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  • MDPI AG  (6)
  • Yi, Fei  (6)
  • 1
    Online Resource
    Online Resource
    Hydrophobically Associating Polymers Dissolved in Seawater for Enhanced Oil Recovery of Bohai Offshore Oilfields
    MDPI AG ; 2022
    In:  Molecules Vol. 27, No. 9 ( 2022-04-24), p. 2744-
    Details
    In: Molecules, MDPI AG, Vol. 27, No. 9 ( 2022-04-24), p. 2744-
    Abstract: As compared to China’s overall oil reserves, the reserve share of offshore oilfields is rather significant. However, offshore oilfield circumstances for enhanced oil recovery (EOR) include not just severe temperatures and salinity, but also restricted space on offshore platforms. This harsh oil production environment requires polymers with relatively strong salt resistance, solubility, thickening ability, rapid, superior injection capabilities, and anti-shearing ability. As a result, research into polymers with high viscosity and quick solubility is recognized as critical to meeting the criteria of polymer flooding in offshore oil reservoirs. For the above purposes, a novel hydrophobically associating polymer (HAP) was prepared to be used for polymer flooding of Bohai offshore oilfields. The synthetic procedure was free radical polymerization in aqueous solutions starting at 0 °C, using acrylamide (AM), acrylic acid (AA), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), and poly(ethylene glycol) octadecyl methacrylate (POM) as comonomers. It was discovered that under ideal conditions, the molecular weight of HAP exceeds 2.1 × 107 g⋅mol−1. In a simulated reservoir environment, HAP has substantially greater solubility, thickening property, and salt resistance than conventional polyacrylamide (HPAM), with equivalent molecular weight. Finally, the injectivity and propagation of the two polymers in porous media were investigated. Compared with HPAM, which has a similar molecular weight, HAP solution with the concentration of 0.175% had a much better oil displacement effect in the porous medium, which can enhance oil recovery by 8.8%. These discoveries have the potential to pave the way for chemical EOR in offshore oilfields.
    Type of Medium: Online Resource
    ISSN: 1420-3049
    URL: Article
    DOI: 10.3390/molecules27092744
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2008644-1
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  • 2
    Online Resource
    Online Resource
    Tuning the Doping Ratio and Phase Transition Temperature of VO2 Thin Film by Dual-Target Co-Sputtering
    MDPI AG ; 2019
    In:  Nanomaterials Vol. 9, No. 6 ( 2019-06-01), p. 834-
    Details
    In: Nanomaterials, MDPI AG, Vol. 9, No. 6 ( 2019-06-01), p. 834-
    Abstract: A new simple way for tuning the phase transition temperature (PTT) of VO2 thin films has been proposed to solve the problem of changing the doping ratio by using the dual-target co-sputtering method. A series of samples with W doping ratios of 0%, 0.5%, 1%, 1.5% and 2% have been fabricated by sputtering V films with the power of pure and 2% W-doped V targets from 500 W: 0 W, 500 W: 250 W, 500 W: 500 W, 250 W: 500 W to 0 W: 500 W respectively and then annealed in an oxygen atmosphere to form VO2. The XRD results of both pure and W-doped VO2 samples reveal that VO2 forms and is the main component after annealing. The PTT can be tuned by controlling the sputtering power ratio of the pure and doped targets. It can be tuned easily from 64.3 °C to 36.5 °C by using the pure and 2% W-doped targets for demonstration, with W doping ratios from 0% to 2%. It is also valid for other doping elements and is a promising approach for the large-scale production of sputtering.
    Type of Medium: Online Resource
    ISSN: 2079-4991
    URL: Article
    DOI: 10.3390/nano9060834
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2662255-5
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  • 3
    Online Resource
    Online Resource
    Transcriptomics and Proteomics Reveal the Cellulose and Pectin Metabolic Processes in the Tension Wood (Non-G-Layer) of Catalpa bungei
    MDPI AG ; 2020
    In:  International Journal of Molecular Sciences Vol. 21, No. 5 ( 2020-03-01), p. 1686-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 21, No. 5 ( 2020-03-01), p. 1686-
    Abstract: Catalpa bungei is an economically important tree with high-quality wood and highly valuable to the study of wood formation. In this work, the xylem microstructure of C. bungei tension wood (TW) was observed, and we performed transcriptomics, proteomics and Raman spectroscopy of TW, opposite wood (OW) and normal wood (NW). The results showed that there was no obvious gelatinous layer (G-layer) in the TW of C. bungei and that the secondary wall deposition in the TW was reduced compared with that in the OW and NW. We found that most of the differentially expressed mRNAs and proteins were involved in carbohydrate polysaccharide synthesis. Raman spectroscopy results indicated that the cellulose and pectin content and pectin methylation in the TW were lower than those in the OW and NW, and many genes and proteins involved in the metabolic pathways of cellulose and pectin, such as galacturonosyltransferase (GAUT), polygalacturonase (PG), endoglucanase (CLE) and β-glucosidase (BGLU) genes, were significantly upregulated in TW. In addition, we found that the MYB2 transcription factor may regulate the pectin degradation genes PG1 and PG3, and ARF, ERF, SBP and MYB1 may be the key transcription factors regulating the synthesis and decomposition of cellulose. In contrast to previous studies on TW with a G-layer, our results revealed a change in metabolism in TW without a G-layer, and we inferred that the change in the pectin type, esterification and cellulose characteristics in the TW of C. bungei may contribute to high tensile stress. These results will enrich the understanding of the mechanism of TW formation.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms21051686
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    A Comparison of the Evaporative Emissions Performance of Light-Duty Vehicles under US Tier 3 and China 6 Test Conditions
    MDPI AG ; 2023
    In:  Atmosphere Vol. 14, No. 7 ( 2023-07-07), p. 1128-
    Details
    In: Atmosphere, MDPI AG, Vol. 14, No. 7 ( 2023-07-07), p. 1128-
    Abstract: To further improve air quality in China, especially ozone and fine particulate matter (PM2.5), additional reductions of volatile organic compounds (VOCs) are needed. Evaporative emissions from internal combustion engines (ICE) and hybrid vehicles are known to be an important source of VOCs in urban cities, which can be efficiently reduced through the introduction of more stringent regulatory standards. The most stringent global standards for evaporative emissions are the U.S. Tier 3 light-duty vehicle standards. This study compares the evaporative emissions of light-duty ICE vehicles designed to China 6 and U.S. Tier 3 regulations for both China and U.S. test conditions. Data are analyzed from manufacturer testing of full vehicle evaporative emissions conducted in the laboratory following U.S. Tier 3 and China 6 certification test methods utilizing Sealed Housing for Evaporative Determination (SHED) chambers equipped with Flame Ionization Detection (FID) analyzers. Vehicles designed to U.S. Tier 3 standards are observed to have 64% lower diurnal and hot soak evaporative emissions and 98% lower canister bleed emissions relative to vehicles designed to China 6 standards. U.S. Tier 3, U.S. Tier 2, and China 6 light-duty evaporative emission certification values submitted by manufacturers are also compared. The average of all current U.S. Tier 3 certifications is, on average, 52.4% lower than the average of all China 6 certifications. The results from the testing and data analysis of five vehicles, with comparison to the certification data, suggest that the introduction of standards equivalent in stringency to U.S. Tier 3 in China can significantly reduce evaporative emissions relative to China 6.
    Type of Medium: Online Resource
    ISSN: 2073-4433
    URL: Article
    DOI: 10.3390/atmos14071128
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2605928-9
    SSG: 23
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  • 5
    Online Resource
    Online Resource
    Primary Selection of Excellent Catalpa fargesii Clones Based on Growth and Wood Properties
    MDPI AG ; 2022
    In:  Forests Vol. 13, No. 10 ( 2022-10-10), p. 1659-
    Details
    In: Forests, MDPI AG, Vol. 13, No. 10 ( 2022-10-10), p. 1659-
    Abstract: To select excellent clones characterized by fast growth and high-quality wood of Catalpa fargesii Bur., growth traits, including height and diameter at breast height (DBH) at 1, 9, 11 and 13 years old, were collected and wood properties, including the Pilodyn value and elastic modulus at age 13 of 200 clones of C. fargesii from different ecological areas (four provinces), were measured. Genetic variation analysis and repeatability estimation were carried out. The correlation between the characteristics and the correlation between the characteristics and the geographical and climatic factors were analyzed. Excellent clones were selected by a comprehensive evaluation method combined with breeding values. The traits of C. fargesii were significantly different among the clones. The coefficient of variation (CV) ranged from 12.12% to 26.17%, and the repeatability (R) ranged from 0.79 to 0.97. The growth traits among ages of 9, 11 and 13 were significantly correlated, and the growth traits at ages of 9, 11 and 13 and Pilodyn values at the age of 13 were positively correlated with altitude and negatively correlated with longitude. Tree growth at ages of 11 and 13 showed a high negative correlation with wood properties. The suitable tree age for the early selection of clones with excellent growth and wood properties is 11 years old. Nine clones with excellent growth, six clones with high-quality wood and three clones with great growth and wood properties were selected, which laid a foundation for further optimization of C. fargesii clones. Additionally, C. fargesii clones in the western and high-altitude areas featured fast growth, while those in the eastern and low-altitude areas had better wood properties. This study serves as a reference for the selection of C. fargesii clones in different ecological areas.
    Type of Medium: Online Resource
    ISSN: 1999-4907
    URL: Article
    DOI: 10.3390/f13101659
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527081-3
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  • 6
    Online Resource
    Online Resource
    Study of an Integration Platform Based on an Adiabatic Active-Layer Waveguide Connection for InP Photonic Device Integration Mirroring That of Heterogeneous Integration on Silicon
    MDPI AG ; 2021
    In:  Photonics Vol. 8, No. 10 ( 2021-10-09), p. 433-
    Details
    In: Photonics, MDPI AG, Vol. 8, No. 10 ( 2021-10-09), p. 433-
    Abstract: In this work, a photonic device integration platform capable of integration of active-passive InP-based photonic devices without the use of material regrowth is introduced. The platform makes use of an adiabatic active-layer waveguide connection (ALWC) to move an optical beam between active and passive devices. The performance of this platform is analyzed using an example made up of four main sections: (1) a fiber coupling section for enabling vertical beam coupling from optical fiber into the photonic chip using a mode-matched surface grating with apodized duty cycles; (2) a transparent waveguide section for realizing passive photonic devices; (3) an adiabatic mode connection structure for moving the optical beam between passive and active device sections; and (4) an active device section for realizing active photonic devices. It is shown that the coupled surface grating, when added with a bottom gold reflector, can achieve a high chip-to-fiber coupling efficiency (CE) of 88.3% at 1550 nm. The adiabatic active-layer mode connection structure has an optical loss of lower than 1% (CE 〉 99%). The active device section can achieve an optical gain of 20 dB/mm with the use of only 3 quantum wells. The optimized structural parameters of the entire waveguide module are analyzed and discussed.
    Type of Medium: Online Resource
    ISSN: 2304-6732
    URL: Article
    DOI: 10.3390/photonics8100433
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2770002-1
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