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In order to enhance the interfacial-adhesion between short E-glass fibers and low-density polyethylene (LDPE), acidic whey; a dairy byproduct was applied as coupling agent. The fibers were immersed in acidic whey for 12, 24, 36, 48 and 60 hours. Composite materials containing 20 wt.% E- glass fibers and LDPE were prepared by extrusion process. The tensile strength and modulus of the produced composites were improved by using acidic whey, and the improvement in those properties was strongly affected by the immersion time of E-glass fibers in acidic whey. An increase of about 289%, 107%, 291% and 721% in modulus of elasticity, tensile strength, modulus efficiency and strength efficiency factors respectively were achieved after 60 hours of immersion of glass fibers in acidic whey. The effects of acidic whey on tensile properties and efficiency factors could be ascribed to the mend in interfacial-adhesion between glass fibers and LDPE polymer. [ABSTRACT FROM AUTHOR]

Native and carbonized freeze‐cast bacterial cellulose‐alginate (BC‐ALG) foams possess an ice‐templated honeycomb‐like architecture with remarkable properties. Their unique pore morphology consists of two levels of porosity: 20–50 µm diameter pores between, and 0.01–10 µm diameter pores within the cell‐walls. The mechanical properties of the BC‐ALG foams, a Young's modulus of up to 646.2 ± 90.4 kPa and a compressive yield strength of up to 37.1 ± 7.9 kPa, are high for their density and scale as predicted by the Gibson–Ashby model for cellular materials. Carbonizing the BC‐ALG foams in an inert atmosphere at 1000–1200 °C in a second processing step, both pore morphology and mechanical properties of the BC‐ALG remain well preserved with specific mechanical properties that are higher than those reported in the literature for similar foams. Also the electrical conductivity of the BC‐ALG foams is high at 1.68 ± 0.04 S cm−1 at a density of only 0.055 g cm−3, and is found to increase with density as predicted, and as a function of the degree of carbonization determined by both carbonization temperature and atmosphere. The property profile makes freeze‐cast BC‐ALG foams and their carbonized foams attractive for energy applications and as a sorbent. [ABSTRACT FROM AUTHOR]

Using the developed methodology for calculating hybrid (metal-polymer) plain bearings, a study of the effect of temperature on the contact parameters and their resource was conducted. Metal-polymer bearings with a bushing made of polyamide PA6 reinforced with glass or carbon dispersed fibers were considered. The calculation of the maximum initial contact pressures and their change due to wear of the bushing was performed. The predictive estimate of resource of the investigated bearings at various loadings was carried out. Quantitative and qualitative patterns of changes in the maximum initial contact pressures and bearing resource with increasing temperature were established. Studies show that the decrease in the modulus of elasticity due to increasing temperature leads to a decrease in the maximum pressure and increase the resource of metal-polymer bearings, which is useful. This phenomenon is due to a decrease in the rigidity of the polymer composite. [ABSTRACT FROM AUTHOR]

Cheddar cheese,rennet casein,camellia seed oil were used as the main raw materials,emulsified salt,skimmed milk powder,etc.as auxiliary materials to develop spread processed cheese.A single factor method was used to add different amounts of camellia seed oil to prepare the spread processed cheese.The storage modulus (G′) and loss modulus (G″) of spread processed cheese under different oscillation frequencies were studied,The difference of the critical point temperature (melting temperature) of viscoelastic change of processed cheese with different amount of camellia seed oil was observed.The results showed that G'and G'' of the spread processed cheese decreased with the increase of camellia seed oil,and the temperature at which the products reached the critical point of viscoelastic change also decreased.The sample with the added amount of camellia seed oil below 50% was more stable.

Calotropis Gigantea (CG) is a shrub plant that grows rampantly in South Asia. Here we report the development of CG bast fibre yarns, which could yield replacements for artificial fibres in engineering applications. Most of the researchers concentrated only in the short form of natural fibres, this leads to dropping the fibre reinforcement in continuous and lengthy products. An attempt has been made in this research by taking CG fibre in the form of twisted yarn as reinforcement. The surface treatment is done to enhance the properties of the CG fibres and to reduce hydrophilic and hygroscopic behaviour using NaOH (aq.). Determining the appropriate NaOH concentration in the treatment solution is essential to reduce the hydrophilicity of the fibres while retaining its mechanical properties. Generally optimised NaOH concentration found by completing fibre characterization, which is a very lengthy and time-consuming process. In this research work, the optimum concentration of NaOH found by a quick and short process using simple techniques. Two techniques were used such as Contact angle measurement of fibre surface and microscopic observation of xylem structure to find an optimum concentration of NaOH in the aqueous solution. On treated CG fibres, the contact angle is found to be as high as 112° for 4 wt.% NaOH (aq.) concentration; indicating that the treatment renders the fibre hydrophobic and the observation of xylem structure (voids) confirms in a minimum amount in the same 4 wt.% NaOH treated fibre. The mechanism involved is rationalized using infrared/vibrational spectroscopy based measurements of untreated and treated sampled. The orientation of the fibre helps with optimization of the properties. The elastic modulus (measured as per ASTM standards) obtained are 4.18 GPa (along the fibres) and 3.05 GPa (perpendicular to the fibres).

Objective: To construct a porous titanium-based implant with good biocompatibility and appropriate modulus matching human bone. Methods: Porous titanium with triangular, quadrangular and hexagonal prism as structure monomer were constructed by 3D printing, and the effects of pore structures on the mechanical and biological properties of materials were investigated by computational simulation, mechanical property tests and cell adhesion and proliferation tests. Results: The modulus of titanium with quadrangular monomer was the closest to that of human bone. Besides, the quadrangular sample also shows the best cytocompatibility, presenting the most promotion effects on cell proliferation. Conclusion: The porous titanium constructed by quadrangular monomer has the best comprehensive performance, and the relevant results can provide data support for the design and clinical application of 3D printing porous titanium-based implants. [ABSTRACT FROM AUTHOR]

A lead free polycrystalline double perovskite-based ceramic oxide Ca2BiNbO6(CBNO) was synthesized by the conventional solid state reaction route. Emergence of a new single-phase double perovskite structure exhibiting cubic phase with space group fm-3 m was confirmed through the room temperature XRD analysis. Particle size of 34.29 nm was obtained using Scherrer's formula. Different electrical parameters such as complex impedances, modulus, dielectric (εr and tanδ) and conductivity were recorded carefully by the LCR analyzer for a wide range of temperatures (25–500 ø°C) and frequencies (100 Hz–5 MHz), respectively. Large room temperature dielectric constant with a NTCR property was investigated. The ferroelectric nature with a transition temperature above 300 °C was analyzed from the study. The thermal dependent conductivity fitted curve satisfies the Arrhenius law and leads to a calculated activation energy of 0.0597 eV. The obtained result promotes this new material to be a favorable candidate to uses in smart and modern electronic device applications. [ABSTRACT FROM AUTHOR]

The mechanical characterization of brain tissue has been generally analyzed in the frequency and time domain. It is crucial to understand the mechanics of the brain under realistic, dynamic conditions and convert it to enable mathematical modelling in a time domain. In this study, the compressive viscoelastic properties of brain tissue were investigated under time and frequency domains with the same physical conditions and the theory of viscoelasticity was applied to estimate the prediction of viscoelastic response in the time domain based on frequency-dependent mechanical moduli through Finite Element models. Storage and loss modulus were obtained from white and grey matter, of bovine brains, using dynamic mechanical analysis and time domain material functions were derived based on a Prony series representation. The material models were evaluated using brain testing data from stress relaxation and hysteresis in the time dependent analysis. The Finite Element models were able to represent the trend of viscoelastic characterization of brain tissue under both testing domains. The outcomes of this study contribute to a better understanding of brain tissue mechanical behaviour and demonstrate the feasibility of deriving time-domain viscoelastic parameters from frequency-dependent compressive data for biological tissue, as validated by comparing experimental tests with computational simulations. [ABSTRACT FROM AUTHOR]

This study investigates the flatwise compressive performance of the developed sandwiches with core stitching modification. Polyvinyl chloride (PVC) foam cores with a density of 0.048 g/cm3 were stitched with 600-tex glass fiber yarns. Then the core materials were sandwiched with carbon/epoxy and glass/epoxy face sheets, respectively. The composite sandwich structures were produced by applying the vacuum bag method, and the composite layers were co-cured. The non-stitched foam core sandwiches were also manufactured as the benchmark. The developed sandwich panels were subjected to flatwise compression tests per the ASTM C365 Standard to obtain compressive properties. The mechanical testing showed that the stitched foam core sandwiches carried dramatically higher compressive loads and presented additional load peaks. Almost 80% and 90% enhancement were achieved in resistance to compressive forces for the sandwiches made of carbon/epoxy and glass/epoxy face sheets, respectively. Also, the increments in the compressive strength of the developed sandwich panels were found above 80% with a minimum weight penalty. Core stitching, providing the sandwich panels to have better out-of-plane strength, is a simple and less time-consuming through-thickness reinforcement process among the other core modification methods. [ABSTRACT FROM AUTHOR]

We focus on two topics that are related to moduli of elements in partially ordered vector spaces. First, we relate operators that preserve moduli to generalized notions of lattice homomorphisms, such as Riesz homomorphisms, Riesz* homomorphisms, and positive disjointness preserving operators. We also consider complete Riesz homomorphisms, which generalize order continuous lattice homomorphisms. Second, we characterize elements with a modulus by means of disjoint elements and apply this result to obtain moduli of functionals and operators in various settings. On spaces of continuous functions, we identify those differences of Riesz* homomorphisms that have a modulus. Many of our results for pre-Riesz spaces of continuous functions lead to results on order unit spaces, where the functional representation is used. [ABSTRACT FROM AUTHOR]

The damping properties of as-cast and austempered Al-alloyed ductile iron produced by rotary furnace melting process and sand casting technique were investigated. Two Al-alloyed ductile irons, which contain 2.29 wt% Al and 3.02 wt% Al, were produced and test samples were machined, followed by heat treatment process. The samples were subjected to both conventional single step and two-step austempering processes. The microstructure of the Al-alloyed ductile irons, after chemically analysed, was characterized using scanning electron microscopy, while the storage modulus, loss modulus and damping capacity were evaluated using a dynamic mechanical analyser of model DMA 242E (Artemis) with NETZSCH format, using three-point bending mode procedure in accordance with ASTM E756-05. It was found that the ausferrite structure of the Al-alloyed ductile iron exhibited improved damping capacity than the pearlite-based Al-alloyed ductile iron of the same composition. Also, the two-step austempered Al-alloyed ductile iron yielded more improved damping capacity values of 0.23194 (1 Hz) and 0.23351 (5 Hz), respectively, at room temperature than the as-cast ductile irons investigated in this study. [ABSTRACT FROM AUTHOR]

Nanoparticle (NP) stiffness has been shown to significantly impact circulation time and biodistribution in anticancer drug delivery. In particular, the relationship between particle stiffness and tumor accumulation and penetration in vivo is an important phenomenon to consider in optimizing NP-mediated tumor delivery. Layerby- layer (LbL) NPs represent a promising class of multifunctional nanoscale drug delivery carriers. However, there has been no demonstration of the versatility of LbL systems in coating systems with different stiffnesses, and little is known about the potential role of LbL NP stiffness in modulating in vivo particle trafficking, although NP modulus has been recently studied for its impact on pharmacokinetics. LbL nanotechnology enables NPs to be functionalized with uniform coatings possessing molecular tumor-targeting properties, independent of the NP core stiffness. Here, we report that the stiffness of LbL NPs is directly influenced by the mechanical properties of its underlying liposomal core, enabling the modulation and optimization of LbL NP stiffness while preserving LbL NP outer layer tumor-targeting and stealth properties. We demonstrate that the stiffness of LbL NPs has a direct impact on NP pharmacokinetics, organ and tumor accumulation, and tumor penetration--with compliant LbL NPs having longer elimination half-life, higher tumor accumulation, and higher tumor penetration. Our findings underscore the importance of NP stiffness as a design parameter in enhancing the delivery of LbL NP formulations. [ABSTRACT FROM AUTHOR]

This paper is aimed at studying the thermal properties of poly(lactic acid), PLA with different plasticizers. Plasticized PLA was obtained by mixing and extruding PLA with 20 mass% of neat cardanol, epoxidized cardanol acetate (ECA) and poly(ethylene glycol) (PEG) 400. The glass transition of completely amorphous samples, melting and crystallization behavior of plasticized PLA were analyzed by differential scanning calorimetry. Results obtained show that, below Tg, a higher enthalpy relaxation occurs for PLA plasticized by cardanol derivatives. This is indicative of a faster mobility of PLA chains below Tg, when cardanol derivatives are used as plasticizers. On the other hand, an opposite behavior was observed for the crystallization studies. In facts, a much faster crystallization was found for PLA plasticized by PEG, which in turn indicates a much higher mobility of PLA chains above Tg compared to PLA plasticized by cardanol derivatives. Mechanical properties obtained on completely amorphous samples show that PLA plasticized by ECA is characterized by lower modulus, which is indicative of a more efficient plasticization. On the other hand, the thicker crystals formed during crystallization of PLA plasticized by ECA involve a more relevant increase in the modulus in semicrystalline samples. [ABSTRACT FROM AUTHOR]

This study presents a rigorous approach for the extraction of the modulus of soil and unbound aggregate base materials for quality management using intelligent compaction (IC) technology. The proposed approach makes use of machine-learning methods in tandem with IC technology and modulus-based spot testing as a local calibration process to estimate the mechanical properties of compacted geomaterials. A calibrated three-dimensional finite element (FE) model that simulates the proof-mapping process of compacted geomaterials was used to develop a comprehensive database of responses of a wide range of single and two-layered geosystems. The database was then used to develop different inverse solvers using artificial neural networks for the estimation of the modulus from the characteristics of the roller and information about the geomaterials. Several instrumented test sites were used for the evaluation and validation of the inverse solvers. The proposed approach was found promising for the extraction of the modulus of compacted geomaterials using IC. The accuracy of the inverse solvers is enhanced if a local calibration process is incorporated as part of a quality management program that includes the use of in situ measurements using modulus-based test devices and laboratory resilient modulus testing. Moreover, compaction uniformity plays a key role in the retrieval of the modulus of geomaterials with certainty. The proposed approach fuses artificial intelligence with mechanistic solutions to position IC as a technology that is well suited for the quality management of compacted materials. [ABSTRACT FROM AUTHOR]

Natural fibers such as banana, sisal, snake grass, coir, hemp, jute and so on are armed with enormous advantages like less weight, reliability, recyclability and environmental friendly nature. Such fibers may enhance the system’s performance by acting as additives with the thermoplastics in different perspectives. Besides the natural composites, hybrid composites facilitate the design of material with specific property matched to an application. In the present work an attempt has been made to manufacture and test the banana and snake grass short fiber reinforced hybrid polyester composites in random orientation and random lay-up. Methyl Ethyl Ketone Peroxide was used as the coupling agent and Cobalt Naphthalene as the catalyst. Hand layup technique was used to manufacture the composites. Relative volume fraction of the fibers was varied between 2.5-12.5% in the ratio 1:1. Properties like tensile strength and modulus, flexural strength and modulus are measured for the composites by conducting the appropriate tests according to ASTM standards.

Among La1-xCaxFeO3-δ (0 ≤ x ≤ 0.5) compounds, the optimal value of the direct current conductivity was registered for a 20% substituted amount. We therefore attempted to study the impedance and dielectric properties of 20% calcium-substituted lanthanum ferrite. We investigated the electric properties in depth between 5 Hz and 13 MHz from 350 to 800°C. The results reveal interesting properties. Indeed, the perovskite shows a huge dielectric constant which promotes its utilization in high-performance dielectric material applications. At a given temperature, ε’ and tan(δ) decrease with increases in frequency. This trend was explained based on the Maxwell Wagner polarization model. The variations in dielectric loss (ε”) with frequency obey the Giuntini theory based on the hopping model. As the temperature increases from 350 to 800°C, the binding energy increases from 0.22 to 0.34 eV, while the minimum hopping distance decreases from 2.16 to 0.12 pm. Consideration of the electric modulus analyzes showed that the relaxation mechanism is dominated at below 400°C by a short-range movement of charge carriers, whereas at above that temperature, a long-range movement of charge carriers is dominant. This study presents a solid foundation for the polarization and dielectric properties of lanthanum ferrite, which is a lead-free, environmentally friendly material and a promising candidate for use in nonlinear optical applications and microwave devices.

The quality of bituminous binders is commonly evaluated by the empirical tests. The functional approach to the evaluation of bitumen properties is a trend that has been applied in the last years. The dynamic shear rheometer (DSR) test has been widely used to determine the shear complex modulus of bitumen in the wide range of frequencies and temperatures. A lot of research works were focused on the effect of the chemical compounds of bitumen on the values of the shear complex modulus. The missing information related to the effect of the compound of bitumen on the elastic and plastic part of the shear complex modulus was input for the presented investigation. The significant effect on the elastic part of the complex modulus was determined only at the high temperatures (60 and 80 °C). The aromatics, resins and asphaltenes were identified as the influencing compounds. The important effect was also noted for the resins at the temperatures of 5 and 15 °C. It was also concluded that the effect of the saturates on the elastic part of the shear complex modulus is marginal. The effect of the aromatics and asphaltenes on the plastic part of the shear complex modulus was identified only at the temperature of 80 °C. The effect of these two compounds at other temperatures seems to be unimportant. The significant effect of the resins was stated for the temperatures of 15 °C and 5 °C. Their effect at other temperatures can be supposed as marginal. The negligible effect of the saturates on the plastic part of the shear complex modulus was deducted.

In this work, Gd2O3 bulks were sintered at temperatures ranging from 1400 °C to 1600 °C for times from 6 h to 24 h, and their microstructure and properties were studied for a wider application of materials in thermal barrier coatings. The densification of the Gd2O3 bulk reached 96.16% when it was sintered at 1600 °C for 24 h. The elastic modulus, hardness, fracture toughness and thermal conductivity of the bulks all increased with the rise in sintering temperature and extension of sintering time, while the coefficient of thermal expansion decreased. When the Gd2O3 bulk was sintered at 1600 °C for 24 h, it had the greatest elastic modulus, hardness, fracture toughness and thermal conductivity of 201.15 GPa, 9.13 GPa, 15.03 MPa·m0.5 and 2.75 W/(m·k) (at 1100 °C), respectively, as well as the smallest thermal expansion coefficients of 6.69 × 10−6/°C (at 1100 °C).

The melt-quenching technique was used to synthesize tellurite glasses of the chemical composition 80TeO2-(20-x) ZnO-xV2O5. X-ray diffraction (XRD) patterns indicate the amorphous nature of the prepared glasses. Raman and FTIR measurements demonstrate a progressive substitution of the Te-O-Te linkages by the Te-O-V bridges and the formation of VO4 and VO5 units by a change of the vanadium coordination due to the higher number of oxygens incorporated by further addition of V2O5. The AC conductivity was investigated in the frequency range of 40 Hz to 107 Hz between 473 K to 573 K. A good coherence of the AC conductivity was found using a model correlating the barrier hopping (CPH) and the dominant conduction process changes from ionic to polaronic with the addition of V2O5. The dielectric constant exhibits high values in the range of lower and medium frequencies. Both variations of the electric modulus and the dielectric loss parameters with frequency and temperature showed a relaxation character mainly assigned to the vanadate phases. The electric modulus displays a non-Debye dielectric dispersion and a relaxation process. The present results open the door to future zinc-tellurite glasses-doped vanadium exploitation as a potential electrolyte-based material for solid-state batteries.

Polymeric hydrogels have drawn considerable attention as a biomedical material for their unique mechanical and chemical properties, which are very similar to natural tissues. Among the conventional hydrogel materials, self-healing hydrogels (SHH) are showing their promise in biomedical applications in tissue engineering, wound healing, and drug delivery. Additionally, their responses can be controlled via external stimuli (e.g., pH, temperature, pressure, or radiation). Identifying a suitable combination of viscous and elastic materials, lipophilicity and biocompatibility are crucial challenges in the development of SHH. Furthermore, the trade-off relation between the healing performance and the mechanical toughness also limits their real-time applications. Additionally, short-term and long-term effects of many SHH in the in vivo model are yet to be reported. This review will discuss the mechanism of various SHH, their recent advancements, and their challenges in tissue engineering, wound healing, and drug delivery.

We demonstrate that, within any computable presentation of the Banach space C [ 0 , 1 ] , computing 1 is no harder than computing the halting set. Additionally, we prove that the modulus operator | · | is Ø ″ -computable and use this to show that C [ 0 , 1 ] is Δ 3 0 -categorical when we restrict ourselves to the presentations in which at least one homeomorphism of the unit interval onto itself is computable. [ABSTRACT FROM AUTHOR]

The present work reports formation of polyurethane (PUR) and carboxylic functionalized graphene (COOH‐fG) nanocomposites via solution mixing method and static and dynamic mechanical characterization with dynamic mechanical analysis (DMA), nano indentation, and tensile and compressive testing. Magnetic stirring of the solutions of PUR in N,N dimethylformamide (DMF) and COOH‐fG in DMF was performed for different compositions of filler, 1%, 3%, 5%, 7%, and 10%, which were heated to obtain nanocomposite films followed by injection molding to cast into samples. Uniform dispersion and good intercalation were observed upon characterization by field emission scanning electron microscopy and X‐ray diffraction techniques. DMA showed that the storage modulus improved with increasing frequency of loading, and a linear decrement in the damping factor with an increase in the concentration of filler was observed. The maximum depth of indent in nano‐indentation test showed a decreasing trend, indicating improvement in nanohardness and elastic modulus with an optimum obtained at 5 wt% composition. An improvement in tensile modulus, tensile strength, and toughness, which were more substantial at lower compositions of filler, was observed. An optimum compressive modulus was obtained for 10 wt% of filler due to more resistance provided by graphene plates to compression as compared to PUR. [ABSTRACT FROM AUTHOR]

Aluminium matrix hybrid composites have been consolidated effectively by spark plasma sintering with new combinations of reinforcement and high volume percentage of ceramic particulates to maximize specific hardness and specific modulus through the powder metallurgy route. The aforementioned techno‐scientific accomplishment with regard to metal matrix composite aims to meet a continuous increase in the global demand for a material with minimum structural weight and high‐modulus for structural (automotive and aerospace) applications. The new aluminium based hybrid composite developed by incorporating ceramic particulate reinforcements (12.5 wt.% silicon carbide and 12.5 wt.% titanium carbide) along with 22.5 wt.% copper as the metallic reinforcement attains significantly high specific hardness (85 HV/gcm−3), specific Young's modulus (33.56 GPa/g cm−3), specific bulk modulus (27.97 GPa/g cm−3) when compared with the reported range of specific hardness (13 HV/g cm−3–89 HV/g cm−3), specific Young's modulus (24 GPa/g cm−3–27 GPa/g cm−3) and specific bulk modulus (20 GPa/g cm−3–22 GPa/g cm−3) possessed by structural steels. This is accredited to the genesis of a novel microstructure that consists of fine copper, silicon carbide and titanium carbide particulates together with a nominal in‐situ originated aluminium‐copper equilibrium phases distributed in a highly substructured aluminium based matrix with a significant dislocation density (7.56 ⋅ 1014 m‐2). [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on a review of the literature (including the geography of specialized research centers), the prehistory and problems of the study of thermal effects in polyepoxides are shown. It is shown that the main research database is now concentrated in 50-60 research centers in India, China, Middle East, the ex-USSR and the EU countries. The article summarizes the results of experiments on hardening a standard bisphenol epoxy-amine polymer. The existence of inorganic microfillers, which impart hardening properties to the epoxy, especially after destructive critical (250 - 300 °C) temperatures, is shown. These include inorganic binders (gypsum and cement), carbides and nitrides (SiC, TiN), metal microparticles (Fe). The ability of the epoxy polymers filled with them to harden or plasticize under the action of critical destructive temperatures, is proposed to be called "thermal hardening" and "thermal plasticization" of epoxy-composites. The work gives examples of these effects on specific compositions with 50 wt% fillers. The creation of these filled compositions makes it possible to expand the temperature range of the practical application of epoxy polymers - in areas with high requirements for the thermal stability of materials. [ABSTRACT FROM AUTHOR]

Copyright of Annals of Warsaw University of Life Sciences - SGGW, Forestry & Wood Technology is the property of Wydawnictwo SGGW and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Blast furnace ferronickel slag (BFNS), currently an underutilized metallurgical residue, was investigated for use as a precursor for alkaline activation. Water glass solutions with various moduli (0.5, 1.0, 1.5 and 2.0) were used at the same water glass concentration of 10% to investigate the influence of the modulus on hydration and mechanical properties. The results show that the modulus has a certain impact on the hydration and mechanical strength development of alkali-activated BFNS. Increasing the modulus of water glass does not change the type of hydration product and the activity of the Mg-containing phases, but it decreases the amount of C2AS, the Ca/Si and Al/Si ratios of the (N,C)-A(M)-S-H gel. In addition, a high silicate modulus deteriorates the pore structure, which has an adverse effect on the development of compressive strength and splitting tensile strength.

In this paper, we present an extensive experimental study on the dynamic mechanical properties of composites with polymer matrices, as well as a quantification of the parameters that influence these properties. Polymer-composite matrices make it possible to form any reinforcement arrangement of fibres, particles, and layers, which makes it possible to form composite materials with certain dominant mechanical properties according to the internal arrangement for the application. In this study, we focused on the dynamic properties (i.e., damping parameters, such as the loss factor (tan d), logarithmic decrement (λ), storage modulus (E′), and loss modulus (E″)) of composites with polymer matrices, including parameters such as the fibre material, fabric weaving, fibre orientation, temperature, frequency, particle size, volume of short fibres, and epoxy resin type. If other articles focus on one type of composite and 1–2 parameters, then the benefit of this article lies in our analysis of 8 mentioned parameters in the experimental analysis of 27 different types of composites with polymer matrices. The tested fibre materials were glass, aramid, and carbon; the tested woven fabrics were twill, plain, unidirectional, and satin; the temperature range was from −50 to +230 °C; the frequency was 1 Hz and 10 Hz; the particle size was 0.1–16 mm; the volume percentages of the short fibres were 3, 6, and 12 vol.% of the hybrid polymer composites and the type of polymer matrix. We used the free-damped-vibration method with vibration dynamic signal analysis and the forced-damped vibration of dynamic mechanical thermal analysis for testing. We ranked the parameters that influence the dynamic vibration properties according to the effects. Among sets of results provided in the paper, considering the storage modulus, loss modulus, and loss factor, the best results of the fibre composites were for aramid-fibre-reinforced polymers, regardless of the weave type, with an advantage for unidirectional fabric. The best results of the particle composites were for those with fine filler sizes that incorporated the short fibres.

To date, there have been a limited number of studies modeling the tensile modulus in the polymer halloysite nanotube (HNT) systems before or after percolation onset. In this paper, an equation for a composite’s modulus post-percolation onset was developed for HNT-filled samples including the interphase and HNT network. The dispersed nanoparticles and adjoining interphase part were neglected, because they caused ineffective influences on the stiffness of the system after percolation onset. The developed model reflects the impacts of HNTs’ size, interphase depth, percolation onset and the volume shares and moduli of the HNT network and its adjacent interphase on the modulus of HNT-based systems. The impacts of issues on the nanocomposite modulus are defendable, confirming the effectiveness of the developed model. HNT length, interphase depth, HNT concentration, net modulus and net portion directly influenced the stiffness, while the HNT radius and percolation onset had inverse effects. Results show that there was a 142% improvement in the modulus of samples at an interphase depth of 40 nm. Moreover, the stiffness improved by 60% at a net modulus of 200 GPa, but it later exhibited a 180% enhancement at a net modulus of 1000 GPa. In addition, the experimental data for the modulus of numerous composites display fine agreement to the predictions, confirming the validity of the developed model.

Polycrystalline Na0.9Ba0.1Nb0.9(Sn0.5Ti0.5)0.1O3 is prepared by the solid-state reaction technique. The formation of single-phase material was confirmed by an X-ray diffraction study and it was found to be a tetragonal phase at room temperature. Nyquist plots (Z′′ versus Z′) show that the conductivity behavior is accurately represented by an equivalent circuit model which consists of a parallel combination of bulk resistance and constant phase elements (CPE). The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law. The conductivity σdc follows the Arrhenius relation. The modulus plots can be characterized by the empirical Kohlrausch–Williams–Watts (KWW), φ(t) = exp( − (t/τ)β) function and the value of the stretched exponent (β) is found to be almost independent of temperature. The near value of activation energies obtained from the analyses of modulus and conductivity data confirms that the transport is through an ion hopping mechanism dominated by the motion of the (O2−) ions in the structure of the investigated material.

Marginal hard asphalt possesses high stiffness and modulus; however, due to poor ductility at low temperature, it was seldom applied into road structures. Increasing asphalt content seemed to be an effective way to minimize the thermal cracking problem of hard hot-mix asphalt (HMA). Therefore, three types of methods (Groups 2–4) aiming to improve hard asphalt content were designed and compared with the traditional method (Group 1). Specifically, Groups 2 and 3 were designed with coarser gradation and lower gyration levels (Ndes), respectively, and Group 4 was designed following the enrobé à module élevé 2 (EME2) method. The high- and low- temperature, fatigue, modulus, and cracking performance were then conducted for each group. It can be seen that with the increase of asphalt content, the low-temperature strain increased in all three groups, of which Groups 2 and 3 improved more significantly. In addition, with the coarser gradation or lower Ndes , the high-temperature and cracking resistance of hard HMAs was lost to some degree; however, they can still compete with traditional neat HMAs. The hard HMAs designed with EME2 method performed excellent dynamic modulus and rutting resistance. Moreover, the hard HMAs designed with EME2 method and lower Ndes showed a surprising improvement in the fatigue life. These results may contribute to the better use of hard HMAs. [ABSTRACT FROM AUTHOR]

Macromolecular components of the vascular extracellular matrix (ECM), particularly elastic fibers and collagen fibers, are critical for the proper physiological function of arteries. When the unique biomechanical combination of these fibers is disrupted, or in the ultimate extreme where fibers are completely lost, arterial disease can emerge. Bioengineers in the realms of vascular tissue engineering and regenerative medicine must therefore ideally consider how to create tissue engineered vascular grafts containing the right balance of these fibers and how to develop regenerative treatments for situations such as an aneurysm where fibers have been lost. Previous work has demonstrated that the primary cells responsible for vascular ECM production during development, arterial smooth muscle cells (SMCs), can be induced to make new elastic fibers when exposed to secreted factors from adipose-derived stromal cells. To further dissect how this signal is transmitted, in this study, the factors were partitioned into extracellular vesicle (EV)-rich and EV-depleted fractions as well as unseparated controls. EVs were validated using electron microscopy, dynamic light scattering, and protein quantification before testing for biological effects on SMCs. In 2D culture, EVs promoted SMC proliferation and migration. After 30 days of 3D fibrin construct culture, EVs promoted SMC transcription of the elastic microfibril gene FBN1 as well as SMC deposition of insoluble elastin and collagen. Uniaxial biomechanical properties of strand fibrin constructs were no different after 30 days of EV treatment versus controls. In summary, it is apparent that some of the positive effects of adipose-derived stromal cells on SMC elastogenesis are mediated by EVs, indicating a potential use for these EVs in a regenerative therapy to restore the biomechanical function of vascular ECM in arterial disease. [ABSTRACT FROM AUTHOR]

Sodium silicate is one of the common alkali activators of geopolymers. The modulus, concentration and dosage of sodium silicate have significant effects on the activation of fly ash, the strength and microstructure of geopolymer. In this paper, unconfined compressive strength test, X-ray diffraction analysis (XRD), Fourier transform infrared light (FTIR), 29Si nuclear magnetic resonance (29Si NMR), scanning electron microscope and energy disperse spectroscopy (SEMEDS), and physisorption experiment (BET) were carried out to study the effects of the sodium silicate modulus and dosage on the mechanical property and microstructure of fly ash-based geopolymer. The results indicated that the main product of the geopolymer activated by sodium silicate was hydrated sodium aluminosilicate (N-A-S-H). When modulus value decreased and meanwhile dosage of sodium silicate increased, the reorganization and polymerization of gel products were accelerated so that the integrity and continuity of the microstructure of geopolymer were improved, and then the strength increased. When the modulus of sodium silicate was 3.28, the maximum value of the strength was at the dosage of 10%. According to this study, it was investigated that modulus value and dosage of sodium silicate had obvious influence on the alkali- activated reaction of fly ash, which can provide an engineering reference for the special soil solidification with geopolymers. [ABSTRACT FROM AUTHOR]

This work attempts to estimate the effect of the reinforcement percentage on Young's modulus for membranes of polymer‐clay nanocomposites (PCNs). Models tried to simulate different contents of the reinforcement for experimentally obtained PCNs with nanometric montmorillonite clays (MMT) incorporated into a polynorbornene dicarboximide matrix. The analyses were carried out modeling through discrete element method (DEM) and finite element analysis (FEA) volume fractions from 0.01 to 0.025 of elliptical MMT nano‐platelets with aspect ratios = 0.2 (1000 × 500 nm) and thicknesses of 1 nm. These models were generated using as starting point the morphology and distribution of the reinforcements observed in scanning electron microscopy for experimental PCNs. Estimations were compared to predictions obtained by Rule of Mixtures and other mathematical models. Results showed that the elastic modulus of the nanocomposites significantly rises as MMT volume fraction increases. Besides, the use of DEM‐FEA generated the predictions closest to the experimental values, with relative errors lower than 10%. For the other models, the errors were significantly high, even reaching 100%. This shows the importance of DEM‐FEA to obtain a more accurate model of a real composite and a better estimation of its mechanical behavior. [ABSTRACT FROM AUTHOR]

Research on the vitreous humor and development of hydrogel vitreous substitutes have gained a rapid increase in interest within the past two decades. However, the properties of the vitreous humor and vitreous substitutes have yet to be consolidated. In this paper, the mechanical properties of the vitreous humor and hydrogel vitreous substitutes were systematically reviewed. The number of publications on the vitreous humor and vitreous substitutes over the years, as well as their respective testing conditions and testing techniques were analyzed. The mechanical properties of the human vitreous were found to be most similar to the vitreous of pigs and rabbits. The storage and loss moduli of the hydrogel vitreous substitutes developed were found to be orders of magnitude higher in comparison to the native human vitreous. However, the reported modulus for human vitreous, which was most commonly tested in vitro, has been hypothesized to be different in vivo. Future studies should focus on testing the mechanical properties of the vitreous in situ or in vivo. In addition to its mechanical properties, the vitreous humor has other biotransport mechanisms and biochemical functions that establish a redox balance and maintain an oxygen gradient inside the vitreous chamber to protect intraocular tissues from oxidative damage. Biomimetic hydrogel vitreous substitutes have the potential to provide ophthalmologists with additional avenues for treating and controlling vitreoretinal diseases while preventing complications after vitrectomy. Due to the proximity and interconnectedness of the vitreous humor to other ocular tissues, particularly the lens and the retina, more interest has been placed on understanding the properties of the vitreous humor in recent years. A better understanding of the properties of the vitreous humor will aid in improving the design of biomimetic vitreous substitutes and enhancing intravitreal biotransport. [ABSTRACT FROM AUTHOR]

Elaborating an instrumented nanoindentation is to exercise nondestructive tests to be applied to volumes of polymethylmetacrylate (PMMA) materials in miniature. This work focuses on factors that explain the trends variation of mechanical properties like Young's modulus (E), contact hardness (H) and indentation force (P). The evolution of E and H with depth (h) and P shows a 2.77 nm inflection point at low penetrations, separating two zones: the first increasing and the second decreasing. This is respectively explained by the surface hardening induced by preparing the material surface, and the existence of a surface hardness gradient denoted by an indentation size effect (ISE) observed at very low depths. Moreover, In addition, a critical penetration depth of 9.71 nm below which the surface effect dominates the variation of the penetrating load is detected. E and H results differences between dynamic and static modes are 8.46% and 6.44% inducing an overestimation of 35 MPa in E value, and an underestimation of 1.23 MPa in H value. This tends to affect the expected nanoscale precision of the indentation to determine the nanomechanical properties of PMMA. [ABSTRACT FROM AUTHOR]