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Transient voltage stability of power system with high penetration of renewable energy faces challenges. This paper proposes a method for quantitatively evaluating the impact of renewable energy penetration rate on transient voltage stability. Based on input-to-state stability (ISS) theory, security and stability indices are constructed to evaluate the stability characteristics, and a quantitative transient voltage stability assessment framework for power system with high penetration of renewable energy is established. Case studies are performed on MATLAB/Simulink, and security/stability indices under different renewable energy penetration rates are calculated. Finally, the critical scale of renewable energy integration is obtained through the coupling relationship between stability characteristics and renewable energy penetration rate.

In the 1980s, Zhejiang University of Technology (ZJUT) started developing a new catalyst for ammonia synthesis which in final form comprises multi-promoters wustite-based catalysts with Fe1-xO as precursor. This became the first new iron catalyst for ammonia synthesis commercialized since Fritz Haber’s promoted iron catalyst. The catalyst is commercialized in the existing or new low pressure process. In this paper, the basic theory, method, technology and practice of the wustite-based catalyst in industrial production and application are reviewed. The wustite-based catalysts are still iron-based, however, they are completely different from the magnetite-based catalyst in the preparation principle, chemical composition, crystal structure, and chemical-physical properties. Wustite does not exist in nature, and is a thermodynamically meta-stable phase. Therefore, the Fe1-xO must be firstly synthesized by a chemical method and avoid occurrence reactions of oxidation and disproportionation to obtain a commercial wustite-based catalyst with single phase and stability during the preparation of catalyst. We described the development of the catalyst, starting from the 1980s with studies to elucidate the inhibition mechanism of disproportionation reaction and the effects of temperature and promoters, and to ensure that a single wustite phase is obtained during preparation. This is a prerequisite for ensuring high activity of the catalyst. Scale up of catalyst production and testing were described briefly, as are some process considerations. Secondly, we described the industrial application of the catalyst with studies to elucidate including the industrial bypass testing, the foundation research on the industrial application technology such as industrial reduction technology due to too fast reduction rate, development of industrial technology taking out the excess reaction heat, optimization of reaction conditions using wustite-based catalyst, low-pressure ammonia process, and optimization of synthesis loop process and convertor for existing synthesis ammonia plant, etc. The wustite-based catalysts exhibit about 70 % higher catalytic activity, and 65.9 % higher the TOF. It is the most advanced commercial iron catalyst with the highest activity and low production cost in the world, and it is competitive with ruthenium-based ammonia synthesis catalysts. In industrial application, compared to the classic magnetite-based catalyst for ammonia synthesis, the higher activity allows lower operating temperatures and loop pressures. Existing loops can utilize it by running at minimum possible loop pressure for extended period of time. This allows to increase ammonia plant performance, efficiency and economy without the need of any revamping. New plants could be designed for lower pressure operation and with a smaller synthesis converter. This all together leads to lower capital expend tureen lower energy costs. The activation of this catalyst is fast and easy, which saves time and cost. Wustite-based catalyst is clearly a perfect low cost alternative to Ru/C catalyst.

Melt infiltration was used to prepare supported zinc oxide (ZnO) adsorbents for hydrogen sulfide (H2S) removal at room temperature, with three molecular sieves (MCM-41, SBA-15, and MCM-48) as carriers. The physical/chemical properties and the performance of these adsorbents were compared with those prepared by impregnation. Low- and wide-angle X-ray diffraction, nitrogen adsorption and transmission electron microscopy characterizations revealed that because precursor penetrated into the pores of carrier by capillary force, melt infiltration can yield more evenly dispersed ZnO in the pores of molecular sieve compared with the impregnation. Based on the breakthrough capacity, the best ZnO loading contents were 20 wt% on MCM-41 and SBA-15, and 30 wt% on MCM-48, and their corresponding utilization ration reached 69.8%, 52.2%, and 45.1%. With the same loading, the utilization ration of adsorbents prepared by impregnation was only 26.8%, 38.2% and 28.3%. Breakthrough tests and multiple adsorption/regeneration cycles showed that adsorbents with a large specific surface area, large pore size, and high strength were favorable. However, carrier with a small pore size and high strength could benefit much more from the melt infiltration.

Iron catalyst was fabricated via simple solid-state reaction of metal nitrates mixture (Fe, K, Al, Ca, Mg, Sm) with oxalic acid dihydrate at room temperature. Iron catalysts prepared by conventional methods, such as co-precipitation and fusing, are also included as comparison. The performances of catalysts were evaluated by the Fischer-Tropsch Synthesis (FTS) in a fixed bed reactor. The results indicate that uniform nanoparticles were obtained with surface area as high as 38.7 m2/g prepared by solid-state reaction. Following calcination at 500 °C, γ-Fe2O3 were obtained as the catalyst precursor. By contrast, α-Fe2O3 was the main precursor derived from co-precipitation. In addition, γ-Fe2O3 prepared by solid-state reaction facilitates the formation of active phase, Fe5C2 with the exposure of (021) facet. High Miller index surface (021) facilitates the adsorption and the dissociation of CO, which contributes the high activity and high selectivity to light olefins. Consequently, compared with conventional catalysts, solid-state reaction derived catalysts exhibit much higher FTO reaction activity and selectivity to lower olefins. The FTY value of 5.62 × 10 3 molCO gFe 1 s 1 was obtained which is almost two times higher than that of catalyst prepared by co-precipitation (3.19 × 10 3 molCO gFe 1 s 1) or 3 times higher than that of catalyst prepared by fusing method (1.98 × 10 3 molCO gFe 1 s 1). The selectivity to light olefins of around 40% is obtained which is significantly higher than that of the reference catalysts (25% and 33% respectively). The present study provides a promising pathway to prepare iron based catalysts at room temperature.

The influences of inlet contraction ratio on both the inlet and combustor of the rocket-based combined cycle engine are investigated in this paper by experimental and numerical approaches. A translating spike was employed to simulate the inlet counter pressure in the wind tunnel experiment. Steady-state pressure distributions were recorded and schlieren photos were obtained simultaneously. The combined numerical-experimental results show that the increased inlet contraction ratio always results in the increasing of the compression ratio and capability of anti-counter pressure, while its impact on the mass flow coefficient is negligible. Besides, the reactive numerical results show that the coefficients of inlet drag and combustor thrust increase with the increasing of the inlet contraction ratio, while the nozzle thrust coefficient demonstrates an opposite trend. These suggest that the selection of an appropriate inlet contraction ratio can effectively improve the total thrust coefficient of the engine, while the appropriate inlet contraction ratio is to be set to the minimum that satisfies the robust combustion requirement.

A series of Ni-doped ZnO/Al2O3 adsorbents with various compositions were fabricated through the sol–gel method. They were then tested dynamically in H2S removal from a gas stream containing H2S in moist N2. The adsorbents obtained were characterized using Scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption and desorption, Powder X-ray diffraction (XRD), CO2 temperature-programmed desorption (CO2-TPD), UV-Raman spectroscopy, photoluminescence (PL) spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. The dynamic tests for H2S removal showed that the sulfur capacity tended to gradually increase at first and then decrease with the increase in Ni2+ dopant content. XPS, PL and UV-Raman spectra results indicated that the concentrations of oxygen vacancies increased after doping Ni species. The increased breakthrough capacity was strongly related to the concentrations of oxygen vacancies. Oxygen vacancies played a dual role in removing H2S in the dynamic tests. They could efficiently promote H2S dissociation by providing high OH concentrations on the ZnO surface by acid–base interaction. Furthermore, oxygen vacancies could efficiently promote the counterdiffusion of HS− or S2− and O2− in the bulk of ZnO. This mechanism of anion diffusion in the ZnO lattice was supposed in this study.

Pancreatic lipase (PL), a crucial enzyme responsible for hydrolysis of dietary lipids, has been validated as a key therapeutic target to prevent and treat obesity-associated metabolic disorders. Herein, we report the design, synthesis and biological evaluation of a series of chalcone-like compounds as potent and reversible PL inhibitors. Following two rounds of structural modifications at both A and B rings of a chalcone-like skeleton, structure-PL inhibition relationships of the chalcone-like compounds were studied, while the key substituents that would be beneficial for PL inhibition were revealed. Among all tested chalcone-like compounds, compound B13 (a novel chalcone-like compound bearing two long carbon chains) displayed the most potent PL inhibition activity, with an IC50 value of 0.33 μM. Inhibition kinetic analyses demonstrated that B13 could potently inhibit PL-mediated 4-MUO hydrolysis in a mixed inhibition manner, with the Ki value of 0.12 μM. Molecular docking simulations suggested that B13 could tightly bind on PL at both the catalytic site and a non-catalytic site that was located on the surface of PL, which was consistent with the mixed inhibition mode of this agent. In addition, B13 displayed excellent stability in artificial gastrointestinal fluids and good metabolic stability in human liver preparations. Collectively, our findings suggested that chalcone-like compounds were good choices for design and development of orally administrated PL inhibitors, while B13 could be served as a promising lead compound to develop novel anti-obesity agents via targeting on PL.

Pancreatic lipase (PL) inhibitor therapy is one of the most effective ways to treat obesity and obesity-associated metabolic disorders. Herein, bioactivity and liquid chromatograph-mass spectrometer (LC-MS) guided fractionation strategy was used to identify the naturally occurring PL inhibitors in Styrax, a popular folk medicine in Asia and Turkey. The results clearly showed that five pentacyclic triterpenoid acids in Styrax displayed strong inhibition on PL, with IC50 values ranging from 0.49 µM to 6.35 µM. Further investigations demonstrated that oleanonic acid and betulonic acid (the most two potent PL inhibitors in Styrax) potently inhibited PL in a reversible and mixed inhibition manner, while molecular dynamics simulations showed that these two agents could stably bind at the entrance to the active site of PL. Collectively, our findings revealed the molecular basis for the anti-obesity effects of Styrax, while the newly identified PL inhibitors in this herb could be used for development of novel anti-obesity agents.

Hydrodynamics and bio-dynamics are equally important in upflow anaerobic sludge blanket (UASB) reactors, but few studies have been conducted to consider both issues when developing a mathematical model. Therefore a novel ADM1-based dispersive model was developed in this study to provide a better description of UASB reactor performance by simultaneously taking into account the hydrodynamics and bio-dynamics of the reactor. Organic overloading shock experiments were carried out in a laboratory-scale UASB reactor to validate the developed model. The results of the simulation model were in good agreement with experimental data. Although considerable calculation time was required, the ADM1-based dispersive model showed obvious advantages in predicting reactor status, which may give an early warning of reactor abnormalities. The models developed here are expected to simulate UASB reactors more effectively and to provide useful information for their design and operation.

This study examined the decolorization ability of Caldicellulosiruptor saccharolyticus isolated from a thermal spring at the optimum growth temperature of 70 °C. This study demonstrated, for the first time, C. saccharolyticus could effectively degrade methyl orange (MO) to 4-aminobenzenesulfonic acid (4-ABA) and N′,N-dimethyl-p-phenylenediamine (DPD) with dissolved hydrogen (DH) as the reducing equivalent. The decolorization reaction was catalyzed by Ni–Fe hydrogenase and the reaction rate was correlated positively to the concentration of DH. At high concentrations of DH the decolorization rates were 6.65 and 7.08 mg/L/h, which decreased to 2.16 and 0.88 mg/L/h after purging with N2. Furthermore, the addition of MO decreased the yield of ethanol via glucose fermentation owing to the limited reducing equivalents. We suggest the competition for hydrogen between the reduction of azo dyes and hydrogenotrophic methanogenesis processes might exist in mixed culture fermentation.

Low sulfur capacity and low regeneration performance are the long-time problems in the industrial application of ZnO-based adsorbents for ambient H2S removal. However, no efficient approach has been reported up to now to simultaneously solve these two problems. With the increasingly stringent environmental regulations in China, a robust but sustainable ZnO-based adsorbent is strongly desired. Herein, we constructed such an adsorbent for the first time by introducing cobalt species into ZnO/SiO2 to form a heterostructured ZnO-Co3O4/SiO2 nanocomposite. For comparison, Co doped ZnO/SiO2 and Zn doped Co3O4/SiO2 were also fabricated. According to the breakthrough tests with initial H2S partial pressure of 57 Pa, the heterostructured ZnO-Co3O4/SiO2 adsorbent exhibited highest sulfur capacity of 188.4 mg S/g sorbent at breakthrough level of 1%, the corresponded partition coefficient (at 0.57 Pa, 303 K) was 10.3 mol. kg−1. Pa−1. The introduced Co species not only improved the dispersion of ZnO nanograins, but also served as active sites for reacting and oxidizing H2S molecular. It also found that the formed ZnO-Co3O4 heterostructure could boost the hydroxylation of H2O, which provided an alkali environment for H2S dissociation. More meaningfully, this exhausted sorbent could be secondarily utilized as catalyst for carbonyl sulfide (COS) hydrogenation and exhibited 100% COS conversion even at a temperature lower than 200 °C, which was almost 3.3 times the conversion achieved by a commercial Co-Mo/Al2O3 catalyst (30%). This study will provide a new idea for rational design of metal oxide-based adsorbents to avoid causing secondary pollution by the spend adsorbents.

The fabrication and magnetic characteristics of Ni and Cu co-doped ZnO nanorods are reported. The Ni and Cu co-doped ZnO nanorods are synthesized by a facile hydrothermal method. Structural characterizations reveal that Ni and Cu ions enter into ZnO lattices without any secondary phases. SEM images show that they are regular nanorods. Magnetic measurements indicate that the obtained rod arrays exhibit room-temperature ferromagnetic behaviors. The exchange interaction between free delocalized carriers (holes from valence band) and the localized d spins of Ni and Cu ions is considered as the cause of the room-temperature ferromagnetism.