3,973 research outputs found
Bai pin pu wang luo zhong de jing ji xue
No full textLuo, Yuan.Thesis Ph.D. Chinese University of Hong Kong 2015.Includes bibliographical references (leaves 273-283).Abstracts also in Chinese.Title from PDF title page (viewed on 01, November, 2016).Luo, Yuan
Mineral-bound lipid formation in soils and sediments: the importance of microbial pathways
No full textDecline in oceanic sulfate levels during the early Mesoproterozoic
No full textMultiple-sulfur isotope compositions ([superscript 32]S, [superscript 33]S, [superscript 34]S and [superscript 36]S) were analyzed for paired carbonate-associated sulfate (CAS) and disseminated pyrite (PY) from the ∼1.6-Ga Gaoyuzhuang Formation of the North China Craton to reconstruct the history of sulfate levels in Proterozoic oceans. The 200-m-thick study interval yielded relatively constant values for δ[superscript 34]S[subscript CAS] (13.0 ± 1.8‰), δ[superscript 34]S[subscript PY] (8.0 ± 2.3‰), and Δ[superscript 34]S[subscript CAS-PY] (∼5‰), as well as relatively constant Δ[superscript 33]S (0 ± 0.05‰) and Δ[superscript 36]S (0.35 ± 0.15‰) for both CAS and pyrite. Limited variation in δ[superscript 34]S[subscript PY] and slightly lower Δ[superscript 33]S of pyrite relative to CAS suggest water-column precipitation of pyrite. Limited fractionation of sulfur during microbial sulfate reduction (as documented by Δ[superscript 34]S[subscript CAS-PY]) implies low seawater sulfate concentrations in the early Mesoproterozoic ocean. We quantitatively constrained paleo-seawater [SO[subscript 4][superscript 2−]] using a novel modeling approach based on measured values of Δ[superscript 34]S[subscript CAS-PY] and ∂δ[superscript 34]S[subscript CAS]/∂t(max). For the study unit, Δ[superscript 34]S[subscript CAS-PY] is 5.4 ± 1.4‰ (n = 17), and ∂δ[superscript 34]S[subscript CAS]/∂t(max) is 6.8–34‰ Myr[superscript −1] based on sedimentation rates of 30–150 m Myr[superscript −1]. These data indicate early Mesoproterozoic seawater [SO[subscript 4][superscript 2−]] of ∼<0.1 to 0.35 mM (with a maximum possible concentration of 1.8 mM), a range that is lower and more tightly constrained than earlier estimates for the Mesoproterozoic. Compilation of published data suggests that low seawater sulfate concentrations began about ∼1.7 Ga and persisted until at least the mid-Mesoproterozoic (∼1.4 Ga), documenting a distinct early Mesoproterozoic perturbation in ocean chemistry that may have been related to a decline in atmospheric pO[subscript 2] after Great Oxidation Event I.National Basic Research Program of China (973 Program) (Grants 2011CB808800 and 2013CB955704)National Natural Science Foundation (China) (Grant 41472170)National 111 Project of China (Grant B08030)China University of Geosciences (CUG 130406 and CUG120117)National Science Foundation (U.S.) (Grant 1338810)NASA Astrobiology InstituteSimons Foundatio
No evidence for high atmospheric oxygen levels 1,400 million years ago
No full textZhang et al. (1) recently proposed atmospheric oxygen levels of ∼4% present atmospheric levels (PAL) based on modeling a paleoenvironment reconstructed from trace metal and biomarker data from the 1,400 Ma Xiamaling Formation in China. Intriguingly, this pO2 level is above the threshold oxygen requirements of basal animals and clashes with evidence for atmospheric oxygen levels <<1% PAL in the mid-Proterozoic (2). However, there are fundamental problems with the inorganic and organic geochemical work presented by Zhang et al. (1)
Rapid oxygenation of Earths atmosphere 2.33 billion years ago
No full textMolecular oxygen (O[subscript 2]) is, and has been, a primary driver of biological evolution and shapes the contemporary landscape of Earth’s biogeochemical cycles. Although “whiffs” of oxygen have been documented in the Archean atmosphere, substantial O2 did not accumulate irreversibly until the Early Paleoproterozoic, during what has been termed the Great Oxygenation Event (GOE). The timing of the GOE and the rate at which this oxygenation took place have been poorly constrained until now. We report the transition (that is, from being mass-independent to becoming mass-dependent) in multiple sulfur isotope signals of diagenetic pyrite in a continuous sedimentary sequence in three coeval drill cores in the Transvaal Supergroup, South Africa. These data precisely constrain the GOE to 2.33 billion years ago. The new data suggest that the oxygenation occurred rapidly—within 1 to 10 million years—and was followed by a slower rise in the ocean sulfate inventory. Our data indicate that a climate perturbation predated the GOE, whereas the relationships among GOE, “Snowball Earth” glaciation, and biogeochemical cycling will require further stratigraphic correlation supported with precise chronologies and paleolatitude reconstructions.National Science Foundation (U.S.) (EAR-1338810)National Natural Science Foundation (China) ((grant no. 41472170)Wellcome Trust Sanger Institute ( 111 Project grant no. B08030)National Basic Research Program of China (973 Program)United States. National Aeronautics and Space Administration (NASA Astrobiology Institute award NNA13AA90A
Esempio di rappresentazione del sé in Lu Ling 路翎, Luo Dadou de yisheng 罗大斗的一生 (La vita di Luo Dadou)
No full textIn the story Luo Dadou’s life (Luo Dadou de yisheng 罗大斗的一生), Lu Ling 路翎 (1923-1994) gives shape to the deepness of human psyche and stresses the suffering of the Self of his age by giving a brilliant emphasis to human individuality. The author succeeds in doing so by creating an amazing psychological characterization of the main character, both by means of words and by means of grammatical structures. By applying Denton’s categories for the study of the Self in modern Chinese literature, I analysed Lu Ling’s short story from the Freudian and Kleinian psychodynamic perspective, so to demonstrate how Lu Ling enters his characters’ minds and wonderfully recreates the psychological dynamics inside and between them
Design of split-inductors applied in positive output super lift luo-converters
No full textAs the demand of the modern electronic devices and appliances are getting higher, the role of the converters with higher output and efficiency become wider for different industries. It has been the role of engineers to explore the converter topology to provide higher output voltage in simple design with less cost. There are quite a number of different ways of lifting output voltage in converter topology.The method that the author will be introducing is called “Split- Inductors Method”, where the
output voltage is totally dependent on the number of inductors used in the converter design. The
report will include a detail discussion about design and results of” split-inductors topology”,
applied to “Positive Output Super Lift Luo Converter” using software simulations and hardware
experiments.Bachelor of Engineerin
Nitrogen fixation sustained productivity in the wake of the Palaeoproterozoic Great Oxygenation Event
No full textThe marine nitrogen cycle is dominated by redox-controlled biogeochemical processes and, therefore, is likely to have been revolutionised in response to Earth-surface oxygenation. The details, timing, and trajectory of nitrogen cycle evolution, however, remain elusive. Here we couple nitrogen and carbon isotope records from multiple drillcores through the Rooihoogte-Timeball Hill Formations from across the Carletonville area of the Kaapvaal Craton where the Great Oxygenation Event (GOE) and its aftermath are recorded. Our data reveal that aerobic nitrogen cycling, featuring metabolisms involving nitrogen oxyanions, was well established prior to the GOE and that ammonium may have dominated the dissolved nitrogen inventory. Pronounced signals of diazotrophy imply a stepwise evolution, with a temporary intermediate stage where both ammonium and nitrate may have been scarce. We suggest that the emergence of the modern nitrogen cycle, with metabolic processes that approximate their contemporary balance, was retarded by low environmental oxygen availability.National Science Foundation (U.S.) (Grant EAR-1338810)National Science Foundation (U.S.) (Grant EAR-1455258
Zhong guo fan long duan he bing shen cha de bi jiao yan jiu
No full textLuo, Yi.Thesis Ph.D. Chinese University of Hong Kong 2015.Includes bibliographical references (leaves 336-349).Abstracts also in Chinese.Title from PDF title page (viewed on 15, November, 2016).Luo, Yi
A Study on Luo Zhi Cheng\ue2s Historical narrative poems
No full textLuo Zhi Cheng is an important poet in the field of Taiwanese modern poetry, who is known for distinctive linguistic style and intense creative consciousness that are respected. Based on his powerful imagination and flourishing creativity as two primary advantages, through the mediation of poetry, prose, remarks, and commentaries, he maximally amplifies the implication of literature, and thereby composes himself and enriches the character. Distinguished from the majority of researchers focusing on Luo\ue2s lyric works, this study particularly found a writing context of \ue2avoidance of lyric sensibility\ue2 in Luo\ue2s poems, that is, his series of works historical themes in the form of long poems utilizing narrative skills to exhibit the remarkable consistency between the internality and the externality of the author.
\ue3\ue3This study conducted a comparative investigation of Luo\ue2s poetry work (The Book of Zhuzi) and prose works (Austral Court\ue2s Notandum and The Initiation of Civilization) to build a relatively more multi-faceted \ue2author\ue2s image of Luo Zhi Cheng\ue2 according to the writing of works of historical themes. Using the methodology of narratology, I departed from the internality of the text (the collection of poems) to identify how Luo forms the ideal spectrum of character by shaping historical persons; and meanwhile, I equally departed from the collections of prose to grasp the external information of the texts, and thereby clarified that Luo may treat \ue2writing, individual, and society\ue2 as a process of self-fulfillment. It is the two corresponding identities \ue2poet\ue2 and \ue2the intellectual\ue2 that are the mechanism of his constructing self-justification. Such investigation of the internality and the externality of text confirmed the complex relationships of the sustained \ue2opposition,\ue2 \ue2coexistence,\ue2 and \ue2conflict\ue2 between Luo and his works of historical themes
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