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Adsorption equilibria of paeoniflorin and albiflorin on cyano-silica column from supercritical carbon dioxide/ethanol

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Chinese Journal of Chemical Engineering 2019年第4期27卷 827-834页

作者： Huisheng Lü Zhi Wang Zhongfeng Geng Yonghui Li Shuangyan Liu Jiatao Liu Key Laboratory for Green Chemical Technology of Ministry of Education R&D Center for Petrochemical Technology Tianjin University Tianjin 300072 China Collaborative Innovation Center of Chemical Science and Engineering Tianjin 300072 China

Adsorption equilibria of paeoniflorin and albiflorin on a cyano-silica column(CN column) from the solution of supercritical carbon dioxide(scCO2) modified with ethanol were studied. The adsorption capacity at 308.15 K,313.15 K, 318.15 K and 323.15 K under pressures corresponding to carbon dioxide/ethanol densities from0.347 g·cm^-3 to 0.662 g·cm^-3 were determined using the elution by characteristic point method(ECP). The effects of temperature and pressure on the solute loading were investigated. The results showed that the lower the temperature, the higher the adsorption capacity. With the decrease of density of scCO2, the adsorption capacity strengthens. The maximum adsorption capacity of paeoniflorin(albiflorin) on the CN column was15.24 mg·ml^-1(31.14 mg·ml^-1) in the range of 0–1.84 mg·ml^-1(0–1.67 mg·ml^-1) of paeoniflorin(albiflorin)standard solution. The adsorption capacity of albiflorin was twice as much as that of paeoniflorin under the same conditions. Adsorption data of paeoniflorin and albiflorin could be well described by the Langmuir model and Freundlich model. Compared with the two model fitting results, the adsorption of paeoniflorin and albiflorin belonged to the monolayer adsorption under conditions of 308.15–323.15 K and 10–17 MPa.

关键词： Adsorption supercritical carbon dioxide Paeoniflorin Albiflorin Isotherm model

The enhanced element enrichment in the supercritical states of granite–pegmatite systems

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Acta Geochimica 2019年第3期38卷 335-349页

作者： Rainer Thomas Paul Davidson Karen Appel Section 3.6.Chemistry and Physics of Earth Materials Helmholtz-Centre Potsdam German Research Centre for Geoscience – GFZ CODES Centre for Ore Deposit and Earth Sciences School of Natural Sciences University of Tasmania High Energy Density scientific instrument European X-Ray Free-Electron Laser Facility GmbH

In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H_2O are completely miscible in all proportions at magmatic temperatures and pressures. This phase evolves from felsic melts and changes into hydrothermal fluids, and its unique properties are particularly important in sequestering and concentrating low abundance elements, such as metals. In our past research, we have focused on processes observed at upper crustal levels, however extensive work by us and other researchers have demonstrated that supercritical melt/fluids should be abundant in melting zones at deep-crustal levels too. We propose that these fluids may provide a connecting link between lower and upper crustal magmas,and a highly efficient transport mechanism for usually melt incompatible elements. In this paper, we explore the unique features of this fluid which allow the partitioning of variouselements and compounds, potentially up to extreme levels,and may explain various features both of mineralization and the magmas that produced them.

关键词： Granites Pegmatites supercritical state Extreme element enrichment

Furfural Reduction via Hydrogen Transfer from supercritical Methanol

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Chemical Research in Chinese Universities 2019年第3期35卷 498-503页

作者： MA Fei LI Hengli JIANG Jiuxing Fine Chemical Industry Research Institute School of ChemistrySun Yat-sen University Guangzhou 510275P.R.China Huizhou Research Institute Sun Yat-sen UniversityHuizhou 516081P.R.China State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical and Technology Beijing 100029P.R.China

Furfural derived from biomass hemicelluloses is an important intermediate for biofuels and chemicals. In order to further upgrade, furfural is usually reduced into 2-methyl furan that is more stable and useful. In this work, furfural was reduced by CuZnAl, CuMgAl, Cu2Cr2O5, CuNiAl as catalysts in a supercritical methanol without external H2 source. The best yield of 2-methyl furan was achieved among the H2 free furfural process reported as high as 74%. And the catalytic behaviors were discussed under difierent catalysts and temperatures conditions.

关键词： Furfural 2-Methyl furan supercritical methanol

Effect of process parameters on the recrystallization and size control of puerarin using the supercritical fluid antisolvent process

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Asian Journal of Pharmaceutical Sciences 2016年第2期11卷 281-291页

作者： Ying Li Yibin Yu Hanbing Wang Fengguang Zhao Department of Pharmacy School of MedicineShenzhen UniversityShenzhenChina Division of Life Science&Health Graduate School at ShenzhenTsinghua UniversityShenzhenChina School of Pharmacy Shenyang Pharmaceutical UniversityShenyangChina Research Institute of Joincare Pharmaceutical Group Industry Co.Ltd ShenzhenChina

The purpose of this study was to investigate the influence of the supercritical CO2 processing on the particle size and morphology of puerarin crystals. The process parameters included solvents, temperature, pressures, antisolvent times, addition volumes, antisolvent addition rates and solute concentrations. After being processed, the dramatic reduction of the dimensions and the change of the crystal shape were noticed. Decreasing the antisolvent addition rate, increasing the temperature and the addition volume below 50 ml led to a decrease in size. The new crystal of puerarin generated at the optimal conditions was 30.34 μm.The solvent of methanol and the concentration of 60 mg/ml were found to determine the type and degree of crystallinity of particles. These results showed that this process has the potential to produce a drug recrystallization product with newly generated crystal forms and the size of drug particles could be controlled through the tuning of various experimental conditions.

关键词： Puerarin Microparticles supercritical fluid GAS Crystallization Particle size

Synthesis of ceramic precursor polycarbosi-lane (PCS) under supercritical fluids (SCFs) state

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Science China(Technological Sciences) 2008年第9期51卷 1445-1450页

作者： YANG DaXiang SONG YongCai LI ZongYuan Key Lab of New Ceramic Fibers and Composites School of Aerospace and Materials EngineeringNational University of Defense TechnologyChangsha 410073China

Using xylene as supercritical fluids (SCFs) media and polydimethylsilane (PDMS) as raw material, the ceramic precursor polycarbosilane (PCS) with moderate mo-lecular weight and narrow molecular weights distribution was synthesized under high pressure and temperature in autoclave. Softening-point test, Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), element analysis and the yield test of PCS were adopted to characterize the SCFs-method and compared with two other PCS synthesis methods named normal-pressure high-temperature (NP) method and high-pressure hith-temperature (HP) method. The results indicate that the PCS maintains a high Si-H content and its chemical formula is SiC1.91H7.27O0.05. The yield is 63.5 wt% which has been improved by about 20 wt%, the softening-point is 180―220 ℃, the number average molecular weight is 1477 and the molecular weights distribution index is 1.61. The synthesis method via supercritical fluids with good diathermancy and reaction uniformity is a new feasi-ble method of synthesizing PCS with good qualities.

关键词： polycarbosilane precursor supercritical fluids synthesis SiC

Lower deviations for supercritical branching processes with immigration

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Frontiers of Mathematics in China 2021年第2期16卷 567-594页

作者： Qi SUN Mei ZHANG School of Mathematics and Statistics Beijing Technology and Business UniversityBeijing 100048China School of Mathematical Sciences Laboratory of Mathematics and Complex SystemsBeijing Normal UniversityBeijing 100875China

For a supercritical branching processes with immigration {Zn};it is known that under suitable conditions on the offspring and immigration distributions, Zn/mn converges almost surely to a finite and strictly positive limit, where m is the offspring mean. We are interested in the limiting properties of P(Zn=kn) with kn=o(mn) as n→∞. We give asymptotic behavior of such lower deviation probabilities in both Schröder and Böttcher cases, unifying and extending the previous results for Galton-Watson processes in literature.

关键词： supercritical branching processes lower deviations immigration

Stress corrosion cracking behavior of 310S in supercritical water with different oxygen concentrations

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Nuclear Science and Techniques 2018年第5期29卷 110-116页

作者： Jin-Hua Liu Yue-Ming Tan Yuan Wang Bin Gong Er Jiang Yong-Fu Zhao Jia-Zhen Wang Shan-Xiu Cong Key Laboratory of Radiation Physics and Technology Ministry of EducationInstitute of Nuclear Science and TechnologySichuan UniversityChengdu 610065China Nuclear Power Institute of China Chengdu 610041China

The effect of dissolved oxygen(DO) on the stress corrosion cracking(SCC) of 310 S in supercritical water was investigated using slow-strain-rate tensile tests.The tensile properties, fracture morphology, and distribution of the chemical composition of the oxide were analyzed to evaluate the SCC susceptibility of 310 S. The results showed that the rupture elongation decreased significantly as the degree of DO increased. A brittle fracture mode was observed on the fracture surface, and only intergranular cracking was observed on the surface of the gauge section, regardless of the DO. Cracks were widely distributed on the gauge surface near the fracture surface.Oxides were observed in the cracks with two-layered structures, i.e., a Cr-rich inner oxide layer and an Fe-rich outer oxide layer.

关键词： supercritical water Dissolved oxygen Stress corrosion cracking Austenitic stainless steels EPMA

Achievability of a supremum for the Hardy-Littlewood-Sobolev inequality with supercritical exponent

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Science China Mathematics 2019年第12期62卷 2497-2504页

作者： Xiaoming An Shuangjie Peng Chaodong Xie School of Mathematics and Statistics Hubei Key Laboratory of Mathematical SciencesCentral China Normal UniversityWuhan 430079China School of Economics Management Guizhou University for Ethinic MinoritiesGuiyang 550025China

In this paper,we prove that the supremum sup{∫B∫B|u(y)|^p(|y|)|u(x)|^p(|x|)/|x-y|^u dxdy:u∈H0^1,rad(B),‖▽u‖L^2(B)=1}is attained,where B denotes the unit ball in R^N(N≥3),μ∈(0,N),p(r)=2^xμ+r^t,t∈(0,min{N/2-... 详细信息

关键词： Hardy-Littlewood-Sobolev inequality achievability of a supremum supercritical exponent

supercritical Elliptic Equation in Hyperbolic Space

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Journal of Partial Differential Equations 2015年第2期28卷 120-127页

作者： HE Haiyang College of Mathematics and Computer Science Key Laboratory of High PerformanceComputing and Stochastic Information Processing (Ministry of Education of China)Hunan Normal University Changsha 410081 China.

In this paper, we study the following semi-linear elliptic equation -△_?~nu=|u|~(p-2)u, (0.1) in the whole Hyperbolic space ?~n, where n≥3, p>2n/(n-2). We obtain some regularity results for the radial singular solutions of problem (0.1). We show that the singular solution u~* with belongs to the closure (in the natural topology given by H_(loc)~1(?~N)∩L_(loc)~p(?~N)) of the set of smooth classical solutions to the Eq. (0.1). In contrast, we also prove that any oscillating radial solutions of (0.1) on ?~N\{0} fails to be in the space H_(loc)~(?~N)∩L_(loc)~p(?~N).

关键词： supercritical singularity hyperbolic space