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  • Author or Editor: Y.L. Xie x
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Summary  

Sediment core samples were collected in the largest urban Lake Donghu (Stations I and II) in China, and the activities of 210Pb, 226Ra and 137Cs were measured by gamma-ray spectrometry. The sedimentation rates, calculated by 210Pb constant rate of supply (CRS) model, ranged from 0.11 to 0.65 (average 0.39) cm. y-1at Station I, and from 0.21 to 0.78 (average 0.46) cm. y-1at Station II. Sedimentation rate calculated by 137Cs as a time marker was 0.55 cm. y-1at Station II. Based on the average sedimentation rate, we obtained 769 and 147 t. y-1for nitrogen and phosphorus retentions in Lake Donghu sediments, respectively.

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Rice straw represents a significant energy source for ruminant animals, and fibers and lignin contents of rice straw are negatively related to intake potential of forages. For improvement of the digestibility of rice straw, it is necessary to understand the genetic basis of the related traits. In present study, mapping of quantitative trait loci (QTL) for acid detergent fiber (ADF), neutral detergent fiber (NDF), and acid detergent lignin (ADL) was carried out using a doubled haploid (DH) population derived from a cross between indica variety Zai-Ye-Qing 8 (ZYQ8) and japonica variety Jing-Xi 17 (JX17). The results indicated that all three parameters were continuously distributed among the DH lines, but many DH lines showed transgressive segregation for all the three traits. A total of three main-effect QTLs were identified for ADF and ADL, two of which, qADF-9 and qADL-9, shared the same region on chromosome 9. These two main-effect QTLs explained more than 20% of the total phenotypic variations, whereas the other QTL, qADF-5, explained 12.8% of the total phenotypic variation for ADF. In addition, another two epistatic QTLs, qADF-2 and qADF-3 could explain 17.6% of the total variations. Thus, we concluded that both main-effects and epistatic QTLs were important in controlling the genetic basis of ADF.

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Patrinia scabra Bunge has long been used in clinic as a traditional Chinese medicine for treating leukemia and cancer and regulating host immune response. Despite their wide use in China, no report on system analysis on their chemical constituents is available so far. The current study was designed to profile the fingerprint of ethyl acetate extract of it, and in addition, to characterize the major fingerprint peaks and determine their quantity. Therefore, a detailed gradient high-performance liquid chromatography was described to separate more than 30 compounds with satisfactory resolution in P. scabra Bunge. Based on the chromatograms of 10 batches samples, a typical high-performance liquid chromatographic (HPLC) fingerprint was established with 23 chromatographic peaks being assigned as common fingerprint peaks. Furthermore, a quadrupole time of flight mass spectrometry (Q-TOF/MS) was coupled for the characterization of major compound. As (+)-nortrachelogenin was the most predominant compound in P. scabra Bunge, the quantification on it was also carried out with the method being validated. As a result, (+)-nortrachelogenin was found to be from 1.33 to 2.21 mg g−1 in this plant material. This rapid and effective analytical method could be employed for quality assessment of P. scabra Bunge, as well as pharmaceutical products containing this herbal material.

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Abstract  

The uptake of rare earth elements (REE) by Euglena gracilis cells has been investigated in Fudan University. The remarkable ability to transport REEs to these cell’s compartments had been observed. X-ray absorption fine structure experiments (XAFS) of cerium in Euglena gracilis were performed at Beijing Synchrotron Radiation Facility (BSRF) to directly determine the cerium valence state and coordination structure in situ. Extended X-ray absorption fine structure (EXAFS) derived calculation showed that cerium was surrounded by 8 N atoms with bond length of 0.258 nm. Combining with other measurements, it may indicate that most likely REEs are mainly located in chlorophyll molecules.

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Summary

Oroxylin A (5,7-dihydroxy-6-methoxyflavone), which has showed multiple pharmacological effects, was semi-synthesized chemically as a pharmaceutical agent. Its impurities, degradation products and their formation pathways remain unknown. In the present study, two impurities (5,6,7-trihydroxyflavone, 5-hydroxy-6,7-dimethoxytlavone) and a degradation product (5,7-dihydroxy-8-methoxyflavone) in Oroxylin A bulk drug substance were identified, and their formation pathways were proposed. A reversed phase liquid chromatographic method for the simultaneous determination of Oroxylin A and the three compounds was developed on a C18 column using methanol-acetonitrile-0.1% acetic acid (54:23:23, v/v/v) as the mobile phase. The detection was performed at 271 nm. The method was validated to be robust, precise, specific and linear between 4 and 40 μg mL−1; the limits of detection and quantification of Oroxylin A were 0.01 and 0.04 μg mL−1, respectively. The developed method was found to be suitable to check the quality of bulk samples of Oroxylin A at the time of batch release and also during its stability studies (long term and accelerated stability).

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Abstract  

The exfoliated poly(vinyl chloride) (PVC)/montmorillonite (MMT) nanocomposites were synthesized by in situ intercalated polymerization of vinyl chloride (VC) in the presence of organic-intercalated montmorillonite (OMMT). Their structures and thermal properties were characterized. The results showed that layered silicates are well exfoliated and uniformly distributed in PVC matrix during in situ intercalated polymerization of VC in the presence of OMMT. The glass transition temperatures of PVC phases in the PVC/MMT nanocomposites are all lower than that of pristine PVC due to the incorporation of the exfoliated silicate layers in PVC matrix. The 5% mass loss temperature (T 5%), the dehydrochlorination temperature (T max1) of the PVC matrix decreased due to the free and interlayer water in MMT, the low thermal stability, and the enhanced dehydrochlorination of the PVC matrix by alkyl ammonium pre-treated MMT. However, the thermal decomposition temperature of the dehydrochlorinated PVC (T max2) and char at 600C are slightly increased in the presence of silicate layers.

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The common wheat line, YW243, developed in our research group, was tested for the resistances of barley yellow dwarf virus (BYDV), powdery mildew (Pm) and stripe rust in field, and was analyzed by molecular markers for convenient trace of the resistant genes in breeding. Genomic in situ hybridization (GISH) analysis and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) assay further demonstrated that YW243 was a homozygous multiple translocation line of Triticum aestivum, Thinopyrum intermedium and Secale cereale (T7DS·7DL-7XL & 1BL·1RS). The disease resistance test and marker analysis showed that YW243 carried seven resistance genes to the three diseases, including Bdv2 to BYDV on 7DL-7XL, Pm4 to powdery mildew on 2AL, Yr2, Yr9, Sr 31 and Lr26 and a new Yr to stripe rust on 7B, 1BL, 1RS and 2BL. Restriction fragment length polymorphism (RFLP) markers Xpsr687 and Xwg380 , sequence tagged site (STS) marker STS 1700 , simple sequence repeat (SSR) markers Xgwmc364 and Xgwm582 , SSR markers Xgwm388 and Xgwm501 can be used as diagnostic tools to track Bdv2, Pm4, Yr2, Yr9 and Yr in YW243 , respectively; and two amplified fragment length polymorphism (AFLP) markers M54E63 - 700 and M54E64 - 699 can also be used to select Yr in YW243 .

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New high-molecular-weight glutenin (HMW glutenin) sequences isolated from six Psathyrostachys juncea accessions by thermal asymmetric interlaced PCR differ from previous sequences from this species. They showed novel modifications in all of the structural domains, with unique C-terminal residues, and their N-terminal lengths were the longest among the HMW glutenins reported to date. In their repetitive domains, there were three repeatable motif units: 13-residue [GYWH(/I/Y)YT(/Q)S(/T)VTSPQQ], hexapeptide (PGQGQQ), and tetrapeptide (ITVS). The 13-residue repeats were restricted to the current sequences, while the tetrapeptides were only shared by D-hordein and the current sequences. However, these sequences were not expressed as normal HMW glutenin proteins because an in-frame stop codon located in the C-termini interrupted the intact open reading frames. A phylogenetic analysis supported different origins of the P. juncea HMW glutenin sequences than that revealed by a previous study. The current sequences showed a close relationship with D-hordein but appeared to be more primitive.

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Abstract

To develop thermal stable flavor, two glycosidic bound flavor precursors, geranyl-tetraacetyl-β-D-glucopyranoside (GLY-A) and geranyl-β-D-glucopyranoside (GLY-B) were synthesized by the modified Koenigs–Knorr reaction. The thermal decomposition process and pyrolysis products of the two glycosides were extensively investigated by thermogravimetry (TG), differential scanning calorimeter (DSC) and on-line pyrolysis-gas chromatography mass spectroscopy (Py-GC-MS). TG showed the T p of GLY-A and GLY-B were 254.6 and 275.7°C. The T peak of GLY-A and GLY-B measured by DSC were 254.8 and 262.1°C respectively.

Py-GC-MS was used for the simply qualitative analysis of the pyrolysis products at 300 and 400°C. The results indicated that: 1) A large amount of geraniol and few by-products were produced at 300°C, the by-products were significantly increased at 400°C; 2) The characteristic pyrolysis product was geraniol; 3) The primary decomposition reaction was the cleavage of O-glycosidic bound of the two glycosides flavor precursors. The study on the thermal behavior and pyrolysis products of the two glycosides showed that this kind of flavor precursors could be used for providing the foodstuff with specific flavor during heating process.

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