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

Exergy Analysis of Alternative Configurations of Biomass-Based Light Olefin Production System with a Combined-Cycle Scheme via Methanol Intermediate

Thermodynamic performance of three conceptual systems for biomass-derived olefin production with electricity cogeneration was studied and compared via exergy analysis at the levels of system, subsystem and operation unit. The base case was composed of the subsystems of gasification, raw fuel gas adjustment, methanol/light olefin synthesis and steam & power generation, etc. The power case and fuel case were designed as the combustion of a fraction of gasification gas to increase power generation and the recycle of a fraction of synthesis tail gas to increase olefin production, respectively. It was found that the subsystems of gasification and steam & power generation contribute ca. 80% of overall exergy destruction for each case, of which gasifier and combustor are the main exergy destruction sources, due to the corresponding chemical exergy degrading of biomass and fuel gas. The low efficiency of 33.1% for the power case could be attributed to the significant irreversibility of the combustor, economizer, and condenser in the combined-cycle subsystem. The effect of the tail gas recycle ratio, moisture content of feedstock, and biomass type was also investigated to enhance system exergy performance, which could be achieved by high recycle ratio, using dry biomass and the feedstock with high carbon content. High system efficiency of 38.9% was obtained when oil palm shell was used, which was 31.7% for rice husk due to its low carbon content

碱性离子液体催化合成三羟甲基丙烷

以碱性离子液体为催化剂，构建了一种新型、高效的合成三羟甲基丙烷（TMP）的方法．系统考察了催化剂类型、催化剂用量、反应温度、反应时间、甲醛与正丁醛用量比等因素对三羟甲基丙烷分离收率的影响．研究结果表明：碱性离子液体的催化性能与其碱强度息息相关，碱性越强、催化活性越高．最优条件下，经离子液体bmimOH催化后，可得到84％的TMP分离收率。这一结果优于传统的有机无机碱催化体系且成功规避了传统碱催化合成TMP过程中繁琐的除盐过程、降低了过程能耗．此外，离子液体催化剂和未反应的丁醛均表现了良好的重复使用性能

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

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

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