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A novel 4A zeolite was successfully synthesized through a green and facile hydrothermal method by using coal fly ash from the flue gas of a thermal power plant as the raw material. The synthesis process was investigated and optimized by single-factor and orthogonal experiments and response surface optimization. Results showed that the Ca2+ exchange capacity of the product reaches 310.2 mg/g under the liquid–solid ratio of 8:1, NaOH solution concentration of 2.41 mol/L, and reaction temperature and time of 95°C and 6 h. This capacity corresponds with the predicted value of the response surface. Characterization tests revealed that the product has good crystallinity and spherical cage morphology, and the specific surface area reaches 5.76 m2/g. All these findings indicated that the hydrothermal treatment of coal fly ash in alkaline solution to prepared zeolite is a feasible route that is environmentally friendly and efficient.

The impact of electrostatic doping level on the dissipative transport of Armchair GNR-TFET is studied using the Quantum Perturbation Theory (QPT) with the Extended Lowest Order Expansion (XLOE) implementation method. Results show that the doping level of the source and drain sides of the GNR-TFET has a significant impact on the phonon contribution to the carrier transport process. Unlike in other similar studies, where phonons are believed to have a constant detrimental influence on the ION/IOFF ratio and Subthreshold Swing (SS) of the TFET devices due to the phonon absorption-assisted tunneling, we show that by a proper engineering of the doping level in the source and drain, the phonon absorption assisted tunneling can be effectively inhibited. We also show that as temperature increase, the device switching property deteriorates in both the ballistic and dissipative transport regimes, and there exists a temperature-dependent critical doping level where the device has optimal switching behavior.

Electrostatic doping (ED)-based graphene nanoribbon (GNR) tunneling field-effect transistor (TFET) with trigate design is studied. The transfer and output characteristics of the GNR-TFET are explored using extended Huckel semiempirical method. An ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio as high as 1014 is obtained with the ON-state current on the order of $10^{\textsf {3}}~\mu \text{A}/\mu \text{m}$ . A sub-60 mv/decade subthreshold swing is also observed (35 mv/decade). Armchair GNR with widths of 11 and 9 dimmers is found to be the best geometry to obtain a high ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio, and channel length of greater than 6.9 nm suppresses short-channel effect. The scaling behavior of the ED-based GNR-TFET is also studied. It is observed that a smaller gate-to-gate distance facilitate large ON-state current and small OFF-state current. Moreover, it is shown that for a high-quality switching performance, the lowest required built-in gate voltage must provide enough energy differential ${\Delta } \text{E}$ between the source- and drain-side energy bands.

In order to explain the modified streamer pattern in nano-modified transformer oil, the polarization effects of suspended particles on the electrodynamics of streamer branching were studied. A multi-physical coupling numerical model of streamer propagation in transformer oil was presented based on the Poisson theory, continuity equations of charge carriers and field-depended molecule ionization. Considering the particle polarization under strong electric field, suspended particles with varying permittivities were studied. The results showed that the polarization of particle distorts electric field and enhances the local electric field strength surrounding the particle. As soon as the local electric field is intensive to produce sufficient ionization, a new streamer would be induced at the pole of the particle to form a side-branch. Besides, the patterns and characteristics of streamer branches highly depend on the permittivity of particle.

In this study electric current-induced wind forces on a unit lattice of a 10-dimer zigzag graphene nanoribbon (ZGNR) are calculated under different magnitudes of electric field and temperatures. Wind forces are calculated using a semi-classical method where quantum mechanics is integrated into ensemble Monte Carlo simulations by considering energy and momentum conservation in both the transverse and longitudinal directions of graphene nanoribbon (GNR) during the electron-phonon scattering process. First order perturbation theory using the deformation potential approximation was used in the calculation of the scattering rates. The results show that under the same electric field, Joule heating power in a 10-dimer ZGNR is around 3 magnitudes higher than that in metallic single-walled carbon nanotubes and the wind forces are 1 magnitude higher. According to the calculated results, the wind force in the 10-dimer ZNGR is in the order of 0.0073 eV A-1 under 20 kV at 300 K and it is much lower than the fracture strength of ZGNR based on the results of molecular dynamics simulations. Thus the failure of GNR under an electric current is considered to be mainly due to the Joule heating.

To determine the hydrochemical characteristics and the factors affecting the water bodies in the Huainan Coalfield, 101 samples of surface water (river water and water in subsidence) and groundwater in the study area were collected in August and December 2016 and analyzed for their mass concentrations, compositions, and types of major ions. The formation and factors affecting the hydrochemical characteristics of the water bodies were analyzed with the ratio of elements, Gibbs diagram and factor analysis. The results suggest that the mass concentrations of the total dissolved solid (TDS) in the water bodies follow the order of water in subsidence > river water > groundwater. The hydrochemical type of the surface water was determined to be a HCO3·Cl-Na type, and the groundwater was determined to be a HCO3−Na·Ca type. The hydrochemical characteristics of the surface water were mainly formed by evaporation. The weathering of the water body was dominated by evaporites, followed by silicate weathering. The ions in the groundwater were mainly derived from the weathering of silicate rocks. Human activities have also exerted effects on the hydrochemical characteristics of the water in subsidence.

3D printing is a new processing technology, which has developed rapidly in recent years. In addition to industrial production and civil fields, it is also widely used in aerospace, military, medical, and other fields. Material used for 3D printing usually needs to have a more prominent adhesion performance to ensure a strong bonding force between multi-layer materials, so as to support the three-dimensional forming of products. Generally speaking, polymer materials such as wire, photosensitive resin, and polymer powder can be used for 3D printing. The experimental results show that the engineering plastics printed by 3D will have obvious anisotropic characteristics. It is brittle in the transverse direction and has broken before reaching the plastic stage, but it shows obvious elastic–plastic characteristics in the vertical direction. It goes through the linear elastic stage first, and then goes through the plastic softening stage.

It is well known that introducing periodic holes into graphene can be used to obtain semiconducting graphene nanomeshes (GNM). Using Molecular Dynamics (MD) simulations as well as semi-empirical Extended Huckel (EH) method, the mechanical and electronic properties of GNM heterojunction are studied. In this study the mechanical and electronic properties of graphene nanoribbons with different hole sizes and different hole shapes (circular, square and equilateral triangle) were studied. Midgap states were observed near the Fermi level, which are also affected by the geometries of the holes. Dependence of the properties on the density (ρ) was also investigated for each geometry. It has been found that GNM is significantly brittle compared to pristine graphene nanoribbons. It is observed that the relationship between the hole shape and size and the band gap is different for armchair and zigzag chirality.

For problems of transversely isotropic elasticity, the semi inverse method is usually adopted according to the Saint Venant principle in Euclidean space. However, the result of this method is not accurate since the local effect is neglected in the computation. In this paper, the governing equations of Hamiltonian system are constructed by using dual variables. According to the characteristics of Hamiltonian matrix operators and the method of variable separation, all the analytical solutions of transversely isotropic elastic plane is obtained, and the complete solution space is established. In fact, the solution of any problem can be expressed as a linear combination of these basic solutions. In the numericl calculation, the problem of fixed end constraints is studied, and the stress concentration caused by boundary constraints is described.

Electron transport properties of undoped armchair Graphene Nanoribbon Heterojunction (GNRHJ) has been studied using semi-empirical extended Huckel method (EH). A two-probe configuration device utilizing armchair GNRHJ has been proposed. It is shown that a potential barrier was formed at the heterojunction interface between semiconductor and semi-metal, which resemble the conventional Schottky barrier at the interface of semiconductor/metal. Transmission spectrum was analyzed at finite bias; and current-bias voltage characteristic relations were established. Results show that the I–V characteristics of the heterojunction have rectifying nature, with its rectification ratio affected by the geometric asymmetry of the heterojunction.

The unraveling process of armchair and zigzag graphene nanoribbons (GNRs) was studied with molecular dynamics simulations using the Adaptive Intermolecular Reactive Empirical Bond Order Potential for carbon–carbon bond. Simulations were performed at 300°K, with GNR length and width varying from 2.5 nm to 15 nm in 2.5 nm increments. In these simulations, the unraveling of the GNRs was started from two positions; the corner or the middle of the top side. Force–displacement relationship was analyzed for the terminal atom of the unraveling chains. For armchair GNRs (AGNRs) that were unraveled from the corner, the force required for the onset of the unraveling is in the range of 4.279–5.045 eV/Å, and the observed failure force in the carbon chain is in the range of 5.553–5.963 eV/Å. Unraveling will not happen when AGNRs are unraveled from the middle, and zigzag GNRs (ZGNRs) are unraveled either from corner or middle. For the latter cases, the bond between the terminal atom and GNR sheet breaks under the stretching force, and only one carbon atom can be pulled out from the GNR sheet. The size effect of width and length on the unraveling process was also studied. Simulations show that size has a trivial effect on unraveling. Comparison between unraveling of AGNRs and ZGNRs indicates that AGNRs are perfect structure to produce Monatomic Carbon Chains, while ZGNRs are more stable and are good candidate for graphene nanodevices that are free from unraveling disintegration.

Test case prioritization technology improves the efficiency of software testing by optimizing the execution order of test cases, which is an important research topic of software regression testing. In order to solve the problem of requirement-based test case prioritization, this paper proposed a solution based on ant colony optimization algorithm and gave its two different implementation methods: distance-based and index-based implementation. Firstly, a general indicator based on requirements was designed to evaluate the test cases. Secondly, the concept of test case attractivity was proposed, and the definition of the distance between test cases was given based on it. Finally, the main design strategies such as the pheromone update strategy, the optimal solution update strategy, and the local optimal mutation strategy were given. The experimental results show that the method has good global optimization ability, and its overall effect is better than particle swarm optimization algorithm, genetic algorithm and random testing.

To achieve software output domain coverage is a challenge to the functional testing of security-critical software. This paper proposed a test data generation method based on artificial immune algorithm using intelligence testing approach. Firstly, based on the analysis of the software output domain coverage problem, we gave the basic idea of applying artificial immune algorithm to software testing, and introduced the general steps of the algorithm. Secondly, we designed the main operators of the artificial immune algorithm, such as antibody affinity evaluation operator, antibody concentration evaluation operator, immune selection operator, clone operator, mutation operator, etc., to achieve the automatic generation of software test data. Finally, several software was used to verify the validity of the method. The verification results show that the method achieves the software output domain coverage, and its effect is better than the genetic algorithm and random testing.

The extracellular matrix (ECM) is a dynamic and intricate three-dimensional (3D) microenvironment with excellent biophysical, biomechanical, and biochemical properties that may directly or indirectly regulate cell behavior, including proliferation, adhesion, migration, and differentiation. Compared with tissue-derived ECM, cell-derived ECM potentially has more advantages, including less potential for pathogen transfer, fewer inflammatory or anti-host immune responses, and a closer resemblance to the native ECM microenvironment. Different types of cell-derived ECM, such as adipose stem cells, synovium-derived stem cells and bone marrow stromal cells, their effects on articular chondrocytes which have been researched. In this study, we aimed to develop a 3D cell culture substrate using decellularized ECM derived from human umbilical cord-derived mesenchymal stem cells (hUCMSCs), and evaluated the effects on articular chondrocytes. We evaluated the morphology and components of hUCMSC-derived ECM using physical and chemical methods. Morphological, histological, immunohistochemical, biochemical, and real-time PCR analyses demonstrated that proliferation and differentiation capacity of chondrocytes using the 3D hUCMSC-derived ECM culture substrate was superior to that using non-coated two-dimensional plastic culture plates. In conclusion, 3D decellularized ECM derived from hUCMSCs offers a tissue-specific microenvironment for in vitro culture of chondrocytes, which not only markedly promoted chondrocyte proliferation but also preserved the differentiation capacity of chondrocytes. Therefore, our findings suggest that a 3D cell-derived ECM microenvironment represents a promising prospect for autologous chondrocyte-based cartilage tissue engineering and regeneration. The hUCMSC-derived ECM as a biomaterial is used for the preparation of scaffold or hybrid scaffold products which need to further study in the future.

Background: Solid dispersions are an effective formulation technique to improve the solubility, dissolution rate, and bioavailability of water-insoluble drugs for oral delivery. In the last 15 years, increased attention was focused on this technology. There were 23 marketed drugs prepared by solid dispersion techniques. Objective: This study aimed to report the big picture of solid dispersion research from 1980 to 2015. Method: Scientific knowledge mapping tools were used for the qualitative and the quantitative analysis of patents and literature from the time and space dimensions. Results: Western Europe and North America were the major research areas in this field with frequent international cooperation. Moreover, there was a close collaboration between universities and industries, while research collaboration in Asia mainly existed between universities. The model drugs, main excipients, preparation technologies, characterization approaches and the mechanism involved in the formulation of solid dispersions were analyzed via the keyword burst and co-citation cluster techniques. Integrated experimental, theoretical and computational tools were useful techniques for in silico formulation design of the solid dispersions. Conclusions: Our research provided the qualitative and the quantitative analysis of patents and literature of solid dispersions in the last three decades.

As with the advance of automated program repair, many novel repair approaches have been proposed in recent. There also exist empirical work focusing on the performance comparison among those approaches. In this paper we survey recent repair work in five main venues, and plan to answer the question of how to measure the performance of automated program repair in term of evaluation metrics. We summary the evaluation metrics in literature, and conduct the discussion on how to construct the common metrics for further research in the area of automated program repair.

Recent research has made promising progress on automated program repair, but there still lacks common evaluation metrics in the evaluation process, increasing the risk of drawing inconsistent or even contradict conclusions. Based on the survey of recent repair work on automated repair published in five main venues, this paper conducts the discussion on the evaluation metrics having been introduced in literature, and in the furure we plan to present our suggest on how to construct the common metrics to facilitate the fair comparisons among competitive repair techniques.

To do software testing of a large-scale and high-complexity security-critical software system is a difficult task in engineering practice. In this paper, a software system testing method based on formal model is proposed. Firstly, the software function, performance and interface were abstracted, and gave the formal definition of software system. Secondly, different strategies of cue analysis were proposed to identify the requirements of software system testing. Then, the process, the stage and the scene analysis of the software system were carried out, and the scene tree model which could describe the system level behavior of the software was established. Finally, the test coverage criterion based on the scene tree model was proposed, and formal static checking and dynamic test cases generation method were given to generate test case set. Experiments show that the method is effective and feasible.