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This study focuses on the preparation of lithium diphosphate compound LiCeP2O7 via conventional solid-state reaction. Analysis using the Rietveld refinement of the X-ray diffraction pattern reveals that the sample adopts a monoclinic structure at room temperature. Surface morphology is further examined through SEM. Additionally, complex impedance and electrical modulus spectroscopy analyses indicate the presence of non-Debye-type relaxation behavior. The direct current (dc) conductivity exhibits Arrhenius behavior, with activation energies of 0.94 eV in region I and 1.21 eV in region II, indicating thermally activated lithium-ion conduction. The thermal behavior of the exponent parameter "s" suggests a transition in the conduction mechanism from large polaron tunneling to small polaron tunneling that occurs at 533 K. Electric modulus studies confirm that the ionic conduction relaxation process is thermally activated and exhibits a spread of relaxation time. Understanding the ionic conduction mechanism will facilitate the design of efficient ionic conductors for battery applications. [ABSTRACT FROM AUTHOR]

The effect of frequency and temperature on the permittivity and transport properties of calcium manganese was investigated. The sample was synthesized using a simple, an economic and a reproducible complex polymerizable route. Thereafter, it was characterized by the X-ray diffraction and complex impedance spectroscopy techniques. The obtained results showed that CaMnO3–δ exhibits a semiconducting behaviour between room temperature and 400°C. Beyond that temperature, the perovskite behaves as a metal. As for the activation energy, it showed a change around 400°C, which is attributed to the first-order transition from semiconducting to the metallic behaviour. Moreover, the dielectric constant and the loss exhibited a decreasing trend with increasing frequency, which is a characteristic of polar dielectrics. Between 25 and 400°C, the maximum barrier height increased from 0.1 to 0.32 eV. The low dissipation factor at high frequencies seems to be an interesting feature highlighting the promising use of CaMnO3–δ in high-frequency microwave device applications. [ABSTRACT FROM AUTHOR]

A359 aluminum alloy composite containing 20 vol. % silicon carbide particles was remelted, and 100-mm diameter foam ingots were prepared using 0.75 wt. % of titanium hydride (TiH2). Three identical experiments each were carried out at two foaming temperatures (640 and 660 °C) to check the reproducibility of the cell structure and foam properties. Foams made at 640 °C were reproducible in terms of foam expansion, cell size and cell size variation along the ingot height. The property scatter, evaluated in terms of relative standard deviation, is similar for density and modulus of the foam. For compressive plastic strength, the scatter is double than for density. The density and mechanical properties are reproducible within these scatters. Foams prepared at 660 °C, on the other hand, suffered from liquid foam collapse during solidification and hence couldn't be qualified for detailed study of reproducibility. The collapse resulted in distortion of the foam ingot and elongated cell structures in other parts. However, the cell size and mechanical properties in the un-distorted region are comparable with those foamed at 640 °C. Overall, good quality cell structure and consistent mechanical properties could be obtained in foams processed at 640 °C. [ABSTRACT FROM AUTHOR]

This study investigated the mechanical and tribological properties of branched polyethyleneimine/polyacrylic acid (bPEI/PAA) coatings. (bPEI/PAA) coatings were prepared on Ti6Al4V substrate using layer-by-layer assembly technique. The coatings have good tribological behaviors with the rotating mode under the deionized water. In particular, (bPEI/PAA)40 has the lowest friction coefficient with the reciprocating mode, about 0.14. The cross-linked network structures were formed with the electrostatic attraction. The amorphous phase of coatings provides a crucial buffer during the loads applying on the surface. The (bPEI/PAA)n coatings have the swelling ability, and there are large decreases of storage modulus and loss modulus in deionized water compared with removing from the deionized water. The excellent tribological properties are ascribed to the cross-linked network structure, amorphous phase, and swelling ability. [ABSTRACT FROM AUTHOR]

K2CuP2O7 potassium diphosphate has been obtained by the traditional solid-state reaction method and characterized by different techniques. Rietveld's refinement of XRD data confirmed orthorhombic symmetry, belonging to the Pbnm space group. SEM mapping and energy dispersive spectroscopy (EDS) indicated the same morphology and different particle sizes. The electrical and dielectric properties of this material were investigated using impedance spectroscopy in the frequency range 100 Hz–1 MHz and temperature range 603–673 K. The temperature dependence of the dc conductivity obeys Arrhenius' law. The frequency-dependent AC conductivity was found to obey Jonscher's power low. The values ​​of the frequency exponents increase with increasing temperature. The conduction mechanism was therefore attributed to the small non-overlapping polaron tunnel effect (NSPT). [ABSTRACT FROM AUTHOR]

A variety of rechargeable Na batteries are under development for use in energy storage systems. For these batteries, a Na-ion conducting solid electrolyte is desired. One such electrolyte under consideration is NaSICON (Na Super Ionic Conductor). One important aspect of the NaSICON electrolytes that has been overlooked is their mechanical properties. Such information is required if NaSICON has to be used as a solid electrolyte in rechargeable Na batteries that exhibit long life cycle and high power. This paper reviews the elastic, plastic, and fracture properties of NaSICON electrolytes. Young's modulus values for NaSICON range from ~ 56 to 97 GPa with Poisson's ratio ~ 0.26. Hardness values determined by micro-indentation for NaSiCON are 4.4–4.9 GPa. The value of the Gilman-Chin parameter suggests the bonding in NaSICON is covalent. As a result of its covalent bonding, NaSICON exhibits a high Peierls which leads to low fracture toughness, with KIC values ~ 1–1.5 MPa m0.5. The fracture strength of NaSICON is between 50 and 110 MPa and is controlled by the amount and size of the second-phase ZrO2 particles. [ABSTRACT FROM AUTHOR]

Cobalt sulphides, including CoS, CoS2, Co3S4 and Co9S8, have been studied as potential anode materials for Li- and Na-ion batteries. However, the mechanical properties of the cobalt sulphides have not been intensively investigated. In this work, density functional theory (DFT) calculation was employed to study the mechanical properties of the cobalt sulphides mentioned above. Besides, the mechanical properties of final products of lithiation/sodiation of Co9S8 have been calculated, including the bulk modulus, shear modulus, Young’s modulus and Poisson’s ratio. This work provides an insight into understanding the electrochemical performance of Co9S8 material as anode material for Li- and Na-storage during the cycling process. [ABSTRACT FROM AUTHOR]

Most commercially-available mechanical testing devices are bulky, expensive, and unable to evaluate changes in sample microstructure under load. This leaves a crucial gap in understanding between material structure and bulk mechanical properties. Our objective was to fabricate a mechanical testing device small enough to fit in most upright or inverted microscopy stages and able to position samples to allow for simultaneous mechanical and microstructural characterization. Parts were 3D printed using the hobbyist-friendly Fused Filament Fabrication technique, then assembled with commercial fasteners and translation components to create a mechanical testing device that utilized the deflection of plastic posts to determine sample reaction forces under applied strain. Video of sample deformation was analyzed using a custom processing script to calculate stress and strain behavior in an automated and high-throughput manner. This device was able to perform mechanical characterization with an accuracy comparable to commercial mechanical testing devices for a wide range of nonlinear and viscoelastic samples under dry and hydrated conditions. Additionally, the device showed compatibility with different upright and inverted microscopes and was able to demonstrate accurate mechanical testing results when used with these instruments. We successfully developed a device capable of accurately testing a majority of soft materials in the field of Biomedical Engineering with the ability to perform additional microstructural characterization using microscopy at a price point of $600. [ABSTRACT FROM AUTHOR]

With the increase in the use of high-density polyethylene (HDPE) products and the serious long-term hazard they pose to the environment, there has been an increasing need to decrease the release of these materials to the environment as waste. This study sets out to develop and optimize the mechanical properties of the GLP-HDPE composite, a sustainable material made from agro residues (ginger leaf particles (GLP)) and high-density polyethylene waste materials. The Taguchi robust technique, analysis of variance, and regression analysis were employed to optimize, analyze, and model the behavior of the composite materials with respect to the developmental factors of particle size and particle content. The optimum bending modulus of elasticity (MOE), modulus of rupture (MOR), and impact energy (IE) of the developed composites was 2490 MPa, 11.90 MPa, and 4.1 J at a particle size/particle content combination of 710 µm/35%, 520 µm/35%, and 710 µm/45%, respectively. Analysis of variance at 95% confidence level showed that the particle content had a significant effect on the MOE, MOR, and IE of the GLP-HDPE composite with a minimum percentage contribution of 71.61%. Equations for predicting the MOE, MOR, and IE of the composites were developed with good prediction accuracy. [ABSTRACT FROM AUTHOR]

Magnetoelectric composites combining ferromagnetic cobalt ferrite (CFO) and ferroelectric barium titanate (BT) are prepared using conventional solid-state reaction. Dielectric measurements reveal that CFO and CFO-BT composites exhibit Maxwell–Wagner polarization and temperature-dependent relaxation originating due to the presence of ions/defects vacancies. Prominently, CFO-30%BT composite showed an unexpected low dielectric loss ≈ 0.5 above 1 kHz and has potential for device application. Impedance spectroscopy confirms the thermally activated relaxation mechanism and high impedance behavior in the samples. Modulus analysis affirms the statistically distributed non-Debye-type behavior existing in CFO-BT composites. The electric conductivity takes place via correlated barrier hopping in CFO and CFO-10BT composite and overlapping large polaron tunneling in CFO-30BT composite. The addition of BT in CFO initiates the structural modification and results in conductivity cross-over with improved conductivity. These results are useful for exploring devices based on CFO-BT composites. [ABSTRACT FROM AUTHOR]

This study focused on rheological and mechanical properties of poly(vinylidene fluoride) nanocomposites incorporated with functionalized graphene nanoplatelets and hydroxylated titanium dioxide. Mechanical properties of the ternary composites were improved with a slight reduction in damping coefficient compared to the pure polymer and graphene binary composites. The storage modulus of the ternary composites significantly increased from about 67.5 Pa for the pure polymer to 3.24 × 105 Pa and 3.49 × 105 Pa at 0.1 rad/s for 6.67 wt% graphene composites containing 10 wt% and 20 wt% titania respectively. All ternary composites showed higher tensile strength and Young modulus compared to the pure polymer. Strong bonding between the polymer and co-fillers with a reduction in interfacial slipping in the ternary composites resulted in their lower damping factor and higher strength compared to their counterparts. The composite samples were prepared by solution and melt mixing methods. The scanning electron microscope was used to examine the samples' morphology and dispersion of the co-fillers in the matrix. Such composites can find applications in automobile and aerospace industries where materials with good strength and noise or vibration absorption capability are required. [ABSTRACT FROM AUTHOR]

Cesium–zinc orthophosphate (CsZnPO4) was prepared by a solid-state method. X-ray powder diffraction at room temperature confirmed the phase formation of the synthetized compound in the monoclinic system (P21/a space group). Infrared and Raman spectroscopies showed the presence of PO43− anion and its vibrations. Regarding the differential scanning calorimetry, three reversible phase transitions were revealed. The first is of a second-order type located at T1 = 520/503 K (heating/cooling), while the second and the third ones are of a first-order type located at T2 = 544/520 K (heating/cooling) and T3 = 585/577 K (heating/cooling). The detected phase transitions with calorimetric measurements were confirmed by average normalized change (ANC) and electrical conductivity study. The conduction of the studied sample is assured by Cs+ ions' hopping in tunnels and its mechanism was discussed. [ABSTRACT FROM AUTHOR]

We study several properties of the modulus of order bounded disjointness-preserving operators. We show that, if T is an order bounded disjointness-preserving operator, then T and jTj have the same compactness property for several types of compactness. Finally, we characterize Banach lattices having b-AM-compact (resp., AM-compact) operators defined between them as having a modulus that is b-AM-compact (resp., AM-compact). [ABSTRACT FROM AUTHOR]

The Na superionic conductor (NASICON) NaNbAlPO compound was prepared by the conventional solid-state reaction method. The formation of single-phase material was confirmed by X-ray diffraction studies, and it was found to be a hexagonal phase at room temperature. The electrical conductivity was measured in the frequency range from 200 Hz to 5 MHz and temperatures between 573 and 773 K using impedance spectroscopy technique. The obtained results were analyzed by fitting the experimental data to the equivalent circuit model. 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. Besides, the frequency dependence of the conductivity is interpreted in terms of Jonscher's law. Temperature dependence of the power law exponent s strongly suggests that the non-overlapping small polaron tunneling (NSPT) model is the dominant transport process. The variation of the imaginary part of the complex modulus as a function of angular frequency at several temperatures shows a double relaxation peak suggesting the presence of grains and grain boundaries in the sample. An analysis of the dielectric constants ε″ and loss tangent tan ( δ) with frequency shows a distribution of relaxation times. [ABSTRACT FROM AUTHOR]

Zinc potassium pyrophosphate KZnPO was synthesized using the conventional solid-state reaction. X-ray powder diffraction analysis proves the formation of a pure phase which crystallizes in the tetragonal system. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 614-718 K and 200 Hz-1 MHz, respectively, by means of impedance spectroscopy. The alternating current (AC) conductivity for grain contribution follows the universal Jonscher's power law. The frequency exponent s is temperature independent and equal to 0.8. The QMT model was proposed to be the most suitable model to characterize the electrical conduction mechanism in the titled sample. Dielectric data were analyzed using complex electrical modulus M* at various temperatures. The bulk relaxation time was found from the peaks position of the above spectra and the thermodynamic parameters were also found using the Eyring theory. [ABSTRACT FROM AUTHOR]

There is distinct deviation between the intrinsic and measurement value of Young's modulus in uniaxial compression tests. The key influence factor has always been owned to the friction between compression platens and specimen. However, we found this is not true by Finite element analysis (FEA) and experiments. FEA results show that the friction only makes a major influence on the plastic behavior, resulting in a barreling deformation, rather than on the elastic deformation behavior of specimen. In fact, the oblique contact between compression plate and specimen will severely influence the homogeneity of the stress field in specimen, and result in the deviation of the measured modulus value. This study can well interpret the relevant provision in ASTM E9-09 that only slim specimens (with aspect ratio ≥ 8) are suitable for the compression modulus tests. [ABSTRACT FROM AUTHOR]

The effect of aging on the nanohardness, modulus and creep properties of non-quenched and tempered steel wire strengthened by cold forming to an area reduction of 37% was investigated by nanoindentation. It was found that aging at 300 °C can improve the nanohardness, modulus, wear resistance and creep resistance of the cold-drawn non-quenched and tempered steel. An aging time longer than 2 h is not necessary since the degree of improvement decreases. The creep procedure of all tested samples includes two distinct stages, the transient creep and steady-state creep. Aging treatment slows down the creep rate at the steady-state stage. [ABSTRACT FROM AUTHOR]

An 8 μm epoxy film deposited on a 350 μm Si (100) Si wafer with a 0.4 μm Au transducer film deposited on top of the polymer film was used to evaluate the thermal conductivity, the modulus of the porous film, and the initiation of spalling upon laser beam irradiation on the back side of the Si wafer. The polymer films were characterized for pore microstructure using scanning electron microscopy and energy dispersive spectrometry. The polymer films were characterized using transient thermo reflectance (TTR) with laser beams illuminating the Au layer. The TTR signal from the polymer film showed only the thermal component and was characteristic of variations associated with thermal conduction into the film. To induce spalling, the back side was illuminated with a Nd-YAG laser beam with a 532 nm wavelength, pulse energy density 1.8 J/cm and a repetition rate of 10 Hz for 10 s in conjunction with TTR measurements on the front side. The TTR signal from the polymer film subjected to laser beam incidence from the backside of the Si wafer showed both the thermal and the acoustic components. The acoustic component was used to detect the initial stages of spalling or delamination. The acoustic oscillations were modeled using a modified wave equation to determine the velocity of sound and the modulus of the film. The results were also used to determine the effect of porosity on the modulus of the polymer film. The TTR signal was found to be very sensitive to detection of delamination without complete separation of the film. [ABSTRACT FROM AUTHOR]

The rubidium ammonium arsenate tellurate Rb(NH)HAsOHAsO.Te(OH) compound was obtained by slow evaporation at room temperature. The differential scanning calorimetry (DSC) has shown three phase transitions at 453, 483, and 491 K, confirmed by the differential thermal analysis (D.T.A). As for the differential thermogravimetric analysis (TG) curve, it has revealed that no mass loss was detected before 475 K. So, the phase transition observed at 453 K does not correspond to the decomposition of this material. Rb(NH)HAsOHAsO.Te(OH) was characterized by impedance spectroscopy technique measured in the 1 KHz-9.91 MHz frequency range from 298 to 483 K. Besides, the cole-cole ( z' versus z') plots were well fitted to an equivalent circuit built up by a parallel combination of resistance ( R), fractal capacitance (CPE), and Warburg element ( W). Furthermore, the conductivity evolution versus temperature has shown the presence of the ionic-protonic superconduction phase transition. The dielectric properties' dependence on both temperature and frequencies of the compound has been reported. The ionic-protonic conductivity and conductivity relaxation calculated from the impedance and modulus spectra, respectively, were found to be thermally activated. [ABSTRACT FROM AUTHOR]

Sn-substituted lead calcium iron niobate specimens with general formula (PbCa)(FeNb)SnO with 0.00 ≤ y ≤ 0.15 in steps of 0.03 have been synthesized using a two-stage method. The x-ray diffraction patterns for all the synthesized samples reveal a perovskite structure with pseudocubic symmetry. A small amount of pyrochlore phase was obtained along with the perovskite phase, decreasing with increasing Sn content up to y = 0.09. The temperature and frequency dependence of the dielectric and electrical properties of Sn-substituted lead calcium iron niobate were studied. Two dielectric anomalies were observed in ε- T plots for all the samples due to generation of oxygen vacancies. The temperature coefficient of relative permittivity, τ, decreased with increasing Sn content. The single, semicircular arc observed in Nyquist plots suggests a single relaxation process. The activation energies obtained from the temperature dependence of the relaxation time and grain resistance were found to be approximately comparable. [ABSTRACT FROM AUTHOR]

Mechanical properties of cylindrical bi-phasic high-entropy alloy CuZrTiAlNi (3 mm in diameter) were characterized by nanoindentation test in each phase. The results show that the constituent FCC phase is of low nanohardness (2.35 GPa) and modulus (60.9 GPa), while another constituent phase in the alloy, the HCP phase, shows much higher nanohardness (6.5 GPa) and modulus (115.3 GPa). Creep occurs in both phases during the indentation. [ABSTRACT FROM AUTHOR]

The KAlPO compound was prepared by conventional solid-state reaction technique. The structure is confirmed by X-ray powder diffraction. The frequency-dependent electrical properties of the sample were investigated in the temperature range of 528-668 K and in the frequency range of 209 Hz-5 MHz by impedance spectroscopy. The ac conductivity has been fitted and studied using Jonscher's equation, whose exponent s varied with the temperature, showing that the non-overlapping small polaron tunneling (NSPT) is the suitable model to describe the electrical conduction mechanism. The variation of dc conductivity suggests Arrhenius type. Besides, the modulus data were analyzed using the Kohlrausch-Williams-Watts (KWW) stretched exponential function. The peak positions ω of the above spectra shifted towards higher frequencies with the increase in temperature. Moreover, the value of activation energy for the bulk obtained from the analysis of equivalent circuit (1.11 eV) and modulus relaxation (0.91 eV) confirms that the transport is not due to a simple hopping mechanism and that the ion transport is probably due to the hopping of K ions along [101] tunnels direction. The thermodynamic parameters were also calculated. [ABSTRACT FROM AUTHOR]

Electrical properties of the NaCuFe(VO) compound were studied using complex impedance spectroscopy in the frequency range 300 Hz-5 MHz and temperature range (523-673 K). Both impedance and modulus analysis exhibit the grain and grain boundary contribution to the electrical response of the sample. The temperature dependence of the bulk and grain boundary conductivity were found to obey the Arrhenius law with activation energies E = 0.87 eV and E = 0.85 eV, respectively. The transport properties, such as hopping frequency ( ω), effective attempt frequency ( ω), and migration entropy ( S/K), have been calculated using the Almond and West formalisms. [ABSTRACT FROM AUTHOR]

II-NaFePO was prepared by conventional ceramic fabrication technique. Rietveld refinement, impedance properties, conductivity dispersion, electric modulus, and their scaling were carried out as a function of frequency and temperature. Thus, X-ray diffraction analysis indicates that the sample exhibits a single-phase nature with a monoclinic structure. In addition, analysis of Nyquist plots as well as modulus analysis revealed the contribution of two electrically active regions corresponding to bulk mechanism and distribution of grain boundaries. The near values of activation energies, obtained from the impedance and modulus spectra, confirm that the transport happens through an ion hopping mechanism, dominated by the motion of the Na ions in the framework of the investigated material resulting from intersecting tunnels or voids where Na is located. [ABSTRACT FROM AUTHOR]

Recently, porous Ti-Nb-based shape memory alloys have been considered as promising implants for biomedical application, because of their non-toxic elements, low elastic modulus, and stable superelasticity. However, the inverse relationship between pore characteristics and superelasticity of porous SMAs will strongly affect their clinical application. Until now, there have been few works specifically focusing on the effect of pore structure on the mechanical properties and superelasticity of porous Ti-Nb-based SMAs. In this study, the pore structure, including porosity and pore size, of porous Ti-22Nb-6Zr alloys was successfully regulated by adjusting the amount and size of space-holder particles. XRD and SEM investigation showed that all these porous alloys had homogeneous composition. Compression tests indicated that porosity played an important role in the mechanical properties and superelasticity of these porous alloys. Those alloys with porosity in the range of 38.5%-49.7% exhibited mechanical properties approaching to cortical bones, with elastic modulus, compressive strength, and recoverable strain in the range of 7.2-11.4 GPa, 188-422 MPa, and 2.4%-2.6%, respectively. Under the same porosity, the alloys with larger pores exhibited lower elastic modulus, while the alloys with smaller pores presented higher compressive strength. [ABSTRACT FROM AUTHOR]

The experimental study on the modulus and hardness (in-press rigidity) of ettringite is carried out in this work. Firstly, the ettringite is obtained by chemical synthesis method. Secondly, samples are formed by filling the ettringite into resin matrix. Thirdly, the indentation modulus and hardness of ettringite are measured with different indentation depths by virtue of the instrument of MTS Nanoindenter XP. Finally, analysis on the modulus and hardness of the ettringite is performed according to the sample unloading curves. The results given by this work indicate that the magnitude of the modulus is 20.07 GPa and the hardness is 0.613 GPa. [ABSTRACT FROM AUTHOR]

This paper describes novel ultraviolet (UV)-curable adhesives with an ultrafast curing rate which are fully cured within 8 s for optical pick-up (OPU) applications. Two kinds of oligomers (novolac epoxy acrylate and urethane acrylate), additives, and inorganic fillers were prepared for the formulation of the adhesives. In addition, three kinds of photo-initiator [2,2-dimethoxy-2-phenylacetophenone and 2-hydroxy-2-methylpropiophenone for surface curing and (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide (TMDPO) for deep curing] were mixed to increase the curing rate. Photo-differential scanning calorimetry (photo-DSC) analyses showed that the newly formulated UV adhesives had faster curing rate than conventional UV adhesives. The UV adhesives were applied to OPUs for DVD/CD-RW, and five kinds of reliability tests, i.e., thermal shock, low-temperature storage, high-temperature storage, high temperature/high humidity, and nonoperation shock tests, were conducted to evaluate the adhesive reliability. According to the results of reliability tests and thermal stress simulations, the UV adhesives with lower storage modulus ( E′) showed better thermal shock reliability due to lower thermal stresses. In addition, OPUs assembled using the UV adhesives passed all reliability tests. Consequently, the UV adhesives were successfully applied to OPUs in OPU production lines, contributing to mass production. [ABSTRACT FROM AUTHOR]

The bulk and shear modulus of metal matrix composites with various volume fractions of particles are modified based on the Eshelby's equivalent inclusion method combined with self-consistent scheme. By introducing the modified modulus, a new model, which can predict the particle size effects on the stress-strain relation under interfacial debonding damage between matrix and particles, is established. The results obtained from the present investigation show a better agreement with the experimental data. [ABSTRACT FROM AUTHOR]

In this paper, the electrical conductivity and relaxation studies in two different temperature regions ( T < T and T > T) on plasticized PEO-PMMA blend polymer electrolyte system with AgNO salt are reported. The polymer electrolyte system has been prepared by solution cast technique and characterized by X-ray diffraction and differential scanning calorimetry. The conduction and relaxation processes at various temperatures have been investigated in the framework of modulus formalism. The distribution of relaxation times is discussed using Argand plot. Variation in ionic conductivity of polymer blends is discussed with the increase of PEO as well as with temperature. [ABSTRACT FROM AUTHOR]

BaTiO film was prepared on Pt/Ti/SiO/Si substrate by the laser chemical vapor deposition method. A single-phase BaTiO film with $$ (\overline{3} 22)/(\overline{2} 23) $$ preferred orientation and columnar cross-section was obtained at high deposition rate (154.8 μm h). The dielectric constant ( ε) of the BaTiO film was 21, measured at 300 K and 1 MHz. The electrical properties of the BaTiO film were investigated by ac impedance spectroscopy from 300 K to 1073 K at 10 Hz to 10 Hz. Plots of the real and imaginary parts of the impedance ( Z′ and Z″) and electrical modulus ( M′ and M″) in the above frequency and temperature range suggested the presence of two relaxation regimes, which were attributed to grain and grain boundary responses. The ac conductivity plots as a function of frequency showed three types of conduction process at elevated temperature. The frequency-independent plateau at low frequency was due to dc conductivity. The mid-frequency conductivity was due to grain boundaries, while the high-frequency conductivity was due to grains. [ABSTRACT FROM AUTHOR]

Bridged polysilsesquioxanes are increasingly used to prepare protective coatings, particulate chromatographic materials, and adsorbents. However, little is known about the mechanical properties of the materials and how they are influenced by the nature of the bridging group. In this paper, we have prepared monolithic xerogels and aerogels of hexylene- and phenylene-bridged polysilsesquioxanes and have measured their flexural strength and modulus. Consistent with their compact structure, the porous, glassy phenylene- and hexylene-bridged xerogels were hundreds of stronger than the analogous aerogels. The nature of the bridging group did not appear to affect the mechanical properties of the xerogels, in contrast, it presented a profound effect on the mechanical properties of the aerogels. Phenylene-bridged aerogels were brittle and 30% stronger than silica aerogels of the same density. However, the opaque hexylene-bridged aerogels were found to be elastic and appreciably weaker than the phenylene-bridged or silica aerogels. [ABSTRACT FROM AUTHOR]

We present a scalable high-speed divide-by- N frequency divider using only basic digital CMOS circuits. The divider achieves high-speed operation using a novel parallel counter and a pipelined architecture. The parallel counter is based on a state look-ahead component in conjunction with an internal pipeline structure in order to simultaneously trigger all state value updates without a rippling effect. The pipeline latencies are precluded due to the use of a subtractor circuit that 'swallows' any additional cycles. Furthermore, our frequency divider is easily scalable to large divider widths due to the use of modular component architecture. The fan-in and fan-out are independent of the divider width, thus making the structure attractive for regular VLSI implementation and continued technology scaling. We implemented our proposed divider using a 0.15-μm TSMC digital cell library and achieved a maximum operating frequency of 2 GHz, an area of 112 848 μm (900 transistors), and consumed 15.47 mW of power operating at 2 GHz for an 8-bit design, which offers 252 different frequency divisions. [ABSTRACT FROM AUTHOR]

Certain tumors, such as breast, frequently metastasize to bone where they can induce bone destruction. Currently, it is well-accepted that the tumor cells are influenced by other cells and growth factors present in the bone microenvironment that lead to tumor-induced bone disease. Over the past 20 years, many groups have studied this process and determined the major contributing factors; however, these results do not fully explain the changes in gene expression and cell behavior that occur when tumor cells metastasize to bone. More recently, groups studying metastasis from soft tissue sites have determined that the rigidity of the microenvironment, which increases during tumor progression in soft tissue, can regulate tumor cell behavior and gene expression. Therefore, we began to investigate the role of the rigid bone extracellular matrix in the regulation of genes that stimulate tumor-induced bone disease. We found that the rigidity of bone specifically regulates parathyroid hormone-related protein (PTHrP) and Gli2 expression in a transforming growth factor β (TGF-β) and mechanotransduction-dependent mechanism. In this review, we summarize the mechanotransduction signaling pathway and how this influences TGF-β signaling and osteolytic gene expression. [ABSTRACT FROM AUTHOR]

In this work, a new phenomenological model is proposed to predict the flexural modulus of symmetric structural foams with complex density distribution across their thickness. The model is based on a generalized Fourier series to represent the density profile and the simple square power-law relation to relate density with modulus. The model predictions are compared with data on polyethylene (LDPE and HDPE) structural foams produced by compression and injection molding. The results show that a very high degree of agreement (less than 3% deviation) can be obtained for these complex structures. [ABSTRACT FROM AUTHOR]

This work reports on the solidification time of simple shaped molds obtained by a lumped parameter model as well as by solving with a finite volume-based numerical computation. The liquid metal has been assumed to be poured at an initial superheat, which is cooled under atmospheric condition. Heat losses from the mold wall by both convection and radiation have been taken into account. The energy equation is solved using a fixed-grid enthalpy approach. The liquid fraction of the mushy zone is obtained from a linear relationship with the temperature. The results from the numerical simulation with A356 as the material have been compared with the lumped parameter formulation relating the modulus of the object. As expected, the lumped solution under-predicts the solidification time. The ratio of actual solidification time with the time obtained from the lumped solution is correlated for the modulus value up to about 0.015. In the limiting case of zero-modulus, the ratio approaches a value of 2.37. [ABSTRACT FROM AUTHOR]

The lead pyrophosphate, PbPO, compound was prepared by conventional solid-state reaction and identified by X-ray powder diffractometer. PbPO has a triclinic structure whose electrical properties were studied using impedance spectroscopy technique. Both impedance and modulus analysis exhibit the grain and grain boundary contribution to the electrical response of the sample. The temperature dependence of the bulk and grain boundary conductivity were found to obey the Arrhenius law with activation energies E = 0.66 eV and E = 0.67 eV, respectively. The scaling behavior of the imaginary part of the complex impedance suggests that the relaxation describes the same mechanism at various temperatures. [ABSTRACT FROM AUTHOR]

In the first part of this article, we had introduced the notion of quadratic reciprocity and dwelt briefly on its history, which goes back all the way to the work of fermat. Then we discussed the Law of Quadratic Reciprocity ('QRL'), which Gauss named Theorema Aureum. Following this, we gave a not too well known proof of the QRL due to G Rousseau. Now we give two more proofs of the QRL , drawing respectively from ideas in linear algebra and field extensions; they too are not very well known. [ABSTRACT FROM AUTHOR]

Are there perfect squares which on division by 7 leave remainder 3? Are there perfect squares which on division by 3 leave remainder 7? (A "remainder of 7" on division by 3 is the same as a remainder of 1.) The answers: 'NO' and 'YES', respectively. These facts are stated by number theorists as follows: 3 is a quadratic non-residue modulo 7; 7 is a quadratic residue modulo 3. The notion of quadratic residue is far reaching, and the key theorem here is the Law of Quadratic Reciprocity , first stated by Euler in 1783, but with out proof, and first proved by Gauss, in 1796. The theorem is easy to state but is mysterious, as it reveals a connection between two questions that appear unconnected. Let p, q be distinct odd primes; then the questions are: "Is p a quadratic residue modulo p?" and "Is q a quadratic residue modulo p?" Gauss had a high regard for this result and called it Theorema Aureum, the Golden Theorem. Though it has been proved in many different ways, it retains its mystery. In this two part article we give three proofs of the theorem. The first one, described in this part, is based on group theory. [ABSTRACT FROM AUTHOR]

The elastic modulus and failure behavior of poly(urea-formaldehyde) shelled microcapsules were determined through single-capsule compression tests. Capsules were tested both dry and immersed in a fluid isotonic with the encapsulent. The testing of capsules immersed in a fluid had little influence on mechanical behavior in the elastic regime. Elastic modulus of the capsule shell wall was extracted by comparison with a shell theory model for the compression of a fluid filled microcapsule. Average capsule shell wall modulus was 3.7 GPa, regardless of whether the capsule was tested immersed or dry. Microcapsule diameter was found to have a significant effect on failure strength, with smaller capsules sustaining higher loads before failure. Capsule size had no effect on the modulus value determined from comparison with theory. [ABSTRACT FROM AUTHOR]

Low-K dielectric films have reduced hardness and modulus relative to traditional dielectric materials. There are many potential challenges associated with these materials to integrate with integrated circuit (IC) technologies. It is important to evaluate the mechanical properties of low-K materials along with their electrical characterization to implement them in sub—0.25μm devices. In this investigation, we have discussed the mechanical properties of low-K dielectric materials and evaluated the mechanical behavior of SiLK and Xerogel samples using nano-indentation studies. Surface behavior after indentation is also investigated with high resolution scanning electron microscopy. Nano-indentation using the continuous stiffness measurement technique is shown to be reliable for evaluating the mechanical properties of thin and low modulus films. [ABSTRACT FROM AUTHOR]

Silica gels can be made by direct reaction of formic acid with tetraethyl orthosilicate. We have characterized wet gels of this type using a beam-bending technique that yields the elastic modulus, Poisson’s ratio, viscoelastic relaxation function, and permeability. When the experiment is performed in ethyl formate, the silica network behaves in an elastic fashion; the permeability is low (<1 nm2), indicating a pore radius of <4.3 nm. The capillary pressure generated in such small pores is estimated to be sufficient to cause collapse of the pores during drying, which would account for the observed ultramicropores in this type of gel. When the pore liquid contains formic acid, viscoelastic relaxation is relatively rapid. Studies of cyclosiloxane compounds indicate that formic acid can attack only the strained siloxane bonds of the network, which would account for the relaxation behavior. Aging in formic acid causes rapid initial shrinkage, because formic acid accelerates condensation of silanols, which drives syneresis; the modulus increases and the permeability decreases monotonically, so there is no indication of coarsening during aging in formic acid, even at 70°C. [ABSTRACT FROM AUTHOR]

Lithium-containing aluminum alloys have shown promise for demanding aerospace applications because of their light weight, high strength, and good damage tolerance characteristics. Additions of ceramic reinforcements to an aluminum-lithium alloy can significantly enhance specific strength, and specific modulus while concurrently offering acceptable performance at elevated temperatures. The processing and fabrication of aluminum-lithium alloy-based composites are hampered by particulate agglomeration or clustering and the existence of poor interfacial relationships between the reinforcing phase and the matrix. The problem of distribution of the reinforcing phase in the metal matrix can be alleviated by mechanical alloying. This article presents the results of a study aimed at addressing and improving the interfacial relationship between the host matrix and the reinforcing phase. Copper-coated silicon carbide particulates are introduced as the particulate reinforcing phase, and the resultant composite mixture is processed by conventional milling followed by hot pressing and hot extrusion. The influence of extrusion ratio and extrusion temperature on microstructure and mechanical properties was established. Post extrusion processing by hot isostatic pressing was also examined. Results reveal the increase in elastic modulus of the aluminum-lithium alloy matrix reinforced with copper-coated SiC to be significantly more than the mechanically alloyed Al-Li/SiC counterpart. This suggests the possible contributions of interfacial strengthening on mechanical response in direct comparison with a uniform distribution of the reinforcing ceramic particulates. [ABSTRACT FROM AUTHOR]

Thin film nitride coatings were deposited on Si (100) substrates by the pulsed laser deposition (PLD) technique. The PLD method is a unique process for depositing high quality thin films with novel microstructure and properties. Boron nitride (BN) films deposited on Si (100) substrates have a higher percentage of c-BN phases when processed in higher nitrogen partial pressure. Titanium nitride films deposited on Si (100) substrates at a higher temperature (600 °C) have better quality crystallinity and higher hardness and Young’s modulus values than films deposited at lower temperatures. Nanoindentation technique was used to measure the mechanical properties of thin films. The film orientation was determined by x-ray diffraction. Atomic force microscopy (AFM) technique was used to understand the growth structure of the films. [ABSTRACT FROM AUTHOR]

The three- point bend strength, Young’s modulus, and vibrational damping of a plasma- sprayed molybdenum-coated Ti- 25Al- 10Nb- 3V- lMo intermetallic were measured. The bend strength of the intermetallic samples was significantly reduced as a result of the molybdenum coating. This decrease in the strength was attributed to cracks formed in the molybdenum coating during the plasma spraying process. Experimental measurements done using the piezoelectric ultrasonic composite technique (PUCOT) indicated that the modulus and vibrational damping of the coated samples were significantly higher than for the uncoated substrates. Thermal cycling of the molybdenum- coated intermetallic between 600 °C and room temperature revealed a saturation increase in the modulus with a corresponding decrease in the mechanical damping. This behavior was attributed to crack healing occurring in the molybdenum coating during the thermal cycling process. [ABSTRACT FROM AUTHOR]

Depth sensing indentation has been used to investigate the elasto-plastic behavior of Hg0.7Cd0.3Te prepared by molecular beam epitaxy, liquid phase epitaxy, as well as of bulk Hg0.7Cd0.3Te prepared by the modified Bridgman method. It was found that Hg0.7Cd0.3Te was characterized by a modulus of elasticity of Eavg ∼ 50 GPa and hardness of Havg ∼ 0.66 GPa, independent of growth technology. The measured hardness was observed to increase with decreasing size of indentation owing to the nucleation of dislocations within the plastic zone. The elasto-plastic response of the samples to nanoindentation was observed to be purely elastic at low indentation depths and developed into ∼ 10% elastic and ∼ 90% plastic response, with an increase in penetration contact depth to above 100 nm exhibiting significant amounts of creep. The transition from purely elastic to elasto-plastic behavior has been observed to be marked by discontinuities, or "pop-in" events in the indenter load-penetration curves, with the indentation zone maximum sheer stress varying with HgCdTe growth method in the range 1.1-1.8 GPa. This onset and subsequent flow of plasticity is postulated to be associated with the spontaneous nucleation and propagation of dislocations. [ABSTRACT FROM AUTHOR]