed varying forms of MUC1, each possessing on of the distinct domain constituting the mucin. Mechanical parameters were used as indicators of lubrication efficiency and, consequently, of the role played by MUC1 in oral lubrication. The results from the tribological tests revealed that the presence of full MUC1 resulted in enhanced lubrication. Furthermore, the structure of MUC1 protein drive the lubrication. In conclusion, the mechanical tests conducted on our epithelium models demonstrated that MUC1 actively participates in epithelium lubrication by facilitating the formation of the MP., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Exposure to mechanical stimuli such as pressure and stretching prompts the skin to undergo physiological adaptations to accommodate and distribute applied forces, a process known as mechanotransduction. Mechanotherapy, which leverages mechanotransduction, shows significant promise across various medical disciplines. Traditional methods, such as massage and compression therapy, effectively promote skin healing by utilizing this mechanism, although they require direct skin contact. This study introduces a novel contactless modality, Shear Wave Stimulation (SWS), and evaluates its efficacy compared to traditional massage in eliciting responses from human skin and fascia. Fifteen healthy volunteers received SWS, while another fifteen volunteers received massage. Tests of skin mechanical properties revealed significant enhancements in skin shear modulus for both methods, showing an increase of approximately 20%. Additionally, deformation analysis of ultrasound images showed distinct responses of the skin and fascia to the two stimuli. SWS induced extension in the dermis (∼18%), hypodermis (∼16%), and fascia (∼22%) along the X and Y axes. In contrast, massage compressed the skin layers, reducing the dermis by around 15% and the hypodermis by about 8%, while simultaneously stretching the superficial fascia by approximately 8%. The observed extension across the entire skin with SWS highlights its potential as a groundbreaking contactless approach for promoting skin healing. Furthermore, the differing responses in blood flow reaffirm the distinct stimulation modes of SWS and massage. These findings establish a foundation for future innovative skin therapy modalities.

Significance: Multilesional basal cell carcinoma (BCC) are spread on sun exposed skin areas, including arms, face and back. The first-line treatment remains the surgical resection or Mohs surgery. Despite its high complexity, Mohs surgery is well practiced in USA and Germany and presents very good results both in esthetic and in carcinology point of view. Large lesions more than 2 cm remain challenging to remove by topical cream used in photodynamic therapy (PDT). If these larger lesions are not treated in less than 1 month, they could grow deeply in the skin, thus enhancing the risk of reoccurrence and the severity of the disease. Despite this model herein studied, that is non melanoma skin cancer is a good prognostic cancer, the therapy aims to be applied to more aggressive melanoma skin cancers., Aim: Total regression of large cutaneous lesions less than 1 month with no reoccurrence., Approach: Tumor induction on murine model bearing a 500 mm 3 subcutaneous lesion. Increasing dose of gold nanoparticles at fixed initial concentration C0 = 0.3 mg/mL, infused into the tumor then exposition of the region of interest to NIR medical laser to assess the therapy. One or two intratumoral administration(s) were compared to surgery and control, that is no treatment, laser alone or nanoparticles alone., Results: Gold nanoparticles alone or the NIR laser alone did not induce the tumor regression. The combination of laser and nanoparticles called plasmonic nanophotothermal therapy induced apoptosis. Derma and hypoderm do not show any visible gold nanoparticles and demonstrated a good cicatrization process., Conclusion: Plasmonic nanophotothermal therapy using two doses of gold nanoparticles was the only protocol that proved its efficacy on large lesions in 14 days, that is 500 mm 3 on a murine model bearing human basal cell carcinoma., (© 2024 The Author(s). Skin Research and Technology published by John Wiley & Sons Ltd.)

The skin, the outermost organ of the human body, is vital for sensing and responding to stimuli through mechanotransduction. It is constantly exposed to mechanical stress. Consequently, various mechanical therapies, including compression, massage, and microneedling, have become routine practices for skin healing and regeneration. However, these traditional methods require direct skin contact, restricting their applicability. To address this constraint, we developed shear wave stimulation (SWS), a contactless mechanical stimulation technique. The effectiveness of SWS was compared with that of a commercial compression bioreactor used on reconstructed skin at various stages of maturity. Despite the distinct stimulus conditions applied by the two methods, SWS yielded remarkable outcomes, similar to the effects of the compression bioreactor. It significantly increased the shear modulus of tissue-engineered skin, heightened the density of collagen and elastin fibers, and resulted in an augmentation of fibroblasts in terms of their number and length. Notably, SWS exhibited diverse effects in the low- and high-frequency modes, highlighting the importance of fine-tuning the stimulus intensity. These results unequivocally demonstrated the capability of SWS to enhance the mechanical functions of the skin in vitro, making it a promising option for addressing wound healing and stretch mark recovery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The skin is an envelope that covers the entire body. Nowadays, understanding and studying the mechanical, biological and sensory properties of the skin is essential, especially in dermatology and cosmetology. The in-depth study of the skin's mechanical behaviour is a highly intriguing challenge, enabling the differentiation of the behaviour of each layer. An extension device was developed to perform relaxation and extension tests to characterize the skin. The device has also been coupled with imaging tools (LC-OCT and ultrasound), allowing us to observe layer-by-layer deformations during the tests. Relaxation tests revealed significant skin anisotropy, as well as an influence of age and gender on skin viscoelastic parameters calculated from relaxation curves and a skin viscoelastic model. These tests also unveiled their ability to distinguish certain characteristic pathologies that alter the mechanical properties of the skin, such as scleroderma or heliodermatitis. Furthermore, the optical-mechanical coupling and deformation calculation through image analysis demonstrated that the skin layers exhibit distinct mechanical behaviours owing to their different structures. Finally, Poisson's ratio of the skin was obtained by calculating the deformation in two directions for each layer., Competing Interests: We declare we have no competing interests., (© 2024 The Authors.)

Type I collagen, a fundamental extracellular matrix (ECM) component, is pivotal in maintaining tissue integrity and strength. It is also the most prevalent fibrous biopolymer within the ECM, ubiquitous in mammalian organisms. This structural protein provides essential mechanical stability and resilience to various tissues, including tendons, ligaments, skin, bone, and dentin. Collagen has been structurally investigated for several decades, and variation to its ultrastructure by histology has been associated with several pathological conditions. The current study addresses a critical challenge in the field of collagen research by providing a novel method for studying collagen fibril morphology at the nanoscale. It offers a computational approach to quantifying collagen properties, enabling a deeper understanding of how collagen type I can be affected by pathological conditions. The application of Fast Fourier Transform (FFT) coupled with Atomic Force Microscope (AFM) imaging distinguishes not only healthy and diseased skin but also holds potential for automated diagnosis of connective tissue disorders (CTDs), contributing to both clinical diagnostics and fundamental research in this area. Here we studied the changes in the structural parameters of collagen fibrils in Ehlers Danlos Syndrome (EDS). We have used skin extracted from genetically mutant mice that exhibit EDS phenotype as our model system (Col1a1 Jrt/+ mice). The collagen fibrils were analyzed by AFM based descriptive-structural parameters, coupled with a 2D Fast Fourier Transform(2D-FFT) approach that automated the analysis of AFM images. In addition, each sample was characterized based on its FFT and power spectral density. Our qualitative data showed morphological differences in collagen fibril clarity (clearness of the collagen fibril edge with their neighbouring fibri), D-banding, orientation, and linearity. We have also demonstrated that FFT could be a new tool for distinguishing healthy from tissues with CTDs by measuring the disorganization of fibrils in the matrix. We have also employed FFT to reveal the orientations of the collagen fibrils, providing clinically relevant phenotypic information on their organization and anisotropy. The result of this study can be used to develop a new automated tool for better diagnosis of CTDs., (© 2023. The Author(s).)

Natural skin tension plays an important role during surgical procedures and during the healing process especially for the face. The study of skin tension can be a means of assessing the aging effect, or the application of a medical or cosmetic product. In this work we propose a characterization of the natural human cheek skin tension in vivo and its variability with age using three characterization methods. These methods consist of facial photography to assess the ptosis of the lower face and the nasolabial fold, suction test to estimate mechanical parameters using the cutometer, and topographic analysis of the skin at rest and during folding test to study the skin relief. The study was carried out on 41 volunteers representing two age groups: 18 young volunteers [20-30] years-old and 23 elderly volunteers [50-65] years-old. The results show that the ptosis of the lower face and the nasolabial fold increase with age. The sagging of the skin observed on the facial photos is related to the loss of elasticity and the increase in the skin viscoelasticity with age. The analysis of the cheek skin relief shows that it has a very fine and flexible lines network. This analysis of the skin relief at rest and during the folding test allowed to determine the main directions of skin tension for the different age groups: [20°-40°] for the young group and [20°-60°] for the elderly group. The natural skin tension decreases with age, wrinkles appear and the skin becomes more anisotropic., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Skin irritation is a common phenomenon that becomes a real concern when caused by the use of medical devices. Because the materials used for the design of these devices are usually carefully selected for chemical compatibility with the skin, it is reasonable to assume that the irritations result from the mechanical interaction between the devices and the skin. The aim of this work was to develop a new device to study both the shear strains in the layers of the skin, using Digital Image Correlation (DIC), and the friction behaviour of ex vivo skin interacting with objects. Pig skin samples with various surface preparations were tested in friction experiments involving different contacting materials encountered in the conception of medical devices. The measure of the static and dynamic coefficients of friction as well as the length of adhesion has highlighted the great influence of skin surface conditioning on friction properties. Strain maps obtained through DIC provided insights into the impact of friction and adhesion effects on shear strain distribution in the skin as a function of depth beneath its surface., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Flavor is one of the main drivers of food consumption and acceptability. It is associated with pleasure feels during eating. Flavor is a multimodal perception corresponding to the functional integration of information from the chemical senses: olfaction, gustation, and nasal and oral somatosensory inputs. As a result, astringency, as a sensation mediated by the trigeminal nerves, influences food flavor. Despite the importance of astringency in food consumer acceptance, the exact chemosensory mechanism of its detection and the nature of the receptors activated remain unknown. Herein, after reviewing the current hypotheses on the molecular origin of astringency, we proposed a ground-breaking hypothesis on the molecular mechanisms underpinning this sensation as a perspective for future research.

Osteoarthritis (OA) is a common degenerative disease whose early management includes promising mechanical treatments. New treatments are initially validated using an animal model in which OA is induced. The MMT (mechanical induction) and MIA (chemical induction) models of OA induction are widespread, but their use to generate early OA is poorly documented. We analyzed and compared early-stage knee OA-induction via these two methods in 16 rats divided into two groups. After 4 weeks of induction, the knees were sampled and studied using both histology (Toluidine Blue and Sirius Red) and surface topology, an innovative technique for characterizing osteoarthritic cartilage. The Mankin-modified score confirms that the two OA-induction models evolved at the same speed. At this early stage, the two models can be differentiated morphologically, although no significant differences were revealed by either cellularity or birefringence analysis. However, the topological analysis generated two forms of quantitative data, the deformation ratio and the cohesion index, that differentiated between the two groups. Thus, the early-stage OA induced by these two models is revealed to differ. The patterns of cartilage damage induced point to MMT as the better choice to assess mechanical approaches to clinical OA treatment.

Skin ageing is a complex process which strongly impacts the three skin layers (epidermis, dermis, hypodermis) both functionally and structurally. Of particular interest are the effects of ageing on the dermis biomechanics and how this evolution can impact the reorganization of the cutaneous lines which compose the skin relief. It has been argued that the skin relief could reflect the underlying mechanical condition of the skin. Nevertheless, there is not yet conclusive evidence of the existence of such a link. This work aims at experimentally studying, in vivo, the correlation between the anisotropy of human skin biomechanics and skin topography as a function of ageing. The study was conducted on a panel of 20 men divided into 4 groups according to age (from 23 to 64 years old). The measurements were performed on the right volar forearm of each volunteer. For the biomechanical measurements, an innovative contactless bio-rheometer was developed. It allows access to the mechanical behaviour of the skin in several directions. This device generates an air blast without any contact with the skin area and measures its dynamic response (evaluation of speed of wave propagation) with a linear laser. Moreover, a turntable enables measurements to be made in different angular directions. To analyse the topography of skin relief, we proposed a new method, based on watershed and linear radon transformations. First, an optical analysis of a replica of the skin relief is performed. Then, from the skin image obtained, the density of the cutaneous lines is calculated in different directions using watersheld transformation. The orientation of the detected lines is then estimated with an algorithm based on linear radon transformation. The results observed show a good correlation between the skin relief and the mechanical properties of the skin all along the ageing process. For both topography and mechanical properties, there is a transition from an almost isotropic mechanical behaviour to an anisotropic one as a function of ageing process. Thus, we might conclude that the skin relief reflects the underlying mechanical conditions of the skin., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objective: Aneurysm wall biomechanics are not yet an integral part of aneurysm rupture risk evaluation. We aimed to develop a new technique describing the biomechanical properties of aneurysm wall and correlating them to rupture status., Methods: Aneurysm wall samples collected during surgery were submitted before and after freezing to tensile tests or as fresh samples to indentation tests. The lateral stiffness or the Young's modulus of the different samples was determined as a function of the mechanical test used. The impact of freezing on biomechanical properties was evaluated. The correlation of clinical and radiologic data with the biomechanical profile of the aneurysm samples was investigated. Two-photon microscopy was used to study collagen fiber organization., Results: Sixteen aneurysm samples (11 unruptured and 5 ruptured) were included. Freezing decreased tissue stiffness. No significant difference was found between ruptured and unruptured aneurysm wall samples regarding demographic characteristics, ethnicity, smoking status, arterial hypertension, site, size and shape of the aneurysm, PHASES score, mechanical profile, or overall Young's modulus. Indentation tests found that the rupture occurred in a restricted area of increased elastic capacity and unruptured areas had increased stiffness. Two-photon microscopy found disruption of the collagen fiber network in rupture zones., Conclusions: The indentation test of fresh aneurysm wall samples described the heterogeneity of biomechanical properties of the tissue and found increased elastic capacity in the rupture zone and increased stiffness in the remainder of the aneurysm. This study could be a basis for further research aimed at building a biomechanical-based model of aneurysm rupture risk., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The tactile perception of a surface texture is mediated by factors such as material, topography, and vibrations induced by the sliding contact. In this paper, sensory characterizations are developed together with topographical and tribo-tactile characterizations to relate perceived features with objective measurements of tribological and dynamic signals. Two sets of surface samples are used in this study: the first set is made of a commercial floor covering tiles that aim at counter-typing natural wood flooring, with both a visual and a tactile texture mimicking wood. A second set is custom-made by replicating the first set using a plain purple polyurethane resin. The comparison between tribo-tactile signals and sensory analysis allowed the identification of objective indices for textures with slight topographical differences. Even though the topography of the replicated samples is the same as their corresponding commercial products, the fact that the material is different, induces differences in the contact and vibrational parameters. This in turn modifies the discrimination performances during the sensory experiment. Tactile characteristics collected during sensory procedures are found to be in agreement with objective indices such as friction coefficients and induced vibrations.

Tactile perception is one of the sensorial modes most stimulated by our daily environment. In particular, perceived softness is an important parameter for judging the sensory quality of surfaces and fabrics. Unfortunately, its assessment greatly depends on the tactile sense of each person, which in turn depends on many factors. Currently, the predominant method for evaluating the tactile perception of fabrics is the human handfeel panel. This qualitative approach does not permit the quantitative measure of touch feel perception. In this study, we present a new artificial finger device to investigate the tactile sensing of ten bathroom tissues. It enables simultaneously measuring the friction and vibrations caused when sliding an artificial finger on the surface of the tissue. The comparison between the results obtained with the artificial finger and the tactile perception evaluated using a handfeel panel showed that the artificial finger is able to separate the two parts of the tactile perception of bathroom tissues: softness and surface texture (velvetiness). The statistical analysis suggests that there is a good correlation between the vibrations measured with the artificial finger and the softness evaluated by the panel. It then shows that the friction measured by the artificial finger is related to the surface texture of a bathroom tissue. The ability of the artificial finger to mimic human touch is demonstrated. Finally, a Principal Component Analysis orders the signatures of the tactile perception of the bathroom tissues in four different groups., (Copyright © 2016. Published by Elsevier B.V.)

Tissue engineered skin usually consist of a multi-layered visco-elastic material composed of a fibrillar matrix and cells. The complete mechanical characterization of these tissues has not yet been accomplished. The purpose of this study was to develop a multiscale approach to perform this characterization in order to link the development process of a cultured skin to the mechanical properties. As a proof-of-concept, tissue engineered skin samples were characterized at different stages of manufacturing (acellular matrix, reconstructed dermis and reconstructed skin) for two different aging models (using cells from an 18- and a 61-year-old man). To assess structural variations, bi-photonic confocal microscopy was used. To characterize mechanical properties at a macroscopic scale, a light-load micro-mechanical device that performs indentation and relaxation tests was designed. Finally, images of the internal network of the samples under stretching were acquired by combining confocal microscopy with a tensile device. Mechanical properties at microscopic scale were assessed. Results revealed that adding cells during manufacturing induced structural changes, which provided higher elastic modulus and viscosity. Moreover, senescence models exhibited lower elastic modulus and viscosity. This multiscale approach was efficient to characterize and compare skin equivalent samples and permitted the first experimental assessment of the Poisson's ratio for such tissues.

Background: In this work, we propose an innovative approach based on a rotary tribometer coupled with laser velocimetry for measuring the elastic wave propagation on the skin., Methods: The method is based on a dynamic contact with the control of the normal force (Fn ), the contact length and speed. During the test a quantification of the friction force is produced. The elastic wave generated by friction is measured at the surface of the skin 35 mm from the source of friction exciter. In order to quantify the spectral range and the energy property of the wave generated, we have used laser velocimetry whose spot laser diameter is 120 μm, which samples the elastic wave propagation at a frequency which may reach 100 kHz. In this configuration, the speaker is the friction exciter and the listener the laser velocimetry. In order to perform non-invasive friction tests, the normal stress has been set to 0.3 N and the rotary velocity to 3 revolutions per second, which involves a sliding velocity of 63 mm/s., Results and Conclusions: This newly developed innovative tribometer has been used for the analysis of the elastic wave propagation induced by friction on human skin during chronological ageing and gender effect. Measurements in vivo have been made on 60 healthy men and women volunteers, aged from 25 to 70. The results concerning the energy of the elastic wave signature induced by friction show a clear difference between the younger and older groups in the range of a low band of frequencies (0-200 Hz). The gender effect was marked by a 20% decrease in the energy of elastic wave propagation in the female group., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Surface improvement of implants is essential for achieving a fast osseo-integration. Technically, the creation of a precise pattern on a titanium alloy surface is challenging. Here, the femtosecond laser was chosen as an innovative technology for texturing with accuracy a nano-micro topography. By adjusting the laser parameters, three biomimetic textures were fabricated on the titanium surface: micropits with nano-ripples in the pits, micropits with nano-ripples around the pits, and a texture with only nano-ripples. Mesenchymal stem cells (MSCs, C3H10T1/2) grown on these surfaces displayed altered morphometric parameters, and modified their focal adhesions in term of number, size, and distribution depending on surface type. These results indicate that the MSCs perceived subtle differences in topography. Dynamic analyses of early cellular events showed a higher speed of spreading on all the textured surfaces as opposed to the polished titanium. Concerning commitment, all the laser-treated surfaces strongly inhibited the expression of adipogenic-related genes (PPARϒ2, C/EBPα) and up-regulated the expression of osteoblastic-related genes (RUNX2, osteocalcin). Interestingly, the combination of micropits to nano-ripples enhanced their osteogenic potential as seen by a twofold increase in osteocalcin mRNA. Alkaline phosphatase activity was increased on all the textured surfaces, and lipid production was down-regulated. The functionalization of metallic surfaces by this high-resolution process will help us understand the MSCs' interactions with substrates for the development of textured implants with predictable tissue integrative properties.

Human hair is a non-homogeneous complex material made of keratin fibers oriented along the longitudinal axis which offer anisotropic mechanical properties. Nowadays, it is possible to measure the mechanical properties of hairs with the classical tests, but most often, these tests are destructive and make hard to measure the influence of some external factors or treatments on the behavior of a same hair fiber. In the current paper, vibrations induced by a non-contact impact have been utilized as a representative response of the mechanical behavior of hair. The characteristics of the vibratory response allow measuring the variation in the mechanical properties and the instantaneous effect of an external factor on the properties of a same sample. First, load relaxation tests have been performed on hair samples after moisturization and for different times of an air-drying process in order to characterize the change in the visco-elastic behavior of hair during the water desorption. Other hair samples have been tested with our non-contact impact and vibration technique in order to observe the change in the vibratory response during the water desorption. The vibratory response has then been correlated to the mechanical properties of the hair fiber., (Copyright © 2015 Elsevier Ltd. All rights reserved.)