Biomedical subjects

Xianliang Qiao

Publications and source records attributed to Xianliang Qiao.

5 recordsLinked to original sources

PubMed2006

Kinetics of oxidative decolorization and mineralization of Acid Orange 7 by dark and photoassisted Co2+-catalyzed peroxymonosulfate system.

A kinetic model was proposed and used to interpret the experimental data for degradation of Acid Orange 7 (AO7) in aqueous solution induced by Co(2+)/peroxymonosulfate (Co/PMS) reagent in terms of both decolorization and mineralization. The pseudo first-order decolorization rate constants are related to [Co(2+)], [PMS], reciprocal of [H(+)] and [AO7](0). Activation energy of the AO7 decolorization process was determined to be 75.7 kJ mol(-1). UV and visible light can accelerate the decolorization and mineralization process due to different mechanisms. In the combined UV/Co/PMS system, UV light can decompose PMS to generate hydroxyl ((*)OH) and sulfate radicals (SO(4)(*-)), while in the Vis/Co/PMS system, excited AO7 molecules can transfer electrons to PMS or Co(3+) and thus accelerate the decomposition of PMS and catalytic cycle of Co(3+)/Co(2+).

Azo Compounds↗

PubMed2006

Quantitative structure-property relationships for direct photolysis of polybrominated diphenyl ethers.

Using semiempirical quantum chemical descriptors, by partial least squares (PLS) regression, quantitative structure-property relationships (QSPRs) were established for direct photolysis quantum yields (Phi) and rate constants (k) of polybrominated diphenyl ether congeners dissolved in water/methanol and methanol solutions, respectively, and irradiated by artificial ultraviolet A light. Q(cum)(2), a parameter indicating robustness and predictive abilities of PLS models, for the significant QSPR models is larger than 0.702. The gap of frontier molecular orbital energies (E(LUMO)-E(HOMO)) and the most positive Mulliken atomic charges on a hydrogen atom (q(H+)) are two main molecular structural factors governing the logPhi values. logPhi increases with increasing E(LUMO)-E(HOMO) and q(H+) values. logk is mainly related to bromination degree and pattern which can be characterized by molecular weight (Mw), average molecular polarizability (alpha), and average Mulliken atomic charges on bromine atoms (q(Br)). logk increases with bromination degree (Mw, alpha) and q(Br).

Least-Squares Analysis↗

PubMed2005

Quantitative relationships between molecular structures, environmental temperatures and solid vapor pressures of PCDD/Fs.

Based on quantum chemical and topological descriptors, temperature-dependent predictive models for solid vapor pressure (PS) of PCDD/Fs were developed. The inclusion of the two topological descriptors, Kier symmetry index (S0K) and Kier flexibility index (PHI), as predictor variables, improved the statistical significance of models. Thus the entropic factors described by the two topological descriptors play a role in influencing the PS values. The cumulative variance of the dependent variable explained by the PLS components and determined by cross-validation (Qcum2), for the final model, is 0.972, indicating that the model has good predictive ability and robustness, and could be used to estimate PS values of PCDD/Fs at different temperatures. The main factors governing log PS values of PCDD/Fs, from important to less important, are temperature, intermolecular dispersive interactions, entropic factor, and intermolecular dipole-dipole and dipole-induced dipole interactions.

Benzofurans↗

PubMed2005

[Toxic effects of 1,8-dihydroxyanthraquinone on Daphnia magna].

The study on the acute, sublethal and chronic toxicity of 1,8-dihydroxyanthraquinone (1,8-dihAQ) to Daphnia magna showed that the 48 h LC50 was 0.37 mg L(-1), and the feeding behavior of Daphnia magna was severely affected by the compound. When exposed to 0.2 mg x L(-1) of 1,8-dihAQ for 5 h, the filtration and ingestion rate of Daphnia magna was inhibited by 97%. Chronic toxicity test results indicated that the reproduction ability decreased dramatically after exposing to sublethal concentration of 1, 8-dihAQ. It could be inferred that reproduction parameters and intrinsic rate of natural increase were the sensitive parameters in characterizing sublethal toxicity. The NOEC and LOEC values for reproduction parameters were also given.

Animals↗

PubMed2003

Use of a multi-layer column device for study on leachability of nitrate in sludge-amended soils.

This paper described a multi-layer column device constructed with six cylindrical polythene tubes with installation of Rhizon soil moisture samplers (Rhizon SMS). The feasibility of using the column device to collect soil solution and percolate and to monitor leachability of nitrate in two sludge-amended soils was evaluated under glasshouse conditions. The soil moisture sampler in the device was demonstrated to be a non-destructive, simultaneous, sequential, convenient and rapid sampling tool for multiple-site porewater extraction. The device provided an in situ monitoring technique for leachability of nitrate in a soil profile following application of the anaerobically digested sewage sludge. The monitored results showed that surface soil amendment of the sewage sludge increased markedly the concentration of nitrate in the soil solutions at depths of 10-30 cm in a neutral paddy soil and at 30-50 cm in an acid red paddy soil. This amendment also largely increased nitrate in the percolates of the acid red soil. The movement and distribution patterns of nitrate in the profile were related to soil types, profile depths and experimental periods. Land application of sewage sludge may pose a risk in groundwater contamination of nitrate.

Environmental Monitoring↗