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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  

Microsoft Academic Search

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

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

2003-01-01

3

DIMETHYL ETHER (DME)FUELED SHUTTLE BUS DEMONSTRATION PROJECT  

Microsoft Academic Search

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

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

2003-01-01

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. 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

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. 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

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 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

7

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

8

Investigation on the fuel spray and emission reduction characteristics for dimethyl ether (DME) fueled multi-cylinder diesel engine with common-rail injection system  

Microsoft Academic Search

The aim of this study is to investigate the effects of dimethyl ether (DME) fuel on the engine performance and the exhaust emission reduction characteristics in a DME fueled four-cylinder diesel engine with a common rail injection system, as well as an injection characteristics and a spray behavior. The injection rate meter and the spray visualization system are utilized for

In Mo Youn; Su Han Park; Hyun Gu Roh; Chang Sik Lee

2011-01-01

9

A comparative study on the autoxidation of dimethyl ether (DME) comparison with diethyl ether (DEE) and diisopropyl ether (DIPE)  

Microsoft Academic Search

The Japanese government is planning to introduce DME as a substituted energy for oil and LNG. Introduction of DME could contribute greatly to both the prevention of global warming and the formation of resource-recycling societies. In these circumstances, a safety assessment of DME is very important when DME is used on a large scale. There is a possibility that prolonged

Michie Naito; Claire Radcliffe; Yuji Wada; Takashi Hoshino; Xiongmin Liu; Mitsuru Arai; Masamitsu Tamura

2005-01-01

10

An investigation of the effects of spray angle and injection strategy on dimethyl ether (DME) combustion and exhaust emission characteristics in a common-rail diesel engine  

Microsoft Academic Search

An experimental investigation was performed on the effects of spray angle and injection strategies (single and multiple) on the combustion characteristics, concentrations of exhaust emissions, and the particle size distribution in a direct-injection (DI) compression ignition engine fueled with dimethyl ether (DME) fuel. In this study, two types of narrow spray angle injectors (?spray=70° and 60°) were examined and its

Seung Hyun Yoon; June Pyo Cha; Chang Sik Lee

2010-01-01

11

Dimethyl Ether (DME)-Fueled Shuttle Bus Demonstration Project for the Period of July 1, 2000-June 30, 2001.  

National Technical Information Service (NTIS)

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 f...

E. M. Chapman S. Bhide A. L. Boehman D. Klinikowski

2003-01-01

12

A combined system of dimethyl ether (DME) steam reforming and lean NOx trap catalysts to improve NOx reduction in DME engines  

Microsoft Academic Search

This paper performs a study on a combined system of DME steam reforming (SR) and lean NOx trap (LNT) in order to improve the performance of the de-NOx catalyst in DME engines. A new concept, a combined system of SR and LNT catalysts, utilizes H2 and CO generated from the DME SR catalyst as a reductant for the LNT catalyst.

Byungchul Choi; Byeong-Soo Oh

2011-01-01

13

Explosion and detonation characteristics of dimethyl ether  

Microsoft Academic Search

In this study, the explosion and detonation characteristics of dimethyl ether (DME) were experimentally investigated. A spherical pressure vessel with an internal volume of 180L was used as the explosion vessel. Therefore, tubes 10m in length with internal diameters of 25mm and 50mm were used as detonation tubes. In addition, we compared the characteristics of DME with those of propane

Toshio Mogi; Sadashige Horiguchi

2009-01-01

14

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

15

Effective utilization of remote coal through dimethyl ether synthesis  

Microsoft Academic Search

Dimethyl ether (DME) is a clean and sustainable alternative fuel that can be produced from natural gas, coal or other organic resources through syngas. The properties of DME are suitable for the production of power generation fuel, transportation fuel, home fuel and chemicals. Production of DME fuel from unutilized natural gas or coal resources in remote areas will contribute in

Y Adachi; M Komoto; I Watanabe; Y Ohno; K Fujimoto

2000-01-01

16

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

Microsoft Academic Search

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 (1–5atm), 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

Troy A. Semelsberger; Rodney L. Borup

2005-01-01

17

Fuel Oxidization on Dimethyl-ether Fuel Cell Cathode  

NASA Astrophysics Data System (ADS)

Cross leaked methanol in the cathode of a direct methanol fuel cell is completely oxidized, however, in the cathode of a dimethyl-ether (DME) fuel cell, the cross leaked DME is not oxidized and is exhausted from the cathode. The present paper reports that active DME oxidation such as methanol oxidation does not occur on the DME cathode until both the current density and cross leaked DME concentration exceed some upper limit. There is no cross leaked DME oxidation on a cathode under normal operating conditions, in which the current density is less than 0.2A/cm2, and the DME concentration is less than 1%. The cathode potential of the direct DME fuel cell does not decrease without active DME oxidation.

Haraguchi, Tadao; Tsutsumi, Yasuyuki; Murakami, Takahiko; Satou, Yasuyuki; Watanabe, Atushi; Yamashita, Susumu

18

Modeling, simulation and control of dimethyl ether synthesis in an industrial fixed-bed reactor  

Microsoft Academic Search

Dimethyl ether (DME) as a clean fuel has attracted the interest of many researchers from both industrial communities and academia. The commercially proven process for large scale production of dimethyl ether consists of catalytic dehydration of methanol in an adiabatic fixed-bed reactor. In this study, the industrial reactor of DME synthesis with the accompanying feed preheater has been simulated and

M. Farsi; R. Eslamloueyan; A. Jahanmiri

2011-01-01

19

Kinetics and modelling of dimethyl ether synthesis from synthesis gas  

Microsoft Academic Search

The kinetics of the dual catalytic methanol and dimethyl ether (DME) synthesis process over a commercial CuO\\/ZnO\\/Al2O3 (methanol forming) and a ?-alumina (dehydration) catalyst have been investigated at 250°C and 5 MPa using a gradientless, internal-recycle-type reactor. A kinetic model for the combined methanol+DME synthesis based on a methanol synthesis model proposed by Vanden Bussche and Froment (1996) J. Catal.,

K. L. Ng; D. Chadwick; B. A. Toseland

1999-01-01

20

Monte Carlo predictions of phase equilibria and structure for dimethyl ether + sulfur dioxide and dimethyl ether + carbon dioxide  

NASA Astrophysics Data System (ADS)

A new force field for dimethyl ether (DME) based on the Lennard-Jones (LJ) 12-6 plus point charge functional form is presented in this work. This force field reproduces experimental saturated liquid and vapor densities, vapor pressures, heats of vaporization, and critical properties to within the statistical uncertainty of the combined experimental and simulation measurements for temperatures between the normal boiling and critical point. Critical parameters and normal boiling point are predicted to within 0.1% of experiment. This force field is used in grand canonical histogram reweighting Monte Carlo simulations to predict the pressure composition diagrams for the binary mixtures DME + SO2 at 363.15 K and DME + CO2 at 335.15 and 308.15 K. For the DME + SO2 mixture, simulation is able to qualitatively reproduce the minimum pressure azeotropy observed experimentally for this mixture, but quantitative errors exist, suggesting that multibody effects may be important in this system. For the DME + CO2 mixture, simulation is able to predict the pressure-composition behavior within 1% of experimental data. Simulations in the isobaric-isothermal ensemble are used to determine the microstructure of DME + SO2 and DME + CO2 mixtures. The DME + SO2 shows weak pairing between DME and SO2 molecules, while no specific pairing or aggregation is observed for mixtures of DME + CO2.

Kamath, Ganesh; Ketko, Marybeth; Baker, Gary A.; Potoff, Jeffrey J.

2012-01-01

21

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

Microsoft Academic Search

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

Li Zhou; Shanying Hu; Dingjiang Chen; Yourun Li; Bing Zhu; Yong Jin

2009-01-01

22

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

23

Simulation and experiment study of dimethyl ether synthesis from syngas in a fluidized-bed reactor  

Microsoft Academic Search

As syngas to dimethyl ether (DME) reaction is highly exothermic and the catalyst temperature window is very narrow, fluidized-bed reactor is an ideal candidate as it is highly effective both in heat and mass transfer. In this paper, a new mechanism and kinetics model for DME synthesis are established and a laboratory fluidized-bed reactor is set up. Experiments are carried

Wen-Zhi Lu; Li-Hua Teng; Wen-De Xiao

2004-01-01

24

Thermodynamics of Hydrogen Production from Dimethyl Ether Steam Reforming and Hydrolysis  

Microsoft Academic Search

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

T. A. Semelsberger

2004-01-01

25

Pulsed-field ionization electron spectroscopy and binding energies of alkali metal-dimethyl ether and -dimethoxyethane complexes  

Microsoft Academic Search

Lithium and sodium complexes of dimethyl ether (DME) and dimethoxyethane (DXE) were produced by reactions of laser-vaporized metal atoms with organic vapors in a pulsed nozzle cluster source. The mono-ligand complexes were studied by photoionization and pulsed field ionization zero electron kinetic energy (ZEKE) spectroscopy. Vibrationally resolved ZEKE spectra were obtained for Li(DME), Na(DME) and Li(DXE) and a photoionization efficiency

Bradford R. Sohnlein; Shenggang Li; Jason F. Fuller; Dong-Sheng Yang

2005-01-01

26

Coke formation and performance of an intermediate-temperature solid oxide fuel cell operating on dimethyl ether fuel  

Microsoft Academic Search

Dimethyl ether (DME) as a fuel of SOFCs is investigated with great attention paid to coke formation over the Ni-YSZ anode. DME is easily decomposed to CH4, CO and H2 at temperatures above 700°C, with total conversion occurring at 850°C over the Ni-YSZ catalyst. These data suggest that the DME electro-oxidation likely proceeds via an indirect pathway. O2-TPO analysis, laser

Chao Su; Ran Ran; Wei Wang; Zongping Shao

27

The aging of wire chambers filled with dimethyl ether: wire and construction materials and freon impurities  

NASA Astrophysics Data System (ADS)

This is a complete summary of our study of the aging of different types of wire chambers, with a variety of construction materials and wires, filled with dimethyl ether (DME) of varying degrees of purity. The resistive Nicotin and Stablohm wires were corroded by DME, producing fast aging. The moderately resistive stainless steel wires were able to withstand extended irradiation (up to 1 C/cm) in high-purity DME without any apparent damage; and gold-plated tungsten and molybdenum wires exhibited a comparable behavior. Many construction materials were tested and recommendations are thus reached as to what kinds of materials are safe in building DME-operated wire chambers. Among many different Freon and hydrocarbon impurities detected in DME by means of gas chromatography (GC), Freon-11 was found to be mostly responsible for the aging, even with noncorrosive stainless steel or gold-plated wires. The availability and feasibility of obtaining Freon-free DME is reported as well.

Jibaly, Mohammed; Majewski, Stan; Chrusch, Peter; Wojcik, Randolph; Sauli, Fabio; Gaudaen, Jan

1989-11-01

28

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

29

Optimal conditions for hydrogen production from coupling of dimethyl ether and benzene synthesis  

Microsoft Academic Search

Coupling energy intensive endothermic reaction systems with suitable exothermic reactions followed by hydrogen permeation through the Pd\\/Ag membrane improves the thermal efficiency of processes, achieving the autothermality within the reactor, reduces the size of reactors, produces the pure hydrogen, and achieving a multiple reactants multiple products configuration. This paper focuses on optimization of hydrogen, dimethyl ether (DME) and benzene production

M. Farsi; M. H. Khademi; A. Jahanmiri; M. R. Rahimpour

2011-01-01

30

Operation of Microstrip Gas Chambers in Low Pressure Dimethyl Ether  

NASA Astrophysics Data System (ADS)

Microstrip gas chambers (MSGC) are miniaturized gas ionization detectors fabricated using the techniques developed for integrated circuit manufacture. These detectors have better position resolution, faster timing, and a higher rate capability compared to standard MWPC detectors, and they offer a radiation hardened alternative to silicon microstrips for vertex detectors. We report here on operation of MSGC detectors at low pressure (P? 10-50 torr) in pure dimethyl ether (DME). This particular operation mode is naturally suited to the detection of low-energy, heavy charged particles internal to the vacuum chamber of a storage ring. This work was supported by the NSF and the University of Louisville.

Martin, M. D.; Browne, K. P.; Hutchins, J. B.; Pitts, W. K.; Walsh, K. M.; Solberg, K.

1996-05-01

31

Cross sections for electron collisions with dimethyl ether  

NASA Astrophysics Data System (ADS)

We report a joint theoretical-experimental investigation of electron collision with dimethyl ether (DME) in the low- and intermediate-energy ranges. Experimental absolute differential, integral, and momentum-transfer cross sections for elastic e?-DME scattering are reported in the 100–1000 eV energy range. Our measurements were performed using a crossed electron-beam–molecular-beam geometry. The angular distribution of the scattered electrons was converted to absolute cross section using the relative flow technique. Theoretically, elastic differential, integral, and momentum-transfer cross sections, as well as the grand-total and total absorption cross sections for electron collision with DME are calculated in the 1–1000 eV energy range. A single-center-expansion technique combined with the Padé approximant method is used in our calculations. A comparison between the present experimental and theoretical data shows very good agreement. Moreover, comparison with theoretical and experimental data for e?-ethanol (an isomer of DME) scattering shows interesting isomeric effects.

Sugohara, R. T.; Homem, M. G. P.; Iga, I.; de Souza, G. L. C.; Machado, L. E.; Ferraz, J. R.; dos Santos, A. S.; Brescansin, L. M.; Lucchese, R. R.; Lee, M. T.

2013-08-01

32

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  

Microsoft Academic Search

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 (γ-alumina) was demonstrated. It provided the productivity and selectivity expected from the LPDME process.

Xiang-Dong Peng

2002-01-01

33

Effect of operating conditions on the synthesis of dimethyl ether over a CuO-ZnO-Al 2O 3\\/NaHZSM-5 bifunctional catalyst  

Microsoft Academic Search

The effect of operating conditions (time on stream, temperature, pressure and space time) on the conversion of CO and CO2, selectivity to dimethyl ether (DME), yield of DME and product distribution is studied in the DME synthesis from H2, CO and CO2 in a single reaction step on a CuO-ZnO-Al2O3\\/NaHZSM-5 bifunctional catalyst. CO conversion is total at 275°C and 40bar,

Javier Ereña; Raúl Garoña; José M. Arandes; Andrés T. Aguayo; Javier Bilbao

2005-01-01

34

Reducing the operation temperature of a solid oxide fuel cell using a conventional nickel-based cermet anode on dimethyl ether fuel through internal partial oxidation  

Microsoft Academic Search

Dimethyl ether (DME)-oxygen mixture as the fuel of an anode-supported SOFC with a conventional nickel-cermet anode for operating at reduced temperatures is systematically investigated. The results of the catalytic tests indicate that sintered Ni-YSZ has high activity for DME partial oxidation, and DME conversion exceeds 90% at temperatures higher than 700°C. Maximum methane selectivity is reached at 700°C. Cell performance

Chao Su; Wei Wang; Huangang Shi; Ran Ran; Hee Jung Park; Chan Kwak; Zongping Shao

2011-01-01

35

Modeling and simulation of tube-shell reactor for dimethyl-ether synthesis from coal-based synthesis gas  

Microsoft Academic Search

Mathematical simulation was performed on tube-shell reactor for dimethyl ether (DME) synthesis from coal-based syngas. The\\u000a model was established based on kinetics of dimethyl-ether synthesis from syngas over a bifunctional catalyst, which is mixed\\u000a by methanol synthesis catalyst and dehydration catalyst as 1:1 mass ratio. Methanol synthesis from CO and CO2 and methanol dehydration were selected as three-independent reactions, CO,

Da-sheng Chen; Hai-tao Zhang; Wei-yong Ying; Ding-ye Fang

2011-01-01

36

Formation pathways of HO 2 and OH changing as a function of temperature in photolytically initiated oxidation of dimethyl ether  

Microsoft Academic Search

The time resolved product formation in oxidation of dimethyl ether (DME) has been studied between 298–625K and 20–90 torr total pressure. Near-infrared frequency modulation spectroscopy (FMS) with Herriott type multi pass optics and UV absorption spectroscopy (UV) were conducted in the same cell. The reaction was initiated by pulsed photolysis in a mixture of Cl2, O2, and DME via CH3OCH2

Kotaro Suzaki; Chinzei Takahisa; Kentaro Tsuchiya; Mitsuo Koshi; Atsumu Tezaki

2007-01-01

37

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

Microsoft Academic Search

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

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

2002-01-01

38

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

39

Multinuclear magnetic resonance studies of gaseous and liquid dimethyl ethers  

NASA Astrophysics Data System (ADS)

Dimethyl ethers (DME): (CH3)2O, CH3OCD3, (CD3)2O have been studied using advanced NMR spectroscopy in liquid and gaseous states at 300 K. Extrapolation of the gas-phase results to the zero-density limit permitted the measurements of 1H, 13C and 17O nuclear magnetic shieldings of isolated DME molecules. The significance of intermolecular effects in the gaseous state as well as by coming from gas to liquid are also reported; measured gas-to-liquid shifts for 13C and 17O nuclei are negative (deshielding effects) but positive for 1H nuclei. The very weak linear dependence on density has also been observed for the carbon-proton and carbon-deuteron scalar coupling constants over one bond in the appropriate methyl group of DME. It was possible to obtain the coupling constants free from intermolecular interactions: 1J0(CH)=138.84 Hz in (CH3)2O, 1J0(CH)=138.81 Hz and 1J0(CD)=21.17 Hz in CH3OCD3 and 1J0(CD)=21.16 Hz in (CD3)2O. The magnitude of isotope effects on nuclear shieldings and indirect coupling constants caused by H/D substitution is also discussed. These new experimental results are suitable for a better verification of ab initio calculations of indirect coupling constants and nuclear magnetic shieldings of all nuclei in molecules under study.

Makulski, W?odzimierz

2005-06-01

40

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

41

Measurements of burning velocities of dimethyl ether and air premixed flames at elevated pressures  

Microsoft Academic Search

Laminar burning velocities of dimethyl ether (DME) and air premixed flames at elevated pressures up to 10atm were measured by using a newly developed pressure-release type spherical bomb. The measurement system was validated using laminar burning velocities of methane–air flames. A comparison with the previous experimental data shows an excellent agreement and demonstrates the accuracy and reliability of the present

Xiao Qin; Yiguang Ju

2005-01-01

42

Simulation of a two-stroke dimethyl -ether free piston engine operating on HCCI combustion  

Microsoft Academic Search

This paper investigates the combustion process and characteristics of a two-stroke dimethyl -ether (DME) free piston engine operating on Homogeneous Charge Compression Ignition (HCCI) combustion, using a one-dimensional dynamics model and a three-dimensional computational fluid dynamics (CFD) model. Through the simulation the feasibility of the design was verified. A wide range of design and operating options were investigated including the

Xutao; Wangyang

2011-01-01

43

Intrinsic reaction rate and the effects of operating conditions in dimethyl ether synthesis from methanol dehydration  

Microsoft Academic Search

The kinetic behavior of a commercial ?-Al2O3 catalyst for the methanol to dimethyl ether (DME) dehydration reaction has been investigated using a differential fixed bed\\u000a reactor at the pressure range 1–16 barg within a temperature range of 260–380 °C. The experimental runs were performed in\\u000a a wide range of feed to water ratios. The experiments were designed by general full

Gholamreza Moradi; Fereydoon Yaripour; Hossein Abbasian; Mostefa Rahmanzadeh

2010-01-01

44

Synthesis of AlOOH slurry catalyst and catalytic activity for methanol dehydration to dimethyl ether  

Microsoft Academic Search

AlOOH slurry catalysts were prepared by complete liquid-phase technology from aluminum iso-propoxide (AIP). Dehydration of methanol to dimethyl ether (DME) over these catalysts was investigated in slurry reactor. The catalysts were characterized by X-ray diffraction(XRD), nitrogen adsorption, temperature-programmed desorption of ammonia (NH3-TPD). The results showed that the slurry catalysts had high specific surface area and pore volume, and the specific

Lei Liu; Wei Huang; Zhi-hua Gao; Li-hua Yin

45

Study on proton-conducting solid oxide fuel cells with a conventional nickel cermet anode operating on dimethyl ether  

Microsoft Academic Search

This study investigates dimethyl ether (DME) as a potential fuel for proton-conducting SOFCs with a conventional nickel cermet anode and a BaZr0.4Ce0.4Y0.2O3?? (BZCY4) electrolyte. A catalytic test demonstrates that the sintered Ni+BZCY4 anode has an acceptable catalytic activity for the decomposition and steam reforming of DME with CO, CH4 and CO2 as the only gaseous carbon-containing products. An O2-TPO analysis

Yu Liu; Youmin Guo; Wei Wang; Chao Su; Ran Ran; Huanting Wang; Zongping Shao

2011-01-01

46

Evaluation of Pd-based catalysts and the influence of operating conditions for autothermal reforming of dimethyl ether  

Microsoft Academic Search

A series of different Pd-based catalysts supported on ceramic monoliths were synthesized and tested in a screening study for autothermal reforming of dimethyl ether (DME). Alumina-supported Pd was shown to be very active for this reaction at temperatures between 350 and 400°C. Adding Zn to Pd\\/?-Al2O3 decreased the activity of decomposition reactions leading to better reforming activity, and resulting in

Marita Nilsson; Peter Jozsa; Lars J. Pettersson

2007-01-01

47

The direct synthesis of dimethyl ether from syngas over hybrid catalysts with sulfate-modified ?-alumina as methanol dehydration components  

Microsoft Academic Search

A series of ?-Al2O3 samples modified with various contents of sulfate (0–15wt.%) and calcined at different temperatures (350–750°C) were prepared by an impregnation method and physically admixed with CuO–ZnO–Al2O3 methanol synthesis catalyst to form hybrid catalysts. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the prepared hybrid catalysts under pressurized fixed-bed continuous flow conditions. The

Dongsen Mao; Weimin Yang; Jianchao Xia; Bin Zhang; Guanzhong Lu

2006-01-01

48

Direct synthesis of dimethyl ether from carbon-monoxide-rich synthesis gas: Influence of dehydration catalysts and operating conditions  

Microsoft Academic Search

Various dehydration catalysts were studied in the synthesis of dimethyl ether (DME) directly from carbon-monoxide-rich synthesis gas under a series of different reaction conditions. The investigated catalyst systems consisted of combinations of a methanol catalyst (CuO\\/ZnO system) with catalysts for methanol dehydration based on ?-Al2O3 or zeolites and ?-Al2O3 was identified as the most favorable dehydration catalyst. Various reaction parameters

Miriam Stiefel; Ruaa Ahmad; Ulrich Arnold; Manfred Döring

2011-01-01

49

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

50

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

2009-04-22

51

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

52

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

53

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.  

National Technical Information Service (NTIS)

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 c...

B. L. Bhatt

1992-01-01

54

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

Microsoft Academic Search

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

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

2004-01-01

55

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

Microsoft Academic Search

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

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

2003-01-01

56

DME-Fired Water-Tube Boiler─A R&D Study  

Microsoft Academic Search

Increasing attention has been given to the development of low-NOx combustion technology for DME (Dimethyl Ether). The present paper describes the R&D study for water-tube boiler carried out in Kansai University and Hirakawa Guidam Co., Ltd. under the support of DME project from METI. The major problem in DME use is the difficulty in the application of premixed flame due

Mamoru Ozawa; Ryosuke Matsumoto; Nobuo Higuchi; Yoshio Hayashi; Hiroki Uematsu; Yoshitaka Suita

2006-01-01

57

Internal motions in a complex consisting of a rare gas atom and a C2v molecule: Theoretical formulations and their applications to Fourier transform microwave spectra of Ne-dimethyl ether and Ar-dimethyl ether  

NASA Astrophysics Data System (ADS)

The internal motion of the rare gas atom, i.e., the relative motion of the two constituents, in a complex shown in the title was discussed by paying special attention to its effect on the rotational motion of the complex in order to extract as much precise information on this motion as possible from the observed rotational spectra. We have set up two theoretical formulations. One is based on a coordinate axis system attached to the C2v molecule, but its origin is floating with the motion of the rare gas atom, while keeping the orientation parallel to the original C2v molecule-fixed coordinate system. The second approach starts with counting the number of equivalent potential minima, which are well separated from the others by high potential barriers, and then collects all permutation-inversion operations, which transform the system from one minimum to another, to set up a group appropriate for the complex. By using the symmetry properties thus derived, a phenomenological Hamiltonian is set up to fit the observed spectra. The two formulations result in alike rotational energy matrices, and we have applied them to analyze the internal motions in the two complexes of present concern: neon-dimethyl ether (Ne-DME) and argon-dimethyl ether (Ar-DME). Some of the transitions observed by the present study exhibited additional splittings, which were interpreted as due to an internal rotation of the methyl groups in DME and were analyzed by the second formulation. For Ar-DME the splittings appeared only in high-K transitions, yielding the V3 potential barrier to be 778(1) cm-1, whereas those observed for Ne-DME were ascribed to the effects of the CH3 internal rotation on the inversion splitting.

Morita, Yasumasa; Ohashi, Nobukimi; Kawashima, Yoshiyuki; Hirota, Eizi

2006-03-01

58

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

59

Performance Estimation of Absorption/Compression Cycle Using Working Pair Dimethyle Ether/Methanol  

NASA Astrophysics Data System (ADS)

This paper presents the performance estimation of hybrid absorption/compression heat pump cycle, which use dimethyl ether (DME) and methanol pair as a working fluid. The disadvantage of the DME as a refrigerant is that it is flammable. But it has several advantages from the environmental aspects; toxicity is very low, and GWP is small. The first purpose of this study is to estimate the reduction of the loss of the heat exchangers, by use of absorption/compression cycle. And the second purpose is to lower the working pressure to reduce the possibility of the leakage of the working fluids. Two hybrid systems are supposed as models; one is absorption/compression system with single stage solution circuit, and another is an absorption/compression system with generator/absorber heat exchange cycle. The former cycle exceeds the cooling and heating COPs of pure DME cycle, reducing the maximum pressure about 130 kPa. And the latter system increases the heating COP by 6 to 36% with the working pressure range about 150-260 kPa.

Endo, Naok; Maeda, Tetsuhiko; Hasegawa, Yasuo

60

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

61

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

62

Uncertainties in the flash point of dimethyl ether  

Microsoft Academic Search

Using the principles of flammability limits and stoichiometry, the currently accepted value for the flash point of dimethyl ether is shown to be incorrect. A corrected value is calculated, and this is about 40°C lower.

J. C. Jones

2001-01-01

63

Kinetic Understanding of the Syngas-to-DME Reaction System and It's Implications to Process and Economics.  

National Technical Information Service (NTIS)

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 dehydr...

X. D. Peng

2002-01-01

64

Liquid-phase preparation of catalysts used in slurry reactors to synthesize dimethyl ether from syngas: Effect of heat-treatment atmosphere  

Microsoft Academic Search

A CuZnAl slurry catalyst was prepared directly from a solution of metal salts by an entirely liquid-phase method. The influence of heat-treatment atmospheres with different proportions of CO2 on the single-step synthesis of dimethyl ether (DME) from syngas was investigated and the catalysts were characterized by powder X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), temperature-programmed desorption of ammonia (NH3-TPD), X-ray

Zhihua Gao; Wei Huang; Lihua Yin; Kechang Xie

2009-01-01

65

Highly effective hybrid catalyst for the direct synthesis of dimethyl ether from syngas with magnesium oxide-modified HZSM-5 as a dehydration component  

Microsoft Academic Search

A series of HZSM-5 zeolites modified with various contents of magnesium oxide (0–10 wt%) were prepared with an incipient impregnation technique and characterized by X-ray diffraction, N2 adsorption, temperature-programmed desorption of NH3 and CO2, 27Al MAS NMR, and FT-IR. The modified HZSM-5 zeolites were mixed physically with methanol synthesis components (CuO–ZnO–Al2O3) to perform the direct synthesis of dimethyl ether (DME)

Dongsen Mao; Weimin Yang; Jianchao Xia; Bin Zhang; Qingying Song; Qingling Chen

2005-01-01

66

Microstructure and properties of CVD tungsten carbide from tungsten hexafluoride and dimethyl ether  

SciTech Connect

Tungsten carbide was deposited from tungsten hexafluoride, dimethyl ether, and hydrogen using a horizontal, cold-wall reactor. The effects of substrate temperature, reactor pressure, and reagent ratio on the coating growth rate, morphology, composition, and microhardness were studied. Under most conditions, the solid deposit was primarily W[sub 3]C with minor amounts of W. The tungsten carbide growth rate data fit an Arrhenius rate expression for temperatures from 425 to 550 C and had an activation energy of 24 kcal/mol at 70 mmHg total pressure and a WF[sub 6]/DME ratio of 6.3. A variety of surface morphologies and microstructures were observed. The microhardness of the coated substrates increased with coating thickness to a maximum value of 2,400 kg/mm[sup 2].

Skaf, D.W.; Warner, A.W.; Dollahon, N.R.; Fargo, G.H. (Villanova Univ., PA (United States))

1994-12-01

67

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

68

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

69

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

70

Formation of Methanol and Dimethyl Ether in Dielectric Barrier Disch arges  

NASA Astrophysics Data System (ADS)

The generation of liquid fuels like methanol (MeOH) and dimethyl ether (DME) from the greenhouse gases (GHG) methane and carbon dioxide has recently attracted growing attention. Investigations of this kind are part of efforts to reduce GHG emissions to the atmosphere. For our investigations we used a tubular dielectric barrier discharge reactor with an annular discharge gap of 1 mm width and a cylindrical quartz dielectric of 2.5 mm thickness. It was operated in methane-oxygen mixtures at pressures between 1 and 4 bar. The discharge was operated at a frequency of about 18 kHz. The power density could be raised up to 20 kW/m^2 of electrode area by increasing the applied voltage. Up to 1.3% MeOH and .4% DME were measured after a single passage through a discharge gap of 310 mm length by GC and GC/MS detection. These values were obtained at 2 bar, substantially lower values were measured at 1 or 4 bar operating pressure. At high specific energies >8 eV per molecule of feed gas the MeOH concentration decreased and methyl formate appeared in the product stream.

Kogelschatz, Ulrich

1996-10-01

71

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

Federal Register 2010, 2011, 2012, 2013

...FRL-8805-3] Oxirane, 2-Methyl-, Polymer with Oxirane, Dimethyl Ether; Tolerance...for residues of oxirane, 2-methyl-,polymer with oxirane, dimethyl ether (CAS Reg...for residues of oxirane, 2-methyl-, polymer with oxirane, dimethyl ether (CAS...

2010-01-27

72

Propagation and extinction of premixed dimethyl-ether\\/air flames  

Microsoft Academic Search

Laminar flame speeds and extinction strain rates of dimethyl-ether\\/air mixtures were measured at room temperature and atmospheric pressure over a wide range of equivalence ratios. The experiments were performed in the counterflow configuration, and included the use of digital particle image velocimetry and laser Doppler velocimetry. The laminar flame speeds were experimentally determined using a new nonlinear extrapolation technique, which

Y. L. Wang; A. T. Holley; C. Ji; F. N. Egolfopoulos; T. T. Tsotsis; H. J. Curran

2009-01-01

73

Overall Spray Characteristics of Dimethyl ether and Biodiesel Fuel under the Ambient Pressure Conditions in a High Pressure Chamber  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to investigate the effect of the ambient pressure on the overall spray characteristics of dimethyl ether (DME) and biodiesel fuel spray in a high-pressure combustion chamber. In order to investigate the spray performance under the various ambient pressure conditions, the high-pressure combustion chamber, which can be controlled by nitrogen gas to obtain the ambient pressure conditions, was applied. To determine the macroscopic structure of the spray, such as the spray development process and the axial/radial distance, frozen images of the spray can be obtained directly using a high-speed camera with a light source according to the elapsed time after energizing begins. At the same time, the results from the DME and biodiesel spray under atmospheric conditions were compared with the results from the spray under various ambient pressure conditions in the chamber. According to the spray characteristics, the axial and maximum radial distances of the biodiesel and DME spray decreased with an increase in the ambient pressure. Also, it was shown that the SMD (Sauter mean diameter) of droplets becomes smaller than that of the spray under the atmosphere condition as the ambient pressure in the high pressure chamber increases.

Kim, Hyung Jun; Park, Su Han; Lee, Chang Sik

74

Effect of surface hydroxyls on dimethyl ether synthesis over the ?-Al2O 3 in liquid paraffin: a computational study.  

PubMed

In a recent paper (Zuo et al., Appl Catal A 408:130-136, 2011), the mechanism of dimethyl ether (DME) synthesis from methanol dehydration over ?-Al2O3 (110) was studied using density functional theory (DFT). Using the same method, the effect of surface hydroxyls on ?-Al2O3 in liquid paraffin during DME synthesis from methanol dehydration is investigated. It is found that DME is mainly formed from two adsorbed CH3O groups via methanol dehydrogenation on both dehydrated and hydrated ?-Al2O3 in liquid paraffin. No close correlation between catalytic activity and acid intensity was found. Before and after water adsorption at typical catalytic conditions (e.g., 553 K), the reaction rate is not obviously changed on ?-Al2O3(100) surface in liquid paraffin, but the reaction rate decreases by about 11 times on the (110) in liquid paraffin. Considering the area of the (110) and (100) surfaces under actual conditions, the catalytic activity decreased mainly because the Al3 sites on the (110) surface gradually become inactive. Catalytic activity decreased mainly due to surface hydrophilicity. The calculated results were consistent with the experiment. PMID:24057976

Zuo, Zhi-Jun; Wang, Le; Han, Pei-de; Huang, Wei

2013-09-22

75

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.

Meyers, A J

1982-01-01

76

Dimethyl ether steam reforming under daily start-up and shut-down (DSS)-like operation over CuFe 2O 4 spinel and alumina composite catalysts  

Microsoft Academic Search

The durability of the CuFe2O4 spinel and ?-Al2O3 composite catalysts for steam reforming of dimethyl ether (DME) was evaluated at 375°C for 120h under the daily start-up and shut-down (DSS) operation. No degradation could be observed for the catalyst subjected to the cooling–heating process in O2 atmosphere. On the other hand, the catalyst performance was significantly degraded by the cooling–heating

N. Shimoda; H. Muroyama; T. Matsui; K. Faungnawakij; R. Kikuchi; K. Eguchi

77

Low NOx Combustion of DME by Means of Flue Gas Recirculation  

Microsoft Academic Search

This study focuses on the fundamental characteristics of DME (Dimethyl Ether) combustion aiming at development of low-NOx combustion technology with flue gas recirculation, FGR. The flue gas is recirculated into the combustion chamber to reduce the oxygen concentration and to suppress the combustion gas temperature, so that NOx emission is significantly reduced. The fuel gas recirculation at high mixing ratio,

Ryosuke Matsumoto; Mamoru Ozawa; Shinya Terada; Takenori Iio

2008-01-01

78

Performance of long straw tubes using dimethyl ether  

NASA Astrophysics Data System (ADS)

A cylindrical tracking detector with an inner radius of one meter employing straw tubes is being envisaged for the FINUDA experiment aimed at hyper-nuclear physics at DA?NE, the Frascati ?-factory. A prototype using several 10 mm and 20 mm diameter, two meter long aluminized mylar straws has been assembled and tested with a one GeV// c pion beam. While operating with dimethyl ether, gas gain, space resolution, and device systematics have been studied. A simple method of correction for systematics due to straw eccentricity has been developed and, once applied, a space resolution better than 40 ?m can be reached.

Benussi, L.; Bertani, M.; Bianco, S.; Fabbri, F. L.; Gianotti, P.; Giardoni, M.; Guaraldo, C.; Lanaro, A.; Lucherini, V.; Mecozzi, A.; Passamonti, L.; Russo, V.; Sarwar, S.

1995-02-01

79

Development of Low-NOx DME Multi-Port Burner  

Microsoft Academic Search

This study focuses on the fundamental characteristics of DME (Dimethyl Ether) combustion, aiming at the development of low-NOx multi-port burner suitable for the tube-nested combustor. In the tube-nested combustion, the water tubes are moved into the furnace closely to the burner to cool the burning flame directly in the field of burning reaction leading to NOx reduction. To prevent the

Ryosuke Matsumoto; Mamoru Ozawa; Isao Ishihara; Shingo Sasaki; Masahiro Takaichi

2006-01-01

80

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.

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

1976-01-01

81

Why (1 0 0) terraces break and make bonds: oxidation of dimethyl ether on platinum single-crystal electrodes.  

PubMed

A surface structural preference for (1 0 0) terraces of fcc metals is displayed by many bond-breaking or bond-making reactions in electrocatalysis. Here, this phenomenon is explored in the electrochemical oxidation of dimethyl ether (DME) on platinum. The elementary C-O bond-breaking step is identified and clarified by combining information obtained from single-crystal experiments and density functional theory (DFT) calculations. Experiments on Pt(1 0 0), Pt(5 1 0), and Pt(10 1 0) surfaces show that the surface structure sensitivity is due to the bond-breaking step, which is unfavorable on step sites. DFT calculations suggest that the precursor for the bond-breaking step is a CHOC adsorbate that preferentially adsorbs on a square ensemble of four neighboring atoms on Pt(1 0 0) terraces, named as "the active site". Step sites fail to strongly adsorb CHOC and are, therefore, ineffective in breaking C-O bonds, resulting in a decrease in activity on surfaces with increasing step density. Our combined experimental and computational results allow the formulation of a new mechanism for the electro-oxidation of DME as well as a simple general formula for the activity of different surfaces toward electrocatalytic reactions that prefer (1 0 0) terrace active sites. PMID:23980577

Li, Hongjiao; Calle-Vallejo, Federico; Kolb, Manuel J; Kwon, Youngkook; Li, Yongdan; Koper, Marc T M

2013-09-13

82

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

83

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

84

Alternariol 9-O-methyl ether dimethyl sulfoxide monosolvate  

PubMed Central

The title compound (systematic name: 3,7-dihy­droxy-9-meth­oxy-1-methyl-6H-benzo[c]chromen-6-one dimethyl sulfoxide monosolvate), C15H12O5·C2H6OS, was isolated from an unidentified endophytic fungus (belonging to class Ascomycetes) of Taxus sp. In the crystal, both the alternariol 9-O-methyl ether (AME) and the dimethyl sulfoxide (DMSO) mol­ecules exhibit crystallographic mirror symmetry. One of the hy­droxy groups makes bifurcated hydrogen bonds, viz. an intra­molecular bond with the carbonyl group and an inter­molecular bond with the carbonyl group in an inversion-related AME mol­ecule. In the crystal, the AME mol­ecules are organized into stacks parallel with the b axis by ?–? inter­actions between centrosymmetrically related mol­ecules [the distance between the centroid of the central ring and the centroid of the meth­oxy-substituted benzene ring in the next mol­ecule of the stack is 3.6184?(5)?Å]. Pairs of DMSO mol­ecules, linked via centrosymmetric C—H?O contacts, are inserted into the voids created by the AME mol­ecules, making O—H?O and C—H?O contacts with the hosts.

Dasari, Sreekanth; Miller, Kristin I.; Kalaitzis, John A.; Bhadbhade, Mohan; Neilan, Brett A.

2013-01-01

85

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

86

Investigation of Hythane, LPG and DME Laminar Flame Speed by Ionization Current Method in a Constant Volume Bomb  

Microsoft Academic Search

The centrally ignited, spherically expanding flames for mathane-hydrogen (hythane), liquified petroleu m gas (LPG) and dimethyl ether (DME) were recorded by Schlieren photography in a bomb. The ionization current between the electrodes was sampled and characterized correspondingly to the combustion process. The relationship b etween the laminar flame speed and the current is established by the correlation theory. The results

Wu Xiaomin; Gao Zhongquan; Meng Xiangwen

87

Carbon dioxide tolerance in the single-stage liquid-phase synthesis of dimethyl ether  

SciTech Connect

In the liquid-phase dimethyl ether process, methanol synthesis catalyst (Cu/ZnO/Al{sub 2}O{sub 3}) and methanol dehydration catalyst ({gamma}-alumina) are slurred in an inert liquid medium. The inert liquid medium used in this investigation is a white mineral oil, Witco-40. This multiphase reaction is conducted in a mechanically agitated slurry reactor. In this process, syngas conversion can be significantly improved by coproduction of dimethyl ether along with methanol. The coproduction strategy improves the thermodynamic and kinetic environment of the reaction system. The effects of catalyst loadings in the slurry and the roles played by carbon dioxide in dimethyl ether synthesis were studied by conducting kinetic experiments. The liquid-phase dimethyl ether synthesis process exhibits higher carbon dioxide tolerance as compared to the liquid-phase methanol synthesis process, whose optimal carbon dioxide concentration in the unbalanced syngas feed is around 8%. These results have been experimentally confirmed.

Sardesai, A.; Gunda, A.; Tartamella, T.; Lee, S.

2000-01-01

88

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

89

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

90

CONVERSION OF DIMETHYL ETHER-BORON TRIFLUORIDE COMPLEX TO POTASSIUM FLUOBORATE  

DOEpatents

A method of preparing KBF/sub 4/ from the dimethyl ether complex of BF/sub 3/ is given. This may be accomplished by introducing the dimethyl ether complex of BF/sub 3/ into an aqueous solution of KF and alcohol, expelling the ether liberated from the complex by heating or stirring and recovering the KBF/sub 4/ so formed. The KBF/sub 4/ is then filtered from the alcohol-water solution, which may be recycled, to reduce the loss of KBF/sub 4/ which is not recovered by filtration.

Eberle, A.R.

1957-06-18

91

Study of dimethyl ether for limited streamer tubes  

NASA Astrophysics Data System (ADS)

Position resolution and lifetime have been studied for one-atmosphere DME in half-inch diameter aluminum tube chambers operated in the limited streamer mode. The radial resolution was measured by timing to be ?r = 73 ?m. The longitudinal resolution was measured by charge division to be <0.3% of the wire length. No significant gain changes were seen after 12 C/cm.

Wang, Y.-X.; Godfrey, G.

1992-08-01

92

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+/-11.8cal/mol for (CH3)2O, (CD3)2O, (CH3)2S, (CH3)2SiH2, (CH3)2SiD2, and (CH3)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 (CH3)2O and (CD3)2O which are small but not negligible (V'12=-124.4,-158.0cal/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+/-15.2cal/mol for CH3OCD3 and CH3SCD3. The corrected barrier, V3(CD3) of CH3OCD3, is obtained to be 2634.4+/-7.1cal/mol, while that of CH3SCD3 cannot be solved due to the lack of the data available. It is with great sadness that we report the passing of Professor Emeritus Michiro Hayashi, who died after a short illness on July 9, 2003.

Niide, Yuzuru; Hayashi, Michiro

2004-02-01

93

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

94

The influence of different methanol synthesis catalysts on direct synthesis of DME from syngas  

Microsoft Academic Search

Methanol synthesis catalysts based on Cu–Zn–Al prepared under different precipitation conditions with the use of Zr or not as a promoter were studied in the direct synthesis of dimethyl ether (DME) using H-ferrierite as a dehydration component. Samples prepared under high supersaturation conditions showed textural and structural changes without any relation to the CO conversion. Samples containing zirconium favored an

J. H. Flores; D. P. B. Peixoto; L. G. Appel; R. R. de Avillez; M. I. Pais da Silva

2011-01-01

95

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

96

Development of Low-NOx DME Multi-Port Burner  

NASA Astrophysics Data System (ADS)

This study focuses on the fundamental characteristics of DME (Dimethyl Ether) combustion, aiming at the development of low-NOx multi-port burner suitable for the tube-nested combustor. In the tube-nested combustion, the water tubes are moved into the furnace closely to the burner to cool the burning flame directly in the field of burning reaction leading to NOx reduction. To prevent the unburned combustibles emission, the diffusion burner used in the tube-nested combustor needs a high performance of the fuel-air mixing. Multi-port burner consists of a fuel-port and surrounding multi-air-ports, which induce a strong re-circulation flow. Thus the fuel-air mixing is enhanced so that the thermal NOx and CO emissions are significantly reduced. The NOx emission of the DME from the co-axial diffusion burner was over 130ppm at 0% O2. On the other hand, NOx emission of DME from the multi-port burner was reduced to 60ppm at 0% O2. With the help of the tube-nested combustion, NOx emission of DME was further reduced to 20ppm at 0% O2.

Matsumoto, Ryosuke; Ozawa, Mamoru; Ishihara, Isao; Sasaki, Shingo; Takaichi, Masahiro

97

Infrared reflection absorption spectroscopic study of the adsorption structures of dimethyl ether and methyl ethyl ether on Cu(1 1 1) and Ag(1 1 1)  

NASA Astrophysics Data System (ADS)

Infrared reflection absorption (IRA) spectra measured for dimethyl ether (DME) adsorbed at 80 K on Cu(1 1 1) and Ag(1 1 1) give IR bands belonging only to the A1 and B2 species, indicating that the adsorbate takes on an orientation in which the C2 axis bisecting the COC bond angle tilts away from the surface normal within the plane perpendicular to the substrates. The DFT method was applied to simulate the IRA spectra, indicating that the tilt angles of DME on Cu(1 1 1) and Ag(1 1 1) are about 50° and 55°, respectively, at submonolayer coverages. The results are in contrast to the case of DME on Cu(1 1 0) and Ag(1 1 0), where the C2 axis is perpendicular to the substrates [T. Kiyohara et al., J. Phys. Chem. A 106 (2002) 3469]. Methyl ethyl ether (MEE) adsorbed at 80 K on Cu(1 1 1) gives IRA bands mainly ascribable to the gauche (G) form, whereas the IRA spectra measured for MEE on Ag(1 1 1) are characterized by the trans (T) form. The rotational isomers are identical with those on Cu(1 1 0) and Ag(1 1 0); i.e., MEE on Cu(1 1 0) takes the G form and the adsorbate on Ag(1 1 0) the T form [T. Kiyohara et al., J. Phys. Chem. B 107 (2003) 5008]. The simulation of the IRA spectra indicated that (i) the G form adsorbate on Cu(1 1 1) takes an orientation, in which the axis bisecting the COC bond angle tilts away from the surface normal by ca. 30° within the plane perpendicular to the surface to make the CH3 CH2 bond almost parallel to the surface, and (ii) the T form adsorbate on Ag(1 1 1) takes an orientation, in which the bisecting axis tilts away by ca. 60° from the surface normal within the perpendicular plane. Comparison of these adsorption structures of MEE on the (1 1 1) substrates with those of MEE on Cu(1 1 0) and Ag(1 1 0) indicates that the structures are mainly determined by a coordination interaction of the oxygen atom to the surface metals and an attractive van der Waals interaction between the ethyl group of MEE and the substrate surfaces. The coordination interaction plays an important role on Cu(1 1 1) and Cu(1 1 0), which makes the adsorbate on the Cu substrates to take the orientations with the bisecting axis near parallel to the surface normal and to assume the G form in order to make the ethyl group parallel to the surface, which is favorable for the van der Waals interaction. In the case of MEE on the Ag substrates the attractive van der Waals interaction plays a dominant role, resulting in the T form which is more favorable for the interaction than the G form.

Kasahara, Takahiro; Itoh, Koichi

2007-02-01

98

A comparative study on the extinction characteristics of non-premixed dimethyl ether and ethanol flames  

Microsoft Academic Search

The extinction characteristics of non-premixed dimethyl ether and ethanol flames were investigated in order to assess the effect of the molecular structure on the combustion behavior of two otherwise similar fuels. The experiments were conducted in the stagnation flow configuration by counterflowing streams of fuel diluted in nitrogen against pure oxygen. Extinction strain rates were determined at atmospheric pressure and

Yang L. Wang; Peter S. Veloo; Fokion N. Egolfopoulos; Theodore T. Tsotsis

2011-01-01

99

Dehydration of methanol over Nordstrandite based catalysts for dimethyl ether synthesis  

Microsoft Academic Search

This study focused on the investigation of Nordstrandite as a catalyst for dehydration of methanol to dimethyl ether synthesis. The structure phase of Nordstrandite has been changed to boehmite and ?-Al2O3 in sequence via calcinations at various temperatures. Moreover, the properties of the samples have been varied significantly with heat treatment. The number of acid sites of Nordstrandite was much

Chang Won Seo; Kwang Deok Jung; Kwan Young Lee; Kye Sang Yoo

2009-01-01

100

Effect of thermodynamic history on secondary relaxation in glassy phenolphthalein-dimethyl-ether  

Microsoft Academic Search

We present a study of the intermediate secondary relaxation process of phenolphthalein-dimethyl-ether. Though this process is intramolecular in nature, it reveals pronounced pressure dependence. Moreover, its relaxation frequency and intensity exhibit pronounced dependence on the thermal history followed during vitrification. These results suggest that the nonequilibrium nature of the glassy state influences this secondary relaxation principally through the dependence on

D. Prevosto; S. Capaccioli; M. Lucchesi; P. A. Rolla; M. Paluch; S. Pawlus

2006-01-01

101

Thermodynamic Properties of Poly(2,6-Dimethyl-1,4-Phenylene Ether).  

National Technical Information Service (NTIS)

The thermodynamic properties of crystalline and amorphous poly(2,6-dimethyl-1,4-phenylene ether) were studied calorimetrically between 80 and 570 deg./K. The calculated configurational entropy of this polymer, of similar magnitude to other glass-forming l...

F. E. Karasz H. E. Bair J. M. O'Reilly

1967-01-01

102

Life cycle inventory analysis on Bio-DME and\\/or Bio-MeOH products through BLUE tower process  

Microsoft Academic Search

Background, aims, and scope  In this study, we focused on the biomass di-methyl ether (Bio-DME) and the biomass methanol (Bio-MeOH) in BTL (Biomass to\\u000a Liquid) fuels which might bring a solution on an energy storage and\\/or CO2 emissions abatement. For these fuels, our object is to estimate CO2 emissions and energy intensities (the specific energy consumption in each sub-process) for the

Kiyoshi Dowaki; Yutaka Genchi

2009-01-01

103

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: kOH+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 kOH+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 kOH+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%: kOH+DME = 8.45 × 10(-18) (T/K)(2.07) exp(262.2 K/T) cm(3) s(-1). For kOH+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

2013-08-20

104

On board dimethyl ether generation to assist methanol engine cold starting  

SciTech Connect

Dimethyl ether has high vapor pressure and wide flammability limits, which make it an excellent fuel for cold starting methanol engines. The authors have investigated the catalytic dehydration of methanol to produce dimethyl ether on board methanol-fueled vehicles. They tested four methanol dehydration catalysts in a microcatalytic plug flow reactor and found that a fluorinated /gamma/-alumina was very active and selective for methanol dehydration in the 250-350/sup 0/C (482-662/sup 0/F) temperature range. They also tested the fluorinated /gamma/-alumina catalyst with a 15% gasoline/85% methanol mixture (M85) and found that the catalyst activity decreased in proportion to the gasoline content but that no catalyst deactivation occurred.

Karpuk, M.E.; Cowley, S.W

1988-01-01

105

Microstructure and properties of CVD tungsten carbide from tungsten hexafluoride and dimethyl ether  

Microsoft Academic Search

Tungsten carbide was deposited from tungsten hexafluoride, dimethyl ether, and hydrogen using a horizontal, cold-wall reactor. The effects of substrate temperature, reactor pressure, and reagent ratio on the coating growth rate, morphology, composition, and microhardness were studied. Under most conditions, the solid deposit was primarily W[sub 3]C with minor amounts of W. The tungsten carbide growth rate data fit an

D. W. Skaf; A. W. Warner; N. R. Dollahon; G. H. Fargo

1994-01-01

106

Nanocrystalline gamma-alumina: A highly active catalyst for dimethyl ether synthesis  

Microsoft Academic Search

In this article, mesoporous nanocrystalline ?-Al2O3 with high surface area is synthesized by a simple sol–gel method with cationic surfactant as template. This sample is used for vapor-phase dehydration of methanol to Dimethyl ether. The synthesized catalyst showed a high surface area of 375m2g?1 and a crystallite size of about 3.9nm. NH3-TPD analysis revealed that the sample with smaller crystallite

Ahmad Reza Keshavarz; Mehran Rezaei; Fereydoon Yaripour

2010-01-01

107

A column packing for isothermal gas chromatographic analysis of C 1 ?C 5 paraffins and monoolefins and dimethyl ether  

Microsoft Academic Search

An analytical GC method was developed which uses a single packed column consisting of three packings in series prepared with the following liquid phases: dimethyl sulfolane, propylene carbonate, and silver nitrate. This system provides satisfactory resolution of mixtures of C1?C5 hydrocarbons and dimethyl ether obtained when converting methanol to gasoline. Due to the high capacity of the column it is

L. W. Zatorski; A. Cichowlas

1981-01-01

108

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

109

Bio-refinery system of DME or CH4 production from black liquor gasification in pulp mills.  

PubMed

There is great interest in developing black liquor gasification technology over recent years for efficient recovery of bio-based residues in chemical pulp mills. Two potential technologies of producing dimethyl ether (DME) and methane (CH(4)) as alternative fuels from black liquor gasification integrated with the pulp mill have been studied and compared in this paper. System performance is evaluated based on: (i) comparison with the reference pulp mill, (ii) fuel to product efficiency (FTPE) and (iii) biofuel production potential (BPP). The comparison with the reference mill shows that black liquor to biofuel route will add a highly significant new revenue stream to the pulp industry. The results indicate a large potential of DME and CH(4) production globally in terms of black liquor availability. BPP and FTPE of CH(4) production is higher than DME due to more optimized integration with the pulping process and elimination of evaporation unit in the pulp mill. PMID:19767203

Naqvi, M; Yan, J; Fröling, M

2009-09-19

110

Resonance multiphoton ionization and dissociation of dimethyl ether via the {\\skew1\\tilde{\\rm C}^{\\prime}}, {\\skew1\\tilde{\\rm C}} and \\tilde{\\rm B} states  

NASA Astrophysics Data System (ADS)

The three-photon resonance four-photon ionization and dissociation spectra of dimethyl ether (DME) are presented in the wavelength range 450-550 nm at 1 nm intervals. The (3+1) REMPI spectra show three prominent bands corresponding to the \\tildeB \\leftarrow \\skew1\\tildeX, {\\skew1\\tildeC} \\leftarrow \\skew1\\tildeX and {\\skew1\\tildeC^{\\prime}} \\leftarrow \\skew1\\tildeX transitions with origins at 61 457 cm-1 (7.615 eV), 59 055 cm-1 (7.322 eV) and 58 010 cm-1 (7.194 eV), respectively. Several ionized species, CH3+, CHnO+ (n = 1-3) and CH3OCH3+, are observed in the region of wavelengths studied here. In order to compare the results, a shorter wavelength multiphoton dissociation and ionization of DME at 355 nm is also presented. At this wavelength, DME undergoes neutral dissociation to CH3 and CH3O and each fragment is then ionized by multiphoton absorption. The fragmentation at 355 nm is very intense and only small fragments such as CH3+, CHO+, CH2+, CH+ and C+ ions are observed. The measurement of photoelectron energy allows us to establish that the DME ionization potential is at least 9.55 ± 0.15 eV. The experiments were performed using a Nd:YAG-OPO (optical parametric oscillator) tunable laser system coupled to a time-of-flight mass spectrometer and a hemispherical electron energy analyser.

Mejia-Ospino, E.; García, G.; Guerrero, A.; Alvarez, I.; Cisneros, C.

2005-01-01

111

Study of the conversion of methanol to dimethyl ether on zeolite HZSM-5 using in situ flow MAS NMR.  

PubMed

The conversion of methanol to gasoline (MTG) range hydrocarbons on zeolite catalyst HZSM-5 has been studied extensively using solid-state NMR. We have studied the reaction under batch and flow conditions using an isolated flow variable-temperature (VT) MAS NMR probe. This probe was developed to study heterogeneous catalysis reactions in situ at temperatures greater than 300 degrees C with reactant flow. In the batch studies, when 13C-labeled methanol was adsorbed on zeolite HZSM-5, sealed, and heated to 250 degrees C, dimethyl ether was formed. Two-dimensional exchange NMR shows that dimethyl ether was in equilibrium with methanol at 250 degrees C. When 13C-methanol was flowed over HZSM-5 at temperatures > or = 200 degrees C, only dimethyl ether was observed. Between 160 degrees C and 200 degrees C, both methanol and dimethyl ether were observed. The flow results are significant in that they suggest that there is no equilibrium between methanol and dimethyl ether in the catalyst at high temperatures, and that surface methoxy groups do not exist on the catalyst at high temperatures. PMID:10811434

Carlson, L K; Isbester, P K; Munson, E J

2000-05-01

112

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 (CH3)2O, CH3OCD3, and (CD3)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

113

ESR evidence for the cation radicals of tetrahydrofurans and dimethyl ether produced in a. gamma. -irradiated frozen matrix of trichlorofluoromethane  

SciTech Connect

Cation radicals of tetrahydrofuran, methyltetrahydrofuran, cis- and trans-dimethyltetrahydrofuran, and dimethyl ether have been produced for the first time in ..gamma..-irradiated solid solutions of trichlorofluoromethane. The hyperfine splitting constants of axial protons adjacent to the ethereal oxygen are found to be as large as 90 to 100 G for the cyclic ethers. The spectral changes observed on temperature elevation toward the melting point of the freon matrix are accounted for in terms of ring puckering, and the activation energy is estimated as 1.65 kcal/mol. The cation radicals undergo ion-molecule reactions to produce neutral radicals of the parent ether molecules.

Kubodera, H. (Kyoto Univ., Japan); Shida, T.; Shimokoshi, K.

1981-09-03

114

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

115

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

116

Catalytic dehydration of methanol to dimethyl ether: Kinetic investigation and reactor simulation  

SciTech Connect

One-dimensional heterogeneous and pseudohomogeneous plug flow models were employed to model an adiabatic fixed bed reactor for the catalytic dehydration of methanol to dimethyl ether. Longitudinal temperature and methanol conversion profiles predicted by these models were compared to those experimentally measured in a pilot reactor. The reactor was packed with 3-mm [gamma]-Al[sub 2]O[sub 3] pellets and operated in a temperature range of 290--360 C and at a pressure of 2.1 bar. Intraparticle mass transport was found to be the rate-controlling step.

Bercic, G. (National Inst. of Chemistry, Ljubljana (Slovenia)); Levec, J. (Univ. of Ljubljana (Slovenia). Dept. of Chemical Engineering)

1993-11-01

117

Virial equation of state and ideal-gas heat capacities of pentafluoro-dimethyl ether  

Microsoft Academic Search

A virial equation of state is presented for vapor-phase pentafluoro-dimethyl ether (CF3?O?CF2H), a candidate alternative refrigerant known as E125. The equation of state was determined from density measurements performed\\u000a with a Burnett apparatus and from speed-of-sound measurements performed with an acoustical resonator. The speed-of-sound measurements\\u000a spanned the ranges 260?T?400 K and 0.05?P?1.0 MPa. The Burnett measurements covered the ranges 283?T?373

J. J. Hurly; J. W. Schmidt; K. A. Gillis

1997-01-01

118

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

119

Lifetimes and global warming potentials for dimethyl ether and for fluorinated ethers: CH 3 OCF 3 (E143a), CHF 2 OCHF 2 (E134), CHF 2 OCF 3 (E125)  

Microsoft Academic Search

Using recent kinetic data, two-dimensional (2-D) chemical-transport modeling of the atmospheric lifetimes of dimethyl ether and fluorinated ethers CH3OCF 3 (E143a), CHF2OCHF 2 (E134), and CHF2OCF3 (E125) shows that E134 and E125 have substantially larger lifetimes than previously estimated. Dimethyl ether has a short atmospheric lifetime of 5.1 days and a relatively insignificant radiative forcing leading to a relatively low

D. A. Good; J. S. Francisco; A. K. Jain; D. J. Wuebbles

1998-01-01

120

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

121

Synthesis of monodispersed poly(acrylonitrile) microspheres by dispersion polymerization in compressed liquid dimethyl ether  

Microsoft Academic Search

In this study, monodispersed spherical particles of poly(acrylonitrile) were synthesized via dispersion polymerization in\\u000a compressed liquid dimethyl ether using 2,2?-azobisisobutyronitrile (AIBN) as an initiator and five kinds of surfactants: PDMS-g-pyrrolidonecarboxylic acid (Monasil PCA™), PDMS modified surfactants, SS-5050K™, KF-6017™, poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-\\u000a heptadecafluorodecyl acrylate), and poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate). Using Monasil\\u000a PCA as a surfactant, uniform and spherical polymer particles were generated. The size of

Dong Woo Cho; Kyoung Shil Oh; Won Bae; Hwayong Kim; Youn-Woo Lee

2009-01-01

122

Performance of Dimethyl-ether Fuel Cells using Pt-Ru Catalyst  

NASA Astrophysics Data System (ADS)

Phenomena is presented whereby the performance of a dimethyl-ether fuel cell (DDFC) at 80°C is much lower when Pt-Ru catalyst is used on the anode than when Pt catalyst is used, in contrast to the higher performance achieved using Pt-Ru catalyst over Pt catalyst in direct methanol fuel cells (DMFC). The DDFC performance achieved using Pt-Ru catalyst increases with temperature and exceeds that using Pt catalyst at temperatures of over 100°C. After high temperature operation, the performance of DDFC using Pt-Ru catalyst at 80°C is improved. By supplying sufficient steam before operation, the performance of DDFC using Pt-Ru catalyst at 80°C is also found to improve. Before and during operation, more steam is needed for stable operation of the DDFC using Pt-Ru catalyst at 80°C than using Pt catalyst.

Haraguchi, Tadao; Tsutsumi, Yasuyuki; Takagi, Hiroyuki; Tamegai, Naoaki; Yamashita, Susumu

123

Wettability, optical properties and molecular structure of plasma polymerized diethylene glycol dimethyl ether  

NASA Astrophysics Data System (ADS)

Modern industry has frequently employed ethylene glycol ethers as monomers in plasma polymerization process to produce different types of coatings. In this work we used a stainless steel plasma reactor to grow thin polymeric films from low pressure RF excited plasma of diethylene glycol dimethyl ether. Plasmas were generated at 5W RF power in the range of 16 Pa to 60 Pa. The molecular structure of plasma polymerized films and their optical properties were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet-Visible Spectroscopy, respectively. The IR spectra show C-H stretching at 3000-2900 cm-1, C=O stretching at 1730-1650 cm-1, C-H bending at 1440-1380 cm-1, C-O and C-O-C stretching at 1200-1000 cm-1. The refraction index was around 1.5 and the optical gap calculated from absorption coefficient presented value near 3.8 eV. Water contact angle of the films ranged from 40° to 35° with corresponding surface energy from 66 to 73×10-7 J. Because of its favorable optical and hydrophilic characteristics these films can be used in ophthalmic industries as glass lenses coatings.

Azevedo, T. C. A. M.; Algatti, M. A.; Mota, R. P.; Y Honda, R.; Kayama, M. E.; Kostov, K. G.; Fernandes, R. S.; Cruz, N. C.; Rangel, E. C.

2009-05-01

124

Low NOx Combustion of DME by Means of Flue Gas Recirculation  

NASA Astrophysics Data System (ADS)

This study focuses on the fundamental characteristics of DME (Dimethyl Ether) combustion aiming at development of low-NOx combustion technology with flue gas recirculation, FGR. The flue gas is recirculated into the combustion chamber to reduce the oxygen concentration and to suppress the combustion gas temperature, so that NOx emission is significantly reduced. The fuel gas recirculation at high mixing ratio, however, may lead to unstable combustion of conventional fuels, methane or city gas. On the other hand, DME has very high potential of applicability for the flue gas recirculation even at high mixing ratio because of its high burning velocity and low ignition temperature. Combustion tests were conducted with laboratory-scale 11kW combustor. The maximum FGR ratio is 85% at the initial air ratio of 1.5 with preheated diluted air about 600K. The NOx emission reduced to 13ppm at 0%-O2, which corresponds to about 9% of NOx emission at FGR=0%. The stable combustion is sustained even in the low oxygen concentration by preheating diluted-air up to near the auto-ignition temperature of DME. Finally, the effect of the flue gas recirculation on the NOx and CO emission is discussed with reference to the industrial-scale water-tube boilers.

Matsumoto, Ryosuke; Ozawa, Mamoru; Terada, Shinya; Iio, Takenori

125

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

Microsoft Academic Search

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

1993-01-01

126

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

127

Thermophysical properties of 2,2,2-trifluoroethanol + tetraethylene glycol dimethyl ether  

SciTech Connect

Isothermal P,x data from 303.15 K to 423.15 K, liquid densities from 283.15 K to 423.15 K, and dynamic viscosities from 343.15 K to 393.15 K for the binary system 2,2,2-trifluoroethanol + tetraethylene glycol dimethyl ether were measured. The vapor-liquid equilibrium (VLE) data were measured. The vapor-liquid equilibrium (VLE) data were measured using a static apparatus. VLE data were correlated by the five-parameter NRTL equation, while density and kinematic viscosity data were correlated with temperature and liquid composition using empirical equations. The viscosity data used in the correlation cover the range of 293.15--393.15 K. VLE data indicate that this binary system exhibits large negative deviations from Raoult`s law. These mixtures present large exothermic excess molar enthalpies. The excess molar enthalpy calculated using the Gibbs-Helmholtz equation and the NRTL parameters was compared with experimental data existing in the literature.

Herraiz, J.; Olive, F.; Zhu, S.; Shen, S.; Coronas, A. [Univ. Rovira i Virgili, Tarragona (Spain). Dept. of Mechanical Engineering

1999-07-01

128

Thermodynamics of catalytic formation of dimethyl ether from methanol in acidic zeolites.  

PubMed

We present a theoretical study of the formation of the first intermediate, dimethyl ether, in the methanol to gasoline conversion within the framework of an ab initio molecular dynamics approach. The study is performed under conditions that closely resemble the reaction conditions in the zeolite catalyst including the full topology of the framework. The use of the method of thermodynamic integration allows us to extract the free-energy profile along the reaction coordinate. We find that the entropic contribution qualitatively alters the free-energy profile relative to the total energy profile. Different transition states are found from the internal and free energy profiles. The entropy contribution varies significantly along the reaction coordinate and is responsible for stabilizing the products and for lowering the energy barrier. The hugely inhomogeneous variation of the entropy can be understood in terms of elementary processes that take place during the chemical reaction. Our simulations provide new insights into the complex nature of this chemical reaction. PMID:11465443

Hytha, M; Stich, I; Gale, J D; Terakura, K; Payne, M C

2001-06-18

129

Explosion Limits of HCFC141b +Air and Dimethyl Ether +Air Mixtures under High Pressure  

NASA Astrophysics Data System (ADS)

According to the development of modern industry,many inflammable materials have been frequently used under high temperature and pressure condition,so information on the explosion limits of the materials under high pressures are required urgently. In this work,experimental studies were carried out to examine the explosion limits of HCFC141b +air and dimethyl ether +air mixtures. The explosion limits were determined using capacitance spark ignition apparatus consisting of an explosion chamber of 60mm in diameter. The temperature of gas mixture was set to 313k and pressures ranged from 0.1 to 0.5MPa. Lower explosion limits of these mixtures at atmospheric pressure were determined as 9.4and 3.8vol.% and upper explosion limits were 15.5 and 18.8vol.%, respectively. These inflammable regions spread slightly with increasing pressure. Usually,the minimum electric energy under atmospheric pressure required to ignite hydrocarbon +air mixtures is not more than 5mJ,while HCFC141b +air mixture shows weak inflammability and it seems to need at least 1J to ignite.

Kubota, Hironobu; Ichida, Takuya; Yoshikado, Masatomo; Makita, Tadashi

130

Control of Ignition and Combustion of Dimethyl Ether in Homogeneous Charge Compression Ignition Engine  

NASA Astrophysics Data System (ADS)

A homogeneous charge compression ignition (HCCI) engine is known to have high thermal efficiency and low nitrogen oxide emission. However, the control of ignition timing and its combustion period over a wide range of engine speeds and loads is one of the barriers to the realization of the engine. On the lean side of the equivalence ratio, control of ignition is difficult due to its long delay of ignition, and there is knocklike problem under high load. In both computations and experiments of HCCI engine operated on dimethyl ether, the operable range (the possible range of fuel input from just ignitable to knock-occurring state) shifted to the rich side with decreasing intake temperature and amount of mixing of carbon dioxide. The range of fuel input was reduced at low intake temperatures, because the hot flame onset angle advanced more quickly than it did at high intake temperatures. However, the mixing of CO2 caused the operable range to shift to the rich side while retaining the same range. The results of this study indicated the possibility of high-load operation or extension of the load range by exhaust gas recirculation.

Kim, Kyoung-Oh; Azetsu, Akihiko; Oikawa, Chikashi

131

Study of RF-excited Diethylene Glycol Dimethyl Ether Plasmas by Mass Spectrometry  

NASA Astrophysics Data System (ADS)

This paper deals with the study of the fragmentation process of diethylene glycol dimethyl ether (CH3O(CH2CH2O)2CH3) (diglyme here in) molecule in low pressure RF excited plasma discharges. The study was carried out using mass spectrometry. The results showed that for a fixed pressure, the increase of the RF power coupled to the plasma chamber from 1 to 35 W produced a plasma environment much more reactive which increases the population of the ionized species like CH2+ (15 amu), C2H4+ (28 amu), CH3O+ (31 amu), C2H4O+ (44 amu), CH3OCH2CH2+ (59 amu) and CH3OCH2CH2O+ (75 amu). This fact may be attributed to the increase of the electronic temperature that makes predominant the occurrence of inelastic processes that promotes molecular fragmentation. For a fixed value of RF power the increase of pressure from 50 mTorr to 100 mTorr produces the decreasing of the above mentioned chemical species due the lower electronic mean free path. These results suggest that if one wants to keep the monomer's functionality within the plasma deposited films resulting from such kind of discharges one must operate in low power conditions.

Algatti, M. A.; Mota, R. P.; Moreira Júnior, P. W. P.; Honda, R. Y.; Kayama, M. E.; Kostov, K. G.

2012-12-01

132

Facile electrosynthesis of novel free-standing electroactive poly((S)-(?)-1,1?-bi-2-naphthol dimethyl ether) films with enhanced main chain axial chirality  

Microsoft Academic Search

Direct anodic oxidation of (S)-(?)-1,1?-bi-2-naphthol dimethyl ether (BNME) in CH2Cl2\\/CHCl3 containing boron trifluoride diethyl etherate (BFEE) as the supporting electrolyte led to facile electrodeposition of high-quality free-standing poly((S)-(?)-1,1?-bi-2-naphthol dimethyl ether) (PBNME) film on stainless steel (SS)\\/indium tin oxide (ITO) electrodes. As-formed PBNME films showed good electroactivity and redox stability in CH2Cl2–BFEE, BFEE, and even in concentrated sulfuric acid. Both doped

Baoyang Lu; Jingkun Xu; Yuzhen Li; Congcong Liu; Ruirui Yue; Xiaoxia Sun

2010-01-01

133

Spectroscopy of a Major Complex Organic Molecule: Mono-Deuterated Dimethyl Ether  

NASA Astrophysics Data System (ADS)

Dimethyl ether is one of the most abundant molecule in star-forming regions. Like other complex organic molecules, its formation process is not yet clearly established. The study of deuteration may provide crucial hints. The mono-deuterated species (CH_2DOCH3) is still a relatively light molecule; its spectrum is the most intense in the THz domain even at ISM temperatures (100--150 K). Therefore, it is is necessary to measure and assign its transitions in this range in order to be able to compute accurate predictions which should allow us to detect it with ALMA, expected to be a powerful tool to observe such isotopic species. In this context, spectra between 50 and 950 GHz were recorded in Lille with a solid-state submillimeter-wave spectrometer. The starting point of the analysis was the centimeter-wave measurements carried out in 2003 for almost all isotopic species. Results concerning the symmetric conformer of the mono-deuterated species will be presented in the paper. The fits performed with the ERHAM code will be discussed. Theoretical development are in progress in order to treat the case of the asymmetric conformer. This work is supported by the CNES and the Action sur Projets de l'INSU, PCMI. This work is also funded by the ANR-08-BLAN-0054 and ANR-08-BLAN-0225 contracts. [1]Ceccarelli, Caselli, Herbst, et al., (eds.), University of Arizona Press, Tucson, 951 (2007) 47 [2]Niide et al., J. Mol.Spectrosc. 220 (2003) 65 [3]Groner, J. Chem. Phys. 107 (1997) 4483

Richard, C.; Margulès, L.; Motiyenko, R. A.; Groner, P.; Coudert, L. H.; Guillemin, J.-C.

2012-06-01

134

Effect of the hybrid catalysts preparation method upon direct synthesis of dimethyl ether from synthesis gas  

Microsoft Academic Search

Direct synthesis of DME from synthesis gas attains more attention recently due to higher conversion and lower cost in comparison to dehydration of the methanol. In this work Synthesis gas To Dimethylether (STD) conversion was examined on various hybrid catalysts prepared by seven different methods. These catalysts had the same general form as CuO\\/ZnO\\/Al2O3 with theoretical weight ratio 31\\/16\\/53, respectively.

G. R. Moradi; S. Nosrati; F. Yaripor

2007-01-01

135

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.

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

2013-01-01

136

Intrinsic kinetics of one-step dimethyl ether synthesis from hydrogen-rich synthesis gas over bi-functional catalyst  

Microsoft Academic Search

The reaction kinetics of the dimethyl ether synthesis from hydrogen-rich synthesis gas over bi-functional catalyst was investigated\\u000a using an isothermal integral reactor at 220–260°C temperature, 3–7 MPa pressure, and 1,000–2,500 mL\\/g·h space velocity. The\\u000a H2\\/CO ratio of the synthetic gas was chosen between 3 : 1 and 6 : 1. The bi-functional catalyst was prepared by physically mixing\\u000a commercial CuO\\/ZnO\\/Al2O3

Chengyuan Cheng; Haitao Zhang; Weiyong Ying; Dingye Fang

2011-01-01

137

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

138

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

139

Ab initio calculations for the spectral analysis of dimethyl ether (CH_3OCH_3) and their isotopologues  

NASA Astrophysics Data System (ADS)

Dimethyl ether is a complex interstellar molecule with two internal rotors, which has a high abundance in the star-forming regions. This point, jointed with the recent development of the last-generation observatories operating at the sub-mm and mm wavelengths, has motivated a new laboratory spectral recording in this frequency range. In spite of that, the rotational spectra was only analysed in depth within its vibrational ground state and a new spectral analysis within the fundamental torsional states is in progress. These analysis were carried out with ERHAM, a global model that takes into account the large amplitude motions owing to the two equivalent internal CH3 tops. Nevertheless, their torsional modes in principle interact with the bending COC mode and an appropiate torsional-bending description would be needed in order to analyse the rotational spectra within higher excited states. In this work, a new analysis of the COC bending and the CH3 torsional degrees of freedom has been carried out by means of ab initio calculations. A new and more accurate three-dimensional Potential Energy Surface (PES), is obtained using the CCSD(T) level of theory. This approach has also been applied to other isotopologues of interest, as 13C-dimethyl ether and the monodeuterated species. The purpose of this study is to help in the assignment of new spectral lines of these species and hence to contribute in the spectral cleaning of the astronomical observations to the interstellar medium.

Senent, M. L.; Villa, M.; Dominguez-Gomez, R.; Alvarez-Bajo, O.; Carvajal, M.

2011-05-01

140

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

2007-09-10

141

Improvement in the catalyst activity for direct synthesis of dimethyl ether from synthesis gas through enhancing the dispersion of CuO\\/ZnO\\/?-Al 2O 3 in hybrid catalysts  

Microsoft Academic Search

Based on the knowledge of the mechanisms of methanol synthesis and methanol dehydration, it was predicted that if the dispersion of CuO\\/ZnO\\/?-Al2O3 in hybrid catalysts for direct synthesis of dimethyl ether from synthesis gas was enhanced, the formation rate of dimethyl ether would be increased. In order to justify the prediction, five preparation methods, including two mechanical mixing ones and

J.-L. Li; X.-G. Zhang; T. Inui

1996-01-01

142

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

143

HIGH-RESOLUTION EXPANDED VERY LARGE ARRAY IMAGE OF DIMETHYL ETHER (CH{sub 3}){sub 2}O IN ORION-KL  

SciTech Connect

We report the first subarcsecond (0.''65 x 0.''51) image of the dimethyl ether molecule, (CH{sub 3}){sub 2}O, toward the Orion Kleinmann-Low nebula. The observations were carried at 43.4 GHz with the Expanded Very Large Array (EVLA). The distribution of the lower energy transition 6{sub 1,5}-6{sub 0,6}, EE (E {sub u} = 21 K) mapped in this study is in excellent agreement with the published dimethyl ether emission maps imaged with a lower resolution. The main emission peaks are observed toward the Compact Ridge and Hot Core southwest components, at the northern parts of the Compact Ridge and in an intermediate position between the Compact Ridge and the Hot Core. A notable result is that the distribution of dimethyl ether is very similar to that of another important larger O-bearing species, the methyl formate (HCOOCH{sub 3}), imaged at a lower resolution. Our study shows that higher spectral resolution (WIDAR correlator) and increased spectral coverage provided by the EVLA offer new possibilities for imaging complex molecular species. The sensitivity improvement and the other EVLA improvements make this instrument well suited for high sensitivity, high angular resolution, and molecular line imaging.

Favre, C. [Department of Physics and Astronomy, University of Arhus, Ny Munkegade 120, DK-8000 Arhus C (Denmark); Wootten, H. A.; Remijan, A. J. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Brouillet, N.; Despois, D.; Baudry, A. [Universite de Bordeaux, OASU, 2 rue de l'Observatoire, BP 89, 33271 Floirac Cedex (France); Wilson, T. L., E-mail: favre@phys.au.dk, E-mail: brouillet@obs.u-bordeaux1.fr, E-mail: despois@obs.u-bordeaux1.fr, E-mail: baudry@obs.u-bordeaux1.fr, E-mail: awootten@nrao.edu, E-mail: aremijan@nrao.edu, E-mail: tom.wilson@nrl.navy.mil [Naval Research Laboratory, Code 7210, Washington, DC 20375 (United States)

2011-09-20

144

Electrochemical Investigation of Li–Al Anodes in Oligo(ethylene glycol) Dimethyl Ether/LiPF6  

SciTech Connect

1 M LiPF{sub 6} dissolved in oligo(ethylene glycol) dimethyl ether with a molecular weight 500 g mol{sup -1} was investigated as a new electrolyte (OEGDME500, 1 M LiPF{sub 6}) for metal deposition and battery applications. At 25 C a conductivity of 0.48 x 10{sup -3} S cm{sup -1} was obtained and at 85 C, 3.78 x 10{sup -3} S cm{sup -1}. The apparent activation barrier for ionic transport was evaluated to be 30.7 kJ mol{sup -1}. OEGDME500, 1 M LiPF{sub 6} allows operating temperature above 100 C with very attractive conductivity. The electrolyte shows excellent performance at negative and positive potentials. With this investigation, we report experimental results obtained with aluminum electrodes using this electrolyte. At low current densities lithium ion reduction and re-oxidation can be achieved on aluminum electrodes at potentials about 280 mV more positive than on lithium electrodes. In situ X-ray diffraction measurements collected during electrochemical lithium deposition on aluminum electrodes show that the shift to positive potentials is due to the negative Gibbs free energy change of the Li-Al alloy formation reaction.

Zhou, Y.N.; Yang, X.; Wang, X.J.; Lee, H.S.; Nam, K.W.; Haas, O.

2010-11-01

145

Theoretical study of the O···Cl interaction in fluorinated dimethyl ethers complexed with a Cl atom: is it through a two-center-three-electron bond?  

PubMed

Theoretical investigations are carried out on the interaction between fluorinated dimethyl ethers (FDME, nF = 0-4) and the Cl atom. Short intermolecular O···Cl distances between 2.401 and 2.938 Å reveal the formation of a new class of complexes. The interaction energies calculated with the G2(MP2) method range between -9.1 (nF = 4) and -26.0 (nF = 0) kJ/mol. The charge transfer occurring from the ethers to atomic Cl is moderate and ranges between 0.012 e (nF = 4) to 0.188 e (nF = 0). The binding energies are linearly related to the proton affinity, to the charge transfer (CT) occurring in the molecular system and inversely proportional to the ionization potential and electron affinity (IP-EA) values. The CT and spin density data indicate substantial two-center-three-electron O···Cl interaction in CH3OCH3···Cl and CH3OCH2F···Cl systems, whereas for highly fluorinated ethers the interaction is predominantly electrostatic in nature. The formation of the complex results in a contraction of the CH bonds, especially in the gauche position. The blue shifts of the C-H stretching vibrations calculated in the partially deuterated isotopomers range between 2 and 54 cm(-1) and are correlated to the variation of the CH distances. PMID:23876015

Zeegers-Huyskens, Therese; Lily, Makroni; Sutradhar, Dipankar; Chandra, Asit K

2013-08-02

146

Synthesis and properties of fluorinated poly(ether ketone imide)s based on a new unsymmetrical and concoplanar diamine: 3,5Dimethyl4-(4-amino-2-trifluoromethylphenoxy)-4?-aminobenzophenone  

Microsoft Academic Search

A new unsymmetrical and concoplanar aromatic diamine monomer containing trifluoromethyl and dimethyl groups, 3,5-dimethyl-4-(4-amino-2-trifluoromethylphenoxy)-4?-aminobenzophenone (3), was synthesized in a three-step reaction using 2,6-dimethylphenol and 4-nitrobenzoyl chloride as starting materials. A series of fluorinated poly(ether ketone imide)s (PEKIs) (5a–d) were prepared from diamine 3 with four aromatic dianhydrides via a one-step high-temperature polycondensation procedure. The obtained PEKIs were readily soluble in

Chen-Yi Wang; Guang Li; Jian-Ming Jiang

2009-01-01

147

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 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)].

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

2011-01-01

148

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

2011-07-09

149

Methanol and 2-methyl-1-propanol (isobutanol) coupling to ethers and dehydration over Nafion H: Selectivity, kinetics, and mechanism  

SciTech Connect

The dehydration of a mixture of methanol and isobutanol has been studied over the sulfonic acid Nafion H catalyst. Dehydration products consisted of dimethyl ether (DME), di-isobutyl ether (DIBE), methyl-isobutyl ether (MIBE), butenes, octenes, and traces of methyl-tertiarybutyl ether (MTBE). At low temperatures and high alcohol pressures (P [ge] 150 kPa), the dehydration product slate was dominated by ether formation with selectivity within the ethers significantly in favor of the mixed ether, MIBE. The rates of ether and butene formation as a function of alcohol pressure could be described by Langmuir-Hinshelwood kinetics in which competitive adsorption of the two alcohols on the surface -SO[sub 3]H sites was the dominant feature. The kinetics of isobutanol dehydration to isobutene were consistent with a dual-site mechanism involving the cooperative action of a free surface -SO[sub 3]H site and an adjacent adsorbed alcohol molecule. Dehydration to ethers was consistent with the reaction of two adsorbed alcohols, also by a dual-site mechanism. As a consequence, dehydration to symmetric ethers showed saturation-type kinetics as a function of alcohol pressure, while the rate of isobutene formation went through a distinct maximum. Due to the competitive adsorption of methanol and isobutanol, the mixed ether MIBE was formed at a maximum rate with an optimum ratio of partial pressures of the two alcohols. The high selectivity to MIBE was explained by stronger adsorption of isobutanol on the catalyst surface as compared to methanol. The absence of MTBE and the predominance of products such as MIBE and 2,5-dimethylhexene suggests that dehydration to give free carbenium ions that subsequently rearrange to the more stable tertiary intermediate was not occurring. It was proposed that the alcohols react with the -SO[sub 3]H groups to give oxonium ions or esters. These intermediates couple to give the product ethers or octenes. 24 refs., 13 figs., 1 tab.

Nunan, J.G.; Klier, K.; Herman, R.G. (Lehigh Univ., Bethlehem, PA (United States))

1993-02-01

150

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  

Microsoft Academic Search

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

1993-01-01

151

Electrochemical Investigation of Al–Li/LixFePO4 Cells in Oligo(ethylene glycol) Dimethyl Ether/LiPF6  

SciTech Connect

1 M LiPF{sub 6} dissolved in oligo(ethylene glycol) dimethyl ether with a molecular weight, 500 g mol{sup -1} (OEGDME500, 1 M LiPF{sub 6}), was investigated as an electrolyte in experimental Al-Li/LiFePO{sub 4} cells. More than 60 cycles were achieved using this electrolyte in a Li-ion cell with an Al-Li alloy as an anode sandwiched between two Li x FePO{sub 4} electrodes (cathodes). Charging efficiencies of 96-100% and energy efficiencies of 86-89% were maintained during 60 cycles at low current densities. A theoretical investigation revealed that the specific energy can be increased up to 15% if conventional LiC{sub 6} anodes are replaced by Al-Li alloy electrodes. The specific energy and the energy density were calculated as a function of the active mass per electrode surface (charge density). The results reveal that for a charge density of 4 mAh cm{sup -2} about 160 mWh g{sup -1} can be reached with Al-Li/LiFePO{sub 4} batteries. Power limiting diffusion processes are discussed, and the power capability of Al-Li/LiFePO{sub 4} cells was experimentally evaluated using conventional electrolytes.

Wang, X.J.; Zhou, Y.N.; Lee, H.S.; Nam, K.W.; Yang, X.Q.; Haas, O.

2011-02-01

152

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

153

Enhancement of dopamine sensing by layer-by-layer assembly of PVI-dmeOs and Nafion on carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this study, carbon nanotubes (CNTs) were modified to further improve their performance in electrochemical sensing of dopamine (DA) levels. After a redox polymer, poly(vinylimidazole) complexed with Os(4, 4'-dimethyl- 2, 2-bipyridine)2Cl (termed PVI-dmeOs) was electrodeposited on multi-wall CNTs (MWCNTs), Nafion and PVI-dmeOs films were successfully layer-by-layer (LBL) assembled on the hydrophilic surface of the as-prepared PVI-dmeOs/CNTs nanocomposites through electrostatic interactions. The LBL assembly was proved by scanning electron microscopy (SEM), electrochemistry and UV-vis spectroscopy measurements. LBL assembly of Nafion/PVI-dmeOs films on CNTs significantly enhanced their linear sweep voltammetry (LSV) response sensitivity to DA, with a maximum enhancement for three Nafion/PVI-dmeOs film-modified MWCNTs. The LSV peak current density of (Nafion/PV I-dmeOs)3/CNT electrodes in response to 10 and 50 µM DA solutions was about 7.3 and 3.9 times those for bare CNTs. At the (Nafion/PV I-dmeOs)3/CNT electrodes, the limit of detection (LOD) (signal-to-noise ratio: 3) was 0.05 µM DA, the linear range was 0.1-10 µM DA (with a linear regression coefficient of 0.97) and the DA-sensing sensitivity was 8.15 µA cm - 2 µM - 1. The newly fabricated (Nafion/PV I-dmeOs)3/CNT electrodes may be developed as an ideal biosensor for direct and in situ measurement of DA levels.

Cui, Hui-Fang; Cui, Yu-Han; Sun, Yu-Long; Zhang, Kuan; Zhang, Wei-De

2010-05-01

154

Your Medicare Coverage: Durable Medical Equipment (DME) Coverage  

MedlinePLUS

... covered? Search Medicare.gov for covered items Durable medical equipment (DME) coverage How often is it covered? Medicare Part B (Medical Insurance) covers durable medical equipment (DME) that your ...

155

Study of liquid–liquid and liquid–solid equilibria of the ternary aqueous system containing poly ethylene glycol dimethyl ether 2000 and tri-potassium phosphate at different temperatures: Experiment and correlation  

Microsoft Academic Search

The liquid–liquid and liquid–solid equilibrium for the poly ethylene glycol di-methyl ether 2000 (PEGDME2000)+K3PO4+H2O system has been determined experimentally at T=(298.15,303.15,308.15 and 318.15)K. The effect of temperature on the binodal curves and tie-lines for the investigated Aqueous Two-Phase System (ATPS) have also been studied. The reliability of some frequently used equations for fitting of obtained binodal data and a new empirical equation for

Mohammed Taghi Zafarani-Moattar; Ebrahim Nemati-Kande

2010-01-01

156

Theoretical investigation of the interaction between fluorinated dimethyl ethers (nF = 1-5) and water: role of the acidity and basicity on the competition between OH...O and CH...O hydrogen bonds.  

PubMed

Theoretical calculations have been carried out using ab initio MP2 and B3LYP density functional methods to investigate the interaction between fluorinated dimethyl ethers (nF = 1-5) and water. Depending on the number of F atoms implanted on the dimethyl ethers, linear structures stabilized by intermolecular O(w)H(w)...O or CH...O(w) hydrogen bonds or closed structures involving both hydrogen bonds are formed. Binding energies of the hydrogen-bonded complexes range between 4 and 12 kJ mol(-1). Blue shifts of the CH stretching vibrations are predicted even in the absence of a direct CH...O interaction. The red shifts of the OH stretching vibrations of water in the open and closed structures are analyzed as well. The natural bond orbital analysis includes the sigma*(O(w)H(w)) and sigma*(CH) occupation, the hybridization of the C atom, the atomic charges, and the intra- and intermolecular hyperconjugation energies. These parameters are discussed as a function of the proton affinity (PA) of the O atom and the deprotonation enthalpy (DPE) of the CH bonds of the fluorinated ethers calculated in a previous work. (16) Our results show that the effective PA in determining the intermolecular O --> sigma*(O(w)H(w)) hyperconjugation energies decreases with increasing acidity of the CH bond. In turn, the effective acidity of the CH bond in determining the intermolecular O(w) --> sigma*(CH) hyperconjugation energies decreases with increasing basicity of the O atom. PMID:19422184

Parveen, Salma; Chandra, Asit K; Zeegers-Huyskens, Thérèse

2009-05-28

157

Oxidation of dimethyl-ether and ethylene in the atmosphere and combustion environment and thermodynamic studies on hydrofluorocarbons usingab initio calculation methods  

NASA Astrophysics Data System (ADS)

Reaction pathways and kinetics are analyzed on CH3OC.H2 unimolecular decay and on the complete CH3OC.H2 + O2 reaction system using thermodynamic properties DHdegf 298,Sdeg 298, and Cp(T) 300 <= T/K <= 1500) derived by two ab initio calculation methods, CBS-q and G2. These are used to determine thermodynamic properties of reactants, intermediate radicals and transition state (TS) compounds. Quantum Rice-Ramsperger-Kassel (QRRK) analysis is used to calculate energy dependent rate constants, k(E), and master equation is used to account for collisional stabilization. Comparison of calculated fall-off with experiment indicates that the CBS-q and G2 calculated Ea,rxn for the rate controlling transition state (?-scission reaction to CH 2O + C.H2OOH) needs to be lowered by factor of 3.3 kcal/mol and 4.0 kcal/mol respectively in order to match the data of Sehested et al. Experimental results on dimethyl-ether pyrolysis and oxidation reaction systems are compared with a detailed reaction mechanism model. The computer code CHEMKIN II is used for numerical integration. Overall agreement of the model data with experimental data is very good. Reaction pathways are analyzed and kinetics are determined on formation and reactions of the adduct resulting from OH addition to ethylene using the above ab initio methods. Hydrogen atom tunneling is included by use of Eckart formalism. Rate constants are compared with experimentally determined product branching ratios (C.H2CH 2OH stabilization: CH2O + CH3: CH3CHO + H). ab initio calculations are performed to estimate thermodynamic properties of nine fluorinated ethane compounds (fluoroethane to hexafluoroethane), eight fluoropropane (1-fluoropropane, 1,1- and 1,2- difluoropropane, 1,1,1- and 1,1,2-trifluoropropane, 1,1,1,2- and 1,1,2,2-tetrafluoropropane and 1,1,1,2,2- pentafluoropropane), and 2-fluoro,2-methylpropane. Standard entropies and heat capacities are calculated using the rigid-rotor-harmonic-oscillator approximation with direct integration over energy levels of the intramolecular rotation potential energy curve. Enthalpies of formation are estimated using G2MP2 total energies and isodesmic reactions. Thermodynamic properties for fluorinated carbon groups C/C/F/H2, C/C/F2/H, C/C/F3, C/C2/F/H, C/C2/F2 and C/C3/F for fluorinated alkane compounds, CD/F/H and CD/F2 for fluorinated alkene compounds and CT/F for fluorinated alkyne compounds are estimated. Fluorine-fluorine interaction terms F/F, 2F/F, 3F/F, 2F/2F, 3F/2F and 3F/3F for alkane compounds, F//F, 2F//F and 2F/2F for alkene compounds, and F///F for alkyne compound are also estimated.

Yamada, Takahiro

1999-08-01

158

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

159

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

160

Theoretical study of the cooperativity in substituted dimethyl ethers complexed with two water molecules. Red or blue shifts of the ?(CH) vibrations?  

NASA Astrophysics Data System (ADS)

The cooperative interactions in CH3OCH3, CH3OCH2F, CH3OCHF2, CH2FOCHF2 and CHF2OCHF2 complexed with two H2O molecules are investigated using the B3LYP method with the 6-311++G(d,p) level. The calculations include the optimized geometries, the cooperative energies along with a natural bond orbital (NBO analysis). Cyclic complexes characterized by OwHw…O and CH…Ow hydrogen bonds are formed. The pairwise or two body interaction energies are computed. The results show that the OwHw…O interaction energies increase with the proton affinity of the O atom of the ethers and that the CH…Ow interaction energies increase with increasing acidity of the CH bond. This is in agreement with the intermolecular distances. The cooperative energy represents 15-20% of the total energy. When nF = 2-4, blue shifts are predicted for the ?(CH) vibration for the 1-1 complexes but red shifts are predicted for the 1-2 complexes. The variation of the CH distances is explained by a competition between the variation of the intramolecular hyperconjugation energies and the intermolecular hyperconjugation energies. The charge transfer between the ether and water molecules is analyzed. When the negative charge on one H2O molecule decreases, the positive charge on the other H2O molecule increases, indicating a nice reciprocal effect.

Chandra, Asit K.; Zeegers-Huyskens, Thérèse

2013-01-01

161

Emissions from Ethers and Organic Carbonate Fuel Additives: A Review  

Microsoft Academic Search

This paper is a review of the available literature on the main features of 11 of the most widely adopted oxygenated additives\\u000a to base gasoline and diesel, focusing particularly on the emissions from the oxygenates considered as additives. The oxygenated\\u000a additives studied are methyl tert-butyl ether, ethyl tertiary butyl ether, tert-amyl ethyl ether, tertiary amyl methyl ether, isopropyl ether, dimethyl

Alessia Arteconi; Alessandro Mazzarini; Giovanni Di Nicola

162

'3Dme--a look inside' creative studio.  

PubMed

3Dme are creative 3D digital story-tellers with a passion for making complex health and medical information comprehensible. They have an enviable ability to understand a broad range of health and medical topics and present them in an accurate and visually engaging manner. '3Dme - A Look Inside' is a privately owned 3D visualisation and multimedia company established by Luke and Sonya Brannelly in 2006. 3Dme are passionate about creating beautiful, scientifically accurate, relevant, high definition, full 3D visualisation presentations to take a look inside the human body to communicate a health or medical education message via engaging, creative digital story-telling. 3Dme's primary objective is to 'improve global health and education outcomes'. Winning a number of local and international awards for their work, they are well on their way to achieving this. 3Dme's vision is simply to use their scientific and artistic skills along with the reach of the internet and digital technology, to captivate, engage and inspire everyone from primary school students, teachers and parents, through to university undergraduates, academics and medical specialists, to improve their understanding of complex health and medical topics. The digital output of their 3D presentations is suitable for a variety of delivery platforms and includes e-learning modules, blended learning, interactive learning modules and Apps. 3Dme has made, and continues to make, significant investments in technology based hardware and software, boasting one of the largest in-house, fully equipped animation render farms in Queensland, Australia. PMID:22397485

Brannelly, Sonya

2012-03-01

163

14 CFR 171.321 - DME and marker beacon performance requirements.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Microwave Landing System (MLS) § 171.321 DME and marker beacon performance requirements. (a) The DME...

2013-01-01

164

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

165

DME synthesis and cyclohexane dehydrogenation reaction in an optimized thermally coupled reactor  

Microsoft Academic Search

This paper presents a study on optimization of DME synthesis and cyclohexane dehydrogenation in a thermally coupled reactor. A steady-state heterogeneous model has been performed in order to evaluate the optimal operating conditions and enhancement of DME and benzene production. In this work, the catalytic methanol dehydration to DME is coupled with the catalytic dehydrogenation of cyclohexane to benzene in

M. H. Khademi; M. Farsi; M. R. Rahimpour; A. Jahanmiri

2011-01-01

166

Dimethyl Sulfoxide  

PubMed Central

Dimethyl sulfoxide is a colorless liquid derived as a by-product from wood pulp in the production of paper. This colorless liquid found immediate application as a polar, aprotic solvent miscible with water and able to dissolve an enormous catalog of polar and nonpolar small molecules. It is presently scarcely used in dermatology, but given its useful properties as a penetration-enhancing solvent excipient and active anti-inflammatory pharmaceutical agent, dimethyl sulfoxide has the potential to be used in a much broader capacity. The authors review the history, chemistry, and clinical utility of dimethyl sulfoxide as it pertains to dermatology.

Capriotti, Joseph A.

2012-01-01

167

Operation of Multidrift Tubes with Dimethyl Ether.  

National Technical Information Service (NTIS)

We have built several 80 cm long multiwire drift tubes, each with 70 independent drift cells constituted by individual anodes centered in a hexagonal cell, 1.45 mm in radius, defined by six cathode wires. A thin hexagonal carbon-fiber envelope, 30 mm in d...

R. Bouclier G. Charpak J. Garabatos B. Guerard J. C. Santiard

1987-01-01

168

Analysis of protein dynamics using local-DME calculations.  

PubMed

Flexibility and dynamics of protein structures are reflected in the B-factors and order parameters obtained experimentally with X-ray crystallography and Nuclear Magnetic Resonance (NMR). Methods such as Normal Mode Analysis (NMA) and Elastic Network Models (ENM) can be used to predict the fluctuations of protein structures for either atomic level or coarse-grained structures. Here, we introduce the Local-Distance Matrix Error (DME), an efficient and simple analytic method to study the fluctuations of protein structures, especially for the ensembles of NMR-determined protein structures. Comparisons with the fluctuations obtained by experiments and other by computations show strong correlations. PMID:21576073

Wu, Di; Smith, Stephen; Mahan, Hannah; Jernigan, Robert L

2011-01-01

169

Intermolecular Interaction Between CO or CO{_2} and Ether or Thioether or Propylene Oxide in a Complex, Investigated by Fourier Transform Microwave Spectroscopy and AB Initio Calculations  

NASA Astrophysics Data System (ADS)

In sharp contrast with the hydrogen bond, which has beenwell established to be one of the strongest interactions between two atomic and/or molecular species, weak interactions between two closed-shell molecules have not been understood in detail. We have thus carried out a systematic study on complexes shown in the title; examples include the CO-ethylene oxide (EO), CO-ethylene sulfide (ES), CO-dimethyl ether (DME), CO-dimehtyl sulfide (DMS), CO{_2}-EO, CO{_2}-ES, CO{_2}-DME, and CO{_2}-propylene oxide (PO) complexes. From their Fourier transform microwave spectra, we determined the {RS} structure, the force constant of the van der Waals stretching mode, and the dissociation energy by analyzing the observed rotational and centrifugal distortion constants. We have also carried out ab initio molecular orbital calculations at the level of MP2 with basis sets 6-311++G(d, p) and aug-cc-pVDZ using the Gaussian 09 package. In most cases, the MP2/6-311++G(d, p) calculations yield rotational constants in better agreement with the experimental values, than the other basis set, in other word, the molecular structures calculated using this basis set are close to those experimentally found for the ground state. The estimated bond dissociation energies including the zero-point vibrational energy corrections ?ZPV and the basis set superposition errors (BSSE) calculated with the counterpoise correction (CP) are in good agreement with the observed binding energies {E_B}. We have applied an NBO analysis to the complexes to calculate the stabilization energy CT (= ?E{??*}), which we found are closely correlated with the binding energies {E_B}. We have thus achieved a consistent overview on the intermolecular interaction in the complexes under consideration.

Kawashima, Yoshiyuki; Orita, Yukari; Sato, Akinori; Hirota, Eizi

2011-06-01

170

Adamantyldimethylsilyl Ethers.  

National Technical Information Service (NTIS)

Adamantyldimethylsilyl ethers, prepared by reaction of the chloride with alcohols in DMF/imidazole or by Ph3P3RhC catalyzed reaction of adamantyldimethylsilane with alcohols, are comparable in stability to t-butyldimethylsilyl ethers. Their hydrolysis yie...

E. Wanek Y. M. Pai W. P. Weber

1985-01-01

171

Synthesis of higher carbon ethers from olefins and alcohols  

Microsoft Academic Search

Higher carbon ether compounds (HME; hexyl methyl ether and OME; octyl methyl ether) are produced from olefins (C6 olefins: 23DM1B; 2,3-dimethyl-1-butene and 23DM2B; 2,3-dimethyl-2-butene and C8 olefins: 244TM1P; 2,4,4-trimethyl-1-pentene and 244TM2P; 2,4,4-trimethyl-2-pentene) and methanol in the presence of commercially available Amberlyst 15 ion exchange catalyst. Stainless steel batch reactors are used and the experiments are conducted from 333 to 373

Jeff Snelling; Christine W. Curtis

2003-01-01

172

Ether options  

SciTech Connect

The authors present an assessment of three ether options. Of all the ethers, MTBE is the most versatile and effective in achieving maximum flexibility for the refiner. For oxygenate mandates, MTBE requires the least amount of ether to achieve the required oxygen level in the gasoline. ETBE production can be economical in the U.S. if ethanol's 60 cents per gallon federal tax subsidy is applied to the ethanol feedstock. However, this would cause a refinery operation to be dependent on a tax subsidy that is due to expire at the end of 1991, at which time the unit would be uneconomical. Of all the ethers, TAME can probably provide the most environmental benefit. It reduces tailpipe emissions and converts some very volatile and highly reactive C/sub 5/ olefins in the gasoline pool into a very low RVP and clean burning ether. This RVP reduction will also provide the refiner with added flexibility in meeting the future RVP control regulations.

Miller, D.J.; Piel, W.J. (ARCO Chemical Co., Newtown Square, PA (US))

1989-01-01

173

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

174

Lithium cycling efficiency of ternary solvent electrolytes with ethylene carbonate—dimethyl carbonate mixture  

Microsoft Academic Search

Lithium cycling efficiency for ternary solvent (mol ratio 1:1:1) electrolytes of different molar conductivities containing LiPF6 and LiClO4 with ethylene carbonate (EC)—dimethyl carbonate (DMC) binary mixture of constant mixed ratio (mol ratio 1:1) was investigated by galvanostatic experiments at 25 °C. The solvents applied to the EC-DMC mixture are 1,2-dimethoxyethane (DME), 2-methyltetrahydrofuran (2-MeTHF) and ethylmethyl carbonate (EMC). The molar conductivity

Yukio Sasaki; Mamoru Hosoya; Minoru Handa

1997-01-01

175

Performance of an Ar-DME imaging photoelectric polarimeter  

NASA Astrophysics Data System (ADS)

The possibility to perform polarimetry in the soft X-ray energy band (2-10 keV) with the Gas Pixel Detector, filled with low Z mixtures, has been widely explored so far. The possibility to extend the technique to higher energies, in combination with multilayer optics, has been also hypothesized in the past, on the basis of simulations. Here we present a recent development to perform imaging polarimetry between 6 and 35 keV, employing a new design for the GPD, filled with a Ar-DME gas mixture at high pressure. In order to improve the efficiency by increasing the absorption gap, while preserving a good parallel electric field, we developed a new configuration characterized by a wider gas cell and a wider GEM. The uniform electric field allows to maintain high polarimetric capabilities without any decrease of spectroscopic and imaging properties. We present the first measurements of this prototype showing that it is now possible to perform imaging and spectro-polarimetry of hard X-ray sources.

Fabiani, S.; Bellazzini, R.; Berrilli, F.; Brez, A.; Costa, E.; Minuti, M.; Muleri, F.; Pinchera, M.; Rubini, A.; Soffitta, P.; Spandre, G.

2012-09-01

176

Imprinting of the MEA Polycomb gene is controlled by antagonism between MET1 methyltransferase and DME glycosylase.  

PubMed

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 maintains cytosine methylation. Seeds with maternal dme and met1 alleles survive, indicating that suppression occurs in the female gametophyte. Suppression requires a maternal wild-type MEA allele, suggesting that MET1 functions upstream of, or at, MEA. DME activates whereas MET1 suppresses maternal MEA::GFP allele expression in the central cell. MET1 is required for DNA methylation of three regions in the MEA promoter in seeds. Our data suggest that imprinting is controlled in the female gametophyte by antagonism between the two DNA-modifying enzymes, MET1 methyltransferase and DME DNA glycosylase. PMID:14667411

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

2003-12-01

177

Five- and Six-Coordinate 2-Methyl-2-propanethiolato Complexes of Zirconium(IV): Synthesis and Structures of [Li(DME)(3)][Zr(SCMe(3))(5)] and [(THF)Li](2)Zr(SCMe(3))(6).  

PubMed

Five-coordinate and six-coordinate 2-methyl-2-propanethiolato complexes of zirconium, [Li(DME)(3)][Zr(SCMe(3))(5)] (1) and [(THF)Li](2)Zr(SCMe(3))(6) (2), were obtained from the ZrCl(4)/LiSCMe(3) reaction system. The control of the Zr coordination number, by the ether ligands, THF or DME, bound to Li, is demonstrated by the conversion of 2 into 1 upon dissolution in DME. 1 and 2 were crystallographically characterized. The structures are extensively disordered. Crystal data follow: 1, hexagonal P6(3)/m, a = b = 12.496(3) Å, c = 17.561(9) Å, Z = 2, V = 2375(1) Å(3), R = 5.0%, R(w) = 6.8%; 2, trigonal R32, a = b = 11.813(3) Å, c = 28.37(1) Å, Z = 3, V = 3428(1) Å(3), R = 5.2%, R(w) = 6.4%. PMID:11666656

Kawaguchi, Hiroyuki; Tatsumi, Kazuyuki; Cramer, Roger E.

1996-07-17

178

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

PubMed

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; Palacios, J M; Brito, B

2013-08-09

179

Perfluoroalkylene Ether Bibenzoxazole Polymers.  

National Technical Information Service (NTIS)

According to the patent application, perfluoroalkylene ether bibenzoxazole polymers are prepared by the polycondensation of perfluoroalkylene ether bis(o-aminophenol) compounds and perfluoroalkylene ether-imidate and -thioimidate esters synthesized by the...

R. C. Evers

1976-01-01

180

Tacan Test Signal Set and Dme Test Signal Set. Phase I.  

National Technical Information Service (NTIS)

A feasibility model TACAN test signal set and a feasibility model DME test signal set was designed, developed, and constructed. Each test set is designed for making ground checks of their respective airborne interrogator units in current use by the commer...

F. Mimken V. Hazners

1966-01-01

181

Symmetry properties of vibrational modes in mesoporphyrin IX dimethyl ester investigated by polarization-sensitive resonance Raman and CARS spectroscopy.  

PubMed

The symmetry properties of selected vibrational modes of mesoporphyrin IX dimethyl ester (MP-IX-DME) in solution are investigated under different electronic resonance conditions. The Raman band parameters of the macrocycle modes nu(2), nu(10), nu(11), and nu(19) are determined from a quantitative analysis of polarized spontaneous resonance Raman (RR) and polarization-sensitive (PS) multiplex coherent anti-Stokes Raman scattering (CARS) spectra obtained with pre-resonant B band and resonant Qx band excitation, respectively. Additionally, the molecular geometry and the vibrational modes of MP-IX-DME are calculated by employing density functional theory (DFT) on the B3LYP/6-31G(d) level. Both the DFT-derived structure and the Raman spectroscopic parameters of MP-IX-DME indicate minor deviations from an ideal D2h macrocycle symmetry. To assess the influence of the beta substitution pattern on the in-plane symmetry, calculated normal-mode vectors and several experimentally detected parameters, such as peak positions, depolarization ratios, and coherent phases, are analyzed. The effects of the macrocycle substitution pattern are different for the selected vibrational modes: nu(2) in particular is very sensitive to subtle perturbations of the in-plane symmetry. The considerable activity of totally symmetric vibrations observed in the PS CARS spectra of MP-IX-DME and the correlation of mode symmetries with coherent phases confirm earlier PS CARS results on octaethylporphine (OEP) acquired under the same electronic resonance conditions. PMID:17004734

Koster, J; Popp, J; Kiefer, W; Schlücker, S

2006-10-01

182

Kinetics of Complexation of the Macrocycles 18C6 and 12C4 Ethers with LiAsF6 in 1,2-Dimethoxyethane at 25 deg C.  

National Technical Information Service (NTIS)

Ultrasonic relaxation spectra of the systems LiAsF6 added to the macrocycles 18C6 or 12C4 ethers, in molar ratio R approx. = 1, in the solvent 1,2-Dimethoxyethane (DME) at t=25 deg C are reported. The concentration range covered was 0.05 to 0.25M for 18C6...

H. Richman Y. Harada S. Petrucci

1984-01-01

183

Simple, Scalable, Script-based, Science Processor for Measurements - Data Mining Edition (S4PM-DME)  

NASA Astrophysics Data System (ADS)

The S4PM-DME is the Goddard Earth Sciences Distributed Active Archive Center's (GES DAAC) web-based data mining environment. The S4PM-DME replaces the Near-line Archive Data Mining (NADM) system with a better web environment and a richer set of production rules. S4PM-DME enables registered users to submit and execute custom data mining algorithms. The S4PM-DME system uses the GES DAAC developed Simple Scalable Script-based Science Processor for Measurements (S4PM) to automate tasks and perform the actual data processing. A web interface allows the user to access the S4PM-DME system. The user first develops personalized data mining algorithm on his/her home platform and then uploads them to the S4PM-DME system. Algorithms in C and FORTRAN languages are currently supported. The user developed algorithm is automatically audited for any potential security problems before it is installed within the S4PM-DME system and made available to the user. Once the algorithm has been installed the user can promote the algorithm to the "operational" environment. From here the user can search and order the data available in the GES DAAC archive for his/her science algorithm. The user can also set up a processing subscription. The subscription will automatically process new data as it becomes available in the GES DAAC archive. The generated mined data products are then made available for FTP pickup. The benefits of using S4PM-DME are 1) to decrease the downloading time it typically takes a user to transfer the GES DAAC data to his/her system thus off-load the heavy network traffic, 2) to free-up the load on their system, and last 3) to utilize the rich and abundance ocean, atmosphere data from the MODIS and AIRS instruments available from the GES DAAC.

Pham, L. B.; Eng, E. K.; Lynnes, C. S.; Berrick, S. W.; Vollmer, B. E.

2005-12-01

184

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

185

Operation of Microstrip Gas Chambers in Low Pressure Dimethyl Ether  

Microsoft Academic Search

Microstrip gas chambers (MSGC) are miniaturized gas ionization detectors fabricated using the techniques developed for integrated circuit manufacture. These detectors have better position resolution, faster timing, and a higher rate capability compared to standard MWPC detectors, and they offer a radiation hardened alternative to silicon microstrips for vertex detectors. We report here on operation of MSGC detectors at low pressure

M. D. Martin; K. P. Browne; J. B. Hutchins; W. K. Pitts; K. M. Walsh; K. Solberg

1996-01-01

186

Comparative predicting study of heterogeneous catalysis using support vector regression and neural networks with chaotic particle swarm optimization algorithm  

Microsoft Academic Search

This paper presents a comparative study of two artificial intelligence based heterogeneous catalysis modeling strategies, namely ANN-CPSO and SVR-CPSO, for modeling dimethyl ether (DME) in direct synthesis from syngas process (called STD process), for reducing both high temporal costs and financial costs, and accelerating the process of industrialization synthesis of DME. In the two hybrid approaches, catalyst compositional models and

Han Xiaoxia; Xie Gang; Xie Keming; Ren Jun

2009-01-01

187

Salvinorin B meth-oxy-methyl ether.  

PubMed

The title compound [MOM-SalB; systematic name: methyl (2S,4aR,6aR,7R,9S,10aS,10bR)-2-(3-fur-yl)-9-meth-oxy-meth-oxy-6a,10b-dimethyl-4,10-dioxo-2,4a,5,6,7,8,9,10a-octa-hydro-1H-benzo[f]isochromene-7-carboxyl-ate], C(23)H(30)O(8), is a deriv-ative of the ?-opioid salvinorin A with enhanced potency, selectivity, and duration of action. Superimposition of their crystal structures reveals, surprisingly, that the terminal C and O atoms of the MOM group overlap with the corresponding atoms in salvinorin A, which are separated by an additional bond. This counter-intuitive isosterism is possible because the MOM ether adopts the 'classic anomeric' conformation (gauche-gauche), tracing a helix around the planar acetate of salvinorin A. This overlap is not seen in the recently reported structure of the tetra-hydro-pyranyl ether, which is less potent. The classic anomeric conformation is strongly favoured in alk-oxy-methyl ethers, but not in substituted acetals, which may contribute to their reduced potency. This structure may prove useful in evaluating models of the activated ?-opioid receptor. PMID:23284529

Munro, Thomas A; Ho, Douglas M; Cohen, Bruce M

2012-10-27

188

Salvinorin B meth-oxy-methyl ether  

PubMed Central

The title compound [MOM-SalB; systematic name: methyl (2S,4aR,6aR,7R,9S,10aS,10bR)-2-(3-fur­yl)-9-meth­oxy­meth­oxy-6a,10b-dimethyl-4,10-dioxo-2,4a,5,6,7,8,9,10a-octa­hydro-1H-benzo[f]isochromene-7-carboxyl­ate], C23H30O8, is a deriv­ative of the ?-opioid salvinorin A with enhanced potency, selectivity, and duration of action. Superimposition of their crystal structures reveals, surprisingly, that the terminal C and O atoms of the MOM group overlap with the corresponding atoms in salvinorin A, which are separated by an additional bond. This counter-intuitive isosterism is possible because the MOM ether adopts the ‘classic anomeric’ conformation (gauche–gauche), tracing a helix around the planar acetate of salvinorin A. This overlap is not seen in the recently reported structure of the tetra­hydro­pyranyl ether, which is less potent. The classic anomeric conformation is strongly favoured in alk­oxy­methyl ethers, but not in substituted acetals, which may contribute to their reduced potency. This structure may prove useful in evaluating models of the activated ?-opioid receptor.

Munro, Thomas A.; Ho, Douglas M.; Cohen, Bruce M.

2012-01-01

189

Genotoxicity of glycol ethers  

SciTech Connect

The genetic toxicology of glycol ethers is reviewed. Ethylene glycol monomethyl ether (EGME) and diglyme have been more extensively studied than other members of this series. Most results indicate a lack of genotoxic potential, but certain tests have yielded positive responses with certain compounds. Ethylene glycol monoethyl ether (EGEE) induced sister chromatid exchanges and chromosomal aberrations in cultured cells. Both EGME and diglyme induced mouse sperm head morphological changes, male rat weak dominant lethal mutations and marked, but reversible, loss of male rat fertility. 22 references, 3 figures, 3 tables.

McGregor, D.B.

1984-08-01

190

High octane ethers from synthesis gas-derived alcohols  

SciTech Connect

The temperature dependence of ether synthesis, particularly unsymmetric methylisobutylether (MIBE), was carried out over the Nafion-H microsaddles (MS) catalyst. The principal product formed under the rather severe reaction conditions of 1100 psig pressure and temperatures in the range of 123--157{degree}C was the expected MIBE formed directly by coupling the methanol/isobutanol reactants. In addition, significantly larger quantities of the dimethylether (DME) and hydrocarbon products were observed than were obtained under milder reaction conditions. Deactivation of the Nafion-H MS catalyst was determined by periodically testing the catalyst under a given set of reaction conditions for the synthesis of MIBE and MTBE from methanol/isobutanol = 2/1, i.e. 123{degree}C, 1100 psig, and total GHSV = 248 mol/kg cat/hr. After carrying out various tests over a period of 2420 hr, with intermittant periods of standing under nitrogen at ambient conditions, the yields of MIBE and MTBE had decreased by 25% and 41%, respectively. In order to gain insight into the role of the surface acidity in promoting the selective coupling of the alcohols to form the unsymmetric ether, the strengths of the acid sites on the catalysts are still being probed by calorimetric titrations in non-aqueous solutions. 11 refs., 13 figs., 9 tabs.

Klier, K.; Herman, R.G.; DeTavernier, S.; Johannson, M.; Kieke, M.; Bastian, R.D.

1991-07-01

191

Metallacrown Ethers: Unique Organometallic Ligands  

Microsoft Academic Search

Metallacrown ethers are a unique class of complexes that form when R2PX-(CH2CH2O)nCH2CH2XPR2 (X = –, O; R = Ph, alkoxy; n = 3–5) ligands chelate to transition metals. Metallacrown ethers with cis-coordinated phosphines (cis-metallacrown ethers) contain a crown ether-like pocket and exhibit size-selective binding of alkali metal cations similar to that observed with the crown ethers. Binding of Li and

Gary M. Gray

1995-01-01

192

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

2012-12-13

193

Determination of dimethyl sulfoxide and dimethyl sulfone in air  

SciTech Connect

Dimethyl sulfoxide (DMSO) and dimethyl sulfone (DMSO{sub 2}) are believed to be intermediates in the marine atmospheric oxidation pathway of dimethyl sulfide (DMS) to SO{sub 2} and sulfate. This report presents for the first time, an analytical method for the determination of trace quantities of DMSO and DMSO{sub 2} in air. It describes in detail the analytical method that was only briefly mentioned in the original geochemical report of DMSO and DMSO{sub 2} in marine air.

Lang, R.F. (Univ. of Miami, FL (United States)); Brown, C.J. (NOAA/AOML Ocean Chemistry Division, Miami, FL (United States))

1991-01-15

194

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

195

Photooxidation of dimethyl sulfide and dimethyl disulfide. I: Mechanism development  

Microsoft Academic Search

Detailed theoretical (Part I, this article) and experimental (Part II) investigations are presented for the mechanism of the atmospheric photooxidation of dimethyl sulfide (CH3SCH3) and dimethyl disulfide (CH3SSCH3). In this paper, comprehensive mechanisms for the atmospheric chemistry of CH3SCH3 and CH3SSCH3 are developed based on fundamental considerations of all available kinetic and mechanistic information.

Fangdong Yin; Daniel Grosjean; John H. Seinfeld

1990-01-01

196

The effects of inhomogeneity in DME-Air mixture in combustion chamber on homogeneous charge compression ignition combustion  

Microsoft Academic Search

In the HCCI Engine, the inhomogeneity exists in fuel distribution and temperature in the pre-mixture microscopically, and has the possibility of affecting the ignition and combustion process. In this study, the effect of the inhomogeneity in DME\\/n-Butane-Air mixture in the combustion chamber on the HCCl combustion was investigated by chemiluminescence method in order to understand the spatial distribution of the

Ock Taeck Lim; Satoshi KETADANI; Kengo KUMANO; Norimasa IIDA

2007-01-01

197

Sorbents for High Temperature Removal of Arsenic from Coal-Derived Synthesis Gas  

Microsoft Academic Search

Gasification technologies convert coal and other heavy feedstocks into synthesis gas feed streams that can be used in the production of a wide variety of chemicals, ranging from hydrogen through methanol, ammonia, acetic anhydride, dimethyl ether (DME), methyl tertiary butyl ether (MTBE), high molecular weight liquid hydrocarbons and waxes. Syngas can also be burned directly as a fuel in advanced

G. O. Alptekin; R. Copeland; M. Dubovik; Y. Gershanovich

2002-01-01

198

Dimethyl ethanolamine-induced asthma.  

PubMed

Progressively severe sneezing, rhinorrhea, cough, wheezing, and dyspnea developed in a spray-painter, apparently in relation to exposure to a particular spray paint. A monitoring of exposure at work revealed the development of symptoms and a decrease in peak flow rates. Subsequent challenges in the laboratory performed under conditions resembling occupational exposure resulted in dual asthmatic responses on exposure to the whole paint (98 per cent methyl methacrylate emulsion and 2 per cent dimethyl ethanolamine solution) and to dimethyl ethanolamine solution (2 per cent) alone. Water, methyl methacrylate emulsion, and 1,4 dioxane (0.6 per cent) used as a thinner in the dimethyl ethanolamine did not produce a response in the airways. Allergy skin tests with dimethyl ethanolamine and a mixture of dimethyl ethanolamine and human serum albumin were negative. To our knowledge, this is the first report of asthma and/or rhinitis induced specifically by dimethyl ethanolamine. The mechanism of the specific reactivity is not known. PMID:857720

Vallieres, M; Cockcroft, D W; Taylor, D M; Dolovich, J; Hargreave, F E

1977-05-01

199

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

NASA Astrophysics Data System (ADS)

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-) 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+,e-) 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.

2009-10-01

200

Natural 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol®).  

PubMed

4-Hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF, furaneol®) and its methyl ether 2,5-dimethyl-4-methoxy-3(2H)-furanone (DMMF) are import aroma chemicals and are considered key flavor compounds in many fruit. Due to their attractive sensory properties they are highly appreciated by the food industry. In fruits 2,5-dimethyl-3(2H)-furanones are synthesized by a series of enzymatic steps whereas HDMF is also a product of the Maillard reaction. Numerous methods for the synthetic preparation of these compounds have been published and are applied by industry, but for the development of a biotechnological process the knowledge and availability of biosynthetic enzymes are required. During the last years substantial progress has been made in the elucidation of the biological pathway leading to HDMF and DMMF. This review summarizes the latest advances in this field. PMID:23765232

Schwab, Wilfried

2013-06-13

201

Glycol Ethers As Groundwater Contaminants  

Microsoft Academic Search

Ether derivatives of dihydroxy alcohols, which are formed from ethylene or propylene, comprise an important group of groundwater contaminants known as glycol ethers. Compounds in this group are used as solvents, cleaning agents, and emulsifiers in many chemical products and manufacturing operations. Glycol ethers have been associated with a variety of toxic effects, and some compounds in the group are

Benjamin Ross; Gunnar Johannson; Gregory D. Foster; William P. Eckel

1992-01-01

202

Binding of ether and carbonyl oxygens to lithium ion  

SciTech Connect

The power of a lithium battery depends on the mobility of the lithium ion. Since the lithium ion, Li{sup +}, binds to the mobile and nonmobile molecules in the electrolyte, then the strength of the Li{sup +} binding affects the conductivity of the electrolyte. The binding of dimethyl ether, diethyl ether, acetone, ethylene carbonate, and propylene carbonate to lithium ion calculated using ab initio quantum mechanics techniques. The binding of water and acetaldehyde to Li{sup +} has been calculated for higher coordination numbers. Using these energies, coordination numbers are predicted for all the species studied These energetics also provide the basis for molecular simulations of cationic transport in the electrolyte. 32 refs.

Blint, R.J. [General Motors Research and Development, Warren, MI (United States). Physical Chemistry Dept.

1995-03-01

203

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

204

Propenyl ether monomers for photopolymerization  

DOEpatents

Propenyl ether monomers of formula V A(OCH.dbd.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 formula V 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, James V. (Clifton Park, NY)

1996-01-01

205

Glycol Ethers As Groundwater Contaminants  

NASA Astrophysics Data System (ADS)

Ether derivatives of dihydroxy alcohols, which are formed from ethylene or propylene, comprise an important group of groundwater contaminants known as glycol ethers. Compounds in this group are used as solvents, cleaning agents, and emulsifiers in many chemical products and manufacturing operations. Glycol ethers have been associated with a variety of toxic effects, and some compounds in the group are relatively potent teratogens. The limited information available suggests that glycol ethers are contaminants in groundwater, especially in anaerobic plumes emanating from disposal of mixed industrial and household waste. Most methods used to analyze groundwater samples cannot adequately detect ?g/? (ppb) concentrations of glycol ethers, and the existing methods perform worst for the most widely used and toxic species. A new method capable of analyzing ?g/? concentrations of glycol ethers was recently developed, and its use is recommended for groundwater samples where glycol ethers are likely to be present.

Ross, Benjamin; Johannson, Gunnar; Foster, Gregory D.; Eckel, William P.

1992-01-01

206

Carbon–hydrogen bond dissociation enthalpies in ethers: a theoretical study  

Microsoft Academic Search

Density functional theory calculations based on different representations of the exchange-correlation functional (BLYP, B3LYP, B3PW91, mPW1PW91, B1LYP, BHandHLYP, BHandH, and B3P86) were carried out to predict C–H bond dissociation enthalpies in selected ethers (dimethyl ether, tetrahydrofuran (thf), and 1,4-dioxane), and some related molecules. Comparison with available experimental information shows that bond dissociation enthalpies are accurately predicted by several functionals when

Filipe Agapito; Benedito J. Costa Cabral; José A. Martinho Simões

2005-01-01

207

Photochemical Reactions of Dimethyl Acetylenedicarboxylate with Benzene and Naphthalene.  

National Technical Information Service (NTIS)

The photochemical reaction of dimethyl acetylenedicarboxylate with benzene gives dimethyl cycloocta-1,3,5,7-tetraene-1,8-dicarboxylate. In contrast, photoreaction of dimethyl acetylenedicarboxylate with molten naphthalene gives dimethyl 1-naphthalenefumar...

E. Grovenstein T. C. Campbell T. Shibata

1968-01-01

208

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

209

Kinetics of complexation of the macrocyclic ethers 18C6 and 12C4 with LiAsF/sub 6/ in 1,2-dimethoxyethane at 25C  

SciTech Connect

Ultrasonic relaxation spectra of the systems LiAsF/sub 6/ added to the macrocyclic ethers 18-crown-6 (18C6) or 12-crown-4 (12C4), in molar ratio R approx. = 1, in the solvent 1,2-dimethoxyethane (DME) at t = 25/sup 0/C, are reported. The concentration range covered was 0.05-0.25 M for 18C6 and 0.1-0.3 M for 12C4. Ancillary electrical conductance data for the same systems in the concentration range 10/sup -4/ to approx. 0.05 M at 25.00/sup 0/C reveal that the lithium-macrocycle interaction is weak, the conductance data being the same up to approx. 10/sup -2/ M, within experimental error of the data for the electrolyte alone in DME. 9 references, 5 figures, 2 tables.

Richman, H.; Harada, Y.; Eyring, E.M.; Petrucci, S.

1985-05-23

210

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

211

Poly(ether ether ketone)\\/poly(aryl ether sulphone) blends: thermal degradation behaviour  

Microsoft Academic Search

The thermodegradative behaviour of blends of poly(ether ether ketone) (PEEK) and poly(aryl ether sulphone) (PES) was studied by dynamic thermogravimetry in order to analyze their thermal stability. The Freeman–Carrol differential approach was used to determine the kinetic parameters i.e. the apparent activation energy (Ea) and order of reaction (n), of the degradation process. The results indicate that the presence of

Bhanu Nandan; L. D Kandpal; G. N Mathur

2003-01-01

212

TRANSPORTATION FUEL FROM COAL WITH LOW CO2 EMISSIONS  

Microsoft Academic Search

We present energy and carbon balances and cost estimates based on detailed Aspen Plus process simulations for five plant designs to co-produce dimethyl ether (DME) and electricity from coal. Four of the designs include capture of CO2 for long-term underground storage. We also illustrate the potential DME offers for reducing emissions by facilitating a shift to more energy-efficient vehicles.

Fuat Celik; Eric D. Larson; Robert H. Williams

213

Synthesis of DME from syngas on the bifunctional Cu–ZnO–Al 2O 3\\/Zr-modified ferrierite: Effect of Zr content  

Microsoft Academic Search

The catalytic activity on the coprecipitated Cu–ZnO–Al2O3\\/Zr-ferrierite (CZA–ZrFER) with different Zr content from 0 to 5wt.% was investigated for the direct synthesis of dimethylether (DME) from H2-deficient and biomass-derived model syngas (H2\\/CO molar ratio=0.93). The catalytic functionalities, such as CO conversion and DME selectivity, showed their maxima on the bifunctional catalyst with 3wt.% Zr-modified ferrierite. Detailed characterization studies were conducted

Jong Wook Bae; Suk-Hwan Kang; Yun-Jo Lee; Ki-Won Jun

2009-01-01

214

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

215

Influence of solid acid catalyst on DME production directly from synthesis gas over the admixed catalyst of Cu\\/ZnO\\/Al 2O 3 and various SAPO catalysts  

Microsoft Academic Search

This study focused on the effect of solid acid catalyst on the catalytic performance in direct DME synthesis. The various SAPO catalysts were prepared to perform methanol dehydration and direct DME synthesis. In methanol dehydration, SAPO-34 and -18 with strong acid sites and showed high initial activity, but deactivated rapidly. This is mainly attributed to the formation of coking materials

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

2007-01-01

216

Desoxyhemigossypol 6-methyl ether  

PubMed Central

The title sesquiterpene [systematic name: 6-methoxy-10-methyl-7-(propan-2-yl)-2-oxatricyclo[6.3.1.04,12]dodeca-1(11),4,6,8(12),9-pentaen-5-ol], C16H18O3, was isolated from pathogen-infected stele tissue of Gossypium barbadense. There are two mol­ecules in the asymmetric unit and the dihedral angle between their naphtho­furan systems is 86.48?(2)°. In the crystal, O—H?O hydrogen bonds between the hy­droxy groups and etheric O atoms link the mol­ecules into centrosymmetric tetra­mers. These tetra­mers are assembled into (010) layers via stacking inter­actions between the naphtho­furan systems [inter­planar distance 3.473?(3)?Å] and short C—H?O contacts.

Uzbekov, Vyacheslav V.; Talipov, Samat A.; Ibragimov, Bakhtiyar T.; Stipanovic, Robert D.; Liu, Jinggao

2013-01-01

217

Bis(dimethyl-ammonium) tetra-chlorido-dimethyl-stannate(IV)  

PubMed Central

Regular crystals of the title compound, (C2H8N)2[Sn(CH3)2Cl4], were obtained by reacting SnMe2Cl2 with (CH3)2NH·HCl in ethanol in a 1:1 ratio. The Sn atom lies on a center of symmetry and is six-coordinated. It has a distorted octahedral SnC2Cl4 environment with the Cl atoms in cis positions. The Cl atoms are connected to dimethyl­ammonium cations through N—H?Cl hydrogen bonds, forming an infinite chain extending parallel to [010].

Diop, Tidiane; Diop, Libasse; Michaud, Francois

2011-01-01

218

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

2012-10-29

219

[Role of the retinal pigment epithelium (RPE) in the pathogenesis and treatment of diabetic macular edema (DME)].  

PubMed

Pigment epithelium-derived factor (PEDF) has recently been shown to be the most potent inhibitor of angiogenesis in the mammalian eye, suggesting that loss of PEDF is involved in the pathogenesis of proliferative diabetic retinopathy. However, a protective role for PEDF in pericyte loss requires elucidation. Present studies suggest that PEDF proteins could protect against advanced glycation end product (AGE), which induce injury in retinal pericytes. Substitution of PEDF proteins may be a promising strategy in the treatment of patients with early diabetic retinopathy. Therefore, injury of RPE is the basic condition, not only of the progress of neovascularization, but initiation of early diabetic microangiopathy and macular edema as well. Recently new intravitreal drugs being used in the treatment of eye diseases with increased level of VEGE. Intravitreally administered a human, monoclonal anti-VEGF agent acts only as symptomatic treatment. It does not eliminate hypoxia and requires repeated administration. It is worth emphasizing, that VEGF functions are not limited to active angiogenesis, but also seems to require the maintenance and differentiation of mature blood vessels, such as the choriocapillaris. Therefore, delivery of these anti-VEGF treatments needs to be specific to sites of neovascularization or limited to a short duration, to prevent disruption of the normal vasculature. The effective method, which preserves RPE, improves oxygenation and release traction on the macula, leading to decreased permeability with subsequent resolution in DME, is pars plana vitrectomy with ILM peeling. There are several investigations that support the theoretical value of vitrectomy for the treatment of DME. Intraoperative administration of anti-VEGF agent and corticosteroids may additionally improve results of operative treatment. PMID:19112870

Chmielewska, Katarzyna; Robaszkiewicz, Jacek; Kosatka, Mariusz

2008-01-01

220

40 CFR 721.10099 - Dialkyl dimethyl ammonium carbonate (generic).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Dialkyl dimethyl ammonium carbonate (generic). 721.10099...721.10099 Dialkyl dimethyl ammonium carbonate (generic). (a...generically as dialkyl dimethyl ammonium carbonate (1:1) (PMN...

2009-07-01

221

40 CFR 721.10099 - Dialkyl dimethyl ammonium carbonate (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Dialkyl dimethyl ammonium carbonate (generic). 721.10099...721.10099 Dialkyl dimethyl ammonium carbonate (generic). (a...generically as dialkyl dimethyl ammonium carbonate (1:1) (PMN...

2013-07-01

222

40 CFR 721.10099 - Dialkyl dimethyl ammonium carbonate (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Dialkyl dimethyl ammonium carbonate (generic). 721.10099...721.10099 Dialkyl dimethyl ammonium carbonate (generic). (a...generically as dialkyl dimethyl ammonium carbonate (1:1) (PMN...

2010-07-01

223

Exogenous Ether Lipids Predominantly Target Mitochondria  

Microsoft Academic Search

Ether lipids are ubiquitous constituents of cellular membranes with no discrete cell biological function assigned yet. Using fluorescent polyene-ether lipids we analyzed their intracellular distribution in living cells by microscopy. Mitochondria and the endoplasmic reticulum accumulated high amounts of ether-phosphatidylcholine and ether-phosphatidylethanolamine. Both lipids were specifically labeled using the corresponding lyso-ether lipids, which we established as supreme precursors for lipid

Lars Kuerschner; Doris Richter; Hans Kristian Hannibal-Bach; Anne Gaebler; Andrej Shevchenko; Christer S. Ejsing; Christoph Thiele

2012-01-01

224

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.

Foundation, Wgbh E.

2004-02-20

225

Equations of state for fluorinated ether refrigerants, pentafluoroethyl methyl ether and heptafluoropropyl methyl ether  

Microsoft Academic Search

Thermodynamic properties of two fluorinated ethers, that meet the criteria of the potential new-generation refrigerants with considerably low global warming potential (GWP) and the zero ozone depletion potential (ODP), are studied in the present paper. The recommended candidates are pentafluoroethyl methyl ether, CF3CF2OCH3 (245cbE??), and heptafluoropropyl methyl ether, CF3CF2CF2OCH3 (347sE??), proposed as alternative refrigerants to replace 1,2-dichloro-1,1,2,2-tetrafluoroethane, CClF2CClF2 (R-114) and

Januarius V. Widiatmo; Koichi Watanabe

2001-01-01

226

Anaerobic degradation of decabromodiphenyl ether.  

PubMed

The environmental safety of decabromodiphenyl ether (BDE-209), a widely used flame retardant, has been the topic of controversial discussions during the past several years. Degradation of BDE-209 into lower brominated diphenyl ether congeners, exhibiting a higher bioaccumulation potential, has been a critical issue. Here, we report on the degradation of BDE-209 and the formation of octa- and nonabromodiphenyl ether congeners under anaerobic conditions. Sewage sludge collected from a mesophilic digester was used as the inoculum and incubated up to 238 days with and without a set of five primers. Following Soxhlet extraction and a liquid chromatography cleanup procedure, parent compounds and debromination products were analyzed by GC/HRMS. In experiments with primers, concentrations of BDE-209 decreased by 30% within 238 days. This corresponds to a pseudo-first-order degradation rate constant of 1 x 10(-3) d(-1). Without primers, the degradation rate constant was 50% lower. Formation of two nonabromodiphenyl ether and six octabromodiphenyl ether congeners proved that BDE-209 underwent reductive debromination in these experiments. Debromination occurred at the para and the meta positions, whereas debromination at the ortho position was not statistically significant. All three nonabromodiphenyl ether congeners (BDE-206, BDE-207, and BDE-208) were found to undergo reductive debromination as well. No significant change of the BDE-209 concentration and no formation of lower brominated congeners was observed in sterile control experiments. To our knowledge, this is the first report demonstrating microbially mediated reductive debromination of BDE-209 under anaerobic conditions. PMID:15773480

Gerecke, Andreas C; Hartmann, Paul C; Heeb, Norbert V; Kohler, Hans-Peter E; Giger, Walter; Schmid, Peter; Zennegg, Markus; Kohler, Martin

2005-02-15

227

Preparation and Properties of Dimethyl Phosphonomethyl Methylsiloxane Dimethylsiloxane Copolymers.  

National Technical Information Service (NTIS)

Dimethyl phosphonomethylheptamethylcyclotetrasiloxane and bis dimethyl phosphonomethyl tetramethyldisiloxane have been prepared by Arbuzov reaction of trimethyl phosphite with bromomethylheptamethylcyclotetrasiloxane and bis tetramethyldisiloxane, respect...

C. D. Juengst W. P. Weber

1987-01-01

228

Surface modification of segmented poly(ether urethane) by grafting sulfo ammonium zwitterionic monomer to improve hemocompatibilities  

Microsoft Academic Search

Segmented poly(ether urethane) (SPEU) was synthesized from 4,4?-diphenylmethane-diisocyanate, polytetramethylene glycol and 1,4-butandiol. SPEU was hydroxylated by potassium peroxosulfate and N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) ammonium was grafted onto hydroxylated SPEU using ceric ammonium nitrate as initiator. The bulk characterization of synthesized SPEU was investigated by FTIR and equilibrium water content. Surface analysis of grafted SPEU film was studied by ATR-FTIR, electron spectroscopy for chemical

Zhang Jun; Yuan Youling; Wu Kehua; Shen Jian; Lin Sicong

2003-01-01

229

Mathematical simulation and optimization of methanol dehydration and cyclohexane dehydrogenation in a thermally coupled dual-membrane reactor  

Microsoft Academic Search

Thermally coupling of endothermic and exothermic reactions in a membrane reactor improves thermal efficiency and production rate in the processes, reduces the size of reactors and decreases purification cost. This paper focuses on modeling and optimization of a thermally coupled dual-membrane reactor for simultaneous production of hydrogen, dimethyl ether (DME) and benzene. A steady state heterogeneous mathematical model is developed

M. Farsi; A. Jahanmiri

2011-01-01

230

In vitro antioxidant activity of Oldenlandia herbacea and isolation of 9,9-dimethyl hexacosane and 23-ethyl-cholest-23-en-3beta-ol.  

PubMed

The petroleum ether, chloroform, ethyl acetate and methanol extracts of the whole plant of Oldenlandia herbacea were screened for in vitro antioxidant activity by using ABTS, DPPH, nitric oxide and hydrogen peroxide assay methods. The chloroform, ethyl acetate and methanol extracts showed potent antioxidant activity against ABTS free radicals. In the hydrogen peroxide method, the methanol and ethyl acetate extracts showed potent activity. Chemical investigation of the petroleum ether extract yielded a long chain hydrocarbon, 9,9-dimethyl hexacosane (1), and a steroid, 23-ethyl-cholest-23-en-3beta-ol (2). PMID:19023815

Singaravelu, Pandian; Shrishailappa, Badami; Subban, Ravi

2008-01-01

231

Effect of water on liquid phase DME synthesis from syngas over hybrid catalysts composed of Cu\\/ZnO\\/Al 2 O 3 and ?-Al 2 O 3  

Microsoft Academic Search

DME synthesis from syngas via methanol has been carried out in a single-stage liquid phase reactor. Cu\\/ ZnO\\/Al2O3 and ?-Al2O3 were used together as methanol synthesis catalyst and dehydration catalyst, respectively. The influence of water on the catalytic\\u000a system was investigated mainly. Water affected the activity of methanol dehydration catalyst as well as methanol synthesis\\u000a catalyst. Thus, removal of water

Hak-Ju Kim; Heon Jung; Kwan-Young Lee

2001-01-01

232

21 CFR 868.5420 - Ether hook.  

Code of Federal Regulations, 2013 CFR

...Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5420 Ether hook. (a) Identification. An ether hook is a device...

2013-04-01

233

Polyphenylene Ethers with Imide Linking Groups.  

National Technical Information Service (NTIS)

Novel polyphenylene ethers with imide linking units are disclosed. These polymers incorporate the solvent and thermal resistance of polyimides and the processability of polyphenylene ethers. Improved physical properties over those of the prior art are obt...

T. L. St.Clair H. D. Burks

1983-01-01

234

Method of Obtaining Nonflammable Cellulose Ethers.  

National Technical Information Service (NTIS)

The method is given for obtaining nonflammable cellulose ethers by treating cellulose-containing raw material with phosphorylating agents in an organic solvent at a high temperature. Vinyl cellulose ethers were used as the cellulose-containing raw materia...

A. I. Polyakov V. V. Smagin L. A. Ilina

1970-01-01

235

The Chromosomally Encoded Cation Diffusion Facilitator Proteins DmeF and FieF from Wautersia metallidurans CH34 Are Transporters of Broad Metal Specificity  

PubMed Central

Genomic sequencing of the ?-proteobacterium Wautersia (previously Ralstonia) metallidurans CH34 revealed the presence of three genes encoding proteins of the cation diffusion facilitator (CDF) family. One, CzcD, was previously found to be part of the high-level metal resistance system Czc that mediates the efflux of Co(II), Zn(II), and Cd(II) ions catalyzed by the CzcCBA cation-proton antiporter. The second CDF protein, FieF, is probably mainly a ferrous iron detoxifying protein but also mediated some resistance against other divalent metal cations such as Zn(II), Co(II), Cd(II), and Ni(II) in W. metallidurans or Escherichia coli. The third CDF protein, DmeF, showed the same substrate spectrum as FieF, but with different preferences. DmeF plays the central role in cobalt homeostasis in W. metallidurans, and a disruption of dmeF rendered the high-level metal cation resistance systems Czc and Cnr ineffective against Co(II). This is evidence for the periplasmic detoxification of substrates by RND transporters of the heavy metal efflux family subgroup.

Munkelt, Doreen; Grass, Gregor; Nies, Dietrich H.

2004-01-01

236

Bacterial degradation of glycol ethers  

Microsoft Academic Search

Assimilation of ethyleneglycol (EG) ethers by polyethyleneglycol-utilizing bacteria was examined. Ethyleneglycol ether-utilizing bacteria were also isolated from soil and activated sludge samples by enrichment-culture techniques. Three strains (4-5-3, EC 1-2-1 and MC 2-2-1) were selected and characterized as Pseudomonas sp. 4-5-3, Xanthobacter autotrophicus, and an unidentified gram-negative, non-spore-forming rod respectively. Their growth characteristics were examined: Pseudomonas sp. 4-5-3 assimilated EG

F. Kawai

1995-01-01

237

Toxicokinetics of ethers used as fuel oxygenates  

Microsoft Academic Search

The toxicokinetics and biotransformation of methyl-tert.butyl ether (MTBE), ethyl-tert.butyl ether (ETBE) and tert.amyl-methyl ether (TAME) in rats and humans are summarized. These ethers are used as gasoline additives in large amounts, and thus, a considerable potential for human exposure exists. After inhalation exposure MTBE, ETBE and TAME are rapidly taken up by both rats and humans; after termination of exposure,

Wolfgang Dekant; Ulrike Bernauer; Elisabeth Rosner; Alexander Amberg

2001-01-01

238

Method of Converting Certain Allylic Ethers to Dienol Ethers.  

National Technical Information Service (NTIS)

This patent application pertains to a method of producing thebaine from codeine and oripavine from morphine which comprises (a) producing the 0-6 methyl ethers from codeine and morphine using potassium hydride and methyl iodide as the O-alkylation agents ...

H. Rapoport R. B. Barber

1976-01-01

239

Long-term stability of cell micropatterns on poly((3-(methacryloylamino)propyl)-dimethyl(3-sulfopropyl)ammonium hydroxide)-patterned silicon oxide surfaces  

Microsoft Academic Search

In this work, we compared the long-term stability and integrity of cell patterns on newly reported, zwitterionic poly((3-(methacryloylamino)propyl)dimethyl(3-sulfopropyl)ammonium hydroxide) (poly(MPDSAH)) films with those on widely used, poly(poly(ethylene glycol) methyl ether methacrylate) (poly(PEGMEMA)) ones. The micropatterns of both polymers were formed on a silicon oxide surface by a combination of micropattern generation of a photoresist, vapor deposition of a silane-based polymerization

Woo Kyung Cho; Bokyung Kong; Hyung Ju Park; Jinkyu Kim; Won Chegal; Joon Sig Choi; Insung S. Choi

2010-01-01

240

A novel method for solid-phase synthesis of oligosaccharides using the N-1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl (Dde) linker  

Microsoft Academic Search

The application of the N-1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl (Dde) linker for the solid-phase synthesis of oligosaccharides is described. The oligosaccharide products can be cleaved from the resin by hydrazine, ammonia or primary amines, but the linker is stable under the conditions of oligosaccharide synthesis. The first sugar can be attached to the resin linker via a vinylogous amide bond, or by ether linkage

Nicholas Drinnan; Michael L West; Max Broadhurst; Barrie Kellam; Istvan Toth

2001-01-01

241

Lubricity of fluorinated alkyl aryl ethers  

Microsoft Academic Search

A series of fluorinated alkyl aryl ethers, composed of hydrocarbon components, fluorinated alkyl groups, and ether linkage groups, were evaluated through a variety of tests to investigate lubricating properties. The basic molecular structure with tetrafluoroethoxyphenyl groups were shown to have excellent lubricities. However, ortho-position substituents to ether linkage groups diminished extreme-pressure properties. Excellent lubricities were suggested to be due to

Hiroyuki Fukui; Hiroshi Murata; Ken-ichi Sanechika; Masanori Ikeda

2000-01-01

242

On new physical reality (on ? ether)  

NASA Astrophysics Data System (ADS)

It is shown that there exists a new physical reality-the ? ether. All the achievements of quantum mechanics and quantum field theory are due to the fact that both the theories include the influence of ? ether on the physical processes occurring in the Universe. Physics of the 20th century was first of all the physics of ? ether.

Isaev, P. S.

2012-05-01

243

Triterpene methyl ethers from palmae epicuticular waxes  

Microsoft Academic Search

Cylindrin and lupeol methyl ether were isolated for the first time from Palmae leaf epicuticular waxes. Butia capitata and Orbignya spp. contain large amounts of ethers, but these are absent in Arecastrum romanzoffianum. A new triterpene methyl ether was isolated from O. phalerata wax. The new compound was characterized as 3-?-methoxy lupane.

S. García; H. Heinzen; C. Hubbuch; R. Martínez; X. de Vries; P. Moyna

1995-01-01

244

Complex Formation between Dimethyl Methylphosphonate and Hexafluoroisopropanol.  

National Technical Information Service (NTIS)

A solvent/water partitioning method was used to measure the complex formation between dimethyl methylphosphonate (DMMP) and hexafluoroisopropanol (HFIP). The highest formation constant was obtained when n-hexane was used as the partitioning solvent. Other...

D. C. Leggett

1990-01-01

245

Fluorinated ethers: A new family of halons. Rept. for Feb 90-Oct 91  

SciTech Connect

The paper discusses the possibility of fluorinated ethers' being a new family of halons. Work at the University of Tennessee to find suitable replacements for fully halogenated chlorofluorocarbons (CFCs) and halons has centered on the incorporation of oxygen as a heteroatom. The most stable class of compounds, fluorinated ethers, potentially doubles the number of candidates versus just the halogenated alkanes, with minimal change in physical properties. The first comparison of compounds involves the dimethyl ether series of compounds which provide substitutionally similar analogs to ethanes. The synthesis, characterization, and physical properties of all of the perfluorinated ethers are discussed briefly and their extinguishment concentrations are tabulated. The work indicates that the mechanism by which perfluorocarbons achieve their flame extinguishment capability is rooted more in the ability to dissipate the energy of free radicals and permit their recombindation, than it is by any bond dissociative or other purely chemical mechanism. This implies that, in the absence of overriding chemical effects (bromine), there should be a correlation between infrared absorptivity and extinguishant effectiveness.

Adcock, J.L.; Mathur, S.B.; Huang, H.Q.; Mukhopadhyay, P.; Wang, B.H.

1991-01-01

246

Ab initio calculated structures of conformers for 1,3-dimethoxy- p-tert-butylcalix[4]crown-5-ether complexed with potassium cation  

Microsoft Academic Search

Stable molecular conformations were calculated for the 1,3-dimethyl ether of p-tert-butylcalix[4]crown-5-ether (1) in the various conformers and their potassium-ion complexes. The structures of three distinct conformations have been optimized using ab initio RHF\\/6-31G methods. After geometry optimizations, B3LYP\\/6-31+G(d,p) single point calculations of the final structures are done to include the effect of electron correlation and the basis set with diffuse

Jong-In Choe; Suk-Kyu Chang; Sik Lee; Shinkoh Nanbu

2005-01-01

247

Catalytic consequences of acid strength in the conversion of methanol to dimethyl ether  

Microsoft Academic Search

The effects of acid identity on CH3OH 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 (kmono) and zero-order (kdimer) CH3OH dehydration rate constants depend exponentially on DPE for POM clusters; the value of kmono

Robert T. Carr; Matthew Neurock; Enrique Iglesia

2011-01-01

248

Control of Ignition and Combustion of Dimethyl Ether in Homogeneous Charge Compression Ignition Engine  

Microsoft Academic Search

A homogeneous charge compression ignition (HCCI) engine is known to have high thermal efficiency and low nitrogen oxide emission. However, the control of ignition timing and its combustion period over a wide range of engine speeds and loads is one of the barriers to the realization of the engine. On the lean side of the equivalence ratio, control of ignition

Kyoung-Oh Kim; Akihiko Azetsu; Chikashi Oikawa

2003-01-01

249

Liquid Densities of Fluorinated Ethers  

NASA Astrophysics Data System (ADS)

The liquid densities of thirteen fluorinated ethers which are expected as promising candidates of CFC alternatives were measured at temperatures from 278 K to 323 K and atmospheric pressure. The fluorinated ethers used in this study are 1-difluoromethoxy-1,1, 2- trifluoroethane, 1-methoxy-1, 1,2,2-tetrafluoroethane, 1-methoxy-2,2 ,3 ,3- tetrafluoropropane, 1-methoxy-1-trifluoromethy1-2,2 ,2- trifluoroethane, 1-methoxy-1,1,2,2, 3-hexafluoropropane,1-difluoromethoxy-2,2, 3, 3 -tetrafluoropropane, 1-methoxy-heptafluoropropane,1-difluoromethoxy-2, 2, 3, 3, 3-pentafluoropropane, 1- (2, 2, 2-trifruoroethoxy) -1, 1, 2,2-tetrafluoroethane, 1-pentafluoroethoxy-1, 1, 2, 2-tetrafluoroethane,2-trifluoromethoxy-1, 1, 1,2-tetrafluorobutane, 1-proxynonafluorobutane, and 1-ethoxy-undecafluoropentane. The liquid density has been measured by the vibrating tube densitometer (ANTON PARR, DMA 602) within an error of 0.07%. The liquid densities decrease monotonically with increase of temperature.

Nakazawa, Noriaki; Sako, Takeshi; Nakane, Takashi; Sekiya, Akira; Kawamura, Mitsutaka; Sato, Masahito; Mochizuki, Yuji; Takada, Naoto; Yasumoto, Masahiko

250

Ether symmetry unification theory (ESU)  

SciTech Connect

The ether symmetry unification (ESU) theory postulates a mechanism that accounts for the formation of the universe as well as the formation of the original mass particles following the big bang. The essential role of the medium-vacuum of the theory of prerelativity is explained. The ultra-high energy particles described in the Ether Symmetry Unification Theory are compared with high energy magnetic monopoles described by Supersymmetry. Phase transitions of high energy events to low energy events and the associated media-vacua involved, postulated by the ESU, are then compared to the low energy events of the standard model within the critical phases of the first two seconds of quantum field theory`s time line.

Cunningham, R.B.

1995-10-01

251

Measuring exposures to glycol ethers.  

PubMed Central

In 1981, NIOSH began investigating the potential reproductive health effects resulting from exposures to a class of organic solvents known generically as glycol ethers (GE). This research was begun as a result of the NIOSH criteria document development program which revealed little data available on the health effects of glycol ether exposure. Toxicologic research was begun by NIOSH and other researchers which suggested substantial reproductive effects in animals. These animal data motivated a study of human exposures in the occupational setting. In 1981 and 1982 NIOSH conducted several walk-through surveys which included preliminary measurements of exposures in a variety of industries including painting trades, coal mining, production blending and distribution facilities, aircraft fueling, and communications equipment repair facilities. The human exposure data from these surveys is summarized in this paper with most results well below 1 parts per million (ppm) and only a few values approaching 10 ppm. Blood samples were collected at one site resulting in GE concentrations below the limit of detection. Exposures to airborne glycol ethers, in the industries investigated during the collection of this data, revealed several problems in reliably sampling GE at low concentrations. It became apparent, from the data and observations of work practices, that air monitoring alone provided an inadequate index of GE exposure. Further field studies of exposure to GE are anticipated, pending location of additional groups of exposed workers and development of more reliable methods for characterizing exposure, especially biological monitoring.

Clapp, D E; Zaebst, D D; Herrick, R F

1984-01-01

252

Measuring exposures to glycol ethers.  

PubMed

In 1981, NIOSH began investigating the potential reproductive health effects resulting from exposures to a class of organic solvents known generically as glycol ethers (GE). This research was begun as a result of the NIOSH criteria document development program which revealed little data available on the health effects of glycol ether exposure. Toxicologic research was begun by NIOSH and other researchers which suggested substantial reproductive effects in animals. These animal data motivated a study of human exposures in the occupational setting. In 1981 and 1982 NIOSH conducted several walk-through surveys which included preliminary measurements of exposures in a variety of industries including painting trades, coal mining, production blending and distribution facilities, aircraft fueling, and communications equipment repair facilities. The human exposure data from these surveys is summarized in this paper with most results well below 1 parts per million (ppm) and only a few values approaching 10 ppm. Blood samples were collected at one site resulting in GE concentrations below the limit of detection. Exposures to airborne glycol ethers, in the industries investigated during the collection of this data, revealed several problems in reliably sampling GE at low concentrations. It became apparent, from the data and observations of work practices, that air monitoring alone provided an inadequate index of GE exposure. Further field studies of exposure to GE are anticipated, pending location of additional groups of exposed workers and development of more reliable methods for characterizing exposure, especially biological monitoring. PMID:6499824

Clapp, D E; Zaebst, D D; Herrick, R F

1984-08-01

253

In vitro genotoxicity of dimethyl terephthalate.  

PubMed

Dimethyl terephthalate (DMTP), the para configuration of dimethyl phthalate, is one of the basic monomers used in the synthesis of polyethylene terephthalate (PET) plastics. Human exposure to DMTP may primarily occur during the manufacture of PET fibers and films. The mutagenic potential of dimethyl terephthalate was evaluated using a battery of in vitro short-term tests: the Ames test; DNA single-strand break assays in CO60 cells and in primary rat hepatocytes; UDS in HeLa cells; chromosome aberration and micronucleus assays in human peripheral blood lymphocytes; selective DNA amplification in CO60 and in Syrian hamster embryo cells. The results of this battery of in vitro assays clearly show that DMTP is nongenotoxic. By contrast, other authors have found DMTP to be an in vivo clastogenic compound and suggested that the mechanisms involved in these in vivo effects seem to have nothing in common with genotoxicity and are still unknown. PMID:2000099

Monarca, S; Pool-Zobel, B L; Rizzi, R; Klein, P; Schmezer, P; Piatti, E; Pasquini, R; De Fusco, R; Biscardi, D

1991-02-01

254

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

NASA Astrophysics Data System (ADS)

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 shift. The obtained intercolumn hopping rates lead us to the conclusion that the electron hopping to a hole soliton carrying a fractional charge of e/2 in the neighbor column dominates the intercolumn charge transport.

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

2003-08-01

255

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.

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

1998-08-04

256

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

257

Photopolymerization of glycerin triglycidyl ether based systems  

Microsoft Academic Search

Photopolymerization process of glycerin triglycidyl ether based systems was studied by an FT-IR spectrometer. An increase\\u000a in the rate of polymerization for glycerin triglycidyl ether was evident when 3,4-epoxycyclohexylmethyl-3?,4?-epoxycyclohexanecarboxylate\\u000a was added to it. Its copolymerization mechanism was confirmed by using DSC analysis. The effect of ethoxylated trimethyol\\u000a propane triacrylate on the rate of polymerization for glycerin triglycidyl ether was also

Biwu Huang; Yiwang Chen; Qilan Deng

2008-01-01

258

Metal ion complexation by ionizable crown ethers  

SciTech Connect

Research conducted since the last progress report includes the synthesis and characterization of twenty three novel proton-ionizable crown ether compounds. Metal ion complexation behavior of new and previously-synthesized proton-ionizable crown ether compounds has been probed by solvent extraction and transport across polymer-supported liquid membranes. The behavior of neutral polyether and proton-ionizable polyether ligands in polymeric membrane electrodes has been assessed. Studies of the use of proton-ionizable crown ethers for separation of lithium isotopes were initiated. Also, the thermodynamics of interactions between alkali metal cations and ionized crown ethers have been probed by titration calorimetry. 10 refs., 1 tab.

Bartsch, R.A.

1989-09-01

259

40 CFR 721.3465 - Stilbene diglycidyl ether.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Stilbene diglycidyl ether. 721.3465 Section...Chemical Substances § 721.3465 Stilbene diglycidyl ether. (a) Chemical...The chemical substance identified as stilbene diglycidyl ether (PMN...

2009-07-01

260

40 CFR 721.3465 - Stilbene diglycidyl ether.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Stilbene diglycidyl ether. 721.3465 Section...Chemical Substances § 721.3465 Stilbene diglycidyl ether. (a) Chemical...The chemical substance identified as stilbene diglycidyl ether (PMN...

2010-07-01

261

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

262

Zinc dust-mediated reductive degradation of decabromodiphenyl ether  

Microsoft Academic Search

Zinc dust serves as a reducing agent in the presence of ammonium formate and NaOH, and is highly effective for the hydrodebromination of decabromodiphenyl ether to give diphenyl ether and the less brominated diphenyl ethers.

Guo-Bin Liu; Hong-Yun Zhao; Bin Yang; Thies Thiemann

2010-01-01

263

Dimethyl Sulfoxide Effects on Isolated Fat Cells.  

National Technical Information Service (NTIS)

The ability of dimethyl sulfoxide to inhibit insulin-stimulated glucose oxidation is not the result of the increased lipolysis observed in the absence of insulin with DMSO. Free fatty acids have been shown to inhibit insulin action on fat cells but DMSO s...

P. B. Wieser

1983-01-01

264

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

265

Critical properties of fluorinated ethers  

Microsoft Academic Search

Using a static-type apparatus, the authors measured the critical temperatures, pressures, and densities of seven fluorinated ethers: CFâCHFOCHFâ, CFâCFâOCHâ, CFâCHâOCHâ, CFâCFâOCHâCFâ, CFâCFâOCHâCHâ, CFâCFâCFâOCHâ, and (CFâ)âCFOCHâ. The advantage of the measuring apparatus was that a small amount of a sample was sufficient to determine the critical properties accurately. The uncertainties of the critical properties measured in this work were {+-}30 mK

Takeshi Sako; Masahito Sato; Noriaki Nakazawa; Masaru Oowa; Masahiko Yasumoto; Haruaki Ito; Shiro Yamashita

1996-01-01

266

Organic compounds in coal-slurry-pipeline waters. Final report. [Phenol, o-cresol, p-cresol, 2,6-dimethyl phenol, o-ethyl phenol, 3,5-dimethyl phenol  

SciTech Connect

Organic compounds in the water separated from coal pipeline slurry has been investigated on a laboratory basis for the slurry with each of three subbituminous coals: Wyodak, Illinois No. 6 and Black Mesa. The results are compare with results from the Black Mesa Pipeline slurry. Compounds such as aryl hydrocarbons, nitrogenous bases, aryl thiophenes and aryl ethers are all more than 99.9% adsorbed when added to water before slurry formation and are undetectable in the resulting slurry waters. Phenols occur in slurry waters and their identification and quantification using methylation with perdeutero phenol as an internal standard for capillary column GC/MS of the methyl ethers is described. Phenol, o-cresol, p-cresol, 2,6-dimethyl phenol, o-ethyl phenol and 3,5-dimethyl phenol were identified and quantified in all slurry waters from each coal. Laboratory results on slurry waters from Black Mesa coal are in agreement with the results for these phenols in the clariflocculator overflow water at the Mohave Generating Station. 4 figures, 13 tables.

Newton, A.S.; Fox, P.J.; Villarreal, H.; Raval, R.; Walker, W. II

1982-09-01

267

Separation of divinyl ether fatty acid isomers by micellar electrokinetic chromatography.  

PubMed

A micellar electrokinetic chromatography (MEKC) method has been developed for the direct resolution of divinyl ether type of hydrophobic fatty acid isomers. The fatty acid isomers resolved include colneleic acid (CL), colnelenic acid (CLn), 14(Z)-etheroleic acid (14(Z)-EL), 14(Z)-etherolenic acid (14(Z)-Eln), 11(Z)-etheroleic acid (11(Z)-EL), 11(Z)-etherolenic acid (11(Z)-Eln), etheroleic acid (EL) and etherolenic acid (Eln). These fatty acid isomers differ in number, position and spatial arrangement of the double bonds and the position of the ether oxygen. A central composite design was employed for the optimization of the key variables of the separation, namely the concentrations of sodium dodecyl sulfate (SDS) and organic modifiers. The use of micelles combined with an organic modifier in the background electrolyte made it possible to dissolve and separate relatively hydrophobic fatty acid isomers, and to achieve high separation efficiency. Using heptakis-(2,3-dimethyl-6-sulfato)-beta-cyclodextrin (HDMS-beta-CD) as a buffer additive, complete separation of the examined eight divinyl ethers was achieved. Separation efficiencies up to 5 x 10(5) theoretical plates/m were achieved under optimized conditions. Direct UV was applied for detection of the fatty acids. The results were compared with those obtained from high-performance liquid chromatography (HPLC) separation. PMID:11358142

Ohman, M; Wang, H; Hamberg, M; Blomberg, L G

2001-04-01

268

Fluorinated Vinyl Ethers and Use Thereof.  

National Technical Information Service (NTIS)

This patent pertains to the synthesis of novel fluoroalkyl ethers, typically (CF3)2CF-O-CH2-CH2-Br which are prepared by reacting a ketone with an alkali metal fluoride, then reacting the resulting intermediate with a dihaloethane. These ethers may be deh...

A. G. Pittman W. L. Wasley

1974-01-01

269

Ethers have good gasoline-blending attributes  

SciTech Connect

Because of their compatibility with hydrocarbon gasoline-blending components, their high octane blending values, and their low volatility blending values, ethers will grow in use as gasoline blending components. This article discusses the properties of ethers as blending components, and environmental questions.

Unzelman, G.H.

1989-04-10

270

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

271

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

272

Dimethyl carbonate for environmentally benign reactions  

Microsoft Academic Search

Dimethyl carbonate (DMC) is a unique molecule having a versatile reactivity. The transesterification of DMC with phenol gives methyl phenyl carbonate, which is converted into diphenyl carbonate (DPC) by disproportionation. MoO3\\/SiO2 is an active catalyst for both reactions. DPC is an essential monomer in the non-phosgene route for polycarbonates. The methoxycarbonylation of aniline gives methyl N-phenyl carbamate in the presence

Yoshio Ono

1997-01-01

273

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

2004-11-17

274

Synthesis of highly lipophilic crown ether carboxylic acids  

SciTech Connect

Synthetic routes to eight highly lipophilic crown ether carboxylic acids are described. Structural variations within this series of crown ether carboxylic acids include changes in the crown ether cavity size, the lipophilic group attachment site, and the basicity of the crown ether oxygens.

Bartsch, R.A.; Liu, Y.; Kang, S.I.; Son, B.; Heo, G.S.; Hipes, P.G.; Bills, L.J.

1983-01-01

275

Criteria for a Recommended Standard: Occupational Exposure to Glycidyl Ethers.  

National Technical Information Service (NTIS)

Glycidyl ethers are characterized by the presence of a three-carbon chain with an epoxide group and an ether linkage. This recommended standard applies to monoglycidyl ethers and diglycidyl ethers that contain an alkyl group, an aromatic group, or a moiet...

C. Woodbury

1978-01-01

276

The estimation of ether's enthalpies of formation  

NASA Astrophysics Data System (ADS)

Taking hydrocarbon as gerneratrix, the differences of enthalpies of formation of ether and their corresponding generatrixes were compared and concluded and the equation to estimate ether’s enthalpy of formation, which was ?f H {e/°}/(kJ/mol) = K(?f H {m/?} - 90 + A) was obtained. The results can be elucidated with bond dissociation energies data, bond-enthalpy of formation method, induction effect and conjugative effect. The more essential account to explain the results can be got by using quantum chemistry theories, etc. Using replacement and comparison method, the way of estimation of organic compounds’ thermodynamic properties including enthalpy of formation can be obtained either.

Li, Yansheng; Zhang, Baolin; Li, Hongping

2009-03-01

277

Solvent-induced crystallization of poly(ether ether ketone)  

NASA Astrophysics Data System (ADS)

The purpose of this study was learn how the diffusion, swelling, and crystallization processes are coupled during solvent-induced crystallization of poly(ether ether ketone) (PEEK). Unoriented amorphous PEEK films were immersed in aprotic organic liquids at ambient temperature and bulk properties or characteristics were monitored as a function of immersion time. The sorption behavior, T g and Tm° suppression, crystallinity, and dynamic mechanical response were correlated as a function of solvent chemistry and immersion time. The saturation time of methylene chloride, 1,3-dichloropropane, tetrahydrofuran, cyclopentanone, chlorobenzene, toluene, diethyl ketone, and ethylbenzene in amorphous PEEK films were found to range from hours to days depending on the level of polymer-solvent interactions. In-situ isochronal DMA spectra show that the Tg of PEEK was suppressed from 150°C to below ambient temperature such that crystallization was kinetically feasible during ambient immersion. In addition, an increase in viscoelastic dispersion was attributed to the presence of crystallinity. From dynamic mass uptake and wide-angle x-ray diffraction (WAXD) results, it was found that the bulk sorption rate was equal to the bulk crystallization rate for all solvent systems that promoted SINC and PEEK exhibited diffusion-limited crystallization, irrespective of the nature of the transport mechanism. In addition, the solvent-induced crystals exhibit preferred orientation as supported by photographic WAXD. A distinct sorption front, observed with scanning electron microscopy, further supports the scenario of diffusion-controlled crystallization and one-dimensional diffusion. Isothermal DMA spectra for THF, cyclopentanone, and chlorobenzene, indicate that, as the solvent diffuses into the films, the stiffness of the polymer decreases at short times, begins to increase, and then reaches a relatively time-independent value. It was determined that the initial decrease in the storage modulus was due to the incredible plasticization of the amorphous phase. When the films contained greater than 60% of the ultimate crystallinity, the storage modulus was observed to increase as a result of the reinforcing effect of the solvent-induced crystals. WAXD and mass uptake results confirm that the plateau in the storage modulus coincides with the completion of bulk crystallization and saturation of the amorphous phase.

McPeak, Jennifer Lynne

278

Synthesis of highly fluorinated poly(arylene ether)s copolymers for proton exchange membrane materials  

Microsoft Academic Search

Highly fluorinated poly(arylene ether)s containing sulfonic acid groups meta to ether linkage (SPAE), intended for fuel cell applications as proton electrolyte membrane materials, were synthesized by potassium carbonate mediated nucleophilic polycondensation reactions of commercially available monomers: 2,8-dihydroxynaphthalene-6-sulfonated salt (2,8-DHNS-6), hexafluorobisphenol A (6F-BPA), and decafluorobiphenyl (DFBP) in dimethylsulfoxide (DMSO) at 160–170°C. FT-IR and 1H NMR were used to characterize the structures.

Dae Sik Kim; Gilles P. Robertson; Michael D. Guiver; Young Moo Lee

2006-01-01

279

Preparation and characterization of semi-crystalline poly(ether ether ketone) hollow fiber membranes  

Microsoft Academic Search

Semi-crystalline poly(ether ether ketone) (PEEK) hollow fiber membranes were successfully prepared utilizing a two step membrane preparation process. In the first step, precursory hollow fibers were formed from blends of PEEK and poly(ether imide) (PEI) by melt extrusion. In the second step, porous PEEK hollow fiber membranes were formed by selective decomposition and removal of the polyimide phase utilizing a

Yong Ding; Benjamin Bikson

2010-01-01

280

A mild and selective deprotection of p-methoxybenzyl (PMB) ether by magnesium bromide diethyl etherate-methyl sulfide  

Microsoft Academic Search

The magnesium bromide diethyl etherate (MgBr2·OEt2)-methyl sulfide (Me2S) system is useful for the mild and chemo-selective deprotection of p-methoxybenzyl (PMB) ether in the presence of 1,3-diene, t-butyldimethylsilyl (TBDMS) ether, benzoate, benzyl ether and acetonide.

Toshihiko Onoda; Ryuichi Shirai; Shigeo Iwasaki

1997-01-01

281

Fluroinated Ethers: A New Family of Halons.  

National Technical Information Service (NTIS)

The paper discusses the possibility of fluorinated ethers' being a new family of halons. Work at the University of Tennessee to find suitable replacements for fully halogenated chlorofluorocarbons (CFCs) and halons has centered on the incorporation of oxy...

J. L. Adcock S. B. Mathur H. Q. Huang P. Mukhopadhyay B. H. Wang

1991-01-01

282

Exposure Assessment of Polybrominated Diphenyl Ethers.  

National Technical Information Service (NTIS)

Polybrominated diphenyl ethers, PBDEs, are a class of brominated flame retardants that, like other persistent organic pollutants (POPs), have been found in humans, wildlife, and biota worldwide. Unlike other POPs, however, the key routes of human exposure...

D. Cleverly M. Lorber

2010-01-01

283

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

284

Urea and Thiourea Derivatives of Bis(dimethyl-phosphinoylmethyl)-amine  

Microsoft Academic Search

A group of hitherto unknown 1-aryl-3,3-bis(dimethyl-phosphinoylmethyl)-, 1-benzyl-3,3-bis(dimethyl-phosphinoylmethyl)- and 1-cyclohexyl-3,3-bis(dimethyl-phosphinoylmethyl) ureas and thioureas 1-10 have been synthesized, characterized, and are reported in this article. The compounds were prepared via reaction of corresponding isocyanates or isothiocyanates with the secondary phosporus-containing amine: bis(dimethyl-phosphinoylmethyl)-amine. The composition of the novel compounds was proved by elemental analysis, corresponding structures were confirmed by IR, 1 H-, 31

Viktoria Lachkova; Sabi Varbanov; Gerhard Hägele; Helmut Keck; Tania Tosheva

2002-01-01

285

Biosynthesis and biotransformation of ether lipids  

Microsoft Academic Search

Some naturally occurring as well as synthetic ether lipids are biologically active. In certain cases, the effects of these\\u000a substances are enhanced, in others, they are inhibited by compounds that were isolated from natural sources or prepared by\\u000a chemical synthesis. The biotrans-formation of natural or “unnatural” ether lipids in microorganisms, plant or animal tissue\\u000a also can lead to substances that

Helmut K. Mangold; Nikolaus Weber

1987-01-01

286

Synthesis of planar chiral ferrocenyl 1,3-diamines and 1,3-amino ethers.  

PubMed

The efficient syntheses of novel planar chiral 1,3-diamines and 1,3-amino ethers with an oxy or amino function directly bound to the cyclopentadienyl ring of ferrocene has been developed. The key reaction is the Cu2O promoted substitution of (pR)-N,N-diisopropyl-2-iodoferrocenecarboxamide with either phthalimide or AcOH to introduce nitrogen or oxygen functionality onto the cyclopentadienyl ring. The enantiomerically pure iodoferrocene derivative is available from the known enantioselective ortho-lithiation of N,N-diisopropylferrocenecarboxamide with n-BuLi-sparteine. In the course of these studies the synthesis of a novel C2 symmetric C-2 dimer of N,N-dimethyl-1-ferrocenylethylamine was characterised by single crystal X-ray diffraction. PMID:14599022

Anderson, James C; Blake, Alexander J; Arnall-Culliford, Jennifer C

2003-10-21

287

Poly(aryl ethers) and related polysiloxane copolymer molecular coatings: preparation and radiation degradation. Final report  

SciTech Connect

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.

1982-05-01

288

Synthesis and Characterization of Poly(phthalazinone Ether Nitrile) Copolymers with Hydrophobic Surface  

NASA Astrophysics Data System (ADS)

Poly(phthalazinone ether nitrile) (PPEN) block copolymers containing polysiloxane were prepared so as to create a strongly hydrophobic polymer surface. The copolymers were synthesized from eugenol end-capped polydimethylsiloxane (PDMS) and fluoro-terminated PPEN oligomers by the aromatic nucleophilic substitution polycondensation in the presence of dimethyl sulfoxide/o-dichlorobenzene and K2CO3 as solvents and catalyst, respectively. The resultant copolymers were characterized by FTIR, 1H NMR, and gel permeation chromatography. XPS analysis results indicated that the copolymer film had a very rich PDMS segment surface. Atomic force microscopy further showed that there existed a continuous PDMS phase on the copolymer surface and PPEN as the dispersive particles was dispersed at diameters between 0.1 and 0.3 nm. The enrichment of PDMS in the copolymer surface could be responsible for an increase of surface water repellency (113.4°).

Dong, L. M.; Liao, G. X.; Liu, C.; Yang, S. S.; Jian, X. G.

289

21 CFR 172.824 - Sodium mono- and dimethyl naphthalene sulfonates.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Sodium mono- and dimethyl naphthalene sulfonates...Multipurpose Additives § 172.824 Sodium mono- and dimethyl naphthalene sulfonates. The food additive sodium mono- and dimethyl naphthalene...

2013-04-01

290

21 CFR 172.824 - Sodium mono- and dimethyl naphthalene sulfonates.  

Code of Federal Regulations, 2010 CFR

... Sodium mono- and dimethyl naphthalene sulfonates...additive sodium mono- and dimethyl naphthalene sulfonates...crystallization of sodium carbonate in an amount not to...Act: (1) Sodium carbonate produced in accordance...of sodium mono- and dimethyl naphthalene...

2009-04-01

291

40 CFR 721.10100 - Dialkyl dimethyl ammonium carbonate (2:1) (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Dialkyl dimethyl ammonium carbonate (2:1) (generic...721.10100 Dialkyl dimethyl ammonium carbonate (2:1) (generic...generically as dialkyl dimethyl ammonium carbonate (2:1) (PMN...

2013-07-01

292

21 CFR 172.824 - Sodium mono- and dimethyl naphthalene sulfonates.  

Code of Federal Regulations, 2010 CFR

... Sodium mono- and dimethyl naphthalene sulfonates...additive sodium mono- and dimethyl naphthalene sulfonates...crystallization of sodium carbonate in an amount not to...Act: (1) Sodium carbonate produced in accordance...of sodium mono- and dimethyl naphthalene...

2010-01-01

293

40 CFR 721.10100 - Dialkyl dimethyl ammonium carbonate (2:1) (generic).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Dialkyl dimethyl ammonium carbonate (2:1) (generic...721.10100 Dialkyl dimethyl ammonium carbonate (2:1) (generic...generically as dialkyl dimethyl ammonium carbonate (2:1) (PMN...

2009-07-01

294

40 CFR 721.10100 - Dialkyl dimethyl ammonium carbonate (2:1) (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Dialkyl dimethyl ammonium carbonate (2:1) (generic...721.10100 Dialkyl dimethyl ammonium carbonate (2:1) (generic...generically as dialkyl dimethyl ammonium carbonate (2:1) (PMN...

2010-07-01

295

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

296

Critical properties of fluorinated ethers  

SciTech Connect

Using a static-type apparatus, the authors measured the critical temperatures, pressures, and densities of seven fluorinated ethers: CF{sub 3}CHFOCHF{sub 2}, CF{sub 3}CF{sub 2}OCH{sub 3}, CF{sub 3}CH{sub 2}OCH{sub 3}, CF{sub 3}CF{sub 2}OCH{sub 2}CF{sub 3}, CF{sub 3}CF{sub 2}OCH{sub 2}CH{sub 3}, CF{sub 3}CF{sub 2}CF{sub 2}OCH{sub 3}, and (CF{sub 3}){sub 2}CFOCH{sub 3}. The advantage of the measuring apparatus was that a small amount of a sample was sufficient to determine the critical properties accurately. The uncertainties of the critical properties measured in this work were {+-}30 mK in temperature, {+-}2 kPa in pressure, and {+-}0.2% in density, respectively. The critical properties of the compounds were compared with those estimated by the Lydersen group contribution method.

Sako, T.; Sato, M.; Nakazawa, N.; Oowa, M. [National Inst. of Materials and Chemical Research, Tsukuba, Ibaraki (Japan). Dept. of Chemical Systems; Yasumoto, M.; Ito, H.; Yamashita, S. [Research Inst. of Innovative Technology for the Earth, Tokyo (Japan)

1996-07-01

297

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

298

Performance of plastic gear made of carbon fiber reinforced poly-ether-ether-ketone  

Microsoft Academic Search

A carbon fiber (CF) reinforced poly-ether-ether-ketone (PEEK) gear was prepared by injection molding, and its gear performance was evaluated. It was found that the wear process of the CF reinforced PEEK gear significantly varied depending on the test conditions, such as the kind of the partner gear combined and whether a lubricant exists on the engagement region or not. It

Masaya Kurokawa; Yoshitaka Uchiyama; Susumu Nagai

1999-01-01

299

Cross-linked poly (ether ether ketone) as a proton exchange membrane for fuel cell applications  

Microsoft Academic Search

Sulfonated poly (ether ether ketone) with pendant carboxylic acid groups was directly synthesized and used to prepare cross-linked polymer electrolyte membrane. The direct synthesis of the sulfonated polymer provided the opportunity to control the degree of sulfonation and the distribution of the sulfonic acid groups within the polymer. The pendant carboxylic acid groups were functionalized by unsaturated groups in order

Shuhua Zhou; Nguyenthi Que Chi; Dukjoon Kim

2010-01-01

300

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

301

Crystallinity and dielectric properties of PEEK, poly(ether ether ketone)  

Microsoft Academic Search

The dependence of specific dielectric properties of polymers on their fundamental molecular parameters was investigated as part of a study involving HV insulation in spacecraft systems. As part of an effort to understand the causes of dielectric breakdown, this investigation focused on the effect of polymer morphology on the electrical characteristics of a poly (ether ether ketone) (PEEK), a high

T. W. Giants

1994-01-01

302

Ethylene glycol monomethyl ether and propylene glycol monomethyl ether: metabolism, disposition, and subchronic inhalation toxicity studies  

Microsoft Academic Search

Short-term and subchronic vapor inhalation studies have shown that there are pronounced differences in the toxicological properties of ethylene glycol monomethyl ether (EGME) and propylene glycol monomethyl ether (PGME). Overexposure to EGME has resulted in adverse effects on testes, bone marrow and lymphoid tissues in laboratory animals. PGME does not affect these tissues, and instead, overexposure to PGME has been

R. R. Miller; E. A. Hermann; J. T. Young; T. D. Landry; L. L. Calhoun

1984-01-01

303

Conformations and Barriers to Methyl Group Internal Rotation in Two Asymmetric Ethers: Propyl Methyl Ether and Butyl Methyl Ether  

NASA Astrophysics Data System (ADS)

The conformational preferences of the O-C-C-C unit are important in many biological systems with the unit generally preferring a gauche configuration compared to an anti configuration. Butyl methyl ether and propyl methyl ether provide very simple systems for this phenomenom to manifest. Pure rotational spectra of the title molecules have been recorded using chirped pulse Fourier transform microwave spectroscopy (CP-FTMW). In the case of butyl methyl ether, only one conformer has been observed. This conformer has torsional angles of COCC = 180°, OCCC = 62° and CCCC = 180° (anti-gauche-anti) and rotational constants of A = 10259.4591(33) MHz, B = 1445.6470(13) MHz, and C = 1356.2944(14) MHz. The rotational spectrum was doubled and has been analyzed to produce an effective barrier to methyl group internal rotation of 780(35) cm-1. A prior rotational spectroscopic study on propyl methyl ether had focused only on the high energy anti-anti conformer. We have analyzed spectra from the lowest energy anti-gauche conformer and the spectroscopic constants will be presented. A summary of the differences in conformational energies and methyl group internal rotation barriers for the class of aliphatic asymmetric ethers will be presented. K. N. Houk, J. E. Eksterowicz, Y.-D. Wu, C. D. Fuglesang, D. B. Mitchell. J. Am. Chem. Soc. 115 (4170), 1993. Hiroshi Kato, Jun Nakagawa, Michiro Hayashi. J. Mol. Spectrosc. 80 (272), 1980.

Long, B. E.; Dechirico, F.; Cooke, S. A.

2012-06-01

304

Stereocontrolled Cyanohydrin Ether Synthesis through Chiral Brønsted Acid-Mediated Vinyl Ether Hydrocyanation.  

PubMed

Vinyl ethers can be protonated to generate oxocarbenium ions that react with Me3SiCN to form cyanohydrin alkyl ethers. Reactions that form racemic products proceed efficiently upon conversion of the vinyl ether to an ?-chloro ether prior to cyanide addition in a pathway that proceeds through Brønsted acid-mediated chloride ionization. Enantiomerically enriched products can be accessed by directly protonating the vinyl ether with a chiral Brønsted acid to form a chiral ion pair. Me3SiCN acts as the nucleophile and PhOH serves as a stoichiometric proton source in a rare example of asymmetric bimolecular nucleophilic addition into an oxocarbenium ion. Computational studies have provided a model for the interaction between the catalyst and the oxocarbenium ion. PMID:23968162

Lu, Chunliang; Su, Xiaoge; Floreancig, Paul E

2013-09-04

305

Synthesis of dimethyl carbonate from carbon dioxide: catalysis and mechanism  

Microsoft Academic Search

The turnover number of the catalytic production of dimethyl carbonate from CO2 and methanol is restricted by thermodynamics as well as catalyst decomposition. The catalytic efficiency is remarkably improved using an acetal as the starting material in methanol. The catalytic activity and selectivity also depend strongly on the CO2 pressure. A possible catalytic cycle involving transformation of CO2 to dimethyl

Toshiyasu Sakakura; Jun-Chul Choi; Yuko Saito; Takeshi Sako

2000-01-01

306

Dimethyl carbonate as a modern green reagent and solvent  

NASA Astrophysics Data System (ADS)

Published data on dimethyl carbonate as a safe reagent and solvent in organic synthesis are generalized and analyzed. The methods of dimethyl carbonate preparation and its use as methylating and carboxymethylating reagent are considered. The attention is focused on the environmentally safe processes corresponding to the green chemistry principles.

Aricò, F.; Tundo, Pietro

2010-08-01

307

Dimethyl sulphide as a foraging cue for Antarctic Procellariiform seabirds  

Microsoft Academic Search

MANY Procellariiform seabirds make their living flying over vast expanses of seemingly featureless ocean waters in search of food. The secret of their success is a mystery, but an ability to hunt by smell has long been suspected1-7. Here we present experimental evidence that Procellariiform seabirds can use a naturally occurring scented compound, dimethyl sulphide, as an orientation cue. Dimethyl

Gabrielle A. Nevitt; Richard R. Veit; Peter Kareiva

1995-01-01

308

Pemoline levels in brain: enhancement by dimethyl sulfoxide.  

PubMed

Pemoline-C(14) dissolved in dimethyl sulfoxide and injected intraperitoneally into rats was found in larger amounts in the brain than was a similar dose given in 0.3 percent tragacanth suspension. This appeared to be related to a partial breakdown of the blood-brain barrier in vivo by the dimethyl sulfoxide. PMID:6058689

Brink, J J; Stein, D G

1967-12-15

309

Ether and the atmospheric chemistry data assimilation  

NASA Astrophysics Data System (ADS)

The French atmospheric chemistry data base Ether has been developed and funded by the French Space Agency (CNES) and the Institut National des Sciences de l'Univers (INSU/CNRS) for about 6 years. The role of Ether is to assist French atmospheric researchers, European scientists, as long as they are involved in co-operation agreements with French scientists, to locate, access and interpret atmospheric data. This centre gathers data from satellite, balloon campaigns linked to satellite validation, aircraft and model results for stratospheric and tropospheric purposes and from different levels of production (raw data, physical data, interpolated or assimilated data). All Ether data are available on-line through a World Web interface (http://ether.ipsl.jussieu.fr). Software and added-value services are provided to assist in the manipulation of the data or to generate higher levels standard data products. Extensive information is also provided on the data collection procedures, formats, contact names and references to scientific papers. In addition to data support activities, a major goal of Ether is to promote the creation of different expertise networks on varying atmospheric chemistry topics. The first working group has been created on data assimilation. It consists in gathering expertises in different themes (satellites, assimilation techniques, modelling, real-time processing) in order to optimally develop a tool able to answer different scientific questions relative to the evolution of the Earth atmosphere in terms of chemistry and dynamics. Based on the PALM tool able to interconnect different codes, it will be able to process different satellite data using two atmospheric models and assimilation schemes within the French Ether data base. Ether will focus on the handling and on the development of added-value services of data for which the French community is directly or indirectly involved. For these projects Ether will provide all the data needed, and will retrieve and give access to assimilated data results and to assimilation tools. This expertise in both data handling and, above all, added-value services within Ether will be used in the European ASSET project in order to participate to a more global and virtual centre, gathering expertises in assimilation of different countries.

Ricaud, P.; Phulpin, T.; Girod, F.; Boonne, C.

310

Toxicokinetics of ethers used as fuel oxygenates.  

PubMed

The toxicokinetics and biotransformation of methyl-tert.butyl ether (MTBE), ethyl-tert.butyl ether (ETBE) and tert.amyl-methyl ether (TAME) in rats and humans are summarized. These ethers are used as gasoline additives in large amounts, and thus, a considerable potential for human exposure exists. After inhalation exposure MTBE, ETBE and TAME are rapidly taken up by both rats and humans; after termination of exposure, clearance by exhalation and biotransformation to urinary metabolites is rapid in rats. In humans, clearance by exhalation is slower in comparison to rats. Biotransformation of MTBE and ETBE is both qualitatively and quantitatively similar in humans and rats after inhalation exposure under identical conditions. The extent of biotransformation of TAME is also quantitatively similar in rats and humans; the metabolic pathways, however, are different. The results suggest that reactive and potentially toxic metabolites are not formed during biotransformation of these ethers and that toxic effects of these compounds initiated by covalent binding to cellular macromolecules are unlikely. PMID:11684356

Dekant, W; Bernauer, U; Rosner, E; Amberg, A

2001-10-15

311

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

312

An Immunoassay for Monitoring Environmental and Human Exposure to the Polybrominated Diphenyl Ether BDE-47  

PubMed Central

We developed a selective competitive enzyme-linked immunosorbent assay (ELISA) to monitor environmental and human exposure to polybrominated diphenyl ether BDE-47 that is used as a flame retardant. 2,2’,4,4’-Tetrabromodiphenyl ether (BDE-47) a dominant PBDE congener of toxicological concern, was the target analyte. To achieve effective hapten presentation on the carrier protein for antibody production, immunizing haptens with a rigid double-bonded hydrocarbon linker introduced at different positions on the target molecule were synthesized as well as coating haptens that mimic a characteristic fragment of the molecule. Rabbit antisera produced against each immunizing antigen were screened against competitive hapten coating antigens. Under optimized competitive indirect ELISA conditions, the linear detection range in the assay buffer that includes 50% dimethyl sulfoxide was 0.35 - 8.50 ?g/L with an IC50 value of 1.75 ?g/L for BDE-47. Little or no cross-reactivity (< 6%) was observed to related PBDE congeners containing the BDE-47 moiety and other halogenated compounds. Using a magnetic particle-based competitive direct ELISA increased the sensitivity by 10-fold over the indirect ELISA. The ELISA provided quantitative results when performed on small volume/weight samples such as dust, furniture foam, and blood/serum following sample preparation, suggesting a convenient screening tool.

Ahn, Ki Chang; Gee, Shirley J.; Tsai, Hsing-Ju; Bennett, Deborah; Nishioka, Marcia G.; Blum, Arlene; Fishman, Elana; Hammock, Bruce D.

2012-01-01

313

Solubility behavior of ethyl cellulose in supercritical fluid solvents  

Microsoft Academic Search

Solubility data to 180°C and 1200 bar are reported for ?1.0 wt.% ethyl cellulose (50% ethoxyl content, 2.5 average degree of substitution) (EC) in neat supercritical fluid (SCF) chlorodifluoromethane (F22); difluoromethane; 1-chloro-1,1-difluoroethane; 1,1-difluoroethane; and dimethyl ether (DME). The pressures needed to dissolve EC in the polar fluorocarbons decreases with increasing solvent size. The exception in this trend is F22 which

Dan Li; Mark A. McHugh

2004-01-01

314

Experimental results from a microdot detector overcoated with a semiconducting layer  

NASA Astrophysics Data System (ADS)

A Microdot (MDOT) detector has been overcoated with a boron-doped amorphous silicon carbide semiconductive layer. The stable operation of the device in mixtures of argon, neon and helium with di-methyl ether (DME) at high gains and at high counting rates is shown. Radiation damage tests give a lifetime of over 120mC/cm using a gas system with plastic gas pipes.

Biagi, S. F.; Duxbury, D.; Gabathuler, E.

1998-12-01

315

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

316

Fluorocarbon Ether Bis(o-Aminophenol) Compounds.  

National Technical Information Service (NTIS)

The patent application describes two compounds: 1,14-bis(3-amino-4-hydroxyphenyl)-perfluoro-5,10-dimethyl-3,6,9,12- tetraoxatetradecane and 1,17-bis(3-amino-4-hydroxyphenyl)perfluoro-3,6,9,15- tetraoxaheptadecane. The compounds are useful as monomers in s...

R. C. Evers

1975-01-01

317

Fluorocarbon Ether Bis(O-Aminophenol) Compounds.  

National Technical Information Service (NTIS)

As new compositions of matter, 1,14-bis(3-amino-4-hydroxyphenyl)perfluoro-5, 10-dimethyl-3,6,9,12-tetraoxatetradecane and 1,17-bis(3-amino-4-hydroxyphenyl)perfluoro-3,6,9,15- tetraoxaheptadecane. The compounds are useful as monomers in synthesizing perflu...

R. C. Evers

1977-01-01

318

Radiation-induced transformations of cellulose ethers  

SciTech Connect

The purpose of this investigation was to study the transformation which take place under the action of ..gamma..-radiation in a number of cellulose ethers containing both saturated (carboxymethyl, hydroxyethyl) and unsaturated (allyl, methacryloyl) groups. Irradiation was carried out on a /sup 60/Co unit in air at 77 and 300 K; the dose rate was 37 and 50 kGy/h respectively. The EPR spectra of ..gamma..-irradiated hydroxyethyl- and allylhydroxyethylcelluloses are identical. Under the action of ..gamma..-radiation extensive changes took place in cellulose ethers which are exhibited in degradation or the formation of three-dimensional structures and are accompanied by a change in the functional composition. The efficiency in the formation of radicals and their localization are determined by the nature and number of substituents in the cellulose ethers.

Nud'ga, L.A.; Petropavlovskii, G.S.; Plisko, E.A.; Isakova, O.V.; Ershov, B.G.

1988-02-10

319

Bis[?-N-(tert-butyl-dimethyl-silyl)-N-(pyridin-2-ylmeth-yl)amido]-bis-[methyl-cobalt(II)  

PubMed Central

The green title complex, [Co2(CH3)2(C12H21N2Si)2], was obtained from bis­{[?-N-tert-butyl­dimethyl­silyl-N-(pyridin-2-ylmeth­yl)amido]­chloridocobalt(II)} and methyl­lithium in diethyl ether at 195?K via a metathesis reaction. The dimeric cobalt(II) complex exhibits a crystallographic center of inversion in the middle of the Co2N2 ring (average Co—N = 2.050?Å). The CoII atom shows a distorted tetra­hedral coordination sphere. The exocyclic Co—N bond length to the pyridyl group shows a similar value of 2.045?(4)?Å. The exocyclic methyl group has a rather long Co—C bond length of 2.019?(5)?Å.

Malassa, Astrid; Agthe, Christine; Gorls, Helmar; Westerhausen, Matthias

2012-01-01

320

Interactions and binding energies of dimethyl methylphosphonate and dimethyl chlorophosphate with amorphous silica.  

PubMed

The fundamental interactions of dimethyl methylphosphonate (DMMP) and dimethyl chlorophosphate (DMCP) on amorphous silica nanoparticles have been investigated with transmission infrared spectroscopy and temperature-programmed desorption (TPD). DMMP and DMCP both adsorb molecularly to silica through the formation of hydrogen bonds between isolated silanols and the phosphoryl oxygen of the adsorbate. The magnitude of the shift of the ?(OH) mode upon simulant adsorption is correlated to the adsorption strength. The activation energies for desorption for a single DMMP or DMCP molecule from amorphous silica varied with coverage. In the limit of zero coverage, after the effects of defects were excluded, the activation energies were 54.5 ± 0.3 and 48.4 ± 1.0 kJ/mol for DMMP and DMCP, respectively. PMID:22780431

Wilmsmeyer, Amanda R; Uzarski, Joshua; Barrie, Patrick J; Morris, John R

2012-07-20

321

Inhalation anaesthesia: from diethyl ether to xenon.  

PubMed

Modern anaesthesia is said to have began with the successful demonstration of ether anaesthesia by William Morton in October 1846, even though anaesthesia with nitrous oxide had been used in dentistry 2 years before. Anaesthesia with ether, nitrous oxide and chloroform (introduced in 1847) rapidly became commonplace for surgery. Of these, only nitrous oxide remains in use today. All modern volatile anaesthetics, with the exception of halothane (a fluorinated alkane), are halogenated methyl ethyl ethers. Methyl ethyl ethers are more potent, stable and better anaesthetics than diethyl ethers. They all cause myocardial depression, most markedly halothane, while isoflurane and sevoflurane cause minimal cardiovascular depression. The halogenated ethers also depress the normal respiratory response to carbon dioxide and to hypoxia. Other adverse effects include hepatic and renal damage. Hepatitis occurs most frequently with halothane, although rare cases have been reported with the other agents. Liver damage is not caused by the anaesthetics themselves, but by reactive metabolites. Type I hepatitis occurs fairly commonly and takes the form of a minor disturbance of liver enzymes, which usually resolves without treatment. Type II, thought to be immune-mediated, is rare, unpredictable and results in a severe fulminant hepatitis with a high mortality. Renal damage is rare, and was most often associated with methoxyflurane because of excessive plasma fluoride concentrations resulting from its metabolism. Methoxyflurane was withdrawn from the market because of the high incidence of nephrotoxicity. Among the contemporary anaesthetics, the highest fluoride concentrations have been reported with sevoflurane, but there are no reports of renal dysfunction associated with its use. Recently there has been a renewed interest in xenon, one of the noble gases. Xenon has many of the properties of an ideal anaesthetic. The major factor limiting its more widespread is the high cost, about 2,000 times the cost of nitrous oxide. PMID:18175089

Bovill, J G

2008-01-01

322

Dissolution of calcium bilirubinate and calcium carbonate debris remaining after methyl tert-butyl ether dissolution of cholesterol gallstones.  

PubMed

Methyl tert-butyl ether rapidly dissolves cholesterol gallstones, although insoluble debris may remain. Total gallstone dissolution could be achieved if safe solvents for these noncholesterol components can be developed. We evaluated the in vitro ability of ethylenediaminetetraacetic acid, citrate, dimethyl sulfoxide, and ionic or nonionic detergents to dissolve the predominantly calcium bilirubinate and calcium carbonate debris remaining after methyl tert-butyl ether gallstone dissolution. Ethylenediaminetetraacetic acid 1% or 2% at pH 9.5 was the most effective of the solvents studied for dissolving calcium and bile pigment. The addition of cholate (25-200 mM) or polysorbate (1%-10%) to ethylenediaminetetraacetic acid 1% at pH 9.5 enhanced pigment dissolution compared to ethylenediaminetetraacetic acid alone. Dissolution of pellets prepared from human gallstones and composed predominantly of either calcium bilirubinate or calcium carbonate was 80% and 85% at 4 h using ethylenediaminetetraacetic acid 1% plus polysorbate-20 1% at pH 9.5. We conclude that ethylenediaminetetraacetic acid, either alone or with a detergent, is an effective solvent for methyl tert-butyl ether-insoluble gallstone debris and deserves assessment in vivo. PMID:2323524

Nelson, P E; Moyer, T P; Thistle, J L

1990-05-01

323

Syntheses of Diazadithiacrown Ethers Containing Two 8-Hydroxyquinoline Side Arms.  

National Technical Information Service (NTIS)

Ten new diazadithiacrown ethers containing two 8-hydroxyquinoline (HQ) sidearms attached through the HQ 7-positions and four new diazadithiacrown ethers containing two HQ sidearms attached through the HQ 2-positions have been prepared. Some of these new l...

H. C. Song J. S. Bradshaw Y. W. Chen G. P. Xue J. A. Chiara

2001-01-01

324

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

325

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

326

Synthesis of Tetraazacrown Ethers Containing Two 8-Hydroxyquinoline Side Arms.  

National Technical Information Service (NTIS)

Four new tetraazacrown ethers containing two 8-hydroxyquinoline side arms were prepared first by reductive amination of 8-acetoxyquinolin-2-carbaldehyde with the appropriate tetraazacrown ether containing two microring NH functions. The resulting bis(8-ac...

Z. Yang J. S. Bradshaw P. B. Savage K. E. Krakowiak R. M. Izatt

1999-01-01

327

21 CFR 520.1846 - Polyoxyethylene (23) lauryl ether blocks.  

Code of Federal Regulations, 2013 CFR

...ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1846 Polyoxyethylene (23) lauryl ether blocks. (a) Specifications. Each molasses-based block contains 2.2 percent polyoxyethylene (23) lauryl ether. (b) Sponsor. See No. 067949 in §...

2013-04-01

328

Nonequivalence of ether theories and special relativity  

NASA Astrophysics Data System (ADS)

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 contact with a rotating disk. This procedure makes it possible, in principle, to measure the one-way velocity of light and to test the theories. First-order experiments confirm special relativity and rule out the ether theory.

Spavieri, G.

1986-09-01

329

Signalling steps in apoptosis by ether lipids  

Microsoft Academic Search

We have investigated the mechanisms of induction of apoptosis by the antineoplastic ether lipid ET-18-OCH3 (ALP) in sensitive S49wt mouse lymphoma cells and ALP-resistant S49ar variants, both with wild-type p53, and in related L1210 cells with mutated p53. Ether lipid-resistant S49ar cells were cross-resistant to extracellular stress factors (cold shock, heat shock, H2O2, dimethylsulfoxide) and to radiation-induced apoptosis but not

L. A. Smets; H. Van Rooij; G. S. Salomons

1999-01-01

330

Synthesis of Alkynyl Ethers and Low Temperature Sigmatropic Rearrangement of Allyl and Benzyl Alkynyl Ethers  

PubMed Central

?–Alkoxy ketones 3 can be transformed into 1-alkynyl ethers 5 by a two-step procedure involving formation of the enol triflate or phosphate and base-induced elimination. Performing the same reaction sequence with allylic alcohols (R2OH, R2 = allyl) furnishes instead ?,?-unsaturated carboxylic acid derivatives 6, derived from [3,3]-sigmatropic rearrangement of the intermediate allyl alkynyl ethers at ?78 °C and trapping of the subsequently formed ketene with nucleophiles (Nu-H). Benzyl alkynyl ether 5 (R2 = benzyl) rearranges to indanone 7 upon heating to 60 °C.

Sosa, Juan R.; Tudjarian, Armen A.; Minehan, Thomas G.

2009-01-01

331

The ether lipid-deficient mouse: Tracking down plasmalogen functions  

Microsoft Academic Search

Chemical and physico-chemical properties as well as physiological functions of major mammalian ether-linked glycerolipids, including plasmalogens were reviewed. Their chemical structures were described and their effect on membrane fluidity and membrane fusion discussed. The recent generation of mouse models with ether lipid deficiency offered the possibility to study ether lipid and particularly plasmalogen functions in vivo. Ether lipid-deficient mice revealed

Karin Gorgas; Andre Teigler; Dorde Komljenovic; Wilhelm W. Just

2006-01-01

332

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

333

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

334

Glycol ether\\/siloxane polymer penetrating and lubricating composition  

Microsoft Academic Search

A penetrating and lubricating composition consists of a silicone lubricant dissolved in a glycol ether carrier having a very low surface tension. The glycol ether gives the composition the ability to penetrate into the cracks between two seized or corroded elements and dissolve any rust or corrosion present. The glycol ether then volitalizes leaving a coating of silicone on the

MacIntosh

1981-01-01

335

Zirconium phosphate sulfonated poly (fluorinated arylene ether)s composite membranes for PEMFCs at 100–140 °C  

Microsoft Academic Search

Organic–inorganic hybrid composite membranes have been prepared and evaluated for polymer electrolyte membrane fuel cells (PEMFCs) at 100–140°C. A series of synthesized poly (fluorinated arylene ether)s was sulfonated by fuming sulfuric acid (20% SO3). The zirconium phosphate composite membrane was prepared by soaking the sulfonated poly (fluorinated arylene ether)s stepwise in 1M zirconyl chloride solution and 1M phosphoric acid solution.

Myung Heui Woo; Ohdeok Kwon; Sung Ho Choi; Ming Zi Hong; Hyung-Wook Ha; Keon Kim

2006-01-01

336

Metabolism of Ether Oxygenates Added to Gasoline.  

National Technical Information Service (NTIS)

The Clean Air Act Amendments of 1990 required use of oxygenated fuels in areas that exceeded the National Ambient Air Quality Standards for carbon monoxide and in areas with very high ozone levels. Adding oxygenates, such as MTBE (methyl tert-butyl ether)...

J. Hong Y. Wang S. N. Mohr F. Y. Bondoc C. Deng W. Dekant U. Bernauer E. Rosner A. Amberg J. M. Benson E. B. Barr J. R. Krone

2001-01-01

337

Orphan enzymes in ether lipid metabolism.  

PubMed

Ether lipids are an emerging class of lipids which have so far not been investigated and understood in every detail. They have important roles as membrane components of e.g. lens, brain and testis, and as mediators such as platelet-activating factor. The metabolic enzymes for biosynthesis and degradation have been investigated to some extent. As most involved enzymes are integral membrane proteins they are tricky to handle in biochemical protocols. The sequence of some ether lipid metabolising enzymes has only recently been reported and other sequences still remain obscure. Defined enzymes without assigned sequence are known as orphan enzymes. One of these enzymes with uncharacterised sequence is plasmanylethanolamine desaturase, a key enzyme for the biosynthesis of one of the most abundant phospholipids in our body, the plasmalogens. This review aims to briefly summarise known functions of ether lipids, give an overview on their metabolism including the most prominent members, platelet-activating factor and the plasmalogens. A special focus is set on the description of orphan enzymes in ether lipid metabolism and on the successful strategies how four previous orphans have recently been assigned a sequence. Only one of these four was characterised by classical protein purification and sequencing, whereas the other three required alternative strategies such as bioinformatic candidate gene selection and recombinant expression or development of an inhibitor and multidimensional metabolic profiling. PMID:22771767

Watschinger, Katrin; Werner, Ernst R

2012-07-04

338

Metal ion complexation by ionizable crown ethers  

SciTech Connect

During the report period a variety of new lipophilic ionizable crown ethers with pendent proton-ionizable groups has been synthesized. In addition a series of proton-ionizable crown ethers without lipophilic groups was prepared to study how structural variations within the ligand influence metal ion complexation in homogeneous media as assessed by NMR spectroscopy or titration calorimetry. A third class of new metal ion-complexing agents is a series of lipophilic acyclic polyether dicarboxylic acids. Competitive solvent extractions of alkali metal and alkaline earth cations and of the mixed species have been conducted to reveal the influence of ring size, nature and attachment site of the lipophilic group, sidearm length, and proton-ionizable group identity and location upon the selectivity and efficiency of metal ion complexation. In addition to such studies of structural variation within the lipophilic proton-ionizable crown ether, the effect of changing the organic solvent and variation of the stripping conditions have been assessed. The ability of proton- ionizable crown ethers to function as selective metal ion carriers in liquid membrane transport processes has been examined in both bulk liquid membrane and polymer-supported liquid membrane transport systems. New acyclic and cyclic polyether carboxylic acid resins have been prepared by condensation polymerization and characterized.

Bartsch, R.A.

1990-06-01

339

Orphan enzymes in ether lipid metabolism  

PubMed Central

Ether lipids are an emerging class of lipids which have so far not been investigated and understood in every detail. They have important roles as membrane components of e.g. lens, brain and testis, and as mediators such as platelet-activating factor. The metabolic enzymes for biosynthesis and degradation have been investigated to some extent. As most involved enzymes are integral membrane proteins they are tricky to handle in biochemical protocols. The sequence of some ether lipid metabolising enzymes has only recently been reported and other sequences still remain obscure. Defined enzymes without assigned sequence are known as orphan enzymes. One of these enzymes with uncharacterised sequence is plasmanylethanolamine desaturase, a key enzyme for the biosynthesis of one of the most abundant phospholipids in our body, the plasmalogens. This review aims to briefly summarise known functions of ether lipids, give an overview on their metabolism including the most prominent members, platelet-activating factor and the plasmalogens. A special focus is set on the description of orphan enzymes in ether lipid metabolism and on the successful strategies how four previous orphans have recently been assigned a sequence. Only one of these four was characterised by classical protein purification and sequencing, whereas the other three required alternative strategies such as bioinformatic candidate gene selection and recombinant expression or development of an inhibitor and multidimensional metabolic profiling.

Watschinger, Katrin; Werner, Ernst R.

2013-01-01

340

Production of molding materials containing polyphenylene ethers  

US Patent & Trademark Office Database

Molding materials containing high molecular weight polyphenylene ethers are produced by a process in which a solution of a polyphenylene ether in an organic solvent, together with another polymer, is freed of solvent by multi-stage evaporation. The solvent is preferably an aromatic compound from the class comprising the hydrocarbons, halohydrocarbons, ethers or esters, the ratio of the other polymer to the polyphenylene ether is advantageously from 99:1 to 20:80 parts by weight, the other polymer is, in particular, a homopolymer or copolymer of styrene or of a homolog thereof, which may be modified with rubber, and the multi-stage evaporation process preferably comprises not less than two and not more than four working up stages. The evaporation is carried out in general at from 120.degree. to 280.degree. C. and under a pressure of from 1 to 3,000 mbar, advantageously in the presence of assistants which reduce the partial pressure, eg. water and/or methanol.

1984-03-13

341

Limonene ethers from tire pyrolysis oil  

Microsoft Academic Search

Tire pyrolysis oil was produced by EnerVision Inc., Halifax, Canada using the continuous ablative reactor (CAR) system. The tire oil was separated by distillation into several fractions. Naphtha and limonene enriched naphtha were reacted with methanol over different catalysts. Batch experiments were carried out to separate limonene as methyl limonene ethers.Whole tire pyrolysis oil was distilled and the resulting distillates

Maria Stanciulescu; Michio Ikura

2006-01-01

342

EXPOSURE OF AMERICANS TO POLYBROMINATED DIPENYL ETHERS  

EPA Science Inventory

Polybrominated diphenyl ethers, or PBDEs, are a class of brominated flame retardants that, like other persistent organic pollutants (POPs), have been found in humans, wildlife, and biota worldwide. Unlike other POPs, however, the key routes of human exposure are not thought to b...

343

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

344

Fluoroalkylation of aryl ether perfluorocyclobutyl polymers  

Microsoft Academic Search

Post functionalizaion of aryl ether perfluorocyclobutyl (PFCB) polymers with fluoroalkyl side chains was accomplished with Umemoto's FITS reagents. The fluoroalkylated PFCB polymers (20 % functionalized) showed increases in both hydrophobicity and oleophobicity. Static contact angle for hexadecane was increased after fluoroalkylation from 0o to greater than 30o for both PFCB polymers. Increased oil repellency makes these materials potential candidates for

S. Clark Ligon; Bruno Amedurib; Dennis W. Smith

345

"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

346

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

347

Elastic electron scattering by ethyl vinyl ether  

SciTech Connect

We report measured and calculated results for elastic scattering of low-energy electrons by ethyl vinyl ether (ethoxyethene), a prototype system for studying indirect dissociative attachment processes that may play a role in DNA damage. The integral cross section displays the expected {pi}{sup *} shape resonance. The agreement between the calculated and measured cross sections is generally good.

Khakoo, M. A.; Hong, L.; Kim, B.; Winstead, C.; McKoy, V. [Department of Physics, California State University, Fullerton, California 92834 (United States); Troy High School, 2200 Dorothy Lane, Fullerton, California 92831 (United States); A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125 (United States)

2010-02-15

348

Sulfonated Poly (Ether Ether Ketone)Based Composite Proton-Exchange Membrane for Energy Production  

Microsoft Academic Search

The preparation of a proton-conducting membrane from Sulponated Poly Ether Ether Ketone (SPEEK), tungsto phosphoric acid (TPA), and inorganic fillers such as titanium dioxide (TiO2), silicon dioxide (SiO2), and zirconium dioxide (ZrO2) was prepared and the electrochemical and mechanical properties were investigated with regards to its application in energy production. The role of tungsto phosphoric acid is to minimize water

S. Seetharaman; G. Sozhan; S. Ravichandran; S. Vasudevan; J. Davidson

2011-01-01

349

Performance of plastic gear made of carbon fiber reinforced poly-ether-ether-ketone: Part 2  

Microsoft Academic Search

Five kinds of PEEK\\/CF composites, made by blending poly-ether-ether-ketone (PEEK) with three kinds of PAN type carbon fibers (CFs) and two kinds of pitch type CFs respectively, were injection-molded into gears. Their gear performance such as the load capability and the wear of tooth were evaluated. The wear properties of PEEK\\/CF gears extremely varied depending on the kinds of CFs,

Masaya Kurokawa; Yoshitaka Uchiyama; Susumu Nagai

2000-01-01

350

Gas transport in bisphenol A poly(ether ether ketone ketone) membrane  

Microsoft Academic Search

A homogeneous dense membrane of bisphenol A poly(ether ether ketone ketone) (PEEKK) has been prepared by a solution casting technique with chloroform as solvent and characterized by wide-angle X-ray diffraction and tensile tester. Permeating characteristics of five pure gases through the membrane has been described systematically. The permeability, diffusivity, solubility, and their selectivities of oxygen, nitrogen, carbon dioxide, methane, and

Xin-Gui Li; Mei-Rong Huang; Ingo Kresse; Jürgen Springer

2001-01-01

351

Development of Sulfonated Poly(ether-ether ketone)s for PEMFC and DMFC  

Microsoft Academic Search

\\u000a During the last two decades, extensive efforts have been made to develop alternative hydrocarbon-based polymer electrolyte\\u000a membranes to overcome the drawbacks of the current widely used perfluorosulfonic acid Nafion. This chapter presents an overview\\u000a of the synthesis, chemical properties, and polymer electrolyte fuel cell applications of new proton-conducting polymer electrolyte\\u000a membranes based on sulfonated poly(arylene ether ether ketone) polymers and

Dae Sik Kim; Michael D. Guiver

352

Ultrafiltration of kiwifruit juice using modified poly(ether ether ketone) hollow fibre membranes  

Microsoft Academic Search

Modified poly(ether ether ketone) (PEEKWC) hollow fibre (HF) membranes were prepared via the dry–wet spinning technique through the phase inversion process. The membranes were characterised by scanning electron microscopy (SEM), pure water permeability (Lp0) and dextran rejection (R%). On the basis of the obtained results, HF membranes were selected and tested for the clarification of kiwifruit juice.The effect of transmembrane

F. Tasselli; A. Cassano; E. Drioli

2007-01-01

353

On the cumulative fatigue damage in short carbon fiber reinforced poly-ether-ether-ketone  

Microsoft Academic Search

The actual load for mechanical structures is not always a constant stress amplitude. Therefore, in order to predict the fatigue life under various stress amplitudes, it is important to investigate whether Miner's rule is applicable or not. In this paper, rotating-bending fatigue tests under two-step loading for short carbon fiber reinforced poly-ether-ether-ketone, CFRPEEK, were carried out in order to investigate

Hiroshi Noguchi; Yun-Hae Kim; Hironobu Nisitani

1995-01-01

354

Process for making propenyl ethers and photopolymerizable compositions containing them  

DOEpatents

Propenyl ether monomers of formula A(OCH{double_bond}CHCH{sub 3}){sub n} (V) 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 formula V 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.

1996-01-23

355

Process for making propenyl ethers and photopolymerizable compositions containing them  

DOEpatents

Propenyl ether monomers of formula V A(OCH.dbd.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 formula V 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, James V. (Clifton Park, NY)

1996-01-01

356

Internal motions in a complex consisting of a rare gas atom and a C2v molecule: Theoretical formulations and their applications to Fourier transform microwave spectra of Ne-dimethyl ether and Ar-dimethyl ether  

Microsoft Academic Search

The internal motion of the rare gas atom, i.e., the relative motion of the two constituents, in a complex shown in the title was discussed by paying special attention to its effect on the rotational motion of the complex in order to extract as much precise information on this motion as possible from the observed rotational spectra. We have set

Yasumasa Morita; Nobukimi Ohashi; Yoshiyuki Kawashima; Eizi Hirota

2006-01-01

357

Characterization of Poly(Dimethyl Siloxane)-Polycarbonate Block Copolymers.  

National Technical Information Service (NTIS)

Shear modulus-temperature curves and swelling behavior of poly(dimethyl siloxane)-bisphenol-A polycarbonate block copolymers were studied. Two glass transitions corresponding to the silicone and polycarbonate phases are found. The dependence of one phase ...

M. Narkis A. V. Tobolsky

1969-01-01

358

Solubility of 2,3-dimethyl-2,3-dinitrobutane  

Microsoft Academic Search

The solubility of 2,3-dimethyl-2,3-dinitrobutane (DMNB) in acetone, acetonitrile, benzene, cyclohexanone, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, 2-ethoxyethanol, ethyl acetate, hexane, methanol, methyl ethyl ketone, tetrahydrofuran, toluene, and water at 5, 15, 25, and 35 C has been determined. The concentration of DMNB was measured by capillary gas chromatography with electron capture detection. The relative standard deviation of the measurements was between about

Marek E. Krzymien

1993-01-01

359

Solubility of 2,3-dimethyl-2,3-dinitrobutane  

SciTech Connect

The solubility of 2,3-dimethyl-2,3-dinitrobutane (DMNB) in acetone, acetonitrile, benzene, cyclohexanone, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, 2-ethoxyethanol, ethyl acetate, hexane, methanol, methyl ethyl ketone, tetrahydrofuran, toluene, and water at 5, 15, 25, and 35 C has been determined. The concentration of DMNB was measured by capillary gas chromatography with electron capture detection. The relative standard deviation of the measurements was between about 1% and 7%.

Krzymien, M.E. (National Research Council, Ottawa, Ontario (Canada))

1993-04-01

360

Synthesis and Properties of Copolymers of Poly(ether ketone ketone) and Poly(ether ether ketone ketone) Containing Naphthalene Moieties and Pendant Cyano Groups  

Microsoft Academic Search

A new monomer containing naphthalene, 2,6-bis(? -naphthoxy)benzonitrile (BNOBN) was synthesized by reaction of ? -naphthol with 2,6-difluorobenzonitrile in N-methyl-2-pyrrolidone (NMP) in the presence of KOH and K 2CO3. Novel copolymers of poly(ether ketone ketone) and poly(ether ether ketone ketone) containing naphthalene moieties and pendant cyano groups were prepared by electrophilic Friedel—Crafts solution copolycondensation of terephthaloyl chloride (TPC) with varying mole

Mingzhong cai; Qin Xi; Nengwen Ding; Caisheng Song

2010-01-01

361

Synthesis and characterization of new poly(aryl ether)s containing alternate emitting and electron transporting chromophores  

Microsoft Academic Search

Three poly(aryl ether)s consisting of alternate isolated blue chromophore (substituted p-aryl vinylene) and electron transport structure (1,3,4-oxadiazole) have been synthesized and characterized. The poly(aryl ether)s (?red>0.5dl\\/g) were obtained by nucleophilic displacement reaction of oxadiazole-activated bis(fluoride) monomers with bis(phenol) monomers. Introduction of ether linkages results in enhanced solubility in organic solvent such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and Pyridine. The polymers

Shiao-Wen Hwang; Yun Chen

2000-01-01

362

OXIDATION OF METHYL FLUORIDE AND DIMETHYL ETHER BY AMMONIA MONOOXYGENASE IN NITROSOMONAS EUROPAEA. (R825689C009)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

363

Dimethyl carbonate production for fuel additives  

SciTech Connect

We have taken note of the transesterification reaction as a highly safe process of dimethyl carbonate (DMC) production for fuel additives. The reaction proceeds under the low corrosiveness and in the relatively mild condition. We have aimed to use an inorganic solid catalyst for this process. The inorganic solid catalyst is thermally stable and can be used in the large-scale fixed bed reactors without a catalyst separation unit. Through the transesterification of ethylene carbonate (EG) with methanol, DMC and ethylene glycol (EG) are co-generated as the products. EG is one of the bulk chemicals produced in the large scale plant comparable to one for the fuel additives. The market balance is important in the coproduction process. On the assumption that the amount of the co-production meets the market balance, the coproduction of DMC and EG is commercially viable. If we can control the amount of the EG coproduction in this process, it makes the process more flexible in the commercial production. Accordingly we have proposed a conceptual process scheme to control the amount of the EG coproduction. In this symposium, the inorganic solid catalyst system applying to the transesterification process and the conceptual process scheme how to control the amount of co-product will be discussed.

Okada, Y.; Kondo, T.; Asaoka, S. [Chiyoda Corp., Yokohama (Japan)

1996-12-31

364

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.

Lavis, Luke D.; Chao, Tzu-Yuan

2011-01-01

365

Dimethyl sulfoxide and dimethyl formamide increase lifespan of C. elegans in liquid.  

PubMed

Lifespan extension through pharmacological intervention may provide valuable tools to understanding the mechanisms of aging and could uncover new therapeutic approaches for the treatment of age-related disease. Although the nematode Caenorhabditis elegans is well known as a particularly suitable model for genetic manipulations, it has been recently used in a number of pharmacological studies searching for compounds with anti-aging activity. These compound screens are regularly performed in amphipathic solvents like dimethyl sulfoxide (DMSO), the solvent of choice for high-throughput drug screening experiments performed throughout the world. In this work, we report that exposing C. elegans to DMSO in liquid extends lifespan up to 20%. Interestingly, another popular amphipathic solvent, dimethyl formamide (DMF), produces a robust 50% increase in lifespan. These compounds work through a mechanism independent of insulin-like signaling and dietary restriction (DR). Additionally, the mechanism does not involve an increased resistance to free radicals or heat shock suggesting that stress resistance does not play a major role in the lifespan extension elicited by these compounds. Interestingly, we found that DMSO and DMF are able to decrease the paralysis associated with amyloid-?3-42 aggregation, suggesting a role of protein homeostasis for the mechanism elicited by these molecules to increase lifespan. PMID:23313473

Frankowski, Harald; Alavez, Silvestre; Spilman, Patricia; Mark, Karla A; Nelson, Joel D; Mollahan, Pamela; Rao, Rammohan V; Chen, Sylvia F; Lithgow, Gordon J; Ellerby, H Michael

2013-01-11

366

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

367

Oxidation of dimethyl sulfide to dimethyl sulfoxide by phototrophic purple bacteria  

SciTech Connect

Enrichment cultures of phototrophic purple bacteria rapidly oxidized up to 10 mM dimethyl sulfide (DMS) to dimethyl sulfoxide (DMSO). DMSO was qualitatively identified by proton nuclear magnetic resonance. By using a biological assay, DMSO was always quantitatively recovered from the culture media. DMS oxidation was not detected in cultures incubated in the dark, and it was slow in cultures exposed to full daylight. Under optimal conditions, the second-order rate constant for DMS oxidation was 6 day/sup -1/ mg of protein/sup -1/ ml/sup -1/. The rate constant was reduced in the presence of high concentration of sulfide (>1 mM), but was not affected by the addition of acetate. DMS was also oxidized to DMSO by a pure strain (tentatively identified as a Thiocystis sp.) isolated from the enrichment cultures. DMS supported growth of the enrichment cultures and of the pure strain by serving as an electron source for photosynthesis. A determination of the amount of protein produced in the cultures and an estimation of the electron balance suggested that the two electrons liberated during the oxidation of DMS to DMSO were quantitatively used to reduce carbon dioxide to biomass. The oxidation of DMS by phototrophic purple bacteria may be an important source of DMSO detected in anaerobic ponds and marshes.

Zeyer, J.; Eicher, P.; Wakeham, S.G.; Schwarzenbach, R.P.

1987-09-01

368

On the radiation resistance of crown ethers  

Microsoft Academic Search

The yields of hydrogen and ethylene from the radiolysis of 15-crown-5, 18-crown-6, dibenzo-18-crown-6, and dicyclohexyl-18-crown-6 ethers have been measured. The quantities obtained are compared with the ones for PEG-300, PEG-600 and 1,4-dioxane measured under the same conditions. The hydrogen yields range from about 1 to nearly 2 molecules per 100 eV and these of ethylene range from 0.02 to 0.15

S. V. Zatonsky; O. S. Povolotskaya

1987-01-01

369

Metal ion complexation by ionizable crown ethers  

SciTech Connect

Since the last informal progress report, research has been focused upon the synthesis and characterization of novel ionizable multidentate ligands and their application in competitive solvent extraction and liquid membrane transport of alkali metal cations and alkaline earth cations. During the report period, considerable attention has been devoted to obtaining a better understanding of the factors which influence the efficiencies and selectivities of alkali metal cation solvent extraction by lipophilic crown ether carboxylic acids.

Bartsch, R.A.

1986-07-15

370

Fluoroalkylation of aryl ether perfluorocyclobutyl polymers  

Microsoft Academic Search

Post functionalization of aryl ether perfluorocyclobutyl (PFCB) polymers with fluoroalkyl side chains\\u000a was accomplished with Umemoto’s FITS reagents. The fluoroalkylated PFCB polymers (20 % functionalized)\\u000a showed increases in both hydrophobicity and oleophobicity. Static contact angle for hexadecane was increased\\u000a after fluoroalkylation from 0o to greater than 30o\\u000a for the two PFCB polymers tested. Increased oil repellency makes these materials potential

S. Clark Ligon; Bruno Ameduri; Bernard Boutevin; Dennis W. Smith

2008-01-01

371

Solvent effect on the complex formation of a crown ether derivative with sodium and potassium ions. Thermodynamic background of selectivity  

NASA Astrophysics Data System (ADS)

The complexation properties of dimethyl-pyridino-18-crown-6 ether (M2P18C6) with Na+ and K+ in different primary alcohols including methanol (MeOH), ethanol (EtOH) and n-propanol (n-PrOH) were investigated by UV-vis spectroscopy. Stability constants and thermodynamic parameters have been determined applying the van't Hoff theory. In the cases of both Na+ and K+ the stability constants increase with decreasing permittivity of the solvent used. M2P18C6 always exhibits better affinity to K+ in each alcoholic solution compared to Na+. Thermodynamic studies suggest that in both cases there is a correlation between the permittivity of the solvent and the enthalpy and entropy change of complex formation.

Li, Yin; Huszthy, Péter; Móczár, Ildikó; Szemenyei, Balázs; Kunsági-Máté, Sándor

2013-01-01

372

Dimethyl sulfide in the Arctic atmosphere  

NASA Astrophysics Data System (ADS)

Dimethyl sulfide (DMS), sulfur dioxide, non-sea-salt sulfate, and various aerosol properties were measured during three field programs (two airborne and one ground-based) near Barrow and Deadhorse (Prudhoe Bay), Alaska. The two airborne sampling programs took place in spring and early summer, and the ground-based measurements spanned an entire summer. DMS concentrations in the Arctic atmosphere ranged from a few parts per trillion by volume (pptv) in spring and fall to higher values in summer (generally a few tens of pptv with occasional peaks of 100 to 300 pptv). In addition, DMS concentrations were measured during the spring near Resolute in seawater below the ice and in ice-algae and kelp cultures. The seawater samples taken from below the ice in spring had DMS concentrations comparable to those in other oceanic regions. Taken together, these measurements show that the Arctic Ocean is potentially a substantial source of DMS, which likely becomes important as sea ice melts in the early summer. Local atmospheric concentrations increased throughout the summer, peaking in August. In regions where accumulation mode aerosols have been scavenged (e.g., by low-level stratus clouds, which are common during the Arctic summer), evidence of rapid new particle production was observed. The seasonal cycle of atmospheric DMS closely resembles that of fine particles observed at Barrow, Alaska, and Alert, Northwest Territories, Canada. This finding indicates that DMS is likely an important precursor to the types of particles that dominate the background arctic aerosol in summertime. These results, together with those from several recently published studies of arctic aerosol, are combined to yield a consistent picture of the role of locally emitted DMS in the production of atmospheric aerosols in the Arctic in summer.

Ferek, Ronald J.; Hobbs, Peter V.; Radke, Lawrence F.; Herring, John A.; Sturges, William T.; Cota, Glenn F.

1995-12-01

373

From ether theory to ether theology: Oliver Lodge and the physics of immortality.  

PubMed

This article follows the development of physicist Oliver Lodge's religio-scientific worldview, beginning with his reticent attraction to metaphysics in the early 1880s to the full formulation of his "ether theology" in the late 1890s. Lodge undertook the study of psychical phenomena such as telepathy, telekinesis, and "ectoplasm" to further his scientific investigations of the ether, speculating that electrical and psychical manifestations were linked phenomena that described the deeper underlying structures of the universe, beneath and beyond matter. For Lodge, to fully understand the ether was to force from the universe an ultimate Revelation, and psychical research, as the most modern and probatory science, was poised to replace religion as the means of that disclosure. PMID:17205538

Raia, Courtenay Grean

2007-01-01

374

Dehydration of scandium chloride hydrate: synthesis and molecular structures of ScCl 3(? 2DME)(MeCN), ScCl 3(diglyme) and [Sc 2(?-OH) 2(H 2O) 10]Cl 4·2H 2O  

Microsoft Academic Search

Various dehydration procedures have been evaluated for ScCl3·6H2O. The ScCl3(DME)(MeCN) 1 and ScCl3(diglyme) 2 [diglyme=MeO(CH2CH2O)2Me] adducts have been synthesized by a ligand-exchange reaction from ScCl3(THF)3 in acetonitrile. The diglyme adduct could also be obtained by dehydration of ScCl3·6H2O by trimethylchlorosilane in diethylether in the presence of the ligand. The complexes were characterized by FT–IR, 1H NMR and by X-ray diffraction.

Valérie Ripert; Liliane G. Hubert-Pfalzgraf; Jacqueline Vaissermann

1999-01-01

375

Structural insights into protein arginine symmetric dimethylation by PRMT5  

PubMed Central

Symmetric and asymmetric dimethylation of arginine are isomeric protein posttranslational modifications with distinct biological effects, evidenced by the methylation of arginine 3 of histone H4 (H4R3): symmetric dimethylation of H4R3 leads to repression of gene expression, while asymmetric dimethylation of H4R3 is associated with gene activation. The enzymes catalyzing these modifications share identifiable sequence similarities, but the relationship between their catalytic mechanisms is unknown. Here we analyzed the structure of a prototypic symmetric arginine dimethylase, PRMT5, and discovered that a conserved phenylalanine in the active site is critical for specifying symmetric addition of methyl groups. Changing it to a methionine significantly elevates the overall methylase activity, but also converts PRMT5 to an enzyme that catalyzes both symmetric and asymmetric dimethylation of arginine. Our results demonstrate a common catalytic mechanism intrinsic to both symmetric and asymmetric arginine dimethylases, and show that steric constrains in the active sites play an essential role in determining the product specificity of arginine methylases. This discovery also implies a potentially regulatable outcome of arginine dimethylation that may provide versatile control of eukaryotic gene expression.

Sun, Litao; Wang, Mingzhu; Lv, Zongyang; Yang, Na; Liu, Yingfang; Bao, Shilai; Gong, Weimin; Xu, Rui-Ming

2011-01-01

376

Cross-linkable fluorinated poly(ether ether ketone) polymers for optical waveguide devices  

Microsoft Academic Search

Cross-linkable fluorinated poly(ether ether ketone) (F-PEEK) polymers are systematically studied for low-loss optical waveguide. Two new bisphenol monomers, (3-trifluoromethyl)phenylhydroquinone (3F-PH) and (3,5-ditrifluoromethyl)phenyl hydroquinone (6F-PH), are prepared. Novel 3F-PEEK and 6F-PEEK polymers are synthesized from these two monomers. By spin coating and thermal cross-linking, the polymeric films provide good optical properties, including high thermal stability, low absorption loss at telecommunication wavelengths

Yu Zhao; Fei Wang; Aize Li; Baijun Liu; Zhongwen Wu; Daming Zhang; Shiyong Liu; Maobin Yi

2004-01-01

377

76 FR 7703 - 1,4-Benzenedicarboxylic Acid, Dimethyl Ester, Polymer With 1,4-Butanediol, Adipic Acid, and...  

Federal Register 2010, 2011, 2012, 2013

...4-Benzenedicarboxylic Acid, Dimethyl Ester, Polymer With 1,4- Butanediol, Adipic Acid...4-benzenedicarboxylic acid, dimethyl ester, polymer with 1,4-butanediol, adipic acid...4-benzenedicarboxylic acid, dimethyl ester, polymer with 1,4-butanediol, adipic...

2011-02-11

378

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

379

40 CFR 721.1225 - Benzene, 1,2-dimethyl-, poly-propene derivatives, sulfonated, po-tas-sium salts.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Benzene, 1,2-dimethyl-, poly-propene...Chemical Substances § 721.1225 Benzene, 1,2-dimethyl-, poly-propene...chemical substance identified as benzene, 1,2-dimethyl-,...

2009-07-01

380

Occupational exposure to glycol ethers and human congenital malformations  

Microsoft Academic Search

ObjectivesThis commentary reviews toxicological information and critically evaluates epidemiological information on the relationship between glycol ethers and congenital malformations.MethodsThe authors identified and assessed toxicological and epidemiological research on glycol ethers used in occupational settings and congenital malformations. Sensitivity analyses evaluated the possible role of methodological problems in explaining the findings of the epidemiological studies.ResultsExposure to certain glycol ethers, including ethylene

George Maldonado; Elizabeth Delzell; Rochelle W. Tyl; Lowell E. Sever

2003-01-01

381

cis-Dichlorido-tetra-kis-(dimethyl sulfoxide-?O)chromium(III) chloride dimethyl sulfoxide monosolvate  

PubMed Central

The structure of the title compound, [CrCl2(C2H6OS)4]Cl·C2H6OS, consists of a CrIII ion coordinated by four O atoms of dimethyl sulfoxide (DMSO) ligands and two chloride ions in cis positions, forming a distorted CrCl2O4 octa­hedron. An isolated Cl? counter-anion and a positionally disordered DMSO mol­ecule [occupancy ratio 0.654?(4):0.346?(4)] are also present. In the structure, the complex cations inter­act with the Cl? counter-anions and the DMSO solvent mol­ecules via weak C—H?Cl and C—H?O inter­actions, forming a three-dimensional network.

Al-Najjar, Nada A.; Al-Sudani, Abdul-Razak H.; Shanshal, Muthana A.; Mousa, Falih H.; Kariuki, Benson M.

2013-01-01

382

Conformational analysis of liquid dimethyl carbonate by molecular dynamics calculations  

NASA Astrophysics Data System (ADS)

Force field parameters for liquid dimethyl carbonate to use in molecular simulations were determined using ab initio calculations and molecular simulations. Molecular dynamics calculations of dimethyl carbonate were performed with these parameters to investigate the conformational and structural properties. The system reached conformational equilibrium with 68% of the most energetically stable conformation at 80 oC. A small deviation of the calculated concentration from that estimated with a Boltzmann distribution is due to the intermolecular interactions. The initial conformation determined with a Boltzmann distribution is confirmed to be a good first approximation for use in molecular simulations. The structure of dimethyl carbonate in the liquid phase was investigated with partial radial distribution functions. The temperature dependence of the density was in good agreement with experiment.

Okada, Okimasa

383

Exposure of gasoline road-tanker drivers to methyl tert -butyl ether and methyl tert -amyl ether  

Microsoft Academic Search

Organic oxygenates, namely, methyl tert-butyl ether (MTBE) and methyl tert-amyl ether (MTAE), are added to gasoline to reduce carbon monoxide in exhausts and to enhance the octane number. The aim\\u000a of this study was to investigate road-tanker drivers' exposure to oxygenate vapors during road-tanker loading and unloading\\u000a as well as to evaluate the measurements of these ethers and their metabolites

Lauri Saarinen; Matti Hakkola; Kaija Pekari; Kaija Lappalainen; Antero Aitio

1998-01-01

384

Regioselective and Stereoselective Entry to ?,?-Disubstituted Vinyl Ethers via the Sequential Hydroboration/Suzuki-Miyaura Coupling of Ynol Ethers.  

PubMed

A highly regio- and stereoselective synthesis of stereodefined ?,?-disubstituted alkenyl ethers featuring the sequential hydroboration/Suzuki-Miyaura coupling of ynol ethers has been described. A number of functional groups, including OMe, Ac, CO2Et, CN, halides, and alkyl, (hetero)aryl, and alkenyl groups, are well-tolerated under the reaction conditions. Furthermore, it allows a facile entry to the labile diarylacetaldehydes by TFA-mediated hydrolysis of ?,?-disubstituted vinyl ethers. PMID:24007364

Cui, Weijian; Mao, Mengyi; He, Zuying; Zhu, Gangguo

2013-09-19

385

Addition of dimethylsulphoxide to methyl-tert-butyl ether and ethyl propionate increases cholesterol dissolving capacity and cholesterol gall stone dissolution in vitro.  

PubMed

There is a discrepancy between in vitro cholesterol dissolving efficacy of methyl-tert-butyl ether (MTBE) and ethyl propionate and cholesterol gall stone dissolution in vivo. This study investigated whether the presence of bile changes the cholesterol dissolving capacity of MTBE and ethyl propionate. The addition of dimethylsulphoxide to MTBE or ethyl propionate was also studied to discover if it improves the dissolving capacity for cholesterol gall stones. The presence of bile caused a 25% decrease in cholesterol dissolving capacity of both MTBE and ethyl propionate (p < 0.0001). This inhibitory effect of bile could be overcome by the addition of dimethyl-sulphoxide: dimethylsulphoxide caused an increase in cholesterol dissolving capacity of MTBE and ethyl propionate, the increase depending on the dimethyl-sulphoxide/bile ratio in the mixture. Mean dissolution time of weight, size, and patient matched cholesterol gall stones was 220 minutes in MTBE and 130 minutes in MTBE/dimethylsulphoxide (p < 0.0001). No stones dissolved completely in ethyl propionate or ethyl propionate/dimethyl-sulphoxide within 300 minutes. In conclusion, MTBE/dimethylsulphoxide is a more potent dissolving agent for cholesterol gall stones than MTBE, giving a 40% reduction in dissolution time. Addition of dimethylsulphoxide to ethyl propionate does not result in faster stone dissolution. MTBE and MTBE/dimethylsulphoxide are far superior to ethyl propionate as solvents for cholesterol gall stones. PMID:7828992

Bergman, J J; Groen, A K; Huibregtse, K; Tytgat, G N

1994-11-01

386

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

387

Conference on Biological Actions and Medical Applications of Dimethyl Sulfoxide (DMSO), 15-17 September 1982.  

National Technical Information Service (NTIS)

This report is a result entitled: Conference on Biological Actions and Medical Applications of Dimethyl Sulfoxide, held September 15-17, 1982. Topics covered include toxicological update of dimethyl sulfoxide (DMSO); biochemical and immunological mechanis...

J. C. De La Torre

1983-01-01

388

21 CFR 524.981d - Fluocinolone acetonide, dimethyl sulfoxide solution.  

Code of Federal Regulations, 2013 CFR

...Fluocinolone acetonide, dimethyl sulfoxide solution. 524.981d Section 524.981d ...Fluocinolone acetonide, dimethyl sulfoxide solution. (a) Specifications. Each milliliter of solution contains 0.01 percent...

2013-04-01

389

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

390

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

391

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

392

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...

2009-07-01

393

40 CFR 721.10518 - Diethylene glycol, polymer with diisocyanatoalkane, polyethylene glycol monomethyl ether- and...  

Code of Federal Regulations, 2013 CFR

...polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked...polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked...polyethylene glycol monomethyl ether- and fluorinatedalkanol-blocked...impurity levels of certain fluorinated impurities.). (b)...

2013-07-01

394

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).  

Code of Federal Regulations, 2013 CFR

...benzene ether, polymer with substituted phenol (generic). 721.1580 Section 721...benzene ether, polymer with substituted phenol (generic). (a) Chemical substance...benzene ether, polymer with substituted phenol (PMN P-98-155) is subject to...

2013-07-01

395

40 CFR 721.10017 - Amine terminated bisphenol A diglycidyl ether polymer (generic).  

Code of Federal Regulations, 2013 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...

2013-07-01

396

40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).  

Code of Federal Regulations, 2010 CFR

...benzene ether, polymer with substituted phenol (generic). 721.1580 Section 721...benzene ether, polymer with substituted phenol (generic). (a) Chemical substance...benzene ether, polymer with substituted phenol (PMN P-98-155) is subject to...

2009-07-01

397

40 CFR 721.10017 - Amine terminated bisphenol A diglycidyl ether polymer (generic).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 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...

2009-07-01

398

40 CFR 721.10017 - Amine terminated bisphenol A diglycidyl ether polymer (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 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...

2010-07-01

399

21 CFR 177.1970 - Vinyl chloride-lauryl vinyl ether copolymers.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Vinyl chloride-lauryl vinyl ether copolymers. 177.1970 Section 177...177.1970 Vinyl chloride-lauryl vinyl ether copolymers. The vinyl chloride-lauryl vinyl ether copolymers identified in paragraph...

2009-04-01

400

21 CFR 177.1970 - Vinyl chloride-lauryl vinyl ether copolymers.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 true Vinyl chloride-lauryl vinyl ether copolymers. 177.1970 Section 177...177.1970 Vinyl chloride-lauryl vinyl ether copolymers. The vinyl chloride-lauryl vinyl ether copolymers identified in paragraph...

2010-01-01

401

Reactions accompanying the chlorination of dimethyl hydrogen phosphite with chlorine  

SciTech Connect

In the chlorination of dimethyl hydrogen phosphite the purity of the dimethyl phosphorochloridate obtained is influenced by the presence of hydrogen chloride in the reaction mixture and the ingress of water into the reaction sphere. With the aid of /sup 31/P NMR spectroscopy it was shown that, when moisture finds its way into the sphere of reaction, in the further distillation of the crude reaction mixture, apart from the latter, trimethyl phosphate formed as a result of the breakdown of tetramethyl pyrophosphate also distills off.

Kir'yazov, M.P.; Belova, L.A.; Soifer, R.S.; Bogel'fer, L.Ya.; Negrebetskii, V.V.; Bakanova, Z.M.

1987-11-20

402

Dimethyl-ammonium 3-carb-oxy-benzoate  

PubMed Central

The asymmetric unit of the title organic salt, C2H8N+·C8H5O4 ?, consists of two dimethyl­ammonium cations and two 3-carb­oxy­benzoate anions. The 3-carb­oxy­benzoate anions are linked via strong inter­molecular and nearly symmetrical O—H?O hydrogen bonds forming infinite chains parallel to [111]. Neighbouring chains are further connected by the dimethyl­ammonium cations via N—H?O bonds, resulting in a double-chain-like structure. The dihedral angles of all carboxylate groups with respect to the phenylene rings are in the range 7.9?(1)–20.48?(9)°.

Siddiqui, Tausif; Koteswara Rao, Vandavasi; Zeller, Matthias; Lovelace-Cameron, Sherri R.

2012-01-01

403

Poly(arylene ether)s containing superacid groups as proton exchange membranes.  

PubMed

A series of poly(arylene ether)s containing pendant superacid groups on fluorenyl groups were synthesized and their properties were investigated for fuel cell applications. Poly(arylene ether)s containing iodo groups were synthesized by the polymerization of 2,7-diiodo-9,9-bis(4-hydroxyphenyl)fluorene with difluorinated compounds such as decafluorobiphenyl, bis(4-fluorophenyl)sulfone, and bis(4-fluorophenyl)ketone, under nucleophilic substitution conditions. The iodo groups on the fluorenyl groups were converted to perfluorosulfonic acid groups via the Ullmann coupling reaction. The degree of perfluorosulfonation was controlled to be up to 92%, which corresponds to an ion exchange capacity (IEC) of 1.52 meq/g. The ionomers yielded flexible, ductile membranes by solution casting. The ionomer membranes exhibited a characteristic hydrophilic/hydrophobic phase separation, with small interconnected hydrophilic clusters (2-3 nm), which is similar to that of the benchmark perfluorinated membrane (Nafion). The aromatic ionomers containing superacid groups showed much higher proton conductivities than those of the conventional sulfonated aromatic ionomers with similar main chain structures. Fuel cell performance with the superacidic ionomer membranes was also tested. PMID:20491452

Mikami, Takefumi; Miyatake, Kenji; Watanabe, Masahiro

2010-06-01

404

Survey of glycol ether use in Taiwan, 1991.  

PubMed

Glycol ethers (including glycol ether esters) are a group of solvents with medium-high boiling points and low evaporation rates, possessing solvent characteristics of alcohol/ether functions (or ether/ester functions). They have been widely used in coatings and other industrial products for more than half a century. Recently, E-series glycol ethers have been found to show reproductive and teratogenic toxicity, and throughout much of the world they are being replaced by the so-called P-series glycol ethers. In responding to the impact of the worldwide transition from E- to P-series glycol ethers, the current status of glycol ether use in Taiwan was studied. This study focuses on the type and quantity of these solvents being used, worker and public knowledge about their hazards, and possible changes in government regulations being considered. In this study, we found that large quantities of E-series glycol ethers were imported and used in Taiwan. The best estimates are: 2-ME, 2,500 tons; 2-EE, 1,200 tons; 2-EEA, 5,000-8,000 tons; 2-BE, 8,000 tons annually in 1991. For P-series glycol ethers, only about 2,500 tons are being used. Lack of knowledge about the potential toxic effects of the E-series glycol ethers is very common among users, regulatory agencies, academic institutes, and the general public. It is hoped that the results of this study, along with educational efforts, government regulations, and provision of technical services, will help prevent Taiwan from becoming a dumping site for these toxic chemicals. PMID:8352288

Lin, C K; Chen, R Y

1993-07-01

405

Synthesis of ?,?-difluoroethyl aryl and heteroaryl ethers.  

PubMed

Fluorine plays a critical role in modern medicinal chemistry due to its unique properties, and new methods for its incorporation into target molecules are of high interest. An efficient new method for the preparation of aryl-?,?-difluoroethyl ethers (4) via addition of aryl and heteroaryl alcohols (1) to commercially available 2-bromo-1,1-difluoroethene (2) and subsequent hydrogenolysis is presented. This procedure is an attractive alternative to existing methods that employ harshly reactive fluorinating systems such as xenon difluoride and hydrogen fluoride. PMID:22817683

Yang, Eddie; Reese, Matthew R; Humphrey, John M

2012-07-20

406

Arborinol methyl ether from Areca catechu L.  

PubMed Central

The title compound isolated from Areca catechu L. (common name: arborinol methyl ether; a member of the arborane family) was established as 3?-methoxyarbor-9(11)-ene, C31H52O. Rings A/B/C/D assume a chair conformation, while ring E has an envelope conformation. The absolute configuration was determined to be (3R,5R,8S,10S,13R,14S,17S,18S, 21S) by analysis of Bijvoet pairs based on resonant scattering of light atoms, yielding a Hooft parameter y of ?0.03?(3).

He, Xixin; Li, Yajun; Zhang, Cuixian; Hu, Xiaopeng

2010-01-01

407

New ways to derivatize at position 6 of 7,7-dimethyl-7,8-dihydropterin  

PubMed Central

Reported are the synthesis of two intermediates for derivatization at position 6 of 7,7-dimethyl-7,8-dihydropterin: 6-carboxylic acid ethyl ester-7,7-dimethyl-7,8-dihydropterin, which is a novel compound, and 6-aldehyde-7,7-dimethyl-7,8-dihydropterin, which is synthesized by a new method with a yield of 90%.

Shi, Genbin; Ji, Xinhua

2011-01-01

408

Enhancement of ketoconazole penetration across the blood-brain barrier of mice by dimethyl sulfoxide.  

PubMed Central

Mice were treated with ketoconazole with and without dimethyl sulfoxide. Concentrations of ketoconazole at 3 and 5 h after treatment were significantly higher in serum (P less than 0.05) and brain tissue homogenate (P less than 0.01) of mice treated with dimethyl sulfoxide than in those of mice not treated with dimethyl sulfoxide.

Iwen, P C; Miller, N G

1986-01-01

409

40 CFR 721.10587 - 1H-Pyrazole, 3,4-dimethyl-.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false 1H-Pyrazole, 3,4-dimethyl-. 721.10587...Chemical Substances § 721.10587 1H-Pyrazole, 3,4-dimethyl-. (a) Chemical...chemical substance identified as 1H-pyrazole, 3,4-dimethyl- (PMN...

2013-07-01

410

40 CFR 721.8160 - Propanoic acid, 2,2-dimethyl-, ethenyl ester.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Propanoic acid, 2,2-dimethyl-, ethenyl...Substances § 721.8160 Propanoic acid, 2,2-dimethyl-, ethenyl...substance identified as propanoic acid, 2,2-dimethyl...Standard Test Method for Resistance of Protective Clothing...

2013-07-01

411

Dibromido(2,9-dimethyl-1,10-phenanthroline-?2 N,N?)(dimethyl sulfoxide-?O)cadmium  

PubMed Central

In the mol­ecule of the title compound, [CdBr2(C14H12N2)(C2H6OS)], the CdII atom is five-coordinated in a distorted trigonal–bipyramidal configuration by two N atoms from a 2,9-dimethyl-1,10-phenanthroline ligand, one O atom from a dimethyl sulfoxide ligand and two Br atoms. In the crystal, ?–? contacts between the pyridine and benzene rings [centroid–centroid distances = 3.710?(5), 3.711?(6) and 3.627?(5)?Å] stabilize the structure.

Moghanlou, Khadijeh

2013-01-01

412

Laboratory study of poisoning of a MnO/Fe2O3 catalyst by dimethyl sulfide and dimethyl disulfide.  

PubMed

The catalytic incineration of dimethyl sulfide and dimethyl disulfide in a MnO/Fe(2)O(3) fixed bed catalytic reactor was studied. This paper provides information on the affect of the operating parameters that included: inlet temperature, space velocity, VOC concentration and O(2) concentration. The results show that the conversion of VOCs increases as the inlet temperature increases and the space velocity decreases. The higher the concentration of VOCs, the lower their conversions. The O(2) concentration has no affect on the conversion of VOCs. VOCs have poisoning affects on the MnO/Fe(2)O(3) catalyst, especially at lower temperatures. PMID:12835030

Chu, H; Hao, G H; Tseng, T K

2003-06-27

413

(4,4?-Dimethyl-2,2?-bipyridine-?2 N,N?)(dimethyl-formamide-?O)diiodido-cadmium  

PubMed Central

In the title compound, [CdI2(C12H12N2)(C3H7NO)], the CdII cation is five-coordinated in a distorted trigonal–bipyramidal configuration by two N atoms from a 4,4?-dimethyl-2,2?-bipyridine ligand, one O atom from a dimethyl­formamide ligand and two I? anions. ?–? stacking between pyridine rings of adjacent mol­ecules [centroid–centroid distance = 3.666?(3) and 3.709?(4)?Å] stabilizes the three-dimensional structure

Shirvan, Sadif A.; Haydari Dezfuli, Sara; Khazali, Fereydoon; Borsalani, Ali

2012-01-01

414

Dibromido(4,4?-dimethyl-2,2?-bipyridine-?2 N,N?)(dimethyl sulfoxide-?O)cadmium  

PubMed Central

In the title compound, [CdBr2(C12H12N2)(C2H6OS)], the CdII atom is five-coordinated in a distorted trigonal–bipyramidal geometry by two N atoms from one 4,4?-dimethyl-2,2?-bipyridine (DMBP) ligand, one O atom from a dimethyl sulfoxide (DMSO) ligand and two Br atoms. A weak intra­molecular C—H?O hydrogen bond occurs between the DMBP and DMSO ligands. ?–? stacking between pyridine rings [centroid–centroid distances = 3.682?(3) and 3.598?(3)?Å] is observed in the crystal.

Shirvan, Sadif A.; Haydari Dezfuli, Sara

2012-01-01

415

Binuclear complexes of La(III) and Eu(II) with the bridging naphthalene dianion. Synthesis and X-ray crystallographic analysis of [ ? 2- ? 4: ? 4-C 10H 8][LaI 2(THF) 3] 2 and [ ? 2- ? 4: ? 4-C 10 H 8][EuI(DME) 2] 2  

Microsoft Academic Search

The treatment of LaI3(THF)3 with equimolar amounts of Li and excess of C10H8 in THF results in the formation of [C10H8][LaI2(THF)3]2 (1) and the reaction of EuI2(THF)2 with Li and C10H8 in DME leads to [C10H8][EuI(DME)2]2 (2), which have been characterized by IR and UV-VIS spectroscopy as well as by X-ray crystallography. 1 is monoclinic, space group P21\\/c (No. 14),

Igor L. Fedushkin; Mikhail N. Bochkarev; Herbert Schumann; Lothar Esser

1995-01-01

416

Theoretical study of beryllium structures analogous to crown ethers  

Microsoft Academic Search

In this paper we present the electronic and structural study of beryllium molecules analogous to crown ethers, where the –CH2– groups have been exchanged for beryllium atoms. The resulting structures are completely planar, unlike crown ethers, that the latter are bi-dimensional and flexible. In addition, the coordination of lithium atoms (as Li+), which are arranged directionally to each oxygen atom,

Maria Esther Sanchez-Castro; Mario Sanchez-Vazquez

2011-01-01

417

Development of Metallacrown Ethers: A New Class of Metal Clusters  

Microsoft Academic Search

Crown ethers have been used for over twenty years as selective binding agents for alkali metal and alkaline earth ions. Although there have been many modifications to the crown ether core, none is so dramatic as to substitute heteroatoms into the positions normally occupied by carbon atoms. In this article we describe a new class of metal clusters which incorporate

Myoung Soo Lah; Vincent L. Pecoraro

1990-01-01

418

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

419

Process for the production of ether and alcohol  

Microsoft Academic Search

This patent describes a process for producing ether containing at most relatively minor amounts of water, it comprises: contacting at least one light olefin with water in an olefin conversion unit in the presence of an acidic zeolite as catalyst to provide an aqueous mixture of alcohol and ether, the olefin conversion unit being operated under conditions which are effective

T. J. Huang; R. B. LaPierre; S. A. Tabak

1989-01-01

420

Process for the production of ether and alcohol  

SciTech Connect

This patent describes a process for producing ether containing at most relatively minor amounts of water, it comprises: contacting at least one light olefin with water in an olefin conversion unit in the presence of an acidic zeolite as catalyst to provide an aqueous mixture of alcohol and ether, the olefin conversion unit being operated under conditions which are effective to provide alcohol by the reaction of olefin and water therein and ether by the dehydration of alcohol and/or by the reaction of olefin and alcohol therin; introducing the aqueous mixture of alcohol and ether into a distillation unit supplied with at least a part of the ether layer recovered from a downstream decantation operation; introducing the azeotropic overheads fraction into a decanter unit operated under conditions which are effective to provide an ether layer containing at most negligible amounts of water and an aqueous product containing negligible amounts of alcohol; and, introducing at least part of the ether layer into the distillation unit to reduce the water content of the final ether product.

Huang, T.J.; LaPierre, R.B.; Tabak, S.A.

1989-08-15

421

The Ether Wind and the Global Positioning System.  

ERIC Educational Resources Information Center

Explains how students can perform a refutation of the ether theory using information from the Global Positioning System (GPS). Discusses the functioning of the GPS, qualitatively describes how position determination would be affected by an ether wind, and illustrates the pertinent ideas with a simple quantitative model. (WRM)

Muller, Rainer

2000-01-01

422

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

423

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

424

HPLC and TLC characterisation of ecdysteroid alkyl ethers.  

PubMed

Semi-synthetic ecdysteroid alkyl ethers have increased potential over natural ecdysteroids as actuators of ligand-inducible gene-expression systems based on the ecdysteroid receptor for in vivo applications. However, a scalable synthesis of these compounds has yet to be developed. We report a set of reversed-phase (RP; C(18) and C(6)) and normal-phase (NP; diol) HPLC systems which can be used to analyse and separate ecdysteroid ethers with single or multiple O-methyl substitutions at the 2alpha-, 3beta-, 14alpha-, 22- and 25-positions. The elution order of methyl ether analogues of the prototypical ecdysteroid 20-hydroxyecdysone (20E) was 3-methyl<2-methyl<14-methyl<25-methyl<22-methyl with both C(18)- and C(6)-RP-HPLC, when eluted with methanol/water mixtures. Further, the elution order of 20E 22-O-alkyl ethers was methylethers can also be adequately resolved by NP-HPLC and silica HPTLC. On the latter, detection of ecdysteroid O-alkyl ethers with the p-anisaldehyde/sulphuric acid reagent distinguishes 22-O-alkyl ethers from non-22-O-alkyl ether analogues by the colour of the resulting spot. PMID:19648067

Lapenna, Silvia; Dinan, Laurence

2009-07-17

425

Emergent gravity and ether-drift experiments  

NASA Astrophysics Data System (ADS)

According to several authors, gravity might be a long-wavelength phenomenon emerging in some ‘hydrodynamic limit’ from the same physical, flat-space vacuum viewed as a form of superfluid medium. In this framework, light might propagate in an effective acoustic geometry and exhibit a tiny anisotropy that could be measurable in the present ether-drift experiments. By accepting this view of the vacuum, one should also consider the possibility of sizeable random fluctuations of the signal that reflect the stochastic nature of the underlying ‘quantum ether’ and could be erroneously interpreted as instrumental noise. To test the present interpretation, we have extracted the mean amplitude of the signal from various experiments with different systematics, operating both at room temperature and in the cryogenic regime. They all give the same consistent value {< A rangle ={mathcal O}(10^{-15})} which is precisely the magnitude expected in an emergent-gravity approach, for an apparatus placed on the Earth’s surface. Since physical implications could be substantial, it would be important to obtain more direct checks from the instantaneous raw data and, possibly, with new experimental set-ups operating in gravity-free environments.

Consoli, M.; Pappalardo, L.

2010-11-01

426

Lanthanide Extraction with 2,5-Dimethyl-2-Hydroxyhexanoic Acid.  

National Technical Information Service (NTIS)

This research is concerned with the solvent extraction into chloroform of the lanthanides, using 2,5-dimethyl-2-hydroxyhexanoic acid (DMHHA). This acid is the first alpha -hydroxy aliphatic acid to be studied as an extracting agent for the lanthanides. Th...

J. H. Miller

1977-01-01

427

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...

428

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

429

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

430

Polysiloxane depolymerization with dimethyl carbonate using alkali metal halide catalysts  

Microsoft Academic Search

Polydimethylsiloxane terminated by a methyl group was almost completely depolymerized in the mixture of dimethyl carbonate (DMC) and methanol using alkali metal halide catalysts to form dimethoxydimethylsilane (DMDMS) and methoxytrimethylsilane (MTMS) monomers. The various alkali metal halides tested as catalysts gave the same monomer yield. The depolymerization rate depended on the kind of alcohol but not on dialkyl carbonate. The

Masaki Okamoto; Sumiko Suzuki; Eiichi Suzuki

2004-01-01

431

Spectroscopic and electrochemical studies of horse myoglobin in dimethyl sulfoxide  

Microsoft Academic Search

This paper reports the first report of rapid, reversible direct electron transfer between a redox protein, specifically, horse myoglobin, and a solid electrode substrate in nonaqueous media and the spectroscopic (UV-vis, fluorescence, and resonance Raman) characterization of the relevant redox forms of myoglobin (Mb) in dimethyl sulfoxide (DMSO). In DMSO, the heme active site of metmyoglobin (metMb) appears to remain

Qiu Li; Patricia Mabrouk

2003-01-01

432

Thermodynamic properties of LiCl in dimethyl sulfoxide  

Microsoft Academic Search

The partial molal free energy, entropy, and enthalpy of transfer of lithium chloride from dimethyl sulfoxide to water are calculated to be -4.93 kcal\\/mole, +24.8 cal\\/C-mole, and +2.61 kcal\\/mole, respectively.

William H. Smyrl; Charles W. Tobias

1968-01-01

433

Dimethyl Sulfoxide in Plastic Surgery of the Skin.  

National Technical Information Service (NTIS)

Dimethyl sulfoxide (DMSO) possesses a number of valuable properties. It exhibits a preservative effect in the storage of tissue and successful results in the transplantation of human skin stored for extended periods (up to 608 days) in 10 percent DMSO sol...

M. F. Kamaev

1970-01-01

434

Real-timed measurement of dimethyl sulfoxide in ambient air  

SciTech Connect

Dimethyl sulfoxide (DMSO) is formed in the atmosphere as an intermediate product of the OH addition reaction with dimethyl sulfide (DMS). In turn, OH also attacks DMSO to form dimethyl sulfone (DMSO[sub 2]), one of the stable end products of atmospheric DMS oxidation. Recently, it has been hypothesized that the emission of dimethyl sulfide (DMS) from the world's oceans and its oxidation in the atmosphere may be responsible for controlling cloud formation over remote oceanic regions. Therefore, it has been further suggested that atmospheric DMS chemistry plays a significant role in global climate change. To verify this hypothesis instrumental techniques must be used or developed which are capable of measuring DMS, its major oxidants, and its individual oxidation products, including DMSO, in the real atmosphere, preferably with a high time resolution. Previously, the authors have already reported the successful development of different mass spectrometric techniques for real-time measurement of DMS, SO[sub 2], CH[sub 3]S(O[sub 2])OH, H[sub 2]SO[sub 4], and OH in the atmosphere. In this paper the authors describe a new highly sensitive method for real-time measurement of DMSO in ambient air. 14 refs., 2 figs.

Berresheim, H.; Tanner, D.J.; Eisele, F.L. (Georgia Institute of Technology, Atlanta (United States))

1993-01-01

435

Fuel Cross Leak of Direct Di-methyl-ether Fuel Cell  

NASA Astrophysics Data System (ADS)

Fuel cross leak through a polymer electrolyte membrane of the direct dimethyl ether fuel cell (DDFC) was investigated and was found to be approximately one-tenth that of the direct methanol fuel cell (DMFC). Three phenomena known to appear in the DMFC were also observed in the DDFC. These were (1) fuel cross leak due to the diffusion which increases with the fuel concentration on an open circuit condition, (2) electro-osmotic cross leak, which increases with the current density and fuel concentration, and (3) decrease of fuel cross leak with the increase of the current density due to fuel consumption at low fuel concentration. The decreased fuel cross leak realized by using Nafion ®117 as a membrane and the low fuel concentration of 11% resulted in an increase of the Farady efficiency of the DDFC of up to 90% at a current density of 80mA/cm2. The CO2 quantity at the anode outlet of the operating DDFC was slightly less than 2 mol per 12 protons, as estimated from an electrochemical reaction on the anode. The CO2 quantity at the cathode outlet was also investigated. The CO2 cross leak increased with current density at every CO2 concentration and the diffusion appeared to be the dominant phenomenon of the CO2 cross leak.

Tsutsumi, Yasuyuki; Nakano, Yasuhiro; Haraguchi, Tadao

436

PhysicoChemical Study of Sulfonated Poly(Ether Ether Ketone) Membranes for Direct Methanol Fuel Cell Application  

Microsoft Academic Search

Sulfonated poly(ether ether ketone) (SPEEK) membranes have been prepared as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cell (DMFC) application. The SPEEK polymer was dissolved into N, N-dimethylacetamide (DMAc) in a subsequent step after sulfonating the raw polymer with concentrated sulfuric acid. The polymer solutions were then cast by pneumatic casting machine. The influence of sulfonation reaction

M. H. D. Othman; A. F. Ismail; A. Mustafa

2007-01-01

437

Synthesis and characterization of poly(silyl ether)s and modified poly(siloxane)s  

NASA Astrophysics Data System (ADS)

Activated dihydridocarbonyltris(triphenylphosphine)ruthenium ( Ru) catalyzes the dehydrogenative silylation condensation copolymerization of ortho-quinones with alpha,o-dihydrido-oligodimethylsiloxanes to give high molecular weight copoly(arylene-1,2-dioxy/oligodimethylsiloxanylene)s in good chemical yield. The hydrosilylation polymerization of aliphatic o-dimethylsilyloxy ketones is also catalyzed by activated Ru to yield unsymmetrical poly(silyl ether)s. Likewise, Ru catalyzes the copolymerization of alpha,o-diketones with alpha,o-dihydrido-oligodimethylsiloxanes to yield symmetrical poly(silyl ether)s. A mechanism of the copolymerizations is proposed, in which beta-hydride elimination is favored over reductive elimination in the reaction of the ortho-quinones. Chiral centers affect the NMR spectra of the poly(silyl ether)s produced by hydrosilylation. The photoluminescence properties of the polymers were studied along with those of model compounds. The decrease in Tgs with increase in siloxane chain length as well as fluorescence spectra is discussed. RuH2(CO)(PPh3)3 (Ru), activated with a stoichiometric amount of styrene, catalyzes the anti-Markovnikov addition of an ortho C-H bond of benzophenone across the C-C double bonds of alpha,o-bis(trimethylsilyloxy)copoly(dimethylsiloxane/vinylmethylsiloxane), alpha,o-bis(vinyldimethsilyloxy)poly(dimethylsiloxane)s, and 1,3-divinyltetramethyldisiloxane to yield alpha,o-bis(trimethylsilyloxy)copoly[dimethylsiloxane/2-(2 '-benzophenonyl)ethylmethylsiloxane]s, alpha,o-bis[2-(2 '-benzophenonyl)ethyldimethylsilyloxy]poly(dimethylsiloxane)s, and 1,3-bis[2-(2'-benzophenonyl)ethyl]tetramethyldisiloxane, respectively. While the Mw/Mn and Tgs of the modified polysiloxanes are similar to those of the precursor polymers, an increase in molecular weight is observed upon heating. 1,3-bis[2-(2 '-Benzophenonyl)ethyl]tetramethyldisiloxane, a model compound, was utilized to test a mechanism for the increase in molecular weight. A mechanism is proposed. Fluorinated and non-fluorinated 1,9-bis(epoxyalkyl)pentasiloxanes have been prepared by the Pt-catalyzed hydrosilylation reaction of vinylepoxides with 1,9-dihydridopentasiloxanes. The 1,9-dihydridopentasiloxanes were prepared by the triflic acid-catalyzed ring-opening of the corresponding cyclotrisiloxanes in the presence of 1,1,3,3-tetramethyldisiloxane. Insoluble cross-linked thin films have been prepared by the diaryliodonium salt photo-acid catalyzed ring-opening polymerization of the 1,9-bis(epoxyalkyl)pentasiloxanes. These materials may be useful as anti-corrosion/foul-release coatings for marine applications.

Mabry, Joseph Mark

438

Identification and removal of the organic compounds in coal-conversion condensate waters. [Dimethyl hydantoin  

SciTech Connect

The purpose of this investigation is research on physical-chemical treatment processes to achieve bulk removal of Chemical Oxygen Demand (COD) from coal-conversion condensate waters. It is anticipated tht combinations of steam stripping and solvent extraction will economically meet most treatment goals. However, there is evidence in the literature which suggests that a significant fraction of the COD in many condensate waters is composed of compounds which are more polar than phenol. This presents two problems. First, these compounds may have very low distribution coefficients into common industrial solvents such as diisopropyl ether (Phenosolvan process) or methylisobutyl ketone (Chem-Pro process). Second, these compounds may not be extracted by methylene chloride, so they may not respond to the GC/MS analytical techniques which are currently used to study these water streams. In this work the literature has been reviewed, and solvent extraction studies have been performed. These studies show that a large fraction of the COD can be economically removed with solvent extraction. The fraction of the COD which remains is significant, however, and is apparently composed of very polar compounds. A sample-preparation technique employing azeotropic distillation with isopropanol has been developed and recovers very polar compounds which are sufficiently non-volatile and soluble in isopropanol for qualitative analysis by GC-MS. High performance liquid chromatography (HPLC) was used to obtain quantitative information about these compounds, as well as the simple phenolics. Dimethyl hydantoin and related compounds have been identified in a coal gasification condensate water for the first time. However, the levels of these compounds appear to be affected by sample age and storage conditions. This behavior is presently being further investigated.

Mohr, D.H. Jr.; King, C.J.

1982-05-01

439

Biodegradation of ethyl t -butyl ether (ETBE), methyl t -butyl ether (MTBE) and t -amyl methyl ether (TAME) by Gordonia terrae  

Microsoft Academic Search

Gordonia terrae strain IFP 2001 was selected from activated sludge for its capacity to grow on ethyl t-butyl ether (ETBE) as sole carbon and energy source. ETBE was stoichiometrically degraded to t-butyl alcohol (TBA) and the activity was inducible. A constitutive strain, G. terrae IFP 2007, derived from strain IFP 2001, was also selected. Methyl t-butyl ether (MTBE) and t-amyl

Guillermina Hernandez-Perez; Françoise Fayolle; Jean-Paul Vandecasteele

2001-01-01

440

Spiroborate Ester-Mediated Asymmetric Synthesis of ?-Hydroxy Ethers and its Conversion to Highly Enantiopure ?-Amino Ethers  

PubMed Central

Borane-mediated reduction of aryl and alkyl ketones with ?-aryl- and ?-pyridyloxy groups affords ?-hydroxy ethers in high enantiomeric purity (up to 99% ee) and in good yield, using as catalyst 10 mol % of spiroborate ester 1 derived from (S)-diphenylprolinol. Representative ?-hydroxy ethers are successfully converted to ?-amino ethers, with minor epimerization, by phthalimide substitution under Mitsunobu’s conditions followed by hydrazinolysis, to obtain primary amino ethers or by imide reduction with borane to afford ?-2,3-dihydro-1H-isoindol ethers. Non-racemic Mexiletine and nAChR analogues with potential biological activity are also synthesized in excellent yield by mesylation of key ?-hydroxy pyridylethers and substitution with 5, 6 and 7 member ring heterocyclic amines.

Huang, Kun; Ortiz-Marciales, Margarita; Correa, Wildeliz; Pomales, Edgardo; Lopez, Xaira Y.

2009-01-01

441

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

442

Ethylene glycol monomethyl ether and propylene glycol monomethyl ether: metabolism, disposition, and subchronic inhalation toxicity studies  

SciTech Connect

Short-term and subchronic vapor inhalation studies have shown that there are pronounced differences in the toxicological properties of ethylene glycol monomethyl ether (EGME) and propylene glycol monomethyl ether (PGME). Overexposure to EGME has resulted in adverse effects on testes, bone marrow and lymphoid tissues in laboratory animals. PGME does not affect these tissues, and instead, overexposure to PGME has been associated with increases in liver weight and central nervous system depression. EGME is primarily oxidized to methoxyacetic acid in male rats, while PGME apparently undergoes O-demethylation to form propylene glycol. Since methoxyacetic acid has been shown to have the same spectrum of toxicity as EGME in male rats, the observed differences in the toxicological properties of EGME and PGME are thought to be due to the fact that the two materials are biotransformed via different routes to different types of metabolites. 6 references, 3 figures, 12 tables.

Miller, R.R.; Hermann, E.A.; Young, J.T.; Landry, T.D.; Calhoun, L.L.

1984-08-01

443

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

2012-03-27

444

Application of Crown Ether to Chemical Analysis. III. Extraction of Amines with Crown Ether  

Microsoft Academic Search

The protonated amines were extracted with crown ether as the picrate into organic solvent. The overall extraction constants(Kex) for the 1 : 1 : 1 complexes, AHLP, of 18-crown-6 with protonated amines and picrate between 1,2-dichloroethane and water have been determined at 25°C. The extractability of complexes decreased in the sequence: primary amines > secondary amines, which indicated that the

H. Noguchi; N. Yoshio; K. Kawahara; H. Nakamura; M. Nagamatsu

1980-01-01

445

Oligomer formation during gas-phase ozonolysis of small alkenes and enol ethers: new evidence for the central role of the Criegee Intermediate as oligomer chain unit  

NASA Astrophysics Data System (ADS)

An important fraction of secondary organic aerosol (SOA) formed by atmospheric oxidation of diverse volatile organic compounds (VOC) has recently been shown to consist of high-molecular weight oligomeric species. In our previous study (Sadezky et al., 2006), we reported the identification and characterization of oligomers as main constituents of SOA from gas-phase ozonolysis of small enol ethers. These oligomers contained repeated chain units of the same chemical composition as the main Criegee Intermediates (CI) formed during the ozonolysis reaction, which were CH2O2 (mass 46) for alkyl vinyl ethers (AVE) and C2H4O2 (mass 60) for ethyl propenyl ether (EPE). In the present work, we extend our previous study (Sadezky et al., 2006) to another enol ether (ethyl butenyl ether EBE) and a variety of structurally related small alkenes (trans-3-hexene, trans-4-octene and 2,3-dimethyl-2-butene). Experiments have been carried out in a 570 l spherical glass reactor at atmospheric conditions in the absence of seed aerosol. SOA formation was measured by a scanning mobility particle sizer (SMPS). SOA filter samples were collected and chemically characterized off-line by ESI(+)/MS-TOF and ESI(+)/MS/MS-TOF, and elemental compositions were confirmed by ESI(+)/MS/MS-FTICR. The results for all investigated unsaturated compounds are in excellent agreement with the observations of our previous study (Sadezky et al., 2006). Analysis of the collected SOA filter samples reveal the presence of oligomeric compounds in the mass range 200 to 800 u as major constituents. The repeated chain units of these oligomers are shown to systematically have the same chemical composition as the respective main Criegee Intermediate (CI) formed during ozonolysis of the unsaturated compounds, which is C3H6O2 (mass 74) for ethyl butenyl ether (EBE), trans-3-hexene, and 2,3-dimethyl-2-butene, and C4H8O2 (mass 88) for trans-4-octene. Analogous fragmentation pathways among the oligomers formed by gas-phase ozonolysis of the different alkenes and enol ethers in our present and previous study (Sadezky et al., 2006), characterized by successive losses of the respective CI-like chain unit as a neutral fragment, indicate a similar principal structure. As in our previous work (Sadezky et al., 2006), we suggest the basic structure of a linear oligoperoxide -[CH(R)-O-O]n- for all detected oligomers, with the repeated chain unit CH(R)OO corresponding to the respective major CI. Furthermore, copolymerization of CI simultaneously formed in the gas phase from two different unsaturated compounds is shown to occur during the ozonolysis of a mixture of trans-3-hexene and ethyl vinyl ether (EVE), leading to formation of oligomers with mixed chain units C3H6O2 (mass 74) and CH2O2 (mass 46). We therefore suggest oligoperoxide formation to be a general, so far unknown reaction pathway of small stabilized CI in the gas phase, which represents an alternative way to high-molecular products and thus contributes to SOA formation.

Sadezky, A.; Winterhalter, R.; Kanawati, B.; Römpp, A.; Spengler, B.; Mellouki, A.; Le Bras, G.; Chaimbault, P.; Moortgat, G. K.

2007-10-01

446

Oligomer formation during gas-phase ozonolysis of small alkenes and enol ethers: new evidence for the central role of the Criegee Intermediate as oligomer chain unit  

NASA Astrophysics Data System (ADS)

An important fraction of secondary organic aerosol (SOA) formed by atmospheric oxidation of diverse volatile organic compounds (VOC) has recently been shown to consist of high-molecular weight oligomeric species. In our previous study (Sadezky et al., 2006), we reported the identification and characterization of oligomers as main constituents of SOA from gas-phase ozonolysis of small enol ethers. These oligomers contained repeated chain units of the same chemical composition as the main Criegee Intermediates (CI) formed during the ozonolysis reaction, which were CH2O2 (mass 46) for alkyl vinyl ethers (AVE) and C2H4O2 (mass 60) for ethyl propenyl ether (EPE). In the present work, we extend our previous study to another enol ether (ethyl butenyl ether EBE) and a variety of structurally related small alkenes (trans-3-hexene, trans-4-octene and 2,3-dimethyl-2-butene). Experiments have been carried out in a 570 l spherical glass reactor at atmospheric conditions in the absence of seed aerosol. SOA formation was measured by a scanning mobility particle sizer (SMPS). SOA filter samples were collected and chemically characterized off-line by ESI(+)/TOF MS and ESI(+)/TOF MS/MS, and elemental compositions were determined by ESI(+)/FTICR MS and ESI(+)/FTICR MS/MS. The results for all investigated unsaturated compounds are in excellent agreement with the observations of our previous study. Analysis of the collected SOA filter samples reveal the presence of oligomeric compounds in the mass range 200 to 800 u as major constituents. The repeated chain units of these oligomers are shown to systematically have the same chemical composition as the respective main Criegee Intermediate (CI) formed during ozonolysis of the unsaturated compounds, which is C3H6O2 (mass 74) for ethyl butenyl ether (EBE), trans-3-hexene, and 2,3-dimethyl-2-butene, and C4H8O2 (mass 88) for trans-4-octene. Analogous fragmentation pathways among the oligomers formed by gas-phase ozonolysis of the different alkenes and enol ethers in our present and previous study, characterized by successive losses of the respective CI-like chain unit as a neutral fragment, indicate a similar principal structure. In this work, we confirm the basic structure of a linear oligoperoxide - [CH(R)-O-O]n - for all detected oligomers, with the repeated chain unit CH(R)OO corresponding to the respective major CI. The elemental compositions of parent ions, fragment ions and fragmented neutrals determined by accurate mass measurements with the FTICR technique allow us to assign a complete structure to the oligomer molecules. We suggest that the formation of the oligoperoxidic chain units occurs through a new gas-phase reaction mechanism observed for the first time in our present work, which involves the addition of stabilized CI to organic peroxy radicals. Furthermore, copolymerization of CI simultaneously formed in the gas phase from two different unsaturated compounds is shown to occur during the ozonolysis of a mixture of trans-3-hexene and ethyl vinyl ether (EVE), leading to formation of oligomers with mixed chain units C3H6O2 (mass 74) and CH2O2 (mass 46). We therefore suggest oligoperoxide formation by repeated peroxy radical-stabilized CI addition to be a general reaction pathway of small stabilized CI in the gas phase, which represents an alternative way to high-molecular products and thus contributes to SOA formation.

Sadezky, A.; Winterhalter, R.; Kanawati, B.; Römpp, A.; Spengler, B.; Mellouki, A.; Le Bras, G.; Chaimbault, P.; Moortgat, G. K.

2008-05-01

447

Thermolysis of phenethyl phenyl ether: A model of ether linkages in low rank coal  

SciTech Connect

Currently, an area of interest and frustration for coal chemists has been the direct liquefaction of low rank coal. Although low rank coals are more reactive than bituminous coals, they are more difficult to liquefy and offer lower liquefaction yields under conditions optimized for bituminous coals. Solomon, Serio, and co-workers have shown that: in the pyrolysis and liquefaction of low rank coals, a low temperature cross-linking reaction associated with oxygen functional groups occurs before tar evolution. A variety of pretreatments (demineralization, alkylation, and ion-exchange) have been shown to reduce these retrogressive reactions and increase tar yields, but the actual chemical reactions responsible for these processes have not been defined. In order to gain insight into the thermochemical reactions leading to cross-linking in low rank coal, we have undertaken a study of the pyrolysis of oxygen containing coal model compounds. Solid state NMR studies suggest that the alkyl aryl ether linkage may be present in modest amounts in low rank coal. Therefore, in this paper, we will investigate the thermolysis of phenethyl phenyl ether (PPE) as a model of 0-aryl ether linkages found in low rank coal, lignites, and lignin, an evolutionary precursor of coal. Our results have uncovered a new reaction channel that can account for 25% of the products formed. The impact of reaction conditions, including restricted mass transport, on this new reaction pathway and the role of oxygen functional groups in cross-linking reactions will be investigated.

Britt, P.F.; Buchanan, A.C. III; Malcolm, E.A.

1994-09-01

448

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

449

Methyl Tertiary Butyl Ether (MTBE) Groundwater Contamination  

NSDL National Science Digital Library

Methyl tertiary-butyl ether (MTBE), a fuel additive, is highly mobile in groundwater, dissolving and traveling faster than the other petroleum constituents which tend to biodegrade and adsorb to soil particles. This unit will introduce the problem of pollutants as they move through the various soil layers and contaminate the groundwater and challenge the students to investigate the effects of MTBE spills in the environment by researching the available literature on fuel oxygenates and learning their mode of transport through the soil. Experimentally determined data, obtained in lab activities, will facilitate building models of the contamination process of the groundwater. Mathematics modeling will involve the use of spreadsheet analysis of real-world-data obtained online.

450

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

451

Oxidative Cleavage of Diverse Ethers by an Extracellular Fungal Peroxygenase*  

PubMed Central

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 (Km(peroxide), 1.99 ± 0.25 mm; Km(ether), 1.43 ± 0.23 mm; kcat, 720 ± 87 s?1), (b) the cleavage of methyl 4-nitrobenzyl ether in the presence of H218O2 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 [(kH/kD)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.

Kinne, Matthias; Poraj-Kobielska, Marzena; Ralph, Sally A.; Ullrich, Rene; Hofrichter, Martin; Hammel, Kenneth E.

2009-01-01

452

Metal-Ion Complexation by Ionic-Crown Ethers. Progress Report.  

National Technical Information Service (NTIS)

During the third year of this DOE-funded project, 15 new crown ether compounds with pendant ionizable groups have been synthesized. Although a majority of these compounds are crown ether carboxylic acids, two crown ether sulfonic acids, a crown ether phos...

R. A. Bartsch

1982-01-01

453

Synthesis of dialkyl ethers from organotrifluoroborates and acetals.  

PubMed

The formation of ethers by C-O bond formation under harsh basic or acidic conditions is an entrenched synthetic disconnection in organic chemistry. We report a strategic alternative that involves the BF(3).OEt(2)-promoted coupling of stable, easily prepared acetals with widely available potassium aryl-, alkenyl-, and alkynyltrifluoroborates. This fast, operationally simple process offers straightforward access to dialkyl ethers, many of which would be difficult to prepare using classical methods. The use of MOM-protected alcohols and acetal-protected aldehydes enables ether formation without recourse to protecting-group manipulations or strong bases. PMID:20000858

Mitchell, T Andrew; Bode, Jeffrey W

2009-12-23

454

Analytical application of functionalized crown ether - metal complexes  

SciTech Connect

The introduction of functional groups such as lipophilic substituents, non-ionic ligating sites, acid-dissociable groups, chromophores, chiral centers, into skeleton of crown ether, and their immobilization through incorporation into polymer matrix in order to modify crown ethers to versatile analytical reagents in chromatography, ion-selective electrode, colorimetry, etc., is presented. After a brief summary of recent syntheses of functionalized crown ethers, their applications in analytical chemistry are discussed with emphasis on the behavior of metal-complex formation. 103 references, 9 tables.

Takagi, M.; Nakamura, H.

1986-01-01

455

Future role of ethers in U. S. gasoline  

SciTech Connect

The author discusses how the role of oxygenates in the U.S. gasoline pool has reached a turning point in favor of ethers. Ethers are attractive as blending agents because of high octane quality, relatively low vapor pressure, and compatibility with hydrocarbons in the gasoline boiling range. Therefore this class of oxygenates will eventually preempt the position of alcohols as gasoline blending agents. In fact, methanol and cosolvents have already been largely replaced by methyl tertiary butyl ether (MTHE). Ethyl tertiary butyl either (ETBE) could, in the future, eliminate ethanol as a practical gasoline component except for isolated downstream blending operations.

Unzelman, G.H. (Hy Ox Inc., Fallbrook, CA (US))

1989-01-01

456

Biodegradation of bis(1-chloro-2-propyl) ether via initial ether scission and subsequent dehalogenation by Rhodococcus sp. strain DTB.  

PubMed

Rhodococcus sp. strain DTB (DSM 44534) grows on bis(1-chloro-2-propyl) ether (DDE) as sole source of carbon and energy. The non-chlorinated diisopropyl ether and bis(1-hydroxy-2-propyl) ether, however, did not serve as substrates. In ether degradation experiments with dense cell suspensions, 1-chloro-2-propanol and chloroacetone were formed, which indicated that scission of the ether bond is the first step while dehalogenation of the chlorinated C(3)-compounds occurs at a later stage of the degradation pathway. Inhibition of ether scission by methimazole suggested that the first step in degradation is catalyzed by a flavin-dependent enzyme activity. The non-chlorinated compounds 1,2-propanediol, hydroxyacetone, lactate, pyruvate, 1-propanol, propanal, and propionate also supported growth, which suggested that the intermediates 1,2-propanediol and hydroxyacetone are converted to pyruvate or to propionate, which can be channeled into the citric acid cycle by a number of routes. Total release of chloride and growth-yield experiments with DDE and non-chlorinated C(3)-compounds suggested complete biodegradation of the chlorinated ether. PMID:12605291

Moreno Horn, Marcus; Garbe, Leif-Alexander; Tressl, Roland; Adrian, Lorenz; Görisch, Helmut

2003-02-21

457

Synthesis and photochromic properties of tetrakis(3,5-dimethyl-2-thienyl)- and tetrakis(2,5-dimethyl-3-thienyl)ethylenes  

Microsoft Academic Search

Tetrakis(3,5-dimethyl-2-thienyl)ethylene and tetrakis(2,5-dimethyl-3-thienyl)ethylene were obtained from the corresponding dithienyl ketones by the McMurry reaction. The photochromic properties of the compounds obtained were studied.

L. I. Belen'kii; G. P. Gromova; A. V. Kolotaev; B. V. Nabatov; M. M. Krayushkin

2005-01-01

458

Dimethyl sulphoxide protects cells against polypeptide toxins and poliovirus.  

PubMed

The effect of dimethyl sulphoxide and other cryoprotective compounds on the sensitivity of cells to polypeptide toxins and to poliovirus was tested. In the presence of these compounds, which all affect membrane fluidity, the cells were protected against the toxic proteins and against poliovirus. The large protection obtained was not due to reduced binding and endocytosis of the toxins. Apparently, the cryoprotective compounds interfere with the entry of toxins and of the poliovirus genome across the cell membrane. PMID:6331401

Sandvig, K; Madshus, I H; Olsnes, S

1984-05-01

459

Synthesis and crystal structure of (dimethyl sulfoxide)succinatodioxouranium  

Microsoft Academic Search

Dimethylsulfoxide)succinatodioxouranium (UOâCâHâO\\/OF(CHâ)â\\/) has been synthesized and investigated. The polymeric structure of the complex has been established by x-ray diffraction analysis. One carboxylate group of the succinate ion is a bidentate bridging group, and the other is a bidentate chelating group. The coordination of the uranyl ion is completed to five-coordination by means of the oxygen atom of dimethyl sulfoxide. The

R. N. Shchelokov; Yu. N. Mikhailov; I. M. Orlova; A. V. Sergeev; Z. R. Ashurov; M. T. Tashev; N. A. Parpiev

1986-01-01

460

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

461

Dimethyl isotope labeling assisted de novo peptide sequencing  

Microsoft Academic Search

Here, we explore a de novo sequencing strategy in which we combine Lys-N protein digestion with differential isotopic dimethyl\\u000a labeling to facilitate the (de novo) identification of multiply charged peptides in ESI-MS, both under CID and ETD conditions.\\u000a For a large fraction of the Lys-N generated peptides, all primary amines are present at the N-terminal lysine, enabling specific\\u000a labeling of

Marco L. Hennrich; Shabaz Mohammed; A. F. Maarten Altelaar; Albert J. R. Heck

2010-01-01

462

Destruction of dimethyl methylphosphonate using a microwave plasma torch  

Microsoft Academic Search

A microwave plasma torch with a microwave power of 1.2 kW destroys dimethyl methylphosphonate (DMMP) with a destruction rate of 1.14 l\\/h, demonstrating a safe removal capability of stockpiled chemical weapons. The FTIR spectra of the discharge gas from DMMP destruction indicates near perfect elimination of DMMP when the proper amount of oxygen gas is added. This can be confirmed

Han S. Uhm; Soon C. Cho; Yong C. Hong; Yang G. Park; Ju S. Park

2008-01-01

463

Destruction of dimethyl methylphosphonate using a microwave plasma torch  

Microsoft Academic Search

A microwave plasma torch with a microwave power of 1.2 kW destroys dimethyl methylphosphonate (DMMP) with a destruction rate of 1.14 l?h, demonstrating a safe removal capability of stockpiled chemical weapons. The FTIR spectra of the discharge gas from DMMP destruction indicates near perfect elimination of DMMP when the proper amount of oxygen gas is added. This can be confirmed

Han S. Uhm; Soon C. Cho; Yong C. Hong; Yang G. Park; Ju S. Park

2008-01-01

464

Fluorinated Ethers: A New Series of CFC Substitutes.  

National Technical Information Service (NTIS)

The paper discusses fluorinated ethers, a new series of chlorofluorocarbon (CFC) substitutes. Compounds synthesized to produce substances with suitable refrigerant properties have generally left out sulfur, nitrogen, and oxygen. The general result is that...

J. L. Adcock S. B. Mathur W. A. VanHook H. Q. Huang M. Narkhede

1991-01-01

465

POLYBROMINATED DIPHENYL ETHERS IN HOUSE DUST AND CLOTHES DRYER LINT  

EPA Science Inventory

Polybrominated diphenyl ether (PBDE) flame retardants are now considered ubiquitous and persistent pollutants. Few studies have examined the concentrations of these chemicals in the home and here we report measurements of PBDEs in house dust samples collected from the Washington...

466

One-Step Synthesis of Polynitroaliphatic Acetals and Ethers.  

National Technical Information Service (NTIS)

A general, one step, high yield reaction has been demonstrated that produces a variety of polynitroaliphatic acetal and ether products. Reaction condition are mild; purification is simple; and, no costly high pressure of high temperature laboratory techni...

R. E. Cochoy R. R. McGuire S. A. Shackelford

1988-01-01

467

The Chemistry of Carbanions. Xviii. Preparation of Trimethylsilyl Enol Ethers.  

National Technical Information Service (NTIS)

Two procedures for the preparation of trimethylsilyl enol ethers from aldehydes and ketones are described. Reaction of the ketone with chlorotrimethylsilane and triethylamine in dimethylformamide solution usually affords an equilibrium mixture of the trim...

H. O. House L. J. Czuba M. Gall H. D. Olmstead

1968-01-01

468

36. BUILDINGS NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, AND ...  

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

36. BUILDINGS NO. 519, ETHER AND ALCOHOL RECOVERY HOUSE, AND NO. 523, REFRIGERATION PLANT BUILDING, LOOKING EAST. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

469

FLUORINATED ETHERS--A NEW SERIES OF CFC SUBSTITUTES  

EPA Science Inventory

The paper discusses fluorinated ethers, a new series of chlorofluorocarbon (CFC) substitutes. ompounds synthesized to produce substances with suitable refrigerant properties have generally left out sulfur, nitrogen, and oxygen. he reasons for these omissions are many and varied. ...

470

PREDICTIONS OF AZEOTROPES FORMED FROM FLUORINATED ETHERS, ETHANES, AND PROPANES  

EPA Science Inventory

The paper discusses an evaluation of the potential for azeotrope formation and performance for fluorinated ethers, ethanes, and propanes. (NOTE: The synthesis of new non-chlorinated refrigerants expands the base of alternatives for replacing ozone-depleting chlorofluorocarbons (O...

471

Oxidative cleavage of diverse ethers by an extracellular fungal ...  

Treesearch

Experiments with tetrahydrofuran showed the reaction was a two-electron ... the biodegradation of natural and anthropogenic low molecular weight ethers in soils ... We recommend that you also print this page and attach it to the printout of the ...

472

Synthesis of Phthalonitrile Resins Containing Ether and Imide Linkages Specification.  

National Technical Information Service (NTIS)

This invention relates, in general, to high temperature materials and, in particular, to a new class of aromatic phthalonitrile monomers containing ether and imide linkages and their conversion to high temperature thermosetting polymers and copolymers and...

T. M. Keller

1989-01-01

473

Formation of Bis-Chloromethyl Ether in Textile - Finishing Operations.  

National Technical Information Service (NTIS)

Formation of bis-chloromethyl ether (542881) (BCME) was investigated at two unspecified textile industries (SIC-2221). BCME sampling was performed in areas where formaldehyde (50000), and chloride ions were used in the work process. BCME was not detected ...

C. C. Yao G. C. Miller T. Marceleno

1976-01-01

474

Solvent Extraction of Some Single Base Propellants with Diethyl Ether.  

National Technical Information Service (NTIS)

The rate of extraction of soluble material by diethyl ether from some single base propellants was examined. Minor components in the extracts were identified and their effect on the bromination procedure for the determination of DPA was investigated. (Auth...

R. G. Davidson K. J. Diviny F. D. Mcpherson

1972-01-01

475