Chai Zhifang

Combination of synchrotron radiation X-ray fluorescence with isoelectric focusing for study of metalloprotein distribution in cytosol of hepatocellular carcinoma and surrounding normal tissues

The combined use of synchrotron radiation X-ray fluorescence (SRXRF) and isoelectric focusing (IEF) has been developed that allows comparison of the distribution of metal-containing proteins in cytosol of human hepatocellular carcinoma (HCC) with its surrounding “normal” tissues. Proteins in samples from two individuals were separated with thin layer IEF, and the contents of Fe, Cu and Zn in protein bands were determined with SRXRF after drying the IEF gel. The results show that the metal-containing proteins in these samples of hepatocellular cytosol are specific for a given patient, and the distribution patterns of metal-containing proteins are distinguishable between the HCC and “normal” tissues. The technique has the advantages of quantifying trace elements and identifying proteins simultaneously.

Mercury speciation and mercury-binding protein study by HPLC-ICP-MS on the estimation of mercury toxicity between maternal and infant rats

A comparative study of methylmercury (MeHg) metabolism and its conversion into inorganic mercury (I-Hg) in organic tissues (brain, liver and kidney) and the subcellular fractions (nucleus, mitochondrion, lysosome, microsome and cytosol) of maternal and infant rats after infant in utero and lactational exposure to methylmercury was achieved by extraction preconcentration with HPLC-ICP-MS determination. The quantification of Hg-containing proteins in brain cytosol was studied by HPLC hyphenated on-line isotope dilution ICP-MS and the proteins were analyzed by SDS-PAGE and MALDI-TOF-MS. The results demonstrated that the methods could be successfully used in the study of mercury species in sub-compartments of organ cells. The study showed that the distribution patterns of MeHg and I-Hg in the levels of organs, the subcellular fractions of organs and proteins are all significantly different between mothers and their offspring, indicating their significantly different metabolism, transportation and accumulation behavior of mercury species, which may be all involved in the toxic mechanism of mercury for adults and young children.

Determination of rare earth elements in plant protoplasts by MAA

A preliminary study on the speciation of rare earth elements in plant cells has been carried out by molecular activation analysis (MAA). Mesophyll protoplasts ofBrassica napus were isolated by enzymatic digestion. After being washed with isosmotic solution containing EDTA for several times, the protoplasts were purified by gradient centrifugation. Then the concentration of rare earth elements (REEs) in the protoplasts was determined by neutron activation analysis. The result shows that REEs can enter the cells of the plant.

Magmatic evolution of Okinawa Trough during its early spreading stage

The Okinawa Trough is different from other typical backarc spreading basins because the, acidic volcanic rock (pumice) is extensively distributed in it. Systematic mineralogical and petrochemical study on a representative core (Z14–5) to characterize the magmatic evolution of the Trough during its early spreading stage showed that the pumice magma was originally from the mantle, but underwent full crystallization differentiation and was possibly contaminated by crust-derived material. With time, the acidic volcanic activities of the Okinawa Trough have an evolutional tendency of shifting to relatively basic magma activity. With further spreading of the Trough the magmatic activity will be intensified and the crust of the Trough will develop from the transitional type to the oceanic type.

Anomalous Behaviour of Photorefractive Grating Erasure Owing to Existence of both Negative and Positive Carriers

In LiNbO3:Fe, anomalous behaviour of grating erasure is observed with different wavelengths, i.e. rapid grating erasure in the short wavelength range, which deviates from the results predicted by the electron transport band model. The deviation is related to the coexistence of electrons and holes in photorefraction, and charge-transfer process including electrons and hole has been proposed. The electron and hole contributions to photoconductivity have been identified by experiments. We also give the theoretical dependence of electron photo-excitation coefficient S of the Fe centre on the wavelength.

Temporal behaviour of micro-discharge in dielectric barrier discharges

A special dielectric barrier discharge (DBD) device consisting of two water electrodes has been designed. The temporal behaviour of the micro-discharge (filament) in the DBD in air at atmospheric pressure is measured by using an optical method. The nonsymmetrical characteristic of the filament has been discovered for the first time. We propose an equation regarding the discharge moment by considering the memory effect of the accumulated charge and the influence of the fluctuation. The results deduced from the equation give a good explanation of the experimental phenomenon, which show that the decay time constant of the accumulated charges is much larger than 100 µs. The relative intensity of fluctuation amplitude is in the range 2-4% under the present experimental conditions.

Subcellular distribution patterns of twenty four elements in the human liver samples studied by molecular activation analysis

Molecular activation analysis based on biological separation techniques combined with instrumental neutron activation analysis (INAA) was applied to study the distribution patterns of 24 elements, including essential and unknown trace elements in the liver organelles. Concentrations of As, Au, Co, I, Mg, Mo, Sb, Sc, Se and Th were found to be the highest in nuclei and mitochondria, while those of Br, Cl, Cs, Cu, K, Na, Rb and V were found to be in cytosol. Concentrations of Al, As, Au, Ba, Fe, I, Sb were found to be the lowest in cytosol. The element As was mainly present in the nuclear fraction, where its concentration was two to four times higher than that in other fractions. Ca and Fe were highly enriched in the microsomal fraction.

Enhanced Photolysis of Nucleic Acid Monomers by Pyrophosphate in the Simulated Primitive Soup

In our simulation of the photochemistry of the primitive soup, it was found that yield of chromophore loss of some nucleic acid bases, nucleosides and nucleotides [NA] undergoing ultraviolet radiation by medium pressure mercury lamp [MPML] was enhanced by pyrophosphate and triphosphate whether O2 is present or not. The yield of chromophore loss of guanosine, uracil, 5′ CMP, and the derivatives of adenine and thymine was observed to rise with the increase of molar concentration of pyrophosphate in N2-saturated systems. In air-saturated samples, increase in yield of chromophore loss was observed when the concentration of pyrophosphate reaches 5×10-4 M, relative yield of chromophore loss (CLrel) coming to maximum in the range from 0.01 to 0.1 M, followed by a slight decline with the further increase of pyrophosphate concentration. The enhancement of photolysis of NA by pyrophosphate was due to the interaction between NA and pyrophosphate radicals photoionized by UV quanta of wavelength less than about 210 nm in the emission spectrum of a MPML. The relevance of this phenomenon to the origin of life has been discussed as well.

The comparative investigation of the dehydration methods of uracil hydrate derivatives

Abstract By following UV absorbance, UV absorption spectra and changes in high performance liquid chromatography hydrate peak elution areas during the reversion of uracil, uridine and 5′UMP hydrates induced by heating hydrated samples in boiling water for 10 min or by incubating acidified samples (pH 1) at room temperature for 24 h, it is shown that these methods do not lead to quantitative dehydration. The disappearance of hydrate peaks and the higher recovery of both the UV absorbance and UV absorption spectra obtained after heating acidified samples (pH 1) indicate that this method is best to achieve total dehydration. Catalysis of dehydration in phosphate buffer solution is also discussed.

Sensitivity Improvement by UV-Light Recording in LiNbO3:Ce:Cu Crystals

Modulated UV light is used to increase the sensitivity of the two-centre holographic recording. Inherent mechanisms of nonvolatile holographic recording in oxidized and reduced crystals are numerically analysed based on solving the two-centre material equations modified for UV-light recording. Experiments verification is performed with an oxidized crystal and a reduced crystal, and the role of UV intensity on the sensitivity is presented.