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Adsorption of Chromium (VI) Using Nano-ZnO Doped Scrap Tire-Derived Activated Carbon

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Journal of Geoscience and Environment Protection 2022年第9期10卷 121-135页

作者： Jean Tsitsi Chigova stanford mudono Department of Chemical Engineering Faculty of Engineering National University of Science and Technology (NUST) Bulawayo Zimbabwe

Nowadays, nano mineral modified biochars show a promising adsorption capacity for pollutants removals by combining the advantages of porous structure of biochar and unique property of nano minerals. In this work, nano-zinc oxide doped scrap tire derived activated carbon (nZnO-STAC) was synthesized by wetness impregnation method. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models while the kinetics of the process were examined using Lagergren Pseudo-first and second order, intraparticle diffusion and Elovich kinetic models. Characterization of the activated carbon by Powder X-ray Diffraction (PXRD). The surface groups present on the activated carbon surface were determined using the Fourier Transform Infra-Red Spectroscopy (FTIR) analysis. Optimization studies were carried out to determine the effects of pH, initial metal concentration, adsorbent dosage, contact time and adsorbent particle size on the Cr (VI) removal efficiency. The results showed optimum Cr (VI) removal at pH 3, 10 mg/L concentration, 120 minutes of contact using 1000 - 1400 μm adsorbent particle size at a dosage of 2.5 g/L. The adsorbent structure was found to be predominantly amorphous. The chromium removal efficiency of the adsorbent was around 81.6%. Of the tested kinetic models, the pseudo-second order model exhibited the best fit with the experimental data with an R2 value of 0.9744. This study clearly demonstrates the feasibility of using the nano-ZnO doped scrap tyre derived activated carbon adsorbent for the remediation of chromium (VI) polluted industrial wastewaters.

关键词： Adsorption Zinc Oxide Nanoparticles Tire Granules Hexavalent Chromium Tannery Effluent

Investigation on the Potential Production of Diesel from Waste Tires

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Journal of Power and Energy Engineering 2022年第10期10卷 1-12页

作者： stanford mudono Nicholas Jim Jean Tsitsi Chigova Department of Chemical Engineering Faculty of Engineering National University of Science and Technology Bulawayo Zimbabwe

An alternative fuel production was performed by catalytic-pyrolysis of waste tires under a nitrogen (N2) environment and with a zeolite catalyst. Pyrolysis of scrap tires has been pointed out as an alternative to the incorrect disposal of tire wastes. Pyrolysis processes can produce tire-derived oils that may be used as fuel or added to conventional fuels, producing fuel blends with improved properties and reduced cost. The pyrolysis process can contribute to removing tire residues from inadequate sites and it can be a sustainable process to produce alternative fuels. The project investigated the conversion of the waste tires into diesel as one way of waste management and also as a viable process which in turn helps to meet the fuel demand. Uses of the diesel and the by-products from the process were also outlined. Experiments were conducted on the pyrolysis process in order to find the optimum conditions for producing the diesel through pyrolysis;the temperature and residence time were optimized in order to get maximum output from the process. The optimum temperature of the reaction was found to be 520˚C and the optimum residence time was 92.5 minutes. Quality tests of the product were then conducted on the obtained product and most of the properties were found to meet the required standard specifications. The most critical properties which are density, final boiling point, flash point and kinematic viscosity, were found to be 0.8495 g/cm3, 370˚C, 50.5˚C and 3.681 cSt, respectively, and they were within the required specifications. Quality analysis showed that a quality product that is suitable for automobiles could be obtained from the process. The process also produces useful by-products such as char, which can aid in the purification process of the diesel after conversion to activated carbon. The process is environmentally friendly if the appropriate pollution prevention methods like gas absorption are thoroughly implemented. Wa

关键词： Density Pyrolysis Residence Time Diesel Flash Point Kinematic Viscosity

Gamma Photon Column Scanning of Prototype and Industrial Distillation Columns

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World Journal of Engineering and Technology 2023年第3期11卷 476-492页

作者： Witness Chirume Joseph Simpson Dongo Caven Dzingai Robin Tinavo Mashingaidze stanford mudono Rachad Alami Peter Baricholo Applied Physics Department National University of Science and Technology (NUST) Bulawayo Zimbabwe Chemical Engineering Department National University of Science and Technology (NUST) Bulawayo Zimbabwe Instrumentation and Industrial Applications National Centre of Nuclear Energy Sciences and Techniques (CNESTEN) Rabat Morocco

Monte Carlo simulation of gamma photon transport and interaction with the distillation column and its contents was performed in order to predict the effects of gamma photons when they interact with matter. The results of the interaction and transport of gamma photons are presented as energy deposition on the distillation column and its contents. Energy attenuation was more pronounced on the column walls and trays as compared to the region between the trays, where there is mostly vapour space. Gamma column scanning was then used to verify the Monte Carlo simulation results by scanning and investigating the integrity of two laboratory prototype distillation and industrial distillation columns. One of the prototype distillation columns was 1 m tall with four trays and the other one was 1.8 m tall consisting of six trays and a packed bed. Commonly encountered distillation column malfunctions such as collapsed tray, weeping, flooding and foaming were simulated in the two prototype distillation columns and scanned. The industrial distillation column was a 26 m tall benzole prefractionator column, consisting of 60 single pass trays and a diameter of 0.8 m. A 10 mCi 60Co gamma radiation source and NaI(Tl) scintillation detector were used to scan the distillation columns. The results from the two prototypes showed that all the simulated malfunctions were clearly detected except for foaming. The results from industrial distillation column showed that all the trays were in their correct position although tray number 32 could be partially damaged and just below tray 41, the scan revealed that there was a loss of column wall thickness. The obtained density profile for the industrial distillation column showed some small variations from the expected density profile and this was attributed to external features on the distillation column and wind bursts that shifted the source and detector from the chosen scan line orientation.

关键词： Gamma Photon Transport Distillation Column Malfunctions Monte Carlo Simulation

The T-box Transcription Factor T-bet in Immunity and Autoimmunity

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Cellular & Molecular Immunology 2006年第2期3卷 87-95页

作者： stanford L.Peng Inflammation Autoimmunity and Transplantation ResearchRoche Palo AltoPalo AltoCAUSA

The T-box transcription factor T-bet （Tbx21） has emerged as a key regulator of type 1-like immunity, playing critical roles in the establishment and/or maintenance of effector call fates in T and B lymphocytes, as well as dendritic cells and natural killer calls. Several autoimmune diseases, especially those classically considered related to T helper 1 （Thl） immunity, appear to require T-bet, at least as judged in mouse models. This review summarizes a current understanding of T-bet＇s role in immunity, as wall as its importance in autoimmunity, with implications for therapeutic intervention.

关键词： transcription factor arthritis lupus inflammatory bowel disease diabetes multiple sclerosis

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Hydrologic and water quality performance of a laboratory scale bioretention unit

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Frontiers of Environmental Science & Engineering 2018年第1期12卷 159-167页

作者： Jun Xia Hongping Wang Richard L. stanford Guoyan Pant Shaw L. Yus State Key Laboratory of Water Resources ＆ Hydropower Engineering Sciences Wuhan University Wuhan 430072 China Key Laboratory of Water Cycle ＆ Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Department of Environmental Engineering School of Resources and Environmental Science Wuhan University Wuhan 430079 China ATR Associates Inc. Strasburg VA 22657 USA Department of Civil and Environmental Engineering University of Virginia Charlottesville VA 22903 USA

A bioretention unit （BRU） or cell is a green infrastructure practice that is widely used as a low impact development （LID） technique for urban stormwater management. Bioretention is considered a good fit for use in China＇s sponge cit.y construction,projects. However, studies on biooretention design, whichincorporates site-specific environmental and social-economic conditions in China are still very much needed. In this study, an experimental BRU, consisted of two cells planted with Turf grass and Buxus shfica,was tested with eighteen synthesized storm events. Three levels （high, median, low） of flows and concentrations of pollutants （TN, TP and COD） were fed to the BRU and the performance of which was examined. The results showed that the BRU not only delayed and lowered the peak flowsbut also removed TN, TP and COD in various ways and to different extents. Under the high, medium and low inflow rate conditions, the outflow peaks were delayed for at least 13 minutes and lowered at least 52%. The two cells stored a maximum of 231 mm and 265 mm for turf grass and Buxus sinica, respectively. For both cells the total depth available for storage was 1,220 mm, including a maximum 110 mm deep ponding area. The largest infiltrate rate was 206 mrn/h for both cells with different plants. For the eighteen events, TP and COD were removed at least 60% and 42% by mean concentration, and 65% and 49% by total load, respectively. In the reservoir layer, the efficiency ratio of removal of TN, TP and COD were 52%, 8% and 38%, respectively, within 5 days after runoff events stopped. Furthermore, the engineering implication of the hydrological and water quality performances in sponge city construction projects is discussed.

关键词： Bioretention unitSponge cityStormwater runoffPeak reductionPollutant removal

LARGE-SIGNAL RESULTS FOR DEGENERATE FOUR-WAVE MIXING AND PHASE CONJUGATE RESONATORS

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天津大学学报 1982年第4期 107-122页

作者： A.E.Siegman stanford University CA 94305 USA

A calculation procedure and various large-signal and numerical solutions are presented for degenerate four-wave mixing in optical Kerr media, and for phase conjugate resonators using degenerate four-wave mixing. The solutions presented take full account of nonlinear refractive index changes, pump depletion, signal saturation, distributed losses, and possible external mirrors with laser gain. We find that including the nonlinear index change generally causes little change in the reflectivity or power output of degenerate four-wave mixing devices, at least with symmetric pumping. The optimum power output from a phase conjugate resonator with and without a laser gain medium is calculated. The results provide some theoretical guidance for designing phase conjugate *** Code 42. 65. Bp; 42. 60. Da

关键词： DFWM LARGE-SIGNAL RESULTS FOR DEGENERATE FOUR-WAVE MIXING AND PHASE CONJUGATE RESONATORS

Effect of process parameters on the density and porosity of laser melted AlSi10Mg/SiC metal matrix composite

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Frontiers of Mechanical Engineering 2018年第4期13卷 520-527页

作者： Omotoyosi H. FAMODIMU Mark stanford Chike F. ODUOZA Lijuan ZHANG Faculty of Science and Engineering School of Engineering Telford Campus University of Wolverhampton WV1 1LY Wolverhampton UK

Laser melting of aluminium alloy-AlSi10Mg has increasingly been used to create specialised products in various industrial applications, however, research on utilising laser melting of aluminium matrix composites in replacing specialised parts have been slow on the uptake. This has been attributed to the complexity of the laser melting process, metal/ceramic feedstock for the process and the reaction of the feedstock material to the laser. Thus, an understanding of the process, material microstructure and mechanical properties is important for its adoption as a manufacturing route of aluminium metal matrix composites. The effects of several parameters of the laser melting process on the mechanical blended composite were thus investigated in this research. This included single track formations of the matrix alloy and the composite alloyed with 5% and 10% respectively for their reaction to laser melting and the fabrication of density blocks to investigate the relative density and porosity over different scan speeds. The results from these experiments were utilised in determining a process window in fabricating near-fully dense parts.

关键词： selective laser melting additive manufacturing mechanical alloying powder metallurgy aluminium metal matrix composite

The olfactory circuit of the fruit fly Drosophila melanogaster

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Science China(Life Sciences) 2010年第4期53卷 472-484页

作者： LIANG Liang1,2 & LUO Liqun1 1Howard Hughes Medical Institute, Department of Biology 2Department of Applied Physics, stanford University, stanford, CA 94305, USA Howard Hughes Medical Institute Department of Biology Stanford University Stanford USA Department of Applied Physics Stanford University Stanford USA

The olfactory circuit of the fruit fly Drosophila melanogaster has emerged in recent years as an excellent paradigm for studying the principles and mechanisms of information processing in neuronal circuits. We discuss here the organizational principles of the olfactory circuit that make it an attractive model for experimental manipulations, the lessons that have been learned, and future challenges.

关键词： olfactory receptor neurons projection neurons local interneurons antennal lobe mushroom body lateral horn behavior information processing

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Analysis on the decadal scale variation of the dust storm in North China

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Science China Earth Sciences 2005年第12期48卷 2260-2266页

作者： KANG Dujuan1,2 & WANG Huijun1 1. NZC/LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100871, China 2. Environmental Fluid Mechanics Laboratory, stanford University, stanford CA 94305, USA NZC/LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Environmental Fluid Mechanics Laboratory Stanford University Stanford USA

In this paper, the temporal variation characteristics of the dust storm in North China are investigated. Based on power spectrum analysis and wavelet analysis, 1956-1970 and 1985-1999 are chosen as the high-frequency and low-frequency dust storm decades respectively. Analysis results clearly show that the spring and wintertime anomalous atmospheric circulation between these two dec-ades are significantly different. Compared with the former decade, there are a strengthened polar vortex, enhanced westerlies near 50°N, and a weak East Asian major though in the winter of the latter decade. The north and center parts of the Siberian high and the Aleutian low become weak. The southerly and easterly wind anomalies appear over the north and east parts of China, which implies the weakening of East Asian winter monsoon. Meanwhile, northern China experiences warmer winters and wetter springs, which are in favor of the weakening of dust storm intensity in North China. There are significant out-of-phase relationships between dust frequency and wintertime westerly intensity, as well as between dust frequency and Arctic Oscillation. It is also found that the frequency of dust weather is strongly re-lated to winter-springtime East Asian monsoon intensity.

关键词： dust storm, climate anomaly, decadal scale variability, East Asian monsoon, AO.

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