bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accumulation Mechanisms and Evolution History of the Giant Puguang Gas Field, Sichuan Basin, China
Authors: HAO Fang , GUO Tonglou , DU Chunguo , ZOU Huayao , CAI Xunyu , ZHU Yangming , LI Kngping , WANG Chunwu , ZHANG Yuanchun 
Published: February 2009

Abstract:Solid bitumens were found throughout the carbonate reservoirs in the Puguang gas field, the largest gas field so far found in marine carbonates in China, confirming that the Puguang gas field evolved from a paleo‐oil reservoir. The fluid conduit system at the time of intensive oil accumulation in the field was reconstructed, and petroleum migration pathways were modeled using a 3‐D model and traced by geochemical parameters. The forward modeling and inversion tracing coincided with each other and both indicated that oils accumulated in the Puguang‐Dongyuezhai structure originated from a generative kitchen to the northwest of the Puguang gas field. The deposition of organic‐rich Upper Permian source rocks dominated by sapropelic organic matter in the Northeast Sichuan Basin, the development of fluid conduit system that was vertically near‐source rock and laterally near‐generative kitchen, and the focusing of oils originated from a large area of the generative kitchen, were the three requirements for the formation of the giant paleo‐oil reservoir from which the giant Puguang gas field evolved. The Puguang gas field had experienced a three‐stage evolution. The post‐accumulation processes, especially the organic‐inorganic interaction in the hydrocarbon‐water‐rock system, had not only profoundly altered the composition and characteristics of the petroleum fluids, but also obviously changed the physicochemical conditions in the reservoir and resulted in complicated precipitation and solution of carbonate minerals.
Origin and Accumulation of Natural Gases in the Upper Paleozoic Strata of the Ordos Basin in Central China
Authors: ZHU Yangming , WANG Jibao , LIU Xinse , ZHANG Wenzheng 
Published: February 2009

Abstract:The natural gases in the Upper Paleozoic strata of the Ordos basin are characterized by relatively heavy C isotope of gaseous alkanes with δ13C1 and δ13C2 values ranging mainly from –35‰ to –30‰ and –27‰ to –22‰, respectively, high δ13C excursions (round 10) between ethane and methane and predominant methane in hydrocarbon gases with most C1/(C1‐C5) ratios in excess of 0.95, suggesting an origin of coal‐derived gas. The gases exhibit different carbon isotopic profiles for C1‐C4 alkanes with those of the natural gases found in the Lower Paleozoic of this basin, and believed to be originated from Carboniferous‐Permian coal measures. The occurrence of regionally pervasive gas accumulation is distinct in the gently southward‐dipping Shanbei slope of the central basin. It is noted that molecular and isotopic composition changes of the gases in various gas reservoirs are associated with the thermal maturities of gas source rocks. The abundances and δ13C values of methane generally decline northwards and from the basin center to its margins, and the effects of hydrocarbon migration on compositional modification seem insignificant. However, C isotopes of autogenetic calcites in the vertical and lateral section of reservoirs show a regular variation, and are as a whole depleted upwards and towards basin margins. Combination with gas maturity gradient, the analysis could be considered to be a useful tool for gas migration.
Differential Tectonic Deformation of the Longmen Mountain Thrust Belt, Western Sichuan Basin, China
Authors: TANG Liangjie , YANG Keming , JIN Wenzheng , WAN Guimei , LÜ Zhizhou , YU Yixin 
Published: February 2009

Abstract:Field investigation and seismic section explanation showed that the Longmen Mountain Thrust Belt has obvious differential deformation: zonation, segmentation and stratification. Zonation means that, from NW to NE, the Longmen Mountain Thrust Belt can be divided into the Songpan‐Garzê Tectonic Belt, ductile deformation belt, base involved thrust belt, frontal fold‐thrust belt, and foreland depression. Segmentation means that it can be divided into five segments from north to south: the northern segment, the Anxian Transfer Zone, the center segment, the Guanxian Transfer Zone and the southern segment. Stratification means that the detachment layers partition the structural styles in profile. The detachment layers in the Longmen Mountain Thrust Belt can be classified into three categories: the deep‐level detachment layers, including the crust‐mantle system detachment layer, intracrustal detachment layer, and Presinian system basal detachment layer; the middle‐level detachment layers, including Cambrian‐Ordovician detachment layer, Silurian detachment layer, etc.; and shallow‐level detachment layers, including Upper Triassic Xujiahe Formation detachment layer and the Jurassic detachment layers. The multi‐level detachment layers have a very important effect on the shaping and evolution of Longmen Mountain Thrust Belt.
Tectonic Framework and Deep Structure of South China and Their Constraint to Oil‐Gas Field Distribution
Authors: WANG Qingchen , LIU Jinsong , DU Zhili , CAI Liguo 
Published: February 2009

Abstract:South China could be divided into one stable craton, the Yangtze Craton (YzC), and several orogenic belts in the surrounding region, that is the Triassic Qinling‐Dabie Orogenic Belt (QDOB) in the north, the Songpan‐Garzê Orogenic Belt (SGOB) in the northwest, the Mesozoic‐Cenozoic Three‐river Orogenic Belt (TOB) in the west, the Youjiang Orogenic Belt (YOB) in the southwest, the Middle Paleozoic Huanan Orogenic Belt (HOB) in the southeast, and the Mesozoic‐Cenozoic Maritime Orogenic Belt (MOB) along the coast. Seismic tomographic images reveal that the Moho depth is deeper than 40 km and the lithosphere is about 210 km thick beneath the YzC. The SGOB is characterized by thick crust (>40 km) and thin lithosphere (<150 km). The HOB, YOB and MOB have a thin crust (<40 km) and thin lithosphere (<150 km). Terrestrial heat flow survey revealed a distribution pattern with a low heat flow region in the eastern YzC and western HOB and two high heat flow regions in the TOB and MOB respectively. Such a “high‐low‐high” heat flow distribution pattern could have resulted from Cenozoic asthenosphere upwelling. All oil‐gas fields are concentrated in the central part of the YzC. Remnant oil pools have been discovered along the southern margin of the YzC and its adjacent orogenic belts. From a viewpoint of geological and geophysical structure, regions in South China with thick lithosphere and low heat flow value, as well as weak deformation, might be the ideal region for further petroleum exploration.
Large‐scale Tazhong Ordovician Reef‐flat Oil‐Gas Field in the Tarim Basin of China
Authors: ZHOU Xinyuan , WANG Zhaoming , YANG Haijun , ZHANG Lijuan , HAN Jianfa , WANG Zhenyu 
Published: February 2009

Abstract:The Tazhong reef‐flat oil‐gas field is the first large‐scale Ordovician organic reef type oil‐gas field found in China. Its organic reefs were developed in the early Late Ordovician Lianglitag Formation, and are the first large reefs of the coral‐stromatoporoid hermatypic community found in China. The organic reefs and platform‐margin grain banks constitute a reef‐flat complex, mainly consisting of biolithites and grainstones. The biolithites can be classified into the framestone, bafflestone, bindstone etc. The main body of the complex lies around the wells from Tazhong‐24 to Tazhong‐82, trending northwest, with the thickness from 100 to 300 m, length about 220 km and width 5–10 km. It is a reef‐flat lithologic hydrocarbon reservoir, with a very complex hydrocarbon distribution: being a gas condensate reservoir as a whole with local oil reservoirs. The hydrocarbon distribution is controlled by the reef complex, generally located in the upper 100–200 m part of the complex, and largely in a banded shape along the complex. On the profile, the reservoir shows a stratified feature, with an altitude difference of almost 2200 m from southeast to northwest. The petroleum accumulation is controlled by karst reservoir beds and the northeast strike‐slip fault belt. The total geologic reserves had reached 297.667 Mt by 2007.
Enzymatic deconstruction of xylan for biofuel production
Authors: DODD DYLAN , CANN ISAAC K. O. 
Published: February 2009

AbstractThe combustion of fossil‐derived fuels has a significant impact on atmospheric carbon dioxide (CO2) levels and correspondingly is an important contributor to anthropogenic global climate change. Plants have evolved photosynthetic mechanisms in which solar energy is used to fix CO2 into carbohydrates. Thus, combustion of biofuels, derived from plant biomass, can be considered a potentially carbon neutral process. One of the major limitations for efficient conversion of plant biomass to biofuels is the recalcitrant nature of the plant cell wall, which is composed mostly of lignocellulosic materials (lignin, cellulose, and hemicellulose). The heteropolymer xylan represents the most abundant hemicellulosic polysaccharide and is composed primarily of xylose, arabinose, and glucuronic acid. Microbes have evolved a plethora of enzymatic strategies for hydrolyzing xylan into its constituent sugars for subsequent fermentation to biofuels. Therefore, microorganisms are considered an important source of biocatalysts in the emerging biofuel industry. To produce an optimized enzymatic cocktail for xylan deconstruction, it will be valuable to gain insight at the molecular level of the chemical linkages and the mechanisms by which these enzymes recognize their substrates and catalyze their reactions. Recent advances in genomics, proteomics, and structural biology have revolutionized our understanding of the microbial xylanolytic enzymes. This review focuses on current understanding of the molecular basis for substrate specificity and catalysis by enzymes involved in xylan deconstruction.
Multiple, large sialoliths of the submandibular gland duct: a case report
Authors: Huang TC , Dalton JB , Monsour FN , Savage NW 
Published: February 2009

AbstractThis paper reviews the major clinical and radiographic features of sialoliths and illustrates these with an unusual case of multiple sialoliths within the submandibular gland duct. The differential diagnosis of other calcific structures both within and outside the salivary gland that may mimic a sialolith is also presented.
τ-function of discrete isomonodromy transformations and probability
Authors: Arinkin D. , Borodin A. 
Published: February 2009

AbstractWe introduce theτ-function of a difference rational connection (d-connection) and its isomonodromy transformations. We show that in a continuous limit ourτ-function agrees with the Jimbo–Miwa–Uenoτ-function. We compute theτ-function for the isomonodromy transformations leading to difference Painlevé V and difference Painlevé VI equations. We prove that the gap probability for a wide class of discrete random matrix type models can be viewed as theτ-function for an associated d-connection.
GRA2 and ROP1 Recombinant Antigens as Potential Markers for Detection of
Toxoplasma gondii
-Specific Immunoglobulin G in Humans with Acute Toxoplasmosis
Authors: Holec-Gąsior Lucyna , Kur Józef , Hiszczyńska-Sawicka Elżbieta 
Published: February 2009

ABSTRACT

A goal of the current study was to evaluate serological applications of
Toxoplasma gondii
GRA2 and rhoptry protein 1 (ROP1) antigens. Soluble recombinant GRA2 and ROP1 antigens as fusion proteins containing six histidyl residues at the N and C terminals were obtained using an
Escherichia coli
expression system. Purification by one-step metal affinity chromatography allowed recovery of milligram amounts of pure recombinant proteins per liter of culture. The usefulness of these antigens for diagnosis of human infections was tested on 167 serum samples obtained during routine diagnostic tests. A panel of 37 serum samples from patients with acute toxoplasmosis was compared to a panel of 90 serum samples from individuals with past infection. The results indicated that both GRA2 and ROP1 recombinant antigens detected antibodies more frequently in samples from individuals with acute infections (100% and 94.6%, respectively) than in samples from individuals with chronic infections (22.5% and 15.5%, respectively). These results suggest that immunoglobulin G antibodies against GRA2 and ROP1 antigens are produced during the acute stage of toxoplasmosis but are uncommon in the chronic phase of the infection. Hence, these recombinant proteins can be used as specific molecular markers to differentiate between acute and chronic infections.
Development of a Bovine Ileal Cannulation Model To Study the Immune Response and Mechanisms of Pathogenesis of Paratuberculosis
Authors: Allen Andrew J. , Park Kun Taek , Barrington George M. , Lahmers Kevin K. , Hamilton Mary Jo , Davis William C. 
Published: February 2009

ABSTRACTAn ileal cannulation model was developed in conjunction with a flow cytometric assay to gain a better understanding of the mechanisms of immunopathogenesis of Johne's disease caused byMycobacterium aviumsubsp.paratuberculosis. Initial studies with calves showed thatM. aviumsubsp.paratuberculosisDNA is detectable by PCR in ileal biopsies during the first months following experimental infection. Inflammatory lesions were not detected on endoscopic evaluation up to 8 months postexperimental infection.M. aviumsubsp.paratuberculosisDNA was detected in multiple tissues at necropsy 8 months postinfection. Examination of the activation status of epithelial lymphocytes from the jejunum and ileum from infected and control animals at necropsy revealed that none of the major subsets of lymphocytes (NK, CD2+, and CD2−γδ T lymphocytes, or CD4 and CD8 αβ T lymphocytes) expressed activation molecules CD25, CD26, CD71, ACT1, or ACT16. Subsets of CD4 and CD8 T lymphocytes from control and infected animals expressed CD26. The majority of CD4 and CD8 T lymphocytes expressed CD45R0, the memory T-lymphocyte marker. An immune response toM. aviumsubsp.paratuberculosiswas detected by 3 months postinfection, dominated by a strong proliferative response of CD4 memory T lymphocytes. The findings indicate an immune response develops following initial exposure toM. aviumsubsp.paratuberculosisthat controls but does not eliminate the pathogen. This persistence ofM. aviumsubsp.paratuberculosispossibly leads to erosion and dysregulation of protective immunity at later time points postinfection. Continuous access to the ileum offers an opportunity to elucidate the cellular and molecular events leading to immune dysregulation and development of chronic inflammatory ileitis.
Nevirapine Resistance in Human Immunodeficiency Virus Type 1-Positive Infants Determined Using Dried Blood Spots Stored for Up to Six Years at Room Temperature
Authors: Nelson Julie A. E. , Loftis Amy M. , Kamwendo Deborah , Fawzi Wafaie W. , Taha Taha E. , Goldenberg Robert L. , Fiscus Susan A. 
Published: February 2009

ABSTRACT

Dried blood spots that had been stored ambiently for 3 to 6 years lost approximately 1 log
10
of human immunodeficiency virus type 1 (HIV-1) RNA, but the majority could still be genotyped for resistance. Nevirapine resistance was found in 7/16 (43.5%) HIV-1-positive HIVNET 024 infants at 4 to 6 weeks, but no resistance was found at other time points.
Temporal Trends of Invasive
Streptococcus pneumoniae
Serotypes and Antimicrobial Resistance Patterns in Spain from 1979 to 2007
Authors: Fenoll A. , Granizo J. J. , Aguilar L. , Giménez M. J. , Aragoneses-Fenoll L. , Hanquet G. , Casal J. , Tarragó D. 
Published: February 2009

ABSTRACT
Temporal trends of serotypes from invasive pneumococcal disease (IPD) in Spain from 1979 to September 2007 under antibiotic and vaccine pressure were analyzed. A significant trend in pneumococcal conjugate 7-valent vaccine (PCV7) serotypes (except serotype 4) was found, whereby the prevalence increased from the early 1980s and decreased in the 2000s for all but serotype 23F, which began decreasing in the late 1980s. Among the major non-PCV7 serotypes, a significant decrease was observed for serotypes 1, 5, and 7F in the 1980s. From the late 1990s, serotypes 1, 5, 6A, 7F, and 19A increased significantly, while serotypes 3 and 8 showed similar but nonsignificant trends over time. The incidence of IPD cases was 10.7/100,000 for the period 1996 to 2006, with reporting coverage ranging from 18% to 43%. A significant decrease in IPD incidence due to PCV7 serotypes was observed, while the incidence of non-PCV7 serotypes increased, with the consequence that there was no clear pattern in the overall incidence of IPD. Penicillin nonsusceptibility was correlated with the proportion of PCV7 serotypes. Erythromycin nonsusceptibility increased in association with long-half-life macrolide consumption and then decreased in 2004 to 2007. The increase in PCV7 serotypes and antibiotic nonsusceptibility related to antibiotic consumption in the 1980s and 1990s was reversed in the 2000s, probably as a result of PCV7 immunization. The decrease in IPD incidence due to PCV7 serotypes was mirrored by an increase in that of non-PCV7 serotypes. The impact of various preventive/therapeutic strategies on pneumococcal evolution is serotype dependent, and the dynamics remain unpredictable.
Evaluation of a Nested-PCR-Derived Sequence-Based Typing Method Applied Directly to Respiratory Samples from Patients with Legionnaires' Disease
Authors: Ginevra Christophe , Lopez Marie , Forey Françoise , Reyrolle Monique , Meugnier Helene , Vandenesch François , Etienne Jerome , Jarraud Sophie , Molmeret Maëlle 
Published: February 2009

ABSTRACT

Sequence-based typing (SBT) is a powerful method based on the sequencing of seven genes of
Legionella pneumophila
isolates. SBT performed directly on clinical samples has been used only in a limited number of cases. In our study, its efficiency was tested with 63 legionellosis respiratory samples. Sixty-three clinical samples, which included 23 samples from sporadic cases and 40 collected during four French outbreaks, confirmed by culture or urinary antigen testing and all positive by
L. pneumophila
quantitative PCR were subtyped by SBT according to the European Working Group for
Legionella
Infections standard scheme. Only 28.6% of the samples provided nucleotide sequences by SBT. Nested-PCR-based SBT (NPSBT) applied to the same respiratory samples was thus evaluated with new PCR primers surrounding the first set of primers used for the SBT. Sequencing results were obtained with 90.5% of the samples. Complete allelic profiles (seven genes sequenced) were obtained for 3.2% versus 53.9% of the samples by SBT and NPSBT, respectively. More importantly, of the 28 culture-negative samples, only 4 did not give any sequencing results. Taken together, NPSBT applied directly to clinical specimens significantly improved epidemiological typing compared to the initial SBT, in particular when no isolates are available.
The Putative Leucine Zipper of the U
L
6-Encoded Portal Protein of Herpes Simplex Virus 1 Is Necessary for Interaction with pU
L
15 and pU
L
28 and Their Association with Capsids
Authors: Yang Kui , Wills Elizabeth , Baines Joel D. 
Published: February 2009

ABSTRACT

Herpes simplex virus (HSV) type 1 capsids contain a single portal vertex that is composed of 12 copies of the U
L
6 gene product (pU
L
6), which forms a pore through which DNA is inserted during packaging. This unique vertex is also believed to comprise the site with which a molecular motor, termed the terminase, associates during the DNA packaging reaction. In HSV, the terminase likely comprises the U
L
15, U
L
28, and U
L
33 proteins (pU
L
15, pU
L
28, and pU
L
33, respectively). The current study was undertaken to identify portal domains required for interaction with the terminase. Both the amino and carboxyl termini, as well as amino acids 422 to 443 of pU
L
6 forming a putative leucine zipper motif, were critical for coimmunoprecipitation with pU
L
15 in the absence of other viral proteins. Amino acids 422 to 443 were also necessary for interaction with pU
L
28 in the absence of other viral proteins. By using an engineered recombinant virus, it was further determined that although amino acids 422 to 443 were dispensable for interaction with scaffold protein and incorporation of portal protein into capsids, they were necessary for coimmunoprecipitation of pU
L
6 and pU
L
15 from infected cell lysates, association of optimal levels of pU
L
15, pU
L
28, and pU
L
33 with capsids, and DNA cleavage and packaging. These data identify a portal protein domain critical for terminase association with the capsid and suggest that both the pU
L
15- and pU
L
28-bearing terminase subunits mediate docking of the terminase with the portal vertex.
The 3′-to-5′ Exonuclease Activity of Vaccinia Virus DNA Polymerase Is Essential and Plays a Role in Promoting Virus Genetic Recombination
Authors: Gammon Don B. , Evans David H. 
Published: February 2009

ABSTRACT

Poxviruses are subjected to extraordinarily high levels of genetic recombination during infection, although the enzymes catalyzing these reactions have never been identified. However, it is clear that virus-encoded DNA polymerases play some unknown yet critical role in virus recombination. Using a novel, antiviral-drug-based strategy to dissect recombination and replication reactions, we now show that the 3′-to-5′ proofreading exonuclease activity of the viral DNA polymerase plays a key role in promoting recombination reactions. Linear DNA substrates were prepared containing the dCMP analog cidofovir (CDV) incorporated into the 3′ ends of the molecules. The drug blocked the formation of concatemeric recombinant molecules in vitro in a process that was catalyzed by the proofreading activity of vaccinia virus DNA polymerase. Recombinant formation was also blocked when CDV-containing recombination substrates were transfected into cells infected with wild-type vaccinia virus. These inhibitory effects could be overcome if CDV-containing substrates were transfected into cells infected with CDV-resistant (CDV
r
) viruses, but only when resistance was linked to an A314T substitution mutation mapping within the 3′-to-5′ exonuclease domain of the viral polymerase. Viruses encoding a CDV
r
mutation in the polymerase domain still exhibited a CDV-induced recombination deficiency. The A314T substitution also enhanced the enzyme's capacity to excise CDV molecules from the 3′ ends of duplex DNA and to recombine these DNAs in vitro, as judged from experiments using purified mutant DNA polymerase. The 3′-to-5′ exonuclease activity appears to be an essential virus function, and our results suggest that this might be because poxviruses use it to promote genetic exchange.