| 1451. |
- Li, Jing-Jing, et al.
(författare)
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Immobilized Triton X-100-assisted refolding of Green Fluorescent Protein-Tobacco Etch Virus protease fusion protein using β-cyclodextrin as the eluent
- 2009
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113 .- 1873-3298. ; 44:3, s. 277-282
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Tidskriftsartikel (refereegranskat)abstract
- A new protein refolding technique based on the use of the non-charged detergent Triton X-100 immobilized to the cross-linked agarose gel Sepharose High Performance has been developed. The new solid phase was used in combination with soluble β-cyclodextrin (β-CD) to refold recombinant Green Fluorescent Protein fused to Tobacco Etch Virus protease (GFPTEVP) expressed as inclusion bodies in E. coli. Previous attempts to refold recombinant GFPTEVP by dilution had failed. In the new procedure a column packed with Triton X-100-coupled Sepharose High Performance was used to capture unfolded GFPTEVP followed by elution using an increasing β-CD concentration gradient. The yield of properly refolded GFPTEVP was 46% at a protein concentration of 380 μg/ml. In contrast, dilution refolding of GFPTEVP at 200 μg/ml refolding buffer resulted in only 4.7% of native protein.
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| 1452. |
- Li, Jing-Jing, et al.
(författare)
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Immobilized β-cyclodextrin polymer coupled to agarose gel properly refolding recombinant Staphylococcus aureus elongation factor-G in combination with detergent micelle
- 2006
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Ingår i: Protein Expression and Purification. ; 45:1, s. 72-79
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Tidskriftsartikel (refereegranskat)abstract
- A novel artificial chaperone system using a combination of interactions between the unfolded protein, a detergent and a chromatographic column packed with immobilized β-cyclodextrin (β-CD) polymer coupled to an agarose gel, was introduced to refold recombinant Staphylococcus aureus elongation factor-G (EF-G). Pre-mixing of 10% Triton X-100 and unfolded EF-G at 24 mg/ml followed by a 20-fold dilution into refolding buffer led to successful capturing of EF-G by Triton X-100 resulting in formation of a detergent–protein complex at 1.2 mg/ml of final protein concentration. The complex was subsequently applied to the immobilized β-CD polymer column resulting in correct refolding of EF-G at a concentration of 530 μg/ml with 99% mass recovery. Detergent concentrations above critical micelle concentration were required for efficient capturing of EF-G at high protein concentration. Other detergents with hydrophile–lipophile-Balance values similar to that of Triton X-100 (Triton N-101, Noindet P40 (NP40), and Berol 185) also produced similar result. Soluble polymerized β-CD was more efficient than the monomer to remove the detergent from the protein complex in a batch system. Immobilized β-CD polymer column further improved the capability of detergent removal and was able to prevent aggregation that occurred with the addition of soluble β-CD polymer at high protein concentration in the batch system. The mechanism for this system-assisted refolding was tentatively interpreted: the released protein could correctly refold in an enclosed hydrophilic environment provided by the integration of matrix and β-CD polymer, and thus avoided aggregation during detergent removal.
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| 1453. |
- Li, Jingchen, et al.
(författare)
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The inhibiting effect of Re-rich layer on the interdiffusion between NiAl and Ni3Al-based superalloy and its degradation
- 2023
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Ingår i: Journal of Alloys and Compounds. - : ELSEVIER SCIENCE SA. - 0925-8388 .- 1873-4669. ; 957
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Tidskriftsartikel (refereegranskat)abstract
- A NiAl alloy/ Ni3Al-based superalloy diffusion couple with an electroplated NiRe layer was prepared. High-temperature interdiffusion performance of the diffusion couple was analyzed at 1100 degrees C under argon at-mosphere and compared with that of the blank group without NiRe layer. A Re-based diffusion barrier formed during the diffusion. The microstructural instability of the superalloy was found to be alleviated by the Re-based diffusion barrier, and the detailed microstructure of the diffusion barrier was identified to be Re-rich a phases and Mo-rich << phase detected by TEM. The chemical diffusion coefficient of Al was reduced by about two orders of magnitude with the modification of the Re-based diffusion barrier. A microstructural degradation of the Re-based barrier layer was observed after high-temperature diffusion of 300 h, which can be attributed to the internal diffusion of Mo.(c) 2023 Elsevier B.V. All rights reserved.
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| 1454. |
- Li, K., et al.
(författare)
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MBE-based SiGe/Si heterojunction multilayer structures
- 2001
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 227-228, s. 744-748
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, SiGe/Si multilayer heterostructures prepared by molecular beam epitaxy (MBE) are described with the aim of manufacturing SiGe heterojunction bipolar transistors (HBTs). Based on the simulations made by Medici, device structures have been designed and grown. The quality of the MBE layered structures has been characterized by reflection high-energy electron diffraction, X-ray diffraction, secondary ion mass spectrometry and spreading resistance. Furthermore, SiGe-HBTs have been fabricated. Promising DC and RF results of processed HBT devices have been obtained. © 2001 Elsevier Science B.V.
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| 1455. |
- Li, Man-Bo, et al.
(författare)
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Amino-Supported Palladium Catalyst for Chemo- and Stereoselective Domino Reactions
- 2021
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 60:2, s. 670-674
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Tidskriftsartikel (refereegranskat)abstract
- A solid amino-supported palladium catalyst is used in an oxidative domino reaction for the diastereoselective construction of alkyne-substituted cyclopentenol compounds. This heterogeneous catalyst exhibits high efficiency and excellent chemoselectivity, as well as good recyclability. The chemoselectivity of the domino reactions was readily controlled by switching the solvent and catalyst. Asymmetric syntheses and an oxidative carbocyclization-borylation reaction have also been developed based on the heterogeneous palladium catalyst.
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| 1456. |
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| 1457. |
- Li-mei, Fang, et al.
(författare)
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Field controllable electronic properties of MnPSe3/WS2 heterojunction for photocatalysis
- 2021
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Ingår i: JOURNAL OF CENTRAL SOUTH UNIVERSITY. - : JOURNAL OF CENTRAL SOUTH UNIV. - 2095-2899 .- 2227-5223. ; 28:12, s. 3728-3736
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Tidskriftsartikel (refereegranskat)abstract
- Transition metal dichalcogenides are interesting candidates as photocatalysts for hydrogen evolution reaction. The MnPSe3/WS2 heterostructure is hence studied here with first principles calculations by exploring its electronic properties under the application of an electric field. It is discovered that the band gap will decrease from the WS2 monolayer to the MnPSe3/WS2 heterostructure with Perdew-Burke-Ernzerhof functional, while increase slightly when electron correlation is involved. The conduction band minimum of the heterostructure is determined by the MnPSe3 layer, while the valence band maximum is contributed by the WS2 layer. The band edges and band gap suggest that the heterostructure will have good photocatalytic properties for water splitting. Moreover, comparing to monolayer WS2, the light absorption in both the ultraviolet and visible regions will be enhanced. When an electric field is present, a linear relation is observed between the electric field and the band gap within specific range, which can thus modulate the photocatalytic performance of this heterostructure.
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| 1458. |
- Li, N., et al.
(författare)
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Detection wavelengths and photocurrents of very long wavelength quantum-well infrared photodetectors
- 2005
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Ingår i: Infrared Physics and Technology. - : Elsevier BV. - 1350-4495. ; 47:1-2, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- Based on detailed studies of the energy band structure and the optical transitions in very long wavelength (>14 μm) GaAs/AlGaAs quantum-well (QW) infrared photodetectors (QWIPs), we have built a practical QWIP model. We study the factors that determine photogenerated carriers and response wavelengths of photocurrents of very long wavelength QWIPs. The material structures of QWIPs are first characterized by the photoluminescence measurements (PL) at room temperature and 77 K respectively. We have found and confirmed a distinctive difference between photocurrent of QWIPs with only one confined state in the quantum well (QW) and those binding two confined states, which resulted in different dependence of detection wavelength on the quantum well width. Also, we have investigated the dependence of response wavelength on several other parameters for very long wavelength QWIPs, such as barrier width and Al mole fraction. By calculating the density of photogenerated carriers in the continuum above the energy barriers using the PL calibrated QWIP structures, we have demonstrated that due to the high sample quality, the photocarriers can be either in miniband states (Bloch states in the multiple quantum wells), or they transport from one quantum well to the next in the form of propagating waves. We have further calculated the densities of photocarriers in the QWIPs reported in the literature. It is shown that the Bloch wave boundary conditions are appropriate for QWIPs with narrow QWs, whereas propagating wave boundary conditions are appropriate for wide QWs.
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| 1459. |
- Li, Nian, et al.
(författare)
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In Situ Study of Order Formation in Mesoporous Titania Thin Films Templated by a Diblock Copolymer during Slot-Die Printing
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 12:51, s. 57627-57637
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Tidskriftsartikel (refereegranskat)abstract
- Slot-die printing, a large-scale deposition technique, is applied to fabricate mesoporous titania films. Printing is interesting, for example, for scaling up solar cells where titania films with an interconnected mesoporous network and a large surface-to-volume ratio are desired as photoanodes. A fundamental understanding of the structure evolution during printing is of high significance in tailoring these films. In this work, we provide important insights into the self-assembly of the slot-die-printed titania/polystyrene-block-poly(ethylene oxide) (PS-b-PEO) micelles into ordered hybrid structures in real time via in situ grazing-incidence small-angle X-ray scattering (GISAXS). GISAXS allows for tracking both vertical and lateral structure development of the film formation process. In the hybrid film, a face-centered cubic (FCC) structure is preferentially formed at the interfaces with air and with the substrate, while a defect-rich mixed FCC and bodycentered cubic (BCC) structure forms in the bulk. After calcination, the surface and inner morphologies of the obtained nanostructured titania films are compared with the spin-coated analogues. In the printed films, the initially formed nanoscale structure of the hybrid film is preserved, and the resulting mesoporous titania film shows a superior order as compared with the spincoated thin films which can be beneficial for future applications.
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| 1460. |
- Li, N., et al.
(författare)
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Tailoring Ordered Mesoporous Titania Films via Introducing Germanium Nanocrystals for Enhanced Electron Transfer Photoanodes for Photovoltaic Applications
- 2021
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 31:34
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Tidskriftsartikel (refereegranskat)abstract
- Based on a diblock-copolymer templated sol–gel synthesis, germanium nanocrystals (GeNCs) are introduced to tailor mesoporous titania (TiO2) films for obtaining more efficient anodes for photovoltaic applications. After thermal annealing in air, the hybrid films with different GeNC content are investigated and compared with films undergoing an argon atmosphere annealing. The surface and inner morphologies of the TiO2/GeOx nanocomposite films are probed via scanning electron microscopy and grazing-incidence small-angle X-ray scattering. The crystal phase, chemical composition, and optical properties of the nanocomposite films are examined with transmission electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet–visible spectroscopy. Special focus is set on the air-annealed nanocomposite films since they hold greater promise for photovoltaics. Specifically, the charge–carrier dynamics of these air-annealed nanocomposite films are studied, and it is found that, compared with pristine TiO2 photoanodes, the GeNC addition enhances the electron transfer, yielding an increase in the short-circuit photocurrent density of exemplary perovskite solar cells and thus, an enhanced device efficiency as well as a significantly reduced hysteresis.
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