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• Ultra-slow coarsening rates of the nanoparticles from 2.47 × 10–29 to 5.74 × 10–29 m3 s–1 were found in the chemically complex high-entropy alloys (HEAs) at 800 °C. • Excellent thermally stable structures with pristine "L1 2 + FCC" were obtained even upon long-term aging at 800°C • The stacking fault-mediated deformation enabled a superior high work-hardening rate and an anomalous improvement in yield strength at elevated temperatures. The precipitate morphologies, coarsening kinetics, elemental partitioning behaviors, grain structures, and tensile properties were explored in detail for L1 2 -strengthened Ni 39.9 Co 20 Fe 15 Cr 15 Al 6 Ti 4– x Nb x B 0.1 (x = 0 at.%, 2 at.%, and 4 at.%) high-entropy alloys (HEAs). By substituting Ti with Nb, the spheroidal-to-cuboidal precipitate morphological transition, increase in the coarsening kinetics, and phase decomposition upon aging at 800 °C occurred. The excessive addition of Nb brings about the grain boundary precipitation of an Nb-rich phase along with the phase decomposition from the L1 2 to lamellar-structured D0 19 phase upon the long-term aging duration. By partially substituting Ti with Nb, the chemically complex and thermally stable L1 2 phase with a composition of (Ni 58.8 Co 9.8 Fe 2.7)(Al 12.7 Ti 5.8 Nb 7.5 Cr 2.3) ensures the stable phase structure and clean grain boundaries, which guarantees the superb high-temperature mechanical properties (791 ± 7 MPa for yielding and 1013 ± 11 MPa for failure) at 700 °C. Stacking faults (SFs) were observed to prevail during the plastic deformation, offering a high work-hardening capability at 700 °C. An anomalous rise in the yield strength at 800 °C was found, which could be ascribed to the multi-layered super-partial dislocations with a cross-slip configuration within the L1 2 particles. [Display omitted] [ABSTRACT FROM AUTHOR]

• Helium bubbles and large stacking faulted loops are observed as the dominant structural damage in the He ion irradiated HEA reinforced by L1 2 nanoparticles. • The L1 2 nanoparticles provide numerous interfaces for He entrapment and damage elimination, which suppresses He bubble growth. • A correlative TEM/APT characterization reveals that the RIS around He bubbles is dominated by the inverse Kirkendall mechanism. • Irradiation-induced dissolution and re-precipitation of the L1 2 nanoparticles can retain the main microstructure of the L1 2 -strengthened HEA and provide a sustainable irradiation resistance. L1 2 -strengthened high entropy alloys (HEAs) with excellent room and high-temperature mechanical properties have been proposed as promising candidates as structural materials for advanced nuclear systems. However, knowledge about their radiation response is fairly limited. In the present work, a novel HEA with a high density of L1 2 nanoparticles was irradiated with He ion at 500 °C. Transmission electron microscope (TEM) and atom probe tomography (APT) were employed to study the evolution of microstructural stability and radiation-induced segregation. Similar to the single-phase FeCoNiCr HEA, the main microstructural features were numerous large faulted dislocation loops and helium bubbles. While the irradiation resistance of the present L1 2 -strengthened HEA is much improved in terms of reduced bubble size, which could be attributed to the considerable He trapping efficiency of the coherent precipitate/matrix interface and the enhanced capability of the interface for damage elimination when the matrix channel width is narrow. APT analysis revealed that an inverse-Kirkendall-mechanism-dominated radiation-induced segregation (RIS) occurs around bubbles, where a significant Co enrichment and Ni depletion can be clearly observed. In addition, the competing dynamics of ballistic mixing and elemental clustering that raised from the irradiation-enhanced diffusion in a highly supersaturated matrix, along with the low precipitation nucleation barrier due to the small lattice misfit, lead to a dynamical precipitation dissolution and re-precipitation appears under irradiation. Such a promising phenomenon is expected to promote a potential self-healing effect and could in turn provide a sustainable irradiation tolerance over the operational lifetime of a reactor. [ABSTRACT FROM AUTHOR]

Severe intermediate-temperature embrittlement as well as rapid softening and oxidation at high temperatures are significant problems for high-entropy alloys (HEAs) in polycrystalline structures, which greatly limit their applications in modern industries. In this study, a novel Co-rich single-crystal high-entropy alloy (HEA), Co41Ni35Al11·5Ta2·5Cr4Ti6(at.%), was innovatively developed. After isothermally aged at 1250 °C, this alloy exhibits an ultrahigh volume fraction of cuboidal L12-type nanoprecipitates (∼80%) which is higher than those of previous Co-based superalloys. More importantly, the present HEA shows excellent mechanical performance at both ambient and elevated temperatures, and no intermediate temperature embrittlement and rapid softening were observed. Noticeably, the yield strength can still maintain at ∼800 and ∼500 MPa when tested at 900 and 1000 °C, which are superior to other conventional single-crystal alloys. Moreover, extraordinary oxidation resistance can be achieved at the high temperature of 1000 °C due to the formation of a compact sandwich-structured oxide layer.

Many boundary-layer flows are governed by one or coupled nonlinear ordinary differential equations (ODEs). Currently, a Mathematica package BVPh 2.0 is issued for nonlinear boundary-value/eigenvalue problems with boundary conditions at multiple points. The BVPh 2.0 is based on an analytic approximation method for highly nonlinear problems, namely the homotopy analysis method (HAM), and is free available online. In this paper, the BVPh 2.0 is successfully applied to solve magnetohydrodynamic (MHD) Falkner–Skan flow of nano-fluid past a fixed wedge in a semi-infinite domain, and the influence of physical parameters on the considered flows is investigated in details. Physically, this work deepens and enriches our understandings about the magnetohydrodynamic Falkner–Skan flows of nano-fluid past a wedge. Mathematically, it illustrates the potential and validity of the BVPh 2.0 for complicated boundary-layer flows. [ABSTRACT FROM AUTHOR]

The present investigation was aimed at optimization of BMPs loaded PLGA microspheres formulations resulting in improved encapsulation efficiency and sustained release of BMPs by varying the molecular weight and copolymer composition of PLGA. Double-emulsion solvent evaporation method was used to prepare the microspheres. The effect of polymer molecular weight and copolymer composition on particle properties and release behavior in vitro was reported. The particle size and encapsulation efficiency increased with increase in molecular weight and lactide content of PLGA. While BMPs release in vitro decreased with increase in molecular weight and lactide content of PLGA. SEM pictures revealed that almost all microspheres were spherical but internal morphology was different. The morphology of PLGA microspheres with exorbitant molecular weight(100kD) was anomalistic whereas the morphology of PLGA microspheres with higher glycolide content(50) have porous structures.

It has been necessary to adopting automatic detection of steel ball based on machine vision in industrial processing. The detecting instrument for surface quality of steel ball based on machine vision and embedded control technique and is applied to detecting external bug region of steel ball in bearing. Its image detection and control system require excellent real-time character and high control accuracy. This paper put forward a new design for image processing and control system of detecting instrument. Firstly, we adopted OTSU segmentation arithmetic based on image enhancement and median filtering. As a result, steel ball was detected by area character parameter. Secondly, we adopted TMS320LF2407A as main processor and integrated CPLD to develop an embedded controller. It presents a novel optimal design method for PID controller based on the ant colony optimization (ACO) algorithm to optimize traditional PID control algorithm. At last, a performance study of experimental system is conducted and it shows that the proposed method can be used in online steel ball detection applications.

Based on BAYES data processing theory, a new method of fuzzy probability is proposed for the parameter reliability of small sample. Prior distribution of fuzzy parameter is obtained by stochastic weighted method, then posterior distribution of fuzzy parameter is got by the method of conjugate distribution. In the end, the formula of fuzzy membership function is constructed, and probability of fuzzy events is solved.The study of this paper aims at the membership function which is deduced in the condition that mean is known and deviation is unknown in normal population distribution. At the same time using information of small sample of actual experiment, the study fully utilizes prior information, so, it is convincing to evaluate reliability of fuzzy parameter. It is obviously economical.

Characteristics of nuclear deformation properties at scission of two fission modes, symmetric and asymmetric, are reviewed. Existence of two kinds of scission configurations associated with the symmetric and asymmetric fission modes is pointed out: elongated and compact configurations. Each symmetric and asymmetric scission property is discussed in terms of shape elongation evaluated from fragment total kinetic energy (TKE). Fragment deformation at scission is also discussed based on neutron multiplicity data. From the systematic study of the scission properties in a wide range of actinide fission, the bimodal fission observed in spontaneous fission (SF) of the heavy actinides is interpreted as the result of the presence of the two fission paths of the ordinary asymmetric mode and a strongly shell-influenced symmetric one. The correlation between the fragment shell structures and the asymmetric mass-yield curves is described.

Carcinogenesis is a multi-stage process with sequence of genetic events governing the phenotypic expression of a series of transformation steps leading to the development of metastatic cancer. In the present study, immortalized human bronchial (BEP2D) and breast (MCF-10F) cells were irradiated with graded doses of either 150 keV/μm alpha particles or 1 GeV/nucleon 56Fe ions. Transformed cells developed through a series of successive steps before becoming tumorigenic in nude mice. Cell fusion studies indicated that radiation-induced tumorigenic phenotype in BEP2D cells could be completely suppressed by fusion with non-tumorigenic BEP2D cells. The differential expressions of known genes between tumorigenic bronchial and breast cells induced by alpha particles and their respective control cultures were compared using cDNA expression array. Among the 11 genes identified to be differentially expressed in BEP2D cells, three (DCC, DNA-PK and p21CIPI) were shown to be consistently down-regulated by 2 to 4 fold in all the 5 tumor cell lines examined. In contrast, their expressions in the fusion cell lines were comparable to control BEP2D cells. Similarly, expression levels of a series of genes were found to be altered in a step-wise manner among tumorigenic MCF-10F cells. The results are highly suggestive that functional alterations of these genes may be causally related to the carcinogenic process.

In previous work we reported on materials design and property estimation using empirical or ordinal representation approaches (Pao et al., 1999, Pao et al., 2000). In this paper, we report in detail on a Basic Concepts approach, which combines some of the merits of both the ab initioquantum theoretic first principles approach and the commonly used empirical approach. We show that it is possible to establish mappings between sets of basic atomic characteristics and properties of materials systems formed from those constituent atomic species. Such mappings are implemented in neural networks and are trained using large bodies of high-quality well-filtered data. We also report on the adaptive extrapolation and exploration of such neural network mappings. Such exploration can be used to suggest likely compositions of new compounds that would have certain required properties. This is accomplished by a combined technique of neural networks and evolutionary search. The feasibility and the effectiveness of this method are illustrated with examples.

Various failure modes observed in fiber reinforced intermetallic matrix composites are analyzed by using a micromechanical analytical model based on the con sistent shear lag theory. Stress distribution is examined for a number of damage configura tions such as interface split, fiber bridging and secondary cracking. Based on the point stress failure criterion, prediction of failure mode is made for a fiber reinforced unidirec tional composite with central transverse crack and subjected to a remote uniform stress.

• The resonant global analytical mode shapes are obtained by considering both the axial and transverse displacements. • The analytical mode shapes are validated based on figure comparisons and MACs. • The steady-state responses of the system are solved as functions of the frequency and amplitude of the excitation. • Periodic, multiperiodic, quasiperiodic and chaotic motions are analyzed numerically. • The accuracy of the mode shapes plays an important role in determining the parametric rule of certain nonlinear phenomena. The nonlinear partial differential governing equations of the planar motion of a Z-shaped structure are derived using Hamilton's principle. The 1:2 internally resonant global analytical mode shapes are validated by figure contrast and the modal assurance criterion (MAC). The partial differential governing equations are truncated into a two-degree-of-freedom ordinary differential system with the validated resonant global analytical mode shapes, and they are further investigated for internal and simultaneous primary resonances. The steady-state responses are studied, and numerical simulations of the system are performed. Complex nonlinear phenomena in the system, such as jumps, bifurcations, quasiperiodic motion and chaos, are observed under specific parameters. The parametric rule of these phenomena obviously depends on the accuracy of mode shapes. This work proposes a nonlinear analysis based on the quantitative validation of mode shapes, which may provide new insights into the optimal design of the parameters and the precise control of the motions of Z-shaped or other multibeam structures in engineering. [ABSTRACT FROM AUTHOR]