Strain Phase Separation: Formation of Ferroelastic Domain Structures

Phase decomposition is a well-known process leading to the formation of two-phase mixtures. Here we show that a strain imposed on a ferroelastic crystal promotes the formation of mixed phases and domains, i.e., strain phase separation with local strains determined by a common tangent construction on the free energy versus strain curves. It is demonstrated that a domain structure can be understood using the concepts of domain/phase rule, lever rule, and coherent and incoherent strain phase separation, in a complete analogy to phase decomposition. The proposed strain phase separation model is validated using phase-field simulations and experimental observations of PbTiO3 and BiFeO3 thin films as examples. The proposed model provides a simple tool to guide and design domain structures of ferroelastic systems

Preliminary Characterization of Underground Hydrological Processes under Multiple Rainfall Conditions and Rocky Desertification Degrees in Karst Regions of Southwest China

Karst regions are widely distributed in Southwest China and due to the complexity of their geologic structure, it is very challenging to collect data useful to provide a better understanding of surface, underground and fissure flows, needed to calibrate and validate numerical models. Without characterizing these features, it is very problematic to fully establish rainfall–runoff processes associated with soil loss in karst landscapes. Water infiltrated rapidly to the underground in rocky desertification areas. To fill this gap, this experimental work was completed to preliminarily determine the output characteristics of subsurface and underground fissure flows and their relationships with rainfall intensities (30 mm h−1, 60 mm h−1 and 90 mm h−1) and bedrock degrees (30%, 40% and 50%), as well as the role of underground fissure flow in the near-surface rainfall–runoff process. Results indicated that under light rainfall conditions (30 mm h−1), the hydrological processes observed were typical of Dunne overland flows; however, under moderate (60 mm h−1) and high rainfall conditions (90 mm h−1), hydrological processes were typical of Horton overland flows. Furthermore, results confirmed that the generation of underground runoff for moderate rocky desertification (MRD) and severe rocky desertification (SRD) happened 18.18% and 45.45% later than the timing recorded for the light rocky desertification (LRD) scenario. Additionally, results established that the maximum rate of underground runoff increased with the increase of bedrock degrees and the amount of cumulative underground runoff measured under different rocky desertification was SRD > MRD > LRD. In terms of flow characterization, for the LRD configuration under light rainfall intensity the underground runoff was mainly associated with soil water, which was accounting for about 85%–95%. However, under moderate and high rainfall intensities, the underground flow was mainly generated from fissure flow

Amine Dynamics in Diamine-Appended Mg2(dobpdc) Metal-Organic Frameworks.

Variable-temperature 15N solid-state NMR spectroscopy is used to uncover the dynamics of three diamines appended to the metal-organic framework Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate), an important family of CO2 capture materials. The results imply both bound and free amine nitrogen environments exist when diamines are coordinated to the framework open Mg2+ sites. There are rapid exchanges between two nitrogen environments for all three diamines, the rates and energetics of which are quantified by 15N solid-state NMR data and corroborated by density functional theory calculations and molecular dynamics simulations. The activation energy for the exchange provides a measure of the metal-amine bond strength. The unexpected negative correlation between the metal-amine bond strength and CO2 adsorption step pressure reveals that metal-amine bond strength is not the only important factor in determining the CO2 adsorption properties of diamine-appended Mg2(dobpdc) metal-organic frameworks

Efficient base-catalyzed decomposition and in situ hydrogenolysis process for lignin depolymerization and char elimination

Serious char formation caused by the repolymerization of unsaturated decomposition products is a considerable challenge for current lignin utilization. Here, a novel and efficient base-catalyzed depolymerization and in situ hydrogenolysis process for lignin decomposition and char elimination was proposed using the synergic catalyst of NaOH coordinated with Ru/C. In which, lignin was first depolymerized to phenolic monomer and its oligomer, and then the oligomer was further converted to more stable aliphatic alcohols simultaneously. The results showed that more than 92.5% of lignin was converted, giving 12.69% phenolic monomer, 6.12% aliphatic alcohol and less than 14.03% residual solid. This residual solid selectivity was far lower than it from the single catalyst condition. Furthermore, the products were analyzed using GC-MS, GPC, HPLC-MS and H-1 NMR. The synergistic effect between depolymerization and hydrogenolysis was also investigated through comparative analysis of the feed-stock, products, and the recovered lignin. (C) 2014 Elsevier Ltd. All rights reserved

Catalytic Conversion of Lignocellulose into Energy Platform Chemicals

With the shortage of fossil fuels and the concerns related to their environmental impact and greenhouse gas effect, extensive research and development programs have been initiated worldwide to convert biomass into valuable products for future biofuels and chemicals. The conversion of lignocellulose into platform chemicals has attracted more attention in recent years. During this process, cellulose and hemicellulose can be high selectively converted into soluble sugars in the presence of catalysts, and the soluble sugars are subsequently converted into widely used platform molecules, such as furan-based chemicals, polyols, organic acid and its ester derivatives. These platform molecules can be further refined into high value-added liquid hydrocarbon fuels through elementary reactions, which are important alternatives to fossil fuel. The catalysts used for the transformation of lignocellulose into various platform chemicals mainly include liquid acid, solid acid, ion liquid and multifunctional materials, which play an important role in the catalytic process. Based on the present research situation, this review provides new insights into the accomplishments in recent years in the chemocatalytic technologies to generate energy platform chemicals from lignocellulosic biomass, with an emphasis on various kinds of catalytic routes and their existing problems and possible solutions. Finally, the future research and development trend in the field is prospected

Process intensification effect of ball milling on the hydrothermal pretreatment for corn straw enzymolysis

Enhancement of the cellulose accessibility is significant for biomass enzymatic hydrolysis. Here, we reported an efficient combined pretreatment for corn straw enzymolysis using ball milling and dilute acid hydrothermal method (a mixture solvent of H2O/ethanol/sulfuric acid/hydrogen peroxide liquid). The process intensification effect of ball milling on the pretreatment of the corn straw was studied through the comparative characterization of the physical-chemical properties of the raw and pretreated corn straw using FT-IR, BET, XRD, SEM, and HPLC analysis. The effect of the pretreatment temperature was also investigated. Furthermore, various pretreatment methods were compared as well. Moreover, the pretreatment performance was measured by enzymolysis. The results showed that ball milling had a significant process intensification effect on the corn straw enzymolysis. The glucose concentration was dramatically increased from 0.41 to 13.86 mg mL(-1) after the combined treatment of ball milling and hydrothermal. The efficient removal of lignin and hemicellulose and the enlargement of the surface area were considered to be responsible for this significant increase based on the intensive analysis on the main components and the physical-chemical properties of the raw and pretreated corn straw. (C) 2015 Elsevier Ltd. All rights reserved

Intensification effect of peroxide hydrogen on the complete dissolution of lignocellulose under mild conditions

Lignocellulose is generally resistant to dissolving in water and conventional organic solvents, which significantly hinders its efficient utilization. In this work, we provide a novel and efficient technology on lignocellulose dissolution under mild conditions for down-stream conversion with heterogeneous catalysts. In a mixture of hydrogen peroxide, sulfuric acid, ethanol and water, corn straw was completely dissolved in the mixture at 170 degrees C for 120 min without significant volatile chemical production (less than 16%). Cellulose and hemicellulose existed as water-soluble oligosaccharides in the solvent, which were more easily converted than the original polymeric carbohydrate. During the dissolved process, peroxide hydrogen exhibited a significant intensification effect on dissolving the hemicellulose, decrystallization of cellulose and delignification with sulfuric acid. Furthermore, lignin was destroyed into fragments in the course of dissolution, which had a looser structure and lower molecular weight

cascadeenzymatichydrolysiscouplingwithultrafinegrindingpretreatmentforsugarcanebagassesaccharification

The biorefinery process for sugarcane bagasse saccharification generally requires significant accessibility of cellulose. We reported a novel method of cascade cellulase enzymatic hydrolysis coupling with ultrafine grinding pretreatment for sugarcane bagasse saccharification. Three enzymatic hydrolysis modes including single cellulase enzymatic hydrolysis, mixed cellulase enzymatic hydrolysis, and cascade cellulase enzymatic hydrolysis were compared. The changes on the functional group and surface morphology of bagasse during cascade cellulase enzymatic hydrolysis were also examined by FT-IR and SEM respectively. The results showed that cascade enzymatic hydrolysis was the most efficient way to enhance the sugarcane bagasse saccharification. More than 65% of reducing sugar yield with 90.1% of glucose selectivity was achieved at 50 degrees C, pH=4.8 for 72 h (1200 r/min) with cellulase I of 7.5 FPU/g substrate and cellulase II of 5 FPU/g substrate

Production of Hydrocarbons via Hydrodeoxygenation of Lignin-Derived Phenolic Compounds

Lignin is the component with the highest carbon content in biomass. The transformation of lignin to high-grade liquid fuels can be achieved via hydrodeoxygenation(HDO) of phenolic intermediates derived from the products of lignin depolymerization. The octane numbers of the hydrodeoxygenation products of phenolic intermediates are quite high. They have vapor pressures and carbon atom number (C6 similar to C10) within the range of gasoline. Thus, these hydrodeoxygenation products would be the most desirable components for a fungible liquid transportation fuel. This is very meaningful to application of lignin. Recently, researches about the hydrodeoxygenation of phenolic compounds develop rapidly. In this paper, the HDO reactions of phenolic compounds using sulfided Mo-based catalyst, noble metal catalyst and inexpensive non-sulfided catalyst are reviewed in detail. It is found that most of the investigated catalysts are bifunctional catalysts, combining the hydrogenation function of active metal with hydrolysis and dehydration of support. The catalytic mechanism for the HDO of phenolic compounds is sketched, and the effects of catalyst supporter on the catalytic activity are also discussed. Furthermore, the current technique challenges are summarized, and future technologic explorations for the efficient hydrodeoxygenation of lignin-derived phenolic compounds are proposed