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Some mollusc shells are formed from an amorphous calcium carbonate (ACC) compound, which further transforms into a crystalline material. The transformation mechanism is not fully understood but is however crucial to develop bioinspired synthetic biomineralization strategies or accurate marine biomineral proxies for geoscience. The difficulty arises from the simultaneous presence of crystalline and amorphous compounds in the shell, which complicates the selective experimental characterization of the amorphous fraction. Here, we use nanobeam X-ray total scattering together with an approach to separate crystalline and amorphous scattering contributions to obtain the spatially resolved atomic pair distribution function (PDF). We resolve three distinct amorphous calcium carbonate compounds, present in the shell of

Biomineralization integrates complex physical and chemical processes bio-controlled by the living organisms through ionic concentration regulation and organic molecules production. It allows tuning the structural, optical and mechanical properties of hard tissues during ambient-condition crystallisation, motivating a deeper understanding of the underlying processes. By combining state-of-the-art optical and X-ray microscopy methods, we investigated early-mineralized calcareous units from two bivalve species, Pinctada margaritifera and Pinna nobilis, revealing chemical and crystallographic structural insights. In these calcite units, we observed ring-like structural features correlated with a lack of calcite and an increase of amorphous calcium carbonate and proteins contents. The rings also correspond to a larger crystalline disorder and a larger strain level. Based on these observations, we propose a temporal biomineralization cycle, initiated by the production of an amorphous precursor layer, which further crystallizes with a transition front progressing radially from the unit centre, while the organics are expelled towards the prism edge. Simultaneously, along the shell thickness, the growth occurs following a layer-by-layer mode. These findings open biomimetic perspectives for the design of refined crystalline materials. STATEMENT OF SIGNIFICANCE: Calcareous biominerals are amongst the most present forms of biominerals. They exhibit astonishing structural, optical and mechanical properties while being formed at ambient synthesis conditions from ubiquitous ions, motivating the deep understanding of biomineralization. Here, we unveil the first formation steps involved in the biomineralization cycle of prismatic units of two bivalve species by applying a new multi-modal non-destructive characterization approach, sensitive to chemical and crystalline properties. The observations of structural features in mineralized units of different ages allowed the derivation of a temporal sequence for prism biomineralization, involving an amorphous precursor, a radial crystallisation front and a layer-by-layer sequence. Beyond these chemical and physical findings, the herein introduced multi-modal approach is highly relevant to other biominerals and bio-inspired studies. ispartof: ACTA BIOMATERIALIA vol:142 pages:194-207 ispartof: location:England status: published

International audience; In living organisms, calcium carbonate biomineralization combines complex bio-controlled physical and chemical processes to produce crystalline hierarchical hard tissues (usually calcite or aragonite) typically from an amorphous precursor phase. Understanding the nature of the successive transient amorphous phases potentially involved in the amorphous-to-crystalline transition requires characterization tools, which are able to provide a spatial and spectroscopic analysis of the biomineral structure. In this work, we present a highly sensitive coherent Raman microscopy approach, which allows one to image molecular bond concentrations in post mortem shells and living animals, by exploiting the vibrational signature of the different carbonates compounds. To this end, we target the nu_1 calcium carbonate vibration mode and produce spatially and spectroscopically resolved images of the shell border of a mollusk shell, the Pinctada margaritifera pearl oyster. A novel approach is further presented to efficiently compare the amount of amorphous carbonate with respect to its crystalline counterpart. Finally, the whole microscopy method is used to image in vivo the shell border and demonstrate the feasibility and the reproducibility of the technique. These findings open chemical imaging perspectives for the study of biogenic and bio-inspired crystals.

Diffusion tensor imaging (DTI) has demonstrated the potential to assess the pathophysiology of mild traumatic brain injury (mTBI) but correlations of DTI findings and pathological changes in mTBI are unclear. We evaluated the potential of ex vivo DTI to detect tissue damage in a mild mTBI rat model by exploiting multiscale imaging methods, histology and scanning micro-X-ray diffraction (SμXRD) 35 days after sham-operation (n = 2) or mTBI (n = 3). There were changes in DTI parameters rostral to the injury site. When examined by histology and SμXRD, there was evidence of axonal damage, reduced myelin density, gliosis, and ultrastructural alterations in myelin that were ongoing at the experimental time point of 35 days postinjury. We assessed the relationship between the 3 imaging modalities by multiple linear regression analysis. In this analysis, DTI and histological parameters were moderately related, whereas SμXRD parameters correlated weakly with DTI and histology. These findings suggest that while DTI appears to distinguish tissue changes at the microstructural level related to the loss of myelinated axons and gliosis, its ability to visualize alterations in myelin ultrastructure is limited. The use of several imaging techniques represents a novel approach to reveal tissue damage and provides new insights into mTBI detection.

Some mollusc shells are formed from an amorphous calcium carbonate (ACC) compound, which further transforms into a crystalline material. The transformation mechanism is not fully understood but is however crucial to develop bioinspired synthetic biomineralization strategies or accurate marine biomineral proxies for geoscience. The difficulty arises from the simultaneous presence of crystalline and amorphous compounds in the shell, which complicates the selective experimental characterization of the amorphous fraction. Here, we use nanobeam X-ray total scattering together with an approach to separate crystalline and amorphous scattering contributions to obtain the spatially resolved atomic pair distribution function (PDF). We resolve three distinct amorphous calcium carbonate compounds, present in the shell of Pinctada margaritifera and attributed to: interprismatic periostracum, young mineralizing units, and mature mineralizing units. From this, we extract accurate bond parameters by reverse Monte Carlo (RMC) modeling of the PDF. This shows that the three amorphous compounds differ mostly in their Ca–O nearest-neighbor atom pair distance. Further characterization with conventional spectroscopic techniques unveils the presence of Mg in the shell and shows Mg–calcite in the final, crystallized shell. In line with recent literature, we propose that the amorphous-to-crystal transition is mediated by the presence of Mg. The transition occurs through the decomposition of the initial Mg-rich precursor into a second Mg-poor ACC compound before forming a crystal.

Osteosarcoma is the most common primary bone cancer type in humans. It is predominantly found in young individuals, with a second peak later in life. The tumour is formed by malignant osteoblasts and consists of collagenous, sometimes also mineralized, bone matrix. While the morphology of osteosarcoma has been well studied, there is virtually no information about the nanostructure of the tumour and changes in mineralization on the nanoscale level. In the present paper, human bone tissue inside, next to and remote from a sclerosing osteosarcoma was studied with small angle x-ray scattering, x-ray diffraction and electron microscopy. Quantitative evaluation of nanostructure parameters was combined with high resolution, large area mapping to obtain microscopic images with nanostructure parameter contrast. It was found that the tumour regions were characterized by a notable reduction in mineral particle size, while the mineral content was even higher than that in normal bone. Furthermore, the normal preferential orientation of mineral particles along the longitudinal direction of corticalis or trabeculae was largely suppressed. Also the bone mineral crystal structure was affected: severe crystal lattice distortions were detected in mineralized tumour tissue pointing to a different ion substitution of hydroxyl apatite in tumorous tissue than in healthy tissue.

A simple route for the in-situ orientation of carbon nanofillers applied during the curing process of a carbon fiber reinforced polymer (CRFP) in a hot press, is demonstrated. Neat MWCNT, amine-functionalized MWCNT (MWCNT-NH2) and CNF were dispersed in an epoxy resin using a three-roll-mill (TRM) to ensure good dispersion. The process leads to a hierarchically structured functional composite where MWCNT/CNF are aligned in the z-direction (out-of-plane) of the carbon fiber plies, giving rise to improved mechanical and electrical performance. Our results demonstrate that aligned carbon nanofillers yield significantly more pronounced improvements than non-oriented fillers. An applicable processing route towards advanced functional composite materials with major practical importance is presented in this study.

The nanostructural adaptation of bone is crucial for its biocompatibility with orthopedic implants. The bone nanostructure also determines its mechanical properties and performance. However, the bone's temporal and spatial nanoadaptation around degrading implants remains largely unknown. Here, we present insights into this important bone adaptation by applying scanning electron microscopy, elemental analysis, and small-angle X-ray scattering tensor tomography (SASTT). We extend the novel SASTT reconstruction method and provide a 3D scattering reciprocal space map per voxel of the sample's volume. From this reconstruction, parameters such as the thickness of the bone mineral particles are quantified, which provide additional information on nanostructural adaptation of bone during healing. We selected a rat femoral bone and a degrading ZX10 magnesium implant as model system, and investigated it over the course of 18 months, using a sham as control. We observe that the bone's nanostructural adaptation starts with an initially fast interfacial bone growth close to the implant, which spreads by a re-orientation of the nanostructure in the bone volume around the implant, and is consolidated in the later degradation stages. These observations reveal the complex bulk bone-implant interactions and enable future research on the related biomechanical bone responses. Statement of significance Traumatic bone injuries are among the most frequent causes of surgical treatment, and often require the placement of an implant. The ideal implant supports and induces bone formation, while being mechanically and chemically adapted to the bone structure, ensuring a gradual load transfer. While magnesium implants fulfill these requirements, the nanostructural changes during bone healing and implant degradation remain not completely elucidated. Here, we unveil these processes in rat femoral bones with ZX10 magnesium implants and show different stages of bone healing in such a model system., Acta Biomaterialia, 134, ISSN:1742-7061, ISSN:1878-7568

Long bone mineralization occurs through endochondral ossification, where a cartilage template mineralizes into bone‐like tissue with a hierarchical organization from the whole bone‐scale down to sub‐nano scale. Whereas this process has been extensively studied at the larger length scales, it remains unexplored at some of the smaller length scales. In this study, the changes in morphology, composition, and structure during embryonic mineralization of murine humeri are investigated using a range of high‐resolution synchrotron‐based imaging techniques at several length scales. With micro‐ and nanometer spatial resolution, the deposition of elements and the shaping of mineral platelets are followed. Rapid mineralization of the humeri occurs over approximately four days, where mineral to matrix ratio and calcium content in the most mineralized zone reach adult values shortly before birth. Interestingly, zinc is consistently found to be localized at the sites of ongoing new mineralization. The mineral platelets in the most recently mineralized regions are thicker, longer, narrower, and less aligned compared to those further into the mineralized region. In summary, this study demonstrates a specific spatial distribution of zinc, with highest concentration where new mineral is being deposited and that the newly formed mineral platelets undergo slight reshaping and reorganization during embryonic development., Long bones are largely formed through endochondral ossification, where a cartilage template gradually mineralizes into a bone‐like tissue. However, the characteristics of this mineralization process at the smaller length scales remain unclear. Using a range of high‐resolution synchrotron‐based techniques, distribution of molecular and elemental content, as well as reshaping and reorganization of mineral platelets are visualized.

Guanine in the anhydrous β-form is a common light manipulator in organisms to produce structural colors for a variety of purposes. The level of control over crystal nucleation and growth of guanine exhibited by these organisms to produce crystals with precise morphology, size, and polymorphism far surpasses what has so far been achieved synthetically from aqueous solution. Here, we show that the morphology of guanine crystals can be altered significantly by inducing crystallization at the air-water interface to produce vase-like morphologies with a few hundred nanometers thick, micron-longcrystals pointing away from the vase opening. The exact morphology is highly dependent on the initial guanine concentration with increasing templating efficiency from the air-water interface at decreasing sample volumes. Scanning nanobeam X-ray diffraction experiments reveal that the vases consist exclusively of the anhydrous β-polymorph and that the crystal long axes coincide with a*. While the morphology does not match the biogenic counterparts that usually are thin along a*, the results demonstrate that interfacial crystallization templates the aggregate morphology and dictates the polymorph of guanine.

Studying nanostructured hierarchical materials such as the biomineralized bone is challenging due to their complex 3D structures that call for high spatial resolution. One route to study such materials is X-ray powder diffraction computed tomography (XRD-CT) that reveals the 3D distribution of crystalline phases and X-ray fluorescence computed tomography (XRF-CT) that provides element distributions. However, the spatial resolution of XRD-CT has thus far been limited. Here we demonstrate better than 120 nm 3D resolution on human bone in XRD-CT and XRF-CT measured simultaneously using X-ray nanobeams. The results pave the way for nanoscale 3D characterization of nanocrystalline composites like bone at unprecedented detail.

Cyt1Aa is the one of four crystalline protoxins produced by mosquitocidal bacterium Bacillus thuringiensis israelensis (Bti) that has been shown to delay the evolution of insect resistance in the field. Limiting our understanding of Bti efficacy and the path to improved toxicity and spectrum has been ignorance of how Cyt1Aa crystallizes in vivo and of its mechanism of toxicity. Here, we use serial femtosecond crystallography to determine the Cyt1Aa protoxin structure from sub-micron-sized crystals produced in Bti. Structures determined under various pH/redox conditions illuminate the role played by previously uncharacterized disulfide-bridge and domain-swapped interfaces from crystal formation in Bti to dissolution in the larval mosquito midgut. Biochemical, toxicological and biophysical methods enable the deconvolution of key steps in the Cyt1Aa bioactivation cascade. We additionally show that the size, shape, production yield, pH sensitivity and toxicity of Cyt1Aa crystals grown in Bti can be controlled by single atom substitution., Bacillus thuringiensis israelensis (Bti) produces the naturally-crystalline proteinaceous toxin Cyt1Aa that is toxic to mosquito larvae. Here the authors grow recombinant nanocrystals of the Cyt1Aa protoxin in vivo and use serial femtosecond crystallography to determine its structure at different redox and pH conditions and by combining their structural data with further biochemical, toxicological and biophysical analyses provide mechanistic insights into the Cyt1Aa bioactivation cascade.

Semiconductor quantum dots (QDs) are widely used for optical applications and bioimaging. In comparison to organic dyes used for fluorescent labeling, QDs exhibit very high photostability and can be further surface modified. Equipping QDs with magnetic properties (mQDs) makes it possible to combine fluorescence and magnetic resonance imaging analyses. For this purpose, we have prepared water-dispersible and magnetic CdTe/ZnS mQDs, whereby ferrous ions are selectively incorporated in either their cores or their shells. This study aims at understanding the differences in optical, structural, and magnetic properties between these core- and shell-doped mQDs. Field-dependent isothermal magnetic susceptibility measurements show that shell-doped mQDs exhibit paramagnetic and their core-doped equivalents superparamagnetic behavior near room temperature. Shell doping results in about 1.7 times higher photoluminescence quantum yields and 1.4 times higher doping efficiency than core doping. X-ray diffraction pattern...

The synthesis of iron oxide nanoparticles (NPs) by thermal decomposition of iron precursors using oleic acid as surfactant has evolved to a state-of-the-art method to produce monodisperse, spherical NPs. The principles behind such monodisperse syntheses are well-known: the key is a separation between burst nucleation and growth phase, whereas the size of the population is set by the precursor-to-surfactant ratio. Here we follow the thermal decomposition of iron pentacarbonyl in the presence of oleic acid via in situ X-ray scattering. This method allows reaction kinetics and precursor states to be followed with high time resolution and statistical significance. Our investigation demonstrates that the final particle size is directly related to a phase of inorganic cluster formation that takes place between precursor decomposition and particle nucleation. The size and concentration of clusters were shown to be dependent on precursor-to-surfactant ratio and heating rate, which in turn led to differences in the onset of nucleation and concentration of nuclei after the burst nucleation phase. This first direct observation of prenucleation formation of inorganic and micellar structures in iron oxide nanoparticle synthesis by thermal decomposition likely has implications for synthesis of other NPs by similar routes.

In this work we use scanning X-ray microscopy to study the structure and elemental composition of neuromelanin-positive neurons in substantia nigra tissue of Parkinson patients (PD) and controls. A total of 53 neurons were analyzed with X-ray fluorescence (XRF) and diffraction using sub-µm-focused synchrotron radiation. A statistical evaluation identified copper as the most group-discriminating element and indicated that interindividual and intraindividual variations are of great relevance in tissue measurements of diseased patients and prevent from automated group clustering. XRF analyses of two Lewy bodies (LBs) highlight a heterogeneity in elemental distributions in these LBs, whereas an innovative X-ray diffraction-based method approach was used to reveal β-sheet-rich crystalline structures in LBs. Overall, sub-µm-focus X-ray microscopy highlighted the elemental heterogeneity in PD pathology.

This work showcases a method to map the full deformation tensor in a single micro-sized crystal. It is shown that measuring the position of two Bragg reflections in reciprocal space is sufficient to obtain the full deformation tensor, if the condition of incompressibility of the material is imposed. This method is used to reveal the surface tension induced deformation at the edges of an as-grown single-crystal VO2 microwire. All components of the deformation tensor of the microwire were measured down to an absolute value of 10−4 in an 8 × 14 µm projected area of the wire. With a beam-defined spatial resolution of 150 × 150 nm, the measurement time was merely 2.5 h.

Composite materials, both biominerals such as bone or shells but also increasingly synthetic materials, often have a complex hierarchical 3D structure ranging over several length scales. To fully understand the structure of such materials, a method for probing the nanoscale structure in 3D is needed. Materials such as bone are particularly challenging due to their complex composition and hierarchical structure. Recent developments in synchrotron x-ray focusing optics have paved the way for smaller x-ray beams with high brilliance. Herein, we present how we probe the 3D elemental distribution and crystallographic properties of human bone using combined fluorescence and diffraction tomography (F-CT and XRD-CT) with a 50 nm pencil X-ray beam. The 2.6×3.1 µm2 cross section sample was a FIB-cut rod of human iliac crest bone. We recorded 2D diffraction patterns and fluorescence spectra for each point in a 50 nm raster scan grid pattern from 92 projection angles covering 0-182°. This allowed us to reconstruct tomographically both x-ray diffraction patterns and the elemental composition in a ∼5×5×3 µm3 volume encompassing the sample. We show that tomographic reconstruction of x-ray diffraction and fluorescence information is possible at

Die herkommliche Bestimmung der Kristallvorzugsorientierung (kristallographische Textur) beruht auf Rontgenbeugung mit Flachendetektoren und 2D-Daten. Echte, ortsaufgeloste 3D-Informationen erfordern eine Probendrehung im Strahl. Dabei wird das beleuchtete Volumen standig verandert und das Streusignal verschmiert, was die Bestimmung komplexer Strukturen verhindert. Diese Einschrankung lasst sich mit energieauflosender Laue-Beugung umgehen. Es wurde eine Methode entwickelt, um einen grosen Teil des reziproken Raums abzudecken und aus der Energie der Rontgenphotonen die dritte Raumdimension zu errechnen. Das Verfahren wurde auf Kohlenstofffasern und Hummerpanzer, als Beispiel fur biomineralisiertes Gewebe, angewendet. Das besondere Potenzial dieser Methode liegt darin, dass sie nur eine einzige Messung erfordert, sowie am direkten Erfassen von 3D-Informationen ohne Vorwissen uber die Probe. Das Verfahren ermoglicht daher das Abrastern groser Proben mit komplexer Struktur und eroffnet die konzeptuelle Moglichkeit, Texturanderungen in situ zu verfolgen, z. B. wahrend Kristallisationsvorgangen.

Biocompatibility is a key issue in the development of new implant materials. In this context, a novel class of biodegrading Mg implants exhibits promising properties with regard to inflammatory response and mechanical properties. The interaction between Mg degradation products and the nanoscale structure and mineralization of bone, however, is not yet sufficiently understood. Investigations by synchrotron microbeam x-ray fluorescence (μXRF), small angle x-ray scattering (μSAXS) and x-ray diffraction (μXRD) have shown the impact of degradation speed on the sites of Mg accumulation in the bone, which are around blood vessels, lacunae and the bone marrow. Only at the highest degradation rates was Mg found at the implant-bone interface. The Mg inclusion into the bone matrix appeared to be non-permanent as the Mg-level decreased after completed implant degradation. μSAXS and μXRD showed that Mg influences the hydroxyl apatite (HAP) crystallite structure, because markedly shorter and thinner HAP crystallites were found in zones of high Mg concentration. These zones also exhibited a contraction of the HAP lattice and lower crystalline order.

The promising applications of core-shell nanoparticles in the biological and medical field have been well investigated in recent years. One remaining challenge is the characterization of the structure of the hydrated polymer shell. Here we use small-angle X-ray scattering (SAXS) to investigate iron oxide core-poly(ethylene glycol) brush shell nanoparticles with extremely high polymer grafting density. It is shown that the shell density profile can be described by a scaling model that takes into account the locally very high grafting density near the core. A good fit to a constant density region followed by a star-polymer-like, monotonously decaying density profile is shown, which could help explain the unique colloidal properties of such densely grafted core-shell nanoparticles. SAXS experiments probing the thermally induced dehydration of the shell and the response to dilution confirmed that the observed features are associated with the brush and not attributed to structure factors from particle aggregates. We thereby demonstrate that the structure of monodisperse core-shell nanoparticles with dense solvated shells can be well studied with SAXS and that different density models can be distinguished from each other. (Graph Presented).

This study deals with the influence of various electron beam irradiation (EBI) dosages on the Brinell hardness of Norway spruce. The results of the hardness measurements and the FT-IR spectroscopic analysis show different effects of the EBI at dosages of 25, 50, 100 and 200 kGy. It was assumed that the lignin and carbohydrates undergo different altering mechanisms due to the EBI treatment. New cleavage products and condensation reactions of lignin and carbohydrates lead to better surface hardness of low irradiated wood samples. These results provide a useful basis for further investigations on the changes in wood chemistry and material properties due to electron beam irradiations.

3D mapping of crystal and nanostructure orientation shows that bone contains a mineral fraction not aligned with the nanostructure., Bone is built from collagen fibrils and biomineral nanoparticles. In humans, they are organized in lamellar twisting patterns on the microscale. It has been a central tenet that the biomineral nanoparticles are co-aligned with the bone nanostructure. Here, we reconstruct the three-dimensional orientation in human lamellar bone of both the nanoscale features and the biomineral crystal lattice from small-angle x-ray scattering and wide-angle x-ray scattering, respectively. While most of the investigated regions show well-aligned nanostructure and crystal structure, consistent with current bone models, we report a localized difference in orientation distribution between the nanostructure and the biomineral crystals in specific bands. Our results show a robust and systematic, but localized, variation in the alignment of the two signals, which can be interpreted as either an additional mineral fraction in bone, a preferentially aligned extrafibrillar fraction, or the result of transverse stacking of mineral particles over several fibrils.

Conventional analysis of the preferred orientation of crystallites (crystallographic texture) involves X-ray diffraction with area detectors and 2D data output. True 3D, spatially resolved information requires sample rotation in the beam, thus changing the probed volume, which introduces signal smearing and precludes the scanning of complex structures. This obstacle has been overcome by energy-dispersive Laue diffraction. A method has been devised to reach a large portion of reciprocal space and translate the X-ray photon energy into the missing third dimension of space. Carbon fibers and lobster exoskeleton as examples of biomineralized tissue have been analyzed. The major potential of this method lies in its "one-shot" nature and the direct 3D information requiring no previous knowledge of the sample. It allows the texture of large samples with complex substructures to be scanned and opens up the conceptual possibility of following texture changes in situ, for example, during crystallization.

This study investigated the distribution of the elemental constituents of Mg-based implants at various stages of the degradation process in surrounding bone tissue, with a focus on magnesium (Mg), as the main component of the alloy, and yttrium (Y), due to its potential adverse health effects. The measurements were performed on the implant-bearing thin sections of rat bone in a time series of implant degradation between one and 18 months. Micro X-ray fluorescence analysis (μXRF) with a special spectrometer meeting the requirements for the measurements of low-Z elements was used. It was found that the migration and accumulation behaviour of implant degradation products is element-specific. A sharp decrease in Mg was observed in the immediate vicinity of the interface and no specific accumulation or aggregation of Mg in the adjacent bone tissue was detected. By contrast, Y was found to migrate further into the bone over time and to remain in the tissue even after the complete degradation of the implant. Although the nature of Y accumulations must still be clarified, its potential health impact should be considered., Materials, 9 (10), ISSN:1996-1944

Understanding the implant–bone interaction is of prime interest for the development of novel biodegrading implants. Magnesium is a very promising material in the class of biodegrading metallic implants, owing to its mechanical properties and excellent immunologic response during healing. However, the influence of degrading Mg implants on the bone nanostructure is still an open question of crucial importance for the design of novel Mg implant alloys. This study investigates the changes in the nanostructure of bone following the application of a degrading WZ21 Mg implant (2 wt% Y, 1 wt% Zn, 0.25 wt% Ca and 0.15 wt% Mn) in a murine model system over the course of 15 months by small angle X-ray scattering. Our investigations showed a direct response of the bone nanostructure after as little as 1 month with a realignment of nano-sized bone mineral platelets along the bone–implant interface. The growth of new bone tissue after implant resorption is characterized by zones of lower mineral platelet thickness and slightly decreased order in the stacking of the platelets. The preferential orientation of the mineral platelets strongly deviates from the normal orientation along the shaft and still roughly follows the implant direction after 15 months. We explain our findings by considering geometrical, mechanical and chemical factors during the process of implant resorption. Statement of significance The advancement of surgical techniques and the increased life expectancy have caused a growing demand for improved bone implants. Ideally, they should be bio-resorbable, support bone as long as necessary and then be replaced by healthy bone tissue. Magnesium is a promising candidate for this purpose. Various studies have demonstrated its excellent mechanical performance, degradation behaviour and immunologic properties. The structural response of bone, however, is not well known. On the nanometer scale, the arrangement of collagen fibers and calcium mineral platelets is an important indicator of structural integrity. The present study provides insight into nanostructural changes in rat bone at different times after implant placement and different implant degradation states. The results are useful for further improved magnesium alloys.

Intelligent resource usage is one of the most challenging tasks for the wood-based panels industry. With respect to this issue, leather shavings, derived during leather preparation, are a promising new raw material, as they offer not only high availability, but also potentially enhance material properties such as panel fire retardancy. In order to improve the performance of these emerging panel binder materials, an understanding of chemical interactions between the different constituents is crucial. This paper investigates the chemical changes that occur during hot-pressing of wood and leather in combination with lignin by means of solid state 13C NMR spectroscopy. These constituents, their binary mixtures, and the influences of panel pressing temperature and pressure commonly used in panel production were investigated. The study showed characteristic chemistry and features of these constituents, quantifying the impacts of both heat and pressure on their interactions. Primarily, analysis revealed that lignin readily connects with both the wood and leather components. Lignin induces chemical change within the protein structure of leather, resembling tanning reactions, or protein complexation. By analogy, it was deduced that this interaction also takes place between leather and the lignin-rich wood fibre surface. This effect may be beneficial in industrial-scale production through improving resin binding properties during panel consolidation.

Besides other ligno-cellulosic materials such as straw, rice husks, or bagasse, wet blue particles from leather production are a promising new raw material stock for wood-based panels, as they offer not only a high availability, but increase the properties of the panel with regard to fire resistance or mechanical characteristics. A panel with a mixture of 42.5% wood fibers, 42.5% wet blue leather particles, and 15% lignin adhesive was produced, and an inhomogeneous sample was prepared. An area of 9 x 10 mm was rasterized and scanned by means of Raman Spectroscopy. Furthermore, the reference spectra of the constituents, i.e. wood fiber, wet blue leather particle, and lignin powder were recorded. The obtained data were treated and analyzed using chemometric methods (principal components analysis PCA and cluster analysis). An important finding was that the reference data were not directly represented in the panels’ spectra, and the correlation matrix of the PCA was not applicable to the panel data. This indicated that chemical changes might take place during the pressing. After processing the panel Raman spectra with the help of PCA and cluster analysis, three distinctive clusters were obtained, discriminating wood, leather, and mixed regions. With the assigned spectral information, it was possible to create a spectral image of the surface.

Wet-white and wet-blue leather shavings were investigated as promising new raw materials as they seem to offer a high availability and cost competitiveness compared to wood, and they also show some interesting new properties. In order to determine a new field of application for the leather shavings and to understand the fiber particle interaction, boards with a density of 700 kg/m³ and a resin load of 12% were produced with varying contents of wood fibers, wet-blue and wet-white leather particles. These panel composites were characterized with regard to their internal bond, modulus of elasticity, and modulus of rupture. Furthermore, the micro-structure of selected panels was investigated by X-Ray computed tomography (CT). Different phases within the CT data were segmented using thresholding algorithms, and the pore size distribution of the panels was analyzed. A substantial difference was found between the panels produced due to the incorporation of leather particles. The internal bond strength increased with rising leather particle content, whereas other mechanical properties dropped. The CT analysis showed a huge difference in the pore size distribution and the number of pores for the different materials. This indicates that the differences visible in mechanical testing were induced by the different geometry of the constituents.