Methanol decomposition to synthesis gas over supported Pd catalysts prepared from synthetic anionic clays

Supported Pd or Rh catalysts were prepared by the solid-phase crystallization method starting from hydrotalcite anionic clay minerals based on [Mg₆Al₂(OH)₁₆CO ₂ ²⁻ ]·4H₂O as the precursors. The precursors were prepared by a coprecipitation method from the raw materials containing Pd²⁺ and various trivalent metal ions which can replace each site of Mg²⁺ and Al³⁺ in the hydrotalcite. Rh³⁺ was also used for preparing the catalyst as comparison. The precursors were then thermally decomposed and reduced to form supported Pd or Rh catalysts and used for the methanol decomposition to synthesis gas. Among the precursors tested, use of Mg–Cr hydrotalcite containing Pd²⁺ resulted in the formation of efficient Pd supported catalysts for the production of synthesis gas by selective decomposition of methanol at low temperature. Although Pd²⁺ cannot well replace the Mg²⁺ site in the hydrotalcite, the Pd supported catalyst (Pd/Mg–Cr) prepared by the solid-phase crystallization method formed highly dispersed Pd metal particles and showed much higher activity than that prepared by the conventional impregnation method. When the precursor was prepared under mild conditions, more fine particles of Pd metal were formed over the catalyst, resulting in high activity. It is likely that the high activity may be due to the highly dispersed and stable Pd metal particles assisted by the role of Cr as the co-catalyst. This revised version was published online in November 2006 with corrections to the Cover Date.     

Geology and fluid chemistry of the Fushime geothermal field, Kyushu, Japan

The Fushime geothermal field is located in a depression close to the coast line. The system is characterized by very high reservoir temperature (>350°C), and a high salinity production fluid. Geological analysis shows that the main reservoir in this field occurs in a fractured zone developed around a dacite intrusion located in the center of the field. High permeability zones recognized by drilling data are found to be associated with fault zones. One of these zones is clearly associated with a NW–SE trending andesite dike swarm which was encountered in some wells.Alteration in the system can be divided into four zones, in order of increasing temperature, based on calcium–magnesium aluminosilicate mineral assemblages: i.e., the smectite, transition, chlorite and epidote zones. The feed zone is located in the chlorite and epidote zones, which can be further divided into three sub-zones according to their potassium or sodium aluminosilicate mineralogy, from the center of the discharge zone: K-feldspar–quartz, sericite–quartz, and albite–chlorite zones.Chloride concentration of the sea-water is 19,800 mg/l, and Br/Cl mole ratio is 1.55. Based on geochemical information, the reservoir chloride concentration of this field ranges from 11,600 to 22,000 mg/kg. The Clres (Cl in reservoir), Br/Cl ratios and stable isotope data indicate that the Fushime geothermal fluid originated from sea-water and is diluted by ground water during its ascent. Some fluids produced from geothermal wells show low pH (about 4). It is thought that sulfide mineral (PbS, ZnS) precipitation during production produces this acidic fluid.     

A case of coronary artery bypass grafting for effort angina in a patient with post skin grafting for an extramammary Paget's disease

The extramammary Paget's disease of anogenital area is rare, and is seen as a precancerous lesion or carcinoma in situ. In most cases, surgical treatment including dissection of regional lymph nodes, skin resection and grafting should be considered first. A 74-year-old male suffered from effort angina and underwent triple coronary artery bypass grafting (CABG) including saphenous vein graft (SVG) harvested from right lower leg. Five years previously he underwent skin grafting for extramammary Paget's disease of both inguinal areas and the perineal area. The postoperative course was uneventful and he was discharged 23 days after the CABG operation. Extramammary Paget's disease is localized in epidermis for years and there has been no report of direct invasion into vessels. Therefore, there appears to be no reason not to use an SVG if there is no luminal thrombus or occlusion.     

Monte Carlo analysis of the space-charge effect in AlGaAs/GaAsballistic collection transistors (BCTs) under high currentinjection

AlGaAs/GaAs ballistic collection transistors (BCTs) are investigated by self-consistent Monte Carlo simulation, focusing on the space-charge effect in the collector region. In addition to the conventional BCT collector structure (i-p⁺-n⁺), modified collector structures which have n^--p⁺-n ⁺ and p^--p⁺-n⁺ doping profiles are examined. By taking account of the fact that the collector delay time is composed of transit time and capacitance charging time, it is shown that the n^--p⁺-n⁺ collector structure is effective for the suppression of the base-widening effect (Kirk effect) compared to the i-p⁺-n⁺ or p^- -p⁺-n⁺ structure. Donors in the n^- layer compensate for the negative space charges produced by near-ballistic electrons. For a simulated BCT with an n^--p ⁺-n⁺ collector, the smaller collector capacitance charging time leads to improvement in current-gain cutoff frequency under high current injection     

WDM field trials of 43-Gb/s/channel transport system for optical transport network

This paper describes recent technical challenges and the progress toward the realization of the optical transport network (OTN) based on 43 Gb/s channel. We describe the new digital frame format "OTU3: Optical Channel Transport Unit 3," which is standardized in ITU-T for OTN, for the enhancement of the network management capability in the OTN based on 43-Gb/s channels. We first proposed 43-Gb/s/ch dense wavelength-division multiplexing (DWDM) dispersion-managed transmission system using carrier-suppressed return-to-zero (CS-RZ) format that has several attractive features; it advances the evolution of OTN into 100 GHz-spaced long-haul DWDM transport networks. The first wavelength-division multiplexing (WDM) field trials confirmed the superiority of CS-RZ format in the DWDM transmission performance for the first time. The first 1 Tb/s (25 /spl times/ 43 Gb/s) WDM field trial confirmed the excellent network management capability of OTU3 in future data-centric OTN using the newly developed 43-Gb/s OTN line-terminal prototype.     

A 128-kb FeRAM macro for contact/contactless smart-card microcontrollers

This paper describes a 128-kb FeRAM macro for smart-card microcontrollers. This macro, which was designed and fabricated using a 0.35-/spl mu/m three-metal CMOS and a Capacitor-on-Metal/Via-stacked-Plug (CMVP) process technology, is ideally suited for recent system LSIs such as smart-card microcontrollers. It has a flexible memory size ranging from 32 to 128 kb, a low consumption current of 0.3 mA, and endurance of more than 10/sup 8/ write/read cycles under a wide range of supply voltages, from 2.7 to 5.5 V. These characteristics, which are required of not only contact-type smart-card microcontrollers but also contactless-type ones, were achieved by using four newly developed circuit technologies: 1) a three-metal CMVP memory cell; 2) a voltage-regulating architecture; 3) a main/sub bitline and wordline structure; and 4) a dynamic-type offset sense amplifier.     

Determination of particulate organic carbon in waters by the chemical oxidation method

Particulate organic carbon (POC) in waters was determined by chemical oxidation method which has been widely used for the determination of total organic carbon and/or dissolved organic carbon. In this method, a water sample was filtered through a filter paper and the paper was placed in a glass ampoule, followed by the determination of POC with a total carbon analyzer. This paper discussed the problems of carbon contamination dissolving from filter papers. The selection of filter papers, the carbon blank values resulting from the papers and the pretreatment of the papers were studied. It became clear that the glass-fiber filter paper pretreated at 500°C for 8 h was superior to the filter papers treated under other conditions. The POC's in waters were determined by this method, and the results agreed well with those obtained by an ordinary dry combustion method.     

Pulse Combustors - Performance and Control

~nonEmphasising time characterishcs and contIDI, onlyfew workll'v is av'ailable among the numerous reports onPulse combustors. Rare work deals with tWin Pulsecombustorsls] or combined pulse combustor-"dinesystemsl']. Kenffield15] obtained with a combinedconvenhonal Pulse combustor-tulbine system acombushon Pressals gain of 3-7% and a totalPerformance Of the combustor-"dine system for Pulsecombushon 40% higher than that of steady'combushonwhat aught also be due tO the brine characteristics.…     

Use of liposome encapsulated hemoglobin as an oxygen carrier for fetal and adult rat liver cell culture

Engineering liver tissue constructs with sufficient cell mass for transplantation implies culturing large numbers of hepatocytes in a reduced volume; however, providing sufficient oxygen to dense cell cultures is still not feasible using only conventional culture medium. Liposome-encapsulated hemoglobin (LEH), an oxygen-carrying blood substitute originally designed for short-term perfusion, may be a good candidate as an oxygen carrier to cultured liver cells. In this study, we investigated the feasibility of maintaining long term hepatocyte cultures using LEH. Primary fetal and adult rat liver cells were directly exposed to LEH for 6 to 14 days in static culture or in a perfused flat plate bioreactor. The functions and viability of adult rat hepatocytes exposed to LEH were not adversely affected in static monolayer culture and were even improved in the bioreactor. However, some cytotoxicity of LEH was observed with fetal rat liver cells after 4 days of culture. LEH, though a suitable oxygen carrier for long-term culture of mature hepatocytes, is not suitable in its present form for perfusing fetal hepatocyte cultures in direct contact with the liposomes; either the LEH will have to be made less toxic or a more sophisticated bioreactor that prevents the direct contact between hepatocytes and perfusates will have to be designed if fetal cells are to be used for liver tissue engineering.     

Survey of pesticide residues in imported frozen vegetables and fruits (1989.4~2008.3)

A survey of pesticide residues in 595 imported frozen products on the Tokyo market from April 1989 to March 2008 was carried out. Forty three kinds of pesticides, including organophosphorus, organochlorine, carbamate, pyrethroid and others, were detected between levels of trace (below 0.01 ppm) and 4.6 ppm from 162 samples. Chlorpyrifos, cypermethrin and omethoate were frequently detected in green vegetables (komatsuna leaf and spinach), cypermethrin and methamidophos were detected in pods and seeds (green soybean and string pea), chlorpropham (CIPC) was detected in potato, and captan and carbaryl were detected in berries (blueberry, raspberry and strawberry). The hydrophilic pesticide methamidophos was detected in flesh of lychee. Residue levels of these pesticides were calculated as between less than 0.5% and 30% of their ADI values according to the daily intake of frozen products. Therefore, these frozen products should be safe when they were eaten in customary amounts.