Graphene oxide–bacterial cellulose (GO/BC) nanocomposite hydrogels with well‐dispersed GO in the network of BC are successfully developed using a facile one‐step in situ biosynthesis by adding GO ...suspension into the culture medium of BC. During the biosynthesis process, the crystallinity index of BC decreases and GO is partially reduced. The experimental results indicate that GO nanosheets are uniformly dispersed and well‐bound to the BC matrix and that the 3D porous structure of BC is sustained. This is responsible for efficient load transfer between the GO reinforcement and BC matrix. Compared with the pure BC, the tensile strength and Young's modulus of the GO/BC nanocomposite hydrogel containing 0.48 wt% GO are significantly improved by about 38 and 120%, respectively. The GO/BC nanocomposite hydrogels are promising as a new material for tissue engineering scaffolds.
Graphene oxide–bacterial cellulose (GO/BC) nanocomposite hydrogels with well‐dispersed GO in the network of BC have been successfully developed using a facile one‐step in situ biosynthesis by adding GO suspension into the culture medium of BC. The composites show a significant increase in tensile properties at relatively low GO loadings.
The differential evolution (DE) intelligent algorithm is used for a state-space model identification for an Extra-atmospheric vehicle, the DE method has advantage of choosing initial point randomly. ...The greatest common right divisor (GCRD) method is used to choose the weighting matrix in loop shaping, which the stability margin is larger as well as a greater bandwidth of the control system. A modified augmented proportional navigation (MAPN) guidance law is proposed for the extra-atmospheric vehicle by using the adaptive extended Kalman filtering(AEKF) observer to estimate the target maneuver acceleration. It shows that the new guidance law provides significant performance improvements over the commonly used classical proportional navigation law, and the simulation results prove that the system achieves a top level control performance.
•3D mesoporous bioglass (MBG) nanofibrous scaffold was doped with Cu.•The Cu-doped scaffold shows large specific surface area and 3D network structure.•Cu-doping does not signifcantly affect ...bioactivity and biocompatibility of MBG scaffold.•Cu-doped MBG shows excellent antibacterial activity against S. aureus and E. coli.
A multifunctional bioactive material with osteogenic and antibacterial performance is of crucial importance for the repair of large bone defects. Herein, three-dimensional (3D) mesoporous bioactive glass (MBG) nanofibrous scaffolds doped with copper (Cu) were synthesized via a one-pot template-assisted sol-gel method followed by calcination. The morphology, structure, pore structure, in vitro bioactivity, cell biocompatibility, and antibacterial activity of the as-prepared 3D Cu-doped MBG nanofibrous scaffolds with varying amounts of doped Cu were characterized and compared. The results demonstrate that, besides large specific surface areas and a well-defined three-dimensional (3D) network structure, the as-prepared scaffolds exhibit good in vitro bioactivity and biocompatibility and excellent antibacterial activity against gram-positive Staphylococcus aureus and gram-negative Escherichia coli. It is believed that the 3D Cu-doped MBG nanofibrous scaffolds show potential application in preventing infections.
Graphene has been widely used to reinforce various hydrogels while there is no report on the composite hydrogels of bacterial cellulose (BC) and graphene. In this work, a graphene/BC (GE/BC) ...nanocomposite hydrogel was prepared by in situ biosynthesis. The morphology and structure of the obtained GE/BC nanocomposite were characterized by SEM, TEM, XRD, and Raman. Results showed that the presence of graphene in the culture medium of BC changed the crystalline structure of BC while the in situ biosynthesis process had no influence on the structure of graphene. It was found that graphene nanoplates were uniformly dispersed in the three-dimensional (3D) BC matrix and tightly bound by BC nanofibers. This unique 3D structure will impart the GE/BC nanocomposite with excellent mechanical, electrical, and biological properties.
Graphene has been widely used to reinforce various hydrogels while there is no report on the composite hydrogels of bacterial cellulose (BC) and graphene. In this work, a graphene/BC (GE/BC) ...nanocomposite hydrogel was prepared by in situbiosynthesis. The morphology and structure of the obtained GE/BC nanocomposite were characterized by SEM, TEM, XRD, and Raman. Results showed that the presence of graphene in the culture medium of BC changed the crystalline structure of BC while the in situbiosynthesis process had no influence on the structure of graphene. It was found that graphene nanoplates were uniformly dispersed in the three-dimensional (3D) BC matrix and tightly bound by BC nanofibers. This unique 3D structure will impart the GE/BC nanocomposite with excellent mechanical, electrical, and biological properties.
In contrast to a traditional coal-fired power generation plant where steam extracted from a turbine is used to preheat the feed- water in all preheating stages, a solar-aided power generation （SAPG） ...plant uses solar heat to replace a part or all of the ex- tracted steam in one or more preheating stages. The performance of an SAPG plant with different replacements is investigated in this study by using specific consumption theory （SCT）. Fuel-specific and cost-specific consumption models for SAPG plants are built based on the SCT. A typical 330 MW coal-fired power plant is used as the study case. The performance of the SAPG plant in terms of specific consumption, with steam obtained from the first through the eighth （except for the fourth） stages of extraction replaced by solar heat, is compared with that of the reference coal-fired power plant. The fuel-specific consumption of the SAPG plant is determined to be lower than that of the reference coal-fired power plant. The fuel-specific consumption accrual distribution in SAPG plants is used to assess the effect of each individual replacement. Effective strategies to reduce the specific costs of the SAPG and coal-fired power plants are proposed based on the results of this study.
•A coupling analysis about solar aided power generation (SAPG) system is made.•The off-design performances of turbine and boiler are considered in SAPG system.•Matrix Thermal Balance Equation is used ...in SAPG system models.
Integrating solar energy into conventional fossil-fuel fired power plant has been proven to be an efficient way to use solar energy for power generation purpose. In a solar-aided power generation (SAPG) system without storage system, owing to the instability of solar radiation, the turbine and the boiler work under off-design conditions most of time. In this paper, a modified simulation model is established to analyze the off-design performance of SAPG system. In order to speed up the calculations of the model, improved Matrix Thermal Balance Equation (MTBE) approach is used. A solar-aided feedwater heating of a 330MW coal-fired power generation unit in fuel-saving operation mode is discussed as a case study. The results show that, in a SAPG system, when HP extraction steam is partly replaced, with the increasing solar energy being introduced, the temperature of exhaust flue gas decreases; boiler efficiency improves and standard coal consumption rate decreases. With more solar heat introduced the temperature of superheated and reheated steam keep constant at first and then decrease rapidly. However, in real project, the temperature drop should be no more the permissible limits, which should be considered. The results obtained in the current study could provide a promising approach to find the balance between coal saving and safe operation of the SAPG system.
Cu-based friction materials have better tribological properties, high mechanical strength, and excellent thermal conductivity; therefore, they are widely used as friction materials in high-speed rail ...brake systems. However, with the remarkable increase in running speed of high-speed trains, a great amount of energy and high temperature are induced in the brake system; therefore, new challenges are generated for brake pad materials. In this paper, Cu-based friction materials were prepared with the addition of various hard particles as the friction phase, in order to obtain a good high temperature tribological performance. The experimental results showed that the Cu-based friction materials with addition of hard particles have moderate mechanical strengths and proper tribological properties. The temperature effects on the tribological behaviors of friction materials were investigated. The coefficient of friction (COF) for friction materials with addition of hard particles increased with temperature, resulting from the integrated effects of friction film, graphite, and material softening. The variation trends of the wear loss and wear rate with temperatures are similar to those of COFs, which are significantly reduced with the addition of hard particles.
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