Pharmacokinetics/pharmacodynamics of marbofloxacin in a Pasteurella multocida serious murine lung infection model

The ARRIVE Guidelines Checklist. Animal Research: Reporting In Vivo Experiments. (PDF 391 kb

Alloying effects of Zr, Nb, Ta, and W on thermodynamic and mechanical properties of TiC based on first-principles calculation

First-principles calculation has been used to study the temperature-dependent thermodynamic and mechanical properties of TiC with additions of transition metal elements through the combination of quasi-harmonic Debye model and thermal electronic excitation. It is found that the substitution behaviors of Zr, Nb, Ta, and W doped into TiC are not only structurally stable, but also would increase its melting temperature. To further determine the alloying effects, the mechanical parameters of doped TiC at finite temperatures have been established by means of ductility, Vickers hardness, fracture toughness, and machinability damage tolerance, from which we reveal that it is feasible to substitute Ti by W in TiC. The computed results are in good agreements with experimental observations in the literature, and are discussed in terms of electronic structures and bond characteristics

Estimating Restrictiveness of SPS Measures for China's Dairy Imports

China has strengthened dairy food safety management with both industrial and trade policies since the melamine incident of 2008. Sanitary and Phytosanitary (SPS) measures constitute the majority of non-tariff measures (NTMs) for China’s dairy imports. Both Trade Restrictiveness Indexes (TRIs) and Overall Trade Restrictiveness Indexes (OTRIs) pertaining to SPS measures are greater than tariff rates for China’s dairy imports. The top ten countries that export dairy to China experienced different levels of market access barriers, depending on whether they export concentrated milk or cream. SPS related measures are essential for China to develop a safe dairy industry. Supplying China with safe and high quality dairy goods is the best method for dairy exporters to overcome barriers of China’s SPS measures

Unraveling L12 Al3X (X=Ti, Zr, Hf) nano-precipitate evolution in aluminum alloys via multi-scale diffusion simulation

The evolution of L12 Al3X (X = Ti, Zr, Hf) nano-precipitates in Al-X alloys was studied by multi-scale diffusion simulation using a combination of first principles calculation and finite element method. The results show that the diffusion coefficient in Al-X solid-solution phase follows DAl>DZr>DHf>DTi, which are in excellent agreement with available experimental values. On the other hand, the mobility of X atoms in L12 Al3X phases is reversed, following DAlAl3X>DTiAl3Ti>DHfAl3Hf>DZrAl3Zr. The calculated Al and X diffusion coefficients in both Al-X solid-solution and L12 Al3X ordered phases were used to simulate the evolution of L12 nano-precipitate embedded in Al-X solid-solution matrix. It is found that only Zr could promote the formation of nano-precipitates at 650 K, the common heat-treatment temperature for advanced Al alloys. At lower temperature, the sluggish atomic movement hinder the nucleation of L12 phase, while at higher temperature the precipitates redissolve into the Al matrix. The multi-scale diffusion simulation underlines the indispensable role of diffusion in L12 Al3X phases on the nano-precipitate evolution, and also provides a feasible way to the rationally design of precipitate strengthening alloys

Electrochemically induced cleavage cracking at twin boundary of sodium layered oxide cathodes

Twinning defects often present in crystalline materials when are subject to mechanical stimuli and are mostly affecting their physicochemical properties. The twinning formation and twin-assisted cracking upon cycling in sodium layered oxides (SLOs) are poorly understood. Combining atomic-resolution imaging, spectroscopy and first principles calculations, we reveal that growth twinning is unexpectedly common in the SLO materials and the twin boundaries show distinct structural and chemical characters from those identified in lithium layered oxides. A unique O-P-O twinning plane was identified in the O3 type SLO materials. We discover that twin-assisted Na diffusion cause large volume variations and trigger cleavage fracture during electrochemical cycling. The present findings not only establish a robust correlation between growth twinning and cleavage cracking in SLOs, but also offer general implications for the development of high-performing intercalation electrode materials by regulating crystallographic defects

Screening Graphene Supported Nitrogen-Coordinated Single-Atom Catalysts for Lithium Polysulfide Conversion in Lithium–Sulfur Batteries

The shuttle effect of lithium polysulfides (Li/PSs) is considered one of the barriers that limits the practical application of lithium–sulfur batteries. Single-atom catalysts (SACs) with modified coordination environments and colorful central metal atoms could modulate the conversion reactions between Li and S and thus provide a viable way to solve the shuttle problem. In this study, the catalytic potential of various graphene-supported SACs (M= Fe, Ni, Pt, and Rh) with pyridine(pd)-N3/N4 and pyrrole(po)-N3/N4 coordination environments in Li/PS conversion are screened based on the thermodynamic stability, adsorption energy, delithiation barrier, and reaction Gibbs free energy. Eight types of SACs, including M-pd-N4 (M= Fe, Ni, Pt, and Rh), M-po-N3 (M= Fe, Ni, and Rh), and Pt-po-N4, demonstrate suitable thermodynamic stability, and their catalytic properties are studied. The adsorption energy indicates that the po-N3 type SACs have strong affiliation to Li/PSs. The M-d and S-p bonding contributes to the low adsorption energy of M-po-N3 (M = Fe, Ni, Rh) to Li/PSs. Despite their strong d-p bonding, Ni-po-N3 and Rh-po-N3 have a low delithiation barrier for Li2S decomposition. The delithiation distance plays an important role in the delithiation barrier. The overall Li/PSs reactions on SACs are determined by the Gibbs free energy. The potential determining step could be classified into two groups for different SACs: one is Li2S4*→Li2S2*, and another is Li2S2*→Li2S*. Based on the calculated catalytic properties, a design chart is summarized, and Ni-po-N3 is proposed as the current state-of-the-art M-N/G SAC for Li/PS conversion

Research advances in phase behavior of multi-component thermal fluids in heavy oil production

The reserves of heavy oil far exceed those of conventional oil， but heavy oil is difficult to exploit due to its high viscosity and density. Thus， the efficient and economical development of heavy oil has become a research focus in the petroleum field. Hybrid thermal recovery are critical for efficiently developing heavy oil reservoirs， and phase behavior of multi-component thermal fluids are the key to designing and evaluating the development processes of heavy oil reservoirs. Therefore， this paper systematically reviewed the current experimental and theoretical research on phase behavior in multi-component thermal fluids of mixed gas systems and heavy oil-gas systems in hybrid thermal recovery. For phase behavior of mixed gas systems， static methods were employed for experimental tests， and state equations and mixing rules were for theoretical prediction. Meanwhile， the phase test of the binary system composed of common gas molecules such as CO2， N2， H2O， and CH4 tends to be mature， while there is a lack of test data and prediction models related to multivariate systems. For heavy oil-gas systems， general experimental processes and recent experimental results were summarized to propose a new experimental device concept for accelerating oil-gas phase equilibrium. Additionally， the disadvantages of current theoretical prediction in gas types， gas injection rates， gas diffusion models， and binary interaction coefficients were pointed out. Furthermore， a prospect was presented for studying the phase behavior of multi-component thermal fluids to promote further mechanism research and parameter optimization of hybrid thermal recovery

A kinetic Monte Carlo simulation method of van der Waals epitaxy for atomistic nucleation-growth processes of transition metal dichalcogenides.

Controlled growth of crystalline solids is critical for device applications, and atomistic modeling methods have been developed for bulk crystalline solids. Kinetic Monte Carlo (KMC) simulation method provides detailed atomic scale processes during a solid growth over realistic time scales, but its application to the growth modeling of van der Waals (vdW) heterostructures has not yet been developed. Specifically, the growth of single-layered transition metal dichalcogenides (TMDs) is currently facing tremendous challenges, and a detailed understanding based on KMC simulations would provide critical guidance to enable controlled growth of vdW heterostructures. In this work, a KMC simulation method is developed for the growth modeling on the vdW epitaxy of TMDs. The KMC method has introduced full material parameters for TMDs in bottom-up synthesis: metal and chalcogen adsorption/desorption/diffusion on substrate and grown TMD surface, TMD stacking sequence, chalcogen/metal ratio, flake edge diffusion and vacancy diffusion. The KMC processes result in multiple kinetic behaviors associated with various growth behaviors observed in experiments. Different phenomena observed during vdW epitaxy process are analysed in terms of complex competitions among multiple kinetic processes. The KMC method is used in the investigation and prediction of growth mechanisms, which provide qualitative suggestions to guide experimental study

Core–Shell Nanocomposites for Improving the Structural Stability of Li-Rich Layered Oxide Cathode Materials for Li-Ion Batteries

The structural stability of Li-rich layered oxide cathode materials is the ultimate frontier to allow the full development of these family of electrode materials. Here, first-principles calculations coupled with cluster expansion are presented to investigate the electrochemical activity of phase-separation, core–shell-structured <i>x</i>Li₂MnO₃·(1 – <i>x</i>)­LiNiCoMnO₂ nanocomposites. The detrimental surface effects of the core region can be countered by the Li₂MnO₃ shell, which stabilizes the nanocomposites. The operational voltage windows are accurately determined to avoid the electrochemical activation of the shell and the subsequent structural evolution. In particular, the dependence of the activation voltage with the shell thickness shows that relatively high voltages can still be obtained to meet the energy density needs of Li-ion battery applications. Finally, activation energies of Li migration at the core–shell interface must also be analyzed carefully to avoid the outbreak of a phase transformation, thus making the nanocomposites suitable from a structural viewpoint