Scientific interest in carbon‐based materials (CBMs) has grown dramatically over the past few decades. Due to a variety of atomic orbital hybrid forms (sp, sp2 and sp3 hybridization), carbon can form ...a variety of materials with diverse structures and characteristics. CBMs used as efficient catalyst supports show extensive promise in organic reactions, which is attributed to their structural similarity with organics, large specific surface area, chemical stability, and photocatalytic properties. This review presents the synthesis of CBM‐supported palladium nanocatalysts based on impregnation, template methods, etc. The CBMs include activated carbon (AC), graphene, carbon nanotubes (CNTs), and their functionalized products, as supports for improving the activity and recyclability of simple Pd nanocatalysts. After surveying the literature where these catalysts have been utilized for carbon–carbon coupling reactions, there is a particular emphasis on Suzuki, Heck, and Sonogashira reactions. The catalytic mechanism of these Pd nanocatalysts (surface heterogeneous catalysis or homogeneous catalysis caused by Pd leaching) is discussed in detail, especially the effect of Pd leaching on the stability of the catalyst.
This review presents thesynthesis of carbon‐based materials (CBMs) supported palladium nanocatalysts based on impregnation, template methods, etc. After surveying the literature where these catalysts have been utilized for carbon‐carbon coupling reactions, there is a particular emphasis on Suzuki, Heck, and Sonogashira reactions. The catalytic mechanism ofthese Pd nanocatalysts (surface heterogeneous catalysis or homogeneous catalysis caused by Pd leaching) is discussed in detail, especially the effect of Pd leaching on the stability of the catalyst.
In recent years, the study of oxidative stress (OS) has become increasingly popular. In particular, the role of OS on female fertility is very important and has been focused on closely. The ...occurrence of OS is due to the excessive production of reactive oxygen species (ROS). ROS are a double-edged sword; they not only play an important role as secondary messengers in many intracellular signaling cascades, but they also exert indispensable effects on pathological processes involving the female genital tract. ROS and antioxidants join in the regulation of reproductive processes in both animals and humans. Imbalances between pro-oxidants and antioxidants could lead to a number of female reproductive diseases. This review focuses on the mechanism of OS and a series of female reproductive processes, explaining the role of OS in female reproduction and female reproductive diseases caused by OS, including polycystic ovary syndrome (PCOS), endometriosis, preeclampsia and so on. Many signaling pathways involved in female reproduction, including the Keap1-Nrf2, NF-κB, FOXO and MAPK pathways, which are affected by OS, are described, providing new ideas for the mechanism of reproductive diseases.
COVID-19 is associated with 5.1% mortality. Although the virological, epidemiological, clinical, and management outcome features of COVID-19 patients have been defined rapidly, the inflammatory and ...immune profiles require definition as they influence pathogenesis and clinical expression of COVID-19. Here we show lymphopenia, selective loss of CD4+ T cells, CD8+ T cells and NK cells, excessive T-cell activation and high expression of T-cell inhibitory molecules are more prominent in severe cases than in those with mild disease. CD8+ T cells in patients with severe disease express high levels of cytotoxic molecules. Histochemical studies of lung tissue from one fatality show sub-anatomical distributions of SARS-CoV-2 RNA and massive infiltration of T cells and macrophages. Thus, aberrant activation and dysregulation of CD8+ T cells occur in patients with severe COVID-19 disease, an effect that might be for pathogenesis of SARS-CoV-2 infection and indicate that immune-based targets for therapeutic interventions constitute a promising treatment for severe COVID-19 patients.
Multiple comparison procedures Cao, Jing; Zhang, Song
JAMA : the journal of the American Medical Association,
08/2014, Volume:
312, Issue:
5
Journal Article
Biomass gasification converts into syngas, then into other chemicals via Fischer-Tropsch (F-T) synthesis is promising for renewable energy utilization. Although gasification is a sustainable and ...environmental-friendly technology for value-added utilization of biomass, tar formation is the major problem during the biomass gasification. Tar could condense on the reactor then block and foul equipment. An optimized gasifier and highly active catalyst were proved to be effective for biomass tar elimination. Furthermore, tar formation mechanism and the decomposition pathway were also important to advance the optimization of gasification reactors and catalyst design. This paper summarized the fundamentals, such as gasifier types, Ni-based catalyst, and reaction and deactivation mechanism. This review also sheds light on other excellent catalysts, effective gasifiers and mathematical models of biomass catalytic gasification, and catalyst reaction mechanisms and mathematical models are also discussed in detail. At last, the paper ends with a conclusion and prospective discussion to the latter lab and industrial-scale research.
•It sheds light on excellent catalysts, gasifiers of biomass gasification.•In-depth discussion of mathematical models are provided.•Detailed description of deactivation and reaction mechanisms.•Prospects and disadvantages of gasification reactions are described.
During the past two years, the introduction of DMSO has revolutionized the fabrication of high-quality pervoskite MAPbI3 (MA = CH3NH3) films for solar cell applications. In the developed DMSO ...process, the formation of (MA)2Pb3I8·2DMSO (shorted as Pb3I8) has well recognized as a critical factor to prepare high-quality pervoskite films and thus accomplish excellent performances in perovskite solar cells. However, Pb3I8 is an I-deficient intermediate and must further react with methylammonium iodide (MAI) to be fully converted into MAPbI3. By capturing and solving the molecular structures of several intermediates involved in the fabrication of perovskite films, we report in this work that the importance of DMSO is NOT due to the formation of Pb3I8. The use of different PbI2-DMSO ratios leads to two different structures of PbI2-DMSO precursors (PbI2·DMSO and PbI2·2DMSO), thus dramatically influencing the quality of fabricated perovskite films. However, such an influence can be minimized when the PbI2-DMSO precursor films are thermally treated to create mesoporous PbI2 films before reacting with MAI. Such a development makes the fabrication of high-quality pervoskite films highly reproducible without the need to precisely control the PbI2:DMSO ratio. Moreover, the formation of ionic compound (MA)4PbI6 is observed when excess MAI is used in the preparation of perovskite film. This I-rich phase heavily induces the hysteresis in PSCs, but is readily removed by isopropanol treatment. On the basis of all these findings, we develop a new effective protocol to fabricate high-performance PSCs. In the new protocol, high-quality perovskite films are prepared by simply treating the mesoporous PbI2 films (made from PbI2-DMSO precursors) with an isopropanol solution of MAI, followed by isopropanol washing. The best efficiency of fabricated MAPbI3 PSCs is up to 19.0%. As compared to the previously reported DMSO method, the devices fabricated by the method reported in this work display narrow efficiency distributions in both forward and reverse scans. And the efficiency difference between forward and reverse scans is much smaller.
Traditional fossil fuel overuse could lead to global warming and environmental pollution. As a renewable energy, biomass energy is a sustainable and low pollution carbon energy, which has a wide ...range of sources. Syngas production from biomass thermochemical conversion is a promising technology to realize effective utilization of the renewable energy. Syngas produced from gasification could be further converted into value-added chemicals via the method of Fischer-Tropsch synthesis. Syngas and CO2 methanation could transform renewable energy into feasible transport and high-density energy. However, tar formation and catalyst deactivation are the main problem during the biomass gasification and methanation. This review sheds light on the development of biomass gasification and syngas methanation. Firstly, we presented the common reactors and some other factors during gasification. Secondly, we provide a comprehensive introduction of the advanced active catalyst for gasification and syngas methanation. Finally, some representative large-scale and commercial plants and companies for biomass gasification were compared and discussed in details. Then the prospective developments in combination of gasification and methanation were concluded to give an outlook for biomass gasification and its downstream development.
•Detailed review of gasification and methanation development.•Discussion of high active catalyst for gasification and methanation.•It sheds light on effective reactors for biomass gasification.•Large-scale commercial development of gasification and methanation are discussed.
This work is aimed to study in situ upgrading of Shengli lignite pyrolysis vapors over different metal-loaded HZSM-5 in a drop tube reactor. Co/HZSM-5, Mo/HZSM-5 and Ni/HZSM-5 (5.0wt%) were prepared ...by wet impregnation and characterized by N2 adsorption-desorption analyzer, X-ray diffraction, transmission electron microscope, Fourier transform infrared spectrometer and temperature programmed desorption of ammonia. The effects of temperature and catalyst on product yields and tar properties were investigated. The results show that the optimal temperature for liquid product was 600°C and aromatics can be directly produced from solid lignite by catalytic fast pyrolysis over metal-loaded HZSM-5 under such mild condition. Due to the participation of metal and acid sites, the bifunctional metal-loaded HZSM-5 showed comparable catalytic activity for deoxygenation reaction in the valorization of oxygen content below 7.1%. The introduction of metal causes the increase of aromatics and the decrease of organic oxygen species in upgraded tar remarkably. Among the catalysts, Ni/HZSM-5 exhibited the best performance for production of high quality tars with highest aromatics content of 94.2% (area%), which can be used as a potential candidate for catalytic upgrading of pyrolysis oil.
•Metal-loaded HZSM-5 was prepared for conversion of lignite to light aromatics.•The BTEXN formation was enhanced by metal-loaded HZSM-5.•Oxygen content in pyrolysis tar is remarkably decreased by metal-loaded HZSM-5.•Ni-loaded HZSM-5 is a potential candidate in catalytic upgrading of pyrolysis oil.
Abstract
Compared with the traditional fuel aircraft tractor, the electric tractor using the four-wheel hub motor independent drive mode has the advantages of environmental protection, low costs, ...flexibility, high controllability, and convenience for later maintenance. The paper uses a four-wheel hub motor tractor and a linear vehicle model to propose a hierarchical steering control strategy. The upper layer control adopts the improved integrated sliding mode control algorithm with the yaw angular speed as the control goal to obtain the additional yaw torque. The additional yaw torque obtained is reasonably distributed to each wheel by the use of the rule distribution algorithm of the lower layer control, to obtain the optimal driving torque of each wheel. Finally, the steering stability of the electric aircraft tractor at different speeds is verified based on Simulink. The results show that the control strategy can better control the speed and stability of steering control of electric vehicles.
Novel p–n heterojunction BiOI/BiPO4 nanocomposites composed of p-type narrow band-gap BiOI and n-type wide band-gap BiPO4 displayed superior photocatalytic performance for decomposing methyl orange ...compared to single BiPO4 and BiOI under visible light irradiation (λ>400nm). Display omitted
•Modification of n-type wide band-gap BiPO4 with p-type narrow band-gap BiOI.•p-BiOI/n-BiPO4 was prepared via a deposition–precipitation method.•BiOI distinctly sensitized BiPO4 to absorb most of the visible light.•BiOI/BiPO4 showed excellent visible light photocatalytic activity for MO.•Enhanced photocatalytic activity was due to the BiOI–BiPO4 heterojunction.
Novel BiOI/BiPO4 photocatalyst with a p–n heterojunction was fabricated via a facile deposition–precipitation method. The phase structures, morphologies and optical properties of the obtained samples were studied by several characterization tools including XRD, SEM, HRTEM, BET, EDS and UV–Vis DRS. BiOI/BiPO4 photocatalyst displayed much higher photocatalytic performance for the methyl orange (MO) degradation than the single BiPO4 and BiOI under visible light (λ>400nm). The best photocatalytic activity of BiOI/BiPO4 with nearly 98% MO degradation located at molar percentage ratio of 40% after 2h irradiation. Moreover, BiOI/BiPO4 could also decompose 50% of colorless phenol solution after 8h irradiation. The enhanced photocatalytic performance can be mainly ascribed to the formation of p–n heterojunction interface in BiOI/BiPO4 which facilitates the transfer and separation of photogenerated electron–hole pairs, as well as the strong visible light absorption originating from the sensitization role of BiOI to BiPO4.
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