A reliable ultrasound-assisted extraction （UAE） method combined with HPLC-UV for quantification of eight active alkaloids in fruits of Macleaya cordata （Willd） R. Br. was developed. The optimization conditions of ...A reliable ultrasound-assisted extraction （UAE） method combined with HPLC-UV for quantification of eight active alkaloids in fruits of Macleaya cordata （Willd） R. Br. was developed. The optimization conditions of UAE were obtained by using Box-Behnken design of response surface methodology. Chromatography was carried out using a Kromasil C18 column by gradient elution with 0.1% phosphoric acid aqueous solution for HPLC-UV. All calibration curves showed good linear correlation coefficients （R^2〉0.999 6） and recoveries （from 97.3% to 104.9%） were acceptable. 1,1-diphenyl-2-picrylhydrazyl （DPPH） method was employed to test the antioxidant activity of the extract from the samples. The proposed method was successfully applied to quantifying eight components in nine samples of M.cordata, and significant variations of alkaloid contents and antioxidant aetivity of the samples from different habitats were demonstrated. It presents a powerful proof for the selection of the best sources to extract eight kinds of alkaloids.展开更多
To improve the adsorption properties of chemically modified chitosan, the chelating resin of salicylal chitosan Schiff bases was prepared by the template cross-linking method using Cu（Ⅱ） as template ion and ethylen...To improve the adsorption properties of chemically modified chitosan, the chelating resin of salicylal chitosan Schiff bases was prepared by the template cross-linking method using Cu（Ⅱ） as template ion and ethylene glycol bisglycidyl ether as cross-linking agent in microwave, and was characterized by IR. The adsorption capacity and selectivity coefficient of the chemically modified chitosan for Cu（Ⅱ）, Fe（Ⅲ） and Zn（Ⅱ） were investigated, respectively. The results show that the adsorption capacity of the resin 2.73 mmol/g for Cu（Ⅱ） is bigger than that for other two metal ions, 0.22 mmol/g for Fe（Ⅲ）, and 0.42 mmol/g for Zn（Ⅱ）, and the selectivity coefficients are as follows: KCu（Ⅱ）/Fe（Ⅲ）=12.4, KCu（Ⅱ）/Zn（Ⅱ）=6.5.展开更多
The novel covalently modified glassy carbon electrode with poly(xylitol) was prepared using an electropolymerization technique for the simultaneous determination of uric acid(UA), xanthine(XA) and hypoxanthine(HX). Th...The novel covalently modified glassy carbon electrode with poly(xylitol) was prepared using an electropolymerization technique for the simultaneous determination of uric acid(UA), xanthine(XA) and hypoxanthine(HX). This new electrode presents an excellent electrocatalytic activity towards the oxidation of UA, XA and HX by cyclic voltammetry(CV) method. The oxidation peaks of the three compounds were well defined and had enhanced the peak currents. The separation potentials of the oxidation peak potentials for UA-XA and XA-HX were 380 and 370 mV in CV, respectively. Using differential pulse voltammetry(DPV) method, the calibration curves in the ranges of 5-55, 1.3-75.3 and 4-59 μmol/L were obtained for HX, XA and UA, respectively. The lowest detection limits(S/N=3) were 4.5, 0.75 and 3.75 μmol/L for HX, XA and UA, respectively. The practical application of the modified electrode was demonstrated by the determination of UA, XA, HX in human urine samples.展开更多
Based on the chiral ligand exchange, the distribution behavior of mandelic acid enantiomers, and the partition of Cu2+ at different pH values were studied in a water/alcohol two-phase system containing Cu2+ and N-n-（...Based on the chiral ligand exchange, the distribution behavior of mandelic acid enantiomers, and the partition of Cu2+ at different pH values were studied in a water/alcohol two-phase system containing Cu2+ and N-n-（dodecyl-L-proline（A）.） The influences of the solvent sort, the pH value, the concentrations of Cu2+ and chiral ligand on the partition coefficient（K） and separation factor（α） were discussed. The experimental results show that the A formed has more stable ternary complex with D-mandelic acid enantiomer than with L-mandelic acid enantiomer. There is an important influence of the pH value on K and α. When the pH values are less than 3.5, the formation of binary complexes is thermodynamically unfavourable. K and α become maximum when pH values are above 3.5 and the molar ratio of the chiral ligand to Cu2+ is 2∶1.展开更多
Production of ceramic armour solutions on-demand/in-theatre would have significant logistical and military advantages.However,even assuming that such technologies could be successfully deployed in the field,such near ...Production of ceramic armour solutions on-demand/in-theatre would have significant logistical and military advantages.However,even assuming that such technologies could be successfully deployed in the field,such near net-shape manufacturing technology is relatively immature compared to conventional sintering of ceramics.In this study,the ballistic performance of a series of additively manufactured(AM)/rapidly-prototyped(RP)alumina tiles of 97.2%of the density of Sintox FATM were investigated using both forward-and reverse-ballistic experiments.These experiments,undertaken with compressed gasguns,employed the depth-of-penetration technique and flash X-ray as primary diagnostics to interrogate both efficiency of penetration and projectile-target interaction,respectively.The RP alumina was found to exhibit useful ballistic properties,successfully defeating steel-cored(AP)7.62×39 mm BXN rounds at velocities of up-to c.a.850 m/s,while exhibiting comparable failure modes to conventionally sintered armour-grade Sintox FATM.However,where a<1%by vol.Cu dopant was introduced into the RP material failure modes changed dramatically with performance dropping below that of conventionally sintered alumina.Overall,the results from both sets of experiments were complimentary and clearly indicated the potential of such RP materials to play an active role in provision of real-world body armour solutions provided quality control of the RP material can be maintained.展开更多
Three coordination polymers[Mn(epda)(2,2'⁃bipy)(H_(2)O)](1),[Mn(epda)(phen)](2),and[Co_(2)(epda)2(bpe)2(H_(2)O)_(4)]·5H_(2)O(3)(H2epda=5⁃ethyl⁃pyridine⁃2,3⁃dicarboxylic acid,2,2'⁃bipy=2,2'⁃bipyridine,...Three coordination polymers[Mn(epda)(2,2'⁃bipy)(H_(2)O)](1),[Mn(epda)(phen)](2),and[Co_(2)(epda)2(bpe)2(H_(2)O)_(4)]·5H_(2)O(3)(H2epda=5⁃ethyl⁃pyridine⁃2,3⁃dicarboxylic acid,2,2'⁃bipy=2,2'⁃bipyridine,phen=phenanthroline,bpe=1,2⁃bis(4⁃pyridyl)ethylene)were synthesized by solvothermal reactions and characterized by single⁃crystal X⁃ray diffraction,thermogravimetric analyses,IR spectroscopy and elemental analysis.1 displays a 1D chain struc⁃ture,and these chains are joined by O-H…O hydrogen bonding andπ⁃πstacking interactions to generate a 2D layer structure.2 displays a 2D layer structure,and adjacent layers are generated 3D architecture throughπ⁃πstacking interactions.3 displays a 1D chain structure,and adjacent chains are generated double layer structure through O-H…O hydrogen bonding.The fluorescent properties of 1 and 3 indicate that they can potentially be used as a luminescent sensor.1 was highly selective and sensitive towards o⁃nitrophenol through different detection mechanisms,however,3 was highly selective and sensitive towards 2,4,6⁃trinitrophenol.In addition,the magnetic behavior of 2 has also been investigated.CCDC:2172533,1,2355773,2,2355774,3.展开更多
A series of extractants （tert-butylcalix[6]arene, tert-butylcalix[8]arene and octeacetate of tert-butylcalix[8]arene） were synthesized, and their structures were identified by IR and JH-NMR. The distribution behavio...A series of extractants （tert-butylcalix[6]arene, tert-butylcalix[8]arene and octeacetate of tert-butylcalix[8]arene） were synthesized, and their structures were identified by IR and JH-NMR. The distribution behavior of ester catechins monomer in the aqueous and chloroform two-phase system containing one of calixarene was studied. The influences of different extractants, concentration of tert-butylcalix[8]arene and extraction temperature on the partition coefficients and the separation factors were investigated. The experiment results show that tert-butylcalix[8]arene is the best extractant that forms a more stable supramolecular compound with gallocatechin gallate （GCG） than with epigallocathechin gallate （EGCG） or epicatechin gallate （ECG）. When the concentration ofp-tert-butylcalix[8]arene is 3.79 mmol/L, the extraction temperature is 4 ℃, the partition coefficients ofKGCG, KECG, KEGCG are 0.987, 0.629, 0.449, the separation factors of al and a2 are 1.450 and 1.596, respectively. The important factors influencing the extraction properties of calixarene are discovered to be its cavity size and hydrogen bonding.展开更多
Mesoporous polyethylene glycol-resorcinol and formaldehyde（PEG-RF） carbon xerogels were prepared by a new polymer blend method in which PEG-RF mixed organic xerogels were synthesized by blending thermally unstable p...Mesoporous polyethylene glycol-resorcinol and formaldehyde（PEG-RF） carbon xerogels were prepared by a new polymer blend method in which PEG-RF mixed organic xerogels were synthesized by blending thermally unstable polyethylene glycol with organic monomers, resorcinol and formaldehyde and then subjected to pyrolization at 1 000 ℃. The influences of mass ratio of PEG to the theoretical yield of RF xerogel, m（PEG）/m（RF） and the （relative） molecular mass of PEG on the pore structure and electric double layer capacitance（EDLC） performance of PEG-RF carbon xerogels were investigated. The results show that PEG under different conditions leads to the difference of phase separation structure of the polymer blend and thus the change of pore structure of PEG-RF carbon xerogels. Specific surface area and capacity of PEG-RF carbon xerogels in 30% H2SO4 solution can reach （755 m2/g） and 150 F/g, respectively. Their surface can be fully utilized to form electric double layer. However, the pore structure differences of PEG-RF carbon xerogels result in their different EDLC performances. The distributed capacitance effect increases with decreasing the pore size of PEG-RF carbon xerogels.展开更多
Zirconia-supported CuO （CuO/ZrO2） composite photocatalysts were successfully synthesized via citric acid-assisted sol-gel technique. For comparison, CuO/ZrO2 materials were also prepared by solid state reaction and ...Zirconia-supported CuO （CuO/ZrO2） composite photocatalysts were successfully synthesized via citric acid-assisted sol-gel technique. For comparison, CuO/ZrO2 materials were also prepared by solid state reaction and co-precipitation method. The as-prepared powders were characterized by X-ray diffractometry （XRD）, transmission electron microscopy （TEM）, and thermogravimetric-differential thermal analysis （TG-DTA）. The photocatalytic activity of CuO/ZrO2 catalyst was investigated based on the H2 evolution from oxalic acid solution under simulated sunlight irradiation. The effects of molar ratio of CuO to ZrO2, preparation method, phase change with the calcination temperature and the durability on the photocatalytic activity of the photocatalyst were investigated in detail. It is found that the optimal activity of photocatalytic H2 evolution （2.41 mmol.h i.g-~） can be obtained when CuO/ZrO2 composite photocatalyst is synthesized by sol-gel technique and the mole ratio of CuO to ZrO2 is 40%. The activity of copper oxide supported on monoclinic ZrO2 calcined at higher temperature is much higher than that on tetragonal ZrO2 calcined at lower temperature, and the best calcination temperature is 900 ℃.展开更多
Distribution behavior of ketoprofen enantiomers was examined in methanol aqueous and organic solvent mixture containing tartaric esters. The influence of length of alkyl chain of tartaric esters, concentration of L-ta...Distribution behavior of ketoprofen enantiomers was examined in methanol aqueous and organic solvent mixture containing tartaric esters. The influence of length of alkyl chain of tartaric esters, concentration of L-tartaric esters and methanol aqueous, kind of organic solvent on partition ratio and separation factors was investigated. The results show that L-tartaric and D-tartaric esters have different chiral recognition abilities. S-ketoprofen is easily extracted by L-tartaric esters, and R-ketoprofen is easily extracted by D-tartaric esters. L-tartaric esters form more stable diastereomeric complexes with S-enantiomer than that with R-enantiomer. This distribution behavior is consistent with chiral recognition mechanism. With the increase of the concentration of tartaric ester from 0 to 0.3 mol/L, partition coefficient K and separation factor a increase. Also, the kind of organic solvent and the concentration of the methanol aqueous have significant influence on K and a.展开更多
Volatile oil was extracted from Illicium Verum Hook. f. by using steam distillation. 41 kinds of compounds were separated and identified by GC/MS, and their relative contents were determined by normalization method. A...Volatile oil was extracted from Illicium Verum Hook. f. by using steam distillation. 41 kinds of compounds were separated and identified by GC/MS, and their relative contents were determined by normalization method. Among 41 identified compounds, there are 14 hydrocarbon components and 22 oxygenated hydrocarbon derivatives, and a small amount of nitrogenous compounds. The main component is anethole, accoun ting for 76.23%, and the other components such as anisyl acetone, anisaldehyde, p allylanisole, p cumic aldehyde and p allylpen take up more than 10%.展开更多
The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concent...The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.展开更多
A symmetrically alternative rotating flow pattern was designed for flocculation process in order to produce large and dense flocs. The special effects of a symmetrically alternative rotating flow on the diameter and d...A symmetrically alternative rotating flow pattern was designed for flocculation process in order to produce large and dense flocs. The special effects of a symmetrically alternative rotating flow on the diameter and density of flocs were investigated. The results show that under the new fluid conditions, the primary particles on the outer part of the formed flocs may be cut down and the flocs contract at the end of the original rotating direction; then fluid changes its rotating direction, an opposite shearing is imposed to the flocs and makes some primary particles slide along the floc surface, leading to a denser floc; meanwhile, the broken and unflocculated particles on the trajectory may have opportunities to penetrate into or cohere to the flocs. Compared with the conventional rotating flow, the new-designed flow pattern can not only keep the floc size (even enlarge the floc diameter if a suitable flow is chosen) but also increase the floc density effectively.展开更多
The mechanism of stability of Co-doped spinel λ-MnO_2 that is referred to as spinel Li_xMn_2O_4 (x=0) was studied by using the first-principle calculation method. The total energy and formation enthalpy can be decrea...The mechanism of stability of Co-doped spinel λ-MnO_2 that is referred to as spinel Li_xMn_2O_4 (x=0) was studied by using the first-principle calculation method. The total energy and formation enthalpy can be decreased remarkably due to the Co substation, resulting in a more stable structure of λ-Mn_xCr_(2-x)O_4. The bond order and DOS analysis were given in detail to explain the nature of stability improvement. The calculated results show that as the content of Co dopant increases, the bond order of Mn—O becomes larger and the peak of density of states around Fermi level shifts toward lower energy. The charge density distribution illustrates that the Mn—O bonding is ionic and partially covalent, and the covalent Mn-O bonding becomes stronger with the increase of Co dopant content. The results confirm that the Codoping will enhance the stability of λ-MnO_2 and hence improve the electrochemistry performance of Li_xMn_2O_4.展开更多
Distribution behavior of terbutaline enantiomers was examined in the aqueous and organic solvent of a two-phase system containing L-dibenzoyltartaric acid and lipophilic phase transfer reagent of Na-tetraphenylborate....Distribution behavior of terbutaline enantiomers was examined in the aqueous and organic solvent of a two-phase system containing L-dibenzoyltartaric acid and lipophilic phase transfer reagent of Na-tetraphenylborate. The influences of pH, organic solvents, concentrations of Na-tetraphenylborate and L-dibenzoyltartaric acid on the partition coefficients and enantioselectivity of terbutaline enantiomers, were investigated. The results show that tetraphenylborate lipophilic anion and terbutaline enantiomers form two lipophilic salt complexes , which facilitates the solubility of the enantiomers in the organic phase. L-dibenzoyltartaric acid forms more stable complexes with enantiomer Ⅱ than with enantiomer I . Enantioselectivity and partition coefficient increase with the addition of the length of alkyl chain of alcohols. pH and concentrations of lipophilic anion and L-dibenzoyltartaric acid influence them obviously and differently.展开更多
Inclusion behavior of oxybutynin （OBN） with hydroxypropyl-β-cyclodextrin （HP-β-CD） was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex stoichiom...Inclusion behavior of oxybutynin （OBN） with hydroxypropyl-β-cyclodextrin （HP-β-CD） was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. Alcohol was added to further investigate the mechanism of the inclusion behavior. Thermodynamic constants AG, AH and AS for inclusion interaction of OBN and HP-β-CD were determined. The results show that host-guest complex with molar ratio of 1：1 is formed, and inclusion stability constant between OBN and HP-β-CD is 54.9 L/mol determined by ultraviolet spectrum and 11.1 L/mol determined by fluorescence spectrum. OBN has weak binding ability with HP-β-CD in aqueous solution （stability constant 〈102 L/mol） and addition of alcohol leads to a decrease of stability constant, which indicates that the hydrophobic force contributes to the inclusion process. AG, AH and AS are all less than zero, which indicates that the inclusion process is a spontaneous and exothermic process.展开更多
Plasticizers in plasticized polyvinyl chloride (PVC) are generally physically added into PVC by compounding so that they can be rapidly leached from PVC articles during service. This results in their migration into th...Plasticizers in plasticized polyvinyl chloride (PVC) are generally physically added into PVC by compounding so that they can be rapidly leached from PVC articles during service. This results in their migration into the human environment with potentially serious consequences and lower effectiveness of the additives in PVC. Potentially the chemical modification of PVC during processing via reactive processing procedure is one of the most attractive solutions to these problems. In this paper, we will report our work in exploring an environmentally friendly and cost-effective reactive processing approach for chemically binding plasticizer into PVC chains. Our research results indicate that it is possible to reduce the plasticizer migration from a plasticized PVC by chemically binding of a certain plasticizer into PVC chains via reactive processing. Thus, high levels of binding of DBM,a maleate plasticizer, to PVC may be reached in less than 10 min under prevailing reactive processing conditions. The extent of binding of DBM as a function of the loading shows two peaks: one at a relatively low loading (less than 0.12 mol·kg^-1 PVC) tends to 100%, the other in the high loading region (more than 1.5 mol·kg^-1 PVC) approaches around 50%. The DBM modified PVC polymer exhibits behaviours as a plasticized PVC but its bound plasticising groups would not be leached by solvent extraction.展开更多
A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots （QDs） is proposed. The photoluminescence of QDs is sensitive to H202. This finding leads to a novel approa...A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots （QDs） is proposed. The photoluminescence of QDs is sensitive to H202. This finding leads to a novel approach for the determination of ethanol using alcohol oxidase （AOx） which, on oxidation of ethanol, produces H202. The method has higher sensitivity, wider analytical range （0.1-8 mmol/L）, and a lower detection limit （0.05 mmol/L）. The relationship between quenching of the photoluminescence of the QDs and the concentration of ethanol is linear.展开更多
Three new chiral stationary phases, 2,6 di O heptyl 3 O trimethylsilyl β cyclodextrin(DHTBCD), 2,6 di O pentyl 3 O trimethylsilyl β cyclodextrin (DPTBCD) and 2,6 di O butyl 3 O trimethylsilyl β cyclodextrin (DBTBCD...Three new chiral stationary phases, 2,6 di O heptyl 3 O trimethylsilyl β cyclodextrin(DHTBCD), 2,6 di O pentyl 3 O trimethylsilyl β cyclodextrin (DPTBCD) and 2,6 di O butyl 3 O trimethylsilyl β cyclodextrin (DBTBCD), were synthesized. Chromatographic properties such as column efficiency, thermal stability and column life span, were studied. The separations of enantiomers, such as ketone, esters, alcohols and olefines, were investigated on the alkylated and silylated β cyclodextrin stationary phases. The influence of diluent on chiral separation was studied. The experimental results indicate that the stationary phases show good chromatographic properties in separating enantiomers. It is observed that inclusion complexation and hydrogen bonding interaction hardly play a role in separating enantiomers.展开更多
基金Project(20576142) supposed by the National Natural Science Foundation of China Project(2009DFA31270) supported by the International Cooperation Project of Ministry of Science and Technology of China
文摘A reliable ultrasound-assisted extraction （UAE） method combined with HPLC-UV for quantification of eight active alkaloids in fruits of Macleaya cordata （Willd） R. Br. was developed. The optimization conditions of UAE were obtained by using Box-Behnken design of response surface methodology. Chromatography was carried out using a Kromasil C18 column by gradient elution with 0.1% phosphoric acid aqueous solution for HPLC-UV. All calibration curves showed good linear correlation coefficients （R^2〉0.999 6） and recoveries （from 97.3% to 104.9%） were acceptable. 1,1-diphenyl-2-picrylhydrazyl （DPPH） method was employed to test the antioxidant activity of the extract from the samples. The proposed method was successfully applied to quantifying eight components in nine samples of M.cordata, and significant variations of alkaloid contents and antioxidant aetivity of the samples from different habitats were demonstrated. It presents a powerful proof for the selection of the best sources to extract eight kinds of alkaloids.
文摘To improve the adsorption properties of chemically modified chitosan, the chelating resin of salicylal chitosan Schiff bases was prepared by the template cross-linking method using Cu（Ⅱ） as template ion and ethylene glycol bisglycidyl ether as cross-linking agent in microwave, and was characterized by IR. The adsorption capacity and selectivity coefficient of the chemically modified chitosan for Cu（Ⅱ）, Fe（Ⅲ） and Zn（Ⅱ） were investigated, respectively. The results show that the adsorption capacity of the resin 2.73 mmol/g for Cu（Ⅱ） is bigger than that for other two metal ions, 0.22 mmol/g for Fe（Ⅲ）, and 0.42 mmol/g for Zn（Ⅱ）, and the selectivity coefficients are as follows: KCu（Ⅱ）/Fe（Ⅲ）=12.4, KCu（Ⅱ）/Zn（Ⅱ）=6.5.
基金Project(201215135) supported by the Natural Science Foundation of Jilin Province,China
文摘The novel covalently modified glassy carbon electrode with poly(xylitol) was prepared using an electropolymerization technique for the simultaneous determination of uric acid(UA), xanthine(XA) and hypoxanthine(HX). This new electrode presents an excellent electrocatalytic activity towards the oxidation of UA, XA and HX by cyclic voltammetry(CV) method. The oxidation peaks of the three compounds were well defined and had enhanced the peak currents. The separation potentials of the oxidation peak potentials for UA-XA and XA-HX were 380 and 370 mV in CV, respectively. Using differential pulse voltammetry(DPV) method, the calibration curves in the ranges of 5-55, 1.3-75.3 and 4-59 μmol/L were obtained for HX, XA and UA, respectively. The lowest detection limits(S/N=3) were 4.5, 0.75 and 3.75 μmol/L for HX, XA and UA, respectively. The practical application of the modified electrode was demonstrated by the determination of UA, XA, HX in human urine samples.
基金Project(20376085) supported by the National Natural Science Foundation of China
文摘Based on the chiral ligand exchange, the distribution behavior of mandelic acid enantiomers, and the partition of Cu2+ at different pH values were studied in a water/alcohol two-phase system containing Cu2+ and N-n-（dodecyl-L-proline（A）.） The influences of the solvent sort, the pH value, the concentrations of Cu2+ and chiral ligand on the partition coefficient（K） and separation factor（α） were discussed. The experimental results show that the A formed has more stable ternary complex with D-mandelic acid enantiomer than with L-mandelic acid enantiomer. There is an important influence of the pH value on K and α. When the pH values are less than 3.5, the formation of binary complexes is thermodynamically unfavourable. K and α become maximum when pH values are above 3.5 and the molar ratio of the chiral ligand to Cu2+ is 2∶1.
文摘Production of ceramic armour solutions on-demand/in-theatre would have significant logistical and military advantages.However,even assuming that such technologies could be successfully deployed in the field,such near net-shape manufacturing technology is relatively immature compared to conventional sintering of ceramics.In this study,the ballistic performance of a series of additively manufactured(AM)/rapidly-prototyped(RP)alumina tiles of 97.2%of the density of Sintox FATM were investigated using both forward-and reverse-ballistic experiments.These experiments,undertaken with compressed gasguns,employed the depth-of-penetration technique and flash X-ray as primary diagnostics to interrogate both efficiency of penetration and projectile-target interaction,respectively.The RP alumina was found to exhibit useful ballistic properties,successfully defeating steel-cored(AP)7.62×39 mm BXN rounds at velocities of up-to c.a.850 m/s,while exhibiting comparable failure modes to conventionally sintered armour-grade Sintox FATM.However,where a<1%by vol.Cu dopant was introduced into the RP material failure modes changed dramatically with performance dropping below that of conventionally sintered alumina.Overall,the results from both sets of experiments were complimentary and clearly indicated the potential of such RP materials to play an active role in provision of real-world body armour solutions provided quality control of the RP material can be maintained.
文摘Three coordination polymers[Mn(epda)(2,2'⁃bipy)(H_(2)O)](1),[Mn(epda)(phen)](2),and[Co_(2)(epda)2(bpe)2(H_(2)O)_(4)]·5H_(2)O(3)(H2epda=5⁃ethyl⁃pyridine⁃2,3⁃dicarboxylic acid,2,2'⁃bipy=2,2'⁃bipyridine,phen=phenanthroline,bpe=1,2⁃bis(4⁃pyridyl)ethylene)were synthesized by solvothermal reactions and characterized by single⁃crystal X⁃ray diffraction,thermogravimetric analyses,IR spectroscopy and elemental analysis.1 displays a 1D chain struc⁃ture,and these chains are joined by O-H…O hydrogen bonding andπ⁃πstacking interactions to generate a 2D layer structure.2 displays a 2D layer structure,and adjacent layers are generated 3D architecture throughπ⁃πstacking interactions.3 displays a 1D chain structure,and adjacent chains are generated double layer structure through O-H…O hydrogen bonding.The fluorescent properties of 1 and 3 indicate that they can potentially be used as a luminescent sensor.1 was highly selective and sensitive towards o⁃nitrophenol through different detection mechanisms,however,3 was highly selective and sensitive towards 2,4,6⁃trinitrophenol.In addition,the magnetic behavior of 2 has also been investigated.CCDC:2172533,1,2355773,2,2355774,3.
基金Project (20576029) supported by the National Natural Science Foundation of China
文摘A series of extractants （tert-butylcalix[6]arene, tert-butylcalix[8]arene and octeacetate of tert-butylcalix[8]arene） were synthesized, and their structures were identified by IR and JH-NMR. The distribution behavior of ester catechins monomer in the aqueous and chloroform two-phase system containing one of calixarene was studied. The influences of different extractants, concentration of tert-butylcalix[8]arene and extraction temperature on the partition coefficients and the separation factors were investigated. The experiment results show that tert-butylcalix[8]arene is the best extractant that forms a more stable supramolecular compound with gallocatechin gallate （GCG） than with epigallocathechin gallate （EGCG） or epicatechin gallate （ECG）. When the concentration ofp-tert-butylcalix[8]arene is 3.79 mmol/L, the extraction temperature is 4 ℃, the partition coefficients ofKGCG, KECG, KEGCG are 0.987, 0.629, 0.449, the separation factors of al and a2 are 1.450 and 1.596, respectively. The important factors influencing the extraction properties of calixarene are discovered to be its cavity size and hydrogen bonding.
文摘Mesoporous polyethylene glycol-resorcinol and formaldehyde（PEG-RF） carbon xerogels were prepared by a new polymer blend method in which PEG-RF mixed organic xerogels were synthesized by blending thermally unstable polyethylene glycol with organic monomers, resorcinol and formaldehyde and then subjected to pyrolization at 1 000 ℃. The influences of mass ratio of PEG to the theoretical yield of RF xerogel, m（PEG）/m（RF） and the （relative） molecular mass of PEG on the pore structure and electric double layer capacitance（EDLC） performance of PEG-RF carbon xerogels were investigated. The results show that PEG under different conditions leads to the difference of phase separation structure of the polymer blend and thus the change of pore structure of PEG-RF carbon xerogels. Specific surface area and capacity of PEG-RF carbon xerogels in 30% H2SO4 solution can reach （755 m2/g） and 150 F/g, respectively. Their surface can be fully utilized to form electric double layer. However, the pore structure differences of PEG-RF carbon xerogels result in their different EDLC performances. The distributed capacitance effect increases with decreasing the pore size of PEG-RF carbon xerogels.
基金Project(20876039) supported by the National Natural Science Foundation of ChinaProject(09JJ3023) supported by the Natural Science Foundation of Hunan Province,China
文摘Zirconia-supported CuO （CuO/ZrO2） composite photocatalysts were successfully synthesized via citric acid-assisted sol-gel technique. For comparison, CuO/ZrO2 materials were also prepared by solid state reaction and co-precipitation method. The as-prepared powders were characterized by X-ray diffractometry （XRD）, transmission electron microscopy （TEM）, and thermogravimetric-differential thermal analysis （TG-DTA）. The photocatalytic activity of CuO/ZrO2 catalyst was investigated based on the H2 evolution from oxalic acid solution under simulated sunlight irradiation. The effects of molar ratio of CuO to ZrO2, preparation method, phase change with the calcination temperature and the durability on the photocatalytic activity of the photocatalyst were investigated in detail. It is found that the optimal activity of photocatalytic H2 evolution （2.41 mmol.h i.g-~） can be obtained when CuO/ZrO2 composite photocatalyst is synthesized by sol-gel technique and the mole ratio of CuO to ZrO2 is 40%. The activity of copper oxide supported on monoclinic ZrO2 calcined at higher temperature is much higher than that on tetragonal ZrO2 calcined at lower temperature, and the best calcination temperature is 900 ℃.
基金Project(20376085) supportecd by the National Natural Science Foundation of China
文摘Distribution behavior of ketoprofen enantiomers was examined in methanol aqueous and organic solvent mixture containing tartaric esters. The influence of length of alkyl chain of tartaric esters, concentration of L-tartaric esters and methanol aqueous, kind of organic solvent on partition ratio and separation factors was investigated. The results show that L-tartaric and D-tartaric esters have different chiral recognition abilities. S-ketoprofen is easily extracted by L-tartaric esters, and R-ketoprofen is easily extracted by D-tartaric esters. L-tartaric esters form more stable diastereomeric complexes with S-enantiomer than that with R-enantiomer. This distribution behavior is consistent with chiral recognition mechanism. With the increase of the concentration of tartaric ester from 0 to 0.3 mol/L, partition coefficient K and separation factor a increase. Also, the kind of organic solvent and the concentration of the methanol aqueous have significant influence on K and a.
基金ScienceFoundationofEducationforHunanProvince (No .0 0C32 4 )
文摘Volatile oil was extracted from Illicium Verum Hook. f. by using steam distillation. 41 kinds of compounds were separated and identified by GC/MS, and their relative contents were determined by normalization method. Among 41 identified compounds, there are 14 hydrocarbon components and 22 oxygenated hydrocarbon derivatives, and a small amount of nitrogenous compounds. The main component is anethole, accoun ting for 76.23%, and the other components such as anisyl acetone, anisaldehyde, p allylanisole, p cumic aldehyde and p allylpen take up more than 10%.
基金Project(20776038)supported by the National Natural Science Foundation of China
文摘The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.
文摘A symmetrically alternative rotating flow pattern was designed for flocculation process in order to produce large and dense flocs. The special effects of a symmetrically alternative rotating flow on the diameter and density of flocs were investigated. The results show that under the new fluid conditions, the primary particles on the outer part of the formed flocs may be cut down and the flocs contract at the end of the original rotating direction; then fluid changes its rotating direction, an opposite shearing is imposed to the flocs and makes some primary particles slide along the floc surface, leading to a denser floc; meanwhile, the broken and unflocculated particles on the trajectory may have opportunities to penetrate into or cohere to the flocs. Compared with the conventional rotating flow, the new-designed flow pattern can not only keep the floc size (even enlarge the floc diameter if a suitable flow is chosen) but also increase the floc density effectively.
基金Project(20376086) supported by National Natural Science Foundation of China
文摘The mechanism of stability of Co-doped spinel λ-MnO_2 that is referred to as spinel Li_xMn_2O_4 (x=0) was studied by using the first-principle calculation method. The total energy and formation enthalpy can be decreased remarkably due to the Co substation, resulting in a more stable structure of λ-Mn_xCr_(2-x)O_4. The bond order and DOS analysis were given in detail to explain the nature of stability improvement. The calculated results show that as the content of Co dopant increases, the bond order of Mn—O becomes larger and the peak of density of states around Fermi level shifts toward lower energy. The charge density distribution illustrates that the Mn—O bonding is ionic and partially covalent, and the covalent Mn-O bonding becomes stronger with the increase of Co dopant content. The results confirm that the Codoping will enhance the stability of λ-MnO_2 and hence improve the electrochemistry performance of Li_xMn_2O_4.
文摘Distribution behavior of terbutaline enantiomers was examined in the aqueous and organic solvent of a two-phase system containing L-dibenzoyltartaric acid and lipophilic phase transfer reagent of Na-tetraphenylborate. The influences of pH, organic solvents, concentrations of Na-tetraphenylborate and L-dibenzoyltartaric acid on the partition coefficients and enantioselectivity of terbutaline enantiomers, were investigated. The results show that tetraphenylborate lipophilic anion and terbutaline enantiomers form two lipophilic salt complexes , which facilitates the solubility of the enantiomers in the organic phase. L-dibenzoyltartaric acid forms more stable complexes with enantiomer Ⅱ than with enantiomer I . Enantioselectivity and partition coefficient increase with the addition of the length of alkyl chain of alcohols. pH and concentrations of lipophilic anion and L-dibenzoyltartaric acid influence them obviously and differently.
基金Project(20976041) supported by the National Natural Science Foundation of China
文摘Inclusion behavior of oxybutynin （OBN） with hydroxypropyl-β-cyclodextrin （HP-β-CD） was investigated by ultraviolet absorption spectrum and fluorescence spectrum. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. Alcohol was added to further investigate the mechanism of the inclusion behavior. Thermodynamic constants AG, AH and AS for inclusion interaction of OBN and HP-β-CD were determined. The results show that host-guest complex with molar ratio of 1：1 is formed, and inclusion stability constant between OBN and HP-β-CD is 54.9 L/mol determined by ultraviolet spectrum and 11.1 L/mol determined by fluorescence spectrum. OBN has weak binding ability with HP-β-CD in aqueous solution （stability constant 〈102 L/mol） and addition of alcohol leads to a decrease of stability constant, which indicates that the hydrophobic force contributes to the inclusion process. AG, AH and AS are all less than zero, which indicates that the inclusion process is a spontaneous and exothermic process.
文摘Plasticizers in plasticized polyvinyl chloride (PVC) are generally physically added into PVC by compounding so that they can be rapidly leached from PVC articles during service. This results in their migration into the human environment with potentially serious consequences and lower effectiveness of the additives in PVC. Potentially the chemical modification of PVC during processing via reactive processing procedure is one of the most attractive solutions to these problems. In this paper, we will report our work in exploring an environmentally friendly and cost-effective reactive processing approach for chemically binding plasticizer into PVC chains. Our research results indicate that it is possible to reduce the plasticizer migration from a plasticized PVC by chemically binding of a certain plasticizer into PVC chains via reactive processing. Thus, high levels of binding of DBM,a maleate plasticizer, to PVC may be reached in less than 10 min under prevailing reactive processing conditions. The extent of binding of DBM as a function of the loading shows two peaks: one at a relatively low loading (less than 0.12 mol·kg^-1 PVC) tends to 100%, the other in the high loading region (more than 1.5 mol·kg^-1 PVC) approaches around 50%. The DBM modified PVC polymer exhibits behaviours as a plasticized PVC but its bound plasticising groups would not be leached by solvent extraction.
基金Project(21005067)supported by the National Natural Science Foundation of ChinaProject(11JJ4015)supported by Natural Science Foundation of Hunan Province,China
文摘A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots （QDs） is proposed. The photoluminescence of QDs is sensitive to H202. This finding leads to a novel approach for the determination of ethanol using alcohol oxidase （AOx） which, on oxidation of ethanol, produces H202. The method has higher sensitivity, wider analytical range （0.1-8 mmol/L）, and a lower detection limit （0.05 mmol/L）. The relationship between quenching of the photoluminescence of the QDs and the concentration of ethanol is linear.
文摘Three new chiral stationary phases, 2,6 di O heptyl 3 O trimethylsilyl β cyclodextrin(DHTBCD), 2,6 di O pentyl 3 O trimethylsilyl β cyclodextrin (DPTBCD) and 2,6 di O butyl 3 O trimethylsilyl β cyclodextrin (DBTBCD), were synthesized. Chromatographic properties such as column efficiency, thermal stability and column life span, were studied. The separations of enantiomers, such as ketone, esters, alcohols and olefines, were investigated on the alkylated and silylated β cyclodextrin stationary phases. The influence of diluent on chiral separation was studied. The experimental results indicate that the stationary phases show good chromatographic properties in separating enantiomers. It is observed that inclusion complexation and hydrogen bonding interaction hardly play a role in separating enantiomers.
