A close phylogenetic relationship between Sipuncula and Annelida evidenced from the complete mitochondrial genome sequence of Phascolosoma esculenta

Background: There are many advantages to the application of complete mitochondrial (mt) genomes in the accurate reconstruction of phylogenetic relationships in Metazoa. Although over one thousand metazoan genomes have been sequenced, the taxonomic sampling is highly biased, left with many phyla without a single representative of complete mitochondrial genome. Sipuncula (peanut worms or star worms) is a small taxon of worm-like marine organisms with an uncertain phylogenetic position. In this report, we present the mitochondrial genome sequence of Phascolosoma esculenta, the first complete mitochondrial genome of the phylum. Results: The mitochondrial genome of P. esculenta is 15,494 bp in length. The coding strand consists of 32.1% A, 21.5% C, 13.0% G, and 33.4% T bases (AT = 65.5%; AT skew = -0.019; GC skew = -0.248). It contains thirteen protein-coding genes (PCGs) with 3,709 codons in total, twenty-two transfer RNA genes, two ribosomal RNA genes and a non-coding AT-rich region (AT = 74.2%). All of the 37 identified genes are transcribed from the same DNA strand. Compared with the typical set of metazoan mt genomes, sipunculid lacks trnR but has an additional trnM. Maximum Likelihood and Bayesian analyses of the protein sequences show that Myzostomida, Sipuncula and Annelida (including echiurans and pogonophorans) form a monophyletic group, which supports a closer relationship between Sipuncula and Annelida than with Mollusca, Brachiopoda, and some other lophotrochozoan groups. Conclusion: This is the first report of a complete mitochondrial genome as a representative within the phylum Sipuncula. It shares many more similar features with the four known annelid and one echiuran mtDNAs. Firstly, sipunculans and annelids share quite similar gene order in the mitochondrial genome, with all 37 genes located on the same strand; secondly, phylogenetic analyses based on the concatenated protein sequences also strongly support the sipunculan + annelid clade (including echiurans and pogonophorans). Hence annelid "key-characters" including segmentation may be more labile than previously assumed.

Relationship between the ennoblement of passive metals and microbe adsorption kinetics in seawater

The relationship between microbial colonization of two kinds of passive metals and ennobling of their corrosion potentials (E-corr) were studied. Two types of passive metal coupons were exposed to natural seawater for about ten days. Under laboratory conditions, all corrosion potentials of the samples ennobled for about 200 mV. Epifluorescence microscopy showed that bacteria adsorption was the main process during about the first day immersion and bacteria reproduced in the following days. The bacteria number increased on the metal surface according to an exponential law and the kinetics of bacteria adsorption at the metal surface during this period was proposed. The ennoblement of E-corr was similar to the increasing bacteria number: E-corr increased quickly during the bacteria adsorption process and increased slowly after biofilms had formed.

Molecular evidence for the sister relationship of the eastern Asia-North American intercontinental species pair in the Podophyllum group (Berberidaceae)

The presumed pair relationships of intercontinental vicariad species in the Podophyllum group (Sinopodophyllum hexandrum vs. Podophyllum pelatum and Diphylleia grayi vs. D. cymosa) were recently, considered to be paraphyletic. In the present paper, the trnL-F and ITS gene sequences of the representatives were used to examine the sister relationships of these two vicariad species. A heuristic parsimony analysis based on the trnLF data identified Diphylleia as the basal clade of the other three genera, but provided poor resolution of their inter-relationships. High sequence divergence was found in the ITS data. ITS1 region, more variable but parsimonyuninformative. has no phylogenetic value, Sequence divergence of the ITS2 region provided abundant, phylogenetically informative variable characters. Analysis of ITS2 sequences confirmeda sister relationship between the presumable vicariad species, in spite of a low bootstrap support for Sinopodophyllum hexandrum vs. Podophyllum pelatum. The combined ITS2 and trnL-F data enforced a sister relationship between Sinopodophyllum hexandrum and Podophyllum pelatum with an elevated bootstrap support of 100%. Based on molecular phylogeny, the morphological evolution of this group was discussed. The self-pollination might have evolved from cross-fertilization two times in this group. The different pollination and seed dispersal systems of Sinopodophyllum hexandrum and Podophlyllum pelatum resulted from their adaptations to different ecological habitats. The divergence time of Sinopodophyllum hexandrum-Podophyllum pelatum is estimated to be 6.52+/-1.89 myr based on the ITS divergence. The divergence of this species pair predated or co-occurred with the recent uplift of the Himalayas 4-3 myr during the late Miocene and the formation of the alpine habitats. Sinopodophyllum hexandrum developed a host of specialized characters in its subsequent adaptation to the arid alpine surroundings. The present study confirmed the different patterns of species relationship between Asian-North American disjuncts. The isolation of plant elements between North America and eastern Asia must have been a gradual process, resulting in the different phylogenetic patterns and divergence times of the disjuncts.

三维VSP技术的研究及应用

Today, because of high petroleum consumption of our country, society steady development and difficulty increase in new resources exploration, deep exploitation of the existing oilfield is needed. More delicate reservoir imaging and description, such as thin layer identification, interlayer exploitation monitoring, subtle structure imaging, reservoir anisotropy recognition, can provide more detail evidence for new development adjustment scheme and enhanced oil recovery. Now, the people have already realized the 3D VSP technique more effective than the general methods in solving these aspects. But VSP technique especially 3D VSP develop slowly due to some reasons. Carrying out the research of VSP technique, it will be very useful to the EOR service. 3D VSP techniques include acquisition、data processing and interpretation. In this paper, the author carried out some researches around acquisition and processing. The key point of acquisition is the survey design, it is critical to the quality of the data and it will influence the reservoir recognition as follows. The author did detailed researches on the layout pattern of shot point and geophone. Some attributes relate to survey design such as reflectivity, incidence angle, observation area, reflection points distribution, fold, minimum well source distance, azimuth angle and so on are studied seriously. In this geometry design of 3D-VSP exploration in deviated wells, the main problems to be solved are: determining the center position of shots distribution, the effect of shots missing on coverage areas and coverage times，locating the shots and receivers of multi-wells. Through simulating and analyzing, the above problems are discussed and some beneficial conclusions are drawn. These will provide valuable references to actual survey design. In data processing, researches emphasize on those relatively key techniques such as wavefield separation, VSP-CDP imaging, the author carried out deep researches around these two aspects. As a result, variant apparent slowness wavefield separation method developed in this article suit the underground variant velocity field and make wavefield separation well, it can overcome reflection bending shortage aroused by conventional imaging method. The attenuateion range of underground seismic wave is very important for amplitude compensation and oil/gas identification.In this paper, seismic wave attenuateion mechanism is studied by 3D-VSP simulateion and Q-inversion technique. By testing with seismic data, the method of VSP data attenuateion and relationship of attenuateion attribute variant with depth is researched. Also the software of survey design and data processing is developed, it fill the gap of VSP area in our country. The technique developed applied successfully in SZXX-A Oilfield、QKYY-B Oilfield、A area and B area. The good results show that this research is valuable, and it is meaningful to the VSP technique development and application of offshore oil industry and other areas in our country.

西峰油田特低渗透油藏渗流机理及开发对策研究

Micro-pore-throat, micro-fracture and low permeability are the most obvious characters of Xifeng ultra-low permeability reservoir, and threshold pressure gradient and medium deformation during the period of oilfield developing results non-linear seepage feature of the formation liquid flowing in the porous medium underground. It is impossible to solve some problems in the ultra-low permeability reservoir development by current Darcy filtration theory and development techniques. In the view of the characters of ultra-low permeability and powerful-diagenesis and fracture up-growth, the paper quantitatively characterizes of through-going scope for reservoir parameters together with some materials such as similarity field outcrop, rock core, drilling, well logging and production dynamic, which provides geological base for further development adjustment. Based on the displacement experiment of different kinds of seepage fluid and oil-water two phases, this paper proves the relationship between threshold pressure gradient and formation permeability in experiment and theory, which is power function and its index is about -1. The variation rule and the mechanism of oil-water two phases threshold pressure gradient are studied. At the same time, based on the experiment of medium deformation, the variation rule of formation physical property parameters and the deformation mechanism are researched, and the influential factors on the medium deformation are analyzed systematically. With elastic unsteady filtration theory, nonlinear mathematical models of the steady and unsteady flow of single phase as well as horizontal well flow and oil-water two phases flow are deduced with the influence of nonlinear factors including threshold pressure gradient and media deformation. The influences of nonlinear factors upon well deliverability and reservoir pressure distribution as well as the saturation variation pattern of oil-water front are analyzed. By means of the researches such as reasonable well pattern, reasonable well array ration, artificial fracture length optimization advisable water flood timing and feasibility of advanced water flooding, it is necessary to find out effective techniques in order to improve development result of this kind of reservoir. This research result develops and improves on low-velocity nonlinear seepage theory, and offers ways to study similar kind of reservoir; it is meaningful to the development of the ultra-low permeability oil and gas reservoir.

孤东油田馆陶组河流相储层流动单元模型与剩余油分布规律研究

Since C.L. Hearn presented the concept of flow unit in 1984, its generation mechanisms and controlling factors have been studied in many aspects using different methods by researchers. There are some basic methods to do the research, and there are several concepts and classification standards about flow unit. Based on previous achievements and using methodologies from sedimentary geology, geophysics, seismic stratigraphy, and reservoir engineering, the author systemically studies the factors controlling flow unit, puts forward a series of methods for recognition, classification and evaluation of flow unit. The results obtained in this paper have important significance not only for understanding the flow unit, but also for revealing the distribution of remaining oil. As a case, this paper deals with the reservoir rocks in Guantao Group of Gudong Oilfield. Zhanhua Sag, Jiyang Depression in Bohaiwan Basin. Based on the study of stratigraphic, depositional and structural characteristics, the author establishes reservoir geological models, reveals the geological characteristics of oil-bearing reservoir of fluvial facies, points out the factors controlling flow unit and geological parameters for classification of flow unit. and summarizes methods and technologies for flow unit study when geological, well-logging and mathematical methods are used. It is the first attempt in literatures to evaluate reservoir by well-logging data constrained by geological conditions, then a well-logging evaluation model can be built. This kind of model is more precise than ever for calculating physical parameters in flow unit. In a well bore, there are six methods to recognize a flow unit. Among them, the activity function and intra-layer difference methods are the most effective. Along a section, the composition type of flow unit can be located according amplitude and impedance on seismic section. Slice method and other methods are used to distinguish flow unit. In order to reveal the distribution laws of flow unit in space, the author create a new method, named combination and composition of flow unit. Based on microscopic pore structure research, the classification methods of flow unit are developed. There are three types of flow unit in the reservoir of fluvial facies. They have their own lithology, petrophysics and pore structure character. Using judgement method, standard functions are built to determine the class of flow unit of fluvial facies. Combining reservoir engineering methods, the distribution laws of remaining oil in different types, or in different part of a flow unit are studied. It is evident that the remaining oil is controlled by the type of flow unit. The author reveals the relationship between flow unit and remaining oil distribution, builds the flowing models, predicts the variation of reservoir parameters in space, put forward different methods developing remaining oil in different flow unit. Especially, based on the results obtained in this paper, some suggestions for the adjustment of the developing flow units have been applied in Districts No.4 and No.7, and good results have been yielded. So, the results of this paper can guide oil field development. They are useful and significant for developing the remaining oil and enhancing the oil recovery efficiency.

企业效率表现和中国环境政策-以造纸企业为例

Understanding relationship between environmental protection and economic development is crucial to form practical environmental policy. At micro level, implementation of environmental regulations often causes production mills adjustment of technology which might leads to change of productive efficiency and cost, which, in turn, determine effort level of mills and even local government in pollution control. Using a stochastic frontier production model and a set of survey data on 126 paper mills from six provinces of China, we measure the technical efficiency changes and analyze the determinants of efficiency. in particular, we examine impact of environmental policy on paper mills' efficiency, using an indicator of environmental policy-the levy ratio of COD. We also estimate a simultaneous-equation model in which the levy rate and emission are jointly determined. The results indicate that there have been efficiency improvements during 1999-2003, when enforcement of environmental regulations have been tightened. The impacts, nevertheless, are different for different types of mills. We also find the levy ratio, which is influenced by both the local social and economic conditions and the characters of paper mills, such as scale, has strong impact on the abatement of the pollutant-COD. Additionally, paper mills' technical efficiency has positive effect on the reduction of the emission intensity of the pollutant-COD. These results lead a set of implications pertinent to policy improvement.

Relationship between the molybdenum phases and the conversion of n-butane over Mo/HZSM-5

The conversion of n-C4H10 was undertaken on MoO3/HZSM-5 catalyst at 773-973K and the phases of molybdenum species were detected by XRD. The XRD results show that bulk MoO3 on HZSM-5 can be readily reduced by n-C4H10 to MoO2 at 773 K and MoO2 can be gradually carburized to molybdenum carbide above 813 K. The molybdenum carbide formed from the carburization of MoO2 with n-C4H10 below 893 K is alpha-MoC1-x with fcc-structure, while hcp-molybdenum carbide formed above 933 K. During the evolution of MoO3 to MoO2 (>773 K) or the carburization of MoO2 to molybdenum carbide (>813 K), deep oxidation, cracking and coke deposition are serious, in particular at higher reaction temperatures, these lead to the poor selectivity to aromatics. Aromatization of n-C4H10 can proceed catalytically on both Mo2C/HZSM-5 and MoO2/HZSM-5, the distribution of the products for the two catalysts is similar below 813 K, but the, activity for Mo2C/HZSM-5 is much higher than that for MoO2/HZSM-5. (C) 2002 Elsevier Science B.V. All rights reserved.