Long-core experimental study of different displacement modes on fractured-vuggy carbonate reservoirs

Wenfang Li,Jiang Chen,Xiqun Tan,Ping Liu,Yun Li,Limin Wang 한국자원공학회 2018 Geosystem engineering Vol.21 No.2

It is difficult to utilize real fractured–vuggy carbonate cores to conduct long-core displacement experiments due to the special structures of fractured and vuggy. Aiming to not affect the porosity and permeability of the original core structure, a special filling method on the sunken space of the core surface was created to meet the requirements of long-core experiments. Long-core experiments of depletion drive, water flooding, gas drive, and water alternating gas (WAG) drive were performed to simulate the actual conditions of one-dimension oil reservoir and systematically study the influence of different development approaches on the recovery of vuggy carbonate reservoirs. Results show that the optimal conversion pressure of water flooding is between 80% bubble point and bubble point pressure. In the high-pressure and high water-cut stage, the development effect of gas–water alternative drive becomes significant, it can effectively reduce water cut and improve oil recovery. The most suitable and effective displacement mode is adopted depletion drive first and converts water flooding when the pressure decreases between 80% bubble point and bubble point pressure. When the water cut approximately reaches 80%, then WAG flooding is performed. The experiments provide data and technical support for the rational development of vuggy carbonate reservoirs.

Improvement of the Steroid Dihydroxylation Efficiency from Dehydroepiandrosterone Using a Substrate Pre-induction Biotransformation Process

Hui Li,Zhenzhen Fu,Heng Li,Wenfang Dou,Jinsong Shi,Zhenghong Xu 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.3

This study investigated the effects of hydroxylase cyptochrome P450 inducers on the efficiency of the biotransformation of dehydroepiandrosterone (DHEA) to 3β, 7α, 15α-trihydroxy-5-androsten-17-one (7α,15α-diOHDHEA)by Colletotrichum lini ST-1. Special attention was given to the substrate DHEA being the best inducer and the fact that it could improve the yield of 7α, 15α-diOHDHEA. Based on the effects of the DHEA pre-induction phases and additional concentrations on 7α, 15α-diOHDHEA production, a substrate pre-induction process was established as follows: 2 g/L DHEA was added for the first time after 12 h of inoculation, followed by the second addition of 6 g/L DHEA after 12 h later. The results showed that this substrate pre-induction process improved the content of cytochrome P450 and that the 7α, 15α-diOH-DHEA yield reached 90.1%, which was 26.9%higher than that obtained in the original process.

Surface Self-Nanocrystallization of α+β Titanium Alloy by Surface Mechanical Grinding Treatment

Chuang Li,Wenfang Cui,Yusheng Zhang 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.3

In this work, the heavy deformation was performed on Ti6Al4V alloy by using surface mechanical grindingtreatment (SMGT) in order to obtain surface nanocrystalline layer. The phase structure and microstructuresin the deformation zones were characterized by XRD, SEM and TEM. The nanocrystallization mechanisms ofα and α phase were clarified. The results show that a gradient structure including nano grain, quasi nanograinand micro-grains was achieved within the depth of 500 μm below the surface. The depth of nanocrystallineslayer was at least 20 μm. From the non deformation zone in the center to the heavy deformation zone close totreated surface, dislocation densities gradually increased. The original coarse grains gradually evolved intodislocation cell structures and subgrains through dislocation movement. In the depth of about 20 μm belowthe treated surface, the subgrains began to split into nano-scale grains with high angle grain boundaries bylattice rotation and tilting mechanisms. During SMGT, β phase deformed and refined prior to α phase, andinhibited the generation of twinning in α grain. The coordinated deformation between a and β phase promotedthe formation of nanocrystallines.

Dynamics of Endogenous Polyamines in Seedling Trees of Pyrus ussuriensis Maxim. × P. bretschneideri Rehd

Chunmin Li,Xinzhong Zhang,Wenquan Yue,Yongbo Zhao,Wenfang Zu,Guangpeng Wang,Ruifeng Chang,Huairui Shu 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

The Effects of Adenoviral Transfection of the Keratinocyte Growth Factor Gene on Epidermal Stem Cells: an In Vitro Study

Xinping Li,Mingsheng Zhang,Ling Liang,Pin Zhao,Kenzo Uchida,Hisatoshi Baba,Hong Huang,Wenfang Bai,Liming Bai 한국분자세포생물학회 2013 Molecules and cells Vol.36 No.4

Epidermal stem cells (ESCs) are characterized as slow-cycling, multi-potent, and self-renewing cells that not only maintain somatic homeostasis but also participate in tissue regeneration and repair. To examine the feasibility of adenoviral vector-mediated keratinocyte growth factor (KGF) gene transfer into in vitro-expanded ESCs, ESCs were isolated from samples of human skin, cultured in vitro, and then transfected with recombinant adenovirus (Ad) carrying the human KGF gene (AdKGF) or green fluorescent protein gene (AdGFP). The effects of KGF gene transfer on cell proliferation, cell cycle arrest, cell surface antigen phenotype, and -catenin expression were investigated. Compared to ESCs transfected with AdGFP, AdKGF-transfected ESCs grew well, maintained a high proliferative capacity in keratinocyte serum-free medium, and expressed high levels of -catenin. AdKGF infection increa-sed the number of ESCs in the G0/G1 phase and promoted ESCs entry into the G2/M phase, but had no effect on cell surface antigen phenotype (CD49f+/CD71-). The results suggest that KGF gene transfer can stimulate ESCs to grow and undergo cell division, which can be applied to enhance cutaneous wound healing.

Simultaneous Improvement of Thermal Conductivity and Strength for Commercial A356 Alloy Using Strontium Modification Process

Kang Wang,Wenfang Li,Wenzhi Xu,Shengyu Hou,Shaodong Hu 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

The Aluminum–Silicon (Al–Si) die-casting alloys, such as the commercial A356 alloy, are expected to be used in heat-sinkand the device with high thermal conductivity due to their high production efficiency of casting process. These fields alsorequired them to possess sound mechanical properties. To meet these demands, the Strontium (Sr) was often utilized tomodify the silicon phase. According to our current work, the secondary dendrite arm spacing of the α-Al grains prominentlywas decreased when 0.05%–0.25% strontium was added. The decrease of the secondary dendrite arm spacing (SDAS) lead tothe enhancement of the mechanical strength as well as the improvement of the thermal and electrical conductivity. When theSr dosage was 0.15% in the commercial A356 alloy, the strength and the thermal conductivity of the A356 alloy simultaneouslyreached the maximum value. The improvement of the electrical and thermal conductivity might by contributed by theformation of a good conductor, Al2Si2Srphase, on the Si surface. Further investigations suggested that the improvement ofthermal conductivity was mainly due to the modification effect of Sr on the eutectic Si phase, which enlarged the specificarea between the α-Al/eutectic Si interface. The WDS analysis indicated that the solubility of Si decreased in aluminummatrix by increasing in the Sr dosage. However, the excessive dosage of strontium would result in the coarsening of themodified silicon phase, deteriorating the strength and the thermal and electrical conductivity of the modified A356 alloys.

Microstructure and Properties of BaTiO3

Min Wang,Guoge Zhang,Wenfang Li,Xiaojun Wang 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.4

In this paper, we report the preparation of BaTiO3 (BT) ferroelectric films from barium hydroxide via micro arc oxidation (MAO) with additives. The BaTiO3 film was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-Raman spectroscopy, precision LCR measurements, and a Radiant Precision LC material analyzer. The results showed that the BT film was mainly composed of tetragonal-phase BaTiO3 , and the BT film was smooth, dense, and crack-free. At the frequency of 100 Hz, the film was found to possess a high dielectric constant of 245.3 and a low dielectric loss (tan δ) of 0.039. Compared with the BT film prepared without additives, the MAO-prepared film showed an increase of 61.1% in dielectric constant and a decrease of 59.4% in dielectric loss (tan δ). The BT film exhibited a saturated P–E hysteresis loop at room temperature.