[Characteristics and Source Analysis of VOCs Pollution During the Period of Ozone Exceeding the Standard in Zibo City].

In recent years, ozone pollution has been growing increasingly serious in the urban areas of China. Volatile organic compounds (VOCs) are important precursors of O3 formation, which is of great significance to studying the main characteristics and sources of VOCs for controlling O3 pollution. In this study, we conducted online VOCs observation in Zibo City from May to September in 2019, monitoring 56 species in total. During the observation, the over-standard rate of ozone was up to 67.8%, the average of ρ(VOCs) was 140.71 µg·m-3, and the concentration of VOCs in the ozone over standard days was 1.04 times that on the non-standard days. The rank of VOC classes was aromatic hydrocarbons>alkanes>alkenes>alkynes. Among them, 1,3,5-tritoluene, o-ethyltoluene, 1-butene, and n-hexane achieved high emission in the exceeding O3 and non-exceeding days. Aromatic hydrocarbon and alkenes contributed more to the potential of ozone formation. According to the PMF source analysis results, VOCs sources in the urban area mainly included motor vehicle sources, fixed combustion sources, solvent sources, process sources, and natural plant sources, among which motor vehicle sources were the most important source of VOCs in the urban area. In addition, motor vehicle sources accounted for 32.3%, and fixed combustion sources accounted for 24.2% on days when ozone exceeded the standard, which increased by 3.3% and 6.9%, respectively, compared with those on days when ozone did not exceed the standard. However, the proportion of solvent sources and process sources decreased by 5.1% when ozone exceeded the standard compared with that on a non-standard day.

[Characteristics of Ozone Pollution and Influencing Factors in Urban and Suburban Areas in Zibo].

In this study, we obtained monitoring data of O3 and its precursors (NOx, VOCs, and CO), as well as meteorological data (temperature, relative humidity, wind speed, and visibility), in 2019 to analyze the characteristics of O3 pollution and the influencing factors in urban and suburban areas. The results showed that the O3 episodes accounted for 25.8% of the whole observation period, mostly occurring from May to September. The concentration of NOx in urban areas was higher than that in suburban areas, whereas the concentrations of O3 and VOCs were lower. The hourly rate of variation in each pollutant had obvious seasonal characteristics; for example, the time of O3 rise and precursor decline in autumn and winter was approximately 1 h later than that in summer, and the peak period of O3 generation and accumulation was shortened. The increase rate in O3 in urban areas was higher than that in suburban areas. Correlation analysis and partial correlation analysis were used to study the relationship between O3 and its influencing factors. The results showed that O3 was negatively correlated with precursors and relative humidity and positively correlated with visibility, temperature, and wind speed, and these factors interacted with each other. According to the multivariate linear regression analysis, the main controlling factors in urban areas were relative humidity, NOx, visibility, and VOCs, whereas in suburban areas they were relative humidity, temperature, NOx, and VOCs.

[Emission Characteristics of Volatile Organic Compounds from Typical Industries in Zibo].

To study the emission characteristics of volatile organic compounds (VOCs) in Zibo, nine key industries and their representative enterprises were selected to conduct a field investigation and measurement. The emitted VOC characteristics in different industries were analyzed. Based on measurement data, the emissions of VOCs from all monitored enterprises were calculated to obtain the localization emission factors. The results showed that different industries exhibited some differences in VOCs components, and the major VOCs components were alkane and halo hydrocarbon. Ethane, acetylene, chloromethane (conclude 1,1-dichloroethane, 1,1,1-trichloroethane), and Freon (Freon 12 or Freon 114) were the characteristic species in most industries. The results indicated that the major VOCs emission links in different types of petrochemical industries were equipment leakage, loading volatilization, storage volatilization losses, and organized discharge, which accounted for more than 40% of emissions. Local emission factors of VOCs calculated in the synthetic rubber and steel manufacturing industries were close to the recommended values in the guide, whereas there were large gaps in other industries.

[Determination of Trace Germanium in Plant Samples by Dry Ashing-Atomic Fluorescence Spectrometry].

To reduce the limit of detection (LOD) and allow the accurate determination of Ge, a dry ashing method was performed to enrich the Ge in plant samples. A method for the determination.of trace Ge in plant samples by HG-AFS was established. Study of the effect of temperature on the ashing of plant samples showed that no volatile loss of Ge occurred even at 900 °C. Additional experiments indicated that a 4 h burning process at 600 °C would be sufficient to fully ash the plant samples. Various digestion methods (involving nitric acid, hydrofluoric acid, and sulfuric acid digestion methods) for ashed samples were investigated. High-temperature ashing with large sample weights was used, which could reduce the reagent doses and the method's LOD effectively and simultaneously, the precision of the method was improved. The method's LOD was 0.27 ng · g(-1), and the relative standard deviation was 3.99%-6.81%. Verified with national biological reference materials (grade I), the proposed method was accurate and reliable.

Application of the Zr/Hf ratio in the determination of hafnium in geochemical samples by high-resolution inductively coupled plasma mass spectrometry.

Hafnium content and its change are of significance in geochemistry and cosmochemistry; however, the determination of hafnium has always been problematic in analytical chemistry. In this paper, a new idea is proposed for the determination of hafnium in geochemical samples, including rocks, soils, and stream sediments. Through the comparison of two conventional open-type acid digestion methods (HF-HNO3-HClO4 and HF-HNO3-H2SO4), it was found that although neither of these methods could fully digest the zirconium and hafnium in a sample, the zirconium and hafnium digestion behaviors in one sample were consistent in the 60 experimental geochemical reference materials with different properties, so the experimentally determined Zr/Hf ratio in solution could be used to calculate the hafnium content in a sample. In addition, possible mass spectral interferences during the determination of zirconium and hafnium by high resolution inductively coupled plasma mass spectrometry (HR-ICPMS) were studied, and it was found that the mass spectral interferences of the selected isotopes (90)Zr and (178)Hf could be neglected. The mass spectral behaviors of (90)Zr and (178)Hf were also very consistent during the determination by HR-ICPMS. Since the hafnium content was calculated using the ratio value, all of the errors (including the errors in weighing process, the accidental errors during operation and the instrument fluctuation in the determination) of the Zr/Hf ratio could be effectively reduced or even eliminated. The relative standard deviation of the actual samples was lower than 3.2%, and the detection limit of the method (considering the dilution effect and matrix effect during measurement of the Zr/Hf ratio and zirconium content) was 0.04 µg/g. The proposed method could satisfy the requirement for the determination of hafnium in geochemical samples.

Amplification and overexpression of Aurora-A in esophageal squamous cell carcinoma.

Aurora-A/BTAK/STK15 gene which encodes a centrosome-associated kinase is located on chromosome 20q13.2, a highly amplified region in various human tumors. Recent studies have demonstrated the overexpression and amplification of Aurora-A in many malignant human cancers. The purpose of this study was to investigate the amplification and expression of Aurora-A in esophageal squamous cell carcinoma. Amplification of Aurora-A was determined by fluorescence in situ hybridization in 7 esophageal cancer cell lines and real-time PCR in 29 esophageal cancer samples. We detected Aurora-A expression in 7 esophageal cancer cell lines and 38 esophageal cancers samples by semi-quantitative reverse transcription-PCR and Western blot hybridization. The amplification of Aurora-A was detected in 27 of 29 (93.1%) esophageal cancer samples and 6 of 7 (85.7%) cancer cell lines. Aurora-A was overexpressed in 27 of 38 (71.1%) esophageal cancer samples and all 7 esophageal cancer cell lines. We conclude that Aurora-A is amplified and overexpressed in esophageal squamous cancer.

[Expression of survivin and its significance in esophageal cancer].

OBJECTIVE: To detect the expression of survivin in esophageal cancer and elucidate its function in esophageal cancer. METHODS: Expression of surviv in was detected in paired normal and tumor tissues from patients with esophageal cancer by semi-quantitative RT-PCR. A dominant-negative survivin (surT34A) was transfected into esophageal cancer EC9706 cells (EC9706surT34A). Colony formation and apoptosis of the parental and surT34A-transfected EC9706 cells were examined in soft agar and by flow cytometry, respectively. RESULTS: Survivin mRNA expression of tumor tissues was higher than normal tissues in 18/27 (66.7%) samples. The expression level of survivin mRNA in tumor tissues (2.08 +/- 1.32) was significantly higher than that in normal tissues (1.22 +/- 1.09). EC9706 surT34A cells formed fewer colonies on agar than the non-transfected ones. After serum withdrawal, EC9706surT34A had higher apoptotic ratio than control, but survivin could reduce the apoptotic ratio. CONCLUSION: Overexpression of survivin is a common eventin esophageal cancer. The dominant-negative survivin can partially inhibit the malignant phenotype of esophageal cancer.

Knockdown of c-Myc expression by RNAi inhibits MCF-7 breast tumor cells growth in vitro and in vivo.

INTRODUCTION: Breast cancer is the leading cause of cancer death in women worldwide. Elevated expression of c-Myc is a frequent genetic abnormality seen in this malignancy. For a better understanding of its role in maintaining the malignant phenotype, we used RNA interference (RNAi) directed against c-Myc in our study. RNAi provides a new, reliable method to investigate gene function and has the potential for gene therapy. The aim of the study was to examine the anti-tumor effects elicited by a decrease in the protein level of c-Myc by RNAi and its possible mechanism of effects in MCF-7 cells. METHOD: A plasmid-based polymerase III promoter system was used to deliver and express short interfering RNA (siRNA) targeting c-myc to reduce its expression in MCF-7 cells. Western blot analysis was used to measure the protein level of c-Myc. We assessed the effects of c-Myc silencing on tumor growth by a growth curve, by soft agar assay and by nude mice experiments in vivo. Standard fluorescence-activated cell sorter analysis and TdT-mediated dUTP nick end labelling assay were used to determine apoptosis of the cells. RESULTS: Our data showed that plasmids expressing siRNA against c-myc markedly and durably reduced its expression in MCF-7 cells by up to 80%, decreased the growth rate of MCF-7 cells, inhibited colony formation in soft agar and significantly reduced tumor growth in nude mice. We also found that depletion of c-Myc in this manner promoted apoptosis of MCF-7 cells upon serum withdrawal. CONCLUSION: c-Myc has a pivotal function in the development of breast cancer. Our data show that decreasing the c-Myc protein level in MCF-7 cells by RNAi could significantly inhibit tumor growth both in vitro and in vivo, and imply the therapeutic potential of RNAi on the treatment of breast cancer by targeting overexpression oncogenes such as c-myc, and c-myc might be a potential therapeutic target for human breast cancer.

[Indomethacin induces apoptosis through inhibition of survivin regulated by beta-catenin/TCF4 in human colorectal cancer cells].

BACKGROUND & OBJECTIVE: Although Wnt pathway plays important role in colorectal carcinogenesis, but the mechanism of this pathway in anti-apoptosis is not clear. This study is to investigate the molecular mechanism of Wnt pathway in anti-apoptosis. METHODS: Survivin promoter region was constructed into luciferase reporter system (pGL3-sur1.8kb). The recombinants pGL3-sur1.8kb were cotransfected with pRL-SV40 into HCT116 cells and the activities were detected with Dual-luciferase reporter assay system. Cell apoptosis was analyzed by flow cytometry. Protein level of survivin and beta-catenin was detected by Western Blot. RESULTS: Survivin could be up-regulated by beta-catenin and down-regulated by TCF4DeltaN in transcriptional level. beta-catenin/TCF4 dependent apoptosis induced by indomethacin could suppress survivin transcription. Overexpression of survivin could partially recover the beta-catenin/TCF4 dependent apoptosis. CONCLUSION: Down-regulation of survivin affected by beta-catenin/TCF4 pathway plays an important role in apoptosis induced by NSAIDs indomethacin in HCT116 cells. The beta-catenin/TCF4-survivin pathway may be a potential target in treatment of colon cancer.

[Survivin mutants reverse the malignancy of HeLa cells].

BACKGROUND & OBJECTIVE: Survivin was aberrantly expressed in most cancer tissues, suggesting that survivin plays an important role in carcinogenesis. This study was designed to investigate the function and mechanism of survivin mutants in tumor cells. METHODS: The site-mutant and truncated survivin mutants were transfected into HeLa cells and selected using G418. Cell apoptosis was analyzed using flow cytometry. Protein level of cyclin D1 was detected by Western blot analysis. RESULTS: Survivin mutant plasmid expressed in the HeLa cells successfully. The expressed protein could be detected using related antibody. Colony formation ability significantly decreased in the HeLa cells with survivin mutants compared with that in the parental HeLa cells. The HeLa cells transfected instantly with survivin mutants could undergo apoptosis automatically. Meanwhile, survivin mutants could cause an increase of multinuclear HeLa cells. The effect of survivin-N showed more effective than that of survivin T34A. Survivin-N and survivin T34A could influence the expression of cyclin D1 and reduced its protein levels of 68% and 12%, respectively. CONCLUSION: Survivin mutants can partially reverse the malignancy of HeLa cells. The reduction of cyclin D1 induced by survivin mutants may play an important role in it. Survivin may be a target gene in gene therapy of cancer.