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2005 Volume 16 Issue 6
2005, 16(6): 711-712
Abstract:
The first total synthesis of 3-oxo-11, 12, 13-trihydroxyeudesm-4-ene, a highly oxygenated natural eudesmane, was described.
The first total synthesis of 3-oxo-11, 12, 13-trihydroxyeudesm-4-ene, a highly oxygenated natural eudesmane, was described.
2005, 16(6): 714-715
Abstract:
L-DOPA has gained widespread credit over the past decades as being the mainstay of the pharmacological treatment of Parkinson's disease. However, there are many adverse effects associated with the use of L-DOPA. The prodrug approach is the most promising way to solve the problem. In this article, a thionated dipeptide prodrug of L-DOPA 11 was synthesized via 10 steps in a total yield of 26.5% from L-DOPA.
L-DOPA has gained widespread credit over the past decades as being the mainstay of the pharmacological treatment of Parkinson's disease. However, there are many adverse effects associated with the use of L-DOPA. The prodrug approach is the most promising way to solve the problem. In this article, a thionated dipeptide prodrug of L-DOPA 11 was synthesized via 10 steps in a total yield of 26.5% from L-DOPA.
2005, 16(6): 716-718
Abstract:
A concise and efficient total synthesis of (-)-umbelactone 1, an occurring γ-hydroxymethyl-α, β-butenolide from Memycelon umbelatum Burm, is described. The synthesis features the use of a ring closing metathesis strategy.
A concise and efficient total synthesis of (-)-umbelactone 1, an occurring γ-hydroxymethyl-α, β-butenolide from Memycelon umbelatum Burm, is described. The synthesis features the use of a ring closing metathesis strategy.
2005, 16(6): 719-722
Abstract:
An extremely facile and rapid solid phase route free of column chromatographic purification for the synthesis of the soluble monodisperse oligo(1, 4-phenyleneethynylene)s up to~60(Å) was presented.
An extremely facile and rapid solid phase route free of column chromatographic purification for the synthesis of the soluble monodisperse oligo(1, 4-phenyleneethynylene)s up to~60(Å) was presented.
2005, 16(6): 723-726
Abstract:
To find new structural leading compounds for the research of the multidrug resistant of antibacterial agents, five novel 8-substituted phenyl-1-pyridin-3-yl-5H-bis[1, 2, 4] triazolo[3, 4-b;4', 3'-d] thiadiazines were prepared from the corresponding intermediates of 3-(5-substituted phenyl[1,3,4]oxadiazol-2-ylmethylsulfanyl)-5-pyridin-3-yl-[1,2,4]triazol-4-ylamines via intramolecular cyclization and the antibacterial activity in vitro against Gram-postive (G+) and Gram negatiye (G-) bacteria was primarily evaluated.
To find new structural leading compounds for the research of the multidrug resistant of antibacterial agents, five novel 8-substituted phenyl-1-pyridin-3-yl-5H-bis[1, 2, 4] triazolo[3, 4-b;4', 3'-d] thiadiazines were prepared from the corresponding intermediates of 3-(5-substituted phenyl[1,3,4]oxadiazol-2-ylmethylsulfanyl)-5-pyridin-3-yl-[1,2,4]triazol-4-ylamines via intramolecular cyclization and the antibacterial activity in vitro against Gram-postive (G+) and Gram negatiye (G-) bacteria was primarily evaluated.
2005, 16(6): 727-728
Abstract:
The first total synthesis of (±)-13-hydroxy-8 (14)-abietene was accomplished in 20.1%yield via a strategy of AC→ABC, in which the reduction of compound 5 with Li/NH3 gave the key intermediate 6 and the title compound was then obtained by the reaction of compound 6 with Grignard reagent.
The first total synthesis of (±)-13-hydroxy-8 (14)-abietene was accomplished in 20.1%yield via a strategy of AC→ABC, in which the reduction of compound 5 with Li/NH3 gave the key intermediate 6 and the title compound was then obtained by the reaction of compound 6 with Grignard reagent.
2005, 16(6): 729-732
Abstract:
Photochemical[2+2] cycloaddition of C60 with podophyllotoxin derivative containing a cyclohexadienone group in o-dichlorobenzene afforded an isomeric mixture of adducts and a pure adduct of C60-fused podophyllotoxin derivatives. The structures of the products were characterized by MS, NMR and IR spectra.
Photochemical[2+2] cycloaddition of C60 with podophyllotoxin derivative containing a cyclohexadienone group in o-dichlorobenzene afforded an isomeric mixture of adducts and a pure adduct of C60-fused podophyllotoxin derivatives. The structures of the products were characterized by MS, NMR and IR spectra.
2005, 16(6): 733-735
Abstract:
In this paper, we present the synthesis and anion recognition properties of the amide based phenanthroline derivatives 1, 2 and 3. In all cases 1:1 receptor:anion complexes were observed. The receptors were found to be selective for fluoride and chloride respectively over other putative anionic guest species.
In this paper, we present the synthesis and anion recognition properties of the amide based phenanthroline derivatives 1, 2 and 3. In all cases 1:1 receptor:anion complexes were observed. The receptors were found to be selective for fluoride and chloride respectively over other putative anionic guest species.
2005, 16(6): 736-738
Abstract:
Sinenxan A[2α, 5α, 10β, 14β-tetraacetoxytaxa-4(20), 11-diene, 1] was biotransformed by a filamentous fungus, Aspergillus niger JCM 5546, and an unusual taxatetraene[2α,5α-acetoxytaxa-4(20), 10(11), 12(18), 13(14)-tetraene, 2], together with two known products,10β-deacetyl sinenxan A (3) and 10β, 14β-dideacetyl sinenxan A (4) were produced.
Sinenxan A[2α, 5α, 10β, 14β-tetraacetoxytaxa-4(20), 11-diene, 1] was biotransformed by a filamentous fungus, Aspergillus niger JCM 5546, and an unusual taxatetraene[2α,5α-acetoxytaxa-4(20), 10(11), 12(18), 13(14)-tetraene, 2], together with two known products,10β-deacetyl sinenxan A (3) and 10β, 14β-dideacetyl sinenxan A (4) were produced.
2005, 16(6): 739-742
Abstract:
Two new s-triazine derivatives, which belong to linear dipolar type and triangle octupolar type respectively, have been synthesized. The structure of the dipolar compound has been determined by X-ray diffraction. The two-photon absorption cross-section σ, and the two-photon excited fluorescence (TPEF) intensities are increased significantly from dipolar compound to octupolar compound.
Two new s-triazine derivatives, which belong to linear dipolar type and triangle octupolar type respectively, have been synthesized. The structure of the dipolar compound has been determined by X-ray diffraction. The two-photon absorption cross-section σ, and the two-photon excited fluorescence (TPEF) intensities are increased significantly from dipolar compound to octupolar compound.
2005, 16(6): 743-746
Abstract:
Insulin was chemically modified with dehydrocholic acid without the use of protecting agents and the main monoacylated insulin. ε-NB29-Dehydrocholyl insulin was obtained selectively and analyzed by PAGE, HPLC and MALDI-TOF-MS.
Insulin was chemically modified with dehydrocholic acid without the use of protecting agents and the main monoacylated insulin. ε-NB29-Dehydrocholyl insulin was obtained selectively and analyzed by PAGE, HPLC and MALDI-TOF-MS.
2005, 16(6): 747-750
Abstract:
Sulfamic acid has been used as an efficient catalyst and green alternative for conventional acidic materials to promote the acetolysis reaction of THF to produce 1,4-diacetoxybutane. This method is also applicable in the acetolysis of other cyclic ethers, such as methyl substituted THF and tetrahydropyran and 1,4-dioxane which is less reactivity.
Sulfamic acid has been used as an efficient catalyst and green alternative for conventional acidic materials to promote the acetolysis reaction of THF to produce 1,4-diacetoxybutane. This method is also applicable in the acetolysis of other cyclic ethers, such as methyl substituted THF and tetrahydropyran and 1,4-dioxane which is less reactivity.
2005, 16(6): 751-754
Abstract:
A series of photo active azido analogues have been synthesized and their photochromic properties have also been investigated by UV-Vis spectrum. It will be used for the rapid and reliable preparation of large amounts of stable, non-radioactive labeled DNA and RNA hybridization probes. And it is supposed to be easily detected for its photochromic properties.
A series of photo active azido analogues have been synthesized and their photochromic properties have also been investigated by UV-Vis spectrum. It will be used for the rapid and reliable preparation of large amounts of stable, non-radioactive labeled DNA and RNA hybridization probes. And it is supposed to be easily detected for its photochromic properties.
2005, 16(6): 755-758
Abstract:
Three synthetic routes for the preparation of nitrogen containing cyclic compounds have been developed, in which the assembling of Fomc-Lys(Boc) residue at N-terminal of resin-bound intermediates is a key prerequisite. Six peptides with nitrogen containing local cyclic structure were efficiently synthesized in good yield starting from chloromethyl resin.
Three synthetic routes for the preparation of nitrogen containing cyclic compounds have been developed, in which the assembling of Fomc-Lys(Boc) residue at N-terminal of resin-bound intermediates is a key prerequisite. Six peptides with nitrogen containing local cyclic structure were efficiently synthesized in good yield starting from chloromethyl resin.
2005, 16(6): 759-762
Abstract:
Based on the pseudo-dilution effect (PDE) on solid support, three cyclopeptides with an aliphatic-aryl ether bond as the bridge were synthesized via SN2 reaction between bromoacetylated at N-terminal and the phenol-OH group in C-terminal Tyr residue. All the products were obtained in good overall yields and characterized by related analytic data.
Based on the pseudo-dilution effect (PDE) on solid support, three cyclopeptides with an aliphatic-aryl ether bond as the bridge were synthesized via SN2 reaction between bromoacetylated at N-terminal and the phenol-OH group in C-terminal Tyr residue. All the products were obtained in good overall yields and characterized by related analytic data.
2005, 16(6): 763-766
Abstract:
(±)-Butyl ester of rosmarinic acid 1 was synthesized by 5-step reactions through the two key intermediates 2 and 3, the total yield was 23.9% and 25.1%, respectively.
(±)-Butyl ester of rosmarinic acid 1 was synthesized by 5-step reactions through the two key intermediates 2 and 3, the total yield was 23.9% and 25.1%, respectively.
2005, 16(6): 767-770
Abstract:
Dimethyl carbonate was synthesized by transesterification reaction between ethylene carbonate and methanol under supercritical conditions without any catalyst. Experimental results showed that the residence time and the molar ratio of methanol to ethylene carbonate all can affect the conversion of ethylene carbonate. When the molar ratio of methanol to ethylene carbonate was 8:1, 81.2% conversion can be achieved at 9.0 MPa and 250℃ after 8 h.
Dimethyl carbonate was synthesized by transesterification reaction between ethylene carbonate and methanol under supercritical conditions without any catalyst. Experimental results showed that the residence time and the molar ratio of methanol to ethylene carbonate all can affect the conversion of ethylene carbonate. When the molar ratio of methanol to ethylene carbonate was 8:1, 81.2% conversion can be achieved at 9.0 MPa and 250℃ after 8 h.
2005, 16(6): 771-773
Abstract:
A new bisxanthone, named bijaponicaxanthone C, was isolated from the whole plant of Hypericum japonicum. The structure was elucidated as 6-[1",5",6"-trihydroxy-2"'-(β-hydroxy-β-methylethyl)-2"',3"'-dihydrofuran(5"',4"',3 ",4")xanthone-3"'-oxyl]-1,3,5-trihydroxy-4-isoprenylxanthone (1) on the basis of the spectral and chemical evidences.
A new bisxanthone, named bijaponicaxanthone C, was isolated from the whole plant of Hypericum japonicum. The structure was elucidated as 6-[1",5",6"-trihydroxy-2"'-(β-hydroxy-β-methylethyl)-2"',3"'-dihydrofuran(5"',4"',3 ",4")xanthone-3"'-oxyl]-1,3,5-trihydroxy-4-isoprenylxanthone (1) on the basis of the spectral and chemical evidences.
2005, 16(6): 774-776
Abstract:
Two novel epimeric eremophilane sesquiterpenes, 7β-H-3α-angeloyl-9(10)-ene-11,12-epoxy-8-oxoeremophilane (1) and 7β-H-3α-angeloyl-9(10)-ene-11, 12-epoxy-8-oxoeremophilane (2) were isolated from the methanol extract of the flower of Cacalia tangutica (Franch.)Hand-Mazz. Their structures were characterized by 1D-, 2D-NMR (1H-1H COSY, HMQC,HMBC, 1H-1H NOESY) and HRESI-MS techniques.
Two novel epimeric eremophilane sesquiterpenes, 7β-H-3α-angeloyl-9(10)-ene-11,12-epoxy-8-oxoeremophilane (1) and 7β-H-3α-angeloyl-9(10)-ene-11, 12-epoxy-8-oxoeremophilane (2) were isolated from the methanol extract of the flower of Cacalia tangutica (Franch.)Hand-Mazz. Their structures were characterized by 1D-, 2D-NMR (1H-1H COSY, HMQC,HMBC, 1H-1H NOESY) and HRESI-MS techniques.
2005, 16(6): 777-780
Abstract:
A new halogenated biindole and a new apo-carotenone have been isolated from the ethanolic extract of the green alga Chaetomorpha basiretorsa Sethcell. On the basis of chemical and spectroscopic methods including 2D NMR technique, their structures have been elucidated as 4,4'-dichloro-5,5'-dibromo-7,7'-dimethoxy-2,2'-bi-1H-indole and l'S*,4'R*-8-(4'-hydroxy-2',6',6'-trimethylcyclohex-2-enyl)-6-methyloct-3E,5E,7E-trien-2-one, respectively.
A new halogenated biindole and a new apo-carotenone have been isolated from the ethanolic extract of the green alga Chaetomorpha basiretorsa Sethcell. On the basis of chemical and spectroscopic methods including 2D NMR technique, their structures have been elucidated as 4,4'-dichloro-5,5'-dibromo-7,7'-dimethoxy-2,2'-bi-1H-indole and l'S*,4'R*-8-(4'-hydroxy-2',6',6'-trimethylcyclohex-2-enyl)-6-methyloct-3E,5E,7E-trien-2-one, respectively.
2005, 16(6): 781-782
Abstract:
A new neolignan glycoside named armaoside (1) was isolated from the whole plant of Pedicularis armata Maxim. Its structure was elucidated by spectroscopic and chemical methods.Antibacterial assay showed that it has moderately antibacterial activities against Eschecichia coli,Bacillus subtilis and Staphylococcus aureus.
A new neolignan glycoside named armaoside (1) was isolated from the whole plant of Pedicularis armata Maxim. Its structure was elucidated by spectroscopic and chemical methods.Antibacterial assay showed that it has moderately antibacterial activities against Eschecichia coli,Bacillus subtilis and Staphylococcus aureus.
2005, 16(6): 783-785
Abstract:
A novel compound, named fortunate A, was isolated from the ethanol extract of the stem bark of Cryptomerica fortunei. Its structure was established on the basis of the spectral evidences including 1D and 2D NMR spectrum.
A novel compound, named fortunate A, was isolated from the ethanol extract of the stem bark of Cryptomerica fortunei. Its structure was established on the basis of the spectral evidences including 1D and 2D NMR spectrum.
2005, 16(6): 786-788
Abstract:
A new diterpene with an abietane skeleton, 3β-hydroxy-8α, 14α-epoxyabieta-11,13(15)-dien-16,12-olide, was isolated from the root of Suregada glomerulate(Blume) Baill. Its structure was elucidated on the basis of spectroscopic and X-ray crystallographic analysis.
A new diterpene with an abietane skeleton, 3β-hydroxy-8α, 14α-epoxyabieta-11,13(15)-dien-16,12-olide, was isolated from the root of Suregada glomerulate(Blume) Baill. Its structure was elucidated on the basis of spectroscopic and X-ray crystallographic analysis.
2005, 16(6): 789-792
Abstract:
β-Cyclodextrin 1 was directly oxidized to the corresponding monoaldehyde 2 on their primary faces by cyclized 2-iodoxybenzoic acid(IBX) in DMSO, followed by the synthesis of β-cyclodextrin derivatives bearing Schiff-base group 3. A new chiral stationary phase(BCDS 6)was then prepared by immobilization of β-cyclodextrin derivative with α-Schiff base group onto the surface of sillica gel. A series of compounds with amino groups were readily separated using this CSP. Methanol and acetonitrile were tested as the mobile phase while the influence of temperature and the addition of aqueous triethylammonium acetate buffer to the mobile phase was also innvestigated. Ferrocene ligand with Schiff-based groups have been separated satisfactorilly on BCDS column.
β-Cyclodextrin 1 was directly oxidized to the corresponding monoaldehyde 2 on their primary faces by cyclized 2-iodoxybenzoic acid(IBX) in DMSO, followed by the synthesis of β-cyclodextrin derivatives bearing Schiff-base group 3. A new chiral stationary phase(BCDS 6)was then prepared by immobilization of β-cyclodextrin derivative with α-Schiff base group onto the surface of sillica gel. A series of compounds with amino groups were readily separated using this CSP. Methanol and acetonitrile were tested as the mobile phase while the influence of temperature and the addition of aqueous triethylammonium acetate buffer to the mobile phase was also innvestigated. Ferrocene ligand with Schiff-based groups have been separated satisfactorilly on BCDS column.
2005, 16(6): 793-796
Abstract:
This paper described a new immunoassay method by capillary electrophoresis with enhanced chemiluminescence (CL) detection system based on luminol-hydrogen peroxide reaction catalyzed by horseradish peroxides (HRP). Using para-iodophenol as a CL enhancer, the detection limit of about 1×10-12 mol/L for HRP was achieved, which corresponded to 1.32×10-5 U/mL. In optimal conditions, the free HRP-labeled CA125 antibody (Ab*) and the bound enzyme-labeled complex (Ab*-Ag) were well separated by capillary electrophoresis within 4 min.The assay was successfully used to determine the contents of CA125 in human sera, which were associated with ovarian cancer, and the recoveries of the standard addition experiments were 96 to 109%.
This paper described a new immunoassay method by capillary electrophoresis with enhanced chemiluminescence (CL) detection system based on luminol-hydrogen peroxide reaction catalyzed by horseradish peroxides (HRP). Using para-iodophenol as a CL enhancer, the detection limit of about 1×10-12 mol/L for HRP was achieved, which corresponded to 1.32×10-5 U/mL. In optimal conditions, the free HRP-labeled CA125 antibody (Ab*) and the bound enzyme-labeled complex (Ab*-Ag) were well separated by capillary electrophoresis within 4 min.The assay was successfully used to determine the contents of CA125 in human sera, which were associated with ovarian cancer, and the recoveries of the standard addition experiments were 96 to 109%.
2005, 16(6): 797-800
Abstract:
Molecularly imprinted polymer, exhibiting considerable enantioselectivity for L-mandelic acid, was prepared using metal coordination-chelation interaction. By evaluating the recognition characteristics in the chromatographic mode, the recognition interactions were proposed:specific and nonspecific metal coordination-chelation interaction and hydrophobic interaction were responsible for substrate binding on metal-complexing imprinted polymer; while the selective recognition only came from specific metal coordination-chelation interaction and specific hydrophobic interaction.
Molecularly imprinted polymer, exhibiting considerable enantioselectivity for L-mandelic acid, was prepared using metal coordination-chelation interaction. By evaluating the recognition characteristics in the chromatographic mode, the recognition interactions were proposed:specific and nonspecific metal coordination-chelation interaction and hydrophobic interaction were responsible for substrate binding on metal-complexing imprinted polymer; while the selective recognition only came from specific metal coordination-chelation interaction and specific hydrophobic interaction.
2005, 16(6): 801-804
Abstract:
Phenyl bonded mesoporous silica (C6H5-MCM-41) was applied as the fiber coating of solid-phase microextraction (SPME). The performance of the fiber coating was discussed coupling to HPLC. Applicability of mesoporous fiber coating was examined for the determination of benzo[a]pyrene (B[a]P) in water samples, The limit of detection (LOD) is 0.28 μg·L-1. Good recovery and relative standard deviation (RSD) were obtained.
Phenyl bonded mesoporous silica (C6H5-MCM-41) was applied as the fiber coating of solid-phase microextraction (SPME). The performance of the fiber coating was discussed coupling to HPLC. Applicability of mesoporous fiber coating was examined for the determination of benzo[a]pyrene (B[a]P) in water samples, The limit of detection (LOD) is 0.28 μg·L-1. Good recovery and relative standard deviation (RSD) were obtained.
2005, 16(6): 805-808
Abstract:
Cyclic voltammetry (CV) and single-step chronocoulometry were used to study the interaction of [Ru(phen)2dppz]2+ (phen=l,10-phenanthroline; dppz=dipyrido[3,2-a:2',3',-c]phen-azine) with herring sperm DNA. The addition of DNA caused a diminution in the peak current and a positive shift in the peak potential of the complex of [Ru(phen)2dppz]2+. The 12 mV positive shift in the peak potentid of [Ru(phen)2dppz]2+ indicates that [Ru(phen)2dppz]2+ binds 2.6 times more strongly to DNA than its reductive form. In addition, by using fluorimetric and UV-spectrophotometric methods and studies of denatured DNA and the effect of NaCl solution, it was also found that the binding mode was intercalation. The decrease of peak current is proportional to the concentration of DNA, which can be applied to estimate DNA concentration.
Cyclic voltammetry (CV) and single-step chronocoulometry were used to study the interaction of [Ru(phen)2dppz]2+ (phen=l,10-phenanthroline; dppz=dipyrido[3,2-a:2',3',-c]phen-azine) with herring sperm DNA. The addition of DNA caused a diminution in the peak current and a positive shift in the peak potential of the complex of [Ru(phen)2dppz]2+. The 12 mV positive shift in the peak potentid of [Ru(phen)2dppz]2+ indicates that [Ru(phen)2dppz]2+ binds 2.6 times more strongly to DNA than its reductive form. In addition, by using fluorimetric and UV-spectrophotometric methods and studies of denatured DNA and the effect of NaCl solution, it was also found that the binding mode was intercalation. The decrease of peak current is proportional to the concentration of DNA, which can be applied to estimate DNA concentration.
2005, 16(6): 809-811
Abstract:
The electroosmotic pump (EOP) using nanosilica particles packed-bed column was experimentally studied. The relationship between flowrate, pressure and applied voltage of the pump, and pressure-flowrate (P-Q) characteristic were investigated.
The electroosmotic pump (EOP) using nanosilica particles packed-bed column was experimentally studied. The relationship between flowrate, pressure and applied voltage of the pump, and pressure-flowrate (P-Q) characteristic were investigated.
2005, 16(6): 812-814
Abstract:
Matrix assisted laser desorption ionization time of flight mass spectrometry(MALDI-TOF-MS, model AXIMA CFR+) was used to analyze galactosyl-HSA (human serum albumin) synthesized in our laboratory. It clearly showed that HSA covalently combined with galactoses. Galactosyl-HSA is pure and the ratio of galactosyl residues to protein is 48:1.
Matrix assisted laser desorption ionization time of flight mass spectrometry(MALDI-TOF-MS, model AXIMA CFR+) was used to analyze galactosyl-HSA (human serum albumin) synthesized in our laboratory. It clearly showed that HSA covalently combined with galactoses. Galactosyl-HSA is pure and the ratio of galactosyl residues to protein is 48:1.
2005, 16(6): 815-818
Abstract:
Based on the enhancement of resonance light scattering (RLS) of m-nitrophenylfluorone-Mo(Ⅵ) complex by protein, a novel method for protein microdetermination in Tween 20 microemulsion has been developed. Under optimum condition, the linear ranges of bovine serum albumin are 0~0.03 μg·mL-1 with detection limits of 3.10 ng·mL-1. Most of amino acids and metal ions do not interfere. The method can be applied to determination of residual protein in penicillin Na salt and penicillin G potassium salt samples with satisfactory results.
Based on the enhancement of resonance light scattering (RLS) of m-nitrophenylfluorone-Mo(Ⅵ) complex by protein, a novel method for protein microdetermination in Tween 20 microemulsion has been developed. Under optimum condition, the linear ranges of bovine serum albumin are 0~0.03 μg·mL-1 with detection limits of 3.10 ng·mL-1. Most of amino acids and metal ions do not interfere. The method can be applied to determination of residual protein in penicillin Na salt and penicillin G potassium salt samples with satisfactory results.
2005, 16(6): 819-822
Abstract:
The activity of lignin peroxidase (LiP) in reversed micelles of polyoxyethylene lauryl ether (Brij30) changed with the molar ratio of water to the surfactant and the denaturant concentration of guanidinium chloride. At low water contents the activity of LiP could be enhanced by the denaturant at moderate concentration. This phenomenon, together with the spectral characteristics of the intrinsic fluorescence of LiP, suggested that the conformation of the active center of LiP was flexible.
The activity of lignin peroxidase (LiP) in reversed micelles of polyoxyethylene lauryl ether (Brij30) changed with the molar ratio of water to the surfactant and the denaturant concentration of guanidinium chloride. At low water contents the activity of LiP could be enhanced by the denaturant at moderate concentration. This phenomenon, together with the spectral characteristics of the intrinsic fluorescence of LiP, suggested that the conformation of the active center of LiP was flexible.
2005, 16(6): 823-826
Abstract:
The morphologies and the microstructures of the dispersed particles of the cubic phase,which were formed by precursor method, were studied. The freeze-fracture TEM clearly showed that the aqueous dispersed particles have irregular cubic shapes. X-ray diffraction technique has been utilized to study the microstructure of the particles and it was found that these particles still retained the cubic character. The sizes of the particles were measured by dynamic light scattering,and the results showed that the sizes of the dispersed particles were between 200~400 nm under different conditions.
The morphologies and the microstructures of the dispersed particles of the cubic phase,which were formed by precursor method, were studied. The freeze-fracture TEM clearly showed that the aqueous dispersed particles have irregular cubic shapes. X-ray diffraction technique has been utilized to study the microstructure of the particles and it was found that these particles still retained the cubic character. The sizes of the particles were measured by dynamic light scattering,and the results showed that the sizes of the dispersed particles were between 200~400 nm under different conditions.
2005, 16(6): 827-830
Abstract:
The nanoporous TiO2 film electrodes have been prepared by a sol-gel deposition process.The photostability of the electrodes in basic solutions has been studied. The results show that the photostability of the electrodes decreases rapidly in strong basic solutions with or without methanol. The reaction of holes to Oad2- produces active Oad- atoms and the products Oad- atoms oxidize Ti3+ to Ti4+ on TiO2 film surface and subsurface. This results in the TiO2 film electrodes unstable in basic solutions both without methanol and with too low concentration.
The nanoporous TiO2 film electrodes have been prepared by a sol-gel deposition process.The photostability of the electrodes in basic solutions has been studied. The results show that the photostability of the electrodes decreases rapidly in strong basic solutions with or without methanol. The reaction of holes to Oad2- produces active Oad- atoms and the products Oad- atoms oxidize Ti3+ to Ti4+ on TiO2 film surface and subsurface. This results in the TiO2 film electrodes unstable in basic solutions both without methanol and with too low concentration.
2005, 16(6): 831-834
Abstract:
Soap-free P(MMA-EA-MAA) particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and methacrylic acid (MAA), and large voids inside the particles were generated by alkali posttreatment in the presence of 2-butanone. Results indicated that the size of void and the particle volume were related with the amount of 2-butanone. The generation mechanism of voids was proposed.
Soap-free P(MMA-EA-MAA) particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and methacrylic acid (MAA), and large voids inside the particles were generated by alkali posttreatment in the presence of 2-butanone. Results indicated that the size of void and the particle volume were related with the amount of 2-butanone. The generation mechanism of voids was proposed.
2005, 16(6): 835-838
Abstract:
The aggregation and fractal structure of mixed metal hydroxides (MMH) agglomerates with increasing ionic strength have been studied by dynamic light scattering (DLS) and SEM techniques. The experiments indicate that the MMH agglomerates have two different structures in RLA regime and DLA regime, and also give the proof that the transition region between RLA and DLA may occur.
The aggregation and fractal structure of mixed metal hydroxides (MMH) agglomerates with increasing ionic strength have been studied by dynamic light scattering (DLS) and SEM techniques. The experiments indicate that the MMH agglomerates have two different structures in RLA regime and DLA regime, and also give the proof that the transition region between RLA and DLA may occur.
2005, 16(6): 839-842
Abstract:
This paper reports observations of significant synergistic effects between dielectric barrier discharge (DBD) plasmas and Cu-ZSM-5 catalysts for C2H4 selective reduction of NOx at 250℃ in the presence of excess oxygen by using a one-stage plasma-over-catalyst (POC) reactor.With the reactant gas mixture of 530 ppm NO, 650 ppm C2H4, 5.8% O2 in N2 and GHSV=12000 h-1, the pure catalytic, pure plasma-induced (discharges over fused silica pellets) and plasmacatalytic (in the POC reactor) NOx conversion are 39%, 1.5% and 79%, respectively. The in-situ optical emission spectra of the reactive systems imply some short-lived active species formed from plasma-induced and plasma-catalytic processes may be responsible to the observed synergistic effects in this one-stage POC system.
This paper reports observations of significant synergistic effects between dielectric barrier discharge (DBD) plasmas and Cu-ZSM-5 catalysts for C2H4 selective reduction of NOx at 250℃ in the presence of excess oxygen by using a one-stage plasma-over-catalyst (POC) reactor.With the reactant gas mixture of 530 ppm NO, 650 ppm C2H4, 5.8% O2 in N2 and GHSV=12000 h-1, the pure catalytic, pure plasma-induced (discharges over fused silica pellets) and plasmacatalytic (in the POC reactor) NOx conversion are 39%, 1.5% and 79%, respectively. The in-situ optical emission spectra of the reactive systems imply some short-lived active species formed from plasma-induced and plasma-catalytic processes may be responsible to the observed synergistic effects in this one-stage POC system.
2005, 16(6): 843-845
Abstract:
Using glycerol, glycol and water as solvent, cetyltrimethylammonium bromide (CTAB)as template, tetraethyl orthosilicate (TEOS) as silica source, ethylenediamine (EDA) as base source,mesoporous molecular sieve MCM-41 has been synthesized at room temperature, characterized by X-ray power diffraction and N2 adsorption. Compared with the samples synthesized by glycol and water, the samples synthesized by glycerol have larger pore diameter and high surface areas.Thus glycerol is an efficient solvent for preparing larger pore mesoporous MCM-41.
Using glycerol, glycol and water as solvent, cetyltrimethylammonium bromide (CTAB)as template, tetraethyl orthosilicate (TEOS) as silica source, ethylenediamine (EDA) as base source,mesoporous molecular sieve MCM-41 has been synthesized at room temperature, characterized by X-ray power diffraction and N2 adsorption. Compared with the samples synthesized by glycol and water, the samples synthesized by glycerol have larger pore diameter and high surface areas.Thus glycerol is an efficient solvent for preparing larger pore mesoporous MCM-41.
2005, 16(6): 846-848
Abstract:
Five ruthenium complexes such as Phen-Ru-Phen, Phen-Ru-Bipy, Phen-Ru-Quin,Quin-Ru-Quin and Bipy-Ru-Quin (where Phen=1, 10-phenanthroline, Quin=8-hydroxyquinoline,Bipy=2, 2'-bipyridine) were synthesized and used as catalysts for the oxidation of benzylic and primary aliphatic alcohols with iodosylbenzene as oxidant. The oxidations were carried out at room temperature, affording the corresponding aldehydes and ketones with high selectivity.
Five ruthenium complexes such as Phen-Ru-Phen, Phen-Ru-Bipy, Phen-Ru-Quin,Quin-Ru-Quin and Bipy-Ru-Quin (where Phen=1, 10-phenanthroline, Quin=8-hydroxyquinoline,Bipy=2, 2'-bipyridine) were synthesized and used as catalysts for the oxidation of benzylic and primary aliphatic alcohols with iodosylbenzene as oxidant. The oxidations were carried out at room temperature, affording the corresponding aldehydes and ketones with high selectivity.
2005, 16(6): 849-852
Abstract:
The steady ordered micro-ribbons of oxidized multi-walled carbon nanotubes (MWNTs)were obtained through micro-aperture PTFE membrane by vacuum filtration. After treatment by mixture of concentrated nitric acid and sulfuric acid, the surface functional groups modified MWNTs can be easily dispersed to form a homogeneous suspension. It is found that the steady micro-ribbons existed in the films obtained by vacuum filtration of the suspension. The filtration formed steady flow field and induced steady alignment of oxidized MWNTs. The chemical treatment of MWNTs forming strong interaction between MWNTs is necessity to keep steady of the micro-ribbons microstructure.
The steady ordered micro-ribbons of oxidized multi-walled carbon nanotubes (MWNTs)were obtained through micro-aperture PTFE membrane by vacuum filtration. After treatment by mixture of concentrated nitric acid and sulfuric acid, the surface functional groups modified MWNTs can be easily dispersed to form a homogeneous suspension. It is found that the steady micro-ribbons existed in the films obtained by vacuum filtration of the suspension. The filtration formed steady flow field and induced steady alignment of oxidized MWNTs. The chemical treatment of MWNTs forming strong interaction between MWNTs is necessity to keep steady of the micro-ribbons microstructure.
