The application of macroporous resins in the separation of licorice flavonoids and glycyrrhizic acid

Glycyrrhizic acid (GA) and licorice flavonoids (LF) are the two classes of bioactive components in licorice with known pharmacological effects. But long-term excessive intake of GA may cause sodium retention and hypertension. In this study, the performance and adsorption characteristics of four widely used macroporous resins for the separation of deglycyrrhizinated, flavonoids enriched licorice has been critically evaluated. The sorption and desorption properties of LF and GA on macroporous resins including XDA-1, LSA-10, D101 and LSA-20 have been compared. The adsorption capacity was found to depend strongly on the pH of the feed solution. XDA-1 offers much higher adsorption capacity for GA and LF than other resins, and its adsorption data fit the best to the Freundlich isotherm. XDA-1 also shows much higher adsorption affinity towards LF than that of GA based on calculated results from the measured adsorption isotherms. Dynamic adsorption and desorption experiments have been carried out on a XDA-1 resin packed column to obtain optimal parameters for separating GA and LF. An enriched LF extract (about 21.9% purity) free of GA, and an enriched GA extract with 66% purity can be separated from crude licorice extract in one run.     

Nontrivial Q2-Dependence in the Gottfried Sum Induced by Nonperturbative Effect

In consideration of the lowest dimensional condensate contributions to the free quark propagator, we obtain the nonperturbative quark propagator with the nonvanishing vacuum average value for quark composite operator (|qq|), Using the -corrected quark propagator and basing on the simple quark-parton model, we discuss the nonperturbative effect in the nucleon structure function. It is shown that the nonperturbative effect modifies the conventional quark-parton model formula of the nucleon structure function at finite Q² and suggests a nontrivial Q²-dependence in the Gottfried sum.     

One-dimensional Rhodium-nickel Alloy Assemblies with Nano-dendrite Subunits for Alkaline Methanol Oxidation

The noble metal rhodium(Rh)nanostructures have wide applications in catalysis and electrocataly-sis.In this work,a series of RhNi alloy nanostructures with diff...     

Quantification of acetylcholine in microdialysate of subcutaneous tissue by hydrophilic interaction chromatography/tandem mass spectrometry

It has recently been suggested that acetylcholine plays an important role in the modulation of tissue inflammation. In order to further understand the newly discovered cholinergic anti-inflammatory pathway, tracking the concentration changes of acetylcholine in tissue is required. This paper describes the development of a method coupling hydrophilic interaction chromatography with electrospray ionization tandem mass spectrometry (HILIC/ESI-MS/MS) for the separation and quantification of acetylcholine in microdialysis samples of normal rats and of rats with local inflammation. The separation of acetylcholine from interferential endogenous compounds and inorganic cations was achieved with a zwitterionic stationary phase column using isocratic elution. Low-energy collision-induced dissociation tandem mass spectrometric (CID-MS/MS) analysis was carried out in the positive ion mode using multiple reaction monitoring (MRM) of the following mass transitions: m/z 146 --> 87 for acetylcholine and m/z 155 --> 87 for the internal standard acetylcholine-D9. The limit of detection for acetylcholine was found to be 0.075 fmol on-column with a signal-to-noise ratio of 3:1. The lower limit of quantification was 0.25 fmol on-column. The calibration curves obtained for acetylcholine in blank microdialysates were linear in the ranges of 0.025-50 nM and 0.025-0.5 nM, with correlation coefficients equal to or greater than 0.9994 and 0.9969, respectively. The recoveries of acetylcholine for high (2 nM) and low (0.5 nM) concentrations were in the ranges of 90-96% and 95-109%, respectively. The coefficients of variation for intra-day and inter-day reproducibility were equal to or less than 7.3% and 10.4%, respectively. The method has been successfully applied in the measurement of acetylcholine in microdialysates from normal and inflamed rat tissue.     

Determination of total dietary fiber in selected foods containing resistant maltodextrin by a simplified enzymatic-gravimetric method and liquid chromatography: interlaboratory study in China

An interlaboratory study was conducted in China to validate the modified AOAC Official Method 2001.03 for the determination of total dietary fiber (TDF) in foods containing resistant maltodextrin (RMD), which will be adopted as the National Standard Method of China. The kind of buffer solution, the volume of filtrate evaporation, the volume of eluent for desalting and residual solution after evaporation, etc. were modified, which had been proved to have acceptable accuracy and precision in the routine assay. TDF contents in 3 representative foods and 2 kinds of RMD ingredient (i.e., NUTRIOSE 06 and NUTRIOSE 10) were measured using the modified method in 6 eligible laboratories representing commercial, industrial, and governmental laboratories in China. The results of the interlaboratory study indicated that the intralaboratory repeatability, interlaboratory reproducibility, and precision of the modified method are adequate for reliable analysis of TDF in food containing RMD, as well as resistant dextrin. Compared to AOAC Official Method 2001.03, the modified method is time- and cost-saving.     

北京正负电子对撞机上QCD的精确检验

广义的Crewther关系式可以把正负电子湮没过程中强子产生的分支比R=σ(e⁺e^－→强子)/σ(e⁺e^－→μ⁺μ^－),同轻子核子深度非弹性散射中的Bjorken求和规则和Gross-UewellynSmith求和规则联系起来,提供一个没有标度和重整化方案任意性的有关量子色动力学(QCD)物理量的基本关系式.强子产生分支比R可以在升级后的北京正负电子对撞机或τ–粲工厂上进行精确的测量,从而提供对QCD的精确检验.     

Property of defect and sensitive light-induced phenomena in GeSbS glasses

Photo-induced ESR in Ge₄₂S₅₈ glass and those with a small amount of Sb₂S₃ can be observed even at 100°C. After the cease of exposure, photo-induced spin decays very slowly at room temperature, but it grows very slowly at 77 K. The decay of the photo-induced spin does not correspond to the decay of photo-induced current. These results are explained by a model where the light exposure makes a certain fraction of defects with negative effective electron correlation energy transform to defects with positive one.     

On a nonlocal problem for a confined plasma in a Tokamak

The paper deals with a nonlocal problem related to the equilibrium of a confined plasma in a Tokamak machine. This problem involves terms u′_* (|u > u(x)|) and |u > u(x)|, which are neither local, nor continuous, nor monotone. By using the Galerkin approximate method and establishing some properties of the decreasing rearrangement, we prove the existence of solutions to such problem.