The Effect of Sodium on the Catalytic Activity of ZnO-Al2O3/ZSM-5 and SnO-Al2O3/ZSM-5 for the Transesterification of Vegetable Oil with Methanol

In order to elucidate the effect of sodium on the activity of ZSM-5 supported metal oxides catalysts (ZnO-Al2O3/ZSM-5 and SnO-Al2O3/ZSM-5) for the transesterification of soybean oil with methanol, ZSM-5 supported metal oxides were prepared with and without sodium hydroxide by impregnation. The metal compositions of the ZSM-5 supported metal oxide catalysts and the metal concentrations dissolved from the catalysts to the methylester phase were measured by SEM-EDS and inductive coupled plasma spectroscopy, respectively. The catalytic activity of ZnO-Al2O3/ZSM-5 and SnO-Al2O3/ZSM-5 containing sodium did not originate from surface metal oxides sites, but from surface sodium sites or dissolved sodium leached from the catalyst surface

Effects of Preparative Parameters on the Structure and Performance of Ca-La Metal Oxide Catalysts for Oil Transesterification

The effects of preparative parameters on the surface basicity, composition, and transesterification activities of several Ca-La metal oxide catalysts were investigated. Four different preparation methods: ammonia-ethanol-carbon dioxide precipitation, physical mixing, impregnation, and co-precipitation, were studied. It was found that the ammonia-ethanol-carbon dioxide precipitation method resulted in the highest BET specific surface area, base strength and base site concentration. Moreover, catalyst surface composition and basicity are a function of calcination temperature, precipitants, pH, and molar ratio of Ca to La in precursor solution, and storage conditions. XRD, XPS, basicity and BET tests revealed that catalyst structure and dispersion of Ca species strongly influenced the catalyst activity. High surface concentration of Ca species, strong base strength and high concentration of base sites, and high specific surface area are characteristics of an active transesterification catalyst

Effect of surface modification of siliconeon Staphylococcus epidermidis adhesion and colonization

Cerebrospinal fluid (CSF) shunts for the treatment of hydrocephalus are generally made of silicone rubber. The growth of bacterial colonies on the silicone surface leads to frequent CSF shunt complications. A systematic study of the effect of the surface modification of silicone on Staphylococcus epidermidis adhesion and colonization was performed for different incubation times by means of colony counting and scanning electron microscopy (SEM). Silicone was modified with different biopolymers and silanes, including heparin, hyaluronan, octadecyltrichlorosilane (OTS), and fluoroalkylsilane (FAS) to provide a stable and biocompatible surface with different surface functional groups and degrees of hydrophobicity. The modified silicone surfaces were studied by using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). After 4 and 8 h of incubation, the FAS- and OTS-coated silicone and the hyaluronan coated OTS/silicone surfaces showed significantly reduced bacterial adhesion and colonization compared to blank silicone by both quantification methods. However, the heparin coated OTS/silicone showed significantly increased bacterial adhesion. These results indicate that the nature of the surface functional group and surface roughness determine the extent of bacterial adhesion and colonization. However, the degree of hydrophobicity of the surface did not appear to play a determining role in bacterial adhesion and colonization. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55980/1/30952_ftp.pd

Ternary Imidazolium-Pyrrolidinium-Based Ionic Liquid Electrolytes for Rechargeable Li-O 2 Batteries

The conductivity and anodic stability of ternary mixed ionic liquid (IL) electrolytes consisting of pyrrolidinium [N-butyl-Nmethylpyrrolidinium + (PYR 14 + )] and imidazolium [1-butyl-3-methylimidazolium + (BMIM + )] based bis(trifluoromethylsulfonyl) imide (TFSI − ) with 0.5 M LiTFSI salt were investigated. PYR 14 TFSI ionic liquid has been reported to be stable under an oxidative environment, while BMIMTFSI provides good ionic conductivity. A conductivity study of IL electrolytes revealed a linear correlation of conductivity as a function of IL -Li salt concentration and IL volume fraction. As a result, improved battery cycling in a mixture of 4:1 (80/20 v/v%) BMIM + : PYR 14 + was observed with a specific capacity of 330 mAh.g −1 over 50 cycles at a current density of 0.1 mA.cm −2 . Also, an EIS study revealed decreasing cathode polarization by demonstrating lower impedance values for ternary mixed electrolyte than that of the pure electrolytes upon cycling. The commercial potential of Li-O 2 rechargeable batteries is tremendous due to their extremely high theoretical energy density of 12 kWh.kg −1 (excluding oxygen), which is comparable to that of gasoline. 1 For automotive applications, Li-O 2 battery technology may be viable if it can provide 1.7 kWh.kg −1 of energy to the wheels after losses from the battery chemistry. However, this technology is suffering with several issues related to electrodes and electrolyte such as lithium metal corrosion, electrolyte decomposition, wettability, cathode structure retention, catalyst selection, among others, which result in a large irreversibility and poor cycle life. 1,2 Previous reports on electrolytes 3-5 suggest that conventional carbonate based electrolyte decomposes during the discharge process to produce irreversible byproducts such as alkyl carbonates and lithium carboxylates; and during the charging process, the oxidative decomposition of these byproducts 6 lead to CO 2 , CO, and other gases instead of O 2 . It has been found that this decomposition process is favored by the highly reactive superoxide radical anion (O 2 •− ) formed through single-electron reduction of oxygen (O 2 + e − → O 2 •− ). 9-11 Another polar solvent, dimethyl sulfoxide (DMSO), is not stable against a Li anode as it can absorb moisture from the air. 20 Although PYR 14 TFSI is stable, its high viscosity (100 centipoise) and low conductivity (1.4 × 10 −3 S cm −1 ) 21 limit the diffusion rate of lithium ions in the electrolyte. On the other hand, various imidazolium based molten salts have demonstrated better cyclability compared to pyrrolidinium in lithium batteries 22 because of the higher ionic conductivity and lower viscosity. Hence, a mixed imidazolium and pyrrolidinium based IL electrolyte could provide the stability and conductivity needed for both Liair and high power Li-ion batteries (LIB). For instance, a ternary ionic liquid: 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide, N-cyanoethyl-N,N,N-trimethylammonium bis(trifluoromethanesulfonyl)imide, and LiTFSI, exhibited a discharge capacity close z E-mail: [email protected] to the theoretical value with good compatibility with a LiCoO 2 cathode. 23 For Li-O 2 batteries, Cecchetto et al. investigated a mixture of PYR 14 TFSI: TEGDME-LiCF 3 SO 3 (1:1) and observed a lower overvoltage with higher conductivity for the electrolyte mixture than TEGDME alone. The present study aims to investigate ternary mixtures (IL 1 -IL 2 -Li-salt) of imidazolium and pyrrolidinium based ILs for Li-O 2 applications. BMIMTFSI was chosen as the imidazolium based IL as it has high ionic conductivity (4 mS.cm −1 ) and lower viscosity (32 centipoise), whereas, PYR 14 TFSI as a pyrrolidinium based IL as a stable solvent. Herein, different ternary mixtures of BMIMTFSI + PYR 14 TFSI + 0.5 M LiTFSI were prepared to study the effect of IL composition on ionic conductivity, electrochemical stability, lithium transference number, and Li-O 2 battery performance. It was found that 4:1 (BMIMTFSI:PYR 14 TFSI) mixed electrolyte enhanced both cyclic performance and columbic efficiency compared to BMIMTFSI or PYR 14 TFSI used alone. Experimental Ternary mixtures of electrolyte preparation.-1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl imide) (BMIMTFSI) (Sigma-Aldrich), and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR 14 TFSI) (TCI America) were used as room-temperature ionic liquids. The chemical structures are shown in Conductivity measurement.-Conductivity of all pure and mixtures of ILs were determined using a digital conductivity meter (VWR International, LLC, model 2052). All tests were measured at room temperature inside the glove box. Electrochemical stability measurement.-The electrochemical stability window of the LiTFSI-IL solutions was determined by linear sweep voltammetry (LSV) using a Gamry Reference 3000 Potentiosta

Performance and durability of a generator set CI engine using synthetic and petroleum based fuels for military applications

The long term performance and durability evaluation of a compression ignition (CI) engine of a diesel power generator using ultra-low sulfur diesel (ULSD) and Synthetic Paraffinic Kerosene, (S-8) fuels have been investigated under military specifications. The brake specific fuel consumptions (BSFC) were 0.308 ± 0.013 and 0.267 ± 0.019 kg/kW-h for ULSD and S-8, respectively. The corresponding brake thermal efficiencies (BTE) were 0.287 ± 0.002 and 0.309 ± 0.005. Degradation of engine performance or engine part wear was not observed during these test periods. Analysis of lubricating oil suggests negligible engine part wear. The frequency and power output of the generator, however, were not as stable with S-8 as those with ULSD. These power and frequency instabilities can be attributed to higher volatility and lower density and viscosity of S-8, all of which affect the fuel injection characteristics.Engine performance Synthetic fuel Fuel properties Lubricating oil Engine wear