The effect of slight to minor biodegradation on C_6 to C_7 light hydrocarbons in crude oils: a case study from Dawanqi Oilfield in the Tarim Basin,NW China

Light hydrocarbons （LHs） are one of the main petroleum fractions in crude oils, and carry much infor- mation regarding the genetic origin and alteration of crude oils. But secondary alterations--especially biodegrada- tion--have a significant effect on the composition of LHs in crude oils. Because most of the LHs affected in oils underwent only slight biodegradation （rank 1 on the biodegradation scale）, the variation of LHs can be used to describe more the refined features of biodegradation. Here, 23 crude oils from the Dawanqi Oilfield in the Tarim Basin, NW China, eleven of which have been biodegraded to different extents, were analyzed in order to investigate the effect of slight to minor biodegradation on C6--C7 LHs. The study results showed that biodegradation resulted in the prior depletion of straight-chained alkanes, followed by branched alkanes. In slight and minor biodegraded oils, such biodegradation scale could not sufficiently affect C6- C7 cycloalkanes. For branched C6--C7 alkanes, generally, monomethylalkanes are biodegraded earlier than dimethylalkanes and trimethylalkanes, which indicates that branched alkanes are more resistant to biodegradation, with the increase of substituted methyl groups on parent rings. The degree of alkylation is one of the primary controlling factors on the biodegradation of C6-Cv LHs. There is a particular case： although 2,2,3-trimethylbutane has a rela- tive higher alkylation degree, 2,2-dimethylpentane is more resistant to biodegradation than 2,2,3-trimethylbutane. 2,2- Dimethylpentane is the most resistant to biodegradation in branched C6-C7 alkanes. Furthermore, the 2-methylpen- tane/3-methylpentane and 2-methylhexane/3-methylhexane ratios decreased steadily with increasing biodegradation, which implies that isomers of bilateral methyl groups are more prone to bacterial attack relative to mid-chain iso- mers. The position of the alkyls on the carbon skeleton is also one of the critical factors controlling the rate of biodegradation. With increasing biodegradation, Mango＇s LH parameters K1 values decrease and K2 values increase, the values of n-heptane and isoheptane decrease, and the indices of methylcyclohexane and cyclohexane increase. LH parameters should be applied cautiously for the biodegraded oils. Because biodegraded samples belong to slight or minor biodegraded oils, the values of n-heptane and isoheptane from Dawanqi Oilfield can better reflect and determine the ＂Biodegraded＂ zone. When the heptane value is 0-21 and the isoheptane value is 0-2.6, the crude oil in Dawanqi Oilfield is defined as the ＂Biodegraded＂ zone

In situ spectroscopic insights into the redox and acid-base properties of ceria catalysts

Cerium oxide(ceria)plays an important and fascinating role in heterogeneous catalysis as illustrated by its versatile use as a catalyst,a catalyst support,or a promotor in various oxidation and reduction reactions.Central to these reactions is the rich defect chemistry,facile redox capability,and unusual acid-base properties of ceria.Understanding the unique redox and acid-base properties of ceria is essential to build the structure-catalysis relationship so that improved catalytic functions can be achieved for ceria-based materials.Among the characterization toolbox,spectroscopic approach indisputably stands out for its unparalleled power in offering chemical insights into the surface properties of ceria at atomic and molecular level.In this review,we summarize advances in revealing the redox and acid-base properties of ceria via a variety of spectroscopic methods including optical,X-ray,neutron,electronic and nuclear spectroscopy.Both direct spectroscopy characterization and its coupling with probe molecules are analyzed to illustrate how the nature,strength and density of different surface sites are influenced by the pretreatment,the morphology and size of ceria nanoparticles.Further directions in taking advantage of in situ/operando spectroscopy for better understanding the catalysis of ceria-based materials are proposed in the summary and outlook section.

Paleo-oil reservoir pyrolysis and gas release in the Yangtze Block imply an alternative mechanism for the Late Permian Crisis

The causes of the global mass extinction that occurred around the Permian-Triassic boundary have been widely studied through the geological record and in various locations.The results show that volcanic activity was a key factor in initiating the crisis during the Late Permian.Compared to other thermal events triggered by volcanic activity,pyrolysis of petroleum in Pre-Permian reservoirs has rarely been suggested as a significant source of the greenhouse gases that caused the mass extinction.In this study,geochemical analysis is carried out of a huge paleo-oil reservoir in the Yangtze Block(YB),South China.The detection of mineral inclusions and pyrobitumens is evidence of rapid pyrolysis of accumulated oil in the Ediacaran reservoir.New evidence from hydrothermal minerals and the presence of domain mesophase in the pyrobitumen suggest that the pyrolysis process occurred abruptly and that greenhouse gases were rapidly released through venting pipes.The dating of such a complex geological event in this old and deeply buried reservoir is inevitably difficult and potentially unreliable.However,cross-validation of the multiple evidence sources,including hydrothermal minerals and domain mesophase,indicates that the rapid oil pyrolysis must have been driven by a major thermal event.Reconstruction of burial and thermal histories suggests that the thermal event was most likely to have been triggered by the Emeishan Large Igneous Province(ELIP),which was in a period of significant volcanic activity during the Late Permian.Massive volumes of gases,including methane,carbon dioxide,and possibly hydrogen sulfide,were released,causing a significant increase in greenhouse gases that may have contributed to global warming and the resulting mass extinction during the Late Permian Crisis(LPC).

Analysis of Action Mechanism of Fuxin Decoction on Heart Failure Based on Network Pharmacology

[Objectives]The purpose was to analyze and predict the mechanism of Fuxin decoction in the treatment of heart failure based on network pharmacology.[Methods]Relevant tools and methods of network pharmacology were used to obtain the active ingredients and action targets of Fuxin decoction and action targets of heart failure,find out the key targets and core clusters of Fuxin decoction on heart failure,and analyze related signal pathways,to explore possible molecular mechanisms.[Results]A total of 53 active ingredients and 224 action targets of Fuxin decoction,1010 heart failure-related target genes,and 94 drug-disease directly acting targets were obtained.From the PPI network constructed,225 key targets and a core cluster composed of 56 nodes and 297 interactions were screened out.Association with tumors,glutamate synapse and other related pathways and related genes such as adenylate cyclase and MAPK were known.[Conclusions]The mechanism of Fuxin decoction in the treatment of heart failure is related toβARs-G protein-adenylate cyclase,PI3K-Akt signaling pathway and HSP90,MAPK and other proteins.

中国野生杜鹃花属植物名录与地理分布数据集

杜鹃花属(Rhododendron)植物分布广泛,生存环境多样,类群结构复杂,深入分析其地理分布格局与特征,可为种质资源保育和利用等提供依据。本文基于大量基础数据及文献资料,更新了中国陆域分布的野生杜鹃花属植物物种名录,统计了其物种多样性、组成成分等信息,建立了中国野生杜鹃花属植物地理分布数据库,旨在为种质资源调查及引种应用研究提供参考。截至2021年7月,共记载7亚属720种(包括114变种、45亚种和2变型),其中中国特有种450种。除宁夏和新疆干旱荒漠地带外,中国其他各省区均有野生杜鹃花属分布,其中云南省分布393种,是省级尺度物种丰富度及特有性最高的区域;其次为四川省(278种)及西藏自治区(271种)。县级尺度贡山独龙族怒族自治县与察隅县以134种并列物种丰富度第一,其次是德钦县128种。

中国野生凤仙花属物种多样性和地理分布数据集

凤仙花属(Impatiens)植物主要分布于旧世界的热带和亚热带山区,对生长环境要求极度严苛,深入分析其地理分布格局与特征,可为种质资源调查和利用提供理论依据。本研究通过系统检索文献资料,更新了该属植物物种名录,整合其地理分布、海拔、特有性等信息,建立了中国野生凤仙花属植物地理分布数据库。截至2022年3月,中国共记载野生凤仙花属植物352种(包含18变种1亚种1变型),其中中国特有种273种。除上海市外,中国其他各省级行政区均有野生凤仙花属植物分布,其中云南省分布有165种,其次为四川省(119种)和西藏自治区(69种)。县级尺度上,贡山独龙族怒族自治县和腾冲市以51种并列物种丰富度第一,其次是福贡县(42种)。中国野生凤仙花属的分布总体呈现以热带、亚热带为中心向高纬度和高海拔区域扩散的格局,广义横断山区、西藏南部地区、滇黔桂喀斯特区域、长江中下游等地为凤仙花属植物集中分布的热点地区。