Sijia Li

Lanzhou University, Kao-lan-hsien, Gansu Sheng, China

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Publications (6)6.53 Total impact

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    ABSTRACT: Morphology and growth of hydrate crystals with cyclic structure inhibitors at a hydrate–liquid interface were directly observed through a microscopic manipulating apparatus. Tetrahydrofuran (THF) hydrate was employed as an objective. The effects of four kind of cyclic structure inhibitors, polyvinylpyrrolidone (PVP), poly(N-vinyl-2-pyrrolidone-co-2-vinyl pyridine) (PVPP), poly(2-vinyl pyridine-co-N-vinylcaprolactam) (PVPC) and poly(N-vinylcaprolactam) (PVCap), were investigated. Morphological patterns between each hydrate crystal growth from hydrate–liquid interface into droplet were found differ significantly. Lamellar structure growth of hydrate crystal was observed without inhibitor, while with PVP was featheriness-like, PVPP was like long dendritic crystal, PVPC was Mimosa pudica leaf-like and PVCap was like weeds. The growth rate of hydrate crystal without inhibitor was 0.00498 mm3/s, while with PVPP, PVPC and PVCap, were 0.00339 mm3/s, 0.00350 mm3/s, 0.00386 mm3/s and 0.00426 mm3/s, respectively. Cyclic structure inhibitors can decrease the growth rate, degree of reduction in growth rate of hydrate crystals decrease with the increase of cylinder number.
    Journal of Crystal Growth 08/2013; 377:101–106. · 1.55 Impact Factor
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    ABSTRACT: In oil and gas field, the application of kinetic hydrate inhibitors (KHIs) independently has remained problematic in high subcooling and high water-cut situation. One feasible method to resolve this problem is the combined use of KHIs and some synergists, which would enhance KHIs' inhibitory effect on both hydrate nucleation and hydrate crystal growth. In this study, a novel kind of KHI copolymer poly(N-vinyl-2-pyrrolidone-co-2-vinyl pyridine)s (HGs) is used in conjunction with TBAB to show its high performance on hydrate inhibition. The performance of HGs with different monomer ratios in structure II tetrahydrofuran (THF) hydrate is investigated using kinetic hydrate inhibitor evaluation apparatus by step-cooling method and isothermal cooling method. With the combined gas hydrate inhibitor at the concentration of 1.0 wt%, the induction time of 19 wt% THF solution could be prolonged to 8.5 h at a high subcooling of 6 °C. Finally, the mechanism of HGs inhibiting the formation of gas hydrate is proposed.
    Journal of Natural Gas Chemistry 03/2012; 21(2):126–131. · 1.41 Impact Factor
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    ABSTRACT: A previous study reported that ginsenoside-Rd reduced the production of tumor necrosis factor-α by inhibiting nuclear factor-κB in lipopolysaccharide-activated N9 microglia in vitro. The aim of the present study was to confirm the anti-inflammatory effects and mechanisms of ginsenoside-Rd in animal experiments involving acute inflammation. The results indicated that ginsenoside-Rd at doses ranging from 12.5 to 50 mg/kg i.m. significantly inhibited the swelling of hind paws in rats for 1-6 h after the carrageenan injection. The levels of proinflammatory cytokines and proinflammatory mediators were markedly reduced by ginsenoside-Rd. Ginsenoside-Rd, when administered intramuscularly at 12.5, 25, and 50 mg/kg doses, showed signicant inhibition of carrageenan-induced production of interleukin-1β (6.91%, 45.75%, and 55.18%, respectively), tumor necrosis factor-α (37.99%, 56.39%, and 47.38%, respectively), prostaglandin E(2) (22.92%, 30.12%, and 36.36%, respectively), and nitric oxide (28.27%, 44.53%, and 53.42%, respectively). In addition, ginsenoside-Rd (12.5, 25, and 50 mg/kg i.m.) effectively decreased the levels of nuclear factor-κB (6.77%, 20.28%, and 41.03%, respectively) and phosphorylation of IκBα (13.23%, 26.92%, and 41.80%, respectively) in the carrageenan-inflamed paw tissues. These results suggest that ginsenoside-Rd has significant anti-inflammatory effects in vivo, which might be due to its blocking of the nuclear factor-κB signaling pathway. Thus, it may be possible to develop ginsenoside-Rd as a useful agent for inflammatory diseases.
    Canadian Journal of Physiology and Pharmacology 02/2012; 90(2):229-36. · 1.56 Impact Factor
  • Shuanshi Fan, Sijia Li, Hua Xin
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    ABSTRACT: Steam based thermal processes are major technologies for bitumen and heavy oil recovery. They are energy intensive, high water demand and huge CO2 emission. When such technologies are applied to the reservoir with thief zones, the economics are even worse. In order to increase the efficiency, people are trying to add solvent into steam to reduce the operation pressure and temperature so the economics. The mechanism of adding solvent into is further reducing the viscosity of bitumen or heavy oil an addition to thermal effects. That means the solvent should be dissolved into oil as soon as they meet each other at the interface. The boiling point of the solvent should be near that of steam. When it is to far from steam, it stays either liquid being produced without reacting with oil or gas stopping the heat exchange of steam. In this paper, PVT of some pure and commercial solvents is reviewed and potential operation pressure and temperature are discussed. This can help engineers to select solvent and design the process properly.1. Introduction It is inescapable that global energy demand is in an increasing trend and will remain so for the coming decades. Heavy-oil and bitumen resources have a significant impact on meeting this demand because of their huge but almost untouched volume, it amounts to it amounts to approximately 70% of world's total oil resources (approximate 6.3-9.1×1012bbl) [1]. With around 7 trillion barrels of heavy oil available globally, the lack of an effcient, feasible, and environmentally friendly heavy-oil production technology is eminent. Steam injection is a proven thermal technique to be used for this purpose and it can be achieved through continuous or cyclic (huff-and-puff) injections. Field experience and simulations studies show that performing these techniques are associated with technical difficulties and usually low recovery factors. Steam Assisted Gravity Drainage (SAGD) is the most used commercial steam-based process being used in bitumen reservoirs, proposed by Butler more than 30 years ago [2,3,4]. The main idea of SAGD was to overcome the problems associated with the highly viscous bitumen by gravity drainages in steam chambers generated by displacement of heavy oil [5]. SAGD is not economic in cases where reservoirs are thin, because heat losses to confining strata become excessive compared to the resource. Another problem in SAGD is the cost involved for treating effluent water and the high energy requirements in order to have a continuous production of steam. On the other hand, huge quantities of heavy oil are trapped in tight but fractured carbonate reservoirs. Until recently, except for limited efforts in the applicability of steam injection at a field pilot scale, there was no method introduced to produce heavy oil from fractured carbonate reservoirs [6]. Considering the drawbacks of the conventional SAGD process, some modifications and even alternative recovery processes were proposed to enhance the overall performance of the SAGD process such as the use of solvent (noncondensable gas) along with the injected steam phase to reduce the amount of heat loss to the overburden and also low-pressure SAGD. Those techniques include miscible flooding (VAPEX) or modified versions of SAGD (ES-SAGD) through different configurations of wells or using additives to steam [7,8]. Although steam solvent process(SSP)is a highly promising technique, many uncertainties and unanswered questions still exist and they should be clarified for SSP to world wide applications. The boiling point of the solvent should be near that of steam. When it is to far from steam, it stays either liquid being produced without reacting with oil or gas stopping the heat exchange of steam. In this paper, PVT of some pure and commercial solvents is reviewed and potential operation pressure and temperature are discussed. This can help engineers to select solvent and design the process properly.
    01/2012;
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    ABSTRACT: Organ transplantation is a life-saving procedure for patients with organ failure. However, the side effects of long-term application of classic immunosuppressant remain major obstacles for successful transplantation. Therefore, new and safe immunosuppressive drugs against acute and chronic rejection are eagerly awaited. In the present study, we detected the effect of ginsenoside-Rd on mitogen-induced mouse spleen lymphocytes proliferation in vitro and observed the effect of ginsenoside-Rd on allograft rejection in a rat skin transplantation model. Th1/Th2 type cytokines secretion and T-cell subsets were also detected. The results showed that ginsenoside-Rd could markedly inhibit Concanavalin A (ConA)-induced mouse spleen T lymphocytes proliferation. Also, ginsenoside-Rd could significantly prolong the mean survival time of skin allograft and improve the skin allograft pathological damage. Furthermore, ginsenoside-Rd could markedly suppress alloantigen-specific production of Th1 cytokines IL-2 and IFN-γ as well as proinflammatory cytokines TNFα and IL-12. In parallel, Th2 cytokine IL-10 production in serum of rat recipients was markedly up-regulated. Ginsenoside-Rd at a dose of 25 mg/kg could significantly reduce the percentages of CD4(+) T cells and CD8(+) T cells in peripheral blood of rat recipients. Our results suggest that ginsenoside-Rd can effectively antagonize transplant rejection, which might qualify ginsenoside-Rd as a putative, therapeutic drug for the treatment of Th1-driven diseases, including transplant rejection.
    Journal of Surgical Research 07/2011; 176(1):267-74. · 2.02 Impact Factor
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    ABSTRACT: To elucidate the molecular mechanisms involved in the therapeutic effects of proanthocyanidins from grape seeds (GSPE), we explore whether GSPE regulates the inflammatory response of TNBS-induced colitis in rats at the levels of NF-κB signal transduction pathway. Rats were intragastrically administered of different doses of GSPE (100, 200 and 400 mg·kg-1) per day for seven days after ulcerative colitis (UC) was induced by intracolonic injection of 2,4,6-trinitrobenzenesulfonic acid (TNBS) dissolved in 50% ethanol. Sulfasalazine (SASP) at 400 mg/kg was used as a positive control drug. The expression of nuclear factor-kappa B (NF-κB), phospho-I kappaB-alpha (pIκBα), inhibitor kappa B kinase (IκK) in the colon tissues were all measured by enzyme-linked immunosorbent assay (ELISA) methods. Treatment with GSPE reduced the expression of NF-κB, pIκBα and IκK in the colon. The results of this study show that GSPE exerts beneficial effects in inflammatory bowel disease by inhibition of NF-κB signal transduction pathways.
    Molecules (Basel, Switzerland). 01/2011; 16(8):6721-31.