Search

A comprehensive one-dimensional model was developed in this work for the simulation of a riser regenerator. The model incorporates the hydrodynamic characteristics of fluidized bed risers and the detailed reaction kinetics of FCC (fluid catalytic cracking) catalyst regeneration and can be used to predict the axial profiles of temperature, oxygen concentration and coke content of the catalyst in the riser. The validity of the present model was confirmed by the experimental data from a pilot demonstration unit. Based on the simulation, effects of solids flow patterns and other parameters including gas velocity, spent and regenerated solids fluxes, temperatures of air and spent catalysts as well as carbon content on the spent catalysts have been systematically examined. The simulation results have provided the necessary information for the optimal design and operation of a FCC riser regenerator unit, presently in operation in China.

To simulate the gas and solids flow structure in downflow circulating fluidized beds or downer reactors, a two-dimensional two-phase turbulence hydrodynamic model (κ. — ϵ turbulence model) was developed. The influence of solid particles on the turbulence structure of the gas phase has been considered in deriving the hydrodynamic model. An improved numerical method (based on the SIMPLE method) is used for the flow model calculation. The predicted radial distributions or axial gas and particle velocities are in good agreement with the experimental data determined by LDV measurement. This turbulence hydrodynamic model provides a good description of the gas and solids flow structure in the downer.

A new method for the hydrolysis of methyl acetate, which consists of a prereactor and a reactive distillation column, has been proposed. The operating variables, including the feed rate, feed ratio of water to MeOAc and reflux ratio, are investigated. It has been found that the conversion of MeOAc increases with increasing reflux ratio, but decreases with increasing feed rate. The feed ratio of water to MeOAc has a considerable effect on the conversion of MeOAc, and an optimum feed ratio has been obtained for the present process.

The growing electric vehicle requirements have attracted great interest in development of lithium ion batteries (LIBs) with large gravimetric and volumetric capacities, long cycle lifespan. To meet these applications, high quality electrode materials are needed. However, conventional bulk electrode materials cannot fully reach the increasing demands due to their inherent limits in performance. In recent years, nanostructured electrode materials with higher rate capability have been acknowledged by low lithium-ion diffusion distance and high electrode/electrolyte area. However, electrode made from nanostructured electrode materials meets these challenges. (1) Nanoparticles tend to self-aggregate and the side reaction with the electrolyte due to high specific surface area, which lead to low initial coulombic efficiency and poor cycling life. (2) Nanoparticles have a huge volume changes during Li+ insertion/ extraction that result in fracture of nanostructured particle, delaminating of the conductive coating and low capacity with cycle increasing. (3) Nanostructured particles have low tap density which results in a low volumetric energy density.Therefore, the electrode materials with optimal structure should be developed to deal with above-mentioned problems. Micro-/nanostructures with controlled size and morphology have attracted considerable attention as high-performance anode materials for next-generation LIBs. This micro-/nanostructure should be a porous microstructure composed of primary nanocrystallines tightly compacted to form 3D channels for ion diffusion. Moreover, this structure can exploit many advantages of nanostructure for lithium ion batteries due to the reduction of side reactions with electrolyte, leading to high density and long cycling life with high safety. Some simple micro-/nano-structured metal oxides such as Mn-based oxides, Co-based oxides, Fe-based oxides and Sn-based oxides, have been recently reported for use in LIBs. Mn-based oxide electrodes (MnO, MnO2, Mn2O3, Mn3O4, ZnMn2O4, NiMn2O4 and CoMn2O4) are developed due to low operating voltages (1.3-1.5 V for lithium extraction) and high energy density. Among these Mn-based anodes, CoMn2O4 has been considered for substitution of the conventional graphite anode in LIBs. The shape and micro/nanostructure of CoMn2O4 material play an important role in the electrochemical performances. In this paper, uniform hierarchical porous CoMn2O4 microspheres and microflowers were realized by adjusting the urea concentration through a solvothermal process followed by a post-annealing treatment. In the low urea concentration, the microflower with diameter size of around 10 μm is composed of porous nanosheets with a thickness of about 20 nm. In the high urea concentration, a large amount of uniform CoMn2O4 microspheres is obtained with average diameter of about 8 μm. CoMn2O4 microsphere is highly porous and composed of numerous primary nanoparticles. As expected, the distribution of the O, Mn and Co elements is homogeneously distributed on the surface for CoMn2O4 microflower and microsphere. The actual molar ratios of Mn and Co for CoMn2O4 microflower and microspheres obtained from energy-dispersive X-ray (EDX) analysis are close to 2, which are consistent with the ratio of that in the precursor solution. The chemical compositional and crystalline structural changes of as-prepared samples were characterized using X-ray diffraction (XRD) and thermogravimetric analysis (TGA). These results show the precursor in the low urea concentration is a MnCo-complex structure (including CoMn-layered double hydroxide and CoMn-glycolates or alkoxide derivatives) in an alkaline environment under this solvothermal conditions. Meanwhile, in the high urea concentration, the precursor Co1/3Mn2/3CO3 sample is formed. The possible formation mechanism of as-prepared CoMn2O4 microsphere and microflower precursors is explained due to the presence of CO2 pressure into the reaction solution. When used as anode materials for lithium-ion batteries, the porous CoMn2O4 microflower and microspheres exhibited good long-life cycling performance at high rate density. At a current density of 100 mA g-1, the CoMn2O4 microflower and microspheres exhibit an initial capacity of 1200 and 1225 mA h g-1 and the capacity is maintained at 710 and 220 mAh g-1 after 50 cycles. Excellent rate capabilities (~813 mAh g-1 at 200 mA g-1 and ~612 mAh g-1 at 600 mA g-1) are observed for CoMn2O4 microspheres. Based on these results, the good electrochemical properties can result from the porous CoMn2O4 microspheres. On the one hand, the micro-/nano porous structured CoMn2O4 microspheres could significantly enhance the electrode integrity by buffering the volume changes with repeating Li+ insertion/ extraction, which is contributed to good cycling stability. On the other hand, the micro-/nano porous structured CoMn2O4 microspheres provide extra active position for Li+ storage and short Li+ ion diffusion length, contributing to the high specific capacity and better rate capability. The CoMn2O4 hierarchical porous microspheres, which have good electrochemical performance and ease of fabrication, hold the great promise as the anode materials for high-performance LIBs. Figure 1

Nowadays, high power Lithium-ion batteries are used as power sources for automobiles in significant quantities. The environmental recycling and resources reuse of these spent automotive Lithium-ion batteries should be highly desired, after their useful lives end. An automotive Li-ion battery pack consists of hundreds of or more individual cells, which are connected and assembled into a pack with control circuitry, as well as thermal and battery management system. These components could be recycled intact from the battery pack, but the recycling process of these individual cells with different chemical compositions is more complicated. In this paper, an effective physical recycling process is put forward and applied to 60Ah prismatic Lithium-ion batteries with steel cove, which are used in electric vehicles produced by China’s Beijing New Energy Automotive Corporation. The recycling process includes the first electrolyte extraction and harmless treatment, cell incision and components separation, and the recovery of active materials. The cleanly separated components such as current collectors, active materials and separator, are high-purity materials which could be reused directly as raw materials to produce another high-value product. Firstly, it is very important to ensure the safety and prevent explosion during the recycling processes, because Lithium-ion batteries contain toxic and flammable electrolyte. The pre-treatment of the individual cell includes the collection and concentration process of organic electrolyte: safe and non-toxic organic solvent was injected into the sealed cell to dissolve the electrolyte, then withdrew and distilled to reuse. The collection process was repeated, finally the sealed cell was vacuum extracted. The distilled residues contain some organic electrolyte solvents such as ethyl methyl carbonate, diethyl carbonate, and salt LiPF6. It was treated with alkali solution to reduce the toxicity of LiPF6, and the reaction product gas HF was absorbed by Ca(OH)2 to form CaF2. The harmless treatment of the LiPF6 in the electrolyte is helpful to carrying out the subsequence processes. Second, the individual cell without electrolyte was opened by cold cutting mode from the top, and jell roll of lithium-ion cell was withdrew from the steel can by clamp. Then jelly roll was reversely winded to part cathode electrode, anode electrode and separator. The segregation of cathode and anode electrodes is benefitial to respectively recycle high-purity different electrode materials (LiFePO4 with binder and conductive additive, graphite with binder) and Cu, Al foils, and avoid the cross contamination. It is quite different the chemical process, by which batteries are crushed, and leached the elements are leached by complicated chemical processes. High power ultrasonic system was used to exfoliate electrode materials from the current collectors. After comparing different solvents, it was verified that low concentration alkaline solution was most effective to exfoliate the cathode and anode electrode materials. Within about 10 minutes, the electrode could be separated into black electrode materials and clean metal foils with metal luster. There is no Al element detected in the solution by ICP, except the alkaline concentration is higher than 2 mol/L. This process has the advantage that almost cathode and anode components are segregated without contaminants, therefore, it is very favorable to recover the active materials by simple heat-treatment with Li salt supplement. Moreover, the recycled steel cans, clean Cu and Al foils can be reused directly. The recycled components corresponding to the separation and recycling steps are shown in Figure 1. It is difficult to recover Li element from recycled cathode material LiFePO4 by chemical precipitation. Because Fe element is very easy to form colloidal precipitation to adsorb a mass of Li+, which greatly decreases the Li recovery efficiency to 52.4%. Considering the recovery cost, it is an effective route to recover the active material LiFePO4 using the recycled materials. Although the recovery efficiency is 95.8% using the amount of cathode electrode in the spent battery as reference, the electrochemical performance of the recovered active material needs to be improved. Their discharge capacities of 120-130mAh/g are lower than original 150mAh/g. Perhaps it is reasonable that recovered materials could possibly be used in less-stringent capacity requirements. Based on our environmentally friendly separation and recycling processes, the pilot recycling demonstration line of automotive Lithium-ion batteries had been established in China’s Beijing Pride Power System Technology Corporation, providing Lithium-ion battery packs for China’s Beijing New Energy Automotive Corporation. The simple recycling technologies are helpful to solve the environmental and resources problems caused by the retirement of mass automotive batteries in the future, and it also needs time to improve the equipment and enact regulations to achieve the recycling goal of harmlessness, large-scale, standardization and automatization. Figure 1

Lithium-ion batteries as a new clean energy with high specific energy and excellent cycle performance and long life serve widely as the power source for many portable electronic devices. However, their power and energy densities need to be further increased particularly for the application in electric vehicles. It is important to develop high capacity anode materials to increase the energy density of lithium-ion batteries as the anode material is one of the key factors affect the performance of lithium-ion batteries. SnSb intermetallic alloys are attractive materials as a potential substitute for the conventional graphite anode because their theoretical capacity of SnSb alloys has been estimated to be superior to that of graphite. However, its practical use is hampered by their large volume change during alloying and de-alloying reaction with Li+, as the continuous volume change during cycling will cause the mechanical pulverization resulting in poor cyclability and cracking of the electrode. Various strategies have been brought forward to improve the cycling stability, for example, preparing thin film materials or nanostructured materials. nanostructured alloy anodes have shown an improved cycle lifetime because nanostructured alloy anodes can accommodate the large volume change and maintain the structural integrity of the electrode during the lithiation/de-lithiation process. In this paper, a nanostructured SnSb anode for Li-ion battery has been prepared by a two-step electrode design consisting of the electrochemically assisted template growth of Cu nanopillars onto a current collector followed by electrochemical plating of SnSb, there among, Cu nanopillars current collector was obtained by P. Simon's method. We try to take advantage of the nanostructuration of our electrodes to buffer the mechanical strains occurring during the cycling of tin and antimony with Li+, thanks to larger free space available for alloy–dealloying reactions, delivers a high cycle life and good power performance. Firstly, Cu nanopillars current collectors were obtained using previously reported procedure. Briefly, arrays of copper nanorods on copper disk substrate were prepared by pulsed cathodic electrodeposition through an alumina oxide membrane. The electrolytic cell assembly has been described in P. Simon's work. Secondly, Copper nanopillars were covered with SnSb by means of an electro-co-deposition process from an aqueous solution consisting of SnSO4, KSbOC4H4O6∙1/2H2O, K4P207∙l0H2O and gelatin. The SnSb coating was produced at a constant cathode current density using a two-electrode glass cell at room temperature. Cu substrate containing copper nanopillars acted as the working electrode, whereas a Pt foil served as the counter electrode. The electrodeposits were carried out for a certain deposition time in a galvanostatic mode. After SnSb electro-co-deposition, the obtained SnSb nanostructured anodes were washed with distilled water and acetone successively and then placed under argon atmosphere to avoid oxidation. The morphology, structure and composition of these anode materials were characterized by XRD, SEM and EDS, respectively. The electrochemical reaction mechanism, charge/discharge capacity and cycle performance were analyzed by various electrochemical measurements. And on this basis, we investigated the correlations between material properties and electrochemical performance of the electrode. The scanning electron microscopy (SEM) image clearly shows SnSb nanoparticles are uniformly deposited on the surface of the Cu nanopillars without any coalescence between them. This particular nanostructure is expected to be able to accommodate volume variations occurring during cycling in a lithium cell and thus result in excellent capacity retention. EDS analysis of the deposits of SnSb on Cu nanopillars current collectors gave a Sn:Sb atomic ratio of about 1: 1. The peaks of X-ray diffraction (XRD) pattern are attributed to the SnSb phase and show a rather amorphous feature. Electrochemical measurements showed that the SnSb nanostructured anodes show a relatively smooth voltage curve and a high initial coulombic efficiency of 95.7%,Quite different the curves with distinct voltage plateaus of the SnSb film electrode which SnSb deposited on a flat surface. And more importantly, the SnSb nanostructured electrode exhibited a high initial reversible storage capacity of about 738.9mAh/g and excellent capacity retention with only 10.6% decay over 30 cycles. The reversible capacity and capacity retention is high compared with the similar materials reported by other literatures. Obviously, the SnSb alloy deposited on the Cu nanopillars experiences the same internal stress as that of the SnSb alloy deposited on a flat Cu surface. In the case of the nanostructured electrode, however, the volume variations upon cycling are effectively buffered by the large free volume between the pillars, thus giving to the electrode the observed excellent capacity retention. It is anticipated that the AAO template-assisted method could also be applied to synthesize other promising nanostructured electrode materials by electrodeposition. Figure 1

Thioredoxin interacting protein (Txnip) is one of the most abundantly up-regulated genes in response to hyperglycemia. The increased renal expression of Txnip was associated with type IV collagen accumulation in streptozotocin-induced diabetic mice. As the mechanism of action of high glucose is unknown, we undertook the investigation of the signaling pathway on the upregulation of Txnip expression induced by high glucose in rat mesangial cells. Rat mesangial cells were exposed to normal (5.5 mM) or high (25 mM) glucose at different time points. Txnip expression was determined using real-time RT-PCR and western-blotting at transcription and translation level, respectively. Intracellular reactive oxygen species (ROS) was detected by FACS Calibur flow cytometer using fluorescent probe (DCFH-DA).The treatment with high glucose resulted in an increase of Txnip mRNA from 4 h to 12 h and Txnip protein from 12 to 24 h in comparison with normal glucose condition. In addition, N-acetyl-cysteine (NAC) was found to decrease Txnip protein expression under high glucose condition. Furthermore, p38MAPK inhibitor SB203580 suppressed Txnip expression at transcription and protein level significantly to high glucose exposure. These results suggest that high glucose exposure improves Txnip mRNA and protein expression level by ROS/MEK/MAPK signaling pathway.

Increased mesangial cell proliferation is one of the major pathologic features in the early stage of diabetic nephropathy (DN). Carnosine is an endogenously synthesized dipeptide that has been reported as a protective factor in diabetic nephropathy. However, the underlying mechanism involved in this effect remains to be elucidated. In this study, the effect of carnosine on cell proliferation and its underlying mechanisms were investigated in cultured rat mesangial cells by the methylthiazoletetrazolium (MTT) assay, the 5-bromo-2-deoxy-uridine (BrdU) cell proliferation assay, flow cytometry and western blotting. The results showed that pretreatment of mesangial cells with carnosine significantly inhibited cell proliferation and DNA synthesis in a dose-dependent manner by increasing the cell population in G1 and reducing that in S-phase. In addition, carnosine could reverse high glucose-induced down-regulation of cyclin-dependent kinase inhibitor p21 but not that of p27. Furthermore, carnosine could reduce the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (p38 MAPK). Taken together, these results suggest that carnosine can inhibit mesangial cell proliferation by modulating cell cycle progress, indicating that carnosine could be a potential therapeutic agent for the prevention of DN in the early stage.

Li-rich cathode material Li[Li0.1Ni0.35Mn0.55]O2 was synthesized by a sol-gel method. The morphology and a-NaFeO2 type structure of the material at ambient conditions were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The high-pressure behavior of the material was studied at pressure up to 19.7 GPa by using angle dispersive synchrotron X-ray powder diffraction (ADXD). The studies affirmed that the a-NaFeO2 type structure existed up to at least 19.7 GPa. Rietveld refinement analysis indicated that the c/a lattice parameter ratio decreased and the Li-O bond length shrunk with the increasing pressure, however, the Li+/Ni2+ ions exchange increased under elevated pressure. The pressure-volume data of the material were fitted to the third-order Birch-Murnaghan equation of state and bulk modulus obtained upon compression from the fitting was 117 (1) GPa.

This paper discusses the conditions which an active wideband echo model in the active echo location should satisfy in a strict sense. Then the analysis of a wideband signal's velocity and distance resolutions is proposed. It is proved that the duration and the carrier frequency of the transmitted signal determine the resolutions. Finally, the cosine signal with a Gauss envelope is analyzed by the method proposed and some results are given. The work provides an efficient analyzing tool for wideband signal processing.

Background ECRG4 has been shown to be a candidate tumor suppressor in several tumors, but its role in glioma remains poorly understood. In this study, we examined the mRNA expression of ECRG4 and investigated its biological role in glioma cells. Methods Real-time PCR was used to examine expression of ECRG4 in gliomas and their matched brain tissues. The effect of ECRG4 expression on cell proliferation, invasion, and migration was investigated in human U251 glioma cells. Finally, the regulation of transcription factor NF-kB by ECRG4 was evaluated by western blotting. Results Of the 10 paired samples analyzed, 9 glioma tissues displayed the decreased expression of ECRG4 compared to matched normal brain tissues. Cells transfected with ECRG4 showed significantly decreased cell proliferation as evaluated by MTT and colony formation assays. Furthermore, overexpression inhibited cell migration and invasion in transwell and Boyden chamber experiments and retarded the cell cycle progression from G1 to S phase by FACSCaliber cytometry. Protein levels of nuclear transcription factor NF-kB, which is involved in cell proliferation, inversely correlated with ECRG4 expression. Conclusion Our data suggest that ECRG4 serves as a tumor suppressor in glioma.