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  • Cramer Graversen posted an update 1 day, 5 hours ago

    Pitch coking determines the quality of pitch coke, which ultimately affects the quality of a carbon anode. In this work, green carbon anodes were studied by scanning electron microscopy (SEM), and the pitch pyrolysis process was tested using a custom-built pyrolysis device. The influence of the coke size on pitch pyrolysis was examined and the action law was analyzed. The results show that the outermost layer of the large size coke has a certain pitch thickness, the subouter layer is filled with a “mixture of fine particles and the pitch,” and the internal area is not soaked by the pitch. Meanwhile, the small particles are soaked and wrapped by the pitch. The pyrolysis dynamics analysis shows that with the increase in particle size, the activation energy gradually increases to 70.00 kJ/mol for 1-2 mm, then rapidly decreases to 31.88 kJ/mol for 3-4 mm, and finally slowly increases to 50.56 kJ/mol for 6-9 mm. When the particle size increases, the coke size 2-3 mm area is dominated by the porous structure.Mycobacterium tuberculosis (Mtb) remains a deadly pathogen two decades after the announcement of tuberculosis (TB) as a global health emergency by the World Health Organization. Medicinal chemistry efforts to synthesize potential drugs to shorten TB treatments have not always been successful. Here, we analyze physiochemical properties of 39 TB drugs and 1271 synthetic compounds reported in 40 publications from 2006 to early 2020. We also propose a new TB space of physiochemical properties that may provide more appropriate guidelines for design of anti-TB drugs.Wood pellet boilers for residential heating applications offer the promise of low emissions, high efficiency, and automatic operation. However, when operated in the field, these units operate often at very low loads causing them to cycle. In this study, the performance of a 25 kW modern pellet boiler under emulated field conditions and fixed nominal loads of 15 and 100% has been studied in a lab-with and without a buffer tank. A dilution tunnel approach was used for the measurement of particulate emissions, in accordance with US certification testing requirements under EPA Methods 28 WHH and 28 WHH PTS. CT-707 Results show that increasing the amount of thermal storage used decreases cycling rates leading to decreased emissions and increased efficiency. Without thermal storage, integrated efficiency over a 15% load test period was 57%, compared to 74% when thermal storage was used. Particulate emissions were 180 and 64 mg/MJ for the 15% load case without and with thermal storage, respectively.The photocatalytic efficiency of TiO2 is reduced by rapid electron-hole recombination. An effective approach to address this limitation is to have TiO2 doped with various metal ions or heteroatoms. Herein, we prepared a series of Li+-doped TiO2 nanoparticles showing high photocatalytic activities through the sol-gel method. The samples were characterized by X-ray diffraction (XRD) and surface area analyses. Effects of Li+ doping on the Brunauer-Emmett-Teller (BET) surface area, crystallite size, phase transformation temperature, and phase composition were studied. The results showed that Li+ doping can promote the generation of the rutile crystal phase in TiO2, lower the anatase-to-rutile transformation temperature, and generate the mixed-crystal effect. The photocatalytic degradation of methyl orange (MO) was used as a probe reaction to evaluate the photoactivity of the nanoparticles. Parameters affecting the photocatalytic efficiency, including the Li+ doping amount, calcination temperature, and catalyst amount, as well as the kinetics of the photocatalytic process toward the degradation of MO, were investigated. The mixed-crystal TiO2, which was doped with 1.0 mol % Li+ and calcined at 550 °C containing 27.1% rutile and 72.9% anatase phase, showed a 2.2-fold increase in the photoactivity on the basis of the rate constant of MO decomposition as compared with the undoped TiO2. The existence of a definite quantity of rutile phase could effectively inhibit the recombination of the electron-hole pairs, thus promoting photocatalytic activity.Coal is one of the major fuels for power generation, and it will continue in this capacity for the next several decades. Two types of coal are mainly used lignite and bituminous coals. When exposed to air, post-mining, the coal surface undergoes LTO (low-temperature oxidation) at RT-150 °C according to the atmospheric oxygen level. The LTO process decreases the calorific value of the coal, and consequently, different gases are released [mainly carbon oxides (CO, CO2), water vapor, hydrogen (H2), and also some low molecular-weight organic gases (C1-5)]. Some of these gases are toxic and flammable. In extreme cases, fires erupt. The mechanism by which the molecular oxygen oxidizes the coal macromolecule at the temperature range of 30-150 °C (LTO process) is complex and also involves a chain of radical reactions that take place; however, the exact underlying mechanism is not yet clear. The LTO process was studied in detail by simulating the processes occurring in the coal piles by using two coal types an American Bailey coal, used in Israeli coal-fired utilities and a German Hambach lignite, used in German utilities. The mechanism underlying the LTO process and the radical reactions that are involved are discussed in detail.The advancement of hydrogen and fuel cell technologies hinges on the development of hydrogen storage methods. Metal-organic frameworks (MOFs) are one of the most favorable materials for hydrogen storage. In this study, we synthesized a series of isostructural mixed-metal metal-organic frameworks (MM-MOFs) of 1,3,5-benzenetricarboxylate (BTC), M-Cu-BTC, where M = Zn2+, Ni2+, Co2+, and Fe2+ using the post-synthetic exchange (PSE) method with metal ions. The powder X-ray diffraction patterns of MM-MOFs were similar with those of single-metal Cu-BTC. Scanning electron microscopy indicates the absence of amorphous phases. Inductively coupled plasma mass spectroscopy of the MM-MOFs shows successful metal exchanges using the PSE method. The N2 adsorption measurements confirmed the successful synthesis of porous MM-MOFs. The metal exchanged materials Ni-Cu-BTC, Zn-Cu-BTC, Fe-Cu-BTC, and Co-Cu-BTC were studied for hydrogen storage and showed a gravimetric uptake of 1.6, 1.63, 1.63, and 1.12 wt %; respectively. The increase in hydrogen adsorption capacity for the three metal exchanged materials is about 60% relative to that of the parent MOF (Cu-BTC).

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