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Abstract: Fats are essential ingredients widely used in the food industry, as well as in cosmetic and pharmaceutical formulations. Solid fats are complex multicomponent systems primarily composed of triacylglycerols (TAGs), which determine the types and properties of the crystalline structures formed. TAGs crystallize in different polymorphs and stacking configurations, with distinct thermal and mechanical properties that influence the macroscopic structure and sensory profile of fat-based products. In this study, a comprehensive multi-technique analysis of animal-derived fats, specifically chicken and beef fats, was conducted. Chemical characterization was performed and solid fat content (SFC) was determined. Thermal behaviour was investigated using differential scanning calorimetry (DSC), whereas crystallization experiments were conducted using in situ turbidity measurements and synchrotron small-angle and wide-angle x-ray scattering (SAXS/WAXS) for structural characterization. Three different synchrotron experimental setups were used for crystallization experiments, including static and sheared conditions. The results demonstrate that the crystallization behaviour of beef and chicken fat samples closely correlate with their TAGs composition. Synchrotron x-ray scattering provided structural insights, highlighting how the polymorphic behaviour is influenced by fat origin and crystallization conditions. For both animal fat types, all three main polymorphs and possible transitions were detected. Moreover, the presence of shear promoted crystallization of stable polymorphs.

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Abstract: Slow skeletal muscles maintain posture and produce graded movement at low metabolic cost. ATP utilization during fixed-end contractions is typically five times slower in slow muscles than in fast muscles from the same species. Mechanical measurements previously suggested that more myosin motors are attached to thin filaments during contraction of slow muscle, which seems incompatible with its high efficiency. We therefore used small-angle X-ray diffraction to provide a structural estimate of the fraction of myosin motors attached to thin filaments in slow muscle. The X-ray signals associated with myosin binding to actin indicate that only ∼10% of myosin motors are actin bound during fixed-end tetani of rat soleus slow muscles, compared with ∼25% in mouse extensor digitorum longus fast muscle. Moreover, X-ray signals associated with the helical organization of OFF myosin motors in the thick filaments show that ∼70% of myosin motors remain in the OFF conformation during tetanic contraction of rat soleus muscle, compared with only 30% in mouse extensor digitorum longus muscle. The much slower force development in soleus muscle also allowed clear separation of early structural changes in thick filaments on activation, some of which are distinct from those reported previously in fast muscles. Moreover, the early structural changes in soleus muscle have about the same amplitude in a twitch and a tetanus, suggesting that they are triggered by thin filament activation rather than thick filament stress and implying a fast signalling pathway between thin and thick filaments.

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Abstract: Dental caries, one of the most prevalent non-communicable diseases worldwide, is characterised by the progressive deterioration of the structure and mechanical properties of dental hard tissues. In human teeth, dentine is the most abundant mineralised tissue, forming the primary support material. To assess changes in the mechanical properties of dentine caused by dental caries and acid erosion, it is crucial to understand the relationship between organic and inorganic dentine components and their organisation into a 3D anisotropic structure at the nanoscale. Over the past 20 years, alterations in dentine structure caused by caries and artificial demineralisation have been reported using conventional microscopy techniques. However, due to the limited spatial resolution of these techniques, the 3D structural organisation including orientation and degree of alignment of mineralised collagen fibrils at the nanoscale, has not been fully explored. This study investigated alterations in the 3D structure of normal, carious and artificially demineralised dentine using SAXS tensor tomography (SASTT). This technique enabled the observation of differences in the local orientation of organic and inorganic components, as well as variations in local scattering intensity, resulting from natural caries and artificial demineralisation. In comparison to normal dentine, caries caused minor orientational differences of both components but had a major impact on the local X-ray scattering intensity. After artificial demineralisation of the dentine, most of the mineral was lost in the outer layers, resulting in a greater reduction in scattering intensity than that caused by caries.

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Abstract: Benchtop ultra-small-angle X-ray scattering (USAXS) offers a practical route to probing micron-scale structural features in soft-matter systems, provided that instrumental limitations are explicitly defined and respected. In this work, a Rigaku NANOPIX mini USAXS instrument is used to characterize hierarchical fat crystal networks, with emphasis on establishing a reliable analysis window and appropriate treatment of slit-geometry effects. Analyzer crystal rocking curves are employed to define a lower bound for quantitative analysis (qmin ≈ 3.4 × 10−4 Å−1), while counting-statistics considerations define an upper bound (qmax ≈ 1.4 × 10−2 Å−1). Data outside this window are shown to be strongly influenced by direct-beam and noise artifacts and are therefore excluded from interpretation. Within the valid q-range, slit-smearing effects inherent to Bonse–Hart geometries are addressed by smearing structural models using open-source SASView software rather than numerically desmearing experimental data. Using cocoa butter, commercial chocolate, and a reference triglyceride mixture as representative case studies, power-law scattering regimes are extracted and compared with synchrotron SAXS measurements over overlapping q-ranges. While absolute slope values vary between instruments and samples, benchtop USAXS captures consistent scattering trends, including stable power-law behavior in tempered systems and transient curvature in untempered samples that diminishes upon storage. These results demonstrate that benchtop USAXS, when interpreted within a rigorously defined q-window and with appropriate resolution treatment, provides a reproducible and accessible tool for comparative analysis of hierarchical fat systems. More broadly, this study outlines best practices and interpretive boundaries for laboratory-scale USAXS measurements in soft-matter research.

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Abstract: Structural biomarkers determined by X-ray scattering of the tissues can complement conventional histopathology and facilitate a fast triage procedure of cancer biopsy samples. It has been shown previously that lipid reflexes can distinguish cancerous from benign samples, except for fibroadenomas. In the present study, we demonstrate that fibroadenoma samples can be recognized using X-ray scattering of collagen. Moreover, we show that modifications in collagen structure are manifested in the water reflexes. Examination of diffraction patterns from water using two-dimensional Fourier transformation and machine learning yields excellent classification metrics in both synchrotron images and laboratory diffractometer data.