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AbstractPoly (N-isopropyl acrylamide) (PNIPAm) and polyacrylamide (PAAm) are widely used in antifouling research because of their non-harmful nature and their high water-absorbing capacity. In addition, hydrogels such as these two, should be investigated for their mechanical properties because their mechanical properties influence the antifouling paint containing them remaining on the surface of the vessels. In this research PAAm, PNIPAm, and kappa carrageenan (κC) doped with graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) composite gels were examined for their mechanical properties for use in antifouling paints as a potential material. For increasing the mechanical properties of composites, GO and MWCNTs are often used as doping materials. In the research described here, a compressive test was used to determine the elasticity, and the modulus was calculated. The toughness was calculated from the slope of the stress-strain curve. The PAAm, PNIPAm, and κC doped with GO and MWCNT exhibited excellent swelling and deswelling behavior and good mechanical properties as composites. The results showed that the composites’ mechanical characteristics increased with an ideal loading concentration of GO and MWCNTs. This study was inspired by our belief of a shortage of research on antifouling materials that are sensitive to the environment. We wanted to create materials that were both effective against fouling and environmentally safe by integrating the beneficial characteristics of hydrogels with potential materials inside antifouling paint. This study, we suggest, is an important step toward the development of antifouling materials with high mechanical performance that are also environmentally friendly. [ABSTRACT FROM AUTHOR]

Carbonate gravelly soils are widely distributed in sub-tropical marine areas. During construction and engineering operations, carbonate gravel undergoes considerable particle crushing, which has remarkable effects on their engineering properties. A series of large-diameter oedometer tests, large-diameter drained and undrained triaxial shear tests were conducted on carbonate gravel specimens taken from the South China Sea. The carbonate gravel specimens exhibit significant particle crushing at common engineering pressure levels, and the particle crushing highly depends on the initial density, loading history and stress path. Three fragmentation modes, fracture, attrition, and abrasion, are notable in carbonate gravel specimens, which induces significant variations of PSD curves and greatly effects the mechanical properties. Particle crushing in carbonate gravel specimens increases the compressibility resulting in the compression index increases with the increase of surcharge pressure; decreases the pressure-hardening resulting in the initial Young's and secant moduli slightly increase with the increase of initial confining pressure; and decreases the dilatancy resulting in the peak and critical state friction angles significantly deceases with the increase of initial confining pressure. Particle crushing also shows great effect on the CSL of the carbonate gravel specimens in both p ′ - q space and e - p ′ space. [ABSTRACT FROM AUTHOR]

It is known that if L is a Dedekind complete Riesz space and (Ω, Σ) is a measurable space, then the partially ordered linear space of all L-valued, finitely additive and order bounded vector measures m on Σ is also a Dedekind complete Riesz space (for the natural operations). In particular, the modulus |m|o of m exists in this space of measures and |m|o is given by a well known formula. Some 20 years ago L. Drewnowski and W. Wnuk asked the question (for L not Dedekind complete) if there is an m for which |m|o exists but, |m|o is not given by the usual formula? We show that such a measure m does indeed exist. [ABSTRACT FROM AUTHOR]

BaBi4Zr2Sn2O15, a modified ceramic sample belonging to the oxide family of layered ferroelectrics, is synthesized using the mixed oxide process after firing for calcination at 810 °C for 6 hrs. XRD study of the compound exhibits the growth of an orthorhombic single-phase structure at atmospheric temperature. The electrical properties of the sample are investigated in a broad temperature range (30–500 °C) and frequency range (100 Hz - 106 Hz). The dielectric properties recommend the transition from ferro to paraelectric state at 410 °C which is much more than room temperature. The impact of frequency and temperature on complex immittance parameters (impedance and modulus) are analyzed by an impedance analyzer in broad frequencies and temperature ranges. The electrical properties show; (i) the existence of semiconductor-like negative temperature coefficients of resistance behavior, (ii) evidence of electrical relaxation phenomena as a function of temperature, and (iii) the existence of single electrical relaxation ascribed to the existence of grain contribution to the electric properties. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the effect of curing mode on polymerization kinetics, biaxial flexural strength (FS) and modulus (MO), and dentin bond strength (BS) of self-adhesive and conventional resin-based cements. Two materials were evaluated: one self-adhesive G-Cem LinkAce (GC) and one conventional resin cement RelyX Ultimate (RU). Polymerization kinetics was followed by infrared spectroscopy (n = 5). Disc specimens of light-activated or self-cured materials were tested for FS and MO (n = 10). Extracted human molars were divided into 4 groups (n = 10) according to resin cement, curing mode, and evaluation time (24 hs and 1 year). Composite discs were used to simulate indirect restoration which bonded to occlusal dentin with the resin cements, and light-activated or allowed to self-cure, and restored teeth were tested for microtensile BS. Data were submitted to statistical analysis at 5% significance level. A rapid rise in conversion was observed when materials were light-activated. When self-cured, RU demonstrated a slower polymerization rate and lower conversion than GC. Dual curing yielded higher FS, MO, and BS than self-curing mode to RU cement, while no significant differences were observed for GC. Light-activation influences polymerization kinetics of resin-based cement, but it did not influence the mechanical properties and adhesion of the self-adhesive cement tested (GC). [ABSTRACT FROM AUTHOR]

This study developed polypropylene (PP) nanocomposites containing surface-functionalized boron nitride (BN) decorated with BaTiO3 (BT). The developed nanocomposites showed well-dispersed nanoparticles in the PP matrix. The nanocomposites showed optimal hardness, elastic modulus, and stiffness of about 166.6 MPa, 2.7 GPa, and 0.12 mN/nm for PP/15BN-5BT nanocomposite compared to 79.4 MPa, 1.7 GPa, and 0.089 mN/nm measured for the pure PP, which are increments of about 110%, 59%, and 35% respectively. Heat deflection temperature and dynamic mechanical properties were also enhanced. Therefore, this study discussed the effects of BN decorated with BT on the nanomechanical and thermomechanical properties of PP nanocomposites. [ABSTRACT FROM AUTHOR]

Ramie fiber as the longest natural cellulose fiber in the world has been widely used in textile production. However, the rigidity of ramie fiber greatly restricts its application in high value-added garments. The softening treatment of ramie fibers is therefore essential. In this study, four different concentrations of ionic liquid (IL) solutions, [Emim]OAc(1-ethyl-3-methylimidazolium acetate), were used to treat degummed ramie fibers. The fiber fineness, mechanical properties, moisture absorption, and liberation ability were tested, and the fibers were also examined with Scanning Electron Micorscope (SEM), Gel Permeation (GPC), and X-ray diffraction (XRD). The results showed that the fiber modulus after 90% IL treatment was decreased to 31% of its original value while the breaking tenacity was decreased to 50% of its original value, these mechanical properties of treated ramie fiber were similar to cotton fiber and much softer than regular ramie fibers. Moreover, with the IL treatment, the ramie fiber presented higher water absorption and breaking elongation. It is believed that with the proper IL treatment, the ramie fiber will show better potential for textile production. [ABSTRACT FROM AUTHOR]

Copper -doped Strontium Titanate (STO) with Copper filler percentages of 5% and 10% was prepared through a solid-state reaction method at high temperatures. The structural study of the materials was characterized by the X-ray diffraction technique and confirmed to be in the Cubic phase. Also, the surface morphology of the samples was studied by scanning electron microscopy. The impedance study of the samples was characterized by an LCR meter between the frequencies ranges 102-106 Hz. The exponential dependence of ac conductivity on frequency was confirmed where the value of ac conductivity increases with the rise in filler concentration from 5% to 10%. [ABSTRACT FROM AUTHOR]

Copper -doped Strontium Titanate (STO) with Copper filler percentages of 5% and 10% was prepared through a solid-state reaction method at high temperatures. The structural study of the materials was characterized by the X-ray diffraction technique and confirmed to be in the Cubic phase. Also, the surface morphology of the samples was studied by scanning electron microscopy. The impedance study of the samples was characterized by an LCR meter between the frequencies ranges 102-106 Hz. The exponential dependence of ac conductivity on frequency was confirmed where the value of ac conductivity increases with the rise in filler concentration from 5% to 10%. [ABSTRACT FROM AUTHOR]

In this paper, bio-based semi-aromatic high-temperature polyamide PA5T/56 was synthesized from bio-based monomer glutamine. The micro and macro physicochemical properties of PA5T/56 were studied by Materials Studio software, Universal Testing Machine and Impact Testing Machine and other software and instruments, and the effect of PA5T content on its properties was explored. The results showed that the Poisson's ratio and modulus of PA56 molecule were the largest, PA5T molecule was the smallest, and PA56T molecule was between the two, indicated that the addition of PA5T molecule enhances the overall mechanical properties; With the increase in PA5T content, the tensile strength and bending strength of PA5T/56 increases, while the elongation at break and impact strength decreases, the density of PA5T/56 increases first and then decreases, and the oil absorption rate and water absorption rate of PA5T/56 decrease gradually; Moreover, PA5T/56 has excellent solvent resistance, it is insoluble in conventional organic solvents and only soluble in concentrated sulfuric acid and trifluoroacetic acid; With the extension of soaking time, the tensile strength and bending strength of PA5T/56 decrease, while the impact strength of PA5T/56 increases first and then decreases. [ABSTRACT FROM AUTHOR]

Robotic Automated Fiber Placement (R-AFP) technology was developed to manufacture composite laminates by placing carbon fiber thermoset towpregs, obtained by impregnating 12 K high-strength grade carbon fibers in an epoxy resin system. In order to avoid placement induced defects, a thermographic scanning technique was implemented for on-line quality monitoring of the R-AFP process. The thermal analysis proved to be an effective and quick approach for the real-time detection of deposition defects generated during. The R-AFP process was performed by applying a constant pressure through the compaction roller; different pressure values were investigated. The effect of the resin weight fraction and compaction pressure on the mechanical properties applied by the deposition head during R-AFP of cross-ply laminates was studied. The reduction of the tensile strength and the increase of the elastic modulus with decreasing pressure of the compaction roller was observed. Furthermore, the values of ultimate tensile strength and elastic modulus decrease as the resin content increases. Finally, the three-dimensional topography of surface fracture of tensile samples was investigated by means of the optical and scanning electron microscopy. [ABSTRACT FROM AUTHOR]

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]

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]

Samarium modified SrBi4-xSmxTi4O15 (x = 0, 0.13, 0.43 and 0.78) ferroelectric ceramics of Aurivillius family were prepared by conventional solid state reaction method. X-ray diffraction studies confirm the formation of a single-phase. Microstructural images show randomly oriented palate-like structure. Broad dielectric peaks were found to obey the modified Curie-Weiss law. The overall inherent ferroelectric nature was explained on the basis of the Avrami model. Furthermore, with increasing the Sm3+ content, the grain morphology and diffusive parameters have shown a comprehending impact on the ferroelectric (hysteresis) behavior. [ABSTRACT FROM AUTHOR]

Epoxy-cashew nut shell liquid (E-CNSL) composites are prepared by open resin moulding method with varying CNSL content (16 to 30 vol. %.). The tensile properties, hardness and impact strength of E-CNSL composites were investigated as per ASTM standards. It is found that the addition of the CNSL in epoxy increases the elongation at break and tensile strength. The 16 vol. % CNSL addition showed maximum tensile strength, and further increased CNSL deteriorates the tensile properties of the resultant composites. Further, hybrid composites are prepared by reinforcing crumb rubber (CR), short banana fibre (BF) and friction dust (FD) in cashew nut shell liquid (CNSL) mixed epoxy. The samples were tested as per ASTM standards to investigate the basic mechanical properties. It is found that the hybrid composite made of 2.5 vol. % CR, 2.5 vol. % FD and 7.5 vol. % BF in epoxy with 16 vol. % of CNSL showed better properties. Further, the specific wear rate, coefficient of friction and rate of water intake is investigated for the hybrid composite and reported. [ABSTRACT FROM AUTHOR]

Molecular Dynamics (MD) was used to determine the accuracy of different force fields on predicting the elastic modulus of single crystal aluminum through nanoindentation tests. In this work, nanoindentation was performed using three different types of force fields (EAM, MEAM and ReaxFF) and the resulting elastic modulus was compared to the value obtained using elastic constants from standard small strain tensile simulations. When the predicted modulus of each force field was compared to the modulus via elastic constants, the ReaxFF resultant moduli were similar to that of nanoindentation, but for EAM and MEAM the two methods produced significantly different values. Therefore, even if a force field is parameterised for elastic modulus, it does not guarantee the force field will accurately predict the modulus from other procedures. As well, two different methods for calculating modulus from indentation curves were compared: The Hertz approximation and the Oliver and Pharr (O&P) method. For EAM and MEAM force fields, the Hertz method significantly under predicted modulus while the O&P method was in better agreement with the experimental modulus. [ABSTRACT FROM AUTHOR]

As opposed to traditional laboratory testing, Molecular Dynamics (MD) offers an atomistic scale method to estimate the mechanical properties of metals. However, there is limited literature that shows the effect of interatomic potentials when determining mechanical properties. Hence, the present research was conducted to investigate the accuracy of various interatomic potentials in estimating mechanical properties of aluminium. Several types of potentials, including Embedded Atom Method (EAM), Modified EAM (MEAM) and Reactive Force Field (ReaxFF) were compared with available experimental data for pure aluminium to determine the most accurate interatomic potential. A uniaxial tensile test was performed at room temperature using MD simulations for nanoscale aluminium. Results demonstrated that those potentials parameterised with elastic constants at physically realisable temperatures were consistently more accurate. Overall, the Mishin et al. EAM potential was the most accurate when compared to single-crystal experimental values. Regardless of the potential type, the error was significantly higher for those potentials that did not consider elastic constants during development. In brief, the application of the interatomic potentials to estimate mechanical properties of a nanoscale aluminium was investigated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The goal of this research is to study the mechanical properties of recycled rubber particles extracted from scrap tires in concrete to introduce a sustainable waste management system and subsequently to reduce the use of non-renewable resources in concrete. In this paper, fine aggregates of concrete are partially replaced (up to 50% by volume of fine aggregate) with recycled long shredded rubber particles mainly smaller than sieve #4 in size. Concrete cylinders with different proportion of rubber are prepared and tested under compression. Also, specimens without rubber are prepared and tested as control specimens. The compressive strength, elastic modulus, and stress-strain curves of the specimens are analyzed to characterize the behaviour of concrete with recycled long shredded rubber particles. The results showed that the rubber weakened the compressive strength and elastic modulus of concrete. Empirical equations are also proposed to account the effect of rubber content on the mechanical properties. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of weakly quasisymmetric homeomorphisms. We investigate under what conditions a weakly H-quasisymmetric map is actually quasisymmetric. As a consequence, we deduce conditions under which the inverse and composition of weakly quasisymmetric homeomorphisms are also weakly quasisymmetric. [ABSTRACT FROM AUTHOR]

Nano-indentation is an interesting tool for analyzing nano-scale mechanical properties. The analysis of nano-mechanical properties as a function of experimental conditions is very critical for designing engineering components. In this study, nano-indentation experiments were performed by considering different values of amplitude (1, 5, 10 nm), frequency (11.2, 22.5, 45 Hz), strain rate (0.02, 0.05, 0.1, 0.2, 1 s−1), peak load (10, 30, 100 mN) and hold time (1, 3, 5, 10, 20, 50, 100 sec) to analyze their effect on the mechanical properties of LDPE. The results showed that the effect of amplitude and frequency on the nano-mechanical properties of LDPE were negligible. Load-displacement curves displayed a shift towards higher indentation depths along with a decrease in peak load from 20.6 to 14.8 mN by having a decrease in strain rate from 1 to 0.02 s−1. Elastic modulus and hardness values exhibited a decrease with an increase in hold time. Logarithmic creep model was used to fit the experimental data of creep as a function of holding time which showed good agreement (r2 ≥ 0.97) with the experimental values. Recommended holding times are also suggested to eliminate the creep and nose problem in order to achieve high accuracy in measurements. [ABSTRACT FROM AUTHOR]

In this paper, various original properties of the Bessel and spherical Bessel functions are presented, based on which we prove a novel uniqueness result of an inverse acoustic obstacle scattering problem, that is, a sound-hard ball with a known center can be uniquely determined by the modulus of a single far-field datum corresponding to a single incident plane wave. [ABSTRACT FROM AUTHOR]

This study evaluates three nondestructive testing (NDT) techniques for quality assessment of asphalt pavements. The three NDT techniques examined include an electromagnetic density gauge, a dynamic stiffness gauge, and geophysical surface wave tests for measuring modulus. In-situ NDT tests were carried out for four representative paving projects covering a range of asphalt mixes and traffic loads, and cores were extracted at the centre of each NDT testing location for laboratory measurement of density and modulus. A comprehensive correlation analysis was carried out to examine the performance of each NDT method for quantifying the quality of the asphalt pavements. The in-situ density had a low correlation with the laboratory density and was not sensitive to variations in temperature and asphalt mix type. The in-situ stiffness measured on the asphalt mixtures several hours after paving had a high correlation with the in-situ dynamic modulus and laboratory density, and is therefore recommended as a quantitative property for quality control. Among the three NDT measurements, the in-situ modulus was most sensitive to variations in temperature and asphalt mix type. After correction for temperature effects, the corrected modulus is recommended as a quantitative property for quality assurance. [ABSTRACT FROM AUTHOR]

Previous strengthening mechanisms described in literature for high density polyethylene (HDPE) carbon nanotubes composites are typical of those observed in fibre reinforced polymeric micro composites. Here, we present a new molecular level strengthening mechanism based on HDPE carbon nanotubes composite, which has not been reported before to the best of authors' knowledge. The HDPE nanocomposite was produced by melt intercalation technique via twin-screw extrusion. Thereafter, the samples were subjected to mechanical tensile tests and scanning electron microscope (SEM) examination. Carbon nanotubes (CNTs) were found to be disentangled from the polymer molecules after yielding and prior to breaking. SEM and optical microscopic observations revealed visible black agglomerate bands at 45° appeared after yielding and prior to the breaking of the ductile HDPE. It was observed that CNTs were pushed out from the intricate mechanical interlocking with the thermoplastic polymeric chains of HDPE during strain hardening. [ABSTRACT FROM AUTHOR]

Use of recycled asphalt pavement (RAP) in highway construction is highly promoted due to recent awareness in sustainable construction practices. The concerns with material brittleness in utilising higher content of RAP are alleviated through addition of rejuvenators to some extent. Inclusion of rejuvenator to the aged binder improves its flexibility and lessens its cracking potential. A study was undertaken to investigate the effectiveness of the impact resonance (IR) testing in determining low-temperature binder properties through mixture testing. To this effect, the presented study consisted of two stages. In stage I, the IR test was conducted on mixes made with different low-temperature grade binders. Stage II consisted of testing pure RAP mixes treated with a rejuvenating agent at different levels using the IR as well as testing blends of recovered RAP binder and rejuvenator and virgin binder using bending beam rheometer (BBR). The IR test was performed at a range of temperatures between and . The results indicate that the IR test can successfully capture the low-temperature properties of binders in virgin mixes as well as RAP mixes incorporating rejuvenator. A very high linear correlation was observed between stiffness from IR testing of the RAP mix and stiffness from BBR testing of the blend of recovered binder and virgin binder and rejuvenator. A good correlation was also observed between phase angle of RAP mixes obtained from IR with the m-value, a relaxation index, from BBR at a range of temperatures for a given rejuvenator content. The results clearly demonstrate the potential of IR to be used for grading and optimisation for the asphalt binder of RAP and rejuvenator content in lieu of the binder recovery method. [ABSTRACT FROM AUTHOR]

The design of highway subgrades necessitates the estimation of strength and stiffness characteristics to a reasonably accurate extent. The present study provides details on investigations on the modulus of resilience of lateritic soils in the region of Dakshina Kannada in Southern India, using the cyclic tri-axial test equipment. The discussions also provide comparisons on similar studies performed using the portable falling weight deflectometer (PFWD), and the California bearing ratio (CBR) test. As part of this study, regression equations were developed in order to correlate the observations made using the PFWD and the CBR with the results obtained using the cyclic tri-axial test. It is felt that the regressions developed for estimating the modulus of resilience based on simpler experimental approaches such as the CBR, and the PFWD, will be of special advantage to pavement engineers in developing nations. [ABSTRACT FROM AUTHOR]

[N(CH3)3H]2ZnCl4 has been analyzed by X-ray powder diffraction patterns, differential scanning calorimetry and impedance spectroscopy. The [N(CH3)3H]2ZnCl4 hybrid compound is obtained by slow evaporation at room temperature and found to crystallize in the orthorhombic system with Pnma space group. Five-phase transitions at low temperature were detected by differential scanning calorimetry measurements. The analysis of Nyquist plots has revealed the contribution of three electrically active regions corresponding to the bulk mechanism, distribution of grain boundaries and electrode processes. The dielectric relaxation is described by a non-Debye model. The study of the dielectric constants ϵ′, ϵ″ and loss tangent tan (δ) with frequency exhibits a distribution of relaxation times. The complex modulus plots have confirmed the presence of grains and grain boundaries as well as a non-Debye type of relaxation in the material. Thermodynamic parameters such as the free energy for dipole relaxation ΔF, the enthalpy ΔH and the change in entropy ΔS have been determined with the help of the Eyring theory. [ABSTRACT FROM AUTHOR]

[N(CH3)3H]2ZnCl4 has been analyzed by X-ray powder diffraction patterns, differential scanning calorimetry and impedance spectroscopy. The [N(CH3)3H]2ZnCl4 hybrid compound is obtained by slow evaporation at room temperature and found to crystallize in the orthorhombic system with Pnma space group. Five-phase transitions at low temperature were detected by differential scanning calorimetry measurements. The analysis of Nyquist plots has revealed the contribution of three electrically active regions corresponding to the bulk mechanism, distribution of grain boundaries and electrode processes. The dielectric relaxation is described by a non-Debye model. The study of the dielectric constants ϵ′, ϵ″ and loss tangent tan (δ) with frequency exhibits a distribution of relaxation times. The complex modulus plots have confirmed the presence of grains and grain boundaries as well as a non-Debye type of relaxation in the material. Thermodynamic parameters such as the free energy for dipole relaxation ΔF, the enthalpy ΔH and the change in entropy ΔS have been determined with the help of the Eyring theory. [ABSTRACT FROM AUTHOR]

Steel matrix composite reinforced with 2–4 vol.% titanium diboride particles was fabricated successfully by powder metallurgy route through hot pressing method. Influence of sintering parameters on densification was investigated by measurement of density of resultant composites. Microstructural analysis of hot-pressed materials was performed. Hardness and deformation behavior under constant load were evaluated by conducting microhardness and nanoindentation tests. The addition of titanium diboride proved to be effective for enhancement of hardness and strength. Composite with 4 vol.% titanium diboride sintered at 1100°C resulted in improved hardness and elastic modulus which could be related to Orowan strengthening resulting from homogeneous distribution of fine titanium diboride particles in steel matrix. The results indicate that proposed method is economically feasible to process steel matrix composites with improved properties. A comparatively lower temperature and pressure offers better control of interface kinetics and microstructure. [ABSTRACT FROM AUTHOR]

Laser-assisted processing and in-situ characterization of a Ni0.7-Al0.1235-Co0.15-Ti0.0265alloy were carried out under a range of simultaneous hydrostatic high pressures of ∼30 GPa and high temperature conditions ∼2000°C using a laser-assisted heating in diamond anvil cell with synchrotron X-ray micro-diffraction. The characterization of the microstructure and X-ray diffraction analysis at ambient conditions confirmed the formation of the cuboids of orderedγ′ phase in the disorderedγmatrix. The isothermal bulk modulus (B0) and its first-order derivative (B0’)of the alloy were determined to beB0 = 123 ± 9 GPa andB0’ = 5.7 ± 2.8. The in-situ characterization of the alloy at high temperatures under high pressures revealed that theγ′ phase transforms into the tetragonaly distorted D022-type structure. This transformation is similar to the transformation that occurs in the ordered Ni3Al, responsible for the improved strength at high temperatures. High pressure was found to increase the onset temperature of the structural distortion. The pressure–temperature phase diagram of the Ni0.7-Al0.1235-Co0.15-Ti0.0265up to ∼30 GPa and ∼2000°C was determined and is reported here. [ABSTRACT FROM PUBLISHER]

Impedance spectra of 0.93BNT-0.07KNN revealed positive and negative temperature coefficient of resistance behaviour up to 400°Cand above 400°C. With the increase of temperature, decreased radii and displaced centres of semicircles from the real axis of impedance Cole-Cole plots suggested non-Debye type relaxation mechanism. Three dielectric relaxation regions: within (i) grain, (ii) grain- grain boundary and (iii) grain boundary were prominent in lower, middle and high temperature regions, respectively. The activation energy ranging from ∼0.79 to 1.2eV, suggested that the conduction carriers were cation and cation, oxygen vacancies in lower and higher temperature regions, respectively. [ABSTRACT FROM AUTHOR]

The objective of this paper is to evaluate the factors affecting resilient and permanent deformation behaviour of unbound granular materials, with a focus on the aggregate physical and morphological characteristics. To evaluate the behaviour of base course, repeated load triaxial testing is commonly used to establish the stress-dependent resilient modulus properties of unbound aggregate base and subbase materials. Although resilient modulus of aggregates is a critical input into mechanistic-empirical pavement design methods, the resilient modulus of unbound base material is often estimated from empirical correlations with index properties in the AASHTOWare Pavement ME design procedure for its simplicity. Since actual field stress conditions and resilient modulus stress states are generally quite different from those generated in the empirical test methods, use of an empirical correlation could lead to an unreliable prediction of resilient modulus and permanent deformation. In order to properly assess the stability of an unbound aggregate layer, it is necessary to establish a proper process to understand the factors affecting fundamental and performance-related properties of unbound granular materials. In this study, aggregate samples from four different sources were tested for resilient modulus and Poisson’s ratio measurements using the Precision Unbound Material Analyzer equipment. Morphological or shape properties of aggregate samples were also measured using an image analysis device. The results demonstrate that aggregate physical and morphological properties affect aggregate resilient and permanent deformation. Further, it is suggested that the resilient modulus of the aggregate should not be used as the sole indicator of rutting performance of aggregate base. [ABSTRACT FROM AUTHOR]

The polycrystalline CrN/Si3N4multilayer films were deposited by magnetron sputtering. We have investigated the effects of substrate temperature on the microstructural, interfacial and mechanical properties. X-ray reflectivity and diffraction (XRR and XRD), and nanoindentation were used to characterize the structures and mechanical properties for the coatings. It was found that the hardness enhancement is caused by the modulus difference in the interface between layer CrN and Si3N4. The elastic modulus is related to the composition of crystalline orientation and distortion. The sharp interface is good for improving the mechanical properties for CrN/Si3N4multilayer. The variation of hardness and modulus are attributed to the changes in grain size and modulus variation caused by crystalline distortion. Compared to sample at room temperature, the yield stress (resistance to plastic deformation) and fracture toughness (resistance to crack propagation) would be improved by increase of substrate temperature. [ABSTRACT FROM PUBLISHER]

A comprehensive study was conducted to evaluate the impact of liquid and lime additives on the pavement performance of asphalt mixtures from five different sources around the USA. Three types of mixtures were evaluated from each source: untreated, liquid-treated and lime-treated. The measured properties of the 15 mixtures included the dynamic modulus master curves and their resistances to rutting and fatigue at the undamaged and moisture-damaged conditions. The moisture-damaged state consisted of subjecting the mixtures’ specimens to six freeze-thaw cycles. First the mixtures from each source were ranked based on their individual properties, i.e. dynamic modulus, permanent deformation and fatigue characteristics. Next, the measured properties of the mixtures were used in a mechanistic analysis to predict the rutting and fatigue lives of flexible pavements constructed with the evaluated mixtures. The estimated rutting and fatigue lives of the flexible pavements were ranked within each source. The analysis of the data showed that ranking of the mixtures within each source based on their individual properties significantly differs from the mixtures based on their rutting and fatigue lives estimated by the mechanistic analysis. This observation led to the conclusion that ranking hot mixed asphalt mixtures solely based on their independent properties provides unreliable recommendations concerning the relative performance of the mixtures. Finally, the performance of the mixtures was compared within each source and showed that lime-treated mixtures out-performed the liquid-treated mixtures for all sources regardless if the source required anti-strip additive or not. [ABSTRACT FROM AUTHOR]

The generation ofin vitrotissue constructs using biomaterials and cardiac cells is a promising strategy for screening novel therapeutics and their effects on cardiac regeneration. Current cardiac mimetic tissue constructs are unable to stably maintain functional characteristics of cardiomyocytes for long-term cultures. The objective of our study was to fabricate and characterize nanofibrous matrices of gelatin for prolonged cultures of primary cardiomyocytes which previously has been used as copolymer or hydrogels. Gelatin nanofibrous matrices were successfully electrospun using a benign binary solvent, cross-linked without swelling and fusing and evaluated by scanning electron microscopy (SEM) and uniaxial tensile measurement. Scaffolds exhibited modulus 19.6 ± 3.6 kPa similar to native human myocardium tissue with fiber diameters of 200–600 nm and average porosity percentage of 49.9 ± 5.6. Myoblasts showed good cell adhesion and proliferation. Neonatal rat cardiomyocytes cultured on gelatin nanofibrous matrices showing synchronized contracting cardiomyocytes (beating) for 27 days were studied by video microscopy. Confocal microscopic analysis of immunofluorescence stained sections indicated the presence of cardiac specific Troponin T in long-term cultures. Semiquantitative RT-PCR analysis of 3D versus 2D cultures revealed enhanced expression of contractile protein desmin. Our studies show that the biophysical and mechanical properties of electrospun gelatin nanofibers are ideal forin vitroengineered cardiac constructs (ECC), to explore cardiac function in drug testing and tissue replacement. Together with stem cell techniques, they may be an ideal platform for prolongedin vitrostudies in alternatives to animal usage for the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Conventional distributed beamforming schemes in multicell system often ignore two practical conditions, (1) the coexistence of intracell interference (InCI) and inter-cell interference (ICI), (2) the number of users is larger than the number of base station (BS) antennas. In this paper, we consider these two conditions and analyze the decentralized beamforming of the multicell system from the viewpoint of zero forcing (ZF). A novel user selection method based on ZF algorithm is proposed to divide the users into two categories, i.e. one of the categories is eligible to participate in ZF algorithm and the other is not. The proposed criterion of partitioning users is based on the degree of parallelity between local channels. In addition, each BS utilizes only the local channel state informations (CSIs) to derive its beamforming vector. The simulation results demonstrate that our proposed algorithm can achieve higher rates and are more robust against InCI and ICI than the traditional ones under the different number of transmitting antennas and users. [ABSTRACT FROM AUTHOR]

Fused deposition modeling (FDM) has gained popularity in industry because of its ability to manufacture complex parts. But when it comes to the manufacturing of functional products, the advantages of FDM are not so distinct due to the high number of intervening parameters and complex optimal settings setup. This paper investigates the influence of process parameters on the rheological and dynamic mechanical properties of FDM-manufactured parts. In this study, an attempt has been made to establish an empirical relationship between the FDM input parameters and the properties involved using IV-optimal response surface methodology and statistical analysis. Further, optimized process parameters were established to maximize the rheological and dynamic mechanical properties through the graphical optimization. The optimization results show that the parameters with the most significant effect on the rheological and dynamic mechanical properties are the layer thickness, the air gap, the road width, and the number of contours. The results also show that by taking into consideration the number of contours, the functionality of manufactured part is improved significantly. [ABSTRACT FROM AUTHOR]

In this paper, we prove some positive results on discreteness and openness of mappings of finite distortion under some integrability condition on the distortion and the multiplicity function of the mapping. We also show that in some sense, our results are sharp. [ABSTRACT FROM PUBLISHER]

Four major types of polyester industrial yarns, viz. high tenacity (HT), high modulus low shrinkage (HMLS), low shrinkage (LS) and super low shrinkage (SLS) polyester yarns, were studied for their static and dynamic properties. An attempt has been made to establish a linkage between static and dynamic properties of these yarns with its structure and with its end applications. HMLS and HT polyester yarns have lower tan δ and work loss, which are the desired characteristics required for its end applications which include tire and conveyer belt. Higher overall orientation and higher fraction of tie molecules helped to achieve these properties in HT and HMLS polyester yarns. LS and SLS polyester yarns are mostly used for static applications. Low thermal shrinkage is the key requirement for the downstream processes of these yarns. Lower amorphous orientation in these two yarns is primarily responsible for achieving very low thermal shrinkage. A good co-relation has been established between the peak temperature of work loss (in slow speed hysteresis test) and the peak temperature of tan δ (in high-speed dynamic test). [ABSTRACT FROM AUTHOR]

In this study, acrylonitrile butadiene styrene/ethylene vinyl acetate-based melt blends were prepared using linear low-density polyethylene as modifier. Commercially available sodium montmorillonite clay was organically modified and incorporated in blends. Fourier transformed infrared was used to confirm the structure of the blend and composites. Morphology of acrylonitrile butadiene styrene / ethylene vinyl acetate blend showed two-phase structure that formed a well-aligned pattern with fine nanoclay distribution. Addition of organo-modified clay depicted increase in tensile strength (43%) and modulus (89%) in damage-free range. XRD results of sodium montmorillonite, organically modified Na-montmorillonite, and PNCs were compared to investigate the degree of dispersion in matrix. [ABSTRACT FROM PUBLISHER]

The authors focus on properties of biomineralized (CaCO3) PVP-CMC hydrogel (designated as I–X) including cytotoxicity assay using primary mouse embryonic fibroblasts. The biomineralized samples (VII–X) showed >80% cell viability, was selected for further characterizations. FTIR and XRD indicate deposition of CaCO3within the PVP-CMC hydrogel matrix, SEM shows changes in morphology and pore diameter (VII and VIII: 1–12 µm; IX: 10–70 µm; X: 70–170 µm), TGA determines the decomposition scenario of CaCO3, and tensile strength of samples (VII–X) ranged between 0.04 and 1.0 GPa, which practically corresponds to the modulus of cancellous bone. [ABSTRACT FROM AUTHOR]

Cold-rolled in situ dendrite/metallic glass matrix (MGM) composites with a composition of Ti48Zr18V12Cu5Be17 exhibit a fact that modulus and hardness of matrix is decreased with the increasing in thickness reduction, while the modulus of dendrites remains constant, and hardness tends to increase sharply with the increase in thickness reduction < 30% and then it approximately remains constant. Free volumes created by plastic deformation lead to the decrease of the matrix modulus. Dendrites are restricted by surrounding matrix, which results in the modulus of dendrites constant. Multiplication of shear bands is the dominant mechanism affecting the hardness of the matrix. The present study gives a guideline to predict the evolution of hardness and modulus in both dendrites and glass matrix in such dual-phase composites. [ABSTRACT FROM AUTHOR]

A compiled database of shear wave velocity measurements in a variety of clays, silts and sands shows directional hierarchies between downhole (VsVH), standard crosshole (VsHV), and rotary crosshole (VsHH) tests. The specialin situdatabase has been collected from 33 well-documented geotechnical test sites. Expressions relating the small-strain shear modulus in terms of effective confining stress level, stress history and void ratio are explored for each of these three modes of directional shear wave velocity. The relationships are separated initially into soil groups (intact clays, fissured clays, sands and silts), and then generalised to consider all soil types together. [ABSTRACT FROM PUBLISHER]

Osteogenesis imperfecta is a congenital disease commonly characterized by brittle bones and caused by mutations in the genes encoding Type I collagen, the single most abundant protein produced by the body. The oim model has a natural collagen mutation, converting its heterotrimeric structure (two α1 and one α2 chains) into α1 homotrimers. This mutation in collagen may impact formation of the mineral, creating a brittle bone phenotype in animals. Femurs from male wild type (WT) and homozygous (oim/oim) mice, all at 12 weeks of age, were assessed using assays at multiple length scales with minimal sample processing to ensure a near-physiological state. Atomic force microscopy (AFM) demonstrated detectable differences in the organization of collagen at the nanoscale that may partially contribute to alterations in material and structural behavior obtained through mechanical testing and reference point indentation (RPI). Changes in geometric and chemical structure obtained from µ-Computed Tomography and Raman spectroscopy indicate a smaller bone with reduced trabecular architecture and altered chemical composition. Decreased tissue material properties in oim/oim mice are likely driven by changes in collagen fibril structure, decreasing space available for mineral nucleation and growth, as supported by a reduction in mineral crystallinity. Multi-scale analyses of this nature offer much in assessing how molecular changes compound to create a degraded, brittle bone phenotype. [ABSTRACT FROM AUTHOR]

Material properties play a significant role in pharmaceutical processing. The impact of roller compaction (RC) and tablet compression on solid fraction (SF), tensile strength (TS) and flexural modulus (FM) of Avicel DG [co-processed excipient with 75% microcrystalline cellulose (MCC) and 25% anhydrous dibasic calcium phosphate (DCPA)], lactose and 1:1 Mixture of the two was studied. Materials were roller compacted at different force and roller type and compressed into tablets over a range of compression pressures (CP). SF, TS and FM were determined for ribbons and tablets. Roller force was a significant variable affecting SF while roller type was not. Both SF and TS of tablets increased with CP with Avicel DG exhibiting greater TS than that of 1:1 Mixture while tablets of lactose had the lowest TS. The TS of tablets decreased exponentially with tablet porosity. Ribbon of Avicel DG had higher TS and lower SF than lactose and greater reworkability. This is attributed to plastic deformation of MCC resulting in high degree of bonding and fragmentation of DCPA that fills the void spaces during tablet compression. The lack of significant increase in SF and low tablet TS for lactose upon compression is likely due to its brittle fragmentation and some elastic recovery as shown by the high FM. [ABSTRACT FROM AUTHOR]

The development of simulation techniques is more crucial to establish the structure-processing-properties relationship for design and optimization of advanced nanocomposites. In this work, the attempts made for the simulation of modulus in polymer/carbon nanotube (CNT) reinforced nanocomposites and the future challenges are discussed. The simulating techniques including micromechanics and multiscale models are extensively analyzed. It is concluded that the multiscale and other new techniques should be developed to cover the wide range of time and length scales, from quantum structure (a few atoms) to macroscopic structure (many domains), to introduce a useful tool for the simulation of modulus. A comprehensive modeling of modulus requires much knowledge in many fields such as polymer, mechanics, and mathematics. [ABSTRACT FROM PUBLISHER]

The thixotropic behaviors of Daqing waxy crude were studied experimentally with the help of the advanced strain controlled rheometer (ARES-G2). The experimental results indicated the decrease in viscosity can be divided into two continuous steps, and the recovery of viscosity consists of three continuous processes. Then a new method was used to model the thixotropic behavior combined with the experimental data, and the new method was based on a potential function that can characterize the recovery capability of the inner structure, it is reasonable for to describe the thixotropic behavior of Daqing waxy crude properly. [ABSTRACT FROM PUBLISHER]

This paper presents a comprehensive study of the effects of titanium dioxide (TiO2) on the dielectric, mechanical, and electromechanical properties of a silicone elastomer. The silicone/TiO2composite films exhibited, in comparison with pure silicone, a steadily improvement of dielectric constant and elastic modulus with the augment of TiO2particles. A transverse planar strain of 18% with pre-strain of 5% at 50V/μm was obtained, which was 50% higher than the corresponding value generated with the pure silicone. The practical actuated strain was lower than the theoretical, and it was well explained. [ABSTRACT FROM AUTHOR]

The deformation modulus of sands below 30 m in the Nakdong River Delta was estimated by using various in-situ tests, such as the piezocone penetrometer (CPT), seismic dilatometer (SDMT), and pressuremeter tests (PMT). Disturbed sand samples retrieved at several depths of two boreholes were reconstituted to simulate the in-situ deposited condition using a slurry method. Thereafter, the drained triaxial compression (TX) and the resonant column (RC) tests were also conducted. The elastic modulus obtained through the application of the TX and PMT results to conventional methods led to the underestimation of the in-situ values, because the inherent characteristics of the natural sands were not considered. Thus, the non-linear modulus degradation curves were constructed using the modulus degradation from the TX, RC, PMT, and the in-situ maximum shear modulus from SDMT. Thereafter, the modulus at 25% failure stress strength was re-evaluated. The re-evaluated values from the TX were in good agreement with those from the PMT, using the unloading curves and with the existing empirical equation based on the seismic CPT. Finally, a CPT-compatible empirical formula for the deformation modulus at 25% failure strength was proposed. [ABSTRACT FROM AUTHOR]

The polycrystalline Ti/TiN multilayer films were deposited by magnetron sputtering. We investigated the effects of mixed discharge gas pressure on the microstructural, interfacial, and mechanical properties of the polycrystalline Ti/TiN multilayer films. X-ray reflectivity and diffraction (XRR and XRD), and nanoindentation were used to characterize the structures and mechanical properties for the films. It was found that the hardness enhancement is caused by the modulus difference in the interface between layer Ti and TiN. The elastic modulus is strongly related to the composition of crystalline orientation and distortion. The sharp interface is good for improving the mechanical properties for Ti/TiN multilayer. [ABSTRACT FROM AUTHOR]