Star Volume Research Articles

Emplacement of shergottites in the Martian crust inferred from three‐dimensional petrofabric and crystal size distribution analyses

AbstractShergottites are mafic to ultramafic igneous rocks that represent the majority of known Martian meteorites. They are subdivided into gabbroic, poikilitic, basaltic, and olivine–phyric categories based on differences in mineralogy and textures. Their geologic contexts are unknown, so analyses of crystal sizes and preferred orientations have commonly been used to infer where shergottites solidified. Such environments range from subsurface cumulates to shallow intrusives to extrusive lava flows, which all have contrasting implications for interactions with crustal material, cooling histories, and potential in situ exposure at the surface. In this study, we present a novel three‐dimensional (3‐D) approach to better understand the solidification environments of these samples and improve our knowledge of shergottites' geologic contexts. Shape preferred orientations of most phases and crystal size distributions of late‐forming minerals were measured in 3‐D using X‐ray computed tomography (CT) on eight shergottites representing the gabbroic, poikilitic, basaltic, and olivine–phyric categories. Our analyses show that highly anisotropic, rod‐like pyroxene crystals are strongly foliated in the gabbroic samples but have a weaker foliation and a mild lineation in the basaltic sample, indicating a directional flow component in the latter. Star volume distribution analyses revealed that most phases (maskelynite, pyroxene, olivine, and oxides/sulfides) preserve a foliated texture with variable strengths, and that the phases within individual samples are strongly to moderately aligned with respect to one another. In combination with relative cooling rates during the final stages of crystallization determined from interstitial oxide/sulfide crystal size distribution analyses, these results indicate that the olivine–phyric samples were emplaced as shallow intrusives (e.g., dikes/sills) and that the gabbroic, poikilitic, and basaltic samples were emplaced in deeper subsurface environments.

EFFECTS OF VOLUME OF INTEREST (VOI) SIZE ON TRABECULAR BONE QUANTIFICATION IN THE JUVENILE DISTAL FEMUR

Volumes of interest (VOI) are commonly assigned to image stacks generated from micro-computed tomography to specify areas for bone quantification. However, the size of the VOI can impact the values obtained for trabecular bone parameters. This study aims to investigate the effect of VOI size by applying VOIs of four different diameters (10%, 15%, 20% and 30% of the antero-posterior width). Ten juvenile right distal femora were included, aged from pre-natal to three years. Smaller VOIs were placed within the largest VOI, with multiple locations used for the same VOI size. The observed parameters included bone volume fraction (BV/TV), trabecular bone thickness (Tb.Th), separation (Tb.Sp), number (Tb.N), degree of anisotropy by mean intercept length (DA.MIL) and star volume distribution (DA.SVD). Statistically significant differences between VOI sizes were found for Tb.Sp, Tb.N, DA.MIL and DA.SVD. A possible effect of localized variation was found due to significantly different values for Tb.Th between VOI locations. The effect related to VOI geometry was reflected by DA.MIL and DA.SVD as no significant difference was found between locations. The minimum diametric strut quantity (DSQ, diameter multiplied by Tb.N) of 4 can be implied based on the zero DA.SVD value found in particular VOIs.

Glucocorticoid‐induced dose‐related and site‐specific bone remodelling, microstructure, and mechanical changes in cancellous and cortical bones

The study investigated the effects of long-term glucocorticoid (GC) administration on bone remodelling, microstructure, and biomechanical strength in cortical and cancellous (trabecular) bones. Thirty-one female Sprague-Dawley rats were randomly divided into three dexamethasone (Dex) dosage groups, 1.0, 2.5, and 5.0mg/kg twice a week for 8weeks, and one control group treated with saline. At the end of the experiment, the tibia of one side and the fourth lumbar vertebrae were processed into sections for a histomorphometric analysis, while the femur of the same side and the fifth vertebrae were isolated for a biomechanical test. A dose-dependent decline in bone formation was observed in both trabecular and cortical (periosteal and endosteal) bones. In contrast, bone resorption was inhibited only in cancellous bone in the two higher dose groups and not dose-related. The ratio of Node/Termini increased, while marrow star volume (MSV) decreased in all Dex groups in metaphyseal trabecular bones, both of which were dose-dependent. Subendosteal cortex porosity increased in parallel with non-uniform trabecular distribution, but cortical thickness remained unchanged. Interestingly, there were no significant changes in microstructure or mechanical strength in lumbar trabecular bone. The cortical elastic load was dose-independently reduced in all three Dex groups when compared with the control group. In summary, bone remodelling was dose-dependently inhibited in cancellous bones but enhanced in intracortical bones. The non-uniform distribution of trabecular bone and increased porosity in the inner edge of cortical bone were both in parallel with GC dosage, and the porosity increase was more likely to occur, leading to reduced cortical mechanical strength.

Selective Voronoi tessellation as a method to design anisotropic and biomimetic implants

The geometry of a metallic scaffold is important for the success of bone implants, where the introduction of porosity can reduce stress shielding effects and allow for bone tissue integration. In this work, porous scaffolds were designed to closely mimic the natural structure of trabecular bone using selective Voronoi tessellation with preferential seeding. A workflow to generate these structures is introduced, where voided regions of seeds in the starting volume create preferential texture during polyhedral expansion, resulting in modified strut orientation in the implant. Anisotropy was digitally characterized by mean-intercept length and star volume distribution measurements to determine similarity to trabecular orientation. This work demonstrates that selective Voronoi tessellation is an effective method to generate biomimetic porous scaffolds with increased anisotropy and tunable strut architecture in three dimensions as a suitable alternative to patient-derived bone geometries.

Correlation between elastic properties and morphology in short fiber composites by X-ray computed micro-tomography

In this work the architectural anisotropy of short fiber reinforced polymers (SFRPs) has been characterized using X-ray computed micro-tomography (micro-CT) with four different morphometric methods: Mean Intercept Length (MIL), Volume Orientation (VO), Star Length Distribution (SLD) and Star Volume Distribution (SVD). The fabric tensor obtained from micro-CT analysis provided information on the fiber orientation, indicating that fibers were partially aligned in the injection direction. The fiber length and orientation obtained from optical microscopy and from the morphometric analysis in 3D, respectively, has been used to determine the mechanical properties of the composite sample, using a model based on micro and macromechanics. This approach leads to the prediction of the elastic constants of the component for any possible composite morphology resulting from injection, representing a key need for the design of SFRP components.

Deterioration of bone microstructure by aging and menopause in Japanese healthy women: analysis by HR-pQCT.

Second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT) has provide higher quality of bone images with a voxel size of 61µm, enabling direct measurements of trabecular thickness. In addition to the standard parameters, the non-metric trabecular parameters such as trabecular morphology (plate to rod-like structures), connectivity, and anisotropy can also be analyzed. The purpose of this study is to investigate deterioration of bone microstructure in healthy Japanese women by measuring standard and non-metric parameters using HR-pQCT. Study participants were 61 healthy Japanese women (31-70years). The distal radius and tibia were scanned using second-generation HR-pQCT, and microstructures of trabecular and cortical bone were measured. Non-metric trabecular parameters included structure model index (SMI), trabecular bone pattern factor (TBPf), connectivity density (Conn.D), number of nodes (N.Nd/TV), degree of anisotropy (DA), and star volume of marrow space (V*ms). Estimated bone strength was evaluated by micro finite element analysis. Associations between bone microstructure, estimated bone strength, age, and menopause were analyzed. Trabecular number declined with age, and trabecular separation increased. SMI and TBPf increased, Conn.D and N.Nd/TV declined, and V*ms increased. Cortical BMD and thickness declined with age, and porosity increased. Stiffness and failure load decreased with age. Cortical thickness and estimated bone strength were affected by menopause. Cortical thickness was most associated with estimated bone strength. Trabecular and cortical bone microstructure were deteriorated markedly with age. Cortical thickness decreased after menopause and was most related to bone strength. Non-metric parameters give additional information about osteoporotic changes of trabecular bone.

Dynamic microstructural changes in alveolar bone in ligature-induced experimental periodontitis.

Periodontitis is an inflammatory disease that causes bone resorption. This study used a ligature-induced experimental periodontitis model to observe the kinetic process of microstructural changes in alveolar bone and introduced star volume analysis as a new methodology to assess microstructural changes. Thirty Wistar rats were used. To induce experimental periodontitis, ligatures were placed around the maxillary first molar. Rats were euthanized on days 0, 1, 3, 7, 14, and 28 after ligature placement. In addition to using hematoxylin and eosin staining, tartrate-resistant acid phosphatase (TRAP)/alkaline phosphatase (ALP) double staining, and micro-computed tomography were performed to analyze bone remodeling. From day 0 to day 7 (initiation phase), the model showed predominant inflammation with increased numbers of TRAP-positive cells, while ALP expression decreased. In contrast, from day 14 to day 28 (resolution phase), inflammatory cells and TRAP-positive cells decreased, whereas ALP expression recovered to levels comparable to that on day 0. Regarding microstructure parameters, in the initiation phase, bone volume fraction, bone mineral density, trabecular thickness, and star volume of the trabeculae decreased significantly, whereas trabecular separation and star volume of the marrow space increased significantly, indicating bone resorption. In the resolution phase, microstructure parameters normalized, indicated bone formation. We confirmed dynamic alveolar bone remodeling in ligature-induced periodontitis in rats. Furthermore, we assessed the potential for using star volume analysis as a sensitive new tool to clarify microstructural changes to alveolar bone in this model.

Aging-associated microstructural deterioration of vertebra in zebrafish

Zebrafish, a small teleost fish, is currently emerging as an animal model of local and systemic aging. In this study, we assessed age-related degenerative changes in the vertebral bone of zebrafish (3–12 month-post-fertilisation [mpf]) using micro-CT scanning. The bone volume (BV) of the trabecular bone in the male and female fish peaked at 6 mpf and reduced with age. In contrast to BV, bone mineral density and tissue volume did not change after 6 mpf, implying that the total mineral volume in the trabecular area remains unchanged, retaining the strength of vertebra. In addition, we performed micro-structural analysis of the trabecular thickness, trabecular number, and star volume of the tissue space and trabeculae, and found that the size of the trabecular bone reduced with age. Furthermore, aged zebrafish (45 mpf) exhibited ectopic ossification inside or outside of their vertebrae.In summary, we analysed bone structural parameters in adult zebrafish vertebra, which are also used in humans, and demonstrated that aged zebrafish have deteriorated microarchitecture (trabecular thickness and number, tissue space star volume and trabecular star volume) with reduction of trabecular bones, similar to that observed during aging in humans. Zebrafish can be utilised as an animal model to understand the pathology of human bone aging, and the discovery of new therapeutic agents against age-related osteoporosis.

Determining the Dilution Exponent for Entangled 1,4-Polybutadienes Using Blends of Near-Monodisperse Star with Unentangled, Low Molecular Weight Linear Polymers

We determine experimentally the “dilution exponent” α for entangled polymers from the scaling of terminal crossover frequency with entanglement density from the linear rheology of three 1,4-polybutadiene star polymers that are blended with low-molecular-weight, unentangled linear 1,4-polybutadiene at various star volume fractions, ϕs. Assuming that the rheology of monodisperse stars depends solely on the plateau modulus GN(ϕs) ∝ ϕs1+α, the number of entanglements per chain Me(ϕs) ∝ ϕs–α, and the tube-segment frictional Rouse time τe(ϕs) ∝ ϕs–2α, we show that only an α = 1 scaling superposes the Me(ϕs) dependence of the terminal crossover frequency ωx,t of the blends with those of pure stars, not α = 4/3. This is the first determination of α for star polymers that does not rely on any particular tube model implementation. We also show that a generalized tube model, the “Hierarchical model”, using the “Das” parameter set with α = 1 reasonably predicts the rheological data of the melts and blends featured in...

Histological and histomorphometric studies of the effects of hyaluronic acid on osseointegration of titanium implant in rabbits

Background: One of the unique prosthesis for tooth or teeth replacement is the dental implant. Our attempt is using a biomaterial system that is easily obtained and applicable and has the ability to provoke osteoinductive growth factor to enhance bone formation at the site of application. One of these natural polymers is hyaluronic acid. Material and methods: Sixty machined surface implants from commercially pure titanium rod inserted in thirty NewZealand rabbits. Two implants placed in both tibia of each rabbit. The animals scarified at 1, 2 and 4 weeks after implantation (10 rabbits for each interval). For all of animals the right tibia’s implant was control (uncoated) and the left one was experimental (coated with 0.1ml Hyaluronic acid gel). All sections have been stained with Haematoxylin and Eosin then they were histologically examined and assessed for histomorphometric analysis for counting of bone cells (osteoblast, osteocyte and osteoclast), cortical bone thickness, trabecular width, thread width and marrow space star volume (V*). Results: Histological findings for hyaluronic acid- coated titanium implant revealed an earlier bone formation, mineralization and maturation than that in control groups. Histomorphometric analysis for all bone parameters that examined in this study, showed highly significant difference between control and experimental groups in all healing intervals. Conclusion: Commercially pure titanium endosseous implants coated with hyaluronic acid may be osteocoductive thus accelerating healing process and enhancing osseointegration.

Treadmill Running Ameliorates Destruction of Articular Cartilage and Subchondral Bone, Not Only Synovitis, in a Rheumatoid Arthritis Rat Model.

We analyzed the influence of treadmill running on rheumatoid arthritis (RA) joints using a collagen-induced arthritis (CIA) rat model. Eight-week-old male Dark Agouti rats were randomly divided into four groups: The control group, treadmill group (30 min/day for 4 weeks from 10-weeks-old), CIA group (induced CIA at 8-weeks-old), and CIA + treadmill group. Destruction of the ankle joint was evaluated by histological analyses. Morphological changes of subchondral bone were analyzed by μ-CT. CIA treatment-induced synovial membrane invasion, articular cartilage destruction, and bone erosion. Treadmill running improved these changes. The synovial membrane in CIA rats produced a large amount of tumor necrosis factor-α and Connexin 43; production was significantly suppressed by treadmill running. On μ-CT of the talus, bone volume fraction (BV/TV) was significantly decreased in the CIA group. Marrow star volume (MSV), an index of bone loss, was significantly increased. These changes were significantly improved by treadmill running. Bone destruction in the talus was significantly increased with CIA and was suppressed by treadmill running. On tartrate-resistant acid phosphate and alkaline phosphatase (TRAP/ALP) staining, the number of osteoclasts around the pannus was decreased by treadmill running. These findings indicate that treadmill running in CIA rats inhibited synovial hyperplasia and joint destruction.

Histological and Histomorphometric Studies of the Effects of Hyaluronic Acid on Osseointegration of Titanium Implant in Rabbits

Background: One of the unique prosthesis for tooth or teeth replacement is the dental implant. Our attempt is using a biomaterial system that is easily obtained and applicable and has the ability to provoke osteoinductive growth factor to enhance bone formation at the site of application. One of these natural polymers is hyaluronic acid. Material and methods: Sixty machined surface implants from commercially pure titanium rod inserted in thirty NewZealand rabbits. Two implants placed in both tibia of each rabbit. The animals scarified at 1, 2 and 4 weeks after implantation (10 rabbits for each interval). For all of animals the right tibia’s implant was control (uncoated) and the left one was experimental (coated with 0.1ml Hyaluronic acid gel). All sections have been stained with Haematoxylin and Eosin then they were histologically examined and assessed for histomorphometric analysis for counting of bone cells (osteoblast, osteocyte and osteoclast), cortical bone thickness, trabecular width, thread width and marrow space star volume (V*). Results: Histological findings for hyaluronic acid- coated titanium implant revealed an earlier bone formation, mineralization and maturation than that in control groups. Histomorphometric analysis for all bone parameters that examined in this study, showed highly significant difference between control and experimental groups in all healing intervals. Conclusion: Commercially pure titanium endosseous implants coated with hyaluronic acid may be osteocoductive thus accelerating healing process and enhancing osseointegration.

A modern approach to porosimetry of virtual cementitious materials

To assess the pore size of virtual cementitious materials, the star volume method (SVM) can be considered an effective tool. Unfortunately, the SVM requires a large number of plane sections in each of the very large number of random points, resulting in a time-consuming and expensive operation. As a more economical alternative, this paper presents a stereology-based contracted method, which uses a well-known theoretical concept proposed by Cauchy. This method completed pore size measurements in a shorter period of time (reductions as high as 85%) while demonstrating reliability to be maintained at the same level.

Decreased Bone Formation Explains Osteoporosis in a Genetic Mouse Model of Hemochromatosiss.

Osteoporosis may complicate iron overload diseases such as genetic hemochromatosis. However, molecular mechanisms involved in the iron-related osteoporosis remains poorly understood. Recent in vitro studies support a role of osteoblast impairment in iron-related osteoporosis. Our aim was to analyse the impact of excess iron in Hfe-/- mice on osteoblast activity and on bone microarchitecture. We studied the bone formation rate, a dynamic parameter reflecting osteoblast activity, and the bone phenotype of Hfe−/− male mice, a mouse model of human hemochromatosis, by using histomorphometry. Hfe−/− animals were sacrificed at 6 months and compared to controls. We found that bone contains excess iron associated with increased hepatic iron concentration in Hfe−/− mice. We have shown that animals with iron overload have decreased bone formation rate, suggesting a direct impact of iron excess on active osteoblasts number. For bone mass parameters, we showed that iron deposition was associated with bone loss by producing microarchitectural impairment with a decreased tendency in bone trabecular volume and trabecular number. A disorganization of trabecular network was found with marrow spaces increased, which was confirmed by enhanced trabecular separation and star volume of marrow spaces. These microarchitectural changes led to a loss of connectivity and complexity in the trabecular network, which was confirmed by decreased interconnectivity index and increased Minkowski’s fractal dimension. Our results suggest for the first time in a genetic hemochromatosis mouse model, that iron overload decreases bone formation and leads to alterations in bone mass and microarchitecture. These observations support a negative effect of iron on osteoblast recruitment and/or function, which may contribute to iron-related osteoporosis.

The Role of Architecture in the Melt-State Self-Assembly of (Polystyrene)star-b-(Polyisoprene)linear-b-(Polystyrene)star Pom-Pom Triblock Copolymers

Using a unique one-pot convergent anionic polymerization strategy, 18 (polystyrene)star-b-(polyisoprene)linear-b-(polystyrene)star (SnISn) pom-pom triblock copolymers were synthesized varying a range of architectural parameters including PS arm molecular weight (Mn,star), the number of arms contained in the star (n), and the PI midblock molecular weight (Mn,PI). A selected series of five of these 18, in which Mn,star was held approximately constant between 14.3 and 16.5 kDa, but with the numbers of arms in the star and PI midblock molecular weight varied, were selected for detailed characterization using rheology, AFM, and SAXS. The five selected all shared PS as the minority component, with star volume fractions (fPS) varying between 0.11 and 0.22. All samples showed clear phase separation, with three of the five adopting a highly ordered hexagonal packing of cylinders (HPC) confirmed through SAXS and AFM. The remaining two systems were limited to liquid-like packing of cylindrical domains (LLP). Longer midblock molecular weights and increased numbers of arms in the star both showed a propensity to hinder formation of a highly ordered hexagonal lattice. Increasing the number of arms in the star also favored transitions to a disordered phase at lower temperatures when overall SnISn molecular weight was held constant. The behavioral trends identified suggest interfacial packing frustration plays a prominent role in determining the ability of the system to develop highly ordered periodic structures. The chain crowding produced by the PS star architecture intrinsically favors interfacial curvature toward the majority PI component, contrary to that intrinsically favored by the block composition alone. In the two systems in which the frustration was architecturally most severe (largest n of 7.1, highest Mn,PI of 191 kDa), evolution of a hexagonal lattice could not be induced, even after significant thermal annealing. The pom-pom architecture itself also appears to have a significant impact on entanglement relaxation dynamics, with development of HPC morphologies only possible at elevated temperatures.

Improved Bone Micro Architecture Healing Time after Implant Surgery in an Ovariectomized Rat.

The present animal study investigated whether oral intake of synthetic bone mineral (SBM) improves peri-implant bone formation and bone micro architecture (BMA). SBM was used as an intervention experimental diet and AIN-93M was used as a control. The SBM was prepared by mixing dicalcium phosphate dihydrate (CaHPO4·2H2O) and magnesium and zinc chlorides (MgCl2 and ZnCl2, respectively), and hydrolyzed in double-distilled water containing dissolved potassium carbonate and sodium fluoride. All rats were randomly allocated into one of two groups: a control group was fed without SBM (n = 18) or an experimental group was fed with SBM (n = 18), at seven weeks old. At 9 weeks old, all rats underwent implant surgery on their femurs under general anesthesia. The implant was inserted into the insertion socket prepared at rats' femur to a depth of 2.5 mm by using a drill at 500 rpm. Nine rats in each group were randomly selected and euthanized at 2 weeks after implantation. The remaining nine rats in each group continued their diets, and were euthanized in the same manner at 4 weeks after implantation. The femur, including the implant, was removed from the body and implant was pulled out by an Instron universal testing machine. After the implant removal, BMA was evaluated by bone surface ratio (BS/BV), bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular number (TbN), trabecular star volume (Vtr), and micro-CT images. BS/BV, BV/TV, TbTh and Vtr were significantly greater in the rats were fed with SBM than those were fed without SBM at 2 and 4 weeks after implantation (P < 0.05). The present results revealed that SBM improves the peri-implant formation and BMA, prominent with trabecular bone structure. The effect of SBM to improve secondary stability of the implant, and shortening the treatment period should be investigated in the future study.

METHODOLOGY FOR POROSIMETRY IN VIRTUAL CEMENTITIOUS COMPOSITES TO ECONOMICALLY AND RELIABLY ESTIMATE PERMEABILITY

A novel methodology is described for porosimetry as well as for water transport through the pore system in dynamic DEM-based virtual cementitious materials. The pore network topology, the pore size distribution and the pore connectivity are assessed on the basis of a robotics-inspired pore delineation method and star volume measurements. Permeability estimates are based on a tube network model that incorporates these parameters and a shape factor. Since concrete contains in practical situations a variable amount of water, permeability estimation is presented as a function of the state of saturation. Satisfactory agreement is found with experimental data, validating the methodology. Earlier, the various "building blocks" were separately validated.

Zoledronic Acid Reverses Acute Bone Impairment in a Mouse Model for Sickle Cell Disease

Sickle cell disease (SCD) is a worldwide distributed hereditary red cell disorder, characterized by the synthesis of pathological hemoglobin S (HbS). Up to now, limited studies in SCD patients have proposed a bone loss related to recurrent acute vaso-occlusive events (VOCs). Here, we designed a study in a humanized mouse model for SCD to evaluate (i) bone structure turnover and micro-architecture by histomorphometric approach; (ii) osteoblastic differentiation by RT-PCR analysis of bone runx2, sparc and alp gene expression. We used humanized healthy control (Hbatm1(HBA)TowHbbtm3(HBG1,HBB)Tow) and SCD (Hbatm1(HBA)TowHbbtm2(HBG1,HBB*)Tow) mice. Mice were divided into different groups as detailed in the enclosed flow-chart. In steady state, we first evaluated bone-marrow erythropoiesis by FACS analysis based on CD44-TER119 strategy. No signs of ineffective erythropoiesis were detectable in SCD mice compared to controls. Bone analysis was performed by histomorphometric approach after double labelling with demeclocycline followed by calcein to evaluate the dynamic parameters of bone turnover and analyzed by a specific software (bone3.1, Explora Nova, Larochelle, France). The histomorphometric bone analysis revealed (i) reduced bone volume with associated decreased trabecular number and increased trabecular separation; (ii) increased bone-turnover measured as bone formation rate (BFR) and activation frequency (AcF); (iii) decreased number of nodes (NdN) and node termini ratio; (iv) increased marrow star volume (MSV) and fractal dimension (D) compared to healthy mice. The bone molecular analysis revealed a significant down-regulation of runx2, sparc and alp gene expression in SCD mice compared to healthy ones. These data indicate a severe osteoporosis with bone fragility associated with alteration of osteogenic differentiation in SCD mice. Zoledronic acid (Zol) is the most powerful available bisphosphonate used to reduce bone turnover and bone fragility. Since VOCs are life-threatening complication of SCD and mainly involved skeletal system, requiring multidiscliplinary approach, we exposed SCD and control mice to hypoxia/reoxygenation (H/R) stress to mimic acute VOCs (see flow-chart). Mice were exposed to hypoxia (8% oxygen, 10 hours) followed by reoxygenation (21% oxygen) for either 18 hours to carry out molecular analysis or 10 days to carry out histomorphometric analysis. In H/R exposed vehicle treated SCD mice, we found (i) a significant increase in AcF (bone turnover), without differences in bone structure and microarchitecture compared to SCD mice under normoxia; (ii) a further reduction in osteogenic differentiation molecular markers. Zol (100 μg/ Kg in a single ip injection) was administrated either 7 days before (Zol-pre) or immediately after (Zol-post) H/R stress. In SCD mice, both Zol-pre and Zol-post significantly prevented the H/R induced increased bone turnover, while no differences were detectable in bone structure and microarchitecture compared to vehicle treated H/R SCD mice. The molecular analysis showed that Zol increased the osteogenic related gene expression, indicating a positive induction of osteogenic differentiation. Our data suggest that murine SCD is characterized by a significant bone impairment related to the unbalance between osteoblastic/osteoclastic activity in favor of osteoclastic one in presence of a down-regulation of osteogenic differentiation. In SCD, Zol plays a pivotal role decreasing osteoclastic activity and promoting osteogenic differentiation, representing a powerful new therapeutic strategy to limit bone disease in SCD. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Three-dimensional arrangement of β-tricalcium phosphate granules evaluated by microcomputed tomography and fractal analysis

The macrophysical properties of granular biomaterials used to fill bone defects have rarely been considered. Granules of a given biomaterial occupy three-dimensional (3-D) space when packed together and create a macroporosity suitable for the invasion of vascular and bone cells. Granules of β-tricalcium phosphate were prepared using polyurethane foam technology and increasing the amount of material powder in the slurry (10, 11, 15, 18, 21 and 25g). After sintering, granules of 1000–2000μm were prepared by sieving. They were analyzed morphologically by scanning electron microscopy and placed in polyethylene test tubes to produce 3-D scaffolds. Microcomputed tomography (microCT) was used to image the scaffolds and to determine porosity and fractal dimension in three dimensions. Two-dimensional sections of the microCT models were binarized and used to compute classical morphometric parameters describing porosity (interconnectivity index, strut analysis and star volumes) and fractal dimensions. In addition, two newly important fractal parameters (lacunarity and succolarity) were measured. Compression analysis of the stacks of granules was done. Porosity decreased as the amount of material in the slurry increased but non-linear relationships were observed between microarchitectural parameters describing the pores and porosity. Lacunarity increased in the series of granules but succolarity (reflecting the penetration of a fluid) was maximal in the 15–18g groups and decreased noticeably in the 25g group. The 3-D arrangement of biomaterial granules studied by these new fractal techniques allows the optimal formulation to be derived based on the lowest amount of material, suitable mechanical resistance during crushing and the creation of large interconnected pores.

PACKING ISSUE IN CEMENT BLENDING FOR SUSTAINABILITY DEVELOPMENTS - APPROACH BY DISCRETE ELEMENT METHOD

Common cement blending materials for concrete like fly ashes, blast furnace slag, silica fume, metakaolin and rice husk ash have been investigated experimentally as to their impact on concrete’s mechanical, physical and sustainability capabilities. Such efforts offer but case-related information on involved materials and used procedures. Generalizations will be difficult because also contradicting information is provided: a weak basis to guide further developments. Published research data on blends with inert components (carbon black) confirm fineness to be the leading parameter governing their mechanics. Experimental efforts revealing blending effects on durability issues are more scarce because of their complicated, laborious and time-consuming nature. Hence, generalization capabilities are even more restricted. An approach is therefore presented for studying cementitious materials in the virtual reality, employing the concurrent algorithm-based dynamic discrete element method (DEM), HADES. Hydration simulation of the simulated (blended) Portland cement grain mixture is thereupon accomplished with an extended version of the vector approach. Robotics-based pore delineation provides topological information, while geometric characterization of the pore networks is accomplished by star volume measurements. Topological and geometric parameters can be combined in a hydraulic model for durability estimation. This approach allows covering a wide range of parameters. This would render possible more systematic and economic development of such materials for sustainability purposes, among other things. The production stages (DEM and hydration simulation) and the analysis stages (pore delineation and topology and geometry assessment) are briefly outlined. Application of the methodology is illustrated on finer and coarser grained cements blended with rice husk ash produced with different fineness. The effects of the gap in grading on the pore network characteristics relevant for transport-based durability items are outlined.