Synchrotron Radiation Micro-computed Tomography Research Articles

Increased AGE Cross-Linking Reduces the Mechanical Properties of Osteons

AbstractThe osteon is the primary structural component of bone, contributing significantly to its unique toughness and strength. Despite extensive research on osteonal structure, the properties of osteons have not been fully investigated, particularly within the context of bone fragility diseases like type 2 diabetes mellitus (T2DM). This study aims to isolate osteons from bovine bone, simulate the effects of increased advanced glycation end-products (AGEs) in T2DM through ribosylation, and evaluate the mechanical properties of isolated osteons. Osteons extracted from the posterior section of bovine femur mid-diaphysis were processed to achieve a sub-millimeter scale for microscale imaging. Subsequently, synchrotron radiation micro-computed tomography was employed to precisely localize and isolate the osteon internally. While comparable elastic properties were observed between control and ribosylated osteons, the presence of AGEs led to decreased strain to failure. Young’s modulus was quantified (9.9 ± 4.9 GPa and 8.7 ± 3 GPa, respectively), aligning closely with existing literature. This study presents a novel method for the extraction and isolation of osteons from bone and shows the detrimental effect of AGEs at the osteonal level.

Investigating dialysis membrane surface charge and hydrophobicity effects on fibrinogen adsorption using synchrotron radiation micro-computed tomography (SR-CT)

Hemodialysis, a critical treatment for end-stage kidney disease (ESKD), efficiently eliminates toxic metabolic waste from the bloodstream. This study probes the complex interactions among surface charge, wettability, and roughness of Polyethersulfone (PES) membranes and their influence on fibrinogen (FB) adsorption, a key culprit in membrane fouling that compromises the dialysis efficacy. Utilizing non-invasive X-ray synchrotron-based micro-tomography (SR-CT), we analyzed an array of PES membranes—ranging from unmodified to superhydrophobic surfaces achieved via surface hydrophobization or hydrophobic mixed matrix methods, heparin-immobilized versions, zwitterionically coated with sulfobetaine and carboxibetaine, and uremic metabolite-modified membranes, each with intensified coatings. Our findings highlight that superhydrophobic membranes, particularly hydrophobic mixed matrix membrane, significantly repel FB, reducing fouling due to their high contact angle. Additionally, membranes with lower surface charges corresponded with lower protein adsorption, emphasizing the pivotal role of electrostatic interactions. Intriguingly, hydrophobic membranes outperformed their hydrophilic counterparts despite having higher surface roughness, suggesting that peak hemodialysis membrane performance is achieved through a synergistic balance of reduced surface charge and enhanced hydrophobicity. These insights drive home the importance of integrating charge, wettability, and texture considerations in membrane design to foster the next generation of low-fouling, high-performance hemodialysis membranes.

Investigating Dialysis Membrane Surface Charge and Hydrophobicity Effects on Fibrinogen Adsorption Using Synchrotron Radiation Micro-Computed Tomography (SR-CT)

Investigating Dialysis Membrane Surface Charge and Hydrophobicity Effects on Fibrinogen Adsorption Using Synchrotron Radiation Micro-Computed Tomography (SR-CT)

A comparison of deep learning segmentation models for synchrotron radiation based tomograms of biodegradable bone implants

Introduction: Synchrotron radiation micro-computed tomography (SRμCT) has been used as a non-invasive technique to examine the microstructure and tissue integration of biodegradable bone implants. To be able to characterize parameters regarding the disintegration and osseointegration of such materials quantitatively, the three-dimensional (3D) image data provided by SRμCT needs to be processed by means of semantic segmentation. However, accurate image segmentation is challenging using traditional automated techniques. This study investigates the effectiveness of deep learning approaches for semantic segmentation of SRμCT volumes of Mg-based implants in sheep bone ex vivo.Methodology: For this purpose different convolutional neural networks (CNNs), including U-Net, HR-Net, U²-Net, from the TomoSeg framework, the Scaled U-Net framework, and 2D/3D U-Net from the nnU-Net framework were trained and validated. The image data used in this work was part of a previous study where biodegradable screws were surgically implanted in sheep tibiae and imaged using SRμCT after different healing periods. The comparative analysis of CNN models considers their performance in semantic segmentation and subsequent calculation of degradation and osseointegration parameters. The models’ performance is evaluated using the intersection over union (IoU) metric, and their generalization ability is tested on unseen datasets.Results and discussion: This work shows that the 2D nnU-Net achieves better generalization performance, with the degradation layer being the most challenging label to segment for all models.

Superhydrophobic polyether sulfone (PES) dialysis membrane with enhanced hemocompatibility and reduced human serum protein interactions: Ex vivo, in situ synchrotron imaging, experimental, and computational studies

This study aimed to enhance the hemocompatibility of polyethersulfone (PES) membranes by increasing their hydrophobicity. Two methods were used: chemical modification with a hydrophobic substance and creating a micropatterned structure using modified silica nanoparticles (SiO2 NP) in a mixed matrix membrane (MMM). Fibrinogen adsorption was assessed using synchrotron radiation micro-computed tomography (SR-µCT), and surface roughness was analyzed with atomic force microscopy (AFM). Hemocompatibility was evaluated by studying interactions with patients' serum and measuring the release of inflammatory biomarkers (C5a, IL-1α, IL-1β, IL-6, vWF, C5b-9 and PF-4). Differential Scanning Calorimeter (DSC) analysis determined the stability of the membrane hydration layer, and water contact angle (WCA) measurements assessed hydrophobic properties. Fourier-transform infrared spectroscopy (FTIR) and surface charge analysis examined surface stability. Molecular docking analysis showed reduced interaction between hydrophobized PES membranes and fibrinogen and albumin in human serum. SR-µCT analysis revealed 20% less fibrinogen adsorption on hydrophobized PES membrane surfaces. MMM PES membranes exhibited minimal fibrinogen adsorption due to the micropatterned structure. Both hydrophobized PES membranes demonstrated reduced vWF biomarker release (25–28%) compared to unmodified PES, with MMM PES membranes performing best. However, both hydrophobized PES membranes led to a significant increase (150%) in IL-6 upon blood contact, attributed to the reduced hydration layer. MMM PES membranes contained the least strongly bound water (0.2%) and exhibited the highest hydrophobicity (98°). This study highlights the potential of hydrophobized PES membranes and MMM structures for enhancing hemocompatibility, with opportunities for optimizing surface modifications to reduce inflammation responses while maintaining desirable properties.

Quantitative Analysis of Bone, Blood Vessels, and Metastases in Mice Tibiae Using Synchrotron Radiation Micro-Computed Tomography

Bone metastases are one of the most dangerous consequences of breast cancer. Early diagnosis and treatment would slow down the development of the disease and increase the survival rates of patients. Bone micro-vasculature is believed to play a major role in the development of bone metastases. It could be used for both diagnosis and as a therapeutic target. Synchrotron radiation micro-computed tomography (SR-µCT) with a contrast agent of blood vessels has been used to analyze the bone vasculature both in healthy and in metastatic bone. However, few studies have investigated the local features of blood vessels around metastases so far. For this purpose, the metastases first need to be automatically segmented. This is a challenging task, however, since the metastases do not contribute a specific contrast to the three-dimensional (3D) SR-µCT images. Here, we propose a new method for the simultaneous segmentation of bone, blood vessels, and metastases from contrast enhanced 3D SR-µCT images based on the nnU-Net architecture. In this study, we showed that only minimal training data was required to achieve a high quality of segmentation. The proposed method allowed for the automatic segmentation of metastases and provided an improved segmentation of bone and blood vessels compared to previous methods while being much more efficient to apply once trained. Further, the automatic segmentation allowed for the measurement of vascular metastases interdistance and to restrict measurements to volumes of interest around the metastases. Finally, we quantitatively analyzed blood vessel parameters locally around metastases. This allowed for the demonstration that a combined anti-angiogenic treatment significantly decreased the volume and thickness of blood vessels close to metastases. The proposed method showed the capacity of the method to reveal new aspects of the blood vessel structure interaction with metastases. This could be further used to both define new targets for precocious detection of metastases as well as to study the kinetics of metastasis development in bone and the action of drugs on this process.

In situ synchrotron quantitative analysis of competitive adsorption tendency of human serum protein to different clinical hemodialysis membranes and assessment of potential impacts

Protein adsorption on hemodialysis (HD) membrane matrices and surfaces is a highly undesirable process, as it triggers complement activation and leads to severe health complications for HD patients. However, there is a lack of systematic research investigating the correlation between membrane characteristics and their performance in the dialysis process. This study aims to provide a comprehensive understanding of the competitive adsorption tendencies of three human serum proteins (albumin (HSA), fibrinogen (FB), and transferrin (TRF)) on clinical dialysis membranes composed of polyethersulfone (PES), polyacrylonitrile (PAN), and polyvinyl fluoride (PVDF) polymers. To assess membrane morphology across the membrane cross-section, in situ synchrotron radiation micro-computed tomography (SR-µCT) imaging was conducted at the Canadian Light Source (CLS). Protein adsorption was analyzed qualitatively and quantitatively using an innovative synchrotron-based X-ray tomography technique. To determine the mutual influence of protein species on overall protein adsorption, adsorption from single-protein solutions was compared to adsorption from a protein mixture. Regarding single-protein adsorption, the PVDF membrane exhibited 40% less adsorption of HSA compared to the PES membrane. Conversely, FB adsorption was approximately 25% higher on the PVDF membrane compared to the PES membrane. The PAN membrane showed similar levels of HSA adsorption as the PES membrane and similar levels of FB adsorption as the PVDF membrane. In the case of adsorption from the protein mixture, a suppression of HSA adsorption and replacement of HSA with FB were observed. Consequently, the initial solution with a HSA content of 92% resulted in an adsorbed layer containing approximately 75–80% HSA across all the studied membranes. TRF adsorption remained unaffected by the presence of other proteins, consistent across all three membranes. Notably, the PES membrane exhibited the most significant change in the adsorbed protein composition between single-protein and multi-protein adsorption. In addition, this study comprehensively assesses the impact of fibrinogen adsorption on dialysis, including its consequences, blood activation, and implications for quality of life.

Heparin-Immobilized Polyethersulfone for Hemocompatibility Enhancement of Dialysis Membrane: In Situ Synchrotron Imaging, Experimental, and Ex Vivo Studies.

The goal of the current study is to enhance the hemocompatibility of polyethersulfone (PES) membranes using heparin immobilization. Heparin was immobilized covalently and via electrostatic interaction with the positively charged PES surface (pseudo-zwitterionic (pZW) complex) to investigate the influence of each method on the membrane hemocompatibility. In situ synchrotron radiation micro-computed tomography (SR-µCT) imaging, available at the Canadian Light Source (CLS), was used to critically assess the fibrinogen adsorption to the newly synthesized membranes qualitatively and quantitatively using an innovative synchrotron-based X-ray tomography technique. The surface roughness of the synthesized membranes was tested using atomic force microscopy (AFM) analysis. The membrane hemocompatibility was examined through the ex vivo clinical interaction of the membranes with patients' blood to investigate the released inflammatory biomarkers (C5a, IL-1α, IL-1β, IL-6, vWF, and C5b-9). The presence and quantitative analysis of a stable hydration layer were assessed with DSC analysis. Surface modification resulted in reduced surface roughness of the heparin-PES membrane. Both types of heparin immobilization on the PES membrane surface resulted in a decrease in the absolute membrane surface charge from -60 mV (unmodified PES) to -13 mV for the pZW complex and -9.16 mV for the covalently attached heparin, respectively. The loss of human serum fibrinogen (FB) was investigated using UV analysis. The PES membrane modified with the heparin pseudo-ZW complex showed increased FB retention (90.5%), while the unmodified PES membrane and the heparin covalently attached PES membrane exhibited approximately the same level of FB retention (81.3% and 79.8%, respectively). A DSC analysis revealed an improvement in the content of the hydration layer (32% of non-freezable water) for the heparin-coated membranes compared to the unmodified PES membrane (2.84%). An SR-µCT analysis showed that the method of heparin immobilization significantly affects FB adsorption distribution across the membrane thickness. A quantitative analysis using SR-µCT showed that when heparin is attached covalently, FB tends to be deposited inside the membrane pores at the top (layer index 0-40) membrane regions, although its content peak distribution shifted to the membrane surface, whereas the unmodified PES membrane holds 90% of FB in the middle (layer index 40-60) of the membrane. The ex vivo hemocompatibility study indicates an improvement in reducing the von Willebrand factor (vWF) for the heparin pseudo-ZW PES membrane compared to the covalently attached heparin and the untreated PES.

Towards an Informed CNN for Bone SR-microCT Image Classification with an Unsupervised Patched-based Image Clustering.

Bone microscale differences cannot be readily recognizable to humans from Synchrotron Radiation micro-Computed Tomography (SR-microCT) images. Premises are possible with Deep Learning (DL) imaging analysis. Despite this, more attention to high-level features leads models to require help identifying relevant details to support a decision. Within this context, we propose a method for classifying healthy, osteoporotic, and COVID-19 femoral heads SR-microCT images informing a vgg16 about the most subtle microscale differences using unsupervised patched-based clustering. Our strategy allows achieving up to 9.8% accuracy improvement in classifying healthy from osteoporotic images over uninformed methods, while 59.1% of accuracy between osteoporosis and COVID-19.Clinical relevance-We established a starting point for classifying healthy, osteoporotic, and COVID-19 femoral heads from SR-microCTs with human non-discriminative features, with 60.91% accuracy in healthy-osteporotic image classification.

The effect of microstructure on the tensile and impact behaviour of short-glass fibre-reinforced polyamide 6.6 as assessed by micro-computed tomography

Injection moulding of short-fibre-reinforced thermoplastics opens a new dimension in the field of mass production of complicated net-shaped parts with accurate dimensions and the new challenge is to produce parts with tailored properties. However, the layered structure frequently observed in these composites strongly affects their mechanical behaviour and constitutes the main difficulty in transferring the results of tests performed on standard specimens to actual components and parts. In addition, to use injection-moulded composite materials safely, their mechanical behaviour under different loading conditions must be well understood. In the present work, the effect of microstructure, in terms of fibre length and orientation, on the tensile and impact behaviour of injection-moulded short-glass fibre-reinforced polyamide 6.6 was investigated. Digital reconstruction of the three-dimensional structure of samples, differently oriented with respect to the melt flow path, was obtained by the high-spatial-resolution non-destructive technique of synchrotron radiation micro-computed tomography (micro-CT). Automatic evaluation of the fibre length distribution was developed by a global method based on the mean fibre length distribution, computed from the star length distribution (SLD). The results of uniaxial tensile tests and Izod impact experiments were successfully correlated with morphological analysis of fractured surfaces and the results of SLD. These studies revealed important changes in fibre orientation distribution when the sample orientation is changed with respect to melt flow direction, which also strongly influenced the composite mechanical response.

3D-imaging and quantitative assessment for size-related penetration of HfO2 nanoparticles in breast cancer tumor by synchrotron radiation microcomputed tomography

The development of quantitative analytical methods to assess the heterogeneous distribution and penetration of nanodrugs in solid tumors is of great importance for anticancer nanomedicine. Herein, Expectation-Maximization (EM) iterate algorithm and threshold segmentation methods were used to visualize and quantify the spatial distribution patterns, penetration depth and diffusion features of two-sized hafnium oxide nanoparticles (s-HfO2 NPs in 2 nm and l-HfO2 NPs in 50 nm sizes) in mouse models of breast cancer using synchrotron radiation micro-computed tomography (SR-μCT) imaging technique. The three-dimensional (3D) SR-μCT images were reconstructed based on the EM iterate algorithm thus clearly displayed the size-related penetration and distribution within the tumors after intra-tumoral injection of HfO2 NPs and X-ray irradiation treatment. The obtained 3D animations clearly show that a considerable amount of s-HfO2 and l-HfO2 NPs diffused into tumor tissues at 2 h post-injection and displayed the obvious increase in the tumor penetration and distribution area within the tumors at day 7 after combination with low-dose X-ray irradiation treatment. A thresholding segmentation for 3D SR-μCT image was developed to assess the penetration depth and quantity of HfO2 NPs along the injection sites in tumors. The developed 3D-imaging techniques revealed that the s-HfO2 NPs presented more homogeneous distribution pattern, diffused more quickly and penetrated more deeply within tumor tissues than the l-HfO2 NPs did. Whereas, the low-dose X-ray irradiation treatment greatly enhanced the wide distribution and deep penetration of both s-HfO2 and l-HfO2 NPs. This developed method may provide quantitative distribution and penetration information for the X-ray sensitive high-Z metal nanodrugs in the cancer imaging and therapy.

In-situ synchrotron imaging, experimental, and computational investigations on the efficiency of Trametes versicolor laccase on detoxification of P-Cresyl Sulfate (PCS) Protein Bound Uremic Toxin (PBUT).

Protein bound uremic toxins (PBUTs) are small substances binding to larger proteins, mostly human serum albumin (HSA), and are challenging to remove by hemodialysis (HD). Among different classes of PBUTs, p-cresyl sulfate (PCS) is the most widely used marker molecule and major toxin, as 95 % is bound to HSA. PCS has a pro-inflammatory effect and increases both the uremia symptom score and multiple pathophysiological activities. High-flux HD to clear PCS leads to serious loss of HSA, which results in a high mortality rate. The goal of the present study is to investigate the efficacy of PCS detoxification in serum of HD patients using a biocompatible laccase enzyme from Trametes versicolor. Molecular docking was used to gain an in-depth understanding of the interactions between PCS and the laccase to identify the functional group(s) responsible for ligand-protein receptor interactions. UV-Vis spectroscopy and gas chromatography-mass spectrometry (GC-MS) were used to assess the detoxification of PCS. GC-MS was used to identify the detoxification byproducts and their toxicity was assessed using docking commutations. In situ synchrotron radiation micro-computed tomography (SR-µCT) imaging available at the Canadian Light Source (CLS) was conducted to assess HSA binding with PCS before and after detoxification with laccase and undertake the corresponding quantitative analysis. GC-MS analyses confirmed the detoxification of PCS with laccase at a concentration of 500mg/L. The potential pathway of PCS detoxification in the presence of the laccase was identified. Increasing laccase concentration led to the formation of m-cresol, as indicated by the corresponding absorption in the UV-Vis spectra and a sharp peak on the GC-MS spectra. Our analysis provides insight into the general features of PCS binding on Sudlow site II, as well as insights into PCS detoxification product interactions. The average affinity energy for detoxification products was lower than that of PCS. Even though some byproducts showed potential toxicity, the level was lower than for PCS based on toxicity indexes (e.g., LD50/LC50, carcinogenicity, neurotoxicity, mutagenicity). In addition, these small compounds can also be more easily removed by HD compared to PCS. SR-µCT quantitative analysis showed adhesion of the HSA to a significant reduced extent in the presence of the laccase enzyme in bottom sections of the polyarylethersulfone (PAES) clinical HD membrane tested. Overall, this study opens new frontiers for PCS detoxification.

Synchrotron micro-computed tomography unveils the three-dimensional structure and origin of staminodes in the Plains Prickly Pear Cactus Opuntia polyacantha Haw. (Cactaceae).

Floral appendages display an array of shapes and sizes. Among these organs, staminodes are morphologically diverse structures that have lost the ability to produce pollen, but in some instances, they produce fertile pollen grains. In the family Cactaceae staminodes are uncommon and range from simple linear to flat to spatulate structures, but studies describing their structural attributes are scanty. This study highlights the advantages of synchrotron radiation for sample preparation and as a research tool for plant biology. It describes the internal morphology of floral parts, particularly stamen, tepal, and staminode in the Plains Prickly Pear Cactus, Opuntia polyacantha, using synchrotron radiation micro-computed tomography (SR-μCT). It also shows the different anatomical features in reconstructed three-dimensional imaging of reproductive parts and discuss the advantages of the segmentation method to detect and characterize the configuration and intricate patterns of vascular networks and associated structures of tepal and androecial parts applying SR-μCT. This powerful technology led to substantial improvements in terms of resolution allowing a more comprehensive understanding of the anatomical organization underlying the vasculature of floral parts and inception of staminodes in O. polyacantha. Tepal and androecial parts have uniseriate epidermis enclosing loose mesophyll with mucilage secretory ducts, lumen, and scattered vascular bundles. Cryptic underlying structural attributes provide evidence of a vascularized pseudo-anther conjoint with tepals. The undefined contours of staminodial appendages (pseudo-anther) amalgamated to the tepals' blurred boundaries suggest that staminodes originate from tepals, a developmental pattern supporting the fading border model of floral organ identity for angiosperms.

Effect of drying-wetting cycles on pore characteristics and mechanical properties of enzyme-induced carbonate precipitation-reinforced sea sand

Enzyme-induced carbonate precipitation (EICP) is an emanating, eco-friendly and potentially sound technique that has presented promise in various geotechnical applications. However, the durability and microscopic characteristics of EICP-treated specimens against the impact of drying-wetting (D-W) cycles is under-explored yet. This study investigates the evolution of mechanical behavior and pore characteristics of EICP-treated sea sand subjected to D-W cycles. The uniaxial compressive strength (UCS) tests, synchrotron radiation micro-computed tomography (micro-CT), and three-dimensional (3D) reconstruction of CT images were performed to study the multiscale evolution characteristics of EICP-reinforced sea sand under the effect of D-W cycles. The potential correlations between microstructure characteristics and macro-mechanical property deterioration were investigated using gray relational analysis (GRA). Results showed that the UCS of EICP-treated specimens decreases by 63.7% after 15 D-W cycles. The proportion of mesopores gradually decreases whereas the proportion of macropores increases due to the exfoliated calcium carbonate with increasing number of D-W cycles. The microstructure in EICP-reinforced sea sand was gradually disintegrated, resulting in increasing pore size and development of pore shape from ellipsoidal to columnar and branched. The gray relational degree suggested that the weight loss rate and UCS deterioration were attributed to the development of branched pores with a size of 100–1000 μm under the action of D-W cycles. Overall, the results in this study provide a useful guidancee for the long-term stability and evolution characteristics of EICP-reinforced sea sand under D-W weathering conditions.

Enhanced contrast synchrotron X-ray microtomography for describing skeleton-associated soft tissue defects in zebrafish mutants.

Detailed histological analyses are desirable for zebrafish mutants that are models for human skeletal diseases, but traditional histological techniques are limited to two-dimensional thin sections with orientations highly dependent on careful sample preparation. On the other hand, techniques that provide three-dimensional (3D) datasets including µCT scanning are typically limited to visualizing the bony skeleton and lack histological resolution. We combined diffusible iodine-based contrast enhancement (DICE) and propagation phase-contrast synchrotron radiation micro-computed tomography (PPC-SRµCT) to image late larval and juvenile zebrafish, obtaining high-quality 3D virtual histology datasets of the mineralized skeleton and surrounding soft tissues. To demonstrate this technique, we used virtual histological thin sections and 3D segmentation to qualitatively and quantitatively compare wild-type zebrafish and nkx3.2 -/- mutants to characterize novel soft-tissue phenotypes in the muscles and tendons of the jaw and ligaments of the Weberian apparatus, as well as the sinus perilymphaticus associated with the inner ear. We could observe disrupted fiber organization and tendons of the adductor mandibulae and protractor hyoideus muscles associated with the jaws, and show that despite this, the overall muscle volumes appeared unaffected. Ligaments associated with the malformed Weberian ossicles were mostly absent in nkx3.2 -/- mutants, and the sinus perilymphaticus was severely constricted or absent as a result of the fused exoccipital and basioccipital elements. These soft-tissue phenotypes have implications for the physiology of nkx3.2 -/- zebrafish, and demonstrate the promise of DICE-PPC-SRµCT for histopathological investigations of bone-associated soft tissues in small-fish skeletal disease models and developmental studies more broadly.

In-situ synchrotron quantitative analysis of competitive adsorption tendency of human serum proteins on polyether sulfone clinical hemodialysis membrane

Comprehensive understanding of protein adsorption phenomenon on membrane surface during hemodialysis (HD) is one of the key moments for development of hemocompatible HD membrane. Though many mechanisms and kinetics of protein adsorption on some surface have been studied, we are still far away from complete understanding and control of this process, which results in a series of biochemical reactions that causes severe complications with health and even the death among HD patients. The aim of this study is to conduct quantitative analysis of competitive adsorption tendency of human serum protein on polyether sulfone (PES) clinical dialysis membrane. In situ synchrotron radiation micro-computed tomography (SR-µCT) imaging available at the Canadian Light Source (CLS) was conducted to assess human serum proteinbinding and undertake the corresponding quantitative analysis.The competitive adsorption of Human protein albumin (HSA), fibrinogen (FB) and transferrin (TRF) were tested from single and multiple protein solution. Furthermore, in-vitro human serum protein adsorption on clinical dialyzers was investigated using UV–Visible to confirm the competitive adsorption tendency. Results showed that when proteins were adsorbed from their mixture, FB content (among proteins) in the adsorbed layer increased from 3.6% mass (content in the initial solution) to 18% mass and 12%, in case of in situ quantitative and invitro analysis, respectively. The increase in FB content was accompanied by the decrease in the HSA content, while TRF remained on approximately on the same level for both cases. Overall, the percentage of HSA adsorption ratio onto the HD membrane has dropped approximately 10 times when HSA was adsorbed in competition with other proteins, compared to the adsorption from single HSA solution. The substitution of HSA with FB was especially noticeable when HSA adsorption from its single solution was compared with the case of the protein mixture. Moreover, SR-µCT has revealed that FB when adsorbed from a protein mixture solution is located predominately in the middle of the membrane, whereas the peak of the distribution is shifted to membrane bottom layers when adsorption from FB single solution takes place. Results showed that HSA FB and TRF adsorption behavior observations are similar on both in-situ small scale and clinical dialyzer of the PES membrane.

Investigation on Human Serum Protein Depositions Inside Polyvinylidene Fluoride-Based Dialysis Membrane Layers Using Synchrotron Radiation Micro-Computed Tomography (SR-μCT).

Hemodialysis (HD) membrane fouling with human serum proteins is a highly undesirable process that results in blood activations with further severe consequences for HD patients. Polyvinylidene fluoride (PVDF) membranes possess a great extent of protein adsorption due to hydrophobic interaction between the membrane surface and non-polar regions of proteins. In this study, a PVDF membrane was modified with a zwitterionic (ZW) polymeric structure based on a poly (maleic anhydride-alt-1-decene), 3-(dimethylamino)-1-propylamine derivative and 1,3-propanesultone. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and zeta potential analyses were used to determine the membrane's characteristics. Membrane fouling with human serum proteins (human serum albumin (HSA), fibrinogen (FB), and transferrin (TRF)) was investigated with synchrotron radiation micro-computed tomography (SR-μCT), which allowed us to trace the protein location layer by layer inside the membrane. Both membranes (PVDF and modified PVDF) were detected to possess the preferred FB adsorption due to the Vroman effect, resulting in an increase in FB content in the adsorbed protein compared to FB content in the protein mixture solution. Moreover, FB was shown to only replace HSA, and no significant role of TRF in the Vroman effect was detected; i.e., TRF content was nearly the same both in the adsorbed protein layer and in the protein mixture solution. Surface modification of the PVDF membrane resulted in increased FB adsorption from both the protein mixture and the FB single solution, which is supposed to be due to the presence of an uncompensated negative charge that is located at the COOH group in the ZW polymer.

Unraveling the effect of collagen damage on bone fracture using in situ synchrotron microtomography with deep learning

When studying bone fragility diseases, it is difficult to identify which factors reduce bone’s resistance to fracture because these diseases alter bone at many length scales. Here, we investigate the contribution of nanoscale collagen behavior on macroscale toughness and microscale toughening mechanisms using a bovine heat-treatment fragility model. This model is assessed by developing an in situ toughness testing technique for synchrotron radiation micro-computed tomography to study the evolution of microscale crack growth in 3D. Low-dose imaging is employed with deep learning to denoise images while maintaining bone’s innate mechanical properties. We show that collagen damage significantly reduces macroscale toughness and post-yield properties. We also find that bone samples with a compromised collagen network have reduced amounts of crack deflection, the main microscale mechanism of fracture resistance. This research demonstrates that collagen damage at the nanoscale adversely affects bone’s toughening mechanisms at the microscale and reduces the overall toughness of bone.

Assessment of strain-induced cavitation of silica-filled styrene-butadiene rubber nanocomposite by synchrotron radiation tomography

Synchrotron radiation micro-computed tomography (SR μCT) was employed to study the cavitation phenomena upon cyclic tensile loading prior to and after thermal exposure of silica-filled styrene-butadiene rubber nanocomposites cured at different temperatures. A comparison with laboratory μCT measurements was also conducted to extend previous knowledge acquired by laboratory μCT into high resolution. SR μCT enhanced the detection of fillers and cavities down to dimensions of 3 μm, which represents a meaningful contribution to elucidate and characterize physical phenomena affecting the mechanical durability of rubber nanocomposites. The main findings revealed that the initiation of cavitation could be classified as: (a) debonding at the agglomerate's poles, (b) internal agglomerate fracture and (c) combination of debonding at the poles and internal agglomerate fracture. Cavitation in the rubber composite cured at 150 °C was dominated by debonding at the agglomerate poles, whereas cavitation in the rubber composite cured at 170 °C was evenly dominated among the three categories. Thermal exposure was found to increase the apparent crosslinking density of the rubber matrix thus inducing an increase of the stiffness of the nanocomposite in one hand and a decrease of its rupture strain. SR μCT revealed that fewer cavities were initiated in these samples, but their size was larger in comparison with the non-thermally treated samples.

Revision of recluse spiders (Araneae: Sicariidae: Loxosceles) preserved in Dominican amber and a total-evidence phylogeny of Scytodoidea reveal the first fossil Drymusidae

Recluse or violin spiders in the genus Loxosceles (Scytodoidea: Sicariidae) are a diverse group (~140 extant species) including medically important species and distributed mainly in the Americas, Africa, and the Mediterranean region. In addition, this genus includes three fossil species from Miocene Dominican amber. Here we revise the taxonomy of these fossil species by examining, imaging and re-describing their type specimens. We find that L. defecta Wunderlich, 1988 and L. deformis Wunderlich, 1988 are bona fide members of the genus and report additional characters overlooked in their original descriptions. We further study the holotype of L. aculicaput Wunderlich, 2004 using synchrotron radiation micro-computed tomography to reveal previously unknown morphological details hidden by fissures in the amber. We found several characters inconsistent with Loxosceles but consistent with Drymusa (false violin spiders; Scytodoidea: Drymusidae), such as three claws, well-developed podotarsite, and a broad colulus. This suggests the species is misplaced in Loxosceles. To test this hypothesis, we estimated a total-evidence phylogeny of the superfamily Scytodoidea including extant and fossil taxa, morphological data, traditional molecular markers, and sequences of ultra-conserved elements. The results show unambiguously that L. aculicaput belongs to Drymusa and is a close relative of extant species of the genus inhabiting the Greater Antilles. Therefore, we here transfer this species to Drymusa, establishing a new combination and new family assignment. Drymusa aculicaputcomb. nov. represents the first known fossil Drymusidae and shows that crown members of this genus already existed in the Miocene.