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1

Development of Low-NOx Emission DME (Dimethyl Ether) Combustor  

NASA Astrophysics Data System (ADS)

This study focuses on fundamental characteristics of DME (Dimethyl Ether) combustion, aiming at the development of low-NOx combustion. DME is one of the most promising new alternative fuels owing to its cleanness of the exhaust gas and wide applications. Combustion experiments using a diffusion burner were conducted for characterizing DME through the comparison with the results of LPG and 13A-city gas. Experimental results demonstrated a high potential of DME for a boiler and a gas-turbine fuel. DME has a wide stable-combustion range compared with those of the other fuels. In this study, the concept of the low-NOx combustion, referred to as the tube-nested combustion, was applied to the DME combustion. This tube-nested combustor consists of tube banks to cool the burning flame leading to NOx reduction. Then, the NOx emission of the DME combustion was successfully reduced to a level suitable for practical applications.

Matsumoto, Ryosuke; Ishihara, Isao; Ozawa, Mamoru; Imahori, Keizo

2

DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT  

SciTech Connect

The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. Within the Combustion Laboratory of the Penn State Energy Institute, they have installed and equipped a Navistar V-8 direct-injection turbodiesel engine for measurement of gaseous and particulate emissions and examination of the impact of fuel composition on diesel combustion. They have also reconfigured a high-pressure viscometer for studies of the viscosity, bulk modulus (compressibility) and miscibility of blends of diesel fuel, dimethyl ether and lubricity additives. The results include baseline emissions, performance and combustion measurements on the Navistar engine for operation on a federal low sulfur diesel fuel (300 ppm S). Most recently, they have examined blends of an oxygenated fuel additive (a liquid fuel called CETANER{trademark}) produced by Air Products, for comparison with dimethyl ether blended at the same weight of oxygen addition, 2 wt.%. While they have not operated the engine on DME yet, they are now preparing to do so. A fuel system for delivery of DME/Diesel blends has been configured and initial investigations at low DME blend ratios (around 5-10 vol%) will begin shortly. They have also performed viscosity measurements on diesel fuel, DME and 50-50 blends of DME in diesel. These tests have verified that DME has a much lower viscosity than the diesel fuel and that the viscosity of the blended fuel is also much lower than the diesel base fuel. This has implications for the injection and atomization of the DME/diesel blends.

Elana M. Chapman; Shirish Bhide; Andre L. Boehman; David Klinikowski

2003-04-01

3

Dimethyl ether (DME) from coal as a household cooking fuel in China  

E-print Network

Dimethyl ether (DME) from coal as a household cooking fuel in China Eric D. Larson Princeton-1003, USA E-mail: hyy@princeton.edu Dimethyl ether (DME) has characteristics similar to liquefied petroleum gas (LPG) as a household cooking fuel. As such, DME is an attractive fuel for clean cooking. DME can

4

DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT  

SciTech Connect

The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The laboratory studies have included work with a Navistar V-8 turbodiesel engine, demonstration of engine operation on DME-diesel blends and instrumentation for evaluating fuel properties. The field studies have involved performance, efficiency and emissions measurements with the Champion Motorcoach ''Defender'' shuttle bus which will be converted to DME-fueling. The results include baseline emissions, performance and combustion measurements on the Navistar engine for operation on a federal low sulfur diesel fuel (300 ppm S). Most recently, they have completed engine combustion studies on DME-diesel blends up to 30 wt% DME addition.

Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Andre L. Boehman; David Klinikowski

2003-04-01

5

DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT  

SciTech Connect

The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. Their strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The bulk of the efforts over the past year were focused on the conversion of the campus shuttle bus. This process, started in August 2001, took until April 2002 to complete. The process culminated in an event to celebrate the launching of the shuttle bus on DME-diesel operation on April 19, 2002. The design of the system on the shuttle bus was patterned after the system developed in the engine laboratory, but also was subjected to a rigorous failure modes effects analysis (FMEA, referred to by Air Products as a ''HAZOP'' analysis) with help from Dr. James Hansel of Air Products. The result of this FMEA was the addition of layers of redundancy and over-pressure protection to the system on the shuttle bus. The system became operational in February 2002. Preliminary emissions tests and basic operation of the shuttle bus took place at the Pennsylvania Transportation Institute's test track facility near the University Park airport. After modification and optimization of the system on the bus, operation on the campus shuttle route began in early June 2002. However, the work and challenges continued as it has been difficult to maintain operability of the shuttle bus due to fuel and component difficulties. In late June 2002, the pump head itself developed operational problems (loss of smooth function) leading to excessive stress on the magnetic coupling and excessive current draw to operate. A new pump head was installed on the system to alleviate this problem and the shuttle bus operated successfully on DME blends from 10-25 vol% on the shuttle bus loop until September 30, 2002. During the period of operation on the campus loop, the bus was pulled from service, operated at the PTI test track and real-time emissions measurements were obtained using an on-board emissions analyzer from Clean Air Technologies International, Inc. Particulate emissions reductions of 60% and 80% were observed at DME blend ratios of 12 vol.% and 25 vol.%, respectively, as the bus was operated over the Orange County driving cycle. Increases in NOx, CO and HC emissions were observed, however. In summary, the conversion of the shuttle bus was successfully accomplished, particulate emissions reductions were observed, but there were operational challenges in the field. Nonetheless, they were able to demonstrate reliable operation of the shuttle bus on DME-diesel blends.

Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Howard Glunt; Andre L. Boehman; Allen Homan; David Klinikowski

2003-04-01

6

DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT  

SciTech Connect

The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethylether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The bulk of the efforts over the past year were focused on the conversion of the campus shuttle bus. This process, started in August 2001, took until April 2002 to complete. The process culminated in an event to celebrate the launching of the shuttle bus on DME-diesel operation on April 19, 2002. The design of the system on the shuttle bus was patterned after the system developed in the engine laboratory, but also was subjected to a rigorous failure modes effects analysis with help from Dr. James Hansel of Air Products. The result of this FMEA was the addition of layers of redundancy and over-pressure protection to the system on the shuttle bus. The system became operation in February 2002. Preliminary emissions tests and basic operation of the shuttle bus took place at the Pennsylvania Transportation institute's test track facility near the University Park airport. After modification and optimization of the system on the bus, operation on the campus shuttle route began in early June 2002. However, the work and challenges have continued as it has been difficult to maintain operability of the shuttle bus due to fuel and component difficulties. As of late June 2002, it appears that the pump head itself developed operational problems (loss of smooth function) leading to excessive stress on the magnetic coupling and excessive current draw to operate. A new pump head is being installed on the system to alleviate this problem and get the shuttle bus back in operation. In summary, the conversion is completed but there have been operational challenges in the field. They continue to work to make the shuttle bus as reliable to operate on DME-diesel blends as possible.

Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Howard Glunt; Andre L. Boehman; Allen Homan; David Klinikowski

2003-04-01

7

Catalytic dehydration of methanol to dimethyl ether (DME) over Pd\\/CabOSil catalysts  

Microsoft Academic Search

Ten wt.-% Pd\\/Cab-O-Sil reduced at 300°C has been found to be an effective catalyst for the catalytic dehydration of methanol to dimethyl ether (DME). The presence of hydrogen in the reagent stream inhibited the catalytic activity, but increased the stability of the catalyst. High reaction temperature and low methanol partial pressure did not favor DME formation.

Mingting Xu; D. Wayne Goodman; Alak Bhattacharyya

1997-01-01

8

Synthesis of dimethyl ether (DME) from methanol over solid-acid catalysts  

Microsoft Academic Search

The catalytic conversion of methanol to dimethyl ether (DME) has been studied over a series of solid-acid catalysts, such as ?-Al2O3, H-ZSM-5, amorphous silica-alumina, as well as titania modified zirconia. All the catalysts are active and selective for DME formation. The apparent activation energy for DME formation over ?-Al2O3 is ca. 25 kcal\\/mol, a value that increases to ca. 37

Mingting Xu; Jack H. Lunsford; D. Wayne Goodman; Alak Bhattacharyya

1997-01-01

9

Catalytic dehydration of methanol to dimethyl ether (DME) over solid-acid catalysts  

Microsoft Academic Search

A series of solid-acid catalysts with different components contents were prepared by coprecipitation (sol–gel) method. These samples comprised ?-alumina and modified ?-Al2O3 with silica. The effects of silica various contents have been investigated on purpose to determine an optimum one. Dehydration of methanol to dimethyl ether (DME) on solid-acid catalysts was studied in a fixed-bed flow reactor at a temperature

F. Yaripour; F. Baghaei; I. Schmidt; J. Perregaard

2005-01-01

10

Development of a Nuclear Hydrogen Production System by Dimethyl Ether (DME) Steam Reforming and Related Technology  

NASA Astrophysics Data System (ADS)

Targeting a hydrogen production system using heat produced by a nuclear reactor at about 300°C, we are developing a dimethyl ether (DME) steam reformer and hydrogen purification systems as well as catalysts for DME reforming. The use of heat from a nuclear reactor suppresses the CO2 concentration change in the atmosphere. In our developments, a catalyst, consisting of mixed oxides, produced hydrogen at a rate of about 1.9 Nm3/h per catalyst volume (m3) at about 300°C. Subsequently, the DME steam reformer achieved a hydrogen production rate of approximately, at least, 1.4 Nm3/h at about 300°C, by absorbing heat from the supplied steam. The aforementioned hydrogen production system via DME steam reforming is to be demonstrated using a thermal power plant. DME steam reforming by using waste heat and the utilization of the produced hydrogen within a combined cycle power plant can reduce fuel consumption, for instance, by about 17% compared to the case of direct DME combustion. The total system, with the use of DME, was compared with the methane case. If necessary, the byproduced CO2 may be injected into coal seams, increasing CH4 production via the substitution of CO2 for CH4 on coal, where CO2 adsorption is expected to be stronger than the CH4 adsorption.

Fukushima, Kimichika; Oota, Hiroyuki; Yamada, Kazuya; Makino, Shinichi; Yagyu, Motoshige; Ikeda, Tatsumi; Asayama, Masahiro; Ogawa, Takashi; Yoshino, Masato

11

An experimental study on the spray characteristics of diesel-dimethyl ether (DME) blended fuels by phase doppler anemometry  

Microsoft Academic Search

This paper presents an experimental study on the spray characteristics of diesel-dimethyl ether (DME) blended fuels by phase\\u000a doppler anemometry (PDA). Blended fuels with DME mass fractions of 15%, 30% and pure diesel fuel were used to evaluate the\\u000a effect of the DME concentration on the spray pattern, droplet size and velocity. The data for spray velocity vector and droplet

Jin Xiao; Zhen Huang; XinQi Qiao

2009-01-01

12

The potential of di-methyl ether (DME) as an alternative fuel for compression-ignition engines: A review  

Microsoft Academic Search

This paper reviews the properties and application of di-methyl ether (DME) as a candidate fuel for compression-ignition engines. DME is produced by the conversion of various feedstock such as natural gas, coal, oil residues and bio-mass. To determine the technical feasibility of DME, the review compares its key properties with those of diesel fuel that are relevant to this application.

Constantine Arcoumanis; Choongsik Bae; Roy Crookes; Eiji Kinoshita

2008-01-01

13

Experimental and analytical study on the spray characteristics of dimethyl ether (DME) and diesel fuels within a common-rail injection system in a diesel engine  

Microsoft Academic Search

This paper investigates the effect of injection parameters on the characteristics of dimethyl ether (DME) as an alternative fuel in a diesel engine with experimental and analytical models based on empirical equations. In order to study macroscopic and microscopic characteristics of DME fuel, this work focuses on the atomization characteristics of DME and compares experimental and predicted results for spray

Hyun Kyu Suh; Chang Sik Lee

2008-01-01

14

Critical solubility of dimethyl ether (DME)+diesel fuel and dimethyl carbonate (DMC)+diesel fuel  

Microsoft Academic Search

An experimental apparatus was developed for measuring the critical solubility. The critical solubilities were determined for binary mixtures of DME+diesel fuel and DMC+diesel fuel. For DME+diesel fuel their critical solubility temperatures ranged from 272.83 to 255.13K while the mass fractions of DME varied from 3.44 to 95.8%; For DMC+diesel fuel, their critical solubility temperatures were between 273.58 and 302.72K while

Xiaoming Zhao; Meifeng Ren; Zhigang Liu

2005-01-01

15

Auto-ignition during instationary jet evolution of dimethyl ether (DME) in a high-pressure atmosphere  

Microsoft Academic Search

The auto-ignition process during transient injection of gaseous dimethyl ether (DME) in a constant high-pressure atmosphere is studied experimentally by laser-optical methods and compared with numerical calculations. With different non-intrusive measurement techniques jet properties and auto-ignition are investigated at high temporal and spatial resolution. The open jet penetrates a constant pressure oxidative atmosphere of up to 4 MPa. During the

G. Fast; D. Kuhn; U. Maas

2009-01-01

16

Hydrodynamics of slurry bubble column during dimethyl ether (DME) synthesis: Gas–liquid recirculation model and radioactive tracer studies  

Microsoft Academic Search

Radioactive tracer measurements, using impulse injections of Ar41, powdered oxide of Mn56 and real catalyst particles doped with an oxide of Mn56, conducted at the Advance Fuels Development Unit (AFDU) slurry bubble column (BC) reactor during dimethyl ether (DME) synthesis (reactor pressure of 5.27MPa, reactor temperature of T=250?C, inlet superficial gas velocity of 17.1cm\\/s, and a catalyst loading of 36wt%)

P. Chen; P. Gupta; M. P. Dudukovic; B. A. Toseland

2006-01-01

17

Synthesis of dimethyl ether (DME) on modified HY zeolite and modified HY zeolite-supported Cu–Mn–Zn catalysts  

Microsoft Academic Search

Synthesis of dimethyl ether (DME) via methanol dehydration were investigated over HY zeolite and over Fe-, Co-, Ni-, Cr-, or Zr-modified HY zeolite, and via direct CO hydrogenation over modified HY zeolite-supported Cu–Mn–Zn catalysts. Zr- and Ni-modified HY zeolite exhibited higher activity and stability for methanol dehydration, while Fe-, Co-, and Cr-modified HY zeolite deactivated quickly due to carbon deposition.

Jinhua Fei; Zhaoyin Hou; Bing Zhu; Hui Lou; Xiaoming Zheng

2006-01-01

18

CO{sub 2}/dimethyl ether (DME) feed mixtures in the DME-to-hydrocarbon (DTH) process  

SciTech Connect

The DTH process represents the second stage in the conversion of syngas to hydrocarbons, where DME produced from the LPDME process is converted to C{sub 1}-C{sub 10} range hydrocarbons over a zeolite type catalyst in a fixed-bed tubular reactor. The reaction occurs in the vapor phase and typically operates at a temperature of 375 C. The product distribution can be can be controlled by varying the operating temperature, pressure and space velocity of DME. Previous investigations have examined the effects of T, P, WHSV, and catalyst type on olefin productivity as well as the processing advantages in starting with DME rather than MeOH. Unreacted CO{sub 2} from the DME synthesis reactor represents a potential problem in terms of further hydrocarbon processing from a DME feedstock; CO{sub 2}/DME mixtures are difficult to separate. A productivity comparison has been made with runs containing feed mixtures of CO{sub 2}/DME and N{sub 2}/DME mixtures. The role of CO{sub 2} on the final product distribution in the DTH process as well as the potential for recycle of unreacted CO{sub 2} back to the DME synthesis reactor has been examined. It has been found that CO{sub 2} is not actively involved in the reaction kinetics for the conversion of DME to hydrocarbons. Product distributions of the gaseous product are similar to those where N{sub 2} was used as the diluent.

Sardesai, A.; Tartamella, T.; Lee, S. [Univ. of Akron, OH (United States)

1995-12-31

19

Generating hydrogen-rich fuel-cell feeds from dimethyl ether (DME) using Cu\\/Zn supported on various solid-acid substrates  

Microsoft Academic Search

Several incipient wetness prepared catalysts containing copper and zinc were prepared in-house and reactor tested for the production of hydrogen from dimethyl ether steam reforming (DME-SR). The incorporation of copper and zinc onto a solid acid substrate (viz., zeolites ZSM-5 and Y with Si\\/Al=2.5–140, ?-Al2O3, and ZrO2) combined the catalytic components for DME hydrolysis to methanol (MeOH) and methanol steam

Troy A. Semelsberger; Kevin C. Ott; Rodney L. Borup; Howard L. Greene

2006-01-01

20

Auto-ignition during instationary jet evolution of dimethyl ether (DME) in a high-pressure atmosphere  

SciTech Connect

The auto-ignition process during transient injection of gaseous dimethyl ether (DME) in a constant high-pressure atmosphere is studied experimentally by laser-optical methods and compared with numerical calculations. With different non-intrusive measurement techniques jet properties and auto-ignition are investigated at high temporal and spatial resolution. The open jet penetrates a constant pressure oxidative atmosphere of up to 4 MPa. During the transient evolution, the fuel jet entrains air at up to 720 K. The subsequent auto-ignition of the ignitable part of the jet occurs simultaneously over a wide spatial extension. The ignition delay times are not affected by variation of the nozzle exit velocity. Thus, the low-temperature oxidation is slow compared with the shorter time scales of mixing, so that chemical kinetics is dominating the process. The typical two-stage ignition is resolved optically with high-speed shadowgraphy at a sampling rate of 10 kHz. The 2D fields of jet velocity and transient mixture fraction are measured phase-coupled with Particle Image Velocimetry (PIV) and Tracer Laser Induced Fluorescence (LIF) during the time-frame of ignition. The instationary Probability Density Functions (PDF) of mixture fraction are described very well by Beta functions within the complete area of the open jet. Additional 1D flamelet simulations of the auto-ignition process are computed with a detailed reaction mechanism for DME [S. Fischer, F. Dryer, H. Curran, Int. J. Chem. Kinet. 32 (12) (2000) 713-740; H. Curran, S. Fischer, F. Dryer, Int. J. Chem. Kinet. 32 (12) (2000) 741-759]. Calculated ignition delay times are in very good agreement with the measured mean ignition delay times of 3 ms. Supplemental flamelet simulations address the influence of DME and air temperature, pressure and strain. Underneath a critical strain rate the air temperature is identified to be the most sensitive factor on ignition delay time. (author)

Fast, G.; Kuhn, D.; Class, A.G. [Institut fuer Kern- und Energietechnik, Forschungszentrum Karlsruhe GmbH, Weberstrasse 5, D-76133 Karlsruhe (Germany); Maas, U. [Institut fuer Technische Thermodynamik, Universitat Karlsruhe (TH), Kaiserstrasse 12, D-76128 Karlsruhe (Germany)

2009-01-15

21

Direct Dimethyl Ether Polymer Electrolyte Fuel Cells for Portable Applications  

E-print Network

Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA Dimethyl ether DME delivery and methanol high energy density storage . DME also has low toxicity compared to methanol, making of the DME fuel cell. At the anode, there is a critical balance between water and DME availability

22

Generating hydrogen-rich fuel-cell feeds from dimethyl ether (DME) using physical mixtures of a commercial Cu\\/Zn\\/Al 2O 3 catalyst and several solid–acid catalysts  

Microsoft Academic Search

Homogeneous physical mixtures containing a commercial Cu\\/ZnO\\/Al2O3 catalyst and a solid–acid catalyst were used to examine the acidity effects on dimethyl ether hydrolysis and their subsequent effects on dimethyl ether steam reforming (DME-SR). The acid catalysts used were zeolites Y [Si\\/Al=2.5 and 15: denoted Y(Si\\/Al)], ZSM-5 [Si\\/Al=15, 25, 40, and 140: denoted Z(Si\\/Al)] and other conventional catalyst supports (ZrO2, and

Troy A. Semelsberger; Kevin C. Ott; Rodney L. Borup; Howard L. Greene

2006-01-01

23

Development of specialty chemicals from dimethyl ether  

SciTech Connect

Dimethyl ether (DME) may be efficiently produced from coal-bases syngas in a high pressure, mechanically agitated slurry reactor. DME synthesis occurs in the liquid phase using a dual catalyst. By operating in a dual catalyst mode, DME may be converted from in-situ produced methanol resulting in higher methyl productivities and syngas conversions over methanol conversion alone. The feasibility of utilizing DME as a building block for more valuable specialty chemicals has been examined. A wide variety of petrochemicals may be produced from DME including light olefins, gasoline range hydrocarbons, oxygenates, and glycol precursors. These chemicals represent an important part of petroleum industries inventory of fine chemicals. Carbonylation, hydrocarbonylation, and oxidative dimerization are but a few of the reactions in which DME may undergo conversion. DME provides an additional route for the production of industrially important petrochemicals.

Tartamella, T.L.; Lee, S. [Univ. of Akron, OH (United States). Dept. of Chemical Engineering

1996-12-31

24

Kinetics and Mechanism of Dimethyl Ether Oxidation to Formaldehyde on Supported Molybdenum Oxide Domains  

E-print Network

spectroscopy and kinetic data to determine the mechanism of dimethyl ether (DME, CH3OCH3) oxidation studies showed that rates of HCHO and CH3OH formation are first-order in DME and zero-order in O2 at low DME pressures. At high DME pressures, rates became independent of DME pressure and acquired positive

Iglesia, Enrique

25

Thrust measurement of dimethyl ether arcjet thruster  

NASA Astrophysics Data System (ADS)

The present paper describes thrust measurement results for an arcjet thruster using Dimethyl ether (DME) as the propellant. DME is an ether compound and can be stored as a liquid due to its relatively low freezing point and preferable vapor pressure. The thruster successfully produced high-voltage mode at DME mass flow rates above 30 mg/s, whereas it yielded low-voltage mode below 30 mg/s. Thrust measurements yielded a thrust of 0.15 N and a specific impulse of 270 s at a mass flow rate of 60 mg/s with a discharge power of 1300 W. The DME arcjet thruster was comparable to a conventional one for thrust and discharge power.

Kakami, Akira; Beppu, Shinji; Maiguma, Muneyuki; Tachibana, Takeshi

2011-04-01

26

Measurement of Vapor-Liquid Equilibrium for the DME + Diisopropyl Ether Binary System and Correlation for the DME + CO2 + Diisopropyl Ether Ternary System  

NASA Astrophysics Data System (ADS)

Vapor-liquid equilibrium (VLE) data have been measured with a static-type VLE apparatus for the dimethyl ether (DME)-diisopropyl ether (DIPE) binary system at five temperatures within the range from 293.04 K to 352.70 K. An isothermal correlation for the experimental data has been carried out based on the Peng-Robinson equation of state. The regressed binary interaction parameters were used to estimate VLE for the DME-CO2-DIPE ternary system at 298.15 K. From the study, it is demonstrated that DIPE is an excellent absorbent for separation in the DME synthesis process from syngas.

Wu, Xianghong; Du, Xiaojie; Zheng, Danxing

2010-02-01

27

Thermodynamic equilibrium calculations of dimethyl ether steam reforming and dimethyl ether hydrolysis  

NASA Astrophysics Data System (ADS)

The production of a hydrogen-rich fuel-cell feed by dimethyl ether (DME) steam reforming was investigated using calculations of thermodynamic equilibrium as a function of steam-to-carbon ratio (0.00-4.00), temperature (100-600 °C), pressure (1-5 atm), and product species. Species considered were acetone, acetylene, carbon dioxide, carbon monoxide, dimethyl ether, ethane, ethanol, ethylene, formaldehyde, formic acid, hydrogen, isopropanol, methane, methanol, methyl-ethyl ether, n-propanol and water. Thermodynamic equilibrium calculations of DME steam reforming indicate complete conversion of dimethyl ether to hydrogen, carbon monoxide and carbon dioxide at temperatures greater than 200 °C and steam-to-carbon ratios greater than 1.25 at atmospheric pressure ( P = 1 atm). Increasing the operating pressure shifts the equilibrium toward the reactants; increasing the pressure from 1 to 5 atm decreases the conversion of dimethyl ether from 99.5 to 76.2%. The trend of thermodynamically stable products in decreasing mole fraction is methane, ethane, isopropyl alcohol, acetone, n-propanol, ethylene, ethanol, methyl-ethyl ether and methanol-formaldehyde, formic acid, and acetylene were not observed. Based on the equilibrium calculations, the optimal processing conditions for dimethyl ether steam reforming occur at a steam-to-carbon ratio of 1.50, a pressure of 1 atm, and a temperature of 200 °C. These thermodynamic equilibrium calculations show dimethyl ether processed with steam will produce hydrogen-rich fuel-cell feeds—with hydrogen concentrations exceeding 70%. The conversion of dimethyl ether via hydrolysis (considering methanol as the only product) is limited by thermodynamic equilibrium. Equilibrium conversion increases with temperature and steam-to-carbon ratio. A maximum dimethyl ether conversion of 62% is achieved at a steam-to-carbon ratio of 5.00 and a processing temperature of 600 °C.

Semelsberger, Troy A.; Borup, Rodney L.

28

Fourier transform microwave spectrum of CO-dimethyl ether  

Microsoft Academic Search

Two sets of 32 rotational transitions were observed for the carbon monoxide-dimethyl ether (CO-DME) complex and two sets of 30 transitions for both 13CO-DME and C18O-DME, in the frequency region from 3.5 to 25.2 GHz, with J ranging from 1<--0 up to 7<--6, by using a Fourier transform microwave spectrometer. The splittings between the two sets of the same transition

Yoshiyuki Kawashima; Yasumasa Morita; Yoshio Tatamitani; Nobuyuki Ohashi; Eizi Hirota

2007-01-01

29

Atmospheric and combustion chemistry of dimethyl ether  

SciTech Connect

It has been demonstrated that dimethyl ether (DME) is an ideal diesel fuel alternative. DME, CH{sub 3}OCH{sub 3}, combines good fuel properties with low exhaust emissions and low combustion noise. Large scale production of this fuel can take place using a single step catalytic process converting CH{sub 4} to DME. The fate of DME in the atmosphere has previously been studied. The atmospheric degradation is initiated by the reaction with hydroxyl radicals, which is also a common feature of combustion processes. Spectrokinetic investigations and product analysis were used to demonstrate that the intermediate oxy radical, CH{sub 3}OCH{sub 2}O, exhibits a novel reaction pathway of hydrogen atom ejection. The application of tandem mass spectrometry to chemi-ions based on supersonic molecular beam sampling has recently been demonstrated. The highly reactive ionic intermediates are sampled directly from the flame and identified by collision activation mass spectrometry and ion-molecule reactions. The mass spectrum reflects the distribution of the intermediates in the flame. The atmospheric degradation of DME as well as the unique fuel properties of a oxygen containing compound will be discussed.

Nielsen, O.J.; Egsgaard, H.; Larsen, E.; Sehested, J. [Risoe National Lab., Roskilde (Denmark); Wallington, T.J. [Ford Motor Co., Dearborn, MI (United States)

1997-12-31

30

Synthesis of methyl acetate from syngas via dimethyl ether  

SciTech Connect

Dimethyl ether (DME) can be used as a building block for a variety of specialty chemicals in the petrochemical industry. Its utilization stems mainly from its efficient production from synthesis gas in a single stage. This Liquid Phase Dimethyl Ether (LP-DME) process, based on dual catalysts slurried in inert oil, can alleviate the chemical equilibrium limitation governing the methanol synthesis reaction and concurrently improve once-through syngas conversion and reactor productivity. Studies in the past have focused on using DME as a feedstock for gasoline range hydrocarbons as well as lower olefins. The focus of this investigation is to study the synthesis of methyl acetate, an important intermediate for acetic acid, from dimethyl ether. In particular, conversion of DME to methyl acetate is investigated over a variety of Group VIII metal substituted phosphotungstic acid salts. Key aspects of the process such as the effect of active metal, support types, multiple metal loading, and feed conditions are examined. Thus, this paper introduces a novel process route for synthesis of methyl acetate from natural gas-based syngas via dimethyl ether as an intermediate.

Tartamella, T.; Sardesai, A.; Lanterman, H.B.; Lee, S.

1999-07-01

31

High pressure injection of dimethyl ether  

SciTech Connect

Partially oxygenated hydrocarbons produced from natural gas have been shown to be viable alternate fuels for the diesel engine, showing favorable combustion characteristics similar to that of diesel fuel but without exhaust particulates and with significantly reduced NO{sub x} emissions and lower engine noise. Further, engine studies have demonstrated that such compounds, like dimethyl ether (DME), can be injected at much lower pressures than conventional diesel fuel with better overall performance. This experimental study compares the injection of DME to that of conventional diesel fuel. Both fuels were injected into a quiescent high pressure chamber containing Nitrogen at pressures up to 25 atmospheres at room temperature with a pintle nozzle and jerk pump. Comparisons were obtained with high speed photography using a Hycam camera. Results indicate that there are significant differences in spray geometry and penetration which are not predictable with analytical models currently used for diesel fuels.

Glensvig, M.; Sorenson, S.C. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Energy Engineering; Abata, D. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Mechanical Engineering and Engineering Mechanics

1996-12-31

32

Decomposition of Ethanol and Dimethyl Ether During Chemical Vapour deposition Synthesis  

E-print Network

1 Decomposition of Ethanol and Dimethyl Ether During Chemical Vapour deposition Synthesis of Single@photon.t.u-tokyo.ac.jp #12;2 Abstract In this study, we investigated carbon feedstock decomposition conditions-phase thermal decomposition of ethanol and dimethyl ether (DME) at typical SWNT growth conditions using

Maruyama, Shigeo

33

Syngas to olefins via dimethyl ether over zeolite catalysts  

SciTech Connect

Coal or natural gas-based syngas can be converted to dimethyl ether (DME) in a dual catalytic, single-stage liquid phase process. The process described here converts dimethyl ether to lower olefins, such as ethylene, propylene, and butenes. Thus, a novel process of producing olefins from syngas via dimethyl ether has been introduced. The process feasibility of dimethyl ether conversion has been evaluated and the range of products of this process has also been identified. The effect of operating parameters and catalyst characteristics on product selectivity has been studied. The superior process advantages as well as its competitive economics quite clearly identify this process to be quite promising when conducted on an industrial scale.

Lee, B.G. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of); Sardesai, A.; Lee, S. [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering

1998-12-31

34

Experimental Study on Homogeneous Charge Compression Ignition Operation by Burning Dimethyl Ether and Methanol  

Microsoft Academic Search

In this paper, a new approach to burning methanol in engine is proposed, in which the engine burns dimethyl ether (DME) and methanol dual fuel in homogeneous charge compression ignition (HCCI) mode, and DME is converted from methanol. Combustion, engine performance, and pollutant emissions of the new HCCI combustion system were investigated. The results show that the stable HCCI operation

Mingfa Yao; Zunqing Zheng; Zheng Chen; Bo Zhang

2007-01-01

35

A study of low-comression-ratio dimethyl ether diesel engines  

Microsoft Academic Search

A new concept of using dimethyl ether (DME) as an alternative fuel in direct injection compression ignition engines with low compression ratios was presented to seek a combustion regime with the highest thermal efficiency. The concept was experimentally evaluated by a comparison of performance and emissions between a DME-fuelled engine and the corresponding conventional diesel engine. The result demonstrated that

S Kajitani; Z Chen; M Oguma; M Konno

2002-01-01

36

Improvement of performance and emissions of a compression ignition methanol engine with dimethyl ether  

SciTech Connect

Dimethyl ether (DME) has very good compression ignition characteristics and can be converted from methanol using a {gamma}-alumina catalyst. In this study a torch ignition chamber (TIC) head with TIC close to the center of the main combustion chamber was designed for the TIC method. The possibility of improvements in reducing the quantities of DME and emission were investigated by optimizing the TIC position, methanol injection timing, DME injection timing, and intake and exhaust throttling. It was found that the necessary amount of DME was greatly reduced when optimizing methanol and DME injection timings. 2 refs., 16 figs., 1 tab.

Guo, J.; Chikahisa, Takemi; Murayama, Tadashi; Miyano, Masaharu

1994-10-01

37

Role of acid catalysis in dimethyl ether conversion processes  

SciTech Connect

Acidity plays an important role in the conversion of methanol and dimethyl ether (DME) to hydrocarbons and oxygenates. In the conversion to hydrocarbons over zeolite catalyst, Broensted acidity is the main contributor to the first hydrocarbon formed. Here, acidity is also an important factor in determining olefin, paraffin, and aromatic content in the final product distribution. Catalyst life has also been found to be related to acidity content in zeolites. DME conversion to oxygenates is especially dependent on high acidity catalysts. Superacids like BF{sub 3}, HF-BF{sub 3}, and CF{sub 3}COOH have been used in the past for conversion of DME in carbonylation reactions to form methyl acetate and acetic acid at high pressures. Recently, heteropoly acids and their corresponding metal substituted salts have been used to convert DME to industrially important petrochemicals resulting in shorter reaction times and without the use of harsh operating conditions.

Tartamella, T.L.; Lee, S. [Univ. of Akron, OH (United States). Dept. of Chemical Engineering

1996-12-31

38

Dimethyl ether fuel proposed as an alternative to LNG  

SciTech Connect

To cope with the emerging energy demand in Asia, alternative fuels to LNG must be considered. Alternative measures, which convert the natural gas to liquid fuel, include the Fischer-Tropsch conversion, methanol synthesis, and dimethyl ether (DME) synthesis. Comparisons are evaluated based on both transportation cost and feed-gas cost. The analysis will show that DME, one alternative to LNG as transportation fuel, will be more economical for longer distances between the natural-gas source and the consumer. LNG requires a costly tanker and receiving terminal. The break-even distance will be around 5,000--7,000 km and vary depending on the transported volume. There will be risk, however, since there has never been a DME plant the size of an LNG-equivalent plant [6 million metric tons/year (mty)].

Kikkawa, Yoshitsugi; Aoki, Ichizo [Chiyoda Corp., Yokohama (Japan)

1998-04-06

39

Dimethyl ether (DME) as an alternative fuel  

Microsoft Academic Search

With ever growing concerns on environmental pollution, energy security, and future oil supplies, the global community is seeking non-petroleum based alternative fuels, along with more advanced energy technologies (e.g., fuel cells) to increase the efficiency of energy use. The most promising alternative fuel will be the fuel that has the greatest impact on society. The major impact areas include well-to-wheel

Troy A. Semelsberger; Rodney L. Borup; Howard L. Greene

2006-01-01

40

Stratified liquefied petroleum gas—dimethyl ether compression ignition engine combustion at various intake valve open timings  

Microsoft Academic Search

The combustion and exhaust emissions characteristics of compression ignition engine with a variable valve timing device were investigated for liquefied petroleum gas (LPG) and dimethyl ether (DME) under various LPG injection timing conditions. LPG was used as the main fuel injected directly into the combustion chamber. DME was used as an ignition promoter injected into the intake port. Different LPG

K Yeom; C Bae

2010-01-01

41

Title: Decomposition of ethanol and dimethyl-ether during CVD synthesis of single-walled carbon nanotubes  

E-print Network

of ethanol and dimethyl-ether during CVD synthesis of single-walled carbon nanotubes Author list: Bo Hou (single-walled carbon nanotubes) was investigated. Gas-phase thermal decomposition of ethanol and DME ethanol and DME decomposition, confirming expected reaction trends and primary byproducts. Peak

Maruyama, Shigeo

42

Evaluation of methyl fluoride and dimethyl ether as inhibitors of aerobic methane oxidation  

USGS Publications Warehouse

Methyl fluoride (MF) and dimethyl ether (DME) were effective inhibitors of aerobic methanotrophy in a variety of soils. MF and DME blocked consumption of CH4 as well as the oxidation of 14CH4 to 14CO2, but neither MF nor DME affected the oxidation of [14C]methanol or [14C]formate to 14CO2. Cooxidation of ethane and propane by methane-oxidizing soils was also inhibited by MF. Nitrification (ammonia oxidation) in soils was inhibited by both MF and DME. Production of N2O via nitrification was inhibited by MF; however, MF did not affect N2O production associated with denitrification. Methanogenesis was partially inhibited by MF but not by DME. Methane oxidation was ~100-fold more sensitive to MF than was methanogenesis, indicating that an optimum concentration could be employed to selectively block methanotrophy. MF inhibited methane oxidation by cell suspensions of Methylococcus capsulatus; however, DME was a much less effective inhibitor.

Oremland, R.S.; Culbertson, C.W.

1992-01-01

43

New clean fuel from coal -- Direct dimethyl ether synthesis from hydrogen and carbon monoxide  

SciTech Connect

Dimethyl ether (DME), which has similar physical properties to propane and is easily liquefied at low pressure, has a significant possibility as a clean and non-toxic fuel from coal or coal bed methane. Equilibrium calculation also shows a big advantage of high carbon monoxide conversion of DME synthesis compared to methanol synthesis. By using a 50 kg/day DME bench scale test plant, direct synthesis of DME from hydrogen and carbon monoxide has been studied with newly developed catalysts which are very fine particles. This test plant features a high pressure three-phase slurry reactor and low temperature DME separator. DME is synthesized at temperatures around 533--553 K and at pressures around 3--5 MPa. According to the reaction stoichiometry, the same amount of hydrogen and carbon monoxide react to DME and carbon dioxide. Carbon conversion to DME is one third and the rest of carbon is converted to carbon dioxide. As a result of the experiments, make-up CO conversion is 35--50% on an once-through basis, which is extremely high compared to that of methanol synthesis from hydrogen and carbon monoxide. DME selectivity is around 60 c-mol %. Most of the by-product is CO{sub 2} with a small amount of methanol and water. No heavy by-products have been recognized. Effluent from the reactor is finally cooled to 233--253 K in a DME separator and liquid DME is recovered as a product.

Ogawa, T.; Ono, M.; Mizuguchi, M.; Tomura, K.; Shikada, T.; Ohono, Y. [NKK Corp., Tokyo (Japan); Fujimoto, K. [Univ. of Tokyo (Japan)

1997-12-31

44

Thermodynamics of Hydrogen Production from Dimethyl Ether Steam Reforming and Hydrolysis  

SciTech Connect

The thermodynamic analyses of producing a hydrogen-rich fuel-cell feed from the process of dimethyl ether (DME) steam reforming were investigated as a function of steam-to-carbon ratio (0-4), temperature (100 C-600 C), pressure (1-5 atm), and product species: acetylene, ethanol, methanol, ethylene, methyl-ethyl ether, formaldehyde, formic acid, acetone, n-propanol, ethane and isopropyl alcohol. Results of the thermodynamic processing of dimethyl ether with steam indicate the complete conversion of dimethyl ether to hydrogen, carbon monoxide and carbon dioxide for temperatures greater than 200 C and steam-to-carbon ratios greater than 1.25 at atmospheric pressure (P = 1 atm). Increasing the operating pressure was observed to shift the equilibrium toward the reactants; increasing the pressure from 1 atm to 5 atm decreased the conversion of dimethyl ether from 99.5% to 76.2%. The order of thermodynamically stable products in decreasing mole fraction was methane, ethane, isopropyl alcohol, acetone, n-propanol, ethylene, ethanol, methyl-ethyl ether and methanol--formaldehyde, formic acid, and acetylene were not observed. The optimal processing conditions for dimethyl ether steam reforming occurred at a steam-to-carbon ratio of 1.5, a pressure of 1 atm, and a temperature of 200 C. Modeling the thermodynamics of dimethyl ether hydrolysis (with methanol as the only product considered), the equilibrium conversion of dimethyl ether is limited. The equilibrium conversion was observed to increase with temperature and steam-to-carbon ratio, resulting in a maximum dimethyl ether conversion of approximately 68% at a steam-to-carbon ratio of 4.5 and a processing temperature of 600 C. Thermodynamically, dimethyl ether processed with steam can produce hydrogen-rich fuel-cell feeds--with hydrogen concentrations exceeding 70%. This substantiates dimethyl ether as a viable source of hydrogen for PEM fuel cells.

T.A. Semelsberger

2004-10-01

45

Barrierless proton transfer across weak CH?O hydrogen bonds in dimethyl ether dimer.  

PubMed

We present a combined computational and threshold photoelectron photoion coincidence study of two isotopologues of dimethyl ether, (DME - h6)n and (DME - d6)n n = 1 and 2, in the 9-14 eV photon energy range. Multiple isomers of neutral dimethyl ether dimer were considered, all of which may be present, and exhibited varying C-H?O interactions. Results from electronic structure calculations predict that all of them undergo barrierless proton transfer upon photoionization to the ground electronic state of the cation. In fact, all neutral isomers were found to relax to the same radical cation structure. The lowest energy dissociative photoionization channel of the dimer leads to CH3OHCH3 (+) by the loss of CH2OCH3 with a 0 K appearance energy of 9.71 ± 0.03 eV and 9.73 ± 0.03 eV for (DME - h6)2 and deuterated (DME - d6)2, respectively. The ground state threshold photoelectron spectrum band of the dimethyl ether dimer is broad and exhibits no vibrational structure. Dimerization results in a 350 meV decrease of the valence band appearance energy, a 140 meV decrease of the band maximum, thus an almost twofold increase in the ground state band width, compared with DME - d6 monomer. PMID:25796245

Yoder, Bruce L; Bravaya, Ksenia B; Bodi, Andras; West, Adam H C; Sztáray, Bálint; Signorell, Ruth

2015-03-21

46

Barrierless proton transfer across weak CH⋯O hydrogen bonds in dimethyl ether dimer  

NASA Astrophysics Data System (ADS)

We present a combined computational and threshold photoelectron photoion coincidence study of two isotopologues of dimethyl ether, (DME - h6)n and (DME - d6)n n = 1 and 2, in the 9-14 eV photon energy range. Multiple isomers of neutral dimethyl ether dimer were considered, all of which may be present, and exhibited varying C-H⋯O interactions. Results from electronic structure calculations predict that all of them undergo barrierless proton transfer upon photoionization to the ground electronic state of the cation. In fact, all neutral isomers were found to relax to the same radical cation structure. The lowest energy dissociative photoionization channel of the dimer leads to CH3OHCH3+ by the loss of CH2OCH3 with a 0 K appearance energy of 9.71 ± 0.03 eV and 9.73 ± 0.03 eV for (DME - h6)2 and deuterated (DME - d6)2, respectively. The ground state threshold photoelectron spectrum band of the dimethyl ether dimer is broad and exhibits no vibrational structure. Dimerization results in a 350 meV decrease of the valence band appearance energy, a 140 meV decrease of the band maximum, thus an almost twofold increase in the ground state band width, compared with DME - d6 monomer.

Yoder, Bruce L.; Bravaya, Ksenia B.; Bodi, Andras; West, Adam H. C.; Sztáray, Bálint; Signorell, Ruth

2015-03-01

47

The effect of catalyst ratio on catalytic performance in liquid phase dimethyl ether process  

SciTech Connect

In the liquid phase dimethyl ether (LPDME) process, two functionally different catalysts are slurried together in an inert liquid medium. Syngas reacts on the surface of the methanol catalyst and methanol is dehydrated on the surface of the dehydration catalyst dispersed in the liquid. The process is adaptable to carbon monoxide-rich syngas derived from second generation coal gasifiers. The effect of catalyst ratio on catalytic performances of the dual catalyst was studied in liquid phase dimethyl ether synthesis from syngas at 280 C, 4.0 MPa. CO conversion, H{sub 2} conversion and DME productivity increased with an increase of catalyst ratio initially, reached their maximum at a catalyst ratio of 4.0--5.0, and then decreased. Methanol productivity and methanol equivalent productivity had a similar trend to that of DME productivity. DME selectivity and hydrocarbon selectivity increased with an increase in catalyst ratio whereas methanol selectivity decreased with catalyst ratio.

Guo Junwang; Niu Yuqin; Zhang Bijiang [Chinese Academy of Sciences, Taiyuan, Shanxi (China). Inst. of Coal Chemistry

1997-12-31

48

Adsorption structure of dimethyl ether on silicalite-1 zeolite determined using single-crystal X-ray diffraction  

PubMed Central

The adsorption structures of dimethyl ether (DME) on silicalite-1 zeolite (MFI-type) are determined using single-crystal X-ray diffraction. The structure of low-loaded DME-silicalite-1 indicates that all DME molecules are located in the sinusoidal channel, which is the most stable sorption site based on the van der Waals interaction between DME and the framework. The configuration of guest molecules (linear or bent) plays an important role in determining where the stable sorption site is in the pore system of MFI-type zeolites. Bent molecules favor the sinusoidal channel, while linear molecules favor the straight channel. The contribution of DME–DME interactions is considerable in the high-loaded DME-silicalite-1 structure. PMID:25274519

Fujiyama, Shinjiro; Seino, Shintaro; Kamiya, Natsumi; Nishi, Koji; Yokomori, Yoshinobu

2014-01-01

49

Intermolecular Interaction in the Formaldehyde-Dimethyl Ether and Formaldehyde-Dimethyl Sulfide Complexes Investigated by Fourier Transform Microwave Spectroscopy and ab Initio Calculations.  

PubMed

The ground-state rotational spectra of the formaldehyde-dimethyl ether (H2CO-DME) and formaldehyde-dimethyl sulfide (H2CO-DMS) complexes have been studied by Fourier transform microwave spectroscopy. The a-type and c-type rotational transitions have been assigned for the normal and deutrated formaldehyde-containing species of both complexes. In the case of H2CO-DME, doublets were observed with the splitting 10-300 kHz, whereas no such splittings were observed for H2CO-DMS, D2CO-DME, and D2CO-DMS. The observed rotational spectra were found consistent with a structure of Cs symmetry with DME or DMS bound to H2CO by two types of hydrogen bonds: C-H(DME/DMS)---O(H2CO) and O(DME)/S(DMS)---H-C(H2CO). The Rcm distances between the centers of mass of the component molecules in the H2CO-DME and H2CO-DMS complexes were determined to be 3.102 and 3.200 Å, respectively, which are shorter than those in most related complexes. The spectral and NBO analyses showed that H2CO-DMS has a stronger charge transfer interaction than H2CO-DME does and that the binding energy of H2CO-DMS is larger than that of H2CO-DME. PMID:25679958

Tatamitani, Yoshio; Kawashima, Yoshiyuki; Osamura, Yoshihiro; Hirota, Eizi

2015-03-12

50

Wide range modeling study of dimethyl ether oxidation  

SciTech Connect

A detailed chemical kinetic model has been used to study dimethyl ether (DME) oxidation over a wide range of conditions. Experimental results obtained in a jet-stirred reactor (JSR) at I and 10 atm, 0.2 < 0 < 2.5, and 800 < T < 1300 K were modeled, in addition to those generated in a shock tube at 13 and 40 bar, 0 = 1.0 and 650 :5 T :5 1300 K. The JSR results are particularly valuable as they include concentration profiles of reactants, intermediates and products pertinent to the oxidation of DME. These data test the Idnetic model severely, as it must be able to predict the correct distribution and concentrations of intermediate and final products formed in the oxidation process. Additionally, the shock tube results are very useful, as they were taken at low temperatures and at high pressures, and thus undergo negative temperature dependence (NTC) behavior. This behavior is characteristic of the oxidation of saturated hydrocarbon fuels, (e.g. the primary reference fuels, n-heptane and iso- octane) under similar conditions. The numerical model consists of 78 chemical species and 336 chemical reactions. The thermodynamic properties of unknown species pertaining to DME oxidation were calculated using THERM.

Pitz, W.J.; Marinov, N.M.; Westbrook, C.K.; Dagaut, P.; Boettner, J-C; Cathonnet, M.

1997-04-01

51

Single-step syngas-to-dimethyl ether processes for optimal productivity, minimal emissions, and natural gas-derived syngas  

Microsoft Academic Search

Process schemes for single-step syngas-to-dimethyl ether (DME) were developed in two stages: (1) the performance of the syngas-to-DME reactor was optimized with respect to the feed gas composition and (2) the optimal reactor feed gas system was integrated with synthesis gas generators. It was shown that the reactor performance is very sensitive to the Hâ:CO ratio in the feed gas.

X. D. Peng; A. W. Wang; B. A. Toseland; P. J. A. Tijm

1999-01-01

52

Catalyst activity maintenance study for the liquid phase dimethyl ether process  

SciTech Connect

The co-production of dimethyl ether (DME) and methanol from syngas is a process of considerable commercial attractiveness. DME coproduction can double the productivity of a LPMEOH process when using coal-derived syngas. This in itself may offer chemical producers and power companies increased flexibility and more profitable operation. DME is also known as a clean burning liquid fuel; Amoco and Haldor-Topsoe have recently announced the use of DME as an alternative diesel fuel. Moreover, DME can be an interesting intermediate in the production of chemicals such as olefins and vinyl acetate. The current APCl liquid phase dimethyl ether (LPDME) process utilizes a physical mixture of a commercial methanol synthesis catalyst and a dehydration catalyst (e.g., {gamma}-alumina). While this arrangement provides a synergy that results in much higher syngas conversion per pass compared to the methanol-only process, the stability of the catalyst system suffers. The present project is aimed at reducing catalyst deactivation both by understanding the cause(s) of catalyst deactivation and by developing modified catalyst systems. This paper describes the current understanding of the deactivation mechanism.

Peng, X.D.; Toseland, B.A.; Underwood, R.P. [Air Products and Chemicals, Inc., Allentown, PA (United States)

1995-12-31

53

Experimental and Modeling Study of Premixed Atmospheric-Pressure Dimethyl Ether?Air Flames  

Microsoft Academic Search

Chemical species profiles have been measured at atmospheric pressure for two dimethyl ether (DME)-air flat flames having fuel-air equivalence ratios of 0.67 and 1.49. The samples, obtained with an uncooled quartz probe, were analyzed by either gas chromatography or Fourier transform infrared (FTIR) spectroscopy for CH4, C2H2, C2H4, C2H6, C3H8, DME, CO, CO2, O2, CH2O, and formic acid. A pneumatic

E. W. Kaiser; T. J. Wallington; M. D. Hurley; J. Platz; H. J. Curran; W. J. Pitz; C. K. Westbrook

2000-01-01

54

A laser and molecular beam mass spectrometer study of low-pressure dimethyl ether flames  

SciTech Connect

The oxidation of dimethyl ether (DME) is studied in low-pressure flames using new molecular beam mass spectrometer and laser diagnostics. Two 30.0-Torr, premixed DME/oxygen/argon flames are investigated with stoichiometries of 0.98 and 1.20. The height above burner profiles of nine stable species and two radicals are measured. These results are compared to the detailed chemical reaction mechanism of Curran and coworkers. Generally good agreement is found between the model and data. The largest discrepancies are found for the methyl radical profiles where the model predicts qualitatively different trends in the methyl concentration with stoichiometry than observed in the experiment.

Andrew McIlroy; Toby D. Hain; Hope A. Michelsen; Terrill A. Cool

2000-12-15

55

Shape-selective catalysis in dimethyl ether conversion  

SciTech Connect

Coal-derived syngas can be effectively converted to dimethyl ether (DME) in a single-stage, liquid-phase process. This Liquid Phase Dimethyl Ether (LPDME) process utilizes a dual catalytic system, which comprises of a physical blend between the methanol synthesis and the methanol dehydration catalyst slurried in an inert mineral oil. Such produced DME has vast potential as a building block chemical in the petrochemical industry to produce value-added specialty chemicals. The current research efforts are made to exploit the utilization of shape-selective catalysis using zeolites to produce targeted petrochemicals, including lower olefinic hydrocarbons. The catalysts probed in this investigation include zeolites of different physical, morphological, and chemical configurations. The effect of acidity of ZSM-5 type zeolites as well as the effect of the different channel size and orientation of the zeolites on product selectivity and catalyst deactivation are examined. Results obtained from experimentation of this study show that ZSM-5 type zeolite with low acidity (high SiO{sub 2}/Al{sub 2}O{sub 3} ratio, in this case 150) exhibits the highest selectivity towards lower (C{sub 2}-C{sub 4}) olefins in general. Controlled selectivity toward targeted olefinic species can be accomplished via devising catalytic reaction systems in such a way that the structural property of the catalyst and reactive interaction between molecules in the pores are geared toward formation of targeted molecular species which also at the same time prevent the formation of less desirable products. The internal morphology of the catalyst also has a pronounced effect on the deactivation phenomenon, where it is observed that zeolites possessing high acidity and a unidimensional channel structure are prone towards catalyst deactivation by coking and pore blockage.

Sardesai, A.; Lee, S.

1999-07-01

56

Slurry phase synthesis of dimethyl ether from syngas -- A reactor model simulation  

SciTech Connect

Dimethyl ether (DME) would be an attractive alternative fuel for diesel, domestic use, and power generation, if it is economically synthesized directly from syngas (derived from coal gasification or natural gas reforming). DME, which is a colorless gas with a boiling point of {minus}25 C, is chemically stable and easily liquefied under pressure. Since the properties of DME are similar to LPG, it can be handled and stored with the same manner as LPG. The authors have performed the slurry phase DME synthesis by using the 50 kg/day bench-scale unit. DME was synthesized at high yield from syngas (H{sub 2}+CO) with the newly developed catalyst system. To establish the scale-up methodology, the reactor simulation technique is essential. The authors developed a mathematical model of the slurry phase bubble column reactor for DME synthesis, which is based on their experimental results. The performance of a commercial-scale DME reactor was simulated by this model, and the results were discussed.

Mizuguchi, Masatsugu; Ogawa, Takashi; Ono, Masami,; Tomura, Keiji; Shikada, Tsutomu; Ohno, Yotaro [NKK Corp., Kawasaki (Japan); Fujimoto, Kaoru [Univ. of Tokyo (Japan)

1998-12-31

57

Influence of solid–acid catalysts on steam reforming and hydrolysis of dimethyl ether for hydrogen production  

Microsoft Academic Search

Influences of solid–acid catalyst on dimethyl ether steam reforming (DME SR) and DME hydrolysis for hydrogen production were investigated. Series of zeolite (JRC-ZHM20(5), JRC-ZHM90(1) as H-mordenite type and JRC-Z5-90H(1) as ZSM-5 type) and of alumina (ALO8, TA1301, TA3301, DK503, NKHD24, NKHO24 and NK324) were used as acidic catalysts for DME hydrolysis. The composite catalysts of the acidic catalyst and CuFe2O4

Kajornsak Faungnawakij; Yohei Tanaka; Naohiro Shimoda; Tetsuya Fukunaga; Shunichiro Kawashima; Ryuji Kikuchi; Koichi Eguchi

2006-01-01

58

Direct synthesis of ethanol from dimethyl ether and syngas over combined H-Mordenite and Cu/ZnO catalysts.  

PubMed

Ethanol was directly synthesized from dimethyl ether (DME) and syngas with the combined H-Mordenite and Cu/ZnO catalysts that were separately loaded in a dual-catalyst bed reactor. Methyl acetate (MA) was formed by DME carbonylation over the H-Mordenite catalyst. Thereafter, ethanol and methanol were produced by MA hydrogenation over the Cu/ZnO catalyst. With the reactant gas containing 1.0% DME, the optimized temperature for the reaction was at 493 K to reach 100% conversion. In the products, the yield of methanol and ethanol could reach 46.3% and 42.2%, respectively, with a small amount of MA, ethyl acetate, and CO(2). This process is environmentally friendly as the main byproduct methanol can be recycled to DME by a dehydration reaction. In contrast, for the physically mixed catalysts, the low conversion of DME and high selectivity of methanol were observed. PMID:20715046

Li, Xingang; San, Xiaoguang; Zhang, Yi; Ichii, Takashi; Meng, Ming; Tan, Yisheng; Tsubaki, Noritatsu

2010-10-25

59

Dimethyl ether synthesis from CO{sub 2}-rich syngas in the LPDME process  

SciTech Connect

The liquid phase dimethyl ether, LPDME, synthesis process was developed by the University of Akron and EPRI team as a means to overcome the chemical equilibrium involved in the synthesis of methanol from a syngas feed. This process alleviates the methanol synthesis equilibrium limitation by converting the product into dimethyl ether. The conversion is performed in a slurry reactor and involves the use of a dual catalyst mixture for the single-stage conversion of syngas to DME. As with the LPMeOH{trademark}, the LPDME process utilizes an inert mineral oil to facilitate heat transfer as well as provide a medium for catalyst mixing. The reaction typically takes place at 250 C and 7.0 MPa and makes use of Cu/ZnO/Al{sub 2}O{sub 3} and {gamma}-Alumina as the methanol synthesis and DME synthesis catalysts respectively. As with LPMeOH{trademark}, the water gas shift reaction plays an important role on final DME productivity, reaction rate and selectivity. The emphasis in this paper is to examine the effect of varying CO{sub 2} concentrations on the reaction kinetics. DME productivity, reaction rate, and selectivity as a function of CO{sub 2} concentration in syngas was examined. Concentrations of CO{sub 2} in syngas ranging from 4% to 13% were used.

Gunda, A.; Tartamella, T.; Gogate, M.; Lee, S. [Univ. of Akron, OH (United States)

1995-12-31

60

A single-stage synthesis of dimethyl ether in liquid phase  

SciTech Connect

A novel, single-stage process for the synthesis of dimethyl ether (DME) has been developed using CO rich syngas in the liquid phase (LPDME). This process utilizes a three-phase, mechanically agitated slurry reactor and makes use of a dual catalyst system consisting of Cu/ZnO/Al{sub 2}O{sub 3} as the methanol synthesis catalyst and {gamma}-Al{sub 2}O{sub 3} for the subsequent conversion to DME. The catalyst is slurried in an inert mineral oil which facilitates effective heat removal. The process involves the synthesis of methanol as an inter-mediate in the production of DME. In doing so, there is a reduction of the chemical equilibrium limitations previously encountered in methanol synthesis alone. As a result, enhanced catalyst activity, per-pass conversion and reactor productivity over methanol synthesis is observed. The process excels over its liquid phase methanol counterpart (LPMeOH{trademark}) in many areas. Specifically, a increase in reactor productivity as high as 95% is attained in the production of DME over LPMeOH{trademark}. Also, a 60% increase in syngas conversion is attained over the production of methanol alone. Experimental studies compare reactor productivities for methanol vs. DME synthesis for several slurry ratios. Also, the effect of temperature and pressure on synthesis rates for methanol and DME are also examined.

Tartamella, T.L.; Lee, S. [Univ. of Akron, OH (United States); Kulik, C.J. [Electric Power Research Inst., Palo Alto, CA (United States)

1994-12-31

61

CATALYST ACTIVITY MAINTENANCE FOR THE LIQUID PHASE SYNTHESIS GAS-TO-DIMETHYL ETHER PROCESS PART II: DEVELOPMENT OF ALUMINUM PHOSPHATE AS THE DEHYDRATION CATALYST FOR THE SINGLE-STEP LIQUID PHASE SYNGAS-TO-DME PROCESS  

SciTech Connect

At the heart of the single-step liquid phase syngas-to-DME process (LPDME{trademark}) is a catalyst system that can be active as well as stable. In the Alternative Fuels I program, a dual-catalyst system containing a Cu-based commercial methanol synthesis catalyst (BASF S3-86) and a commercial dehydration material ({gamma}-alumina) was demonstrated. It provided the productivity and selectivity expected from the LPDME process. However, the catalyst system deactivated too rapidly to warrant a viable commercial process [1]. The mechanistic investigation in the early part of the DOE's Alternative Fuels II program revealed that the accelerated catalyst deactivation under LPDME conditions is due to detrimental interaction between the methanol synthesis catalyst and methanol dehydration catalyst [2,3]. The interaction was attributed to migration of Cu- and/or Zn-containing species from the synthesis catalyst to the dehydration catalyst. Identification of a dehydration catalyst that did not lead to this detrimental interaction while retaining adequate dehydration activity was elusive. Twenty-nine different dehydration materials were tested, but none showed the desired performance [2]. The search came to a turning point when aluminum phosphate was tested. This amorphous material is prepared by precipitating a solution containing Al(NO{sub 3}){sub 3} and H{sub 3}PO{sub 4} with NH{sub 4}OH, followed by washing, drying and calcination. The aluminum phosphate catalyst has adequate dehydration activity and good stability. It can co-exist with the Cu-based methanol synthesis catalyst without negatively affecting the latter catalyst's stability. This report documents the details of the development of this catalyst. These include initial leads, efforts in improving activity and stability, investigation and development of the best preparation parameters and procedures, mechanistic understanding and resulting preparation guidelines, and the accomplishments of this work.

Xiang-Dong Peng

2002-05-01

62

A SINGLE-STAGE, LIQUID-PHASE DIMETHYL ETHER SYNTHESIS PROCESS FROM SYNGAS II. COMPARISON OF PER-PASS SYNGAS CONVERSION, REACTOR PRODUCTIVITY AND HYDROGENATION EXTENT  

Microsoft Academic Search

In part I of this series on the development of a single-stage, liquid-phase dimethyl ether (DME) synthesis process from syngas, the process feasibility and the process variable effects on the dual catalyst activity were discussed. This part focuses on the comparison of the single-stage reactor productivity of liquid phase methanol synthesis to that of the co-production of methanol and DME.

Sunggyu Lee; Makarand R. Gogate; Conrad J. Kulik

1991-01-01

63

Synergistic effect of mixing dimethyl ether with methane, ethane, propane, and ethylene fuels on polycyclic aromatic hydrocarbon and soot formation  

SciTech Connect

Characteristics of polycyclic aromatic hydrocarbon (PAH) and soot formation in counterflow diffusion flames of methane, ethane, propane, and ethylene fuels mixed with dimethyl ether (DME) have been investigated. Planar laser-induced incandescence and fluorescence techniques were employed to measure relative soot volume fractions and PAH concentrations, respectively. Results showed that even though DME is known to be a clean fuel in terms of soot formation, DME mixture with ethylene fuel increases PAH and soot formation significantly as compared to the pure ethylene case, while the mixture of DME with methane, ethane, and propane decreases PAH and soot formation. Numerical calculations adopting a detailed kinetics showed that DME can be decomposed to produce a relatively large number of methyl radicals in the low-temperature region where PAH forms and grows; thus the mixture of DME with ethylene increases CH{sub 3} radicals significantly in the PAH formation region. Considering that the increase in the concentration of O radicals is minimal in the PAH formation region with DME mixture, the enhancement of PAH and soot formation in the mixture flames of DME and ethylene can be explained based on the role of methyl radicals in PAH and soot formation. Methyl radicals can increase the concentration of propargyls, which could enhance incipient benzene ring formation through the propargyl recombination reaction and subsequent PAH growth. Thus, the result substantiates the importance of methyl radicals in PAH and soot formation, especially in the PAH formation region of diffusion flames. (author)

Yoon, S.S. [Corporate Research and Development Division, Hyundai-Kia Motors, Gyeonggi-do 445-706 (Korea); Anh, D.H. [Korea Electric Power Research Institute, Daejeon 305-380 (Korea); Chung, S.H. [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea)

2008-08-15

64

Process for producing dimethyl ether form synthesis gas  

DOEpatents

This invention pertains to a Fischer Tropsch process for converting synthesis gas to an oxygenated hydrocarbon with particular emphasis on dimethyl ether. Synthesis gas comprising carbon monoxide and hydrogen are converted to dimethyl ether by carrying out the reaction in the presence of an alkali metal-manganese-iron carbonyl cluster incorporated onto a zirconia-alumina support.

Pierantozzi, Ronald (Macungie, PA)

1985-01-01

65

Process for producing dimethyl ether from synthesis gas  

DOEpatents

This invention pertains to a Fischer Tropsch process for converting synthesis gas to an oxygenated hydrocarbon with particular emphasis on dimethyl ether. Synthesis gas comprising carbon monoxide and hydrogen are converted to dimethyl ether by carrying out the reaction in the presence of an alkali metal-manganese-iron carbonyl cluster incorporated onto a zirconia-alumina support.

Pierantozzi, R.

1985-06-04

66

Separation of Dimethyl Ether from Syn-Gas Components by Poly(dimethylsiloxane) and Poly(4-methyl-1-pentene) Membranes  

SciTech Connect

Permeability and selectivity in gas transport through poly(4-methyl-1-pentene) (TPX) and poly(dimethylsiloxane) (PDMS) using variable temperature mixed gas experiments is reported. Selected gases include H2, CO, CH4, CO2, and dimethyl ether (DME). The DME data is the first to be reported through these membranes. In this paper, the chosen polymers reflect both rubbery and crystalline materials. Rubbery polymers tend to be weakly size sieving, which, in this work, has resulted in larger permeabilities, lower separation factors, and lower activation energies of permeation (Ep). Conversely, the crystalline TPX membranes showed much greater sensitivity to penetrant size; although the gas condensability also played a role in transport.

Christopher J. Orme; Frederick F. Stewart

2011-05-01

67

Using Heteropolyacids in the Anode Catalyst Layer of Dimethyl Ether PEM Fuel Cells  

SciTech Connect

In this study, polarization experiments were performed on a direct dimethyl ether fuel cell (DMEFC). The experimental setup allowed for independent control of water and DME flow rates. Thus the DME flow rate, backpressure, and water flow rate were optimized. Three heteropoly acids, phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and silicotungstic acid (STA) were incorporated into the anode catalyst layer in combination with Pt/C. Both PTA-Pt and STA-Pt showed higher performance than the Pt control at 30 psig of backpressure. Anodic polarizations were also performed, and Tafel slopes were extracted from the data. The trends in the Tafel slope values are in agreement with the polarization data. The addition of phosphotungstic acid more than doubled the power density of the fuel cell, compared to the Pt control.

Ferrell III, J. R.; Turner, J. A.; Herring, A. M.

2008-01-01

68

Structural Requirements and Reaction Pathways in Dimethyl Ether Combustion Catalyzed by Supported Pt Clusters  

SciTech Connect

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The identity and reversibility of the elementary steps required for catalytic combustion of dimethyl ether (DME) on Pt clusters were determined by combining isotopic and kinetic analyses with density functional theory estimates of reaction energies and activation barriers to probe the lowest energy paths. Reaction rates are limited by C-H bond activation in DME molecules adsorbed on surfaces of Pt clusters containing chemisorbed oxygen atoms at near-saturation coverages. Reaction energies and activation barriers for C-H bond activation in DME to form methoxymethyl and hydroxyl surface intermediates show that this step is more favorable than the activation of C-O bonds to form two methoxides, consistent with measured rates and kinetic isotope effects. This kinetic preference is driven by the greater stability of the CH3OCH2* and OH* intermediates relative to chemisorbed methoxides. Experimental activation barriers on Pt clusters agree with density functional theory (DFT)-derived barriers on oxygen-covered Pt(111). Measured DME turnover rates increased with increasing DME pressure, but decreased as the O2 pressure increased, because vacancies (*) on Pt surfaces nearly saturated with chemisorbed oxygen are required for DME chemisorption. DFT calculations show that although these surface vacancies are required, higher oxygen coverages lead to lower C-H activation barriers, because the basicity of oxygen adatoms increases with coverage and they become more effective in hydrogen abstraction from DME. Water inhibits reaction rates via quasi-equilibrated adsorption on vacancy sites, consistent with DFT results indicating that water binds more strongly than DME on vacancies. These conclusions are consistent with the measured kinetic response of combustion rates to DME, O2, and H2O, with H/D kinetic isotope effects, and with the absence of isotopic scrambling in reactants containing isotopic mixtures of 18O2-16O2 or 12CH3O12CH3-13CH3O13- CH3. Turnover rates increased with Pt cluster size, because small clusters, with more coordinatively unsaturated surface atoms, bind oxygen atoms more strongly than larger clusters and exhibit lower steadystate vacancy concentrations and a consequently smaller number of adsorbed DME intermediates involved in kinetically relevant steps. These effects of cluster size and metal-oxygen bond energies on reactivity are ubiquitous in oxidation reactions requiring vacancies on surfaces nearly saturated with intermediates derived from O2.

Ishikawa, Akio; Neurock, Matthew; Iglesia, Enrique

2007-10-31

69

Structural requirements and reaction pathways in dimethyl ether combustion catalyzed by supported Pt clusters.  

PubMed

The identity and reversibility of the elementary steps required for catalytic combustion of dimethyl ether (DME) on Pt clusters were determined by combining isotopic and kinetic analyses with density functional theory estimates of reaction energies and activation barriers to probe the lowest energy paths. Reaction rates are limited by C-H bond activation in DME molecules adsorbed on surfaces of Pt clusters containing chemisorbed oxygen atoms at near-saturation coverages. Reaction energies and activation barriers for C-H bond activation in DME to form methoxymethyl and hydroxyl surface intermediates show that this step is more favorable than the activation of C-O bonds to form two methoxides, consistent with measured rates and kinetic isotope effects. This kinetic preference is driven by the greater stability of the CH3OCH2* and OH* intermediates relative to chemisorbed methoxides. Experimental activation barriers on Pt clusters agree with density functional theory (DFT)-derived barriers on oxygen-covered Pt(111). Measured DME turnover rates increased with increasing DME pressure, but decreased as the O2 pressure increased, because vacancies (*) on Pt surfaces nearly saturated with chemisorbed oxygen are required for DME chemisorption. DFT calculations show that although these surface vacancies are required, higher oxygen coverages lead to lower C-H activation barriers, because the basicity of oxygen adatoms increases with coverage and they become more effective in hydrogen abstraction from DME. Water inhibits reaction rates via quasi-equilibrated adsorption on vacancy sites, consistent with DFT results indicating that water binds more strongly than DME on vacancies. These conclusions are consistent with the measured kinetic response of combustion rates to DME, O2, and H2O, with H/D kinetic isotope effects, and with the absence of isotopic scrambling in reactants containing isotopic mixtures of 18O2-16O2 or 12CH3O12CH3-13CH3O13CH3. Turnover rates increased with Pt cluster size, because small clusters, with more coordinatively unsaturated surface atoms, bind oxygen atoms more strongly than larger clusters and exhibit lower steady-state vacancy concentrations and a consequently smaller number of adsorbed DME intermediates involved in kinetically relevant steps. These effects of cluster size and metal-oxygen bond energies on reactivity are ubiquitous in oxidation reactions requiring vacancies on surfaces nearly saturated with intermediates derived from O2. PMID:17915866

Ishikawa, Akio; Neurock, Matthew; Iglesia, Enrique

2007-10-31

70

Metal Ion Binding: An Electronic Structure Study of M+(dimethyl ether)(n), M= Cu, Ag and Au, (n= 1 - 4) Complexes  

SciTech Connect

The structures and incremental binding enthalpies of cation-ligand complexes formed from a single coinage metal cation (Cu+, Ag+ and Au+) and as many as four dimethyl ether (DME) ligands are studied with second order perturbation theory (MP2) and coupled cluster theory (CCSD(T)). Basis sets of up to augmented quintuple zeta quality were used in an effort to minimize basis set truncation error. The present results are compared with recent collision-induced dissociation measurements for the Cu+(DME)n complexes, as well as with related complexes in which water either replaces dimethyl ether as the ligand or alkali metal cations replace the coinage metals. Agreement between the theoretical and experimental incremental binding enthalpies (kcal/mol) is good for the two larger copper complexes: DH0(Cu+(DME)3)= 13.9 (theory) vs 13.1? 0.9 kcal/mol (expt.) and DH0(Cu+(DME)4)=11.5 (theory) vs 10.8? 2.3 (expt.). For the two smaller, more tightly bound copper complexes, the level of agreement i s somewhat poorer: DH0(Cu+(DME))= 48.4 (theory) vs 44.3? 2.7 kcal/mol (expt.) and DH0(Cu+(DME)2)= 51.3 (theory) vs 46.1? 1.8 (expt.). In general, DME binds copper, silver and gold 15% - 25% more strongly than water.

Feller, David F.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Dixon, David A.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)

2002-01-01

71

Extraction of Fucoxanthin from Raw Macroalgae excluding Drying and Cell Wall Disruption by Liquefied Dimethyl Ether  

PubMed Central

Macroalgae are one of potential sources for carotenoids, such as fucoxanthin, which are consumed by humans and animals. This carotenoid has been applied in both the pharmaceutical and food industries. In this study, extraction of fucoxanthin from wet brown seaweed Undaria pinnatifida (water content was 93.2%) was carried out with a simple method using liquefied dimethyl ether (DME) as an extractant in semi-continuous flow-type system. The extraction temperature and absolute pressure were 25 °C and 0.59 MPa, respectively. The liquefied DME was passed through the extractor that filled by U. pinnatifida at different time intervals. The time of experiment was only 43 min. The amount of fucoxanthin could approach to 390 ?g/g dry of wet U. pinnatifida when the amount of DME used was 286 g. Compared with ethanol Soxhlet and supercritical CO2 extraction, which includes drying and cell disruption, the result was quite high. Thus, DME extraction process appears to be a good method for fucoxanthin recovery from U. pinnatifida with improved yields. PMID:24796299

Kanda, Hideki; Kamo, Yuichi; Machmudah, Siti; Wahyudiono; Goto, Motonobu

2014-01-01

72

Scale study of direct synthesis of dimethyl ether from biomass synthesis gas.  

PubMed

We investigated the synthesis of dimethyl ether (DME) from biomass synthesis gas using a kind of hybrid catalyst consisting of methanol and HZSM-5 zeolite in a fixed-bed reactor in a 100 ton/year pilot plant. The biomass synthesis gas was produced by oxygen-rich gasification of corn core in a two-stage fixed bed. The results showed that CO conversions reached 82.00% and 73.55%, the selectivities for DME were 73.95% and 69.73%, and the space-time yields were 124.28 kg m(-3) h(-1) and 203.80 kg m(-3) h(-1) when gas hourly space velocities were 650 h(-1) and 1200 h(-1), respectively. Deoxidation and tar removal from biomass synthesis gas was critical to the stable operation of the DME synthesis system. Using single-pass synthesis, the H(2)/CO ratio improved from 0.98-1.17 to 2.12-2.22. The yield of DME would be increased greatly if the exhaust was reused after removal of the CO(2). PMID:19393311

Lv, Yongxing; Wang, Tiejun; Wu, Chuangzhi; Ma, Longlong; Zhou, Yi

2009-01-01

73

Selective homogeneous synthesis of dimethyl ether from methanol.  

PubMed

Selected Brønsted acidic ionic liquids were tested as homogeneous catalysts for the dehydration of methanol to dimethyl ether. Ionic liquids incorporating an alkanesulfonic acid as a part of the cation, a complex acidic anion, [A(2)H](-), or both, proved to be good catalysts for this process, providing high conversions and selectivities. Homogeneous catalysis in the liquid state represents a novel approach to dimethyl ether synthesis. PMID:20177636

Atkins, Martin P; Earle, Martyn J; Seddon, Kenneth R; Swad?ba-Kwa?ny, Ma?gorzata; Vanoye, Laurent

2010-03-14

74

Combustion and emission characteristics of DME as an alternative fuel for compression ignition engines with a high pressure injection system  

Microsoft Academic Search

The subject of this work is the investigation of the injection characteristics of neat dimethyl ether (DME) and the effect of DME fuel on the exhaust emission characteristics and engine performance of compression ignition engines. In order to analyze the injection characteristics of DME fuel as an alternative fuel for compression ignition engines, experiments were conducted to obtain the injection

Myung Yoon Kim; Seung Hyun Yoon; Bong Woo Ryu; Chang Sik Lee

2008-01-01

75

Lecithin microemulsions in dimethyl ether and propane for the generation of pharmaceutical aerosols containing polar solutes.  

PubMed

Water soluble compounds have been incorporated into solution phase metered dose inhalers (MDIs) utilizing lecithin inverse microemulsions in dimethyl ether (DME) and propane. DME and propane acted as both solvent and propellant. Experiments utilizing model propellants (dimethylethyleneglycol (DMEG) and hexane) were used to investigate microemulsion physicochemical phenomena, and the results were used to design and interpret the technically more challenging MDI experiments. NMR and viscosity experiments with model propellants were consistent with a "sphere-to-string" micellar shape change as the solvent was varied from pure DMEG to pure hexane. Water soluble solutes, including selected peptides and fluorescently labeled poly-alpha, beta-[N-(2-hydroxyethyl) D,L-aspartamide] (fPHEAs), dissolved in DME/propane dependent on lecithin and water content. MDIs containing microemulsions generated aerosols with mass median aerodynamic values ranging from 2.7 to 3.1 microns, within the range of commercially available formulations. Fine particle fraction values (50-70%) exceeded those of commercial formulations. fPHEA up to 18 kDa did not adversely affect the aerosol characteristics. Deposition of the aerosol onto a water surface resulted in the formation of liposomes with partially entrapped solute. PMID:12229259

Sommerville, Mark L; Johnson, Charles S; Cain, Judith B; Rypacek, Franticek; Hickey, Anthony J

2002-01-01

76

Catalyst deactivation studies in the dimethyl ether-to-hydrocarbons process  

SciTech Connect

The conversion of Dimethyl Ether (DME) to hydrocarbons is the latter step in the conversion of coal-derived syngas to hydrocarbons via DME. The shape-selective ZSM-5 zeolite catalysts play an instrumental part in this reaction in limiting the higher end of the product spectrum. This process being of an exothermic nature, the temperature rise across the catalyst bed causes some hydrocarbons to be deposited on the catalyst as coke. The presence of water as a by-product in the catalyst environment also enhances the catalyst deactivation. Deactivation of the ZSM-5 catalyst is studied in detail in terms of catalyst performance and life over a period of time. The conversion of DME and the hydrocarbon product distribution are studied as a function of time-on-stream. The SiO{sub 2}/Al{sub 2}O{sub 3} molar ratio of the ZSM-5 catalyst is regarded to be important in determining the degree of coke formation as well as the product distribution of the final hydrocarbon product. Catalysts used in aging experiments were studied as to determine the quantity and structure of the deposited coke. Extracted coke from the catalyst was analyzed via GC/MS methods.

Sardesai, A.; Tartamella, T.L.; Lee, S. [Univ. of Akron, OH (United States). Dept. of Chemical Engineering

1996-12-31

77

Study on systems based on coal and natural gas for producing dimethyl ether  

SciTech Connect

China is a coal-dependent country and will remain so for a long time. Dimethyl ether (DME), a potential substitute for liquid fuel, is a kind of clean diesel motor fuel. The production of DME from coal is meaningful and is studied in this article. Considering the C/H ratios of coal and natural gas (NG), the cofeed (coal and NG) system (CFS), which does not contain the water gas shift process, is studied. It can reduce CO{sub 2} emission and increase the conversion rate of carbon, producing more DME. The CFS is simulated and compared with the coal-based and NG-based systems with different recycling ratios. The part of the exhaust gas that is not recycled is burned, producing electricity. On the basis of the simulation results, the thermal efficiency, economic index, and CO{sub 2} emission ratio are calculated separately. The CFS with a 100% recycling ratio has the best comprehensive evaluation index, while the energy, economy, and environment were considered at the same time.

Zhou, L.; Hu, S.Y.; Chen, D.J.; Li, Y.R.; Zhu, B.; Jin, Y. [Tsinghua University, Beijing (China). Dept. of Chemical Engineering

2009-04-15

78

Selective inhibition of ammonium oxidation and nitrification-linked N2O formation by methyl fluoride and dimethyl ether  

USGS Publications Warehouse

Methyl fluoride (CH3F) and dimethyl ether (DME) inhibited nitrification in washed-cell suspensions of Nitrosomonas europaea and in a variety of oxygenated soils and sediments. Headspace additions of CH3F (10% [vol/vol]) and DME (25% [vol/vol]) fully inhibited NO2- and N2O production from NH4+ in incubations of N. europaea, while lower concentrations of these gases resulted in partial inhibition. Oxidation of hydroxylamine (NH2OH) by N. europaea and oxidation of NO2- by a Nitrobacter sp. were unaffected by CH3F or DME. In nitrifying soils, CH3F and DME inhibited N2O production. In field experiments with surface flux chambers and intact cores, CH3F reduced the release of N2O from soils to the atmosphere by 20- to 30-fold. Inhibition by CH3F also resulted in decreased NO3- + NO2- levels and increased NH4+ levels in soils. CH3F did not affect patterns of dissimilatory nitrate reduction to ammonia in cell suspensions of a nitrate- respiring bacterium, nor did it affect N2O metabolism in denitrifying soils. CH3F and DME will be useful in discriminating N2O production via nitrification and denitrification when both processes occur and in decoupling these processes by blocking NO2- and NO3- production.

Miller, L.G.; Coutlakis, M.D.; Oremland, R.S.; Ward, B.B.

1993-01-01

79

QM/MM molecular dynamics study of the potential of mean force for the association of K{sup +} with dimethyl ether in aqueous solution  

SciTech Connect

We present a hybrid Quantum Mechanical/Molecular Mechanical (QM/MM) molecular dynamics study of the free energy profile for the association of K{sup +} with dimethyl ether (DME) in H{sub 2}O. We calculate a potential of mean force and find a weak solvent separated ion-dipole pair (SSIDP) at 5.4 A separation and a contact ion-dipole (CIDP) free energy minimum at 2.7 A separation of the K{sup +} with the oxygen of DME. The latter distance agrees well with the gas-phase optimized K{sup +}/DME structure. This study demonstrates the nonadditive interactions of a solvated cation with a simple monodentate organic ligand. These results are useful for interpreting K{sup +} complexation by multidentate ligands, such as the crown ethers. 36 refs., 4 figs., 1 tab.

Thompson, M.A. [Pacific Northwest Lab., Richland, WA (United States)

1995-11-15

80

ULEV potential of a DI/TCI diesel passenger car engine operated on dimethyl ether  

SciTech Connect

This paper describes a feasibility test program on a 2 liter, 4 cylinder DI/TCI passenger car engine operated on the new alternative fuel Dimethyl Ether (DME) with the aim of demonstrating its potential of meeting ULEV (ultra low emission vehicle) emissions (0.2 g/mi NOx in the FTP 75 test cycle) when installed in a full size passenger car. Special attention is drawn to the fuel injection equipment (FIE) as well as combustion system requirements towards the reduction of NOx and combustion noise while keeping energetic fuel consumption at the level of he baseline DI/TCI diesel engine. FIE and combustion system parameters were optimized on the steady state dynamometer by variation of a number of parameters, such as rate of injection, number of nozzle holes, compression ratio, piston bowl shape and exhaust gas recirculation. The paper presents engine test results achieved with DME under various operating conditions and compares these results to those achieved with the diesel version of the same engine.The FTP 75 cycle results were projected from steady state engine maps using a vehicle simulation program taking into account vehicle data and road resistance data of a given vehicle.The cycle results are also compared to actual chassis dynamometer results achieved with the diesel version of the same engine installed in the same vehicle.the passenger car DI/TCI engine adapted for and operated on DME shows very promising results with respect to meeting ULEV NOx emissions without any soot emissions and without the need for a DENOX catalyst. DME fuel consumption on energy basis can be kept very close to the DI diesel value. An oxidation catalyst will be necessary to meet the stringent CO and HC ULEV emission limits.

Kapus, P.E.; Cartellieri, W.P.

1995-12-31

81

Torsionally Excited Dimethyl Ether in the Laboratory and in Space  

NASA Astrophysics Data System (ADS)

Dimethyl ether (DME) is highly abundant in hot cores and numerous transitions within the vibrational ground state have been detected in various interstellar line surveys of sources such as Orion KL. As a nearly prolate asymmetric top with two internal rotors, it shows a complex spectrum with low lying torsional modes. The energy levels of the two lowest torsional states (v11, and v15) lie only 200 and 240 cm-1 above the ground state (barrier height ? 915 cm-1), and are thus sufficiently populated in these interstellar sources to exhibit transitions in line surveys due to high excitation temperatures in hot cores. So far, the lack of sufficiently accurate predictions for the two lowest excited torsional states prevented their identification in astronomical spectra. Therefore, we analyzed spectra, which have been recorded within the context of the investigations of the ground state. In total, more than 9500 transitions have been assigned covering the frequency range from 38 up to 1670 GHz. The enlarged splitting of each rotational level into four substates (AA, EE, AE, EA) compared to its size in the ground state and a large number of perturbed transitions hampered not only the line assignment but also the astrophysical modelling. However, the inclusion of interaction terms between both excited states in the model of an effective Hamiltonian for a symmetric two-top rotor, allowed us to model both excited states within a global fit, and also to accurately determine the energy difference between both states. Frequency predictions have been calculated based on this analysis and have been used to unambiguously assign numerous rotational transitions within these excited states in the astronomical line survey of the hot core region G327.3-0.6. P. Schilke, T.D. Groesbeck et al., Astrophys.J.Suppl.Ser., 108,(1997) 301-337 P. Schilke, D.J. Benford, T.R. Hunter et al., Astrophys.J.Suppl.Ser., 132,(2001) 281-364. P. Groner, S. Albert, E. Herbst, and F.C. De Lucia, Astrophys. J., 500, (1998) 1059-1063 C.P. Endres, B.J. Drouin et al., Astronom.Astrophys., 504, (2009) 635-640

Endres, C. P.; Müller, H. S. P.; Lewen, F.; Giesen, T. F.; Schlemmer, S.; Drouin, B. J.; Bisschop, S.; Groner, P.

2010-06-01

82

Single-step syngas-to-dimethyl ether processes for optimal productivity, minimal emissions, and natural gas-derived syngas  

SciTech Connect

Process schemes for single-step syngas-to-dimethyl ether (DME) were developed in two stages: (1) the performance of the syngas-to-DME reactor was optimized with respect to the feed gas composition and (2) the optimal reactor feed gas system was integrated with synthesis gas generators. It was shown that the reactor performance is very sensitive to the H{sub 2}:CO ratio in the feed gas. The optimal DME productivity and best material utilization were obtained with a feed gas containing 50% hydrogen and 50% carbon monoxide. In the second phase the syngas generation units considered were CO{sub 2}-methane reformer, steam-methane reformer, methane partial oxidation, and coal gasifier. The integration adjusts the H{sub 2}:CO ratio in natural gas-derived syngas to fit the optimal DME reactor operation and minimizes CO{sub 2} emissions and material loss. The technical feasibility of these schemes was demonstrated by simulations using realistic reactor models, kinetics, and thermodynamics under commercially relevant conditions.

Peng, X.D.; Wang, A.W.; Toseland, B.A.; Tijm, P.J.A.

1999-11-01

83

Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas  

SciTech Connect

As part of the DOE-sponsored contract for the Synthesis of Dimethyl Ether (DME) and Alternative Fuels in the Liquid Phase from Coal- Derived Syngas, the single-step, slurry phase DME synthesis process was developed. The development involved screening of catalyst systems, process variable studies, and catalyst life studies in two 300 ml stirred autoclaves. As a spin-off of the Liquid Phase Methanol (LPMEOH*) process, the new process significantly improves the syngas conversion efficiency of the LPMEOH process. This improvement can be achieved by replacing a portion of methanol catalyst with a dehydration catalyst in the reactor, resulting in the product methanol being converted to DME, thus avoiding the thermodynamic equilibrium constraint of the methanol reaction. Overall, this increases syngas conversion per-pass. The selectivity and productivity of DME and methanol are affected by the catalyst system employed as well as operating conditions. A preferred catalyst system, consisting of a physical mixture of a methanol catalyst and a gamma alumina, was identified. An improvement of about 50% in methanol equivalent productivity was achieved compared to the LPMEOH process. Results from the process variable study indicate that higher pressure and CO[sub 2] removal benefit the process significantly. Limited life studies performed on the preferred catalyst system suggest somewhat higher than expected deactivation rate for the methanol catalyst. Several DME/methanol mixtures were measured for their key properties as transportation fuels. With small amounts of DME added, significant improvements in both flash points and Reid Vapor Pressure (RVP) were observed over the corresponding values of methanol alone.

Bhatt, B.L.

1992-09-01

84

Property of LCP-GEM in Pure Dimethyl Ether at Low Pressure  

E-print Network

We present a systematic investigation of the gain properties of a gas electron multiplier (GEM) foil in pure dimethyl ether (DME) at low pressures. The GEM is made from copper- clad liquid crystal polymer insulator (LCP-GEM) designed for space use, and is applied to a time projection chamber filled with low-pressure DME gas to observe the linear polarization of cosmic X-rays. We have measured gains of a 100 um-thick LCP-GEM as a function of the voltage between GEM electrodes at various gas pressures ranging from 10 to 190 Torr with 6.4 keV X-rays. The highest gain at 190 Torr is about 2x10^4, while that at 20 Torr is about 500. We find that the pressure and electric-field dependence of the GEM gain is described by the first Townsend coefficient. The energy scale from 4.5 to 8.0 keV is linear with non-linearity of less than 1.4% above 30 Torr.

Takeuchi, Y; Kitaguchi, T; Yamada, S; Iwakiri, W; Asami, F; Yoshikawa, A; Kaneko, K; Enoto, T; Hayato, A; Kohmura, T

2013-01-01

85

Spectral and polarimetric characterization of the Gas Pixel Detector filled with dimethyl ether  

NASA Astrophysics Data System (ADS)

The Gas Pixel Detector belongs to the very limited class of gas detectors optimized for the measurement of X-ray polarization in the emission of astrophysical sources. The choice of the mixture in which X-ray photons are absorbed and photoelectrons propagate, deeply affects both the energy range of the instrument and its performance in terms of gain, track dimension and ultimately, polarimetric sensitivity. Here we present the characterization of the Gas Pixel Detector with a 1 cm thick cell filled with dimethyl ether (DME) at 0.79 atm, selected among other mixtures for the very low diffusion coefficient. Almost completely polarized and monochromatic photons were produced at the calibration facility built at INAF/IASF-Rome exploiting Bragg diffraction at nearly 45°. For the first time ever, we measured the modulation factor and the spectral capabilities of the instrument at energies as low as 2.0 keV, but also at 2.6, 3.7, 4.0, 5.2 and 7.8 keV. These measurements cover almost completely the energy range of the instrument and allows to compare the sensitivity achieved with that of the standard mixture, composed of helium and DME.

Muleri, F.; Soffitta, P.; Baldini, L.; Bellazzini, R.; Brez, A.; Costa, E.; Fabiani, S.; Krummenacher, F.; Latronico, L.; Lazzarotto, F.; Minuti, M.; Pinchera, M.; Rubini, A.; Sgró, C.; Spandre, G.

2010-08-01

86

Laser-induced plasma in methane and dimethyl ether for flame ignition and combustion diagnostics  

NASA Astrophysics Data System (ADS)

In this paper we report the investigation of the laser-induced breakdown and ignition behaviour of methane/air and dimethyl ether (DME)/air mixtures. Moreover, the optical emission from the induced plasma is utilized for determining the mixture composition quantitatively by means of laser-induced breakdown spectroscopy (LIBS). To the best of the authors' knowledge, LIBS and laser ignition of DME have not been reported in literature before. The technique under investigation is finally employed for combustion diagnostics in laminar as well as turbulent flames. In the laminar premixed and non-premixed flames the LIBS spectra allow spatially resolved measurements of the equivalence ratio and enable studying the mixing of gases provided through the burner with the surrounding room air. In addition, the breakdown threshold of the applied laser pulse energy yields an estimate for the local temperature. In the turbulent cases single-shot LIBS spectra are recorded at fixed position allowing the derivation of local statistical fluctuations of the equivalence ratio in partially premixed jet flames. The results show that laser-induced breakdowns have a strong potential for flame diagnostics and, under suitable conditions, for the ignition of combustible mixtures.

Kiefer, J.; Tröger, J. W.; Li, Z. S.; Aldén, M.

2011-04-01

87

Experimental and Computational Study of Nonpremixed Ignition of Dimethyl Ether in Counterflow  

SciTech Connect

The ignition temperature of nitrogen-diluted dimethyl ether (DME) by heated air in counterflow was experimentally determined for DME concentration from 5.9 to 30%, system pressure from 1.5 to 3.0 atmospheres, and pressure-weighted strain rate from 110 to 170/s. These experimental data were compared with two mechanisms that were respectively available in 1998 and 2003, with the latter being a substantially updated version of the former. The comparison showed that while the 1998-mechanism uniformly over-predicted the ignition temperature, the 2003-mechanism yielded surprisingly close agreement for all experimental data. Sensitivity analysis for the near-ignition state based on both mechanisms identified the deficiencies of the 1998-mechanism, particularly the specifics of the low-temperature cool flame chemistry in effecting ignition at higher temperatures, as the fuel stream is being progressively heated from its cold boundary to the high-temperature ignition region around the hot-stream boundary. The 2003-mechanism, consisting of 79 species and 398 elementary reactions, was then systematically simplified by using the directed relation graph method to a skeletal mechanism of 49 species and 251 elementary reactions, which in turn was further simplified by using computational singular perturbation method and quasi-steady-state species assumption to a reduced mechanism consisting of 33 species and 28 lumped reactions. It was demonstrated that both the skeletal and reduced mechanisms mimicked the performance of the detailed mechanism with high accuracy.

Zheng, X L; Lu, T F; Law, C K; Westbrook, C K

2003-12-19

88

Synthesis of Methanol and Dimethyl Ether from Syngas over Pd/ZnO/Al2O3 Catalysts  

SciTech Connect

A Pd/ZnO/Al2O3 catalyst was developed for the synthesis of methanol and dimethyl ether (DME) from syngas. Studied were temperatures of operation ranging from 250°C to 380°C. High temperatures (e.g. 380°C) are necessary when combining methanol and DME synthesis with a methanol to gasoline (MTG) process in a single reactor bed. A commercial Cu/ZnO/Al2O3 catalyst, utilized industrially for the synthesis of methanol at 220-280°C, suffers from a rapid deactivation when the reaction is conducted at high temperature (>320°C). On the contrary, a Pd/ZnO/Al2O3 catalyst was found to be highly stable for methanol and DME synthesis at 380°C. The Pd/ZnO/Al2O3 catalyst was thus further investigated for methanol and DME synthesis at P=34-69 bars, T= 250-380°C, GHSV= 5 000-18 000 h-1, and molar feeds H2/CO= 1, 2, and 3. Selectivity to DME increased with decreasing operating temperature, and increasing operating pressure. Increased GHSV’s and H2/CO syngas feed ratios also enhanced DME selectivity. Undesirable CH4 formation was observed, however, can be minimized through choice of process conditions and by catalyst design. By studying the effect of the Pd loading and the Pd:Zn molar ratio the formulation of the Pd/ZnO/Al2O3 catalyst was optimized. A catalyst with 5% Pd and a Pd:Zn molar ratio of 0.25:1 has been identified as the preferred catalyst. Results indicate that PdZn particles are more active than Pdº particles for the synthesis of methanol and less active for CH4 formation. A correlation between DME selectivity and the concentration of acid sites of the catalysts has been established. Hence, two types of sites are required for the direct conversion of syngas to DME: 1) PdZn particles are active for the synthesis of methanol from syngas, and 2) acid sites which are active for the conversion of methanol to DME. Additionally, CO2 formation was problematic as PdZn was found to be active for the water-gas-shift (WGS) reaction, under all the conditions evaluated.

Lebarbier, Vanessa MC; Dagle, Robert A.; Kovarik, Libor; Lizarazo Adarme, Jair A.; King, David L.; Palo, Daniel R.

2012-10-01

89

Detonation characteristics of dimethyl ether and ethanol-air mixtures  

NASA Astrophysics Data System (ADS)

The detonation cell structure in dimethyl ether vapor and ethanol vapor-air mixtures was measured at atmospheric pressure and initial temperatures in the range of 293-373 K. Tests were carried out in a 6.2-m-long, 10-cm inner diameter tube. For more reactive mixtures, a series of orifice plates were used to promote deflagration-to-detonation transition in the first half of the tube. For less reactive mixtures prompt detonation initiation was achieved with an acetylene-oxygen driver. The soot foil technique was used to capture the detonation cell structure. The measured cell size was compared to the calculated one-dimensional detonation reaction zone length. For fuel-rich dimethyl ether mixtures the calculated reaction zone is highlighted by a temperature gradient profile with two maxima, i.e., double heat release. The detonation cell structure was interpreted as having two characteristic sizes over the full range of mixture compositions. For mixtures at the detonation propagation limits the large cellular structure approached a single-head spin, and the smaller cells approached the size of the tube diameter. There is little evidence to support the idea that the two cell sizes observed on the foils are related to the double heat release predicted for the rich mixtures. There was very little influence of initial temperature on the cell size over the temperature range investigated. A double heat release zone was not predicted for ethanol-air detonations. The detonation cell size for stoichiometric ethanol-air was found to be similar to the size of the small cells for dimethyl ether. The measured cell size for ethanol-air did not vary much with composition in the range of 30-40 mm. For mixtures near stoichiometric it was difficult to discern multiple cell sizes. However, near the detonation limits there was strong evidence of a larger cell structure similar to that observed in dimethyl ether air mixtures.

Diakow, P.; Cross, M.; Ciccarelli, G.

2015-02-01

90

Low-pressure DME synthesis with Cu-based hybrid catalysts using temperature-gradient reactor  

Microsoft Academic Search

Dimethyl ether (DME), the target product of this study, has many advantages as diesel fuel. The aim of this study is to develop a catalytic process in which 90% CO conversion to DME and CO2 from syngas (3CO+3H2?DME+CO2) is attained at 1–3MPa. In such a process, both recycling loop and compression of syngas can be omitted resulting in an economic

Kohji Omata; Yuhsuke Watanabe; Tetsuo Umegaki; Gunji Ishiguro; Muneyoshi Yamada

2002-01-01

91

Pressure and temperature dependence of excess enthalpies of methanol + tetraethylene glycol dimethyl ether and methanol + polyethylene glycol dimethyl ether 250  

SciTech Connect

The excess molar enthalpies at 323.15 K, 373.15 K, and 423.15 K, at 8 MPa, are reported for the binary mixtures methanol + tetraethylene glycol dimethyl ether (TEGDME) and methanol + poly(ethylene glycol) dimethyl ether 250 (PEGDME 250). Excess molar enthalpies were determined with a Setaram C-80 calorimeter equipped with a flow mixing cell. For both systems, the excess enthalpies are positive over the whole composition range, increasing with temperature. The H{sup E}(x) curves are slightly asymmetrical, and their maxima are skewed toward the methanol-rich region. The excess enthalpies slightly change with the pressure, the sign of this change being composition-dependent. In the case of mixtures with TEGDME, the experimental H{sup E} values have been compared with those predicted with the Gmehling et al. version of UNIFAC (Dortmund) and the Nitta-Chao and DISQUAC group contribution models.

Lopez, E.R.; Coxam, J.Y.; Fernandez, J.; Grolier, J.P.E.

1999-12-01

92

The Mark III vertex chamber: Studies using DME  

SciTech Connect

Studies have been performed using a prototype of a pressurized wire vertex chamber with 8 mm diameter straw geometry. A 35 ..mu..m spatial resolution using dimethyl ether (DME) at 1 bar and 30 ..mu..m using argon ethane (50/50 mixture) at 4 bar was obtained. Preliminary studies show the DME to adversely affect such materials as aluminized Mylar and Delrin.

Pitman, D.

1987-04-01

93

Analysis of energy release and NO x emissions of a CI engine fuelled on diesel and DME  

Microsoft Academic Search

Combustion and NOx emissions from a dimethyl ether (DME) fuelled compression ignition engine were investigated. The test engine used consisted of an unmodified two-cylinder direct injection four-stroke air cooled type. The injection timing and injector opening pressure were left unaltered from their diesel fuelling settings. Analysis of the fuel line pressure shows that due to the compressibility of DME the

D. Cipolat

2007-01-01

94

On the competition between hydrogen abstraction versus C-O bond fission in initiating dimethyl ether combustion  

SciTech Connect

There has been a growing interest in the potential use of dimethyl ether (DME) as a diesel fuel in compression ignition engines. There are two initiation steps involved in the combustion of DME, one involving C-O bond fission and the other involving hydrogen abstraction by molecular oxygen. The kinetics and thermodynamics of C-O bond fission were explored computationally in a previous paper. The present paper addresses the competing process--hydrogen abstraction by molecular oxygen. Ab initio molecular orbital calculations are used to study the structures and energetics of the reactants, products, and the transition state for the CH{sub 3}OCH{sub 3} + O{sub 2} reaction. The calculations predict a barrier for hydrogen abstraction from CH{sub 3}OCH{sub 3} by O{sub 2} of 47.4 kcal/mol. This is lower than the barrier height for C-O bond fission previously calculated to be 81.1 kcal/mol. The results support values used in current models for the combustion of DME. Moreover, an examination of rates for C-O bond fission versus hydrogen abstraction by O{sub 2} suggests that the bimolecular process is the dominant pathway.

Francisco, J. [Purdue Univ., West Lafayette, IN (United States). Dept. of Chemistry] [Purdue Univ., West Lafayette, IN (United States). Dept. of Chemistry

1999-07-01

95

Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived syngas; Quarterly technical progress report No. 2, 1 April--30 June 1990  

SciTech Connect

Contract objectives are: development of a one-step liquid phase dimethyl ether/methanol process; and investigation of the potential of liquid phase synthesis of alternative fuels from coal-derived synthesis gas. In the one-step liquid phase Dimethyl Ether (DME) program, the optimum ratio of methanol synthesis catalyst to DME forming catalyst is forming 4.3 to 1 under reaction conditions of 250{degrees}C and 750 psig. At a commercially significant space velocity of 6000 sl/kg-hr, the methanol equivalent productivity is 50% higher than that for methanol synthesis alone. Using Shell gas instead of ``CO-rich`` (Texaco) gas leads to lower DME productivity due to the lower hydrogen content. In exploratory tests for new fuels produced directly from syngas, a slurry of H-ZSM-5 zeolite in a Decalin liquid medium successfully produced DME and C{sub 2}-C{sub 4} alkanes from a syngas/methanol feedstock. As anticipated, Decalin was less easily cracked by the ZSM-5. A slurry consisting of a 50/50 mixture of S3-86 methanol catalyst and H-ZSM-5 zeolite in Decalin produced C1-C7 hydrocarbons, DME and methanol from a CO-rich gas feed. The non-optimum conditions, however, resulted in a poor selectivity to gasoline -- boiling hydrocarbons (2.5% by wt.). More tests are planned for July. In exploratory work on new fuels, Cesium doping of the S3-86 methanol catalyst gave good yields (11--23 wt %) of higher, C{sub 2}-C{sub 5}, alcohols in a liquid phase unit. Liquid stability was excellent. 6 tabs., 22 figs.

NONE

1991-01-11

96

Consider the DME alternative for diesel engines  

SciTech Connect

Engine tests demonstrate that dimethyl ether (DME, CH{sub 3}OCH{sub 3}) can provide an alternative approach toward efficient, ultra-clean and quiet compression ignition (CI) engines. From a combustion point of view, DME is an attractive alternative fuel for CI engines, primarily for commercial applications in urban areas, where ultra-low emissions will be required in the future. DME can resolve the classical diesel emission problem of smoke emissions, which are completely eliminated. With a properly developed DME injection and combustion system, NO{sub x} emissions can be reduced to 40% of Euro II or U.S. 1998 limits, and can meet the future ULEV standards of California. Simultaneously, the combustion noise is reduced by as much as 15 dB(A) below diesel levels. In addition, the classical diesel advantages such as high thermal efficiency, compression ignition, engine robustness, etc., are retained.

Fleisch, T.H.; Meurer, P.C.

1996-07-01

97

Inhibition of dimethyl ether and methane oxidation in Methylococcus capsulatus and Methylosinus trichosporium.  

PubMed Central

Metal-chelating or -binding agents inhibited the oxidation of dimethyl ether and methane, but not methanol, by cell suspensions of Methylococcus capsulatus and Methylosinus trichosporium. Evidence suggests that the involvement of metal-containing enzymatic systems in the initial step of oxidation of dimethyl ether and methane. PMID:4428

Patel, R; Hou, C T; Felix, A

1976-01-01

98

Obligate methylotrophy: evaluation of dimethyl ether as a C1 compound.  

PubMed Central

The suitability of dimethyl ether as a C1 compound was examined with the obligate methylobacterium Methylococcus capsulatus (Texas). The ether did not support growth and was not formed during growth on methane; it was an inhibitor of growth and oxidation of methane and a poor oxidation substrate for cell suspensions. NADH stimulation of methane, but not dimethyl ether, oxidation occurred in cell extracts. PMID:6802804

Meyers, A J

1982-01-01

99

Selective homogeneous and heterogeneous catalytic conversion of methanol/dimethyl ether to triptane.  

PubMed

The demand for specific fuels and chemical feed-stocks fluctuates, and as a result, logistical mismatches can occur in the supply of their precursor raw materials such as coal, biomass, crude oil, and methane. To overcome these challenges, industry requires a versatile and robust suite of conversion technologies, many of which are mediated by synthesis gas (CO + H(2)) or methanol/dimethyl ether (DME) intermediates. One such transformation, the conversion of methanol/DME to triptane (2,2,3-trimethylbutane) has spurred particular research interest. Practically, triptane is a high-octane, high-value fuel component, but this transformation also raises fundamental questions: how can such a complex molecule be generated from such a simple precursor with high selectivity? In this Account, we present studies of this reaction carried out in two modes: homogeneously with soluble metal halide catalysts and heterogeneously over solid microporous acid catalysts. Despite their very different compositions, reaction conditions, provenance, and historical scientific context, both processes lead to remarkably similar products and mechanistic interpretations. In both cases, hydrocarbon chains grow by successive methylation in a carbocation-based mechanism. The relative rates of competitive processes-chain growth by methylation, chain termination by hydrogen transfer, isomerization, and cracking-systematically depend upon the structure of the various hydrocarbons produced, strongly favoring the formation of the maximally branched C(7) alkane, triptane. The two catalysts also show parallels in their dependence on acid strength. Stronger acids exhibit higher methanol/DME conversion but also tend to favor chain termination, isomerization, and cracking relative to chain growth, decreasing the preference for triptane. Hence, in both modes, there will be an optimal range: if the acid strength is too low, activity will be poor, but if it is too high, selectivity will be poor. A related reaction, the methylative homologation of alkanes, offers the possibility of upgrading low-value refinery byproducts such as isobutane and isopentane to more valuable gasoline components. With the addition of adamantane, a hydride transfer catalyst that promotes activation of alkanes, both systems effectively catalyze the reaction of methanol/DME with lighter alkanes to produce heavier ones. This transformation has the further advantage of providing stoichiometric balance, whereas the stoichiometry for conversion of methanol/DME to alkanes is deficient in hydrogen and requires rejection of excess carbon in the form of carbon-rich arenes, which lowers the overall yield of desired products. Alternatively, other molecules can serve as sacrificial sources of hydrogen atoms: H(2) on heterogeneous catalysts modified by cations that activate it, and H(3)PO(2) or H(3)PO(3) on homogeneous catalysts. We have interpreted most of the features of these potentially useful reactions at a highly detailed level of mechanistic understanding, and we show that this interpretation applies equally to these two widely disparate types of catalysts. Such approaches can play a key role in developing and optimizing the catalysts that are needed to solve our energy problems. PMID:22277056

Hazari, Nilay; Iglesia, Enrique; Labinger, Jay A; Simonetti, Dante A

2012-04-17

100

IMPACT OF DME-DIESEL FUEL BLEND PROPERTIES ON DIESEL FUEL INJECTION SYSTEMS  

SciTech Connect

The objectives of this research program are to develop information on lubricity and viscosity improvers and their impact on the wear mechanisms in fuel injectors operating on blends of dimethyl ether (DME) and diesel fuel. This project complements another ongoing project titled ''Development of a Dimethyl Ether (DME)-Fueled Shuttle Bus Demonstration Project''. The objectives of that research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In the shuttle bus project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. In this project, they have sought to develop methods for extending the permissible DME content in the DME-diesel blends without experiencing rapid injector failure due to wear. To date, the activities have covered two areas: development of a high-pressure lubricity test apparatus for studies of lubricity and viscosity improvers and development of an injector durability stand for evaluation of wear rates in fuel injectors. This report provides summaries of the progress toward completion of both experimental systems and a summary of the plan for completion of the project objectives.

Elana M. Chapman; Andre L. Boehman; Kimberly Wain; Wallis Lloyd; Joseph M. Perez; Donald Stiver; Joseph Conway

2002-07-01

101

Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived syngas; Quarterly technical progress report No. 3, 1 July--30 September 1990  

SciTech Connect

Contract objectives are: development of a one-step liquid phase dimethyl ether/methanol process; and investigation of the potential of liquid phase synthesis of alternative fuels from coal-derived synthesis gas. Definition of Preferred Catalyst System was completed after several commercial methanol catalysts and dehydration catalysts were tested. BASF S3-86 and Catapal gamma alumina is the preferred catalyst system of choice. Process Variable Scans on the Preferred Catalyst System was started with Shell gas. Data were obtained at various pressures (750 to 1400 psig), temperatures (250 to 280{degrees}C), and space velocities (5000 to 9000 sl/kg-hr). Increase in system pressure seems to have a very significant benefit to both DME and methanol formation. Both Texaco and Shell gases were evaluated. A ``stoichiometric`` feed composition (50% CO, 50% H{sub 2}) that yields maximum DME productivity at equilibrium was evaluated with a fresh batch of the optimum catalyst system. Productivities with the ``stoichiometric`` gas were much higher compared to Shell or Texaco gas. Following that test, Dow gas was evaluated (41% CO, 41% H{sub 2}, 16% CO{sub 2} and 2% N{sub 2}) using the same catalyst to study the effect of CO{sub 2}. Three DME/MEOH (1--4% DME) mixtures were evaluated by SWRI for their fuel properties. Results indicate that, with small amounts of DME added, significant improvements in both flash point and RVP are possible over the properties of LaPorte MEOH. the slurry-phase dehydration of alcohols to ethers was investigated by feeding 10 mol% mixed alcohols in N{sub 2} over an alumina catalyst suspended in mineral oil. Two alcohol mixture compositions were chosen for this study. One mixture contained methanol, ethanol, and 1-propanol in proportions representative of those in IFP Substifuel, while the other mixture contained methanol, ethanol, and isobutanol in proportions representative of those in Lurgi Octamix. 21 figs., 13 tabs.

NONE

1991-01-25

102

The Low Temperature Oxidation of DME and Mutual Sensitization of the Oxidation of DME and Nitric Oxide: Experimental and Detailed Kinetic Modeling  

Microsoft Academic Search

The oxidation of dimethylelher (DME) has been studied experimentally at low-temperature {550-800 K) in a jet-stirred reactor operating at I atm. The mutual sensitization of the oxidation of dimethyl-ether and NO was also studied. It was shown that above 600 K, NO enhances the oxidation of DME in the cool flame regime and yields methylformate (not formed without NO) whereas

PHILIPPE DAGAUT; JOCELYN LUCHE; MICHEL CATHONNET

2001-01-01

103

DME: The next market breakthrough or a methanol-related fuel  

SciTech Connect

Amoco has been involved for several years in the development of technology for the synthesis of liquid fuels from remote natural gas. In a recent collaborative work with Haldor Topsoe S/A, AVL LIST GmbH and Navistar, Amoco identified Dimethyl Ether (DME) as a new, ultraclean alternative fuel for diesel engines. DME can be handled like liquefied petroleum gas (LPG), itself an important alternative transportation fuel. However, unlike most other fuels, the raw exhaust of diesel engines fueled with DME satisfies California 1998 ULEV (Ultra Low Emission Vehicle) standards, now. DME`s greenhouse gas emissions, measured from cradle-to-grave, are lowest among all transportation fuel alternatives. Today, DME is manufactured from methanol and is used primarily as an aerosol propellant because of its attractive physical properties and its environmentally benign characteristics. Haldor Topsoe S/A developed a process for the direct production of DME from natural gas. The process can be used for the large scale manufacture of DME using predominantly single-train process units. When manufactured at large scale, DME can be produced and marketed at a cost comparable to conventional transportation fuels. The market driven demand for DME as a transportation fuel is envisioned to grow in three stages. Initially, DME is envisioned to be produced via methanol dehydration, followed by retrofits, and lastly by large scale dedicated plants. DME fuel demonstration fleet tests are scheduled to commence during 1996. Today`s methanol producer likely also will be tomorrow`s DME producer.

Gradassi, M.J.; Basu, A.; Fleisch, T.H.; Masin, J.G. [Amoco Exploration and Production Technology Group, Naperville, IL (United States)

1995-12-31

104

Rate Constants for the Reactions of Hydroxyl Radical with Several Alkanes, Cycloalkanes, and Dimethyl Ether  

NASA Technical Reports Server (NTRS)

Relative rate experiements were used to measure rate constants and temperature denpendencies of the reactions of OH with propane, n-butane, n-pentane, n-hexane, cyclopropane, cyclobutane, cyclopentane, and dimethyl ether.

DeMore, W.; Bayes, K.

1998-01-01

105

Microwave spectrum of two top molecules in the excited states dimethyl ether, dimethyl sulfide, and dimethyl silane  

NASA Astrophysics Data System (ADS)

Microwave spectra of dimethyl ether, dimethyl sulfide, and dimethyl silane in the torsionally excited states have been measured. The methyl internal rotations of these molecules were analyzed from the observed multiplets and from the reported multiplets of transitions. The method developed for ethyl silane in the previous paper was extended to equivalent two top molecules. For equivalent two top molecules, apparent barriers of methyl internal rotations obtained from the experiments were corrected by the kinetic and potential cross terms. They are V3=2645.8±10.0, 2632.4 ± 42.9, 2146.0 ± 13.8, 1651.5 ± 10.1, 1648.0 ± 13.7, and 1649.9 ± 11.8 cal/mol for (CH 3) 2O, (CD 3) 2O, (CH 3) 2S, (CH 3) 2SiH 2, (CH 3) 2SiD 2, and (CH 3) 2SiHD, respectively. The potential cross terms, V12(1-cos3 ?1)(1-cos3 ?2) terms are negligible for the three molecules, while V'12sin3 ?1sin3 ?2 terms are also very close to zero except those for (CH 3) 2O and (CD 3) 2O which are small but not negligible ( V'12=-124.4,-158.0 cal/mol). The investigations were extended to those of non-equivalent two top species and the corrected barriers of the methyl tops, V3, are obtained to be 2615.6 ± 8.6 and 2155.0 ± 15.2 cal/mol for CH 3OCD 3 and CH 3SCD 3. The corrected barrier, V3(CD 3) of CH 3OCD 3, is obtained to be 2634.4 ± 7.1 cal/mol, while that of CH 3SCD 3 cannot be solved due to the lack of the data available.

Niide, Yuzuru; Hayashi, Michiro

2004-02-01

106

DME-to-oxygenates process studies  

SciTech Connect

The feasibility of the production of hydrocarbons from dimethyl ether (DNM) has been illustrated in a fixed bed micro-reactor as well as a bench scale fluidized bed reactor by the University of Akron/EPRI DME-to-Hydrocarbon (DTG) Process. The DTG process has distinct advantages over its methanol based counterpart. Specifically, the DTG process excels in the area of higher productivity, higher per-pass conversion, and lower heat duties than the MTG process. Also of special importance is the production of oxygenates -- including MTBE, ETBE, and TAME. DME may be reacted with isobutylene to produce a mixture of MTBE and ETBE. The properties of ETBE excel over MTBE in the areas of lower RVP and higher RON. According to industrial reports, MTBE is the fastest growing chemical (1992 US capacity 135,350 BPD, with expected growth of 34%/year to 1997). Also, recent renewed interest as an octane-enhancer and as a source of oxygen has spurred a growing interest in nonrefinery synthesis routes to ETBE. TAME, with its lower RVP and higher RON has proven useful as a gasoline blending agent and octane enhancer and may also be produced directly from DME. DME, therefore, serves as a valuable feedstock in the conversion of may oxygenates with wide-scale industrial importance. It should be also noted that the interest in the utilization of DME as process feedstock is based on the favorable process economics of EPRI/UA`s liquid phase DME process.

Tartamella, T.L.; Sardesai, A.; Lee, S. [Univ. of Akron, OH (United States); Kulik, C.J. [Electric Power Research Inst., Palo Alto, CA (United States)

1994-12-31

107

Process feasibility of DME to olefin conversion  

SciTech Connect

The production of hydrocarbons via a synthetic route has been extensively studied by Mobil through its methanol based Methanol-to-Gasoline (MTG) process. An alternative approach using dimethyl ether (DME) has been developed by the University of Akron -- UA/EPRI DME-to-Hydrocarbons Process. The process feasibility of the production of hydrocarbons from DME has been illustrated in a bench scale, fluidized bed reactor using ZSM-5 type catalyst. In an effort to satisfy the growing demand for olefins as an intermediate chemical feedstocks a mechanistic/kinetic study was developed. The synthesis of olefins has been studied in packed bed micro-reactor using ZSM-5 catalyst. Experimental work has given details of reaction kinetics and mechanism in the conversion of DME to olefins. DME concentration weight hourly space velocity (WHSV), as well as reactor temperature and pressure were investigated in the study. This work was used as a precursor to the production of olefins/hydrocarbons from DME in a fluidized bed reactor. Product gas analysis was performed using an external GC standard method.

Tartamella, T.L.; Fullerton, K.L.; Lee, S. [Univ. of Akron, OH (United States); Kulik, C.J. [Electric Power Research Inst., Palo Alto, CA (United States)

1994-12-31

108

Competition of C(sp(2))-X···O Halogen Bonding and Lone Pair···? Interactions: Cryospectroscopic Study of the Complexes of C2F3X (X = F, Cl, Br, and I) and Dimethyl Ether.  

PubMed

Inspection of the electrostatic potential of C2F3X (X = F, Cl, Br, and I) revealed a second electropositive region in the immediate vicinity of the C?C double bond apart from the ? hole of chlorine, bromine, and iodine, leading to C(sp(2))-X···Y halogen bonding, through which complexes stabilized by so-called lone pair···? interactions can be formed. Consequently, the experimental studies for the complexes of dimethyl ether with C2F3X (X = F, Cl, Br, and I) not only allowed one to experimentally characterize and rationalize the effects of hybridization on halogen bonding but, for the first time, also allowed the competition of C-X···Y halogen bonding and lone pair···? interactions to be studied at thermodynamic equilibrium. Analysis of the infrared and Raman spectra reveals that in the cryosolutions of dimethyl ether and C2F3I, solely the halogen-bonded complex is present, whereas C2F3Br and C2F3Cl give rise to a lone pair···? bonded complex as well as a halogen-bonded complex. Mixtures of dimethyl ether with C2F4 solely yield a lone pair···? bonded complex. The experimentally derived complexation enthalpies for the halogen bonded complexes are found to be -14.2(5) kJ mol(-1) for C2F3I·DME and -9.3(5) kJ mol(-1) for C2F3Br·DME. For the complexes of C2F3Cl with dimethyl ether, no experimental complexation enthalpy could be obtained, whereas the C2F4·DME complex has a complexation enthalpy of -5.5(3) kJ mol(-1). The observed trends have been rationalized with the aid of an interaction energy decomposition analysis (EDA) coupled to a Natural Orbital for Chemical Valence (NOCV) analysis and also using the noncovalent interaction index method. PMID:25390877

Geboes, Yannick; Nagels, Nick; Pinter, Balazs; De Proft, Frank; Herrebout, Wouter A

2015-03-19

109

Evaluation of Glove Material Resistance to Ethylene Glycol Dimethyl Ether Permeation  

Microsoft Academic Search

Some glycol ethers have been reported to cause adverse reproductive effects in exposed male and female workers, and skin absorption has been determined to be an important route of entry of this class of chemicals. Because ethylene glycol dimethyl ether (EGDME) is a possible component of lithium-based primary battery electrolyte systems, a study was undertaken to determine the resistance of

R. MENKE; C. F. CHELTON

1988-01-01

110

Steam reforming of dimethyl ether for generating hydrogen-rich fuel-cell feeds  

NASA Astrophysics Data System (ADS)

This research evaluates both the thermodynamic and experimental aspects of dimethyl ether as a hydrogen carrier for fuel-cell feeds. The thermodynamics of generating hydrogen from dimethyl ether via partial oxidation, by steam reforming, or by the combined processes of partial oxidation and steam reforming were investigated as functions of temperature (100°C--600°C), steam-to-carbon ratio (0.00--4.00), oxygen-to-carbon ratio (0.00--2.80), pressure (1--5 atm) and product species. Thermodynamically, the resulting optimal processing conditions for dimethyl ether steam reforming occurred at a steam-to-carbon ratio of 1.50, a pressure of 1 atm and a temperature of 200°C, resulting in a hydrogen production efficiency of 97%. These results also showed that dimethyl ether hydrolysis to methanol, the first step in the steam reforming process to form hydrogen, was equilibrium limited. Modeling the start-up energies and efficiencies of an automotive scale on-board fuel processor was also carried out as a function of fuel source (methane, methanol, ethanol, dimethyl ether and gasoline). Results demonstrated that a fuel processor utilizing dimethyl ether yielded the highest overall efficiency. Dimethyl ether hydrolysis to form methanol (the desired intermediate) was studied experimentally over a series of as-received catalysts of varying acidity (zeolites Y and ZSM-5, ZrO2, gamma-Al2O 3, SiO2 and BASF K3-110) and also a series of in-house prepared composite catalysts containing copper and zinc, using a packed-bed reactor. All the acid catalysts, with the exception of ZrO2, attained the previously calculated equilibrium-limited conversions to methanol in the temperature range of interest (125°C--400°C). Several homogeneous physical mixtures containing both an as-received acid catalyst and BASF K3-110 (a methanol-to-hydrogen catalyst) were used to examine the process of converting dimethyl ether to hydrogen, (i.e., dimethyl ether steam reforming). Hydrogen production efficiencies exceeding 95% and hydrogen production rates exceeding 85 mmoles gcat -1 h-1 were observed. In-house prepared composite catalysts, consisting of copper and zinc loaded onto a solid-acid substrate via incipient wetness or co-ion exchange, were also evaluated for dimethyl ether steam reforming activity, but were generally found less active than the physical mixture catalysts. Variations in catalyst activity and selectivity are discussed in terms of zeolite characteristics. In situ DRIFTS experiments were also performed.

Semelsberger, Troy Allen

111

Development of alternative fuels from coal derived syngas. Topical report: Task 2.2, Demonstration of a one-step slurry-phase process for the production of dimethyl ether/methanol mixtures at the LaPorte Alternative Fuels Development Unit  

SciTech Connect

This report documents engineering, modification, and operations efforts of demonstration of dimethyl-ether/methanol coproduction in a slurry-phase reactor, carried out in a 2-ft diameter bubble column reactor. Equipment modifications made it possible to remove the product DME and by-product CO{sub 2} from the reactor effluent. Coproduction of dimethyl-ether (DME) and methanol (MeOH) was accomplished in the slurry reactor by physically mixing two different catalysts. The catalyst used to produce MeOH from syngas was manufactured by BASF (type S3-86); the catalyst used to convert MeOH to DME was Catapal {gamma}-alumina. Ratio of MeOH to DME catalysts determined the selectivity towards DME. The demonstration sought to study effect of cocatalyst ratio on product selectivity. Three different proportions of DME catalyst were examined: 0, 6.6, and 19.3 wt % alumina. At each catalyst proportion, the plant was operated at two different gas space velocities. Some process variables were maintained at fixed conditions; most important variables included: reactor temperature (482F), reactor pressure (750 psig), and reactor feed gas composition (35% H{sub 2}, 51% CO,13% CO{sub 2} 1% other, nominal-molar basis).

Not Available

1993-06-01

112

Chemical recycling of carbon dioxide to methanol and dimethyl ether: from greenhouse gas to renewable, environmentally carbon neutral fuels and synthetic hydrocarbons.  

PubMed

Nature's photosynthesis uses the sun's energy with chlorophyll in plants as a catalyst to recycle carbon dioxide and water into new plant life. Only given sufficient geological time can new fossil fuels be formed naturally. In contrast, chemical recycling of carbon dioxide from natural and industrial sources as well as varied human activities or even from the air itself to methanol or dimethyl ether (DME) and their varied products can be achieved via its capture and subsequent reductive hydrogenative conversion. The present Perspective reviews this new approach and our research in the field over the last 15 years. Carbon recycling represents a significant aspect of our proposed Methanol Economy. Any available energy source (alternative energies such as solar, wind, geothermal, and atomic energy) can be used for the production of needed hydrogen and chemical conversion of CO(2). Improved new methods for the efficient reductive conversion of CO(2) to methanol and/or DME that we have developed include bireforming with methane and ways of catalytic or electrochemical conversions. Liquid methanol is preferable to highly volatile and potentially explosive hydrogen for energy storage and transportation. Together with the derived DME, they are excellent transportation fuels for internal combustion engines (ICE) and fuel cells as well as convenient starting materials for synthetic hydrocarbons and their varied products. Carbon dioxide thus can be chemically transformed from a detrimental greenhouse gas causing global warming into a valuable, renewable and inexhaustible carbon source of the future allowing environmentally neutral use of carbon fuels and derived hydrocarbon products. PMID:19063591

Olah, George A; Goeppert, Alain; Prakash, G K Surya

2009-01-16

113

Performance evaluation of chemically recuperated gas turbine (CRGT) power plants fuelled by di-methyl-ether (DME)  

Microsoft Academic Search

This paper reports a performance analysis on CRGT power plants fuelled by DME, which is a potentially attractive fuel for gas turbines. The study also includes a performance comparison of simple cycle gas turbines fuelled by natural gas, DME and methanol. The study shows that, owing to the exhaust heat recovery carried out through DME pre-heating and vaporization before combustion,

Daniele Cocco; Vittorio Tola; Giorgio Cau

2006-01-01

114

Industrial gas turbine combustion performance test of DME to use as an alternative fuel for power generation  

Microsoft Academic Search

DME (dimethyl ether, CH3OCH3) is both a good alternative fuel for transportation and power generation and an LPG substitute owing to its cleanliness, multi-source productivity and the ease with which it is transported. This study was conducted to verify whether DME is a good fuel for gas turbines and to identify potential problems in fuelling a commercial gas turbine with

Min Chul Lee; Seok Bin Seo; Jae Hwa Chung; Yong Jin Joo; Dal Hong Ahn

2009-01-01

115

A novel catalyst for DME synthesis from CO hydrogenation  

Microsoft Academic Search

The effect of manganese on the dispersion, reduction behavior and active states of surfaces of ?-Al2O3 supported copper catalysts was investigated by X-ray powder diffraction (XRD), temperature-programmed reduction (TPR) and XPS technologies. The relationship between the area of metallic copper and the activity of dimethyl ether (DME) synthesis from CO\\/H2 was also investigated. The catalytic activity over Cu-MnOx\\/?-Al2O3 catalyst for

Gong-Xin Qi; Xiao-Ming Zheng; Jin-Hua Fei; Zhao-Yin Hou

2001-01-01

116

Search for photoinsecticides: effect of hematoporphyrin dimethyl ether on leafmining pest Liriomyza bryoniae (Diptera: Agromyzidae)  

Microsoft Academic Search

Photoactive compounds might be used as effective pesticide agents, with almost no impact on the environment, being nontoxic and not mutagenic. The point is, that nontoxic photoactive compound accumulates within the insect body and, following exposition to visible light, induces lethal photochemical reactions and death of target pest. The aim of this study was to determine, whether hematoporphyrin dimethyl ether

V. B?da; S. Rad; N. Kuril?ik

2006-01-01

117

A study of natural gas\\/DME combustion in HCCI engines using CFD with detailed chemical kinetics  

Microsoft Academic Search

Combustion characteristics of natural gas and dimethyl ether (DME) mixture in a homogeneous charge compression ignition (HCCI) engine were studied numerically. Detailed chemical kinetics with 83 species and 360 reactions was used with an engine CFD code to simulate the combustion process. Operating conditions with different fuel compositions were simulated. Combustion, nitrogen oxides emissions and effects of fuel compositions on

Song-Charng Kong

2007-01-01

118

VizieR Online Data Catalog: Dimethyl ether-13C lab spectra up to 1.5THz (Koerber+, 2013)  

NASA Astrophysics Data System (ADS)

The interpretation of astronomical observations depends on the knowledge of accurate rest frequencies and intensities. The objective of this work is to provide spectroscopic data for the two 13C-isotopologues of dimethyl ether in the vibrational ground state. High-resolution rotational-torsional spectra of dimethyl ether-13C1 and dimethyl ether-13C2 have been measured in the laboratory covering frequencies up to 1.5THz. The analysis is based on an effective rotational Hamiltonian for molecules with two large amplitude motions. (2 data files).

Koerber, M.; Bisschop, S. E.; Endres, C. P.; Kleshcheva, M.; Pohl, R. W. H.; Klein, A.; Lewen, F.; Schlemmer, S.

2013-09-01

119

Metal oxide catalysts for DME steam reforming: Ga 2 O 3 andGa 2 O 3 –Al 2 O 3 catalysts  

Microsoft Academic Search

The steam reforming of dimethyl ether (DME) was performed on Ga2O3–Al2O3 mixed oxides prepared by sol–gel method. Ga2O3 significantly affects the catalytic performance with respect to the DME conversion and H2 yield. The catalytic activity increases with the Ga concentration in Ga2O3–Al2O3 mixed oxides. It is very interesting that without the aid of an additional transition metal component, Ga2O3 and

Thomas Mathew; Yusuke Yamada; Atsushi Ueda; Hiroshi Shioyama; Tetsuhiko Kobayashi

2005-01-01

120

Design of a Pulse Injector for DME Propellant  

NASA Astrophysics Data System (ADS)

Recently, a pulsed plasma thruster (PPT), which has advantages such as smallness, lightweight and low power consumption, has attracted attention again for the application to small satellites. Liquid propellant like water or alcohol provides higher specific impulse in comparison with conventional Teflon propellant. Nevertheless, water and alcohol propellants have problems: higher freezing point or contamination to satellites by the exhaust gas. In this study, we propose to apply DME (Di-methyl ether) to the PPT's propellant. DME can be stored as liquid, and requires no pressurant because DME has a vapor pressure of 0.6 MPa at 298 K. DME would also be potentially usable as heat transfer media, coolant, working fluid of heat pipe etc. We have designed and tested a prototyped pulse injector supplying liquid DME to discharge channels of the PPTs. Experimental results showed that the pulse injector successfully injected liquefied DME of 1.16 mg/shot, which is equivalent to the mass shot of a high power class PPT. The shape of injected liquid was dependent on the duration of the gating-pulse applied to the injector; a group of droplets were provided with a 20 ms gating-pulse duration, and a single stream with 25 ms or longer gating-pulse duration.

Fukunaga, Masato; Kakami, Akira; Tachibana, Takeshi

121

Evaluation of glove material resistance to ethylene glycol dimethyl ether permeation.  

PubMed

Some glycol ethers have been reported to cause adverse reproductive effects in exposed male and female workers, and skin absorption has been determined to be an important route of entry of this class of chemicals. Because ethylene glycol dimethyl ether (EGDME) is a possible component of lithium-based primary battery electrolyte systems, a study was undertaken to determine the resistance of various commercially available gloves to permeation of this liquid. The gloves were tested by the ASTM Method F-739-81, and butyl rubber was found to be the most effective barrier to permeation. Further studies determined that the butyl gloves could be reused if they were reconditioned overnight in a vacuum oven at 50 degrees C. When a mixture of ethylene glycol dimethyl ether (30% v/v) and propylene carbonate (70% v/v) was tested, the results indicated that the propylene carbonate retards the permeation of the glycol ether by a factor of 10. This is believed to be caused by the propylene carbonate coating the surface of the butyl membrane to reduce the sorption of EGDME. PMID:3177216

Menke, R; Chelton, C F

1988-08-01

122

Evaluation of glove material resistance to ethylene glycol dimethyl ether permeation  

SciTech Connect

Some glycol ethers have been reported to cause adverse reproductive effects in exposed male and female workers, and skin absorption has been determined to be an important route of entry of this class of chemicals. Because ethylene glycol dimethyl ether (EGDME) is a possible component of lithium-based primary battery electrolyte systems, a study was undertaken to determine the resistance of various commercially available gloves to permeation of this liquid. The gloves were tested by the ASTM Method F-739-81, and butyl rubber was found to be the most effective barrier to permeation. Further studies determined that the butyl gloves could be reused if they were reconditioned overnight in a vacuum oven at 50 degrees C. When a mixture of ethylene glycol dimethyl ether (30% v/v) and propylene carbonate (70% v/v) was tested, the results indicated that the propylene carbonate retards the permeation of the glycol ether by a factor of 10. This is believed to be caused by the propylene carbonate coating the surface of the butyl membrane to reduce the sorption of EGDME.

Menke, R.; Chelton, C.F.

1988-08-01

123

IMPACT OF DME-DIESEL FUEL BLEND PROPERTIES ON DIESEL FUEL INJECTION SYSTEMS  

SciTech Connect

The objectives of this research program are to develop information on lubricity and viscosity improvers and their impact on the wear mechanisms in fuel injectors operating on blends of dimethyl ether (DME) and diesel fuel. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In the shuttle bus project, we have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. Our strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. In this project, we have sought to develop methods for extending the permissible DME content in the DME-diesel blends without experiencing rapid injector failure due to wear. To date, our activities have covered three areas: examination of the impact of lubricity additives on the viscosity of DME, development of a high-pressure lubricity test apparatus for studies of lubricity and viscosity improvers and development of an injector durability stand for evaluation of wear rates in fuel injectors. This report provides summaries of the progress toward evaluation of the viscosity impacts of lubricity additives, completion of both experimental systems and a summary of the plan for completion of the project objectives.

Elana M. Chapman; Andre Boehman; Kimberly Wain; Wallis Lloyd; Joseph M. Perez; Donald Stiver; Joseph Conway

2003-06-01

124

Reaction of dimethyl ether with hydroxyl radicals: kinetic isotope effect and prereactive complex formation.  

PubMed

The kinetic isotope effect of the reactions OH + CH3OCH3 (DME) and OH + CD3OCD3 (DME-d6) was experimentally and theoretically studied. Experiments were carried out in a slow-flow reactor at pressures between 5 and 21 bar (helium as bath gas) with production of OH by laser flash photolysis of HNO3 and time-resolved detection of OH by laser-induced fluorescence. The temperature dependences of the rate coefficients obtained can be described by the following modified Arrhenius expressions: k(OH+DME) = (4.5 ± 1.3) × 10(-16) (T/K)(1.48) exp(66.6 K/T) cm(3) s(-1) (T = 292-650 K, P = 5.9-20.9 bar) and k(OH+DME-d6) = (7.3 ± 2.2) × 10(-23) (T/K)(3.57) exp(759.8 K/T) cm(3) s(-1) (T = 387-554 K, P = 13.0-20.4 bar). A pressure dependence of the rate coefficients was not observed. The agreement of our experimental results for k(OH+DME) with values from other authors is very good, and from a fit to all available literature data, we derived the following modified Arrhenius expression, which reproduces the values obtained in the temperature range T = 230-1500 K at pressures between 30 mbar and 21 bar to better than within ±20%: k(OH+DME) = 8.45 × 10(-18) (T/K)(2.07) exp(262.2 K/T) cm(3) s(-1). For k(OH+DME-d6), to the best of our knowledge, this is the first experimental study. For the analysis of the reaction pathway and the kinetic isotope effect, potential energy diagrams were calculated by using three different quantum chemical methods: (I) CCSD(T)/cc-pV(T,Q)Z//MP2/6-311G(d,p), (II) CCSD(T)/cc-pV(T,Q)Z//CCSD/cc-pVDZ, and (III) CBS-QB3. In all three cases, the reaction is predicted to proceed via a prereaction OH-ether complex with subsequent intramolecular hydrogen abstraction and dissociation to give the methoxymethyl radical and water. Overall rate coefficients were calculated by assuming a thermal equilibrium between the reactants and the prereaction complex and by calculating the rate coefficients of the hydrogen abstraction step from canonical transition state theory. The results based on the molecular data from methods (I) and (II) showed a satisfactory agreement with the experimental values, which indicates that the pre-equilibrium assumption is reasonable under our conditions. In the case of method (III), the isotope effect was significantly underpredicted. The reason for this discrepancy was identified in a fundamentally differing reaction coordinate. Obviously, the B3LYP functional applied in method (III) for geometry and frequency calculations is inadequate to describe such systems, which is in line with earlier findings of other authors. PMID:23914942

Bänsch, Cornelie; Kiecherer, Johannes; Szöri, Milan; Olzmann, Matthias

2013-09-01

125

Comparison of the solubility of PVF and PVDF in supercritical CH{sub 2}F{sub 2} and CO{sub 2} and in CO{sub 2} with acetone, dimethyl ether, and ethanol  

SciTech Connect

Cloud-point data are reported at temperatures to 245 C and pressures to 2700 bar for poly(vinyl fluoride) (PVF) and poly(vinylidene fluoride) (PVDF) in CO{sub 2}, CH{sub 2}F{sub 2}, dimethyl ether (DME), acetone, and ethanol and in mixtures of CO{sub 2} with acetone, DME, and ethanol. PVF does not dissolve in CO{sub 2} even at 245 C and 2700 bar, but, PVF does dissolve in CH{sub 2}F{sub 2} at 180 C and pressures in excess of 1500 bar. To dissolve PVF in DME, pressures in excess of 550 bar and temperatures in excess of 130 C are needed although it only takes {approximately}100 bar to maintain a single phase to temperatures of {approximately}220 C with ethanol and acetone. Compared to the conditions needed to dissolve PVF, it takes hundreds of bar less pressure to dissolve PVDF in CO{sub 2}, CH{sub 2}F{sub 2}, and DME and {approximately}60 bar less pressure to dissolve it in acetone, but it does take {approximately}60 bar more pressure to dissolve it in ethanol. With CO{sub 2}, ethanol is a better cosolvent than acetone for both fluoropolymers at high temperatures and at low ethanol concentrations. However, when the temperature is decreased or the ethanol concentration is increased, it acts as an antisolvent probably due to ethanol self-association. Compared to ethanol and acetone, DME is not as good a cosolvent more than likely as a result of its lower density and smaller dipole moment. For all three cosolvents, their impact on the reduction of the cloud-point pressure diminishes with increasing cosolvent concentration. It is also evident that CO{sub 2} is an effective antisolvent since small amounts of it added to the polymer-cosolvent mixtures greatly increase the pressures needed to obtain a single phase.

Lora, M. [Univ. di Padova (Italy). Ist. di Impianti Chimici] [Univ. di Padova (Italy). Ist. di Impianti Chimici; Lim, J.S. [Korean Inst. of Science and Technology, Seoul (Korea, Republic of)] [Korean Inst. of Science and Technology, Seoul (Korea, Republic of); McHugh, M.A. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemical Engineering] [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemical Engineering

1999-04-08

126

Low-temperature synthesis of DME from CO 2\\/H 2 over Pd-modified CuO–ZnO–Al 2O 3–ZrO 2\\/HZSM-5 catalysts  

Microsoft Academic Search

Three series of Pd-modified CuO–ZnO–Al2O3–ZrO2\\/HZSM-5 catalysts were prepared and characterized by BET, XRD and TPR analysis. The catalytic system was evaluated in the development of direct synthesis of dimethyl ether (DME) from carbon dioxide hydrogenation at low temperature (T=200 °C, P=3.0 MPa). The results indicated that the addition of palladium markedly enhanced the DME synthesis and retarded the CO formation.

Kunpeng Sun; Weiwei Lu; Min Wang; Xianlun Xu

2004-01-01

127

IMPACT OF DME-DIESEL FUEL BLEND PROPERTIES ON DIESEL FUEL INJECTION SYSTEMS  

SciTech Connect

The objectives of this research program are to develop information on lubricity and viscosity improvers and their impact on the wear mechanisms in fuel injectors operating on blends of dimethyl ether (DME) and diesel fuel. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In the shuttle bus project, we have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. Our strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. In this project, we have sought to develop methods for extending the permissible DME content in the DME-diesel blends without experiencing rapid injector failure due to wear. Our activities have covered three areas: examination of the impact of lubricity additives on the viscosity of DME, development of a high-pressure lubricity test apparatus for studies of lubricity and viscosity improvers and development of an injector durability stand for evaluation of wear rates in fuel injectors. The first two of these areas have resulted in valuable information about the limitations of lubricity and viscosity additives that are presently available in terms of their impact on the viscosity of DME and on wear rates on injector hardware. The third area, that of development of an injector durability test stand, has not resulted in a functioning experiment. Some information is provided in this report to identify the remaining tasks that need to be performed to make the injector stand operational. The key observations from the work are that when blended at 25 wt.% in either diesel fuel or Biodiesel fuel, DME requires more than 5 wt.% additive of all viscosity and lubricity additives tested here to even approach the lower limit of the ASTM diesel fuel viscosity requirement. To treat neat DME sufficiently to make DME comply with the ASTM diesel fuel viscosity requirement would require a viscosity additive with 10{sup 45} cSt viscosity, which is not possible with current additive technologies.

Elana M. Chapman; Andre Boehman; Kimberly Wain; Wallis Lloyd; Joseph M. Perez; Donald Stiver; Joseph Conway

2004-04-01

128

Reinvestigation of microwave spectrum of dimethyl ether and rs structures of analogous molecules  

NASA Astrophysics Data System (ADS)

Microwave spectra of dimethyl ether and its sixteen isotopic species have been measured. For species with singlet spectra, a least-squares analysis of observed transition frequencies gave rotational and five quartic centrifugal distortion constants. For species with multiplet spectra due to the methyl internal rotation, a least-squares analysis of observed multiplet frequencies gave not only unperturbed rotational and five quartic centrifugal distortion constants but also the quantities related to the methyl internal rotation. The rs structures from (CH 3) 2O, CH 3OCD 3, and (CD 3) 2O species as the parent species, respectively, were compared with one another. The proposed rs structure has been established from all the species measured and was compared with the rs-like structure obtained by a diagnostic least-squares method and with the reported structure. The rs structure of the present molecule was compared with the reported structures of dimethyl sulfide and dimethyl silane in relation to the tilt phenomenon. The rs structure of dimethyl sulfide was revised based on the present comparison.

Niide, Yuzuru; Hayashi, Michiro

2003-07-01

129

CFD MODELING OF DIESEL OIL AND DME PERFORMANCE IN A TWO-STROKE FREE PISTON ENGINE  

Microsoft Academic Search

This paper presents the CFD KIVA3V, rel. 2 model and numerical results of combustion process simulations in a two-stroke, uniflow scavenging dual free piston engine, FPE, designed for electricity generation. Two fuels, diesel oil and dimethyl ether (DME), were studied in order to achieve HCCI-like combustion. Limited size reaction mechanisms were constructed and used in the modeling. The diesel oil

V. I. GOLOVITCHEV; M. BERGMAN; L. MONTORSI

2007-01-01

130

Energy-saving drying technology for porous media using liquefied DME gas  

Microsoft Academic Search

Process design and energy requirement for a practical plant are investigated for an energy-saving drying (dewatering) process\\u000a invented by the authors in 2002 for high-moisture porous materials. The basic concept of the process involves the extraction\\u000a of water from a high-moisture porous material by bringing it in physical contact with liquefied dimethyl ether (DME) at room\\u000a temperature. Water content of

Hideki Kanda; Hisao Makino; Minoru Miyahara

2008-01-01

131

Role of dehydration catalyst acid properties on one-step DME synthesis over physical mixtures  

Microsoft Academic Search

The direct synthesis of dimethyl ether (DME) was studied in a continuous high-pressure unit composed basically of a Berty reactor and on-line gas chromatograph. A commercial methanol synthesis catalyst and some solid-acid catalysts (alumina, HZSM-5, tungsten–zirconia and sulfated-zirconia) were used as physical mixtures. The dehydration catalysts were characterised by pyridine adsorption followed by IR spectroscopy and tested in the methanol

F. S. Ramos; A. M. Duarte de Farias; L. E. P. Borges; J. L. Monteiro; M. A. Fraga; E. F. Sousa-Aguiar; L. G. Appel

2005-01-01

132

Liquid densities, kinematic viscosities, and heat capacities of some ethylene glycol dimethyl ethers at temperatures from 283.15 to 423.15 K  

SciTech Connect

Liquid densities and heat capacities at 1 MPa, and kinematic viscosities at atmospheric pressure of monoethylene glycol dimethyl ether (MEGDME), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TrEGDME), tetrathylene glycol dimethyl ether (TEGDME), pentaethylene glycol dimethyl ether (PeEGDME), and polyethylene glycol 250 dimethyl ether (PEGDMe 250) were measured in the temperature range from 283.15 to 423.15 K. For each substance, experimental data were correlated with temperature using empirical polynomial equations. The experimental data were also used to evaluate the predictive capability of some estimation methods of liquid densities and heat capacities for the studied ethylene glycol dimethyl ethers. The densities estimated by the Yen-Woods equation agree with the experimental values with a root-mean-square relative deviation (RMSD) of 3.21% for all ethylene glycol dimethyl ethers. The best estimated results of liquid heat capacities were obtained from the Rowlinson equation based on the corresponding-states principle, with a RMSD of 1.12%. The group-contribution methods give the worst results, especially at high temperatures.

Conesa, A.; Coronas, A. [Univ. Rovira i Virgili, Tarragona (Spain). Dept. of Mechanical Engineering] [Univ. Rovira i Virgili, Tarragona (Spain). Dept. of Mechanical Engineering; Shen, S. [Nanjing Univ. of Chemical Technology (China)] [Nanjing Univ. of Chemical Technology (China)

1998-09-01

133

Commercial-scale demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) Process. Peroxide formation of dimethyl ether in methanol mixtures  

SciTech Connect

Organic peroxides could form when dimethyl ether in methanol is stored for three to six months at a time. The objective of this work was to determine the level of peroxide formation from dimethyl ether in reagent grade methanol and raw methanol at room temperature under 3 atmospheres (45 psig) of air. Raw methanol is methanol made from syngas by the LPMEOH Process without distillation. Aliphatic ethers tend to react slowly with oxygen from the air to form unstable peroxides. However, there are no reports on peroxide formation from dimethyl ether. After 172 days of testing, dimethyl ether in either reagent methanol or raw methanol at room temperature and under 60--70 psig pressure of air does not form detectable peroxides. Lack of detectable peroxides suggests that dimethyl ether or dimethyl ether and methanol may be stored at ambient conditions. Since the compositions of {approximately} 1.3 mol% or {approximately} 4.5 mol% dimethyl ether in methanol do not form peroxides, these compositions can be considered for diesel fuel or an atmospheric turbine fuel, respectively.

Waller, F.J.

1997-11-01

134

Simultaneous Quantification of OH and HO_2 in Dimethyl Ether Oxidation Using Faraday Rotation Spectroscopy  

NASA Astrophysics Data System (ADS)

OH and HO_2 are key radical species that control the autoignition and flame chemistry of fuels. Quantification of these radicals in the low-temperature oxidation of fuels is challenging due to their low concentrations. Strong spectral interference from more abundant non-radical species can further complicate accurate quantification of OH and HO_2. Faraday Rotation Spectroscopy (FRS), a laser-based diagnostic that exploits magneto-optical properties of paramagnetic radical species, can overcome these technical challenges to provide sensitive and selective in situ quantification of radicals. Previously we have been able to illustrate the strengths of FRS in quantification of HO_2 radicals in the low-temperature oxidation of dimethyl ether. Recently we have constructed a dual-wavelength FRS system capable of simultaneous in situ measurement of OH and HO_2. A DFB diode laser operating at 2.8 ?m is used to target the Q(1.5e) and Q(1.5f) transitions in the fundamental vibrational band of the 2?3/2 ground electronic state of OH. An EC-QCL operating at 7.1 ?m is used to target a Q-branch spectral feature in the ?b{2} vibrational band of HO_2. Concentrations of the target species are extracted from the measured spectra through fitting of an FRS spectral model. Based on preliminary retrievals, 3? detection limits of <1 ppmv for OH and HO_2 have been estimated from the non-linear least-squares fitting results. In this talk I will discuss the application of dual-wavelength FRS for sensitive measurement of OH and HO_2 radicals generated by oxidation of dimethyl ether in a flow reactor over a 520 K - 1050 K temperature range. B. Brumfield et al., J. Phys. Chem. Lett., 4, 872 (2013) B. Brumfield et al., ``Dual Modulation Faraday Rotation Spectroscopy of HO_2 in a Flow Reactor'' Accepted in Optics Letters (2014) N. Kurimoto et al., ``Quantitative Measurements of HO_2 / H_2O_2 and Intermediate Species in Low and Intermediate Temperature Oxidation of Dimethyl Ether'', Submitted to The 35th International Symposium on Combustion.

Brumfield, Brian; Yang, Xueliang; Lefkowitz, Joseph; Ju, Yiguang; Wysocki, Gerard

2014-06-01

135

Study of a self quenching streamer mode in pure gases of DME and isobutane  

E-print Network

A self quenching streamer (SQS), or limited streamer mode has been studied in single wire chambers with cross-sections 12x12 mm and wire diameters 15, 25 and 50 microns. Chambers were filled with either pure dimethyl ether (DME) or isobutane gases and irradiated with Gd-148 alpha and Fe-55 x-ray sources. Clear transitions from a proportional to 100% SQS mode were observed on all three diameter wires with both gases irradiated with alpha particles. Double SQS discharges due to inclined tracks observed in DME gas allowed an estimation of a streamer size along the wire of less than 1 mm. The second SQS discharge appears less than 1 mm from the first within about 500 ns. Charge spectra obtained with DME irradiated with Fe-55 x-rays might also be interpreted as a transition to a SQS mode, although no direct evidence of that was seen in the observed pulse shapes.

Yu. I. Davydov; R. Openshaw

2005-06-22

136

Process for the production of ethylidene diacetate from dimethyl ether using a heterogeneous catalyst  

DOEpatents

This invention relates to a process for producing ethylidene diacetate by the reaction of dimethyl ether, acetic acid, hydrogen and carbon monoxide at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that is stable to hydrogenation and comprises an insoluble polymer having pendant quaternized heteroatoms, some of which heteroatoms are ionically bonded to anionic Group VIII metal complexes, the remainder of the heteroatoms being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for 3 consecutive runs without loss in activity.

Ramprasad, D.; Waller, F.J.

1998-04-28

137

Process for the production of ethylidene diacetate from dimethyl ether using a heterogeneous catalyst  

DOEpatents

This invention relates to a process for producing ethylidene diacetate by the reaction of dimethyl ether, acetic acid, hydrogen and carbon monoxide at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that is stable to hydrogenation and comprises an insoluble polymer having pendant quaternized heteroatoms, some of which heteroatoms are ionically bonded to anionic Group VIII metal complexes, the remainder of the heteroatoms being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for 3 consecutive runs without loss in activity.

Ramprasad, Dorai (Allentown, PA); Waller, Francis Joseph (Allentown, PA)

1998-01-01

138

Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas. Task 2.2: Definition of preferred catalyst system; Task 2.3: Process variable scans on the preferred catalyst system; Task 2.4: Life-test on the preferred catalyst system  

SciTech Connect

As part of the DOE-sponsored contract for the Synthesis of Dimethyl Ether (DME) and Alternative Fuels in the Liquid Phase from Coal- Derived Syngas, the single-step, slurry phase DME synthesis process was developed. The development involved screening of catalyst systems, process variable studies, and catalyst life studies in two 300 ml stirred autoclaves. As a spin-off of the Liquid Phase Methanol (LPMEOH*) process, the new process significantly improves the syngas conversion efficiency of the LPMEOH process. This improvement can be achieved by replacing a portion of methanol catalyst with a dehydration catalyst in the reactor, resulting in the product methanol being converted to DME, thus avoiding the thermodynamic equilibrium constraint of the methanol reaction. Overall, this increases syngas conversion per-pass. The selectivity and productivity of DME and methanol are affected by the catalyst system employed as well as operating conditions. A preferred catalyst system, consisting of a physical mixture of a methanol catalyst and a gamma alumina, was identified. An improvement of about 50% in methanol equivalent productivity was achieved compared to the LPMEOH process. Results from the process variable study indicate that higher pressure and CO{sub 2} removal benefit the process significantly. Limited life studies performed on the preferred catalyst system suggest somewhat higher than expected deactivation rate for the methanol catalyst. Several DME/methanol mixtures were measured for their key properties as transportation fuels. With small amounts of DME added, significant improvements in both flash points and Reid Vapor Pressure (RVP) were observed over the corresponding values of methanol alone.

Bhatt, B.L.

1992-09-01

139

Process Design, Simulation and Integration of Dimethyl Ether (DME) Production from Shale Gas by Direct and Indirect Methods  

E-print Network

sensitivity analysis is also conducted to evaluate the process profitability under variable market conditions. Finally, the both methods are compared in terms of the fixed capital cost, operating cost, return on investment, and CO_(2) and water impact...

Karagoz, Secgin

2014-08-11

140

VizieR Online Data Catalog: Dimethyl ether laboratory spectra up to 2.1THz (Endres+, 2009)  

NASA Astrophysics Data System (ADS)

Dimethyl ether (CH3OCH3) is one of the largest or detected in the interstellar medium. As an asymmetric top molecule with two methyl groups which undergo large amplitude motions and a dipole moment of mub=1.3D it conveys a dense spectrum throughout the terahertz region and contributes to the spectral line confusion in astronomical observations at these frequencies. Rotational spectra of dimethyl ether in its ground vibrational states are presented in this paper, which have been measured in the laboratory and analyzed covering frequencies up to 2.1THz. The analysis is based on an effective Hamiltonian for a symmetric two-top rotor and includes experimental data published so far. Frequency predictions are presented up to 2.5THz for astronomical applications with accuracies better than 1MHz. (1 data file).

Endres, C. P.; Drouin, B. J.; Pearson, J. C.; Muller, H. S. P.; Lewen, F.; Schlemmer, S.; Giesen, T. F.

2009-07-01

141

Efficient synthesis of dimethyl ether over HZSM-5 supported on medium-surface-area beta-SiC foam.  

PubMed

In this study, we aimed to produce a highly selective and stable catalyst for the production of dimethyl ether by methanol dehydration. The activities were compared of different active phases of the employed system, zeolite HZSM-5 or gamma-alumina, supported on silicon carbide as foam, and it was found that the supported zeolite catalysts are more active than and as selective as the alumina-based catalysts. The as-prepared zeolite/SiC composites reveal good stability in long-term tests in the presence or absence of steam. The high stability is attributed to the presence of highly dispersed micrometer-sized zeolite particles, which make the active sites more accessible to the reactants and promote the quick transfer of the desired product, dimethyl ether, out of the catalyst bed, minimizing deactivation of the catalyst. PMID:18846596

Ivanova, Svetlana; Vanhaecke, Estelle; Louis, Benoit; Libs, Suzanne; Ledoux, Marc-Jacques; Rigolet, Sévérine; Marichal, Claire; Pham, Charlotte; Luck, Francis; Pham-Huu, Cuong

2008-01-01

142

Laboratory rotational spectra of the dimethyl ether 13C-isotopologues up to 1.5 THz  

NASA Astrophysics Data System (ADS)

Context. Dimethyl ether is found in high abundance in the interstellar medium. Owing to its strong and dense spectrum throughout the entire microwave and terahertz regime, it contributes to the spectral confusion in astronomical line surveys. The great sensitivity of new observatories like ALMA enhances the need for reliable spectroscopic data, especially for isotopic species of abundant molecules. In addition, the study of the interstellar 12C/13C isotopic ratio can be used as a tracer of the formation process of a molecular species, and thus it gives insight into the chemical evolution of the observed region. Aims: The interpretation of astronomical observations depends on the knowledge of accurate rest frequencies and intensities. The objective of this work is to provide spectroscopic data for the two 13C-isotopologues of dimethyl ether in the vibrational ground state. Methods: High-resolution rotational-torsional spectra of 12CH3O13CH3 and (13CH3)2O have been measured in the laboratory covering frequencies up to 1.5 THz. The analysis is based on an effective rotational Hamiltonian for molecules with two large-amplitude motions. Results: Predictions of the complete ground state rotational spectrum of dimethyl ether-13C1 and -13C2 up to 2 THz are presented with accuracies better than 1 MHz. Based on the laboratory work, transitions of 12CH3O13CH3 dimethyl ether have been detected for the first time in a large submillimeter line survey of the high-mass star forming region G327.3-0.6 performed with the APEX telescope. Full Tables 5 and 6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A112

Koerber, M.; Bisschop, S. E.; Endres, C. P.; Kleshcheva, M.; Pohl, R. W. H.; Klein, A.; Lewen, F.; Schlemmer, S.

2013-10-01

143

Multiphase fluidization in large-scale slurry jet loop bubble columns for methanol and or dimethyl ether production  

Microsoft Academic Search

A solution methodology is proposed for the process development and process engineering of a continuously operated jet loop bubble column including integrated external or internal steam generation for, e.g., a high-efficiency large-scale medium pressure methanol and or dimethyl ether production, or other gas to liquid Fischer–Tropsch applications.A jet loop bubble column is defined in the present process development to study

A. Bakopoulos

2006-01-01

144

Development of an Optical Gas Leak Sensor for Detecting Ethylene, Dimethyl Ether and Methane  

PubMed Central

In this paper, we present an approach to develop an optical gas leak sensor that can be used to measure ethylene, dimethyl ether, and methane. The sensor is designed based on the principles of IR absorption spectrum detection, and comprises two crossed elliptical surfaces with a folded reflection-type optical path. We first analyze the optical path and the use of this structure to design a miniature gas sensor. The proposed sensor includes two detectors (one to acquire the reference signal and the other for the response signal), the light source, and the filter, all of which are integrated in a miniature gold-plated chamber. We also designed a signal detection device to extract the sensor signal and a microprocessor to calculate and control the entire process. The produced sensor prototype had an accuracy of ±0.05%. Experiments which simulate the transportation of hazardous chemicals demonstrated that the developed sensor exhibited a good dynamic response and adequately met technical requirements. PMID:23539025

Tan, Qiulin; Pei, Xiangdong; Zhu, Simin; Sun, Dong; Liu, Jun; Xue, Chenyang; Liang, Ting; Zhang, Wendong; Xiong, Jijun

2013-01-01

145

Inhibition of monocyte adhesion and fibrinogen adsorption on glow discharge plasma deposited tetraethylene glycol dimethyl ether.  

PubMed

Monocytes and macrophages play important roles in host responses to implanted biomedical devices. Monocyte and macrophage interactions with biomaterial surfaces are thought to be mediated by adsorbed adhesive proteins such as fibrinogen and fibronectin. Non-fouling surfaces that minimize protein adsorption may therefore minimize monocyte adhesion, activation, and the foreign body response. Radio-frequency glow discharge plasma deposition (RF-GDPD) of tetraethylene glycol dimethyl ether (tetraglyme) was used to produce polyethylene oxide (PEO)-like coatings on a fluorinated ethylene-propylene (FEP) surface. Electron spectroscopy for chemical analysis (ESCA) and static time of flight secondary ion mass spectrometry (ToF-SIMS) were used to characterize the surface chemistry of tetraglyme coating. Fibrinogen adsorption to the tetraglyme surface was measured with 125I-labeled fibrinogen and ToF-SIMS. Adsorption of fibrinogen to plasma deposited tetraglyme was less than 10 ng cm(-2), a 20-fold decrease compared to untreated FEP or tissue culture polystyrene (TCPS). Monocyte adhesion to plasma deposited tetraglyme was significantly lower than adhesion to FEP or TCPS. In addition, when the surfaces were preadsorbed with fibrinogen, fibronectin, or blood plasma, monocyte adhesion to plasma deposited tetraglyme after 2 h or 1 day was much lower than adhesion to FEP. RF-GDPD tetraglyme coating provides a promising approach to make non-fouling biomaterials that can inhibit non-specific material-host interactions and reduce the foreign body response. PMID:11787523

Shen, M; Pan, Y V; Wagner, M S; Hauch, K D; Castner, D G; Ratner, B D; Horbett, T A

2001-01-01

146

Synthesis of five-membered cyclic ethers by reaction of 1,4-diols with dimethyl carbonate.  

PubMed

The reaction of 1,4-diols with dimethyl carbonate in the presence of a base led to selective and high-yielding syntheses of related five-membered cyclic ethers. This synthetic pathway has the potential for a wide range of applications. Distinctive cyclic ethers and industrially relevant compounds were synthesized in quantitative yield. The reaction mechanism for the cyclization was investigated. Notably, the chirality of the starting material was maintained. DFT calculations indicated that the formation of five-membered cyclic ethers was energetically the most favorable pathway. Typically, the selectivity exhibited by these systems could be rationalized on the basis of hard-soft acid-base theory. Such principles were applicable as far as computed energy barriers were concerned, but in practice cyclization reactions were shown to be entropically driven. PMID:22730182

Aricò, Fabio; Tundo, Pietro; Maranzana, Andrea; Tonachini, Glauco

2012-08-01

147

Methanol catalyst deactivation under dual catalytic mode for DME synthesis  

SciTech Connect

The liquid phase dimethyl ether (DME) synthesis process (LPDME) involves the synthesis of methanol as an intermediate in the production of DMIE. The process involves the use of a dual catalyst system composed of Cu/ZnO/Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3} as the methanol synthesis and DMIE synthesis catalyst respectively. The effect of catalyst deactivation was studied via long term catalyst activity checks to examine the extent of crystal growth and the thermal aging behavior. X-ray powder diffraction, X-ray fluorescence and elemental intensity compositions and the crystallite size distributions of the aged catalysts were examined. Experimental studies have shown that catalyst deactivation is slower when DME synthesis catalyst is coexistent with the methanol synthesis catalyst. This difference in activity is attributed to a decrease in the concentration of the aqueous phase (water and methanol) in the slurry reactor for the production of DME over methanol. Furthermore, the roles of water and methanol in the deactivation of methanol synthesis catalyst have been experimentally determined.

Lee, B.G.; Tartamella, T.L.; Lee, S. [Univ. of Akron, OH (United States)

1994-12-31

148

A Life Cycle Analysis on a Bio-DME production system considering the species of biomass feedstock in Japan and Papua New Guinea  

Microsoft Academic Search

This paper describes the performance and\\/or CO2 intensities of a Bio-DME (Biomass Di-methyl Ether) production system, considering the differences of biomass feedstock. In the past LCA studies on an energy chain model, there is little knowledge on the differences of biomass feedstock and\\/or available condition. Thus, in this paper, we selected Papua New Guinea (PNG) which has good potential for

Masashi Higo; Kiyoshi Dowaki

2010-01-01

149

Combining activated carbon adsorption with heterogeneous photocatalytic oxidation: lack of synergy for biologically treated greywater and tetraethylene glycol dimethyl ether.  

PubMed

The aim of the study was to evaluate whether the addition of activated carbon in the photocatalytic oxidation of biologically pretreated greywater and of a polar aliphatic compound gives synergy, as previously demonstrated with phenol. Photocatalytic oxidation kinetics were recorded with fivefold concentrated biologically pretreated greywater and with aqueous tetraethylene glycol dimethyl ether solutions using a UV lamp and the photocatalyst TiO2 P25 in the presence and the absence of powdered activated carbon. The synergy factor, SF, was quantified as the ratio of photocatalytic oxidation rate constant in the presence of powdered activated carbon to the rate constant without activated carbon. No synergy was observed for the greywater concentrate (SF approximately 1). For the aliphatic compound, tetraethylene glycol dimethyl ether, addition of activated carbon actually had an inhibiting effect on photocatalysis (SF < 1), while synergy was confirmed in reference experiments using aqueous phenol solutions. The absence of synergy for the greywater concentrate can be explained by low adsorbability of its organic constituents by activated carbon. Inhibition of the photocatalytic oxidation of tetraethylene glycol dimethyl ether by addition of powdered activated carbon was attributed to shading of the photocatalyst by the activated carbon particles. It was assumed that synergy in the hybrid process was limited to aromatic organics. Regardless of the lack of synergy in the case of biologically pretreated greywater, the addition of powdered activated carbon is advantageous since, due to additional adsorptive removal of organics, photocatalytic oxidation resulted in a 60% lower organic concentration when activated carbon was present after the same UV irradiation time. PMID:24191472

Gulyas, Holger; Argáez, Angel Santiago Oria; Kong, Fanzhuo; Jorge, Carlos Liriano; Eggers, Susanne; Otterpohl, Ralf

2013-01-01

150

Combining activated carbon adsorption with heterogeneous photocatalytic oxidation: Lack of synergy for biologically treated greywater and tetraethylene glycol dimethyl ether  

PubMed Central

The aim of the study was to evaluate whether the addition of activated carbon in the photocatalytic oxidation of biologically pretreated greywater and of a polar aliphatic compound gives synergy, as previously demonstrated with phenol. Photocatalytic oxidation kinetics were recorded with fivefold concentrated biologically pretreated greywater and with aqueous tetraethylene glycol dimethyl ether solutions using a UV lamp and the photocatalyst TiO2 P25 in the presence and the absence of powdered activated carbon. The synergy factor, SF, was quantified as the ratio of photocatalytic oxidation rate constant in the presence of powdered activated carbon to the rate constant without activated carbon. No synergy was observed for the greywater concentrate (SF ? 1). For the aliphatic compound, tetraethylene glycol dimethyl ether, addition of activated carbon actually had an inhibiting effect on photocatalysis (SF < 1), while synergy was confirmed in reference experiments using aqueous phenol solutions. The absence of synergy for the greywater concentrate can be explained by low adsorbability of its organic constituents by activated carbon. Inhibition of the photocatalytic oxidation of tetraethylene glycol dimethyl ether by addition of powdered activated carbon was attributed to shading of the photocatalyst by the activated carbon particles. It was assumed that synergy in the hybrid process was limited to aromatic organics. Regardless of the lack of synergy in the case of biologically pretreated greywater, the addition of powdered activated carbon is advantageous since, due to additional adsorptive removal of organics, photocatalytic oxidation resulted in a 60% lower organic concentration when activated carbon was present after the same UV irradiation time. PMID:24191472

Gulyas, Holger; Argáez, Ángel Santiago Oria; Kong, Fanzhuo; Jorge, Carlos Liriano; Eggers, Susanne; Otterpohl, Ralf

2013-01-01

151

DOI: 10.1002/cctc.201000383 Catalytic Co-Homologation of Alkanes and Dimethyl Ether  

E-print Network

- lective formation of triptane and isobutane by means of the homologation of DME or methanol (Scheme 140/SiO2).[8] The remarkable selectivity to isobutane and triptane reflects a preference alkanes and isobutane on H-BEA zeo- lites, and for the role of adamantane as a hydride transfer co

Iglesia, Enrique

152

Dimethyl ether: laboratory spectra up to 2.1 THz. Torsion-rotational spectra within the vibrational ground state  

NASA Astrophysics Data System (ADS)

Dimethyl ether (CH_3OCH_3) is one of the largest organic molecules detected in the interstellar medium. As an asymmetric top molecule with two methyl groups which undergo large amplitude motions and a dipole moment of ?=1.3 D, it conveys a dense spectrum throughout the terahertz region and contributes to the spectral line confusion in astronomical observations at these frequencies. In this paper, we present rotational spectra of dimethyl ether in its ground vibrational states, which have been measured in the laboratory and analyzed covering frequencies up to 2.1 THz. The analysis is based on an effective Hamiltonian for a symmetric two-top rotor and includes experimental data published so far. Frequency predictions are presented up to 2.5 THz for astronomical applications with accuracies better than 1 MHz. Table A.1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/504/635

Endres, C. P.; Drouin, B. J.; Pearson, J. C.; Müller, H. S. P.; Lewen, F.; Schlemmer, S.; Giesen, T. F.

2009-09-01

153

Performance Analysis of heat pump cycle using CO2/DME refrigerant mixture  

NASA Astrophysics Data System (ADS)

Performance analyses have been carried out for a heat pump cycle using zeotropic refrigerant mixtures of carbon dioxide (CO2) and dimethyl ether (DME). In order to clarify the characteristics and coefficient of performance (COP) of CO2/DME heat pump cycle, the concentration of mixture was varied over a wide range. The calculation conditions were established as a hot-water supply system and the calculations were conducted by considering the heat transfer between the refrigerant and heat source/sink water. Because the heat transfer between refrigerant and heat source/sink water strongly affects on the cycle behavior, effects of the heat transfer capability parameter were investigated. The heat pump cycle is formed around the critical point for high CO2 concentration mixtures and it is formed under the critical point for low CO2 concentration mixtures. The COP has the maximum at a certain pressure for each mixture and the COPs of the mixture and pure DME are higher than that of pure CO2. Operating pressure decreases with increase of DME concentration. The effects of heat transfer between the refrigerant and heat source/sink water on characteristics of the cycle have also been clarified.

Onaka, Yoji; Miyara, Akio; Tsubaki, Koutaro; Koyama, Shigeru

154

Single-Step Syngas-to-Distillates (S2D) Synthesis via Methanol and Dimethyl Ether Intermediates: Final Report  

SciTech Connect

The objective of the work was to enhance price-competitive, synthesis gas (syngas)-based production of transportation fuels that are directly compatible with the existing vehicle fleet (i.e., vehicles fueled by gasoline, diesel, jet fuel, etc.). To accomplish this, modifications to the traditional methanol-to-gasoline (MTG) process were investigated. In this study, we investigated direct conversion of syngas to distillates using methanol and dimethyl ether intermediates. For this application, a Pd/ZnO/Al2O3 (PdZnAl) catalyst previously developed for methanol steam reforming was evaluated. The PdZnAl catalyst was shown to be far superior to a conventional copper-based methanol catalyst when operated at relatively high temperatures (i.e., >300°C), which is necessary for MTG-type applications. Catalytic performance was evaluated through parametric studies. Process conditions such as temperature, pressure, gas-hour-space velocity, and syngas feed ratio (i.e., hydrogen:carbon monoxide) were investigated. PdZnAl catalyst formulation also was optimized to maximize conversion and selectivity to methanol and dimethyl ether while suppressing methane formation. Thus, a PdZn/Al2O3 catalyst optimized for methanol and dimethyl ether formation was developed through combined catalytic material and process parameter exploration. However, even after compositional optimization, a significant amount of undesirable carbon dioxide was produced (formed via the water-gas-shift reaction), and some degree of methane formation could not be completely avoided. Pd/ZnO/Al2O3 used in combination with ZSM-5 was investigated for direct syngas-to-distillates conversion. High conversion was achieved as thermodynamic constraints are alleviated when methanol and dimethyl are intermediates for hydrocarbon formation. When methanol and/or dimethyl ether are products formed separately, equilibrium restrictions occur. Thermodynamic relaxation also enables the use of lower operating pressures than what would be allowed for methanol synthesis alone. Aromatic-rich hydrocarbon liquid (C5+), containing a significant amount of methylated benzenes, was produced under these conditions. However, selectivity control to liquid hydrocarbons was difficult to achieve. Carbon dioxide and methane formation was problematic. Furthermore, saturation of the olefinic intermediates formed in the zeolite, and necessary for gasoline production, occurred over PdZnAl. Thus, yield to desirable hydrocarbon liquid product was limited. Evaluation of other oxygenate-producing catalysts could possibly lead to future advances. Potential exists with discovery of other types of catalysts that suppress carbon dioxide and light hydrocarbon formation. Comparative techno-economics for a single-step syngas-to-distillates process and a more conventional MTG-type process were investigated. Results suggest operating and capital cost savings could only modestly be achieved, given future improvements to catalyst performance. Sensitivity analysis indicated that increased single-pass yield to hydrocarbon liquid is a primary need for this process to achieve cost competiveness.

Dagle, Robert A.; Lebarbier, Vanessa MC; Lizarazo Adarme, Jair A.; King, David L.; Zhu, Yunhua; Gray, Michel J.; Jones, Susanne B.; Biddy, Mary J.; Hallen, Richard T.; Wang, Yong; White, James F.; Holladay, Johnathan E.; Palo, Daniel R.

2013-11-26

155

Mechanistic details of acid-catalyzed reactions and their role in the selective synthesis of triptane and isobutane from dimethyl ether  

E-print Network

of triptane and isobutane from dimethyl ether Dante A. Simonetti, John H. Ahn, Enrique Iglesia Department alkoxides undergo facile b-scission to form tert-butoxides that desorb preferentially as isobutane via in such chains to the early stages of the homologation chain and account for the prevalence of isobutane among

Iglesia, Enrique

156

Structure and Reactivity of Alkyl Ethers Adsorbed on CeO2(111) Model Catalysts  

SciTech Connect

The effect of surface hydroxyls on the adsorption of ether on ceria was explored. Adsorption of dimethyl ether (DME) and diethyl ether (DEE) on oxidized and reduced CeO{sub 2}(111) films was studied and compared with Ru(0001) using RAIRS and sXPS within a UHV environment. On Ru(0001) the ethers adsorb weakly with the molecular plane close to parallel to the surface plane. On the ceria films, the adsorption of the ethers was stronger than on the metal surface, presumably due to stronger interaction of the ether oxygen lone pair electrons with a cerium cation. This interaction causes the ethers to tilt away from the surface plane compared to the Ru(0001) surface. No pronounced differences were found between oxidized (CeO{sub 2}) and reduced (CeOx) films. The adsorption of the ethers was found to be perturbed by the presence of OH groups on hydroxylated CeOx. In the case of DEE, the geometry of adsorption resembles that found on Ru, and in the case of dimethyl ether DME is in between that one found on clean CeOx and the metal surface. Decomposition of the DEE was observed on the OH/CeOx surface following high DEE exposure at 300 K and higher temperatures. Ethoxides and acetates were identified as adsorbed species on the surface by means of RAIRS and ethoxides and formates by s-XPS. No decomposition of dimethyl ether was observed on the OH/CeOx at these higher temperatures, implying that the dissociation of the C-O bond from ethers requires the presence of {beta}-hydrogen.

F Calaza; T Chen; D Mullins; S Overbury

2011-12-31

157

Structure and Reactivity of Alkyl Ethers Adsorbed on CeO(2)(111) Model Catalysts  

SciTech Connect

The effect of surface hydroxyls on the adsorption of ether on ceria was explored. Adsorption of dimethyl ether (DME) and diethyl ether (DEE) on oxidized and reduced CeO{sub 2}(111) films was studied and compared with Ru(0001) using RAIRS and sXPS within a UHV environment. On Ru(0001) the ethers adsorb weakly with the molecular plane close to parallel to the surface plane. On the ceria films, the adsorption of the ethers was stronger than on the metal surface, presumably due to stronger interaction of the ether oxygen lone pair electrons with a cerium cation. This interaction causes the ethers to tilt away from the surface plane compared to the Ru(0001) surface. No pronounced differences were found between oxidized (CeO{sub 2}) and reduced (CeOx) films. The adsorption of the ethers was found to be perturbed by the presence of OH groups on hydroxylated CeOx. In the case of DEE, the geometry of adsorption resembles that found on Ru, and in the case of dimethyl ether DME is in between that one found on clean CeOx and the metal surface. Decomposition of the DEE was observed on the OH/CeOx surface following high DEE exposure at 300 K and higher temperatures. Ethoxides and acetates were identified as adsorbed species on the surface by means of RAIRS and ethoxides and formates by s-XPS. No decomposition of dimethyl ether was observed on the OH/CeOx at these higher temperatures, implying that the dissociation of the C-O bond from ethers requires the presence of {beta}-hydrogen.

Calaza, Florencia C [ORNL; Chen, Tsung-Liang [ORNL; Mullins, David R [ORNL; Overbury, Steven {Steve} H [ORNL

2011-01-01

158

Ethers  

NSDL National Science Digital Library

Ethers are the focus of these quiz questions from the JCE organic chemistry quiz bank. There are five sets of questions, which focus on epoxides, mechanisms of reactions, synthesis for ether compounds.

Reich, Ieva

159

Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas  

SciTech Connect

As part of the DOE-sponsored contract Synthesis of Dimethyl Ether and Alternative Fuels in the Liquid Phase from Coal-Derived Syngas'' experimental evaluations of the one-step synthesis of alternative fuels were carried out. The objective of this work was to develop novel processes for converting coal-derived syngas to fuels or fuel additives. Building on a technology base acquired during the development of the Liquid Phase Methanol (LPMEOH) process, this work focused on the development of slurry reactor based processes. The experimental investigations, which involved bench-scale reactor studies, focused primarily on three areas: (1) One-step, slurry-phase syngas conversion to hydrocarbons or methanol/hydrocarbon mixtures using a mixture of methanol synthesis catalyst and methanol conversion catalyst in the same slurry reactor. (2) Slurry-phase conversion of syngas to mixed alcohols using various catalysts. (3) One-step, slurry-phase syngas conversion to mixed ethers using a mixture of mixed alcohols synthesis catalyst and dehydration catalyst in the same slurry reactor. The experimental results indicate that, of the three types of processes investigated, slurry phase conversion of syngas to mixed alcohols shows the most promise for further process development. Evaluations of various mixed alcohols catalysts show that a cesium-promoted Cu/ZnO/Al[sub 2]O[sub 3] methanol synthesis catalyst, developed in Air Products' laboratories, has the highest performance in terms of rate and selectivity for C[sub 2+]-alcohols. In fact, once-through conversion at industrially practical reaction conditions yielded a mixed alcohols product potentially suitable for direct gasoline blending. Moreover, an additional attractive aspect of this catalyst is its high selectivity for branched alcohols, potential precursors to iso-olefins for use in etherification.

Underwood, R.P.

1993-01-01

160

Raman and infrared spectra of dimethyl ether 13C-isotopologue (CH3O13CH3) from a CCSD(T) potential energy surface  

NASA Astrophysics Data System (ADS)

So far, no experimental data of the infrared and Raman spectra of 13C isotopologue of dimethyl ether are available. With the aim of providing some clues of its low-lying vibrational bands and with the hope of contributing in a next spectral analysis, a number of vibrational transition frequencies below 300 cm-1 of the infrared spectrum and around 400 cm-1 of the Raman spectrum have been predicted and their assignments were proposed. Calculations were carried out through an ab initio three dimensional potential energy surface based on a previously reported one for the most abundant dimethyl ether isotopologue (M. Villa et al., J. Phys. Chem. A 115 (2011) 13573). The potential function was vibrationally corrected and computed with a highly correlated CCSD(T) method involving the COC bending angle and the two large amplitude CH3 internal rotation degrees of freedom. Also, the Hamiltonian parameters could represent a support for the spectral characterization of this species. Although the computed vibrational term values are expected to be very accurate, an empirical adjustment of the Hamiltonian has been performed with the purpose of anticipating some workable corrections to any possible divergence of the vibrational frequencies. Also, the symmetry breaking derived from the isotopic substitution of 13C in the dimethyl ether was taken into account when the symmetrization procedure was applied.

Carvajal, M.; Álvarez-Bajo, O.; Senent, M. L.; Domínguez-Gómez, R.; Villa, M.

2012-09-01

161

Optimized Structures and Proton Affinities of Fluorinated Dimethyl Ethers: An Ab Initio Study  

NASA Technical Reports Server (NTRS)

Ab initio methods have been used to investigate the proton affinity and the geometry changes upon protonation for the molecules (CH3)2O, (CH2F)2O, (CHF2)2O, and (CF3)2O. Geometry optimizations were performed at the MP2/3-2 I G level, and the resulting geometries were used for single-point energy MP2/6-31G calculations. The proton affinity calculated for (CH3)2O was 7 Kjoule/mole from the experimental value, within the desired variance of +/- 8Kjoule/mole for G2 theory, suggesting that the methodology used in this study is adequate for energy difference considerations. For (CF3)20, the calculated proton affinity of 602 Kjoule/mole suggests that perfluorinated ether molecules do not act as Lewis bases under normal circumstances; e.g. degradation of commercial lubricants in tribological applications.

Orgel, Victoria B.; Ball, David W.; Zehe, Michael J.

1996-01-01

162

Charge Transport in the Insulating State of DMe-DCNQI2Li above TSP: A Possible Fractional Charge Soliton Conduction with 1  

E-print Network

Charge Transport in the Insulating State of DMe-DCNQI2Li above TSP: A Possible Fractional Charge) A spin-Peierls system DMe-DCNQI2Li is studied with W-band electron paramagnetic resonance (EPR) ( 94 GHz that a quasi-one-dimensional (Q1D) -electronic system, lithium salt with dimethyl- dicyanoquinone-diimine DMe

Mizoguchi, Kenji

163

Spasmolytic effect of galetin 3,6-dimethyl ether, a flavonoid obtained from Piptadenia stipulacea (Benth) Ducke.  

PubMed

Piptadenia stipulacea (Benth) Ducke is a tree of the Caatinga, in Northeast Brazil, popularly known as "Jurema-branca", "Jurema malícia-da-serra", "Carcará" and "Calumbi". In folk medicine, a decoction or tincture of its bark and leaves are used to treat wounds and as healing agents. Galetin 3,6-dimethyl ether (FGAL) is a flavonoid isolated from the aerial components of Piptadenia stipulacea (Benth) Ducke. We decided to investigate a possible FGAL spasmolytic effect on preparations of both the guinea pig ileum and trachea, the rat uterus and the male rat aorta. FGAL inhibited oxytocin (IC(50) = 2.2 ± 0.4 × 10(-5) M) and carbachol (CCh)-induced (IC(50) = 7.7 ± 1.3 × 10(-5) M) phasic contractions in the rat uterus, but was more effective in the inhibition of the oxytocin-induced contractions. In the guinea pig ileum, FGAL equipotently inhibited CCh (IC(50) = 2.8 ± 0.4 × 10(-5) M) and histamine-induced (IC(50) = 2.3 ± 0.5 × 10(-5) M) phasic contractions. FGAL equipotently and concentration-dependently relaxed guinea pig trachea preparations pre-contracted with CCh, both in the absence (EC(50) = 0.8 ± 0.1 × 10(-5) M) and presence (EC(50) = 1.0 ± 0.1 × 10(-5) M) of a functional epithelium. FGAL also relaxed preparations of the rat aorta pre-contracted with phenylephrine in both the absence (EC(50) = 5.0 ± 1.1 × 10(-6) M) and presence (EC(50) = 5.4 ± 1.2 × 10(-6) M) of a functional endothelium. FGAL shows a non-selective spasmolytic effect on each of the smooth muscle preparations we have tested, but with a greater effect on those from the rat aorta. The relaxant effect on preparations of both the guinea pig trachea and the rat aorta seems to not involve the epithelium or endothelium-derived relaxing factors. PMID:22104374

Macêdo, Cibério Landim; Vasconcelos, Luiz Henrique César; Correia, Ana Carolina de C; Martins, Italo Rossi Roseno; de Lira, Daysianne Pereira; Santos, Bárbara Viviana de Oliveira; da Silva, Bagnólia Araújo

2011-01-01

164

A cryospectroscopic study of the blue-shifting C–H?O bonded complexes of pentafluoroethane with dimethyl ether-d 6, acetone-d 6 and oxirane-d 4  

Microsoft Academic Search

The infrared spectra of solutions of pentafluoroethane, CHF2CF3, and dimethyl ether-d6, acetone-d6, or oxirane-d4 dissolved in liquid krypton were investigated, at temperatures between 118 and 168K. In all spectra, evidence was found for the formation of C–H?O hydrogen bonded complexes that are characterized by a blue shift in the C–H stretching fundamental. The shifts were found to be +15.1cm?1 (dimethyl

B. J. van der Veken; S. N. Delanoye; B. Michielsen; W. A. Herrebout

2010-01-01

165

Bifunctional pathways mediated by Pt clusters and Al2O3 in the catalytic combustion of dimethyl ether{  

E-print Network

of c-Al2O3 and ZrO2 supports on DME combustion turnover rates. The combination of acid sites on various for 5 h before use. ZrO2 was prepared as previously described.8 Pt/Al2O3 and Pt/ZrO2 were prepared by incipient wetness impregnation of c-Al2O3 or ZrO2 with aqueous H2PtCl6?6H2O solutions and subsequent

Iglesia, Enrique

166

Di-?-acetato-bis­(dimethyl­formamide)­penta­kis­(?-N,2-dioxidobenzene-1-car­boximidato)tetra­kis­(1-ethyl­imidazole)­penta­manganese(III)­manganese(II)–diethyl ether–dimethyl­foramide–methanol–water (1/1/1/1/0.12)  

PubMed Central

The title compound [Mn6(C7H4NO3)5(CH3CO2)2(C5H8N2)4(C3H7NO)2]·(C2H5)2O·C3H7NO·CH3OH·0.12H2O, abbreviated as MnII(OAc)2[15-MCMnIII(N)shi-5](EtIm)4(DMF)2·diethyl ether·DMF·MeOH·0.12H2O (where ?OAc is acetate, MC is metallacrown, shi3? is salicylhydroximate, EtIM is n-ethylimidazole, DMF is N,N-dimethylformamide, and MeOH is methanol) contains five MnIII ions as members of the metallacrown ring and an MnII ion bound in the central cavity. The central MnII ion is seven-coordinate with a distorted face-capped trigonal–prismatic geometry. The five MnIII ions of the metallacrown ring are six-coordinate with distorted octa­hedral geometries. The configuration of the MnIII ions about the metallacrown ring follow a ???PP pattern, with P representing planar. The four 1-ethyl­imidazole ligands are bound to four different MnIII ions. A diethyl ether solvent mol­ecule was found to be disordered over two mutually exclusive sites with an occupancy ratio of 0.568?(7):0.432?(7). A methanol solvent mol­ecule was found to be disordered over two mutually exclusive sites by being hydrogen bonded either to a dimethyl­formamide solvent mol­ecule (major occupancy component) or to an O atom of the main mol­ecule (minor occupancy component). The occupancy ratio refined to 0.678?(11):0.322?(11). Associated with the minor component is a partially occupied water mol­ecule [total occupancy 0.124?(15)]. PMID:22090833

Tigyer, Benjamin R.; Zeller, Matthias; Zaleski, Curtis M.

2011-01-01

167

Di-?-acetato-bis-(dimethyl-formamide)-penta-kis-(?-N,2-dioxidobenzene-1-car-boximidato)tetra-kis-(1-ethyl-imidazole)-penta-manganese(III)-manganese(II)-diethyl ether-dimethyl-foramide-methanol-water (1/1/1/1/0.12).  

PubMed

The title compound [Mn(6)(C(7)H(4)NO(3))(5)(CH(3)CO(2))(2)(C(5)H(8)N(2))(4)(C(3)H(7)NO)(2)]·(C(2)H(5))(2)O·C(3)H(7)NO·CH(3)OH·0.12H(2)O, abbreviated as Mn(II)(OAc)(2)[15-MC(MnIII(N)shi)-5](EtIm)4(DMF)2·diethyl ether·DMF·MeOH·0.12H(2)O (where (-)OAc is acetate, MC is metallacrown, shi(3-) is salicylhydroximate, EtIM is n-ethylimidazole, DMF is N,N-dimethylformamide, and MeOH is methanol) contains five Mn(III) ions as members of the metallacrown ring and an Mn(II) ion bound in the central cavity. The central Mn(II) ion is seven-coordinate with a distorted face-capped trigonal-prismatic geometry. The five Mn(III) ions of the metallacrown ring are six-coordinate with distorted octa-hedral geometries. The configuration of the Mn(III) ions about the metallacrown ring follow a ???PP pattern, with P representing planar. The four 1-ethyl-imidazole ligands are bound to four different Mn(III) ions. A diethyl ether solvent mol-ecule was found to be disordered over two mutually exclusive sites with an occupancy ratio of 0.568?(7):0.432?(7). A methanol solvent mol-ecule was found to be disordered over two mutually exclusive sites by being hydrogen bonded either to a dimethyl-formamide solvent mol-ecule (major occupancy component) or to an O atom of the main mol-ecule (minor occupancy component). The occupancy ratio refined to 0.678?(11):0.322?(11). Associated with the minor component is a partially occupied water mol-ecule [total occupancy 0.124?(15)]. PMID:22090833

Tigyer, Benjamin R; Zeller, Matthias; Zaleski, Curtis M

2011-08-01

168

Molecular structure of ThBr{sub 4}(DME){sub 2} (DME = 1,2-dimethoxyethane)  

SciTech Connect

The molecular structure of ThBr{sub 4}(DME){sub 2}(DME = 1,2-dimethoxyethane), the first structurally characterized thorium complex containing a simple bidentate ether ligand, is described. The eight-coordinate complex presents a distorted dodecahedral geometry, with Th-Br and Th-O bond lengths in the ranges 2.8516(13)-2.8712(13) {angstrom} and 2.564(8)-2.620(8) {angstrom}, respectively. ThBr{sub 4}(DME){sub 2} is monoclinic, space group P2{sub 1}/n, a = 7.672(1), b = 14.581(1), c = 15.847(2) {angstrom}, {beta} = 102.24(1){degree}, V = 1732.4(3) {angstrom}{sup 3}, and Z = 4.

Rabinovich, D.; Scott, B.L.; Nielsen, J.B.; Abney, K.D.

1999-02-01

169

Interface Properties between Lithium Metal and a Composite Polymer Electrolyte of PEO18Li(CF3SO2)2N-Tetraethylene Glycol Dimethyl Ether  

PubMed Central

The electrochemical properties of a composite solid polymer electrolyte, consisting of poly(ethylene oxide) (PEO)-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and tetraethylene glycol dimethyl ether (TEGDME) was examined as a protective layer between lithium metal and a water-stable lithium ion-conducting glass ceramic of Li1+x+y(Ti,Ge)2?xAlxP3?ySiyO12 (LTAP). The lithium ion conductivity and salt diffusion coefficient of PEO18LiTFSI were dramatically enhanced by the addition of TEGDME. The water-stable lithium electrode with PEO18LiTFSI-2TEGDME, as the protective layer, exhibited a low and stable electrode resistance of 85 ?·cm2 at 60 °C, after 28 days, and low overpotentials of 0.3 V for lithium plating and 0.4 V for lithium stripping at 4.0 mA·cm?2 and 60 °C. A Li/PEO18LiTFSI-2TEGDME/LTAP/saturated LiCl aqueous solution/Pt, air cell showed excellent cyclability up to 100 cycles at 2.0 mAh·cm?2. PMID:24957059

Wang, Hui; Matsui, Masaki; Takeda, Yasuo; Yamamoto, Osamu; Im, Dongmin; Lee, Dongjoon; Imanishi, Nobuyuki

2013-01-01

170

Physicochemical and catalytic characteristics of La-H-ZSM-5 zeolite in converting dimethyl ether to the mixtures of gasoline hydrocarbons: Effect of ion exchange conditions  

NASA Astrophysics Data System (ADS)

The effect of the manner and conditions of introducing lanthanum cations into NH4-ZSM-5 zeolite on the properties of catalysts for the conversion of dimethyl ether into the mixtures of gasoline hydrocarbons is studied. The physicochemical properties of synthesized catalysts are studied by means of temperature-programmed ammonia desorption, the adsorption of benzene, atomic absorption spectroscopy, differential scanning calorimetry, and thermogravimetry. It is shown that the degree to which lanthanum cations are replaced by ammonium cations both depends on the conditions of ion exchange in the zeolite and affects its acidity spectrum and the selectivity of the formation of paraffin hydrocarbons with isostructure. It is concluded that an increase in the amount of introduced lanthanum leads to an increase in the content of iso-paraffins from 69 to 76 wt % and a decrease in the content of aromatic hydrocarbons from 10.5 to 5.5 wt % and that of durene from 1.5 to 0.2 wt % in the products.

Kitaev, L. E.; Bukina, Z. M.; Yushchenko, V. V.; Ionin, D. A.; Kolesnichenko, N. V.; Khadzhiev, S. N.

2014-03-01

171

Spray characteristics of alternative fuels in constant volume chamber(comparison of the spray characteristics of LPG, DME and n-dodecane)  

Microsoft Academic Search

It has been recognized that alternative fuels such as dimethyl ether\\u000d\\u000a\\u0009(DME) and liquefied petroleum gas (LPG) have less polluting combustion\\u000d\\u000a\\u0009characteristics than diesel fuel. In this study, such alternative\\u000d\\u000a\\u0009fuels were injected into a high pressure and temperature chamber\\u000d\\u000a\\u0009by means of an electronically controlled common rail injection system\\u000d\\u000a\\u0009to reproduce their charge stratification processes in the engine.\\u000d\\u000a\\u0009Their

Seang-Wock Lee; Jin Kusaka; Yasuhiro Daisho

2001-01-01

172

VOR\\/DME system improvements  

Microsoft Academic Search

The VOR\\/DME\\/TACAN system of short distance navigation in the United States has provided service over the past decade to all civil and military air traffic. Improvements have been incorporated which have been in the nature of refinements, assuring adequate performance for all current aircraft needs. Recent analyses indicate that continued use of VOR\\/DME to meet increased civil air traffic demands

A. B. Winick; D. M. Brandewie

1970-01-01

173

Nature of K[sup +]/crown ether interactions. A hybrid quantum mechanical-molecular mechanical study  

SciTech Connect

We present a hybrid quantum mechanical/molecular mechanical (QM/MM) molecular dynamics study of dimethyl ether (DME) and 18-crown-6 (18c6) interacting with K[sup +]. The QM/MM method employs the semiempirical AM1 method to describe the ethers, the MM parametrization of Dang for K[sup +], and the MM SPC/e model for H[sub 2]O. We parametrize the interaction Hamiltonian to the binding energies and optimized geometries for K[sup +]/DME using ab initio HF and MP2/6-31+G* results. The resulting QM/MM model describes the polarization response of both free DME and K[sup +]-complexed DME well. The QM/MM model gives good agreement with the experimental and ab initio structures for K[sup +]/18c6. We calculate gas-phase K[sup +]/18c6 binding energies of [minus]70.2 and [minus]72.0 kcal/mol with the QM/MM and MP2/6-31+G* (CP corrected) methods, respectively. Our simulation results for K[sup +]/18c6 in H[sub 2]O show that the most probable K[sup +]/18c6 center-of-mass displacement is 0.25 [angstrom], in marked contrast to previous molecular dynamics results of Dang and Kollman. Our result is consistent with K[sup +] having an optimal [open quotes]fit[close quotes] for the cavity of 18c6. Still, we find that K[sup +] retains significant solvent accessibility coordinating two H[sub 2]O molecules, on average, in the K[sup +]/18c6 simulation. 81 refs., 13 figs., 4 tabs.

Thompson, M.A.; Glendening, E.D.; Feller, D. (Pacific Northwest Lab., Richland, WA (United States))

1994-10-13

174

Electrochemical oxidation of hydrolyzed poly oxymethylene-dimethyl ether by PtRu catalysts on Nb-doped SnO(2-?) supports for direct oxidation fuel cells.  

PubMed

We synthesized Pt and PtRu catalysts supported on Nb-doped SnO(2-?) (Pt/Sn0.99Nb0.01O(2-?), PtRu/Sn0.99Nb0.01O(2-?)) for direct oxidation fuel cells (DOFCs) using poly oxymethylene-dimethyl ether (POMMn, n = 2, 3) as a fuel. The onset potential for the oxidation of simulated fuels of POMMn (methanol-formaldehyde mixtures; n = 2, 3) for Pt/Sn0.99Nb0.01O(2-?) and PtRu/Sn0.99Nb0.01O(2-?) was less than 0.3 V vs RHE, which was much lower than those of two commercial catalysts (PtRu black and Pt2Ru3/carbon black). In particular, the onset potential of the oxidation reaction of simulated fuels of POMMn (n = 2, 3) for PtRu/Sn0.99Nb0.01O(2-?) sintered at 800 °C in nitrogen atmosphere was less than 0.1 V vs RHE and is thus considered to be a promising anode catalyst for DOFCs. The mass activity (MA) of PtRu/Sn0.99Nb0.01O(2-?) sintered at 800 °C was more than five times larger than those of the commercial catalysts in the measurement temperature range from 25 to 80 °C. Even though the MA for the methanol oxidation reaction was of the same order as those of the commercial catalysts, the MA for the formaldehyde oxidation reaction was more than five times larger than those of the commercial catalysts. Sn from the Sn0.99Nb0.01O(2-?) support was found to have diffused into the Pt catalyst during the sintering process. The Sn on the top surface of the Pt catalyst accelerated the oxidation of carbon monoxide by a bifunctional mechanism, similar to that for Pt-Ru catalysts. PMID:25415540

Kakinuma, Katsuyoshi; Kim, In-Tae; Senoo, Yuichi; Yano, Hiroshi; Watanabe, Masahiro; Uchida, Makoto

2014-12-24

175

A cryospectroscopic study of the blue-shifting C-H⋯O bonded complexes of pentafluoroethane with dimethyl ether-d 6, acetone-d 6 and oxirane-d 4  

NASA Astrophysics Data System (ADS)

The infrared spectra of solutions of pentafluoroethane, CHF 2CF 3, and dimethyl ether-d 6, acetone-d 6, or oxirane-d 4 dissolved in liquid krypton were investigated, at temperatures between 118 and 168 K. In all spectra, evidence was found for the formation of C-H⋯O hydrogen bonded complexes that are characterized by a blue shift in the C-H stretching fundamental. The shifts were found to be +15.1 cm -1 (dimethyl ether-d 6), +24.3 cm -1 (acetone-d 6) and +20.3 cm -1 (oxirane-d 4), while the corresponding intensity ratios ?com/ ?mon were derived to be 0.35(1), 0.42(5) and 0.54(2). Using spectra recorded at different temperatures the complexation enthalpy ?H? for the complexes were determined to be -12.1(1), -12.9(1) and -12.6(1) kJ mol -1, respectively. The results are compared with theoretical data obtained by combining ab initio complexation energies with thermal and solvent corrections obtained from statistical thermodynamical calculations and Monte Carlo-Free Energy Perturbation simulations. The results are also compared with experimental and theoretical data obtained for the complexes formed between the same proton acceptors and fluoroform.

van der Veken, B. J.; Delanoye, S. N.; Michielsen, B.; Herrebout, W. A.

2010-07-01

176

Stabilized three-stage oxidation of DME/air mixture in a micro flow reactor with a controlled temperature profile  

SciTech Connect

Ignition and combustion characteristics of a stoichiometric dimethyl ether (DME)/air mixture in a micro flow reactor with a controlled temperature profile which was smoothly ramped from room temperature to ignition temperature were investigated. Special attention was paid to the multi-stage oxidation in low temperature condition. Normal stable flames in a mixture flow in the high velocity region, and non-stationary pulsating flames and/or repetitive extinction and ignition (FREI) in the medium velocity region were experimentally confirmed as expected from our previous study on a methane/air mixture. In addition, stable double weak flames were observed in the low velocity region for the present DME/air mixture case. It is the first observation of stable double flames by the present methodology. Gas sampling was conducted to obtain major species distributions in the flow reactor. The results indicated that existence of low-temperature oxidation was conjectured by the production of CH{sub 2}O occured in the upstream side of the experimental first luminous flame, while no chemiluminescence from it was seen. One-dimensional computation with detailed chemistry and transport was conducted. At low mixture velocities, three-stage oxidation was confirmed from profiles of the heat release rate and major chemical species, which was broadly in agreement with the experimental results. Since the present micro flow reactor with a controlled temperature profile successfully presented the multi-stage oxidations as spatially separated flames, it is shown that this flow reactor can be utilized as a methodology to separate sets of reactions, even for other practical fuels, at different temperature. (author)

Oshibe, Hiroshi; Nakamura, Hisashi; Tezuka, Takuya; Hasegawa, Susumu; Maruta, Kaoru [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

2010-08-15

177

Coexistence of one- and three-dimensional Fermi surfaces and heavy cyclotron mass in the molecular conductor (DMe-DCNQI)2Cu  

Microsoft Academic Search

The Fermi surface of the molecular conductor (DMe-DCNQI)2Cu (DMe-DCNQI=2,5-dimethyl-N,N'-dicyanoquinonediimine) has been investigated by the de Haas-van Alphen method. Seven different oscillations with heavy cyclotron masses are observed at frequencies lower than 3000 T. These effects arise from the three-dimensional (3D) Fermi surface which is dominated mainly by the Cu 3d orbital character. Many oscillations with frequency higher than 3000 T

S. Uji; T. Terashima; H. Aoki; J. S. Brooks; R. Kato; H. Sawa; S. Aonuma; M. Tamura; M. Kinoshita

1994-01-01

178

Spin-Peierls transition of the quasi-one-dimensional electronic system (DMe-DCNQI)2M (M=Li,Ag) probed by heat capacity  

Microsoft Academic Search

Through ac and thermal relaxation calorimetry techniques, we have performed a thermodynamic investigation of the spin-Peierls systems, (DMe-DCNQI)2Ag and (DMe-DCNQI)2Li, where DMe-DCNQI is 2,5-dimethyl-N,N'-dicyanoquinonediimine. The fully gapped nature characteristic of the spin-Peierls (sP) ground state was confirmed by the absence of gamma (T-linear) term in the low-temperature heat capacity for a single crystal. At higher temperatures, two distinct peaks were

Yasuhiro Nakazawa; Akane Sato; Mitsuro Seki; Kazuya Saito; Ko-Ichi Hiraki; Toshihiro Takahashi; Kazushi Kanoda; Michio Sorai

2003-01-01

179

Dimethyl Fumarate  

MedlinePLUS

Dimethyl fumarate is used to treat relapsing forms (course of disease where symptoms flare up from time to ... and problems with vision, speech, and bladder control). Dimethyl fumarate is in a class of medications called Nrf2 ...

180

KINETIC UNDERSTANDING OF THE SYNGAS-TO-DME REACTION SYSTEM AND ITS IMPLICATIONS TO PROCESS AND ECONOMICS  

SciTech Connect

In a single-step synthesis gas-to-dimethyl ether process, synthesis gas (or syngas, a mixture of H{sub 2} and CO) is converted into dimethyl ether (DME) in a single reactor. The three reactions involved in this process, methanol synthesis, methanol dehydration and water gas shift, form an interesting reaction network. The interplay among these three reactions results in excellent syngas conversion or reactor productivity. A fundamental understanding of this interplay helps to explain many experimental and simulation observations, to identify optimal reaction conditions, and to provide guidelines for process development. The higher syngas conversion or reactor productivity in the syngas-to-DME reaction system, compared to that in the syngas-to-methanol reaction system, is referred to as chemical synergy. This synergy exhibits a strong dependence on the composition of the reactor feed. To demonstrate the extent of this dependence, simulations with adjusted activity for each reaction were performed to reveal the relative rate of each reaction. The results show that the water gas shift reaction is the most rapid, being practically controlled by the equilibrium. Both methanol synthesis and methanol dehydration reactions are kinetically controlled. The kinetics of the dehydration reactions is greater than that of the methanol synthesis reaction in the CO-rich regime. However, the rates of these two reactions come closer as the H{sub 2} concentration in the reactor feed increases. The role of the dehydration reaction is to remove the equilibrium barrier for the methanol synthesis reaction. The role of the water gas shift reaction is more complex; it helps the kinetics of methanol dehydration by keeping the water concentration low, which in turn enhances methanol synthesis. It also readjusts the H{sub 2}:CO ratio in the reactor as the reactions proceed. In the CO-rich regime, the water gas shift reaction supplements the limiting reactant, H{sub 2}, by reacting water with CO. This enhances both the kinetics and thermodynamic driving force of the methanol synthesis reaction. In the H{sub 2}-rich regime, water gas shift consumes the limiting reactant, CO, which harms both the kinetics and thermodynamics of methanol synthesis. An understanding of these complex roles of the methanol dehydration and water gas shift reactions and of their dependence on the syngas composition explains why the synergy is high in the CO-rich regime, but decreases with increasing H{sub 2} or CO{sub 2} content in the reactor feed. The methanol equivalent productivity of the syngas-to-DME reactor is also a strong function of the reactor feed. A mathematical approach was developed to understand this dependence. The approach divides a power law type of rate equation into two terms, the kinetic term (the rate of the forward reaction) and the thermodynamics or driving force term (1- approach to equilibrium). The equations for the best feed composition for each term were derived. The approach was developed for the single reaction system, and then extended to the syngas-to-DME reaction system. The equations provide insights into why and how the methanol synthesis in the syngasto-DME system depends on the other two reactions. They can also be used to calculate the best feed composition for a given conversion. The analysis shows that for typical commercial syngas conversion, the optimal H{sub 2}:CO ratio for the LPDME{trademark} reactor is around 1-to-1, in good agreement with the results from the simulation. While the 1-to-1 feed provides a good foundation for some process configurations, it does not match the composition of natural gas-derived syngas, which typically has a H{sub 2}:CO ratio of 2:1 or greater. The process would also produce one CO{sub 2} molecule for every DME product, both a materials utilization and an environmental problem. However, recycling CO{sub 2} to the syngas generation unit can solve all of these problems. Integration schemes with different syngas generation technologies (dry reforming, steam methane reforming and partial oxidation) were

Xiang-Dong Peng

2002-12-01

181

Optimal design and operation of a natural gas tri-reforming reactor for DME synthesis  

Microsoft Academic Search

Korea Gas Corporation (KOGAS) is developing a new di-methyl-ether (DME) plant. Syngas is provided by natural gas tri-reforming, in a reactor consisting of a homogenous part where oxidation leads to a temperature increase required for the reforming reactions and a catalytic part where the reforming reactions take place. A first principle model for the tri-reforming reactor is developed. A kinetic

Wonjun Cho; Taekyong Song; Alexander Mitsos; J. Thomas McKinnon; Glen H. Ko; John E. Tolsma; Douglas Denholm

2009-01-01

182

Synthesis of dimethyl ether and alternative fuels in the liquid phase from coal-derived synthesis gas. Task 3.2: Screen novel catalyst systems; Task 3.3:, Evaluation of the preferred catalyst system  

SciTech Connect

As part of the DOE-sponsored contract ``Synthesis of Dimethyl Ether and Alternative Fuels in the Liquid Phase from Coal-Derived Syngas`` experimental evaluations of the one-step synthesis of alternative fuels were carried out. The objective of this work was to develop novel processes for converting coal-derived syngas to fuels or fuel additives. Building on a technology base acquired during the development of the Liquid Phase Methanol (LPMEOH) process, this work focused on the development of slurry reactor based processes. The experimental investigations, which involved bench-scale reactor studies, focused primarily on three areas: (1) One-step, slurry-phase syngas conversion to hydrocarbons or methanol/hydrocarbon mixtures using a mixture of methanol synthesis catalyst and methanol conversion catalyst in the same slurry reactor. (2) Slurry-phase conversion of syngas to mixed alcohols using various catalysts. (3) One-step, slurry-phase syngas conversion to mixed ethers using a mixture of mixed alcohols synthesis catalyst and dehydration catalyst in the same slurry reactor. The experimental results indicate that, of the three types of processes investigated, slurry phase conversion of syngas to mixed alcohols shows the most promise for further process development. Evaluations of various mixed alcohols catalysts show that a cesium-promoted Cu/ZnO/Al{sub 2}O{sub 3} methanol synthesis catalyst, developed in Air Products` laboratories, has the highest performance in terms of rate and selectivity for C{sub 2+}-alcohols. In fact, once-through conversion at industrially practical reaction conditions yielded a mixed alcohols product potentially suitable for direct gasoline blending. Moreover, an additional attractive aspect of this catalyst is its high selectivity for branched alcohols, potential precursors to iso-olefins for use in etherification.

Underwood, R.P.

1993-01-01

183

Performance and Emissions of a Second Generation Biofuel -DME  

E-print Network

Performance and Emissions of a Second Generation Biofuel - DME D. Kittelson1, W. Watts1, D. Bennett, 2010 #12;Performance and Emissions of a Second Generation Biofuel: DME · We started working on a three will briefly describe why we are excited about the potential of DME #12;Outline · DME basics · Environmental

Minnesota, University of

184

Preparation and catalytic performance of CuO-znO-AlO3/clinoptilolite nanocatalyst for single-step synthesis of dimethyl ether from syngas as a green fuel.  

PubMed

Direct conversion of syngas to dimethyl ether was successfully carried out over a clinoptilolite supported nanocatalyst modified by NH4Cl. A series of bifunctional nanocatalysts, CuO-ZnO-Al2O3 (CZA) over Clinoptilolite with different loading of CZA, were prepared via coprecipitation method and their catalytic performance were compared in a fixed-bed high pressure reactor. The catalysts were characterized by XRD, BET, FESEM, FTIR and TPD-NH3 techniques. The physicochemical analysis showed that with NH4CI treatment, the specific surface area of clinoptilolite increased obviously, while its crystallinity decreased slightly. It was found that the crystallinity of clinoptilolite was dramatically changed, whereas crystallinity of CuO has not been influenced significantly by the increase of CZA content. Moreover, with increasing the CZA/Clinoptilolite ratio, the specific surface area of nanocatalysts decreased. It is shown that the CZA particle size is distributed between 30.5-131.2 nm with an average size of 70.6 nm in which 77.8% of the particles are in the range of below 100 nm. The TPD-NH3 patterns showed that the number of the acid sites of the nanocatalysts decreased with the increase the CZA content. The influence of reaction pressure was investigated, confirming that the optimal reaction pressure for this catalyst was 40 bar. The catalytic performance is shown that the CZA/Clinoptilolite = 2 nanocatalyst had higher activity, selectivity due to its higher acidic sites. PMID:23901522

Khoshbin, Reza; Haghighi, Mohammad

2013-07-01

185

A velocity map imaging photoelectron spectrometer for the study of ultrafine aerosols with a table-top VUV laser and Na-doping for particle sizing applied to dimethyl ether condensation.  

PubMed

We present a new experimental configuration for the study of size-dependent, angle-resolved photoelectron and photoion spectra of weakly bound ultrafine aerosol particles targeted at particle sizes below ~20 nm. It combines single photon ionization by a tunable, table-top vacuum ultraviolet laser at energies up to 18 eV with velocity map imaging detection and independent size determination of the aerosol particles using the Na-doping method. As an example, the size-dependence of the valence photoelectron spectrum of dimethyl ether clusters and ultrafine aerosols is investigated. Up to a mean particle diameter of ~3-4 nm, the first ionization energy (value at band maximum) decreases systematically (up to ~1 eV) and the corresponding band broadens systematically (up to a factor of ~3) with increasing aggregate size. Plateau values for band positions and bandwidths are reached beyond a diameter of ~3-4 nm. Experimental evidence for the dominance of the fast intermolecular proton transfer over monomer fragmentation reactions upon ionization is presented via photoion imaging. PMID:23387577

Yoder, Bruce L; West, Adam H C; Schläppi, Bernhard; Chasovskikh, Egor; Signorell, Ruth

2013-01-28

186

Characterization of knocking combustion in HCCI DME engine using wavelet packet transform  

Microsoft Academic Search

A diesel engine is modified for homogeneous charge compression ignition (HCCI) combustion with dimethyl ether. With and without knock, in-cylinder pressure is acquired, and in-cylinder temperature, rate of heat release (ROHR), pressure rise rate and pressure rise acceleration obtained. Wavelet packet transform is performed to decompose pressure signal into three layers with subsignals obtained. Three wavelet packet quantifiers for seven

Junxing Hou; Xinqi Qiao; Zhen Wang; Wei Liu; Zhen Huang

2010-01-01

187

Alternative Position and Navigation based on DME Accumulated Delta Range  

E-print Network

Alternative Position and Navigation based on DME Accumulated Delta Range Tunc Ertan and Mark L Measuring Equip- ment (DME) ground transponders. This method provides an Alternative Position and Navigation]. The use of the existing Distance Measuring Equipment (DME) ground transponder network has been proposed

Psiaki, Mark L.

188

ORIGINAL ARTICLE DME/TACAN interference mitigation for GNSS: algorithms  

E-print Network

ORIGINAL ARTICLE DME/TACAN interference mitigation for GNSS: algorithms and flight test results in this frequency band, in particular, pulsed signals from distance measuring equip- ment (DME) and tactical air and necessary. We first present the real DME/TACAN environment at Stanford, CA as an example to illustrate

Gao, Grace Xingxin

189

14 CFR 171.321 - DME and marker beacon performance requirements.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false DME and marker beacon performance requirements...Microwave Landing System (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the...

2012-01-01

190

14 CFR 171.321 - DME and marker beacon performance requirements.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false DME and marker beacon performance requirements...Microwave Landing System (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the...

2011-01-01

191

14 CFR 171.321 - DME and marker beacon performance requirements.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false DME and marker beacon performance requirements...Microwave Landing System (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the...

2014-01-01

192

14 CFR 171.321 - DME and marker beacon performance requirements.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false DME and marker beacon performance requirements...Microwave Landing System (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME equipment must meet the...

2013-01-01

193

Direct synthesis of DME over bifunctional catalyst: surface properties and catalytic performance  

Microsoft Academic Search

A series of bifunctional catalysts CuO\\/ZnO\\/ZrO2\\/HZSM-5 with different ZrO2 contents were prepared and characterized by surface area, XRD and XPS analysis. The catalytic system was evaluated in the development of STD process (synthesis gas-to-dimethyl ether). Based on these results, it was deduced that the incorporation of ZrO2 in CuO lattice caused the formation of Cu+ on the catalyst surface during

Kunpeng Sun; Weiwei Lu; Fengyan Qiu; Shuwen Liu; Xianlun Xu

2003-01-01

194

Conversion of Biomass Syngas to DME Using a Microchannel Reactor  

Microsoft Academic Search

The capability of a microchannel reactor for direct synthesis of dimethylether (DME) from biomass syngas was explored. The reactor was operated in conjunction with a hybrid catalyst system consisting of methanol synthesis and dehydration catalysts, and the influence of reaction parameters on syngas conversion was investigated. The activities of different dehydration catalysts were compared under DME synthesis conditions. Reaction temperature

Jianli Hu; Yong Wang; Chunshe Cao; Douglas C. Elliott; Don J. Stevens; James F. White

2005-01-01

195

1H, 7Li, and 19F nuclear magnetic resonance and ionic conductivity studies for liquid electrolytes composed of glymes and polyetheneglycol dimethyl ethers of CH3O(CH2CH2O)nCH3 (n=3-50) doped with LiN(SO2CF3)2  

NASA Astrophysics Data System (ADS)

Solid polyethyleneoxides (PEO) are in effect "polymer liquids" due to their flexibility and high solubility for alkaline salts. To clarify the role of PEO in electrolyte systems, electrolytes composed of members of the "glyme family" [i.e., diglyme(DG), triglyme(TG), tetraglyme(TeG), pentaglyme(PG), and polyethyleneglycol dimethyl ethers(PEGDM)] doped with LiN(SO2CF3)2 were investigated. PEGDMs form a series of low molecular weight PEO-like homologues with molecular weights between 400 and 2500. Electrolytes of the glymes and PEGDMs were prepared for two salt concentrations (ether oxygen: lithium; O:Li) 20:1 and 10:1. The ionic conductivities and the self-diffusion coefficients of the solvent, anion and lithium ions in the electrolytes were measured using pulsed-field gradient spin-echo (PGSE) 1H, 19F, and 7Li NMR, respectively. From the spin-lattice relaxation times (T1) it was found that the segmental motions of the CH2CH2O moiety and the lithium hopping motions are correlated and that the rate of the segmental motions decreases as the molecular size of the solvent increases. The ionic conductivities calculated from the diffusion coefficients are compared with the experimental ac ionic conductivities. The diffusion and ion conduction mechanisms are discussed and the lithium ion-solvent interactions are shown to depend on the solvent size.

Hayamizu, Kikuko; Akiba, Etsuo; Bando, Toshinori; Aihara, Yuichi

2002-09-01

196

Carbonylation DOI: 10.1002/anie.200900464  

E-print Network

to produce dimethyl ether (DME) and methyl formate (MF) [Eq. (2)] was the only competing process observed. 2 to MMAc and the rate of DMM disproportionation to DME and MF are shown in Figure 1a. The products DME and MF were formed in a ratio DME:MF close to two, consistent with the stoichiometry of Equation (2

Bell, Alexis T.

197

Study on the application of DME\\/diesel blends in a diesel engine  

Microsoft Academic Search

In this paper fuels, based on various DME to diesel ratios are investigated. Physical and chemical properties of DME and diesel display mutual solubility at any ratio. The vapor pressure of DME\\/diesel blends is lower than that of pure DME at the same temperatures and it decreases with an increase of diesel mass fraction in blends, which is beneficial to

Wang Ying; Li Genbao; Zhu Wei; Zhou Longbao

2008-01-01

198

High octane ethers from synthesis gas-derived alcohols. Quarterly technical progress report, April--June 1993  

SciTech Connect

The results shown in Figures 10 and 11 demonstrate that the formation of butenes was very sensitive to the alcohol partial pressure. A small elevation of the alcohol pressure suppressed the formation of butenes rather drastically at both 90 and 117{degree}C. The synthesis rates of DME, MIBE, and MTBE ethers were not significantly affected at 90{degree}C, although there was a trend to increase the space time yield of DME as the alcohol pressure was increased. At the reaction temperature of 117{degree}C, all of the ethers showed increasing productivities as the pressure of the reactants was increased (Figure 11). An isotope labelling experiment was carried out to provide mechanistic insight into the manner in which methanol and isobutanol react together to form DME, MIBE, and MTBE ethers and to determine if MTBE were derived from MIBE.

Klier, K.; Herman, R.G.; Menszak, J.; Johansson, M.A.; Feeley, O.C.; Kim, D.

1993-07-01

199

Investigation of Volumetric Properties of Some Glycol Ethers Using a Simple Equation of State  

NASA Astrophysics Data System (ADS)

In this work, a simple equation of state (EoS) has been used to predict the density and other thermodynamic properties such as the isobaric expansion coefficient, ? P , the isothermal compressibility, ? T , and the internal pressure, P i , of six glycol ethers including diethylene glycol monobutyl ether (DEGBE), propylene glycol propyl ether (PGPE), diethylene glycol monomethyl ether (DEGME), diethylene glycol monoethyl ether (DEGEE), triethylene glycol dimethyl ether (TriEGDME), and tetraethylene glycol dimethyl ether (TEGDME) at different temperatures and pressures. A comparison with literature experimental data has been made. Additionally, statistical parameters between experimental and calculated densities for the GMA EoS and four other EoSs (Soave Redlich Kwong, Peng Robinson, Soave Redlich Kwong with volume translation, and Patel Teja) indicate the superiority of the GMA EoS.

Moosavi, M.; Goharshadi, E. K.

2006-09-01

200

Planar-DME: a single-layer zero-skew clock tree router  

Microsoft Academic Search

This paper presents new single-layer, i.e., planar-embeddable, clock tree constructions with exactzero skew under either the linear or the Elmore delay model. Our method, called Planar-DME,consists of two parts. The first algorithm, called Linear-Planar-DME, guarantees an optimal planarzero-skew clock tree (ZST) under the linear delay model. The second algorithm, called ElmorePlanar-DME, uses the Linear-Planar-DME connection topology in constructing a low-cost

Andrew B. Kahng; Chung-wen Albert Tsao

1996-01-01

201

A DME Based Area Navigation Systems for GPS/WAAS Interference Mitigation In General Aviation Applications  

E-print Network

A DME Based Area Navigation Systems for GPS/WAAS Interference Mitigation In General Aviation Measuring Equipment (DME), to provide a redundant navigation system alongside GPS/WAAS during this phase out period. Specif- ically, a system that fuses a low-end DME receiver with low cost dead-reckoning sensors

Stanford University

202

Spin soliton dynamics and magnetic susceptibility of (DMe-DCNQI)2Li by ESR under pressure$  

E-print Network

Spin soliton dynamics and magnetic susceptibility of (DMe-DCNQI)2Li by ESR under pressure$ M-0198, Japan Abstract At ambient pressure, a 1/4 filled spin-Peierls system (DMe-DCNQI)2Li shows spin; Antiferromagnetic order 1. Introduction We have studied the electronic states of one-dimensional (1D) system of (DMe

Mizoguchi, Kenji

203

DME/TACAN Interference and its Mitigation in L5/E5 Bands  

E-print Network

DME/TACAN Interference and its Mitigation in L5/E5 Bands Grace Xingxin Gao Stanford University, CA, in particular, high power pulsed signals from Distance Measuring Equipment (DME) and Tactical Air Navigation GNSS Monitor System (SGMS) is used to investigate the DME/TACAN signal environment at Stanford, CA, USA

Stanford University

204

Containing a Difficult Target: Techniques for Mitigating DME Multipath to Alternative  

E-print Network

Containing a Difficult Target: Techniques for Mitigating DME Multipath to Alternative Position equipment (DME)/Tactical Air Navigation (TACAN) has been serving aviation for approximately 60 years. It has Systems (GNSS) will be the primary source of this capability, DME can have a vital role in the future

Stanford University

205

DME: Documentation Management Environment for Software Product Lines Tool Demo Proposal  

E-print Network

DME: Documentation Management Environment for Software Product Lines ­ Tool Demo Proposal Ha Duy of Singapore +65 65162863 stan@comp.nus.edu.sg Tool demo at: http://www.comp.nus.edu.sg/~stan/DME to a new context ­ often a slow, tedious, and error-prone process. Document Management Environment (DME

Jarzabek, Stan

206

Conversion of Biomass Syngas to DME Using a Microchannel Reactor  

SciTech Connect

The capability of a microchannel reactor for direct synthesis of dimethylether (DME) from biomass syngas was explored. The reactor was operated in conjunction with a hybrid catalyst system consisting of methanol synthesis and dehydration catalysts, and the influence of reaction parameters on syngas conversion was investigated. The activities of different dehydration catalysts were compared under DME synthesis conditions. Reaction temperature and pressure exhibited similar positive effects on DME formation. A catalytic stability test of the hybrid catalyst system was performed for 880 hours, during which CO conversion only decreased from 88% to 81%. In the microchannel reactor, the catalyst deactivation rate appeared to be much slower than in a tubular fixed-bed reactor tested for comparison. Test results also indicated that the dehydration reaction rate and the water depletion rate via a water-gas-shift reaction should be compatible in order to achieve high selectivity to DME. Using the microchannel reactor, it was possible to achieve a space time yield almost three times higher than commercially demonstrated performance results. A side-by-side comparison indicated that the heat removal capability of the microchannel reactor was at least six times greater than that of a commercial slurry reactor under similar reaction conditions.

Hu, Jianli; Wang, Yong; Cao, Chunshe; Elliott, Douglas C.; Stevens, Don J.; White, James F.

2005-03-01

207

UST\\/DME: a clock tree router for general skew constraints  

Microsoft Academic Search

In this paper, we propose new approaches for solving the useful-skew tree (UST) routing problem [17]: Clock routing subject to general skew constraints. The clock layout synthesis engine of our UST algorithms is based on the deferred-merge embedding (DME) paradigm for zero-skew tree [5; 1] and bounded-skew tree [8; 2] routings; hence, the names UST\\/DME and Greedy-UST\\/DME for our algorithms.

Chung-Wen Albert Tsao; Cheng-Kok Koh

2000-01-01

208

Liquid phase methanol and dimethyl ether synthesis from syngas  

Microsoft Academic Search

The Liquid Phase Methanol Synthesis (LPMeOHTM) process has been investigated in our laboratories since 1982The reaction chemistry of liquid phase methanol synthesis over commercial Cu\\/ZnO\\/Al2O3 catalysts, established for diverse feed gas conditions including H2-rich, CO-rich, CO2-rich, and CO-free environments, is predominantly based on the CO2 hydrogenation reaction and the forward water-gas shift reactionImportant aspects of the liquid phase methanol synthesis

Sunggyu Lee; Abhay Sardesai

2005-01-01

209

Performance and emission characteristics of an SI engine operated with DME blended LPG fuel  

Microsoft Academic Search

In this study, a spark ignition engine operated with DME blended LPG fuel was experimentally investigated. In particular, performance, emissions characteristics (including hydrocarbon, CO, and NOx emissions), and combustion stability of an SI engine fuelled with DME blended LPG fuel were examined at 1800 and 3600rpm.Results showed that stable engine operation was possible for a wide range of engine loads

Seokhwan Lee; Seungmook Oh; Young Choi

2009-01-01

210

Broadband Spectral Observation of a dMe Star Radio Flare  

E-print Network

Broadband Spectral Observation of a dMe Star Radio Flare M. G¨udel 1 , A.O.Benz 1 , T.S. Bastian 2 Laboratories Macclesfield, Cheshire SK 11 9DL, United Kingdom Summary A flare on the dMe star AD Leonis

Guedel, Manuel

211

Diesel emission improvements by the use of oxygenated DME\\/diesel blend fuels  

Microsoft Academic Search

A kind of oxygenate fuel, DME, has been proposed and tested for use with diesel fuel as a means of reducing exhaust emissions. The addition of DME to diesel fuel results in the decrease of the lower calorific value, aromatics fraction and kinematic viscosity of blend fuels. Simultaneously, cetane number, C\\/H ratio and oxygen content of the blends are enhanced,

Wang Ying; Zhou Longbao; Wang Hewu

2006-01-01

212

Imprinting of the MEA Polycomb Gene Is Controlled by Antagonism between MET1 Methyltransferase and DME Glycosylase  

Microsoft Academic Search

The MEA Polycomb gene is imprinted in the Arabidopsis endosperm. DME DNA glycosylase activates maternal MEA allele expression in the central cell of the female gametophyte, the progenitor of the endosperm. Maternal mutant dme or mea alleles result in seed abortion. We identified mutations that suppress dme seed abortion and found that they reside in the MET1 methyltransferase gene, which

Wenyan Xiao; Mary Gehring; Yeonhee Choi; Linda Margossian; Hong Pu; John J. Harada; Robert B. Goldberg; Roger I. Pennell; Robert L. Fischer

2003-01-01

213

The Radio Properties of the dMe Flare Star Proxima Centauri Institute of Astronomy & Astrophysics, Academia Sinica,  

E-print Network

The Radio Properties of the dMe Flare Star Proxima Centauri Jeremy Lim Institute of Astronomy--polarized and apparently narrowband flare at 20 cm, similar to those seen on other dMe flare stars. This flare was detected wavelength observations of other dMe flare stars. We show that the high mass--loss rate inferred by Mullan et

White, Stephen

214

H-bonded molecular interaction study on binary mixtures of mono alkyl ethers of ethylene glycol with different polar solvents by concentration dependent dielectric analysis  

Microsoft Academic Search

Static dielectric constant measurements on binary mixtures of the homologous series of mono alkyl ethers of ethylene glycol with six different characteristic polar solvents i.e. ethyl alcohol, ethylene glycol, glycerol, water, dimethyl formamide and dimethyl sulphoxide over the entire concentration range were carried out using precision LCR meter and a four terminal liquid dielectric test fixture at 1?MHz and 25°C.

R. J. Sengwa; Madhvi; Sonu Sankhla

2006-01-01

215

NOx Reduction on a Transition Metal-free ?-Al2O3 Catalyst Using Dimethylether (DME)  

SciTech Connect

NO2 and dimethylether (DME) adsorption as well as DME and NO2 coadsorption on a transition metal-free ?-alumina catalyst were investigated via in-situ transmission Fourier transform infrared spectroscopy (in-situ FTIR), residual gas analysis (RGA) and temperature programmed desorption (TPD) techniques. NO2 adsorption at room temperature leads to the formation of surface nitrates and nitrites. DME adsorption on the alumina surface at 300 K leads to molecularly adsorbed DME, molecularly adsorbed methanol and surface methoxides. Upon heating the DME-exposed alumina to 500-600 K the surface is dominated by methoxide groups. At higher temperatures methoxide groups are converted into formates. At T > 510 K formate decomposition takes place to form H2O(g) and CO(g). DME and NO2 coadsorption at 423 K do not indicate a significant reaction between DME and NO2. However, in similar experiments at 573 K, fast reaction occurs and the methoxides present at 573 K before the NO2 adsorption are converted into formates, simultaneously with the formation of isocyanates. Under these conditions, NCO can further be hydrolyzed into isocyanic acid or ammonia with the help of water which is generated during the formate formation, decomposition and/or NCO formation steps.

Ozensoy, Emrah; Herling, Darrell R.; Szanyi, Janos

2008-07-15

216

Acquisition and Tracking of GIOVE-A Broadcast L1/E5/E6 Signals and Analysis of DME/TACAN  

E-print Network

Acquisition and Tracking of GIOVE-A Broadcast L1/E5/E6 Signals and Analysis of DME Distance Measuring Equipment (DME) and Tactical Air Navigation (TACAN) systems. DME provides a distance-based transponder. DME and TACAN operate in four modes (X, Y, W and Z) between 960 MHz and 1215 MHz. This range

Stanford University

217

Poly(arylene ether)s containing pendent ethynyl groups  

NASA Technical Reports Server (NTRS)

Poly(arylene ether)s containing pendent ethynyl and substituted ethynyl groups and poly(arylene ether) copolymers containing pendent ethynyl and substituted ethynyl groups are readily prepared from bisphenols containing ethynyl and substituted ethynyl groups. The resulting polymers are cured up to 350.degree. C. to provide crosslinked poly(arylene ether)s with good solvent resistance, high strength and modulus.

Hergenrother, Paul M. (Inventor); Jensen, Brian J. (Inventor)

1996-01-01

218

Study of fuel consumption when introducing DME or ethanol into diesel engine  

Microsoft Academic Search

An investigation of the effect of DME or ethanol on fuel consumption is conducted in a four-stroke, one-cylinder, direct-injection diesel engine. DME or ethanol is first heated to pyrolyze and then the resultant product gas is introduced into air intake. Brake Specific Fuel Consumption (BSFC) can be reduced a lot, when emulsified fuel (diesel fuel emulsified with water) is fueled

Zhang Bo; Fu Weibiao; Gong Jingsong

2006-01-01

219

Long hydrocarbon chain ether diols and ether diacids that favorably alter lipid disorders in vivo.  

PubMed

Long hydrocarbon chain ethers with bis-terminal hydroxyl or carboxyl groups have been synthesized and evaluated for their potential to favorably alter lipid disorders including metabolic syndrome. Compounds were assessed for their effects on the de novo incorporation of radiolabeled acetate into lipids in primary cultures of rat hepatocytes as well as for their effects on lipid and glycemic variables in female obese Zucker fatty rats following 1 and 2 weeks of daily oral administration. The most active compounds were found to be symmetrical with four to five methylene groups separating the central ether functionality and the gem dimethyl or methyl/aryl substituents. Biological activity was found to be greatest for tetramethyl-substituted ether diols (e.g., 28 and 31), while bis(arylmethyl) derivatives (e.g., 10, 11, and 27), diethers (e.g., 49, 50, and 56), and diphenyl ethers (e.g., 35 and 36) were the least active. For the most biologically active compound 28, we observed as much as a 346% increase in serum HDL-cholesterol and a 71% reduction in serum triglycerides at the highest dose administered (100 mg/kg) after 2 weeks of treatment. For compound 31 we observed a 69% reduction in non-HDL-cholesterol, accompanied by a 131% increase in HDL-cholesterol and an 84% reduction in serum triglycerides under the same treatment conditions. PMID:15456261

Mueller, Ralf; Yang, Jing; Duan, Caiming; Pop, Emil; Zhang, Lian Hao; Huang, Tian-Bao; Denisenko, Anna; Denisko, Olga V; Oniciu, Daniela C; Bisgaier, Charles L; Pape, Michael E; Freiman, Catherine Delaney; Goetz, Brian; Cramer, Clay T; Hopson, Krista L; Dasseux, Jean-Louis H

2004-10-01

220

BroadBand Spectrum of dMe Star Radio Emission M Gudel and A. O. Benz  

E-print Network

Broad­Band Spectrum of dMe Star Radio Emission M G¨udel and A. O. Benz Institute of Astronomy, ETH, Z¨urich Running title: Spectrum of dMe Star Radio Emission Proofs and offprint requests: M. G.59.1 Journal: Letters #12; Broad­Band Spectrum of dMe Star Radio Emission M. G¨udel and A.O. Benz Institute

Guedel, Manuel

221

Crown ethers in graphene.  

PubMed

Crown ethers are at their most basic level rings constructed of oxygen atoms linked by two- or three-carbon chains. They have attracted attention for their ability to selectively incorporate various atoms or molecules within the cavity formed by the ring. However, crown ethers are typically highly flexible, frustrating efforts to rigidify them for many uses that demand higher binding affinity and selectivity. Here we present atomic-resolution images of the same basic structures of the original crown ethers embedded in graphene. This arrangement constrains the crown ethers to be rigid and planar. First-principles calculations show that the close similarity of the structures should also extend to their selectivity towards specific metal cations. Crown ethers in graphene offer a simple environment that can be systematically tested and modelled. Thus, we expect that our finding will introduce a new wave of investigations and applications of chemically functionalized graphene. PMID:25391367

Guo, Junjie; Lee, Jaekwang; Contescu, Cristian I; Gallego, Nidia C; Pantelides, Sokrates T; Pennycook, Stephen J; Moyer, Bruce A; Chisholm, Matthew F

2014-01-01

222

Crown ethers in graphene  

NASA Astrophysics Data System (ADS)

Crown ethers are at their most basic level rings constructed of oxygen atoms linked by two- or three-carbon chains. They have attracted attention for their ability to selectively incorporate various atoms or molecules within the cavity formed by the ring. However, crown ethers are typically highly flexible, frustrating efforts to rigidify them for many uses that demand higher binding affinity and selectivity. Here we present atomic-resolution images of the same basic structures of the original crown ethers embedded in graphene. This arrangement constrains the crown ethers to be rigid and planar. First-principles calculations show that the close similarity of the structures should also extend to their selectivity towards specific metal cations. Crown ethers in graphene offer a simple environment that can be systematically tested and modelled. Thus, we expect that our finding will introduce a new wave of investigations and applications of chemically functionalized graphene.

Guo, Junjie; Lee, Jaekwang; Contescu, Cristian I.; Gallego, Nidia C.; Pantelides, Sokrates T.; Pennycook, Stephen J.; Moyer, Bruce A.; Chisholm, Matthew F.

2014-11-01

223

Coordination geometries of solvated lanthanide(II) ions: Molecular structures of the cationic species [(DIME)[sub 3]Ln][sup 2+] (DIME = diethylene glycol dimethyl ether; Ln[sup 2+] = Sm, Yb), [(DIME)[sub 2]Yb(CH[sub 3]CN)[sub 2  

SciTech Connect

The first lanthanide(II) cationic species with coordination numbers 7,8, and 9 have been structurally characterized. Mercury amalgams of the elemental lanthanides (Ln(Hg) where Ln = Sm, Eu, Yb) cleanly reduce Mn[sub 2](CO)[sub 10] and Co[sub 2](CO)[sub 8] in polydentate ethers to [Mn(CO)[sub 5

White, J.P. III; Deng, H.; Boyd, E.P.; Gallucci, J.; Shore, S.G. (Ohio State Univ., Columbus, OH (United States))

1994-04-13

224

Poly(Arylene Ether)s Containing Pendent Ethynyl Groups  

NASA Technical Reports Server (NTRS)

Poly(arylene ether)s containing pendent ethynyl groups synthesized. Offer advantage over linear poly(arylene ether)s in upon heating, pendent ethynyl groups react to form cross-linked molecular structures exhibiting greater resistance to solvents and higher glass-transition temperatures and tensile moduli. Polymers useful as adhesives, moldings, films, and matrices of composite materials.

Hergenrother, Paul M.; Jensen, Brian J.

1995-01-01

225

Simultaneous determination of six hydrophilic ethers at trace levels using coconut charcoal adsorbent and gas chromatography/mass spectrometry.  

PubMed

The main objective of the following study was to determine the efficiency of a method that uses coconut charcoal as a solid-phase extraction (SPE) adsorbent in order to simultaneously detect six hydrophilic ether species in water in the low microgram-per-liter range. The applied method was validated for quantification of ethyl tert-butyl ether, 1,4-dioxane, ethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme) and tetraethylene glycol dimethyl ether (tetraglyme). SPE followed by gas chromatography/mass spectrometry of the extracts using the selected ion monitoring mode allowed for establishing low detection limits in the range of 0.007-0.018 ?g/L in ultrapure water and 0.004-0.020 ?g/L in environmental samples. Examination of the method accuracy and precision resulted in a recovery greater than 86.8 % for each compound with a relative standard deviation of less than 6.6 %. A stability study established a 5-day holding time for the unpreserved water samples and extracts. Finally, 27 samples obtained from surface water bodies in Germany were analyzed for the six hydrophilic ethers. Each analyte was detected in at least eight samples at concentrations reaching 2.0 ?g/L. The results of this study emphasize the advantage of the method to simultaneously determine six hydrophilic ether compounds. The outcome of the surface water analyses augments a concern about their frequent and significant presence in surface water bodies in Germany. PMID:23232954

Stepien, D K; Püttmann, W

2013-02-01

226

One- and two-electron-transfer reactions of (dpp-Bian)Sm(dme)3.  

PubMed

The reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-Bian) with an excess of samarium in 1,2-dimethoxyethane (dme) affords the Sm(II) complex (dpp-Bian)Sm(dme)(3) (1). The reaction of 1 with 0.5 mol equiv of 1,2-dibromostilbene proceeds with the formation of the dimeric Sm(III) complex [(dpp-Bian)SmBr(dme)](2) (2). Oxidation of both the metal and the dpp-Bian ligand takes place if 1 is reacted with equimolar amounts of 1,2-dibromostilbene or iodine, yielding the monomeric Sm(III) derivatives (dpp-Bian)SmBr(2)(dme) (3) and (dpp-Bian)SmI(2)(THF)(2) (4; THF = tetrahydrofuran), respectively. The reaction of 1 with 0.5 mol equiv of iodine followed by 0.5 mol equiv of tetramethylthiuram disulfide gives the Sm(III) complex (dpp-Bian)SmI[SC(S)NMe(2)](dme) (5). Compound 4 and tBuOK react with the formation of the iodine-bridged dimer [(dpp-Bian)SmI(OtBu)(THF)](2) (6). Complexes 1 and 2 have been characterized by (1)H NMR spectroscopy and complexes 2-6 by their molecular structures, which were determined by single-crystal X-ray diffraction. PMID:20151685

Fedushkin, Igor L; Maslova, Olga V; Hummert, Markus; Schumann, Herbert

2010-03-15

227

Functional and Expression Analysis of the Metal-Inducible dmeRF System from Rhizobium leguminosarum bv. viciae  

PubMed Central

A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metallidurans has been identified in the genome of Rhizobium leguminosarum UPM791. The R. leguminosarum dmeF gene is located downstream of an open reading frame (designated dmeR) encoding a protein homologous to the nickel- and cobalt-responsive transcriptional regulator RcnR from Escherichia coli. Analysis of gene expression showed that the R. leguminosarum dmeRF genes are organized as a transcriptional unit whose expression is strongly induced by nickel and cobalt ions, likely by alleviating the repressor activity of DmeR on dmeRF transcription. An R. leguminosarum dmeRF mutant strain displayed increased sensitivity to Co(II) and Ni(II), whereas no alterations of its resistance to Cd(II), Cu(II), or Zn(II) were observed. A decrease of symbiotic performance was observed when pea plants inoculated with an R. leguminosarum dmeRF deletion mutant strain were grown in the presence of high concentrations of nickel and cobalt. The same mutant induced significantly lower activity levels of NiFe hydrogenase in microaerobic cultures. These results indicate that the R. leguminosarum DmeRF system is a metal-responsive efflux mechanism acting as a key element for metal homeostasis in R. leguminosarum under free-living and symbiotic conditions. The presence of similar dmeRF gene clusters in other Rhizobiaceae suggests that the dmeRF system is a conserved mechanism for metal tolerance in legume endosymbiotic bacteria. PMID:23934501

Rubio-Sanz, L.; Prieto, R. I.; Imperial, J.; Brito, B.

2013-01-01

228

Dermatitis caused by dimethyl cyanocarbonimidodithioate.  

PubMed

Dimethyl cyanocarbonimidodithioate (CAS No. 10191-60-3) a raw material for cimetidine synthesis, is labelled as an irritant on its storage tank. There is no information available regarding the toxic effects of human exposure. We report a case of severe dermatitis clinically resembling erythema multiforme following an accidental exposure to dimethyl cyanocarbonimidodithioate in an occupational setting. A clerk sifted a handful of dimethyl cyanocarbonimidodithioate from an unlabelled bucket through his bare hands during an inspection prior to customs clearance. Five hours later, while he was washing his hands, pruritus, erythema and vesicles developed over the exposed area. The skin condition worsened within two weeks, extending to his whole body with generalized erythema and vesicles of various sizes. Some vesicles became confluent with ruptured bullae, resembling a second degree burn over 40% of the body. Elevation of the serum IgE (705 mu/mL, normal less than 300 mu/mL) and lymphocyte activation with an increased 3H-thymidine uptake by the patient's mononuclear cells suggested that this episode resulted from a cell-mediated allergic skin reaction. The skin lesions improved progressively after systemic steroid therapy for about two weeks. Dimethyl cyanocarbonimidodithioate is used as a raw material for cimetidine synthesis by some pharmaceutical manufacturers. Our experience suggests that a severe reaction similar to that caused by another H2-blocker, ranitidine and its intermediate may be caused by dimethyl cyanocarbonimidodithioate in occupational exposures. Systemic steroid administration is beneficial in treatment. PMID:1355116

Hung, D Z; Deng, J F; Tsai, W J

1992-01-01

229

Evidence for spin solitons and their dynamics in a spin-Peierls system ,,DMe-DCNQI...2Li Maki Hiraoka,1  

E-print Network

Evidence for spin solitons and their dynamics in a spin-Peierls system ,,DMe-DCNQI...2Li Maki-Peierls system (DMe-DCNQI)2Li has been studied with electron paramagnetic resonance EPR under hydrostatic-dicyanoquinone-diimine (DMe-DCNQI)2Li is a one-dimensional 1D -band sys- tem composed of 1D stacks of DMe-DCNQI molecules

Mizoguchi, Kenji

230

Molecular Structure of Dimethyl sulfide  

NSDL National Science Digital Library

Dimethyl sulfide results from malt, and from the short or weak boil of wort, slow chilling, or bacterial infection during beer-brewing processes. Also, dimethyl sulfide is found in large amounts in the oceans when the phytoplankton bloom releases it. It is used as a solvent for a variety of organic and inorganic materials. It is employed as a pre-sulfiding agent for catalysts in the refinery and petrochemical manufacturing process, and is also used in steel mill furnaces to control dusting.

2002-10-10

231

Spin Density Distribution and Electronic States in (DMe-DCNQI)2M, (M=Li, Ag, Cu) from High-Resolution Solid-State NMR  

E-print Network

Spin Density Distribution and Electronic States in (DMe-DCNQI)2M, (M=Li, Ag, Cu) from High determined the spin density distribution to investigate the electronic states of the (DMe-DCNQI)2M systems of the DMe-DCNQI molecule give the -electron spin distribution of the Li salt, which might correspond

Mizoguchi, Kenji

232

Spin density distribution and electronic states in ,,DMe-DCNQI...2M ,,M=Li,Ag,Cu... from high-resolution solid-state NMR  

E-print Network

Spin density distribution and electronic states in ,,DMe-DCNQI...2M ,,M=Li,Ag,Cu... from high to investigate the electronic states of the DMe-DCNQI 2M systems, where M is Li, Ag, and Cu. The Knight shift 15 N data. The Knight shift data at each atom of the DMe-DCNQI molecule give the -electron spin

Mizoguchi, Kenji

233

8 IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATEDCIRCUITS AND SYSTEMS, VOL. 15, NO. 1, JANUARY 1996 Planar-DME: A Single-Layer  

E-print Network

, JANUARY 1996 Planar-DME: A Single-Layer Zero-Skew Clock Tree Router Andrew B. Kahng, Member, ZEEE constructionswith exact zero skew under either the linear or the Elmore delay model. Our method, called Planar-DME, consists of two parts. The first algorithm, called Linear-Planar-DME, guarantees an optimal planar zero

Kahng, Andrew B.

234

Molecular Structure of Isopropyl ether  

NSDL National Science Digital Library

Diisopropyl ether has been used an extraction agent and as a solvent in paint thinners and stain removers. It has also been considered for use as an additive to raise the octane rating of gasoline. It is released into the environment through various waste streams associated with its laboratory use and the use and manufacture of removers. Diisopropyl ether is considered mildly toxic. Short term exposures produce anesthetic effects similar to ethyl ether and irritate the eyes, the skin, and the respiratory tract. Diisopropyl ether has been found many groundwater and surface water supplies. Many ethers are known to resist biodegradation and studies suggest that diisopropyl ether is resistant as well.

2002-10-01

235

Temperature dependence of the transfer coefficient for the hydrogen evolution reaction on the DME  

Microsoft Academic Search

The correlation between the transfer coefficient ? for the hydrogen evolution reaction with temperature T was studied at the dropping mercury electrode (DME). The transfer coefficient, corrected for the diffuse double layer, was found to be independent of temperature for LiCl and KCl as the supporting electrolytes. In the case of CsCl, a small residual dependence of ? on T

E. Kirowa-Eisner; M. Schwarz; M. Rosenblum; E. Gileadi

1995-01-01

236

http://informatics.medicine.dal.ca http://dme.medicine.dal.ca  

E-print Network

http://informatics.medicine.dal.ca http://dme.medicine.dal.ca www.medicine.dal.ca www at the level of Assistant Professor. Medical Informatics in the Faculty of Medicine was established in 1996 in the Medical Informatics Program, program development in the Faculty of Medicine and in the Health Informatics

Adl, Sina

237

Results of wire chamber ageing tests with CH4- and DME-based gas mixtures  

Microsoft Academic Search

Results are presented of ageing tests performed on single-wire proportional counters under controlled conditions. The rate of the detector ageing with methane mixtures has been found to be independent of the anode and cathode materials used, and also of the purity of the gas. The rate of ageing for DME mixtures, on the other hand, appears to depend on the

Roger Bouclier; M Capéans-Garrido; C. Garabatos; R. D. Heuer; M. Jeanrenaud; T. C. Meyer; Fabio Sauli; K. Silander

1994-01-01

238

Improving the accuracy of aircraft absolute altitude estimation using DME measurements  

Microsoft Academic Search

Recently an algorithm was developed by Lefas et at. (1988), for estimating the absolute altitude of civil aircraft using measurements from two sets of distance measuring equipment (DME). An interesting conclusion was that if the aeroplane deviates from the airlane marked by the two DMEs, secondary surveillance radar (SSR) measurements are also necessary, and this fact causes the degradation of

C. M. REKKAS; C. C. Lefas; N. J. KRIKELIS

1990-01-01

239

Fourier transform microwave spectrum of the CO-dimethyl sulfide complex  

NASA Astrophysics Data System (ADS)

The rotational spectrum of the CO-dimethyl sulfide (DMS) complex was measured in the frequency region from 4.8 up to 25 GHz by Fourier transform microwave spectroscopy. For the normal species 27 a-type and 57 c-type transitions were observed, while 16 and 8 c-type transitions were assigned for the species with 34S and 13C in the DMS moiety, respectively, in natural abundance. In addition, 7 a-type and 48 c-type transitions were assigned for the complex with the 13CO enriched species as a component and 9 a-type and 42 c-type transitions for the complex with enriched C 18O. No splitting was observed, which could be ascribed to the tunneling motion of the CO between two possible potential minima around DMS, while many transitions were split by the internal-rotation of the two methyl tops of the DMS unit. In cases where the K-type splitting was close to the methyl internal-rotation splitting, forbidden transitions were observed which apparently followed b-type selection rules. All of the observed transition frequencies for the normal species were analyzed simultaneously using a two-top internal-rotation and rotation Hamiltonian. The potential barrier height V3 to internal rotation of the methyl groups of the DMS was determined to be 745.5 (30) cm -1. The transition frequencies observed for all the isotopomers were analyzed using an asymmetric-rotor rotational Hamiltonian, to determine rotational and centrifugal distortion constants. The rs coordinates calculated from the observed rotational constants led to the conclusion that the CO moiety was located in a plane perpendicular to the skeletal plane of the DMS and bisecting its CSC angle. This structure of the CO-DMS is very much different from that of the CO-DME, in which the CO is located in the DME skeletal plane. The distance between the centers of gravity of the two moieties, Rcm, was calculated to be 3.789 Å for the CO-DMS, which is longer by only 0.11 Å than that in the CO-DME complex: 3.68 Å, in spite of the fact that the van der Waals radius of the S atom is much larger than that of the O atom. The small difference in Rcm is, in part, ascribed to the location of the CO relative to the DMS/DME. The more important reason is that the intermolecular bonding of the CO-DMS is stronger than that of CO-DME; by assuming a Lennard-Jones-type potential, the force constant of the van der Waals stretching mode and the dissociation energy were estimated to be 2.7 Nm -1 and 3.3 kJ mol -1, respectively, which were larger than those of the CO-DME: 1.4 Nm -1 and 1.6 kJ mol -1.

Sato, Akinori; Kawashima, Yoshiyuki; Hirota, Eizi

2010-10-01

240

Propenyl ether monomers for photopolymerization  

DOEpatents

Propenyl ether monomers of formula A(OCH{double_bond}CHCH{sub 3}){sub n} wherein n is an integer from one to six and A is selected from cyclic ethers, polyether and alkanes are disclosed. The monomers are readily polymerized in the presence of cationic photoinitiators, when exposed to actinic radiation, to form poly(propenyl ethers) that are useful for coatings, sealants, varnishes and adhesives. Compositions for preparing polymeric coatings comprising the compounds of the above formula together with particular cationic photoinitiators are also disclosed, as are processes for making the monomers from allyl halides and readily available alcohols. The process involves rearranging the resulting allyl ethers to propenyl ethers.

Crivello, J.V.

1996-10-22

241

Synthesis of oxygenate products for high volume fuels applications. Quarterly technical progress report, November 1, 1994--January 31, 1995  

SciTech Connect

The objective of this project is to develop high yield syntheses of oxygenate products that are liquid at room temperature using as starting materials dimethy ether (DME) or methanol. The identified products include: Dimethyl Carbonate (DMC), 1,1-Dimethoxyethane (DMOE), C{sub 2}{sup +} Alcohols/Ethers (C{sub 2}AE). The technical strategy is outlined below: (A) Synthesis of DMC via oxidative carbonylation of DME instead of methanol. Since this synthesis would not co-produce water as a byproduct, there is a potential for very high DME conversions in contrast to the low (ca 20%) conversions obtained in conventional plants. Technical emphasis will be placed on development of a supported copper catalyst with a capability for cleavage of DME into its chemisorbed organic moieties. (B) Synthesis of 1,1-dimethoxymethane (DMOE) from acetylene/CO/H{sub 2} process streams obtained from commercial methane oxidative pyrolysis processes. In the overall processing scheme the syngas would be converted to DME. The wet acetylene stream would be partially condensed to retain an equivalent of water and then condensed with DME to produce EMOE. (C) Direct conversion of DME or DME/methanol to ethanol/propanol or their methyl ethers. Under the influence of functionalized alcohol condensation catalysts developed exclusively at Amoco it should be possible to achieve direct conversion of dimethyl ether (or methanol) to ethanol/propanol and/or the methyl ethers of these alcohols. Although this reaction is not currently known, a combination of key catalyst components from identified systems should result in a DME conversion catalyst to C{sub 2}+ oxygenates. (D) Reaction of DME or acetylene with synthesis gas (CO/H{sub 2}) or methanol. A variety of catalysts will be tested for conversion of acetylene/CO/H{sub 2} or acetylene/methanol to propylene and conversion of DME/CO/H{sub 2} or DME/methanol to dimenthyoxymethane (DMM) and/or other oxygenates.

NONE

1995-03-08

242

DME\\/TACAN Interference and its Mitigation in L5\\/E5 Bands  

Microsoft Academic Search

The Galileo E5a\\/E5b signals and the GPS L5 signal lie within the Aeronautical Radionavigation Services (ARNS) band. They suffer interference from the services in this frequency band, in particular, high power pulsed signals from Distance Measuring Equipment (DME) and Tactical Air Navigation (TACAN) systems. The pulsed interference degrades received Signal to Interference and Noise Ratio (SINR), lowers the acquisition sensitivity

Grace Xingxin Gao

243

How is the Diamagnetic Effect (DME) Relevant to Stellar Surface Phenomena?  

E-print Network

The structure of stellar atmospheres can be modified if they include embedded diverging magnetic fields. This is due to the presence of speed filters. Here we examine some of the relevant effects through the numerical simulation of the motion of charged particles. We introduce the concept of "floating" particles and point out the relevance of the diamagnetic effet (DME) to the evolution of Maxwellian velocity distributions into Non-Maxwellian.

Netzach Farbiash; Raphael Steinitz

2005-06-05

244

How is the Diamagnetic Effect (DME) Relevant to Stellar Surface Phenomena?  

E-print Network

The structure of stellar atmospheres can be modified if they include embedded diverging magnetic fields. This is due to the presence of speed filters. Here we examine some of the relevant effects through the numerical simulation of the motion of charged particles. We introduce the concept of "floating" particles and point out the relevance of the diamagnetic effet (DME) to the evolution of Maxwellian velocity distributions into Non-Maxwellian.

Farbiash, N; Farbiash, Netzach; Steinitz, Raphael

2005-01-01

245

UST\\/DME: a clock tree router for general skew constraints  

Microsoft Academic Search

In this article, we propose new approaches for solving the useful-skew tree (UST) routing problem [Xi and Dai 1997]: clock routing subject to general skew constraints. The clock layout synthesis engine of our UST algorithms is based on the deferred-merge embedding (DME) paradigm for the zero-skew tree (ZST) [Edahiro 1992; Chao et al. 1992] and bounded-skew tree (BST) [Cong and

Chung-wen Albert Tsao; Cheng-kok Koh

2002-01-01

246

Poly(ethylenglycol)dimethylether-lithium bis(trifluoromethanesulfonyl)imide, PEG500DME-LiTFSI, as high viscosity electrolyte for lithium ion batteries  

NASA Astrophysics Data System (ADS)

In this paper we report a poly(ethylenglycol)dimethylether-lithium bis(trifluoromethanesulfonyl) imide (PEG500DME-LiTFSI) as high viscosity, safe electrolyte for lithium ion batteries. The high molecular weight of the end-capped ether solvent is reflected as low vapor pressure and excellent thermal stability of the electrolyte, as demonstrated by thermogravimetry, this resulting in remarkable safety content. The electrochemical impedance spectroscopy study of the electrolyte demonstrates a Li-transference number of 0.48, a conductivity of the order of 10-3 S cm-1, and a high interphase stability with the lithium metal, the linear sweep voltammetry indicates an electrochemical stability window extending up to 4.8 V vs. Li/Li+. Furthermore, promising electrochemical performances in terms of reversibility, cycling stability and low charge-discharge polarization are observed using the electrolyte in lithium and in lithium ion batteries using lithium cobalt oxide (LCO) as cathode and titanium dioxide (TiO2) as anode. Hence, this electrolyte is a promising candidate for applications in safe, high performance lithium ion batteries.

Bernhard, Rebecca; Latini, Alessandro; Panero, Stefania; Scrosati, Bruno; Hassoun, Jusef

2013-03-01

247

Experimental investigation on flame pattern formations of DME-air mixtures in a radial microchannel  

SciTech Connect

Flame pattern formations of premixed DME-air mixture in a heated radial channel with a gap distance of 2.5 mm were experimentally investigated. The DME-air mixture was introduced into the radial channel through a delivery tube which connected with the center of the top disk. With an image-intensified high-speed video camera, rich flame pattern formations were identified in this configuration. Regime diagram of all these flame patterns was drawn based on the experimental findings in the equivalence ratio range of 0.6-2.0 and inlet velocity range of 1.0-5.0 m/s. Compared with our previous study on premixed methane-air flames, there are several distinct characteristics for the present study. First, Pelton-wheel-like rotary flames and traveling flames with kink-like structures were observed for the first time. Second, in most cases, flames can be stabilized near the inlet port of the channel, exhibiting a conical or cup-like shape, while the conventional circular flame was only observed under limited conditions. Thirdly, an oscillating flame phenomenon occurred under certain conditions. During the oscillation process, a target appearance was seen at some instance. These pattern formation characteristics are considered to be associated with the low-temperature oxidation of DME. (author)

Fan, Aiwu [School of Energy and Power Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan (China); Institute of Fluid Science, Tohoku University, Aoba-ku, Sendai (Japan); Maruta, Kaoru; Nakamura, Hisashi [Institute of Fluid Science, Tohoku University, Aoba-ku, Sendai (Japan); Kumar, Sudarshan [Aerospace Engineering Department, IIT Bombay, Powai, Mumbai (India); Liu, Wei [School of Energy and Power Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan (China)

2010-09-15

248

Ether and hydrocarbon production  

SciTech Connect

This patent describes a continuous process for converting lower aliphatic alkanol and olefinic hydrocarbon to alkyl tertiary-alkyl ethers and C{sub 5} + gasoline boiling range hydrocarbons. It comprises contacting alkanol and a light olefinic hydrocarbon stream rich in isobutylene and other C{sub 4} isomeric hydrocarbons under iso-olefin etherification conditions in an etherification reaction zone containing acid etherification catalyst; separating etherification effluent to recover a light stream comprising unreacted alkanol and light olefinic hydrocarbon and a liquid product stream containing alkyl tertiary-butyl ether; and contacting the light stream with acidic, medium pore metallosilicate catalyst under alkanol and hydrocarbon conversion conditions whereby C{sub 5} + gasoline boiling range hydrocarbons are produced.

Harandi, M.N.; Owen, H.

1991-03-19

249

40 CFR 721.333 - Dimethyl alkylamine salt (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Dimethyl alkylamine salt (generic). 721.333 Section 721...Substances § 721.333 Dimethyl alkylamine salt (generic). (a) Chemical substance...identified generically as a Dimethyl alkylamine salt (PMNs P-99-0368 and...

2012-07-01

250

40 CFR 721.333 - Dimethyl alkylamine salt (generic).  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Dimethyl alkylamine salt (generic). 721.333 Section 721...Substances § 721.333 Dimethyl alkylamine salt (generic). (a) Chemical substance...identified generically as a Dimethyl alkylamine salt (PMNs P-99-0368 and...

2014-07-01

251

40 CFR 721.333 - Dimethyl alkylamine salt (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Dimethyl alkylamine salt (generic). 721.333 Section 721...Substances § 721.333 Dimethyl alkylamine salt (generic). (a) Chemical substance...identified generically as a Dimethyl alkylamine salt (PMNs P-99-0368 and...

2010-07-01

252

40 CFR 721.333 - Dimethyl alkylamine salt (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Dimethyl alkylamine salt (generic). 721.333 Section 721...Substances § 721.333 Dimethyl alkylamine salt (generic). (a) Chemical substance...identified generically as a Dimethyl alkylamine salt (PMNs P-99-0368 and...

2011-07-01

253

Searching for solvent cavities via electron photodetachment: The ultrafast charge-transfer-to-solvent dynamics of sodide in a series of ether solvents  

SciTech Connect

It was recently predicted by simulations and confirmed by neutron diffraction experiments that the structure of liquid tetrahydrofuran (THF) contains cavities. The cavities can be quite large and have a net positive electrostatic potential, so they can serve as pre-existing traps for excess electrons created via photodetachment from various solutes. In this paper, we use electron photodetachment via charge-transfer-to-solvent (CTTS) excitation of sodide (Na{sup -}) to probe for the presence of pre-existing cavities in a series of ether solvents: THF, diethyl ether, 1,2-dimethoxyethane (DME), and diglyme (DG). We find that electrons photodetached from sodide appear after a time delay with their equilibrium spectrum in all of these solvents, suggesting that the entire series of ethers contains pre-existing solvent cavities. We then use the variation in electron recombination dynamics with CTTS excitation wavelength to probe the nature of the cavities in the different ethers. We find that the cavities that form the deepest electron traps turn on at about the same energy in all four ether solvents investigated, but that the density of cavities is lower in DG and DME than in THF. We also examine the dynamics of the neutral sodium species that remains following CTTS photodetachment of an electron from sodide. We find that the reaction of the initially created gas-phase-like Na atom to form a (Na{sup +},e{sup -}) tight-contact pair occurs at essentially the same rate in all four ether solvents, indicating that only local solvent motions and not bulk solvent rearrangements are what is responsible for driving the partial ejection of the remaining Na valence electron.

Larsen, Molly C.; Schwartz, Benjamin J. [Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095-1569 (United States)

2009-10-21

254

Molecular Structure of Ethyl ether  

NSDL National Science Digital Library

Divinyl ether is a highly volatile colorless liquid. This compound can be synthesized from dichloroethyl ether by treatment with alkali. It is used by medical practitioners as an inhalation anesthetic for short operations. This chemical is also used to synthesize co-polymers for clear plastic bottles. A word of caution, ethers are known to form peroxides, which are can potentially lead to an explosion. Therefore, one should periodically test for peroxides using a test such as the potassium iodide detection method.

2002-10-01

255

STANDARD OPERATING PROCEDURE DIMETHYL SULFOXIDE (DMSO)  

E-print Network

12.1 STANDARD OPERATING PROCEDURE for DIMETHYL SULFOXIDE (DMSO) Location(s): ___________________________________________________ Chemical(s): Dimethyl Sulfoxide (DMSO) Specific Hazards: Combustible liquid, transport across skin barrier as nitrile products are easily degraded by DMSO). Extended Contact: butyl rubber gloves Lab coat __X

Pawlowski, Wojtek

256

X-RAY FLARING ON THE dMe STAR, ROSS 154 B. J. Wargelin, V. L. Kashyap, J. J. Drake, D. GarcIia-Alvarez,1  

E-print Network

X-RAY FLARING ON THE dMe STAR, ROSS 154 B. J. Wargelin, V. L. Kashyap, J. J. Drake, D. Garc to be more active than FYG dwarfs, with ap- proximately half of the former (the dMe stars) showing emission as the Sun's, dMe stars have X-ray emission that is usually comparable to or larger than the solar X

Wargelin, Bradford J.

257

Quasi-one dimensional diffusive motion of spin solitons in the spin-Peierls state of (DMe-DCNQI)2Li  

E-print Network

Quasi-one dimensional diffusive motion of spin solitons in the spin-Peierls state of (DMe-DCNQI)2Li, Saitama, 351-0198, Japan Abstract (DMe-DCNQI)2Li is a 1/4 filled spin-Peierls (SP) system with the SP dependence of Tsp. It is due to a simple quasi-1-D electronic structure of (DMe-DCNQI)2Li, even under high

Mizoguchi, Kenji

258

Poly(arylene ether)s That Resist Atomic Oxygen  

NASA Technical Reports Server (NTRS)

Novel poly(arylene ether)s containing phosphine oxide (PAEPO's) made via aromatic nucleophilic displacement reactions of activated aromatic dihalides (or, in some cases, activated aromatic dinitro compounds) with new bisphenol monomers containing phosphine oxide. Exhibited favorable combination of physical and mechanical properties and resistance to monatomic oxygen in oxygen plasma environment. Useful as adhesives, coatings, films, membranes, moldings, and composite matrices.

Connell, John W.; Hergenrother, Paul; Smith, Joseph G., Jr.

1994-01-01

259

Allene ether Nazarov cyclization.  

PubMed

The ease of synthesis and the exceptional reactivity of alkoxyallenes has led to their use in a large number of highly diverse applications. This Report describes their use in various versions of the allene ether Nazarov cyclization. Following a brief introduction to the Nazarov cyclization (Section 1), the oxidative cyclization of vinyl alkoxyallenes is discussed first (Section 2). Nazarov cyclizations of ?-alkoxyallenyl vinyl ketones and of ?-alkoxyallenyl vinyl tertiary carbinols are covered (Section 3). The discovery and the subsequent rational design of acetals that serve as chiral auxiliaries on the allene in highly enantioselective Nazarov cyclizations is explained (Section 4). Interrupted Nazarov cyclizations of alkoxyallenes that are generated in situ from the isomerization of propargyl ethers on solid supports are discussed, including the evolution of a highly diastereoselective, chiral auxiliary controlled version of the reaction. Some applications of the methodology to natural products total synthesis have been included so as to provide the reader with benchmarks with which to judge the utility of the methodology. PMID:24196585

Tius, Marcus A

2014-05-01

260

A new mechanism for the aerobic catabolism of dimethyl sulfide.  

PubMed Central

Aerobic degradation of dimethyl sulfide (DMS), previously described for thiobacilli and hyphomicrobia, involves catabolism to sulfide via methanethiol (CH3SH). Methyl groups are sequentially eliminated as HCHO by incorporation of O2 catalyzed by DMS monooxygenase and methanethiol oxidase. H2O2 formed during CH3SH oxidation is destroyed by catalase. We recently isolated Thiobacillus strain ASN-1, which grows either aerobically or anaerobically with denitrification on DMS. Comparative experiments with Thiobacillus thioparus T5, which grows only aerobically on DMS, indicate a novel mechanism for aerobic DMS catabolism by Thiobacillus strain ASN-1. Evidence that both organisms initially attacked the methyl group, rather than the sulfur atom, in DMS was their conversion of ethyl methyl sulfide to ethanethiol. HCHO transiently accumulated during the aerobic use of DMS by T. thioparus but not with Thiobacillus strain ASN-1. Catalase levels in cells grown aerobically on DMS were about 100-fold lower in Thiobacillus strain ASN-1 than in T. thioparus T5, suggesting the absence of H2O2 formation during DMS catabolism. Also, aerobic growth of T. thioparus T5 on DMS was blocked by the catalase inhibitor 3-amino-1,2,4-triazole whereas that of Thiobacillus strain ASN-1 was not. Methyl butyl ether, but not CHCl3, blocked DMS catabolism by T. thioparus T5, presumably by inhibiting DMS monooxygenase and perhaps methanethiol oxidase. In contrast, DMS metabolism by Thiobacillus strain ASN-1 was unaffected by methyl butyl ether but inhibited by CHCl3. DMS catabolism by Thiobacillus strain ASN-1 probably involves methyl transfer to a cobalamin carrier and subsequent oxidation as folate-bound intermediates. PMID:8285684

Visscher, P T; Taylor, B F

1993-01-01

261

Oral Minocycline for the Treatment of Diabetic Macular Edema (DME): Results of a Phase I/II Clinical Study  

PubMed Central

Purpose. Inflammation contributes significantly to the pathogenesis of diabetic macular edema (DME). In particular, retinal microglia demonstrate increased activation and aggregation in areas of DME. Study authors investigated the safety and potential efficacy of oral minocycline, a drug capable of inhibiting microglial activation, in the treatment of DME. Methods. A single-center, prospective, open-label phase I/II clinical trial enrolled five participants with fovea-involving DME who received oral minocycline 100 mg twice daily for 6 months. Main outcome measurements included best-corrected visual acuity (BCVA), central retinal subfield thickness (CST), and central macular volume using spectral domain optical coherence tomography (SD-OCT) and late leakage on fluorescein angiography (FA). Results. Findings indicated that the study drug was well tolerated and not associated with significant safety issues. In study eyes, mean BCVA improved continuously from baseline at 1, 2, 4, and 6 months by +1.0, +4.0, +4.0, and +5.8 letters, respectively, while mean retinal thickness (CST) on OCT decreased by ?2.9%, ?5.7%, ?13.9, and ?8.1% for the same time points. At month 6, mean area of late leakage on FA decreased by ?34.4% in study eyes. Mean changes in contralateral fellow eyes also demonstrated similar trends. Improvements in outcome measures were not correlated with concurrent changes in systemic factors. Conclusions. In this pilot proof-of-concept study of DME, minocycline as primary treatment was associated with improved visual function, central macular edema, and vascular leakage, comparing favorably with historical controls from previous studies. Microglial inhibition with oral minocycline may be a promising therapeutic strategy targeting the inflammatory etiology of DME. (ClinicalTrials.gov number, NCT01120899.) PMID:22589436

Cukras, Catherine A.; Petrou, Philip; Chew, Emily Y.; Meyerle, Catherine B.; Wong, Wai T.

2012-01-01

262

amine methanol, ether . Amine amine CO2  

E-print Network

IP [2012] 7 C O 2 (CO2) . CO2 amine methanol, ether . Amine amine CO2 CO2 .Amine CO2 (functional group) amine amine+ +promoter .Amine CO2 CO2 . . , methanol ether methanol, ether promoter CO2 CO2 H2S, COS CO2 . Methanol rectisol process, di-methylene ether polypropylene glycol selexol (-30oC) . CO2

Hong, Deog Ki

263

Synthesis and properties of novel sulfonated poly(arylene ether sulfone) ionomers for vanadium redox flow battery  

Microsoft Academic Search

Novel sulfonated poly(arylene ether sulfone)s with electron-withdrawing sulfone groups in each repeat unit were synthesized via step polymerization followed by post-sulfonation using chlorosulfonic acid. The sulfonation degree can be readily controlled by adjusting the feed ratio of the repeat unit of polymers to chlorosulfonic acid. The synthesized polymers are soluble in common aprotic solvents such as dimethyl sulfoxide, N,N?-dimethylacetamide and

Dongyang Chen; Shuanjin Wang; Min Xiao; Yuezhong Meng

2010-01-01

264

21 CFR 172.133 - Dimethyl dicarbonate.  

Code of Federal Regulations, 2013 CFR

...than 99.8 percent as determined by the following titration method: principles of method Dimethyl dicarbonate...eg., Metrohm burette) Stirrer Device for potentiometric titration Reference electrode Glass electrode...

2013-04-01

265

21 CFR 172.133 - Dimethyl dicarbonate.  

Code of Federal Regulations, 2011 CFR

...than 99.8 percent as determined by the following titration method: principles of method Dimethyl dicarbonate...eg., Metrohm burette) Stirrer Device for potentiometric titration Reference electrode Glass electrode...

2011-04-01

266

21 CFR 172.133 - Dimethyl dicarbonate.  

Code of Federal Regulations, 2012 CFR

...than 99.8 percent as determined by the following titration method: principles of method Dimethyl dicarbonate...eg., Metrohm burette) Stirrer Device for potentiometric titration Reference electrode Glass electrode...

2012-04-01

267

21 CFR 172.133 - Dimethyl dicarbonate.  

Code of Federal Regulations, 2014 CFR

...than 99.8 percent as determined by the following titration method: principles of method Dimethyl dicarbonate...eg., Metrohm burette) Stirrer Device for potentiometric titration Reference electrode Glass electrode...

2014-04-01

268

21 CFR 172.133 - Dimethyl dicarbonate.  

Code of Federal Regulations, 2010 CFR

...than 99.8 percent as determined by the following titration method: principles of method Dimethyl dicarbonate...eg., Metrohm burette) Stirrer Device for potentiometric titration Reference electrode Glass electrode...

2010-04-01

269

The neuropeptide FF analogue, 1DME, enhances in vivo met-enkephalin release from the rat spinal cord  

Microsoft Academic Search

Behavioural studies have suggested that endogenous opioids mediate the antinociceptive action of neuropeptide FF (FLFQPQRF–NH2) at the spinal level in the rat. This hypothesis was directly assessed by investigating the effects of a NPFF analogue, 1DMe ([D-Tyr1,(NMe)Phe3]NPFF), on the spinal outflow of met-enkephalin-like material (MELM) in halothane-anaesthetised rats. Intrathecal infusion (0.1 ml\\/min) of 1DMe (0.1 ?M–0.1 mM, for 45 min)

S Ballet; A Mauborgne; C Gouardères; A. S Bourgoin; J-M Zajac; M Hamon; F Cesselin

1999-01-01

270

VLBI observations of two single dMe stars: spatial resolution and astrometry  

E-print Network

We report on 3.6 cm VLA and VLBA observations of YZ CMi and AD Leo, two nearby dMe stars. We resolve YZ CMi and can fit a circular symmetrical gaussian component of FWHP of 0.98 +/-0.2 mas, corresponding to an extent of the corona above the photosphere of 1.77 x 10^{10} +/-8.8 x 10^{9} cm or 0.7 +/-0.3 Rstar (Rstar refers to the photospheric radius). We obtain an estimate of the brightness temperature of 7.3 x 10^{7} K, which is consistent with that expected from gyrosynchrotron emission. For AD Leo the emitting region is unresolved. We therefore set a conservative upper limit to its diameter of 1.8 times the photosphere diameter, which leads to an extent of the corona above the photosphere of dMe stars with measured sizes with the Sun and conclude that these active stars have much more extended coronal radio emission than the Sun. The VLBA position of YZ CMi has been found to differ by 32 mas from the positions calculated from the Hipparcos catalogue. The discrepancy is caused by large errors in the listed proper motion. An improved value is given.

M. R. Pestalozzi; A. O. Benz; J. E. Conway; M. Guedel

1999-12-08

271

VLBI observations of two single dMe stars spatial resolution and astrometry  

E-print Network

We report on 3.6 cm VLA and VLBA observations of YZ CMi and AD Leo, two nearby dMe stars. We resolve YZ CMi and can fit a circular symmetrical gaussian component of FWHP of 0.98 +/-0.2 mas, corresponding to an extent of the corona above the photosphere of 1.77 x 10^{10} +/-8.8 x 10^{9} cm or 0.7 +/-0.3 Rstar (Rstar refers to the photospheric radius). We obtain an estimate of the brightness temperature of 7.3 x 10^{7} K, which is consistent with that expected from gyrosynchrotron emission. For AD Leo the emitting region is unresolved. We therefore set a conservative upper limit to its diameter of 1.8 times the photosphere diameter, which leads to an extent of the corona above the photosphere of dMe stars with measured sizes with the Sun and conclude that these active stars have much more extended coronal radio emission than the Sun. The VLBA position of YZ CMi has been found to differ by 32 mas from the positions calculated from the Hipparcos...

Pestalozzi, M R; Conway, J E; Güdel, M

2000-01-01

272

Cis-METHYL Vinyl Ether: the Rotational Spectrum up to 600 GHz  

NASA Astrophysics Data System (ADS)

Astronomical observation of dimethyl ether, methyl ethyl ether places the methyl vinyl ether among the species of potential interstellar relevance. The millimeter and submillimeter-wave transitions pertaining to the vibrational ground state and the first excited states of the methoxy, ?24, and methyl, ?23, torsional modes and the in-plane bending mode, ?16, of the cis-methyl vinyl ether have been measured and analyzed in the frequency region from 50 to 600 GHz. A significant Fermi-type and Coriolis interactions between the v24=1 and v23=1 states have been observed and the rotational spectra were analyzed using an effective two-state Hamiltonian explicitly involving corresponding coupling operators. A sets of spectroscopic constants for the ground state as well as for all three excited states reproducing the observed spectrum within the experimental uncertainty provide sufficiently precise information for the astronomical search for methyl vinyl ether. Z. Peeters, S. D. Rodgers, S. B. Charnley, L. Schriver-Mazzuoli, A. Schriver, J. V. Keane, and P. Ehrenfreund, Astron. & Astrophys. 2006, 445, 197. G. W. Fuchs, U. Fuchs, T. F. Giesen, F. Wyrowski, Astron. & Astrophys. 2005, 444, 521. B. E. Turner, A. J. Apponi, Astrophys. J. Lett. 2001, 561, 207.

Kolesniková, Lucie; Daly, Adam M.; Alonso, José L.

2014-06-01

273

Biodegradation of gasoline ether oxygenates.  

PubMed

Ether oxygenates such as methyl tertiary butyl ether (MTBE) are added to gasoline to improve fuel combustion and decrease exhaust emissions. Ether oxygenates and their tertiary alcohol metabolites are now an important group of groundwater pollutants. This review highlights recent advances in our understanding of the microorganisms, enzymes and pathways involved in both the aerobic and anaerobic biodegradation of these compounds. This review also aims to illustrate how these microbiological and biochemical studies have guided, and have helped refine, molecular and stable isotope-based analytical approaches that are increasingly being used to detect and quantify biodegradation of these compounds in contaminated environments. PMID:23116604

Hyman, Michael

2013-06-01

274

Einstein's Thoughts on the Ether  

NSDL National Science Digital Library

Do light waves travel through the ether like waves on a lake travel through water? In this video segment adapted from NOVA, a young Albert Einstein grapples with this question while examining the speed of light.

WGBH Educational Foundation

2004-02-20

275

Vinyl Ether for Dental Anæsthesia  

PubMed Central

Properties: Vinyl ether, CH2:CH2:O:CH2:CH2, a volatile liquid. Lipoidsoluble but highly inflammable. Toxicity.—Has little effect on liver function; overdoses produce respiratory paralysis, but not cardiac paralysis. Indications.—Replaces ethyl chloride for short operations, and can be added to gas and oxygen instead of ether or chloroform. Is a safe and portable anæsthetic for the general practitioner. Administration.—Open method convenient, but not very satisfactory, a closed method produces better anæsthesia. Special inhaler described and illustrated. Vinyl ether is obtainable in ampoules of 3 c.c., a sufficient quantity for the average case. Induction is rapid; signs of anæsthesia described. Patient's colour remains excellent. Apparatus required when vinyl ether is to be added to gas-and-oxygen. ImagesFig. 1Fig. 2Fig. 3 PMID:19991136

Goldman, Victor

1937-01-01

276

Imide/arylene ether copolymers  

NASA Technical Reports Server (NTRS)

Imide/arylene ether block copolymers are prepared by reacting anhydride terminated poly(amic acids) with amine terminated poly(arylene ethers) in polar aprotic solvents and by chemically or thermally cyclodehydrating the resulting intermediate poly(amic acids). The resulting block copolymers have one glass transition temperature or two, depending upon the particular structure and/or the compatibility of the block units. Most of these block copolymers form tough, solvent resistant films with high tensile properties.

Jensen, Brian J. (inventor); Hergenrother, Paul M. (inventor); Bass, Robert G. (inventor)

1992-01-01

277

Ether lipids based on the glyceryl ether skeleton: Present state, future potential  

Microsoft Academic Search

Lipids from natural sources consist mainly of saponifiable substances, such as glycerides, along with some unsaponifiable\\u000a lipids, some of which are ether lipids. Typical ether lipids are monoalkyl ethers of glycerin, also called alkyl\\/alkenyl glyceryl\\u000a ethers. Alkyl\\/alkenyl glyceryl ethers have also been reported in marine organisms and in human feces. Several chemical syntheses\\u000a of such ether lipids have been reported.

Kouichi Urata; Naotake Takaishi

1996-01-01

278

Sulfonimide-containing poly(arylene ether)s and poly(arylene ether sulfone)s, methods for producing the same, and uses thereof  

DOEpatents

The present invention is directed to sulfonimide-containing polymers, specifically sulfonimide-containing poly(arylene ether)s and sulfonimide-containing poly(arylene ether sulfone)s, and processes for making the sulfonimide-containing poly(arylene ether)s and sulfonimide-containing poly(arylene ether sulfone)s, for use conductive membranes and fuel cells.

Hofmann, Michael A.

2006-11-14

279

Alternatives to Petroleum Diesel Fuel  

Microsoft Academic Search

There are four alternative fuels that can be relatively easily used in conventional compression ignition engines (CIE): vegetable oil, biodiesel, Fischer-Tropsch (F-T) diesel, and dimethyl ether (DME). Vegetable oils, such as palm, soybean, sunflower, peanut, and olive, can be used as alternative fuels for diesel engines. Both F-T and DME can be manufactured from natural gas and are therefore not

A. Demirbas

2007-01-01

280

Space, Time, Ether, and Kant  

NASA Astrophysics Data System (ADS)

This dissertation focused on Kant's conception of physical matter in the Opus postumum. In this work, Kant postulates the existence of an ether which fills the whole of space and time with its moving forces. Kant's arguments for the existence of an ether in the so-called Ubergang have been acutely criticized by commentators. Guyer, for instance, thinks that Kant pushes the technique of transcendental deduction too far in trying to deduce the empirical ether. In defense of Kant, I held that it is not the actual existence of the empirical ether, but the concept of the ether as a space-time filler that is subject to a transcendental deduction. I suggested that Kant is doing three things in the Ubergang: First, he deduces the pure concept of a space-time filler as a conceptual hybrid of the transcendental object and permanent substance to replace the category of substance in the Critique. Then he tries to prove the existence of such a space-time filler as a reworking of the First Analogy. Finally, he takes into consideration the empirical determinations of the ether by adding the concept of moving forces to the space -time filler. In reconstructing Kant's proofs, I pointed out that Kant is absolutely committed to the impossibility of action-at-a-distance. If we add this new principle of no-action-at-a-distance to the Third Analogy, the existence of a space-time filler follows. I argued with textual evidence that Kant's conception of ether satisfies the basic structure of a field: (1) the ether is a material continuum; (2) a physical quantity is definable on each point in the continuum; and (3) the ether provides a medium to support the continuous transmission of action. The thrust of Kant's conception of ether is to provide a holistic ontology for the transition to physics, which can best be understood from a field-theoretical point of view. This is the main thesis I attempted to establish in this dissertation.

Wong, Wing-Chun Godwin

281

Petrochemicals from coal-derived syngas  

SciTech Connect

The development of the Liquid Phase Dimethyl Ether (LPDME) process has established a means to effectively convert CO-rich syngas to dimethyl ether (DME) in a mechanically agitated slurry reactor. By operating in a dual catalyst mode, in-situ produced methanol may be converted to DME, thereby alleviating the chemical equilibrium limitation imposed on the methanol synthesis reaction. As a result, higher syngas conversions and methyl productivities are seen over methanol synthesis alone. This effective route to DME production over methanol has led to the development of conversion technologies based on a DME feedstock. Oxygenates, in particular, ethers and their precursors, are very important as potential clean fuel additives and have been postulated through vinylation/hydrogenation and oxidative coupling reactions. Specialty chemicals such as methyl acetate and acetic acid have widescale industrial importance in the conversion to ethanol from a non-agricultural feedstock. Vapor phase oxidative dimerization of DME over tin based catalysts produced precursors of ethylene glycol. Finally, DME has been extensively used as a feedstock for hydrocarbon synthesis including olefins, paraffins and gasoline range hydrocarbons, over zeolite based catalysts with a 46% increase in product selectivity over methanol. The efficient production of DME in the liquid phase has given it widescale industrial significance as a potential replacement for methanol and as a keystone for more important petrochemicals.

Sardesai, A.; Lee, S. [Univ. of Akron, OH (United States). Dept. of Chemical Engineering

1996-12-31

282

Catalytic Consequences of Acid Strength in the Conversion of Methanol to Dimethyl Ether  

SciTech Connect

The effects of acid identity on CH{sub 3}OH dehydration are examined here using density functional theory (DFT) estimates of acid strength (as deprotonation energies, DPE) and reaction energies, combined with rate data on Keggin polyoxometalate (POM) clusters and zeolite H-BEA. Measured first-order (k{sub mono}) and zero-order (k{sub dimer}) CH3OH dehydration rate constants depend exponentially on DPE for POM clusters; the value of k{sub mono} depends more strongly on DPE than k{sub dimer} does. The chemical significance of these rate parameters and the basis for their dependences on acid strength were established by using DFT to estimate the energies of intermediates and transition states involved in elementary steps that are consistent with measured rate equations. We conclude from this treatment that CH{sub 3}OH dehydration proceeds via direct reactions of co-adsorbed CH{sub 3}OH molecules for relevant solid acids and reaction conditions. Methyl cations formed at ion-pair transition states in these direct routes are solvated by H{sub 2}O and CH{sub 3}OH more effectively than those in alternate sequential routes involving methoxide formation and subsequent reaction with CH{sub 3}OH. The stability of ion-pairs, prevalent as intermediates and transition states on solid acids, depends sensitively on DPE because of concomitant correlations between the stability of the conjugate anionic cluster and DPE. The chemical interpretation of k{sub mono} and k{sub dimer} from mechanism-based rate equations, together with thermochemical cycles of their respective transition state formations, show that similar charge distributions in the intermediate and transition state involved in k{sub dimer} cause its weaker dependence on DPE. Values of k{sub mono} involve uncharged reactants and the same ion-pair transition state as k{sub dimer}; these species sense acid strength differently and cause the larger effects of DPE on k{sub mono}. Confinement effects in H-BEA affect the value of k{sub mono} because the different sizes and number of molecules in reactants and transition states selectively stabilize the latter; however, they do not influence k{sub dimer}, for which reactants and transition states of similar size sense spatial constraints to the same extent. This combination of theory and experiment for solid acids of known structure sheds considerable light on the relative contributions from solvation, electrostatic and van der Waals interactions in stabilizing cationic transition states and provides predictive insights into the relative contributions of parallel routes based on the size and charge distributions of their relevant intermediates and transition states. These findings also demonstrate how the consequences of acid strength on measured turnover rates depend on reaction conditions and their concomitant changes in the chemical significance of the rate parameters measured. Moreover, the complementary use of experiment and theory in resolving mechanistic controversies has given predictive guidance about how rate and equilibrium constants, often inextricably combined as measured rate parameters, individually depend on acid strength based on the magnitude and spatial distributions of charges in reactants, products and transition states involved in relevant elementary steps. The unique relations between k{sub mono}, k{sub dimer} and DPE developed here for CH{sub 3}OH dehydration can be applied in practice to assess the acid strength of any solid acid, many of which have unknown structures, preventing reliable calculations of their DPE by theory.

Carr, Robert T.; Neurock, Matthew; Iglesia, Enrique

2011-02-14

283

75 FR 4288 - Oxirane, 2-Methyl-, Polymer with Oxirane, Dimethyl Ether; Tolerance Exemption  

Federal Register 2010, 2011, 2012, 2013, 2014

...formulation under 40 CFR 180.960. BASF Corporation, 100 Campus Dr., Florham Park, NJ 07932 submitted a petition to EPA under...pesticide petition (PP 9E7595) filed by BASF Corporation, 100 Campus Dr., Florham Park, NJ 07932. The petition requested...

2010-01-27

284

pVT data of poly(ethylene glycol) dimethyl ether in 1,2-butanediol  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

285

Dimethyl sulfoxide permeation through glove materials  

Microsoft Academic Search

The permeation of dimethyl sulfoxide through specimens from four commercially available gloves was measured. Breakthrough times ranged from 1–1\\/2 to 2 hours for natural rubber latex to over 8 hours for neoprene latex. The Buna-N (nitrile) material exhibited the highest permeation rate.

ARTHUR D. SCHWOPE; MARGARET A. RANDEL; MILDRED G. BROOME

1981-01-01

286

Lung injury in dimethyl sulfate poisoning  

SciTech Connect

Two manual laborers were exposed to dimethyl sulfate during work and sustained mucosal injury to the eyes and respiratory tract. In one of them, noncardiogenic pulmonary edema occurred and improved with high-dose methylprednisolone. On follow-up for 10 months, this patient developed persistent productive cough with no evidence of bronchiectasis or bronchial hyperreactivity.

Ip, M.; Wong, K.L.; Wong, K.F.; So, S.Y.

1989-02-01

287

Revisiting optical clearing with dimethyl sulfoxide (DMSO)  

Microsoft Academic Search

Functional optical characterization of disease progression and response to therapy suffers from loss of spatial resolution and imaging depth due to scattering. Here we report on the ability of dimethyl sulfoxide (DMSO) alone to reduce the optical scattering of skin. We observed a threefold reduction in the scattering of skin with topical DMSO application. With an in vivo window chamber

Albert K. Bui; R. Anthony McClure; Jennell Chang; Charles Stoianovici; Jason Hirshburg; Alvin T. Yeh; Bernard Choi

2009-01-01

288

Dimethyl sulfide in the marine atmosphere  

Microsoft Academic Search

We have performed over 900 measurements of atmospheric dimethyl sulfide (DMS) in five different marine locations: the equatorial Pacific; Cape Grim, Tasmania; the Bahamas; the North Atlantic; and the Sargasso Sea. At all locations, DMS concentrations were usually in the range of 100-400 ng S m-3, with similar avarage concentrations of approximately 150 ng S m-3 (107 parts per thousand

M. O. Andreae; R. J. Ferek; F. Bermond; K. P. Byrd; R. T. Engstrom; S. Hardin; P. D. Houmere; F. LeMarrec; H. Raemdonck; R. B. Chatfield

1985-01-01

289

21 CFR 524.660 - Dimethyl sulfoxide.  

Code of Federal Regulations, 2014 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660 Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2014-04-01

290

Synthesis of (+)-spirolaxine methyl ether.  

PubMed

A short and efficient synthesis of (+)-spirolaxine methyl ether, a metabolite of the fungus Sporotrichum laxum with inhibitory activity against Helicobacter pylori, is described. The synthesis has been carried out by a Prins cyclization, to obtain the [6,5]-spiroketal system, and a Wadsworth-Emmons condensation, applied for the installation of the polymethylene chain on the phthalide moiety. PMID:16872220

Nannei, Raffaella; Dallavalle, Sabrina; Merlini, Lucio; Bava, Adriana; Nasini, Gianluca

2006-08-01

291

Polyarylene Ethers With Improved Properties  

NASA Technical Reports Server (NTRS)

Series of new polyarylene ethers (PAE's) prepared from reaction of activated dihalo compounds with various bisphenols. Compounds exhibit excellent processability by compression molding, plus good mechanical properties. All PAE's prepared suitable for use as adhesives, coatings, films, membranes, and composite matrices. Potentially useful for spacecraft and aircraft applications.

Hergenrother, Paul M.; Jensen, Brian J.; Havens, Stephen J.

1988-01-01

292

The fate of dimethyl p-(methylthio)phenyl phosphate in cotton plants  

E-print Network

-sulfoxide 0-demethyl GC-6506-sulfone Dimethyl phosphate Methyl Phosphate HSP04 0. 88 0. 10 0. 75 0. 50 0. 18 0. 32 0. 56 0. 26 0. 37 0. 04 0. 00 0. 79 0. 26 0. 03 0. 00 a/Solvent mixtures: A, 4:1 diethyl ether and acetonitrile; B, 90:10:3... 92. 2 2. 8 2. 3 2. 0 0. 0 0. 0 4. 5 92. 3 1. 4 1. 8 0. 0 s 46. 3 1. 9 14. 3 19. 1 12. 1 0, 4 65. 2 4. 3 7. 9 18. 0 4. 2 0. 0 2. 4 54. 6 11. 1 21. 1 10. 8 0. 1 33. 0 3. 7 12. 4 26. 7 24. 1 0. 0 47. 6 5. 6 10. 1 20...

Wendel, Lloyd Eugene

1973-01-01

293

Technical Report NREL/TP-6A50-56324  

E-print Network

Mountain Institute Joel Swisher #12;iv List of Acronyms CAFE Corporate Average Fuel Economy CAES compressed CSP concentrating solar power CT combustion turbine DME dimethyl ether DSM demand-side management EIA-equivalent GHG greenhouse gas GTL gas-to-liquid GW gigawatts IPCC Intergovernmental Panel on Climate Change IRP

294

Homogeneous charge compression ignition of LPG and gasoline using variable valve timing in an engine  

Microsoft Academic Search

The combustion characteristics and exhaust emissions in an engine were investigated under homogeneous charge compression ignition (HCCI) operation fueled with liquefied petroleum gas (LPG) and gasoline with regard to variable valve timing (VVT) and the addition of di-methyl ether (DME). LPG is a low carbon, high octane number fuel. These two features lead to lower carbon dioxide (CO2) emission and

Kitae Yeom; Jinyoung Jang; Choongsik Bae

2007-01-01

295

Acid strength and solvation effects on methylation, hydride transfer, and isomerization rates during catalytic homologation of C1 species  

E-print Network

Zeolites Carbenium ion Homologation a b s t r a c t Dimethyl ether (DME) homologation forms isobutane, FAU, MFI) via methylation and hydride transfer steps that favor isobutane and triptane formation isobutane. MFI forms isobutane and triptane with much lower selectivity than mesoporous acids or large

Iglesia, Enrique

296

Single-walled Carbon Nanotube Growth in a Wide Temperature Range  

E-print Network

Single-walled Carbon Nanotube Growth in a Wide Temperature Range Shohei Chiashi1, Taiki Inoue1 range. Ethanol and dimethyl ether (DME) were used as the carbon source and Co/Mo metal particles deposited on silicon substrates were used as the catalyst. The CVD temperature ranged from 400 to 900 degree

Maruyama, Shigeo

297

Evidence for spin solitons and their dynamics in a spin-Peierls system (DMe-DCNQI)2Li  

Microsoft Academic Search

A spin-Peierls system (DMe-DCNQI)2Li has been studied with electron paramagnetic resonance (EPR) under hydrostatic pressure. A definite frequency dependence of the EPR linewidth is observed for the Curie spins that appear below TSP, demonstrating a clear one-dimensional diffusive character similar to t-(CH)x. This is strong evidence for Curie spins to arise from spin solitons as domain walls caused by structural

Maki Hiraoka; Hirokazu Sakamoto; Kenji Mizoguchi; Reizo Kato

2002-01-01

298

How to make the production of methanol\\/DME “GREENER“—Integration of wind power with modern coal chemical industry  

Microsoft Academic Search

The urgency and necessity of alternative fuels give an impetus to the development of modern coal chemical industry. Coal-based\\u000a methanol\\/DME is the key element of this industry. Wind power, whose installed capacity increased at a rate of more than 100%\\u000a in recent years, has the most developed technologies in renewable energy. However, there still exist many unsolved problems\\u000a in wind

Weidou Ni; Jian Gao; Zhen Chen; Zheng Li

2009-01-01

299

GSC 2314-0530: the shortest-period eclipsing system with dMe components  

E-print Network

CCD photometric observations in VRI colors and spectroscopic observations of the newly discovered eclipsing binary GSC 2314-0530 (NSVS 6550671) with dMe components and very short period of P=0.192636 days are presented. The simultaneous light-curve solution and radial velocity solution allows to determine the global parameters of GSC 2314-0530: T_{1}=3735 K; T_{2}=3106 K; M_{1}=0.51 M_sun; M_{2}=0.26 M_sun; R_{1}=0.55 R_sun; R_{2}=0.29 R_sun; L_{1}=0.053 L_sun; L_{2}=0.007 L_sun; i=72.5 degr; a=1.28 R_sun; d=59 pc. The chromospheric activity of its components is revealed by strong emission in the H_alpha line (with mean EW=5 A) and observed several flares. Empirical relations mass-M_{bol}, mass-radius and mass-temperature are derived on the basis of the parameters of known binaries with low-mass dM components.

Dimitrov, D

2010-01-01

300

Interaction of low-energy electrons with dimethyl sulfide and dimethyl disulfide  

NASA Astrophysics Data System (ADS)

We report elastic integral cross sections for low-energy electron scattering by gas-phase dimethyl sulfide and dimethyl disulfide, obtained with the Schwinger multichannel method with pseudopotentials. Our symmetry-resolved cross sections for dimethyl sulfide reveal that the single broad structure at 3.25 eV observed in the electron transmission spectrum (assigned as a ?CS* shape resonance) would actually arise from two superimposed anion states in the B2 and A1 symmetry components of the C2 v point group. We also obtained two low-lying shape resonances for dimethyl disulfide, in good agreement with the available electron transmission data. In view of the recently reported measurements on dissociative electron attachment to dimethyl disulfide [C. Matias, A. Mauracher, P. Scheier, P. Limão-Vieira, and S. Denifl, Chem. Phys. Lett. 605-606, 71 (2014), 10.1016/j.cplett.2014.05.016], we also calculated cross sections for stretched S-S bond lengths, which indicate a fast stabilization consistent with the experimental data.

Santos, J. S. dos; Kossoski, F.; Varella, M. T. do N.

2014-11-01

301

XRAY FLARING ON THE dMe STAR, ROSS 154 B. J. Wargelin, V. L. Kashyap, J. J. Drake, D. GarcI a l are , 1 an . W. a la  

E-print Network

X­RAY FLARING ON THE dMe STAR, ROSS 154 B. J. Wargelin, V. L. Kashyap, J. J. Drake, D. GarcI â?? â??a l e M d e d e e e FYG d , ­ e e e e dMe e H , e e e e e e e e e e e S , dMe e X­ e e e e X­ e e M d d­rayYluminous and faster rotating dMe stars: AD Leo (Saar & Linsky 1985), EV Lac (Johns­Krull & Valenti 1996), and AUMic

Wargelin, Bradford J.

302

Aza crown ether compounds as anion receptors  

SciTech Connect

A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI.sup.+ ion in alkali metal batteries.

Lee, Hung Sui (East Setauket, NY); Yang, Xiao-Oing (Port Jefferson Station, NY); McBreen, James (Bellport, NY)

1998-08-04

303

Aza crown ether compounds as anion receptors  

DOEpatents

A family of aza-ether based compounds including linear, multi-branched and aza-crown ethers is provided. When added to non-aqueous battery electrolytes, the new family of aza-ether based compounds acts as neutral receptors to complex the anion moiety of the electrolyte salt thereby increasing the conductivity and the transference number of LI{sup +} ion in alkali metal batteries. 3 figs.

Lee, H.S.; Yang, X.O.; McBreen, J.

1998-08-04

304

Near-Infrared Electrochromism in Electroactive Pentacenediquinone-Containing Poly(aryl ether)s  

E-print Network

Near-Infrared Electrochromism in Electroactive Pentacenediquinone-Containing Poly(aryl etherVed October 21, 2005 The synthesis and near-infrared electrochromic properties of pentacenediquinone-infrared electrochromic properties of pentacenediquinone-containing poly(aryl ether)s were studied

Wan, Xin-hua

305

40 CFR 721.10067 - Ether amine phosphonate salt (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Ether amine phosphonate salt (generic). 721.10067 Section 721...721.10067 Ether amine phosphonate salt (generic). (a) Chemical substances...identified generically as ether amine phosphonate salt (PMNs P-05-57,...

2012-07-01

306

40 CFR 721.10067 - Ether amine phosphonate salt (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Ether amine phosphonate salt (generic). 721.10067 Section 721...721.10067 Ether amine phosphonate salt (generic). (a) Chemical substances...identified generically as ether amine phosphonate salt (PMNs P-05-57,...

2010-07-01

307

40 CFR 721.10067 - Ether amine phosphonate salt (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Ether amine phosphonate salt (generic). 721.10067 Section 721...721.10067 Ether amine phosphonate salt (generic). (a) Chemical substances...identified generically as ether amine phosphonate salt (PMNs P-05-57,...

2013-07-01

308

40 CFR 721.10551 - Bisphenol S mono ether (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Bisphenol S mono ether (generic). 721.10551...Chemical Substances § 721.10551 Bisphenol S mono ether (generic). (a...chemical substance identified generically as bisphenol S mono ether (PMN...

2013-07-01

309

40 CFR 721.10551 - Bisphenol S mono ether (generic).  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Bisphenol S mono ether (generic). 721.10551...Chemical Substances § 721.10551 Bisphenol S mono ether (generic). (a...chemical substance identified generically as bisphenol S mono ether (PMN...

2014-07-01

310

40 CFR 721.3440 - Haloalkyl substituted cyclic ethers.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Haloalkyl substituted cyclic ethers. 721.3440 Section 721... § 721.3440 Haloalkyl substituted cyclic ethers. (a) Chemical substance and...chemical substances haloalkyl substituted cyclic ethers (PMN P-85-368 and...

2010-07-01

311

40 CFR 721.10666 - Quaternary ammonium compounds, bis(fattyalkyl) dimethyl, salts with tannins (generic).  

Code of Federal Regulations, 2013 CFR

...bis(fattyalkyl) dimethyl, salts with tannins (generic). 721.10666 Section...bis(fattyalkyl) dimethyl, salts with tannins (generic). (a) Chemical substance...bis(fattyalkyl) dimethyl, salts with tannins (PMN P-12-437) is subject to...

2013-07-01

312

40 CFR 721.10666 - Quaternary ammonium compounds, bis(fattyalkyl) dimethyl, salts with tannins (generic).  

Code of Federal Regulations, 2014 CFR

...bis(fattyalkyl) dimethyl, salts with tannins (generic). 721.10666 Section...bis(fattyalkyl) dimethyl, salts with tannins (generic). (a) Chemical substance...bis(fattyalkyl) dimethyl, salts with tannins (PMN P-12-437) is subject to...

2014-07-01

313

Vibrational Study Of Poly(Ether Ether Ketone).  

NASA Astrophysics Data System (ADS)

The medium infrared region (4000-400cm-1) has been widely used to study crystallinity because differences could be observed in the vibrational spectrum of several polymers which could be related to crystallinity as determined by X-ray diffraction, differential scanning calorimetry and density measurements. However, as crystallinity is concerned with packing of chains and interactions between neighboor chains, the absorption bands arising from such vibrations appear therefore at wavenumbers below 400 cm -1. Poly-(oxy-1,4-phenyleneoxy-1,4-phenylenecarbonyl-1,4-phenylene) or poly(aryl ether ether ketone) (PEEK),commercially introduced by ICI1, has been attracting increasing interest. It is a semicrystalline polymer with an unusual combination of properties such as high chemical resistance, excellent thermal stability as good mechanical properties. Taking into account of its high temperature high strength characteristics and melt processability, PEEK is generating interest for applications such as reinforced composites, coatings, electrical connectors, impeller housings... Fourier transform infrared spectroscopy is a quick and powerful tool to investigate orientation and/or crystallinity in polymeric materials.

Dosiere, M.

1989-12-01

314

Delayed dermal burns caused by dimethyl acetylenedicarboxylate.  

PubMed

A chemical operator handling dimethyl acetylenedicarboxylate (DMAD) developed delayed and pain-free burns on one of his feet 2 days after a supposed spillage of DMAD. The injuries were confirmed to be associated with DMAD by chemical analysis of the operator's safety boot and patch tests. DMAD easily penetrates some protective clothing and dilute solutions can still be hazardous: the toxic effect is compounded by being delayed and painless. The lachrymatory irritant properties of undiluted DMAD are not adequate warning of its presence or spillage in quantities sufficient to cause significant skin damage. PMID:6235090

Slovak, A J; Payne, A R

1984-07-01

315

Dimethyl fumarate protection against collagen II degradation.  

PubMed

Degradation of collagen type II caused by pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-?) is one of the major pathological characteristics of osteoarthritis (OA). Dimethyl fumarate (DMF) is a medication approved by the US Food and Drug Administration (FDA) as an oral multiple sclerosis (MS) therapy. In this study, we found that DMF ameliorated collagen type II degradation by inhibiting the expression of MMP-1, MMP-3, and MMP-13 caused by TNF-?. Mechanistically, DMF attenuated MMPs expression by suppressing JAK/STAT3 pathway. These findings imply that DMF treatment might be a potential therapeutic strategy for chondroprotective therapy. PMID:25305493

Li, Ye; Tang, Jie; Hu, Yong

2014-11-14

316

Biogenic production of dimethyl sulfide: Krill grazing  

SciTech Connect

Dimethyl sulfide (DMS), a dominant sulfur compound in sea water, is a possible precursor for cloud condensation nuclei in the atmosphere and may influence global climate. The primary source of DMS is phytoplankton, but the mechanisms remain uncertain, and concentrations of DMS in the ocean vary spatially and temporally. Laboratory studies suggest zooplankton grazing may be an important process leading to the formation of DMS in the ocean. This paper describes ocean studies which examine the suggestion that grazing by krill may be a significant source for DMS production in the antarctic coastal region. 11 refs., 2 figs.

Daly, K.L.; DiTullio, G.R. (Univ. of Tennessee, Knoxville, TN (United States))

1993-01-01

317

Research on Si-Al based catalysts prepared by complete liquid-phase method for DME synthesis in a slurry reactor  

NASA Astrophysics Data System (ADS)

A series of Si-Al based DME synthesis catalysts were prepared by complete liquid-phase method and characterized by in situ XPS, XRD, N 2 adsorption and NH 3-TPD analyses. Based on the results, the addition of Si could adjust the pore structure and surface acidity of catalyst, exhibiting a strong promoting effect on the CO conversion and DME selectivity. However, when Si/Al ratio is higher, Si would cover active sites and increase the amount of strong acidity sites, causing the reduction in catalytic activity. It was found from in situ XPS characterization that Cu 0 is the active center of methanol synthesis in DME production, and the addition of Si changes the chemical surroundings of active components and weaken the interaction between Cu, Zn and Al, which maybe give rise to the decrease in catalyst stability.

Li, Zhihong; Zuo, Zhijun; Huang, Wei; Xie, Kechang

2011-01-01

318

Covariant Ether Theories and Special Relativity  

Microsoft Academic Search

The present paper defines “covariant ether theories” as all space-time theories that are alternative to special relativity theory (SRT), but nevertheless satisfy the general relativity principle. A general analysis of the properties of admissible space-time transformations shows that the number of such “covariant ether theories” is infinite, and that all these theories are indistinguishable from SRT with all experiments in

A. L. Kholmetskii

2003-01-01

319

Polymeric Electrolyte Containing 12-Crown-4 Ether  

NASA Technical Reports Server (NTRS)

Experiments show incorporation of 12-crown-4 ether into solid electrolytes based on polyethylene oxide enhances their electrochemical properties. More specifically, 12-crown-4 ether increases Faradaic efficiency for Li+ ions in low-power secondary Li cells and enables operation of these cells at lower temperatures with higher efficiencies.

Nagasubramanian, Ganesa; Distefano, Salvador

1992-01-01

320

Composition-explicit distillation curves of diesel fuel with glycol ether and glycol ester oxygenates: fuel analysis metrology to enable decreased particulate emissions.  

PubMed

We recently introduced several important improvements in the measurement of distillation curves of complex fluids. The modifications to the classical measurement provide for (1) a composition-explicit data channel for each distillate fraction (for both qualitative and quantitative analysis), (2) temperature measurements that are true thermodynamic state points that can be modeled with an equation of state, (3) temperature, volume, and pressure measurements of low uncertainty suitable for equation of state development, (4) consistency with a century of historical data, (5) an assessment of the energy content of each distillate fraction, (6) trace chemical analysis of each distillate fraction, and (7) corrosivity assessment of each distillate fraction. We have applied the new method to the measurement of rocket propellant, gasolines, jet fuels, and hydrocarbon crude oils. In this paper we presentthe application of the technique to representative diesel fuel and mixtures of diesel fuel with some of the more promising oxygenating agents; namely, the glycol ethers and glycol esters: tri(propylene glycol) methyl ether (TPM), dibutyl maleate (DBM), and an 80/ 20 (vol/vol) mixture of diethylene glycol methyl ether (DGME) + 1,2-dimethoxyethane (DME) a mixture often referred to as Cetaner. We present not only the distillation curves but also a chemical characterization of each fraction, and discuss the contrasts between the various mixtures. The measurements are significant as an environmental design tool for decreased particulate emissions. PMID:18983093

Smith, Beverly L; Ott, Lisa S; Bruno, Thomas J

2008-10-15

321

Purification of aqueous cellulose ethers  

SciTech Connect

Manufacture of cellulose ethers usually involves high amounts of salt by-products. For application of the product, salt must be removed. In this work, we have studied the injection of high-pressure CO{sub 2} into an aqueous polymer-salt solution; we find that upon addition of isopropanol in addition to CO{sub 2}, the solution separates into two phases. One phase is rich in polymer and water, and the other phase contains mostly isopropanol, water and CO{sub 2}. The salt distributes between the two phases, thereby offering interesting possibilities for development of a new purification process for water-soluble polymers. This work presents experimental phase-equilibrium data for hydroxyethyl cellulose and sodium carboxymethyl cellulose with sodium acetate and potassium sulfate, respectively, in the region 40{degree}C and 30 to 80 bar. Based on these data, we suggest a process for the manufacture and purification of water-soluble cellulose ethers. 15 refs., 14 figs., 9 tabs.

Bartscherer, K.A.; de Pablo, J.J.; Bonnin, M.C.; Prausnitz, J.M.

1990-07-01

322

DME synthesis from synthesis gas on the admixed catalysts of Cu\\/ZnO\\/Al 2O 3 and ZSM-5  

Microsoft Academic Search

Na-ZSM-5 and H-ZSM-5 catalysts with three different Si\\/Al ratios were prepared to investigate methanol dehydration and direct DME synthesis. The acid strength of ZSM-5 increased with a decrease in the Si\\/Al ratios and methanol dehydration rate was maximized on H-ZSM-5(30) with the highest acid strength. The direct DME synthesis was conducted on the admixed catalysts of Cu\\/ZnO\\/Al2O3 and ZSM-5. The

Ji-Hyun Kim; Min Jo Park; Sun Jin Kim; Oh-Shim Joo; Kwang-Deog Jung

2004-01-01

323

Ether polar lipids of methanogenic bacteria: structures, comparative aspects, and biosyntheses.  

PubMed Central

Complete structures of nearly 40 ether polar lipids from seven species of methanogens have been elucidated during the past 10 years. Three kinds of variations of core lipids, macrocyclic archaeol and two hydroxyarchaeols, were identified, in addition to the usual archaeol and caldarchaeol (for the nomenclature of archaeal [archaebacterial] ether lipids, see the text). Polar head groups of methanogen phospholipids include ethanolamine, serine, inositol, N-acetylglucosamine, dimethyl- and trimethylaminopentanetetrol, and glucosaminylinositol. Glucose is the sole hexose moiety of glycolipids in most methanogens, and galactose and mannose have been found in a few species. Methanogen lipids are characterized by their diversity in phosphate-containing polar head groups and core lipids, which in turn can be used for chemotaxonomy of methanogens. This was shown by preliminary simplified analyses of lipid component residues. Core lipid analysis by high-pressure liquid chromatography provides a method of determining the methanogenic biomass in natural samples. There has been significant progress in the biosynthetic studies of methanogen lipids in recent years. In vivo incorporation experiments have led to delineation of the outline of the synthetic route of the diphytanylglycerol ether core. The mechanisms of biosynthesis of tetraether lipids and various polar lipids, and cell-free systems of either lipid synthesis, however, remain to be elucidated. The significance and the origin of archaeal ether lipids is discussed in terms of the lipid composition of bacteria living in a wide variety of environments, the oxygen requirement for biosynthesis of hydrocarbon chains, and the physicochemical properties and functions of lipids as membrane constituents. PMID:8464404

Koga, Y; Nishihara, M; Morii, H; Akagawa-Matsushita, M

1993-01-01

324

Cutaneous metabolism of glycol ethers.  

PubMed

The toxicity of glycol ethers is associated with their oxidation to the corresponding aldehyde and alkoxyacetic acid by cytosolic alcohol dehydrogenase (ADH; EC 1.1.1.1.) and aldehyde dehydrogenase (ALDH; 1.2.1.3). Dermal exposure to these compounds can result in localised or systemic toxicity including skin sensitisation and irritancy, reproductive, developmental and haemotological effects. It has previously been shown that skin has the capacity for local metabolism of applied chemicals. Therefore, there is a requirement to consider metabolism during dermal absorption of these compounds in risk assessment for humans. Cytosolic fractions were prepared from rat liver, and whole and dermatomed skin by differential centrifugation. Rat skin cytosolic fractions were also prepared following multiple dermal exposure to dexamethasone, ethanol or 2-butoxyethanol (2-BE). The rate of ethanol, 2-ethoxyethanol (2-EE), ethylene glycol, 2-phenoxyethanol (2-PE) and 2-BE conversion to alkoxyacetic acid by ADH/ALDH in these fractions was continuously monitored by UV spectrophotometry via the conversion of NAD+ to NADH at 340 nm. Rates of ADH oxidation by rat liver cytosol were greatest for ethanol followed by 2-EE >ethylene glycol >2-PE >2-BE. However, the order of metabolism changed to 2-BE >2-PE >ethylene glycol >2-EE >ethanol using whole and dermatomed rat skin cytosolic fractions, with approximately twice the specific activity in dermatomed skin cytosol relative to whole rat skin. This suggests that ADH and ALDH are localised in the epidermis that constitutes more of the protein in dermatomed skin than whole skin cytosol. Inhibition of ADH oxidation in rat liver cytosol by pyrazole was greatest for ethanol followed by 2-EE >ethylene glycol >2-PE >2-BE, but it only inhibited ethanol metabolism by 40% in skin cytosol. Disulfiram completely inhibited alcohol and glycol ether metabolism in the liver and skin cytosolic fractions. Although ADH1, ADH2 and ADH3 are expressed at the protein level in rat liver, only ADH1 and ADH2 are selectively inhibited by pyrazole and they constitute the predominant isoforms that metabolise short-chain alcohols in preference to intermediate chain-length alcohols. However, ADH1, ADH3 and ADH4 predominate in rat skin, demonstrate different sensitivities to pyrazole, and are responsible for metabolising glycol ethers. ALDH1 is the predominant isoform in rat liver and skin cytosolic fractions that is selectively inhibited by disulfiram and responds to the amount of aldehyde formed by the ADH isoforms expressed in these tissues. Thus, the different affinity of ADH and ALDH for alcohols and glycol ethers of different carbon-chain length may reflect the relative isoform expression in rat liver and skin. Following multiple topical exposure, ethanol metabolism increased the most following ethanol treatment, and 2-BE metabolism increased the most following 2-BE treatment. Ethanol and 2-BE may induce specific ADH and ALDH isoforms that preferentially metabolise short-chain alcohols (i.e. ADH1, ALDH1) and longer chain alcohols (i.e. ADH3, ADH4, ALDH1), respectively. Treatment with a general inducing agent such as dexamethasone enhanced ethanol and 2-BE metabolism suggesting induction of multiple ADH isoforms. PMID:15551062

Lockley, David J; Howes, Douglas; Williams, Faith M

2005-03-01

325

Poly(aryl ethers) and related polysiloxane copolymer molecular coatings: Preparation and radiation degradation  

NASA Technical Reports Server (NTRS)

The radiation degradation of poly(arylene ether sulfones) and related materials is studied. These basic studies are important both as a means to developing stronger, more stable matrix resins for composite materials, as well as to improve the data base in regard to chemical structure-physical property relationships. Thirty homo and copolymers were synthesized, at least partially characterized and, in several cases suitable film casting techniques were developed. Four samples were chosen for initial radiation degradation. Poly(dimethyl siloxane) soft bocks/segments can preferentially migrate to the surface of copolymer films. Since siloxanes are utilized as thermal control coatings, this form of 'molecular' coating is of interest. The chemistry for preparing such copolymers with any of the polymers described was demonstrated.

Mcgrath, J. E.

1982-01-01

326

Methods for synthesis of nonabromodiphenyl ethers and a chloro-nonabromodiphenyl ether  

Microsoft Academic Search

Polybrominated diphenyl ethers (PBDEs) have been used extensively as brominated flame retardants (BFRs) in textiles, upholstery and electronics. They are ubiquitous contaminants in wildlife and humans. A low concentration of nonabrominated diphenyl ethers (nonaBDEs) is present in commercial DecaBDE and they are also abiotic and biotic debromination products of decabromodiphenyl ether (BDE-209). The objective of the present work was to

Anna Christiansson; Daniel Teclechiel; Johan Eriksson; Åke Bergman; Göran Marsh

2006-01-01

327

27 CFR 21.108 - Ethyl ether.  

Code of Federal Regulations, 2010 CFR

...FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.108 Ethyl ether. (a) Odor. Characteristic odor. (b) Specific gravity at 15.56 °/15.56 °C. Not more than 0.728. [T.D. ATF-133,...

2010-04-01

328

METHYL TERTIARY-BUTYL ETHER (MTBE): Gasoline  

NSDL National Science Digital Library

This site gives an explanation of Methyl tertiary butyl ether (MTBE), also known as an oxygenate, a chemical compound used as a gasoline additive to enhance the octane and subsequently burn the fuel more completely.

329

IINS, MIR, and DFT Investigations, of Vibrational Spectra, of 3, 3Dimethyl1Butanol, and 3, 3Dimethyl2Butanol  

Microsoft Academic Search

Molecular vibrational spectra in 3, 3-dimethyl-1-butanol, (CH3)3 CCH2CH2OH, and 3, 3-dimethyl-2-butanol, (CH3)3CCHOHCH3, were measured by the inelastic incoherent neutron scattering and mid infrared spectroscopy and for 3, 3-dimethyl-2-butanol additionally by the far infrared absorption method. Experimental results were discussed and compared with the results of the quantum chemical calculations performed by the density functional theory (DFT\\/B3LYP\\/6-311G**) and semi-empirical PM3 calculation

E. Juszynska; K. Holderna-Natkaniec; M. Massalska-Arodz; I. Natkaniec; E. Sciesinska; J. Sciesinski

2008-01-01

330

21 CFR 73.37 - Astaxanthin dimethyl-disuccinate.  

Code of Federal Regulations, 2011 CFR

...Section 73.37 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT...ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.37 Astaxanthin dimethyl-disuccinate...use in color additive mixtures for coloring foods. (b) Specifications...

2011-04-01

331

Molecular structure and transport dynamics in Nafion and sulfonated poly(ether ether ketone ketone) membranes  

Microsoft Academic Search

An atomistic simulation technique is performed to investigate the molecular structure and transport dynamics inside a hydrated Nafion membrane and a hydrated sulfonated poly(ether ether ketone ketone) (SPEEKK) membrane. The simulation system consists of the representative fragments of the polymer electrolytes, hydronium ions and solvent molecules, such as water plus methanol molecules. Simulation results show that the hydrated SPEEKK has

P. Y. Chen; C. P. Chiu; C. W. Hong

2009-01-01

332

Sulfonated poly(tetramethydiphenyl ether ether ketone) membranes for vanadium redox flow battery application  

Microsoft Academic Search

Sulfonated poly(tetramethydiphenyl ether ether ketone) (SPEEK) with various degree of sulfonation is prepared and first used as ion exchange membrane for vanadium redox flow battery (VRB) application. The vanadium ion permeability of SPEEK40 membrane is one order of magnitude lower than that of Nafion 115 membrane. The low cost SPEEK membranes exhibit a better performance than Nafion at the same

Zhensheng Mai; Huamin Zhang; Xianfeng Li; Cheng Bi; Hua Dai

2011-01-01

333

Synthesis and Modification of Poly(ether ether ketone) and their Properties: A Review  

Microsoft Academic Search

Synthetic aromatic polyarylether ketones are known for their high performance applications. Poly(ether ether ketone) is an important material which is most widely used in such aggressive environments as nuclear plants, oil and geothermal wells, chemical plants, and high-pressure steam valves. Considering the wide range of properties of PEEK polymers, a variety of structurally modified PEEK polymers are also reported. This

Devesh Shukla; Yuvraj Singh Negi; Jugmendra Sen Uppadhyaya; Vijai Kumar

2012-01-01

334

Comparative acute and subchronic toxicity of ethylene glycol monopropyl ether and ethylene glycol monopropyl ether acetate  

Microsoft Academic Search

The acute toxicity of ethylene glycol monopropyl ether (EGPE) and ethylene-glycol monopropyl ether acetate (EGPEA) was determined in a series of standardized tests. The oral LDââ in rats was 3089 and 9456 mg\\/kg EGPE and EGPEA, respectively. Skin irritation was slight following an occluded single dose application of either compound to the guinea pig abdomen. The dermal LDââ for guinea

G. V. Katz; W. J. Krasavage; C. J. Terhaar

1984-01-01

335

Acute oral toxicity of ethylene glycol monomethyl ether and diethylene glycol monomethyl ether  

Microsoft Academic Search

The glycol ethers are a class of chemicals exhibiting the polar properties of alcohols and the nonpolar properties of ethers, making them useful in a variety of industrial applications including the manufacture of plastics, as bases for inks, dyes and cleaners and as deicing agents. They are also used as chemical intermediates, as diluents for hydraulic brake fluid, and in

Toshihiro Kawamoto; Koji Matsuno; Fujio Kayama; Manabu Hirai; Kelichi Arashidani; Masahiro Yoshikawa; Yasushi Kodama

1990-01-01

336

Enhanced enzyme activity and enantioselectivity of lipases in organic solvents by crown ethers and cyclodextrins.  

PubMed

Lipases from Candida rugosa (CRL) and Pseudomonas cepacia (PCL) were co-lyophilized with cyclic oligoethers including four crown ethers and nine cyclodextrins (CyDs), and their transesterification activity and enantioselectivity in organic solvents were evaluated. The PCL co-lyophilized with each additive showed simultaneously enhanced enzyme activity and enantioselectivity when compared to the native lipase lyophilized from buffer alone; in contrast, such enhancement was not observed for the co-lyophilized CRL. Among the cyclic oligoethers examined, permethylated betaCyD (Me1.78betaCyD), as the most suitable additive, was used for the optimization of both the co-lyophilized PCL preparation and reaction conditions by determining the effects of varying the additive/lipase ratio, aqueous pH, the nature of organic solvents, and temperature. The initial rate determined for the transesterification between racemic 2,2-dimethyl-1,3-dioxolane-4-methanol and vinyl butyrate in diisopropyl ether at 30 degrees C increased by up to 17-fold and the enantioselectivity represented by E could be doubled. While there was an inverse correlation between temperature and enantioselectivity, with the Me1.78betaCyD-PCL co-lyophilizate, the reaction rate even at 0 degrees C was much higher than that at higher temperatures in the native PCL-catalyzed reaction. Hence, this method seems to be of practical use for the large-scale production of optically active compounds. PMID:16233437

Mine, Yurie; Fukunaga, Kimitoshi; Itoh, Kyoko; Yoshimoto, Makoto; Nakao, Katsumi; Sugimura, Yoshiaki

2003-01-01

337

Steric effects in hula-twist photoisomerization. 1,4-dimethyl- and 2,3-dimethyl-1,4-diphenylbutadienes.  

PubMed

1,4-Dimethyl-1,4-diphenylbutadiene was shown to be able to execute regiospecific HT-1 photoisomerization around a methyl group when irradiated in a low-temperature organic glass, albeit at reduced efficiency. 2,3-Dimethyl-1,4-diphenylbutadiene exhibited a different type of steric effect, causing the E,E-isomer to undergo regiospecific HT-1 photoisomerization. PMID:15984859

Yang, Lan-Ying; Liu, Robert S H; Wendt, Natalie L; Liu, Jin

2005-07-01

338

Rigid-strut-containing crown ethers and [2]catenanes for incorporation into metal-organic frameworks.  

PubMed

To introduce crown ethers into the struts of metal-organic frameworks (MOFs), general approaches have been developed for the syntheses of dicarboxylic acid dibenzo[30]crown-10 (DB30C10DA), dicarboxylic acid di-2,3-naphtho[30]crown-10 (DN30C10DA), dicarboxylic acid bisparaphenylene[34]crown-10 (BPP34C10DA), and dicarboxylic acid 1,5-naphthoparaphenylene[36]crown-10 (NPP36C10DA). These novel crown ethers not only retain the characteristics of their parent crown ethers since they can 1) bind cationic guests and 2) serve as templates for making mechanically interlocked molecules (MIMs), such as catenanes and rotaxanes, but they also present coordination sites to connect with secondary building units (SBUs) in MOFs. The binding behavior of BPP34C10DA with 1,1'-dimethyl-4,4'-bipyridinium bis(hexafluorophosphate) (DMBP2.PF(6)) has been investigated by means of UV/Vis, fluorescence, and NMR spectroscopic techniques. The crystal superstructure of the complex DMBP2.PF(6) subset BPP34C10DA was determined by X-ray crystallography. The NPP36C10DA-based [2]catenane (H(2)NPP36C10DC-CAT4.PF(6)) and the BPP34C10DA-based [2]catenane (H(2)BPP34C10DC-CAT4.PF(6)) were prepared in DMF at room temperature by the template-directed clipping reactions of the planarly chiral NPP36C10DA and BPP34C10DA with 1,1'-[1,4-phenylenebis(methylene)]di-4,4'-bipyridin-1-ium bis(hexafluorophosphate) and 1,4-bis(bromomethyl)benzene, respectively. The crystal structure of the dimethyl ester (BPP34C10DE-CAT4.PF(6)) of the [2]catenane H(2)BPP34C10DC-CAT4.PF(6) was investigated by X-ray crystallography, which revealed racemic R and S isomers with planar chirality present in the crystal in a 1:1 ratio. These crown ether based struts serve as excellent organic ligands to bind with transition metal ions in the construction of MOFs: the crown ethers BPP34C10DA and NPP36C10DA in the presence of Zn(NO(3))(2)4.H(2)O afforded the MOF-1001 and MOF-1002 frameworks, respectively. The crystal structures of MOF-1001 and MOF-1002 are both cubic and display Fm3m symmetry. The unit cell parameter of the metal-organic frameworks is a=52.9345 A. Since such MOFs, containing electron-donating crown ethers are capable of docking incoming electron-accepting substrates in a stereoelectronically controlled fashion, the present work opens a new access to the preparation and application of MOFs. PMID:19946906

Zhao, Yan-Li; Liu, Lihua; Zhang, Wenyu; Sue, Chi-Hau; Li, Qiaowei; Miljani?, Ognjen S; Yaghi, Omar M; Stoddart, J Fraser

2009-12-14

339

Enhancement of enzyme activity and enantioselectivity by cyclopentyl methyl ether in the transesterification catalyzed by Pseudomonas cepacia lipase co-lyophilized with cyclodextrins  

Microsoft Academic Search

The solvent effects of cyclopentyl methyl ether (CPME) on the reaction rates and enzyme enantioselectivity in the enantioselective transesterifications of racemic 6-methyl-5-hepten-2-ol (racemic sulcatol: SUL) and racemic 2,2-dimethyl-1,3-dioxolane-4-methanol (racemic solketal: SOL) with a series of enol esters catalyzed by Pseudomonas cepacia lipase co-lyophilized with cyclodextrins (a-, ß-, ?-, partially methylated ß-,?and 2,3,6-tri-O-methyl-ß-cyclodextrin: aCyD; ßCyD; ?CyD; Me1.78 ßCyD; Me3ßCyD) were investigated

Yurie Mine; Lin Zhang; Kimitoshi Fukunaga; Yoshiaki Sugimura

2005-01-01

340

Dimethyl disulfide (DMDS) and dimethyl sulfide (DMS) emissions from biomass burning in Australia  

NASA Astrophysics Data System (ADS)

We identify dimethyl disulfide (DMDS) as the major reduced sulfur-containing gas emitted from bushfires in Australia's Northern Territory. Like dimethyl sulfide (DMS), DMDS is oxidized in the atmosphere to sulfur dioxide (SO2) and methane sulfonic acid (MSA), which are intermediates in the formation of sulfuric acid (H2SO4). The mixing ratios of DMDS and DMS were the highest we have ever detected, with maximum values of 113 and 35 ppbv, respectively, whereas background values were below the detection limit (10 pptv). Molar emission ratios relative to carbon monoxide (CO) were [1.6 +/- 0.1] × 10-5 and [6.2 +/- 0.3] × 10-6, for DMDS and DMS respectively, while molar emission ratios relative to carbon dioxide (CO2) were [4.7 +/- 0.4] × 10-6 and [1.4 +/- 0.4] × 10-7, respectively. Assuming these observations are representative of biomass burning, we estimate that biomass burning could yield up to 175 Gg/yr of DMDS (119 Gg S/yr) and 13 Gg/yr of DMS.

Meinardi, Simone; Simpson, Isobel J.; Blake, Nicola J.; Blake, Donald R.; Rowland, F. Sherwood

2003-05-01

341

41. LOOKING WEST AT BUILDING NO. 519, ETHER AND ALCOHOL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

41. LOOKING WEST AT BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, (LEFT) AND BUILDING NO. 521, ETHER VAULT, (RIGHT) IN FOREGROUND - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

342

37. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, NORTHWEST ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

37. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, NORTHWEST CORNER OF BUILDING. BUILDING NO. 521 (ETHER VAULT) IN BACKGROUND LEFT. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

343

Dimethyl sulfide in the Amazon rain forest  

NASA Astrophysics Data System (ADS)

Surface-to-atmosphere emissions of dimethyl sulfide (DMS) may impact global climate through the formation of gaseous sulfuric acid, which can yield secondary sulfate aerosols and contribute to new particle formation. While oceans are generally considered the dominant sources of DMS, a shortage of ecosystem observations prevents an accurate analysis of terrestrial DMS sources. Using mass spectrometry, we quantified ambient DMS mixing ratios within and above a primary rainforest ecosystem in the central Amazon Basin in real-time (2010-2011) and at high vertical resolution (2013-2014). Elevated but highly variable DMS mixing ratios were observed within the canopy, showing clear evidence of a net ecosystem source to the atmosphere during both day and night in both the dry and wet seasons. Periods of high DMS mixing ratios lasting up to 8 h (up to 160 parts per trillion (ppt)) often occurred within the canopy and near the surface during many evenings and nights. Daytime gradients showed mixing ratios (up to 80 ppt) peaking near the top of the canopy as well as near the ground following a rain event. The spatial and temporal distribution of DMS suggests that ambient levels and their potential climatic impacts are dominated by local soil and plant emissions. A soil source was confirmed by measurements of DMS emission fluxes from Amazon soils as a function of temperature and soil moisture. Furthermore, light- and temperature-dependent DMS emissions were measured from seven tropical tree species. Our study has important implications for understanding terrestrial DMS sources and their role in coupled land-atmosphere climate feedbacks.

Jardine, K.; Yañez-Serrano, A. M.; Williams, J.; Kunert, N.; Jardine, A.; Taylor, T.; Abrell, L.; Artaxo, P.; Guenther, A.; Hewitt, C. N.; House, E.; Florentino, A. P.; Manzi, A.; Higuchi, N.; Kesselmeier, J.; Behrendt, T.; Veres, P. R.; Derstroff, B.; Fuentes, J. D.; Martin, S. T.; Andreae, M. O.

2015-01-01

344

High octane ethers from synthesis gas-derived alcohols  

SciTech Connect

The objective of the proposed research is to synthesize high octane ethers, primarily methyl isobutyl ether (MIBE) and methyl tertiary butyl ether (MTBE), directly from H{sub 2}/CO/CO{sub 2} coal-derived synthesis gas via alcohol mixtures that are rich in methanol and 2-methyl-1-propanol (isobutanol). The overall scheme involves gasification of coal, purification and shifting of the synthesis gas, higher alcohol synthesis, and direct synthesis of ethers.

Klier, K.; Herman, R.G.; Johansson, M.; Feeley, O.C.

1992-01-01

345

Chemistry of dimethyl sulfide in the equatorial Pacific atmosphere  

NASA Astrophysics Data System (ADS)

A field study of the chemistry of dimethyl sulfide (DMS) was conducted on the island of Kiritimati (Christmas Island) during July and August, 1994. This island is located at 2°N, 157°W approximately 2000 km south of Hawaii. We obtained a very repeatable diurnal variation for both DMS and sulfur dioxide (SO2) during two 5-day and one 2-day experiments. Near sunrise DMS was about 200 pptv. It decreased to about 120 pptv by late afternoon. During the daytime SO2 increased from about 20 pptv to about 75 pptv. At night DMS increased and SO2 decreased almost linearly. About 62% of the DMS was converted to SO2. DMS was emitted from the ocean at an average flux of 3.7 × 1013 molecules m-2 s-1. The average dry deposition velocity of SO2 was 6.8 mm sec-1. Most of the SO2 appeared to be lost to the ocean although a comparable but not significantly larger flux to aerosol cannot be ruled out. Dimethyl sulfoxide was in the range 10 to 50 pptv with a mean of about 25 pptv. Dimethyl sulfone was in the range 0 to 15 pptv with a mean of about 3 pptv. There was no diurnal trend in either species. A much smaller fraction of the DMS was converted to dimethyl sulfone than dimethyl sulfoxide.

Bandy, A. R.; Thornton, D. C.; Blomquist, B. W.; Chen, S.; Wade, T. P.; Ianni, J. C.; Mitchell, G. M.; Nadler, W.

346

Ion and solvent diffusion and ion conduction of PC-DEC and PC-DME binary solvent electrolytes of LiN(SO 2CF 3) 2  

Microsoft Academic Search

Two binary mixed solvent systems typically used for lithium batteries were studied by measuring the self-diffusion coefficients of the solvent, lithium ion and anion, independently by using the multi-nuclear pulsed field-gradient spin-echo (PGSE) 1H, 7Li and 19F NMR method. One system was propylene carbonate (PC) and diethyl carbonate (DEC) system and the other binary system was PC and 1,2-dimethoxyethane (DME),

Kikuko Hayamizu; Yuichi Aihara

2004-01-01

347

Charge Transport in the Insulating State of (DMe-DCNQI)2Li above TSP: A Possible Fractional Charge Soliton Conduction with ±1\\/2e  

Microsoft Academic Search

A spin-Peierls system (DMe-DCNQI)2Li is studied with W-band electron paramagnetic resonance (EPR) (≈94 GHz) to unveil a charge transport mechanism in the insulating 4kF charge density wave state above TSP. The electron hopping between the neighbor DCNQI columns provides an additional broadening of the EPR linewidth, since the neighbor columns are generally nonequivalent to each other with respect to g

Maki Hiraoka; Hirokazu Sakamoto; Kenji Mizoguchi; Tatsuhisa Kato; Reizo Kato

2003-01-01

348

Spin soliton dynamics and pressure effects in the spin-Peierls system (DMe-DCNQI) 2M (M=Li, Ag)  

Microsoft Academic Search

(DMe-DCNQI)2M (M=Li, Ag) is a 14-filled spin-Peierls system. We study the spin\\/charge dynamics in the insulating state by EPR. The linewidth shows exponential dependence at T?Tsp. Further, pressure enhances mainly prefactor of the exponential dependences. These results are successfully understood in terms of the relaxation accompanied with the intercolumn hopping caused by the spin–orbit interaction both for the Li and

M. Hiraoka; H. Sakamoto; K. Mizoguchi; T. Kato; K. Furukawa; R. Kato; K. Hiraki; T. Takahashi

2004-01-01

349

Thermal conductivity of (DMe-DCNQI)2Li1-xCux (0<=x<=0.14) : Phonon propagation and the spin-Peierls lattice distortion  

Microsoft Academic Search

We have measured the thermal conductivity of organic molecular crystals (DMe-DCNQI)2Li1-xCux (0<=x<=0.14) over a wide temperature range between 4 and 250K . We observed the phonon contribution in the whole range measured. A phonon peak was observed near ˜20K . This peak denotes a crossover between the phonon mean free path that diverges as T-2 and the phonon specific heat

Kiyoshi Torizuka; Hiroyuki Tajima; Takashi Yamamoto

2005-01-01

350

General Ether Theory and Graviton Mass  

E-print Network

We introduce additional restriction into "general ether theory" - a generalization of Lorentz ether theory to gravity - which fixes the signs of the cosmological constants in this theory. This leads to an oscillating universe, thus, solves the cosmological horizon problem without inflation. We prove the equivalence of the Lagrangian of this theory with Logunov's "relativistic theory of gravity" with massive graviton and a variant of GR with four non-standard scalar fields and negative cosmological constant. We consider the remaining differences between these theories.

Ilja Schmelzer

2009-12-08

351

Crystalline imide/arylene ether copolymers  

NASA Technical Reports Server (NTRS)

Crystalline imide/arylene ether block copolymers are prepared by reacting anhydride terminated poly(amic acids) with amine terminated poly)arylene ethers) in polar aprotic solvents and chemically or thermally cyclodehydrating the resulting intermediate poly(amic acids). The block copolymers of the invention have one glass transition temperature or two, depending on the particular structure and/or the compatibility of the block units. Most of these crystalline block copolymers for tough, solvent resistant films with high tensile properties. While all of the copolymers produced by the present invention are crystalline, testing reveals that copolymers with longer imide blocks or higher imide content have increased crystallinity.

Jensen, Brian J. (inventor); Hergenrother, Paul M. (inventor); Bass, Robert G. (inventor)

1995-01-01

352

40 CFR 721.990 - 1,4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized.  

Code of Federal Regulations, 2013 CFR

...4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized...4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized...4-benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol,...

2013-07-01

353

40 CFR 721.990 - 1,4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized.  

Code of Federal Regulations, 2014 CFR

...4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized...4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized...4-benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol,...

2014-07-01

354

40 CFR 721.990 - 1,4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized.  

Code of Federal Regulations, 2012 CFR

...4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized...4-Benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol, cyclized...4-benzedicarboxylic acid, dimethyl ester, polymer with 1,4 - butanediol,...

2012-07-01

355

IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES  

SciTech Connect

This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

Jason M. Keith

2005-02-01

356

39. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, LOOKING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

39. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, LOOKING AT SOUTHWEST CORNER WITH BUILDING NO. 521, ETHER VAULT, AND BUILDING NO. 519-A, ETHER & ALOCOHL STORAGE TANKS, IN BACKGROUND RIGHT. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

357

Hydrogen-assisted catalytic ignition characteristics of different fuels  

SciTech Connect

Hydrogen-assisted catalytic ignition characteristics of methane (CH{sub 4}), n-butane (n-C{sub 4}H{sub 10}) and dimethyl ether (DME) were studied experimentally in a Pt-coated monolith catalytic reactor. It is concluded that DME has the lowest catalytic ignition temperature and the least required H{sub 2} flow, while CH{sub 4} has the highest catalytic ignition temperature and the highest required H{sub 2} flow among the three fuels. (author)

Zhong, Bei-Jing; Yang, Fan [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Yang, Qing-Tao [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); China Aerodynamics Research and Development Center, Mianyang 621000 (China)

2010-10-15

358

Insight into Selected Reactions in Low-Temperature Dimethyl Ether Combustion from Born-Oppenheimer Molecular Dynamics  

E-print Network

-Oppenheimer Molecular Dynamics Amity Andersen Accelrys, Inc., 10188 Telesis Court, Suite 100, San Diego, California(dO)H) and the first · OH of chain branching. The dissociation of HOOCH2OC HOOH exhibits non-RRKM behavior in its for low-temperature autoignition has been modeled after analogous mechanisms for low-temperature oxidation

Carter, Emily A.

359

A large amplitude flaring dMe star in the 1978 October 6B $?$-ray burst error box  

E-print Network

Spectroscopic observations provide evidence that the optical transient object observed in 1966 on archival plates of Sonneberg Observatory is a B=18.5 dMe star. For an assumed flare duration of 40 min. (or longer) the flare amplitude was $\\bigtriangleup$m$_{B}$ $\\approx$ 5.2 mag. If the recorded event was belonging to the class of 'fast' flares its amplitude could have reached 7-9 mag.. We estimate a lower limit for the optical flare energy release of 10$^{35}$ (d/100 pc)$^2$ erg/s. We discuss the positional coincidence of this large amplitude flaring star with the error box of the $\\gamma$-ray burst 1978 October 6B and conclude that the flare star is probably not related to the $\\gamma$-ray burst. The fact that no other optical flare was found from this object restricts their frequency to be less than 7$\\times$10$^{-4}$ h$^{-1}$ for amplitudes (in B) greater than 4.5 mag. Nevertheless, large amplitude flares constitute a serious background problem for the wide field search for possible optical counterparts of $\\gamma$-ray bursters.

J. Greiner; C. Motch

1994-09-16

360

A large amplitude flaring dMe star in the 1978 October 6B $\\gamma$-ray burst error box  

E-print Network

Spectroscopic observations provide evidence that the optical transient object observed in 1966 on archival plates of Sonneberg Observatory is a B=18.5 dMe star. For an assumed flare duration of 40 min. (or longer) the flare amplitude was \\bigtriangleupm_{B} \\approx 5.2 mag. If the recorded event was belonging to the class of 'fast' flares its amplitude could have reached 7-9 mag.. We estimate a lower limit for the optical flare energy release of 10^{35} (d/100 pc)^2 erg/s. We discuss the positional coincidence of this large amplitude flaring star with the error box of the \\gamma-ray burst 1978 October 6B and conclude that the flare star is probably not related to the \\gamma-ray burst. The fact that no other optical flare was found from this object restricts their frequency to be less than 7\\times10^{-4} h^{-1} for amplitudes (in B) greater than 4.5 mag. Nevertheless, large amplitude flares constitute a serious background problem for the wide field search for possible optical counterparts of \\gamma-ray burster...

Greiner, J; Greiner, J; Motch, C

1994-01-01

361

Ether- and ester-bound iso-diabolic acid and other lipids in members of acidobacteria subdivision 4.  

PubMed

Recently, iso-diabolic acid (13,16-dimethyl octacosanedioic acid) has been identified as a major membrane-spanning lipid of subdivisions 1 and 3 of the Acidobacteria, a highly diverse phylum within the Bacteria. This finding pointed to the Acidobacteria as a potential source for the bacterial glycerol dialkyl glycerol tetraethers that occur ubiquitously in peat, soil, lakes, and hot springs. Here, we examined the lipid composition of seven phylogenetically divergent strains of subdivision 4 of the Acidobacteria, a bacterial group that is commonly encountered in soil. Acid hydrolysis of total cell material released iso-diabolic acid derivatives in substantial quantities (11 to 48% of all fatty acids). In contrast to subdivisions 1 and 3 of the Acidobacteria, 6 out of the 7 species of subdivision 4 (excepting "Candidatus Chloracidobacterium thermophilum") contained iso-diabolic acid ether bound to a glycerol in larger fractional abundance than iso-diabolic acid itself. This is in agreement with the analysis of intact polar lipids (IPLs) by high-performance liquid chromatography-mass spectrometry (HPLC-MS), which showed the dominance of mixed ether-ester glycerides. iso-Diabolic acid-containing IPLs were not identified, because these IPLs are not released with a Bligh-Dyer extraction, as observed before when studying lipid compositions of subdivisions 1 and 3 of the Acidobacteria. The presence of ether bonds in the membrane lipids does not seem to be an adaptation to temperature, because the five mesophilic isolates contained a larger amount of ether lipids than the thermophile "Ca. Chloracidobacterium thermophilum." Furthermore, experiments with Pyrinomonas methylaliphatogenes did not reveal a major influence of growth temperature over the 50 to 69°C range. PMID:24928878

Sinninghe Damsté, Jaap S; Rijpstra, W Irene C; Hopmans, Ellen C; Foesel, Bärbel U; Wüst, Pia K; Overmann, Jörg; Tank, Marcus; Bryant, Donald A; Dunfield, Peter F; Houghton, Karen; Stott, Matthew B

2014-09-01

362

40 CFR 180.1083 - Dimethyl sulfoxide; exemption from the requirement of a tolerance.  

Code of Federal Regulations, 2013 CFR

...From Tolerances § 180.1083 Dimethyl sulfoxide; exemption from the requirement of a tolerance. Dimethyl sulfoxide (DMSO) [CAS Registry Number 67-68-5] is exempted from the requirement of a tolerance when used as an inert solvent or...

2013-07-01

363

40 CFR 180.1083 - Dimethyl sulfoxide; exemption from the requirement of a tolerance.  

Code of Federal Regulations, 2011 CFR

...From Tolerances § 180.1083 Dimethyl sulfoxide; exemption from the requirement of a tolerance. Dimethyl sulfoxide (DMSO) [CAS Registry Number 67-68-5] is exempted from the requirement of a tolerance when used as an inert solvent or...

2011-07-01

364

40 CFR 180.1083 - Dimethyl sulfoxide; exemption from the requirement of a tolerance.  

Code of Federal Regulations, 2010 CFR

...From Tolerances § 180.1083 Dimethyl sulfoxide; exemption from the requirement of a tolerance. Dimethyl sulfoxide (DMSO) [CAS Registry Number 67-68-5] is exempted from the requirement of a tolerance when used as an inert solvent or...

2010-07-01

365

40 CFR 180.1083 - Dimethyl sulfoxide; exemption from the requirement of a tolerance.  

Code of Federal Regulations, 2012 CFR

...From Tolerances § 180.1083 Dimethyl sulfoxide; exemption from the requirement of a tolerance. Dimethyl sulfoxide (DMSO) [CAS Registry Number 67-68-5] is exempted from the requirement of a tolerance when used as an inert solvent or...

2012-07-01

366

40 CFR 180.1083 - Dimethyl sulfoxide; exemption from the requirement of a tolerance.  

Code of Federal Regulations, 2014 CFR

...From Tolerances § 180.1083 Dimethyl sulfoxide; exemption from the requirement of a tolerance. Dimethyl sulfoxide (DMSO) [CAS Registry Number 67-68-5] is exempted from the requirement of a tolerance when used as an inert solvent or...

2014-07-01

367

Viscoelastic Behavior of Polyacrylonitrile/Dimethyl Sulfoxide Concentrated Solution with Water  

E-print Network

Viscoelastic Behavior of Polyacrylonitrile/Dimethyl Sulfoxide Concentrated Solution with Water: The spinnability and polydispersity of polyacrylonitrile/dimethyl sulfoxide (PAN/DMSO)/H2O spinning solutions; rheology; viscoelastic properties; water content INTRODUCTION Polyacrylonitrile (PAN)-based precursor

Pan, Ning

368

Low equivalent weight Friedel-Crafts cross-linked sulfonated poly(ether ether ketone)  

Microsoft Academic Search

Poly(ether ether ketone) (PEEK) was sulfonated by electrophillic aromatic substitution to produce a highly water soluble polymer. With an equivalent weight (EW) of 381g\\/eq, the polymer is capable of a proton conductivity of 0.2S\\/cm at 80°C and 100% relative humidity (RH). High proton conductivity in polymer electrolyte membranes is a key factor for optimum hydrogen fuel cell performance. Under testing

Stephen L. N. H. Rhoden; Clovis A. Linkous; Nahid Mohajeri; Diego J. Díaz; Paul Brooker; Darlene K. Slattery; James M. Fenton

2011-01-01

369

Synthesis and characterization of new poly(arylene ether)s based on dihydroxynaphthalene isomers  

Microsoft Academic Search

A series of new poly(arylene ether ketone)s and poly(arylene ether sulfone)s, obtained starting from dihydroxynaphthalene isomers, have been prepared by solution condensation polymerization. The polymers, having inherent viscosities from 0.20 to 0.77 dl g?1, have been obtained in quantitative yields, had excellent thermal stability as shown by 10% weight loss temperatures in nitrogen and air (above 460 and 430°C, respectively)

F. A. Bottino; G. Di Pasquale; N. Leonardi; A. Pollicino

1998-01-01

370

Development of Sulfonated Poly(ether-ether ketone)s for PEMFC and DMFC  

NASA Astrophysics Data System (ADS)

During the last two decades, extensive efforts have been made to develop alternative hydrocarbon-based polymer electrolyte membranes to overcome the drawbacks of the current widely used perfluorosulfonic acid Nafion. This chapter presents an overview of the synthesis, chemical properties, and polymer electrolyte fuel cell applications of new proton-conducting polymer electrolyte membranes based on sulfonated poly(arylene ether ether ketone) polymers and copolymers.

Kim, Dae Sik; Guiver, Michael D.

371

Biomonitoring Polybrominated Diphenyl Ethers in Lactating Women  

Technology Transfer Automated Retrieval System (TEKTRAN)

Breast milk is a valuable biological specimen for biomonitoring lipid-soluble polybrominated diphenyl ethers (PBDEs). The goal of this project was to determine the levels of PBDEs in breast milk of lactating women from the Seacoast region of New Hampshire and to examine potential relationships betw...

372

POLYBROMINATED DIPHENYL ETHERS IN SOUTHERN MISSISSIPPI CATFISH  

EPA Science Inventory

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in a wide variety of consumer products. Concerns surrounding these compounds are primarily due do their ubiquitous presence in the environment as well as in human tissue, such as milk, coupled with evidence indi...

373

POLYBROMINATED DIPHENYL ETHERS IN US SOILS  

EPA Science Inventory

Chemical analysis of thirty-three soil samples from 15 US states reveals Polybrominated Diphenyl Ethers (PBDEs), in every sample.PBDE concentrations rangefrom 0.09 to 1200 parts per billion by mass. These data are the first analysis of soil concentrations of PBDEs in soils from a...

374

Nonequivalence of ether theories and special relativity  

Microsoft Academic Search

The role played by clock synchronization procedures for coordinate transformations which account for time dilation and length contraction is discussed. Special relativity is here compared with the ether theory based on the Tangherlini transformations. These transformations are shown to be theoretically distinguishable from the Lorentz ones by means of an internal synchronization procedure which makes use of rods kept in

Gianfranco Spavieri

1986-01-01

375

Polybrominated diphenyl ether (PBDE) flame retardants  

Microsoft Academic Search

Polybrominated diphenyl ether, PBDE, flame retardants are now a world-wide pollution problem reaching even remote areas. They have been found to bioaccumulate and there are concerns over the health effects of exposure to PBDEs, they also have potential endocrine disrupting properties. They are lipophilic compounds so are easily removed from the aqueous environment and are predicted to sorb onto sediments

Frank Rahman; Katherine H Langford; Mark D Scrimshaw; John N Lester

2001-01-01

376

"Crown Ether" Synthesis: An Organic Laboratory Experiment.  

ERIC Educational Resources Information Center

This experiment is designed to acquaint the student with a macromolecular synthesis of a crown ether type compound. The starting materials are readily available and the product, a cyclic polyether, belongs to a class of compounds that has aroused the interest of chemist and biologist alike. (Author/BB)

Field, Kurt W.; And Others

1979-01-01

377

Polybrominated diphenyl ethers in California wastestreams  

Microsoft Academic Search

Polybrominated diphenyl ethers (PBDEs) are used in consumer products, including electronics, fabrics, and polyurethane foam. Exposures may occur during the products’ useful lifetime and also after the products’ disposal. A survey of California wastestreams (e-wastes, autoshredder waste and wastewater sewage sludge) attempted to assess the relative importance of these wastestreams as repositories of PBDEs. Based on measurements of PBDEs in

Myrto Petreas; Daniel Oros

2009-01-01

378

Certain glycol ethers eliminated from toxic chemical release reporting requirements  

SciTech Connect

Effective June 28, 1994, the U.S. Environmental Protection Agency (EPA) eliminated high molecular weight glycol ethers from the reporting requirements of section 313 of the Emergency Planning and Community Right-To-Know Act of 1986 (EPCRA). EPCRA (42 U.S.C. 11023) is also referred to as Title III of the Superfund Amendments and Reauthorization Act (SARA) of 1986. EPA redefined the glycol ethers category list of chemicals subject to reporting based on an EPA review of available human health data on short-chain glycol ethers. EPA is removing only the surfactant glycol ethers, which are high molecular weight glycol ethers, i.e., those with pendant alkyl groups and that typically have eight or more carbon atoms. The redefinition retains certain glycol ethers (i.e., ethylene glycol ethers where there are 1,2, or 3 repeating ethylene oxide groups) in the category. These are reasonably anticipated to cause adverse human health effects.

NONE

1994-09-01

379

Semi-volatile and particulate emissions from the combustion of alternative diesel fuels  

Microsoft Academic Search

Motor vehicle emissions are a major anthropogenic source of air pollution and contribute to the deterioration of urban air quality. In this paper, we report results of a laboratory investigation of particle formation from four different alternative diesel fuels, namely, compressed natural gas (CNG), dimethyl ether (DME), biodiesel, and diesel, under fuel-rich conditions in the temperature range of 800–1200°C at

Sukh Sidhu; John Graham; Richard Striebich

2001-01-01

380

Dimethyl sulfoxide enhances polyethylene glycol-mediated somatic cell fusion  

Microsoft Academic Search

The efficiency of fusion of human diploid cells by polyethylene glycol was greatly enhanced by addition of dimethyl sulfoxide. The extent of fusion was directly proportional to the concentrations of both of these compounds. At all except the highest concentrations, cell loss was moderate to minimal and perturbation of cell cycle function as measured by [3H]thymidine labeling indices and mitotic

T. H. Norwood; C. J. Zeigler; G. M. Martin

1976-01-01

381

Radiolabeled dimethyl branched long chain fatty acid for heart imaging  

DOEpatents

A radiolabeled long chain fatty acid for heart imaging that has dimethyl branching at one of the carbons of the chain which inhibits the extent to which oxidation can occur. The closer to the carboxyl the branching is positioned, the more limited the oxidation, thereby resulting in prolonged retention of the radiolabeled compound in the heart.

Knapp, Jr., Furn F. (Oak Ridge, TN); Goodman, Mark M. (Knoxville, TN); Kirsch, Gilbert (Woippy, FR)

1988-08-16

382

DIMETHYL AND METHYL HYDROGEN SULFATE IN THE ATMOSPHERE  

EPA Science Inventory

A novel technique of using the sample tube penetration profile of trace reactive gases has been applied to the sampling and indirect identification of candidate species through their diffusion coefficients. Laboratory studies of trace dimethyl and methyl hydrogen sulfate flow and...

383

21 CFR 524.660b - Dimethyl sulfoxide gel.  

Code of Federal Regulations, 2013 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660b Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2013-04-01

384

21 CFR 524.660b - Dimethyl sulfoxide gel.  

Code of Federal Regulations, 2010 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660b Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2010-04-01

385

21 CFR 524.660b - Dimethyl sulfoxide gel.  

Code of Federal Regulations, 2011 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660b Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2011-04-01

386

21 CFR 524.660b - Dimethyl sulfoxide gel.  

Code of Federal Regulations, 2012 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660b Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2012-04-01

387

21 CFR 524.660a - Dimethyl sulfoxide solution.  

Code of Federal Regulations, 2012 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660a Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2012-04-01

388

21 CFR 524.660a - Dimethyl sulfoxide solution.  

Code of Federal Regulations, 2013 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660a Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2013-04-01

389

21 CFR 524.660a - Dimethyl sulfoxide solution.  

Code of Federal Regulations, 2011 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660a Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2011-04-01

390

21 CFR 524.660a - Dimethyl sulfoxide solution.  

Code of Federal Regulations, 2010 CFR

...HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED...AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.660a Dimethyl...per day. Total duration of therapy should not exceed 30 days...per day. Total duration of therapy should not exceed 14...

2010-04-01

391

Chemistry of dimethyl sulfide in the equatorial Pacific atmosphere  

SciTech Connect

A field study of the chemistry of dimethyl sulfide (DMS) was conducted on the island of Kiritimati (Christmas Island) during July and August, 1994. This island is located at 2{degrees}N, 157{degrees}W approximately 2000km south of Hawaii. The authors obtained a very repeatable diurnal variation for both DMS and sulfur dioxide (SO{sub 2}) during two 5-day and one 2-day experiments. Near sunrise DMS was about 200pptv. It decreased to about 120 pptv by late afternoon. During the daytime SO{sub 2} increased from about 20 pptv to about 75 pptv. At night DMS increased and SO{sub 2} decreased almost linearly. About 62% of the DMS was converted to SO{sub 2}. DMS was emitted from the ocean at an average flux of 3.7 x 10{sup 13} molecules in m{sup {minus}2}s{sup {minus}1}. The average dry deposition velocity of SO{sub 2} was 6.8 mm sec{sup {minus}1} Most of the SO{sub 2} appeared to be lost to the ocean although a comparable but not significantly larger flux to aerosol cannot be ruled out. Dimethyl sulfoxide was in the range 10 to 50 pptv with a mean of about 25 pptv. Dimethyl sulfone was in the range 0 to 15 pptv with a mean of about 3 pptv. There was no diurnal trend in other species. A much smaller fraction of the DMS was converted to dimethyl sulfone than dimethyl sulfoxide. 27 refs., 2 fig., 2 tab.

Bandy, A.R.; Thornton, D.C.; Blomquist, B.W. [Drexel Univ., Philadelphia, PA (United States)] [and others] [Drexel Univ., Philadelphia, PA (United States); and others

1996-04-01

392

Ether bridge formation in loline alkaloid biosynthesis.  

PubMed

Lolines are potent insecticidal agents produced by endophytic fungi of cool-season grasses. These alkaloids are composed of a pyrrolizidine ring system and an uncommon ether bridge linking carbons 2 and 7. Previous results indicated that 1-aminopyrrolizidine was a pathway intermediate. We used RNA interference to knock down expression of lolO, resulting in the accumulation of an alkaloid identified as exo-1-acetamidopyrrolizidine based on high-resolution MS and NMR. Genomes of endophytes differing in alkaloid profiles were sequenced, revealing that those with mutated lolO accumulated exo-1-acetamidopyrrolizidine but no lolines. Heterologous expression of wild-type lolO complemented a lolO mutant, resulting in the production of N-acetylnorloline. These results indicated that the non-heme iron oxygenase, LolO, is required for ether bridge formation, probably through oxidation of exo-1-acetamidopyrrolizidine. PMID:24374065

Pan, Juan; Bhardwaj, Minakshi; Faulkner, Jerome R; Nagabhyru, Padmaja; Charlton, Nikki D; Higashi, Richard M; Miller, Anne-Frances; Young, Carolyn A; Grossman, Robert B; Schardl, Christopher L

2014-02-01

393

Cyclic ethers adsorbed on Ru(001)  

NASA Astrophysics Data System (ADS)

The three cyclic ethers 1,3-dioxane. 1,4-dioxane and 1,3,5-trioxane all exhibit multiple desorption states from Ru(001) between 200 and 310 K, in addition to the multilayer and metastable states at lower temperature. Most distinctive are the two low-temperature ?-states. which are similar in shape, position, and relative population for all three compounds. This suggests that these states are associated with configurations which are accessible to all three molecules. The data also indicate that there is some molecular decomposition to gaseous CO and H 2. 1,4-Dioxane yields the largest amounts of these decomposition products, suggesting that this molecule is most susceptible to surface-catalyzed decomposition. The desorption data for the three cyclic ethers are grossly similar to each other, and also to the straight-chain diethers which we have previously studied.

Walczak, M. M.; Thiel, P. A.

1990-11-01

394

Vacuum structure and ether-drift experiments  

E-print Network

In the data of the ether-drift experiments there might be sizable fluctuations superposed on the smooth sinusoidal modulations due to the Earth's rotation and orbital revolution. These fluctuations might reflect the stochastic nature of the underlying "quantum ether" and produce vanishing averages for all vectorial quantities extracted from a naive Fourier analysis of the data. By comparing the typical stability limits of the individual optical resonators with the amplitude of their relative frequency shift, the presently observed signal, rather than being spurious experimental noise, might also express fundamental properties of a physical vacuum similar to a superfluid in a turbulent state of motion. In this sense, the situation might be similar to the discovery of the CMBR that was first interpreted as mere instrumental noise.

M. Consoli; L. Pappalardo

2009-05-12

395

Synthesis and utility of fluorogenic acetoxymethyl ethers  

PubMed Central

Phenolic fluorophores such as fluorescein, Tokyo Green, resorufin, and their derivatives are workhorses of biological science. Acylating the phenolic hydroxyl group(s) in these fluorophores masks their fluorescence. The ensuing ester is a substrate for cellular esterases, which can restore fluorescence. These esters are, however, notoriously unstable to hydrolysis, severely compromising their utility. The acetoxymethyl (AM) group is an esterase-sensitive motif that can mask polar functionalities in small molecules. Here, we report on the use of AM ether groups to mask phenolic fluorophores. The resulting profluorophores have a desirable combination of low background fluorescence, high chemical stability, and high enzymatic reactivity, both in vitro and in cellulo. These simple phenyl ether-based profluorophores could supplement or supplant the use of phenyl esters for imaging biochemical and biological systems. PMID:21394227

Lavis, Luke D.; Chao, Tzu-Yuan

2011-01-01

396

Synthesis and utility of fluorogenic acetoxymethyl ethers.  

PubMed

Phenolic fluorophores such as fluorescein, Tokyo Green, resorufin, and their derivatives are workhorses of biological science. Acylating the phenolic hydroxyl group(s) in these fluorophores masks their fluorescence. The ensuing ester is a substrate for cellular esterases, which can restore fluorescence. These esters are, however, notoriously unstable to hydrolysis, severely compromising their utility. The acetoxymethyl (AM) group is an esterase-sensitive motif that can mask polar functionalities in small molecules. Here, we report on the use of AM ether groups to mask phenolic fluorophores. The resulting profluorophores have a desirable combination of low background fluorescence, high chemical stability, and high enzymatic reactivity, both in vitro and in cellulo. These simple phenyl ether-based profluorophores could supplement or supplant the use of phenyl esters for imaging biochemical and biological systems. PMID:21394227

Lavis, Luke D; Chao, Tzu-Yuan; Raines, Ronald T

2011-01-01

397

Ether bridge formation in loline alkaloid biosynthesis  

PubMed Central

Lolines are potent insecticidal agents produced by endophytic fungi of cool-season grasses. These alkaloids are composed of a pyrrolizidine ring system and an uncommon ether bridge linking carbons 2 and 7. Previous results indicated that 1-aminopyrrolizidine was a pathway intermediate. We used RNA interference to knock down expression of lolO, resulting in the accumulation of a novel alkaloid identified as exo-1-acetamidopyrrolizidine based on high-resolution MS and NMR. Genomes of endophytes differing in alkaloid profiles were sequenced, revealing that those with mutated lolO accumulated exo-1-acetamidopyrrolizidine but no lolines. Heterologous expression of wild-type lolO complemented a lolO mutant, resulting in the production of N-acetylnorloline. These results indicated that the non-heme iron oxygenase, LolO, is required for ether bridge formation, probably through oxidation of exo-1-acetamidopyrrolizidine. PMID:24374065

Pan, Juan; Bhardwaj, Minakshi; Faulkner, Jerome R.; Nagabhyru, Padmaja; Charlton, Nikki D.; Higashi, Richard M.; Miller, Anne-Frances; Young, Carolyn A.; Grossman, Robert B.; Schardl, Christopher L.

2014-01-01

398

Poly(Arylene Ether Imidazole) Surface Films  

NASA Technical Reports Server (NTRS)

Films adhere well to some substrates, provide smooth surfaces, and facilitate release from molds. Thin films of thermoplastic poly(arylene ether imidazole)s (PAEI's) particularly suitable for use as surface modifiers for graphite/epoxy or graphite/bismaleimide composite panels. Molecule of PAEI includes imidazole groups along its backbone that co-cure with epoxies or bismaleimides during processing. Films thermally stable and resistant to bombardment by energetic electrons.

Connell, John W.; Towell, Timothy W.; Tompkins, Stephen S.

1993-01-01

399

Solvation of dichlorocarbene: complexation with aryl ethers.  

PubMed

Dichlorocarbene (CCl(2)), generated by laser flash photolysis of dichlorodiazirine, formed pi- and O-ylidic complexes with aromatic ethers such as anisole, 1,3-dimethoxybenzene, 1,3,5-trimethoxybenzene, dibenzofuran, and dibenzo-18-crown-6 and with the aromatic ester phenyl acetate. These complexes were visualized by UV-vis spectroscopy, and they retarded the addition of CCl(2) to tetramethylethylene by factors of 18-152. Computational studies based on density functional theory provided structures and energetics for the transient species and rationalized their absorption spectra. Complexes were not observed between CCl(2) and simple, nonaromatic ethers such as THF, dioxane, or 18-crown-6, nor did these ethers much affect the addition rate of CCl(2) to tetramethylethylene. Computations also suggested that pi-complexes of CCl(2) and, e.g., mesitylene and durene, were energetically reasonable transients. Although these species were not detected spectroscopically, the aromatic compounds did slow the addition of CCl(2) to tetramethylethylene by factors of 15 and 31, respectively. PMID:19877654

Moss, Robert A; Wang, Lei; Odorisio, Christina M; Zhang, Min; Krogh-Jespersen, Karsten

2010-01-14

400

Chemistry and adhesive properties of poly(arylene ether)s containing heterocyclic units  

NASA Technical Reports Server (NTRS)

Novel poly(arylene ether)s containing heterocyclic units were prepared, characterized, and evaluated as adhesives and composite matrices. The polymers were prepared by reacting a heterocyclic bisphenol with an activated aromatic dihalide in a polar aprotic solvent, using potassium carbonate. The polymerizations were generally carried out in N,N-dimethylacetamide at 155 C. In some cases, where the polymers were semicrystalline, higher temperatures and thus higher boiling solvents were necessary to keep the polymers in solution. Heterocyclic rings incorporated into the poly(arylene ether) backbone include phenylquinoxaline, phenylimidazole, benzimidazole, benzoxazole, 1,3,4-oxadiazole, and 1,2,4-triazole. The polymers were characterized by differential scanning calorimetry, solution viscosity, X-ray diffraction, thin film, and adhesive and (in some cases) composite properties. The glass transition temperatures, crystalline melt temperature, solubility, and mechanical properties varied depending upon the heterocyclic ring. The chemistry and properties of these materials are discussed.

Connell, John W.

1991-01-01

401

Synthesis and characteristics of polyarylene ether sulfones  

NASA Technical Reports Server (NTRS)

A method utilizing potassium carbonate/dimethyl acetamide, as base and solvent respectively, was used for the synthesis of several homopolymers and copolymers derived from various bisphenols. It is demonstrated that this method deviates from simple second order kinetics; this deviation being due to the heterogeneous nature of the reaction. Also, it is shown that a liquid induced crystallization process can improve the solvent resistance of these polymers. Finally, a Monte Carlo simulation of the triad distribution of monomers in nonequilibrium copolycondensation is discussed.

Viswanathan, R.; Johnson, B. C.; Ward, T. C.; Mcgrath, J. E.

1981-01-01

402

Poly (Aryl Ether Ketones) Bearing Alkylated Side Chains  

NASA Technical Reports Server (NTRS)

This invention relates generally to poly(aryl ether ketones) bearing alkylated side chains. It relates particularly to soluble, thermally stable. low dielectric poly(aryl ether ketones) with alkylated side chains and especially to films and coatings thereof. These poly(aryl ether ketones) have a structural formula wherein Y is selected from the group consisting of CF3 and CH3; and wherein R is C(sub n)H(sub (2n+1)) and n = 11-18.

Cassidy, Patrick E. (Inventor); Fitch, John W., III (Inventor); Gronewald, Scott D. (Inventor); St.Clair, Ann K. (Inventor); Stoakley, Diane M. (Inventor)

2002-01-01

403

Vinyl ether resist system for UV-cured nanoimprint lithography  

Microsoft Academic Search

Cationic curing of vinyl ethers for step-and-flash nanoimprint lithography is described. Photochemical acid generators for use in the vinyl ether formulation were carefully selected on the basis of their solubility in neat lipophilic vinyl ether. Our favorite acid generators include diphenyltolylsulfonium triflate, CGI261, CGI1905, CGI1906, and CGI1907. The CGI1900 series is sensitive to i-line irradiation while the former two can

Hiroshi Ito; Frances A. Houle; Mark W. Hart; Rick A. DiPietro

2006-01-01

404

Brønsted Acid Catalyzed ?'-Functionalization of Silylenol Ethers with Indoles.  

PubMed

A new method which enables carbon-carbon bond formation at the ?'-position of silylenol ethers by using catalytic amounts of pyridinium triflate is reported. This chemistry successfully produces, structurally challenging, highly substituted indole-containing silylenol ethers in excellent yields with complete regiocontrol, presumably through silyloxyallyl cation intermediates. Despite the use of Brønsted acid, the silylenol ether moiety does not undergo protodesilylation, thus underscoring the very mild reaction conditions. PMID:25694101

Ayala, Caitlan E; Dange, Nitin S; Fronczek, Frank R; Kartika, Rendy

2015-04-01

405

Synthesis of poly(vinyl ether)s with perfluoroalkyl pendant groups  

Microsoft Academic Search

2-Perfluoro(alkyl)ethyl vinyl ethers, F(CF2)nCH2CH2OCHCH2, (n = 6 or 8), were synthesized and polymerized by means of cationic initiators (HI\\/ZnI2 and CF3SO3H\\/(CH3)2S). The perfluorohexyl-substituted poly(vinyl ether) is completely amorphous. The polymer with perfluorooctyl segments shows side chain crystallization with a disordering transition. For the corresponding perfluorooctyl monomer a liquid-crystalline phase was observed before melting. Copolymerization experiments of the flurocarbon-segmented monomers with

Jens Höpken; Martin Möller; Myongsoo Lee; Virgil Percec

1992-01-01

406

Divinyl ether synthase gene, and protein and uses thereof  

DOEpatents

The present invention relates to divinyl ether synthase genes, proteins, and methods of their use. The present invention encompasses both native and recombinant wild-type forms of the synthase, as well as mutants and variant forms, some of which possess altered characteristics relative to the wild-type synthase. The present invention also relates to methods of using divinyl ether synthase genes and proteins, including in their expression in transgenic organisms and in the production of divinyl ether fatty acids, and to methods of suing divinyl ether fatty acids, including in the protection of plants from pathogens.

Howe, Gregg A.; Itoh, Aya

2006-12-26

407

Divinyl ether synthase gene and protein, and uses thereof  

DOEpatents

The present invention relates to divinyl ether synthase genes, proteins, and methods of their use. The present invention encompasses both native and recombinant wild-type forms of the synthase, as well as mutants and variant forms, some of which possess altered characteristics relative to the wild-type synthase. The present invention also relates to methods of using divinyl ether synthase genes and proteins, including in their expression in transgenic organisms and in the production of divinyl ether fatty acids, and to methods of suing divinyl ether fatty acids, including in the protection of plants from pathogens.

Howe, Gregg A. (East Lansing, MI); Itoh, Aya (Tsuruoka, JP)

2011-09-13

408

TIME-RESOLVED PROPERTIES AND GLOBAL TRENDS IN dMe FLARES FROM SIMULTANEOUS PHOTOMETRY AND SPECTRA  

SciTech Connect

We present a homogeneous analysis of line and continuum emission from simultaneous high-cadence spectra and photometry covering near-ultraviolet and optical wavelengths for 20 M dwarf flares. These data were obtained to study the white-light continuum components at bluer and redder wavelengths than the Balmer jump. Our goals were to break the degeneracy between emission mechanisms that have been fit to broadband colors of flares and to provide constraints for radiative-hydrodynamic (RHD) flare models that seek to reproduce the white-light flare emission. The main results from the analysis are the following: (1) the detection of Balmer continuum (in emission) that is present during all flares and with a wide range of relative contributions to the continuum flux at bluer wavelengths than the Balmer jump; (2) a blue continuum at flare maximum that is linearly decreasing with wavelength from {lambda} = 4000-4800 A, indicative of hot, blackbody emission with typical temperatures of T{sub BB} {approx} 9000-14, 000 K; (3) a redder continuum apparent at wavelengths longer than H{beta} ({lambda} {approx}> 4900 A) which becomes relatively more important to the energy budget during the late gradual phase. The hot blackbody component and redder continuum component have been detected in previous studies of flares. However, we have found that although the hot blackbody emission component is relatively well-represented by a featureless, single-temperature Planck function, this component includes absorption features and has a continuum shape strikingly similar to the spectrum of an A-type star as directly observed in our flare spectra. New model constraints are presented for the time evolution among the hydrogen Balmer lines and between Ca II K and the blackbody continuum emission. We calculate Balmer jump flux ratios and compare to the solar-type flare heating predictions from RHD models. The model ratios are too large and the blue-optical ({lambda} = 4000-4800 A) slopes are too red in both the impulsive and gradual decay phases of all 20 flares. This discrepancy implies that further work is needed to understand the heating at high column mass during dMe flares.

Kowalski, Adam F.; Hawley, Suzanne L.; Davenport, James R. A. [Astronomy Department, University of Washington, Box 351580, U.W. Seattle, WA 98195-1580 (United States); Wisniewski, John P. [HL Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks Street, Norman, OK 73019 (United States); Osten, Rachel A. [Space Telescope Science Institute, 3700 San Martin Drive Baltimore, MD 21218 (United States); Hilton, Eric J. [Universe Sandbox, Seattle, WA (United States); Holtzman, Jon A. [Department of Astronomy, New Mexico State University, Box 30001, Las Cruces, NM 88003 (United States); Schmidt, Sarah J., E-mail: adam.f.kowalski@nasa.gov [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

2013-07-15

409

Recently, crown ethers have become very popular extractants for metal ions separation from aqueous solution. Crown ethers form complex with metal ion.  

E-print Network

Recently, crown ethers have become very popular extractants for metal ions separation from aqueous solution. Crown ethers form complex with metal ion. Selection of suitable crown ether and metal ion depends on various factors such as proper spatial orientation of the crown ether oxygen dipole in the direction

Singh, Jayant K.

410

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Disubstituted benzene ether, polymer with substituted phenol...Substances § 721.1580 Disubstituted benzene ether, polymer with substituted phenol...generically identified as disubstituted benzene ether, polymer with substituted...

2013-07-01

411

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Disubstituted benzene ether, polymer with substituted phenol...Substances § 721.1580 Disubstituted benzene ether, polymer with substituted phenol...generically identified as disubstituted benzene ether, polymer with substituted...

2014-07-01

412

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Disubstituted benzene ether, polymer with substituted phenol...Substances § 721.1580 Disubstituted benzene ether, polymer with substituted phenol...generically identified as disubstituted benzene ether, polymer with substituted...

2011-07-01

413

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Disubstituted benzene ether, polymer with substituted phenol...Substances § 721.1580 Disubstituted benzene ether, polymer with substituted phenol...generically identified as disubstituted benzene ether, polymer with substituted...

2010-07-01

414

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Disubstituted benzene ether, polymer with substituted phenol...Substances § 721.1580 Disubstituted benzene ether, polymer with substituted phenol...generically identified as disubstituted benzene ether, polymer with substituted...

2012-07-01

415

Hydration of 2-cyanoethyl ethers of acetylenic alcohols. Alcoholysis of the hydration products  

Microsoft Academic Search

1.The hydration of 2-cyanoethyl ethers of various acetylenic alcohols was carried out.2.The resulting 2-cyanoethyl ethers of a-hydroxy ketones were converted into the corresponding 2-(methoxycarbonyl) ethyl ethers.

I. N. Nazarov; G. A. Shvekhgeimer

1958-01-01

416

40 CFR 721.10605 - Polyoxyalkylene ether, polymer with aliphatic diisocyanate, homopolymer, alkanol-blocked (generic).  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Polyoxyalkylene ether, polymer with aliphatic diisocyanate, homopolymer...721.10605 Polyoxyalkylene ether, polymer with aliphatic diisocyanate, homopolymer...generically as polyoxyalkylene ether, polymer with aliphatic diisocyanate,...

2014-07-01

417

40 CFR 721.10518 - Diethylene glycol, polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and...  

Code of Federal Regulations, 2014 CFR

...polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked...polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked...polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and...

2014-07-01

418

40 CFR 721.10518 - Diethylene glycol, polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and...  

Code of Federal Regulations, 2013 CFR

...polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked...polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked...polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and...

2013-07-01

419

40 CFR 721.10017 - Amine terminated bisphenol A diglycidyl ether polymer (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Amine terminated bisphenol A diglycidyl ether polymer (generic...Substances § 721.10017 Amine terminated bisphenol A diglycidyl ether polymer (generic...identified generically as amine terminated bisphenol A diglycidyl ether polymer...

2012-07-01

420

40 CFR 721.10017 - Amine terminated bisphenol A diglycidyl ether polymer (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Amine terminated bisphenol A diglycidyl ether polymer (generic...Substances § 721.10017 Amine terminated bisphenol A diglycidyl ether polymer (generic...identified generically as amine terminated bisphenol A diglycidyl ether polymer...

2013-07-01

421

40 CFR 721.10017 - Amine terminated bisphenol A diglycidyl ether polymer (generic).  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Amine terminated bisphenol A diglycidyl ether polymer (generic...Substances § 721.10017 Amine terminated bisphenol A diglycidyl ether polymer (generic...identified generically as amine terminated bisphenol A diglycidyl ether polymer...

2014-07-01

422

75 FR 28804 - An Exposure Assessment of Polybrominated Diphenyl Ethers (PBDEs)  

Federal Register 2010, 2011, 2012, 2013, 2014

...Exposure Assessment of Polybrominated Diphenyl Ethers (PBDEs) AGENCY: Environmental...Exposure Assessment of Polybrominated Diphenyl Ethers'' (EPA/600/R-08...identified in EPA's 2006 Polybrominated Diphenyl Ethers (PBDEs) Project...

2010-05-24

423

40 CFR 721.10017 - Amine terminated bisphenol A diglycidyl ether polymer (generic).  

Code of Federal Regulations, 2010 CFR

...terminated bisphenol A diglycidyl ether polymer (generic). 721.10017 Section...terminated bisphenol A diglycidyl ether polymer (generic). (a) Chemical substances...terminated bisphenol A diglycidyl ether polymer (PMNs P-01-257/258/259...

2010-07-01

424

Asymmetric hydrolysis of dimethyl 3-phenylglutarate catalyzed by Lecitase Ultra ®  

Microsoft Academic Search

The asymmetric hydrolysis of dimethyl 3-phenylglutarate (1) by different immobilized preparations of a phospholipase A1 (Lecitase Ultra (LECI)) at pH 7 and 25°C has been studied. Agarose beads coated with octyl, cyanogen bromide (CNBr), polyethylenimine (PEI) or glyoxyl groups were used as supports for the immobilization of LECI. The different derivatives behaved very differently in terms of activity, discrimination between

Zaida Cabrera; Gloria Fernandez-Lorente; Jose M. Palomo; Jose M. Guisan; Roberto Fernandez-Lafuente

2008-01-01

425

Dimethyl Sulfoxide Suppresses Apoptosis in Burkitt's Lymphoma Cells  

Microsoft Academic Search

Previous reports have suggested that dimethyl sulfoxide (DMSO) may be a useful reversible G1 arresting agent for synchronizing Raji Burkitt's lymphoma cells (K. Takase et al. (1992) Cell Growth Differ. 3, 515-521; M. Sawai et al. (1990) Exp. Cell Res. 187, 4-10). We have therefore critically evaluated several aspects of DMSO's effects using Daudi and Ramos Burkitt's lymphoma (BL) cells.

Ching-Kow E. Lin; Cosmas I. Kalunta; Fun-Shan Chen; Tam Thuan Nguyen; John S. Kaptein; Pramod M. Lad

1995-01-01

426

Photodegradation of dimethyl and di-2-ethylhexyl phthalates  

E-print Network

hexane and water was photodegraded by a 450-watt mercury vapor arc lamp in a quartz-cell. Several unidentified products were formed during the hexane solution photolysis. Aqueous solutions of DEHP were not good models for the study of phthalate photo...- lysis because of the very poor water solubility of DEHP. Dimethyl phthalate (DMP) was a better model. DEHP was photodegraded more efficiently than DMP in aqueous solution. Relative efficiencies of photodegradation of DMP using filters were quartz...

Hammargren, Thomas Fredric

1976-01-01

427

Dimethyl sulfoxide inhibits histamine release induced by various chemicals  

Microsoft Academic Search

Dimethyl sulfoxide was found to inhibit histamine release induced by compound 48\\/80 at concentrations ranging from 0.6 to 10%. At higher concentrations (20 and 40%) the substance caused histamine release by itself. Heat inactivation at 50°C of the mast cells did not prevent this release, suggesting a lytic mechanism for this action and this was further proved by the trypan

L. Candussio; F. B. Klugmann; G. Decorti; S. Bevilacqua; L. Baldini

1987-01-01

428

Diapause Prevention Effect of Bombyx mori by Dimethyl Sulfoxide  

PubMed Central

HCl treatment has been, for about 80 years, the primary method for the prevention of entry into embryonic diapauses of Bombyx mori. This is because no method is as effective as the HCl treatment. In this study, we discovered that dimethyl sulfoxide (DMSO) prevented entry into the diapause of the silkworm, Bombyx mori. The effect of diapause prevention was 78% as a result of treatment with 100% DMSO concentration, and the effect was comparable to that of the HCl treatment. In contrast, in the case of non-diapause eggs, hatchability was decreased by DMSO in a concentration-dependent manner. The effect of DMSO was restricted within 24 hours after oviposition of diapause eggs, and the critical period was slightly shorter than the effective period of the HCl treatment. DMSO analogs, such as dimethyl formamide (DMF) and dimethyl sulfide (DMS), did little preventive effect against the diapause. Furthermore, we also investigated the permeation effects of chemical compounds by DMSO. When treated with an inhibitor of protein kinase CK2 (CK2) dissolved in DMSO, the prevention rate of the diapause was less than 40%. This means that the inhibition effect by the CK2 inhibitor was the inhibition of embryonic development after diapause prevention by DMSO. These data suggest that DMSO has the effects of preventing from entering into the diapause and permeation of chemicals into diapause eggs. PMID:23675522

Yamamoto, Takayuki; Mase, Keisuke; Sawada, Hiroshi

2013-01-01

429

The Mouse that Roared: A Superflare from the dMe Flare Star EV Lac detected by Swift and Konus-Wind  

E-print Network

We report on a large stellar flare from the nearby dMe flare star EV Lac observed by the Swift and Konus-Wind satellites and the Liverpool Telescope. It is the first large stellar flare from a dMe flare star to result in a Swift trigger based on its hard X-ray intensity. Its peak f_X from 0.3--100 keV of 5.3x10^-8 erg/cm2/s is nearly 7000 times larger than the star's quiescent coronal flux, and the change in magnitude in the white filter is >4.7. This flare also caused a transient increase in EV Lac's bolometric luminosity (L_bol) during the early stages of the flare, with a peak estimated L_X/L_bol ~3.1. We apply flare loop hydrodynamic modeling to the plasma parameter temporal changes to derive a loop semi-length of l/Rstar =0.37 +/-0.07. The soft X-ray spectrum of the flare reveals evidence of iron Kalpha emission at 6.4 keV. We model the Kalpha emission as fluorescence from the hot flare source irradiating the photospheric iron, and derive loop heights of h/Rstar=0.1, consistent within factors of a few wi...

Osten, Rachel A; Drake, Stephen; Tueller, Jack; Cummings, Jay; Krimm, Hans; Pye, John; Pal'shin, Valentin; Golenetskii, Sergei; Reale, Fabio; Oates, Samantha R; Page, Mat J; Melandri, Andrea

2010-01-01

430

Carbon-carbon bond cleavage of 1,2-hydroxy ethers b7 vanadium(V) dipicolinate complexes  

SciTech Connect

The development of alternatives to current petroleum-based fuels and chemicals is becoming increasingly important due to concerns over climate change, growing world energy demand, and energy security issues. Using non-food derived biomass to produce renewable feedstocks for chemicals and fuels is a particularly attractive possibility. However, the majority of biomass is in the form of lignocellulose, which is often not fully utilized due to difficulties associated with breaking down both lignin and cellulose. Recently, a number of methods have been reported to transform cellulose directly into more valuable materials such as glucose, sorbitol, 5-(chloromethyl)furfural, and ethylene glycol. Less progress has been made with selective transformations of lignin, which is typically treated in paper and forest industries by kraft pulping (sodium hydroxide/sodium sulfide) or incineration. Our group has begun investigating aerobic oxidative C-C bond cleavage catalyzed by dipicolinate vanadium complexes, with the idea that a selective C-C cleavage reaction of this type could be used to produce valuable chemicals or intermediates from cellulose or lignin. Lignin is a randomized polymer containing methoxylated phenoxy propanol units. A number of different linkages occur naturally; one of the most prevalent is the {beta}-O-4 linkage shown in Figure 1, containing a C-C bond with 1,2-hydroxy ether substituents. While the oxidative C-C bond cleavage of 1,2-diols has been reported for a number of metals, including vanadium, iron, manganese, ruthenium, and polyoxometalate complexes, C-C bond cleavage of 1,2-hydroxy ethers is much less common. We report herein vanadium-mediated cleavage of C-C bonds between alcohol and ether functionalities in several lignin model complexes. In order to explore the scope and potential of vanadium complexes to effect oxidative C-C bond cleavage in 1,2-hydroxy ethers, we examined the reactivity of the lignin model complexes pinacol monomethyl ether (A), 2-phenoxyethanol (B), and 1,2-diphenyl-2-methoxyethanol (C) (Figure 1). Reaction of (dipic)V{sup V}(O)O{sup i}Pr (1a) or (dipic)V{sup v}(O)OEt (lb) with A, B, or C in acetonitrile yielded new vanadium(V) complexes where the alcohol-ether ligand was bound in a chelating fashion. From the reaction of 1b with pinacol monomethyl ether (A) in acetonitrile solution, (dipic)V{sup v}(O)(pinOMe) (2) (PinOMe = 2,3-dimethyl-3-methoxy-2-butanoxide) was isolated in 61 % yield. Reaction of 1b with 2-phenoxyethanol (B) in acetonitrile gave the new complex (dipic)V{sup v}(O)(OPE) (3) (OPE = 2-phenoxyethoxide), which was isolated in 76% yield. In a similar fashion, 1a reacted with 1,2-diphenyl-2-methoxyethanol (C) to give (dipic)V(O)(DPME) (4) (DPME = 1,2-diphenyl-2-methoxyethoxide), which was isolated in 39% yield. Complexes 2, 3, and 4 were characterized by {sup 1}H NMR and IR spectroscopy, elemental analysis, and X-ray crystallography. Compared to the previously reported vanadium(V) pinacolate complex (dipic)V(O)(pinOH) the X-ray structure of complex 2 reveals a slightly shorter V = O bond, 1.573(2) {angstrom} vs 1.588(2) {angstrom} for the pinOH structure. Complexes 3 and 4 display similar vanadium oxo bond distances of 1.568(2) {angstrom} and 1.576(2) {angstrom}, respectively. All three complexes show longer bonds to the ether-oxygen trans to the oxo (2.388(2) {angstrom} for 2, 2.547(2) {angstrom} for 3, and 2.438(2) {angstrom} for 4) than to the hydroxy-oxygen in the pinOH structure (2.252(2) {angstrom}).

Hanson, Susan K [Los Alamos National Laboratory; Gordon, John C [Los Alamos National Laboratory; Thorn, David L [Los Alamos National Laboratory; Scott, Brian L [Los Alamos National Laboratory; Baker, R Tom [Los Alamos National Laboratory

2009-01-01

431

Toxic effects of decabromodiphenyl ether (BDE-209) on human embryonic kidney cells  

PubMed Central

Polybrominated diphenyl ethers (PBDEs) are widely used as flame-retardant additives in consumer and household products and can escape into the environment over time. PBDEs have become a global environmental organic pollutant due to the properties of persistence, toxicity, and bioaccumulation. The well-studied toxic effects of PBDEs mainly include thyroid hormone disruption and neurotoxicity. There is no consistent conclusions on the carcinogenic potential of PBDEs to date. Here, we explored the toxic effects of BDE-209 on human embryonic kidney cells (HEK293T). The comparison of the gene expression profiles of HEK293T cells with BDE-209 treatment and the negative control found that BDE-209 exposure may alter nucleosome organization through significantly changing the expression of histone gene clusters. The remodeled chromatin structure could further disturb systemic lupus erythematosus as one of the toxic effects of BDE-209. Additionally, gene sets of different cancer modules are positively correlated with BDE-209 exposure. This suggests that BDE-209 has carcinogenic potential for a variety of tumors. Collectively, BDE-209 has a broader toxicity not limited to disruption of thyroid hormone-related biological processes. Notably, the toxic effects of BDE-209 dissolved in dimethyl sulfoxide (DMSO) is not the simply additive effects of BDE-209 and DMSO alone. PMID:24834073

Li, Min; Liu, Zhenping; Gu, Liang; Yin, Rong; Li, Huarong; Zhang, Xiaobai; Cao, Tongcheng; Jiang, Cizhong

2014-01-01

432

Toxic effects of decabromodiphenyl ether (BDE-209) on human embryonic kidney cells.  

PubMed

Polybrominated diphenyl ethers (PBDEs) are widely used as flame-retardant additives in consumer and household products and can escape into the environment over time. PBDEs have become a global environmental organic pollutant due to the properties of persistence, toxicity, and bioaccumulation. The well-studied toxic effects of PBDEs mainly include thyroid hormone disruption and neurotoxicity. There is no consistent conclusions on the carcinogenic potential of PBDEs to date. Here, we explored the toxic effects of BDE-209 on human embryonic kidney cells (HEK293T). The comparison of the gene expression profiles of HEK293T cells with BDE-209 treatment and the negative control found that BDE-209 exposure may alter nucleosome organization through significantly changing the expression of histone gene clusters. The remodeled chromatin structure could further disturb systemic lupus erythematosus as one of the toxic effects of BDE-209. Additionally, gene sets of different cancer modules are positively correlated with BDE-209 exposure. This suggests that BDE-209 has carcinogenic potential for a variety of tumors. Collectively, BDE-209 has a broader toxicity not limited to disruption of thyroid hormone-related biological processes. Notably, the toxic effects of BDE-209 dissolved in dimethyl sulfoxide (DMSO) is not the simply additive effects of BDE-209 and DMSO alone. PMID:24834073

Li, Min; Liu, Zhenping; Gu, Liang; Yin, Rong; Li, Huarong; Zhang, Xiaobai; Cao, Tongcheng; Jiang, Cizhong

2014-01-01

433

Solubilization of 4,4'-dibromodiphenyl ether under combined TX-100 and cosolvents.  

PubMed

This paper is focused on the selection of cosolvents in the remediation of contaminated soils. The aim of this study was to investigate the combined effects of Triton X-100 (TX-100) and different cosolvents on the solubilization behavior of 4,4'-dibromodiphenyl ether (BDE-15) and the washing of BDE-15 from a contaminated soil. (1)H NMR spectroscopies were used to elucidate the interactions among TX-100, cosolvents, and BDE-15 in aqueous micellar solution. Results showed that the solubility of BDE-15 was enhanced by the observed synergism among TX-100, BDE-15, and cosolvents, and the TX-100/dimethyl sulfoxide (DMSO) system exhibited the best performance in the solubilization of BDE-15. Similar synergism was further evidenced in the washing of BDE-15 from a contaminated soil. With 10 % (v/v) DMSO and 6.4 mM TX-100 solution added, considerable synergistic effect was achieved in TX-100/DMSO system, leading to the highest removal efficiency (92.9 %) of BDE-15 from the soil, relative to that of 67.3 % with TX-100 alone at the same concentration. PMID:25269841

Yang, Xingjian; Lu, Guining; Wang, Rui; Guo, Chuling; Zhang, Hongliang; Dang, Zhi

2015-03-01

434

Phenylethynyl-Terminated Poly(Arylene Ethers)  

NASA Technical Reports Server (NTRS)

Phenylethynyl-terminated poly(arylene ethers) synthesized in wide range of molecular weights by adjusting monomer ratios and adding appropriate amounts of 4-phenylethynyl-4'-fluorobenzophenone to monomers to end-cap oligomers during polymerization. Have low molecular weights and low melt viscosities, and are easily processed as adhesives, composites, and moldings. Thermally cured to provide materials that are crosslinked and insoluble in common organic solvents. Exhibit increased resistance to solvents, greater tensile moduli, and better high-temperature properties. Useful as adhesives, composite matrices, and moldings, especially in applications in which combination of toughness and resistance to solvents needed.

Jensen, Brian J.; Bryant, Robert G.; Hergenrother, Paul M.

1994-01-01

435

Fluorinated Poly(Phenylene Ether Ketones)  

NASA Technical Reports Server (NTRS)

Fluorinated poly(phenylene ether ketones) are colorless, transparent, low-dielectric-constant, highly thermally stable polymers. Particularly suitable for use as film and coating materials in electronic and thermal-control applications such as; passivant insulating coats and interlevel dielectrics in microelectronic circuits, or as protective transparent coats on solar cells or mirrors. Solubility and transparency of 12F-PEK along with its lower dielectric constant and other properties make it more useful as dielectric film and coating material in many applications.

St. Clair, Anne K.; Cassidy, Patrick E.; Tullos, Gordon L.

1994-01-01

436

Diisopropyl ether syntheses from crude acetone  

Microsoft Academic Search

Diisopropyl ether (DIPE) may be generated via a novel, two-step process from crude, by-product, acetone streams through initial\\u000a acetone hydrogenation over a bulk-metal, nickel-rich catalyst to give isopropanol (IPA), followed by dehydration of said IPA\\u000a intermediate in the presence of an acidic, large-pore zeolite catalyst. Three classes of acidic zeolite have proven effective\\u000a for selective DIPE production, including Beta-zeolite, ?-zeolites

John F. Knifton; Pei-Shing E. Dai

1999-01-01

437

Methyl Tertiary Butyl Ether (MTBE): Drinking Water  

NSDL National Science Digital Library

MTBE, a gasoline oxygenater additive, has been detected in ground water sources throughout different parts of the country. These ground water sources are often the source of drinking water, and the presence of methyl tertiary butyl ether in even minute quantities can make the water undrinkable. Research to date has not conclusively identified any quantitative level at which serious health risks may occur. This site provides information on behalf of the Environmental Protection Agency on the concerns and occurence of MTBE in drinking water.

438

Sulfonated poly(ether ether ketone)-based composite membrane for polymer electrolyte membrane fuel cells  

Microsoft Academic Search

The solid proton conductor zirconium phosphate sulfophenylenphosphonate of composition Zr(HPO4)0.65(SPP)1.35 where SPP denotes metasulfophenylenphosphonate was prepared in the amorphous gel form in dimethyl formamide (DMF) and characterized by 31P NMR. The composite membranes of SPEEK up to 50wt.% of zirconium phosphate sulfophenylenphosphonate content were prepared by introducing the solid proton conductor from the gel. The composite membranes were characterized using

Palanichamy Krishnan; Jin-Soo Park; Tae-Hyun Yang; Won-Yong Lee; Chang-Soo Kim

2006-01-01

439

Polybrominated Diphenyl Ethers in the Sediments of the Great Lakes.  

E-print Network

Polybrominated Diphenyl Ethers in the Sediments of the Great Lakes. 4. Influencing Factors, Trends in the five Laurentian Great Lakes, and each was analyzed for 10 congeners of polybrominated diphenyl ethers-PBDE congeners (9BDEs) in the sediments of all the Great Lakes was estimated to be approximately 5.2 ( 1.1 tonnes

Rockne, Karl J.

440

48. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, INTERIOR, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

48. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, INTERIOR, 5TH LEVEL, LOOKING NORTH AT ETHER AND ALCOHOL CONDENSERS AT TOP OF TOWER. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

441

Conductometric Studies on Cation-Crown Ether Complexes: A Review  

Microsoft Academic Search

Crown ethers have proved to be unique cyclic molecules for molecular recognition of suitable substrates by hydrogen bonds, ionic interactions, and\\/or hydrophobic interactions. The study of interactions involved in complexation of different cations with crown ethers in mixtures of solvents is important for a better understanding of the mechanism of biological transport, molecular recognition, and other analytical applications. This fundamental

Francis A. Christy; Pranav S. Shrivastav

2011-01-01

442

47. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, INTERIOR, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

47. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, INTERIOR, 4TH LEVEL, LOOKING NORTH AT TOPS OF ALCOHOL AND ETHER DISTILLATION TOWERS. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

443

46. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, INTERIOR, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

46. BUILDING NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, INTERIOR, CONTROL PANEL LEVEL (2ND DECK) OF ETHER AND ALCOHOL STILL BUILDING, LOOKING NORTH, SHOWING TWO ALCOHOL DISTILLATION TOWERS BEHIND 'MIXED SOLVENT UNIT' CONTROL PANEL. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

444

Network Structure of Cellulose Ethers Used in Pharmaceutical Applications  

E-print Network

Network Structure of Cellulose Ethers Used in Pharmaceutical Applications during Swelling and physical characteristics of cellulose de- rivatives used in pharmaceutical applications have been de cellulose ethers that differ in their type and degree of substitution and to elucidate the network structure

Peppas, Nicholas A.

445

Catalytic Asymmetric Synthesis of Hydroxy Enol Ethers: Approach to a  

E-print Network

Catalytic Asymmetric Synthesis of Hydroxy Enol Ethers: Approach to a Two-Carbon Homologation. The resultant enantiomerically enriched hydroxy enol ethers were converted to protected hydroxy aldehydes the catalytic asymmetric allylation of aldehydes followed by oxidative cleavage of the allyl group (Scheme 1, A

Walsh, Patrick J.

446

IRIS TOXICOLOGICAL REVIEW OF PENTABROMODIPHENYL ETHER (EXTERNAL REVIEW DRAFT)  

EPA Science Inventory

The U.S. EPA is conducting a peer review of the scientific basis supporting the human health hazard and dose-response assessments of congeners of polybrominated diphenyl ethers (PDBEs), this review is about 2,2',4,4',5-Pentabromodiphenyl Ether, or commonly referred to as PentaBDE...

447

IRIS TOXICOLOGICAL REVIEW OF DECABROMODIPHENYL ETHER (EXTERNAL REVIEW DRAFT)  

EPA Science Inventory

The U.S. EPA is conducting a peer review of the scientific basis supporting the human health hazard and dose-response assessments of congeners of polybrominated diphenyl ethers (PDBEs), this review is about Decabromodiphenyl Ether, or commonly referred to as decaBDE (BDE-209). ...

448

IRIS TOXICOLOGICAL REVIEW OF HEXABROMODIPHENYL ETHER (EXTERNAL REVIEW DRAFT)  

EPA Science Inventory

The U.S. EPA is conducting a peer review of the scientific basis supporting the human health hazard and dose-response assessments of congeners of polybrominated diphenyl ethers (PDBEs), this review is about 2,2',4,4',5,5'-Hexabromodiphenyl Ether, or commonly referred to as HexaB...

449

Synthesis of the first perfluoro-spiro-bis-crown ethers  

SciTech Connect

Since the first perfluoro crown ethers were prepared by members of our research group, many new perfluoro crown ethers have been synthesized, and medical applications such as {sup 19}F NMR imaging and oxygen carrier applications as well as new chemistry associated with these compounds are currently under study. Perfluoro crown ethers do not form extremely stable complexes with metal cations because the basicities of perfluoro crown ethers decrease as the amount of fluorine substitution increases. On the contrary, perfluoro crown ethers form complexes with certain anions in the gas phase. In order to explore the chemistry of theses new compounds, the preparation of new perfluoro crown ethers, such as multilooped perfluoro crown ethers, is very important. We report in this paper the syntheses of the first perfluoro-spiro-bis[19]crown ethers, perfluoro-spiro-bis-crown-6 (1), perfluoro-spiro-bis[16]crown-5 (2), and perfluoro-spiro-bis[13]crown-4 (3), by elemental fluorine. 12 refs., 3 figs., 1 tab.

Wei, Han-Chao; Lynch, V.M.; Lagow, R.J. [Univ. of Texas, Austin, TX (United States)] [Univ. of Texas, Austin, TX (United States)

1997-03-07

450

Synthesis of unsymmetrical pyrazines based on ?-diazo oxime ethers.  

PubMed

Synthesis of unsymmetrically substituted pyrazines has been a challenge. The reactivity of ?-imino carbenoids derived from ?-diazo oxime ethers has been exploited for pyrazine synthesis, in which the reaction of ?-diazo oxime ethers with 2H-azirines provides highly substituted pyrazines in good to excellent yields. PMID:25590992

Loy, Nicole S Y; Kim, Sunggak; Park, Cheol-Min

2015-02-01

451

Imide/arylene ether copolymers with pendent trifluoromethyl groups  

NASA Technical Reports Server (NTRS)

A series of imide/arylene ether block copolymers were prepared using an arylene ether block containing a hexafluoroisopropylidene group and an imide block containing a hexafluoroisopropylidene and a trifluoromethyl group in the polymer backbone. The copolymers were characterized and mechanical properties were determined and compared to the homopolymers.

Jensen, Brian J.; Havens, Stephen J.

1992-01-01

452

Ether theory of gravitation: why and how?  

E-print Network

Gravitation might make a preferred frame appear, and with it a clear space/time separation--the latter being, a priori, needed by quantum mechanics (QM) in curved space-time. Several models of gravitation with an ether are discussed: they assume metrical effects in an heterogeneous ether and/or a Lorentz-symmetry breaking. One scalar model, starting from a semi-heuristic view of gravity as a pressure force, is detailed. It has been developed to a complete theory including continuum dynamics, cosmology, and links with electromagnetism and QM. To test the theory, an asymptotic scheme of post-Newtonian approximation has been built. That version of the theory which is discussed here predicts an internal-structure effect, even at the point-particle limit. The same might happen also in general relativity (GR) in some gauges, if one would use a similar scheme. Adjusting the equations of planetary motion on an ephemeris leaves a residual difference with it; one should adjust the equations using primary observations. The same effects on light rays are predicted as with GR, and a similar energy loss applies to binary pulsars.

Mayeul Arminjon

2007-05-31

453

Biosynthesis of archaeal membrane ether lipids  

PubMed Central

A vital function of the cell membrane in all living organism is to maintain the membrane permeability barrier and fluidity. The composition of the phospholipid bilayer is distinct in archaea when compared to bacteria and eukarya. In archaea, isoprenoid hydrocarbon side chains are linked via an ether bond to the sn-glycerol-1-phosphate backbone. In bacteria and eukarya on the other hand, fatty acid side chains are linked via an ester bond to the sn-glycerol-3-phosphate backbone. The polar head groups are globally shared in the three domains of life. The unique membrane lipids of archaea have been implicated not only in the survival and adaptation of the organisms to extreme environments but also to form the basis of the membrane composition of the last universal common ancestor (LUCA). In nature, a diverse range of archaeal lipids is found, the most common are the diether (or archaeol) and the tetraether (or caldarchaeol) lipids that form a monolayer. Variations in chain length, cyclization and other modifications lead to diversification of these lipids. The biosynthesis of these lipids is not yet well understood however progress in the last decade has led to a comprehensive understanding of the biosynthesis of archaeol. This review describes the current knowledge of the biosynthetic pathway of archaeal ether lipids; insights on the stability and robustness of archaeal lipid membranes; and evolutionary aspects of the lipid divide and the LUCA. It examines recent advances made in the field of pathway reconstruction in bacteria. PMID:25505460

Jain, Samta; Caforio, Antonella; Driessen, Arnold J. M.

2014-01-01

454

Thermal decomposition of technological polymer blends 1. Poly(aryl ether ether ketone) with a thermotropic liquid crystalline polymer  

Microsoft Academic Search

The thermal decomposition of blends of poly(aryl ether ether ketone), PEEK, with a thermotropic liquid crystalline polymer (LCP), VECTRA, was investigated using thermogravimetric analysis under dynamic conditions. The activation energies were obtained using integral and differential methods. The thermal analysis of the blends show that thermal stability is clearly affected with respect to the unblended materials, and it was also

M. Naffakh; G. Ellis; M. A. Gómez; C. Marco

1999-01-01

455

Preparation of poly(ether ether ketone)-based polymer electrolytes for fuel cell membranes using grafting technique  

Microsoft Academic Search

Poly(ether ether ketone) (PEEK)-based polymer electrolyte membranes (PEMs) was successfully prepared by radiation grafting of a styrene monomer into PEEK films and the consequent selective sulfonation of the grafting chains in the film state. Using milder sulfonation, the sulfonation reactions proceeded at the grafted chains in preference to the phenylene rings of PEEK main chains; as a result, the grafted

Shin Hasegawa; Yasuyuki Suzuki; Yasunari Maekawa

2008-01-01

456

Chemicals as peak shaving agents in IGCC based power plants  

SciTech Connect

Coal gasification generates a very impure synthesis gas, which before use in gas turbines for Integrated Gasification Combined Cycle (IGCC) plants has to be cleaned thoroughly. The purification of such a gas may be done by hot gas cleaning to a level which allows the gas to be used for production of chemicals such as methanol or dimethyl ether (DME). Such a production may be attractive either for use of the substances as such in the chemical industry or as automotive fuels. Alternatively these fuels may also be used as gas turbine fuels for power production. In the latter case an interesting possibility exists in the form of chemical recuperation. Low grade heat is used in the catalytically based transformation of methanol or DME into hydrogen and carbon monoxide. The present paper deals with the hot gas cleaning processes and the catalytic processes involved in a power plant in which the produced methanol and/or DME is used for peak shaving purposes.

Hansen, J.B.; Aasberg-Petersen, K.; Sigurdardottir, D.; Nielsen, H. [Haldor Topsoe A/S (Denmark)

1998-12-31

457

40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.  

Code of Federal Regulations, 2012 CFR

...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner...

2012-07-01

458

40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.  

Code of Federal Regulations, 2013 CFR

...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner...

2013-07-01

459

40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.  

Code of Federal Regulations, 2014 CFR

...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner...

2014-07-01

460

40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.  

Code of Federal Regulations, 2010 CFR

...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner...

2010-07-01

461

40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.  

Code of Federal Regulations, 2011 CFR

...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. ...carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner...

2011-07-01

462

40 CFR 180.261 - N-(Mercaptomethyl) phthali-mide S-(O,O-dimethyl phosphoro-dithioate) and its oxygen analog...  

Code of Federal Regulations, 2010 CFR

...O-dimethyl phosphoro-dithioate) and its oxygen analog; tolerances for residues. 180...dimethyl phosphoro-dithioate) and its oxygen analog; tolerances for residues. ...dimethyl phosphorodithioate) and its oxygen analog N -(mercaptomethyl)...

2010-07-01

463

Formation of complex organic molecules in cold objects: the role of gas-phase reactions  

NASA Astrophysics Data System (ADS)

While astrochemical models are successful in reproducing many of the observed interstellar species, they have been struggling to explain the observed abundances of complex organic molecules. Current models tend to privilege grain surface over gas-phase chemistry in their formation. One key assumption of those models is that radicals trapped in the grain mantles gain mobility and react on lukewarm ( ? 30 K) dust grains. Thus, the recent detections of methyl formate (MF) and dimethyl ether (DME) in cold objects represent a challenge and may clarify the respective role of grain-surface and gas-phase chemistry. We propose here a new model to form DME and MF with gas-phase reactions in cold environments, where DME is the precursor of MF via an efficient reaction overlooked by previous models. Furthermore, methoxy, a precursor of DME, is also synthesized in the gas phase from methanol, which is desorbed by a non-thermal process from the ices. Our new model reproduces fairly well the observations towards L1544. It also explains, in a natural way, the observed correlation between DME and MF. We conclude that gas-phase reactions are major actors in the formation of MF, DME and methoxy in cold gas. This challenges the exclusive role of grain-surface chemistry and favours a combined grain-gas chemistry.

Balucani, Nadia; Ceccarelli, Cecilia; Taquet, Vianney

2015-04-01

464

Dimethyl fumarate for relapsing-remitting multiple sclerosis.  

PubMed

For many years the only drugs licensed for the treatment of multiple sclerosis (MS) were administered by injection (interferon beta, glatiramer and ?natalizumab). Recently, three oral drugs have become available. We have previously reviewed the use of ?fingolimod for highly active relapsing-remitting MS1 and ?teriflunomide for the management of relapsing-remitting MS in adults.2 Here, we review the evidence for ?dimethyl fumarate (Tecfidera-Biogen Idec Ltd) for the treatment of adults with relapsing-remitting MS. PMID:25213591

2014-09-01

465

Atomistic and mesoscale simulation of polymer electrolyte membranes based on sulfonated poly(ether ether ketone)  

NASA Astrophysics Data System (ADS)

We report results of multiscale simulations of a hydrated ionomer membrane based on sulfonated poly(ether ether ketone) (sPEEK) that constitutes an important class of the promising membrane materials for fuel cell applications. Using atomistic and field-theoretic simulation techniques - classical molecular dynamics and dynamic density functional theory - we study the processes of self-organization in sPEEK membranes in the presence of water. At the same water content, both simulation techniques predict a similar structure of the hydrated membranes. The observed membrane morphology can be represented as a topologically complex sponge-like network consisting of irregular water-filled channels. Compared to Nafion, the channels in the sPEEK membrane are narrower. Nevertheless, the estimated percolation threshold in sPEEK is lower than for Nafion.

Komarov, P. V.; Veselov, I. N.; Chu, P. P.; Khalatur, P. G.; Khokhlov, A. R.

2010-03-01

466

The effect of high-energy electron radiation on poly(arylene ether)s  

NASA Technical Reports Server (NTRS)

Thin films of four experimental poly(arylene ether)s of similar chemical structure were exposed to 1 MeV electrons while under high vacuum. The films received total exposures of 5 x 10 exp 7 and 1 x 10 exp 9 rads at a dose rate of 5 x 10 exp 7 rads/h and a pressure of 2 x 10 exp -7 torr. Films exposed to 5 x 10 exp 7 rads showed dramatic changes in molecular weight distribution. After exposures of 1 x 10 exp 9 rads the films were only partially soluble in chloroform and exhibited no detectable changes in the glass transition temperatures. Thin-film tensile properties were also altered by the exposure to electron radiation. The effect of the exposures as determined by various analyses is discussed.

Connell, J. W.; Siochi, E. J.; Croall, C. I.

1993-01-01

467

Wear of ceramic-on-carbon fiber-reinforced poly-ether ether ketone hip replacements.  

PubMed

Total hip replacement has been a successful surgical intervention for over 50 years, with the majority of bearings using a polyethylene cup. Long-term failure due to osteolysis and loosening has been widely documented and alternative bearings have been sought. A novel carbon fiber-reinforced poly-ether ether ketone (CFR-PEEK) cup was investigated through experimental friction and wear studies. Friction studies demonstrated the bearings operated in a boundary lubrication condition, with friction factors higher than those for other hip replacement bearings. The wear study was conducted with 36 mm diameter bearings tested against Biolox Delta heads for a period of 10 million cycles. The mean volumetric wear rate was 0.3 mm(3)/Mc, indicating the ceramic-on-CFR-PEEK bearing to be a very low wearing option for total hip replacement. PMID:22454322

Brockett, Claire L; John, Gemma; Williams, Sophie; Jin, Zhongmin; Isaac, Graham H; Fisher, John

2012-08-01

468

Origin of mechanical modifications in poly (ether ether ketone)/carbon nanotube composite  

SciTech Connect

Variations in the hardness of a poly (ether ether ketone) beam electrically modified with multi-walled carbon nanotubes (MWCNT, 0.5%-3%) are investigated. It is shown that both rupture and hardness variations correlate with the changes in carbon nanotube concentration when using micro indentation and extended Raman imaging. Statistical analysis of the relative spectral intensities in the Raman image is used to estimate local tube concentration and polymer crystallinity. We show that the histogram of the Raman D band across the image provides information about the amount of MWCNTs and the dispersion of MWCNTs in the composite. We speculate that we have observed a local modification of the ordering between pure and modified polymer. This is partially supported by small angle neutron scattering measurements, which indicate that the agglomeration state of the MWCNTs is the same at the concentrations studied.

Pavlenko, Ekaterina; Puech, Pascal; Bacsa, Wolfgang, E-mail: wolfgang.bacsa@cemes.fr [CEMES-CNRS and University of Toulouse, 29 Jeanne Marvig, 31055 Toulouse (France); Boyer, François; Olivier, Philippe [Université de Toulouse, Institut Clément Ader, I.U.T. Université Paul Sabatier - 133C Avenue de Rangueil - B.P. 67701, 31077 Toulouse CEDEX 4 (France); Sapelkin, Andrei [School of Physics and Astronomy, Queen Mary, University of London, Mile End Road, E1 4NS London (United Kingdom); King, Stephen; Heenan, Richard [ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX Didcot (United Kingdom); Pons, François; Gauthier, Bénédicte; Cadaux, Pierre-Henri [AIRBUS FRANCE (B.E. M and P Toulouse), 316 Route de Bayonne, 31060 Toulouse (France)

2014-06-21

469

Origin of mechanical modifications in poly (ether ether ketone)/carbon nanotube composite  

NASA Astrophysics Data System (ADS)

Variations in the hardness of a poly (ether ether ketone) beam electrically modified with multi-walled carbon nanotubes (MWCNT, 0.5%-3%) are investigated. It is shown that both rupture and hardness variations correlate with the changes in carbon nanotube concentration when using micro indentation and extended Raman imaging. Statistical analysis of the relative spectral intensities in the Raman image is used to estimate local tube concentration and polymer crystallinity. We show that the histogram of the Raman D band across the image provides information about the amount of MWCNTs and the dispersion of MWCNTs in the composite. We speculate that we have observed a local modification of the ordering between pure and modified polymer. This is partially supported by small angle neutron scattering measurements, which indicate that the agglomeration state of the MWCNTs is the same at the concentrations studied.

Pavlenko, Ekaterina; Boyer, François; Puech, Pascal; Olivier, Philippe; Sapelkin, Andrei; King, Stephen; Heenan, Richard; Pons, François; Gauthier, Bénédicte; Cadaux, Pierre-Henri; Bacsa, Wolfgang

2014-06-01

470

A sulfonated poly (aryl ether ether ketone ketone) isomer: synthesis and DMFC performance  

SciTech Connect

A sulfonated poly(aryl ether ether ketone ketone) (PEEKK) having a well-defined rigid homopolymer-like chemical structure was synthesized from a readily-prepared PEEKK post-sulfonation with concentrated sulfuric acid at room temperature within several hours. The polymer electrolyte membrane (PEM) cast from the resulting polymer exhibited an excellent combination of thermal resistance, oxidative and dimensional stability, low methanol fuel permeability and high proton conductivity. Furthermore, membrane electrode assemblies (MEAs) were successfully fabricated and good direct methanol fuel cell (DMFC) performance was observed. At 2 M MeOH feed, the current density at 0.5 V reached 165 mA/cm, which outperformed our reported analogues and eveluated Nafion membranes.

Kim, Yu Seung [Los Alamos National Laboratory; Liu, Baijun [JILIN UNIV.; Hu, Wei [JILIN UNIV.; Jiang, Zhenhua [JILIN UNIV.; Robertson, Gilles [CANADA NRC; Guiver, Michael [CANADA NRC

2009-01-01

471

Methoxy-ether and crown-ether derivatives of tetrahomodioxa- and octahomotetraoxacalix[4]arenes.  

PubMed

Three methoxy-ether and one methoxy-ether/crown-ether derivatives of p-tert-butyltetrahomodioxa- and p-R-octahomotetraoxacalix[4]arenes (R = methyl, tert-butyl, H) have been investigated. The first three compounds, 7,15,21,27-tetra-tert-butyl-29,30,31,32-tetramethoxy-3,11-dioxapentacyclo[23.3.1.1(5,9).1(13,17).1(19,23)]ditriaconta-1(29),5,7,9(30),13,15,-17(31),19,21,23(32),25,27-dodecaene, C(50)H(68)O(6), 33,34,35,36-tetramethoxy-7,15,23,31-tetramethyl-3,11,19,27-tetraoxapentacyclo[27.3.1.1(5,9).1(13,17).1(21,25)]hexatriaconta-1(33),5,7,9(34),13,15,17(35),21,23,25(36),29,31-dodecaene, C(40)H(48)O(8), and 7,23-di-tert-butyl-33,34,35,36-tetramethoxy-3,11,19,27-tetraoxapentacyclo[27.3.1.1(5,9).1(13,17).1(21,25)]hexatriaconta-1(33),5,7,9(34),13,15,17(35),- 21,23,25(36),29,31-dodecaene, C(44)H(56)O(8), in the partial-cone or 1,2-alternate conformations, present the common feature of methoxy-ether self-inclusion, while the fourth, 42,43-dimethoxy-7,15,23,31-tetramethyl-3,11,19,27,34,37,40-heptaoxahexacyclo[15.15.9.1(5,9).1(21,25).0(13,41).0(29,33)]tritetraconta-5(42),6,8,13(41),14,16,21(43),22,24,29(33),30,32-dodecaene, C(42)H(50)O(9), adopts the 1,3-alternate conformation owing to the presence of a 1,3-polyether chain. PMID:11498633

Masci, B; Saccheo, S; Fonsi, M; Varrone, M; Finelli, M; Nierlich, M; Thuéry, P

2001-08-01

472

Crown Ethers in Nonaqueous Electrolytes for Lithium/Air Batteries  

SciTech Connect

The effects of three crown ethers, 12-crown-4, 15-crown-5, and 18-crown-6, as additives and co-solvents in non-aqueous electrolytes on the cell performance of primary Li/air batteries operated in a dry air environment were investigated. Crown ethers have large effects on the discharge performance of non-aqueous electrolytes in Li/air batteries. A small amount (normally less than 10% by weight or volume in electrolytes) of 12-Crown-4 and 15-crown-5 reduces the battery performance and a minimum discharge capacity appears at the crown ether content of ca. 5% in the electrolytes. However, when the content increases to about 15%, both crown ethers improve the capacity of Li/air cells by about 28% and 16%, respectively. 15-Crown-5 based electrolytes even show a maximum discharge capacity in the crown ether content range from 10% to 15%. On the other hand, the increase of 18-crown-6 amount in the electrolytes continuously lowers of the cell performance. The different battery performances of these three crown ethers in electrolytes are explained by the combined effects from the electrolytes’ contact angle, oxygen solubility, viscosity, ionic conductivity, and the stability of complexes formed between crown ether molecules and lithium ions.

Xu, Wu; Xiao, Jie; Wang, Deyu; Zhang, Jian; Zhang, Jiguang

2010-02-04

473

Stereoselective synthesis of six- and seven-membered ether rings based on the ring expansion  

Microsoft Academic Search

Six- and seven-membered ether rings were stereoselectively synthesized based on the rearrangement of the cyclic ether with the simultaneous ring expansion. Treatment of ether having a mesylate or bromide group as the leaving group on the side chain with Zn(OAc)2 or AgOAc stereoselectively produced the ring expanded ether in good yield.

Tadashi Nakata; Sumihiro Nomura; Hiroko Matsukura

1996-01-01

474

Hydrocarbon conversion process. [production of gasoline blending stock using etherated gasoline to reduce emissions  

Microsoft Academic Search

A process is given for producing gasoline blending stock which comprises (a) feeding an alcohol and a light hydrocarbon mixture containing at least tertiary olefins, linear olefins and isobutane to an etheration zone, (b) reacting the alcohol with the tertiary olefins in the etheration zone to obtain an ether and unreacted linear olefins and isobutane, (c) separating the ether from

R. H. Kozlowski; R. P. Sieg; J. W. Scott

1975-01-01

475

High temperature fuel cell membranes based on poly(arylene ether)s containing benzimidazole groups  

SciTech Connect

Development of new high-performance polymer membranes that retain their proton conductivity under low humidity conditions is one of the most critical requirements to commercialize PEMFC systems. Current sulfonated proton exchange membranes acquire proton conductivity by water that solvates ion and carries proton. Consequently, a loss of water under low RH conditions immediately results in a loss of proton conductivity. One approach to maintain proton conductivity under low RH conditions is to replace water with a less volatile proton solvent. Kreuer has pointed out the possibility to develop fully polymeric proton-conducting membranes based on nitrogen-containing heterocycles such as imidazole, benzimidazole, and pyrazole. We have attempted to blend those less volatile proton solvent with sulfonated copolymers such as polystyrene sulfonic acid, Nafion, poly(arylene ether sulfone, BPSH-xx). [Ref. DOE review meeting 2007 and 2008] However, we observed that imidazole was slowly sublimated out as temperature and humidity increases which could cause poisoning of electro-catalyst, corrosion and losing conductivity. In this presentation, we report the synthesis of novel poly(arylene ether sulfone)s containing benzimidazole groups These benzimidazole containing polymer was blended with sulfonated poly(arylene ether sulfone). In the blend system, benzimidazole group attached to the polysulfone acts as a medium through the basic nitrogen for transfer of protons between the sulfonic acid groups. Proton conductivity of the blend membranes was investigated as a function of water content at 80 C and compared the performance with water based proton conduction system.

Kim, Dae Sik [Los Alamos National Laboratory; Kim, Yu Seung [Los Alamos National Laboratory; Lee, Kwan - Soo [Los Alamos National Laboratory; Boncella, James M [Los Alamos National Laboratory; Kuiper, David [Los Alamos National Laboratory; Guiver, Michael D [CANADA

2009-01-01

476

Photolytical transformation rates of individual polybrominated diphenyl ethers in technical octabromo diphenyl ether (DE-79).  

PubMed

Polybrominated diphenyl ethers (PBDEs) are of environmental concern due to their persistence, potential to bioaccumulate, and possible toxic effects, especially for the lower brominated homologues. Reductive debromination under UV light has been identified as the main abiotic pathway for PBDE transformation. Although the kinetics and transformation products have been determined for individual PBDE congeners in different matrices, no effort has been made to determine the kinetics of these congeners when technical mixtures are exposed to UV light. We irradiated technical octabromodiphenyl ether (DE-79) in a perdeuterated solvent to determine the photolytic transformation kinetics of native PBDE congeners. Each deuterium that replaced bromine resulted in a shift to higher masses compared to the native congener, which was measured by gas chromatography with electron ionization mass spectrometry in the selected ion monitoring mode (GC/EI-MS-SIM). Tri-, tetra-, and pentabromodiphenyl ether products (BDE 28, BDE 47, BDE 49, BDE 99, BDE 100) could be proportioned to higher brominated precursors as a function of irradiation time. The kinetics of UV-irradiated single PBDE congeners matched well with results of previous studies of single congeners. However, when the same congeners were irradiated in the technical DE-79 mixture, their half-lives were longer by 20-160%. This study indicates that individually irradiated PBDE congeners behave differently than if present as a mixture. This result should be taken into account in models predicting the environmental fate of PBDEs and most likely also the mixtures of other contaminant groups. PMID:20121183

Bendig, Paul; Vetter, Walter

2010-03-01

477

Oxidative cleavage of diverse ethers by an extracellular fungal peroxygenase.  

PubMed

Many litter-decay fungi secrete heme-thiolate peroxygenases that oxidize various organic chemicals, but little is known about the role or mechanism of these enzymes. We found that the extracellular peroxygenase of Agrocybe aegerita catalyzed the H2O2-dependent cleavage of environmentally significant ethers, including methyl t-butyl ether, tetrahydrofuran, and 1,4-dioxane. Experiments with tetrahydrofuran showed the reaction was a two-electron oxidation that generated one aldehyde group and one alcohol group, yielding the ring-opened product 4-hydroxybutanal. Investigations with several model substrates provided information about the route for ether cleavage: (a) steady-state kinetics results with methyl 3,4-dimethoxybenzyl ether, which was oxidized to 3,4-dimethoxybenzaldehyde, gave parallel double reciprocal plots suggestive of a ping-pong mechanism (K(m)((peroxide)), 1.99 +/- 0.25 mM; K(m)((ether)), 1.43 +/- 0.23 mM; k(cat), 720 +/- 87 s(-1)), (b) the cleavage of methyl 4-nitrobenzyl ether in the presence of H2(18)O2 resulted in incorporation of 18O into the carbonyl group of the resulting 4-nitrobenzaldehyde, and (c) the demethylation of 1-methoxy-4-trideuteromethoxybenzene showed an observed intramolecular deuterium isotope effect [(k(H)/k(D))(obs)] of 11.9 +/- 0.4. These results suggest a hydrogen abstraction and oxygen rebound mechanism that oxidizes ethers to hemiacetals, which subsequently hydrolyze. The peroxygenase appeared to lack activity on macromolecular ethers, but otherwise exhibited a broad substrate range. It may accordingly have a role in the biodegradation of natural and anthropogenic low molecular weight ethers in soils and plant litter. PMID:19713216

Kinne, Matthias; Poraj-Kobielska, Marzena; Ralph, Sally A; Ullrich, René; Hofrich