20 research outputs found

    Problems with the application of heptane and isoheptane values as light hydrocarbon parameters

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    The light hydrocarbon data from 772 oil samples in 25 oilfields, together with GC/MS data from 338 saturated hydrocarbon samples were used to discuss the relationship between kerogen types, using the heptane value, isoheptane value and C29 sterane 20S/(S+R) ratio. Although the heptane and isoheptane values are related to kerogen type, the correlation is different from that in Thompson's interpretation, so the correlation cannot be directly used in research on land facies oils in China. Consideration should be taken when using the heptane and isoheptane values, as secondary alteration and mixed oil sources are the main factors leading to the abnormal change in heptane and isoheptane values. The heptane and isoheptane values have a larger maturity range than that of C29 sterane 20S/(S+R). There are three types of oil samples (original immature oil, altered oil and mixed source oil with different maturity) that may fall into the “Biodegradation” area of the Thompson interpretation. For the biodegraded oil in Thompson's interpretation, the reservoir may have undergone a secondary charge. 摘要: 用采自中国国内25个油区的772个原油轻烃分析数据, 结合其中338个样品的饱和烃GC/MS分析数据, 就原油正、异庚烷值与烃源岩干酪根类型的关系以及与C29甾20S/ (20S+20R)成熟度参数的相关性, 对影响参数值发生异常变化的因素等作了研讨。研究认为, 正、异庚烷值确实与母源干酪根类型有关, 但相关关系与Thompson的图版有所差别, 研究中国陆相原油时不宜直接引用; 原油次生蚀变和混源是使原油正、异庚烷值发生异常变化的重要因素, 在用正、异庚烷值作研究时必须备加注意; 正、异庚烷值标示原油成熟度的范围大于C29甾20S/(20S+20R)所能标示的; 落入Thompson图版“Biodegraded”区域的油样可能有3类: 原生的未熟油, 已遭蚀变的原油和成熟度不同的混源油, 对于未落入该区域内的生物降解油, 认为油藏存在二次注入的可能性。图6表2参26 Key words: light hydrocarbon, heptane value, isoheptane value, maturity parameter, secondary alteration, mixed source oi

    Light Management in Upconverting Nanoparticles: Ultrasmall Core/Shell Architectures to Tune the Emission Color

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    Ultrasmall NaGdF<sub>4</sub> nanoparticles with core/shell and core/shell/shell architectures have been synthesized following a microwave-based thermolysis procedure, allowing us to rapidly obtain homogeneous nanoparticles compared to conventional heating. To analyze the possibilities of the proposed structure in terms of tuning the emission color, core and shells have been doped with different lanthanide ion pairs (either Er<sup>3+</sup>/Yb<sup>3+</sup> and/or Tm<sup>3+</sup>/Yb<sup>3+</sup>), keeping them therefore spatially separated inside the different layers of the nanoparticles. Here, we demonstrate that the position of the dopants inside the nanoparticles affects the intensity of the different emission bands of the luminescing Tm<sup>3+</sup> and Er<sup>3+</sup> ions and show how it has a relevant effect on the overall emission color of the luminescence obtained after 975 nm excitation

    The Π-Formed Diaphragm Wall Construction for Departure and Reception of Shield Machine

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    In the design of shield tunnels, it is important to determine the structure of the diaphragm wall in order to achieve the required retaining wall structure pattern. In this paper, the stabilization effect of a new diaphragm wall structure (Π-formed diaphragm wall) is investigated based on model experiments and numerical simulations. By varying the length of the wing wall and its angle to the end wall, it is possible to discuss the effect of different styles of Π-formed diaphragm wall on the support of the soil behind the wall during the departure and reception of the shield machine, the effect of the wing wall on the internal force distribution of the diaphragm wall generated during excavation, the effect of the excavation of the shield machine on the internal force distribution of the diaphragm wall, and the ground settlement during the departure and reception of the shield machine in different construction stages. Π-formed diaphragm walls can effectively support the soil behind the wall and reduce the major principal stresses generated during excavation. The maximum value of the major principal stress in the wing wall of the Π-formed diaphragm wall increases with the length of the wing wall, and the damage to the concrete of the diaphragm wall tends to occur on the outside rim of the wing wall

    Magnetic Photoluminescent Nanoplatform Built from Large-Pore Mesoporous Silica

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    Integrating multiple components to realize cancer diagnosis and therapy in a single theranostic nanoplatform has drawn considerable attention. Herein, a multifunctional theranostic nanoplatform (mSiO2@PbS/CdS-Fe3O4) was successfully fabricated by carefully designing thiol-modified large-pore mesoporous silica nanospheres (mSiO2), followed by coordination-driven embedding of Fe3O4 nanoparticles (NPs) and PbS/CdS quantum dots (QDs) inside. The excellent feature of near-infrared (NIR) excitation and NIR emission of PbS/CdS QDs enables deep-tissue photoluminescence imaging, which was demonstrated ex vivo with tissue as thick as 14 mm. Meanwhile, owing to the presence of superparamagnetic Fe3O4 NPs, mSiO2@PbS/CdS-Fe3O4 can be rapidly confined under an external magnetic field (MF), and exhibit a significantly high T2 relaxivity in T2-weighted magnetic resonance (MR) images in vivo. When mSiO2@PbS/CdS-Fe3O4 was exposed to external physical stimuli of MF and/or NIR laser, they produced strong local heating through magnetothermal/photothermal effects. Owing to the unique mesoporous structure of mSiO2@PbS/CdS-Fe3O4, doxorubicin (DOX) was readily loaded into them and the drug-release profile was subsequently evaluated under multistimuli (pH/MF/NIR). The release of DOX was significantly enhanced at lower pH, and higher temperatures caused by magnetothermal/photothermal effects. Our results pave the road toward developing a highly powerful nanoplatform for bimodal imaging (NIR deep-tissue photoluminescence and MR imaging), and simultaneously for integrating synergistic treatment capabilities of hyperthermia and pH/MF/NIR-responsive drug release

    Multifunctional Self-Assembled Supernanoparticles for Deep-Tissue Bimodal Imaging and Amplified Dual-Mode Heating Treatment

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    Developing multifunctional therapeutic and diagnostic (theranostic) nanoplatforms is critical for addressing challenging issues associated with cancers. Here, self-assembled supernanoparticles consisting of superparamagnetic Fe3O4 nanoparticles and photoluminescent PbS/CdS quantum dots whose emission lies within the second biological window (II-BW) are developed. The proposed self-assembled Fe3O4 and PbS/CdS (II-BW) supernanoparticles [SASNs (II-BW)] exhibit outstanding photoluminescence detectable through a tissue as thick as 14 mm, by overcoming severe light extinction and concomitant autofluorescence in II-BW, and significantly enhanced T2 relaxivity (282 mM–1 s–1, ca. 4 times higher than free Fe3O4 nanoparticles) due to largely enhanced magnetic field inhomogeneity. On the other hand, SASNs (II-BW) possess the dual capacity to act as both magnetothermal and photothermal agents, overcoming the main drawbacks of each type of heating separately. When SASNs (II-BW) are exposed to the dual-mode (magnetothermal and photothermal) heating, the thermal energy transfer efficiency is amplified 7-fold compared with magnetic heating alone. These results, in hand with the excellent photo- and colloidal stability, and negligible cytotoxicity, demonstrate the potential use of SASNs (II-BW) for deep-tissue bimodal (magnetic resonance and photoluminescence) in vivo imaging, while simultaneously providing the possibility of SASNs (II-BW)-mediated amplified dual-mode heating treatment for cancer therapy
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