Osteoarthritis (OA) is a chronic and progressive joint disease characterized by cartilage destruction, synovial thickening, joint space narrowing, osteophyte, and calcium crystal deposition, which affects hundreds of millions of people worldwide [1,2]. Synergetic therapy is an emerging platform for the treatment of OA [3,4], which can provide long-term joint lubrication without shear thinning and restrain the systematic toxicity from oral administration. However, the construction of porous nanocarriers with good lubricating performance and stimuli-responsive drug release is still challenging. We develop a hybrid nanocarrier by growing hydrogel layers on surface of metal-organic framework nanoparticles (nanoMOFs) via one-pot soap-free emulsion polymerization. The core-shell structure of nanoMOFs@microgel demonstrated high-temperature aqueous dispersion stability. Using as aqueous lubricating additives, the hybrids enabled reductions in both the coefficient of friction and wear volume. By co-culturing the anti-inflammatory drug-loaded nanoMOFs@microgel with human normal chondrocytes, the hybrids showed good biocompatibility and anti-inflammatory effect on the chondrocytes with inflammation by regulating the expression of OA-related genes. Our work establishes multifunctional biolubricant system for efficient OA treatment and biomedical application.

Additive manufacturing (AM) processes and corresponding process parameters provide a wide range of structures and mechanical properties. For example, the development of a composite structure with harder particles embedded in a softer metal matrix can lead to the formation of a mechanical blend layer (MML) that significantly decreases the coefficient of friction (COF) and improves wear resistance [1]. In this work, a composite with reinforced quasi-crystalline Al-Fe-Cr aluminum matrix was initially manufactured by selective laser melting (SLM), using a prealloyed Al-Fe-Cr powder. After AM processing, the sample microstructure was composed of a region with coarse quasi-crystals (QCs) particles and a region with fine QC particles (Figure 1). Samples were later characterized by nanoindentation, for evaluation of hardness and elastic modulus of both regions. In parallel, scratch test procedures [2] were conducted on the sample surface, to characterize the effect of a single abrasive particle on both regions. Profilometry tests were conducted to analyze the volumetric loss after the scratch tests and to study the topographic difference of the scratches in both regions. It was identified that the region of fine particles presented an elastic modulus for low nanoindentation load values that is lower than that of the region with coarse particles (Figure 2a). Besides, during the scratch tests, changes in the abrasion micromechanisms were noted as a function of the variation in normal load. Scratch tests have also indicated how the friction and wear behavior was affected by microstructural features, such as quasi-crystal particle distribution (Figure 3). In the end, profilometry analyses indicated that the fine particle region presented the largest volumetric losses after the scratch tests (Figure 2b), corroborating the results of the nanoindentation tests. Results of the micromechanical analysis were later correlated with the behavior of the sample in mechanical polishing (with abrasive sizes down to 0.06 µm), also characterized by profilometry, after which it was noticed that the fine particle region, topographically, is below to the region of coarse particles.

The global ecological context is compelling agri-food industry professionals to increase the production of sustainable food by expanding plant-based protein production. However, foods containing these types of proteins often have a very astringent taste with sensations of dryness, puckering, and a non-juicy perception [1]. The components responsible for astringency are known as polyphenols [2]. This sensation is due to the loss of lubrication on the epithelium because of the aggregation of polyphenols and plant proteins with epithelial proteins such as MUC1[3]. An oral epithelium model was developed to evaluate the effect of polyphenols and plant proteins on epithelium model lubrication and to analyse the protective mechanisms established by the oral mucosa to limit polyphenol and proteins damages before and after friction. An original tribometer was developed within the scope of this work to perform friction on the epithelium model. Tests were conducted by applying polyphenols to epithelium models to examine their effects. In certain cases, proteins rich in proline (PRPs) were additionally introduced to assess their protective capacity against polyphenols. To analyse the effects of these elements, we investigated damage surfaces as well as topographies as indicators. According to the literature, polyphenols induce aggregations that may disrupt epithelial lubrication, thereby resulting in a sensation of astringency [4]. The results of this study indicate that the addition of polyphenols and plant proteins altered the topography of epithelium models, leading to an increase in roughness that characterizes polyphenol aggregation on the surface, see Figure 1 . This topographical alteration is also correlated with an increase in friction forces. Importantly, the study demonstrated that the prior addition of PRPs mitigated the impact of polyphenols, thereby reducing the alteration of the topography. The analysis of damage also revealed that the presence of polyphenols and plant proteins caused more significant damage after friction compared to samples without astringent component addition. These damages were also less pronounced in the presence of PRPs. In conclusion, this study highlights that polyphenols and plant proteins disrupt the surface of oral epithelium models, as evidenced by the alteration of topography associated with an increase in friction forces. These findings suggest that these astringent compounds disturb epithelial lubrication, giving rise to the sensation of astringency. However, the presence of PRPs appears to play a protective role by limiting aggregations, thereby reducing the sensation of astringency and mitigating the effects of polyphenols and plant proteins.

Recent interest in improving lifespan of electrical slip rings for application in wind turbines has renewed the need for deeper understanding of sliding electrical contact operation. In contact slip rings using graphite-based brush technology, the creation of a tribofilm, or “patina”, at the interface with the metal slip ring is a well-known phenomenon [1, 2]. In this scope, the study of its formation in a bronze/silver-graphite contact has been conducted. The test bench is based on an instrumented industrial slip ring specific for wind turbine application (Figure 1). It permits to measure the electrical performance of the contact during the rotation. The electrical resistance measurement, coupled with an encoder for the angular position, allows to draw the electrical resistance as a function of both the number of cycles and the position of the brush on the ring. Thanks to this, we are able to link the electrical performance to the structural and chemical state of the tribofilm. We performed surface and structural observations with optical microscope and SEM/TEM/EDX, as well as advanced chemical surface characterization with XPS and Raman spectroscopy. Thanks to this multitechnique analysis, a scenario of tribofilm formation on the metallic surface of the slip ring has been proposed, and permits to justify the evolution of the electrical performance of the sliding contact (Figure 2). Wear measurements on the silver-graphite brushes were also conducted. The results show an influence of both the electrical current direction and the brushes sliding direction on wear. If the polarity effects were already documented in the literature [3-5] and can be explained by oxidation phenomena, the effect of the sliding direction seems to be more peculiar. We suspect the loose third body, composed by powdery wear debris, to be responsible for the reduction of the brush wear. It could explain why the effect of sliding direction is not well described, since it would depend on the contact geometry and its debris retention capability. Further investigation will be undertaken to confirm this hypothesis. We also want to estimate the impact of a modification of the roughness of the metallic ring, which could play a role in the debris retention and the tribofilm formation.

Everybody wants beautiful hair that is pleasant to touch. Indeed, hair has great social significance for human beings as it reflects our physical state. Thus, for many years, especially in the second half of the 20th century, scientists have focused on the physical and chemical properties of hair and developed methods of evaluation based on scientific values. We propose to explore the tribological and morphological hair changes due to chemical and thermomechanical treatments. Caucasian hair samples were used. We studied the effect of chemical and thermomechanical treatments on the sensorial properties of hair. The morphology of hair was evaluated using optical interferometry and wavelet analysis. A haptic tribometer system to perform the friction tests and simultaneously measure the friction force and the vibrations between the probe and the hair surface. Several key results were obtained in this study. First, a new method using wavelet decomposition of a surface was used to quantitatively evaluate hair cuticle modifications at different scales. The SMa and NAD parameters were found to be good indicators of the sensorial properties of hair (softness and brightness). Then, we introduced vibration analysis during the friction test as a new parameter to study the tribological behavior of the hair surface. The acoustic vibratory level was found to be a good indicator of the hair surface’s softness. Furthermore, the dependence of the frequency peak of the induced vibrations during the friction tests, with respect to the roughness of the hair surface was demonstrated. An increase in roughness corresponds to a peak of higher amplitude. Finally, it appeared that coloring and bleaching hair damaged it and impacted its sensorial properties: the hair fiber became less soft, less bright and rougher. Moreover, applying thermomechanical treatments to damaged hair improved sensorial properties by smoothing the surface and erasing the asperities. Thus, the hair fiber appears brighter and smoother.

This paper investigates the impact of ion infiltration of substrates on the optical properties of films. SnO2 films are prepared on silica-soda-lime (SL) and fused quartz (FQ) substrates by spin-coating method with the same growth parameters. The roughness of the films is characterised by atomic force microscopy (AFM). The compositions are determined by X-ray photoelectron spectroscopy (XPS). The physical properties, such as refractive index and extinction coefficient, are analyzed by spectroscopic ellipsometry (SE) with a single Tauc-Lorentz oscillator model in the wavelength range between 250-1000nm. Results show that the refractive index on FQ is more significant than that on SL, which may be caused by the metal ions of substrates. This phenomenon indicates that the substrate type affect the film's optical properties. In addition, the whale optimisation algorithm (WOA) is applied for the determination of thicknesses and refractive index of SnO2 in different substrates with transparent wavelength coverage (400nm-800nm), and it found that the results obtained by the WOA algorithm agree with those by SE well.

The manufacturing sector is consistently looking to move towards more smart and autonomous processes in order to reduce wastage and achieve ‘right first-time every-time’ outcomes. This requires sufficient real-time feedback from processes to correct errors during machining/build cycles. Achieving this is non-trivial and requires the proliferation of sensors integrated to provide ‘on-machine’ or ‘in-process’ measurement. The current size, weight and cost of conventional optical instrumentation is a significant barrier to realising this vision. While there have been ongoing efforts to realise small and lightweight instrumentation using conventional approaches these have seen limited success in general. However, recent developments in the areas of nanophotonics and metasurfaces means they now offer a path by which a step-change in these key sensor attributes can be achieved. Here, we discuss our recent work in this area, considering how metasurfaces can be utilised to both miniaturise and simplify optical systems. The flexible control of optical wavefronts passing through metasurfaces also potentially provides a path to implement techniques that, if realised using conventional glass elements could only be achieved using complex and difficult to manufacture freeform optical surfaces. Our recent work has looked at exploiting metasurfaces to create ultra-compact realisations of several optical techniques prevalent in surface and dimensional metrology, including confocal microscopy, chromatic confocal microscopy, spectroscopy and focus variation. However, the potential of this approach goes far beyond this. The metasurfaces implemented are of the truncated optical waveguide form, consisting of square arrays of GaN pillars having a fixed height of 750 nm and arranged with a centre-to-centre spacing of 450 nm. The radii of the pillars are varied to change the local phase delay that light experiences when passing through them. Circular pillars are used which minimise polarisation dependence which is advantageous for sensors detecting light reflected from unknown surfaces. A selection of the manufactured metasurfaces on an Al_2 O_3 substrate is shown in figure 1(a). The confocal sensor shown in figure 1(b) demonstrates how multiple functions can be combined in a single metasurface, interleaving pillars that deliver two different phase delays simultaneously allow the sensor to be realised with just the addition of a point light source and a point detector. The chromatic confocal sensor (CCS) shown in figure 1(c) utilises the chromatic aberration inherent in basic hyperbolic metalens designs to remove the need for groups of lenses or diffractive optical elements. In this realisation, the end of an optical fibre is used as the point source with the only additional element needed to realise the probe being the metalens. In addition, we have combined this with metalens-enhanced probe with a compact specklemeter. This device the analyses wavelength dependant speckle patterns, produced by a pseudo-randomized scattering medium consisting of femtosecond laser machined voids, to replace a conventional bulk optic spectrometer. This approach yields a CCS sensor with both the probe and the detection elements realised in an ultra-compact form. Finally, we describe a focus variation instrument that exploits the wavelength dependent focal plane of a simple metalens to determine topography using a ‘shape-from-focus’ approach without any mechanical scanning of elements, and a metasurface based spectrometer implemented by a metalens which combines dispersion and focussing functions in a single element. Summary: Nanophotonic elements, including photonic metasurfaces, offer a new path to the creation of ultra-compact instrumentation which can overcome the longstanding barriers present when using traditional approaches to optical sensor design. We show how they can provide a path to the development of a new generation of ultra-compact optical instrumentation which will underpin the necessary proliferation of on-machine optical sensors and support the development of more smart and autonomous manufacturing processes.

Metallic-based additive manufacturing through Laser-Powder Bed Fusion (L-PBF) has gained significant attention across various sectors due to its capability to produce highly accurate, complex, and customised geometric parts [1, 2]. Consequently, addressing unexpected deviations from the intended geometry during the production process through post-processing operations becomes challenging, particularly for internal complex features. To address this limitation, in-process layer-based surface measurement methods are an active area of research to enable in-time corrective actions or process halts upon the identification of critical defects [1, 3–6]. Fringe projection (FP) [3, 7] has shown potential as a suitable measurement technique, owing to its high-resolution, non-invasive, and full-field surface topology measurement capabilities, facilitating defect detection. In the L-PBF process, FP measurements are typically implemented in a fully-closed confined machine chamber. This requires the proper integration of the measurement system with the existing machine setup to enable accurate measurement of the printed surface within the expected limits of accuracy and resolution, minimising errors. To fully exploit FP advantages for measuring surface topology in L-PBF, appropriate hardware choices regarding the measurement system are crucial. Additionally, the FP acquisition and reconstruction algorithms should be customised to realise the required measurement speed and accuracy. This study identifies factors significantly impacting measurement speed, accuracy and resolution, with emphasis on investigating the impact of hardware selection and related parameters. Simulations conducted using Unity and Solidworks software offer insights into depth of field, resolution, and field of view within a 1:1 scale mock-up chamber within an L-PBF machine (see Figures 1 and 2 for the design and FP simulation, respectively). This analysis enables the selection of suitable lens and aperture sizes, allowing to focus on the measurement area and reducing noise interference due to compact space of L-PBF chamber. Based on the hardware setup and simulation outcomes, an optimal depth of field is determined to ensure consistent fringe resolution across the target area. Furthermore, the gamma calibration plots signify the appropriate choice and application of fringe projection methods.

Recent advancements in manufacturing technologies, notably in additive manufacturing, have enabled the production of complex freeform surfaces tailored to meet specific functional requirements. However, the precise measurement and characterization of these intricate surfaces pose significant challenges when using traditional methods. In our prior research, we established a comprehensive framework for characterizing freeform surfaces represented as 3D triangle meshes. This innovative approach allows for a complete assessment of 3D surface topography without compromising any data. Within this framework, we have also developed and validated a suite of 3D parameters. These parameters encompass various dimensions, including height, hybrid, volume, and feature-specific measurements. A critical aspect of 3D surface characterization is surface decomposition, which entails differentiating the surface texture from the foundational reference surface. This paper introduces our latest advancements in freeform surface filtration techniques essential for effective decomposition. We are currently developing four distinct types of filtration methods: (1) Laplacian Diffusion Filter: This functions similarly to the standard Gaussian filter but is tailored for lattice grid surfaces. It effectively smoothens the surface while maintaining its essential characteristics. (2) Improved Diffusion Filter with Anti-Shrinkage Properties: This innovative filter is adept for both dimensional analysis and surface texture assessment. Its anti-shrinkage feature ensures that the true nature of the surface is retained during the filtration process. (3) Feature-Preserving Diffusion Filter: Specifically designed for structured freeform surfaces, this filter maintains the integrity of distinct surface features while performing necessary filtration. (4) Morphological Filters: These versatile filters are capable of executing a range of operations, including morphological erosion, dilation, opening, closing, and sequential procedures. They are instrumental in refining the surface for detailed analysis. The paper will introduce these filtration methods and present preliminary results demonstrating their efficacy in the context of freeform surface characterization. This research marks a significant step forward in the precise analysis of complex surfaces, paving the way for more advanced applications in manufacturing and quality control.