Optimization of sample pretreatment for determination of polycyclic aromatic hydrocarbons in estuarine sediments by gas chromatography

This study examined levels of polycyclic aromatic hydrocarbons (PAHs) in estuarine sediments in Licun (Qingdao, China) by gas chromatography under optimized conditions for sample pretreatment via ultrasonic extraction, column chromatography, and thin layer chromatography. Methanol and dichloromethane (DCM)/methanol (2:1, v/v) were used in ultrasonic extraction, and DCM was used as eluate for column chromatography. The developing system consisted of n-hexane and DCM at a ratio of 9:1 (v/v), with DCM as the extraction solvent for PAHs-containing silica gel scraped off the plate. When the spiking level is 100 ng, total recoveries of spiked matrices for four target PAHs (phenanthrene, anthracene, pyrene and chrysene) were 83.7%, 76.4%, 85.8%, and 88.7%, respectively, with relative standard deviation (RSD) between 5.0% and 6.5% (n = 4). When the spiking level is 1000 ng, associated total recoveries were 78.6%, 72.7%, 82.7% and 85.3%, respectively, with RSD between 4.4% and 5.3% (n = 4). The opti-mized method was advantageous for determination of PAHs in complex matrix due to its effective sample purification.     

Optimization of ultrasonic extraction and clean-up protocol for the determination of polycyclic aromatic hydrocarbons in marine sediments by high-performance liquid chromatography coupled with fluorescence detection

The procedures of ultrasonic extraction and clean-up were optimized for the determination of polycyclic aromatic hydrocarbons (PAHs) in marine sediments. Samples were ultrasonically extracted, and the extracts were purified with a miniaturized silica gel chromatographic column and analyzed with high performance liquid chromatography (HPLC) with a fluorescence detector. Ultrasonication with methanol-dichloromethane (2:1, v/v) mixture gave higher extraction efficiency than that with dichloromethane. Among the three elution solvents used in clean-up step, dichloromethane-hexane (2:3, v/v) mixture was the most satisfactory. Under the optimized conditions, the recoveries in the range of 54.82% to 94.70% with RSDs of 3.02% to 23.22% for a spiked blank, and in the range of 61.20% to 127.08% with RSDs of 7.61% to 26.93% for a spiked matrix, were obtained for the 15 PAHs studied, while the recoveries for a NIST standard reference SRM 1941b were in the range of 50.79% to 83.78% with RSDs of 5.24% to 21.38%. The detection limits were between 0.75 ng L-1 and 10.99 ng L-1for different PAHs. A sample from the Jiaozhou Bay area was examined to test the established methods.     

Determination of Steroid Hormone Residues in Fish Tissues Using Gel Permeation Chromatography and Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

A highly sensitive method was developed for the simultaneous determination of 8 steroid hormones in high-fat fish tissues using ultra high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The 8 steroid hormones were extracted from the tissues with diethyl ether.Differing from other common purification methods,the extract solutions were cleaned by gel permeation chromatography(GPC) using ethyl acetate-cyclohexane solution(1:1,v/v) as the mobile phase.The separation of target compounds was carried out by a BEH C18 column and a gradient elution consisting of acetonitrile and 0.2% aqueous formic acid(v/v).The compounds were detected under the multiple reaction monitoring(MRM) mode and quantified with external standard method.This method was validated with respect to linearity,specificity,accuracy and precision.A linearity with correlation coefficient larger than 0.995 was achieved in the range of 0.5 to 50 ng m L~(-1).The average recoveries at the spiked levels of 1.0,5.0,and 10.0 μg kg~(–1) varied between 81.7% and 90.8%,with the relative standard deviations(n=5) ranged from 3.50% to 10.0%.The limit of quantification(LOQ) for 8 steroid hormones ranged from 0.2 to 1.5 μg kg~(-1).It was concluded that this method can be successfully applied for the determination of 8 steroid hormones in complicated matrices including high-fat fish tissues.     

Retreived bacteria from Noctiluca miliaris (green) bloom of the northeastern Arabian Sea

In recent years, seasonal blooms of the dinoflagellate Noctiluca miliaris have appeared in the open-waters of the northern Arabian Sea (NAS). This study provides the first characterization of bacteria from a seasonal bloom of green Noctiluca of NAS (20°N?17°N and 64°E–70°E), during the spring-inter-monsoon cruise of Sagar Sampada 253, in March 2007. Bacterial growth as assessed by most-probable number (MPN) and plate counts, revealed ‘variable-physiotypes’ over a wide range of salinities (0%–25% w/v NaCl), pH levels (5–8.5), and organic nutrient strengths, in comparison to non-bloom waters. MPN indices of bacteria in surface waters of bloom stations *DWK and *PRB, corresponded to (3.08–4.41)×10³ cells/mL at 3.5% NaCl (w/v), and (2.82–9.49)×10² cells/mL at 25% (w/v) NaCl in tryptone-yeast extract broth (TYE). Plate counts were (1.12–4)×10⁶ CFU/mL at 0% (w/v) NaCl, (1.28–3.9)×10⁶ CFU/mL at 3.5% (w/v) NaCl, and (0.4–7)×10⁴ CFU/mL at 25% NaCl (w/v) on TYE. One-tenth-strength Zobell’s gave (0.6–3.74)×10⁵ CFU/mL at pH 5 to (3.58–7.5)×10⁵ CFU/mL at pH 8.5. These bacteria were identified to the genera Bacillus, Cellulomonas, Staphylococcus, Planococcus, Dietzia, Virgibacillus, Micrococcus, Sporosarcinae, Leucobacter, and Halomonas. The identity of three strains (GUFBSS253N2, GUFBSS253N30, and GUFBSS253N84) was confirmed through 16S rDNA sequence homology as Bacillus cohnii, Bacillus flexus, and Bacillus cereus. The ～2–3-fold higher plate counts of culturable bacteria from the open-waters of the NAS indicate that these bacteria could critically determine the biogeochemical dynamics of the bloom and its milieu. The role of these bacteria in sustaining/terminating the bloom is under evaluation.     

Preparation of polysaccharides in different molecular weights from Ulva pertusa Kjellm (Chorophyta)

As molecular weight controls the biological activities of polysaccharides, screening the optimal molecular weight of polysaccharides is important in drug research and application. In this study, hydrogen peroxide was employed as oxidant, and temperature, reaction time, and concentration of polysaccharides and hydrogen peroxide were examined for their effects on the preparation of polysaccharides in different molecular weights fromUlva pertusa. Our experiment suggested that the optimal degradation concentrations for polysaccharides and hydrogen peroxide were 2.5% (w/v) and 8.0% (v/v), respectively. The range of degradation measured by relative viscosity was mainly controlled by temperature and time. Results revealed that 35°C was the optimal temperature for obtaining low-degradation samples, and 50°C was the most favorable temperature to accelerate the reaction to yield highly-degraded samples. Four samples in different molecular weights A, B, C and D were finally prepared. The controllability was evaluated by the relative standard deviation (RSD) of relative viscosity, and the peak molecular weights and the polydispersity indexes (M_w/M_n) of molecular weights were measured by high performance gel permeation chromatography (HPGPC). This work was supported by the Scientific and Technical Bureau of Shandong Province.     

Studies on Bioflocculant Production by Pseudoalteromonas sp.NUM8, a Marine Bacteria Isolated from the Circulating Seawater

A bioflocculant producing potential bacteria was isolated from the circulating seawater of bio-filter using streak plate methods. The bacteria was identified through biochemical characteristics, partial 16 S ribosomal ribonucleic acids(rRNA), nucleotide sequencing, and BLAST analysis of the gene sequence that showed the bacteria have 99% similarity to Pseudoalteromonas sp.and deposited in GenBank as Pseudoalteromonas sp. NUM8 with accession number JX435820. Influences of time course assay,carbon sources, nitrogen sources, inoculum size, as well as initial pH on the bacteria producing extracellular bioflocculant activity were investigated. The results showed that the strain optimal production period of microbial bioflocculant was at 72 h(flocculating activity of 94.5%), then dropped slowly. The bacteria optimally produced the bioflocculant when 1.0% sucrose and 0.5% sodium nitrate were used as sole sources of carbon and nitrogen with flocculating activities of 92.8% and 93.8% respectively. Also, the bacteria produced the bioflocculant optimally when initial pH of the medium was 5.0(flocculating activity 93.2%), and when Ca~(2+)was used as cation(flocculating activity 93.4%). The culture condition of inoculum size of 3%(v/v) was optimal flocculant production(flocculating activity 94.4%). Composition analyses indicated the bioflocculant to be principally a glycoprotein made up of about 34.3% protein and 63.4% total carbohydrate.     

Antibacterial activity of extracts from <Emphasis Type="Italic">Zostera marina</Emphasis> against pathogens of <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> skin ulceration disease

The purpose of this study was to investigate the antibacterial activity of extracts from Zostera marina against the pathogens of Apostichopus japonicus skin ulceration disease. When 95% ethanol (v/v) solvent was used to extract Zostera marina at 50°C, aqueous extract (ZA) showed obvious bacteriostatic effects on the tested bacterial strains (inhibition halo diameters between 8.23 mm and 13.62 mm), whereas the ethyl acetate extract (ZE) was almost inactive. The minimal inhibitory concentration (MIC) of ZA against four pathogens were homogeneous at 12.8 g L⁻¹. ZA components were analyzed by thin layer chromatography (TLC) assay and six fractions were obtained. In another study, the six fractions showed inhibitory effects against the tested bacteria while their functions seemed to counteract the ZA activity.     

Cloning,expression and characterization of a lipase gene from marine bacterium <Emphasis Type="Italic">Pseudoalteromonas lipolytica</Emphasis> SCSIO 04301

A lipase gene, lip1233, isolated from Pseudoalteromonas lipolytica SCSIO 04301, was cloned and expressed in E. coli. The enzyme comprised 810 amino acid residues with a deduced molecular weight of 80 kDa. Lip1233 was grouped into the lipase family X because it contained a highly conserved motif GHSLG. The recombinant enzyme was purified with Ni-NTA affinity chromatography. The optimal temperature and pH value of Lip1233 were 45°C and 8.0, respectively. It retained more than 70% of original activity after being incubated in pH ranging from 6.0 to 9.5 for 30 min. It was stable when the temperature was below 45°C, but was unstable when the temperature was above 55°C. Most metal ions tested had no significant effect on the activity of Lip1233. Lip1233 remained more than original activity in some organic solvents at the concentration of 30% (v/v). It retained more than 30% activity after incubated in pure organic solvents for 12 h, while in hexane the activity was nearly 100%. Additionally, Lip1233 exhibited typical halotolerant characteristic as it was active under 4M NaCl. Lip1233 powder could catalyze efficiently the synthesis of fructose esters in hexane at 40°C. These characteristics demonstrated that Lip1233 is applicable to elaborate food processing and organic synthesis.     

A comparative analysis of four kinds of polysaccharides purified from Furcellaria lumbricalis

Four kinds of polysaccharides (FA, FB, FC and FD) were extracted and purified from a red alga Furcellaria lumbricalis. Their monosaccharide composition, average molecular mass and structural feature were determined by gas chromatography (GC), high performance gel permeation chromatography (HPGPC) and Fourier transform infrared spectroscopy (FTIR), respectively. The results showed that FA and FB were composed of galactose (Gal), 3,6-anhydro-galactose (AnG) and 4-sulfated-galactose (G4S), which were structurally similar to β-carrageenan and κ-carrageenan. FC was composed of sulfated galactose and small amount of AnG, indicating that it was a hybrid-sulfated galactan. FD was composed of α-1,4-glucose and belonged to floridean starch. The respective yields of FA, FB, FC and FD were 4.84%, 33.74%, 8.76% and 13.5%, and the corresponding were 537 kD, 432 kD, 513 kD and 51 kD respectively. Owning to its high content (>60%) of polysaccharide, F. lumbricalis will be a good source of marine sulfated polysaccharide and shows its potential utilization in food and medicine.     

Intercomparison of the Extended Reconstructed Sea Surface Temperature v4 and v3b Datasets

Version 4(v4) of the Extended Reconstructed Sea Surface Temperature(ERSST) dataset is compared with its precedent, the widely used version 3b(v3b). The essential upgrades applied to v4 lead to remarkable differences in the characteristics of the sea surface temperature(SST) anomaly(SSTa) in both the temporal and spatial domains. First, the largest discrepancy of the global mean SSTa values around the 1940 s is due to ship-observation corrections made to reconcile observations from buckets and engine intake thermometers. Second, differences in global and regional mean SSTa values between v4 and v3b exhibit a downward trend(around-0.032℃ per decade) before the 1940s, an upward trend(around 0.014℃ per decade) during the period of 1950–2015, interdecadal oscillation with one peak around the 1980s, and two troughs during the 1960s and 2000s, respectively. This does not derive from treatments of the polar or the other data-void regions, since the difference of the SSTa does not share the common features. Third, the spatial pattern of the ENSO-related variability of v4 exhibits a wider but weaker cold tongue in the tropical region of the Pacific Ocean compared with that of v3b, which could be attributed to differences in gap-filling assumptions since the latter features satellite observations whereas the former features in situ ones. This intercomparison confirms that the structural uncertainty arising from underlying assumptions on the treatment of diverse SST observations even in the same SST product family is the main source of significant SST differences in the temporal domain. Why this uncertainty introduces artificial decadal oscillations remains unknown.     

Mechanism Study of Endothelial Protection and Inhibits Platelet Activation of Low Molecular Weight Fucoidan from Laminaria japonica

Several studies have indicated that fucoidan fractions with low molecular weight and different sulfate content from Laminaria japonica could inhibit the activation of platelets directly by reducing the platelet aggregation. To explore the direct effect of LMW fucoidan on the platelet system furthermore and examine the possible mechanism, the endothelial protection and inhibits platelet activation effects of two LMW fucoidan were investigated. In the present study, Endothelial injury model of rats was made by injection of adrenaline(0.4 mg kg-1) and human umbilical vein endothelial cells were cultured. v WF level was be investigated in vivo and in vitro as an important index of endothelial injury. LMW fucoidan could significantly reduce v WF level in vascular endothelial injury rats and also significantly reduce v WF level in vitro. The number of EMPs was be detected as another important index of endothelial injury. The results showed that LMW fucoidan reduced EMPs stimulated by tumor necrosis factor. In this study, it was found that by inhibiting platelet adhesion, LMW fucoidan played a role in anti-thrombosis and the specific mechanism of action is to inhibit the flow of extracellular Ca2+. All in a word, LMW fucoidan could inhibit the activation of platelets indirectly by reducing the concentration of EMPs and v WF, at the same time; LMW fucoidan inhibited the activation of platelets directly by inhibiting the flow of extracellular Ca2+.     

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遥感降水产品在中国不同气候区的适用性研究

遥感降水产品相对于气象站观测数据能够更好地反映降水的空间分布特征,对其进行不同气候区上的差异性评价对数据产品选择和遥感降水反演算法改进均有重大意义.本文选择中国典型气候区(干旱区、过渡区、湿润区和青藏高原地区),以649个经偏差矫正后的气象站降水数据为标准,评估了5种国际常用的遥感降水产品(CHIRPS v2.0,CM...     

ANALYSIS ON THE PRESENT SITUATION ANDCONTRIBUTING FACTORS OF VACANT COMMERCIAL HOUSING IN GUANGZHOU URBAN DISTRICT

According to the on-the-spet sampling investigation, this paper analyzes the conditions of different dis-tricts, different locales and different types of the vacant commercial housing as well as the contributing factors, whichwas completed in recent three years in Guangzhou urban district. It is found that vacant ratio of samples in Gusngzhou accounted for 20. 94%, which is relatively high. The authors argue that real estate industry of Guangzhou has made rapid progress, at the same time, people should not overlook the vacant commercial housing. It will benefit the sustainable develop-ment of the real estate industry of Guangzhou to carry out effective measures and actively to make use of present vacanthousing.     

结合模糊度和形态学指数约束的深度学习建筑物提取

基于高分辨率遥感影像的建筑物提取一直是研究的热点问题,深度学习的深层次特征提取方法,非常适合高分辨率影像中建筑物的提取,但使用深度学习提取建筑物时,大多以改变网络结构为主进行算法优化,很少与其他方法结合.本文研究在改进深度学习网络结构的基础上,结合影像模糊度约束增强、形态学建筑指数约束增强等方法,对建筑物提取方法进行更...     

Seasonal Responses of Net Primary Productivity of Vegetation to Phen-ological Dynamics in the Loess Plateau,China

With global warming,the great changes in the patterns of plant growth have occurred.The conditions in early spring and late autumn have changed the process of v...     

灰线性加权非等距GM(1,1)形变预测模型

结合加权非等距GM(1,1)模型与线性回归理论,构建灰线性加权非等距GM(1,1)预测模型,并给出对模型预测精度起决定性作用的灰指数v和参数m的优化方法。与加权非等距GM(1,1)模型和线性回归预测模型相比,灰线性加权非等距GM(1,1)预测模型的精度更高,预测有效时间更长,模型的稳定性更好。优化v和m后,灰线性加权非等距GM(1,1)预测模型的实用性、稳定性进一步提高。     

Co-Production of Lipids,Eicosapentaenoic Acid,Fucoxanthin, and Chrysolaminarin by Phaeodactylum tricornutum Cultured in a Flat-Plate Photobioreactor Under Varying Nitrogen Conditions

The marine diatom Phaeodactylum tricornutum is a polymorphological, ecologically significant, and well-studied model of unicellular microalga. This diatom can accumulate diverse important metabolites. Herein, we cultured P. tricornutum in an internally installed tie-piece flat-plate photobioreactor under 14.5 m mol L~(-1)(high nitrogen, HN) and 2.9 m mol L~(-1)(low nitrogen, LN) of KNO_3 and assessed its time-resolved changes in biochemical compositions. The results showed that HN was inductive to accumulate high biomass(4.1 g L~(-1)). However, the LN condition could accelerate lipid accumulation in P. tricornutum. The maximum total lipid(TL) content under LN was up to 42.5% of biomass on day 12. Finally, neutral lipids(NLs) were 63.8% and 75.7% of TLs under HN and LN, respectively. The content of EPA ranged from 2.3% to 1.5% of dry weight during the growth period under the two culture conditions. Peak volumetric lipid productivity of 128.4 mg L~(-1)d~(-1) was achieved in the HN group(on day 9). The highest volumetric productivity values of EPA, chrysolaminarin, and fucoxanthin were obtained in the exponential phase(on day 6) under HN, which were 9.6, 93.6, and 4.7 mg L~(-1)d~(-1), respectively. In conclusion, extractable amounts of lipids, EPA, fucoxanthin, and chrysolaminarin could be obtained from P. tricornutum by regulating the culture conditions.     

利用双重索引快速构建道路网络连通拓扑

路网拓扑关系的生成是进行最优路径规划的基础。本文针对ISO GDF4.0模型对道路连通拓扑的定义,结合最优路径规划对道路网络连通拓扑的要求,提出一种使用R-tree空间索引和B-tree索引双重索引方式快速生成道路连通拓扑的算法。连通拓扑快速构建算法包括新道路生成和网络拓扑提取两部分,新道路生成过程中,首先,自上而下地打断道路形成直线段集并求交点,然后,自下而上地重构直线段集以生成新道路。在打断道路求交点过程中,对道路建立R-tree空间索引,显著提高了几何要素的查找速度。在网络拓扑提取过程中对序列化数据建立B-tree索引,使得其查找速度大大加快。通过对双重索引算法的时间复杂度分析与验证表明,本文提出的拓扑生成算法具有较高的执行效率。     

1980s-2005年内蒙古地区生态系统服务功能价值的时空变化分析

近几十年,内蒙古地区实施了诸多生态修复与保育工程。为了评估这些工程的实施成效,本文以土地利用/覆被变化(LUCC)为切入点,借助价值存量、价值增量、价值空间强度等参量,在全区和盟市尺度上,估算并分析了内蒙古地区陆地生态系统服务功能价值变化的时空特征及驱动因素。研究结果表明：(1)2000年以来,全区价值存量小幅度增加了0.24%,但价值增量的减少速度加快了32.9%,且中东部的变化大于西部;(2)在经济发展和人口增长的双重压力下,中东部平原耕作区、森林保育区深受国家宏观政策的影响,2000年后生态系统服务功能价值存量分别增加了4.52%、4.23%,价值增量分别增加了5.91亿元、8.88亿元;中西部山区草原荒漠化治理区受制于降水不显著的波动减少态势,2000年后生态系统服务功能价值存量增加了3.51%,但价值增量减少了4.22亿元;(3)2000年以来,中东部地区人类活动正向胁迫的影响力,由前期的45.8%增强到后期的76%,但中西部地区仍然面临着艰巨的生态治理压力。研究结果为科学合理划分生态功能区、规划实施生态修复与保育工程、建立生态补偿机制提供了参照。