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Chemical Evolution of LiCoO2 and NaHSO4·H2O Mixtures with Different Mixing Ratios During Roasting Process 被引量:4
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作者 WANG Dahui WEN Hao +2 位作者 CHEN Huaijing YANG Yujiao LIANG Hongyan 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2016年第4期674-677,共4页
Mixtures of NaHSO4·H2O and LiCoO2 extracted from spent lithium-ion batteries were prepared with molar ratios of 1:1, 1:2 and 1:3. The chemical evolution of the LiCoO2 and NaHSO4-H20 mixtures during the roastin... Mixtures of NaHSO4·H2O and LiCoO2 extracted from spent lithium-ion batteries were prepared with molar ratios of 1:1, 1:2 and 1:3. The chemical evolution of the LiCoO2 and NaHSO4-H20 mixtures during the roasting process was investigated by means of thermogravimetric analysis and differential scanning calorimetry (TG-DSC), X-ray diffraction(XRD), scanning electron (XPS). The results show that the chemical reactions in microscopy(SEM), and X-ray photoelectron spectroscopy the LiCoO2 and NaHSO4·H2O mixtures proceed during the roasting process. The Li element in the product of the roasting process is in the form of LiNa(SO4). With the increase of the proportion of NaHSO4·H2O in the mixtures, the Co element evolves as follows: LiCoO2→Co3O4→Na6Co(SOa)4→Na2Co(SO4)2. The roasting products exhibit dense structures and irregular shapes, and the bonding energy of Co increases. 展开更多
关键词 Spent lithium-ion battery LiCo02 Sulfating roasting chemical evolution
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N-phosphoryl amino acid models for P–N bonds in prebiotic chemical evolution 被引量:4
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作者 Feng Ni Chuan Fu +9 位作者 Xiang Gao Yan Liu Pengxiang Xu Liu Liu Ye Lv Songsen Fu Ying Sun Daxiong Han Yan-Mei Li Yufen Zhao 《Science China Chemistry》 SCIE EI CAS CSCD 2015年第3期374-382,共9页
Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P–N bond might have contributed to the evolution of pre... Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P–N bond might have contributed to the evolution of prebiotic chemistry. N-phosphoryl amino acids(PAAs) can serve as interesting small molecular models for the study of P–N bonds in prebiotic chemical evolution. PAAs are capable of simultaneously producing several important biomolecules such as polypeptides and oligonucleotides under mild reaction conditions. In this review, we describe the chemistry of PAAs, discusse their likely prebiotic origins and their reactivity and how they relate to biological P–N bond species. We also depict a possible prebiotic scenario mediated by PAAs in which PAAs may have acted as one of the essential forces driving prebiotic biomolecules to the first protocell. 展开更多
关键词 N-phosphoryl amino acid biological P–N bond chemical evolution origin of life
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Phases of Environmental Evolution Indicated by Primary Chemical Elements and Paleontological Records in the Upper Pleistocene-Holocene Series for the Salawusu River Valley,China 被引量:17
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作者 LI Baosheng WEN Xiaohao +5 位作者 QIU Shifan David Dian ZHANG DU Shuhuan CHEN Deniu OU Xianjiao NIU Dongfeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2007年第4期555-565,共11页
Studies of lithology, sedimentary facies and the distribution regularity of SiO2 and Al2O3 contents and Al2O3/SiO2 ratio allow us to divide the Upper Pleistocene-Holocene Series represented by the MUanggouwan section ... Studies of lithology, sedimentary facies and the distribution regularity of SiO2 and Al2O3 contents and Al2O3/SiO2 ratio allow us to divide the Upper Pleistocene-Holocene Series represented by the MUanggouwan section in China's Salawnsu River valley into six segments: MGS1, MGS2, MGS3, MGS4, MGS5 and MGS6. The boundary ages for MGS1 (the Dishaogouwan and Dagouwan Formations), MGS2 (the upper Chengchuan Formation), MGS3 (the middle Chengchuan Formation), MGS4 (the lower Chengchuan Formation), MGS5 (most strata of the Salawusu Formation) and MGS6 (the bottom of the Salawusu Formation and the top of the Lishi Formation) correspond to those of MIS1, MIS2, MIS3, MIS4, MISS and MIS6, respectively, from deep sea sediments or continental glaciers. MGS5 can be subdivided into five subsegments (MGS5a, MGS5b, MGS5c, MGS5d and MGS5e) and the boundary ages of these subsegments correspond to those of MISSa, MISSb, MIS5c, MIS5d and MIS5e, respectively. Based on the paleoenvironment and paleoecology indicated by the primary chemical elements, fossil vertebrates, mollusks and pollen grains, we hypothesize that MGS1, MGS2, MGS3, MGS4, MGS5 and MGS6 and the subsegments of MGS5 match the corresponding stages for oxygen isotopes in the deep sea sediments and continental glaciers, and the substages of MIS5 in terms of climatic characters, further explaining the phenomena that determined the formation of the late Quaternary strata and the paleontology of the Salawusu River valley. These phenomena relate to fluctuations in the global climate (and particularly in the East Asian monsoon) during the glacial and interglacial periods. 展开更多
关键词 Salawusu River valley Upper Pleistocene-Holocene Series primary chemical elements phases of evolution paleontological records
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A plausible pathway to prebiotic peptides via amino acid amides on the primordial Earth
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作者 DingWei Gan XiangMin Lei +6 位作者 RenWu Zhou SongSen Fu Jing Sun RuSen Zhou Kostya(Ken)Ostrikov YuFen Zhao JianXi Ying 《Earth and Planetary Physics》 EI CAS CSCD 2024年第6期868-877,共10页
The prebiotic synthesis of peptides prior to ribosome-catalyzed processes remains an enigma.The synthesis of abiotic peptides from amino acids(AAs)is primarily constrained by high activation energies and unfavorable t... The prebiotic synthesis of peptides prior to ribosome-catalyzed processes remains an enigma.The synthesis of abiotic peptides from amino acids(AAs)is primarily constrained by high activation energies and unfavorable thermodynamics,necessitating the identification of plausible prebiotic alternatives for synthesizing prebiotic peptides.Here we present a plausible pathway to the formation of prebiotic peptides,wherein oligopeptides,oligopeptide amides,and cyclic oligopeptides can be directly synthesized from amino acid amides(AA-NH2)under wet–dry cycle conditions without the need for any enhancers.The subsequent investigation revealed that AA-NH2 demonstrated more favorable thermodynamic reaction effects than AAs in peptide formation.In contrast to the polymerization of AAs,the process of peptide formation through the polymerization of AA-NH2 was significantly simplified.Additionally,AA-NH2 was discovered to function as a“bridge”for the formation of peptides from AAs,thereby facilitating their participation in the synthesis of intricate peptide structures.On the basis of these findings,a plausible mechanism for the prebiotic origin network of peptides under primordial Earth conditions has been proposed.Overall,this research presents a plausible pathway for the generation of prebiotic peptides and peptide libraries within prebiotic environments. 展开更多
关键词 prebiotic chemistry origin of life chemical evolution PEPTIDE
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Discharge plasma for prebiotic chemistry: Pathways to life’s building blocks
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作者 DingWei Gan LongFei Hong +9 位作者 TianYu Li TianQi Zhang XiangYu Wang JiePing Fan RuSen Zhou DingXin Liu JianXi Ying Patrick JCullen YuFen Zhao RenWu Zhou 《Earth and Planetary Physics》 EI CAS CSCD 2024年第6期823-835,共13页
Discharge plasmas, recognized as unique platforms for investigating the origins of chemical life, have garnered extensive interest for their potential to simulate prebiotic conditions. This paper embarks on a comprehe... Discharge plasmas, recognized as unique platforms for investigating the origins of chemical life, have garnered extensive interest for their potential to simulate prebiotic conditions. This paper embarks on a comprehensive overview of recent advancements in the plasma-enabled synthesis of life’s building blocks, charting the complex environmental parameters believed to have surrounded life’s inception. This discussion elaborates on the fundamental mechanisms of discharge plasmas and their likely role in fostering conditions necessary for the origin of life on early Earth. We consider a variety of chemical reactions facilitated by plasma, specifically the synthesis of vital organic molecules - amino acids, nucleobases, sugars, and lipids. Further, we delve into the impact of plasmas on prebiotic chemical evolution. We expect this review to open new horizons for future investigations in plasma-related prebiotic chemistry that could offer valuable insights for unraveling the mysteries of life's origin. 展开更多
关键词 origin of life discharge plasma prebiotic chemistry chemical evolution
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Promoting effect of nitrogen doping on carbon nanotube-supported RuO2 applied in the electrocatalytic oxygen evolution reaction
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作者 Kunpeng Xie Wei Xia +4 位作者 Justus Masa Fengkai Yang Philipp Weide Wolfgang Schuhmann Martin Muhler 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2016年第2期280-286,共7页
RuO2 nanoparticles supported on multi-walled carbon nanotubes(CNTs) functionalized with oxygen(OCNTs) and nitrogen(NCNTs) were employed for the oxygen evolution reaction(OER) in 0.1 M KOH.The catalysts were sy... RuO2 nanoparticles supported on multi-walled carbon nanotubes(CNTs) functionalized with oxygen(OCNTs) and nitrogen(NCNTs) were employed for the oxygen evolution reaction(OER) in 0.1 M KOH.The catalysts were synthesized by metal-organic chemical vapor deposition using ruthenium carbonyl(Ru3(CO)(12)) as Ru precursor. The obtained RuO2/OCNT and RuO2/NCNT composites were characterized using TEM, H2-TPR, XRD and XPS in order probe structure–activity correlations, particularly, the effect of the different surface functional groups on the electrochemical OER performance. The electrocatalytic activity and stability of the catalysts with mean RuO2 particle sizes of 13–14 nm was evaluated by linear sweep voltammetry, cyclic voltammetry, and chronopotentiometry, showing that the generation of nitrogen-containing functional groups on CNTs was beneficial for both OER activity and stability. In the presence of RuO2, carbon corrosion was found to be significantly less severe. 展开更多
关键词 Ruthenium dioxide chemical vapor deposition Nitrogen-doped carbon nanotubes Oxygen evolution reaction
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Origins of building blocks of life: A review 被引量:2
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作者 Norio Kitadai Shigenori Maruyama 《Geoscience Frontiers》 SCIE CAS CSCD 2018年第4期1117-1153,共37页
How and where did life on Earth originate? To date, various environments have been proposed as plausible sites for the origin of life. However, discussions have focused on a limited stage of chemical evolution, or em... How and where did life on Earth originate? To date, various environments have been proposed as plausible sites for the origin of life. However, discussions have focused on a limited stage of chemical evolution, or emergence of a specific chemical function of proto-biological systems. It remains unclear what geochemical situations could drive all the stages of chemical evolution, ranging from condensation of simple inorganic compounds to the emergence of self-sustaining systems that were evolvable into modern biological ones. In this review, we summarize reported experimental and theoretical findings for prebiotic chemistry relevant to this topic, including availability of biologically essential elements(N and P) on the Hadean Earth, abiotic synthesis of life's building blocks(amino acids, peptides, ribose, nucleobases, fatty acids, nucleotides, and oligonucleotides), their polymerizations to bio-macromolecules(peptides and oligonucleotides), and emergence of biological functions of replication and compartmentalization. It is indicated from the overviews that completion of the chemical evolution requires at least eight reaction conditions of(1) reductive gas phase,(2) alkaline pH,(3) freezing temperature,(4)fresh water,(5) dry/dry-wet cycle,(6) coupling with high energy reactions,(7) heating-cooling cycle in water, and(8) extraterrestrial input of life's building blocks and reactive nutrients. The necessity of these mutually exclusive conditions clearly indicates that life's origin did not occur at a single setting; rather, it required highly diverse and dynamic environments that were connected with each other to allow intratransportation of reaction products and reactants through fluid circulation. Future experimental research that mimics the conditions of the proposed model are expected to provide further constraints on the processes and mechanisms for the origin of life. 展开更多
关键词 ASTROBIOLOGY BIOCHEMISTRY chemical evolution Extraterrestrial life Hadean Earth Hydrothermal systems
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Nuclear geyser model of the origin of life:Driving force to promote the synthesis of building blocks of life 被引量:2
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作者 Toshikazu Ebisuzaki Shigenori Maruyama 《Geoscience Frontiers》 SCIE CAS CSCD 2017年第2期275-298,共24页
We propose the nuclear geyser model to elucidate an optimal site to bear the first life.Our model overcomes the difficulties that previously proposed models have encountered.Nuclear geyser is a geyser driven by a natu... We propose the nuclear geyser model to elucidate an optimal site to bear the first life.Our model overcomes the difficulties that previously proposed models have encountered.Nuclear geyser is a geyser driven by a natural nuclear reactor,which was likely common in the Hadean Earth,because of a much higher abundance of 235U as nuclear fuel.The nuclear geyser supplies the following:(1)high-density ionizing radiation to promote chemical chain reactions that even tar can be used for intermediate material to restart chemical reactions,(2)a system to maintain the circulation of material and energy,which includes cyclic environmental conditions(warm/cool,dry/wet,etc.)to enable to produce complex organic compounds,(3)a lower temperature than 100℃ as not to break down macromolecular organic compounds,(4)a locally reductive environment depending on rock types exposed along the geyser wall,and(5)a container to confine and accumulate volatile chemicals.These five factors are the necessary conditions that the birth place of life must satisfy.Only the nuclear geyser can meet all five,in contrast to the previously proposed birth sites,such as tidal flat,submarine hydrothermal vent,and outer space.The nuclear reactor and associated geyser,which maintain the circulations of material and energy with its surrounding environment,are regarded as the nuclear geyser system that enables numerous kinds of chemical reactions to synthesize complex organic compounds,and where the most primitive metabolism could be generated. 展开更多
关键词 Origin of life chemical evolution Natural nuclear reactor Aqueous electron Radiation chemistry
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Interaction between N-Phospho-Amino Acids and Nucleoside in Aqueous Medium
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作者 Yu Fen ZHAO Jian Jun HU Yong JU (State Laboratory of Bioorganic Phosphorus Chemistry. Department of Chemislry. School of Life Science and Engineering. Tsinghua University. Beijing 100084) 《Chinese Chemical Letters》 SCIE CAS CSCD 2000年第5期407-408,共2页
Nucleosides were phosphorylated with different N- (O, O-diisopropyl) phosphoryl amino acids to give nucleoside mono phosphates in aqueous solution. 2', 3', and 5'-isomers had been confirmed by comparison w... Nucleosides were phosphorylated with different N- (O, O-diisopropyl) phosphoryl amino acids to give nucleoside mono phosphates in aqueous solution. 2', 3', and 5'-isomers had been confirmed by comparison with authentic samples on the basis of HPLC analysis. The conversion percentage of nucleoside indicated that N- (O, O-diisopropyl) phosphoryl aspartic acid reacted with adenosine and guanosine at a much higher rate than other kinds of N- phosphoryl amino acids. while phosphorylation of cytidine and uridine was relatively easy by using N- (O, O-diisopropyl) phosphoryl threonine. The result could give some clue to the prebiotic code origin of nucleic acid and protein. 展开更多
关键词 N-phospho-amino acids nucleoside mono phosphate PHOSPHORYLATION uridylyl uridine (UpU) origin chemical evolution
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Potential Prebiotic Relevance of Glycine Single Crystals Enclosing Fluid Inclusions: An Experimental and Computer Simulation with Static Magnetic Fields
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作者 E. Angeles-Camacho J. Cruz-Castañeda +8 位作者 A. Meléndez M. Colín-García K. Cervantes de la Cruz S. Ramos-Bernal A. Negrón-Mendoza G. Garza-Ramos P. Rodríguez-Zamora C. Camargo-Raya A. Heredia 《Advances in Biological Chemistry》 2020年第5期140-156,共17页
<span style="font-family:Verdana;">Glycine crystallizes into three different polymorphs called </span><i><span style="font-family:Verdana;">α</span></i><span... <span style="font-family:Verdana;">Glycine crystallizes into three different polymorphs called </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">, </span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;"> under standard physicochemical conditions. They have different features depending on their structural variations. The possible interaction of glycine with magnetic minerals in meteorites and comets or in the ancient Earth, paves the way to study the self-assembly and molecular behavior under irradiation and magnetic conditions. The magnetic field might induce the formation of a specific polymorph of glycine. To gain insight on the consequences of gamma irradiation with a gradient of static magnetic fields (0.06 T, 0.3 T, 0.42 T and 0.6 T) on the self-assembly of single macroscopic glycine crystals, we gamma irradiated the powdered amino acid and then assembled single crystals from water solutions. The preliminary results showed a stable formation of fluid </span><span style="font-family:Verdana;">inclusions in the single crystals and no straightforward effect on the</span><span style="font-family:Verdana;"> self-assem</span><span style="font-family:Verdana;">- </span><span style="font-family:;" "=""><span style="font-family:Verdana;">bly process after glycine gamma irradiation and interaction with static magnetic fields. The </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;"> glycine polymorph single crystals formed at 55<span style="white-space:nowrap;">°</span> from the magnetic longitudinal axis and seemed to be enhanced by gamma radiation. </span><span><span style="font-family:Verdana;">The </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;">-glycine single crystals presented L and D circular dichroism signals,</span></span><span style="font-family:Verdana;"> whereas the irradiated samples presented no circular dichroism bands. Com</span></span><span style="font-family:Verdana;">- </span><span style="font-family:;" "=""><span style="font-family:Verdana;">puter simulations suggest different catalytic properties from </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">γ</span></i><span style="font-family:Verdana;"> glycine crystals.</span></span> 展开更多
关键词 Glycine Polymorphs Fluid Inclusions Gamma Irradiation chemical evolution FT-IR Circular Dichroism Chiral Crystals
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Chromosomal Engineering of Escherichia coli for Efficient Production of Coenzyme Q_(10)
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作者 黄明涛 陈韵妍 刘建忠 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第5期559-569,共11页
The plasmid-expression system is routinely plagued by potential plasmid instability. Chromosomal integration is one powerful approach to overcome the problem. Herein we report a plasmid-free hyper-producer E.coli stra... The plasmid-expression system is routinely plagued by potential plasmid instability. Chromosomal integration is one powerful approach to overcome the problem. Herein we report a plasmid-free hyper-producer E.coli strain for coenzyme Q10 production. A series of integration expression vectors, pxKC3T5b and pxKT5b, were constructed for chemically inducible chromosomal evolution(multiple copy integration) and replicon-free and markerless chromosomal integration(single copy integration), respectively. A coenzyme Q10 hyper-producer Escherichia coli TBW20134 was constructed by applying chemically inducible chromosomal evolution,replicon-free and markerless chromosomal integration as well as deletion of menaquinone biosynthetic pathway.The engineered E. coli TBW20134 produced 10.7 mg per gram of dry cell mass(DCM) of coenzyme Q10 when supplemented with 0.075 g·L-1of 4-hydroxy benzoic acid; this yield is unprecedented in E. coli and close to that of the commercial producer Agrobacterium tumefaciens. With this strain, the coenzyme Q10 production capacity was very stable after 30 sequential transfers and no antibiotics were required during the fermentation process. The strategy presented may be useful as a general approach for construction of stable production strains synthesizing natural products where various copy numbers for different genes are concerned. 展开更多
关键词 coenzyme Q10 Escherichia coli chemically inducible chromosomal evolution replicon-free and markerless chromosomal integration chromosomal engineering
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Low-α metal-rich stars with sausage kinematics in the LAMOST survey: Are they from the Gaia-Sausage-Enceladus galaxy? 被引量:3
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作者 Gang Zhao Yuqin Chen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2021年第3期14-26,共13页
We search for metal-rich Sausage-kinematic(MRSK)stars with[Fe/H]>−0.8 and−100<Vϕ<50 km/s in LAMOST DR5 in order to investigate the influence of the Gaia-Sausage-Enceladus(GSE)merger event on the Galactic disk... We search for metal-rich Sausage-kinematic(MRSK)stars with[Fe/H]>−0.8 and−100<Vϕ<50 km/s in LAMOST DR5 in order to investigate the influence of the Gaia-Sausage-Enceladus(GSE)merger event on the Galactic disk.For the first time,we find a group of low-αMRSK stars,and classify it as a metal-rich tail of the GSE galaxy based on the chemical and kinematical properties.This group has slightly larger R_(apo),Z_(max) and Etot distributions than a previously-reported high-αgroup.Its low-αratio does not allow for an origin resulting from the splash process of the GSE merger event,as is proposed to explain the high-αgroup.A hydrodynamical simulation by Amarante et al.provides a promising solution,in which the GSE galaxy is a clumpy Milky-Way analogue that develops a bimodal disk chemistry.This scenario explains the existence of MRSK stars with both high-αand low-αratios found in this work.It is further supported by another new feature that a clump of MRSK stars is located at Z_(max)=3-5 kpc,which corresponds to the widely adopted disk-halo transition at|Z|∼4 kpc.We suggest that a pile-up of MRSK stars at Zmax contributes significantly to this disk-halo transition,an interesting imprint left by the GSE merger event.These results also provide an important implication on the connection between the GSE and the Virgo Radial Merger. 展开更多
关键词 Galactic halo spiral arms and Galactic disk chemical composition and chemical evolution kinematics and dynamics rotation
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Nucleosynthesis in thermonuclear supernovae
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作者 Claudia Travaglio W. Raphael Hix 《Frontiers of physics》 SCIE CSCD 2013年第2期199-216,共18页
We review our understanding of the nucleosynthesis that occurs in thermonuclear supernovae and their contribution to Galactic Chemical evolution. We discuss the prospects to improve the modeling of the nucleosynthesis... We review our understanding of the nucleosynthesis that occurs in thermonuclear supernovae and their contribution to Galactic Chemical evolution. We discuss the prospects to improve the modeling of the nucleosynthesis within simulations of these events. 展开更多
关键词 SUPERNOVAE nuclear reactions explosive nucleosynthesis stellar spectra hydrodynamics chemical evolution
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Mechanism of Lithium and Cobalt Recovery from Spent Lithium-ion Batteries by Sulfation Roasting Process
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作者 YU Yucshan WANG Dahui +3 位作者 CHEN Huaijing ZHANG Xiaodong XU Li YANG Lixin 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2020年第5期908-914,共7页
Diflerent from the traditional pyTometallurgical recovery process of Li and Co from spent lithium-ion batteries,a new recovery method for Li and Co was established by converting LiCoO2 into water-soluble metal sul-fat... Diflerent from the traditional pyTometallurgical recovery process of Li and Co from spent lithium-ion batteries,a new recovery method for Li and Co was established by converting LiCoO2 into water-soluble metal sul-fates by roasting a mixture of LiCoO2 and NaHSO4-H2O.The evolution law of the mixture with increased roasting temperature was investigated by thennogravimetry-diflerential scamiing calorimetry(TG-DSC),in situ X-ray diflrac-tion(XRD),XRD,and X-ray photoelectron spectroscopy(XPS).The results show that the phase transition of LiCoO2 mixed with NaHSO4 H2O with increased temperature proceeded as follows:LiCoO2,NaHSO4 H2O→LiCo02,NaHSO4→Lil-xCo02,LiNaSO4,Na2S2O7,Na2SO4→Li1-xCoCO2,Co3O4,LiNaSO4,Na2SO4→Co3O4,LiNaSO4.The reaction mechanism of this roasting process may be as follows:LiCoO2+NaHSO4-H2O→l/2Li2SO4+l/2Na2SO4+l/3Co3O4+l/12O2+3/2H2O,Li2SO4+Na2SO4=2LiNaSO4. 展开更多
关键词 LICOO2 chemical evolution ROASTING In situ XRD
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The TMRT K band observations towards 26 infrared dark clouds:NH_3, CCS, and HC_3N
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作者 Jinjin Xie Gary A.Fuller +9 位作者 Di Li Longfei Chen Zhiyuan Ren Jingwen Wu Yan Duan Junzhi Wang Juan Li Nicolas Peretto Tie Liu Zhiqiang Shen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2021年第7期126-136,共11页
We present one of the first Shanghai Tian Ma Radio Telescope (TMRT) K Band observations towards a sample of 26 infrared dark clouds (IRDCs).We observed the (1,1),(2,2),(3,3),and (4,4) transitions of NH_(3) together wi... We present one of the first Shanghai Tian Ma Radio Telescope (TMRT) K Band observations towards a sample of 26 infrared dark clouds (IRDCs).We observed the (1,1),(2,2),(3,3),and (4,4) transitions of NH_(3) together with CCS (2_(1)–>1_(0)) and HC_(3)NJ=2-1,simultaneously.The survey dramatically increases the existing CCS-detected IRDC sample from 8 to 23,enabling a better statistical study of the ratios of carbon-chain molecules (CCM) to N-bearing molecules in IRDCs.With the newly developed hyperfine group ratio (HFGR) method of fitting NH_(3) inversion lines,we found the gas temperature to be between 10 and18 K.The column density ratios of CCS to NH_(3) for most of the IRDCs are less than 10^(-2),distinguishing IRDCs from low-mass star-forming regions.We carried out chemical evolution simulations based on a three-phase chemical model NAUTILUS.Our measurements of the column density ratios between CCM and NH_(3) are consistent with chemical evolutionary ages of 10^(5) yr in the models.Comparisons of the data and chemical models suggest that CCS,HC_(3)N,and NH_(3) are sensitive to the chemical evolutionary stages of the sources. 展开更多
关键词 star formation infrared dark clouds chemical evolution
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