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The reported study was devoted to the investigation of viscoelastic behavior for solid and porous ultra-high molecular weight polyethylene (UHMWPE) under compression. The obtained experimental stress curves were interpreted using a two-term Prony series to represent the superposition of two coexisting activation processes corresponding to long molecular (~160 s) and short structural (~20 s) time scales, respectively, leading to good statistical correlation with the observations. In the case of porous polymer, the internal strain redistribution during relaxation was quantified using digital image correlation (DIC) analysis. The strongly inhomogeneous deformation of the porous polymer was found not to affect the relaxation times. To illustrate the possibility of generalizing the results to three dimensions, X-ray tomography was used to examine the porous structure relaxation at the macro- and micro-scale levels. DIC analysis revealed positive correlation between the applied force and relative density. The apparent stiffness variation for UHMWPE foams with mixed open and closed cells was described using a newly proposed three-term expression. Furthermore, in situ tensile loading and X-ray scattering study was applied for isotropic solid UHMWPE specimens to investigate the evolution of internal structure and orientation during drawing and stress relaxation in another loading mode.

Recent years witnessed progressive broadening of the practical use of 3D-printed aluminium alloy parts, in particular for specific aerospace applications where weight saving is of great importance. Selective laser melting (SLM) is an intrinsically multi-parametric fabrication technology that offers multiple means of controlling mechanical properties (elastic moduli, yield strength, and ductility) through the control over grains size, shape, and orientation. Targeted control over mechanical properties is achieved through the tuning of 3D-printing parameters and may even obviate the need of heat treatment or mechanical post-processing. Systematic studies of grain structure for different printing orientations with the help of EBSD techniques in combination with mechanical testing at different dimensional levels are the necessary first steps to implement this agenda. Samples of 3D-printable Al-Mg-Si RS-333 alloy were fabricated in three orientations with respect to the principal build direction and the fast laser beam scanning direction. Sample structure and proper-ties were investigated using a number of techniques, including EBSD, in situ SEM tensile testing, roughness measurements, and nanoindentation. The as-printed samples were found to display strong variation in Young’s modulus values from nanoindentation (from 43 to 66 GPa) and tensile tests (from 54 to 75 GPa), yield stress and ultimate tensile strength (100–195 and 130–220 MPa) in different printing orientations, and almost constant hardness of about 0.8 GPa. A further preliminary study was conducted to assess the effect of surface finishing on the mechanical performance. Surface polishing was seen to reduce Young’s modulus and yield strength but improves ductility, whereas the influence of sandblasting was found to be more controversial. The experimental results are discussed in connection with the grain morphology and orientation.

Siliceous diatom frustules represent an up-and-coming platform for a range of bio-assisted nanofabrication processes able to overcome the complexity and high cost of current engineering technology solutions in terms of negligibly small power consumption and environmentally friendly processing combined with unique highly porous structures and properties. Herein, the modification of diatomite - a soft, loose, and fine-grained siliceous sedimentary rock composed of the remains of fossilized diatoms - with gold nanoparticles using layer-by-layer technology in combination with a freezing-induced loading approach is demonstrated. The obtained composite structures are characterized by dynamic light scattering, extinction spectroscopy, scanning (SEM) and transmission electron microscopy (TEM), and photoacoustic imaging techniques, and tested as a platform for surface-enhanced Raman scattering (SERS) using Rhodamine 6G. SEM, TEM, and energy dispersive X-ray spectroscopy (EDX) confirmed a dense coating of gold nanoparticles with an average size of 19 nm on the surface of the diatomite and within the pores. The photoacoustic signal excited at a wavelength of 532 nm increases with increasing loading cycles of up to three polyelectrolyte-gold nanoparticle bilayers. The hybrid materials based on diatomite modified with gold nanoparticles can be used as SERS substrates, but also as biosensors, catalysts, and platforms for advanced bioimaging.

The reported study was devoted to the investigation of viscoelastic behavior for solid and porous ultra-high-molecular-weight polyethylene (UHMWPE) under compression. The obtained experimental stress curves were interpreted using a two-term Prony series to represent the superposition of two coexisting activation processes corresponding to long molecular (~160 s) and short structural (~20 s) time scales, respectively, leading to good statistical correlation with the observations. In the case of porous polymer, the internal strain redistribution during relaxation was quantified using Digital Image Correlation (DIC) analysis. The strongly inhomogeneous deformation of the porous polymer was found not to affect the relaxation times. In order to generalize the results to three dimensions, X-ray tomography was used to examine the porous structure at the macro- and micro-scale levels. DIC analysis revealed positive correlation between the applied force and relative density. The apparent stiffness variation for UHMWPE foams with mixed open and closed cells was described using a newly proposed three-term expression. Furthermore, the in situ tensile loading and X-ray scattering study was applied for isotropic solid UHMWPE specimens to investigate their parameters of internal structure during orientation and stress relaxation process at another mode.

Photosynthetic single-celled diatom algae, due to their unique structure and properties, represent promising candidates for various applications in technology and biomedicine. These nanostructured objects, enveloped within a silica cell wall called a frustule, play a significant role in Earth’s ecology. In this study, we proposed new techniques for monitoring the growth of diatoms—in situ fluorescence measurements using the IVIS imaging system and photoacoustic measurements with a raster scanning optoacoustic mesoscopy (RSOM) setup. Two different diatom cultures, Achnanthidium sibiricum and Encyonema silesiacum, were cultivated under the optimal conditions in the incubator and monitored over the period of 70 days. Our results showed that the total radiant efficiency increases with increasing incubation time for E. silesiacum. Simultaneously, for A. sibiricum it slightly decreases after 56 days, indicating that diatoms were at the end of their exponential growth phase. The photoacoustic signal from E. silesiacum was lower than from A. sibiricum, which is in good agreement with spectroscopic characterization results. The IVIS imaging system made it possible to assess the growth and viability of diatom cells without compromising cell integrity. In contrast, photoacoustic imaging has proved to be suitable for the rapid detection and thorough in situ assessment of the density of diatom colonies due to the presence of light-absorbing chromophores. These methods can be used to monitor the growth of diatoms and facilitate the harvesting of bioactive substances derived from diatoms for pharmaceutical and biomedical purposes.

The present article overviews the current state-of-the-art and future prospects for the use of diatomaceous earth (DE) in the continuously expanding sector of energy science and technology. An eco-friendly direct source of silica and the production of silicon, diatomaceous earth possesses a desirable nano- to micro-structure that offers inherent advantages for optimum performance in existing and new applications in electrochemistry, catalysis, optoelectronics, and biomedical engineering. Silica, silicon and silicon-based materials have proven useful for energy harvesting and storage applications. However, they often encounter setbacks to their commercialization due to the limited capability for the production of materials possessing fascinating microstructures to deliver optimum performance. Despite many current research trends focusing on the means to create the required nano- to micro-structures, the high cost and complex, potentially environmentally harmful chemical synthesis techniques remain a considerable challenge. The present review examines the advances made using diatomaceous earth as a source of silica, silicon-based materials and templates for energy related applications. The main synthesis routes aimed at preserving the highly desirable naturally formed neat nanostructure of diatomaceous earth are assessed in this review that culminates with the discussion of recently developed pathways to achieving the best properties. The trend analysis establishes a clear roadmap for diatomaceous earth as a source material of choice for current and future energy applications.

A series of experiments was carried out using strips (and nets) of synthetic polymers to increase the contact surface during the cultivation of attached forms of microphytes. We used bands of different composition, as well as with different microrelief surface areas, and a fine-mesh PLA network with an inhomogeneous surface. The experiments were performed on liquid nutrient media in accumulative cultures, and on solid nutrient medium in pure culture. The results showed a number of positive features of such cultivation, based on the selective isolation of individual species and their small combinations from the composition of accumulative cultures, as well as on the effective growth of individual species on specific elements of the microrelief of polymer surfaces. The polymers used were: PET, PP, LDPE, UHMWPE and PLA.

Electrospinning fabrication of mats presents new opportunities for flexible manufacturing of hierarchically structured materials. Electrospun mats were fabricated from the solutions of 10 wt% polyvinyl alcohol (PVA) and 2 wt% of collagen gel mixed in different mass ratios (50:50, 60:40, 70:30, 80:20, 90:10). The use of 10 wt% PVA aqueous solution leads to stable fiber formation. In the present study we demonstrate that this solution provides a good base to produce collagen-PVA fiber mats by electrospinning. Beadless fibers were formed for collagen concentration not exceeding 0.6 wt% from the whole solution, that corresponds to the 70:30 mixing ratio of the PVA solution to collagen gel. All PVA-collagen solutions were measured to find out the dynamic viscosity at the corresponded shear rate.

The pursuit of new nanotechnologies is driven by the demand for miniaturization, ubiquitous computing, increasing connectivity and the Internet of Things (IoT) paradigm, the environmental agenda, and the confluence between microelectronics and biomedical fields. Of particular interest for the present overview are the capabilities of prokaryotic and eukaryotic microorganisms to fabricate numerous nanostructured self-copies from ecologically friendly and renewable raw materials offering new pathways for low energy consumption, smart nanofabrication at production rates that remain unattainable for today’s engineering technologies. The present discussion is focused on the use of stiff and strong nanostructured silica diatom frustules that is widely mooted in the literature in consideration of photonic, photovoltaic, plasmonic, and drug delivery applications. Chemical post-processing routes can be applied to synthesize and deposit nanostructures (Ag, Au, MnO2, ZnO etc.) using templates and substrates of diatomaceous earth and individual diatom frustules. In this concise overview we discuss the background knowledge, motivation and justification for the use of siliceous diatom frustules as a platform for smart nanofabrication, and attempt to anticipate future developments in this field.

Diatom algae are active and efficient photosynthesizing single cell organisms responsible for a quarter of biomass and a quarter of oxygen release on the Earth surface. Diatoms form an enormously diverse class of microorganisms possessing stiff and strong, durable exoskeletons made from hydrated amorphous silica forming neat 3D nanostructures, and displaying hierarchical organization up to the scale of tens of micrometres. In our ongoing research into the structure and properties of diatoms we observed their colonization patterns on various surfaces, including polymers (PE, PP, PC and PETF) and silicon. This process can be guided by purposeful surface patterning to introduce pits, grooves, and ledges. Guided colonization opens the prospect of assembly and harvesting diatom frustules for applications in micro- and nano-electro-mechanical systems (MEMS and NEMS). Additionally, the wide range and specificity of diatoms opens the possibility of using them as tags and markers that are below the level of visibility by naked eye, but present specific spectroscopic fingerprints in visible light and UV ranges. Diatom ‘tags’ can also be read using high magnification imaging using Scanning Electron Microscopy (SEM). As a contributory guidance to morphological diversity of diatoms we present a mini-atlas of diatom in the form of high resolution SEM images.

SLM Additive Manufacturing has demonstrated great potential for aerospace applications when structural elements of individual design and/or complex shape need to be promptly supplied. 3D-printable AlSi10Mg (RS-300) alloy is widely used for the fabrication of different structures in aerospace industry. The importance of the evaluation of residual stresses that arise as a result of complex 3D-printing process thermal history is widely discussed in literature, but systematic assessment remains lacking for their magnitude, spatial distribution, and comparative analysis of different evaluation techniques. In this study we report the results of a systematic study of residual stresses in a 3D-printed double tower shaped samples using several approaches: the contour method, blind hole drilling laser speckle interferometry, X-ray diffraction, and Xe pFIB-DIC micro-ring-core milling analysis. We show that a high level of tensile and compressive residual stresses is inherited from SLM 3D-printing and retained for longer than 6 months. The stresses vary over a significant proportion of the material yield stress. All residual stress evaluation techniques considered returned comparable values of residual stresses even regardless of dramatically different dimensional scales from millimeters for the Contour Method down, laser speckle interferometry and XRD and down to small fractions of a mm (70 μm) for Xe pFIB-DIC ring-core drilling. The use of residual stress evaluation is discussed in the context of optimizing the printing strategy to enhance the mechanical performance and long-term durability.

The structure of self-reinforced composites (SRCs) based on ultra-high molecular weight 21 polyethylene (UHMWPE) was studied by means of Wide-Angle X-Ray Scattering (WAXS), X-Ray 22 tomography, Raman spectroscopy, Scanning Electron Microscopy (SEM) and in situ tensile testing 23 in combination with advanced processing tools like Avizo, ImageJ, and Ncorr to determine the cor-24 relation between the processing conditions, on the one hand, and the molecular structure and 25 mechanical properties, on the other. SRCs were fabricated by hot compaction of UHMWPE fibers at 26 different pressure and temperature combinations without addition of polymer matrix or softener. 27 It was found by WAXS that higher compaction temperatures led to more extensive melting of 28 fibers with the corresponding reduction of the Herman’s factor reflecting the degree of molecular 29 orientation, while the increase of hot compaction pressure suppressed the melting of fibers within 30 SRCs at a given temperature. X-Ray tomography proved the absence of porosity while polarized 31 light Raman spectroscopy measurements for both longitudinal and perpendicular fiber orienta-32 tions showed qualitatively the anisotropy of SRC samples. SEM revealed that the matrix was 33 formed by interlayers of molten polymer entrapped between fibers in SRCs. Moreover, in situ 34 tensile tests demonstrated the increase of Young’s modulus and tensile strength with increasing 35 temperature.

3D-printed aluminium alloy fabrications made by selective laser melting (SLM) offer a promising route for the production of small series of custom-designed heat exchangers with complex geometry and shape and miniature size. Alloy composition and printing parameters need to be optimized to mitigate fabrication defects (pores and microcracks) and enhance the part performance. The deformation response needs to be studied with adequate characterization techniques at relevant dimensional scale capturing the peculiarities of micro-mechanical behavior relevant to the particular article and specimen dimensions. Purposefully designed Al-Si-Mg 3D-printable RS-333 alloy was investigated with a number of microscopy techniques including in situ mechanical testing with a Deben Microtest 1 kN stage integrated and synchronized with Tescan Vega3 SEM to acquire high resolution image datasets for Digital Image Correlation (DIC) analysis. Dog bone specimens were 3D-printed in different orientation of gauge zone cross-section with respect to the fast laser beam scanning and growth directions. This corresponds to varying local conditions of metal solidification and cooling. Specimens show variation in mechanical properties, namely, Young’s modulus (65…78 GPa), yield stress (80–150 MPa), ultimate tensile strength (115–225 MPa) and elongation at break (0,75–1,4 %). Furthermore, the failure localization and character was altered with the change of gauge cross-section orientation. DIC analysis allowed correct strain evaluation that overcame the load frame compliance effect and helped to identify the unevenness of deformation distribution (plasticity waves) that ultimately resulted in exceptionally high strain localization near the ultimate failure crack position.

Plastic debris is gradually filling the seas, oceans, and freshwater bodies of the planet. Since the 1950s, a huge amount of plastic has entered into various bodies of water. All these objects decompose at different rates, and aquatic organisms take part in these processes. This book chapter provides an overview of studies carried out in recent decades on the interaction between microorganisms and plastic debris in the aquatic environment. Both prokaryotic communities and algo-bacterial cenoses are considered. A separate section is devoted to the research results of the authors of this book chapter, obtained in the natural environment, contaminated with plastic, and in field experiments in the sea.

Carbonized elastomer-based composites (CECs) possess a number of attractive features in terms of thermomechanical and electromechanical performance, durability in aggressive media and facile net-shape formability, but their relatively low ductility and strength limit their suitability for structural engineering applications. Prospective applications such as structural elements of micro-electro-mechanical systems MEMS can be envisaged since smaller principal dimensions reduce the susceptibility of components to residual stress accumulation during carbonization and to brittle fracture in general. We report the results of in situ in-SEM study of microdeformation and fracture behavior of CECs based on nitrile butadiene rubber (NBR) elastomeric matrices filled with carbon and silicon carbide. Nanostructured carbon composite materials were manufactured via compounding of elastomeric substance with carbon and SiC fillers using mixing rolling mill, vulcanization, and low-temperature carbonization. Double-edge notched tensile (DENT) specimens of vulcanized and carbonized elastomeric composites were subjected to in situ tensile testing in the chamber of the scanning electron microscope (SEM) Tescan Vega 3 using a Deben microtest 1 kN tensile stage. The series of acquired SEM images were analyzed by means of digital image correlation (DIC) using Ncorr open-source software to map the spatial distribution of strain. These maps were correlated with finite element modeling (FEM) simulations to refine the values of elastic moduli. Moreover, the elastic moduli were derived from unloading curve nanoindentation hardness measurements carried out using a NanoScan-4D tester and interpreted using the Oliver–Pharr method. Carbonization causes a significant increase of elastic moduli from 0.86 ± 0.07 GPa to 14.12 ± 1.20 GPa for the composite with graphite and carbon black fillers. Nanoindentation measurements yield somewhat lower values, namely, 0.25 ± 0.02 GPa and 9.83 ± 1.10 GPa before and after carbonization, respectively. The analysis of fractography images suggests that crack initiation, growth and propagation may occur both at the notch stress concentrator or relatively far from the notch. Possible causes of such response are discussed, namely, (1) residual stresses introduced by processing, (2) shape and size of fillers, and (3) the emanation and accumulation of gases in composites during carbonization.

Numerical simulations were carried out using the Finite Element Method (FEM) to determine the frequency characteristics of mechanical vibration of diatom silica frustules under the conditions and at frequencies that are not readily accessible to experimental measurement. The results revealed the influence of the frustule morphology on the natural frequency spectra. The effect of frustule density, stiffness, dimensions, pore size, and wall thickness on the eigenfrequencies and the corresponding modal shapes were studied in detail. Diatom frustules have natural frequencies in the range between several MHz and tens of MHz that make them a promising candidate for future MEMS applications. Eigenfrequencies depend linearly on the speed of sound in the frustule wall and decrease parabolically with the diameter and the pore size to diameter ratio. Dimensional analysis allowed obtaining functional correlations that encapsulate the various dependencies in compact analytical form. The satisfactory nature of our calculations and correlations derived from them is confirmed through an agreement with the analytical solutions from the literature.

Porous ultra-high molecular weight polyethylene (UHMWPE) is a high performance bioinert polymer used in cranio-facial reconstructive surgery in procedures where relatively low mechanical stresses arise. As an alternative to much stiffer and costly polyether-ether-ketone (PEEK) polymer, UHMWPE finds further wide application in hierarchically structured hybrids for advanced implants mimicking cartilage, cortical and trabecular bone tissues within a single component. The mechanical behaviour of open-cell UHMWPE sponges obtained through sacrificial desalination of hot compression-moulded UHMWPE-NaCl powder mixtures shows a complex dependence on the fabrication parameters and microstructural features. In particular, similarly to other porous media it displays significant inhomogeneity of strain that readily localises within deformation bands that govern the overall response. In this article, we report advances in the development of accurate experimental techniques for operando studies of the structure-performance relationship applied to the porous UHMWPE medium with pore sizes of about 250 µm that are most well-suited for live cell proliferation and fast vascularization of implants. Samples of UHMWPE sponges were subjected to in situ compression using a micromechanical testing device within Scanning Electron Microscope (SEM) chamber, allowing the acquisition of high-resolution image sequences for Digital Image Correlation (DIC) analysis. Special masking and image processing algorithms were developed and applied to reveal the evolution of pore size and aspect ratio. Key structural evolution and deformation localisation phenomena were identified at both macro- and micro-structural levels in the elastic and plastic regimes. The motion of pore walls was quantitatively described, and the presence and influence of strain localisation zones were revealed and analysed using DIC technique.

Porous ultra-high molecular weight polyethylene (UHMWPE) is a high-performance bioinert polymer used in cranio-facial reconstructive surgery in procedures where relatively low mechanical stresses arise. As an alternative to much stiffer and more costly polyether-ether-ketone (PEEK) polymer, UHMWPE is finding further wide applications in hierarchically structured hybrids for advanced implants mimicking cartilage, cortical and trabecular bone tissues within a single component. The mechanical behaviour of open-cell UHMWPE sponges obtained through sacrificial desalination of hot compression-moulded UHMWPE-NaCl powder mixtures shows a complex dependence on the fabrication parameters and microstructural features. In particular, similarly to other porous media, it displays significant inhomogeneity of strain that readily localises within deformation bands that govern the overall response. In this article, we report advances in the development of accurate experimental techniques for operando studies of the structure–performance relationship applied to the porous UHMWPE medium with pore sizes of about 250 µm that are most well-suited for live cell proliferation and fast vascularization of implants. Samples of UHMWPE sponges were subjected to in situ compression using a micromechanical testing device within Scanning Electron Microscope (SEM) chamber, allowing the acquisition of high-resolution image sequences for Digital Image Correlation (DIC) analysis. Special masking and image processing algorithms were developed and applied to reveal the evolution of pore size and aspect ratio. Key structural evolution and deformation localisation phenomena were identified at both macro- and micro-structural levels in the elastic and plastic regimes. The motion of pore walls was quantitatively described, and the presence and influence of strain localisation zones were revealed and analysed using DIC technique.

Highlights • Photoacoustic and fluorescence lifetime imaging of diatoms was demonstrated for the first time. • The photoacoustic signal of diatom algae is proportional to their concentration. • Chlorophyll a and c and possibly fucoxanthin are the likely sources of photoacoustic signal. • Chlorophyll a in diatoms shows a strong fluorescence signal. • Fluorescence lifetime of the diatom chromophores is in the range 0.5–2 ns., Photoacoustic and fluorescent methods are used intensely in biology and medicine. These approaches can also be used to investigate unicellular diatom algae that are extremely important for Earth’s ecology. They are enveloped within silica frustules (exoskeletons), which can be used in drug delivery systems. Here, we report for the first time the successful application of photoacoustic (PA) and fluorescent visualization of diatoms. Chlorophyll a and c and fucoxanthin were found likely to be responsible for the photoacoustic effect in diatoms. The PA signal was obtained from gel drops containing diatoms and was found to increase with the diatom concentration. The fluorescence lifetime of the diatom chromophores ranged from 0.5 to 2 ns. The dynamic light scattering, absorbance, and SEM characterization techniques were also applied. The results were considered in combination to elucidate the nature of the photoacoustic signal. Possible biotechnological applications are proposed for the remote photoacoustic monitoring of algae.

COVID-19 pandemic provoked a number of restrictive measures, such as the closure or severe restriction of border transit for international trading traffic, quarantines and self-isolation. This caused a series of interrelated consequences that not only prevent or slow down the spread of disease, but also impact the medical systems’ capability to treat the patients and help their recovery. In particular, steeply growing demand for medical safety goods cannot be satisfied by regular suppliers due to the shortage of raw materials originating from other countries or remotely located national sources, under conditions of quarantined manpower. The current context inevitably brings back memories (and records!) of the situation 80 years ago, when WWII necessitated major effort directed at the rapid build-up of low cost mass production to satisfy all aspects of war-time need. In the present short report we document a successful case of fast mass-production of light transparent medical safety face shields (thousands per day) realized in Skolkovo Institute of Science and Technology (Skoltech) fabrication laboratory (FabLab). The demand for safety face shields by tens of hospitals in Moscow City and Region rapidly ramped up due to the need to protect medical staff during patient collection and transportation to hospitals, and within both the infected (“red”) and uninfected (“green”) zones. Materials selection for sterilizable transparent materials was conducted based on the analysis of merit indices, namely, minimal weight at given stiffness and minimal cost at given stiffness. Due to the need for permanent wear, design was motivated by low weight and comfortable head fixation, along with high production efficiency. The selection of minimal tooling in University fabrication workshops and the use of distributed volunteer labor are discussed.

Successful direct route production of silicon nanostructures from diatomaceous earth (DE) on a single crystalline silicon wafer via the magnesiothermic reduction reaction is reported. The formed porous coating of 6 &micro, m overall thickness contains silicon as the majority phase along with minor traces of Mg, as evident from SEM-EDS and the Focused Ion Beam (FIB) analysis. Raman peaks of silicon at 519 cm&minus, 1 and 925 cm&minus, 1 were found in both the film and wafer substrate, and significant intensity variation was observed, consistent with the SEM observation of the directly formed silicon nanoflake layer. Microstructural analysis of the flakes reveals the presence of pores and cavities partially retained from the precursor diatomite powder. A considerable reduction in surface reflectivity was observed for the silicon nanoflakes, from 45% for silicon wafer to below 15%. The results open possibilities for producing nanostructured silicon with a vast range of functionalities.

The use of aluminum alloy AA2024-T4 (Russian designation D16T) in applications requiring a high strength-to-weight ratio and fatigue resistance such as aircraft fuselage often demands the control and modification of surface properties. A promising route to surface conditioning of Al alloys is laser treatment. In the present work, the formation of ripples and conical microstructures under scanning with femtosecond (fs) laser pulses was investigated. Laser treatment was performed using 250 fs pulses of a 1033 nm Yb:YAG laser. The fluence of the pulses varied from 5 to 33 J/cm2. The scanning was repeated from 1 to 5 times for different areas of the sample. Treated areas were evaluated using focused ion beam (FIB)- scanning electron microscopy (SEM) imaging and sectioning, energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), and confocal laser profilometry. The period of laser-induced periodic surface structures (LIPSS) and the average spacing of conical microstructures were deduced from SEM images by FFT. Unevenness of the treated areas was observed that is likely to have been caused by ablation debris. The structural and elemental changes of the material inside the conical microstructures was revealed by FIB-SEM and EDX. The underlying formation mechanisms of observed structures are discussed in this paper.

Deformation analysis in engineering materials and components is a subject of ongoing enquiry due to its importance for obtaining reliable prediction of strength and durability of structures and assemblies. Whilst optical methods deliver information about surface displacements, X-ray scattering methods have the capability to provide efficient assessment of crystal lattice distortion in the bulk of the component. The height digital image correlation (hDIC) technique is an alternative to conventional digital image correlation that uses the out-of-plane surface height variations for the identification of triaxial deformations. In this study, the hDIC technique was used for the determination of displacements in an aluminium specimen after 3-point bending process that creates a complex deformation state that includes both axial displacements and rotations. The surface of the specimen was prepared for the analysis by electric discharge machining (EDM) technique that has minimal effect on material properties and produces random height profile well-suited for the aim of this study. Surface height variations were measured using deep focus microscopy and used instead of pixel intensity for correlation in the DIC process. The distribution of total of elastic and plastic strains were also calculated by the evolutionary eigenstrain model using 2D X-ray diffraction patterns processed according to the polar transformation method. The agreement between hDIC and polar X-Ray diffraction analyses allowed reliable cross-validation between these two techniques.

A layered hybrid implant was designed and fabricated for the surgical replacement of worn cartilage to meet the complex requirements of biocompatibility and mechanics. The natural hierarchical structure was purposefully mimicked to improve the implant performance and integration. The hybrid was fabricated using three components: processed collagen gel, hydroxyapatite (HAp) powder and ultra-high molecular weight polyethylene (UHMWPE) in bulk and sponge form. The fabrication included hot molding, sacrificial templating, infusion, and freeze-casting stages. The hybrid had a porous transition layer made of porous UHMWPE impregnated with collagen by means of infusion. SEM and FTIR analyses confirmed successful collagen impregnation of porous UHMWPE. The morphology of transition layer was selected and produced to provide the UHMWPE pore size distribution in a range ∼50–150 μm that is favorable for the osseointegration by osteoblast proliferation. Biocompatibility tests were carried out in vitro. The index of red blood cells hemolysis showed 0.6 % after 4 h of co-incubation that proved excellent biocompatibility of the fabricated UHMWPE-Collagen-HAp hybrid.

COVID-19 pandemic provoked a number of restrictive measures, such as the closure or severe restriction of border transit for international trading traffic, quarantines and self-isolation. This caused a series of interrelated consequences that not only prevent or slow down the spread of disease, but also impact the medical systems&rsquo, capability to treat the patients and help their recovery. In particular, steeply growing demand for medical safety goods cannot be satisfied by regular suppliers due to the shortage of raw materials originating from other countries or remotely located national sources, under conditions of quarantined manpower. The current context inevitably brings back memories (and records!) of the situation 80 years ago, when WWII necessitated major effort directed at the rapid build-up of low-cost mass production to satisfy all aspects of war-time need. In the present short report we document a successful case of fast mass-production of light transparent medical safety face shields (thousands per day) realized in Skolkovo Institute of Science and Technology (Skoltech) at Fablab and Machine Shop Shared Facility (Skoltech FabLab). The demand for safety face shields by tens of hospitals in Moscow and other cities rapidly ramped up due to the need to protect medical staff during patient collection and transportation to hospitals, and within both the infected (&ldquo, red&rdquo, ) and uninfected (&ldquo, green&rdquo, ) zones. Materials selection for sterilizable transparent materials was conducted based on the analysis of merit indices, namely, minimal weight at given stiffness and minimal cost at given stiffness. Due to the need for permanent wear, design was motivated by low weight and comfortable head fixation, along with high production efficiency. The selection of minimal tooling in University fabrication workshops and the use of distributed volunteer labor are discussed.