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  • Open Access

    ARTICLE

    Synthesis and Reinforcement of Thermostable Polymers Using Renewable Resources

    Nicole Segura Salas1, Felipe Orozco Gutiérrez3, Luis Daniel Mora Murillo2, Yendry Corrales Ureña3, Shakira Johnson1, José Vega Baudrit3, Rodolfo Jesús González-Paz3*

    Journal of Renewable Materials, Vol.5, No.3-4, pp. 313-322, 2017, DOI:10.7569/JRM.2017.634122

    Abstract Vegetable oils are being used for the production of biodegradable polymers, opening new possibilities for the synthesis of greener materials that could compete in national markets with petroleum-based polymers. In this study, castor oil and a catalyst (cobalt[II] naphtenate as promotor and MEKP as initiator) from local stores and styrene in different ratios were used to produce thermostable polymers. The kinetics of the polymerization reaction was followed by infrared spectroscopy. A polymeric material was synthetized which presents good mechanical properties. Therefore, composites were produced using 1 wt% of microcellulose extracted from biomass waste as reinforcement More >

  • Open Access

    ARTICLE

    Mixed Convection of Nanofluids inside a Lid-Driven Cavity Heated by a Central Square Heat Source

    Fatima-zohra Bensouici1, *, Saadoun Boudebous2

    FDMP-Fluid Dynamics & Materials Processing, Vol.13, No.3, pp. 189-212, 2017, DOI:10.3970/fdmp.2017.013.189

    Abstract A numerical work has been performed to analyze the laminar mixed convection of nanofluids confined in a lid driven square enclosure with a central square and isotherm heat source. All the walls are cooled at constant temperature, and the top wall slides rightward at constant velocity. The simulations considered four types of nanofluids (Cu, Ag, Al2O3 and TiO2)-Water. The governing equations were solved using finite volume approach by the SIMPLER algorithm. Comparisons with previously published work are performed and found to be in good agreement. The influence of pertinent parameters such as Richardson number, size of… More >

  • Open Access

    ARTICLE

    NUMERICAL STUDY OF FIN-TUBE TYPE HEAT EXCHANGER WITH DELTA WINGLETS

    Divyprakash C. Pal, Abhik Majumder*

    Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-9, 2016, DOI:10.5098/hmt.7.1

    Abstract In this present work heat transfer characteristics, thermal performance and pressure drop are studied numerically for a finned-tube bank heat exchanger with Delta Winglet Vortex Generator (DWVG) on the fin at different angle of attack (α). The thermo-fluid is studied by varying α at 15o , 25o , 30o and 35o . The base length (lDW) of the winglet also varied from 20mm to 35mm. The heat transfer coefficient and pressure drop increased in all the cases with increase in Reynolds number. However, significant increase in heat transfer of about 23.92% was observed for α More >

  • Open Access

    ARTICLE

    Enhancements to Modified Chebyshev-Picard Iteration Efficiency for Perturbed Orbit Propagation

    B. Macomber1, A. B. Probe1, R. Woollands1, J. Read1, J. L. Junkins1

    CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.1, pp. 29-64, 2016, DOI:10.3970/cmes.2016.111.029

    Abstract Modified Chebyshev Picard Iteration is an iterative numerical method for solving linear or non-linear ordinary differential equations. In a serial computational environment the method has been shown to compete with, or outperform, current state of practice numerical integrators. This paper presents several improvements to the basic method, designed to further increase the computational efficiency of solving the equations of perturbed orbit propagation. More >

  • Open Access

    ARTICLE

    Enhancement of Chemosensitivity by Stathmin-1 Silencing in Gastric Cancer Cells In Situ and In Vivo

    Zhi-jian Meng*, Ke Tao

    Oncology Research, Vol.23, No.1-2, pp. 35-41, 2015, DOI:10.3727/096504015X14452563486057

    Abstract Reports show that the stathmin gene may have a close relationship with tumor chemotherapeutic sensitivity. However, the effect of stathmin-1 on the chemosensitivity of gastric cancer to docetaxel has not been clearly determined. siRNA targeting stathmin-1 was introduced. The cell growth inhibition, expression of associated proteins, cell cycle, and apoptosis were evaluated by MTT, Western blot, and flow cytometric assays, respectively. The influence of silencing stathmin-1 was detected in situ and in vivo. SGC7901/docetaxel cells are the drug-resistant cells. After silencing stathmin-1, the resistance index (RI) reduced to 3.41, the expressions of STMN-1, MDR1, and More >

  • Open Access

    ARTICLE

    Enhancement of Drug Sensitivity by Knockdown of HIF-1α in Gastric Carcinoma Cells

    Qun Zhao, Bi-Bo Tan, Yong Li, Li-Qiao Fan, Pei-Gang Yang, Yuan Tian

    Oncology Research, Vol.23, No.3, pp. 129-136, 2015, DOI:10.3727/096504015X14500513118029

    Abstract In this study, the effects of hypoxia-inducible factor-1α (HIF-1α) on gastric carcinoma (GC) drug resistance through apoptosis-related genes are investigated. First, HIF-1α-specific siRNA was synthetized and transfected into drug-resistant GC cell line OCUM-2MD3/L-OHP. Then MTT assay was applied to test the inhibition rate of GC cells by 5-fluorouracil (5-FU) and oxaliplatin (L-OHP). After that, flow cytometry (FCM) was applied to measure apoptosis rate. qPCR and Western blot assay were employed to detect HIF-1α and apoptosis-related genes. Results showed that HIF-1α in OCUM-2MD3/L-OHP cells was higher than that in OCUM-2MD3 and gastric epithelial cells. After HIF-1α-siRNA More >

  • Open Access

    ARTICLE

    INFLUENCES OF THE PUNCHED DELTA WINGLET VORTEX GENERATORS IN A CIRCULAR TUBE HEAT EXCHANGER ON THERMO-HYDRAULIC PERFORMANCE

    Withada Jedsadaratanachaia, Amnart Boonloib,*

    Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-19, 2015, DOI:10.5098/hmt.6.13

    Abstract Numerical investigations on flow topology, heat transfer behavior and thermal performance evaluation in a circular tube heat exchanger with the punched delta winglet vortex generators (PDWVG) inserted in the middle of the test section are presented. The effects of the flow attack angles that converging to the center of the tube; α = 0°, 5°, 10°, 15°, 20°, 25°, and flow directions; winglet tips pointing downstream and upstream, are investigated for the Reynolds numbers; Re = 100 – 2000. The finite volume method and SIMPLE algorithm are used for the current study. The results are presented… More >

  • Open Access

    ARTICLE

    HEAT TRANSFER ENHANCEMENT OF HEAT EXCHANGER INSERTED TWISTED PLATES FOR CARBON DIOXIDE GAS

    Makoto Shibahara*

    Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-4, 2015, DOI:10.5098/hmt.6.9

    Abstract Overall heat transfer coefficients of the heat exchanger inserted twisted plates for CO2 were measured. The overall heat transfer coefficients increased with mass flow rates of water at the same Reynolds number in the experiment. It is considered that the helically twisting fluid motions in the twisted heat exchanger were contributed to the heat transfer enhancements. More >

  • Open Access

    ARTICLE

    Static and Dynamic Analysis of Laminated Thick and Thin Plates and Shells by a Very Simple Displacement-based 3-D Hexahedral Element with Over-Integration

    Qifeng Fan1, Yaping Zhang2, Leiting Dong1,3, Shu Li1, Satya N. Atluri4

    CMC-Computers, Materials & Continua, Vol.47, No.2, pp. 65-88, 2015, DOI:10.3970/cmc.2015.047.065

    Abstract A very simple displacement-based hexahedral 32-node element (denoted as DPH32), with over-integration in the thickness direction, is developed in this paper for static and dynamic analyses of laminated composite plates and shells. In contrast to higher-order or layer-wise higher-order plate and shell theories which are widely popularized in the current literature, the proposed method does not develop specific theories of plates and shells with postulated kinematic assumptions, but simply uses the theory of 3-D solid mechanics and the widely-available solid elements. Over-integration is used to evaluate the element stiffness matrices of laminated structures with an… More >

  • Open Access

    ARTICLE

    Analysis of Local Fracture Strain and Damage Limit of Advanced High Strength Steels using Measured Displacement Fields and FEM

    N. Ma1,2, K. Sato3, K. Takada4

    CMC-Computers, Materials & Continua, Vol.46, No.3, pp. 195-219, 2015, DOI:10.3970/cmc.2015.046.195

    Abstract The local mechanical behaviors of advanced high strength steels undergoing a very large strain from uniform plastic deformation to fracture were investigated with the aid of a measured displacement field and a measurement based FEM. As a measurement method, a digital image grid method (DIGM) was developed and the three-direction transient displacement field on uniaxial tensile test pieces was measured. Combining the measured transient displacement field with the finite element method, a measurement based FEM (M-FEM) was developed for the computation of distribution of the local strains, local stresses and ductile damage accumulation in a More >

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