Search Results

You are looking at 1 - 10 of 33 items

  • Author: Jie Ding x
Clear All Modify Search

Abstract

Functional gradient biomaterials have been widely applied in the biomedical field due to their designable structure and performance. In this paper, hydroxyapatite-titanium particles hierarchical filled polyetheretherketone functional gradient biocomposites [(HA-Ti)/PEEK FGBm] were successfully fabricated through combination of a layer-by-layer casting method and hot pressing technology. The microstructure and morphology of the FGBm were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), energy dispersive X-ray analysis spectrometry (EDS) and scanning electron microscopy (SEM). The results of XRD and EDS verified that the components of the FGBm consist of HA, Ti and PEEK. FTIR and SEM studies showed that the existence of TiO2 thin film on the surface of Ti particles was beneficial to improve the wettability of Ti particles to the PEEK matrix, thus increasing the interfacial bonding strength between Ti particles and PEEK matrix. The SEM observation revealed that the size of HA particles in (HA-Ti)/PEEK FGBm was on the nano-scale and that of Ti particles was on the micron-scale. Furthermore, several typical microstructures such as micro-pores, dimple-like, and encapsulated-like morphologies in (HA-Ti)/PEEK FGBm were observed by SEM. With the rise of Ti and HA particle content in PEEK matrix, the distribution of them in PEEK matrix becomes more and more inhomogeneous and they tend to agglomerate.

Abstract

In order to drastically exploit the potential of the aero engine and improve acceleration performance in the combat state, an on-line optimized controller based on genetic algorithms is designed for an aero engine. For testing the validity of the presented control method, detailed joint simulation tests of the designed controller and the aero engine model are performed in the whole flight envelope. Simulation test results show that the presented control algorithm has characteristics of rapid convergence speed, high efficiency and can fully exploit the acceleration performance potential of the aero engine. Compared with the former controller, the designed on-line optimized controller (DOOC) can improve the security of the acceleration process and greatly enhance the aero engine thrust in the whole range of the flight envelope, the thrust increases an average of 8.1% in the randomly selected working states. The plane which adopts DOOC can acquire better fighting advantage in the combat state.

Abstract

This study focuses on on-line specific fuel consumption (SFC) optimization of aero engines. For solving this optimization problem, a nonlinear pneumatic and thermodynamics model of the aero engine is built and a hybrid optimization technique which is formed by combining the genetic algorithm (GA) and the sequential quadratic programming (SQP) is presented. The ability of standard GA and standard SQP in solving this type of problem is investigated. It has been found that, although the SQP is fast, very little SFC reductions can be obtained. The GA is able to solve the problem well but a lot of computational time is needed. The presented hybrid GA-SQP gives a good SFC optimization effect and saves 76.6% computational time when compared to the standard GA. It has been shown that the hybrid GA-SQP is a more effective and higher real-time method for SFC on-line optimization of the aero engine.

Abstract

C44H76CaO19S2, monoclinic, C2 (no. 5), a = 25.5446(14) Å, b = 7.38025(19) Å, c = 18.8450(10) Å, β = 136.543(10)°, Z = 2, V = 2443.6(4) Å3, R gt(F) = 0.0419, wR ref(F 2) = 0.1161, T = 293(2) K.

Abstract

During 2012, about 782,500 new liver cancer cases were diagnosed and 745,500 deaths occurred all around the world. Liver cancer is the 2nd major cause of cancer death in men around the world and in underdeveloped countries. Dysregulation of the balance between proliferation and cell death, hepatitis B virus infection and hepatitis C virus chronic infection, and carcinogenic micro RNAs mainly contribute to the development and progression of liver cancer. Under physiological status, Src maintained the foundation of cells. While in liver cancer, it is known that the basic activities of cells are apparently disturbed possibly by Src. The mechanisms underlying the development and progression of liver cancer is needed to elucidate. In this study, we summarized newly found regulation pathway of SRC signaling, and clinical experience with inhibitors of Src signaling, such as, novel molecules that directly or indirectly targeted Src signaling which can be utilized in the treatment of liver cancer.

Abstract

Nano-silica modified phenolic resin film is prepared using different mass fractions of nano-silica by liquid composites molding (LCM). The effects of nano-silica on the rheology and curing of phenolic resin are studied by rheometer and differential scanning calorimeter (DSC). The results show that the viscosity of nano-silica modified phenolic resin decreases with the increase of temperature, and the viscosity is lowest between 70°C and 90°C. The appropriate resin film infusion (RFI) process is investigated, and the stepped curing process system is established. In addition, the microstructures of modified phenolic film and composites are tested by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Nano-silica can be uniformly dispersed in phenolic resin when the amount of nano-silica added is ≤ 4%. And the mechanical properties of nano-silica modified phenolic composites are tested by universal material testing machine. The optimum nano-silica mass loading for the improvement of mechanical properties is found. This work provides an effective way to prepare the modified phenolic resin film suitable for resin film infusion (RFI) processes, and it maybe become a backbone of thermal protection material in aerospace.

Abstract

The aim of this study was to explore the effects of bone marrow mesenchymal stem cells (BMMSCs) and alendronate sodium (ALN) intervention on osteoporosis (OP). Sixty-eight 6-month-old healthy female Sprague Dawley (SD) rats were used to generate an OP model by removal of the ovaries. After 12 weeks, rats were treated with BMMSCs (BMMSC group) or ALN (ALN group) for 5 weeks. Serum type I collagen C terminal peptide (CTX_1), procollagen type I N-terminal propeptide (PINP), and bone alkaline phosphatase (BALP) were tested along with the femur bone density and other properties, including bone mineral density (BMD), BALP, percent trabecular area (BV/TV), trabecular thickness (Tb.Th), trabecular number (TbN), maximum load, maximum stress, maximum strain, and elastic modulus. BMD, BALP, BV/TV, Tb.Th, TbN, maximum load, maximum stress, maximum strain, and elastic modulus values were higher in the BMMSC group versus the ALN group relative to the control group (p < 0.05); CTX_1, PINP, trabecular separation (Tb.Sp), and osteoclast number (OC.N) were lowest in the BMMSC group versus the ALN group relative to the control group (p < 0.05). Both BMMSCs and ALN could improve the metabolic function and bone quality in osteoporotic mice while restoring the strength and toughness of bones. The intervention effects of BMMSCs are better than ALN in this model.

Abstract

C18H16N2O5, triclinic, P1̄ (no. 2), a = 8.716(1) Å, b = 9.969(1) Å, c = 11.435(2) Å, α = 104.535(3)°, β = 104.039(4)°, γ = 111.181(2)°, V = 833.5 Å3, Z = 2, Rgt(F) = 0.0446, wRref(F2) = 0.1276, T = 296 K.