ZrO₂/PMMA nanocomposite particles are synthesized through an in-situ free radical emulsion polymerization based on the silane coupling agent (Z-6030) modified ZrO₂ nanoparticles, and the morphology, size and its distribution of nanocomposite particles are investigated. Scanning electron microscopy (SEM) images demonstrate that the methyl methacrylate (MMA) feeding rate has a significant effect on the particle size and morphology. When the MMA feeding rate decreases from 0.42 ml·min^-1 to 0.08 ml·min^-1, large particles (about 200-550 nm) will not form, and the size distribution become narrow (36-54 nm). The average nanocomposite particles size increases from 34 nm to 55 nm, as the MMA/ZrO₂ nanoparticles mass ratio increased from 4︰1 to 16︰1. Regular spherical ZrO₂/PMMA nanocomposite particles are synthesized when the emulsifier OP-10 concentration is 2 mg·ml^-1. The nanocomposite particles could be mixed with VAc-VeoVa10 polymer matrix just by magnetic stirring to prepare the ZrO₂/PMMA/VAc-VeoVa10 hybrid coatings. SEM and atomic force microscopy (AFM) photos reveal that the distribution of the ZrO₂/PMMA nanocomposite particles in the VAc-VeoVa10 polymer matrix is homogenous and stable. Here, the grafted-PMMA polymer on ZrO₂ nanoparticles plays as a bridge which effectively connects the ZrO₂ nanoparticles and the VAc-VeoVa10 polymer matrix with improved comparability. In consequence, the hybrid coating with good dispersion stability is obtained.

Nanosized calcium carbonate particles were prepared with a continuous gas-liquid membrane contactor. The effects of Ca(OH)₂ concentration, CO₂ pressure and liquid flow velocity on the particles morphology, pressure drop and membrane fouling were studied. With rising Ca(OH)₂ concentrations, the average size of the particles increased. The effects of Ca(OH)₂ concentration and CO₂ pressure on particles were not apparent under the experimental conditions. When the Ca(OH)₂ concentration and liquid flow velocity were high, or the CO₂ pressure was low, the fouling on the membrane external surface at the contactor entrance was serious due to liquid leakage, whereas the fouling was slight at exit. The fouling on the membrane inner-surface at entrance was apparent due to adsorption of raw materials. The membrane can be recovered by washing with dilute hydrochloric acid and reused for at least 6 times without performance deterioration.

Chemical-looping gasification (CLG) is a novel process for syngas generation from solid fuels, sharing the same basic principles as chemical-looping combustion (CLC). It also uses oxygen carriers (mainly metal oxide and calcium sulfate) to transfer heat and oxygen to the fuel. In this paper, the primary investigation into the CLG process with CaSO₄ as oxygen carrier was carried out by thermodynamic analysis and experiments in the tube reactor. Sulfur-contained gas emission was mainly H₂S rather than SO₂ in the CLG process, showing some different features from the CLC. The mass and heat balance of CLG processes were calculated thermodynamically to determinate the auto-thermal operating conditions with different CaSO₄/C and steam/C molar ratios. It was found that the CaSO₄/C molar ratio should be higher than 0.2 to reach auto-thermal balance. The effect of temperature on the reactions between oxygen carrier and coal was investigated based on Gibbs free energy minimum method and experimental results. It indicated that high temperature favored the CLG process in the fuel reactor and part of syngas was consumed to compensate for auto-thermal system.

The physical absorption of CO₂ in water containing different types of particles was studied in a microchannel operated under Taylor flow. The maximum enhancement factors of 1.43-2.15 were measured for activated carbon (AcC) particles. The analysis shows that the enhancement effect can be attributed to the shuttle mechanism. Considering the separate contributions of mass transfer from bubble cap and liquid film, a heterogeneous enhancement model is developed. According to this model, the enhancement factors E_Cap, E_Film and E_Ov are mainly determined by mass transfer coefficient K_L (K_L,Cap and K_L,Film), adsorptive capacity of particles m, and coverage fraction of particles at gas-liquid interface ζ. With both effects of particle-to-interface adhesion and apparent viscosity included, the model predicts the enhancement effect of AcC particles reasonably well.

The solutions of dynamic optimization problems are usually very difficult due to their highly nonlinear and multidimensional nature. Genetic algorithm (GA) has been proved to be a feasible method when the gradient is difficult to calculate. Its advantage is that the control profiles at all time stages are optimized simultaneously, but its convergence is very slow in the later period of evolution and it is easily trapped in the local optimum. In this study, a hybrid improved genetic algorithm (HIGA) for solving dynamic optimization problems is proposed to overcome these defects. Simplex method (SM) is used to perform the local search in the neighborhood of the optimal solution. By using SM, the ideal searching direction of global optimal solution could be found as soon as possible and the convergence speed of the algorithm is improved. The hybrid algorithm presents some improvements, such as protecting the best individual, accepting immigrations, as well as employing adaptive crossover and Gaussian mutation operators. The efficiency of the proposed algorithm is demonstrated by solving several dynamic optimization problems. At last, HIGA is applied to the optimal production of secreted protein in a fed batch reactor and the optimal feed-rate found by HIGA is effective and relatively stable.

Determination of the optimal model parameters for biochemical systems is a time consuming iterative process. In this study, a novel hybrid differential evolution (DE) algorithm based on the differential evolution technique and a local search strategy is developed for solving kinetic parameter estimation problems. By combining the merits of DE with Gauss-Newton method, the proposed hybrid approach employs a DE algorithm for identifying promising regions of the solution space followed by use of Gauss-Newton method to determine the optimum in the identified regions. Some well-known benchmark estimation problems are utilized to test the efficiency and the robustness of the proposed algorithm compared to other methods in literature. The comparison indicates that the present hybrid algorithm outperforms other estimation techniques in terms of the global searching ability and the convergence speed. Additionally, the estimation of kinetic model parameters for a feed batch fermentor is carried out to test the applicability of the proposed algorithm. The result suggests that the method can be used to estimate suitable values of model parameters for a complex mathematical model.

Locality preserving projection (LPP) is a newly emerging fault detection method which can discover local manifold structure of a data set to be analyzed, but its linear assumption may lead to monitoring performance degradation for complicated nonlinear industrial processes. In this paper, an improved LPP method, referred to as sparse kernel locality preserving projection (SKLPP) is proposed for nonlinear process fault detection. Based on the LPP model, kernel trick is applied to construct nonlinear kernel model. Furthermore, for reducing the computational complexity of kernel model, feature samples selection technique is adopted to make the kernel LPP model sparse. Lastly, two monitoring statistics of SKLPP model are built to detect process faults. Simulations on a continuous stirred tank reactor (CSTR) system show that SKLPP is more effective than LPP in terms of fault detection performance.

The vapor-liquid equilibrium data of four binary systems (acetic acid+p-xylene, methyl acetate+n-propyl acetate, n-propyl acetate+p-xylene and methyl acetate+p-xylene) are measured at 101.33 kPa with Ellis equilibrium still, and then both the NRTL and UNIQUAC models are used in combination with the HOC model for correlating and estimating the vapor-liquid equilibrium of these four binary systems. The estimated binary VLE results using correlated parameters agree well with the measured data except the methyl acetate+p-xylene system which easily causes bumping and liquid rushing out of the sampling tap due to their dramatically different boiling points. The correlation results by NRTL and UNIQUAC models have little difference on the average absolute deviations of temperature and composition of vapor phase, and the results by NRTL model are slightly better than those by UNIQUAC model except for the methyl acetate+n-propyl acetate system, for which the latter gives more accurate correlations.

On the basis of energy conservation law and surface pressure isotherm, the conformation energy changes of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) in pure phospholipid monolayer at the air/water interface during compression are derived. The optimized conformations of phospholipids at absolute freedom state are simulated by Gaussian 98 software. Based on following assumptions: (1) the conformation energy change is mainly caused by the rotation of one special bond; (2) the atoms of glycerol near the water surface are active; (3) the rotation is motivated by hydrogen-bond action; (4) the rotation of bond is inertial, one simplified track of conformational change is suggested and the conformations of DPPC and DPPG at different states are determined by the plots of conformation energy change vs. dihedral angle. The thickness of the simulated phospholipid monolayer is consistent with published experimental result. According to molecular areas at different states, the molecular orientations in the compressing process are also developed.

Disulfide bond formation protein A (DsbA) is one of the important helper proteins for folding in protein synthesis in vivo. In this study, purification of recombinant DsbA was investigated by examining four important factors with Box-Behnken design method, a statistic-based design of experiments. The optimal operation conditions were obtained by adopting the effectiveness coefficient method on the multi-objective problem, which takes the protein recovery, purification efficiency and throughput of ion-exchange chromatography into account. After the optimization, protein recovery of 96.8% and purity higher than 95% DsbA was achieved, and the productivity was (377.9?1.7) mg soluble DsbA per liter broth. The purified protein was identified by peptide mass fingerprinting matching the record of gi|2624856, a mutant of DsbA. The DsbA was preliminarily applied to the refolding of denatured lysozyme in vitro.

A novel modified pilot scale anaerobic oxidation ditch with additional internal anoxic zones was operated experimentally, aiming to study the improvement of biological nitrogen and phosphorus removal and the effect of enhanced denitrifying phosphorus removal in the process. Under all experimental conditions, the anaerobic-oxidation ditch with additional internal anoxic zones and an internal recycle ratio of 200% had the highest nutrient removal efficiency. The effluent NH₄⁺-N, total nitrogen (TN), PO₄^3--P and total phosphorus (TP) contents were 1.2 mg·^-1, 13 mg·^-1, 0.3 mg·^-1 and 0.4 mg·^-1, respectively, all met the discharge standards in China. The TN and TP removal efficiencies were remarkably improved from 37% and 50% to 65% and 88% with the presence of additional internal anoxic zones and internal recycle ratio of 200%. The results indicated that additional internal anoxic zones can optimize the utilization of available carbon source from the anaerobic outflow for denitrification. It was also found that phosphorus removal via the denitrification process was stimulated in the additional internal anoxic zones, which was beneficial for biological nitrogen and phosphorus removal when treating wastewater with a limited carbon source. However, an excess internal recycle would cause nitrite to accumulate in the system. This seems to be harmful to biological phosphorus removal.

Four kinds of Ca-based sorbents were prepared by calcination and hydration reactions using different precursors: calcium hydroxide, calcium carbonate, calcium acetate monohydrate and calcium oxide. The CO₂ absorption capacity of those sorbents was investigated in a fixed-bed reactor in the temperature range of 350-650 ℃. It was found that all of those sorbents showed higher capacity for CO₂ absorption when the operating temperature higher than 450 ℃. The CaAc₂-CaO sorbent showed the highest CO₂ absorption capacity of 299 mg·g^-1. The morphology of those sorbents was examined by scanning electron microscope (SEM), and the changes of composition before and after carbonation were also determined by X-ray diffraction (XRD). Results indicated that those sorbents have the similar chemical compositions and crystalline phases before carbonation reaction [mainly Ca(OH)₂], and CaCO₃ is the main component after carbonation reaction. The SEM morphology shows clearly that the sorbent pores were filled with reaction products after carbonation reaction, and became much denser than before. The N₂ adsorption-desorption isotherms indicated that the CaAc₂-CaO and CaCO₃-CaO sorbents have higher specific surface area, larger pore volume and appropriate pore size distribution than that of CaO-CaO and Ca(OH)₂-CaO.

Heterogeneous catalysts with ultrafine or nano particle size have currently attracted considerable attentions in the chemical and petrochemical production processes, but their large-scale applications remain challenging because of difficulties associated with their efficient separation from the reaction slurry. A porous ceramic membrane reactor has emerged as a promising method to solve the problem concerning catalysts separation in situ from the reaction mixture and make the production process continuous in heterogeneous catalysis. This article presents a review of the present progress on porous ceramic membrane reactors for heterogeneous catalysis, which covers classification of configurations of porous ceramic membrane reactor, major considerations and some important industrial applications. A special emphasis is paid to major considerations in term of application-oriented ceramic membrane design, optimization of ceramic membrane reactor performance and membrane fouling mechanism. Finally, brief concluding remarks on porous ceramic membrane reactors are given and possible future research interests are also outlined.

The methylotrophic yeast Pichia pastoris is a highly successful system for production of a variety of heterologous proteins due to its unique features/abilities for effective protein expression, and tremendous efforts have been made to increase heterologous protein productivity by P. pastoris in recent years. When new engineered yeast strains are constructed and are ready to use for industrial protein production, process control and optimization techniques should be applied to improve the fermentation performance in the following aspects: (1) increase recombinant cell concentrations in fermentor to high density during growth phase; (2) effectively induce heterologous proteins by enhancing/stabilizing titers or concentrations of the proteins during induction phase; (3) decrease operation costs by relieving the working loads of heat-exchange and oxygen supply. This article reviews and discusses the key and commonly used techniques in heterologous protein production by P. pastoris, with the focus on optimizations of fermentation media and basic operation conditions, development of optimal glycerol feeding strategies for achieving high density cultivation of P. pastoris and effective heterologous protein induction methods by regulating specific growth rate, methanol concentration, temperatures, mixture ratio of multi-carbon substrates, etc. Metabolic analysis for recombinant protein production by P. pastoris is also introduced to interpret the mechanism of sub-optimal heterologous protein production and to explore further optimal expression methods.