In the present work, an ODS 12 Cr steel was characterized using Electron Microscopy techniques, in an as-received condition and after annealing treatments between 773 K and 1573 K. Results show a complex microstructure, with the presence of fine Y–Ti–O nanoparticles dispersed in the matrix. After annealing at 1573 K, the average diameter of Y–Ti–O nanoparticles increases from ~ 4 to ~ 7 nm and partial recrystallization occurs. The trapping behavior of deuterium in the steel in its as-received state and annealed at 1573 K was investigated. Samples were exposed to low-energy deuterium plasma and analyzed with thermal desorption spectroscopy, after waiting times of 1 day and 25 days. The samples measured 1 day after exposure released a higher total amount of deuterium than the ones measured after 25 days. The effect of waiting time is explained by the release of deuterium, at 300 K, from sites with low activation energy for detrapping, E_d. In the as-received condition, part of the deuterium detrapped at 300 K was re-trapped by high-E_d sites. For the samples in the annealed condition, the redistribution of deuterium from low-E_d to high-E_d sites was not observed, but the total amount of deuterium released was higher.

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Iron-matrix composites with calcium silicate (CS) bioceramic as the reinforcing phase were fabricated through powder metallurgy processes. The microstructures, mechanical properties, apatite deposition and biodegradation behavior of the Fe-CS composites, as well as cell attachment and proliferation on
their surfaces, were characterized. In the range of CS weight percentages selected in this study, the composites possessed compact structures and showed differently decreased bending strengths as compared with pure iron. Immersion tests in simulated body fluid (SBF) revealed substantially enhanced deposition of CaP on the surfaces of the composites as well as enhanced degradation rates as compared with pure iron. In addition, the composite containing 20% CS showed a superior ability to stimulate hBMSCs proliferation when compared to pure iron. Our results suggest that incorporating calcium silicate particles into iron could be an effective approach to developing iron-based biodegradable bone implants with improved biomedical performance.@en

As part of an international intercomparison project, the weak temperature gradient (WTG) and damped gravity wave (DGW) methods are used to parameterize large-scale dynamics in a set of cloud-resolving models (CRMs) and single column models (SCMs). The WTG or DGW method is implemented using a configuration that couples a model to a reference state defined with profiles obtained from the same model in radiative-convective equilibrium. We investigated the sensitivity of each model to changes in SST, given a fixed reference state. We performed a systematic comparison of the WTG and DGW methods in different models, and a systematic comparison of the behavior of those models using the WTG method and the DGW method. The sensitivity to the SST depends on both the large-scale parameterization method and the choice of the cloud model. In general, SCMs display a wider range of behaviors than CRMs. All CRMs using either the WTG or DGW method show an increase of precipitation with SST, while SCMs show sensitivities which are not always monotonic. CRMs using either the WTG or DGW method show a similar relationship between mean precipitation rate and column-relative humidity, while SCMs exhibit a much wider range of behaviors. DGW simulations produce large-scale velocity profiles which are smoother and less top-heavy compared to those produced by the WTG simulations. These large-scale parameterization methods provide a useful tool to identify the impact of parameterization differences on model behavior in the presence of two-way feedback between convection and the large-scale circulation.

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In this paper, we revisit the full lattice representation of continuous piecewise affine (PWA) functions and give a formal proof of its representation ability. Based on this, we derive the irredundant lattice PWA representations through removal of redundant terms and literals. Necessary and sufficient conditions for irredundancy are proposed. Besides, we explain how to remove terms and literals in order to ensure irredundancy. An algorithm is given to obtain an irredundant lattice PWA representation. In the worked examples, the irredundant lattice PWA representations are used to express the optimal solution of explicit model predictive control problems, and the results turn out to be much more compact than those given by a state-of-the-art algorithm.@en

The cometabolism as a technique for enhancing biodegradation of pentachlorophenol (PCP) has been widely used, but the effect of dosing mode of growth substrates on the cometabolic degradation of PCP in an anaerobic system with and without the addition of ZVI is still not clear. In this study, the effects of dosing modes of sodium acetate as co-substrate, i.e., one-step pulse, evenly distributed pulse, and stepwise declining pulse, and zero-valent iron (ZVI) of 1 mg l−1 on pentachlorophenol (PCP) degradation and changes in anaerobic microbial community were examined in batch tests. The results indicated that the degradation kinetic constants of PCP were related to the dosing mode of co-substrate. The complete mineralization rates of PCP in the two groups with evenly distributed pulse mode and stepwise declining pulse mode were faster than the observed rates of the group with one-step pulse mode, according to the quantitative analysis of 2,3,5,6-tetrachlorophenol, 2,3,5-tetrachlorophenol, and 2,5-chlorophenol. In addition, there was a substantial change in the content of intracellular polysaccharide in the cometabolic process of the one-step pulse and stepwise declining pulse groups. Furthermore, the electron transport system (ETS) activities reached to the maximum values of 0.841 and 0.813 ug g−1 in these two groups with the addition of 1 g l−1 ZVI, respectively. Moreover, Alcaligenes (11.02%), Comamonas (14.58%), and Ralstonia (9.16%) were the dominant genera in the groups with the three co-substrate dosing modes, respectively. This study provides a new insight into achieving anaerobic cometabolic degradation of PCP with different dosing modes of co-substrate.@en

As part of an international intercomparison project, a set of single-column models (SCMs) and cloud-resolving models (CRMs) are run under the weak-temperature gradient (WTG) method and the damped gravity wave (DGW) method. For each model, the implementation of the WTG or DGW method involves a simulated column which is coupled to a reference state defined with profiles obtained from the same model in radiative-convective equilibrium. The simulated column has the same surface conditions as the reference state and is initialized with profiles from the reference state. We performed systematic comparison of the behavior of different models under a consistent implementation of the WTG method and the DGW method and systematic comparison of the WTG and DGW methods in models with different physics and numerics. CRMs and SCMs produce a variety of behaviors under both WTG and DGW methods. Some of the models reproduce the reference state while others sustain a large-scale circulation which results in either substantially lower or higher precipitation compared to the value of the reference state. CRMs show a fairly linear relationship between precipitation and circulation strength. SCMs display a wider range of behaviors than CRMs. Some SCMs under the WTG method produce zero precipitation. Within an individual SCM, a DGW simulation and a corresponding WTG simulation can produce different signed circulation. When initialized with a dry troposphere, DGW simulations always result in a precipitating equilibrium state. The greatest sensitivities to the initial moisture conditions occur for multiple stable equilibria in some WTG simulations, corresponding to either a dry equilibrium state when initialized as dry or a precipitating equilibrium state when initialized as moist. Multiple equilibria are seen in more WTG simulations for higher SST. In some models, the existence of multiple equilibria is sensitive to some parameters in the WTG calculations.

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A transferable force field for the PbSe-CdSe solid system using the partially charged rigid ion model has been successfully developed and was used to study the cation exchange in PbSe-CdSe heteronanocrystals [A. O. Yalcin et al., "Atomic resolution monitoring of cation exchange in CdSe-PbSe heteronanocrystals during epitaxial solid-solid-vapor growth," Nano Lett. 14, 3661-3667 (2014)]. In this work, we extend this force field by including another two important binary semiconductors, PbS and CdS, and provide detailed information on the validation of this force field. The parameterization combines Bader charge analysis, empirical fitting, and ab initio energy surface fitting. When compared with experimental data and density functional theory calculations, it is shown that a wide range of physical properties of bulk PbS, PbSe, CdS, CdSe, and their mixed phases can be accurately reproduced using this force field. The choice of functional forms and parameterization strategy is demonstrated to be rational and effective. This transferable force field can be used in various studies on II-VI and IV-VI semiconductor materials consisting of CdS, CdSe, PbS, and PbSe. Here, we demonstrate the applicability of the force field model by molecular dynamics simulations whereby transformations are initiated by cation exchange@en

A set of interatomic pair potentials is developed for ZnO based on the partially charged rigid ion model (PCRIM). The derivation of the potentials combines lattice inversion, empirical fitting, and ab initio energy surface fitting. We show that, 0 despite the low number of parameters in this model (8), a wide range of physical properties is accurately reproduced using the new potential model. The calculated lattice parameters and elastic constants of ZnO in the wurtzite (WZ) phase, as well as the lattice parameters and stabilities of ZnO in other high-pressure and metastable phases, agree well with experiments and with density functional theory (DFT) calculations. The calculated transition pressure of the wurtzite-to-rocksalt (WZ-to-RS) transition is 12.3 GPa. A wurtzite-to-honeycomb (WZ-to-HC) phase transition induced by uniaxial pressure along the c-axis is simulated by means of molecular dynamics (MD) simulations. The WZ-to-HC transition takes place at an uniaxial pressure of 8.8 GPa while the reverse transition takes place at 2.9 GPa, which is consistent with DFT calculations. Other physical properties, including phonon dispersion, phonon density of states, and melting point calculated using our ZnO potential model are in good agreement with experimental and DFT data. Limitations of the novel ZnO potential model are also discussed.@en