Application of preparative high-speed counter-current chromatography for separation of methyl gallate from Acer truncatum Bunge

Preparative separation of methyl gallate in leaves extract of Acer truncatum Bunge was conducted using high-speed counter-current chromatography (HSCCC) with a solvent system composed of ethyl acetate-ethanol-water at volume ratios of 5:1:5 (v/v/v). In a single operation, 57.5 mg of methyl gallate was obtained from 120 mg of the extract. HPLC analyses of the counter-current chromatography (CCC) fraction revealed that the methyl gallate was having over 97% purity. Its structure was identified by 1H NMR and 13C NMR.     

Use of k0 concept to corrections for interferences from fissionable nuclides in reactor NAA

A neutron spectrum-independent compound nuclear constant, Ik_o, is proposed for fission interference corrections in reactor NAA by parametric method. Ik₀ values for eight major fission interference cases, belonging to three different types, have been determined in six irradiation positions (with _th/ _e 13,7–134) of three research reactors in our Institute. The general agreement among experimental Ik₀ 's from different irradiation positions and between experimental and calculated Ik₀ values for the same interference case verifies the validity of the method. Calculated Ik₀ values for all the possible fission interferences are tabulated. Interferences from²³⁸U(n,) and²³²Th(n,) reactions and reactor fast neutron induced²³⁸U(n, f) and²³²Th(n, f) reactions are discussed.     

Constituents from Rubia Ustulata Diels and R. Yunnanensis Diels and Their Antiplatelet Aggregation Activity

A new anthraquinone glycoside, rubiayannone‐A ( 1 ), and a new coumarin, rubilatin‐A ( 2 ), together with twenty‐two known compounds were isolated and characterized from the roots of Rubia ustulata. A new anthraquinone, 2‐carbomethoxyanthraquinone ( 3 ), and rubiayannone‐A, 2‐formylanthraquinone were obtained from the roots of R. yunnanensis. The structures of those compounds were elucidated by spectroscopic methods. The antiplatelet aggregation activity of the isolated compounds 1, 4～6 were also discussed.     

Synthesis and Crystal Structure of Organocobalt(III) Complexes with Secondary Alkyls or Bulky Schiff Base Equatorial Ligands

Alkylcobalt(III) Schiff base B(12) model complexes with secondary alkyls or a bulky diamine in the equatorial position were synthesized and characterized. Structures have been first determined by X-ray diffraction analysis for i-C(4)H(9)Co(salen)(gamma-pic) (I), n-C(3)H(7)Co(salen)(gamma-pic) (II) and C(2)H(5)Co(SB) (III), where salen = N,N'-ethylenebis(salicylideneamine) dianion; SB = 1,1,2,2-tetramethyl-N,N'-ethylenebis(salicylideneamine) dianion, gamma-pic = gamma-picoline. Crystal data for I (CoC(26)N(3)O(2)H(30)): space group P2(1)/c with a = 6.661(5) ?, b = 18.612(2) ?, c = 19.533(3) ?, beta = 98.93(1) degrees, V = 2392.10 ?(3), D(calcd) = 1.320 g.cm(-3), Z = 4, and R = 0.048 for 4469 measured reflections. Crystal data for II (CoC(25)N(3)O(2)H(28)): space group P2(1)/c, a = 9.609(6) ?, b = 19.169(8) ?, c = 12.995(9) ?, beta = 106.9(7) degrees, V = 2290.4 ?(3), D(calcd) = 1.332 g.cm(-1), Z = 4, and R = 0.048 for 4358 measured reflections. Crystal data for III (CoC(22)N(2)O(2)H(27)): space group P2(1)/c, a = 8.318(3) ?, b = 21.579(2) ?, c = 11.572(2) ?, beta = 93.35(1) degrees, V = 2073.7 ?(3), D(calcd) = 1.314 g.cm(-1), Z = 4, and R = 0.060 for 3954 measured reflections. The crystal structure data reveal that complexes I and II display six-coordinate octahedral geometry; their Co-C, Co-N bond lengths, as well as the Co-C-C angles, are very close to those in 5'-deoxyadenosylcobalamin. Complex III is one of the very few compounds having five-coordinate square pyramidal geometry and observed instability of the Co-C bond.     

Quantitative analysis of 23-hydroxybetulinic acid in mouse plasma using electrospray liquid chromatography/mass spectrometry

23-Hydroxybetulinic acid is a newly isolated derivative of betulinic acid. The agent exhibits potential anti-tumor activity and functions in this regard via apoptosis. In support of pharmacokinetic and toxicological evaluations, a new assay based on liquid chromatography/mass spectrometry (LC/MS) was developed for the quantitative analysis of 23-hydroxybetulinic acid. Sample preparation consisted of extraction of the plasma by the addition of methylene chloride followed by centrifugation. Aliquots of the supernatant were analyzed using an isocratic reversed-phase high-performance liquid chromatography (HPLC) system coupled to a negative ion electrospray mass spectrometer. Molecules of 23-hydroxybetulinic acid and the internal standard limonin were detected using selected ion monitoring at m/z 471 and 469, respectively. The limit of detection of 23-hydroxybetulinic acid was 0.05 pg (0.11 fmol) injected on-column (10 pg/mL, 5 microL injection volume), and the limit of quantitation was 10 pg (21.19 fmol, 2 ng/mL, 5 muL injection volume). 23-Hydroxybetulinic acid was stable in plasma samples at -20 degrees C for at least 3 weeks. The intra-day and inter-day coefficients of variation of the assay were 3.0 and 4.8%, respectively. The utility of the assay was demonstrated by measuring 23-hydroxybetulinicacid in mouse plasma following intragastric administration (IG) in vivo. Pharmacokinetic parameters were calculated using the 3P97 pharmacokinetic software package. A two-compartment, first-order model was selected for pharmacokinetic modeling. The result showed that after IG of 200 mg/kg 23-hydroxybetulinic acid, the plasma concentrations reached peaks at 2 h with C(max) of 3.1 microg/mL. The 200 mg/kg 23-hydroxybetulinic acid suspension IG doses were found to have long elimination half-lives of 25.6 h and low bioavailability of 2.3%. No interference was noted due to endogenous substances. These analytical methods should be of value in future studies related to the development and characterization of 23-hydroxybetulinic acid.     

Titania membrane preparation with chemical stability for very hash environments applications

The high-quality tubular titania MF membranes are successfully prepared by dip-coating techniques and systematically investigated with regard to their corrosive resistances. The experiments show that dispersants PAA and anatase powder were preferably employed to prepare desired suspensions with solid loading 10–15 wt.% and that suspensions properties significantly affect the final membranes quality. The titania MF membranes with pure water permeability 742.42 l m⁻² h⁻¹ bar⁻¹ and 0.1 μm pore diameter have been obtained using the prepared suspensions. The corrosion resistance of titania membranes exhibits that the anatase layers are more stable than the alumina supports in boiling corrosive medium and that the poor quality titania MF membranes become more deteriorated due to its top layer pore blockages and fouling layer formation, which provides a wide range of practical application fields in very hash environments with reliable data supports.     

邻氨基酚电聚合膜的研究

在酸性溶液中, 邻氨基酚(OAP)可电聚合成均匀的活性聚邻氮基酚膜(POAP), 膜有致密结构和“张开”结构。POAP膜的主要结构形式为: 与Ni~(2+)络合后, 形成POAP—Ni~(2+)膜, 其主要结构形式为:     

苯胺在银和金电极上的表面增强拉曼光谱

聚苯胺作为性能较好的导电高聚物有很大的应用潜力,有关其聚合和导电机理的研究受到广泛重视。表面增强拉曼光谱(SERS)能现场(in situ)检测表面吸附分子、提     

PREPARATION AND CHARACTERIZATION OF ION EXCHANGE MEMBRANES BASED ON POLYVINYLIDENE FLUORIDE

 A new ion exchange membrane based on polyvinylidene fluoride (PVDF) and sulfonated poly(styrene- divinylbenzene) was prepared by in-situ polymerization. The incorporation of sulfonic groups into the polyvinylidene fluoride composite membrane was confirmed by infrared spectroscopy (IR), ion exchange capacity (IEC) and energy dispersive X-ray analysis (EDAX). Area resistance, IEC and water uptake of the treated membrane were evaluated. When 20% of the crosslinked membrane was sulfonated at 80°C for 22 h, the PVDF ion exchange membrane can attain 0.8 Ω·cm²area resistance in NaCl aqueous solution at 25℃, IEC is as high as 2.43 millimoles per gram of the wet membrane. The hydrophilicity of PVDF membrane is also significantly improved after treatment. When 60% of crosslinked membrane was sulfonated at 80 ℃ for 6 h, water uptake of the treated membrane can attain 64.7%.     

DNAzyme amplification of molecular beacon signal

This paper reports an improved catalytic molecular beacon. Addition of the target oligonucleotide activates a DNA enzyme (DNAzyme), which, in turn, activates multiple copies of molecular beacons (MB) and gives rise to a strong fluorescence signal. In a previous design, the activated DNAzyme could oligomerize, especially dimerize, and result in inactivation of the DNAzyme. The current design avoids this problem, upon activated by the target DNA, the DNAzyme will stay constantly active. With the improved method, a detection of 10 pM DNA has been demonstrated, which is 1000 times more sensitive than the method previously reported.