Breakdown of oil films and formation of residual films

The breakdown processes of oil films under quasi-static loading have been investigated by using a newly developed steel-oil-mercury system. The relationship between the thickness and breakdown ratio of a hexadecane film is represented by a single master curve independently of the indentation speed, indentation load, and temperature. The master curve shows that the breakdown process of hexadecane includes two stages; one is the decrement of the thickness without breakdown and the other is the decrement of the thickness with a drastic progress of breakdown. By solving a small amount of fatty acid in hexadecane, the thickness increases and the breakdown ratio decreases noticeably; a multilayer residual film supporting normal load is formed between two metal surfaces. Experiments at different temperatures reveal a negative relationship between the temperature and thickness of residual film, which indicates that the residual film is organized by physical interaction rather than chemical interaction. At least under a lower concentration, the residual film appears to consist of not only fatty acid molecules but also hexadecane molecules.     

NiCoFe/C cathode electrocatalysts for direct ethanol fuel cells

A direct ethanol fuel cell (DEFC), which is less prone to ethanol crossover, is reported. The cell consists of PtRu/C catalyst as the anode, Nafion^® 117 membrane, and Ni–Co–Fe (NCF) composite catalyst as the cathode. The NCF catalyst was synthesized by mixing Ni, Co, and Fe complexes into a polymer matrix (melamine-formaldehyde resins), followed by heating the mixture at 800 °C under inert atmosphere. TEM and EDX experiments suggest that the NCF catalyst has alloy structures of Ni, Co and Fe. The catalytic activity of the NCF catalyst for the oxygen reduction reaction (ORR) was compared with that of commercially available Pt/C (CAP) catalyst at different ethanol concentrations. The decrease in open circuit voltage (V_oc) of the DEFC equipped with the NCF catalysts was less than that of CAP catalyst at higher ethanol concentrations. The NCF catalyst was less prone to ethanol oxidation at cathode even when ethanol crossover occurred through the Nafion^®117 film, which prevents voltage drop at the cathode. However, the CAP catalyst did oxidize ethanol at the cathode and caused a decrease in voltage at higher ethanol concentrations.     

IAEA activities on Mmall and Medium Reactors: Harmonization of energy demand and supply in developing countries

Small and Medium Reactors (SMRs) are attractive in developing countries because of their unique features such as: better suitability for smaller electric grids, lower investment cost, smaller components and equipment to facilitate modularization, etc. Furthermore, other factors induced by SMR implementation, such as technical transfer promotion, domestic infrastructure improvement, stabilization of energy cost, and environmental protection put SMRs into a more favorable position. From the nuclear plant suppliers, many SMR designs are available for a wide range of applications. A questionnaire study, which the IAEA conducted in 1996, confirmed that several countries are interested in SMRs and that some SMRs are already in the detailed design stage. A projection shows that the total nuclear capacity would increase in all regions that consist mainly of developing countries in the near future. For a timely and broad implementation of SMRs, information exchange and cooperation are indispensable between nuclear suppliers and buyers. The IAEA continues to play a role in encouraging and assisting development and practical application of SMRs for harmonization of energy demand and supply in developing countries.     

The influence of carboxylate ions on the growth of β-FeOOH particles

Colloidal -FeOOH particles were produced by hydrolysis of FeCl₃ solutions doped with varied amounts of formate, lactate, oxalate, tartarate, pyromellitate and EDTA ions at 100 °C. The resulting particles were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric-differential thermal analysis, Fourier transform-infrared spectroscopy, elemental analysis, and the adsorption of nitrogen and water. With increasing concentration of added carboxylate ions, the mean modal size of the particles formed increased at low concentrations and decreased after passing the maximum. The crystallite sizes also revealed a maximum on adding EDTA, oxalate and lactate ions, while they monotonically decreased with the addition of other ions. Doping with tartarate and pyromellitate ions by more than 7 and 10 mol%, respectively, produced amorphous particles containing a large amount of these ions. The particles formed with 20 mol% tartarate ions adsorbed water selectively.     

40-Gb/s packet-selective photonic add/drop multiplexer based on optical-code label header processing

A packet-by-packet-selective photonic add/drop multiplexer, of the finest data granularity, is experimentally demonstrated at 40 Gb/s. An optical-code label, attached to the packet, enables determination, in the optical domain, of whether to drop, cut through, or add packets.     

Transmission line with distributed erbium-doped fiber amplifier

We show the advantages of distributed erbium-doped fiber amplifiers (EDFAs) over lumped EDFAs. Using the distributed EDFA for 50%-100% of the transmission line lessens the signal degradation compared to the conventional transmission line. We also show the feasibility of the gain-flattened d-EDFA transmission line. An experiment shows that the gain peak is shifted and flattened at low pump powers     

Performance analysis of disk allocation method usingerror-correcting codes

The problem of distributing a Cartesian product file on multiple disks to maximize the parallelism for partial match queries is addressed. C. Faloutsos et al. (1989) have proposed an allocation method for Cartesian product files on multiple disks by using linear error-correcting codes. The performance of the allocation method is analyzed. Some conditions under which the allocation method is strictly optimal for queries with a given number of unspecified attributes are presented. A necessary and sufficient condition for a linear code to give a strictly optimal allocation method is discussed. Formulas for the average response time on queries with w unspecified attributes, denoted T_w, in terms of the weight distribution of the code or its dual code, and formulas for the average response time Ton all queries, are given. Several examples whose average response times T_w or T are close to theoretical lower bounds are presented     

Occurrence of multiple ethyl 4-chloro-3-oxobutanoate-reducing enzymes in Candida magnoliae

Multiple ethyl 4-chloro-3-oxobutanoate (COBE)-reducing enzymes were isolated from a cell-free extract of Candida magnoliae. A NADPH-dependent COBE-reducing enzyme, distinct from the carbonyl reductase and aldehyde reductase previously reported, was purified to homogeneity using five steps, including polyethylene glycol treatment. The relative molecular mass of the enzyme was estimated to be 86,000 on high performance gel-permeation chromatography and 29,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme catalyzed the reduction of COBE to the corresponding (S)-alcohol with a 51% enantiomeric excess. The substrate specificity of the enzyme was different from those of the other COBE-reducing enzymes of the same strain. The partial amino acid sequences of the enzyme showed that it belongs to the short chain alcohol dehydrogenase/reductase (SDR) family. This is the first report of multiple COBE-reducing enzymes with various stereoselectivities occurring in the same strain but belonging to different (super)families.     

Ultrahigh-speed driverless MQW intensity modulator, and 20 Gbit/s, 100 km transmission experiments

An InGaArInAlAs MQW modulator with the low voltage of 1.5 V for 10 dB extinction ratio and 16 GHz bandwidth has been developed. This ultrahigh-speed modulator enables the modulator driver to be eliminated from the transmitter. 100 km transmission experiments have been carried out using either a 1 V peak to peak output monolithic-IC-driven modulator at 15 Gbit/s or a 2 V peak to peak output multiplexer-driven modulator at 20 Gbit/s. This is the first report on multigigabit operation of MQW modulators to the authors' knowledge.<>     

Spectral restoration and energy resolution improvement of electron energy-loss spectra by Pixon reconstruction: II. Application to practical ELNES analysis of low SNR

We applied Pixon deconvolution as introduced in Part I to several practical, examples of low signal-to-noise ratio (SNR), electron energy-loss spectra with a goal toward restoring their fine spectral features and/or improving the energy resolution. We demonstrate that by directly fitting the two-dimensional spectral data recorded on the CCD; the method enables us to reveal fine spectral structures. Consequently, Pixon reconstruction extends the ability to probe electronic states in very spatially localized areas, a capability currently unique to our method.