The extraction behaviors of zinc from ammoniacal solutions were investigated using β-diketone (HA) and their mixtures with CYANEX923 or LIX84I. The effects of pH, total ammonia concentration, extractant concentrati...The extraction behaviors of zinc from ammoniacal solutions were investigated using β-diketone (HA) and their mixtures with CYANEX923 or LIX84I. The effects of pH, total ammonia concentration, extractant concentration, anion species and temperature on zinc extraction were examined. The synergistic mechanism was discussed with regard to the structure of extractant and the extracted zinc complexes. It is found that the increase of total ammonia concentration and pH inhibits zinc extraction for all extraction systems due to the formation of zinc ammine complexes in aqueous phase. This effect of HA with CYANEX923 is evidently smaller than that of HA with LIX84I or HA alone system. Effect of anion species on the zinc extraction by HA with CYANEX923 can be neglected, but this effect of HA alone and the mixture of HA with LIX84I decreases in the order of (NH4)2SO4 〉 NH4NO3 〉 NH4Cl.展开更多
Three new rare earth ternary complexes, RE(PB)_3bpy (RE=Sm^(3+) , Eu^(3+) , and Tb^(3+) ), were synthesized by the reaction of 1-(p-phenylethynyl- phenyl)-1,3-butanedione (HPB) and 2,2′-bipyridine (bpy) with rare ear...Three new rare earth ternary complexes, RE(PB)_3bpy (RE=Sm^(3+) , Eu^(3+) , and Tb^(3+) ), were synthesized by the reaction of 1-(p-phenylethynyl- phenyl)-1,3-butanedione (HPB) and 2,2′-bipyridine (bpy) with rare earth chloride RECl_3 , respectively, in alcohol solution. The compositions were characterized by means of infrared (IR) spectra, chemical analysis, elemental analysis, and thermodynamic analysis. Luminescent properties of the three complexes were studied. At room temperature, under UV light excitation, the Sm^(3+) , Eu^(3+) , and Tb^(3+) complexes exhibit characteristic emission of the central ions. The fluorescence spectra show that the fluorescence emission intensity of Eu^(3+) complex is the strongest. The narrow strongest emission band of Eu^(3+) complex is considered to be a valuable material with bright red fluorescence.展开更多
In order to study the luminescent properties of ternary rare earth complexes with fl-diketone ligand, three new β-diketone ligands, 1-phenyl-3-(p-phenylethynylphenyl)-1,3-propanedione(HPPP), 1-(2-thienyl)-3-(p...In order to study the luminescent properties of ternary rare earth complexes with fl-diketone ligand, three new β-diketone ligands, 1-phenyl-3-(p-phenylethynylphenyl)-1,3-propanedione(HPPP), 1-(2-thienyl)-3-(p-phenylethynylphenyl)-1,3-propanedione (HTPP) and 1-(2-furyl)-3-(p-phenylethynylphenyl)-1,3-propanedione (HFPP), were synthesized by Sonogashira coupling reaction and Claisen condensation. Three new ternary rare earth complexes, TbL3phen (L = PPP, TPP, or FPP), were synthesized by the reaction of rare earth chloride TbCl3,1,10-phenanthroline (phen) with HPPP, HTPP, or HFPP respectively, in alcohol solution. The compositions were characterized by means of elemental analysis, chemical analysis, and IR spectra. Luminescent properties of the three new complexes have been studied. The results show that the ternary Yb(Ⅲ) complexes only emit the weak fluorescence of the Tb(Ⅲ) ion, which reveals the triplet state energy of the ligands does not match well with the excited state vibrating energy of Tb^3+ ion.展开更多
A novel carbazole functionalized β-diketone, methyl 6-(9-ethylcarbazole-3-yl)-oxoacetyl-2-pyridinecarboxylate (MEP), and its corresponding binary Eu(III) complexes Eu(MEP)y2H2O and ternary complex Eu(MEP)aP...A novel carbazole functionalized β-diketone, methyl 6-(9-ethylcarbazole-3-yl)-oxoacetyl-2-pyridinecarboxylate (MEP), and its corresponding binary Eu(III) complexes Eu(MEP)y2H2O and ternary complex Eu(MEP)aPhen with 1,10-Phenanthroline (Phen) were prepared. The ligand was characterized based on elemental analysis, FT-IR, and ^1H NMR, and the complexes were characterized with elemental analysis, FT-IR and thermogravimetric and differential thermal analysis (TG-DTA). The investigation of fluorescence properties of the complexes Eu(MEP)3·2H2O and Eu(MEP)3Phen showed that the Eu(III) ion could be sensitized efficiently by the ligand to some extent, in partitular, in the ternary system, the secondary ligand Phen acting as a light-harvesting center was involved in the highly efficient energy transfer process, and the emission was stronger than the binary complex. In addition, the introduction of the carbazole moiety enlarged the n-conjugated system of the ligand and enhanced the luminescent intensity of the complexes.展开更多
Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The product...Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The products were formed in high to excellent yields under mild reaction conditions and in short reaction times.展开更多
The structural and dynamical properties of hexafluoroacetylacetone(HFA) and acetylacetone(AA) at the water/supercritical CO2(Sc-CO2) interface at 20 MPa and 318.15 K are investigated by molecular dynamics simulations....The structural and dynamical properties of hexafluoroacetylacetone(HFA) and acetylacetone(AA) at the water/supercritical CO2(Sc-CO2) interface at 20 MPa and 318.15 K are investigated by molecular dynamics simulations.The TIP3P potential is used for water and the EPM2 model is for CO2.The water phase and SC-CO2 phase form a distinct immiscible liquid-liquid interface.The two chelating molecules show interfacial preference.Comparatively,the AA molecules show somewhat more preference for interfacial region,whereas the HFA molecules are preferably near the Sc-CO2 phase.The orientational distribution of the β-diketone molecules and the radial distribution functions between β-diketones and solvents are obtained in order to study the microscopic structural properties of the β-diketones at the water-SC-CO2 interface.It is found that the translational diffusion and rotational diffusion of HFA and AA are obviously anisotropic and decrease as the β-diketone molecules approach the interface.The anisotropic dynamic behavior for the solute molecules is related to the corresponding structural properties.展开更多
Three novel β-diketones (HPPP, HTPP, and HFPP) ligands were synthesized by Sonogashira coupling reaction and Claisen condensation. The structure of β-diketones was confirmed with elemental analysis, IR, NMR and MS...Three novel β-diketones (HPPP, HTPP, and HFPP) ligands were synthesized by Sonogashira coupling reaction and Claisen condensation. The structure of β-diketones was confirmed with elemental analysis, IR, NMR and MS spectra. Three new ternary complexes consisting of Eu(Ⅲ), β-diketones, and 1,10-phenanthroline(phen) were synthesized and characterized as TbL3phen (L=PPP, TPP, FPP) with elemental analysis, chemical analysis, and IR spectra, and their luminescence properties were studied.展开更多
Asymmetric intramolecular cyclopropanation of allylic diazoacetate was investigated using a chiral (β-diketone)-copper complex as catalyst, excellent yield and enantioselectivity were achieved. Some factors influenci...Asymmetric intramolecular cyclopropanation of allylic diazoacetate was investigated using a chiral (β-diketone)-copper complex as catalyst, excellent yield and enantioselectivity were achieved. Some factors influencing enantioselectivity were discussed.展开更多
To provide new insights into the development and utilization of Douchi artificial starters,three common strains(Aspergillus oryzae,Mucor racemosus,and Rhizopus oligosporus)were used to study their influence on the fer...To provide new insights into the development and utilization of Douchi artificial starters,three common strains(Aspergillus oryzae,Mucor racemosus,and Rhizopus oligosporus)were used to study their influence on the fermentation of Douchi.The results showed that the biogenic amine contents of the three types of Douchi were all within the safe range and far lower than those of traditional fermented Douchi.Aspergillus-type Douchi produced more free amino acids than the other two types of Douchi,and its umami taste was more prominent in sensory evaluation(P<0.01),while Mucor-type and Rhizopus-type Douchi produced more esters and pyrazines,making the aroma,sauce,and Douchi flavor more abundant.According to the Pearson and PLS analyses results,sweetness was significantly negatively correlated with phenylalanine,cysteine,and acetic acid(P<0.05),bitterness was significantly negatively correlated with malic acid(P<0.05),the sour taste was significantly positively correlated with citric acid and most free amino acids(P<0.05),while astringency was significantly negatively correlated with glucose(P<0.001).Thirteen volatile compounds such as furfuryl alcohol,phenethyl alcohol,and benzaldehyde caused the flavor difference of three types of Douchi.This study provides theoretical basis for the selection of starting strains for commercial Douchi production.展开更多
The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed ...The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed vacuum drying(PVD),freeze drying(FD),infrared drying(IRD),hot-air drying(HAD)and sun drying(SD)on free amino acids(FAAs),α-dicarbonyl compounds(α-DCs)and volatile compounds(VOCs)in rape bee pollen(RBP)were determined.The results showed that FD significantly released the essential amino acids(EAAs)compared with fresh samples while SD caused the highest loss.Glucosone was the dominantα-DCs in RBP and the highest loss was observed after PVD.Aldehydes were the dominant volatiles of RBP and SD samples contained more new volatile substances(especially aldehydes)than the other four drying methods.Comprehensively,FD and PVD would be potential methods to effectively reduce the quality deterioration of RBP in the drying process.展开更多
Two kinds of fishbone-like, β-diketone-based liquid crystalline polysilsesquioxanes(FBDKLCP'S), homopolymeric (H-FBDKLCP) and copolymeric (C-FBDKaLCP) have been first synthesized via the hydrosilylation reaction ...Two kinds of fishbone-like, β-diketone-based liquid crystalline polysilsesquioxanes(FBDKLCP'S), homopolymeric (H-FBDKLCP) and copolymeric (C-FBDKaLCP) have been first synthesized via the hydrosilylation reaction of a vinyl-terminated β-diketone with the homopolymeric ladderlike polyhydrosilsesquioxane (LPHSQ) and random copolymethylhydrosilsesquioxane (LRPMHSQ) respectively. These new kinds of FBDKLCP with M of 10~4 is thermotroic liquid crystalline polymer and its clearing temperatures T_i's and mesophase range △T's are much higher than those of the corresponding comb-like β-diketone liquid crystalline polysiloxane (DKLCP) by about 200℃. Similar results have been observed with the comparison of the two different structure Cu-coordinating compounds The significant increases in T_((?))'s and △T's of the FBDKLCP and Cu-FBDKLCP are mainly attributed to the great rigidity of the ladderlike polysilsesquioxane backbone.展开更多
A new type of palladium chelate of β-diketone-based side chain liquid crystal polysiloxane (Pd-DKLCP) has been synthesized by chelation reaction of palladium dichloride with polymeric ligand, β-diketone polysiloxane...A new type of palladium chelate of β-diketone-based side chain liquid crystal polysiloxane (Pd-DKLCP) has been synthesized by chelation reaction of palladium dichloride with polymeric ligand, β-diketone polysiloxane (DKLCP), using THF as solvent at R.T.. The Pd-chelation results in greatly increasing the phase transition temperature T_K and the enthalpy change △H_K from crystal to liquid crystal state and making the temperature range of LC state △T(△T=T_(Cl)-T_K) widened. All these chelates Pd-DKLCP's do not show T_(Cl) until decomposition at 205℃. It is noteworthy that the Pd-chelation can exert more positive effect on the mesomorphic behaviour of the polymer ligand than the counterpart Cu-DKLCP does. It is probable due to the bigger size of disc-like mesogen formed from β-diketone and Pd^(+2) ion with 4d orbital.展开更多
A new type of metal coordinated liquid crystalline polymers has been synthesized by complexation of metal ions with β-diketone based side chain liquid crystal polysiloxane (DKLCP). The complexation of copper ions wit...A new type of metal coordinated liquid crystalline polymers has been synthesized by complexation of metal ions with β-diketone based side chain liquid crystal polysiloxane (DKLCP). The complexation of copper ions with DKLCP greatly increases the phase transition temperature T_k from crystalline state to liquid crystalline state and T_(cl) from LC to isotropic state and makes the range of phase transition ΔT (ΔT=T_(cl)-T_k) widened. These complexes are soluble in common organic solvents. However, the incorporation of europium ions into DKLCP molecules gives rise to reduction in liquid crystallinity and crosslinking in some cases. The DKLCP coordinated with suitable amount of Eu ions can show good liquid crystallinity and fluorescent property.展开更多
A new type of binuclear europlum β-diketone chelates Eum Y1-m(TTA)3 phen (0≤m≤1) and the influence of the proportion of Y on fluorescence intensity of the Eu-complexes were studied. It was found the proportion of Y...A new type of binuclear europlum β-diketone chelates Eum Y1-m(TTA)3 phen (0≤m≤1) and the influence of the proportion of Y on fluorescence intensity of the Eu-complexes were studied. It was found the proportion of Y3+ could affect the fluorescence properties and the film formation seriously. only m≥0.5.Y3+ could increase the luminescent intensity and improve the film formalion. As a resull. three new binuclear europium β-diketone chelales consisted of Eu, Y1-m (TTA)3phen (m=0.9. 0.7 and 0.5) were designed and synthesized. Their structures were elucidated by IR. UV. DSC and Elementary Analysis. Their PL properties were studied. The results showed that the three binuclear europium β-diketone chelates had better PL properties and film formation than Eu(TYA)3phen. They could emit sharply red light, and fluorescenl wavelength of them was all at 613nm (half bandwidth 10nm). They can be used as red organic electroluminescent materials (OELMs) in organic electrolminescent devices (OELDS).展开更多
Density Functional Theory method is applied to investigate the enol-keto tautomerism of both acyclic and cyclic α-fluorine-β-diketones. It is shown that, for acyclic cases, α-fluorine could improve the relative sta...Density Functional Theory method is applied to investigate the enol-keto tautomerism of both acyclic and cyclic α-fluorine-β-diketones. It is shown that, for acyclic cases, α-fluorine could improve the relative stability of keto tautomer by lessening intramolecular hydrogen bond of enol form, whereas the relative stability of cyclic enol could be attributed to two factors: destabilization of keto and stabilization of enol. Furthermore, the relative stabilities of all enol tautomers are improved in THF to different extents.展开更多
Tris(d,d-dicampholylmethanato) iron (Ⅲ) complex, Fe(dcm)3, was found to be an excellent catalyst for asymmetric oxygenation of styrene analogues into the corresponding epoxides. Good chemical yields and higher ...Tris(d,d-dicampholylmethanato) iron (Ⅲ) complex, Fe(dcm)3, was found to be an excellent catalyst for asymmetric oxygenation of styrene analogues into the corresponding epoxides. Good chemical yields and higher enantioselectivity were obtained with combined use of molecular oxygen and an aldehyde at 30℃, Some factors influencing enantioselectivity were discussed.展开更多
A new chiral β-diketone Cu (Ⅱ) catalyst was synthesized and used for the asymmetric cyclopropanation of styrene with diazoester. A high optical yield (~90%) was achieved. The effect of the structure of substrate on ...A new chiral β-diketone Cu (Ⅱ) catalyst was synthesized and used for the asymmetric cyclopropanation of styrene with diazoester. A high optical yield (~90%) was achieved. The effect of the structure of substrate on the enantioselectivity was studied. Both chendcal yield and optical yield being reduced when the steric bulky substrate was employed. The reaction mechanism and the chiral model of the transition state are under fufther investigation.展开更多
The exploitation of shale gas is promising due to depletion of the conventional energy and intensification of the greenhouse effect.In this paper,we proposed a heat-fluid-solid coupling damage model of supercritical C...The exploitation of shale gas is promising due to depletion of the conventional energy and intensification of the greenhouse effect.In this paper,we proposed a heat-fluid-solid coupling damage model of supercritical CO_(2)(SC-CO_(2))compound fracturing which is expected to be an efficient and environmentally friendly way to develop shale gas.The coupling model is solved by the finite element method,and the results are in good agreement with the analytical solutions and fracturing experiments.Based on this model,the fracture propagation characteristics at the two stages of compound fracturing are studied and the influence of pressurization rate,in situ stress,bedding angle,and other factors are considered.The results show that at the SC-CO_(2)fracturing stage,a lower pressurization rate is conducive to formation of the branches around main fractures,while a higher pressurization rate inhibits formation of the branches around main fractures and promotes formation of the main fractures.Both bedding and in situ stress play a dominant role in the fracture propagation.When the in situ stress ratio(δ_(x)/δ_(y))is 1,the presence of bedding can reduce the initiation pressure and failure pressure.Nevertheless,it will cause the fracture to propagate along the bedding direction,reducing the fracture complexity.In rocks without bedding,hydraulic fracturing has the lengthening and widening effects for SC-CO_(2)induced fracture.In shale,fractures induced at the hydraulic fracturing stage are more likely to be dominated by in situ stresses and have a shorter reorientation radius.Therefore,fracture branches propagating along the maximum principal stress direction may be generated around the main fractures induced by SC-CO_(2)at the hydraulic fracturing stage.When the branches converge with the main fractures,fracture zones are easily formed,and thus the fracture complexity and damage area can be significantly increased.The results are instructive for the design and application of SC-CO_(2)compound fracturing.展开更多
基金Project (2007CB613601) supported by the National Basic Research Program of ChinaProject (CX2010B112) supported by Hunan Provincial Innovation Foundation for Postgraduate, China
文摘The extraction behaviors of zinc from ammoniacal solutions were investigated using β-diketone (HA) and their mixtures with CYANEX923 or LIX84I. The effects of pH, total ammonia concentration, extractant concentration, anion species and temperature on zinc extraction were examined. The synergistic mechanism was discussed with regard to the structure of extractant and the extracted zinc complexes. It is found that the increase of total ammonia concentration and pH inhibits zinc extraction for all extraction systems due to the formation of zinc ammine complexes in aqueous phase. This effect of HA with CYANEX923 is evidently smaller than that of HA with LIX84I or HA alone system. Effect of anion species on the zinc extraction by HA with CYANEX923 can be neglected, but this effect of HA alone and the mixture of HA with LIX84I decreases in the order of (NH4)2SO4 〉 NH4NO3 〉 NH4Cl.
基金supported by the National Natural Science Foundation of China(No.21141008)the Natural Science Foundation of Inner Mongolia,China(No.2009MS0205)Baotou Science and Technology Bureau,China(No.2010J2004)
文摘Three new rare earth ternary complexes, RE(PB)_3bpy (RE=Sm^(3+) , Eu^(3+) , and Tb^(3+) ), were synthesized by the reaction of 1-(p-phenylethynyl- phenyl)-1,3-butanedione (HPB) and 2,2′-bipyridine (bpy) with rare earth chloride RECl_3 , respectively, in alcohol solution. The compositions were characterized by means of infrared (IR) spectra, chemical analysis, elemental analysis, and thermodynamic analysis. Luminescent properties of the three complexes were studied. At room temperature, under UV light excitation, the Sm^(3+) , Eu^(3+) , and Tb^(3+) complexes exhibit characteristic emission of the central ions. The fluorescence spectra show that the fluorescence emission intensity of Eu^(3+) complex is the strongest. The narrow strongest emission band of Eu^(3+) complex is considered to be a valuable material with bright red fluorescence.
文摘In order to study the luminescent properties of ternary rare earth complexes with fl-diketone ligand, three new β-diketone ligands, 1-phenyl-3-(p-phenylethynylphenyl)-1,3-propanedione(HPPP), 1-(2-thienyl)-3-(p-phenylethynylphenyl)-1,3-propanedione (HTPP) and 1-(2-furyl)-3-(p-phenylethynylphenyl)-1,3-propanedione (HFPP), were synthesized by Sonogashira coupling reaction and Claisen condensation. Three new ternary rare earth complexes, TbL3phen (L = PPP, TPP, or FPP), were synthesized by the reaction of rare earth chloride TbCl3,1,10-phenanthroline (phen) with HPPP, HTPP, or HFPP respectively, in alcohol solution. The compositions were characterized by means of elemental analysis, chemical analysis, and IR spectra. Luminescent properties of the three new complexes have been studied. The results show that the ternary Yb(Ⅲ) complexes only emit the weak fluorescence of the Tb(Ⅲ) ion, which reveals the triplet state energy of the ligands does not match well with the excited state vibrating energy of Tb^3+ ion.
基金supported by China Postdoctoral Science Foundation (20080431027)the Postdoctoral Science Foundation of Central South University (50573019)
文摘A novel carbazole functionalized β-diketone, methyl 6-(9-ethylcarbazole-3-yl)-oxoacetyl-2-pyridinecarboxylate (MEP), and its corresponding binary Eu(III) complexes Eu(MEP)y2H2O and ternary complex Eu(MEP)aPhen with 1,10-Phenanthroline (Phen) were prepared. The ligand was characterized based on elemental analysis, FT-IR, and ^1H NMR, and the complexes were characterized with elemental analysis, FT-IR and thermogravimetric and differential thermal analysis (TG-DTA). The investigation of fluorescence properties of the complexes Eu(MEP)3·2H2O and Eu(MEP)3Phen showed that the Eu(III) ion could be sensitized efficiently by the ligand to some extent, in partitular, in the ternary system, the secondary ligand Phen acting as a light-harvesting center was involved in the highly efficient energy transfer process, and the emission was stronger than the binary complex. In addition, the introduction of the carbazole moiety enlarged the n-conjugated system of the ligand and enhanced the luminescent intensity of the complexes.
基金support from the Research Council of Mazandaran University
文摘Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The products were formed in high to excellent yields under mild reaction conditions and in short reaction times.
基金Supported by the National Natural Science Foundation of China (20776066, 20476044) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (20060291002).
文摘The structural and dynamical properties of hexafluoroacetylacetone(HFA) and acetylacetone(AA) at the water/supercritical CO2(Sc-CO2) interface at 20 MPa and 318.15 K are investigated by molecular dynamics simulations.The TIP3P potential is used for water and the EPM2 model is for CO2.The water phase and SC-CO2 phase form a distinct immiscible liquid-liquid interface.The two chelating molecules show interfacial preference.Comparatively,the AA molecules show somewhat more preference for interfacial region,whereas the HFA molecules are preferably near the Sc-CO2 phase.The orientational distribution of the β-diketone molecules and the radial distribution functions between β-diketones and solvents are obtained in order to study the microscopic structural properties of the β-diketones at the water-SC-CO2 interface.It is found that the translational diffusion and rotational diffusion of HFA and AA are obviously anisotropic and decrease as the β-diketone molecules approach the interface.The anisotropic dynamic behavior for the solute molecules is related to the corresponding structural properties.
基金supported by the Natural Science Foundation of Inner Mongolia (200508010210)the Education Department of Inner Mongolia (NJ06002, NJcxy08124)Science and Technology Bureau of Baotou (2007G1013)
文摘Three novel β-diketones (HPPP, HTPP, and HFPP) ligands were synthesized by Sonogashira coupling reaction and Claisen condensation. The structure of β-diketones was confirmed with elemental analysis, IR, NMR and MS spectra. Three new ternary complexes consisting of Eu(Ⅲ), β-diketones, and 1,10-phenanthroline(phen) were synthesized and characterized as TbL3phen (L=PPP, TPP, FPP) with elemental analysis, chemical analysis, and IR spectra, and their luminescence properties were studied.
文摘Asymmetric intramolecular cyclopropanation of allylic diazoacetate was investigated using a chiral (β-diketone)-copper complex as catalyst, excellent yield and enantioselectivity were achieved. Some factors influencing enantioselectivity were discussed.
基金supported by Special key project of technological innovation and application development in Yongchuan District,Chongqing(2021yc-cxfz20002)the special funds of central government for guiding local science and technology developmentthe funds for the platform projects of professional technology innovation(CSTC2018ZYCXPT0006).
文摘To provide new insights into the development and utilization of Douchi artificial starters,three common strains(Aspergillus oryzae,Mucor racemosus,and Rhizopus oligosporus)were used to study their influence on the fermentation of Douchi.The results showed that the biogenic amine contents of the three types of Douchi were all within the safe range and far lower than those of traditional fermented Douchi.Aspergillus-type Douchi produced more free amino acids than the other two types of Douchi,and its umami taste was more prominent in sensory evaluation(P<0.01),while Mucor-type and Rhizopus-type Douchi produced more esters and pyrazines,making the aroma,sauce,and Douchi flavor more abundant.According to the Pearson and PLS analyses results,sweetness was significantly negatively correlated with phenylalanine,cysteine,and acetic acid(P<0.05),bitterness was significantly negatively correlated with malic acid(P<0.05),the sour taste was significantly positively correlated with citric acid and most free amino acids(P<0.05),while astringency was significantly negatively correlated with glucose(P<0.001).Thirteen volatile compounds such as furfuryl alcohol,phenethyl alcohol,and benzaldehyde caused the flavor difference of three types of Douchi.This study provides theoretical basis for the selection of starting strains for commercial Douchi production.
基金supported by National Natural Science Foundation of China(Nos.31871861 and 31501548)The Apicultural Industry Technology System(NCYTI-43-KXJ17)The Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences(CAAS-ASTIP-2015-IAR)。
文摘The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed vacuum drying(PVD),freeze drying(FD),infrared drying(IRD),hot-air drying(HAD)and sun drying(SD)on free amino acids(FAAs),α-dicarbonyl compounds(α-DCs)and volatile compounds(VOCs)in rape bee pollen(RBP)were determined.The results showed that FD significantly released the essential amino acids(EAAs)compared with fresh samples while SD caused the highest loss.Glucosone was the dominantα-DCs in RBP and the highest loss was observed after PVD.Aldehydes were the dominant volatiles of RBP and SD samples contained more new volatile substances(especially aldehydes)than the other four drying methods.Comprehensively,FD and PVD would be potential methods to effectively reduce the quality deterioration of RBP in the drying process.
文摘Two kinds of fishbone-like, β-diketone-based liquid crystalline polysilsesquioxanes(FBDKLCP'S), homopolymeric (H-FBDKLCP) and copolymeric (C-FBDKaLCP) have been first synthesized via the hydrosilylation reaction of a vinyl-terminated β-diketone with the homopolymeric ladderlike polyhydrosilsesquioxane (LPHSQ) and random copolymethylhydrosilsesquioxane (LRPMHSQ) respectively. These new kinds of FBDKLCP with M of 10~4 is thermotroic liquid crystalline polymer and its clearing temperatures T_i's and mesophase range △T's are much higher than those of the corresponding comb-like β-diketone liquid crystalline polysiloxane (DKLCP) by about 200℃. Similar results have been observed with the comparison of the two different structure Cu-coordinating compounds The significant increases in T_((?))'s and △T's of the FBDKLCP and Cu-FBDKLCP are mainly attributed to the great rigidity of the ladderlike polysilsesquioxane backbone.
文摘A new type of palladium chelate of β-diketone-based side chain liquid crystal polysiloxane (Pd-DKLCP) has been synthesized by chelation reaction of palladium dichloride with polymeric ligand, β-diketone polysiloxane (DKLCP), using THF as solvent at R.T.. The Pd-chelation results in greatly increasing the phase transition temperature T_K and the enthalpy change △H_K from crystal to liquid crystal state and making the temperature range of LC state △T(△T=T_(Cl)-T_K) widened. All these chelates Pd-DKLCP's do not show T_(Cl) until decomposition at 205℃. It is noteworthy that the Pd-chelation can exert more positive effect on the mesomorphic behaviour of the polymer ligand than the counterpart Cu-DKLCP does. It is probable due to the bigger size of disc-like mesogen formed from β-diketone and Pd^(+2) ion with 4d orbital.
文摘A new type of metal coordinated liquid crystalline polymers has been synthesized by complexation of metal ions with β-diketone based side chain liquid crystal polysiloxane (DKLCP). The complexation of copper ions with DKLCP greatly increases the phase transition temperature T_k from crystalline state to liquid crystalline state and T_(cl) from LC to isotropic state and makes the range of phase transition ΔT (ΔT=T_(cl)-T_k) widened. These complexes are soluble in common organic solvents. However, the incorporation of europium ions into DKLCP molecules gives rise to reduction in liquid crystallinity and crosslinking in some cases. The DKLCP coordinated with suitable amount of Eu ions can show good liquid crystallinity and fluorescent property.
文摘A new type of binuclear europlum β-diketone chelates Eum Y1-m(TTA)3 phen (0≤m≤1) and the influence of the proportion of Y on fluorescence intensity of the Eu-complexes were studied. It was found the proportion of Y3+ could affect the fluorescence properties and the film formation seriously. only m≥0.5.Y3+ could increase the luminescent intensity and improve the film formalion. As a resull. three new binuclear europium β-diketone chelales consisted of Eu, Y1-m (TTA)3phen (m=0.9. 0.7 and 0.5) were designed and synthesized. Their structures were elucidated by IR. UV. DSC and Elementary Analysis. Their PL properties were studied. The results showed that the three binuclear europium β-diketone chelates had better PL properties and film formation than Eu(TYA)3phen. They could emit sharply red light, and fluorescenl wavelength of them was all at 613nm (half bandwidth 10nm). They can be used as red organic electroluminescent materials (OELMs) in organic electrolminescent devices (OELDS).
基金This project was supported by the Natural Science Foundation of China (No. 20502022) and the Ph.D. Fund of Ningbo (No. 2004A610010)
文摘Density Functional Theory method is applied to investigate the enol-keto tautomerism of both acyclic and cyclic α-fluorine-β-diketones. It is shown that, for acyclic cases, α-fluorine could improve the relative stability of keto tautomer by lessening intramolecular hydrogen bond of enol form, whereas the relative stability of cyclic enol could be attributed to two factors: destabilization of keto and stabilization of enol. Furthermore, the relative stabilities of all enol tautomers are improved in THF to different extents.
文摘Tris(d,d-dicampholylmethanato) iron (Ⅲ) complex, Fe(dcm)3, was found to be an excellent catalyst for asymmetric oxygenation of styrene analogues into the corresponding epoxides. Good chemical yields and higher enantioselectivity were obtained with combined use of molecular oxygen and an aldehyde at 30℃, Some factors influencing enantioselectivity were discussed.
文摘A new chiral β-diketone Cu (Ⅱ) catalyst was synthesized and used for the asymmetric cyclopropanation of styrene with diazoester. A high optical yield (~90%) was achieved. The effect of the structure of substrate on the enantioselectivity was studied. Both chendcal yield and optical yield being reduced when the steric bulky substrate was employed. The reaction mechanism and the chiral model of the transition state are under fufther investigation.
基金the funding support from the National Natural Science Foundation of China(Nos.52274093 and 52004236).
文摘The exploitation of shale gas is promising due to depletion of the conventional energy and intensification of the greenhouse effect.In this paper,we proposed a heat-fluid-solid coupling damage model of supercritical CO_(2)(SC-CO_(2))compound fracturing which is expected to be an efficient and environmentally friendly way to develop shale gas.The coupling model is solved by the finite element method,and the results are in good agreement with the analytical solutions and fracturing experiments.Based on this model,the fracture propagation characteristics at the two stages of compound fracturing are studied and the influence of pressurization rate,in situ stress,bedding angle,and other factors are considered.The results show that at the SC-CO_(2)fracturing stage,a lower pressurization rate is conducive to formation of the branches around main fractures,while a higher pressurization rate inhibits formation of the branches around main fractures and promotes formation of the main fractures.Both bedding and in situ stress play a dominant role in the fracture propagation.When the in situ stress ratio(δ_(x)/δ_(y))is 1,the presence of bedding can reduce the initiation pressure and failure pressure.Nevertheless,it will cause the fracture to propagate along the bedding direction,reducing the fracture complexity.In rocks without bedding,hydraulic fracturing has the lengthening and widening effects for SC-CO_(2)induced fracture.In shale,fractures induced at the hydraulic fracturing stage are more likely to be dominated by in situ stresses and have a shorter reorientation radius.Therefore,fracture branches propagating along the maximum principal stress direction may be generated around the main fractures induced by SC-CO_(2)at the hydraulic fracturing stage.When the branches converge with the main fractures,fracture zones are easily formed,and thus the fracture complexity and damage area can be significantly increased.The results are instructive for the design and application of SC-CO_(2)compound fracturing.