Hawthorn fruits (Crataegus pinnatifida) present high content of high-methoxyl pectin, able to gel under high-sugar acidic conditions. In this work, the proximate and phytochemical composition of two ...cultivars of hawthorn fruit and the gelling ability of their unrefined (not further processed) dried powders and their extracted pectins were evaluated and systematically compared with citrus pectins (CP1 and CP2). Mianqiu (MI), a less known cultivar, showed two-fold higher pectin content and titratable acidity than Dajinxing (DA), one of the most common cultivars. DA showed higher starch, insoluble dietary fiber, pasting viscosity and total and extractable (EPP) phenolic compounds. EPP content was almost two-fold higher in DA than MI, resulting in stronger antioxidant properties. All high-methoxyl sugar acid gels exhibited a predominantly elastic response. MI resulted in hawthorn-powder gels with higher elastic modulus (G′) after gel-making (initially stronger gels), and lower G′ increase during storage (hardening) than DA. Citrus pectins (CP2 > CP1) showed higher gel-strength and faster gelling ability than hawthorn pectin gels (DA > MI) based on the lower G’ and lack of gel formation after 90 min of cooling in hawthorn pectin-based gels. The gelation results were closely linked to the starch-to-pectin ratio, purity, and degree of methyl esterification.
•Hawthorn fruit from Mianqiu (MI) was richer in pectin than Dajinxing (DA) cultivar.•Flour from DA cultivar had higher starch, total dietary fiber and pasting viscosity.•Extractable phenolics were two-fold higher in DA, with stronger antioxidant capacity.•MI flour formed high-sugar acid gels with higher elastic modulus and less hardening.•Citrus pectins showed faster gelling and higher gel-strength than hawthorn pectins.
Extensive nanoindentation testing over a range of deflection depths of up to 4 μm yielded a large dataset, providing a viable framework for the statistical assessment of the mechanical properties, ...specifically elastic modulus (E) and hardness (H), of compositionally diverse organic-rich mudstone samples. The data from indentations as shallow as 300–400 nm were clustered using the k-means algorithm to identify three mechanical categories in the samples: a soft pseudophase (e.g., organic matter, gypsum, and clay minerals), a stiff pseudophase (e.g., quartz and feldspar), and a transitional composite-like pseudophase bridging the soft and hard minerals. The initially diverse values of E and H for the mechanical pseudophases were observed to converge to a constant value at indentations beyond 2–2.5 μm (varying between different samples), implying the existence of a minimal probing depth for assessing the bulk E and H of heterogeneous mudstone samples. The obtained bulk E and H values (8–21 GPa and 0.3–0.9 GPa, respectively) demonstrated a strong correlation with the mineralogical composition of the indented samples. Despite containing a notable proportion of mechanically stiff components (>45 vol%), the bulk mechanical parameters determined in this study were significantly lower than those reported for major shale formations such as the Barnett and Longmaxi Shale. This discrepancy is primarily due to the presence of organic matter with low thermal maturity (Ro < 0.6%), which constitutes <36 vol% of the samples, and a significant gypsum content, accounting for <15 vol%.
The employed approach not only demonstrated the importance of choosing the proper indentation depths for investigating the mechanical properties of highly heterogeneous mudstone rocks and their constituent minerals, but it also illustrated the capability of examining various volumes of investigation using nanoindentation, approaching macroscopic values, and identifying a representative element volume (REV). The findings also provided crucial insights into the fracability and overall producibility of the investigated formations, thereby enhancing our understanding of their extraction potential.
•CSM nanoindentation assesses macro-scale rock mechanics, surpassing nano- and micro-scale norms.•Indentation depths over 2.5 μm capture representative element volume (REV) in heterogeneous rock samples.•The findings highlighted the significant influence of rock composition on its mechanical properties.
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•TPMS parameter influences on elastic modulus and anisotropy were analyzed.•Isotropic TPMS were designed by the proposed Curvature-Wall thickness adjustment method.•Composite TPMS was ...proposed for units with performances far from the target to generate isotropic TPMS.
Recently, triply periodic minimal surface (TPMS) is emerging as an ideal tool to generate porous structures. Yet, most of the current work only focuses on controlling the elastic modulus by the relative density. For special engineering applications, such as porous bone implants or energy absorbers, the generated porous TPMS may still be broken due to anisotropy. In this work, two strategies are proposed to design isotropic TPMS structures. The numerical homogenization theory and finite element analysis methods are utilized to study the relationship between TPMS parameters and the elastic modulus or anisotropy properties. Based on that, a Curvature-Wall thickness (CW) adjustment method is proposed for sheet TPMS structures whose performances are close to isotropy properties. In virtue of the constructed design map, both elastic modulus and anisotropy properties can be controlled. For sheet TPMS structures whose performances are far from the isotropy properties, the TPMS units can be combined to generate composite TPMS, which can be further designed by the proposed Curvature-Wall thickness adjustment method. Experimental results verify the effectiveness and accuracy of the proposed approaches. Appropriate elastic modulus and ideal isotropy properties can be acquired at the same time.
Abstract Polyetheretherketone (PEEK) possesses a similar elastic modulus as bones but yet suffers from bio-inertness and poor osteogenesis. In this work, tantalum ions are implanted energetically ...into PEEK by plasma immersion ion implantation (PIII) to form Ta2 O5 nanoparticles in the near surface. Nanoindentation reveals that the surface elastic modulus of the Ta ion implanted PEEK is closer to that of human cortical bones. In vitro cell adhesion, alkaline phosphatase activity, collagen secretion, extracellular matrix mineralization, and real-time PCR analyses disclose enhanced adhesion, proliferation, and osteogenic differentiation of rat bone mesenchymal stem cells (bMSCs) on the Ta-PIII modified PEEK. In vivo evaluation of the cortico-cancellous rat femur model by means of micro-CT, sequential fluorescent labeling, and histological analysis after 8 weeks confirms significantly improved osteointegration. The bone-like elastic modulus and modified surface topography of the Ta-PIII modified PEEK synergistically induce osteogenic differentiation of bMSCs and the surface-modified materials have large potential in dental and orthopedic implants.
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•Hydrate formed on soft and stiff solid surfaces shows distinct adhesion strengths.•Adhesion strength of hydrate on soft substrates is greatly dictated by the shear loading ...rate.•Adhesion strength of hydrate on stiff substrates is greatly affected by the elastic modulus of the substrates.
Hydrate formation and accumulation pose significant challenges in oil and gas pipelines, leading to flow assurance issues and safety hazards. It is crucial to understand hydrate adhesion to prevent the accretion of hydrate in petro-pipelines. In this study, the adhesion strength (AS) of tetrahydrofuran (THF) hydrate on various solid surfaces with different elastic moduli subjected to shear loading rates ranging from 10 to 10000 μm/s is comprehensively investigated by shear force experimental measurements and finite element (FE) simulations. The results reveal that the hydrate AS is primarily influenced by the elastic modulus of the substrates, and the shear-induced detachment properties are strongly dependent on the shear loading rate. Specifically, when the hydrate is synthesized on a soft polydimethylsiloxane (PDMS) substrate, the AS exhibits minimal changes at low and high shear loading rates. However, under intermediate shear loading rates, the AS rapidly increases by approximately 500 %. In contrast, when the hydrate is formed on stiff polytetrafluoroethylene (PTFE) and polyethylene (PE) substrates, the AS is increased by approximately 200 % and 230 %, respectively as shear loading rate increases. Interestingly, for the hydrate on a stiff hydrophobic coated glass slide (CG) substrate, the AS anomalously decreases with increasing shear loading rates. These findings provide valuable insights into the effects of substrate properties and shear loading rate on hydrate adhesion. The results are of significance for the design of optimal coatings that ensure flow assurance of oil and gas in pressure-variant petro-pipelines.
•Waste rubber fiber used for partial replacement of fine aggregate in concrete.•Effect of elevated temperature on the properties of waste rubber fiber concrete is examined.•Strength, modulus of ...elasticity, water permeability and chloride diffusion were studied.•Inclusion of rubber fiber causes higher reduction in properties of concrete on exposure to elevated temperature.•Temperature higher than 150°C leads to decomposition of rubber fiber in concrete.
Accumulation of the waste tire is a major problem as degradation of these tires is extensively difficult. The results of experimental studies available for rubberized concrete provide a strong recommendation for the use of this waste where strength is not a major concern. The effect of partial replacement of fine aggregate by waste rubber fiber on the properties of concrete subjected to elevated temperature has been evaluated in this paper. A systematic experimental investigation has been carried out to evaluate the effect of elevated temperature on compressive strength, mass loss, static modulus of elasticity, dynamic modulus of elasticity, water permeability and chloride-ion permeability of control mix (no replacement of fine aggregate by rubber fiber) and waste rubber fiber concrete. Two types of cooling, normal cooling and fast cooling have been considered for the effect on compressive strength. Six levels of temperature with three exposure durations have been considered in this study for all the specimens. Microstructure analysis of waste rubber fiber concrete has also been carried out to investigate the effect of elevated temperature on crack pattern and bonding of rubber fiber and cement matrix.
Lutetium disilicate (Lu2Si2O7) is considered a promising material for environmental barrier coatings because of its remarkable high-temperature stability and low thermal conductivity. In this study, ...nanostructured Lu2Si2O7 coating was prepared successfully using as-prepared feedstocks via atmospheric plasma spraying. The nanomechanical performance of the coating was studied. The results showed that the coating exhibited a bimodal nanomechanical performance attributed to the bimodal distribution of its microstructure; i.e., in the coating, the melted lamella exhibited higher elastic modulus and nanohardness, whereas the unmelted and semi-melted parts processed low elastic modulus and nanohardness. The elastic modulus and nanohardness of the coating were 143.438 ± 25.449 GPa and 9.239 ± 3.514 GPa, respectively. Furthermore, the elastic and plastic works were 9.018–14.752 nJ and 12.792–25.793 nJ, respectively. The average value of the microhardness dissipation parameter of the coating was 0.615, demonstrated that the remarkable wear resistance of the coating.
The first-principle calculations were selected to investigate the structure, elastic modulus, electronic properties and thermodynamic properties of three W3Si cubic structures (Pm-3m, Fm-3m and ...Pm-3n). The influence of pressure on the stability and elastic modulus of W3Si is further studied. Two novel W3Si phases: Pm-3m and Fm-3m are firstly found. The order of thermodynamic stability is Pm-3n > Fm-3m > Pm-3m. The bulk modulus and shear modulus of Pm-3n structure are up to 306.8 GPa and 157.1 GPa, respectively. In particular, the elastic modulus of Pm-3n structure is bigger than the Pm-3m and Fm-3n structures at the range of whole pressure. Compared to Pm-3m and Fm-3m structures, the high elastic modulus of Pm-3n structure is attributed to the role of the W–W and W–Si bonds. The high-temperature thermodynamic properties of W3Si are attributed to the vibration of Si atom. Finally, the order of Debye temperature is Pm-3n > Fm-3m > Pm-3m.
In this work, glass samples were obtained by melt-quenching in the binary system (100-x)KPO3-xNb2O5 with x = 20, 30, 40, and 50 mol%. Thermal properties investigated by DSC together with structural ...investigations by Raman spectroscopy allowed to understand the structural effect of Nb2O5 incorporation in the potassium phosphate glass network. A transparent glass-ceramic has also been produced by heat treatment of the 50KPO3–50Nb2O5 glass sample. Density, molar volume, atomic packing, and refractive index were determined and increased with Nb2O5 content. Chemical resistance in several corrosive aqueous solutions was found to increase with Nb2O5 content and crystallization. Vickers hardness as well as elastic modulus and hardness obtained from nanoindentation experiments also strongly increased with higher niobium contents, indicating that not only optical properties but also chemical and mechanical properties are improved with niobium incorporation in the phosphate glass network.
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