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Seven composite models of meta-aramid fibers with different moisture contents were studied using molecular dynamics simulation. The effects of moisture on the thermal stability and mechanical properties of the fibers and their mechanisms were analyzed, considering characteristics such as hydrogen bonding, free volume, mean square displacement, and mechanical parameters. The simulation results showed that the large number of hydrogen bonds between water molecules and meta-aramid fibers destroyed the original hydrogen-bond network. Hydrogen bonds between the molecular chains of meta-aramid fibers were first destroyed, and their number decreased with increasing moisture content. The free volume of the fibers thereby increased, the interactions between fiber chains weakened with increasing moisture content, and the fiber chain movement intensified accordingly. The ratio of diffusion coefficients of the water molecules to moisture contents of the composite models increased linearly, and the water molecule diffusion increased, which accelerated the rate of damage to the original hydrogen-bond network of the meta-aramid fibers and further reduced their thermal stability. In general, the mechanical properties of the composites were negatively related to their moisture content. [ABSTRACT FROM AUTHOR]

The February 2024 issue of the Journal of Materials Science features a cover paper titled "Enhancing the impact property of high-entropy alloys with graphene layers: a molecular dynamics study" by Qing-Xiang Pei et al. The paper explores the use of molecular dynamics simulations to study the impact of a projectile on a high-entropy alloy (HEA) containing layers of graphene. The authors highlight the broad interest in their research, as it appeals not only to the modeling community but also to other communities interested in the materials being modeled. The paper provides valuable insights into the behavior of composite materials and includes figures illustrating the preparation of the model material and the interaction between a projectile and the HEA. The article is freely accessible through the SharedIt link provided, and the corresponding authors can be contacted for access to the data. The publisher, Springer Nature, maintains a neutral stance on jurisdictional claims and institutional affiliations. [Extracted from the article]

The quality of transformer insulation is related to the safe and stability operation of the power grid, and the life of the transformer oil-paper insulation system mainly depends on the state of paper insulation. With the continuous improvement of the voltage level, the requirements for insulating paper are becoming higher and higher. Based on the molecular dynamics simulation technology, the effects of carbon nanowires with three different structures on the thermodynamic properties of cellulose insulating paper were analyzed from the aspects of mechanical parameters, MSD (mean square displacement), CED (cohesive energy density) and hydrogen bond. The simulation results showed that the carbon nanowires with three different structures have improved the thermodynamic properties of cellulose. Among them, the hard chiral carbon nanowires have the most significant improvement in the thermodynamic properties of cellulose. The elastic modulus, bulk modulus, and shear modulus have been increased by 30%, 25.6%, and 32.9%, respectively. It was found that the thermal stability of cellulose insulation paper modified by three different structure carbon nanowires was improved. The increase of thermal stability was mainly due to the increase of the cohesive energy density and the number of intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

Abstract: Highly ordered polymer composites of layered graphene/graphene oxide (GO) sheets, i.e. graphene/GO paper, are attractive candidates for novel structural and functional applications. Here, molecular dynamics simulations are employed to elucidate the structural and mechanical properties of the graphene/GO paper based polymer composites. We find that the large scale properties of these composites are controlled by the conformation and content of polymer molecules within the interlayer galleries. Polymer conformations affect the interlayer spacing, while the polymer content controls the layer–matrix interactions, thereby affecting the elastic modulus of the composites. Additionally, the chemical composition of individual GO sheets also plays a critical role in establishing the mechanical properties of the composites. Specifically, a higher density of oxygen-containing groups leads to the decrease of elastic modulus of individual GO sheets. However, the groups also lead to the increased hydrogen bonds between the GO sheets and polymer molecules, resulting in the corresponding increase in overall stiffness. Our studies suggest the possibility of tuning the properties of graphene/GO paper composites by altering the conformation and content of polymer, as well as the density of functional groups on individual GO sheets. [Copyright &y& Elsevier]

Abstract: The formation mechanisms of wrinkles in single layer graphene sheets and graphene oxide (GO) papers, as well as their effects on the corresponding Young’s moduli have been studied based on the molecular dynamics simulations. Wrinkling occurs in GO papers in the form of undulation as a consequence of the interactions between the adjacent individual GO sheets. In particular, the edge-to-edge interactions play a dominant role in determining the wrinkled structure, whereas the face-to-face interactions hardly cause wrinkles as they are thermodynamically stable with inherently low potential energies. Both graphene sheets and GO papers with wrinkles show two different modes of deformation in tension. Although wrinkles have only a negligible effect on Young’s modulus of the individual graphene sheets, they reduce the Young’s modulus of GO papers by as much as 60% of the pristine value. [Copyright &y& Elsevier]

The degree of polymerization (DP) has been regarded as an important symbol of mechanical strength, reflecting the aging condition of transformer insulation paper. In this article, a new concept called fracture degree is proposed on the basis of DP. First, nine cellulose Iβ crystal models with different fracture degrees were built. Then relevant mechanical parameters and hydrogen bond numbers were calculated by molecular dynamics (MD) simulation. Results showed that during the aging process of insulation paper with fracture of cellulose chain, the elastic constant C33 produces appreciable impact on the Young's modulus (E). With the decrease of DP and increase of fracture degree, the Young's modulus step decreases. To the 50% and 100% fracture degree models respectively, the relationship between their different degrees of polymerization and Young's modulus is subjected to similar exponential distributions. With the increase of the fracture degree, the average hydrogen bond number drops, and the change rules apply to the Young's modulus. Since hydrogen bond is the main factor of mechanical strength, it can be inferred that the fracture degree influences mechanical strength seriously. [ABSTRACT FROM AUTHOR]

An attempt has been made for enhancing the thermostability of xylanase (Mxyl) retrieved from a compost-soil-based metagenomic library. The analysis of the structure of xylanase by molecular dynamics simulation revealed more structural fluctuations in β-sheets. When the surface of β-sheets was enriched with arginine residues by substituting serine/threonine by site-directed mutagenesis, the enzyme with four arginine substitutions (MxylM4) exhibited enhanced thermostability at 80 °C. The T1/2 of MxylM4 at 80 °C, in the presence of birchwood xylan, increased from 130 to 150 min at 80 °C without any alteration in optimum pH and temperature and molecular mass. Improvement in thermostability of MxylM4 was corroborated by increase in Tm by 6 °C over that of Mxyl. The Km of MxylM4, however, increased from 8.01 ± 0.56 of Mxyl to 12.5 ± 0.32 mg ml −1, suggesting a decrease in the affinity as well as specific enzyme activity. The Mxyl as well as MxylM4 liberated chromophores and lignin-derived compounds from kraft pulp, indicating their applicability in pulp bleaching. [ABSTRACT FROM AUTHOR]

The diffusion behaviour of hydrogen, carbon monoxide, carbon dioxide, methane, acetylene, ethylene and ethane in oil and paper medium was examined using molecular dynamics to reveal the diffusion mechanism of gas molecules in transformer oil–paper insulation system at the microscopic level. These compounds are commonly used in the dissolved gas analysis of power transformers and produced during the ageing process of oil–paper composite insulating material. Two groups of models were constructed using molecular dynamics simulation software to simulate the diffusion behaviour of the aforementioned seven types of small gas molecules in oil and paper. The diffusion coefficients, displacement features, free volume characteristics and interaction energies of the gas molecules were investigated. In particular, the diffusion micro-mechanism of the gas molecules was observed. The differences in diffusion features among the gas molecules were discussed, and the factors influencing the diffusion of the gas molecules were compared. Simulation results indicate that the diffusion coefficients of gas molecules in cellulose is an order of magnitude lower than that in oil, and the diffusion coefficients of these gas molecules in the two types of insulation media have different orders. Free volume of gas molecules is the main factor that influences the diffusion behaviour in oil, whereas intermolecular interaction is the main influencing factor of diffusion behaviour in cellulose. [ABSTRACT FROM PUBLISHER]

This paper series aims to establish a complete correspondence between fine-grained (FG) and coarse-grained (CG) dynamics by way of excess entropy scaling (introduced in Paper I). While Paper II successfully captured translational motions in CG systems using a hard sphere mapping, the absence of rotational motions in single-site CG models introduces differences between FG and CG dynamics. In this third paper, our objective is to faithfully recover atomistic diffusion coefficients from CG dynamics by incorporating rotational dynamics. By extracting FG rotational diffusion, we unravel, for the first time reported to our knowledge, a universality in excess entropy scaling between the rotational and translational diffusion. Once the missing rotational dynamics are integrated into the CG translational dynamics, an effective translation-rotation coupling becomes essential. We propose two different approaches for estimating this coupling parameter: the rough hard sphere theory with acentric factor (temperature-independent) or the rough Lennard-Jones model with CG attractions (temperature-dependent). Altogether, we demonstrate that FG diffusion coefficients can be recovered from CG diffusion coefficients by (1) incorporating "entropy-free" rotational diffusion with translation-rotation coupling and (2) recapturing the missing entropy. Our findings shed light on the fundamental relationship between FG and CG dynamics in molecular fluids. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were used to analyze the internal mechanism for the observed improvement in performance of nano-modified meta-aramid insulation paper from a microscopic point of view. The results showed that the k-polyphenylsilsesquioxane(PPSQ) modified meta-aramid insulation paper was superior to b-PPSQ modified meta-aramid insulation paper in terms of its thermal stability and mechanical and electrical properties. The analysis of microscopic parameters showed that the stiffness of k-PPSQ was less than that of b-PPSQ, and the hydroxyl groups on the open-loop system were more likely to enter the dispersed system, resulting in higher bonding strength, meta-aramid fiber chains between k-PPSQ molecules, and the formation of hydrogen bonds. Additionally, the nano-enhancement effects of k-PPSQ and b-PPSQ resulted in various improvements, including a reduction in pores between molecules in the blend model, an increase in the contact area, the formation of interfacial polarization, and a reduction in defects at the interface. [ABSTRACT FROM AUTHOR]

A bibliometric analysis of TASK Quarterly in the years 1997-2021 in terms of various bibliometric indicators was performed to celebrate the 25th anniversary of the publication of the first issue of the journal. The number of publications and citations increased over the mentioned span of years. The leading countries in terms of the greatest number of papers published in TASK Quarterly are Poland, Italy, Germany, Ukraine, USA and Russia. Moreover, it is shown that international collaboration can result in a greater number of citations per publication. The average publication time in TASK Quarterly is 77 days, including the average submission-acceptance time (44 days) and the average acceptancepublication time (33 days). Based on the author's findings, it can be seen that although TASK Quarterly is a journal devoted mainly to physical and computer sciences, many publications also focus on the aspects related to mathematics, biomedical engineering and biophysics. CFD, molecular dynamics, the finite element method (FEM) and numerical simulations are the most frequently used keywords in articles published in TASK Quarterly. [ABSTRACT FROM AUTHOR]

The document is a contents list from the journal CrystEngComm, focusing on the design and understanding of solid-state and crystalline materials. It includes research papers on topics such as organic-inorganic hybrid oxygen evolution catalysts, crystal structure prediction, battery construction, and magnetic studies of coordination polymers. The journal also covers topics like colorimetric detection, degradation of pollutants, and laser crystal growth, showcasing a diverse range of research in the field of chemistry. [Extracted from the article]

• Capability of the lead based perovskite halide family towards NH 3 gas sensing both by visual detection as well as electrical detection method. • The compatibility with papers sensor due to low temperature solution processing working at room temperature. • Compatible with extremely low power paper electronics for sensing operation during electrical detection. • The family of lead halide perovskite follows a general sensing mechanism substantiated by molecular dynamics simulation. • Develop them as a common platform for solid state room temperature NH 3 gas sensor with cost effective and disposable, paper based technology. In this paper we show that, high sensitivity and high selectivity room temperature ammonia (NH 3) gas sensors with both visual and electrical response can be made from family of lead halide perovskites with different cations and anions. These sensors, based on papers, act as general platforms for new generation of solid state gas sensors for sensitive detection of NH 3 gas by simple color change (∼10 ppm sensitivity) as well as electrical resistance change with sub ppm sensitivity limited by electrical noise only. The sensors with materials like CH 3 NH 3 PbI 3 (MAPI), CH 3 NH 3 PbBr 3 (MAPB) and CH(NH 2) 2 PbI 3 (FAPI), are grown on paper from solution. MAPB changes color from orange to white and FAPI and MAPI from black to yellow under NH 3 gas exposure respectively. For electrical sensor operation, a fixed concentration (20 ppm) of NH 3 gas, the sensitivity of MAPI is highest at 96 % followed by MAPB at 82 % and FAPI at 65 %. The sensors with electrical read out could trace NH 3 gas well below ppm level with only few nanowatt of power consumption. Based on experiments, a sensing mechanism has been proposed. The proposed mechanism mainly consists of decomposition of the perovskite halides to lead (Pb) halide by preferential adsorption of NH 3 gas molecules. The proposed mechanism has also been substantiated by molecular dynamics simulations. These sensors fabricated by simple solution process on paper substrates and operable at ambient temperature, are compatible with very low power (∼ nW) paper electronics. [ABSTRACT FROM AUTHOR]

Thermal energy storage and utilization has been widely concerned due to the intermittency, renewability, and economy of renewable energy. In this paper, the potential energy function of binary Na2CO3–K2CO3 salt was first constructed using the Deep Potential GENerator (DPGEN) enhanced sampling method. Deep potential molecular dynamics simulations were performed to calculate the thermal properties and structural evolution of binary carbonates. The results show that as the temperature increases from 1073 to 1273 K, the viscosity and thermal conductivity decrease from 5.011 mPa s and 0.502 W/(m K) to 2.526 mPa s and 0.481 W/(m K), respectively. The decrease in viscosity is related to the distance and interaction between the molten salt ions. In addition, the diffusion coefficients, energy barriers, ionic radius, angular distribution function, and coordination number of molten salt were calculated and analyzed. The CO32− exhibits a stable planar triangular structure. The ionic radius of Na+ is smaller than that of K+, which makes Na+ suffer less spatial hindrance during motion and has a higher diffusion coefficient. The energy barriers that Na+ needs to overcome to escape the Coulomb force is greater than that of K+ ions, so molten salt containing Na+ may possess greater heat storage potential. We believe that the potential function constructed with DPGEN enhanced sampling strategy can provide more convincing results for predicting the thermal properties of molten salts. This paper aims to provide a technical route to develop the novel complex molten salt phase change material for thermal energy storage. [ABSTRACT FROM AUTHOR]

The glass transition temperature (Tg) in the amorphous region of an insulation paper is one of the most important characteristics for thermal stability. Molecular dynamic simulations have been performed on three micro-structural models, namely, amorphous pure cellulose, amorphous cellulose with water and amorphous cellulose with oil, to study the microscopic mechanism of the glass transition process for oil-immersed transformer insulation paper. Using the method of specific volume versus temperature curve, the Tg of amorphous pure cellulose, cellulose with water, and cellulose with oil was determined as 448, 418 and 440 K, respectively. The current study may provide some information for thermal aging. The simulation results show that during the glass transition process, both the chain motion and mechanical properties of cellulose changes significantly. Relative to the oil molecules, water molecules immersed in the amorphous region of insulation paper can disrupt hydrogen bonds between cellulose chains. This phenomenon results in a significant reduction in the glass transition temperature and affects the thermal stability of the insulation paper. [ABSTRACT FROM AUTHOR]

Abstract: Moisture is an important factor that influences the safe operation of transformers. In this study, molecular dynamics was employed to investigate the diffusion behavior of water molecules in the oil–paper insulation materials of transformers. Two oil–cellulose models were built. In the first model, water molecules were initially distributed in oil, and in the second model, water molecules were distributed in cellulose. The non-bonding energies of interaction between water molecules and oil, and between water molecules and cellulose, were calculated by the Dreiding force field. The interaction energy was found to play a dominant role in influencing the equilibrium distribution of water molecules. The radial direction functions of water molecules toward oil and cellulose indicate that the hydrogen bonds between water molecules and cellulose are sufficiently strong to withstand the operating temperature of the transformer. Mean-square displacement analysis of water molecules diffusion suggests that water molecules initially distributed in oil showed anisotropic diffusion; they tended to diffuse toward cellulose. Water molecules initially distributed in cellulose diffused isotropically. This study provides a theoretical contribution for improvements in online monitoring of water in transformers, and for subsequent research on new insulation materials. [Copyright &y& Elsevier]

Yu I et al. i [1] presented an interesting investigation on the flow and aerodynamic heating characteristics of air and hydrogen-oxygen combustion gas under the same total temperature and pressure. The authors concentrated on the variations of temperature and velocity of the combustion gas flow in a nozzle and the shock standoff distance and stagnation pressure for the combustion gas flows around a sphere. Fluid mechanics covers a vast scope of flow phenomena that occur in nature, biology, and numerous engineering fields. [Extracted from the article]

Based on fundamental difference in diffusion mechanisms of substitutional and interstitial atoms and using molecular dynamics simulation of hydrogen migration, it is shown that accelerated hydrogen flux in the polycrystalline iron, as observed in the course of cathodic charging, cannot originate from the enhanced hydrogen grain boundary diffusion. A possible role of grain boundary cracking is supposed. [ABSTRACT FROM AUTHOR]

Transformer faults frequently occur because of a deterioration of the insulation performance caused by corrosive sulfides. By studying the distribution and diffusion of different sulfides in oil paper, the mechanism of sulfur corrosion can be further investigated. Here, the diffusion of macromolecular sulfides (represented by DBDS and n-hexadecanethiol) and small molecular sulfides (represented by hydrogen sulfide) in oil-paper insulation systems were studied based on molecular dynamics simulation methods. The simulation results showed that cellulose had a strong interaction with hydrogen sulfide, while oil had a strong interaction with DBDS and n-hexadecathiol. This makes the trajectory and relative concentration of the various sulfides in the oil-Paper system different: DBDS was mainly distributed in oil, n-hexadecathiol was distributed at the oil-paper interface, and hydrogen sulfide was mainly distributed in cellulose. In addition, the diffusibility of DBDS and n-hexadecathiol in oil and cellulose were negatively correlated with the interaction energy: a larger interaction energy resulted in lower diffusion. The diffusion of hydrogen sulfide in oil paper was determined by the free volume fraction. A larger free volume fraction resulted in more intense molecular diffusion. The results of this work can provide a reference for prevention of sulfur corrosion. • Different sulfide and oiled paper have different binding ability. • The diffusion ability of sulfide is correlated with the interaction energy. • For small molecule sulfides, their ability to diffuse depends on its free volume. [ABSTRACT FROM AUTHOR]

Cellulosic insulation paper is usually used in oil-immersed transformer insulation systems. In this study, the molecular dynamics method based on reaction force field (ReaxFF) was used to simulate the pyrolysis process of a cellobiose molecular model. Through a series of ReaxFF- Molecular Dynamics (MD) simulations, the generation path of ethanol at the atomic level was studied. Because the molecular system has hydrogen bonding, force-bias Monte Carlo (fbMC) is mixed into ReaxFF to reduce the cost of calculation by reducing the sampled data. In order to ensure the reliability of the simulation, a model composed of 20 cellobioses and a model composed of 40 cellobioses were respectively established for repeated simulation in the range of 500–3000 K. The results show that insulating paper produced ethanol at extreme thermal fault, and the intermediate product of vinyl alcohol is the key to the aging process. It is also basically consistent with others' previous experiment results. So it can provide an effective reference for the use of ethanol as an indicator to evaluate the aging condition of transformers. [ABSTRACT FROM AUTHOR]

The European Biophysics Journal Prizes awarded at the European Biophysical Societies Association (EBSA) Congress in Stockholm in the Summer of 2023 recognised papers published in 2020 and 2021 which made use of multiple complementing experimental, theoretical and computational approaches. One of the winning papers addressed the specific role of arginine residues within antimicrobial and cell-penetrating peptides, in promoting membrane defect stabilisation and pore formation. The other winning paper described the influence of atomic force microscopy probe geometry on the measurement of surface deformability, assessed for investigation of the differing viscoelastic properties of non-malignant and cancerous cells. These papers showcase biophysical science; the importance of combining different experimental, modelling and molecular dynamics methods; and how researchers need to understand the theoretical basis and the limitations of the techniques they use. EBSA warmly congratulates the authors on their work and its subsequent recognition. Publication of these papers also demonstrates the ongoing commitment of the European Biophysics Journal to molecular scale and to systems biophysics, and to support of the international biophysical community. [ABSTRACT FROM AUTHOR]

In a recent paper, we derived a new equation of state (EOS) for dense hydrogen/helium mixtures that covers the temperature–density domain from solar-type stars to brown dwarfs and gaseous planets. This EOS is based on the so-called additive volume law and thus does not take into account the interactions between the hydrogen and helium species. In the present paper, we go beyond these calculations by taking into account H/He interactions, derived from quantum molecular dynamics simulations. These interactions, which eventually lead to H/He phase separation, become important at low temperature and high density, in the domain of brown dwarfs and giant planets. The tables of this new EOS are made publicly available. [ABSTRACT FROM AUTHOR]

• Nano-SiO 2 increases the acids in oil for an oil-paper insulating systems. • The diffusion of acids was explored by molecular dynamics. • The addition of nano-SiO 2 increases the adsorption energy of oil to acids. • Acids can be adsorbed on hydroxylated nano-SiO 2 in the form of hydrogen bond. It is important to study the diffusion of acids because acids can accelerate the aging of oil-paper insulation systems. In the paper, the diffusion of acids is weakened by adding nano-SiO 2 in oil. The results of relative concentration, centroid trajectory and density field distribution by molecular dynamics simulation show that there are more acids in the oil of nano-SiO 2 oil-cellulose paper system (Nano-O-P model) than that of pure mineral oil-cellulose paper system (Pure-O-P model). This is primarily attributed to the hydrogen bonding of nano-SiO 2 to acids and the adsorption energy of oil to acids was increased in the Nano-O-P model. The number of hydrogen bonds between formic acids and cellulose in the Nano-O-P model was reduced by 32.5% compared with that in the Pure-O-P model, protecting the intermolecular hydrogen bonding structure of the cellulose paper and reducing the promotional effect of acids on the aging of oil-paper insulating systems. [ABSTRACT FROM AUTHOR]

Azobenzenes are ubiquitous motifs very important in many areas of science. Azo compounds display crucial properties for important applications, mainly for the chemical industry. Because of their discovery, the main application of aromatic azo compounds has been their use as dyes. These compounds are excellent candidates to function as molecular switches because of their efficient cis–transisomerization in the presence of appropriate radiation. The classical methods for the synthesis of azo compounds are the azo coupling reaction (coupling of diazonium salts with activated aromatic compounds), the Mills reaction (reaction between aromatic nitroso derivatives and anilines) and the Wallach reaction (transformation of azoxybenzenes into 4-hydroxy substituted azoderivatives in acid media). More recently, other preparative methods have been reported. This critical reviewcovers the various synthetic methods reported on azo compounds with special emphasis on the more recent ones and their mechanistic aspects (170 references). [ABSTRACT FROM AUTHOR]

Covering: 2000 to June 2010 [ABSTRACT FROM AUTHOR]

AFM surface adhesion measurements made on virgin and recycled bleached kraft pulp show that recycling increases the apparent hydrophilicity of the fiber surface. Yet, the water retention values and strength decreases as expected, which is consistent with internal cross-linking of the bonding sites and a reduction in hydrophilicity. Recycling does not affect the amount of monolayer water bound to the fiber surface indicating that the pore water is reduced but not the water bound to fiber surfaces. It is proposed that the contact area between the AFM tip and the fiber is greater for recycled material than for virgin. This could be caused by fiber shrinkage, changes in the angle of contact, lamination of fibrils, or other processes. Hence, in this instance, the surface adhesion values are more a measure of the topography of the surface than of its chemistry. An application to newsprint is illustrated. [ABSTRACT FROM AUTHOR]

Abstract: We study the deviations for the results of the properties of a hard-sphere gas near the walls of a micro/nano channel using the hybrid MD–MC simulation method compared to the pure MD and MC results. Our model for the micro channel consists of two parallel infinite plates situated at distance L apart from each other, and of gas molecules confined between these two walls. We study the dependence of the deviations for higher densities, considering different lengths of the different simulation domains in the hybrid MD–MC method. We find that when density is increased, the deviations in the pure MC results are increasing compared to pure MD results. The deviations in the hybrid simulation results are decreasing and are very small when increasing the width of the solid–gas interface. The deviations of the pure MC simulation results from the pure MD simulation results for the number density are found to be around 0.9%, when the reduced density and the width of the channel , where λ is the mean free path. When the hybrid method is used, the deviations are decreasing with a factor from two to three, and are between 0.32%–0.42%. For more dense gas (), the deviations of the MC simulation results for the number density are found to be 1.71%, and the deviations of the hybrid MD–MC simulation results between 0.246% and 0.6977%. We discuss how these deviations in case of a dense gas () depend on the width of the interface, and we study it for the case when the MD domain is 10% and MC domain is 90% from the simulation domain, and also for the case when the MD domain is 50% and MC domain 50% from the whole simulation domain. For more dilute gas, the MC, MD and hybrid MC–MD simulations are in very good agreement and the deviations are negligible. [Copyright &y& Elsevier]

Insulation faults caused by corrosive sulfur contained in oil-paper insulation systems in transformers are a key factor affecting the safety and stable of operation of this critical equipment. To date, sulfur corrosion phenomena have been studied from an experimental point of view; however, little attention has been paid to the microscale mechanism of sulfur corrosion. On the basis of molecular dynamics simulations, we analyze the effects of hydrogen sulfide content on the mechanical and thermal properties of cellulose insulating paper in terms of hydrogen bonding, diffusion coefficients, mean square displacement, and mechanical parameters. The results of our kinetic simulations show that the mechanical properties of cellulose decrease as the content of hydrogen sulfide increases. At a hydrogen sulfide content of 8%, the elastic modulus of cellulose decreases by 33.1%, the volume modulus decreases by 46.4%, the shear modulus decreases by 37%, and the glass transition temperature decreases by 83 K. An increase of hydrogen sulfide content weakens interactions between cellulose chains, leading to increased chain motion, which thereby reduces the thermal stability of cellulose. The effects of hydrogen sulfide molecules on the mechanical and thermal properties of cellulose are mainly attributed to the formation of many hydrogen bonds between hydrogen sulfide molecules and cellulose, which destroy the original hydrogen bond network of the cellulose. At a high hydrogen sulfide content, van der Waals forces between cellulose molecules are weakened, lowering intermolecular interactions and reducing the thermal stability of the cellulose. • Hydrogen sulfide reduces the mechanical properties of cellulose. • Hydrogen sulfide increases the chain motion and reduces the thermal stability. • Hydrogen sulfide forms new hydrogen bonds and destroys the original bond network. [ABSTRACT FROM AUTHOR]

The dissociation of methane is not only an important reaction step in catalytic processes, but also of fundamental interest. Dynamical effects during the dissociative chemisorption of methane on metal surfaces cause significant differences in computed reaction rates, compared to what is predicted by typical transition state theory (TST) models. It is clear that for a good understanding of the catalytic activation of methane dynamical simulations are required. In this paper, a general blueprint is provided for performing dynamical simulations of the dissociative chemisorption of methane on metal surfaces, by employing either the quasi-classical trajectory or ring polymer molecular dynamics approach. If the computational setup is constructed with great care-since results can be affected considerably by the setup - chemically accurate predictions are achievable. Although this paper concerns methane dissociation, the provided blueprint is, so far, applicable to the dissociative chemisorption of most molecules. [ABSTRACT FROM AUTHOR]

In order to investigate the relationship between the molecular structure of fibers and the differences in physicochemical interactions between fibers and asphalt on the performance of fiber-modified asphalt, this paper chose two types of fibers with different chemical structures: straw fiber and polyester fiber. First, the differences in molecular interactions between the two fibers and asphalt were explored using molecular dynamics, then the differences in the adsorption capacity of the two fibers on asphalt components were tested by attenuated total reflection infrared spectroscopy experiments, and finally, the differences in the rheological properties of the two fiber-modified asphalts were tested by dynamic shear rheology and low-temperature creep experiments. The molecular dynamics simulation findings reveal that polyester fibers may intersperse into asphalt molecules and interact with them via structures such as aromatic rings, whereas straw fibers are merely adsorbed on the asphalt's surface. Straw fibers and asphalt exhibit hydrogen bonding, whereas polyester fibers and asphalt display van der Waals interactions. The results of attenuated total reflectance infrared spectroscopy indicated that polyester fiber absorbed asphalt components better than straw fiber. The rheological tests revealed that the polyester fiber had the highest complex shear modulus in the temperature range of 46–82 °C, and at 64 °C, the phase angle was 4.289° lower than that of the straw fiber-treated bitumen. Polyester fiber-modified asphalt had a 32.48%, 15.72%, and 6.09% lower creep modulus than straw fiber-modified asphalt at three low-temperature conditions: −6 °C, −12 °C, and −18 °C. It is clear that fibers with aromatic rings as a chemical structure outperform lignin-based fibers in terms of improving asphalt characteristics. The research findings can serve as a theoretical foundation for the selection of fibers to produce fiber-modified asphalt. [ABSTRACT FROM AUTHOR]

This study aims to assess the nanotribology research output at global level using scientometric tools. The SCOPUS database was used to retrieve records related to the nanotribology research for the period 1996–2010. Publications were counted on a fractional basis. The level of collaboration and its citation impact were examined. The performance of the most productive countries, institutes and most preferred journals is assessed. Various visualization tools such as the Sci2 tool and Ucinet were employed. The USA ranked top in terms of number of publications, citations per paper and h-index, while Switzerland published a higher percentage of international collaborative papers. The most productive institution was Tsinghua University followed by Ohio State University and Lanzhou Institute of Chemical Physics, CAS. The most preferred journals were Tribology Letters, Wear and Journal of Japanese Society of Tribologists. The result of author keywords analysis reveals that Molecular Dynamics, MEMS, Hard Disk and Diamond like Carbon are major research topics. [ABSTRACT FROM AUTHOR]

A comprehensive collection of papers citing the works of a leading theoretical molecular spectroscopist has been analyzed. Citations were collected in the period 1937-75, and classified by the following criteria: (a) cited in a 'cover-all' review; (b) cited among others; (c) cited extensively or as argumentation; (d) cited with some reservation; (e) cited with criticism; and (f) extensively used for further development. Results indicate a constant citation frequency within the entire period studied. It seems that the effect of the increase of publication output in this field is just about compensated for by the decay of the citation frequency. Citations of type a are uniformly spread over all papers, with an average of one citation every ten years. The ratio of types a + b to types c + d + e + f is not inconsistent with a value of about 1:2 - that is, citations to this author reflect considerable real impact. [ABSTRACT FROM AUTHOR]

The papers by Yang et al. [[5]] and Wang et al. [[6]] mainly studied the corrosion of CO SB 2 sb on gathering pipelines and the monitoring of the corrosion rate. The paper by Hou et al. [[1]] investigated the microscopic adsorption pattern of CH SB 4 sb and the competitive adsorption behavior of CH SB 4 sb and CO SB 2 sb in sodium-based montmorillonite using molecular simulation methods. The CO SB 2 sb pre-pad energized fracturing technology can not only further increase oil production, but also effectively realize the geological storage and utilization of CO SB 2 sb , thus greatly reducing the greenhouse effect. [Extracted from the article]