Kinetics of Non-catalyzed Decomposition of D-xylose in High Temperature Liquid Water

The kinetics of non-catalyzed decompositions of xylose and its decomposition product furfural in high temperature liquid water （HTLW） was studied for temperature from 180 to 220℃ and under pressure of 10MPa. The main products of xylose decomposition were furfural and formic acid, and furfural further degraded to formic acid under HTLW condition. With the assumption of first order kinetics e.quation, the evaluated activation energy of xylose and furfural decomposition was 123.27kJ·mol^-1 and 58.84kJ·mol^-1, respectively.

Kinetics of non-catalyzed hydrolysis of tannin in high temperature liquid water

High temperature liquid water(HTLW) has drawn increasing attention as an environmentally benign medium for organic chemical reactions,especially acid-/base-catalyzed reactions. Non-catalyzed hydrolyses of gallotannin and tara tannin in HTLW for the simultaneous preparation of gallic acid(GA) and pyrogallol(PY) are under investigation in our laboratory. In this study,the hydrolysis kinetics of gallotannin and tara tannin were determined. The reaction is indicated to be a typical consecutive first-order one in which GA has formed as a main intermediate and PY as the final product. Selective decomposition of tannin in HTLW was proved to be possible by adjusting reaction temperature and time. The present results provide an important basic data and reference for the green preparation of GA and PY.

Dissolution of Konjac Glucomannan with Room Temperature Ionic Liquids

Two kinds of new room temperature ionic liquids （RTILs）, 1-allyl-3-methylimidazolium chloride （AMIMCl） and 1-butyl-3-methylimidazolium chloride （BMIMCl）, were synthesized and used for the dissolution of konjac glucomannan （KGM）. The experimental results showed that the solubility of KGM in AMIMCl was better than that in BMIMCl. Regenerated KGM were obtained by adding anhydrous alcohol to the KGM / ionic liquids solutions. Solubility, molecular weight, structure, and thermal property of the regenerated KGM were investigated by polarized optical microscopy （POM）, viscosimetry, infrared spectroscopy （IR）, X-ray diffraction technique （XRD）, thermogravimetry （TG） and differential scanning calorimetry （DSC）. It was demonstrated that the viscosity-averaged molecular weight of the KGM samples decreased after regeneration because of the molecular degradation of KGM. Results from IR and XRD indicated that the chemical structure and the crystalline form of regenerated KGM were not changed. Results from TG and DSC showed that the thermal stability of the regenerated KGM samples only slightly decreased. These results suggest that AMIMCl and BMIMCl are direct and effective solvents for KGM.

Substitution Reactions by Azide and Thiocyanide Anions in Room Temperature Ionic Liquids

Conducted in the ionic liquids, activated and inactivated halides, acyl chlorides, tosylate, and bezotriazolyl acylates were converted to corresponding azide and thiocyanide compounds in high yields under mild conditions.

Enhanced Acid/Base Catalysis in High Temperature Liquid Water

Two novel and environmentally benign solvent systems, organic acids-ennchea high temperature liquid water （HTLW） and NH3-enriched HTLW, were developed, which can enhance the reaction rate of acid/base-catalyzed organic reactions in HTLW. We investigated the decomposition of fructose in organic acids-enriched HTLW, hydrolysis of cinnamaldehyde and aldol condensation of phenylaldehyde with acetaldehyde in NH3-enriched HTLW. The experimental results demonstrated that organic acids-enriched or NH3-enriched HTLW can greatly accelerate acid/base-catalyzed organic reactions in HTLW.

An Experimental Study on the Drag Property of High-Temperature Particles Falling into Cold Liquid Pool

This experiment is to study the special resistant induced by the high-speed evaporation surrounding themoving high-temperature particles. An observable equipment was designed, in which the first 11 experiments wereperformed by pouring one or several Zirconia spheres with various high-temperature and a diameter of 3～ 10 mminto a water pool. The particles falling-down speeds were recorded by high-speed photographic instrumentation,and pressures and water temperatures were measured. A comparison between the experiments with cold and hotspheres respectively, employing three different sphere types each, was presented. The experimental data, com-pared with the theory of the evaporation drag model, are nearly identical.

Synthesis of multi-hydroxyl and sulfonyl dual-functionalized room temperature ionic liquids

Starting from the hydroxylamine (dimethyl amino ethanol, triethanolamine) and 1,3-propane sultone, a series of hydroxyl and sulfonyl dual-functionalized zwitterionic salts and corresponding acidic room temperature ionic liquids have been synthesized. The hydroxyl groups of the synthesized substances were confirmed by the 1H NMR measurement. These zwitterionic salts and ionic liquids may be used for synthesizing other functionalized ionic liquids or ionic liquid-polymer (polyelectrolyte).

Effects of water on the structure and transport properties of room temperature ionic liquids and concentrated electrolyte solutions

Transport properties and the associated structural heterogeneity of room temperature aqueous ionic liquids and especially of super-concentrated electrolyte aqueous solutions have received increasing attention,due to their potential application in ionic battery.This paper briefly reviews the results reported mainly since 2010 about the liquid-liquid separation,aggregation of polar and apolar domains in neat RTILs,and solvent clusters and 3D networks chiefly constructed by anions in super-concentrated electrolyte solutions.At the same time,the dominating effect of desolvation process of metal ions at electrode/electrolyte interface upon the transport of metal ions is stressed.This paper also presents the current understanding of how water affects the anion-cation interaction,structural heterogeneities,the structure of primary coordination sheath of metal ions and consequently their transport properties in free water-poor electrolytes.

Molecular dynamics study of room temperature ionic liquids with water at mica surface

Water in room temperature ionic liquids(RTILs) could impose significant effects on their interfacial properties at a charged surface. Although the interfaces between RTILs and mica surfaces exhibit rich microstructure, the influence of water content on such interfaces is little understood,in particular, considering the fact that RTILs are always associated with water due to their hygroscopicity. In this work, we studied how different types of RTILs and different amounts of water molecules affect the RTIL-mica interfaces, especially the water distribution at mica surfaces,using molecular dynamics(MD) simulation. MD results showed that(1) there is more water and a thicker water layer adsorbed on the mica surface as the water content increases, and correspondingly the average location of K^+ ions is farther from mica surface;(2) more water accumulated at the interface with the hydrophobic [Emim][TFSI] than in case of the hydrophilic [Emim][BF4] due to the respective RTIL hydrophobicity and ion size. A similar trend was also observed in the hydrogen bonds formed between water molecules. Moreover, the 2D number density map of adsorbed water revealed that the high-density areas of water seem to be related to K^+ ions and silicon/aluminum atoms on mica surface. These results are of great importance to understand the effects of hydrophobicity/hydrophicility of RTIL and water on the interfacial microstructure at electrified surfaces.

Impedance Spectroscopic Study on Room Temperature Ionic Liquid-Water Mixtures

AC impedance spectroscopy in pure room temperature ionic liquids （RTILs） and RTIL-water mixture was measured at the temperature of range from 30 ℃ down to -30 ℃. The cations of RTILs are N,N-diethyl-N-methyl-N-（2-methoxyethyl） ammonium （[DEME]）, 1-ethyl-3-methylimidazolium （[C2mim]） and l-butyl-3-methylimidazolium （[Camim]）, the anions are tetrafluoroborate （[BF4]） and bis（trifluoromethanesulfonyl）imide （[TFSI]）. In all pure RTILs, there are two kinds of local minima in real part of the AC impedance Zreal. By adding water to [DEME][BF4] （0 mol% 〈 x 〈 94 mol%） at room temperature, the local minimum value at higher frequency decreased remarkably at the fixed frequency with increasing water concentration. Above 94 mol% H20, a quite different profile of the AC impedance spectroscopy was obtained. In addition to Zreal. temperature dependence of an imaginary part of the impedance Zimag had an isosbestic point below 94 mol%. The isosbestic point disappeared above 94 mol%. The isosbestic point in Zing reveals an interaction between [DEME][BFa] and H2O.

CO2 Capture at Room Temperature and Ambient Pressure: Isomer Effect in Room Temperature Ionic Liquid/Propanol Solutions

A CO2 capture system without supercritical CO2 was optimized for mixtures of hydrophobic room temperature ionic liquids (RTILs) and propanol. We tested RTILs using bis(trifluoromethanesulfonyl)imide, TFSI-, anion and four quaternary ammonium cations, two quaternary phosphonium cations, and one imidazolium cation. The addition of 2-propanol into the RTILs clearly promoted the capture of normal CO2(nCO2) at ambient temperature and pressure. When combined with 2-propanol, the most efficient RTILs for nCO2 capture were N-butyl-N,N,N-trimethylammonium TFSI-. This enhancement of nCO2 capture was not observed in RTIL mixtures with 1-propanol or in propanol mixtures containing other phosphonium- and imidazolium-based RTILs. The torsion angle of TFSI-, which was calculated using density functional theory, is thought to be related to high nCO2 capture efficiently.

TEMPERATURE DEPENDENCE OF AIR SEPARATION OF LIQUID CRYSTALLINE TRIHEPTYL CELLULOSE/ETHYL CELLULOSE MEMBRANES

Triheptyl cellulose/ethyl cellulose(3/97)binary blend membranes were prepared from tetrahydrofuran,chloroform and dichloromethane solutions and their air separation capabit- ities were studied at different temperatures.With increasing temperature from 25 to 85℃,the flux QOEA of O_2-enriched air(OEA),O_2 permselectivity and the O_2 concentration Yo_2 in the OEA all increase.The membranes show a unique trend in their Yo_2～QOEA relationship,that is,the air separation capability increases simultaneously with the OEA permeation capability.The magnitudes of QOEA and Yo_2 for 17μm-thick membrane after the testg time of 36hours at 70℃ are 5×10^(-4)cm^3 (STP)/s·cm^2 and 37.6%,respectively.The air separation capability depends slightly on membrane forming solvents.

Phase-Transitions at High, Very High, and Very Low Temperatures upon Nano-Indentations: Onset Forces and Transition Energies

This paper describes the phase-transition energies from published loading curves on the basis of the physically deduced FN = k-h3/2 law that does not violate the energy law by assuming h2 instead, as still do ISO-ASTM 14,577 standards. This law is valid for all materials and all “one-point indentation” temperatures. It detects initial surface effects and phase-transition kink-unsteadiness. Why is that important? The mechanically induced phase-transitions form polymorph interfaces with increased risk of crash nucleation for example at the pickle forks of airliners. After our published crashing risk, as nucleated within microscopic polymorph-interfaces via pre-cracks, had finally appeared (we presented microscopic images (5000×) from a model system), 550 airliners were all at once grounded for 18 months due to such microscopic pre-cracks at their pickle forks (connection device for wing to body). These pre-cracks at phase-transition interfaces were previously not complained at the (semi)yearlycheckups of all airliners. But materials with higher compliance against phase- transitions must be developed for everybody’s safety, most easily by checking with nanoindentations, using their physically correct analyses. Unfortunately, non-physical analyses, as based on the after all incredible exponent 2 on h for the FN versus h loading curve are still enforced by ISO-ASTM standards that cannot detect phase-transitions. These standards propagate that all of the force, as applied to the penetrating cone or pyramid shall be used for the depth formation, but not also in part for the pressure to the indenter environment. However, the remaining part of pressure (that was not consumed for migrations, etc.) is always used for the elastic modulus detection routine. That severely violates the energy-law! Furthermore, the now physically analyzed published loading curves contain the phase-transition onsets and energies information, because these old-fashioned authors innocently (?) published (of course correct) experimental loading curves. These follow as ever the physically deduced FN = k-h3/2 relation that does not violate the energy law. Nevertheless, the old-fashioned authors stubbornly assume h2instead of h3/2 as still do ISO-ASTM 14,577 standards according to an Oliver-Pharr publication of 1992 and textbooks. The present work contributes to understanding the temperature dependence of phase-transitions under mechanical load, not only for aviation and space flights, which is important. The physical calculations use exclusively regressions and pure algebra (no iterations, no fittings, and no simulations) in a series of straightforward steps by correcting for unavoidable initial effects from the axis cuts of the linear branches from the above equation exhibiting sharp kink unsteadiness at the onset of phase transitions. The test loading curves are from Molybdenum and Al 7075 alloy. The valid published loading curves strictly follow the FN = k-h3/2 relation. Full applied work, conversion work, and conversion work per depth unit show reliable overall comparable order of magnitude values at temperature increase by 150°C (Al 7075) and 980°C (Mo) when also considering different physical hardnesses and penetration depths. It turns out how much the normalized endothermic phase-transition energy decreases upon temperature increase. For the only known 1000°C indentation we provide reason that the presented loading curves changes are only to a minor degree caused by the thermal expansion. The results with Al 7075 up to 170°C are successfully compared. Al 7075 alloy is also checked by indentation with liquid nitrogen cooling (77 K). It gives two endothermic and one very prominent exothermic phase transition with particularly high normalized phase-transition energy. This indentation loading curve at liquid nitrogen temperature reveals epochal novelties. The energy requiring endothermic phase transitions (already seen at 20°C and above) at 77 K is shortly after the start of the second polymorph (sharply at 19.53 N loading force) followed by a strongly exothermic phase-transition by producing (that is losing) energy-content. Both processes at 77 K are totally unexpected. The produced energy per depth unit is much higher energy than the one required for the previous endothermic conversions. This exothermic phase-transition profits from the inability to provide further energy for the formation of the third polymorph as endothermic obtained at 70°C and above. That is only possible because the very cold crystal can no longer support endothermic events but supports exothermic ones. Both endothermic and exothermic phase-transitions at 77 K under load are unprecedented and were not expected before. While the energetic support at 77 K for endothermic processes under mechanical load is unusual but still understandable (there are also further means to produce lower temperatures). But strongly exothermicphase-transition under mechanical load for the production of new modification with negative energy content (less than the energy content of the ambient polymorph) at very low temperature is an epochal event here on earth. It leads to new global thinking and promises important new applications. The energy content of strongly exothermic transformed material is less than the thermodynamic standard zero energy-content on earth. And it can only be reached when there is no possibility left to produce an endothermic phase-transition. Such less than zero-energy-content materials should be isolated, using appropriate equipment. Their properties must be investigated by chemists, crystallographers, and physicists for cosmological reasons. It could be that such materials will require cooling despite their low energy content (higher stability!) and not survive at ambient temperatures and pressures on earth, but only because we do not know of such negative-energy-content materials with our arbitrary thermodynamic standard zeros on earth. At first one will have to study how far we can go up with temperature for keeping them stable. Thus, the apparently never before considered unprecedented result opens up new thinking for the search of new polymorphs that can, of course, not be reached by heating. Various further applications including cosmology and space flight explorations are profiting from it.

Synthesis of 2-Arylimidazo[l, 2-a]pyrimidines in Ionic Liquids

Room temperature ionic liquids were used as a "green" recyclable alternative to conventional solvents in the synthesis of pharmaceutically useful compounds 2-arylimidazo[1, 2-a] pyrimidines through Tschotschibabin reaction of a-bromoacetophenones with 2-aminopyrimidine in good yields.

Metal organic framework‐ionic liquid hybrid catalysts for the selective electrochemical reduction of CO_(2) to CH4

The electrochemical reduction of CO_(2) towards hydrocarbons is a promising technology that can utilize CO_(2) and prevent its atmospheric accumulation while simultaneously storing renewable en‐ergy.However,current CO_(2) electrolyzers remain impractical on a large scale due to the low current densities and faradaic efficiencies(FE)on various electrocatalysts.In this study,hybrid HKUST‐1 metal‐organic framework‒fluorinated imidazolium‐based room temperature ionic liquid(RTIL)electrocatalysts are designed to selectively reduce CO_(2) to CH_(4).An impressive FE of 65.5%towards CH_(4) at-1.13 V is achieved for the HKUST‐1/[BMIM][PF_(6)]hybrid,with a stable FE greater than 50%maintained for at least 9 h in an H‐cell.The observed improvements are attributed to the increased local CO_(2) concentration and the improved CO_(2)‐to‐CH_(4) thermodynamics in the presence of the RTIL molecules adsorbed on the HKUST‐1‐derived Cu clusters.These findings offer a novel approach of immobilizing RTIL co‐catalysts within porous frameworks for CO_(2) electroreduction applications.

Experimental study on freezing of liquids under static magnetic field

Freezing processes of several liquids under static magnetic field(SMF) less than 50 mT were investigated. Central temperature of liquid samples held in glass test tubes immersed in a liquid bath was measured and collected. Nucleation temperature and phase transition time were obtained from freezing curves. Normality tests were performed for nucleation temperature of these liquids with/without magnetic field and normality distributions were justified. Analysis of variances was carried out for nucleation temperature of these liquids with magnetic field flux density as the influencing factor. Results showed that no significant difference was found for deionized water with or without SMF. However, differences exist in 0.9% NaCl solution and 5% ethylene glycol solution with and without SMF. Nucleation temperature of 0.9% NaCl with SMF is lower than that without SMF, while its phase transition time is shorter than that without SMF. Nucleation temperature of 5% ethylene glycol with SMF is higher than that without SMF, while its phase transition time is not modified with SMF.

Effect of ionic liquids on stability of O/W miniemulsion for application of low emission coating products

Room temperature ionic liquids(RTILs) are non-volatile organic salts. They may replace conventional coalescing agents in latex coating thus reducing volatile organic compounds(VOCs) emission as well as improving performance of latex coating products such as better thermal stability, conductivity, and antifouling property. The formation of latex coating containing RTILs can be achieved by encapsulation of RTILs inside particles via miniemulsion polymerization. In this study, the role of RTILs and its concentration on stability of miniemulsion during storage and polymerization were investigated. It has been found that, above a critical concentration(10 wt%), adding more RTILs to oil phase may weaken miniemulsion stability during storage as well as polymerization. Such observations were consistent with the zeta potential measurement for miniemulsions prepared at the similar conditions. The results obtained here would be a useful guideline for the development of new waterborne coating products with desirable functions and particle sizes.

Fatigue behaviors and damage mechanisms for Nb_(3)Sn triple-helical structure at liquid nitrogen temperature

Nb_(3)Sn triple‐helical structure is the elementary structure in the superconducting cable of ITER magnets and undergoes prolonged fatigue loading in extreme environments leading to serious damage degradation.In this paper,the fatigue behaviors of the Nb_(3)Sn triple‐helical structure have been investigated by the strain cycling fatigue experiments at liquid nitrogen temperature.The results indicate that Nb_(3)Sn triple‐helical structures with short twist‐pitches possess excellent fatigue damage resistance than that of long twist‐pitches,such as longer fatigue life,slower damage degradation,and smaller energy dissipation.Meanwhile,a theoretical model of damage evolution has been established to reveal the effects of twist‐pitches on fatigue properties for triplehelical structures,which is also validated by the present experimental data.Furthermore,one can see that the Nb_(3)Sn superconducting wires in a triple‐helical structure with the shorter twist‐pitches have a larger elongation of helical structure and less cyclic deformation,which can be considered as the main mechanism of better fatigue damage properties for the triple‐helical structures during the strain cycling processes.These findings provide a better understanding of the fatigue properties and damage mechanisms for Nb_(3)Sn triple‐helical structures in superconducting cables of ITER magnets.

A miniature liquid helium temperature JT cryocooler for space application

Along with the development of space science and technology,miniature liquid helium temperature long life cryocooler is a focus subject in cryogenic study.Since it is the precondition of space detection researches,institutions of space in many countries do the research on it.In this article,we designed a compound cooling system.A three-stage high frequency thermal coupled pulse tube cryocooler was used to precool a Joule-Thomson(JT)cryocooler.This system has no moving parts at low temperatures and is hence suitable for space operation.Liquid helium temperature was successfully achieved in both open loop and closed cycle experiments.In the closed cycle experiment,when 473 W electric power was inputted,the cooling system reached a no-load temperature of 4.4 K,and a cooling capacity of 11.6 mW was provided at 4.54 K.It is the first miniature liquid helium temperature JT cryocooler in China and the research achievement paves a way for the space application of ultra-long wave infrared detection and THz technologies.

Ladle Furnace Liquid Steel Temperature Prediction Model Based on Optimally Pruned Bagging

For accurately forecasting the liquid steel temperature in ladle furnace （LF）, a novel temperature predic tion model based on optimally pruned Bagging combined with modified extreme learning machine （ELM） is pro posed. By analyzing the mechanism of LF thermal system, a thermal model with partial linear structure is obtained. Subsequently, modified ELM, named as partial linear extreme learning machine （PLELM）, is developed to estimate the unknown coefficients and undefined function of the thermal model. Finally, a pruning Bagging method is pro- posed to establish the aggregated prediction model for the sake of overcoming the limitation of individual predictor and further improving the prediction performance. In the pruning procedure, AdaBoost is adopted to modify the ag- gregation order of the original Bagging ensembles, and a novel early stopping rule is designed to terminate the aggre- gation earlier. As a result, an optimal pruned Bagging ensemble is achieved, which is able to retain Bagging＇s ro- bustness against highly influential points, reduce the storage needs as well as speed up the computing time. The pro- posed prediction model is examined by practical data, and comparisons with other methods demonstrate that the new ensemble predictor can improve prediction accuracy, and is usually consisted compactly.