Molecular analysis of the coat protein gene of peanut stripe virus from China

Peanut stripe virus (PStV) is one of the most common viruses infecting peanut that causes great economic losses every year. The 3ʹ-terminal 1082 bp of 74 PStV isolates collected from 12 districts of Shandong province, China were sequenced. Their coat protein (CP) genes were 864 bp in length and shared identities of 98.0%~100% and 98.3% ~100% at nt and aa levels. The identities between the CP genes of these isolates and other 36 isolates from the GenBank were 93.5%~100% and 92.0%~100% at nt and aa levels, respectively. PStV isolates can be clustered into two phylogenetic groups. The isolates from United States, mainland China, and Indonesia formed group I and those from Viet Nam, Thailand, and Taiwan formed group II. The PStV isolates in group I can be further classified to two subgroups. The gene flow of PStV populations within a country was frequent, but that between countries was infrequent.

A multi-mode screech frequency prediction formula for circular supersonic jets

A time evolution analysis is presented for the interaction between the instability waves, shock cells, and screech tones based on the authors' previous numerical simulation database. An attachment and reinforcement process of the upstream propagating screech waves with the downstream hydrodynamic waves is identified and recognized as part of the screech loop. The first five shock cells are recognized as the effective sound source region. Through an analysis of the phase variation in the dominant pressure fluctuations for several typical Mach number screeching jets, it is found that the total number of the instability waves and the upstream feedback sound waves in the effective source region can be identified as 5 for the A1, B, and D modes and 6 for A2 and C modes, respectively. A screech tone frequency prediction formula is thus proposed based on this relation. The predicted screech wavelengths or Strouhal numbers of cold and hot jets all agree well with the experimental data by other researchers, except for a small discrepancy for the B mode. It is also noticed that the measured two A0 modes by Ponton et al. [NASA Technical Memorandum No. 113137, Langley Research Center (1997)] can be classified to A1 and A2 modes, respectively, according to the proposed formula.

Celecoxib reduces symptoms in men with difficult chronic pelvic pain syndrome (Category IIIA)

We investigated the effectiveness of celecoxib in reducing symptoms in patients with difficult chronic pelvic pain syndrome (CPPS), NIH category IIIA. Sixty-four patients with category IIIA CPPS were randomized into two groups of 32 subjects each. One group was treated with celecoxib (200 mg daily) and the other with placebo. All patients underwent treatment for 6 weeks and were evaluated clinically before (baseline) and after 1, 2, 4, 6, and 8 weeks of treatment. The evaluation included the NIH Chronic Prostatitis Symptom Index (NIH-CPSI) and a subjective global assessment (SGA). Repeated measures analysis of variance was used to evaluate treatment and time effects and their interaction. A decrease (means +/- SD) in total NIH-CPSI score from 23.91 +/- 5.27 to 15.88 +/- 2.51 in the celecoxib group and from 24.25 +/- 5.09 to 19.50 +/- 2.50 in the placebo group was observed during treatment (0 to 6 weeks). A statistically significant decrease was observed in pain subscore (P < 0.006), quality of life subscore (P < 0.032) and total NIH-CPSI score (P < 0.015) after 2, 4 and 6 weeks, but not in urinary subscore. In addition, 38% of the celecoxib and 13% of the placebo subjects had at least a moderate improvement in SGA. The trend was similar for the NIH-CPSI scores. However, the response to treatment in terms of total NIH-CPSI score or subscore was not significantly different from placebo after interruption of treatment for 2 weeks. Our results show that celecoxib provides significant symptomatic improvement limited to the duration of the therapy in patients with difficult category IIIA CPPS compared to placebo.

Cadmium and other metal uptake by Lobelia chinensis and Solanum nigrum from contaminated soils

Cadmium concentrations in two plant species and their corresponding soils were evaluated in a metal contaminated area. The average Cd concentrations reached 36.9 and 141 mg kg(-1) in Solanum nigrum leaves and Lobelia chinensis shoots, respectively. There is a significant relationship between the Cd concentration in the aerial tissues and the corresponding soils on a logarithmic scale. Under the hydroponic culture conditions, the maximum Cd concentration in the S. nigrum leaves and L. chinensis shoots were 1,110 and 414 mg kg(-1), respectively. Cd concentration was higher in the roots than in the aerial parts. The two plants may be used in suitable phytoremediation process.

Molecular variability of five Cucumber mosaic virus isolates from China

Cucumber mosaic virus (CMV) isolates are currently divided into two main groups, I and II according to their genomic sequences. The group I is further divided into two subgroups IA and IB. We performed a phylogenetic analysis of the genome regions containing 1a, 2a, 2b, coat protein (CP), and movement protein (MP) genes of 5 CMV isolates from China and other 28 CMV isolates available in the GenBank. The results indicated that CMV isolates could be genetically divided into three groups I, II, and III according to the genes encoding MP, CP, 1a, and 2a proteins and to the 2 groups according to the gene 2b. Group I could be further divided into two subgroups (IA and IB) according to the genes encoding CP, MP, 2a, and 2b proteins and to the three subgroups (IA, IB, and IC) according to the gene encoding 1a protein. Four of 5 examined Chinese CMV isolates belonged to the subgroup IB, while the remaining isolate was a natural inter-subgroup reassortant. We found that the 2b gene of CMV was under positive selection, while the other genes were under negative selection. No evidence of the selection associated with a host adaptation or geographic distribution was found.

Degradation of gas-liquid gliding arc discharge on Acid Orange II

The effects of pH value, initial concentration of dye solution and temperature on the degradation efficiency of Acid Orange II (AO7) using gas-liquid gliding arc discharge were investigated. The influences of pH value and temperature on degradation efficiency were not apparent. Increasing initial solution concentration caused the decrease of degradation rate and the increase of absolute degradation quantity. Considering energy efficiency and absolute degradation quantity, the gas-liquid gliding arc discharge is fit for treating high concentration organic wastewater. A possible mineralization pathway was proposed through the analysis of intermediate products detected by gas chromatograph coupled with mass spectrophotometer (GC-MS) and ion chromatograph (IC). Hydroxyl radicals reacted with the azo linkage-bearing carbon of a hydroxy-substituted ring, leading to the cleavage of -C-N- and degradation of AO7. The solution biodegradability was significantly improved (BOD(5)/COD from 0.02 to 0.43). The toxicity of intermediate products was lower than that of the initial Acid Orange II.

PCDD/F concentrations of agricultural soil in the vicinity of fluidized bed incinerators of co-firing MSW with coal in Hangzhou, China

The concentrations of 17PCDD/F congeners as well as tetra- to octa-homologues were determined in 33 soil samples collected within a radius of 7 km from a municipal solid waste (MSW) incineration plant that is equipped with three fluidized bed incinerators (FBIs) of co-firing MSW with coal in Hangzhou, China. The total PCDD/F concentrations ranged from 0.39 to 5.04 pg I-TEQ g(-1) (54-285 pg g(-1)), with an average and a median value of 1.22 and 0.84 pg I-TEQ g(-1) (105 and 86 pg g(-1)), respectively. A systematic decrease of PCDD/F levels was observed with the increasing distances and with the decreasing downwind frequencies from the plant. The comparisons of homologue and congener patterns and multivariate analysis of soil and flue gas samples strongly indicated that most of the soil samples were influenced by the FBIs. Apart from the incineration plant, historical PCDD/F emissions of hazardous waste incinerator (HWI) and motor vehicles as well as the application of 1,3,5-trichloro-2-(4-nitrophenoxy) benzene (CNP) seemed to play an important role in soil samples adjacent to these potential sources.

Characteristic of polychlorinated dibenzo-p-dioxins and dibenzofurans in fly ash from incinerators in china

Fly ash from municipal solid waste (MSW), medical waste (MW) and electrical power plant (EPP) incinerators were analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The study showed that the PCDD/F levels in fly ash were EPP<MSW<MW. The homologue profiles of PCDD/Fs in fly ash produced from waste incinerators were similar. However, the homologue profiles of PCDD/Fs in fly ash from electrostatic precipitator (ESP) of electrical power plant were different from that from waste incinerator. The strong correlation was found between the concentration of 2,3,4,7,8-PeCDF and the I-TEQ value of fly ash regardless of the different fly ashes sources.

Effects of calcium-based sorbents on PCDD/F formation from pentachlorophenol combustion process

Calcium-based sorbents are widely employed to reduce the acidic gases emission from combustion processes, and also have effects on trace organic pollutants formation and emission. Batch experiments were conducted to investigate the effects of calcium-based sorbents on pentachlorophenol (PCP) forming PCDDs/Fs during high temperature combustion processes. The results indicated that highly chlorinated PCDD/F homologues were the predominant dioxin products from PCP thermo decomposition, and only minor increasing of PCDDs happened when Ca/Cl ratio was lower than 1, while a major jump occurred when Ca/Cl ratio increased from 1 to 2. The CaO addition clearly promoted the production of all chlorinated dibenzo-p-dioxins homologue and 4-7DFs homologue. Comparison of total PCDD/F emission and its I-TEQ for three different calcium-based sorbents addition (CaO, CaCO3, basic fly ash) indicated that CaO and fly ash containing CaO had almost the same promotion effects on PCDDs/Fs originated from PCP, while CaCO3 inhibit PCDD/F formation greatly with inhibition efficiency up to 70%. Such effects may be partly proved by the observed clearly different micro-surface structures of their reaction residues. The mechanism of CaO on condensation and dechlorination reactions for PCP forming PCDDs and acid-base interaction were proposed to speculate the promotion effects of CaO, and the reaction precedence was used to speculate the inhibition effects of CaCO3 on PCDDs/Fs originated from PCP. The results of the present paper might be useful for the industrial application of calcium-based sorbents to control PCDD/F emission.

Degradation of PCDD/Fs by mechanochemical treatment of fly ash from medical waste incineration

The potential of mechanochemical treatment (MC) to degrade PCDD/Fs contained in fly ash was tested via grounding with and without calcium oxide (CaO) under atmospheric pressure. Three types of fly ash collected from medical waste incineration were compared, originating either from rotary kiln fluidized bed multi-stage incinerator using activated carbon spray (FA1, FA2), or a simple stoker incinerator without activated carbon spray (FA3). In test I: CaO to FA1 mixed at ratio of 6-60% was milled at rotational speed of 350 rpm; in test II: FA2 and FA3 without CaO were milled at rotational speed of 400 rpm. The duration of the tests was 2h. The results from the present study indicate that (1) under two test conditions of with and without CaO, PCDD/Fs contained in real fly ash both can be degraded by mechanochemical treatment, (2) under condition of blending with CaO, the degradation efficiency of PCDD/Fs increased with increasing ratio of CaO, (3) the degradation efficiency of PCDD/Fs may increase with rotational speed increasing and (4) the destruction and dechlorination are major mechanism for PCDD/Fs degradation. These results show that mechanochemical treatment is a high potential technology for PCDD/Fs degradation in fly ash.

First Report of Spirea Witches'-Broom Disease in China

Bumald spirea (Spiarea bumalda Burv.) is an important ornamental tree widely grown in northern China. In August of 2006, spirea plants exhibiting symptoms of witches'-broom, stunting, yellowing, and shoot dieback were found at an incidence of 5 to 15% in Qingzhou City, Shandong Province, China. Total DNA was extracted separately from 0.1 g of phloem tissue from leaf midribs and stems of six symptomatic and six asymptomatic plants with a modified cetyltriethylammonium bromide (CTAB) method (3). Resulting DNA samples were analyzed for phytoplasma DNA by a nested PCR assay using phytoplasma universal 16S rDNA gene primer pairs R16mF2/R16mR1 and R16F2n/R16R2 (2). These primers amplified 1.5- and 1.2-kb products, respectively, from DNA of all symptomatic plants only. Restriction fragment length polymorphism (RFLP) analysis of the 1.2-kb 16S rDNA product using enzymes AluI, MseI, and HhaI indicated that all symptomatic plants contained a group 16SrI (aster yellows group) subgroup B (16SrI-B) phytoplasma strain (4). A 16S rDNA sequence derived from this strain (GenBank Accession No. EF176608) was most similar (99.8 and 99.6%) to those of severe aster yellows (GenBank Accession No. M86340) and Maryland aster yellows (GenBank Accession No. AF322644) phytoplasmas, respectively, thereby confirming strain identity based on RFLP analysis. A phytoplasma (Spiarea stunt phytoplasma, GenBank Accession No. AF190228), which belongs to X-disease group (16SrIII), was reported to infect spirea and probably be lethal to S. tomentosa in New York (1,4). The phytoplasma reported here shared low identity (90.8%) with Spiarea stunt phytoplasma, but also caused dieback of spirea shoots. The epidemiology and economic impact of this disease need further intensive investigation. To our knowledge, this is the first report of spirea witches'-broom disease and of its association with a subgroup 16SrI-B phytoplasma in China. References: (1) H. M. Griffiths et al. Can. J. Plant Pathol. 16:255, 1994. (2) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (3) Y. Qi et al. Biotechnol. Bull. 4:44, 2004. (4) The IRPCM Phytoplasma/Spiroplasma Working Team-Phytoplasma Taxonomy Group. Int. J. Syst. Bacteriol. 54:1243, 2004.

Different plantar interface effects on dynamics of the lower limb

The moments acting on the lower limb joints influence the life of the arthrosis. These loads may depend on the footwear and action style. The footwear factor was studied with three-dimensional gait measure system. Five young women in their 20s, wear 7 cm high-heeled shoes and sneakers, and walked in 10 m gait laboratory walkway. Inversed dynamics was used to analysis the torques at the ankle, knee and hip. Results showed that peak adduction moments at the knee and ankle increased and flexion/extension moments at hip increased with high-heel shoes compared with the sneakers. The high-heeled shoes result in greater load in lower limb joints especial to the knee and hip.

Development of a fast scanning miniature probe and methods of dispersion management for high-resolution optical coherence tomography

We present a design of a miniature fiber-optic probe capable of rapid lateral scanning. The miniature probe permits forward-looking optical coherence tomography (OCT) imaging of internal organs in real time. Fast lateral scanning also enables a new real-time image acquisition sequence, potentially permitting real-time focus tracking. To perform sensitive heterodyne detection, a sufficient Doppler frequency is achieved by using an electro-optic (EO) phase modulator. In this paper we describe an effective approach to compensate the dispersion induced by the EO crystal up to the third order. We show that an optimal axial resolution offered by the light source can be recovered through the dispersion management. Preliminary results of real-time OCT imaging of biological tissues with the lateral-priority scanning probe are presented.

Impaired clearance of phenacetin in hepatic cirrhosis and fibrosis

OBJECTIVE

CYP450 1A2 is constitutively expressed in liver. Phenacetin O-de-ethylation is a marker reaction for CYP450 1A2 activity. In this paper, the metabolism of phenacetin has been studied in patients with chronic hepatitis B or cirrhosis secondary to a hepatitis B virus infection. The possibility of using the phenacetin test in the evaluation of liver function in these subjects has also been tested.

SUBJECTS AND METHODS

Phenacetin pharmacokinetics and the recovery of its urinary metabolites were studied in 8 normal subjects, 16 patients with chronic hepatitis B and 12 patients with cirrhosis. The phenacetin test was performed in 18 normal subjects and 52 hepatocellular carcinoma (HCC) patients. The test was repeated in HCC patients after treatment with transcatheter arterial chemoembolization (TACE).

RESULTS

Compared with normal controls, phenacetin apparent clearance decreased by 47.0% (p < 0.05) and 78.7% (p < 0.01) in patients with chronic hepatitis B and cirrhosis, respectively. The recovery of phenacetin O-de-ethylated metabolites decreased by 24.6 and 72.4% (p < 0.01). 46 of 52 HCC patients (88.4%) had an abnormal phenacetin test before TACE, where the ratio of plasma total acetaminophen to phenacetin was below the lower limit of the normal control range. The ratio was less than 50% of normal controls in 6 HCC patients who had a deterioration in liver function from Child-Pugh class A to Child-Pugh class B after TACE.

CONCLUSION

The metabolism of phenacetin is impaired in patients with chronic hepatitis B and cirrhosis. The phenacetin test can predict the susceptibility of liver function to TACE in HCC patients.

[Screening and cloning of the down-regulation gene by recombinant interferon-B using suppression subtractive hybridization technique.]

BACKGROUND

To construct a subtractive cDNA library of target genes down-regulated in human hepatocarcinoma cell line HepG2 cells treated with IFNB, and clone genes of the down-regulation by IFNB using suppression subtractive hybridization (SSH) technology and bioinformatics techniques.

METHODS

The mRNA was isolated from HepG2 cells induced by recombinant interferon-B and 0.9 percent sodium chloride, respectively, then cDNA was synthesized. After restriction enzyme Rsa I digestion, small sizes cDNAs were obtained. Then tester cDNA was divided into two portions and each was ligated to the specific cDNA adaptor 1 and adaptor 2 respectively. After tester cDNA was hybridized with driver cDNA twice and underwent two times of nested PCR, the DNA fragment was subcloned into T/A plasmid vectors to set up the subtractive library. Amplification of the library was carried out with E.coli strain DH5a. The cDNA was sequenced and analyzed in GenBank with Blast search after PCR.

RESULTS

The subtractive library of genes down-regulation in HepG2 cells treated with recombination interferon-B was constructed successfully. The amplified library contained 58 positive clones. Colony PCR and sequence analysis was performed in 35 clones randomly, and the full length sequences were obtained with bioinformatics method. Altogether 12 coding sequences were obtained.

CONCLUSION

A subtractive cDNA library of genes down-regulation in HepG2 cells treated with IFNB using SSH technique was constructed successfully, which brings some new clues for studying the regulation mechenism of IFNB in liver cells.

Heavy metal contamination and distribution in the urban environment of Guangzhou, SE China

Ever-increasing heavy metal accumulation in the urban environment of Guangzhou, the largest light industrial production base and one of the most rapidly developing cities in China, poses a serious threat to environment as well as to human health in the region. As a sink or source, urban deposits are good indicators of the level and extent of heavy metal accumulation in the surface environment. The aim of this preliminary study was to examine the distribution of heavy metal contamination in the urban environment of Guangzhou. It was based on a systematic sampling of road dusts and corresponding gully sediments along major roads running mainly through commercial and residential to industrial districts of the city. In addition to road dusts and gully sediments, ceiling dusts from the Pearl River Tunnel were also collected to characterize anthropogenic emissions dominated by traffic-related activities. In general, the level of Cd, Cu, Pb and Zn contaminations were more severe on the industrialized side of Guangzhou than on the western side where heavy traffic and industrial activities were limited. The primary determinants of the level of heavy metal contamination and the distribution of this contamination in the urban environment of Guangzhou were the site-specific conditions of its urban setting, particularly the types of industries, the nature of the traffic flow, sample residence times and variations in grain size of the particulate contaminants. This study highlights the complexity of the urban system and indicates that in just such a system individual urban components should be interlinked to assess the long-term environmental and health effects of heavy metal contamination. Among the heavy metals tested--Cd, Cu, Pb and Zn--the level of Zn contamination was the most severe and widespread, and thus requires immediate attention.

Evaluation of PCDD/Fs emission from fluidized bed incinerators co-firing MSW with coal in China

The levels and homologue profile of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from stack gas of three typical fluidized bed incinerators co-firing municipal solid waste (MSW) with Chinese coal were measured. The PCDD/Fs emission was in the range of 0.0054-0.1961 ng I-TEQ/N m(3). Comparison of PCDD/Fs detection results by HRGC/HRMS and HRGC/LRMS suggested that it was feasible to detect fly ash with high PCDD/Fs concentration by HRGC/LRMS. Several factors on PCDD/Fs emission were discussed. The primary reason for the lower PCDD/Fs emission was the inhibition mechanism of relatively high sulfur in feeding coal on PCDD/Fs formation. The emission results also showed that there was no directly correlation between PCDD/Fs levels and CO, O(2) and HCl concentration in flue gas. It was estimated that about 0.1034 g I-TEQ was annually emitted to atmosphere from the tested three MSW incinerators (total daily treatment capacity is 800 tonnes MSW).

Detection of adeno-associated virus type 2 genome in cervical carcinoma

Adeno-associated virus (AAV) can impair the replication of other viruses. Adeno-associated virus seroprevalences have been reported to be lower among women with cervical cancer. In-vitro, AAV can interfere with the production of human papillomavirus virions. Adeno-associated virus-2 DNA has also been detected in cervical cancer tissue, although not consistently. To evaluate the role of AAV infection in relation to invasive cervical cancer, we performed a nested case–control study within a retrospectively followed population-based cohort. A total of 104 women who developed invasive cervical cancer on average 5.6 years of follow-up (range: 0.5 months–26.2 years) and 104 matched control-women who did not develop cervical cancer during the same follow-up time were tested for AAV and human papillomavirus by polymerase chain reaction. At baseline, two (2%) case-women and three (3%) control-women were positive for AAV-2 DNA. At the time of cancer diagnosis, 12 (12%) case-women and 3 (3%) matched control-women were positive for AAV-2 DNA. Persisting AAV infection was not evident. In conclusion, AAV-2 DNA was present in a low proportion of cervical cancers and we found no evidence that the presence of AAV in cervical smears of healthy women would be associated with reduced risk of cervical cancer.

Source seasonality of polycyclic aromatic hydrocarbons (PAHs) in a subtropical city, Guangzhou, South China

Mega-cities are large sources of air pollution on a regional base. Differences in energy structures, geographical settings and regional climate features lead to a large variety of air pollution sources from place to place. To understand the seasonality of air pollution sources is critical to precise emission inventories and a sound protection of human health. Based on a year-round dataset, the sources of PAHs in the air of Guangzhou were drawn by principal factor analysis (PCA) in combination with diagnostic ratios, and the seasonality of these sources were analyzed by PCA/MLR (multiple linear regressions) and discussed. The average total gaseous and particulate PAHs concentrations were 313 and 23.7 ng m(-3), respectively, with a higher concentration of vapor PAHs in summer and particulate PAHs in winter. In addition to vehicle exhaust, which contributed 69% of the particulate PAHs, coal combustion was still an important source and contributed 31% of the particulate PAHs. Relatively constant contribution from coal combustion was found through the year, implying that coal combustion in power plants was not a seasonally dependent source. Evaporation from contaminated ground may be an important source of light PAHs in summer, providing an average contribution of 68% to the total PAHs in this study. By comparing the PAH concentrations and meteorological parameters, we found that higher concentrations of particulate PAHs in winter resulted from enhanced vehicle exhaust under low temperature and accumulation of pollutants under decreased boundary layer, slower wind speed, and long-term dryness conditions. It is suggested that the typical subtropical monsoon climate in South China, cool and dry in winter, hot and humid in summer, may play a key role in controlling the source seasonality (by enhancing vehicle exhaust in winter, ground evaporation in summer), and hence the ambient concentrations of PAHs in the air.

Heavy metal and Pb isotopic compositions of aquatic organisms in the Pearl River Estuary, South China

The accumulation of trace metals in aquatic organisms may lead to serious health problems through the food chain. The present research project aims to study the accumulation and potential sources of trace metals in aquatic organisms of the Pearl River Estuary (PRE). Four groups of aquatic organisms, including fish, crab, shrimp, and shellfish, were collected in the PRE for trace metal and Pb isotopic analyses. The trace metal concentrations in the aquatic organism samples ranged from 0.01 to 2.10 mg/kg Cd, 0.02 to 4.33 mg/kg Co, 0.08 to 4.27 mg/kg Cr, 0.15 to 77.8 mg/kg Cu, 0.17 to 31.0 mg/kg Ni, 0.04 to 30.7 mg/kg Pb, and 8.78 to 86.3 mg/kg Zn (wet weight). High concentrations of Cd were found in crab, shrimp and shellfish samples, while high concentration of Pb was found in fish. In comparison with the baseline reference values in other parts of the world, fish in the PRE had the highest elevated trace metals. The results of Pb isotopic compositions indicated that the bioaccumulation of Pb in fish come from a wide variety of food sources and/or exposure pathways, particularly the anthropogenic inputs.

Sedimentary record of polycyclic aromatic hydrocarbons in a sediment core from the Pearl River Estuary, South China

Owing to the hydrodynamic and sedimentation conditions, the western shoal of the Pearl River Estuary (PRE) is known to be an important sink of terrestrial substances including particle-associated pollutants from the Pearl River Delta (PRD) region. In this study, we report the sedimentary record of polycyclic aromatic hydrocarbons (PAHs) during the 20(th) century in a sediment core from the western shoal of the PRE. The summation PAH concentration ranged from 59 ng g(-1) to 330 ng g(-1) in the core with two distinct peaks. An initial increase of summation PAH concentration was found around the 1860s. The amounts of PAHs remained relatively constant for roughly 100 years, followed by the first peak in the 1950s. Then, there was a decrease in PAH concentration and flux in the 1960s and 1970s. A sharp increase of PAH concentration was observed in the early 1980s with a maximum concentration in the 1990s. The PAH diagnostic ratios indicated that the PAHs in the sediment core were mainly of pyrolytic origin, and that atmospheric deposition and land runoff may serve as the important pathways for PAHs input to the sediment. The Gross Domestic Product (GDP) was used as an index of socioeconomic development in the PRD region, which was correlated positively with the changes of PAH concentration and flux in the sediment core. The rapid increase in vehicle numbers and energy consumption in the region in the last two decades may have contributed to the rapid PAH increase since the early 1980s. The results clearly elucidated the impact of regional economic development on the estuarine environment.

Over one hundred years of trace metal fluxes in the sediments of the Pearl River Estuary, South China

The rapid economic development in the Pearl River Delta (PRD) region in South China in the last three decades has had a significant impact on the local environment. Estuarine sediment is a major sink for contaminants and nutrients in the surrounding ecosystem. The accumulation of trace metals in sediments may cause serious environmental problems in the aquatic system. Thirty sediment cores were collected in the Pearl River Estuary (PRE) in 2000 for a study on trace metal pollution in this region. Heavy metal concentrations and Pb isotopic compositions in the four 210Pb-dated sediment cores were determined to assess the fluxes in metal deposits over the last one hundred years. The concentrations of Cu, Pb and Zn in the surface sediment layers were generally elevated when compared with the sub-surface layers. There has been a significant increase in inputs of Cu, Pb and Zn in the PRE since the 1970s. The results also showed that different sampling locations in the estuary received slightly different types of inputs. Pb isotopic composition data indicated that the increased Pb in the recent sediments was of anthropogenic origin. The results of trace metal influxes showed that about 30% of total Pb and 15% of total Zn in the sediments in the 1990s were from anthropogenic sources. The combination of trace metal analysis, Pb isotopic composition and 210Pb dating in an estuary can provide vital information on the long-term accumulation of metals in sediments.

Modeling of configurations and third-order nonlinear optical properties of C36 and C34X2 (X=B,N)

Using the ab initio method, the geometrical structures of C(36) and the X (B,N)-doped isomers C(34)X(2) have been optimized. On the basis of the optimized structures, then, the third-order nonlinear optical polarizabilities gamma in the different optical processes of the third-harmonic generation, electric-field induced second-harmonic generation and degenerate four-wave mixing, and two-photon absorption (TPA) cross sections delta are calculated by using TDB3LYP method coupled with the sum-over-states method. The calculated results show that the one-photon allowed excitation process dominate the two-photon excitation process for C(36)-D(6h), whereas the two-photon allowed excitation process dominate the one-photon excitation process for C(36)-D(2d) and C(34)X(2) (B,N). It is found that the largest resonant TPA peaks of dopant fullerenes have a blueshift and the TPA cross sections have an enhancement compared with those of the parent fullerenes of isomers C(36)-D(6h) and C(36)-D(2d).