Search

The electrical signals generated by an electromechanical coupling mechanism in biomaterials have significant potential applications in the field of biomedical engineering. For example, the piezoelectric- or flexoelectric-induced electrical signals in bone biomaterials play an important role in facilitating self-repair, remodeling, and reshaping processes. Polyetheretherketone (PEEK) has been found to possess excellent mechanical properties and biocompatibility with bone, making it an outstanding choice as an implantable polymer material. It is particularly important to investigate the electromechanical response performance of PEEK materials. In this study, we experimentally examine the flexoelectricity of PEEK and evaluate its effective out-of-plane direct and converse flexoelectric coefficients. Using the piezoresponse force microscopy module of atomic force microscopy, we observe a clear converse flexoelectric effect in a PEEK disk-shaped sample. The effective out-of-plane converse flexoelectric coefficient of the PEEK disk-shaped sample is about μ 3333 eff = 0.21 ± 0.02 nN / V. The effective out-of-plane direct flexoelectric coefficient, determined through the bending experiment of a PEEK cantilever, is f 3113 eff = 17.61 nC/m, which is larger than that of polyvinylidene fluoride and is nearly two orders of magnitude superior over other biomaterials such as bone and hydroxyapatite. This indicates that PEEK materials have even greater potential for development and research in biomedical engineering applications such as intervertebral fusion, bone joint replacement, bone rehabilitation and regeneration, etc. [ABSTRACT FROM AUTHOR]

1. Male and female Chukar partridges are difficult to differentiate based on their morphology or by the Chromobox-Helicase-DNA binding (CHD) during early growth. 2. The current study developed a novel, simple, low-cost and rapid sexing protocol for Chukar partridges based on the newly defined sexing gene ubiquitin-associated protein 2 (UBAP2). 3. The length of polymorphism between UBAP2-W and UBAP2-Z homologous genes allows for easy sex discrimination in this species. Molecular sexing analysis was based on the simultaneous amplification of both genes, resulting in two distinct amplicons (947 bp and 535 bp) in heterogametic females and only a single band (535 bp) in homogametic males, which is easy to detect with agarose gel electrophoresis. 4. This technique is simple and convenient for genetic sex determination in Chukar partridges. [ABSTRACT FROM AUTHOR]

Geomagnetically induced currents (GICs) are one of the main manifestations through which space weather affects human technical facilities, and GICs constitute the final link in the solar wind‐magnetosphere‐ionosphere‐ground interaction chain. Therefore, understanding the responses of power grids to solar superstorms is crucial for space weather research and emergency preparedness purposes. In this work, we combine the Space Weather Modeling Framework with a ground conductivity model and a model of the Chinese Guangdong 500 kV power grid to investigate the response of the whole power grid if the 23 July 2012 solar superstorm had struck the Earth. The maximum |GICs| produced in the power grid by this event reach approximately 400 A, which is more than thrice those measured during a strong magnetic storm with Kp = 8. Based on statistical analyses of the strength and duration of large GICs at 54 substations and a comparison with the GICs responsible for the Hydro‐Québec power outage on 13 March 1989, we stipulate that the risk of GICs in the Guangdong 500 kV power grid is very high. The simulation results also reveal that field‐aligned currents can play an important role in producing GICs in middle‐ and low‐latitude power grids during solar superstorms. This finding provides crucial insight for understanding the factors that generate strong GICs at middle and low latitudes. Plain Language Summary: The Sun is not a particularly peaceful entity, it can abruptly launch powerful radiation and plasma into space. If such a coronal mass ejection (also called a solar storm) struck the Earth, there would be serious consequences for humanity. Specifically, solar storms can generate geomagnetically induced currents (GICs) in high‐voltage power transmission systems, which can damage transformers and even cause the whole system to collapse. How would a power grid respond to an extreme solar storm? Furthermore, how strong can the associated GICs be, and how serious are the consequences? To address these uncertainties, we built a model of the corresponding interaction chain based on physical principles. The model was driven by the solar wind conditions of a solar superstorm that occurred on 23 July 2012 and was observed by a satellite. We showed that even a low‐latitude power grid may collapse under the impact of a solar superstorm. Consequently, without sufficient preparation, the consequences of a solar superstorm for power grids worldwide could be devastating. Key Points: We built a model to simulate geomagnetically induced currents (GICs) in a power grid in China during a solar superstormGICs can reach hundreds of amperes in a low‐latitude power network during a solar superstormField‐aligned currents play an important role in producing GICs within low‐latitude power networks during solar superstorms [ABSTRACT FROM AUTHOR]

This paper aims to develop three-dimensional fundamental thermo-elastic solutions for an infinite/ half-infinite space of a two-dimensional hexagonal quasi-crystal, which is subjected to a point heat source. Starting from the newly developed general solution in terms of quasi-harmonic potential functions, the corresponding fundamental solutions are derived by means of the trial-and-error technique. Six appropriate potential functions involved in the general solution are observed. The present fundamental solutions are applied to construct boundary integral equations governing the contact problems. Numerical calculations are performed to show the distributions of the thermo-elastic coupling field variables in a half-space subjected to a point thermal source. [ABSTRACT FROM AUTHOR]

The general governing equation of transverse wave motion in a viscoelastic single-walled carbon nanotube (SWCNT) adhered by surface material is formulated on the basis of the nonlocal elasticity theory and the Kelvin model. The properties of transverse wave propagation in the SWCNT are investigated. The explicit expressions are derived for the frequency and phase velocity of the wave motion. The small scale and surface effects and the influences of structural damping on the properties of wave propagation are elucidated. It is concluded that the frequency and phase velocity of transverse wave propagation in the viscoelastic SWCNT are related to the small scale, surface elasticity, residual surface tension, and structural damping. The small scale and surface effects and the impact of structural damping on the properties of transverse wave propagation are dependent upon the wave number and tube diameter. [ABSTRACT FROM AUTHOR]

In this work, a unified formulation of full geometrically nonlinear refined shell theory is developed for the accurate analysis of highly flexible shell structures. The tensor calculus is utilized to explicitly derive the linear and nonlinear differential operator matrices of the geometrical relation in the orthogonal parallel curvilinear coordinate system. By employing the Carrera Unified Formulation (CUF), various kinematics of two-dimensional shell structures are consistently formulated via an appropriate index notation and a generalized expansion of the primary variables by arbitrary functions in the thickness direction, leading to lower- to higher-order shell models with only pure displacement variables. Furthermore, the principle of virtual work and a finite element approximation are exploited to straightforwardly formulate the nonlinear governing equations in a total Lagrangian approach. Particularly, the path-following Newton–Raphson linearization method based on the arc-length constraint is used to deal with the full geometrically nonlinear problem. Independent of the theory approximation order, the forms of the fundamental nuclei of the secant and tangent stiffness matrices of the unified shell element are formulated via the CUF and the three-dimensional Green-Lagrange strain components. Numerical assessments and comparisons of the present results with those provided in the literature for popular benchmark problems involving different metallic shell structures are found to be excellent and demonstrate the capabilities of the developed CUF shell model to predict the post-buckling, large-deflection, snap-through and snap-back nonlinear responses with high accuracy. [ABSTRACT FROM AUTHOR]

In this paper, we studied how field emission from thermally evaporated W18O49 nanowires depended on temperature. As the temperature changed from 300K to 723 K, we found anomalous changes in emission current. Below an applied field of ∼12.5V μm-1, the emission current tended to increase with rising temperature, while above 12.5V μm-1 the current depended less on temperature in the range of 573-723 K. Furthermore, at high temperatures, we found the Fowler-Nordheim plots of these nanowires to be nonlinear. We believe that the anomalous behavior is associated with surface states at low fields and field penetration at high fields. [ABSTRACT FROM AUTHOR]

In this study, we propose a phononic plate model with periodically corrugated surfaces and investigate the propagation behavior of Lamb waves in it. In contrast to the traditional phononic crystals which are composed of isotropic materials, the electroelastic coupling is taken into account in this investigation. Based on the Floquet's theorem, the Lamb wave solution is expanded in the series form of spatially harmonic plane waves. Band structures in the first Brillouin zone are presented graphically. The band gaps can be tuned by adjusting the structural parameters. We find that the structural symmetry of the plate has significant influence on the band gap properties. The symmetry breaking of the plate structure leads to more band gaps appearing in the first Brillouin zone. Moreover, the band gaps are also sensitive to the symmetry of the electric boundary conditions, which provides a feasible way to electrically control the acoustic band structure. © 2014 AIP Publishing LLC. [ABSTRACT FROM AUTHOR]

We present an analytical model to evaluate the magnetoelectric (ME) effects in functionally graded multiferroic laminated plates. The static and frequency-dependant ME effects in functionally graded piezoelectric and piezomagnetic (FGPP) bilayers with different gradations of the material property along the thickness are analyzed. The results show that the FGPP bilayers with special gradation have a stronger ME coupling effect than that in the homogeneous structure. The magnetic energy-harvesters made of FGPP bilayers achieve a larger output power as well. [ABSTRACT FROM AUTHOR]

Estimating the feed intake of grazing herbivores is critical for determining their nutrition, overall productivity and utilization of grassland resources. A 17-day indoor feeding experiment was conducted to evaluate the potential use of Medicago sativa as a natural supplement for estimating the total feed intake of sheep. A total of 16 sheep were randomly assigned to four diets (four sheep per diet) containing a known amount of M. sativa together with up to seven forages common to typical steppes. The diets were: diet 1, M. sativa + Leymus chinensis + Puccinellia distans ; diet 2, species in diet 1 + Phragmites australis ; diet 3, species in diet 2 + Chenopodium album + Elymus sibiricus ; and diet 4, species in diet 3 + Artemisia scoparia + Artemisia tanacetifolia. After faecal marker concentrations were corrected by individual sheep recovery, treatment mean recovery or overall recovery, the proportions of M. sativa and other dietary forages were estimated from a combination of alkanes and long-chain alcohols using a least-square procedure. Total intake was the ratio of the known intake of M. sativa to its estimated dietary proportion. Each dietary component intake was obtained using total intake and the corresponding dietary proportions. The estimated values were compared with actual values to assess the estimation accuracy. The results showed that M. sativa exhibited a distinguishable marker pattern in comparison to the other dietary forage species. The accuracy of the dietary composition estimates was significantly (P < 0.001) affected by both diet diversity and the faecal recovery method. The proportion of M. sativa and total intake across all diets could be accurately estimated using the individual sheep or the treatment mean recovery methods. The largest differences between the estimated and observed total intake were 2.6 g and 19.2 g, respectively, representing only 0.4% and 2.6% of the total intake. However, they were significantly (P < 0.05) biased for most diets when using the overall recovery method. Due to the difficulty in obtaining individual sheep recovery under field conditions, treatment mean recovery is recommended. This study suggests that M. sativa , a natural roughage instead of a labelled concentrate, can be utilized as a dietary supplement to accurately estimate the total feed intake of sheep indoors and further indicates that it has potential to be used in steppe grassland of northern China, where the marker patterns of M. sativa differ markedly from commonly occurring plant species. [ABSTRACT FROM AUTHOR]

We present an analytical model to predict the magnetoelectric (ME) effect in multiferroic laminated plates consisting of piezoelectric material and giant magnetostrictive material (GMM). The nonlinear behavior of GMM is taken into account by employing a simple quadratic constitutive relation. Both static and dynamic cases are considered. It is found that: (1) the dependence of ME effect on the applied magnetic field is quite different from that reported in the previous analysis; and (2) one part of the induced electric field has a frequency that is double the driving frequency of the applied magnetic field. The results indicate that multiferroic laminated plates with GMM layers have potential applications in multipliers and energy harvesters. [ABSTRACT FROM AUTHOR]

We solved analytically the magnetoelectric (ME) effect in a bilayered piezoelectric/piezomagnetic cylinder under harmonic excitation. We revealed that at a fixed thickness ratio of the layers, the static or low-frequency ME effect can be substantially enhanced by increasing the curvature of the cylinder. In the megahertz frequency domain, on the other hand, we observed that the peak ME effect can be considerably increased by decreasing the curvature. We further showed that at a fixed curvature, the ME effect can be tuned to be around the resonant frequency for giant output by varying the boundary condition and thickness ratio. [ABSTRACT FROM AUTHOR]

The optical, magnetic, and transport behaviors of Ge1-xMnxTe (x=0.24 and 0.55) grown by solid-source molecular-beam epitaxy are investigated. X-ray diffraction shows that Ge1-xMnxTe crystallizes in rocksalt structure. The temperature-dependent magnetization (M-T) for x=0.55 sample gives a Curie paramagnetic temperature of θp∼180 K, which is consistent with the temperature-dependent resistivity ρ(T) measurement. Anomalous Hall effect is clearly observed in the samples and can be attributed to extrinsic skew scattering based on the scaling relationship of ρxy∝ρxx1.06. The magnetoresistance of Ge1-xMnxTe is isotropic and displays a clear hysterestic loop at low temperature, which resembles that of giant-magnetoresistance granular system in solids. [ABSTRACT FROM AUTHOR]

Fluid–structure interaction is fundamental to the characteristics of the induced flows due to the motion of structures in fluids and also is crucial to the performance of submerged structures. This paper presents a three-dimensional analytical study of the intrinsic free vibration of an elastic multilayered hollow sphere interacting with an exterior non-Newtonian fluid medium. The fluid is assumed to be characterized by a compressible linear viscoelastic model accounting for both the shear and compressional relaxation processes. For small-amplitude vibrations, the equations governing the viscoelastic fluid can be linearized, which are then solved by introducing appropriate potential functions. The solid is assumed to exhibit a particular material anisotropy, i.e. spherical isotropy, which includes material isotropy as a special case. The equations governing the anisotropic solid are solved in spherical coordinates using the state-space formalism, which finally establishes two separate transfer relations correlating the state vectors at the innermost surface with those at the outermost surface of the multilayered hollow sphere. By imposing the continuity conditions at the fluid–solid interface, two separate analytical characteristic equations are derived, which characterize two independent classes of vibration. Numerical examples are finally conducted to validate the theoretical derivation as well as to investigate the effects of various factors, including fluid viscosity and compressibility, fluid viscoelasticity, solid anisotropy and surface effect, as well as solid intrinsic damping, on the vibration characteristics of the submerged hollow sphere. Particularly, our theoretically predicted vibration frequencies and quality factors of gold nanospheres with intrinsic damping immersed in water agree exceptionally well with the available experimentally measured results. The reported analytical solution is truly and fully three-dimensional, covering from the purely radial breathing mode to the torsional mode to any general spheroidal mode as well as being applicable to various simpler situations, and hence can be a broad-spectrum benchmark in the study of fluid–structure interaction. [ABSTRACT FROM AUTHOR]

In this paper, the complex variable method is applied to study three-dimensional problems of transversely isotropic functionally graded circular plates subjected to concentrated edge forces and couples. To that end, the extended England–Spencer plate theory is adopted to obtain the general solutions of the governing equations in which four analytic functions α (ζ) , β (ζ) , ϕ (ζ) and ψ (ζ) are involved. The material properties can vary along the thickness direction in an arbitrary fashion. The cylindrical boundary of the plate is considered to be free which is well known as the first kind basic problem in plane elasticity. Four analytic functions can be determined by the Cauchy's integral formula and conformal mapping technology. As a result, the 3D stress field is investigated for a transversely isotropic FGM circular plate whose cylindrical boundary is subjected to concentrated forces and couples. The proposed elasticity solutions can be used as benchmarks to validate solutions obtained based on various simplified plate theories or numerical methods. [ABSTRACT FROM AUTHOR]

The well-known general solution for uncoupled thermoelasticity of isotropic bodies was proposed by Goodier, which has been utilized extensively since its birth in 1937. When the steady-state response is considered, the temperature field satisfies Laplace's equation, and the corresponding elastic field can be expressed in terms of a harmonic function, giving rise to the Williams solution. However, for anisotropic bodies, there are no steady-state thermoelastic general solutions that are expressed in terms of (quasi)harmonic functions until 2000. This article presents a short review of the harmonic general solutions for uncoupled elasticity of transversely isotropic materials with thermal and other effects. These solutions are obtained by simply but forcedly combining the heat conduction equation with other governing equations (e.g., the Navier equations). We will show that the Williams solution as well as some other solutions all can be deduced as the special cases. Two application scenarios of the general solutions are also highlighted to demonstrate their elegance and versatility. [ABSTRACT FROM AUTHOR]

Presents information on a study which investigated strain-induced effects in quantum wells (QW) of InP substrates. Illustration of the calculated piezoelectric field for the strained QW; Interband transitions; Measurement of the critical layer thickness.

Presents a study which prepared an inverse parabolic quantum well (IPQW) using molecular-beam epitaxy by a digital compositional grading superlattice composed of Al[sub0.36]Ga[sub0.64]As/gallium arsenide. Description of the ideal IPQW; Measurement of the zero-field photoluminescence (PL) and photocurrent spectra; Display of representative PL spectra for the IPQW; Comparison of the behavior of IPQW and square quantum wells.

Presents a self-consistent analysis of electric field-dependent intersubband transitions for a thin layer inserted quantum well. Theoretical formulations; Optimization of the field-dependent 1-2 intersubband transition via adjustments of the quantum well parameters; Conclusions.

In this work we evaluated a novel microreactor prepared using a surface modified, high surface-to-volume ratio multi-lumen fused silica capillary (MLC). The MLC investigated contained 126 parallel channels, each of 4 μm internal diameter. The MLC, along with conventional fused silica capillaries of 25 μm and 50 μm internal diameter, were treated by (3-aminopropyl)triethoxysilane (APTES) and then modified with gold nanoparticles, of ∼20 nm in diameter, to ultimately provide immobilisation sites for the proteolytic enzyme, trypsin. The modified capillaries and MLCs were characterised and profiled using non-invasive scanning capacitively coupled contactless conductivity detection (sC4D). The sC4D profiles confirmed a significantly higher amount of enzyme was immobilised to the MLC when compared to the fused silica capillaries, attributable to the increased surface to volume ratio. The MLC was used for dynamic protein digestion, where peptide fragments were collected and subjected to off-line chromatographic evaluation. The digestion was achieved with the MLC reactor, using a residence time of just 1.26 min, following which the HPLC peak associated with the intact protein decreased by ＞70%. The MLC reactors behaved similarly to the classical in vitro or in-solution approach, but provided a reduction in digestion time, and fewer peaks associated with trypsin auto-digestion, which is common using in-solution digestion. The digestion of cytochrome C using both the MLC-IMER and the in-solution approach, resulted in a sequence coverage of ∼80%. The preparation of the MLC microreactor was reproducible with ＜2.5% RSD between reactors (n = 3) as determined by sC4D. [ABSTRACT FROM AUTHOR]

Based on the generalized England’s method, the three-dimensional elastic response in a transversely isotropic functionally graded elliptical plate with clamped edge subject to uniform load is investigated. The material properties can arbitrarily vary along the thickness direction of the plate. The expressions of the mid-plane displacements of the plate are constructed to meet the clamped boundary conditions in which the unknown constants are determined from the governing equations. The expressions of four analytic functions α(ζ), β(ζ), ϕ(ζ) and ψ(ζ) corresponding to this problem are then obtained using the complex variables method. As a result, the three-dimensional elasticity solution of a functionally graded elliptical plate with clamped boundary subject to uniform load is derived. Finally, numerical examples are presented to verify the proposed method and discuss the effects of different factors on the deformation and stresses in the plate. [ABSTRACT FROM AUTHOR]

Enterovirus A-71 (EV-A71) may be fatal, but the natural history, symptoms, and signs are poorly understood. This study aimed to examine the natural history of fatal EV-A71 infection and to identify the symptoms and signs of early warning of deterioration. This was a clinical observational study of fatal cases of EV-A71 infection treated at five Chinese hospitals between 1 January 2010 and 31 December 2012. We recorded and analysed 91 manifestations of EV-A71 infection in order to identify early prognosis indicators. There were 54 fatal cases. Median age was 21.5 months (Q1-Q3: 12-36). The median duration from onset to death was 78.5 h (range, 6 to 432). The multilayer perceptron analysis showed that ataxia respiratory, ultrahyperpyrexia, excessive tachycardia, refractory shock, absent pharyngeal reflex, irregular respiratory rhythm, hyperventilation, deep coma, pulmonary oedema and/or haemorrhage, excessive hypertension, tachycardia, somnolence, CRT extension, fatigue or sleepiness and age were associated with death. Autopsy findings (n = 2) showed neuronal necrosis, softening, perivascular cuffing, colloid and neuronophagia phenomenon in the brainstem. The fatal cases of enterovirus A71 had neurologic involvement, even at the early stage. Direct virus invasion through the neural pathway and subsequent brainstem damage might explain the rapid progression to death. [ABSTRACT FROM AUTHOR]

The IV-VI diluted magnetic semiconductor Ge1-xMnxTe thin films on BaF2 (111) substrate have been prepared using solid-source molecular-beam epitaxy technique by varying the Mn concentrations from x=0.25 to 0.98. The chemical Mn concentration was determined by x-ray photoelectron spectroscopy measurement. The in situ reflection high-energy electron diffraction pattern indicates that the growth mechanism is in the island-growth mode. The x-ray diffraction shows that the Ge1-xMnxTe films crystallize in the NaCl phase with (111) orientation. A clear ferromagnetic ordering is observed in the detailed temperature-dependent magnetization measurement for 0.25C on Mn concentration x tends to follow a quadratic behavior. This phenomenon can be attributed to the increase of antiferromagnetic interaction since MnTe is an antiferromagnet. [ABSTRACT FROM AUTHOR]

So far only a few approaches have been reported for the successful synthesis of 3D flower-like hierarchical gold nanostructures. In this paper, a facile, seedless and one-pot approach to synthesize a new class of flower-shaped gold nanoparticles with sheet-like petals has been proposed by reduction of HAuCl4 with ascorbic acid in (1-hexadecyl)trimethylammonium chloride solution, in the presence of silver nitrate (AgNO3). The growth of petals can be controlled and tuned by adjusting the amount of silver nitrate in the growth solution, and the reaction progress and evolution of the petals were monitored by time-course measurements via UV-vis-NIR spectroscopy and SEM to observe the growth mechanisms of nanoparticles. Besides, their optical properties, especially SERS performances, were also studied. These SERS-active gold nanoparticles were further utilized in the design of bright SERS tags for selectively in vitro imaging cancer cells. The results indicate that these Au NFs can be used as good SERS substrates or to design sensitive SERS sensors. [ABSTRACT FROM AUTHOR]

Human tumour necrosis factor α ( hTNF α) has been proved to be a validated therapeutic target in a number of immune-mediated inflammatory diseases ( IMIDs). Fully human monoclonal antibodies ( mAbs) that can neutralize soluble hTNF α ( sTNF α) as well as transmembrane hTNF α (tm TNF α) are more desirable hTNF α antagonists. Here, we report that novel anti- hTNF α human low-molecular-weight MAbs have been selected and identified using both sTNF α and tm TNF α as target antigens by the combination of ribosome display and E. coli expression system for the first time. As a newly born engineering small molecular antibody, three-domain antibody fragment ( VH/ κ) provides an alternative promising molecular principle to generate biological agents for TNF α-dependent IMIDs. In this study, a panel of novel human VH/κs (F09, F21, F49 and F409) with high affinity (10−10-10−9 mol/l) to neutralize sTNF α as well as tm TNF α was generated by the combination of ribosome display and E. coli expression system. Among the four clones, F21 and F409 could reduce cytotoxicity on L929 cells induced by sTNF α as well as tm TNF α effectively, and both of them had great potential to inhibit hTNF α-mediated NF- κB activation. Soluble F21 and F409 were also able to inhibit the binding of hTNF α to TNFR1 and TNFR2. The new human antibodies described here have desirable capability to neutralize sTNF α as well as tm TNF α effectively with high affinity and reasonable stability; this may provide an alternative approach for patients who are not responding adequately to currently available anti-TNF α agents. [ABSTRACT FROM AUTHOR]

We studied the propagation of extensional waves in a thin piezoelectric semiconductor rod of ZnO whose c-axis is along the axis of the rod. The macroscopic theory of piezoelectric semiconductors was used which consists of the coupled equations of piezoelectricity and the conservation of charge. The problem is nonlinear because the drift current is the product of the unknown electric field and the unknown carrier density. A perturbation procedure was used which resulted in two one-way coupled linear problems of piezoelectricity and the conservation of charge, respectively. The acoustic wave and the accompanying electric field were obtained from the equations of piezoelectricity. The motion of carriers was then determined from the conservation of charge using a trigonometric series. It was found that while the acoustic wave was approximated by a sinusoidal wave, the motion of carriers deviates from a sinusoidal wave qualitatively because of the contributions of higher harmonics arising from the originally nonlinear terms. The wave crests become higher and sharper while the troughs are shallower and wider. This deviation is more pronounced for acoustic waves with larger amplitudes. [ABSTRACT FROM AUTHOR]

The present paper theoretically investigates kink and kink-like waves propagating in pre-stretched Mooney-Rivlin viscoelastic rods. In the constitutive modeling, the Cauchy stress tensor is assumed to consist of an elastic part and a dissipative part. The asymptotic method is adopted to simplify the nonlinear dynamic equations in the limit of finite-small amplitude and long wavelength. Using the reductive perturbation method, we further derive the well-known far-field equation (i.e. the KdV-Burgers equation), to which two kinds of explicit traveling wave solutions are presented. Examples are given to show the influences of pre-stretch and viscosity on the wave shape and wave velocity. It is shown that pre-stretch could be an effective method for modulating the two types of waves. In addition, such waves may be utilized to measure the viscosity coefficient of the material. The competition between the effects of pre-stretch and viscosity on the kink and kink-like waves is also revealed. [ABSTRACT FROM AUTHOR]

The phase transformation behaviour and microsegregation profiles during solidification process of the 20SiMn2MoV as cast ingot was analysed using a computational simulation. Then a conservative estimate of the solidification temperature range was provided by the modified Scheil module of Thermo-Calc software, the result was combined with the previous results of the computational simulation and that were used to simulate the homogenization kinetics of this steel. The simulated maximum/minimum dendrite compositions were confirmed by the experimental composition analysis, the good agreement between the simulation and experiments shows that the thermodynamic calculation and kinetic simulation approaches can be used to design an optimised homogenisation heat treatment for as cast ingots, this method does not need a large amount of experimental data of test ingots. [ABSTRACT FROM AUTHOR]

The relationship between sheep diet selection and the vertical/horizontal availability of plant species on complex natural Leymus chinensis grassland was investigated. Two plots (low and high stocking rate plots) with different vegetation availabilities, created by adjusting sheep numbers, were studied for 3 months (June, July and August). In each month, the sheep's diet composition was estimated using n-alkanes in combination with long-chain alcohols and/or fatty acid markers. Vertical (sward surface height) and horizontal food availability (proportion cover of individual plant species) were determined simultaneously. The results revealed that sheep diet composition varied greatly according to seasonal variations in vegetation availability, and that sheep diet selection was related to the vertical and horizontal availability of plant species on both plots. Horizontal availability, which turned out to be the main influencing factor, was strongly and positively correlated with sheep diet composition in each month on both plots. On the low stocking rate plot, vertical availability affected sheep consumption in June, July and August. In contrast, a significant correlation between diet composition and vertical availability was only observed in July on the high stocking rate plot. These results suggest that the relative importance of vertical and horizontal availability differed between plots depending on vegetation availability. Horizontal availability played a more important role than vertical availability when sheep grazed freely on natural L. chinensis grassland. Finally, the changing selectivity index for each plant species in each grazing period on both plots indicated different grazing impacts on vegetation communities when vegetation availability differed. [ABSTRACT FROM PUBLISHER]

The effect of out-of-plane pre-stretch on the 2D sonic crystal with stretchable elastomeric scatterers is explored. The hyperelastic scatterers are characterized by a compressible neo-Hookean model. The Dirichlet-to-Neumann (DtN) map is adopted to obtain the band structure and equi-frequency contours. We focus on the first passband and find that a variety of switching functionalities for refraction behaviors can be realized in selected frequencies under a specific pre-stretch range. These refraction switches enable an active control of wave propagation and are applicable in advanced technologies where switchable and multifunctional sonic crystals are required. [ABSTRACT FROM AUTHOR]

Interleukin-22 ( IL-22) and IL-22-producing T helper ( Th) cells are involved in the pathogenesis of autoimmune diseases. However, the roles of IL-22 and IL-22-producing T helper cells in systemic lupus erythematosus ( SLE) remain unclear. Plasma levels of IL-22 were measured in 41 patients with SLE (19 new-onset and 22 relapsing patients) and 20 healthy controls by enzyme-linked immunosorbent assay ( ELISA). Meanwhile, the percentages of CD4+ IFN- γ+ (Th1), CD4+ IL-17+ (Th17) and CD4+ IFN- γ− IL-17− IL-22+ ( Th22) cells in peripheral lymphocytes were determined by flow cytometry, and plasma IL-22 autoantibodies were detected by ELISA in 19 new-onset SLE patients and 20 healthy controls. Plasma IL-22 levels in new-onset SLE patients were significantly decreased compared with relapsing SLE patients and healthy controls. After treatment with prednisone and hydroxychloroquine, the levels of plasma IL-22 in new-onset SLE patients were obviously increased but still lower than healthy controls. There was a positive correlation between plasma IL-22 levels and the percentages of Th22 cells, but not Th1 and Th17 cells. Moreover, plasma IL-22 levels as well as peripheral Th17 and Th22 cells correlated with SLE disease activity index ( SLEDAI) scores and erythrocyte sedimentation rate ( ESR). High frequencies of plasma IL-22 autoantibodies were detected in new-onset SLE patients. However, IL-22 levels did not correlate with IL-22 autoantibody. Decreased plasma IL-22 levels and correlation with Th22 cells may be distinct features in new-onset SLE. Moreover, IL-22 and Th22 cell correlated with SLE disease activity. [ABSTRACT FROM AUTHOR]

Temperature dependence of field emission characteristics of tungsten sub-oxide (W18O49) nanowires was investigated in the range from 143 K to room temperature. It is found that the field emission currents under the same applied electrical field decrease with the decreasing temperature. A two-step process involving the phonon-assisted tunneling from defect states to conduction band was introduced to explain the observed phenomenon. A good agreement between the theoretical and experimental results was achieved. [ABSTRACT FROM AUTHOR]