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An equation of state (EOS) explicit in Helmholtz free energy has been improved to calculate the PVTx and vapor–liquid phase equilibrium properties of CH 4 –CO 2 fluid mixture. This EOS, where four mixing parameters are used, is based on highly accurate EOSs recommended by NIST for pure components (CH 4 and CO 2 ) and contains a simple generalized departure function presented by Lemmon and Jacobsen (1999). Comparison with experimental data available indicates that the EOS can calculate both vapor–liquid phase equilibrium and volumetric properties of this binary fluid system with accuracy close to that of experimental data up to high temperature and pressure within full range of composition. The EOS of CH 4 –CO 2 fluid, together with the updated Gibbs free energy model of solid CO 2 (dry ice), is applied to calculate the CH 4 content ( x CH4 ) and molar volume ( V m ) of the CH 4 –CO 2 fluid inclusion based on the assumption that the volume of an inclusion keeps constant during heating and cooling. V m − x CH 4 diagrams are presented, which describe phase transitions involving vapor, liquid and CO 2 solid phases of CH 4 –CO 2 fluid inclusions. Isochores of CH 4 –CO 2 inclusions at given x CH 4 and V m can be easily calculated from the improved EOS. [ABSTRACT FROM AUTHOR]

Exploration of the application prospects of cattail fibers (CFs) in natural composites, and other fields is important for the sustainable development of new, green, light-weight, functional biomass materials. In this study, the physical and chemical properties, micro/nano structure, and mechanical characteristics of CFs were investigated. The CFs have a low density (618.0 kg m−3). The results of transmission electron microscopy and tensile testing data indicated that the cattail trunk fiber (CTF) bundle is composed of parenchyma cells and solid stone cells, demonstrating high specific modulus (10.1 MPa∙m3·kg−1) and high elongation at break (3.9%). In turn, the cattail branch fiber (CBF) bundle is composed of parenchyma cells with specific "half-honeycomb" shape. The inner diaphragms divide these cells into the open cavities. This structural feature endows the CTF bundles with stable structure, good oil absorption and storage capacities. The chemical component and the Fourier transform infrared spectroscopy analyses show that the CFs have higher lignin content (20.6%) and wax content (11.5%), which are conducive to the improvement of corrosion resistance, thermal stability and lipophilic–hydrophobic property of CF. Finally, the thermogravimetric analysis indicates that its final degradation temperature is 404.5 °C, which is beneficial to the increase in processability of CFs-reinforced composites. • The cattail fiber (CF) has lower density and multi-cavity structure. • Higher wax content endows CF with lipophilic-hydrophobic potential. • The cattail branch fiber (CBF) has "half-honeycomb" shape and inner diaphragms. • The CBF structural feature gives CF stable structure and good oil storage capacities. • The cattail trunk fiber bundles exhibit excellent mechanical properties. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the natural Luffa vine (LV) fiber to be effectively used as cellulose fiber reinforcing material for lightweight and decay-resistance composite materials. The physical, chemical, thermal, and morphological properties of the LV fibers, together with their microstructure are investigated. The test results conclude that the LV density, microscopic characteristics, and mechanical properties show that this crop is a lightweight (200–550 kg/m3) natural fiber with a porous structure and a high specific modulus (1.18–2.04 MPa∙ m3/kg). The chemical, X-ray diffraction and the Fourier transform infrared spectroscopy analyses indicate that the LV has a high lignin content (25.18%) and a relatively high relative crystallinity (37.18%) of cellulose, and it contains saponins, which increase its erosion resistance and hardness. The thermogravimetric analysis reveals that the fibers can stand up to 315.4 °C. Moreover, due to their kinetic activation energy of 63.9 kJ/mol, they can be used as reinforcement materials in thermoplastic green composites with a working temperature below 300°. • Luffa vine (LV) have a multi-level porous structure and a high specific modulus. • The presence of saponins help LV develop corrosion-resistant composites. • The LV lignin is mostly guajacyl lignin and only a small amount of syringyl lignin. • The LV thermal properties meet to a working temperature of composites below 300 °C. [ABSTRACT FROM AUTHOR]

Abstract: This work reports the application of thermodynamic models, including equations of state, to binary (salt-free) CH4–H2O fluid inclusions. A general method is presented to calculate the compositions of CH4–H2O inclusions using the phase volume fractions and dissolution temperatures of CH4 hydrate. To calculate the homogenization pressures and isolines of the CH4–H2O inclusions, an improved activity–fugacity model is developed to predict the vapor–liquid phase equilibrium. The phase equilibrium model can predict methane solubility in the liquid phase and water content in the vapor phase from 273 to 623K and from 1 to 1000bar (up to 2000bar for the liquid phase), within or close to experimental uncertainties. Compared to reliable experimental phase equilibrium data, the average deviation of the water content in the vapor phase and methane solubility in the liquid phase is 4.29% and 3.63%, respectively. In the near-critical region, the predicted composition deviations increase to over 10%. The vapor–liquid phase equilibrium model together with the updated volumetric model of homogenous (single-phase) CH4–H2O fluid mixtures (Mao S., Duan Z., Hu J. and Zhang D. (2010) A model for single-phase PVTx properties of CO2–CH4–C2H6–N2–H2O–NaCl fluid mixtures from 273 to 1273K and from 1 to 5000bar. Chem. Geol. 275, 148–160), is applied to calculate the isolines, homogenization pressures, homogenization volumes, and isochores at specified homogenization temperatures and compositions. Online calculation is on the website: http://www.geochem-model.org/. [Copyright &y& Elsevier]

Abstract: The IAPWS-95 formulation explicit in Helmholtz free energy proposed by Wagner and Pruß (The IAPWS formulation 1995 for the thermodynamic properties of ordinary water substance for general and scientific use, Journal of Physical and Chemical Reference Data 2002 31(2), 387–535) is extended to calculate the volumetric property of the fluid water from 1GPa and 273K to 20GPa and 4273K. Comparison with large experimental and molecular dynamic simulation data above 1GPa shows that the equation of state can reproduce the volume of the fluid water with an average absolute deviation of 0.52%. Thus the original IAPWS-95 formulation together with the extended part can be used in a much larger temperature–pressure region: 273–4273K and 0–20GPa. In addition, this paper also reports a reliable and highly efficient method to calculate the saturated properties of water so that the equation of state can be conveniently applied in the study of fluid inclusion: calculating homogenization pressures, homogenization densities (or molar volumes) and isochores. Computer code of the model can be obtained from the first author. [Copyright &y& Elsevier]

[Display omitted] • Two SA and FA cross-coupled dimers, SA-(β–O–4)-FA and α, β de-protonated SA-(β–5)-FA, were identified for the first time in vitro. • The yield of homo-coupled β–O–4 of SA was lower than 5%, which was overestimated in previous reports. • A tetrahydrofuran β–β coupled dehydrodimer of SA was discovered. During the lignification of grass cell walls, ferulate acts like a nucleation site that can cross couple with monolignols, i.e. coniferyl alcohol and sinapyl alcohol, to form dimeric products. Here we investigated in detail the ferulate-sinapyl alcohol cross-coupling products in an effort on better understanding the nature and scope of lignin-ferulate interactions. In a biomimetic oxidative system, sinapyl alcohol (SA) reacted with ethyl ferulate (FA), a simplified model for feruloyl polysaccharides in plants, to give a mixture of dozens of dimeric products. We delineated the structure of each product by GC-MS and NMR characterizations. It was found that sinapyl alcohol readily reacts with ethyl ferulate producing various cross-coupled dimers including SA-(β–5)-FA (compound 6), SA-(β–8)-FA (both ester and lactones, compounds 7 and 9), and SA-(β–O–4)-FA (compound 8) cross-coupled products in addition to homo-coupled products from ethyl ferulate or sinapyl alcohol. SA-(β–O–4)-FA 8 was identified for the first time in a vitro free radical biomimetic system and the homo-coupled SA-(β–O–4)-SA 3 from sinapyl alcohol was accurately quantified as less than 5%, while the half-open syringaresinol 5 was discovered when dimerization of SA was catalyzed by peroxidase in a biomimetic buffer system. Moreover, one new compound 18 formed by the cross-coupled linkage SA-(β–5)-FA (de-protonated) was identified by GC-MS and NMR, and one possible FA-(8–β)-SA dimer 19* was proposed. [ABSTRACT FROM AUTHOR]

• Luffa vine (LV) is a low-density natural plant fiber with a porous structure. • The secondary wall of LV fiber cell contains two layers with spiral thickening. • Sclerenchyma cell of LV exhibits excellent micromechanical properties. • The microscopic characteristics endow LV with good processability. • The pit pairs on cell walls provide good permeability to LV fibers. The exploration of luffa vine (LV) in the polymer composites field can contribute to the development of lightweight composites and expand their use in new wide scale applications. In this study, the physical and chemical properties and the microstructure of the LV fibers were investigated by various techniques. The results of LV density and microscopic characteristics indicated that this crop is a lightweight (with density mainly concentrated in 0.30–0.45 g cm−3) natural fiber with a porous structure (the ratio of wall to lumen: 0.2–0.3). Transmission electron microscopy and nanoindentation analyses showed that the secondary wall of the LV sclerenchyma cell is made up of two layers with spiral thickening and exhibiting a high nanoindentation modulus (7.8–10.4 GPa) and a high nanoindentation hardness (0.40–0.58 GPa). The chemical composition and X-ray diffraction analysis indicated that the LV has high lignin content (20–25%) and a relatively high relative crystallinity index of cellulose, which are conducive to increase the hardness of the LV fiber. Moreover, microscopic characteristics analysis also revealed that the LV fiber cells have a relatively high aspect ratio (30.3), there are pit pairs on the LV fiber cell walls, and the core fiber cells of the LV have relatively high flexibility coefficient (0.8), which are beneficial to increase the processability of composite materials with the LV fibers as reinforcement. [ABSTRACT FROM AUTHOR]

Sulfide-silicate melt partitioning controls the behavior of gold in magmas, which is critical for understanding the Earth's deep gold cycle and formation of gold deposits. However, the mechanisms that control the sulfide-silicate melt partitioning of gold remain largely unknown. Here we present constraints from laboratory experiments on the partition coefficient of gold between monosulfide-solid-solution (MSS) and silicate melt (D A u M S S / S M) under conditions relevant for magmatism at subduction settings. Thirty-five experiments were performed in Au capsules to determine D A u M S S / S M at 950-1050 °C, 0.5-3 GPa, oxygen fugacity (f O 2) of ∼FMQ-1.7 to FMQ+2.7 (FMQ refers to the fayalite-magnetite-quartz buffer), and sulfur fugacity (f S 2) of −2.2 to 2.1, using a piston cylinder apparatus. The silicate melt composition changes from dry to hydrous andesite to rhyolite. The results obtained from electron microprobe and laser-ablation ICP-MS analyses show that the gold solubility in silicate melts ranges from 0.01 to 55.3 ppm and is strongly correlated with the melt sulfur content [S] melt at f O 2 of ∼FMQ-1.7 to FMQ+1.6, which can be explained by the formation of complex Au-S species in the silicate melts. The gold solubility in MSS ranges from 130 to 2800 ppm, which is mainly controlled by f S 2. D A u M S S / S M ranges from 10 to 14000 at f O 2 of ∼FMQ-1.7 to FMQ+1.6, the large variation of which can be fully explained by combined [S] melt and f S 2. Therefore, all of the parameters that can directly affect [S] melt and f S 2 , such as alkali metals, water, FeO, and f O 2 , can indirectly affect D A u M S S / S M. The mechanisms that control the sulfide-silicate melt partitioning of gold and the other chalcophile elements, such as Ni, Re, and Mo, differ significantly. This is because gold is dissolved mainly as Au-S species in the silicate melts, while the other chalcophile elements are dissolved mainly as metal oxides in the silicate melts. Applying the correlation between D A u M S S / S M and [S] melt to slab melting and arc magmatic differentiation under different redox conditions, we find that ancient to modern slab melts carry negligible to less than 25% of the slab gold to the subarc mantle; however, gold-enrichment can occur in MSS-saturated arc magmas that have differentiated under moderately oxidized conditions with f O 2 between FMQ and FMQ+1.6, in particular if the magmatic crystallization follows a fractional crystallization model. We conclude that moderately oxidized magmas with high contents of alkali metals, sulfur, and water, owing to their low D A u M S S / S M and efficient magma-to-fluid transfer of gold and sulfur, have a high potential to form gold deposits. • MSS/silicate melt partition coefficient for Au (D A u M S S / S M) ranges from 10 to 14000. • D A u M S S / S M is a strong function of the melt sulfur content and sulfur fugacity. • Slab melts carry negligible to less than 25% of slab Au to the mantle wedge. • Au-enrichment can occur in MSS-saturated, moderately oxidized arc magmas. • Moderately oxidized, hydrous alkaline magmas have a high Au ore-forming potential. [ABSTRACT FROM AUTHOR]