emperature and oil,and has a stable dis

ld,so we present the well logging series and gas drilling technique suited to Daqing area.Some proper logging evaluation approaches are used such as GR spectrometry log,CN log,induction log and NMR log,etc.well logging;technology;gas drilling;foam drilling;casing drilling;Daqing oilfield0测井技术Well Logging Technology20-22 104P631.8B019;B021;A011;A012;C;21;D3;A;B;B019_21;A011_D3;A012_C;B021_21;赵平;16-18 100高孔密复合射孔技术研究周志华;谭忠健;刘富奎;西安通源石油科技股份有限公司,中海石油(中国)有限公司天津分公司勘探部,中海石油(中国)有限公司天津分公司勘探部 陕西西安710065,天津300452,天津300452复合射孔;;高孔密;;p-t过程测试;;现场应用提出了一种新型装药结构并实现在高孔密条件下的复合射孔,所开发的产品进行了地面混凝土靶测试、地面动态压力-时间(p-t)过程测试和现场应用试验。试验结果表明,高孔密复合射孔器能够将高孔密的多孔道、多相位的射孔特点与高能气体压裂造缝机理有机地结合,形成了孔缝结合的深穿透、高孔密和多相位的沟通通道,有效地改善了近井带的渗流能力,实现了油井的高产和稳产。现场应用效果良好。On High Foramen Density Technology for the Fracture Perfo     

New intermediate host records for the avian schistosomes Dendritobilharzia pulverulenta, Gigantobilharzia huronensis, and Trichobilharzia querquedulae from North America

Here we provide the first North American report of a naturally infected snail, Gyraulus parvus, harboring the larval stages of the cosmopolitan, arterial schistosome, Dendritobilharzia pulverulenta. The relatively small cercariae of this species are shed in the early morning, are sticky, and adhere to the water's surface film. We also provide a report of the snail host, Physa gyrina, of the widespread North American passerine schistosome, Gigantobilharzia huronensis. Finally, we provide unambiguous documentation that Physa gyrina is a natural snail host for Trichobilharzia querquedulae, a schistosome primarily of dabbling ducks.     

Assembly and patterning of the vascular network of the vertebrate hindbrain

The cranial vasculature is essential for the survival and development of the central nervous system and is important in stroke and other brain pathologies. Cranial vessels form in a reproducible and evolutionarily conserved manner, but the process by which these vessels assemble and acquire their stereotypic patterning remains unclear. Here, we examine the stepwise assembly and patterning of the vascular network of the zebrafish hindbrain. The major artery supplying the hindbrain, the basilar artery, runs along the ventral keel of the hindbrain in all vertebrates. We show that this artery forms by a novel process of medial sprouting and migration of endothelial cells from a bilateral pair of primitive veins, the primordial hindbrain channels. Subsequently, a second wave of dorsal sprouting from the primordial hindbrain channels gives rise to angiogenic central arteries that penetrate into and innervate the hindbrain. The chemokine receptor cxcr4a is expressed in migrating endothelial cells of the primordial hindbrain channels, whereas its ligand cxcl12b is expressed in the hindbrain neural keel immediately adjacent to the assembling basilar artery. Knockdown of either cxcl12b or cxcr4a results in defects in basilar artery formation, showing that the assembly and patterning of this crucial artery depends on chemokine signaling.     

Multimodal Imaging and Soft X-Ray Tomography of Fluorescent Nanodiamonds in Cancer Cells

Multimodal imaging promises to revolutionize the understanding of biological processes across scales in space and time by combining the strengths of multiple imaging techniques. Fluorescent nanodiamonds (FNDs) are biocompatible, chemically inert, provide high contrast in light- and electron-based microscopy, and are versatile optical quantum sensors. Here it is demonstrated that FNDs also provide high absorption contrast in nanoscale 3D soft X-ray tomograms with a resolution of 28 nm in all dimensions. Confocal fluorescence, atomic force, and scanning electron microscopy images of FNDs inside and on the surface of PC3 cancer cells with sub-micrometer precision are correlated. FNDs are found inside ≈1 µm sized vesicles present in the cytoplasm, providing direct evidence of the active uptake of bare FNDs by cancer cells. Imaging artefacts are quantified and separated from changes in cell morphology caused by sample preparation. These results demonstrate the utility of FNDs in multimodal imaging, contribute to the understanding of the fate of FNDs in cells, and open up new possibilities for biological imaging and sensing across the nano- and microscale.     

Primer-template interactions during DNA amplification fingerprinting with single arbitrary oligonucleotides

Summary DNA amplification fingerprinting (DAF) is the enzymatic amplification of arbitrary stretches of DNA which is directed by very short oligonucleotide primers of arbitrary sequence to generate complex but characteristic DNA fingerprints. To determine the contribution of primer sequence and length to the fingerprint pattern and the effect of primer-template mismatches, DNA was amplified from several sources using sequence-related primers. Primers of varying length, constructed by removing nucleotides from the 5 terminus, produced unique patterns only when primers were 8 nucleotides or fewer in length. Larger primers produced either identical or related fingerprints, depending on the sequence. Single base changes within this first 8-nucleotide region of the primer significantly altered the spectrum of amplification products, especially at the 3 terminus. Increasing annealing temperatures from 15° to 70° C during amplification did not shift the boundary of the 8-nucleotide region, but reduced the amplification ability of shorter primers. Our observations define a 3-terminal oligonucleotide domain that is at least 8 bases in length and largely conditions amplification, but that is modulated by sequences beyond it. Our results indicate that only a fraction of template annealing sites are efficiently amplified during DAF. A model is proposed in which a single primer preferentially amplifies certain products due to competition for annealing sites between primer and terminal hairpin loop structures of the template.     

Shifty salamanders: transient trophic polymorphism and cannibalism within natural populations of larval ambystomatid salamanders

Introduction

Many species of ambystomatid salamanders are dependent upon highly variable temporary wetlands for larval development. High larval densities may prompt the expression of a distinct head morphology that may facilitate cannibalism. However, few studies have characterized structural cannibalism within natural populations of larval salamanders. In this study we used two species of larval salamanders, long-toed (Ambystoma macrodactylum) and ringed salamanders (A. annulatum). Head morphometrics and stable isotopic values of carbon (δ¹³C) and nitrogen (δ¹⁵N) were used to identify the presence or absence of structural cannibalism. Weather conditions were also analyzed as a potential factor associated with the expression of cannibalistic morphology.

Results

Populations of salamander larvae did not consistently exhibit cannibalistic morphologies throughout collection periods. Larval long-toed salamanders exhibited trophic polymorphisms when relatively lower precipitation amounts were observed. Larval ringed salamanders were observed to be cannibalistic but did not exhibit polymorphisms in this study.

Conclusions

Structural cannibalism may be transient in both species; however in long-toed salamanders this morphology is necessary for cannibalism. Ringed salamanders can be cannibalistic without morphological adaptations; however the cannibal morph may prolong the viable time period for cannibalism. Additionally, weather conditions may alter pond hydroperiod, subsequently influencing head morphology and cannibalism.

     

Multiplex quantification of lamprey specific bile acid derivatives in environmental water using UHPLC-MS/MS

Larval and adult sea lampreys (Petromyzon marinus) release bile salts and acids into the surrounding aquatic environment. Some of these bile salts and acids, such as petromyzonol sulfate (PZS), 3-keto petromyzonol sulfate (3k PZS), petromyzonamine disulfate (PADS), petromyzosterol disulfate (PSDS), and 3-keto allocholic acid (3k ACA), may function as pheromones. To examine the release and distribution patterns of these metabolites, which this study has termed bile acid derivatives, we developed a novel UHPLC-MS/MS method that was characterized by simple sample preparation, baseline separation, and short analysis time for all studied compounds. These five analytes were separated in 7 min using a reversed-phase C18 column containing 1.7 μm particles and a gradient elution at pH 8.9. Once separated, the analytes were subjected to electrospray ionization-mass spectrometry (negative ion mode) and collision-induced dissociation tandem mass spectrometry (CID-MS/MS) using the multiple reaction monitoring (MRM) mode. Deuterated 3k PZS ([(2)H(5)]3k PZS) was added as the internal standard (IS) to the sample prior to solid phase extraction (SPE). Among the three types of SPE sorbent tested, mixed-mode cation-exchange and reversed-phase sorbent for bases (MAX) and acids (MCX), and reversed-phase C18 sorbent (Sep-pak), the best recoveries (84.1-99.7%) were obtained with MCX cartridges. The calibration curves of all five analytes were linear between 0.15 and 1200 ng/mL, with R(2)≥0.9997. This method had a precision of relative standard deviation (RSD) ≤9.9% and an accuracy of deviation (DEV) ≥92.5%. The developed method was successfully used to quantify bile acid derivatives found in streams where lampreys spawn (SD<1.4) and water conditioned with male sea lampreys (SD<4.8). Utilizing this method provides a routine analysis of lamprey bile acid derivatives and may prove useful for sea lamprey population estimates in future studies and applications.