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The exploration of lattice distortion is of great significance to design and improve the substitutional solid solutions (SSSs). However, the distortion caused by substitution atoms is not well understood. We propose the atomistic mechanism and establish the corresponding theoretical framework that physically describes the distortion of general SSSs. The consideration is the local distortion propagates from the lattices containing substitution atoms to the bulks. Specifically, the local anisotropic lattice distortion is described by the atomic model based on the minimum energy principle, the non-uniform propagation of the local distortion is expressed by the one-dimension atomic chain model, and the whole-field distortion of SSSs is predicted by superimposing the distortion in the independent atomic chains. The framework is applied not only to predict the lattice constants, track each atoms equilibrium position, but also to estimate the distortion resistance of SSSs, and is validated via ab initio simulations of various SSSs with different types and contents substitution atoms. The research clarifies the origin mechanism and the universal laws of dilatation and lays the fundament for revealing the strengthening mechanism of SSSs.

Although hydrogen embrittlement has been observed and in detail studied nearly for one and a half-century in the past, the physically-based quantitative mechanism is not available yet. Here a new quantification mechanism of H embrittlement at atomic scale applicable for various metals is demonstrated. The process of the cohesion reduction caused by the lattice trapping H atoms in interstices is physically expressed. Specifically, the strongly intensified Pauli repulsion in interstices occupied by H atoms caused by the local increase of electron density leads to lattices dilatate and thus metallic cohesion diminish. The ab initio simulation is conducted to validate the quantification mechanism and the theoretical results of the nearest neighbor atom distance and the maximum cohesion strength agree pretty well with the simulation results for various metals trapping H atoms. The study reveals the content and location of the trapped H atoms and the electronic structure properties of host metals co-determine the cohesion strength of the lattice after trapping H atoms, provides the atomic scale mechanism to quantify the general cohesion reduction of the lattice trapping H atoms, and takes the essential step in predicting the evolution of metallic material mechanical properties in the environment contained H atoms.

Low-permeability reservoirs have strong heterogeneity, and the production prediction based on traditional seepage model is not accurate enough. The dynamic capillary-force seepage model can characterize the dynamic heterogeneity of seepage and more accurately describe the oil–water flow process. In this paper, the calculation formula of the dynamic capillary force is obtained through a real low-permeability core experiment, and the seepage model of dynamic capillary force is established. Based on the model, the authors quantitatively study the effects of formation pressure, heterogeneity and production speed on dynamic capillary force through numerical solutions. It is found that compared with the traditional static capillary-force seepage model, the dynamic capillary-force seepage model makes the predicted water cut increase and the recovery factor decrease. With the increase in development time, formation pressure and production rate will make the effect of dynamic capillary force more obvious. According to the comparison of heterogeneous reservoir models, results show that the horizontal heterogeneity will strengthen the dynamic capillary-force effect, while the vertical heterogeneity will weaken the dynamic capillary-force effect. In the range of research parameters, the recovery ratio predicted by the dynamic capillary-force seepage model can be reduced by 4.7%. A new oil–water seepage model is proposed, which can characterize the spatial difference and dynamic change of low-permeability reservoirs with time. It is of great significance for describing the remaining oil distribution of low-permeability reservoirs in detail and making decisions on efficient EOR measures.

The synthesization and characterization of a new environmental functional material-sulfonic cellulose - were studied in this paper. The preparation conditions were optimized through an orthogonal experiment. The modified cellulose was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The adsorption rules of cationic organic pollutants and heavy metal ions by this new material were discussed. Regeneration and recycling performances of the sulfonic cellulose were also investigated. At the temperature of 323 K, sulfonic cellulose was prepared by grafting 2-acrylamido-2-methylpropane sulfonic acid (AMPS) onto alkali-treated cellulose for 4 h with the employing of ceric ammonium nitrate as initiator. The mass ratio of AMPS to cellulose was 3:1 and the concentration of ceric ammonium nitrate was 63.8 mmol/L. The sulfur content of sulfonic cellulose was 7.32 wt%. The peaks of 1,303 and 1,159 cm-1 in IR suggested the existence of the sulfonic group in sulfonic cellulose. The XRD and SEM results showed that the crystallinity decreased while the specific surface area increased after modification. Batch adsorption results showed that sulfonic cellulose had a favorable adsorption capacity for model contaminants at pH 6.0-7.0. The adsorption process was endothermic and reached equilibrium in 180 mm. The adsorption rules of cationic organic pollutants and heavy metal ions indicated that sulfonic cellulose had high adsorption capacity for the cationic dyes with a coplanar macromolecule structure and organic compounds carrying the amino group. Under room temperature, 1.0 mol/L HCI can be used as a desorption solution and the equilibrium adsorption capacity had little decrease (less than 7%) after six adsorption-desorption cycles. [ABSTRACT FROM AUTHOR]

Removal of anionic surfactants from aqueous solutions by adsorption onto quaternary ammonium cationic cellulose (QACC) was investigated. The effects of solution acidity, initial concentration, adsorption time, and temperature on the adsorption of sodium dodecyl-benzene sulfonate (SDBS), sodium lauryl sulfate (SLS), and sodium dodecyl sulfonate (SDS) were studied. The kinetic experimental data fit well with the pseudo-second-order model; the rate constant of the adsorption increased with temperature. The values of apparent activation energy for the adsorption were calculated as ranging from 10.2 to 17.4 kJ/mol. The adsorption isotherm can be described by the Langmuir isotherm. The values of thermodynamic parameters (ΔH0, ΔS0, and ΔG0) for the adsorption indicated that this process was spontaneous and endothermic. At 318 K, the saturated adsorption capacities of QACC for SDBS, SLS, and SDS were 1.75, 1.53, and 1.39 mmol/g, respectively. The adsorption process was mainly chemisorption and partially physisorption. The results show that QACC is effective for the removal of anionic surfactants. [ABSTRACT FROM AUTHOR]