salicylideneaminospironaphthoxazines bifunctional photochromic: Topics by WorldWideScience.org

Research and development project in fiscal 1989 for fundamental technologies for next generation industries. Achievement report on research and development on photoreactive materials (Research on function separating type photochromic materials); 1989 nendo hikari hanno zairyo no kenkyu kaihatsu seika hokokusho. Kino bunrigata photochromic zairyo ni kansuru kenkyu

Ring opening dynamics of diarylethene derivative (BTF6) in n-hexane are studied by femtosecond transient absorption and time resolved spontaneous fluorescence techniques. Cyclo-reversion time constant is obtained.

2001-11-01

Solvothermal Synthesis of a New Photochromic Azo Polymer and its Self-assembly Behavior

Research and development has been performed on photochromic materials expected to be used in ultra-high density recording, high resolution indication and photoswitches. With regard to molecular orientation in the ternary system mixed LB film, the result of structural analysis by XPM spectrum revealed that the acceptor constituent in the LB film is so structured that it is separated and laminated with two other constituents, and that the sensitizer constituent and the donor constituent are not recognized of being separated definitely. Regarding the electron movement reaction in the solid phase system, a photo-current measuring experiment was carried out on the laminated film which is vacuum-deposited with the ternary system comprising of the donor, sensitizer, and acceptor. It was concluded that the observed photo-current reflects the electron movement reaction in the solid phase as it is. For the photo-current in the LB film, increase in the photo-current was ...

1990-03-01

British Library Electronic Table of Contents (United Kingdom)

An amphiphilic azobenzene diblock copolymer {2-[4-(4-methoxy phenyl azo)phenoxy]hexyl acrylate co-acrylic acid} was synthesized via reversible addition-fragmentation chain transfer polymerization in a hydrothermal reactor. The products were characterized by 1H-NMR, DSC, GPC and UV-Vis spectroscopy. Different self-assembly behaviors of this amphiphilic diblock copolymer in different organic solvent with different water content were investigated. In THF/H2O solution, the diblock copolymer self-assembled into spheres and the spheres would then change to vesicles with smaller size by increasing the volume of H2O. However, in DMSO/H2O solution, the sizes and morphologies of the self-assembled spheres would not change significantly with an enhanced amount of H2O. Photochromic behaviors of the am...

2010-01-01

Evaluation of carbon substrates for bifunctional air electrodes applied in zinc-air-batteries

Phosphorylation of Annexin A1 by TRPM7 Kinase: A Switch Regulating the Induction of an ?-Helix

The key component for improving the energy efficiency and cycle life of the electrically rechargeable zinc-air battery is the bifunctional air electrode. The air electrodes described in this paper contained different types of carbon black as the substrate for the perovskite catalyst (La{sub 0.6}Ca{sub 0.4}CoO{sub 3}). Morphological and physical properties of the carbon substrates play an important role in enhancing the activity and stability of the bifunctional air electrode. Current-potential curves and cycle-life tests were applied in order to gather information on the activity and stability of these electrodes. (authors)

2000-07-01

Thio Wax Ester Biosynthesis Utilizing the Unspecific Bifunctional Wax Ester Synthase/Acyl Coenzyme A:Diacylglycerol Acyltransferase of Acinetobacter sp. Strain ADP1

TRPM7 is an unusual bifunctional protein consisting of an α-kinase...Full Text Available

2011-03-29

Induction of an abortive and futile DNA repair process in E. coli by the antitumor DNA bifunctional intercalator, ditercalinium: role in polA in death induction.

The bifunctional wax ester synthase/acyl coenzyme A (acyl-CoA):diacylglycerol acyltransferase (WS/DGAT) from Acinetobacter sp. strain ADP1 (formerly Acinetobacter calcoaceticus...Full Text Available

2005-02-01

Evolution of a bifunctional enzyme: 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

Ditercalinium, an antitumor bifunctional intercalator which forms a high affinity reversible complex with DNA, was found to be specifically cytotoxic for polA and lig7 E. coli strains. In the polA strain,...Full Text Available

1988-02-11

Phosphoglycerate kinase and triosephosphate isomerase from the hyperthermophilic bacterium Thermotoga maritima form a covalent bifunctional enzyme complex.

The bifunctional rat liver enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (ATP:D-fructose-6-phosphate 2-phosphotransferase/D-fructose-2,6-bisphosphate 2-phosphohydrolase, EC 2.7.1.105/EC...Full Text Available

1989-12-01

Construction of a novel bifunctional biogenic amine receptor by two point mutations of the H2-histamine receptor.

Phosphoglycerate kinase (PGK) from the hyperthermophilic bacterium Thermotoga maritima has been purified to homogeneity. A second larger enzyme with PGK activity and identical N-terminal sequence was...Full Text Available

1995-02-01

A Bifunctional Geranyl and Geranylgeranyl Diphosphate Synthase Is Involved in Terpene Oleoresin Formation in Picea abies1[W][OA

BACKGROUND: H2-histamine receptors mediate a wide range of physiological functions extending from stimulation of gastric acid secretion to induction of human promyelocyte differentiation. We have previously...Full Text Available

1995-03-01

Synthesis, characterization, and evaluation of a novel bifunctional chelating agent for the lead isotopes {sup 203}Pb and {sup 212}Pb

The conifer Picea abies (Norway spruce) defends itself against herbivores and pathogens with a terpenoid-based oleoresin composed chiefly of monoterpenes (C₁₀) and diterpenes...Full Text Available

2010-02-01

Synthesis, characterization, and evaluation of a novel bifunctional chelating agent for the lead isotopes "2"0"3Pb and "2"1"2Pb

Radioisotopes of Pb(II) have been of some interest in radioimmunotherapy and radioimmunoimaging (RII). However, the absence of a kinetically stable bifunctional chelating agent for Pb(II) has hampered its use for these applications. {sup 203}Pb (T{sub 1/2}=52.02 h) has application potential in RII, with a {gamma}-emission that is ideal for single photon emission computerized tomography, whereas {sup 212}Pb (T{sub 1/2}=10 h) is a source of highly cytotoxic {alpha}-particles via its decay to its {sup 212}Bi (T{sub 1/2}=60 min) daughter. The synthesis of the novel bifunctional chelating agent 2-(4-isothiocyanotobenzyl)-1,4,7,10-tetraaza-1,4,7,10-tetra-(2-carbamoyl methyl)-cyclododecane (4-NCS-Bz-TCMC) is reported herein. The Pb[TCMC]{sup 2+} complex was less labile to metal ion release than Pb[DOTA]{sup 2-} at pH 3.5 and below in isotopic exchange experiments. In addition to increased stability to Pb{sup 2+} ion release at low pH, the ...

2000-01-01

Nucleotide sequence and genetic analysis of a 13.1-kilobase-pair Pseudomonas denitrificans DNA fragment containing five cob genes and identification of structural genes encoding Cob(I)alamin adenosyltransferase, cobyric acid synthase, and bifunctional cobinamide kinase-cobinamide phosphate guanylyltransferase.

Radioisotopes of Pb(II) have been of some interest in radioimmunotherapy and radioimmunoimaging (RII). However, the absence of a kinetically stable bifunctional chelating agent for Pb(II) has hampered its use for these applications. "2"0"3Pb (T_1_/_2=52.02 h) has application potential in RII, with a #gamma#-emission that is ideal for single photon emission computerized tomography, whereas "2"1"2Pb (T_1_/_2=10 h) is a source of highly cytotoxic #alpha#-particles via its decay to its "2"1"2Bi (T_1_/_2=60 min) daughter. The synthesis of the novel bifunctional chelating agent 2-(4-isothiocyanotobenzyl)-1,4,7,10-tetraaza-1,4,7,10-tetra-(2-carbamoyl methyl)-cyclododecane (4-NCS-Bz-TCMC) is reported herein. The Pb[TCMC]"2"+ complex was less labile to metal ion release than Pb[DOTA]"2"- at pH 3.5 and below in isotopic exchange experiments. In addition to increased stability to Pb"2"+ ion release at low pH, the bifunctional TCMC ...

2000-01-01

Biophysical analysis of DNA modified by 1,2-diaminocyclohexane platinum(II) complexes

A 13.1-kb DNA fragment carrying Pseudomonas denitrificans cob genes has been sequenced. The nucleotide sequence and genetic analysis revealed that this fragment contained five different cob genes named...Full Text Available

1991-10-01

Solution-based characterization of surface-enhanced Raman response of single scattering centers

Modification of DNA and double-stranded deoxyoligonucleotides with antitumor 1,2-diamino-cyclohexanedinitroplatinum(II) (Pt-dach) complexes was investigated with the aid of physico-chemical methods and chemical probes of nucleic acid conformation. The three Pt-dach complexes were used which differed in isomeric forms of the dach non-leaving ligand-Pt(1R,2R-dach), Pt(1S,2S-dach) and Pt(1R,2S-dach) complexes. The latter complex has lower antitumor activity than the other two Pt-dach complexes. Pt(1R,2S-dach) complex exhibits the slowest kinetics of its binding to DNA and of the conversion of monofunctional binding to bifunctional lesions. The anomalously slow electrophoretic mobility of multimers of the platinated and ligated oligomers suggests that bifunctional binding of Pt-dach complexes to a d(GG) site within double-stranded oligonucleotides induces bending of the oligomer. It is proposed that different effects of the Pt-dach complexes on DNA ...

1992-01-25

Progress towards a 20 Ah/12 V zinc/air battery

We demonstrate the rapid optical characterization of large numbers of individual metal nanoparticles freely diffusing in colloidal solution by confocal laser spectroscopy. We find that hollow gold nanospheres and solid silver nanoparticles linked with a bifunctional ligand, both designed nanostructures, exhibit significantly higher monodispersity in their Rayleigh and Raman scattering response than randomly aggregated gold and silver nanoparticles. We show that measurements of rotational diffusion timescales allow sizing of particles significantly more reliably than can be obtained using translational diffusion timescales.

2008-03-06

Development and cycle test of zinc-oxygen cells

Electrode areas, for the bifunctional O{sub 2}-electrodes and the pasted Zn-electrodes, have been successfully scaled up from 25 cm{sup 2} up to 250 cm{sup 2}. A filter press type cell was used to measure the cycle life of larger electrodes (100 cm{sup 2}). Up to now, more than 100 charge-discharge cycles (900 hours) with these scaled up Zn/O{sub 2}-cells could be demonstrated. (author) 2 figs., 2 refs.

1997-06-01

Zinc/air battery R and D research and development of bifunctional oxygen electrode: Tasks I and II, Final report

For the development of a rechargeable zinc/air battery, La{sub 0.6}Ca{sub 0.4}CoO{sub 3}-catalyzed (perovskite) bifunctional oxygen electrodes and pasted zinc electrodes were prepared and tested in monopolar zinc/air cells. The cells were cycled in moderately alkaline electrolyte. The maximum power as well as the cycle life of the cells were investigated. Up to 450 cycles could be reached, and attractive specific energies and powers were obtained. (author) 3 figs., 4 refs.

1995-07-01

Alkaline rechargeable zinc-air battery; Alkalische wiederaufladbare Zink-Luft Batterie

Studies were conducted of the bifunctional oxygen electrode. The development of a rechargeable metal-oxygen (air) cell has been hampered to a great extent by the lack of a stable and cost effective oxygen electrode capable of use during both charge and discharge. The first type of bifunctional electrode consists of two distinct catalytifc layers. The oxygen reduction catalyst layer containing a supported gold catalyst is in contact with a hydrophilic nickel layer in which evolution of oxygen takes place. Loadings of gold from 0.5 to 1.0 mg/cm/sup 2/ were investigated; carbon, graphite, metal, and spinel oxides were evaluated as substrates. The second part of the research effort was centered on developing a reversible oxygen electrode containing only one catalytic layer for both reduction and evolution of oxygen. The work was directed specifically to the study of perovskite type of oxides with the composition AA/sup 1/BO/sub 3/ where A is an ...

1986-12-01

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Enhanced antibacterial activity of bifunctional Fe3O4-Ag core-shell nanostructures

Because of its high energy density, compatibility with aqueous electrolytes and the low toxicity of its active materials, the zinc-air battery system is an interesting candidate for electric vehicle applications. The use of O{sub 2} from the air as a reactant requires a partially open cell construction and a technologically challenging air interface. This report describes the research and development program at the Paul Scherrer Institute which finally led to the demonstration of a durable, electrically rechargeable zinc-oxygen battery. In a first phase the research program was focused on the development of bifunctional oxygen diffusion electrodes and pasted zinc electrodes. The current-potential behaviour and the cycle life performance of anodes and cathodes was tested in single electrode measurements (three-electrode arrangements) as well as in complete monopolar zinc-oxygen and zinc-air cells. La{sub 0.6}Ca{sub 0.4}CoO{sub 3}-activated ...

1996-11-01

British Library Electronic Table of Contents (United Kingdom)

We describe a simple one-pot thermal decomposition method for the production of a stable colloidal suspension of narrowly dispersed superparamagnetic Fe3O4-Ag core-shell nanostructures. These biocompatible nanostructures are highly toxic to microorganisms. Antimicrobial activity studies were carried out on both Gram negative (Escherichia coli and Proteus vulgaris) and Gram positive (Bacillus megaterium and Staphylococcus aureus) bacterial strains. Efforts have been made to understand the underlying molecular mechanism of such antibacterial actions. The effect of the core-shell nanostructures on Gram negative strains was found to be better than that observed for silver nanoparticles. The minimum inhibitory concentration (MIC) values of these nanostructures were found to be considerably lowe...

2009-01-01

Development of rechargeable monopolar and bipolar zinc/air batteries

Novel bifunctional natriuretic peptides as potential therapeutics.

For the development of a rechargeable zinc/air battery, La[sub 0.6]Ca[sub 0.4]CoO[sub 3]-catalyzed (perovskite) bifunctional oxygen electrodes and pasted zinc electrodes were prepared and tested in monopolar zinc/air cells. In addition, a bipolar Zn/air stack was tested using reticulated copper foam as substrate for the zinc deposit. The cells were cycled in moderately alkaline ZnO-saturated electrolyte with KF as an electrolyte additive. The maximum power as well as the cycle life of the cells was investigated. The differences in porosity of the zinc electrode before and after the long-term test were analyzed using mercury porosimetry. (author) 8 figs., 13 refs.

1995-01-01

Science.gov (United States)

Synthetic atrial natriuretic peptide (carperitide) and B-type natriuretic peptide (BNP; nesiritide) are used to treat congestive heart failure. However, despite beneficial cardiac unloading properties, reductions in renal perfusion pressures limit their clinical effectiveness. Recently, CD-NP, a chimeric peptide composed of C-type natriuretic peptide (CNP) fused to the C-terminal tail of Dendroaspis natriuretic peptide (DNP), was shown to be more glomerular filtration rate-enhancing than BNP in dogs. However, the molecular basis for the increased responsiveness was not determined. Here, we show that the DNP tail has a striking effect on CNP, converting it from a non-agonist to a partial agonist of natriuretic peptide receptor (NPR)-A while maintaining the ability to activate NPR-B. This effect is specific for human receptors because CD-NP was only a slightly better activator of rat NPR-A due to the promiscuous nature of CNP in this species. Interesting, the DNP tail alone had no effect ...

2008-10-21

Support effects on CO hydrogenation over Ru/zeolite catalysts

Silver nanoparticle-decorated carbon nanotubes as bifunctional gas-diffusion electrodes for zinc-air batteries

Hydrogenation of carbon monoxide at 101.3 kPa has been studied over a series of ion-exchanged Ru catalysts supported on NaX, NaY, KL, Na mordenite, and HY zeolites. The type of zeolite had pronounced effects on the activity and selectivity of the Ru. The specific activity would appear to be related to the dispersion of reduced ruthenium in the zeolite. Methane selectivity, however, seems to be strongly influenced by the type and concentration of alkali cations remaining in the ion-exchanged zeolite. These cations appear to promote chain growth much as traditional alkali promoters would, though perhaps more indirectly. Due to bifunctional properties of the zeolite-supported catalysts, a significant fraction of C/sub 4/ was in the form of isobutane. Formation of isobutane seems to be related to either the Si/Al ratio in the zeolites or the concentration of the remaining alkali cations, but not to the OH concentration. In addition, H/sub 2/ chemisorption at 25/sup 0/C ...

1984-02-01

Nitroimidazole conjugates of bis(thiosemicarbazonato)64Cu(II) - Potential combination agents for the PET imaging of hypoxia

Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence may be useful for ...

2010-07-01

British Library Electronic Table of Contents (United Kingdom)

Combination agents comprising two different pharmacophores with the same biological target have the potential to show additive or synergistic activity. Bis(thiosemicarbazonato)copper(II) complexes (e.g. 64Cu-ATSM) and nitroimidazoles (e.g. 18F-MISO) are classes of tracer used for the delineation of tumor hypoxia by positron emission tomography (PET). Three nitroimidazole-bis(thiosemicarbazonato)copper(II) conjugates were produced in order to investigate their potential as combination hypoxia imaging agents. Two were derived from the known bifunctional bis(thiosemicarbazone) H2ATSM/A and the third from the new precursor diacetyl-2-(4-N-methyl-3-thiosemicarbazone)-3-(4-N-ethylamino-3-thiosem icarbazone) - H2ATSM/en. Oxygen-dependent uptake studies were performed using the 64Cu radiolabelled ...

2010-01-01

New polysaccharide-based polymer electrolytes; Nouveaux electrolytes polymeres a base de polysaccharides

In vivo evaluation of a lead-labeled monoclonal antibody using the DOTA ligand

Polysaccharides like cellulose and chitosan are known for their filmic properties. This paper concerns the synthesis and the study of chitosan-based polymer electrolytes. A preliminary work concerns the study of glucosamine reactivity. The poly-condensation of chitosan ethers (obtained by reaction with ethylene oxide or propylene oxide) with bifunctional and monofunctional oligo-ethers leads to the formation of thin lattices (10 {mu}m) having excellent mechanical properties. The presence of grafted polyether chains along the polysaccharide skeleton allows to modify the vitreous transition temperature and the molecular disorder of the system. Two type of polymer electrolytes have been synthesized: electrolytes carrying a dissolved alkaline metal salt and ionomers. The analysis of their thermal, dynamical mechanical, nuclear magnetic relaxation, electrical, and electrochemical properties shows that this new class of polymer electrolytes has the same performances as ...

1996-12-31

Feasibility study of a new zinc-air battery concept using flowing alkaline electrolyte

The aim of this study was to assess the utility of a radioimmunoconjugate containing a lead radionuclide for therapy and scintigraphy applications. The radioimmunoconjugate evaluated consisted of a bifunctional DOTA ligand and monoclonal antibody (MAb) B72.3 using athymic mice bearing LS-174T tumors, human colon carcinoma xenografts. In the studies reported here, the lead-203-DOTA complex itself was first demonstrated to have in vivo stability. MAb B72.3 was then conjugated with the DOTA ligand and labeled with "2"0"3Pb, and the immunoreactivity of B72.3 was maintained. The localization of the radioimmunoconjugate to tumor tissue and other select organs paralleled that of DOTA-"1"2"5I-B72.3, suggesting a similar metabolic pattern of the two radioimmunoconjugates. Thus, the DOTA-metal complex does not alter the behavior of the radioimmunoconjugate. Tumor localization of the "2"0"3Pb-DOTA-B72.3 conjugate was demonstrated with biodistribution studies as well as ...

1998-05-01

Catalytic behavior of Co/(Nanob-Zeolite) bifunctional catalysts for Fischer-Tropsch reactions

Proof-of-principle experiments are reported for a new concept in electrically rechargeable zinc-air battery. The zinc electrode is a porous flow-thru type using a copper foam metal substrate with zinc deposition onto the foam metal from concentrated zincate electrolyte (as used in zinc-slurry type batteries). The bifunctional air electrode employs low-cost materials, being fabricated entirely from carbon-based precursors and small amounts of nickel and/or cobalt oxide. Corrosion measurements on the graphite materials in the air electrode indicate sufficient corrosion resistance for 8000 h life on charge. A prototype single cell was constructed having 1.5 Ah capacity producing 1.2 V discharge -2.0 charge at the three hour rate and has produced stable voltages for more than 150 cycles. Based on the 1.5 Ah prototype characteristics, design calculations for a 32 kWh battery project an energy density of about 110 Wh/kg, peak power density of 140 W/kg, electrical ...

1986-04-01

British Library Electronic Table of Contents (United Kingdom)

Cobalt supported on Beta zeolite catalysts were prepared by impregnation of metal salts in aqueous solution and were tested for the Fischer Tropsch reaction. The support consisted of a Beta zeolite composed by crystallites of nanometric dimensions and a SiO2/Al2O3 molar ratio of about 50. This support was impregnated with Co(NO3)2 aqueous solution using different metal loads of 7.5, 10, 15 and 20wt% Co. These materials were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), N2 adsorption (BET), thermal programmed reduction (TPR) and FTIR of adsorbed pyridine (i.e., surface acid sites distribution). All the catalysts showed a significant catalytic activity for the F-T reaction from synthesis gas (CO+2H2), in a continuous fixed bed reactor sys...

2011-01-01

Bi-functional oxygen electrodes using Pr-Mn-Fe-based perovskite-type oxides as catalysts

Masking of trace metal contaminants with citrate in the In-111 labeling of Mab-DTPA

To develop oxygen electrodes for rechargeable metal-air batteries, the electrochemical behaviour of gas-diffusion-type carbon electrodes loaded with Pr-Mn-Fe-based perovskite-type oxides was examined for the reduction and evolution of oxygen in 8 M KOH at 60 C. Among the oxides tested, Pr{sub 0.2}Ca{sub 0.8}Mn{sub 0.1}Fe{sub 0.9}O{sub 3} gave the highest electrode performances, e.g., current densities of 275 mA/cm{sup 2} (for oxygen reduction) and 225 mA/cm{sup 2} (for oxygen evolution) at -300 and +650 mV vs. Hg/HgO, respectively. The electrode performances were found to depend on both the catalytic activity of the oxides for H{sub 2}O{sub 2} decomposition reaction and the amounts of oxygen desorbed from the oxides. Furthermore, it was confirmed that the small zinc-air battery including the gas-diffusion-type electrode loaded with Pr{sub 0.2}Ca{sub 0.8}Mn{sub 0.1}Fe{sub 0.9}O{sub 3} showed good discharge and charge characteristics. (orig.)

1999-07-01

Kinetics and FTIR studies of hydrocarbon synthesis on Pd/ZSM5 catalysts. Final report

Tumor imaging using radioiodinated monoclonal antibodies (Mab) suffered from rapid in vivo deiodination. This problem can be circumvented by covalent attachment of a bifunctional chelating group to the Mab followed by chelation with a suitable cationic radionuclide such as In-111. Competition of trace metal contaminants with In-111 for chelating sites, however, is known to lower the labeling yield. Since commercially available reagents may be contaminated with other trace metal ions, the effect of trace metals on Mab-DTPA chelation and the possibility of masking the trace metal effect on the In-111 labeling of Mab-DTPA were, therefore, investigated. Labeling yield of 93% was obtained when 1 mg (20mg/ml) of Mab F(ab')/sub 2/-DTPA (protein to DTPA ratio of --1) was allowed to incubate with 3 mCi In-111 in 2 ml acetate buffer (0.5M, pH 5.5) for 30 min. The yield was drastically decreased to 13-76% when the reactions were carried out with the addition of 1-2 #mu#g of ...

1985-06-02

A novel zinc-air battery for electric vehicles

Hydrocarbon synthesis during CO hydrogenation over Pd/M-ZSM5 (M=H,Na,La) and Pd/SiO/sub 2/ has been investigated. Overall activity depended on the cation-exchanged form of the support and decreased in the order Pd/La-ZSM5 = Pd/Na-ZSM5 > Pd/H-ZSM5 > Pd/SiO/sub 2/. The zeolite-supported catalysts showed high selectivity towards saturated C/sub 2/-C/sub 6/ hydrocarbons, whereas Pd/SiO/sub 2/ favored methanol production. Increasing temperature and H/sub 2//CO feed ratio led to higher reaction rates, lower yields of C/sub 2/-C/sub 6/ products, and increased lighter hydrocarbons. A mechanical mixture of Pd/SiO/sub 2/ and Na-ZSM5 showed similar product distribution as Pd/Na-ZSM5. Infrared spectra of the catalysts under reaction conditions indicate the presence of adsorbed oxygenates on the zeolite. Changes in the IR bands during the initial stages of the reaction suggest that surface species on the zeolite are not methanol synthesis intermediates. The effects of various temperatures and ...

1986-10-15

Investigation of dominant loss mechanisms in low-temperature polymer electrolyte membrane fuel cells

A new type of zinc electrode is matched with new bifunctional air electrodes to produce a zinc-air battery of a novel design. The zinc electrode is a flow-thru type made from copper foam-metal. The air electrode uses corrosion resistant carbon black as a high area support for a highly dispersed spinel oxide electrocatalyst. The battery design employs flowing electrolyte, 12 M KOH saturated or supersaturated with zincate. Single cells as large as 200 cm{sup 2} (1/5 EV design scale) having a capacity of 20 AH have been tested with C/4--C/16 constant current cycling. More extensive and realistic life cycle testing was done with 2 Ah cells, including the Simplified Federal Urban Driving Schedule (SFUDS) cycle. This testing has confirmed that these cells can provide the necessary transient power response required for urban EV applications. The cells achieved an average of 72 SFUDS repetitions (7.2 hrs) per discharge cycle, more than twice the number with a sealed lead ...

1995-07-01