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Gang Yu

Publications and source records attributed to Gang Yu.

At least 37 records · Page 2Linked to original sources
PubMed2005

[Adopting the method of correlation coefficient to improve the accuracy of the xylene isomer's prediction model].

This paper focuses on the detailed researches on the correlation coefficient in near infrared spectrum and points out its characteristics in multi-component solution; the paper also proves the principle of obtaining more accurate results when using high correlation coefficient for model building, and presents a practical experiment to test the conclusions by using para-xylene, meta-xylene, and orthoxylene's mixture.

Algorithms↗
PubMed2005

[Prediction of photolysis half-lives of PCDD /Fs adsorbed on spruce needles optimized by genetic algorithm].

Adopting quantum chemical parameters of PCDD/Fs computed with quantum chemical PM3 algorithm, quantitative structure-property relationship (QSPR) model, which could predict photolysis half-life (t1/2) of PCDD/Fs adsorbed to spruce [Picea abies (L.) Karst.] needle surfaces, is established using genetic algorithm (GA) algorithm. It is considered that the main factors affecting lg t1/2 of PCDD/Fs are the energy of the highest occupied molecular orbital (EHOMO), ELUMO - EHOMO and average molecular polarizability (alpha). The lg t1/2 values increase with the increasing of EHOMO and a. The relationship between the lg t1/2 values and ELUMO - EHOMO is a parabolic curve. The lg t1/2 values increase with the increasing of ELUMO - EHOMO when ELUMO - EHOMO > or = 7.847 and decrease with the increasing of when ELUMO - EHOMO < or = 7.847.

Algorithms↗
PubMed2005

[Chlorobenzenes in water and surface sediments from Tonghui River of Beijing].

Eleven chlorobenzenes (except MCB of a total of 12 in the congener series) in water and surface sediment samples collected from Tonghui River of Beijing China in November,2003 are analyzed. The range of total chlorobenzenes (CBs) was 0.093 - 6.638 microg x L(-1) in water, among which DCBs occupy 88.8%; while 95.3 - 1 827.7 ng x g(-1) in surface sediments, among which DCBs, TCBs,TeCBs,PeCB and HCB occupy 15.6%, 31.7%, 17.6%, 21.2% and 13.9% respectively. Comparison with the results of other research areas, the pollution of CBs in surface sediments is some serious. Besides, there is no significant correlation between total CBs concentrations in water and those in surface sediments.

China↗
PubMed2005

Mechanism of NO reduction with non-thermal plasma.

Non-thermal plasma has been proved to be an effective and competitive technology for removing NO in flue gas since 1970. In this paper, the NO reduction mechanism of the non-thermal plasma reaction in NO/N2/O2 system was investigated using the method of spectral analysis and quantum chemistry. By the establishment of NO reduction and gas discharge plasma emission spectrum measuring system, the NO reduction results, gas discharge emission spectra of NO/N2/O2 and pure N2 were obtained, and then the model of molecular orbit of N2 either in ground state or its excited state was worked out using the method of molecular orbit Ab initio in Self-Consistent Field (SCF). It was found that NO reduction in NO/N2 gas discharge plasma was achieved mainly through a series of fast elementary reactions and the N(E6) at excited state was the base for NO reduction.

Air Pollution↗
PubMed2005

Characteristics of NO reduction with non-thermal plasma.

As a new type of NO removal system, NO reduction in N2-NO plasma was applied to solve the difficulties in the traditional methods, such as higher energy-consumption, larger equipment size and high cost, and so on. Using the experimental NO reduction system with single-pair electrode tip discharge structure, the NO reduction characteristics of N2-NO system were revealed to guide the engineering practice; the results of NO reduction with single-pair electrode tip discharge plasma also have the same instructive meaning to the NO reduction with multi-pair electrode tip discharge plasma. The amount of both active N atom and NO removal rate increased with the distance /g increasing between the two electrode tips and then dropped when the distance exceeded a certain value. The NO removal rate increased while the voltage between two electrode tips or the resident time of gas flow increased. The distance is a key geometrical variable factor that can determine the intensity of electric field between two electrode tips and the resident time of gas. In this paper, the effects of the dielectric features on NO reduction using dielectric-barrier discharge plasma system were also studied. The results of NO removal rate with different dielectrics such as Al2O3, CaO, MgO and glass showed that the electric field intensity is different with different dielectric, because it brings different energy to particles in discharge room and thus it causes different NO removal rate.

Aluminum Oxide↗
PubMed2005

[Regulatory effect of Smad7 gene on MAPK signal pathway in malignant transformation of immortalized human bronchial epithelial BEP2D cells].

BACKGROUND & OBJECTIVE: Smad7 is an inhibitor of transforming growth factor-beta (TGF-beta) signal pathway. TGF-beta could induce the expression of several genes through activating SMAD and ras/MEK/ERK pathways. This study was to determine whether Smad7 is involved in regulating mitogen-activated protein kinase (MAPK) signal pathway with TGF-beta in malignant transformation of human bronchial epithelial BEP2D cells. METHODS: Immortalized BEP2D cells and malignant BERP35T2 cells were co-transfected with full-length Smad7 cDNA constructed pCISmad7.neo or Smad7 siRNA, transactivator vector pTet-Elk or pTet-Jun, and reporter vector pTRE-Luc, and stimulated with TGF-beta. The regulatory effect of Smad7 on MAPK signal pathway was investigated by standard luciferase assay. RESULTS: In BEP2D cells, when treated with TGF-beta1, phosphorylated activities of Elk and Jun were up-regulated (P(Elk)=0.033, P(Jun)=0.016); after co-transfection of Elk or Jun with pCISmad7.neo, phosphorylated activity of Elk was increased, and that of Jun was decreased (P(Elk)=0.017, P(Jun)=0.028); after co-transfection of Elk or Jun with Smad7 siRNA, phosphorylated activity of Elk was decreased, and that of Jun was increased (P(Elk)=0.018, P(Jun)=0.005). In BERP35T2 cells, when treated with TGF-beta1, phosphorylated activity of Elk was up-regulated (P=0.006); after co-transfection of Elk and Smad7 siRNA, phosphorylated activity of Elk was decreased (P=0.000); no activity of Jun was detected in BERP35T2 cells. CONCLUSIONS: In the process of malignant transformation of BEP2D cells, the intervention of Smad7 in MAPK signal pathway leads to the activity imbalance between extracellular signal-related protein kinase (ERK) and c-Jun NH2-terminal kinase (JNK), which in turn promotes cell proliferation. All these could contribute to further malignant transformation of these cells.

Bronchi↗
PubMed2005

Synergistic removal of nitrogen monoxide by non-thermal plasma and catalyst simultaneously.

An experimental system of De-NO with plasma-catalyst(Cu zeolite) was established to investigate the differences between De-NO with plasma-catalyst and De-NO only with plasma, to provide the instruction for selecting appropriate catalyst and operating condition. The characteristics of De-NO with plasma and De-NO with plasma-catalyst were investigated comparatively by experiments. The experimental results show that De-NO with plasma-catalyst has high NO removal rate; Cu zeolite is an effective catalyst which can promote NO removal rate in plasma remarkably; De-NO with plasma-catalyst should be operated at low temperature and the temperature has opposite effects on the function of catalyst and plasma; water vapor and O2 can increase the NO removal rate.

Air Pollution↗
PubMed2005

[Application of cross-correlation analysis to model transfer of near infrared spectrum].

Model transfer was studied by cross-correlation in near infrared spectrum. The hypothesis is that there exists an inherent proportional constant between the two spectra for model building measured by two different spectrometers after cross-correlation analysis is put forward and approved. The compatibility of the two models is enhanced after using the proportional constant. So the good results were obtained.

Models, Chemical↗
PubMed2004

Occurrence of PAHs, PCBs and organochlorine pesticides in the Tonghui River of Beijing, China.

Tonghui River, a typical river in Beijing, People's Republic of China, was studied for its water and sediment quality, by determining the levels of 16 polycyclic aromatic hydrocarbons (PAHs), 12 polychlorinated biphenyls (PCBs) and 18 organochlorine pesticides in water and sediment samples. Total PAHs, PCBs and organochlorine pesticides concentrations in water varied from 192.5 to 2651 ng/l, 31.58-344.9 ng/l and 134.9-3788 ng/l, respectively. The total PAHs, PCBs and organochlorine pesticides concentrations in surficial sediments were 127-928 ng/g, 0.78-8.47 ng/g and 1.79-13.98 ng/g dry weight, respectively. The results showed that the concentration of these selected organic pollutants in sediment was higher than those in surface water. It may be due to the fact that organic hydrophobic pollutants tend to stay in the sediments. The PAHs were dominated by 2-, 3-ring components in water samples and by 3- and 4-ring compounds in sediment. For organochlorines, alpha-HCH, delta-HCH, Heptachlor, Endosulfan II, DDT are the major organochlorine pesticides in water while Heptachlor, Dieldrin and DDE composed of 95% of total organochlorine pesticides in sediment. For HCHs (HCHs=alpha-HCH+beta-HCH+gamma-HCH+delta-HCH), the predominance of alpha-HCH of total HCHs were clearly observed in water and sediment. PCB18, PCB31 and PCB52 were predominant in water, on average these compounds collectively accounted for 67% of total PCBs. But in sediment, the predominant compounds were PCB28, PCB31 and PCB153, which accounted for 71% of total PCBs in sediment. The levels of micro pollutants in our study areas were compared with other studies.

China↗
PubMed2004

Application of TLSER method in predicting the aqueous solubility and n-octanol/water partition coefficient of PCBs, PCDDs and PCDFs.

The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n-octanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls(PCBs), polychlorinated dibenzodioxins and dibenzofurans (PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AM1 semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(alpha), energy of the lowest unoccupied molecular orbit( E(LUMO)), energy of the highest occupied molecular orbit( E(HOMO)), the most positive charge on a hydrogen atom (q+), and the most negative atomic partial charge(q-) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n-octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models. The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties of macromolecular chemicals, such as persistent organic pollutants.

1-Octanol↗
PubMed2004

Predicting physico-chemical properties of polychlorinated diphenyl ethers (PCDEs): potential persistent organic pollutants (POPs).

Polychlorinated diphenyl ethers (PCDEs) have received more and more concerns as a category of potential persistent organic pollutants (POPs). Modeling its environmental fate and exposure assessment require a number of fundamental physico-chemical properties. However, the experimental data are currently limited due to the difficulty in analysis caused by the complexity of PCDE congeners. As an alternative, the quantitative structure property relationship (QSPR) approach could be used. In this paper, twelve kinds of molecular connectivity indices (MCIs) of all 209 possible molecular structure patterns of PCDEs were calculated. Based on 106 PCDEs with three observed physico-chemical properties-vapour pressure (P0L), aqueous solubility (Sw) and n-octanol/water (Kow) and their MCIs data, a series of QSPR equations were established using multiple linear regression (MLR) method. As a result, three equations with best performance were selected mainly from the view of high regression coefficient (R) and low standard error(SE). All of them showed significant relationship and high accuracy. With these equations the properties of other 103 patterns of PCDEs without the reported observed values were predicted. Furthermore, three partition properties for PCDE congeners-Henry' s Law constants (H), partition coefficients between gas/water (Kgw) and gas/n-octanol (Kgo) were calculated according to the internal relationship among these six properties. These observed and predicted values, in contrast with the criteria listed in the Stockholm treaty about POPs which has been signed by more than ninety countries in May 2001, illustrated that most of PCDEs congeners are potential persistent organic pollutants. As all descriptors/predictors are derived just from the molecular structure itself and without the import of any empirical parameters, this method is impersonal and promising for the estimation of physico-chemical properties of PCDEs.

1-Octanol↗
PubMed2004

[Influential factors on the toxicity of pentachlorophenol sodium with MICROTOX system in water].

The biological toxicity of pentachlorophenol sodium (Na-PCP), a typical kind of aquatic organic pollutants, was tested with the MICROTOX system using luminescent bacteria with the influence of several factors taken into consideration. The EC50 of Na-PCP increases with the increasing of the pH and hardness of the sample. The EC50 (15 min) of Na-PCP is approximately equal to its EC50 (20 min). Compared with some common organic pollutants, which exhibit little influence on the toxicity of Na-PCP when mixed, Na-PCP is more toxic. A reduction of 14% in relative luminescent rate was observed in the experiment with a natural sample. The natural sample exhibits similar influence on the toxicity of Na-PCP similarly compared with unionized water.

Luminescence↗
PubMed2004

[Study of photoelectrocatalytic oxidation of benzoic acid].

This study reports the photoelectrocatalytic oxidation of benzoic acid in a three-electrode photoelectroreactor. The effects of the anode bias potential, the atmosphere of reaction and the basis material for photocatalyst preparation on the removal efficiency of benzoic acid were researched. The photoelectrocatalysis was compared with photolysis, photocatalysis and electrolysis. The results of the experiments indicated the removal efficiency of benzoic acid after the photoelectrocatalytic oxidation process for 1 h could be more than 85%, much higher than the efficiency of photolysis (48%), photocatalysis (30%) and electrolysis (nearly having no effect). The synergetic effect of the photoelectricity was obvious. The working electrode and the counter electrode were arranged as two concentric columns whose diameters were different. The results showed that this kind of arrangement mode was very effective. In nitrogen atmosphere the removal efficiency of benzoic acid could be 98% when TiO2/Ti acted as the anode of the photoelectrocatalytic oxidation process for 1 h, much better than the TiO2/Al did (85%). While in oxygen atmosphere the two kinds of electrodes were both effective and the removal efficiency of benzoic acid could approach 100%.

Benzoic Acid↗
PubMed2004

[Kinetics of degradation of hexane in the gas phase by photocatalysis and combined photocatalysis and ozone].

The degradations of trace hexane under high flow rate (5 L/min-17 L/min) in the gas phase by TiO2/UV, O3/UV and O3/TiO2/UV were studied. The kinetic effects of the inlet concentration of hexane, flow rate, water concentration and ozone dosage on the conversion of hexane in the three processes were examined respectively. The experimental results showed that the addition of ozone to the photocatalysis process increased the conversion of hexane significantly. The O3/TiO2/UV process was more efficient than the TiO2/UV in decomposing hexane. The degradation rate increased with increasing the initial concentration of hexane in the processes of TiO2/UV and O3/TiO2/UV. They matched well with the Langmuir-Hinshelwood (L-H) kinetic model. In the range of flow rate studied, the degradation rate increased with an increasing flow rate in both processes of TiO2/UV and O3/TiO2/UV, while was not affected in the process of O3/UV. The degradation rate in the three processes was affected by water concentration. The degradation rate of the two processes O3/UV and O3/TiO2/UV increased almost linearly with the increase of ozone dosage.

Air Pollutants↗
PubMed2004

[The influence on the biodegradation of phenanthrene by nonionic surfactant, Tween20].

The objective of this study was to quantify the bioavailability of phenanthrene solubilized in surfactants by a mixed phenanthrene-degrading culture isolated from the petroleum contaminated soils. An nonionic surfactant, Tween20, was used. The effects of Tween20 on the microbial degradation of phenanthrene were evaluated depending on the rotary flasks experiments. The results showed that the concentrations of Tween20 above the critical micelle concentration (CMC) could increase the solubility of phenanthrene on great extent and were not toxic to the phenanthrene-degrading bacteria, and that the presence of surfactant micelles did not inhibit the biodegradation of phenanthrene. Phenanthrene solubilized in the micelles of Tween20 in liquid media was bioavailable and degradable by the mixed culture of bacteria.

Biodegradation, Environmental↗
PubMed2004

[Preliminary investigation on endocrine disrupting chemicals in a sewage treatment plant of Beijing].

Endocrine disrupting chemicals (EDCs) existed in the water treatment units of Beijing based Sewage Treatment Plant were analyzed by SPE-GC/MSD and GC/ECD. Totally 30 EDCs were detected from the influent, effluent and sludge. The results show that about 70%-99% EDCs in the influent were removed after treatment. Sludge adsorption played an important role in the reduction of EDCs. The range of phenols in sludge was 17-35 mg/kg, the range of PAEs was 25-77 mg/kg and the range of PAHs was 1.33-1.74 mg/kg. Compared with the results in other countries in literature, the existence of EDCs in the Sewage Treatment Plant was not serious.

Benzhydryl Compounds↗