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  • Author or Editor: Tao Wang x
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Although significant progress has been made on Agrobacterium -mediated wheat transformation, the current methodologies use immature embryos as recipient tissues, a process which is labor intensive, time consuming and expensive. In this study, we have managed to develop an Agrobacterium -based transformation scheme using explants derived from mature embryos. Based on transient expression of β -glucuronidase (GUS) marker, mature embryo halves prepared from freshly imbibed seeds were generally most susceptible to Agrobacterium -mediated T-DNA transfer. According to the results of callus induction and shoot production, Yumai 66 and Lunxuan 208 showed higher selection and regeneration efficiency than Bobwhite. In line with this finding, fertile T 0 transgenic plants were most readily obtained for both spring and winter wheat when mature embryo halves were used for co-inoculation by Agrobacterium cells. The presence of the antibiotic selection marker ( nptII , encoding neomycin phosphotransferase II) in the T 0 plants was revealed by both genomic PCR amplification and the enzyme-linked immunosorbent assay (ELISA). Additional analysis showed that the transgene was stably inherited from the two different generations and segregated normally among the T 1 progenies. Further development along this line will raise the efficiency of wheat transformation and increase the use of this approach in the molecular breeding of wheat crop.

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In traditional Chinese medicine, plants of the genus Peganum have been used to treat cough, hypertension, diabetes, asthma, jaundice, lumbago, and many other ailments. In this study, seeds of the plants of genus Peganum, including P. harmala Linn., P. multisectum (Maxim) Bobr, P. nigellastrum Bunge, and Peganum variety were collected from different provinces in China. A simple, rapid, and effective thin-layer chromatographic (TLC) fingerprint combined with bioautographic technique has been established for the identification of acetylcholinesterase (AChE) inhibitors from these seeds. The methanol extracts of seeds were separated on silica gel plates with ethyl acetate-methanol-ammonia 10:1.5:0.5 (ν/ν) as mobile phase, and then the plates were inspected under UV 366 nm and visualized by spraying with both Dragendorff’s and vanillin-sulfuric acid reagents as well as by bioautographic assay. Moreover, the limits on AChE inhibitive activity of harmine and harmaline were found to be 0.01 μg, in comparison to that of galanthamine of also 0.01 μg. The TLC fingerprints combined with the bioautographic method could distinguish the seeds of the different species of genus Peganum investigated. Moreover, harmine and harmaline displayed similar AChE inhibition compared to galanthamine.

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A radioactive multitracer solution was prepared from the reaction of selenium with 25 MeV/nucleon40Ar ions. Using off-line -ray spectrometry, the solution containing 47 radioactive isotopes of 24 elements was obtained. The nucleide with the longest half-life was22Na, and the shortest-lived one was81Rb8.

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The stability constants for tracer concentrations of Co(II) complexes with the red earth fulvic acid were determined at pH 3.8–6.8 and ionic strength 0.0010–1.0 mol/l by using the cation exchange equilibrium method and the radiotracer60Co. The effects of ionic strength and pH on the stability constants of 1∶1 Co(II) complexes were investigated, and it was found that the stability constants of complexes of humic substances do not vary with ionic strength and pH in a manner similar to that of simple complexes.

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The stability constants for tracer concentrations of Co(II) complexes with both the red earth humic and fulvic acids were determined at pH 5.9 and ionic strength 0.010 mol/l by using theArdakani-Stevenson cation exchange equilibrium method and the radiotracer60Co. It was found that the 1:1 complexes of Co(II) with the red earth humic and fulvic acids were formed and that the average values of logβ (stability constant) of humic and fulvic acid complexes were 5.76±0.19 and 4.42±0.03, respectively.

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Herein, the sorption properties of Eu(III) on Na-attapulgite were performed by using batch sorption experiments under different experimental conditions, such as contact time, pH, ionic strength, humic acid and temperatures. The results indicated that the sorption of Eu(III) on Na-attapulgite was strongly dependent on pH and temperature. At low pH values, the sorption of Eu(III) was influenced by ionic strength, whereas the sorption was not affected by ionic strength at high pH values. The sorption of Eu(III) was mainly dominated by ion exchange or outer-sphere surface complexation at low pH values, and by inner-sphere surface complexation or surface precipitation at high pH values. The sorption of Eu(III) onto Na-attapulgite increased with increasing temperature. The Langmuir and Freundlich models were applied to simulate the sorption isotherms, and the results indicated that the Langmuir model simulated the sorption isotherms better than the Freundlich model. The thermodynamic parameters (∆G o, ∆S o, ∆H o) were calculated from the temperature dependent sorption isotherms at 293, 313 and 333 K, respectively, and the results indicated that the uptake of Eu(III) on Na-attapulgite was an endothermic and spontaneous process. The results of high Eu(III) sorption capacity on Na-attapulgite suggest that the attapulgite is a suitable material for the preconcentration and immobilization of Eu(III) ions from large volumes of aqueous solutions.

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The distribution coefficients,K d of 36 elements from Na to Bi on a silica were determined at pH 4, 7, 9 and in the absence and presence of fulvic acid (FA) using a multitracer technique. The multitracer solution was prepared by irradiation of Th(NO3)4 with 40Ar ion beam. The effects of pH and fulvic acid on the K d values of 36 elements were studied. It was found that the sequences of the K d values of alkali elements (Cs>Rb>K>Na) and of alkaline earth elements(Ba>Ca>Mg) in the absence of FA can be qualitatively explained in terms of chemical bond formation and hydration. Various effects of pH and the negative or positive effect of FA on the adsorption of 36 elements were observed and are probably related to the species of 36 elements in the aqueous solutions containing CO3 2–, OH, Cl and FA. For most of the elements studied here the K d values are increased with increasing pH and are decreased with adding FA.

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A series of Ag-doped Ag–V/TiO2 catalysts with low vanadium loadings were prepared by one-step sol–gel methods and the effects of the Ag doping on the selective catalytic reduction (SCR) of NOx with NH3 were investigated. The catalytic activity of the catalysts increased about 20% by the addition of 1–3 wt% of Ag. The catalysts were characterized by XRD and H2-TPR. The results indicated that the V and Ag were well dispersed on the TiO2 support and the Ag doping inhibited the growth of TiO2 anatase crystallite and improved the oxidation ability of adsorption sites. The reduction temperature of vanadium oxide decreased and the activity for NH3-SCR enhanced. The doped Ag also had NH3-SCR activity, but it was very low. The durability of the catalysts was acceptable and the resistance to H2O was not very good. The effects of the calcination temperature and GHSV were also investigated; it was found that the optimal calcination temperature was 450 °C and the GHSV should not be higher than 48,000 h−1.

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Multiwalled carbon nanotubes (MWCNTs) have attracted multidisciplinary study because of their unique physicochemical properties. Herein, the sorption of U(VI) from aqueous solution to oxidized MWCNTs was investigated as a function of contact time, pH and ionic strength. The results indicate that U(VI) sorption on oxidized MWCNTs is strongly dependent on pH and ionic strength. The sorption of U(VI) is mainly dominated by surface complexation and cation exchange. The sorption of U(VI) on oxidized MWCNTs is quickly to achieve the sorption equilibrium. The sorption capacity calculated from sorption isotherms suggests that oxidized MWCNTs are suitable material in the preconcentration and solidification of U(VI) from large volumes of aqueous solutions.

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The stability of the inclusion complex of β-CD with cinnamic aldehyde was investigated by means of TG and DSC. The mass loss takes place in three stages: dehydration occurs at 50–120°C; dissociation of β-CD·C9H8O proceeds in the range 200–260°C; and decomposition of β-CD begins at 280°C. The kinetics of the dissociation of β-CD·C9H8O was studied by means of thermogravimetry both at constant temperature and with linearly increasing temperature. The results demonstrate that the dissociation of β-CD·C9H8O is dominated by a one-dimensional diffusion process. The activation energyE is 160 kJ mol−1, and the pre-exponential factorA is 5.8×1014 min−1. Scanning electron microscope observations and the results of crystal structure analysis are in good agreement with those of thermogravimetry.

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