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In this work, the modified attachment energy model was used to predict the crystal morphology of isosorbide mononitrate (ISMN) in the dichloromethane (CH2Cl2) solvent system and dichloromethane-n-hexane (CH2Cl2-C6H14) mixed solvent system. The solvent effect can significantly affect the crystal morphology, which can profoundly impact both the drug's physicochemical properties and the subsequent technological treatment process. In addition, the interactions between solvent molecules and crystal faces were investigated using molecular dynamics simulation, and radial distribution function (RDF) analysis was performed to determine the types of interactions. The structural parameter S was introduced to characterize the roughness of each crystal surface; the change in the CH2Cl2 diffusion coefficient before and after the addition of C6H14 was analyzed using mean square displacement (MSD). The calculation results of the modified attachment energy from the two solvent systems revealed that C6H14 could accelerate crystal growth, while the crystal morphology was not greatly affected, which is of some significance as a guide for the industrial crystallization process. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the crystallization of DNTF in modified double-base propellants, glycidyl azide polymer (GAP) was used as the coating material for the in situ coating of DNTF, and the performance of the coating was investigated to inhibit the crystallization. The results show that GAP can form a white gel on the surface of DNTF crystals and has a good coating effect which can significantly reduce the impact sensitivity and friction sensitivity of DNTF. Molecular dynamics was used to construct a bilayer interface model of GAP and DNTF with different growth crystal surfaces, and Molecular dynamics calculations of the binding energy and mechanical properties of the composite system were carried out. The results showed that GAP could effectively improve the mechanical properties of DNTF. The values of K/G, γ and ν are higher than those of DNTF crystals, and the values of C12-C44 are positive, indicating that GAP can improve DNTF ductility while also improving toughness. Combining the experimental results with the simulation calculations, energetic binder GAP can be referred to as a better cladding layer for DNTF, which is feasible for inhibiting the DNTF crystallization problem in propellants. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Currently, laser-induced damage is a prominent focus in the field of ultrafast laser micro/nano processing. This article focused on the potential formation thickness of the ultrafast laser-induced sapphire crystal surface recast layer. To investigate the influence of laser parameters and crystal orientation on the recast layer potential formation thickness at the atomic scale, a molecular dynamics model of laser irradiation sapphire crystal was constructed. Experiments of laser-induced recast layer formation were carried out, and the effects of laser fluence, pulse width, and wavelength on the surface recast layer were analyzed. The results show that the ejected atom start formation time is significantly influenced by pulse width, while the potential formation thickness of the recast layer is mainly influenced by the deposited laser energy. Moreover, under the same laser energy, the damage extent in sapphire crystal caused by laser irradiation along the (0001) orientation is significantly weaker compared to irradiation along the (1–100) and (11–20) orientations. This article could provide theoretical and process references for suppressing the ultrafast laser-induced sapphire crystal surface recast layer formation. [ABSTRACT FROM AUTHOR]

Arginine‐modified polyepoxysuccinic acid (Arg‐PESA) was used as a scale inhibitor to study its anti‐scaling and anti‐corrosion performance. The existence of arginine groups enhances the adsorption and chelation of calcium substances, thus inhibiting the formation of a calcium scale. The effects of temperature, scale inhibitor concentration, pH, and calcium ion concentration on scale inhibition performance were studied. The morphologies and structures of the calcium scale and carbon steel coupons were observed and characterized by spectroscopic and microscopic methods. The interaction between Arg‐PESA and different crystal surfaces of calcium carbonate was simulated by molecular dynamics to elucidate the anti‐scaling mechanism. The addition of Arg‐PESA also significantly enhanced the dispersion of iron oxide. [ABSTRACT FROM AUTHOR]

The 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20)-solvent (methanol, ethanol, ethyl acetate and acetone) interfacial models were constructed to investigate the intermolecular interaction variances on different roughness surfaces. The constant volume and temperature molecular dynamics (NVT-MD) simulation was performed on the interfacial models. The mass density distributions of four kinds of solvent at interfaces were calculated based on the NVT-MD results. The surface electrostatic potential (ESP) of seven important extended CL-20 surfaces were studied at the B3LYP-D level with 6-311G (D) basis set. The interaction energies ( E int ), polarities of surfaces, radial distribution function (RDF) and number of H⋯O atom pairs were analyzed. The results show the largest densities of ethanol and acetone appear at the roughest (1 1 0) surface, while generating on the smoothest (1 1 −1) and (0 0 2) surfaces for methanol and ethyl acetate. ESP at the “basin” of (1 1 0) and (1 0 1) rough surfaces are negative, benefiting for attractions of solvent positive groups. RDF analysis indicates that the rough surfaces may be more beneficial for stronger non-bond interaction formation at the solvent-CL-20 interfaces. Results of interaction energies show that E int of the roughest surface [(1 1 0) or (1 0 1)] are the largest (most negative) and relative small at the smooth (0 0 2) surface, indicating the influence of solvent on rougher face growth is more significant. [ABSTRACT FROM AUTHOR]

Improving the surface quality of the ZnGeP 2 crystal is an important way to expand its application range. Given the high difficulty of processing the ZnGeP 2 crystal, the research proposed a method of increasing the processing temperature of the material to expand the range of the plastic region, then improving the surface quality, the feasibility of the method was verified by heating assisted nanoindentation experiment and molecular dynamics simulation. The use of diamond tools to scribe the surface revealed the microscopic morphology changes of the ZnGeP 2 crystal under high temperatures. Finally, with the assistance of heating, the surface of ZnGeP 2 crystal was processed comprehensively by ultra-precision diamond fly-cutting machine, the experimental results showed that as the processing temperature increased, the surface quality of the ZnGeP 2 crystal gradually improved, and the surface roughness Sa could reach to 9.426 nm. The effectiveness of improving the surface quality through heating assisted cutting was verified, which had guiding significance for the processing of other hard and brittle materials. • The theory of improving the surface quality of ZnGeP 2 by heating assisted processing was put forward. • The feasibility of the theory was verified by molecular dynamics simulation and heating assisted nano-indentation. • The influence of heating assistance on the surface quality of ZnGeP 2 was analyzed. • The surface roughness of ZnGeP 2 obtained by heating assistance was higher, up to 9.426 nm. [ABSTRACT FROM AUTHOR]

Sodium carboxymethyl cellulose (SCMC) effectively inhibits the growth of calcium carbonate fouling. In this work, molecular dynamics simulation is used to reveal the antifouling mechanism between SCMC and calcite surface. The configuration, radial distribution function, interaction energy between SCMC and calcite surface, and ability of SCMC to replace water molecules are analyzed. The results indicate that SCMC molecules regularly appear in the vicinity of 2.3 Å near the calcite surface for the different concentrations, and a strong interaction exists between them. The probability of SCMC appearing at ≈2.3 Å from the crystal surface increases with the SCMC concentration, and more SCMC molecules are adsorbed on calcite surface. Moreover, the interaction between SCMC and calcite surface increases with the increase of SCMC concentrations, and the SCMC molecules exhibit strong ability to drive water molecules on calcite surface. The binding energy between three calcite surfaces and SCMC from strong to weak follows the order: (1‐10) > (104) > (110). [ABSTRACT FROM AUTHOR]