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It has been well-known that the Ingard-Myers impedance condition, while simple to apply, is subject to the hydrodynamic Kelvin-Helmholtz-type instability due to its use of a vortex sheet in modeling the flow at the liner boundary. Recently, in the development of a time domain boundary element method for acoustic scattering by treated surfaces, it was found that by neglecting a certain second-order spatial derivative term in the Ingard-Myers formulation, the hydrodynamic instability can be avoided. The present paper aims to provide further analysis of this modified condition, hereby referred to as the Truncated Ingard-Myers Impedance Boundary Condition (TIMIBC). It will be shown, based on the dispersion relations of linear waves, that the instability intrinsic to the Ingard-Myers condition is eliminated in the proposed new formulation. Quantitative assessments on the accuracy of the TIMIBC for scattering of acoustic waves by lined surfaces are carried out, and its effectiveness is demonstrated by a numerical example. It is found that the TIMIBC provides a good approximation to the original Ingard-Myers condition for flows of low to mid subsonic Mach numbers. As such, the proposed TIMIBC can offer a practical solution for overcoming the intrinsic instability associated with the Ingard-Myers condition. Moreover, time domain implementation of the TIMIBC is also discussed and illustrated with a numerical example using a finite difference scheme. In particular, a minimization procedure for finding the poles and coefficients of a broadband multipole expansion for the impedance function is formulated by which, unlike the commonly used vector-fitting method, passivity of the model is ensured. [ABSTRACT FROM AUTHOR]

A reverse calculation method termed soil and lining physics‐informed neural network (SL‐PINN) is proposed for the estimation of load for tunnel lining in elastic soil based on radial displacement measurements of the tunnel lining. To achieve efficient and accurate calculations, the framework of SL‐PINN is specially designed to consider the respective displacement characteristics of surrounding soil and tunnel lining. A multistep training method based on the meshless characteristics of SL‐PINN is established to promote calculation efficiency. The multistep training method involves increasing the number of collocation points in each calculation step while decreasing the learning rate after scaling of SL‐PINN. The feasibility of SL‐PINN is verified by numerical simulation data and field data. Compared to other inverse calculation methods, SL‐PINN has lower precision requirements for the measurement instrument with the same level of calculation accuracy. [ABSTRACT FROM AUTHOR]

OAT-affected patients have significant difficulties in achieving pregnancy through spontaneous intercourse, and ICSI is the clinical treatment of choice for these patients. Here, we identified a novel nonsense I PNLDC1 i variant in a patient with Oligo-astheno-teratozoospermia (OAT) and poor clinical outcomes of intracytoplasmic sperm injection (ICSI) from a consanguineous Chinese family. [Extracted from the article]

Acoustic liners are an effective tool for noise reduction and are characterized by a frequency-dependent impedance value. In this paper, a time-domain boundary element method for acoustic scattering coupled with a broadband impedance boundary condition is studied for the case of no mean flow. A Burton-Miller reformulation of the time domain boundary element method for acoustic scattering is carried out with both the pressure and its surface normal derivative terms retained. A multipole impedance model is converted into the time domain and used for enforcing an impedance boundary condition over a wide range of frequencies. Discretization of the coupled system is described. In particular, the time-domain impedance boundary condition is discretized by the third-order implicit backward difference scheme. Stability of the coupling is assessed by an eigenvalue analysis. Scattering solutions that demonstrate the validity and stability of the numerical method are presented. [ABSTRACT FROM AUTHOR]

Individuals with diabetes mellitus (DM) have an increased risk of fracture. Glycemic control is crucial to the management of DM, but there are concerns pertaining to hypoglycemia development in the course of glycemic control target achievement. The extent to which glycemic control may affect the risk of fracture remains less defined. Hypoglycemia-induced falls have been suggested to contribute to an elevated risk of fracture in DM patients. In this meta-analysis of observational studies, we aimed to investigate the relative contribution of glycemic control, as measured by glycated hemoglobin (HbA1c), and hypoglycemia to the risk of fracture in DM. The PubMed and Web of Science databases were searched for relevant studies. A random-effects model was used to generate summary relative risks (RRs) and 95% confidence intervals (CIs). Both increased HbA1c levels (RR per 1% increase 1.08, 95% CI 1.03, 1.14; nstudies = 10) and hypoglycemia (RR 1.52, 95% CI 1.23, 1.88; nstudies = 8) were associated with an increased risk of fracture. The association between HbA1c levels and the risk of fracture was somewhat nonlinear, with a noticeably increased risk observed at an HbA1c level ≥ 8%. The positive associations of HbA1c levels and hypoglycemia with the risk of fracture did not reach statistical significance in the studies that adjusted for insulin use, hypoglycemia, or falls for the former and in those that adjusted for falls for the latter. In summary, both increased HbA1c levels and hypoglycemia may increase the risk of fracture in patients with DM. The positive association between HbA1c levels and the risk of fracture appears to be, in part, explained by hypoglycemia-induced falls, possibly due to insulin use. The avoidance of hypoglycemia in the course of achieving good glycemic control through the careful selection of glucose-lowering medications may contribute to fracture prevention by reducing the risk of falls related to treatment-induced hypoglycemia. [ABSTRACT FROM AUTHOR]

The mechanical integrity of the sealant material is of key importance for the long-term, reliable operation of solid oxide fuel/electrolysis cell stacks. However, in-situ monitoring and detection of potential failures in sealing materials using classical electrochemical characterization techniques are difficult tasks. Therefore, in this work, the acoustic emission (AE) technique is applied to monitor and characterize the failure process of a glass-ceramic sealant exposed to torsional shear strength at both room and typical stack operation temperature (750 °C). Hourglass-shaped steel specimens are produced for the tests. A glass-ceramic material with two different porosities is used to join the specimens. The failure process is characterized in terms of AE peak amplitude, AE cumulative hits and AE energy, as well as the average frequency content of the signals. The results indicate that the degree of microscopic damage can be determined from the analysis of the AE energy and the fracture mechanisms can be found by statistical analysis of the average frequency of the signals. The fractured surfaces are visualized by optical microscopy to unveil that specimens with high porosity showed a fully cohesive fracture pattern, while specimens with low porosity showed a partially fracture pattern. As a result, AE method promises to be a potential in-operando technique for monitoring mechanical failure processes inside solid oxide cell stacks. • AE monitoring of glass ceramic sealants under torsion reveals different emission patterns. • Propagation of cracks in high-porosity specimens is faster than in low-porosity specimens. • Analysis of the average frequency content of signals reveals matrix cracking. • Post-test analysis reveals two fracture patterns in the glass-ceramic sealants. [ABSTRACT FROM AUTHOR]

One of the essential components for ensuring the long service life of solid oxide cell (SOC) stacks is the sealant used. Therefore, in this work, an experimental investigation of the glass ceramic sealant (GCS) fracture process was carried out using an Acoustic Emission (AE) based approach. A series of tensile tests at room temperature were performed and the acoustic activity emitted was recorded by two AE sensors. An AE signal analysis was then performed using two approaches: wave mode identification and frequency content analysis. To understand the fracture process of the GCS, the analysis was supported with prior knowledge of the GCS microstructure and a post-test visual analysis. This demonstrated the presence of low-frequency failure mechanisms (50–400 kHz) such as debonding, fiber pull-out and matrix cracking, and high-frequency mechanisms (>400 kHz) such as fiber breakage. The results confirm the suitability of using the acoustic emission approach for monitoring failure events and show its potential application in SOC stacks monitoring. Image 1 • AE applied to understand fracture of glass ceramic sealant in SOCs. • Tensile tests are performed at room temperature and AE signals are recorded. • Identification of fracture mechanisms of sealant can be achieved. • Wave mode and frequency analysis is used to identify the fracture mechanisms. [ABSTRACT FROM AUTHOR]

Based on the oxygen ion conductor La2Mo2O9, a series of K, Fe, and Mn doped samples La1.95K0.05Mo2-xTxO9-δ (T=Fe,Mn; x=0,0.025,0.05,0.1) were prepared with conventional solid-state reaction method. The effects of Fe and Mn doping on the cationic and anionic ions diffusion, phase transition, and electrical conductivity were studied. The mechanical spectroscopy (or internal friction) technique was exploited to investigate the microscopic transport mechanism and to deduce the dynamical relaxation parameters. Three internal friction peaks (PL, PH, and PM) were observed in the La1.95K0.05Mo2-xTxO9-δ samples, among which PL and PM are of relaxational type while PH is associated with a kind of phase transition. The results revealed that peak PL is originated from the short-distance jumps of oxygen vacancies, while peak PM is associated with the short-distance diffusion of Mn (Fe) ions and peak PH with the phase transition from the static disordered state to the dynamic disordered state of oxygen ion distribution. Based on the results of conductivity measurements, it can be concluded that the high-temperature conductivity of La2Mo2O9 can be improved obviously by the Fe or Mn doping at Mo site and the low-temperature conductivity can be increased by the simultaneous K doping at La site. [ABSTRACT FROM AUTHOR]

The microstructure and optical dielectric constants of HfOxNy thin films deposited by using radio frequency reactive magnetron sputtering have been investigated at various substrate temperatures. Fourier transform infrared spectroscopy spectra indicate that an interfacial layer has been formed between the Si substrate and the HfOxNy thin film during deposition. Spectroscopy ellipsometry (SE) results show that the substrate temperature has a strong effect on physical properties of HfOxNy thin films such as refractive index n and extinction coefficient k. Meanwhile, the optical dielectric functions of the films have determined using SE data and optical absorption properties of HfOxNy thin films deposited at different substrate temperatures have also been studied. [ABSTRACT FROM AUTHOR]

Abstract Solid oxide fuel cell is a promising technology to convert renewable energy sources to electricity electrochemically at high efficiencies, thus an important applied research topic worldwide. The in-house developed so-called F-stack-design aims at stationary applications and can achieve a very long lifetime. However, since production costs should be reduced, one research focus lies on finding suitable less expensive materials. Therefore, alternatives for the benchmark Ni-mesh as anode contacting element in the stack were studied. Several types of Ni-coated-steels were tested in a stack. After 3000 h of operation the different anode contact materials are compared with the Ni-mesh in terms of microstructure as well as chemical composition. A discussion of the results is given. Highlights • All anode contact materials degraded similarly. • The stainless steel 430 with thin Ni-coating shows the best behavior. • The Ni-coating of the low-carbon-steel vanishes. • The Ni-coated-steel-meshes are strongly subjected to oxidation and are not suitable. [ABSTRACT FROM AUTHOR]

Abstract It is well-known that the convective wave equation with a uniform mean flow can be transformed into a standard wave equation without flow by a Prandtl-Glauert-Lorentz type transformation. This paper examines the boundary condition to be used in the transformed coordinates for acoustic scattering by rigid bodies. Recently, based on the energy conservation equation for acoustic waves propagating in a uniform flow, a new solid wall boundary condition, dubbed the Zero Energy Flux (ZEF) solid surface boundary condition, has been proposed. Instead of the commonly used solid surface boundary condition that the normal acoustic velocity be zero, the ZEF condition requires that the acoustic energy flux be zero. In this paper, we point out that when formulated in the acoustic velocity potential and under the ZEF boundary condition, the normal derivative of the velocity potential remains to be zero when computed in the transformed coordinates. As such, numerical methods developed for solving the standard wave equation can be directly applied to the convective wave equation through a use of the Prandtl-Glauert-Lorentz transformation. Utilization of the transformation is particularly beneficial for numerical methods based on the boundary integral formulation because of the simplified kernel function in the transformed coordinates, for both the time domain and the frequency domain approaches. Useful relations for applying the transformation are derived and numerical examples that demonstrate the effectiveness of the transformation and ZEF boundary condition are presented. [ABSTRACT FROM AUTHOR]

Objectives: Kaposi's sarcoma (KS) is a multicentric angioproliferative cancer of endothelial origin typically occurring in the context of immunosuppression or immunodeficiency. Consequently, KS is one of the most common cancers in HIV‐infected individuals and frequently occurs among transplant recipients. Nevertheless, its incidence in different populations is not well understood. Methods: We searched online databases for publications on KS incidence. A random‐effect meta‐analysis was performed to combine the KS incidences and incidence rate ratios (IRRs) for associated risk factors. Results: Seventy‐six eligible studies representing 71 time periods were included. For HIV‐infected people, the overall KS incidence was 481.54 per 100 000 person‐years with a 95% confidential interval (CI) of 342.36–677.32 per 100 000 person‐years. HIV‐infected men who have sex with men (MSM) had the highest incidence of KS (1397.11 per 100 000 person‐years; 95% CI 870.55–2242.18 per 100 000 person‐years). The incidence of KS was significantly lower in female than in male individuals (IRR 3.09; 95% CI 1.70–5.62). People receiving highly active antiretroviral therapy (HAART) had a lower incidence compared with people who had never received HAART (IRR 6.57; 95% CI 1.91–24.69). The incidence of KS was 68.59 (95% CI 31.39–149.86) per 100 000 person‐years in transplant recipients, 52.94 (95% CI 39.90–70.20) per 100 000 person‐years in children with HIV infection, and 1.53 (95% CI 0.33–7.08) per 100 000 person‐years in the general population. Conclusions: Globally, a relatively high incidence of KS was found among HIV‐seropositive people and, in particular, in HIV‐infected MSM. The introduction of HAART has largely prevented the development of KS, but it has not entirely removed the challenge of KS. In Africa, in particular, KS imposes a very heavy disease burden, which can mainly be attributed to the high prevalence of KS‐associated herpesvirus and poor access to HAART. [ABSTRACT FROM AUTHOR]

High temperature water electrolysis with solid oxide electrolysis cells (SOECs) is a promising method for hydrogen production. In order to study the performance and degradation behavior of cells with different cell components in electrolysis mode, a four-cell stack was assembled that used JÜLICH's F10 design with two types of air electrodes based on La 0.6 Sr 0.4 CoO 3−δ (LSC) and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF). A PVD-prepared GDC layer was applied to LSCF cells while a screen-printing GDC layer was used in the LSC cells. The performance of the stack was first characterized with IV-curve measurements in both SOFC and SOEC modes within the temperature range of 700–800 °C. The durability of the stack was investigated by conducting a long-term stationary electrolysis operation with a constant current density of −0.5 Acm −2 and steam conversion rate of 50% at 800 °C. Electrochemical Impedance Spectroscopy (EIS) was used to study the electrochemical performance of the stack, as well as the degradation behavior during long-term electrolysis operation. The method “Distribution of Relaxation Times” (DRT) was applied for the further analysis of the EIS data, and the DRT results have successfully supported the stack degradation analysis. [ABSTRACT FROM AUTHOR]

It has been well-known that under the assumption of a uniform mean flow, the acoustic wave propagation equation can be formulated as a boundary integral equation. However, the constant mean flow assumption, while convenient for formulating the integral equation, does not satisfy the solid wall boundary condition wherever the body surface is not aligned with the assumed uniform flow. A customary boundary condition for rigid surfaces is that the normal acoustic velocity be zero. In this paper, a careful study of the acoustic energy conservation equation is presented that shows such a boundary condition would in fact lead to source or sink points on solid surfaces. An alternative solid wall boundary condition, termed zero energy flux boundary condition, is proposed that conserves the acoustic energy and a time domain boundary integral equation is derived. Furthermore, stabilization of the integral equation by Burton-Miller type reformulation is presented. The stability is studied theoretically as well as numerically by an eigenvalue analysis. Numerical solutions are also presented that demonstrate the stability of the current formulation. [ABSTRACT FROM AUTHOR]

Contents Microbial environment is one of the important factors that affect the quality of preserved semen. Iodine methionine ( IM), participating in the production and activation of metabolic enzymes, is a new type of amino acid chelate. To date, there has been no report to evaluate the effects of IM on boar semen preservation at 17°C. This study was designed to investigate the effects of IM on boar sperm quality and reproductive performance during liquid storage at 17°C and its antibacterial effect. Semen samples collected from six Yorkshire boars were diluted with basic liquid containing different concentrations of IM (0, 20, 40, 80, 160 and 320 μM). Subsequently, sperm motility, plasma membrane integrity and acrosome integrity were determined. After 6 days of preservation, the difference in microbial composition between control group and 80 μM IM group was compared using 16S rDNA sequencing, and the effects of IM on reproductive performance were also compared and analysed between the two groups. The results demonstrated that 20, 40 and 80 μM IM improved boar sperm motility, plasma membrane integrity and acrosome integrity. 80 μM IM was the optimum concentration. Conversely, 160 and 320 μM IM resulted in deleterious consequences to boar sperm quality compared to the control group and other treatment groups ( p < .05). After 6 days of preservation, sperm motility, plasma membrane integrity and acrosome integrity were 56.0%, 51.8% and 59.4%, respectively. There was no significant difference in non-return rate between the two groups ( p > .05). But the litter size of 80 μM IM group was significantly higher than that of control group ( p < .05). 80 μM IM inhibited proliferation of the phylum Proteobacteria and the genus Staphylococcus as well as Pseudomonas ( p < .05). Further studies are required to understand the antibacterial mechanism of IM in liquid-preserved boar semen. [ABSTRACT FROM AUTHOR]

Deficit irrigation has been shown to increase crop water use efficiency (WUE) under certain conditions, even though the yield is slightly reduced. In this study, the Root Zone Water Quality Model (RZWQM) was first calibrated with measured data from a large weighing lysimeter from 1998 to 2003 at the Yucheng Experimental Station in the North China Plain for daily evapotranspiration (ET), soil water storage (0-120 cm), leaf area index (LAI), aboveground biomass, and grain yield. The calibrated model was then used to explore crop responses to ET-based irrigation management using weather data from 1958 to 2015 and identify the most suitable ET-based irrigation schedules for the area. Irrigation amount was determined by constraining irrigation to a percentage of potential crop ET (40%, 60%, 80%, and 100% ETc) at the various growth stages of wheat [planting to before winter dormancy (P-D), green up to booting (G-B), booting to flowering (B-F), and flowering to maturity (F-M)] and of maize [planting to silking (P-S) and silking to maturity (S-M)], subject to seasonal water availability limits of 100/50, 200/100, 300/150, and 400/200 mm and no water limit for wheat/maize seasons, respectively. In general, wheat was more responsive to irrigation than maize, while greater influence of weather variation was simulated on maize than on wheat. For wheat with seasonal water limits, the highest average WUE was simulated with the highest targeted ETc levels at both the G-B and B-F stages and lower targeted ETc levels at the P-D and F-M stages. However, the highest average grain yield was simulated with the highest targeted ETc levels at all four growth stages for no water limit and the 400 mm water limit, or at both the G-B and B-F stages for the 300 and 200 mm water limits. For maize, lower targeted ETc levels after silking did not significantly affect maize production due to the high season rainfall, but irrigation of 60% ETc before silking was recommended. These results could be used as guidelines for precision irrigation along with real-time weather information. [ABSTRACT FROM AUTHOR]

Current maize hybrids have lower critical aboveground biomass nitrogen (N) concentration (TCNP) and grain N concentration (GNC) compared to older hybrids, but few crop models have incorporated this trend. The objective of this study was to evaluate alternative algorithms for calculating TCNP (biomass-based method) and GNC (grain N demand based on N dilution curve) for predicting crop N concentration and N uptake for a current maize hybrid in the CERES-Maize model as implemented in the Root Zone Water Quality Model (RZWQM). Experimental data were obtained from a field study on maize irrigated to meet various percentages (40% to 100%) of evapotranspiration demand at both vegetative and reproductive stages in 2012 and 2013 in Greeley, Colorado. The original RZWQM showed little response of aboveground N concentration (AGBNC) to the irrigation treatments and overpredicted GNC in both years. As a result, crop N uptake was generally overpredicted, with root mean square error (RMSE) values of 28 to 60 kg N ha-1 for the two years. Adjusted coefficients in the original TCNP and GNC algorithms (RZWQM_ADJ) effectively reduced the overpredicted GNC but with less improvement in response to the irrigation treatments in 2013 compared with the original RZWQM simulations. The RZWQM with modified TCNP and GNC algorithms simulated lower GNC and AGBNC than the original version, significantly improved the responses to the irrigation treatments, and captured the variations in measured GNC among seasons. The corresponding crop N uptake simulations improved more in 2012 than in 2013, with lower RMSE values of 16 to 32 kg N ha-1 than the original and RZWQM_ADJ versions. The better-predicted grain N uptake by the alternative algorithms could be helpful to making better crop N management decisions under different deficit irrigation conditions. [ABSTRACT FROM AUTHOR]

Various artificial multilayers consisting of YDy BaCuO/REO/YDyBaCuO films (RE = Y, Gd, Eu, etc.) about 1 μm in a sandwich-type structure are fabricated on oxide-buffered Hastelloy substrates using low-fluorine metalorganic deposition (MOD) method. Superconducting and microscopic performances are studied on composite YDyBaCuO multilayer films with and without intercalated YO, GdO, and EuO ultrathin films. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) are used to investigate growth orientation and surface morphology, revealing that multiple superconducting YDyBaCuO thin films separated by an ultrathin REO interlayer have better c-axis orientation, better in-plane and out-plane textures, as well as superior surface morphology. Using this interlayer technology, a significant enhancement of critical current density ( J ) both in self-field and under applied magnetic field is obtained. [ABSTRACT FROM AUTHOR]

YEuBaCuO(x = 0, 0.1, 0.3, 0.5) thin films were prepared on buffered substrates by trifluoroacetate metal organic deposition (TFA-MOD). The europium-doped film showed better out- and in-plane texture than the pure YBaCuO thin film and special topography. In the meantime, the superconducting transition temperature T was improved with the increase of europium content and spanned a small range when x= 0.5 doping levels. Besides, the J value was obviously enhanced with europium addition, and YEuBaCuO showed the best superconducting properties under self-field. Furthermore, the J value was obviously improved under magnetic field, and the enhanced flux-pinning properties was also observed in europium-substituted samples which may be attributed to the good grain connections and the effective flux pinning centers introduced by europium addition. The thickness of prepared film samples were approximately 400 nm. The structure of samples were characterized by x-ray diffraction (XRD), Raman spectrum was used to investigate the crystallization and growth orientation, and the surface morphology of films were got by field-emission scanning electronic microscopy (FE-SEM). Moreover, energydispersive spectroscopy (EDS) was utilized to determine element composition. Spatial distribution of J of the film was obtained by mapping analysis of inductive measurement at 77 K. And the superconducting properties under magnetic fields were measured by magnetic property measurement system with a SQUID magnetometer. [ABSTRACT FROM AUTHOR]

We investigate the state feedback pinning synchronization of fractional-order complex networks. Based on the stability theory of fractional-order differential systems and state feedback control by a single controller, synchronization conditions for fractional-order complex networks are given. We assume that the coupling matrix is irreducible, and provide a numerical example to illustrate the validity of the proposed conclusions. [ABSTRACT FROM AUTHOR]

Ovarian hormones, especially estrogen, may facilitate drug use vulnerability in females. Oxytocin is of special relevance to females and an important neuroendocrine factor regulating drug use. Mandarin vole (Microtus mandarinus) is a monogamous rodent, with complex nonsexual social behavior. Here, we examined whether ovariectomy produces effects on cocaine-induced aggressive behaviors, estrogen receptor alpha (ERα) and oxytocin in virgin female mandarin voles. The data indicate that repeated cocaine exposure increased aggressive behavior and reduced levels of oxytocin expression in the paraventricular nucleus in ovariectomized and sham-operated females. In addition, cocaine reduced the levels of ERα expression in the medial nuclei of the amygdale in sham-operated females. In contrast, cocaine decreased ERα expression in the medial preoptic area and increased serum estradiol levels in ovariectomized females. These results suggest that ovariectomy influences the effects of cocaine on central levels of ERα and oxytocin expression and serum estrogen levels. The estrogen system acts in concert with oxytocin to regulate cocaine-induced aggressive behavior in virgin females. [ABSTRACT FROM AUTHOR]

The work is devoted to investigate the interaction between the special rotational deformation and interface collinear cracks in nanocrystalline bi-materials. As an illustrative example, the effect of the disclination quadrupole produced by the special rotational deformation on the emission of lattice dislocation from a finite interfacial crack tip in nanocrystalline bi-material is explored theoretically using the complex variable method. The complex form expression of dislocation force and the critical stress intensity factors for the first edge dislocation emission under remote mode I loadings and mode II loadings are deduced. And the influences of material properties, grain size, disclination strength, disclination location and orientation, special rotational deformation orientations, and crack length on the critical stress intensity factors are discussed in detail. The results show that the special rotational deformation and the relative shear modulus of the upper the lower half plane have great effect on the lattice dislocation emission from the interface collinear crack tip. [ABSTRACT FROM AUTHOR]

Internal friction (or damping) is a measure of energy dissipation during mechanical vibration. The internal friction peak induced by grain boundary (GB) relaxation was discovered by Kê in polycrystals in 1947. The GB internal friction and related anelastic effects have been successfully interpreted by Zener's anelastic theory and viscous sliding model. Since then, the GB internal friction peak has been widely used to study the dynamic process of GBs, impurity segregation at GBs and relevant processes in materials science. Previously, the GB internal friction was mostly studied with polycrystalline materials, in which mixed contributions of different types of GBs are involved. Since the microstructures and behaviors for different types of GBs are different, the detailed mechanism of the GB peak in polycryatals has not been clearly clarified. From the beginning of the 21th century, the internal friction in bicrystals (each has a single boundary) with different misorientations and rotation axes has been systematically investigated. The results indicate that the internal friction can be used to distinguish the individual behavior of different types of GBs and applied to the practice of “GB engineering.” Moreover, the coupling effect and compensation effect involved in GB relaxation has been recently observed and explained. The coupling effect means a correlated atomic motion occurred in GB relaxation. The compensation effect indicates that the apparent activation enthalpy is linearly related to the activation entropy in GB relaxation. These findings improve the understanding of the mechanism of GB internal friction. This article attempts to give a comprehensive review to the investigations of GB internal friction in polycrystals, bamboo-crystals, and bicrystals. The microscopic mechanisms and the further applications of GB internal friction are discussed and prospected. [ABSTRACT FROM AUTHOR]

Alkaligrass ( Puccinellia chinampoensis Ohwi), one of the important forage grasses in saline-alkalieroded grasslands, has been proved to be invaluable for improving saline-alkali soils. However, little is known of its genetic instabilities during in vitro culture for its artificial breeding. In this paper, a simple and efficient regeneration system of mature seed-induced calli in alkaligrass was established, and the somaclonal variation in the regenerated plants was assessed by inter-simple sequence repeat (ISSR) and retrotransposon-microsatellite amplified polymorphism (REMAP) markers. 18 randomly chosen regenerants were subjected to ISSR and REMAP analysis with the shoot from the same grain of seed as the control. ISSR analysis showed that of the 145 scored bands, 13 were polymorphic among the analyzed samples, giving rise to a genetic variation frequency of 8.97%. REMAP analysis revealed that 4 out of 127 scored bands were polymorphic, a genetic variation frequency of 3.15% occurred. Cluster analysis indicated that the genetic similarity index calculated on the basis of ISSR data or REMAP data among the 18 regenerated plants and the donor plant was 0.974 and 0.996 respectively. All the results confirmed that somaclonal variation was induced by tissue culture in alkaligrass at a higher frequency, and indicated that the regeneration system could be a viable option for genetic improvement of alkaligrass by biotechniques. [ABSTRACT FROM AUTHOR]

An important objective in biomedical and environmental risk assessment is estimation of minimum exposure levels that induce a pre-specified adverse response in a target population. The exposure points in such settings are typically referred to as benchmark doses (BMDs). Parametric Bayesian estimation for finding BMDs has grown in popularity, and a large variety of candidate dose-response models is available for applying these methods. Each model can possess potentially different parametric interpretation(s), however. We present reparameterized dose-response models that allow for explicit use of prior information on the target parameter of interest, the BMD. We also enhance our Bayesian estimation technique for BMD analysis by applying Bayesian model averaging to produce point estimates and (lower) credible bounds, overcoming associated questions of model adequacy when multimodel uncertainty is present. An example from carcinogenicity testing illustrates the calculations. [ABSTRACT FROM AUTHOR]

A series of hard projectile high-speed (500–700 m/s) impact tests on the steel fiber reinforced high strength concrete (SFRHSC) panel with rear steel liner and (or) backfilled sandy soil were conducted. The impact resistance of the above layered composite target as well as the parametric influences were assessed experimentally. It indicates that, within the discussed parameters variation ranges: (i) the rear sandy soil layer enhance the impact resistance of the SFRHSC/steel composite target; (ii) the steel liner also enhance the impact resistance of SFRHSC/sandy layer composite target; (iii) the strengthening effect of the rear sandy soil layer on the impact resistance of bare SFRHSC panel is more influential than the rear steel liner; (iv) Reinforcing steel bars of the concrete panel has no obvious effect on the impact resistance of SFRHSC/steel/sandy soil composite target; (v) Mixing steel fibers can efficiently reduce the damages of the concrete target. An approach for predicting the ballistic limits of SFRHSC/steel and SFRHSC/steel/sandy soil composite targets were proposed and compared with the present test data. [ABSTRACT FROM AUTHOR]

The ultra-high performance steel fiber reinforced concrete (UHP-SFRC) with the corundum coarse aggregate (UHP-CASFRC) was prepared under common curing temperature and pressure procedures. The static tests on UHP-CASFRC were conducted, including the uniaxial compression, direct tensile and four points bending tests. Totally 16 shots of reduce-scaled projectile penetration tests on UHP-CASFRC and 2 comparative shots on HSC targets were conducted. The influences of the strength (hardness), size and volumetric ratio of coarse aggregate, incident velocity of the projectile (510–850 m/s) as well as the repeated strikes on the depth of penetration (DOP), area and volume of the impact crater, as well as the structural integrity and mass loss of the projectile were discussed. By comparisons with the previous conducted basalt aggregated UHP-SFRC (UHP-BASFRC), the superior projectile impact resistance of UHP-CASFRC targets was verified. Within the discussed parametric variation ranges, it derived that: (i) Enlarging the size of the coarse aggregates can help reducing the DOP, impact crater area and volume, the harder coarse aggregate can decreasing the DOP by aggravating the mass abrasions of the projectile. The influences of coarse aggregate hardness on impact crater area and volume mainly depends on its surface roughness; (ii) When the sizes of the coarse aggregates were less than the projectile shank diameter ( d ), the harder coarse aggregates only aggravates the mass abrasions of the projectile, while the structural integrity of projectile could be maintained; (iii) For UHP-CASFRC target, the structural destruction of the projectile occurred when the coarse aggregates sizes increasing larger than d . From a structure protective point of view, the corundum sizes ≥1.5 d is suggested; (iv) The hardness of the coarse aggregate is the most influential factor on the mass abrasion of the projectile, and the previously proposed engineering models for mass abrasions of the ogive-nosed projectile high-speed penetrating into concrete target are further validated. [ABSTRACT FROM AUTHOR]

The interaction problem of a piezoelectric screw dislocation dipole with a confocal elliptic blunt crack in elliptical inhomogeneity subjected to remote anti-plane stress field and in-plane electric field is investigated by using the complex method of elasticity. The exact closed-form solutions of a series of quantities, such as singularity stress field, image force and image torque acting on the center of screw dislocation dipole, stress intensity factor and electric displacement intensity factor of crack tip, energy release rate, and generalized strain energy density are obtained. Then the influence laws of remote load, the dip angle of dislocation dipole, the size of blunt crack, and the material constants on the quantities are analyzed. The numerical results show that the image force, image torque, stress intensity factor, and electric displacement intensity factor make periodic variation as the dip angle of dislocation dipole; the energy release rate of crack tip is negative when subjected to pure electric field, however, it can be positive or negative when subjected to the combined action of mechanical field and electric field; the sharp crack is not easy to expand in some combined action of mechanical field and electric field. [ABSTRACT FROM AUTHOR]

Decitabine, which reverses hypermethylation of the p15INK4B gene in vitro, has been used to relieve cytopenias and blast excess in over 50% of patients with high-risk myelodysplastic syndrome (MDS). In this study, heme oxygenase-1 (HO-1) was overexpressed in MDS cell line SKM-1, which was closely related to resistance to decitabine-induced apoptosis. We aimed to further investigate the role of HO-1 in apoptosis induced by low-dose decitabine in SKM-1 cells. Upregulation of HO-1 by transfecting it into SKM-1 cells with lentivirus vector promoted cell proliferation and protected them against apoptosis. In contrast, downregulation of HO-1 enhanced decitabine-induced apoptosis but reduced accumulation of the S phase in cell cycle. To explore the mechanism, the expressions of cell cycle-related proteins were detected after the cells were treated by decitabine in each group. p15INK4B and CDK4 were overexpressed in SKM-1 cells in which HO-1 was inhibited, and the expression-depending apoptosis was related to the caspase-3 pathway. Even though HO-1 was silenced, the apoptotic rate never increased as the caspase-3 pathway was blocked. It is well known that p15INK4B dominantly regulates the S phase of the cell cycle. p15INK4B was herein demethylated more evidently in the group of SKM-1 cells in which HO-1 was downregulated, as well as in the mononuclear cells of patients suffering from MDS. In the case of poor prognosis, the mRNA level of HO-1 was raised. In conclusion, overexpression of HO-1 indicated resistance to demethylation of p15INK4B induced by decitabine. [ABSTRACT FROM AUTHOR]

Twenty-five shots of reduce-scaled projectiles perforation test on five configurations of monolithic and segmented RC panels with a rear steel liner were conducted. The impact resistances of layered bare RC and RC/steel composite targets were analyzed quantitatively based on the obtained striking and residual velocities of the projectiles, and the accuracy of the newly developed small-caliber accelerometer in recording the high-amplitude accelerations of the projectile is validated. The main conclusions are: (1) With the same overall thickness and projectile striking velocity, the stacked segmented targets have higher impact resistance than the spaced segmented targets. (2) For the spaced segmented targets with the same total thickness (i) the impact resistance of the monolithic RC plate is better than that of the segmented target, which is not dependent on the impact velocity as well as the rear steel liner is attached or not; (ii) the more the layers of the segmented target, the more inferiority of the segmented target has; (iii) while the number of the layers is fixed, e.g. double layers in the present test, the impact resistance of the segmented target is dependent on the order of the slabs, which is enhanced with the thickness of the later RC plate increasing. (3) An explicit dimensionless expression for predicting the terminal ballistic parameters of the projectile perforating the RC slab was proposed and well validated. (4) The newly proposed equivalent approach for predicting the ballistic limit of the projectile perforating RC/steel composite target was evaluated with the present tests. [ABSTRACT FROM AUTHOR]

The ultra-high performance cement based composites (UHPCC) with the additions of steel fibers and basalt coarse aggregates was prepared under ambient temperature and pressure. In order to apply the UHPCC in the constructions of anti-strike protective structures, the impact resistance of UHPCC was investigated experimentally by conducting the high-speed projectile penetration tests with the broad striking velocities from 510 m/s to 1320 m/s. The rigid and mass abrasive penetration regimes are observed when the projectile striking velocity was lower than 1 km/s and increased up to 1–1.5 km/s, respectively. The experiments validated that UHPCC material has excellent projectile impact resistance, such as reducing the depth of penetration (DOP) and the crater dimensions of the rigid projectile, as well as defeating the structure and deviating the terminal ballistic trajectory of the abrasive projectile. The previously proposed models for rigid penetration depth on fiber reinforced high strength concrete as well as the limit striking velocity causing the structural destruction of mass abrasive projectile are both well validated. The parameters influential analyses further indicate that UHPCC with the compressive strength of 90 MPa and steel fiber mixing ratio of 1.5% is the most efficient and economical choice for protective structure constructions. In details, within the discussed ranges: (i) the projectile impact crater dimensions enlarges with the increase of the compressive strength of the target and the projectile striking kinetic energy, and which was reduced with the increase of fiber mixing fraction and the mixed coarse aggregate. The influential degree of mixing fibers on reducing the cratering dimensions is much greater than which of compressive strength on enlarging the cratering dimensions; (ii) both of the compressive strength, the fiber mixing fraction as well as coarse aggregates can help decreasing the DOP of the projectile so as to enhance the impact resistance of the target, while the contribution of fibers is very limited for the relatively low addition ratio (⩽3%). The DOP of the projectiles are no longer decreasing obviously when the compressive strength of the target is larger than nearly 90 MPa. [ABSTRACT FROM AUTHOR]

Stocking rate (SR) is the primary management factor that influences livestock gains, plant community changes and forage production, as well as economic returns for livestock producers. More effective stocking decision making by ranchers in the semi-arid northern mixed-grass prairie requires clearly understanding forage production and yearling steer weight gain (SWG) responses to SR and high weather variability. The objectives of this study were to: (1) test the Great Plains Framework for Agricultural Resource Management-Range (GPFARM-Range) model for predicting forage production and SWG under three experimental SR treatments and long-term weather conditions on semiarid northern mixed-grass prairie in southeast Wyoming, USA; and (2) quantify the threshold responses of forage production and SWG to SR and the yearly weather variability across years using long-term simulations with SR higher than those experimentally evaluated. We improved upon the GPFARM-Range model to simulate peak standing crop (PSC) and SWG for three experimental SR treatments (low, moderate and high; 0.20, 0.33 and 0.44steerha−1, respectively) from 1982 to 2012 at Cheyenne, Wyoming, USA. The improved model accurately predicted the effects of SR on PSC and SWG across years (root mean square errors from 355 to 387kgha−1 for PSC and from 12.8 to 14.2kghead−1 for SWG). We ran the model with long-term weather data and 50-300% higher SR (0.66-1.76steerha−1) than the high SR experimental treatment. Differential responses of predicted total intake of digestible nutrients (quadratic increase) and metabolic maintenance (linear increase) to these higher SR resulted in a quadratic increase of predicted SWG with SR and high yearly variability at high SR levels. The financially-optimum SR with highest profits was reduced to 0.33steerha−1 for dry or normal seasons and 0.44steerha−1 for wet seasons. Such reduced SR can also benefit land conservation with high PSC and low harvest efficiency. The moderate SR with 25% harvest efficiency was determined between 0.22 and 0.33steerha−1 for dry or normal seasons, or between 0.33 and 0.44steerha−1 for wet seasons. These results provide useful direction for selecting an effective SR to achieve high economic net return with lower yearly variability (risk) and reduced likelihood of rangeland degradation. [ABSTRACT FROM AUTHOR]

The electro-elastic interaction between a piezoelectric screw dislocation and a semi-infinite wedge crack partially penetrating a circular nanoscale piezoelectric inhomogeneity is investigated. Using Riemann-Schwartz's symmetry principle integrated with the analysis of singularity of complex functions and the conformal mapping technique, the expressions of electro-elastic fields in matrix and inhomogeneity regions are derived explicitly. The image force, the stress intensity and electric displacement intensity factor of crack tip, as well as the critical applied stress and the critical electric displacement intensity factor for dislocation emission are discussed in detail. The results show that the positive piezoelectric screw dislocation can reduce the stress intensity factor of the wedge crack tip and shield the crack growth. If the coupling of electric displacement and positive stress at the interface is considered, the shielding effect will increase and the situation of image force will change. The most probable angle for dislocation emission is zero, and the greater the shear modulus and piezoelectric constant of the matrix, the greater the wedge crack opening angle, the more difficult for dislocation emission. In addition, the positive (negative) interface stress blocks (boosts) dislocation emission, and the existence of electric displacement at the interface makes dislocation emission more difficult. [ABSTRACT FROM AUTHOR]

The interaction between a screw dislocation and a circular nano-inhomogeneity with a semi-infinite wedge crack penetrating the interface is investigated. By using Riemann-Schwartz's symmetry principle integrated with the analysis of singularity of complex functions and the conformal mapping technique, the analytical expressions of the stress field in both the circular nano-inhomogeneity and the infinite matrix, the image force acting on the screw dislocation and the stress intensity factor at the crack tip are obtained. The influence of elastic mismatch of materials, inhomogeneity size, interface stress, wedge crack opening angle and the relative location of dislocation on the image force and on the equilibrium position of the screw dislocation and the shielding effect of the screw dislocation are discussed in detail. The results show that interface stress has a significant impact on the movement of dislocations near the interface, and the effect of interface stress enhances when the inhomogeneity radius decreases. With the decrease in the wedge crack opening angle, the influence of interface stress on the movement of the screw dislocation and on the SIF enhances. With the increment of the relative shear modulus, the influence of interface stress weakens with the screw dislocation locating in the inhomogeneity and strengthens with the screw dislocation locating in the matrix. When the screw dislocation is located in the inhomogeneity, the positive (negative) interface stress increases (decreases) the shielding effect, while this phenomenon is opposite when the screw dislocation locates in the matrix. [ABSTRACT FROM AUTHOR]

Objectives: To explore the factors associated with the operative duration for paediatric tracheobronchial foreign body removal by rigid bronchoscopy, and to analyse the learning curve for mastery of the rigid bronchoscopy skill. Methods: A retrospective study was performed of paediatric cases of tracheobronchial foreign body removal by rigid bronchoscopy in our department from January 2007 to July 2019. Multivariate Cox regression analysis was used to analyse the factors associated with the operative duration. In addition, the learning curves for two doctors were evaluated by curve-fitting regression analysis. Results: A total of 410 paediatric cases of tracheobronchial foreign body removal by rigid bronchoscopy were evaluated. The operative duration was significantly influenced by the skill of the doctor. The learning curves for both doctor A and doctor B demonstrated two typical phases: an initially rapidly changing learning phase followed by a steady consolidation phase. Conclusion: The operative duration for paediatric tracheobronchial foreign body removal by rigid bronchoscopy was associated with the skill of the doctor. In order to fully master the rigid bronchoscopy technique, doctors should perform a minimum number of procedures to pass the learning phase and reach the consolidation phase. [ABSTRACT FROM AUTHOR]

As dislocation emission is regarded as the critical point of brittle-to-ductile transition of fracture mechanism and the defects interact with domain walls motions due to their self-stress fields, the investigations on dislocation forces, especially the interaction force and the reaction between domain switching and dislocations, are the most important fundamentals of dislocation slip in the brittle-to-ductile transition and the pinning effect on domain wall motion mechanisms. In this paper, an innovative method base on the strain nucleus simulated by an assembly of four dislocations and the Green's function integration is used to solve generalized stress field arising from domain switching. Then, the accurate expressions of the interaction forces, pinning forces and the image forces on dislocation are obtained and analyzed. At last, the lattice resistance is also discussed. The numerical results show that the dislocation emission is possible when temperature and load are proper, and the domain switching interaction force is the main driving force of dislocation slip in ferroelectric material under negative electric field load. The curve and equation of the lattice resistance correlated with temperature can also be fitted by the results of the proposed analytical method and corresponding experiments. [ABSTRACT FROM AUTHOR]

Objective: To identify significant distinctive characteristics of urothelial carcinoma (UC) in kidney transplant recipients between China and Western countries and investigate probable tumor screening and treatment factors contributing to these differences. Methods: Renal transplant recipients from 1998 to 2011 in our institution diagnosed with UC were included in this study. Our data on tumor incidence, clinical characteristics, and outcomes were compared with literature reports. Results: Among 2572 renal transplant recipients identified, 24 (0.93%) experienced UC, including 10 men and 14 women of overall mean age of 49.3 ± 11.6 years at transplantation and 53.5 ± 9.5 years at tumor detection. The Chinese traditional herbal intake mainly focused on 2 preparations: Aristolochic acid and rhubarb (the latter was mainly used in patients with chronic renal impairment) in 20 people. There were 21 (87.5%) cases of upper (UTUC) 5 cases of bilateral, and 13 cases of multifocal urinary tract urothelial carcinoma. Four subjects died owing to tumor progression at 4–63 months postoperatively. Conclusions: UC in renal transplant recipients shared notable characteristics in China with widespread herb intake: UTUC predominance; multifocal and bilateral organ involvement; high rates of recurrence, progression, and dissemination, in contrast with bladder tumor dominance in Western countries. As a consequence, we suggest that bilateral nephroureterectomy should be performed prophylactically in high-risk patients, especially those with a long history of Chinese herb intake. The relationship of rhubarb consumption to UC in renal transplant recipients should be noted and evaluated. [ABSTRACT FROM AUTHOR]

The interaction between piezoelectric screw dislocations and two asymmetrical interfacial cracks emanating from an elliptic hole under combined mechanical and electric load at infinity is dealt with. The closed-form solutions are derived for complex potentials and generalized stress fields. In the limiting cases, some well-known results can be obtained from the present solutions. Moreover, some new exact solutions are shown. The stress intensity factor and the energy release rate at the right tip due to a screw dislocation near the right interfacial crack are also calculated. The results show that the shielding effect of dislocation on crack expanding decreases with the increase in dislocation azimuth angle and the distance between the dislocation and the crack tip, and the repulsion acting on the dislocation from the other half plane demotes crack propagation. The increasing of the length of the other crack promotes crack growth, but the increasing of the minor semi-axis demotes it. [ABSTRACT FROM AUTHOR]

Aims Hepatocyte nuclear factor-1α (HNF-1α) regulates the expression of genes encoding proteins involved in glucose metabolism and insulin secretion. Mutations in the HNF-1α gene cause maturity-onset diabetes of the young Type 3. However, the mechanism leading to this disease has not been completely ascertained. Previously, we found a novel mutation in the regulatory element of the human HNF-1α gene in two Chinese diabetes pedigrees. The nucleotide at position -128 T was substituted by G (nt-128 T→G). In this study, we analysed the functional defect of nt-128 T→G in HNF-1α transcription activity. Methods Luciferase reporter gene assays were carried out to examine the functional characteristics of this mutant. Electrophoretic mobility shift assays and chromatin immunoprecipitation were performed to confirm the binding of nuclear proteins to oligonucleotides. Results The variant construct (nt-128 T→G) had a 1.65-fold increase in promoter activity compared with that of the wild-type construct in HepG2 cells and a 1.33-fold increase in MIN6 cells, respectively. The variant resided at a FOXA/HNF-3 binding site identified by a series of competitive electrophoretic mobility shift assays and antibody supershift analyses. The assays showed a differential binding affinity in the wild-type and the nt-128 T→G mutant fragments by FOXA/HNF-3. Chromatin immunoprecipitation indicated that FOXA/HNF-3 bound to this region in vivo. One nucleotide substitution in the FOXA/HNF-3 site in the human HNF-1α regulatory element caused an increase of HNF-1α transcriptional activity. Conclusions Our data suggested that this substitution in the promoter region affects DNA-protein interaction and HNF-1α gene transcription. The mutant may contribute to the development of diabetes in these two nt-128 T→G pedigrees of Chinese. [ABSTRACT FROM AUTHOR]

The magnetic properties of Mg-doped ZnO thin films grown under different oxygen pressures P and annealing temperatures T on Si (001) substrates by pulsed-laser deposited (PLD) were investigated. The hysteresis curve at room temperature (RT), measured with a high-resolution magnetometer (∼10 emu), revealed the presence of a ferromagnetic state for all Mg-doped ZnO thin films that were investigated. Interestingly, a significant magnetic signal was observed for an amorphous ZnMgO thin film; RT ferromagnetism in amorphous ZnMgO films has rarely been reported. Photoluminescence (PL) spectroscopy measurements, as well as microstructure analysis, suggest that RT ferromagnetism in ZnMgO thin film, when exposed to an oxygen atmosphere or annealed in air, is related to oxygen interstitials, O, and zinc vacancies, V. Strong polarization from electrons trapped on these defects and vacancies induces the magnetic properties. We reveal a possible approach for explaining the origin of magnetism by a defect-induced mechanism rather than the conventional carrier-induced mechanism. In our proposed mechanism, a defect-rich polarizing effect may play a crucial role in the magnetic behavior of ZnO-based semiconductors. [ABSTRACT FROM AUTHOR]

The image force and stability of a screw dislocation inside a coated cylindrical inhomogeneity with interface stresses are analyzed. A three-phase composite cylinder model is utilized to study the issues. The stress boundary condition at the interface of the coating layer is modified by incorporating surface/interface stress. The analytical solution of complex functions of the inhomogeneity, the coating layer, and the infinite matrix is derived by means of the complex variable method. With the aid of the obtained stress fields and the Peach-Koehler formula, the explicit expression of the image force acting on the screw dislocation is obtained. The critical radius of the inhomogeneity where the screw dislocation stays is evaluated. The influence of the interface stresses on the image force and the critical radius of the inhomogeneity is derived. The results indicate that the negative interface stresses attract the dislocation, and the positive interface stresses repel the dislocation. The critical radius of inhomogeneity will increase for considering the negative interface stresses and will decrease for considering the positive interface stresses. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we formulate a numerical method that is high order with strong accuracy for numerical wave numbers, and is adaptive to non-uniform grids. Such a method is developed based on the discontinuous Galerkin method (DGM) applied to the hyperbolic equation, resulting in finite difference type schemes applicable to non-uniform grids. The schemes will be referred to as DGM-FD schemes. These schemes inherit naturally some features of the DGM, such as high-order approximations, applicability to non-uniform grids and super-accuracy for wave propagations. Stability of the schemes with boundary closures is investigated and validated. Proposed scheme is demonstrated by numerical examples including the linearized acoustic waves and solutions of non-linear Burger’s equation and the flat-plate boundary layer problem. For non-linear equations, proposed flux finite difference formula requires no explicit upwind and downwind split of the flux. This is in contrast to existing upwind finite difference schemes in the literature. [Copyright &y& Elsevier]

Abstract: Water is the most important limiting factor of wheat (Triticum aestivum L.) and maize (Zea mays L.) double cropping systems in the North China Plain (NCP). A two-year experiment with four irrigation levels based on crop growth stages was used to calibrate and validate RZWQM2, a hybrid model that combines the Root Zone Water Quality Model (RZWQM) and DSSAT4.0. The calibrated model was then used to investigate various irrigation strategies for high yield and water use efficiency (WUE) using weather data from 1961 to 1999. The model simulated soil moisture, crop yield, above-ground biomass and WUE in responses to irrigation schedules well, with root mean square errors (RMSEs) of 0.029cm3 cm−3, 0.59Mgha−1, 2.05Mgha−1, and 0.19kgm−3, respectively, for wheat; and 0.027cm3 cm−3, 0.71Mgha−1, 1.51Mgha−1 and 0.35kgm−3, respectively, for maize. WUE increased with the amount of irrigation applied during the dry growing season of 2001–2002, but was less sensitive to irrigation during the wet season of 2002–2003. Long-term simulation using weather data from 1961 to 1999 showed that initial soil water at planting was adequate (at 82% of crop available water) for wheat establishment due to the high rainfall during the previous maize season. Preseason irrigation for wheat commonly practiced by local farmers should be postponed to the most sensitive growth stage (stem extension) for higher yield and WUE in the area. Preseason irrigation for maize is needed in 40% of the years. With limited irrigation available (100, 150, 200, or 250mm per year), 80% of the water allocated to the critical wheat growth stages and 20% applied at maize planting achieved the highest WUE and the least water drainage overall for the two crops. [Copyright &y& Elsevier]

The interaction between a screw dislocation and an interfacial cruciform crack and collinear linear cracks under loads at infinity was investigated. General solutions of complex potentials to this problem were derived by using complex potential theory. As illustrative examples, the closed form solution for a screw dislocation interacting with an interfacial cruciform crack and a linear crack is obtained. The stress intensity factor and critical stress intensity factor for dislocation emission are also calculated. The results show that the shielding effect increases with the increase of the shear modulus and the distance between the two cracks, but it decreases with the increase of dislocation azimuth and the distance between the dislocation and the cruciform crack tip. The critical loads at infinity for dislocation emission increase with the increment of the emission angle, the distance the two cracks and the vertical length of the cruciform crack. [ABSTRACT FROM AUTHOR]

According to the Mott and Nabarro’s model, the contribution to the critical shear stress of the material caused by the interaction between edge dislocations and nanoscale cylindrical inhomogeneities with interface stresses is obtained. The influence of the radius and the volume fraction of the inhomogeneity as well as the interface stresses on the critical shear stress is investigated. The important result is that, if the interface stress is considered, a maximum of the contribution to the critical shear stress produced by this interaction may be obtained when the radius of the inhomogeneity reaches a critical value. [ABSTRACT FROM AUTHOR]

In [8-118, 9, 10, 11] a superconvergence analysis is derived for the smooth and singular Poisson equations by the finite difference method (FDM) using the Shortley-Weller approximation. In this article, we explore the superconvergence analysis for a parabolic equation using the Shortley-Weller approximation and the Crank-Nicolson scheme (CNS) in space and time discretization, respectively, denoted simply as FDM-CNS. The results of derivative superconvergence in [8-118, 9, 10, 11] can be extended to parabolic problems of smooth and singular solutions. The main results are as follows: when [image omitted] and [image omitted], the superconvergence rate O(h2 + k2) is derived for the solution derivatives in discrete H1 norms by the FDM-CNS on rectangular domains, where k is the time mesh spacing in the Crank-Nicolson scheme and h is the maximal mesh length of difference grids used. Note that the difference grids are not confined to be quasi-uniform, and local refinements are allowed for the solutions with unbounded derivatives. Numerical experiments are provided to support the superconvergence O(h2 + k2). [ABSTRACT FROM AUTHOR]

A theoretical model is proposed for elastic stress relaxation of a buried strained cylindrical inhomogeneity, which assumes the edge misfit dislocation dipole formation in the soft matrix at some distance from the interface. The critical radius of the inhomogeneity for the formation of the edge misfit dislocation dipole is given and the influence of various parameters on the critical radius is evaluated. The result indicates that the critical radius decreases with increasing misfit strain and core radius of the misfit dislocation. It is also found that, compared to the edge misfit dislocation dipole formation in the interface, the critical radius of the inhomogeneity decreases when the location of an edge misfit dislocation dipole formation is in the soft matrix at some distance from the interface. [ABSTRACT FROM AUTHOR]

A three-phase composite cylinder model is utilized to study the elastic interaction between screw dislocations and embedded multiple circular cross-section inclusions (fibers) with imperfect interfaces in composites. By means of complex variable techniques, the explicit solutions of stress and displacement fields are obtained. With the aid of the Peach–Koehler formula, the explicit expressions of image forces exerted on screw dislocations are derived. The equilibrium positions of the appointed screw dislocation near one of the inclusions are discussed for variable parameters (interface imperfection, material mismatch and dislocation position) and the influence of the nearby inclusions and dislocations is also considered. The results show that, if the inclusion is stiffer than the matrix and the magnitude of the degree of interface imperfection reaches the certain value, a new equilibrium position for the screw dislocation in the matrix can always be produced in comparison with the previous solution (the perfect interface). The effect of elastic constants of the inclusion on the image force and the equilibrium position of the appointed screw dislocation is weak when the interface imperfection is strong. It is also seen that the magnitude of the image force exerted on the appointed dislocation caused by multiple inclusions is always smaller than that produced by a single inclusion. The impact of the closer dislocations on the mobility of the appointed dislocation is very significant. [ABSTRACT FROM AUTHOR]