Tianjin UniversityTianjin

Tianjin, China

Tianjin UniversityTianjin

Tianjin, China
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Qin Y.,Tianjin UniversityTianjin | Zhang X.,Tianjin UniversityTianjin | Wang Y.,Tianjin UniversityTianjin | Liu Y.,Tianjin UniversityTianjin
Sensors and Actuators, B: Chemical | Year: 2017

For gas sensor applications, a unique heterostructure array of W18O49/TiO2 core-shell nanowires with high alignment and uniform shell layer were fabricated by thermal oxidation of W film followed by sputter deposition and annealing of TiO2. The ordering of the rough aligned W18O49–core nanowires formed from thermal oxidation of metallic W film is found to be modulated considerably by the sputter deposition of shell layer. Thicker shell results in better alignment. The gas-sensing characteristics of the as-prepared W18O49/TiO2 nanowire sensor are evaluated at room temperature to 150 °C by measuring the dynamic response over NO2 concentration ranging from 0.5 to 5 ppm. The W18O49/TiO2 core-shell nanowires show temperature-dependent p-n response characteristic reversal. At room temperature, it behaves as an abnormal p-type semiconductor and exhibits good NO2-sensing performances including high sensitivity, good selectivity and excellent dynamic response-recovery characteristics. It is found that, with improved alignment, the heteronanowires array responses to sub-ppm level of NO2 with ultrafast response and recovery rate at room temperature. The measured response times are shorter than 5 s and the sensor can be recovered completely within 50s. The underlying gas-sensing mechanism correlated to the p-type response inversion at room temperature is analyzed in detail. © 2016 Elsevier B.V.

Shang Z.,Missouri University of Science and Technology | Li S.,Gas Technology Institute | Li L.,Tianjin UniversityTianjin | Liu G.,Tianjin UniversityTianjin | Liang X.,Missouri University of Science and Technology
Applied Catalysis B: Environmental | Year: 2017

A highly stable and extremely active nickel (Ni) nanoparticle catalyst, supported on porous γ-Al2O3 particles, was prepared by atomic layer deposition (ALD). The catalyst was employed to catalyze the reaction of dry reforming of methane (DRM). The catalyst initially gave a low conversion at 850 °C, but the conversion increased with an increase in reaction time, and stabilized at 93% (1730 L h−1 g Ni −1 at 850 °C). After regeneration, the catalyst showed a very high methane reforming rate (1840 L h−1 g Ni −1 at 850 °C). The activated catalyst showed exceptionally high catalytic activity and excellent stability of DRM reaction in over 300 h at temperatures that ranged from 700 °C to 850 °C. The excellent stability of the catalyst resulted from the formation of NiAl2O4 spinel. The high catalytic activity was due to the high dispersion of Ni nanoparticles deposited by ALD and the reduction of NiAl2O4 spinel to Ni during the DRM reaction at 850 °C. It was verified that NiAl2O4 can be reduced to Ni in a reductive gas mixture (i.e., carbon monoxide and hydrogen) during the reaction at 850 °C, but not by H2 alone. © 2016 Elsevier B.V.

Huang P.,Tianjin UniversityTianjin | Zhang Y.,Chinese Academy of Sciences | Wang W.,Chinese Academy of Sciences | Zhou J.,Tianjin UniversityTianjin | And 4 more authors.
Journal of Controlled Release | Year: 2015

Combined chemoradiotherapy is potent to defeat malignant tumor. Concurrent delivery of radioisotope with chemotherapeutic drugs, which also act as the radiosensitizer, to tumor tissues by a single vehicle is essential to achieve this objective. To this end, a macroscale injectable and thermosensitive micellar-hydrogel (MHg) depot was constructed by thermo-induced self-aggregation of poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone)-poly(ethyleneglycol)-poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (PECT) triblock copolymer micelles (Ms), which could not only serve as a micellar drug reservoir to locally deliver concentrated nano chemotherapeutic drugs, but also immobilize radioisotopes at the internal irradiation hot focus. Doxorubicin (DOX) and iodine-131 labeled hyaluronic acid (131I-HA) were used as the model therapeutic agents. The aqueous mixture of drug-loaded PECT micelles and 131I-HA exhibited sol-to-gel transition around body temperature. In vitro drug release study indicated that PECT/DOX Ms were sustainedly shed from the native PECT/DOX MHg formulation, which could be internalized by tumor cells with rapid intracellular DOX release. This hydrogel formulation demonstrated considerable in vitro antitumor effect as well as remarkable radiosensitization. In vivo subcutaneous injection of PECT MHg demonstrated that 131I isotope was immobilized stably at the injection location and no obvious indication of damage to major organs were observed as indicated by the histopathological analysis. Furthermore, the peritumoral injection of chemo-radiation therapeutic agents-encapsulated MHg formulation on tumor-bearing nude mice resulted in the desired combined treatment effect, which significantly improved the tumor growth inhibition efficiency with minimized drug-associated side effects to major organs. Consequently, such a thermosensitive MHg formulation, which enabled the precise control over the dosage and ratio of combination therapeutic agents to obtain the desired therapeutic effect with a single drug administration and reduced side effects, holds great potential for spatiotemporally delivery of multiple bioactive agents for sustained combination therapy. © 2015 Published by Elsevier B.V.

Krishna L.S.,Malaysia Japan International Institute of Technology | Yuzir A.,Malaysia Japan International Institute of Technology | Yuvaraja G.,Tianjin UniversityTianjin | Ashokkumar V.,University TeknologiJohor
International Journal of Phytoremediation | Year: 2017

The feasibility for the removal of Acid Blue25 (AB25) by Bengal gram fruit shell (BGFS), an agricultural by-product, has been investigated as an alternative for high-cost adsorbents. The impact of various experimental parameters such as dose, different dye concentration, solution pH, and temperature on the removal of Acid Blue25 (AB25) has been studied under the batch mode of operation. pH is a significant impact on the sorption of AB25 onto BGFS. The maximum removal of AB25 was achieved at a pH of 2 (83.84%). The optimum dose of biosorbent was selected as 200 mg for the removal of AB25 onto BGFS. Kinetic studies reveal that equilibrium reached within 180 minutes. Biosorption kinetics has been described by Lagergren equation and biosorption isotherms by classical Langmuir and Freundlich models. Equilibrium data were found to fit well with the Langmuir and Freundlich models, and the maximum monolayer biosorption capacity was 29.41 mg g−1 of AB25 onto BGFS. The kinetic studies indicated that the pseudo-second-order (PSO) model fitted the experimental data well. In addition, thermodynamic parameters have been calculated. The biosorption process was spontaneous and exothermic in nature with negative values of ΔG° (−1.6031 to −0.1089 kJ mol−1) and ΔH° (−16.7920 kJ mol−1). The negative ΔG° indicates the feasibility of physical biosorption process. The results indicate that BGFS could be used as an eco-friendly and cost-effective biosorbent for the removal of AB25 from aqueous solution. © 2017 Taylor & Francis Group, LLC.

Zhen X.,Tianjin University of Technology | Wang Y.,Tianjin UniversityTianjin
Renewable and Sustainable Energy Reviews | Year: 2015

Abstract Methanol is an alternative, renewable, environmentally and economically attractive fuel; it is considered to be one of the most favorable fuels for conventional fossil-based fuels. Methanol has been recently used as an alternative to conventional fuels for internal combustion (IC) engines in order to satisfy some environmental and economical concerns. Because of a number of relatively large research projects that have been ongoing recently, much progress has been made that is worth reporting. This paper systematically describes the methanol productions, including the productions from coal, natural gas, coke-oven gas, hydrogen, biomass etc. It introduces the potentials of methanol as a renewable resource taking into account the world supply and demand, economic benefits and the effects on human health and the environment. Thirteen methods of application such as methanol/gasoline, methanol/diesel blends which can be used on the IC engines are summarized. Finally, this paper puts forward some new suggestions on the weakness in the researches of methanol engine. © 2015 Elsevier Ltd.

Yang Z.,Tianjin UniversityTianjin | Lin J.,Tianjin UniversityTianjin | Wang Y.,Tianjin UniversityTianjin | Wang D.,Tianjin UniversityTianjin
Vacuum | Year: 2017

Al2O3 ceramic was successfully joined to TiAl alloy by active brazing using an Ag-Cu-Ti + W composite filler. The effects of brazing temperature, holding time, and W content on the microstructure and mechanical properties of the brazed joints were investigated. The typical interfacial structure of joints brazed at 880 °C for 10 min was: Al2O3/Ti3(Cu, Al)3O/W + Ag(s.s) + TiCu + dispersed AlCu2Ti/blocky AlCu2Ti + Ag(s.s)/AlCu2Ti layer + AlCuTi layer/TiAl alloy. By increasing the brazing temperature and holding time, the thickness of the Ti3(Cu, Al)3O reaction layer increased, and the blocky AlCu2Ti amount in the middle of the brazing seam aggregated and grew gradually. W particles added in the brazing seam could decrease the mismatch of coefficients of thermal expansion between the Al2O3 ceramic and brazing seam, thus relieving the residual stresses yielded in the ceramic substrate and improving the joint strength. The maximum shear strength reached 148 MPa when the joints were brazed with Ag-Cu-Ti + 20 wt. % W composite filler at 880 °C for 10 min. However, excessive W particles resulted in defects such as microcracks and micropores in the joint, leading to a reduction in shear strength. © 2017 Elsevier Ltd

Xu G.,Tianjin UniversityTianjin | Wang X.,Tianjin UniversityTianjin | Xu S.,Tianjin UniversityTianjin | Wang J.,Tianjin UniversityTianjin
Engineering Analysis with Boundary Elements | Year: 2017

The oriented shift and inverse of double-emulsion globules containing two inner droplets with different sizes and locations in modest extensional flows are investigated numerically in this paper through a boundary element method. The asymmetric layout of daughter droplets leads to the asymmetric inner flow field and pressure field inside the globule, which causes its asymmetric rheological behaviors. The direction of shift is determined not only by the size ratio rR 2/rL 2 and the location ratio dR/dL of two inner droplets, but also by some flow factors such as the capillary number Ca. There is a critical capillary number Cac as a function of rR 2/rL 2 and dR/dL, beyond which the globule will move to the right, otherwise, it will shift to the opposite direction. © 2017 Elsevier Ltd

Liu M.,Tianjin UniversityTianjin | Liu H.,Tianjin UniversityTianjin | Liu H.,Shanghai JiaoTong University | Zhang R.,Tianjin UniversityTianjin
Ocean Engineering | Year: 2015

Abstract Solid particle erosion in pipelines is a severe problem involved in hydrocarbon transportation and hence an important topic in flow assurance. A simplified CFD-based procedure is proposed to calculate the penetration rates in elbows for annular flow. This new method overcomes the disadvantages of current empirical or semi-empirical models. The procedure consists of three main sections: flow modeling, particle tracking, and penetration calculation. The k-ε model is employed to analyze the flow field in the core area of the pipe based on the assumption that the gas-liquid interface is regarded as an actual pipe wall. Then a Lagrangian method is adopted to track trajectories of the entrained droplets and sand particles in the core area, and the velocity decay of sand particles across the liquid film is calculated combined with the film thickness correlation. Based on the knowledge of the flow field and the particle motion, penetration rates are calculated by introducing the solid particle erosion equation. By comparing with experimental data available from the literature, the new method is proved to be reasonable in simplifying the simulation of annular flow field and shows good accuracy in erosion prediction. A better agreement between predicted erosion rates and experimental data can be made when applied to larger curvature radius elbows. © 2015 Elsevier Ltd.

Zhu N.,Tianjin UniversityTianjin | Wang J.,Tianjin UniversityTianjin | Liu L.,Tianjin UniversityTianjin
Energy Conversion and Management | Year: 2015

Abstract The COP (Coefficient of Performance) of the ground-source heat pump (GSHP) system decreased gradually year after year mainly caused by imbalance of thermal energy inputting, especially in heating-dominated climate zones. An experimental system of solar seasonal storage coupling with ground-source heat pump was designed and implemented. This system was installed in a group of new buildings of the new campus in Tianjin, China, which is located in cold climate zone and heat demand is dominated. To make evaluation to this system, a mathematical method was developed to calculate the COP of GSHP system and the coupled system. In this thermal storage experiment process, a system with 1500 m2 solar thermal collectors and 580 sets of 120 m deep ground thermal exchangers was involved in this research. Results show that the soil temperature has not descended but increased by 0.21°C, and the COP of system and heat pump unit increased 3.4% and 2.4% respectively compared to the operation data without solar seasonal storage process during last year. Although the effectiveness of solar seasonal storage coupled is not conspicuous as expected during the testing period, it indicates that the tendency of COP declination is prevented, and further illustrating that improving the COP of the system is a long-term work, the application of solar seasonal storage coupled with GSHP system should be encouraged for long-term operation. © 2015 Elsevier Ltd.

Wang Z.,Tianjin UniversityTianjin | Huachen Z.,Tianjin UniversityTianjin | Liu H.,Tianjin UniversityTianjin | Bu Y.,Imperial College London
Ocean Engineering | Year: 2015

Abstract Upheaval buckling is one of the most common problems threatening the safe operation of subsea pipelines, which is trigged by the increasing of temperature and inner pressure. In order to predict the critical buckling temperature and post buckling path of upheaval buckling, ABAQUS is used to build four kinds of numerical models, and they are static and dynamic models both in 2D and 3D. Two analysis procedures which combine the static and dynamic processes are applied to aforementioned models. The results show good agreement with existing test data. For snap upheaval buckling, pipelines have two different buckling modes. Such buckling modes are not found in experiments. In addition, only 3D dynamic model can catch such buckling modes. For bifurcation upheaval buckling, predicted buckling temperatures of those models are all acceptable with an error of 5%. © 2015 Elsevier Ltd.

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