Surface-modified maghemite as the cathode material for lithium batteries

The inorganic–organic hybrid maghemite (γ-Fe₂O₃)/polypyrrole (PPy) was synthesized and evaluated as cathode-active material for room temperature lithium batteries. The nanometer-sized core–shell structure of the hybrid consisting of the maghemite core with surface modified by PPy was evidenced from the morphological examination. The cathode fabricated with the as-prepared hybrid material delivered an initial discharge capacity of 233 mAh g⁻¹ and a reversible capacity of ∼62 mAh g⁻¹ after 50 charge–discharge cycles. A much higher performance with an initial discharge capacity of 378 mAh g⁻¹ and a reversible capacity of ∼100 mAh g⁻¹ was achieved with the cathode based on the segregated active material, which was obtained by subjecting the as-prepared hybrid material to an additional ball-milling process. The study demonstrates the promising lithium insertion characteristics of the nanometer-sized core–shell maghemite/PPy particles prepared under optimized conditions for application in secondary batteries.     

Nitrogen removal in an upflow sludge blanket (USB) reactor combined by aerobic biofiltration systems.

A new nitrogen removal process (up-flow sludge blanket and aerobic filter, USB-AF) was proposed and tested with real sewage. In the USB reactor, the larger part of influent organic and nitrogen matters were removed, and ammonia was effectively oxidized in the subsequent aerobic filter. The role of the aerobic filter was to convert ammonia into nitrate, an electron acceptor that could convert soluble organic matters into volatile suspended solid (VSS) in the USB. The accumulated as well as influent VSS in the USB was finally degraded to fermented products that were another good carbon source for denitrification. Total COD, settleable COD and soluble COD in the raw sewage were 325, 80 and 140 mg/l, respectively. Most unsettleable COD as well as some SCOD in the influent was successfully removed in the USB. TCOD removal in the anoxic filter was by denitrification with the recycled nitrate. Low COD input to the aerobic filter could increase nitrification efficiency, reduce the start-up period and save the aeration energy in the USB-AF system. About 95% of ammonia was nitrified in the aerobic filter with no relation to the influent ammonia concentration. Denitrification efficiency of the recycled nitrate in the anoxic filter was about 85, 83, and 72% at recycle ratios of 100, 200, and 300%, respectively. T-N removal efficiency was 70% at recycle ratio of 300%.     

Cell Adhesion and in Vivo Osseointegration of Sandblasted/Acid Etched/Anodized Dental Implants

The authors describe a new type of titanium (Ti) implant as a Modi-anodized (ANO) Ti implant, the surface of which was treated by sandblasting, acid etching (SLA), and anodized techniques. The aim of the present study was to evaluate the adhesion of MG-63 cells to Modi-ANO surface treated Ti in vitro and to investigate its osseointegration characteristics in vivo. Four different types of Ti implants were examined, that is, machined Ti (control), SLA, anodized, and Modi-ANO Ti. In the cell adhesion study, Modi-ANO Ti showed higher initial MG-63 cell adhesion and induced greater filopodia growth than other groups. In vivo study in a beagle model revealed the bone-to-implant contact (BIC) of Modi-ANO Ti (74.20% ± 10.89%) was much greater than those of machined (33.58% ± 8.63%), SLA (58.47% ± 12.89), or ANO Ti (59.62% ± 18.30%). In conclusion, this study demonstrates that Modi-ANO Ti implants produced by sandblasting, acid etching, and anodizing improve cell adhesion and bone ongrowth as compared with machined, SLA, or ANO Ti implants. These findings suggest that the application of Modi-ANO surface treatment could improve the osseointegration of dental implant.     

Volatility behavior of oil,industrial commodity and stock markets in a regime-switching environment

This study supplements previous regime-switching studies on WTI crude oil and finds two possible volatility regimes for the strategic commodity prices of Brent oil, WTI oil, copper, gold and silver, and the S&P 500 index, but with varying high-to-low volatility ratios. The dynamic conditional correlations (DCCs) indicate increasing correlations among all the commodities since the 2003 Iraq war but decreasing correlations with the S&P 500 index. The commodities also show different volatility persistence responses to financial and geopolitical crises, while the S&P 500 index responds to both financial and geopolitical crises. Implications are discussed.     

Chemical vapor synthesis and characterization of aluminum nanopowder

Aluminum is a component in many promising hydrogen storage materials such as aluminum hydride and complex aluminum hydrides. In this research, Al and TiAl₃-containing Al nanopowders were prepared by a chemical vapor synthesis (CVS) process using Mg as the reducing agent. XRD and EDS results indicated that the produced powder was composed of Al or Al with TiAl₃. The shape of the powder was spherical with the average size in the range of 10-50 nm measured by SEM, TEM, BET and ZetaPALS compared with the typically larger than 100 nm for commercially available fine Al powders. In addition, the effects of the operating conditions such as Ar flow rate, precursor feed rate and reaction temperature on the properties of the product powder were investigated.     

Cycling performance of a lithium-ion polymer cell assembled by in-situ chemical cross-linking with fluorinated phosphorous-based cross-linking agent

Lithium-ion polymer cells composed of a carbon anode and a LiCoO₂ cathode are assembled with a gel polymer electrolyte cured by in-situ chemical cross-linking with novel cross-linking agents. The strong interfacial adhesion between the electrodes and the porous polyethylene membrane by the chemical cross-linking results in the stable capacity retention of the cell. However, a reduction in the ionic mobility in both the electrolyte and the electrodes adversely affects the high rate performance of the cell. These results imply that proper control of the cross-linking density in the cell is imperative for achieving good capacity retention and high rate performance of the cell.     

Long-term performance of anode-supported SOFC integrated with metal interconnect by joining process

Using relatively simple and cheap joining process, anode-supported solid oxide fuel cell integrated with metal interconnect is fabricated and its impedance spectra are analyzed and compared with anode-supported cell at the operating temperature of 800 °C. The stable long-term performance is shown for about 800 h at 800 °C under the constant current density of 300 mA cm⁻². The thermal cycle experiments from the operating temperature to the room temperature are also carried out in this study, while the maximum power density of 0.7 W cm⁻² is indicated. The microstructures are analyzed using scanning electron microscope and energy dispersive X-ray spectra are analyzed for observing a diffusion of metal ions at the anode, adhesion layer and metal support.     

Design optimization of a laser printer cleaning blade for minimizing permanent set

When a cleaning blade in a laser printer is excessively deformed, immoderate permanent set can result, leading to weaker nip pressure between the cleaning blade and OPC drum that worsens its cleaning performance and printing quality. In this study, the correlation of the permanent set with stress and strain was investigated through tensile tests with rubber test specimens. Based on the experimental results, the maximum von-Mises stress value was used to quantify the permanent set. A design optimization problem was formulated to minimize the maximum von-Mises stress while satisfying the design constraints for maintaining appropriate contact between the cleaning blade and the OPC drum. We employed metamodel-based design optimization using design of experiments, metamodeling and an optimization algorithm to circumvent the difficulty of structural analyses at some design points. Using the proposed design approach, the optimal maximum von-Mises stress was reduced by 40.2 % compared to the initial stress value while all the design constraints were satisfied. In order to verify the validity of our design optimization result, we manufactured the cleaning blades according to the optimum design solution and performed permanent set and printer tests. The test results clearly showed the validity of our design optimization result.     

A quasi-two-dimensional electrochemistry modeling tool for planar solid oxide fuel cell stacks

A quasi-two-dimensional numerical model is presented for the efficient computation of the steady-state current density, species concentration, and temperature distributions in planar solid oxide fuel cell stacks. The model reduction techniques, engineering approximations, and numerical procedures used to simulate the stack physics while maintaining adequate computational speed are discussed. The results of the model for benchmark cases with and without on-cell methane reformation are presented with comparisons to results from other research described in the literature. Simulations results for a multi-cell stack have also been demonstrated to show capability of the model on simulating cell to cell variation. The capabilities, performance, and scalability of the model for the study of large multi-cell stacks are then demonstrated.