Science.gov

Sample records for miniature direct methanol

  1. The direct methanol fuel cell

    SciTech Connect

    Halpert, G.; Narayanan, S.R.; Frank, H.

    1995-08-01

    This presentation describes the approach and progress in the ARPA-sponsored effort to develop a Direct Methanol, Liquid-Feed Fuel Cell (DMLFFC) with a solid Polymer Electrolyte Membrane (PEM) for battery replacement in small portable applications. Using Membrane Electrode Assemblies (MEAs) developed by JPL and Giner, significant voltage was demonstrated at relatively high current densities. The DMLFFC utilizes a 3 percent aqueous solution of methanol that is oxidized directly in the anode (fuel) chamber and oxygen (air) in the cathode chamber to produce water and significant power. The only products are water and CO{sub 2}. The ARPA effort is aimed at replacing the battery in the BA 5590 military radio.

  2. Air breathing direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming

    2002-01-01

    An air breathing direct methanol fuel cell is provided with a membrane electrode assembly, a conductive anode assembly that is permeable to air and directly open to atmospheric air, and a conductive cathode assembly that is permeable to methanol and directly contacting a liquid methanol source.

  3. Air Breathing Direct Methanol Fuel Cell

    DOEpatents

    Ren; Xiaoming

    2003-07-22

    A method for activating a membrane electrode assembly for a direct methanol fuel cell is disclosed. The method comprises operating the fuel cell with humidified hydrogen as the fuel followed by running the fuel cell with methanol as the fuel.

  4. Air breathing direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming; Gottesfeld, Shimshon

    2002-01-01

    An air breathing direct methanol fuel cell is provided with a membrane electrode assembly, a conductive anode assembly that is permeable to air and directly open to atmospheric air, and a conductive cathode assembly that is permeable to methanol and directly contacting a liquid methanol source. Water loss from the cell is minimized by making the conductive cathode assembly hydrophobic and the conductive anode assembly hydrophilic.

  5. Direct methanol fuel cell for portable applications

    SciTech Connect

    Valdez, T.I.; Narayanan, S.R.; Frank, H.; Chun, W.

    1997-12-01

    A five cell direct methanol fuel cell stack has been developed at the Jet Propulsion Laboratory. Presently direct methanol fuel cell technology is being incorporated into a system for portable applications. Electrochemical performance and its dependence on flow rate and temperature for a five cell stack are presented. Water transport data, and water transport mechanisms for direct methanol fuel cells are discussed. Stack response to pulse loads has been characterized. Implications of stack performance and operating conditions on system design have been addressed.

  6. Methanol crossover in direct methanol fuel cell systems.

    SciTech Connect

    Pivovar, B. S.; Bender, G.; Davey, J. R.; Zelenay, P.

    2003-01-01

    Direct methanol fuel cells (DMFCs) are currently being investigated for a number of different applications from several milliwatts to near kilowatt size scales (cell phones, laptops, auxiliary power units, etc .). Because methanol has a very high energy density, over 6000 W hr/kg, a DMFC can possibly have greatly extended lifetimes compared to the batteries, doesn't present the storage problems associated with hydrogen fuel cells and can possibly operate more efficiently and cleanly than internal combustion engines.

  7. Methods of conditioning direct methanol fuel cells

    DOEpatents

    Rice, Cynthia; Ren, Xiaoming; Gottesfeld, Shimshon

    2005-11-08

    Methods for conditioning the membrane electrode assembly of a direct methanol fuel cell ("DMFC") are disclosed. In a first method, an electrical current of polarity opposite to that used in a functioning direct methanol fuel cell is passed through the anode surface of the membrane electrode assembly. In a second method, methanol is supplied to an anode surface of the membrane electrode assembly, allowed to cross over the polymer electrolyte membrane of the membrane electrode assembly to a cathode surface of the membrane electrode assembly, and an electrical current of polarity opposite to that in a functioning direct methanol fuel cell is drawn through the membrane electrode assembly, wherein methanol is oxidized at the cathode surface of the membrane electrode assembly while the catalyst on the anode surface is reduced. Surface oxides on the direct methanol fuel cell anode catalyst of the membrane electrode assembly are thereby reduced.

  8. Single passive direct methanol fuel cell supplied with pure methanol

    NASA Astrophysics Data System (ADS)

    Feng, Ligang; Zhang, Jing; Cai, Weiwei; Liang, Liang; Xing, Wei; Liu, Changpeng

    2011-03-01

    A new single passive direct methanol fuel cell (DMFC) supplied with pure methanol is designed, assembled and tested using a pervaporation membrane (PM) to control the methanol transport. The effect of the PM size on the fuel cell performances and the constant current discharge of the fuel cell with one-fueling are studied. The results show that the fuel cell with PM 9 cm2 can yield a maximum power density of about 21 mW cm-2, and a stable performances at a discharge current of 100 mA can last about 45 h. Compared with DMFC supplied with 3 M methanol solution, the energy density provided by this new DMFC has increased about 6 times.

  9. Enhanced methanol utilization in direct methanol fuel cell

    DOEpatents

    Ren, Xiaoming; Gottesfeld, Shimshon

    2001-10-02

    The fuel utilization of a direct methanol fuel cell is enhanced for improved cell efficiency. Distribution plates at the anode and cathode of the fuel cell are configured to distribute reactants vertically and laterally uniformly over a catalyzed membrane surface of the fuel cell. A conductive sheet between the anode distribution plate and the anodic membrane surface forms a mass transport barrier to the methanol fuel that is large relative to a mass transport barrier for a gaseous hydrogen fuel cell. In a preferred embodiment, the distribution plate is a perforated corrugated sheet. The mass transport barrier may be conveniently increased by increasing the thickness of an anode conductive sheet adjacent the membrane surface of the fuel cell.

  10. Advances in direct oxidation methanol fuel cells

    NASA Technical Reports Server (NTRS)

    Surampudi, S.; Narayanan, S. R.; Vamos, E.; Frank, H.; Halpert, G.; Laconti, Anthony B.; Kosek, J.; Prakash, G. K. Surya; Olah, G. A.

    1993-01-01

    Fuel cells that can operate directly on fuels such as methanol are attractive for low to medium power applications in view of their low weight and volume relative to other power sources. A liquid feed direct methanol fuel cell has been developed based on a proton exchange membrane electrolyte and Pt/Ru and Pt catalyzed fuel and air/O2 electrodes, respectively. The cell has been shown to deliver significant power outputs at temperatures of 60 to 90 C. The cell voltage is near 0.5 V at 300 mA/cm(exp 2) current density and an operating temperature of 90 C. A deterrent to performance appears to be methanol crossover through the membrane to the oxygen electrode. Further improvements in performance appear possible by minimizing the methanol crossover rate.

  11. Methanol Oxidation on Pt3Sn(111) for Direct Methanol Fuel Cells: Methanol Decomposition.

    PubMed

    Lu, Xiaoqing; Deng, Zhigang; Guo, Chen; Wang, Weili; Wei, Shuxian; Ng, Siu-Pang; Chen, Xiangfeng; Ding, Ning; Guo, Wenyue; Wu, Chi-Man Lawrence

    2016-05-18

    PtSn alloy, which is a potential material for use in direct methanol fuel cells, can efficiently promote methanol oxidation and alleviate the CO poisoning problem. Herein, methanol decomposition on Pt3Sn(111) was systematically investigated using periodic density functional theory and microkinetic modeling. The geometries and energies of all of the involved species were analyzed, and the decomposition network was mapped out to elaborate the reaction mechanisms. Our results indicated that methanol and formaldehyde were weakly adsorbed, and the other derivatives (CHxOHy, x = 1-3, y = 0-1) were strongly adsorbed and preferred decomposition rather than desorption on Pt3Sn(111). The competitive methanol decomposition started with the initial O-H bond scission followed by successive C-H bond scissions, (i.e., CH3OH → CH3O → CH2O → CHO → CO). The Brønsted-Evans-Polanyi relations and energy barrier decomposition analyses identified the C-H and O-H bond scissions as being more competitive than the C-O bond scission. Microkinetic modeling confirmed that the vast majority of the intermediates and products from methanol decomposition would escape from the Pt3Sn(111) surface at a relatively low temperature, and the coverage of the CO residue decreased with an increase in the temperature and decrease in partial methanol pressure.

  12. A self-sustained, complete and miniaturized methanol fuel processor for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Yang, Mei; Jiao, Fengjun; Li, Shulian; Li, Hengqiang; Chen, Guangwen

    2015-08-01

    A self-sustained, complete and miniaturized methanol fuel processor has been developed based on modular integration and microreactor technology. The fuel processor is comprised of one methanol oxidative reformer, one methanol combustor and one two-stage CO preferential oxidation unit. Microchannel heat exchanger is employed to recover heat from hot stream, miniaturize system size and thus achieve high energy utilization efficiency. By optimized thermal management and proper operation parameter control, the fuel processor can start up in 10 min at room temperature without external heating. A self-sustained state is achieved with H2 production rate of 0.99 Nm3 h-1 and extremely low CO content below 25 ppm. This amount of H2 is sufficient to supply a 1 kWe proton exchange membrane fuel cell. The corresponding thermal efficiency of whole processor is higher than 86%. The size and weight of the assembled reactors integrated with microchannel heat exchangers are 1.4 L and 5.3 kg, respectively, demonstrating a very compact construction of the fuel processor.

  13. Design and Operation of an Electrochemical Methanol Concentration Sensor for Direct Methanol Fuel Cell Systems

    NASA Technical Reports Server (NTRS)

    Narayanan, S. R.; Valdez, T. I.; Chun, W.

    2000-01-01

    The development of a 150-Watt packaged power source based on liquid feed direct methanol fuel cells is being pursued currently at the Jet propulsion Laboratory for defense applications. In our studies we find that the concentration of methanol in the fuel circulation loop affects the electrical performance and efficiency the direct methanol fuel cell systems significantly. The practical operation of direct methanol fuel cell systems, therefore, requires accurate monitoring and control of methanol concentration. The present paper reports on the principle and demonstration of an in-house developed electrochemical sensor suitable for direct methanol fuel cell systems.

  14. Selectivity of Direct Methanol Fuel Cell Membranes.

    PubMed

    Aricò, Antonino S; Sebastian, David; Schuster, Michael; Bauer, Bernd; D'Urso, Claudia; Lufrano, Francesco; Baglio, Vincenzo

    2015-11-24

    Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion(®) were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate-PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA) was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC). The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA) was higher than the benchmark Nafion(®) 115-based MEA (77 mW·cm(-2) vs. 64 mW·cm(-2)). This result was due to a lower methanol crossover (47 mA·cm(-2) equivalent current density for s-PEEK vs. 120 mA·cm(-2) for Nafion(®) 115 at 60 °C as recorded at OCV with 2 M methanol) and a suitable area specific resistance (0.15 Ohm cm² for s-PEEK vs. 0.22 Ohm cm² for Nafion(®) 115).

  15. Selectivity of Direct Methanol Fuel Cell Membranes

    PubMed Central

    Aricò, Antonino S.; Sebastian, David; Schuster, Michael; Bauer, Bernd; D’Urso, Claudia; Lufrano, Francesco; Baglio, Vincenzo

    2015-01-01

    Sulfonic acid-functionalized polymer electrolyte membranes alternative to Nafion® were developed. These were hydrocarbon systems, such as blend sulfonated polyetheretherketone (s-PEEK), new generation perfluorosulfonic acid (PFSA) systems, and composite zirconium phosphate–PFSA polymers. The membranes varied in terms of composition, equivalent weight, thickness, and filler and were investigated with regard to their methanol permeation characteristics and proton conductivity for application in direct methanol fuel cells. The behavior of the membrane electrode assemblies (MEA) was investigated in fuel cell with the aim to individuate a correlation between membrane characteristics and their performance in a direct methanol fuel cell (DMFC). The power density of the DMFC at 60 °C increased according to a square root-like function of the membrane selectivity. This was defined as the reciprocal of the product between area specific resistance and crossover. The power density achieved at 60 °C for the most promising s-PEEK-based membrane-electrode assembly (MEA) was higher than the benchmark Nafion® 115-based MEA (77 mW·cm−2 vs. 64 mW·cm−2). This result was due to a lower methanol crossover (47 mA·cm−2 equivalent current density for s-PEEK vs. 120 mA·cm−2 for Nafion® 115 at 60 °C as recorded at OCV with 2 M methanol) and a suitable area specific resistance (0.15 Ohm cm2 for s-PEEK vs. 0.22 Ohm cm2 for Nafion® 115). PMID:26610582

  16. Lightweight Stacks of Direct Methanol Fuel Cells

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram; Valdez, Thomas

    2004-01-01

    An improved design concept for direct methanol fuel cells makes it possible to construct fuel-cell stacks that can weigh as little as one-third as much as do conventional bipolar fuel-cell stacks of equal power. The structural-support components of the improved cells and stacks can be made of relatively inexpensive plastics. Moreover, in comparison with conventional bipolar fuel-cell stacks, the improved fuel-cell stacks can be assembled, disassembled, and diagnosed for malfunctions more easily. These improvements are expected to bring portable direct methanol fuel cells and stacks closer to commercialization. In a conventional bipolar fuel-cell stack, the cells are interspersed with bipolar plates (also called biplates), which are structural components that serve to interconnect the cells and distribute the reactants (methanol and air). The cells and biplates are sandwiched between metal end plates. Usually, the stack is held together under pressure by tie rods that clamp the end plates. The bipolar stack configuration offers the advantage of very low internal electrical resistance. However, when the power output of a stack is only a few watts, the very low internal resistance of a bipolar stack is not absolutely necessary for keeping the internal power loss acceptably low.

  17. Recent Studies on Methanol Crossover in Liquid-Feed Direct Methanol Fuel Cells

    NASA Technical Reports Server (NTRS)

    Valdez, T. I.; Narayanan, S. R.

    2000-01-01

    In this work, the effects of methanol crossover and airflow rates on the cathode potential of an operating direct methanol fuel cell are explored. Techniques for quantifying methanol crossover in a fuel cell and for separating the electrical performance of each electrode in a fuel cell are discussed. The effect of methanol concentration on cathode potential has been determined to be significant. The cathode is found to be mass transfer limited when operating on low flow rate air and high concentrations of methanol. Improvements in cathode structure and operation at low methanol concentration have been shown to result in improved cell performance.

  18. Improved Direct Methanol Fuel Cell Stack

    SciTech Connect

    Wilson, Mahlon S.; Ramsey, John C.

    2005-03-08

    A stack of direct methanol fuel cells exhibiting a circular footprint. A cathode and anode manifold, tie-bolt penetrations and tie-bolts are located within the circular footprint. Each fuel cell uses two graphite-based plates. One plate includes a cathode active area that is defined by serpentine channels connecting the inlet and outlet cathode manifold. The other plate includes an anode active area defined by serpentine channels connecting the inlet and outlet of the anode manifold, where the serpentine channels of the anode are orthogonal to the serpentine channels of the cathode. Located between the two plates is the fuel cell active region.

  19. A micro direct methanol fuel cell demonstrator

    NASA Astrophysics Data System (ADS)

    Wozniak, Konrad; Johansson, David; Bring, Martin; Sanz-Velasco, Anke; Enoksson, Peter

    2004-09-01

    The demand for compact power sources with high energy density is increasing. A direct methanol fuel cell (DMFC) is a renewable energy source which works at near room temperature, and allows for easier liquid fuel storage, which makes it a potential candidate. We report the design, fabrication and characterization of a self-driven DMFC made by micromachining techniques and macro-assembly. Several designs were created on the basis of state-of-the-art DMFCs. A simplified mathematical model was used mainly to design the flow channels and verify the polarization curves, which reveal the output power of a cell. Silicon was used as a substrate for the fabrication of electrodes, and the membrane electrode assembly was provided by Ion Power, Inc. A 0.25 cm2 cell showed a performance of 0.29 mW cm-2 and an open circuit voltage of 0.7 V. Ten microliters of 6 M methanol solution is sufficient to operate the cell for more than 1 h.

  20. Direct methanol fuel cell and system

    DOEpatents

    Wilson, Mahlon S.

    2004-10-26

    A fuel cell having an anode and a cathode and a polymer electrolyte membrane located between anode and cathode gas diffusion backings uses a methanol vapor fuel supply. A permeable polymer electrolyte membrane having a permeability effective to sustain a carbon dioxide flux equivalent to at least 10 mA/cm.sup.2 provides for removal of carbon dioxide produced at the anode by reaction of methanol with water. Another aspect of the present invention includes a superabsorpent polymer material placed in proximity to the anode gas diffusion backing to hold liquid methanol or liquid methanol solution without wetting the anode gas diffusion backing so that methanol vapor from the liquid methanol or liquid methanol-water solution is supplied to the membrane.

  1. Methanol-tolerant cathode catalyst composite for direct methanol fuel cells

    DOEpatents

    Zhu, Yimin; Zelenay, Piotr

    2006-09-05

    A direct methanol fuel cell (DMFC) having a methanol fuel supply, oxidant supply, and its membrane electrode assembly (MEA) formed of an anode electrode and a cathode electrode with a membrane therebetween, a methanol oxidation catalyst adjacent the anode electrode and the membrane, an oxidant reduction catalyst adjacent the cathode electrode and the membrane, comprises an oxidant reduction catalyst layer of Pt.sub.3Cr/C so that oxidation at the cathode of methanol that crosses from the anode through the membrane to the cathode is reduced with a concomitant increase of net electrical potential at the cathode electrode.

  2. Methanol-Tolerant Cathode Catalyst Composite For Direct Methanol Fuel Cells

    DOEpatents

    Zhu, Yimin; Zelenay, Piotr

    2006-03-21

    A direct methanol fuel cell (DMFC) having a methanol fuel supply, oxidant supply, and its membrane electrode assembly (MEA) formed of an anode electrode and a cathode electrode with a membrane therebetween, a methanol oxidation catalyst adjacent the anode electrode and the membrane, an oxidant reduction catalyst adjacent the cathode electrode and the membrane, comprises an oxidant reduction catalyst layer of a platinum-chromium alloy so that oxidation at the cathode of methanol that crosses from the anode through the membrane to the cathode is reduced with a concomitant increase of net electrical potential at the cathode electrode.

  3. Integrated anode structure for passive direct methanol fuel cells with neat methanol operation

    NASA Astrophysics Data System (ADS)

    Wu, Huijuan; Zhang, Haifeng; Chen, Peng; Guo, Jing; Yuan, Ting; Zheng, Junwei; Yang, Hui

    2014-02-01

    A microporous titanium plate based integrated anode structure (Ti-IAS) suitable for passive direct methanol fuel cells (DMFCs) fueled with neat methanol is reported. This anode structure incorporates a porous titanium plate as a methanol mass transfer barrier and current collector, pervaporation film for passively vaporizing methanol, vaporous methanol cavity for evenly distributing fuel, and channels for carbon dioxide venting. With the effective control of methanol delivery rate, the Ti-IAS based DMFC allows the direct use of neat methanol as the fuel source. In the meantime, the required water for methanol-oxidation reaction at the anode can also be fully recovered from the cathode with the help of the highly hydrophobic microporous layer in the cathode. DMFCs incorporating this new anode structure exhibit a power density as high as 40 mW cm-2 and a high volumetric energy density of 489 Wh L-1 operating with neat methanol and at 25 °C. Importantly, no obvious performance degradation of the passive DMFC system is observed after more than 90 h of continuous operation. The experimental results reveal that the compact DMFC based on the Ti-IAS exhibits a substantial potential as power sources for portable applications.

  4. Recovery Act: Advanced Direct Methanol Fuel Cell for Mobile Computing

    SciTech Connect

    Fletcher, James H.; Cox, Philip; Harrington, William J; Campbell, Joseph L

    2013-09-03

    ABSTRACT Project Title: Recovery Act: Advanced Direct Methanol Fuel Cell for Mobile Computing PROJECT OBJECTIVE The objective of the project was to advance portable fuel cell system technology towards the commercial targets of power density, energy density and lifetime. These targets were laid out in the DOE’s R&D roadmap to develop an advanced direct methanol fuel cell power supply that meets commercial entry requirements. Such a power supply will enable mobile computers to operate non-stop, unplugged from the wall power outlet, by using the high energy density of methanol fuel contained in a replaceable fuel cartridge. Specifically this project focused on balance-of-plant component integration and miniaturization, as well as extensive component, subassembly and integrated system durability and validation testing. This design has resulted in a pre-production power supply design and a prototype that meet the rigorous demands of consumer electronic applications. PROJECT TASKS The proposed work plan was designed to meet the project objectives, which corresponded directly with the objectives outlined in the Funding Opportunity Announcement: To engineer the fuel cell balance-of-plant and packaging to meet the needs of consumer electronic systems, specifically at power levels required for mobile computing. UNF used existing balance-of-plant component technologies developed under its current US Army CERDEC project, as well as a previous DOE project completed by PolyFuel, to further refine them to both miniaturize and integrate their functionality to increase the system power density and energy density. Benefits of UNF’s novel passive water recycling MEA (membrane electrode assembly) and the simplified system architecture it enabled formed the foundation of the design approach. The package design was hardened to address orientation independence, shock, vibration, and environmental requirements. Fuel cartridge and fuel subsystems were improved to ensure effective fuel

  5. Assessment of methanol electro-oxidation for direct methanol-air fuel cells

    SciTech Connect

    Fritts, S.D.; Sen, R.K.

    1988-07-01

    The Office of Energy Storage and Distribution of the US Department of Energy (DOE) supports the development of a methanol-air fuel cell for transportation application. The approach used at Los Alamos National Laboratory converts the methanol fuel to a hydrogen-rich gas in a reformer, then operates the fuel cell on hydrogen and air. The reformer tends to be bulky (raising vehicle packaging problems), has a long startup period, and is not well suited for the transient operation required in a vehicle. Methanol, however, can be oxidized electrochemically in the fuel cell. If this process can be conducted efficiently, a direct methanol-air fuel cell can be used, which does not require a reformer. The objective of this study is to assess the potential of developing a suitable catalyst for the direct electrochemical oxidation of methanol. The primary conclusion of this study is that no acceptable catalysts exist can efficiently oxidize methanol electrochemically and have the desired cost and lifetime for vehicle applications. However, recent progress in understanding the mechanism of methanol oxidation indicates that a predictive base can be developed to search for methanol oxidation catalysts and can be used to methodically develop improved catalysts. Such an approach is strongly recommended. The study also recommends that until further progress in developing high-performance catalysts is achieved, research in cell design and testing is not warranted. 43 refs., 12 figs., 1 tab.

  6. Thermodynamic properties of direct methanol polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Seong, Ji Yun; Bae, Young Chan; Sun, Yang Kook

    A new semi-empirical model is established to describe the cell voltage of a direct methanol fuel cell (DMFC) as a function of current density. The model equation is validated experimental data over a wide range of a methanol concentration and temperatures. A number of existing models are semi-empirical. They, however, have a serious mathematical defect. When the current density, j, becomes zero, the equation should reduce to the open circuit voltage, E0. These models, however, do not meet the mathematical boundary condition. The proposed model focuses on very unfavorable conditions for the cell operation, i.e. low methanol solution concentrations and relatively low cell temperatures. A newly developed semi-empirical equation with reasonable boundary conditions includes the methanol crossover effect that plays a major role in determining the cell voltage of DMFC. Also, it contains methanol activity based on thermodynamic functions to represent methanol crossover effect.

  7. Direct methanol feed fuel cell and system

    NASA Technical Reports Server (NTRS)

    Surampudi, Subbarao (Inventor); Frank, Harvey A. (Inventor); Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Jeffries-Nakamura, Barbara (Inventor); Kindler, Andrew (Inventor); Halpert, Gerald (Inventor)

    2004-01-01

    Improvements to non acid methanol fuel cells include new formulations for materials. The platinum and ruthenium are more exactly mixed together. Different materials are substituted for these materials. The backing material for the fuel cell electrode is specially treated to improve its characteristics. A special sputtered electrode is formed which is extremely porous.

  8. Direct methanol feed fuel cell and system

    NASA Technical Reports Server (NTRS)

    Surampudi, Subbarao (Inventor); Frank, Harvey A. (Inventor); Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Jeffries-Nakamura, Barbara (Inventor); Kindler, Andrew (Inventor); Halpert, Gerald (Inventor)

    2008-01-01

    Improvements to non acid methanol fuel cells include new formulations for materials. The platinum and ruthenium are more exactly mixed together. Different materials are substituted for these materials. The backing material for the fuel cell electrode is specially treated to improve its characteristics. A special sputtered electrode is formed which is extremely porous.

  9. Direct methanol feed fuel cell and system

    NASA Technical Reports Server (NTRS)

    Surampudi, Subbarao (Inventor); Frank, Harvey A. (Inventor); Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Jeffries-Nakamura, Barbara (Inventor); Kindler, Andrew (Inventor); Halpert, Gerald (Inventor)

    2001-01-01

    Improvements to non acid methanol fuel cells include new formulations for materials. The platinum and ruthenium are more exactly mixed together. Different materials are substituted for these materials. The backing material for the fuel cell electrode is specially treated to improve its characteristics. A special sputtered electrode is formed which is extremely porous.

  10. Direct methanol feed fuel cell and system

    NASA Technical Reports Server (NTRS)

    Surampudi, Subbarao (Inventor); Frank, Harvey A. (Inventor); Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Jeffries-Nakamura, Barbara (Inventor); Kindler, Andrew (Inventor); Halpert, Gerald (Inventor)

    2000-01-01

    Improvements to non-acid methanol fuel cells include new formulations for materials. The platinum and ruthenium are more exactly mixed together. Different materials are substituted for these materials. The backing material for the fuel cell electrode is specially treated to improve its characteristics. A special sputtered electrode is formed which is extremely porous.

  11. Towards neat methanol operation of direct methanol fuel cells: a novel self-assembled proton exchange membrane.

    PubMed

    Li, Jing; Cai, Weiwei; Ma, Liying; Zhang, Yunfeng; Chen, Zhangxian; Cheng, Hansong

    2015-04-18

    We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.

  12. Direct Methanol Fuel Cell (DMFC) Battery Replacement Program

    DTIC Science & Technology

    2013-01-29

    studies on performance degradation of Catalysts and Nafion™ Membrane Functional Groups in Direct Methanol Fuel Cells, IN PREP (06 2013) TOTAL: 1 Books... 18 Single Cell: Progress...31 Laser Activated Membrane Introduction Mass Spectrometry (LAMIMS) .................................... 37 Future Work (internally

  13. TOPICAL REVIEW: Micromachined polymer electrolyte membrane and direct methanol fuel cells—a review

    NASA Astrophysics Data System (ADS)

    Nguyen, Nam-Trung; Chan, Siew Hwa

    2006-04-01

    This review reports recent progress of the development of micromachined membrane-based fuel cells. The review first discusses the scaling law applied to this type of fuel cell. Impacts of miniaturization on the performance of membrane-based fuel cells are highlighted. This review includes only the two most common micro fuel cell types: proton exchange membrane micro fuel cells (PEMµFC) and direct methanol micro fuel cells (DMµFC). Furthermore, we only consider fuel cells with the active area of a single cell less than 1 square inch. Since the working principles of these fuel cell types are well known, the review only focuses on the choice of material and the design consideration of the components in the miniature fuel cell. Next, we compare and discuss the performance of different micro fuel cells published recently in the literature. Finally, this review gives an outlook on possible future development of micro fuel cell research.

  14. Direct methanol feed fuel cell and system

    NASA Technical Reports Server (NTRS)

    Surampudi, Subbarao (Inventor); Frank, Harvey A. (Inventor); Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Jeffries-Nakamura, Barbara (Inventor); Kindler, Andrew (Inventor); Halpert, Gerald (Inventor)

    2009-01-01

    Improvements to non acid methanol fuel cells include new formulations for materials. The platinum and ruthenium are more exactly mixed together. Different materials are substituted for these materials. The backing material for the fuel cell electrode is specially treated to improve its characteristics. A special sputtered electrode is formed which is extremely porous. The fuel cell system also comprises a fuel supplying part including a meter which meters an amount of fuel which is used by the fuel cell, and controls the supply of fuel based on said metering.

  15. Real-time mass spectrometric study of the methanol crossover in a direct methanol fuel cell

    SciTech Connect

    Wang, J.T.; Wasmus, S.; Savinell, R.F.

    1996-04-01

    The products of methanol crossover through the acid-doped polybenzimidazole polymer electrolyte membrane (PBI PEM) to the cathode of a prototype direct methanol fuel cell (DMFC) were analyzed using multipurpose electrochemical mass spectrometry (MPEMS) coupled to the cathode exhaust gas outlet. It was found that the methanol crossing over reacts almost quantitatively to CO{sub 2} at the cathode with the platinum of the cathode acting as a heterogeneous catalyst. The cathode open-circuit potential is inversely proportional to the amount of CO{sub 2} formed. A poisoning effect on the oxygen reduction also was found. Methods for the estimation of the methanol crossover rate at operating fuel cells are suggested.

  16. Novel Materials for High Efficiency Direct Methanol Fuel Cells

    SciTech Connect

    Carson, Stephen; Mountz, David; He, Wensheng; Zhang, Tao

    2013-12-31

    Direct methanol fuel cell membranes were developed using blends of different polyelectrolytes with PVDF. The membranes showed complex relationships between polyelectrolyte chemistry, morphology, and processing. Although the PVDF grade was found to have little effect on the membrane permselectivity, it does impact membrane conductivity and methanol permeation values. Other factors, such as varying the polyelectrolyte polarity, using varying crosslinking agents, and adjusting the equivalent weight of the membranes impacted methanol permeation, permselectivity, and areal resistance. We now understand, within the scope of the project work completed, how these inter-related performance properties can be tailored to achieve a balance of performance.

  17. Studies on an ultrasonic atomization feed direct methanol fuel cell.

    PubMed

    Wu, Chaoqun; Liu, Linghao; Tang, Kai; Chen, Tao

    2017-01-01

    Direct methanol fuel cell (DMFC) is promising as an energy conversion device for the replacement of conventional chemical cell in future, owing to its convenient fuel storage, high energy density and low working temperature. The development of DMFC technology is currently limited by catalyst poison and methanol crossover. To alleviate the methanol crossover, a novel fuel supply system based on ultrasonic atomization is proposed. Experimental investigations on this fuel supply system to evaluate methanol permeation rates, open circuit voltages (OCVs) and polarization curves under a series of conditions have been carried out and reported in this paper. In comparison with the traditional liquid feed DMFC system, it can be found that the methanol crossover under the ultrasonic atomization feed system was significantly reduced because the DMFC reaches a large stable OCV value. Moreover, the polarization performance does not vary significantly with the liquid feed style. Therefore, the cell fed by ultrasonic atomization can be operated with a high concentration methanol to improve the energy density of DMFC. Under the supply condition of relatively high concentration methanol such as 4M and 8M, the maximum power density fed by ultrasonic atomization is higher than liquid by 6.05% and 12.94% respectively.

  18. Improved Flow-Field Structures for Direct Methanol Fuel Cells

    SciTech Connect

    Gurau, Bogdan

    2013-05-31

    The direct methanol fuel cell (DMFC) is ideal if high energy-density liquid fuels are required. Liquid fuels have advantages over compressed hydrogen including higher energy density and ease of handling. Although state-of-the-art DMFCs exhibit manageable degradation rates, excessive fuel crossover diminishes system energy and power density. Although use of dilute methanol mitigates crossover, the concomitant lowering of the gross fuel energy density (GFED) demands a complex balance-of-plant (BOP) that includes higher flow rates, external exhaust recirculation, etc. An alternative approach is redesign of the fuel delivery system to accommodate concentrated methanol. NuVant Systems Inc. (NuVant) will maximize the GFED by design and assembly of a DMFC that uses near neat methanol. The approach is to tune the diffusion of highly concentrated methanol (to the anode catalytic layer) to the back-diffusion of water formed at the cathode (i.e. in situ generation of dilute methanol at the anode layer). Crossover will be minimized without compromising the GFED by innovative integration of the anode flow-field and the diffusion layer. The integrated flow-field-diffusion-layers (IFDLs) will widen the current and potential DMFC operating ranges and enable the use of cathodes optimized for hydrogen-air fuel cells.

  19. Towards operating direct methanol fuel cells with highly concentrated fuel

    NASA Astrophysics Data System (ADS)

    Zhao, T. S.; Yang, W. W.; Chen, R.; Wu, Q. X.

    A significant advantage of direct methanol fuel cells (DMFCs) is the high specific energy of the liquid fuel, making it particularly suitable for portable and mobile applications. Nevertheless, conventional DMFCs have to be operated with excessively diluted methanol solutions to limit methanol crossover and the detrimental consequences. Operation with diluted methanol solutions significantly reduces the specific energy of the power pack and thereby prevents it from competing with advanced batteries. In view of this fact, there exists a need to improve conventional DMFC system designs, including membrane electrode assemblies and the subsystems for supplying/removing reactants/products, so that both the cell performance and the specific energy can be simultaneously maximized. This article provides a comprehensive review of past efforts on the optimization of DMFC systems that operate with concentrated methanol. Based on the discussion of the key issues associated with transport of the reactants/products, the strategies to manage the supply/removal of the reactants/products in DMFC operating with highly concentrated methanol are identified. With these strategies, the possible approaches to achieving the goal of concentrated fuel operation are then proposed. Past efforts in the management of the reactants/products for implementing each of the approaches are also summarized and reviewed.

  20. On direct and indirect methanol fuel cells for transportation applications

    SciTech Connect

    Ren, Xiaoming; Wilson, M.S.; Gottesfeld, S.

    1995-09-01

    Power densities in electrolyte Direct Methanol Fuel Cells have been achieved which are only three times lower than those achieved with similar reformate/air fuel cells. Remaining issues are: improved anode catalyst activity, demonstrated long-term stable performance, and high fuel efficiencies.

  1. On direct and indirect methanol fuel cells for transportation applications

    SciTech Connect

    Gottesfield, S.

    1996-04-01

    Research on direct oxidation methanol fuel cells (DMFCs) and polymer electrolyte fuel cells (PEFCs) is discussed. Systems considered for transportation applications are addressed. The use of platinum/ruthenium anode electrocatalysts and platinum cathode electrocatalysts in polymer electrolyte DMFCs has resulted in significant performance enhancements.

  2. Low Crossover Polymer Electrolyte Membranes for Direct Methanol Fuel Cells

    NASA Technical Reports Server (NTRS)

    Prakash, G. K. Surya; Smart, Marshall; Atti, Anthony R.; Olah, George A.; Narayanan, S. R.; Valdez, T.; Surampudi, S.

    1996-01-01

    Direct Methanol Fuel Cells (DMFC's) using polymer electrolyte membranes are promising power sources for portable and vehicular applications. State of the art technology using Nafion(R) 117 membranes (Dupont) are limited by high methanol permeability and cost, resulting in reduced fuel cell efficiencies and impractical commercialization. Therefore, much research in the fuel cell field is focused on the preparation and testing of low crossover and cost efficient polymer electrolyte membranes. The University of Southern California in cooperation with the Jet Propulsion Laboratory is focused on development of such materials. Interpenetrating polymer networks are an effective method used to blend polymer systems without forming chemical links. They provide the ability to modify physical and chemical properties of polymers by optimizing blend compositions. We have developed a novel interpenetrating polymer network based on poly (vinyl - difluoride)/cross-linked polystyrenesulfonic acid polymer composites (PVDF PSSA). Sulfonation of polystyrene accounts for protonic conductivity while the non-polar, PVDF backbone provides structural integrity in addition to methanol rejection. Precursor materials were prepared and analyzed to characterize membrane crystallinity, stability and degree of interpenetration. USC JPL PVDF-PSSA membranes were also characterized to determine methanol permeability, protonic conductivity and sulfur distribution. Membranes were fabricated into membrane electrode assemblies (MEA) and tested for single cell performance. Tests include cell performance over a wide range of temperatures (20 C - 90 C) and cathode conditions (ambient Air/O2). Methanol crossover values are measured in situ using an in-line CO2 analyzer.

  3. Performance of direct methanol polymer electrolyte fuel cell

    SciTech Connect

    Shin, Dong Ryul; Jung, Doo Hwan; Lee, Chang Hyeong; Chun, Young Gab

    1996-12-31

    Direct methanol fuel cells (DMFC) using polymer electrolyte membrane are promising candidate for application of portable power sources and transportation applications because they do not require any fuel processing equipment and can be operated at low temperature of 60{degrees}C - 130{degrees}C. Elimination of the fuel processor results in simpler design, higher operation reliability, lower weight volume, and lower capital and operating cost. However, methanol as a fuel is relatively electrochemical inert, so that kinetics of the methanol oxidation is too slow. Platinum and Pt-based binary alloy electrodes have been extensively studied for methanol electro-oxidation in acid electrolyte at ambient and elevated temperatures. Particularly, unsupported carbon Pt-Ru catalyst was found to be superior to the anode of DMFC using a proton exchange membrane electrolyte (Nafion). The objective of this study is to develop the high performance DNTC. This paper summarizes the results from half cell and single cell tests, which focus on the electrode manufacturing process, catalyst selection, and operating conditions of single cell such as methanol concentration, temperature and pressure.

  4. Studies on Methanol Crossover in Liquid-Feed Direct Methanol Pem Fuel Cells

    NASA Technical Reports Server (NTRS)

    Narayanan, S. R.

    1995-01-01

    The performance of liquid feed direct methanol fuel cells using various types of Nafion membranes as the solid polymer electrolyte have been studied. The rate of fuel crossover and electrical performance has been measured for cells with Nafion membranes of various thicknesses and equivalent weights. The crossover rate is found to decrease with increasing thickness and applied current. The dependence of crossover rate on current density can be understood in terms of a simple linear diffusion model which suggests that the crossover rate can be influenced by the electrode structure in addition to the membrane. The studies suggest that Nafion EW 1500 is a very promising alternate to Nafion EW 1100 for direct methanol fuel cells.

  5. Materials and Manufacturing Challenges of Direct Methanol Fuel Cells

    DTIC Science & Technology

    2009-04-27

    SPSf. Figure 5 shows four basic polymers in which benzimidazole (BIm), amino- benzimidazole (ABIm), nitrobenzimidazole (NBIm), and perimidine (PImd...Membranes Based on Sulfonated Polyetheretherketone and Polysulfone Bearing Benzimidazole Side Groups for Fuel Cells,” Electrochemistry Communications...Bearing Benzimidazole Side Groups for Direct Methanol Fuel Cells,” Electrochemical and Solid State Letters, Vol. 10, 2007, p. B70-B73. [12] Fu, Y.-Z

  6. Direct methanol feed fuel cell with reduced catalyst loading

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew (Inventor)

    1999-01-01

    Improvements to direct feed methanol fuel cells include new protocols for component formation. Catalyst-water repellent material is applied in formation of electrodes and sintered before application of ionomer. A membrane used in formation of an electrode assembly is specially pre-treated to improve bonding between catalyst and membrane. The improved electrode and the pre-treated membrane are assembled into a membrane electrode assembly.

  7. Performance, methanol tolerance and stability of Fe-aminobenzimidazole derived catalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Sebastián, David; Serov, Alexey; Artyushkova, Kateryna; Atanassov, Plamen; Aricò, Antonino S.; Baglio, Vincenzo

    2016-07-01

    Highly active and durable non-platinum group metals (non-PGM) catalyst based on iron-nitrogen-carbon (Fe-N-C) for the oxygen reduction reaction (ORR) derived from pyrolyzed Fe-aminobenzimidazole (Fe-ABZIM) was synthesized by sacrificial support method (SSM), and characterized by several physical-chemical techniques: scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller method and X-ray photoelectron spectroscopy. In half-cell electrochemical configuration, the Fe-ABZIM catalyst presented a significant improvement of ORR activity with respect to a recently reported non-PGM formulation based on Fe-aminoantipyrine, with an enhancement of half-wave potential of about 85 mV in O2-saturated sulfuric acid solution. To the moment, the gap with respect to a benchmark Pt/C catalyst was about 90 mV. The Fe-ABZIM catalyst showed a remarkably high tolerance to methanol, resulting in superior ORR performance compared to Pt/C at methanol concentrations higher than 0.02 M. In direct methanol fuel cell (DMFC) good performances were also obtained. A durability test (100 h) at 90 °C, feeding 5 M methanol, was carried out. A certain decrease of performance was recorded, amounting to -0.20 mW cm-2 h-1 at the very beginning of test and -0.05 mW cm-2 h-1 at the end. However, the Fe-ABZIM is more adequate than previously reported formulations in terms of both ORR activity and stability.

  8. Recent advances in high-performance direct methanol fuel cells

    SciTech Connect

    Narayanan, S.R.; Chun, W.; Valdez, T.I.

    1996-12-31

    Direct methanol fuel cells for portable power applications have been advanced significantly under DARPA- and ARO-sponsored programs over the last five years. A liquid-feed direct methanol fuel cell developed under these programs, employs a proton exchange membrane as electrolyte and operates on aqueous solutions of methanol with air or oxygen as the oxidant. Power densities as high as 320 mW/cm{sup 2} have been demonstrated. Demonstration of five-cell stack based on the liquid-feed concept have been successfully performed by Giner Inc. and the Jet Propulsion Laboratory. Over 2000 hours of life-testing have been completed on these stacks. These fuel cells have been also been demonstrated by USC to operate on alternate fuels such as trimethoxymethane, dimethoxymethane and trioxane. Reduction in the parasitic loss of fuel across the fuel cell, a phenomenon termed as {open_quotes}fuel crossover{close_quotes} has been achieved using polymer membranes developed at USC. As a result efficiencies as high as 40% is considered attainable with this type of fuel cell. The state-of-development has reached a point where it is now been actively considered for stationary, portable and transportation applications. The research and development issues have been the subject of several previous articles and the present article is an attempt to summarize the key advances in this technology.

  9. High specific power, direct methanol fuel cell stack

    DOEpatents

    Ramsey, John C.; Wilson, Mahlon S.

    2007-05-08

    The present invention is a fuel cell stack including at least one direct methanol fuel cell. A cathode manifold is used to convey ambient air to each fuel cell, and an anode manifold is used to convey liquid methanol fuel to each fuel cell. Tie-bolt penetrations and tie-bolts are spaced evenly around the perimeter to hold the fuel cell stack together. Each fuel cell uses two graphite-based plates. One plate includes a cathode active area that is defined by serpentine channels connecting the inlet manifold with an integral flow restrictor to the outlet manifold. The other plate includes an anode active area defined by serpentine channels connecting the inlet and outlet of the anode manifold. Located between the two plates is the fuel cell active region.

  10. Novel anode catalyst for direct methanol fuel cells.

    PubMed

    Basri, S; Kamarudin, S K; Daud, W R W; Yaakob, Z; Kadhum, A A H

    2014-01-01

    PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs) but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni) and iron (Fe). Multiwalled carbon nanotubes (MWCNTs) are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV) is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA) tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR). The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2-5 nm) PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g(-1) catalyst.

  11. Novel Anode Catalyst for Direct Methanol Fuel Cells

    PubMed Central

    Basri, S.; Kamarudin, S. K.; Daud, W. R. W.; Yaakob, Z.; Kadhum, A. A. H.

    2014-01-01

    PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs) but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni) and iron (Fe). Multiwalled carbon nanotubes (MWCNTs) are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV) is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA) tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR). The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2–5 nm) PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g−1 catalyst. PMID:24883406

  12. New Catalysts for Direct Methanol Oxidation Fuel Cells

    SciTech Connect

    Adzic, Radoslav

    1998-08-01

    A new class of efficient electrocatalytic materials based on platinum - metal oxide systems has been synthetized and characterized by several techniques. Best activity was found with NiWO{sub 4}-, CoWO{sub 4}-, and RuO{sub 2}- sr¡pported platinum catalysts. A very similar activity at room temperature was observed with the electrodes prepared with the catalyst obtained from International Fuel Cells Inc. for the same Pt loading. Surprisingly, the two tungstates per se show a small activity for methanol oxidation without any Pt loading. Synthesis of NiWO{sub 4} and CoWO{sub 4} were carried out by solid-state reactions. FTIR spectroscopy shows that the tungstates contain a certain amount of physically adsorbed water even after heating samples at 200{degrees}C. A direct relationship between the activity for methanol oxidation and the amount of adsorbed water on those oxides has been found. The Ru(0001) single crystal shows a very small activity for CO adsorption and oxidation, in contrast to the behavior of polycrystalline Ru. In situ extended x-ray absorption fine structure spectroscopy (EXAFS) and x-ray absorption near edge spectroscopy (XANES) showed that the OH adsorption on Ru in the Pt-Ru alloy appears to be the limiting step in methanol oxidation. This does not occur for Pt-RuO{SUB 2} electrocatalyst, which explains its advantages over the Pt-Ru alloys. The IFCC electrocatalyst has the properties of the Pt-Ru alloy.

  13. Mass balance research for high electrochemical performance direct methanol fuel cells with reduced methanol crossover at various operating conditions

    NASA Astrophysics Data System (ADS)

    Park, Jun-Young; Lee, Jin-Hwa; Kang, SangKyun; Sauk, Jun-Ho; Song, Inseob

    Mass balance research in direct methanol fuel cells (DMFCs) provides a more practical method in characterizing the mass transport phenomena in a membrane electrode assembly (MEA). This method can be used to measure methanol utilization efficiency, water transport coefficient (WTC), and methanol to electricity conversion rate of a MEA in DMFCs. First, the vital design parameters of a MEA are recognized for achieving high methanol utilization efficiency with increased power density. In particular, the structural adjustment of anode diffusion layer by adding microporous layer (MPL) is a very effective way to decrease WTC with reduced methanol crossover due to the mass transfer limitation in the anode. On the other hand, the cathode MPL in the MEA design can contribute in decreasing methanol crossover. The change of structure of cathode diffusion layer is also found to be a very effective way in improving power density. In contrast, the WTC of DMFC MEAs remains virtually constant in the range of 3.4 and 3.6 irrespective of the change of the cathode GDL. The influence of operating condition on the methanol utilization efficiency, WTC, and methanol to electricity conversion rate is also presented and it is found that these mass balance properties are strongly affected by temperature, current density, methanol concentration, and the stoichiometry of fuel and air.

  14. Bifunctional activation of a direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Kulikovsky, A. A.; Schmitz, H.; Wippermann, K.; Mergel, J.; Fricke, B.; Sanders, T.; Sauer, D. U.

    We report a novel method for performance recovery of direct methanol fuel cells. Lowering of air flow rate below a critical value turns the cell into bifunctional regime, when the oxygen-rich part of the cell generates current while the rest part works in electrolysis mode (electrolytic domain). Upon restoring the normal (super-critical) air flow rate, the galvanic performance of the electrolytic domain increases. This recovery effect is presumably attributed to Pt surface cleaning on the cathode with the simultaneous increase in catalyst utilization on the anode.

  15. Laser direct marking applied to rasterizing miniature Data Matrix Code on aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Xia-Shuang; He, Wei-Ping; Lei, Lei; Wang, Jian; Guo, Gai-Fang; Zhang, Teng-Yun; Yue, Ting

    2016-03-01

    Precise miniaturization of 2D Data Matrix (DM) Codes on Aluminum alloy formed by raster mode laser direct part marking is demonstrated. The characteristic edge over-burn effects, which render vector mode laser direct part marking inadequate for producing precise and readable miniature codes, are minimized with raster mode laser marking. To obtain the control mechanism for the contrast and print growth of miniature DM code by raster laser marking process, the temperature field model of long pulse laser interaction with material is established. From the experimental results, laser average power and Q frequency have an important effect on the contrast and print growth of miniature DM code, and the threshold of laser average power and Q frequency for an identifiable miniature DM code are respectively 3.6 W and 110 kHz, which matches the model well within normal operating conditions. In addition, the empirical model of correlation occurring between laser marking parameters and module size is also obtained, and the optimal processing parameter values for an identifiable miniature DM code of different but certain data size are given. It is also found that an increase of the repeat scanning number effectively improves the surface finish of bore, the appearance consistency of modules, which has benefit to reading. The reading quality of miniature DM code is greatly improved using ultrasonic cleaning in water by avoiding the interference of color speckles surrounding modules.

  16. An algebraic model on the performance of a direct methanol fuel cell with consideration of methanol crossover

    NASA Astrophysics Data System (ADS)

    Yin, Ken-Ming

    An algebraic one-dimensional model on the membrane-electrode-assembly (MEA) of direct methanol fuel cell (DMFC) is proposed. Non-linear regression procedure was imposed on the model to retrieve important parameters: solid polymer electrolyte conductivity κ m, exchange current density of methanol electro-oxidation at anode catalyst surface i oM,ref, and mass diffusivity of methanol in aqueous phase within the porous electrode D a that correspond to the experimentally measured polarization curves. Although numerical iteration is required for a complete solution, the explicit relationships of methanol concentration, methanol crossover rate, oxygen concentration and cell discharge current density do provide a clear picture of the mass transport and electrochemical kinetics within the various porous media in the MEA. It is shown the cathode mixed potential induced by the parallel reactions of oxygen reduction and oxidation of crossover methanol elucidates the potential drop of the cathode and the decrease of the cell open circuit voltage (OCV). Methanol transport in the membrane is described by the diffusion, electro-osmosis, and pressure induced convection. Detailed accounts of the effects of anode methanol and cathode oxygen feed concentrations on the cell discharge performance are given with correlation to the physical structure and chemical compositions of the catalyst layers (CLs).

  17. Improved Anode for a Direct Methanol Fuel Cell

    NASA Technical Reports Server (NTRS)

    Valdez, Thomas; Narayanan, Sekharipuram

    2005-01-01

    A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the

  18. Methanol

    Integrated Risk Information System (IRIS)

    EPA / 635 / R - 11 / 001Fa www.epa.gov / iris TOXICOLOGICAL REVIEW OF METHANOL ( NONCANCER ) ( CAS No . 67 - 56 - 1 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) September 2013 U.S . Environmental Protection Agency Washington , DC ii DISCLAIMER This document

  19. Direct Methanol Fuel Cell Prototype Demonstration for Consumer Electronics Applications

    SciTech Connect

    Carlstrom, Charles, M., Jr.

    2009-07-07

    This report is the final technical report for DOE Program DE-FC36-04GO14301 titled “Direct Methanol Fuel Cell Prototype Demonstration for Consumer Electronics Applications”. Due to the public nature of this report some of the content reported in confidential reports and meetings to the DOE is not covered in detail in this report and some of the content has been normalized to not show actual values. There is a comparison of the projects accomplishments with the objectives, an overview of some of the key subsystem work, and a review of the three levels of prototypes demonstrated during the program. There is also a description of the eventual commercial product and market this work is leading towards. The work completed under this program has significantly increased the understanding of how Direct Methanol Fuel Cells (DMFC) can be deployed successfully to power consumer electronic devices. The prototype testing has demonstrated the benefits a direct methanol fuel cell system has over batteries typically used for powering consumer electronic devices. Three generations of prototypes have been developed and tested for performance, robustness and life. The technologies researched and utilized in the fuel cell stack and related subsystems for these prototypes are leveraged from advances in other industries such as the hydrogen fueled PEM fuel cell industry. The work under this program advanced the state of the art of direct methanol fuel cells. The system developed by MTI micro fuel cells aided by this program differs significantly from conventional DMFC designs and offers compelling advantages in the areas of performance, life, size, and simplicity. The program has progressed as planned resulting in the completion of the scope of work and available funding in December 2008. All 18 of the final P3 prototypes builds have been tested and the results showed significant improvements over P2 prototypes in build yield, initial performance, and durability. The systems have

  20. Thin Film Catalyst Layers for Direct Methanol Fuel Cells

    NASA Technical Reports Server (NTRS)

    Witham, C. K.; Chun, W.; Ruiz, R.; Valdez, T. I.; Narayanan, S. R.

    2000-01-01

    One of the primary obstacles to the widespread use of the direct methanol fuel cell (DMFC) is the high cost of the catalyst. Therefore, reducing the catalyst loading well below the current level of 8-12 mg/cm 2 would be important to commercialization. The current methods for preparation of catalyst layers consisting of catalyst, ionomer and sometimes a hydrophobic additive are applied by either painting, spraying, decal transfer or screen printing processes. Sputter deposition is a coating technique widely used in manufacturing and therefore particularly attractive. In this study we have begun to explore sputtering as a method for catalyst deposition. Present experiments focus on Pt-Ru catalyst layers for the anode.

  1. A miniaturized adaptive microphone array under directional constraint utilizing aggregated microphones.

    PubMed

    Matsumoto, Mitsuharu; Hashimoto, Shuji

    2006-01-01

    This paper introduces a miniaturized microphone array using the Directionally Constrained Minimization of Power (DCMP) method, which utilizes the transfer functions of microphones located at the same place, namely aggregated microphones. The phased microphone array realizes a noise reduction and direction of arrival (DOA) estimation system according to differences in the arrival time, phase shift, and/or the level of the sound wave for each microphone. Hence it is difficult to miniaturize the microphone array. The objective of our research is to miniaturize the system size using aggregated microphones. In this paper, we first show that the phased microphone array system and the proposed aggregated microphone system can be described within the same framework. We then apply a microphone array under directional constraint to the aggregated microphones and compare the proposed method with the microphone array. We show the directional pattern of the aggregated microphones. We also show the experimental results regarding DOA estimation.

  2. Improved Cathode Structure for a Direct Methanol Fuel Cell

    NASA Technical Reports Server (NTRS)

    Valdez, Thomas; Narayanan, Sekharipuram

    2005-01-01

    An improved cathode structure on a membrane/electrode assembly has been developed for a direct methanol fuel cell, in a continuing effort to realize practical power systems containing such fuel cells. This cathode structure is intended particularly to afford better cell performance at a low airflow rate. A membrane/electrode assembly of the type for which the improved cathode structure was developed (see Figure 1) is fabricated in a process that includes brush painting and spray coating of catalyst layers onto a polymer-electrolyte membrane and onto gas-diffusion backings that also act as current collectors. The aforementioned layers are then dried and hot-pressed together. When completed, the membrane/electrode assembly contains (1) an anode containing a fine metal black of Pt/Ru alloy, (2) a membrane made of Nafion 117 or equivalent (a perfluorosulfonic acid-based hydrophilic, proton-conducting ion-exchange polymer), (3) a cathode structure (in the present case, the improved cathode structure described below), and (4) the electrically conductive gas-diffusion backing layers, which are made of Toray 060(TradeMark)(or equivalent) carbon paper containing between 5 and 6 weight percent of poly(tetrafluoroethylene). The need for an improved cathode structure arises for the following reasons: In the design and operation of a fuel-cell power system, the airflow rate is a critical parameter that determines the overall efficiency, cell voltage, and power density. It is desirable to operate at a low airflow rate in order to obtain thermal and water balance and to minimize the size and mass of the system. The performances of membrane/electrode assemblies of prior design are limited at low airflow rates. Methanol crossover increases the required airflow rate. Hence, one way to reduce the required airflow rate is to reduce the effect of methanol crossover. Improvement of the cathode structure - in particular, addition of hydrophobic particles to the cathode - has been

  3. Effect of pervaporation plate thickness on the rate of methanol evaporation in a passive vapor-feed direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Fauzi, N. F. I.; Hasran, U. A.; Kamarudin, S. K.

    2015-09-01

    In a passive vapor-feed direct methanol fuel cell (DMFC), methanol vapor is typically obtained using a pervaporation plate in a process by which liquid methanol contained in the fuel reservoir undergoes a phase change to vapor in the anodic vapor chamber. This work investigates the effect of pervaporation plate thickness on the rate of methanol evaporation using a three-dimensional simulation model developed by varying the plate thickness. A. The rate of methanol evaporation was measured using Darcy's law. The rate of methanol evaporation was found to be inversely proportional to the plate thickness, where the decrease in thickness inevitably lowers the resistance along the plate and consequently increases the methanol transport through the plate. This shows that the plate thickness has a significant influence on the rate of methanol evaporation and thereby plays an important role in improving the performance of the passive vapor-feed direct methanol fuel cell.

  4. A New High-Resolution Direction Finding Architecture Using Photonics and Neural Network Signal Processing for Miniature Air Vehicle Applications

    DTIC Science & Technology

    2015-09-01

    RESOLUTION DIRECTION FINDING ARCHITECTURE USING PHOTONICS AND NEURAL NETWORK SIGNAL PROCESSING FOR MINIATURE AIR VEHICLE APPLICATIONS by Robert...RESOLUTION DIRECTION FINDING ARCHITECTURE USING PHOTONICS AND NEURAL NETWORK SIGNAL PROCESSING FOR MINIATURE AIR VEHICLE APPLICATIONS 5. FUNDING...unlimited 12b. DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) This paper investigates the design of an interferometric direction finding receiver

  5. Nano-Engineered Catalysts for Direct Methanol Fuel Cells

    NASA Technical Reports Server (NTRS)

    Myung, Nosang; Narayanan, Sekharipuram; Wiberg, Dean

    2008-01-01

    Nano-engineered catalysts, and a method of fabricating them, have been developed in a continuing effort to improve the performances of direct methanol fuel cells as candidate power sources to supplant primary and secondary batteries in a variety of portable electronic products. In order to realize the potential for high energy densities (as much as 1.5 W h/g) of direct methanol fuel cells, it will be necessary to optimize the chemical compositions and geometric configurations of catalyst layers and electrode structures. High performance can be achieved when catalyst particles and electrode structures have the necessary small feature sizes (typically of the order of nanometers), large surface areas, optimal metal compositions, high porosity, and hydrophobicity. The present method involves electrodeposition of one or more catalytic metal(s) or a catalytic-metal/polytetrafluoroethylene nanocomposite on an alumina nanotemplate. The alumina nanotemplate is then dissolved, leaving the desired metal or metal/polytetrafluoroethylene-composite catalyst layer. Unlike some prior methods of making fine metal catalysts, this method does not involve processing at elevated temperature; all processing can be done at room temperature. In addition, this method involves fewer steps and is more amenable to scaling up for mass production. Alumina nanotemplates are porous alumina membranes that have been fabricated, variously, by anodizing either pure aluminum or aluminum that has been deposited on silicon by electronbeam evaporation. The diameters of the pores (7 to 300 nm), areal densities of pores (as much as 7 x 10(exp 10)sq cm), and lengths of pores (up to about 100 nm) can be tailored by selection of fabrication conditions. In a given case, the catalytic metal, catalytic metal alloy, or catalytic metal/ polytetrafluoroethylene composite is electrodeposited in the pores of the alumina nanotemplate. The dimensions of the pores, together with the electrodeposition conditions

  6. A passive fuel delivery system for portable direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Guo, Z.; Cao, Y.

    A passive device is utilized for transferring methanol into water through a wick material. The wick material preferentially has a higher wicking capability with respect to methanol than water, and operates in a siphon fashion with the intake end in contact with methanol and the discharge end in contact with water. Due to the difference of wicking capabilities, a net amount of methanol is pumped into water. The device described above is used as a fuel delivery component for a liquid-feed fuel cell system, such as a direct methanol fuel cell (DMFC), which directly utilizes a liquid fuel without an intermediate reforming process. In the present experimental study, methanol and water are stored separately in two containers and a wick is positioned between the containers as a siphon, with the aqueous methanol solution communicating with the anode of the DMFC. Methanol is siphoned from the methanol container to the water container in situ when the methanol in the water is consumed during the operation of the fuel cell. Through a proper selection of the wick and the containers, the methanol concentration near the anode of the DMFC was maintained within a preferred range.

  7. Capillary siphons and their application in the fuel delivery system of direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Guo, Zhen

    The objective of the work is to develop a fuel delivery system for potable direct methanol fuel cell. Currently, one of the most fundamental limitations of direct methanol fuel cells is that the fuel supplied to the anode of the DMFC must be a very dilute aqueous methanol solution (usually 0.5˜1.5 M). If a DMFC is filled with a dilute aqueous methanol solution, the fuel cell operation time per refuel would be very short, which would considerably diminish the advantage of a DMFC over a conventional battery. To overcome this difficulty, a complex fuel delivery system based on the modern micro system technology was proposed by the author. The proposed fuel delivery system would include micro-pumps, a methanol sensor, and a control unit. The fuel delivery system adds considerable costs to the fuel cell system and consume considerable amount of electricity from the fuel cell, which in turn significantly reduces the net power output of the fuel cell. As a result, the DMFC would have tremendous difficulty to compete with the conventional battery technology in terms of costs and power output. This work presents a novel passive fuel delivery system for direct methanol fuel cells. In this particular system, a methanol fuel and an aqueous methanol solution are stored separately in two containers and a wick is disposed between the two containers in a siphon fashion, with the container of the aqueous methanol solution communicating with the anode of the DMFC. Methanol is siphoned from the methanol container to the aqueous solution container in-situ when the methanol in the aqueous methanol solution is consumed during the operation of the fuel cell. Through a proper selection of the wick and the containers, the methanol concentration near the anode of the DMFC could be maintained within a preferable range.

  8. Wire mesh current collectors for passive direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Shrivastava, Naveen K.; Thombre, Shashikant B.; Motghare, Ramani V.

    2014-12-01

    This paper examines the feasibility of the stainless steel wire mesh as current collector in the passive direct methanol fuel cell (DMFCs-W). A novel single cell fixture is designed and fabricated. The cell performance is evaluated and compared with five different wire mesh current collectors. The supporting plates are optimized for every mesh. The performance of DMFCs-W is compared with the conventional passive DMFC which uses perforated metal plate as current collector (DMFC-P). The polarization tests and electrochemical impedance spectroscopy are performed to investigate the different aspects of the cell performance. The results reveal that the DMFCs-W yield better performance than the DMFC-P. Also, more uniform fuel distribution at catalyst layer and higher cell temperature is achieved with wire mesh current collectors. It is found that the wire mesh geometry has significant effect on the cell performance and the mesh made of relatively thick wires gives better cell performance. This study identifies the stainless steel wire mesh as promising material to be used as current collector and potential substitute to the perforated plate current collectors in the passive DMFC.

  9. SHAPE SELECTIVE NANOCATALYSTS FOR DIRECT METHANOL FUEL CELL APPLICATIONS

    SciTech Connect

    Murph, S.

    2012-09-12

    While gold and platinum have long been recognized for their beauty and value, researchers at the Savannah River National Laboratory (SRNL) are working on the nano-level to use these elements for creative solutions to our nation's energy and security needs. Multiinterdisciplinary teams consisting of chemists, materials scientists, physicists, computational scientists, and engineers are exploring unchartered territories with shape-selective nanocatalysts for the development of novel, cost effective and environmentally friendly energy solutions to meet global energy needs. This nanotechnology is vital, particularly as it relates to fuel cells.SRNL researchers have taken process, chemical, and materials discoveries and translated them for technological solution and deployment. The group has developed state-of-the art shape-selective core-shell-alloy-type gold-platinum nanostructures with outstanding catalytic capabilities that address many of the shortcomings of the Direct Methanol Fuel Cell (DMFC). The newly developed nanostructures not only busted the performance of the platinum catalyst, but also reduced the material cost and overall weight of the fuel cell.

  10. A monolayer graphene - Nafion sandwich membrane for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Yan, X. H.; Wu, Ruizhe; Xu, J. B.; Luo, Zhengtang; Zhao, T. S.

    2016-04-01

    Methanol crossover due to the low selectivity of proton exchange membranes is a long-standing issue in direct methanol fuel cell technology. Here we attempt to address this issue by designing a composite membrane fabricated by sandwiching a monolayer graphene between two thin Nafion membranes to take advantage of monolayer graphene's selective permeability to only protons. The methanol permeability of the present membrane is demonstrated to have a 68.6% decrease in comparison to that of the pristine Nafion membrane. The test in a passive direct methanol fuel cell (DMFC) shows that the designed membrane retains high proton conductivity while substantially suppressing methanol crossover. As a result, the present membrane enables the passive DMFC to exhibit a decent performance even at a methanol concentration as high as 10.0 M.

  11. Miniature Flow-Direction/Pitot-Static Pressure Probes

    NASA Technical Reports Server (NTRS)

    Ashby, George C., Jr.; Coombs, David S.; Eves, John W.; Price, Howard E.; Vasquez, Peter

    1989-01-01

    Precision flow-direction/pitot-static pressure probes, ranging from 0.035 to 0.090 inch (0.89 to 2.29 mm) in outside diameter, successfully fabricated and calibrated for use in Langley 20-inch Mach 6 Tunnel. Probes simultaneously measure flow direction and static and pitot pressures in flow fields about configurations in hypersonic flow at temperatures up to 500 degree F (260 degree C).

  12. Bio-Inspired Miniature Direction Finding Acoustic Sensor

    PubMed Central

    Wilmott, Daniel; Alves, Fabio; Karunasiri, Gamani

    2016-01-01

    A narrowband MEMS direction finding sensor has been developed based on the mechanically coupled ears of the Ormia Ochracea fly. The sensor consists of two wings coupled at the middle and attached to a substrate using two legs. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone. Thus, the directional response of the sensor is symmetric about the normal axis making the determination of the direction ambiguous. To overcome this shortcoming two sensors were assembled with a canted angle similar to that employed in radar bearing locators. The outputs of two sensors were processed together allowing direction finding with no requirement of knowing the incident sound pressure level. At the bending resonant frequency of the sensors (1.69 kHz) an output voltage of about 25 V/Pa was measured. The angle uncertainty of the bearing of sound ranged from less than 0.3° close to the normal axis (0°) to 3.4° at the limits of coverage (±60°) based on the 30° canted angle used. These findings indicate the great potential to use dual MEMS direction finding sensor assemblies to locate sound sources with high accuracy. PMID:27440657

  13. Bio-Inspired Miniature Direction Finding Acoustic Sensor

    NASA Astrophysics Data System (ADS)

    Wilmott, Daniel; Alves, Fabio; Karunasiri, Gamani

    2016-07-01

    A narrowband MEMS direction finding sensor has been developed based on the mechanically coupled ears of the Ormia Ochracea fly. The sensor consists of two wings coupled at the middle and attached to a substrate using two legs. The sensor operates at its bending resonance frequency and has cosine directional characteristics similar to that of a pressure gradient microphone. Thus, the directional response of the sensor is symmetric about the normal axis making the determination of the direction ambiguous. To overcome this shortcoming two sensors were assembled with a canted angle similar to that employed in radar bearing locators. The outputs of two sensors were processed together allowing direction finding with no requirement of knowing the incident sound pressure level. At the bending resonant frequency of the sensors (1.69 kHz) an output voltage of about 25 V/Pa was measured. The angle uncertainty of the bearing of sound ranged from less than 0.3° close to the normal axis (0°) to 3.4° at the limits of coverage (±60°) based on the 30° canted angle used. These findings indicate the great potential to use dual MEMS direction finding sensor assemblies to locate sound sources with high accuracy.

  14. Bifunctional Anode Catalysts for Direct Methanol Fuel Cells

    SciTech Connect

    Rossmeisl, Jan; Ferrin, Peter A.; Tritsaris, Georgios A.; Nilekar, Anand U.; Koh, Shirlaine; Bae, Sang Eun; Brankovic, Stanko R.; Strasser, Peter; Mavrikakis, Manos

    2012-06-13

    Using the binding energy of OH* and CO* on close-packed surfaces as reactivity descriptors, we screen bulk and surface alloy catalysts for methanol electro-oxidation activity. Using these two descriptors, we illustrate that a good methanol electro-oxidation catalyst must have three key properties: (1) the ability to activate methanol, (2) the ability to activate water, and (3) the ability to react off surface intermediates (such as CO* and OH*). Based on this analysis, an alloy catalyst made up of Cu and Pt should have a synergistic effect facilitating the activity towards methanol electro-oxidation. Using these two reactivity descriptors, a surface PtCu3 alloy is proposed to have the best catalytic properties of the Pt–Cu model catalysts tested, similar to those of a Pt–Ru bulk alloy. To validate the model, experiments on a Pt(111) surface modified with different amounts of Cu adatoms are performed. Adding Cu to a Pt(111) surface increases the methanol oxidation current by more than a factor of three, supporting our theoretical predictions for improved electrocatalysts.

  15. Enhancing the methanol tolerance of platinum nanoparticles for the cathode reaction of direct methanol fuel cells through a geometric design

    PubMed Central

    Feng, Yan; Ye, Feng; Liu, Hui; Yang, Jun

    2015-01-01

    Mastery over the structure of nanoparticles might be an effective way to enhance their performance for a given application. Herein we demonstrate the design of cage-bell nanostructures to enhance the methanol tolerance of platinum (Pt) nanoparticles while remaining their catalytic activity for oxygen reduction reaction. This strategy starts with the synthesis of core-shell-shell nanoparticles with Pt and silver (Ag) residing respectively in the core and inner shell regions, which are then agitated with saturated sodium chloride (NaCl) solution to eliminate the Ag component from the inner shell region, leading to the formation of bimetallic nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a metal shell with nano-channels, which exhibit superior methanol-tolerant property in catalyzing oxygen reduction reaction due to the different diffusion behaviour of methanol and oxygen in the porous metal shell of cage-bell structured nanoparticles. In particular, the use of remarkably inexpensive chemical agent (NaCl) to promote the formation of cage-bell structured particles containing a wide spectrum of metal shells highlights its engineering merit to produce highly selective electrocatalysts on a large scale for the cathode reaction of direct methanol fuel cells. PMID:26578100

  16. Enhancing the methanol tolerance of platinum nanoparticles for the cathode reaction of direct methanol fuel cells through a geometric design

    NASA Astrophysics Data System (ADS)

    Feng, Yan; Ye, Feng; Liu, Hui; Yang, Jun

    2015-11-01

    Mastery over the structure of nanoparticles might be an effective way to enhance their performance for a given application. Herein we demonstrate the design of cage-bell nanostructures to enhance the methanol tolerance of platinum (Pt) nanoparticles while remaining their catalytic activity for oxygen reduction reaction. This strategy starts with the synthesis of core-shell-shell nanoparticles with Pt and silver (Ag) residing respectively in the core and inner shell regions, which are then agitated with saturated sodium chloride (NaCl) solution to eliminate the Ag component from the inner shell region, leading to the formation of bimetallic nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a metal shell with nano-channels, which exhibit superior methanol-tolerant property in catalyzing oxygen reduction reaction due to the different diffusion behaviour of methanol and oxygen in the porous metal shell of cage-bell structured nanoparticles. In particular, the use of remarkably inexpensive chemical agent (NaCl) to promote the formation of cage-bell structured particles containing a wide spectrum of metal shells highlights its engineering merit to produce highly selective electrocatalysts on a large scale for the cathode reaction of direct methanol fuel cells.

  17. Laser-induced forward transfer direct-write of miniature sensor and microbattery systems

    NASA Astrophysics Data System (ADS)

    Pique, Alberto; Arnold, Craig B.; Wartena, Ryan C.; Weir, David W.; Pratap, Bhanu; Swider-Lyons, Karen E.; Kant, Richard A.; Chrisey, Douglas B.

    2003-02-01

    Direct-Write techniques have the potential to revolutionize the way miniature sensor devices and microbattery systems are designed and fabricated. The Naval Research Laboratory has developed an advanced laser-based forward transfer process for direct writing novel structures and devices comprising of metals, ceramics, polymers and composites under ambient conditions on both ceramic and plastic substrates. Using this forward transfer technique, we have demonstrated the ability to rapidly prototype various types of physical and chemical sensor devices, and microbatteries. The laser forward transfer process is computer controlled which allows the design of the devices to be easily modified and adapted to any specific application. Furthermore, the same process enables the fabrication of complete sensor or power-source systems by incorporating the passive electronic components required for sensor readout or power management. Examples are provided of various types of miniature sensors, and prototype alkaline and Li-ion microbatteries fabricated using this technique.

  18. Design and fabrication of a magnetic fluid micropump for applications in direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Lee, Shi-Min; Kuan, Yean-Der; Sung, Min-Feng

    Direct methanol fuel cells (DMFCs) are widely considered to have great potential for portable electric applications, and the power requirements for many of them are only a few watts. Therefore, a low power liquid pump is especially desirable for driving the methanol solution fuel for an active direct methanol fuel. The main objective of this paper is to design and fabricate a magnetic fluid micropump that has characteristics of low operation voltage and current and is suitable for use in DMFCs. Two prototypes were developed and tested. The magnetic fluid micropumps are successfully applied to drive the fuel to a DMFC, and measurements of the cell performance are also conducted.

  19. A simple preparation of very high methanol tolerant cathode electrocatalyst for direct methanol fuel cell based on polymer-coated carbon nanotube/platinum

    PubMed Central

    Yang, Zehui; Nakashima, Naotoshi

    2015-01-01

    The development of a durable and methanol tolerant electrocatalyst with a high oxygen reduction reaction activity is highly important for the cathode side of direct methanol fuel cells. Here, we describe a simple and novel methodology to fabricate a practically applicable electrocatalyst with a high methanol tolerance based on poly[2,2′-(2,6-pyridine)-5,5′-bibenzimidazole]-wrapped multi-walled carbon nanotubes, on which Pt nanoparticles have been deposited, then coated with poly(vinylphosphonic acid) (PVPA). The polymer coated electrocatalyst showed an ~3.3 times higher oxygen reduction reaction activity compared to that of the commercial CB/Pt and methanol tolerance in the presence of methanol to the electrolyte due to a 50% decreased methanol adsorption on the Pt after coating with the PVPA. Meanwhile, the peroxide generation of the PVPA coated electrocatalyst was as low as 0.8% with 2 M methanol added to the electrolyte, which was much lower than those of the non-PVPA-coated electrocatalyst (7.5%) and conventional CB/Pt (20.5%). Such a high methanol tolerance is very important for the design of a direct methanol fuel cell cathode electrocatalyst with a high performance. PMID:26192397

  20. Froghopper-inspired direction-changing concept for miniature jumping robots.

    PubMed

    Jung, Gwang-Pil; Cho, Kyu-Jin

    2016-09-14

    To improve the maneuverability and agility of jumping robots, several researchers have studied steerable jumping mechanisms. This steering ability enables robots to reach a particular target by controlling their jumping direction. To this end, we propose a novel direction-changing concept for miniature jumping robots. The proposed concept allows robots to be steerable while exerting minimal effects on jumping performance. The key design principles were adopted from the froghopper's power-producing hind legs and the moment cancellation accomplished by synchronized leg operation. These principles were applied via a pair of symmetrically positioned legs and conventional gears, which were modeled on the froghopper's anatomy. Each leg has its own thrusting energy, which improves jumping performance by allowing the mechanism to thrust itself with both power-producing legs. Conventional gears were utilized to simultaneously operate the legs and cancel out the moments that they induce, which minimizes body spin. A prototype to verify the concept was built and tested by varying the initial jumping posture. Three jumping postures (synchronous, asynchronous, and single-legged) were tested to investigate how synchronization and moment cancelling affect jumping performance. The results show that synchronous jumping allows the mechanism to change direction from -40° to 40°, with an improved take-off speed. The proposed concept can only be steered in a limited range of directions, but it has potential for use in miniature jumping robots that can change jumping direction with a minimal drop in jumping performance.

  1. Review on utilization of the pervaporation membrane for passive vapor feed direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Fauzi, N. F. I.; Hasran, U. A.; Kamarudin, S. K.

    2013-12-01

    The Direct Methanol Fuel Cell (DMFC) is a promising portable power source for mobile electronic devices because of its advantages including easy fuel storage, high energy density, low temperature operation and compact structure. In DMFC, methanol is used as a fuel source where it can be fed in liquid or vapor phase. However, the vapor feed DMFC has an advantage over the liquid feed system as it has the potential to have a higher operating temperature to increase the reaction rates and power outputs, to enhance the mass transfers, to reduce methanol crossover, reliable for high methanol concentration and it can increase the fuel cell performance. Methanol vapor can be delivered to the anode by using a pervaporation membrane, heating the liquid methanol or another method that compatible. Therefore, this paper is a review on vapor feed DMFC as a better energy source than liquid feed DMFC, the pervaporation membrane used to vaporize methanol feed from the reservoir and its applications in vapor feed DMFC.

  2. Sulfonated polyphosphazene-based membranes for use in direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Carter, Roy Lee

    Novel crosslinked and sulfonated poly[bis(3-methylphenoxy)phosphazene] blended proton exchange membranes were fabricated for use as the solid polymer electrolyte in a direct methanol fuel cell. Three polymers, polybenzimidazole, polyacrylonitrile and polyvinylidene fluoride-co-polyhexafluoropropylene were found to be compatible for blending with sulfonated polyphosphazene. A combination of blending and crosslinking was shown to be an effective method of producing durable, low water swelling films with acceptable proton conductivity. A novel tracer-diffusion 1H NMR method was developed and used to measure the mutual diffusion of methanol in non-crosslinked and crosslinked membranes composed of sulfonated polyphosphazene. The technique measures the growth of a solute NMR signal in the bulk (external) solution as it diffuses out of a thin film membrane. The transient increase in methanol peak height during analyte (methanol) desorption was fitted to a simple theoretical diffusion model using the methanol diffusion coefficient as an adjustable parameter. This method was found to be fast, reproducible, and accurate to within about +/-20%. Diffusion coefficients at 25°C were in the range of 1.0 x 10-8 cm2/s to 4.0 x 10-7 cm2/s for methanol concentrations of 1.0--5.0 M and were significantly smaller than those reported for a NafionRTM perfluorosulfonic acid membrane. Direct liquid methanol fuel cell tests were performed with membrane electrode assemblies (MEAs) fabricated with polyphosphazene-based proton-exchange membranes. MEAs worked best when high ion-exchange capacity (high conductivity) polyphosphazene membrane contacted the electrodes, in which case the fuel cell power output was nearly the same as that with Nafion 117 (for current densities ≤0.15 A/cm2), but the methanol crossover was three times lower than that of Nafion. The electrochemical performance of single-membrane MEAs with low conductivity S-POP/PAN films was poor, although the methanol crossover was

  3. Polymeric nanocomposite proton exchange membranes prepared by radiation-induced polymerization for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Kim, Young-Seok; Seo, Kwang-Seok; Choi, Seong-Ho

    2016-01-01

    The vinyl group-modified montmorillonite clay (F-MMT), vinyl group-modified graphene oxide (F-GO), and vinyl group-modified multi-walled carbon nanotube (F-MWNT) were first prepared by ion exchange reaction of 1-[(4-ethylphenyl)methyl]-3-butyl-imidazolium chloride in order to use the materials for protection against methanol cross-over in direct methanol fuel cell (DMFC) membrane. Then polymeric nanocomposite membranes with F-MMT, F-GO, and F-MWNT were prepared by the solvent casting method after radiation-induced polymerization of vinyl monomers in water-methanol mixture solvents. The proton conductivity, water uptake, ion-exchange capacity, methanol permeability, and DMFC performance of the polymeric nanocomposite membranes with F-MMT, F-GO, and F-MWNT were evaluated.

  4. Electrode and interconnect for miniature fuel cells using direct methanol feed

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor); Clara, Filiberto (Inventor)

    2004-01-01

    An improved system for interconnects in a fuel cell. In one embodiment, the membranes are located in parallel with one another, and current flow between them is facilitated by interconnects. In another embodiment, all of the current flow is through the interconnects which are located on the membranes. The interconnects are located between two electrodes.

  5. Direct methanol fuel cells for transportation applications. Quarterly technical report, April--June 1997

    SciTech Connect

    Fuller, T.F.; Kunz, H.R.; Moore, R.

    1997-11-01

    The purpose of this research and development effort is to advance the performance and viability of direct methanol fuel cell technology for light-duty transportation applications. For fuel cells to be an attractive alternative to conventional automotive power plants, the fuel cell stack combined with the fuel processor and ancillary systems must be competitive in terms of both performance and costs. A major advantage for the direct methanol fuel cell is that a fuel processor is not required. A direct methanol fuel cell has the potential of satisfying the demanding requirements for transportation applications, such as rapid start-up and rapid refueling. The preliminary goals of this effort are: (1) 310 W/l, (2) 445 W/kg, and (3) potential manufacturing costs of $48/kW. In the twelve month period for phase 1, the following critical areas will be investigated: (1) an improved proton-exchange membrane that is more impermeable to methanol, (2) improved cathode catalysts, and (3) advanced anode catalysts. In addition, these components will be combined to form membrane-electrode assemblies (MEA`s) and evaluated in subscale tests. Finally a conceptual design and program plan will be developed for the construction of a 5 kW direct methanol stack in Phase 2 of the program. Progress in these areas is described.

  6. Direct methanol fuel cells for transportation applications. Quarterly technical report, June 1996--September 1996

    SciTech Connect

    Fuller, T.F.; Kunz, H.R.; Moore, R.

    1996-11-01

    The purpose of this research and development effort is to advance the performance and viability of direct methanol fuel cell technology for light-duty transportation applications. For fuel cells to be an attractive alternative to conventional automotive power plants, the fuel cell stack combined with the fuel processor and ancillary systems must be competitive in terms of both performance and costs. A major advantage for the direct methanol fuel cell is that a fuel processor is not required. A direct methanol fuel cell has the potential of satisfying the demanding requirements for transportation applications, such as rapid start-up and rapid refueling. The preliminary goals of this effort are: (1) 310 W/l, (2) 445 W/kg, and (3) potential manufacturing costs of $48/kW. In the twelve month period for phase 1, the following critical areas will be investigated: (1) an improved proton-exchange membrane that is more impermeable to methanol, (2) improved cathode catalysts, and (3) advanced anode catalysts. In addition, these components will be combined to form membrane-electrode assemblies (MEA`s) and evaluated in subscale tests. Finally a conceptual design and program plan will be developed for the construction of a 5 kW direct methanol stack in phase II of the program.

  7. Behavioral pattern of a monopolar passive direct methanol fuel cell stack

    NASA Astrophysics Data System (ADS)

    Kim, Young-Jin; Bae, Byungchan; Scibioh, M. Aulice; Cho, EunAe; Ha, Heung Yong

    A passive, air-breathing, monopolar, liquid feed direct methanol fuel cell (DMFC) stack consisting of six unit cells with no external pump, fan or auxiliary devices to feed the reactants has been designed and fabricated for its possible employment as a portable power source. The configurations of the stack of monopolar passive feed DMFCs are different from those of bipolar active feed DMFCs and therefore its operational characteristics completely vary from the active ones. Our present investigation primarily focuses on understanding the unique behavioral patterns of monopolar stack under the influence of certain operating conditions, such as temperature, methanol concentration and reactants feeding methods. With passive reactants supply, the temperature of the stack and open circuit voltage (OCV) undergo changes over time due to a decrease in concentration of methanol in the reservoir as the reaction proceeds. Variations in performance and temperature of the stack are mainly influenced by the concentration of methanol. Continuous operation of the passive stack is influenced by the supply of methanol rather than air supply or water accumulation at the cathode. The monopolar stack made up of six unit cells exhibits a total power of 1000 mW (37 mW cm -2) with 4 M methanol under ambient conditions.

  8. Sol-gel based silica electrodes for inorganic membrane direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Kim, Hyea; Kohl, Paul A.

    Inorganic glass electrodes are of interest for use with inorganic proton exchange membranes for direct methanol fuel cells. Platinum-ruthenium glass electrodes (PtRu/C-SiO 2) have been prepared by incorporating the PtRu/C nanoparticles into a silica-based matrix. The SiO 2 matrix was synthesized through the sol-gel reaction of 3-(trihydroxysilyl)-1-propanesulfonic acid (3TPS) and 3-glycidoxypropyltrimethoxysilane (GPTMS). The distribution of the PtRu/C particles can be controlled by changing the properties of the gel matrix. The effect of gelation time, mole fraction of reactants within the sol, curing temperature, and glass ionomer content were investigated. The adhesion of the catalyst layer on the membrane, catalytic activity for methanol oxidation, and inhibition of methanol permeation through the membrane have been characterized and optimized. The electroless deposition of PtRu onto the PtRu/C nanoparticles was performed to increase the sheet conductivity of the electrode. It was found that the electrolessly deposited metal improved the catalytic activity for methanol oxidation and decreased the methanol cross-over. The methanol fuel cell performance using the inorganic membrane electrode assembly was 236 μA cm -2 at 0.4 V and was stable for more than 10 days.

  9. Low-Pt-Content Anode Catalyst for Direct Methanol Fuel Cells

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram; Whitacre, Jay

    2008-01-01

    Combinatorial experiments have led to the discovery that a nanophase alloy of Pt, Ru, Ni, and Zr is effective as an anode catalyst material for direct methanol fuel cells. This discovery has practical significance in that the electronic current densities achievable by use of this alloy are comparable or larger than those obtained by use of prior Pt/Ru catalyst alloys containing greater amounts of Pt. Heretofore, the high cost of Pt has impeded the commercialization of direct methanol fuel cells. By making it possible to obtain a given level of performance at reduced Pt content (and, hence, lower cost), the discovery may lead to reduction of the economic impediment to commercialization.

  10. Optimizing membrane electrode assembly of direct methanol fuel cells for portable power

    NASA Astrophysics Data System (ADS)

    Liu, Fuqiang

    Direct methanol fuel cells (DMFCs) for portable power applications require high power density, high-energy conversion efficiency and compactness. These requirements translate to fundamental properties of high methanol oxidation and oxygen reduction kinetics, as well as low methanol and water crossover. In this thesis a novel membrane electrode assembly (MEA) for direct methanol fuel cells has been developed, aiming to improve these fundamental properties. Firstly, methanol oxidation kinetics has been enhanced and methanol crossover has been minimized by proper control of ionomer crystallinity and its swelling in the anode catalyst layer through heat-treatment. Heat-treatment has a major impact on anode characteristics. The short-cured anode has low ionomer crystallinity, and thus swells easily when in contact with methanol solution to create a much denser anode structure, giving rise to higher methanol transport resistance than the long-cured anode. Variations in interfacial properties in the anode catalyst layer (CL) during cell conditioning were also characterized, and enhanced kinetics of methanol oxidation and severe limiting current phenomenon were found to be caused by a combination of interfacial property variations and swelling of ionomer over time. Secondly, much effort has been expended to develop a cathode CL suitable for operation under low air stoichiometry. The effects of fabrication procedure, ionomer content, and porosity distribution on the microstructure and cathode performance under low air stoichiometry are investigated using electrochemical and surface morphology characterizations to reveal the correlation between microstructure and electrochemical behavior. At the same time, computational fluid dynamics (CFD) models of DMFC cathodes have been developed to theoretically interpret the experimental results, to investigate two-phase transport, and to elucidate mechanism of cathode mixed potential due to methanol crossover. Thirdly, a MEA with low

  11. Investigation of Ruthenium Dissolution in Advanced Membrane Electrode Assemblies for Direct Methanol Based Fuel Cells Stacks

    NASA Technical Reports Server (NTRS)

    Valdez, T. I.; Firdosy, S.; Koel, B. E.; Narayanan, S. R.

    2005-01-01

    This viewgraph presentation gives a detailed review of the Direct Methanol Based Fuel Cell (DMFC) stack and investigates the Ruthenium that was found at the exit of the stack. The topics include: 1) Motivation; 2) Pathways for Cell Degradation; 3) Cell Duration Testing; 4) Duration Testing, MEA Analysis; and 5) Stack Degradation Analysis.

  12. In situ synthesis of nanocomposite membranes: comprehensive improvement strategy for direct methanol fuel cells.

    PubMed

    Rao, Siyuan; Xiu, Ruijie; Si, Jiangju; Lu, Shanfu; Yang, Meng; Xiang, Yan

    2014-03-01

    In situ synthesis is a powerful approach to control nanoparticle formation and consequently confers extraordinary properties upon composite membranes relative to conventional doping methods. Herein, uniform nanoparticles of cesium hydrogen salts of phosphotungstic acid (CsPW) are controllably synthesized in situ in Nafion to form CsPW–Nafion nanocomposite membranes with both improved proton conductivity and methanol-crossover suppression. A 101.3% increase of maximum power density has been achieved relative to pristine Nafion in a direct methanol fuel cell (DMFC), indicating a potential pathway for large-scale fabrication of DMFC alternative membranes.

  13. Three-dimensional anode engineering for the direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Bauer, A.; Oloman, C. W.; Gyenge, E. L.

    Catalyzed graphite felt three-dimensional anodes were investigated in direct methanol fuel cells (DMFCs) operated with sulfuric acid supporting electrolyte. With a conventional serpentine channel flow field the preferred anode thickness was 100 μm, while a novel flow-by anode showed the best performance with a thickness of 200-300 μm. The effects of altering the methanol concentration, anolyte flow rate and operating temperature on the fuel cell superficial power density were studied by full (2 3 + 1) factorial experiments on a cell with anode area of 5 cm 2 and excess oxidant O 2 at 200 kPa(abs). For operation in the flow-by mode with 2 M methanol at 2 cm 3 min -1 and 353 K the peak power density was 2380 W m -2 with a PtRuMo anode catalyst, while a PtRu catalyst yielded 2240 W m -2 under the same conditions.

  14. A review of polymer electrolyte membranes for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Neburchilov, Vladimir; Martin, Jonathan; Wang, Haijiang; Zhang, Jiujun

    This review describes the polymer electrolyte membranes (PEM) that are both under development and commercialized for direct methanol fuel cells (DMFC). Unlike the membranes for hydrogen fuelled PEM fuel cells, among which perfluorosulfonic acid based membranes show complete domination, the membranes for DMFC have numerous variations, each has its advantages and disadvantages. No single membrane is emerging as absolutely superior to others. This review outlines the prospects of the currently known membranes for DMFC. The membranes are evaluated according to various properties, including: methanol crossover, proton conductivity, durability, thermal stability and maximum power density. Hydrocarbon and composite fluorinated membranes currently show the most potential for low cost membranes with low methanol permeability and high durability. Some of these membranes are already beginning to impact the portable fuel cell market.

  15. Polymer electrolyte direct methanol fuel cells: an option for transportation applications

    SciTech Connect

    Gottesfeld, S.; Cleghorn, S.J.C.; Ren, X.; Springer, T.E.; Wilson, M.S.; Zawodzinski, T.A.

    1996-10-01

    PEFCs most frequently considered for electric vehicles have been based on either hydrogen carried aboard, or steam-reforming of methanol on board to produce H2 + CO2. Direct methanol fuel cells (DMFCs), which use a liquid methanol fuel feed, completely avoid the complexity and weight penalties of the reformer, but have not been considered a serious option until recently, because of much lower power densities. Recent advances in DMFCs have been dramatic, however, with the DMFC reaching power densities which are significant fractions of those provided by reformate/air fuel cells. Use of established Pt-Ru anode electrocatalysts and Pt cathode electrocatalysts in polymer electrolyte DMFCs has resulted in enhanced DMFC performance, particularly when operated above 100 C and when catalyst layer composition and structure are optimized. The higher DMFC power densities recently achieved provide a new basis for considering DMFCs for transportation applications.

  16. Performance and modelling of a direct methanol solid polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Scott, K.; Taama, W.; Cruickshank, J.

    The performance and modelling of a direct methanol fuel cell based on a solid polymer electrolyte membrane (SPE) is reported. Two sizes of cell are used: a small cell with an area of 9 cm 2 and a large single cell with an area of 250 cm 2. The fuel cell utilises a vapourised methanol fuel at a porous carbon/Pt-Ru catalyst electrode. The performance of the fuel cell is affected by the cross-over of methanol from the anode to the cathode through the polymer membrane and this behaviour is modelled. To evaluate cell performance, mathematical models are constructed which describe mass transport in the porous electrode structures and the potential and concentration distributions in the electrode regions. These models are used to predict the cell voltage and current density response of the fuel cell.

  17. High-temperature passive direct methanol fuel cells operating with concentrated fuels

    NASA Astrophysics Data System (ADS)

    Zhao, Xuxin; Yuan, Wenxiang; Wu, Qixing; Sun, Hongyuan; Luo, Zhongkuan; Fu, Huide

    2015-01-01

    Conventionally, passive direct methanol fuel cells (DMFC) are fed with diluted methanol solutions and can hardly be operated at elevated temperatures (>120 °C) because the ionic conductivity of Nafion-type proton exchange membranes depends strongly on water content. Such a system design would limit its energy density and power density in mobile applications. In this communication, a passive vapor feed DMFC capable of operating with concentrated fuels at high temperatures is reported. The passive DMFC proposed in this work consists of a fuel reservoir, a perforated silicone sheet, a vapor chamber, two current collectors and a membrane electrode assembly (MEA) based on a phosphoric acid doped polybenzimidazole (PBI) membrane. The experimental results reveal that the methanol crossover through a PBI membrane is substantially low when compared with the Nafion membranes and the PBI-based passive DMFC can yield a peak power density of 37.2 mW cm-2 and 22.1 mW cm-2 at 180 °C when 16 M methanol solutions and neat methanol are used respectively. In addition, the 132 h discharge test indicates that the performance of this new DMFC is quite stable and no obvious performance degradation is observed after activation, showing its promising applications in portable power sources.

  18. On the actual cathode mixed potential in direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Zago, M.; Bisello, A.; Baricci, A.; Rabissi, C.; Brightman, E.; Hinds, G.; Casalegno, A.

    2016-09-01

    Methanol crossover is one of the most critical issues hindering commercialization of direct methanol fuel cells since it leads to waste of fuel and significantly affects cathode potential, forming a so-called mixed potential. Unfortunately, due to the sluggish anode kinetics, it is not possible to obtain a reliable estimation of cathode potential by simply measuring the cell voltage. In this work we address this limitation, quantifying the mixed potential by means of innovative open circuit voltage (OCV) tests with a methanol-hydrogen mixture fed to the anode. Over a wide range of operating conditions, the resulting cathode overpotential is between 250 and 430 mV and is strongly influenced by methanol crossover. We show using combined experimental and modelling analysis of cathode impedance that the methanol oxidation at the cathode mainly follows an electrochemical pathway. Finally, reference electrode measurements at both cathode inlet and outlet provide a local measurement of cathode potential, confirming the reliability of the innovative OCV tests and permitting the evaluation of cathode potential up to typical operating current. At 0.25 A cm-2 the operating cathode potential is around 0.85 V and the Ohmic drop through the catalyst layer is almost 50 mV, which is comparable to that in the membrane.

  19. Effect of the impurities in crude bio-methanol on the performance of the direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Tsujiguchi, Takuya; Furukawa, Takayuki; Nakagawa, Nobuyoshi

    As an environmental friendly and economical methanol for the fuel of a DMFC, we focused on a crude bio-methanol from woody biomass without refining. The effects of the impurities, i.e., ethanol, 1-butanol, methyl formate and diisopropyl ether, contained in the crude bio-methanol on the DMFC performance were investigated. Methyl formate and diisopropyl ether hardly or only slightly affected the DMFC performance, while ethanol and 1-butanol caused a significant degradation in the performance. When multiple impurities are present in the fuel as well as the crude bio-methanol, the degradation was somewhat lower than that of the single impurity, 1-butanol, which was the most harmful component of the multiple impurities. When using the crude bio-methanol as a DMFC fuel, removal of the harmful impurities, such as ethanol and 1-butanol, is necessary, otherwise a novel catalyst, which is also active for the oxidation of these impurities, required.

  20. Dieselzymes: development of a stable and methanol tolerant lipase for biodiesel production by directed evolution

    PubMed Central

    2013-01-01

    Background Biodiesels are methyl esters of fatty acids that are usually produced by base catalyzed transesterification of triacylglyerol with methanol. Some lipase enzymes are effective catalysts for biodiesel synthesis and have many potential advantages over traditional base or acid catalyzed transesterification. Natural lipases are often rapidly inactivated by the high methanol concentrations used for biodiesel synthesis, however, limiting their practical use. The lipase from Proteus mirabilis is a particularly promising catalyst for biodiesel synthesis as it produces high yields of methyl esters even in the presence of large amounts of water and expresses very well in Escherichia coli. However, since the Proteus mirabilis lipase is only moderately stable and methanol tolerant, these properties need to be improved before the enzyme can be used industrially. Results We employed directed evolution, resulting in a Proteus mirabilis lipase variant with 13 mutations, which we call Dieselzyme 4. Dieselzyme 4 has greatly improved thermal stability, with a 30-fold increase in the half-inactivation time at 50°C relative to the wild-type enzyme. The evolved enzyme also has dramatically increased methanol tolerance, showing a 50-fold longer half-inactivation time in 50% aqueous methanol. The immobilized Dieselzyme 4 enzyme retains the ability to synthesize biodiesel and has improved longevity over wild-type or the industrially used Brukholderia cepacia lipase during many cycles of biodiesel synthesis. A crystal structure of Dieselzyme 4 reveals additional hydrogen bonds and salt bridges in Dieselzyme 4 compared to the wild-type enzyme, suggesting that polar interactions may become particularly stabilizing in the reduced dielectric environment of the oil and methanol mixture used for biodiesel synthesis. Conclusions Directed evolution was used to produce a stable lipase, Dieselzyme 4, which could be immobilized and re-used for biodiesel synthesis. Dieselzyme 4 outperforms

  1. Can miniature pulpotomy procedure improve treatment outcomes of direct pulp capping?

    PubMed

    Asgary, Saeed; Ahmadyar, Maryam

    2012-02-01

    Dental pulp exposure is a common incident during dental treatment. If there are clinical signs of pulp vitality, it is recommended to carry out direct pulp capping (DPC) using appropriate pulp covering agents (PCA). The main objectives are maintenance of pulp vitality/healing along with the formation of a calcified bridge beneath the PCA. Our proposed hypothesis is based on consideration of biologic principles in order to achieve improved treatment outcomes of DPC for cariously exposed pulp using miniature pulpotomy procedure (MPP). MPP will result in improved treatment outcomes of DPC by improved maintenance of a clean surgical pulp wound; removal of infected dentin chips/damaged pulp tissue specially injured odontoblast cells; improved proximity/interaction of PCA to undifferentiated mesenchymal/stem cells; better control of bleeding; and creating an improved seal using PCA.

  2. Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells

    PubMed Central

    Kim, Jiyoung; Jang, Jin-Sung; Peck, Dong-Hyun; Lee, Byungrok; Yoon, Seong-Ho; Jung, Doo-Hwan

    2016-01-01

    Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF–supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA) of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected.

  3. Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells.

    PubMed

    Kim, Jiyoung; Jang, Jin-Sung; Peck, Dong-Hyun; Lee, Byungrok; Yoon, Seong-Ho; Jung, Doo-Hwan

    2016-08-15

    Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF-supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA) of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected.

  4. Performance of PEM Liquid-Feed Direct Methanol-Air Fuel Cells

    NASA Technical Reports Server (NTRS)

    Narayanan, S. R.

    1995-01-01

    A direct methanol-air fuel cell operating at near atmospheric pressure, low-flow rate air, and at temperatures close to 60oC would tremendously enlarge the scope of potential applications. While earlier studies have reported performance with oxygen, the present study focuses on characterizing the performance of a PEM liquid feed direct methanol-air cell consisting of components developed in house. These cells employ Pt-Ru catalyst in the anode, Pt at the cathode and Nafion 117 as the PEM. The effect of pressure, flow rate of air and temperature on cell performance has been studied. With air, the performance level is as high as 0.437 V at 300 mA/cm2 (90oC, 20 psig, and excess air flow) has been attained. Even more significant is the performance level at 60oC, 1 atm and low flow rates of air (3-5 times stoichiometric), which is 0.4 V at 150 mA/cm2. Individual electrode potentials for the methanol and air electrode have been separated and analyzed. Fuel crossover rates and the impact of fuel crossover on the performance of the air electrode have also been measured. The study identifies issues specific to the methanol-air fuel cell and provides a basis for improvement strategies.

  5. Anionic-cationic bi-cell design for direct methanol fuel cell stack

    NASA Astrophysics Data System (ADS)

    Kim, Hyea; Ünlü, Murat; Zhou, Junfeng; Anestis-Richard, Irene; Kohl, Paul A.

    A new fuel cell stack design is described using an anion exchange membrane (AEM) fuel cell and a proton exchange membrane (PEM) fuel cell in series with a single fuel tank servicing both anodes in a passive direct methanol fuel cell configuration. The anionic-cationic bi-cell stack has alkaline and acid fuel cells in series (twice the voltage), one fuel tank, and simplified water management. The series connection between the two cells involves shorting the cathode of the anionic cell to the anode of the acidic cell. It is shown that these two electrodes are at essentially the same potential which avoids an undesired potential difference and resulting loss in current between the two electrodes. Further, the complimentary direction of water transport in the two kinds of fuel cells simplifies water management at both the anodes and cathodes. The effect of ionomer content on the AEM electrode potential and the activity of methanol oxidation were investigated. The individual performance of AEM and PEM fuel cells were evaluated. The effect of ion-exchange capacity in the alkaline electrodes was studied. A fuel wicking material in the methanol fuel tank was used to provide orientation-independent operation. The open circuit potential of the bi-cell was 1.36 V with 2.0 M methanol fuel and air at room temperature.

  6. Comprehensive one-dimensional, semi-analytical, mathematical model for liquid-feed polymer electrolyte membrane direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Kareemulla, D.; Jayanti, S.

    Polymer electrolyte membrane direct methanol fuel cells (PEM-DMFCs) have several advantages over hydrogen-fuelled PEM fuel cells; but sluggish methanol electrochemical oxidation and methanol crossover from the anode to the cathode through the PEM are two major problems with these cells. In the present work, a comprehensive one-dimensional, single phase, isothermal mathematical model is developed for a liquid-feed PEM-DMFC, taking into account all the necessary mass transport and electrochemical phenomena. Diffusion and convective effects are considered for methanol transport on the anode side and in the PEM, whereas only diffusional transport of species is considered on the cathode side. A multi-step reaction mechanism is used to describe the electrochemical oxidation of methanol at the anode. Stefan-Maxwell equations are used to describe multi-component diffusion on the cathode side and Tafel type of kinetics is used to describe the simultaneous methanol oxidation and oxygen reduction reactions at the cathode. The model fully accounts for the mixed potential effect caused by methanol crossover at the cathode. It shows excellent agreement with literature data of the limiting current density for different low methanol feed concentrations at different operating temperatures. At high methanol feed concentrations, oxygen depletion on the cathode side, due to excessive methanol crossover, results in mass-transport limitations. The model can be used to optimize the geometric and physical parameters with a view to extracting the highest current density while still keeping a tolerably low methanol crossover.

  7. Modelling of solid polymer and direct methanol fuel cells: Phenomenological equations and analytical solutions

    NASA Astrophysics Data System (ADS)

    Kauranen, P. S.

    1993-04-01

    In the solid state concept of a direct methanol fuel cell (DMFC), methanol is directly oxidized at the anode of a solid polymer electrolyte fuel cell (SPEFC). Mathematical modelling of the transport and reaction phenomena within the electrodes and the electrolyte membrane is needed in order to get a closer insight into the operation of the fuel cell. In the work, macro-homogenous porous electrode and dilute solution theories are used to derive the phenomenological equations describing the transport and reaction mechanisms in a SPEFC single cell. The equations are first derived for a conventional H2/air SPEFC, and then extended for a DMFC. The basic model is derived in a one dimensional form in which it is assumed that species transport take place only in the direction crossing the cell sandwich. In addition, two dimensional descriptions of the catalyst layer are reviewed.

  8. 3D anodes for direct methanol fuel cells: Science and synthesis

    NASA Astrophysics Data System (ADS)

    Takmeel, Qanit

    The high specific energy density of methanol in direct methanol fuel cells (DMFCs) makes them particularly suitable for portable applications. However, a typical DMFC membrane electrode assembly (MEA) delivers an order of magnitude less power density compared to a hydrogen fuel cell MEA. Conventional DMFCs are operated at dilute methanol concentrations to counter problems arising from the methanol crossover issue. A breakthrough in power density can be achieved if the MEA structure is fundamentally altered to enable supply of more concentrated methanol than in current DMFCs. It has been shown that the current anode designs are limited by mass transport resulting in low current density. [1] An anode, with manifold increase in surface area, for catalysis would increase the limiting current density (jL), as a result of which the power density of the fuel cell would increase. In this work, the role of layering of Pt on Ru was studied and this lay the foundation towards understanding catalytic behavior in the fuel cell anode. Cyclic voltammetry (CV), in conjunction with copper underpotential deposition (Cu-UPD) and 15 kelvin probe force microscopy (KPFM), showed that by adjusting the thickness of Pt on a Ru substrate, the Fermi energy (EF) of the surface can be tailored to yield more efficient methanol electro-oxidizing catalysts. In order to increase the effective catalysis surface area, three-dimensional (3D) carbon based hierarchical structures were fabricated on which Pt-Ru catalyst was grown using atomic layer deposition (ALD). Scanning electron microscopy (SEM), with image processing, was used to determine the surface coverage of the carbon surfaces. CV showed that as much as hundred times the current density (j) can be achieved with such a structure as compared to a flat surface. Subsequently, mass transport limitations were studied via chronoamperometry (CA) performed in different methanol concentrations. The studies were also used to extract the rate order of

  9. (Non) formation of methanol by direct hydrogenation of formate on copper catalysts

    SciTech Connect

    Yang, Yong; Mims, Charles A.; Disselkamp, Robert S.; Kwak, Ja Hun; Peden, Charles HF; Campbell, C. T.

    2010-10-14

    We have attempted to hydrogenate adsorbed formate species on copper catalysts to probe the importance of this postulated mechanistic step in methanol synthesis. Surface formate coverages up to 0.25 were produced at temperatures between 413K and 453K on supported (Cu/SiO2) copper and unsupported copper catalysts. The adlayers were produced by various methods including (1) steady state catalytic conditions in CO2-H2 (3:1, 6 bar) atmospheres, and (2) by exposure of the catalysts to formic acid. As reported in earlier work, the catalytic surface at steady state contains bidentate formate species with coverages up to saturation levels of ~ 0.25 at the low temperatures of this study. The reactivity of these formate adlayers was investigated at relevant reaction temperatures in atmospheres containing up to 6 bar H2 partial pressure by simultaneous mass spectrometry (MS) and infrared (IR) spectroscopy measurements. The yield of methanol during the attempted hydrogenation (“titration”) of these adlayers was insignificant (<0.2 mol % of the formate adlayer) even in dry hydrogen partial pressures up to 6 bar. Hydrogen titration of formate species produced from formic acid also failed to produce significant quantities of methanol, and attempted titration in gases consisting of CO-hydrogen mixtures or dry CO2 were also unproductive. The formate decomposition kinetics, measured by IR, were also unaffected by these changes in the gas composition. Similar experiments on unsupported copper also failed to show any methanol. From these results, we conclude that methanol synthesis on copper cannot result from the direct hydrogenation of (bidentate) formate species in simple steps involving adsorbed H species alone. Furthermore, experiments performed on both supported (Cu/SiO2) and unsupported copper catalysts gave similar results implying that the methanol synthesis reaction mechanism only involves metal surface chemistry. Pre-exposure of the bidentate formate adlayer to oxidation

  10. Effect of the cathode open ratios on the water management of a passive vapor-feed direct methanol fuel cell fed with neat methanol

    NASA Astrophysics Data System (ADS)

    Li, Xianglin; Faghri, Amir

    2011-08-01

    A novel approach has been proposed to improve the water management of a passive direct methanol fuel cell (DMFC) fed with neat methanol without increasing its volume or weight. By adopting perforated covers with different open ratios at the cathode, the water management has been significantly improved in a DMFC fed with neat methanol. An optimized cathode open ratio could ensure both the sufficient supply of oxygen and low water loss. While changing the open ratio of anode vaporizer can adjust the methanol crossover rate in a DMFC. Furthermore, the gas mixing layer, added between the anode vaporizer and the anode current collector to increase the mass transfer resistance, can improve the cell performance, decrease the methanol crossover, and increase the fuel efficiency. For the case of a DMFC fed with neat methanol, an anode vaporizer with the open ratio of 12% and a cathode open ratio of 20% produced the highest peak power density, 22.7 mW cm-2, and high fuel efficiency, 70.1%, at room temperature of 25 ± 1 °C and ambient humidity of 25-50%.

  11. X-ray absorption and electrochemical studies of direct methanol fuel cell catalysts

    SciTech Connect

    Zurawski, D.J.; Aldykiewicz, A.J. Jr.; Baxter, S.F.; Krumpelt, M.

    1996-12-31

    In order for polymer electrolyte fuel cells to operate directly on methanol instead of hydrogen, a distinct advantage for portable applications, methanol oxidation must be catalyzed effectively in the acidic environment of the cell. Platinum-ruthenium and platinum-ruthenium oxide are generally considered to be the most active catalysts for this purpose. The presence of ruthenium significantly enhances the activity of platinum in these catalysts, for reasons not yet fully understood. We are using X-ray absorption spectroscopy (XAS) and electrochemical techniques to evaluate the mechanisms proposed to account for this enhancement in order to further improve the catalyst`s activity. We are considering three enhancement mechanisms. An intermediate in the oxidation of methanol on platinum is carbon monoxide and its oxidation is the rate-determining step in the overall oxidation mechanism. It has been proposed that ruthenium facilitates the removal of carbon monoxide from the platinum surface. First, it has been proposed that ruthenium decreases the strength of the platinum-carbon monoxide bond. Carbon monoxide bonds to the catalyst by interacting with the d-band of platinum, therefore a change in the d-band occupancy of platinum as a result of alloying may influence the bond strength of carbon monoxide. Another proposed enhancement mechanism involves lowering of the potential for the formation of the CO-oxidizing species. Finally, the binary catalysts may have a structure which is more conducive to the methanol dehydrogenation and carbon monoxide reactions. Based on these three proposed enhancement mechanisms, a goal of this study is to correlate catalyst electronic properties, structure, and oxidation state with the performance of proton-exchange membrane (Nafion) direct methanol fuel cells.

  12. Selective electrocatalysts toward a prototype of the membraneless direct methanol fuel cell

    PubMed Central

    Feng, Yan; Yang, Jinhua; Liu, Hui; Ye, Feng; Yang, Jun

    2014-01-01

    Mastery over the structure of nanomaterials enables control of their properties to enhance their performance for a given application. Herein we demonstrate the design and fabrication of Pt-based nanomaterials with enhanced catalytic activity and superior selectivity toward the reactions in direct methanol fuel cells (DMFCs) upon the deep understanding of the mechanisms of these electrochemical reactions. In particular, the ternary Au@Ag2S-Pt nanocomposites display superior methanol oxidation reaction (MOR) selectivity due to the electronic coupling effect among different domains of the nanocomposites, while the cage-bell structured Pt-Ru nanoparticles exhibit excellent methanol tolerance for oxygen reduction reaction (ORR) at the cathode because of the differential diffusion of methanol and oxygen in the porous Ru shell of the cage-bell nanoparticles. The good catalytic selectivity of these Pt-based nanomaterials via structural construction enables a DMFC to be built without a proton exchange membrane between the fuel electrode and the oxygen electrode. PMID:24448514

  13. Development of Anodic Flux and Temperature Controlling System for Micro Direct Methanol Fuel Cell

    NASA Astrophysics Data System (ADS)

    Li, M. M.; Liu, C.; Liang, J. S.; Wu, C. B.; Xu, Z.

    2006-10-01

    Micro Direct Methanol Fuel Cell (μDMFC) is a kind of newly developed power sources, which effective apparatus for its performance evaluation is still in urgent need at present. In this study, a testing system was established for the purpose of testing the continuous working performance such as micro flux and temperature of μDMFC. In view of the temperature controlling for micro-flux liquid fuel, a heating block with labyrinth-like single pass channel inside for heating up the methanol solution was fabricated. A semiconductorrefrigerating chip was utilized to heat and cool the liquid flow during testing procedures. On the other hand, the two channels of a high accuracy double-channel syringe pump that can suck and pump in turn so as to transport methanol solution continuously was adopted. Based on the requirements of wide-ranged temperature and micro flux controlling, the solenoid valves and the correlative component were used. A hydraulic circuit, which can circulate the fed methanol cold to hot in turn, has also been constructed to test the fatigue life of the μDMFC. The automatic control was actualized by software module written with Visual C++. Experimental results show that the system is perfect in stability and it may provide an important and advanced evaluation apparatus to satisfy the needs for real time performance testing of μDMFC.

  14. Self-Activated Micro Direct-Methanol Fuel Cell (muDMFC) at Near Room Temperature

    DTIC Science & Technology

    2007-11-02

    control of multiphase flows at the microscale is crucial to micro-DMFC development. Through micro channel experiments we showed that wettability ...channel experiments study the effects of wettability (hydrophilic/hydrophobic) as well as the presence of impurities in the fuel on the operating...and gas are flowing into square cross-sectional microchannels. The optimal wettability properties for Micro-Direct Methanol Fuel Cells are hydrophilic

  15. TiO2 Nanotube-Carbon (TNT-C) as Support for Pt-based Catalyst for High Methanol Oxidation Reaction in Direct Methanol Fuel Cell.

    PubMed

    Abdullah, M; Kamarudin, S K; Shyuan, L K

    2016-12-01

    In this study, TiO2 nanotubes (TNTs) were synthesized via a hydrothermal method using highly concentrated NaOH solutions varying from 6 to 12 M at 180 °C for 48 h. The effects of the NaOH concentration and the TNT crystal structure on the performance for methanol oxidation were investigated to determine the best catalyst support for Pt-based catalysts. The results showed that TNTs produced with 10 M NaOH exhibited a length and a diameter of 550 and 70 nm, respectively; these TNTs showed the best nanotube structure and were further used as catalyst supports for a Pt-based catalyst in a direct methanol fuel cell. The synthesized TNT and Pt-based catalysts were analysed by FESEM, TEM, BET, EDX, XRD and FTIR. The electrochemical performance of the catalysts was investigated using cyclic voltammetry (CV) and chronoamperometric (CA) analysis to further understand the methanol oxidation in the direct methanol fuel cell (DMFC). Finally, the result proves that Pt-Ru/TNT-C catalyst shows high performance in methanol oxidation as the highest current density achieved at 3.3 mA/cm(2) (normalised by electrochemically active surface area) and high catalyst tolerance towards poisoning species was established.

  16. TiO2 Nanotube-Carbon (TNT-C) as Support for Pt-based Catalyst for High Methanol Oxidation Reaction in Direct Methanol Fuel Cell

    NASA Astrophysics Data System (ADS)

    Abdullah, M.; Kamarudin, S. K.; Shyuan, L. K.

    2016-12-01

    In this study, TiO2 nanotubes (TNTs) were synthesized via a hydrothermal method using highly concentrated NaOH solutions varying from 6 to 12 M at 180 °C for 48 h. The effects of the NaOH concentration and the TNT crystal structure on the performance for methanol oxidation were investigated to determine the best catalyst support for Pt-based catalysts. The results showed that TNTs produced with 10 M NaOH exhibited a length and a diameter of 550 and 70 nm, respectively; these TNTs showed the best nanotube structure and were further used as catalyst supports for a Pt-based catalyst in a direct methanol fuel cell. The synthesized TNT and Pt-based catalysts were analysed by FESEM, TEM, BET, EDX, XRD and FTIR. The electrochemical performance of the catalysts was investigated using cyclic voltammetry (CV) and chronoamperometric (CA) analysis to further understand the methanol oxidation in the direct methanol fuel cell (DMFC). Finally, the result proves that Pt-Ru/TNT-C catalyst shows high performance in methanol oxidation as the highest current density achieved at 3.3 mA/cm2 (normalised by electrochemically active surface area) and high catalyst tolerance towards poisoning species was established.

  17. Proton exchange membrane materials for the advancement of direct methanol fuel-cell technology

    DOEpatents

    Cornelius, Christopher J.

    2006-04-04

    A new class of hybrid organic-inorganic materials, and methods of synthesis, that can be used as a proton exchange membrane in a direct methanol fuel cell. In contrast with Nafion.RTM. PEM materials, which have random sulfonation, the new class of materials have ordered sulfonation achieved through self-assembly of alternating polyimide segments of different molecular weights comprising, for example, highly sulfonated hydrophilic PDA-DASA polyimide segment alternating with an unsulfonated hydrophobic 6FDA-DAS polyimide segment. An inorganic phase, e.g., 0.5 5 wt % TEOS, can be incorporated in the sulfonated polyimide copolymer to further improve its properties. The new materials exhibit reduced swelling when exposed to water, increased thermal stability, and decreased O.sub.2 and H.sub.2 gas permeability, while retaining proton conductivities similar to Nafion.RTM.. These improved properties may allow direct methanol fuel cells to operate at higher temperatures and with higher efficiencies due to reduced methanol crossover.

  18. Development of cesium phosphotungstate salt and chitosan composite membrane for direct methanol fuel cells.

    PubMed

    Xiao, Yanxin; Xiang, Yan; Xiu, Ruijie; Lu, Shanfu

    2013-10-15

    A novel composite membrane has been developed by doping cesium phosphotungstate salt (CsxH3-xPW12O40 (0≤x≤3), Csx-PTA) into chitosan (CTS/Csx-PTA) for application in direct methanol fuel cells (DMFCs). Uniform distribution of Csx-PTA nanoparticles has been achieved in the chitosan matrix. The proton conductivity of the composite membrane is significantly affected by the Csx-PTA content in the composite membrane as well as the Cs substitution in PTA. The highest proton conductivity for the CTS/Csx-PTA membranes was obtained with x=2 and Cs2-PTA content of 5 wt%. The value is 6×10(-3) S cm(-1) and 1.75×10(-2) S cm(-1) at 298 K and 353 K, respectively. The methanol permeability of CTS/Cs2-PTA membrane is about 5.6×10(-7), 90% lower than that of Nafion-212 membrane. The highest selectivity factor (φ) was obtained on CTS/Cs2-PTA-5 wt% composite membrane, 1.1×10(4)/Scm(-3)s. The present study indicates the promising potential of CTS/Csx-PTA composite membrane as alternative proton exchange membranes in direct methanol fuel cells.

  19. A direct methanol fuel cell system to power a humanoid robot

    NASA Astrophysics Data System (ADS)

    Joh, Han-Ik; Ha, Tae Jung; Hwang, Sang Youp; Kim, Jong-Ho; Chae, Seung-Hoon; Cho, Jae Hyung; Prabhuram, Joghee; Kim, Soo-Kil; Lim, Tae-Hoon; Cho, Baek-Kyu; Oh, Jun-Ho; Moon, Sang Heup; Ha, Heung Yong

    In this study, a direct methanol fuel cell (DMFC) system, which is the first of its kind, has been developed to power a humanoid robot. The DMFC system consists of a stack, a balance of plant (BOP), a power management unit (PMU), and a back-up battery. The stack has 42 unit cells and is able to produce about 400 W at 19.3 V. The robot is 125 cm tall, weighs 56 kg, and consumes 210 W during normal operation. The robot is integrated with the DMFC system that powers the robot in a stable manner for more than 2 h. The power consumption by the robot during various motions is studied, and load sharing between the fuel cell and the back-up battery is also observed. The loss of methanol feed due to crossover and evaporation amounts to 32.0% and the efficiency of the DMFC system in terms of net electric power is 22.0%.

  20. The performance analysis of direct methanol fuel cells with different hydrophobic anode channels

    NASA Astrophysics Data System (ADS)

    Yeh, Hung-Chun; Yang, Ruey-Jen; Luo, Win-Jet; Jiang, Jia-You; Kuan, Yean-Der; Lin, Xin-Quan

    In order to enhance the performance of the direct methanol fuel cell (DMFC), the product of CO 2 bubble has to be efficiently removed from the anode channel during the electrochemical reaction. In this study, the materials of Polymethyl Methacrylate (PMMA) with hydrophilic property and polydimethylsiloxane (PDMS) with hydrophobic property are used to form the anode cannel. The channel is fabricated through a microelectromechanical system (MEMS) manufacture process of the DMFCs. In addition, some particles with high hydrophobic properties are added into the PDMS materials in order to further reduce the hydro-resistance in the anode channel. The performance of the DMFCs is investigated under the influence of operation conditions, including operation temperature, flow rate, and methanol concentration. It is found that the performance of the DMFC, which is made of PDMS with high hydrophobic particles, can be greatly enhanced and the hydrophobic property of the particles can be unaffected by different operation conditions.

  1. Direct measurement of nutrient concentrations in freshwaters with a miniaturized analytical probe: evaluation and validation.

    PubMed

    Copetti, D; Valsecchi, L; Capodaglio, A G; Tartari, G

    2017-04-01

    This work deals with the evaluation of the aqueous concentrations of dissolved reactive phosphorus (DRP), total phosphorus (TP), and ammonium nitrogen (N-NH4) in surface water by means of direct online instrumentation. A portable, submersible, and automated analyzer designed to measure dissolved and total nutrient concentrations characterized by miniaturization of the entire analytical process was tested against laboratory methods. A total number of 36 water samples of different origin (i.e., rain, river, lake, and sewage waters) were analyzed and used in the comparison of DRP, TP, and N-NH4 data. Raw data were distributed in a broad range of concentrations: 5-299 μg P/L for DRP, 7-97 μg P/L for TP, and 11-332 μg N/L for N-NH4. Regression analysis underlined a high significant correlation between the measures of the probe and those of the laboratory (0.6 < R (2) < 0.9; p < 0.001) and pointed out the effectiveness of the new instrument in representing a broad range of nutrient concentrations.

  2. Direct Conversion of Methane to Methanol under Mild Conditions over Cu-Zeolites and beyond.

    PubMed

    Tomkins, Patrick; Ranocchiari, Marco; van Bokhoven, Jeroen A

    2017-02-21

    In the recent years methane has become increasingly abundant. However, transportation costs are high and methane recovered as side product is often flared rather than valorized. The chemical utilization of methane is highly challenging and currently mainly based on the cost-intensive production of synthesis gas and its conversion. Alternative routes have been discovered in academia, though high temperatures are mostly required. However, the direct conversion of methane to methanol is an exception. It can already be carried out at comparably low temperatures. It is challenging that methanol is more prone to oxidation than methane, which makes high selectivities at moderate conversions difficult to reach. Decades of research for the direct reaction of methane and oxygen did not yield a satisfactory solution for the direct partial oxidation toward methanol. When changing the oxidant from oxygen to hydrogen peroxide, high selectivities can be reached at rather low conversions, but the cost of hydrogen peroxide is comparably high. However, major advancements in the field were introduced by converting methane to a more stable methanol precursor. Most notable is the conversion of methane to methyl bisulfate in the presence of a platinum catalyst. The reaction is carried out in 102% sulfuric acid using SO3 as the oxidant. This allows for oxidation of the platinum catalyst and prevents the in situ hydrolysis of methyl bisulfate toward the less stable methanol. With a slightly different motif, the stepped conversion of methane to methanol over copper-zeolites was developed a decade ago. The copper-zeolite is first activated in oxygen at 450 °C, and then cooled to 200 °C and reacts with methane in the absence of oxygen, thus protecting a methanol precursor from overoxidation. Subsequently methanol can be extracted with water. Several active copper-zeolites were found, and the active sites were identified and discussed. For a long time, the process was almost unchanged

  3. A spontaneous and passive waste-management device (PWMD) for a micro direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Chuang, Yun-Ju; Chieng, Ching-Chang; Pan, Chin; Luo, Shih-Jin; Tseng, Fan-Gang

    2007-05-01

    This paper introduces a passive waste-management device (PWMD) for a micro direct methanol fuel cell to exhale CO2 gas and to gather and transport water and methanol residue during operation. It passively employs condensation, temperature gradient, surface tension gradient and droplet coalescence to accumulate liquid, separate liquid and gas, and transport droplets without the need of external power. CO2 gas can be breathed out through hydrophobic micro holes with the assistance of buoyancy force while water/methanol vapor is condensing into droplets, coalescing with smaller droplets and is transported toward a cooler and more hydrophilic waste tank through wettability gradient. The wettability gradient is prepared by diffusion-controlled silanization with a gradient from 117° to 28° and is radial toward the outer boundary, which can drive droplets down to 1 µl with a speed of up to 20 mm s-1. With the assistance of coalescence along with the wettability gradient, the condensed water droplets can reach a double speed of 40 mm s-1. The maximum water removal rate of the PWMD can approach 6.134 µl s-1 cm-2, which is at least one order of magnitude higher than the demand of a standard µDMFC with power generation ability of 100 mW cm-2.

  4. TUNING OF SIZE AND SHAPE OF AU-PT NANOCATALYST FOR DIRECT METHANOL FUEL CELLS

    SciTech Connect

    Murph, S.

    2011-04-20

    In this paper, we report the precise control of the size, shape and surface morphology of Au-Pt nanocatalysts (cubes, blocks, octahedrons and dogbones) synthesized via a seed-mediated approach. Gold 'seeds' of different aspect ratios (1 to 4.2), grown by a silver-assisted approach, were used as templates for high-yield production of novel Au-Pt nanocatalysts at a low temperature (40 C). Characterization by electron microscopy (SEM, TEM, HRTEM), energy dispersive X-ray analysis (EDX), UV-Vis spectroscopy, zeta-potential (surface charge), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to better understand their physico-chemical properties, preferred reactivities and underlying nanoparticle growth mechanism. A rotating disk electrode was used to evaluate the Au-Pt nanocatalysts electrochemical performance in the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) of direct methanol fuel cells. The results indicate the Au-Pt dogbones are partially and in some cases completely unaffected by methanol poisoning during the evaluation of the ORR. The ORR performance of the octahedron particles in the absence of MeOH is superior to that of the Au-Pt dogbones and Pt-black, however its performance is affected by the presence of MeOH.

  5. Radiation-grafted membranes based on polyethylene for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Sherazi, Tauqir A.; Guiver, Michael D.; Kingston, David; Ahmad, Shujaat; Kashmiri, M. Akram; Xue, Xinzhong

    Styrene was grafted onto ultrahigh molecular weight polyethylene powder (UHMWPE) by gamma irradiation using a 60Co source. Compression moulded films of selected pre-irradiated styrene-grafted ultrahigh molecular weight polyethylene (UHMWPE-g-PS) were post-sulfonated to the sulfonic acid derivative (UHMWPE-g-PSSA) for use as proton exchange membranes (PEMs). The sulfonation was confirmed by X-ray photoelectron spectroscopy (XPS). The melting and flow properties of UHMWPE and UHMWPE-g-PS are conducive to forming homogeneous pore-free membranes. Both the ion conductivity and methanol permeability coefficient increased with degree of grafting, but the grafted membranes showed comparable or higher ion conductivity and lower methanol permeability than Nafion ® 117 membrane. One UHMWPE-g-PS membrane was fabricated into a membrane-electrode assembly (MEA) and tested as a single cell direct methanol fuel cell (DMFC). Low membrane cost and acceptable fuel cell performance indicate that UHMWPE-g-PSSA membranes could offer an alternative approach to perfluorosulfonic acid-type membranes for DMFC.

  6. The effect of operation and design parameters on the performance of the direct methanol fuel cell

    SciTech Connect

    Simpson, S.F.; Cisar, A.; Franaszczuk, K.

    1996-12-31

    Fuel cell technology continues to receive considerable attention as a potential replacement for fossil fuels as a primary source of terrestrial power. Ideally, such power systems would operate at relatively low temperatures (< 100{degrees}C) which suggests strongly the use of cell technology based upon the proton exchange membrane (PEM). Without question, hydrogen is a very desirable fuel choice for these types of systems, because of its high energy density. However, the difficulties associated with the production and routine handling of hydrogen limit severely its commercial use at present. The direct methanol fuel cell (DMFC) is a particularly attractive alternative to the use of the hydrogen/oxygen cell. Although not as high as hydrogen, the energy density of methanol is the highest among the organic fuels. Furthermore, because of the similarity in liquid handling requirements between methanol and gasoline, a significant portion of the infrastructure necessary for the marketing and distribution of the fuel is already in place. Other inherent attributes of the DMFC which include rapid start-up and operation with little or no emission or noise signature have led to an intense DMFC research effort over the past twenty years and, indeed, the DMFC has even been referred to as {open_quotes}the electrochemist`s dream{close_quotes}.

  7. Model-based analysis of water management in alkaline direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Weinzierl, C.; Krewer, U.

    2014-12-01

    Mathematical modelling is used to analyse water management in Alkaline Direct Methanol Fuel Cells (ADMFCs) with an anion exchange membrane as electrolyte. Cathodic water supply is identified as one of the main challenges and investigated at different operation conditions. Two extreme case scenarios are modelled to study the feasible conditions for sufficient water supply. Scenario 1 reveals that water supply by cathodic inlet is insufficient and, thus, water transport through membrane is essential for ADMFC operation. The second scenario is used to analyse requirements on water transport through the membrane for different operation conditions. These requirements are influenced by current density, evaporation rate, methanol cross-over and electro-osmotic drag of water. Simulations indicate that water supply is mainly challenging for high current densities and demands on high water diffusion are intensified by water drag. Thus, current density might be limited by water transport through membrane. The presented results help to identify important effects and processes in ADMFCs with a polymer electrolyte membrane and to understand these processes. Furthermore, the requirements identified by modelling show the importance of considering water transport through membrane besides conductivity and methanol cross-over especially for designing new membrane materials.

  8. Coupled electrochemical and heat/mass transport characteristics in passive direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Chen, Rong

    methanol concentrations are obtained. It was further revealed that the improved performance with higher methanol concentrations is due primarily to the increased operating temperature resulting from the exothermic reaction between the permeated methanol and oxygen on the cathode. In addition, to further reflect the effect of two-phase heat and mass transport on the performance of the passive DMFC, we then developed a two-phase two-dimensional thermal model. With this model, the effects of methanol concentration, open ratio and channel and rib width on cell performance were investigated. It was found that although the larger open ratio and smaller channel and rib width exhibit the lower cell operating temperature as a result of the lower heat generation rate, the cell performance is still higher as a result of the increased mass transfer rate on both the anode and cathode. Keywords: Passive Direct Methanol Fuel Cell; Cell Performance; Thermal Effect; Open-circuit Condition; Methanol Concentration; Cell Orientation; Metal Foam, Effective Thermal Conductivity; Oxygen Transport; Mass Transfer Resistance; Two-phase Transport; Open Ratio; Channel and Rib Width.

  9. Effects of Nafion loading in anode catalyst inks on the miniature direct formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Morgan, Robert D.; Haan, John L.; Masel, Richard I.

    Nafion, within the anode and cathode catalyst layers, plays a large role in the performance of fuel cells, especially during the operation of the direct formic acid fuel cell (DFAFC). Nafion affects the proton transfer in the catalyst layers of the fuel cell, and studies presented here show the effects of three different Nafion loadings, 10 wt.%, 30 wt.% and 50 wt.%. Short term voltage-current measurements using the three different loadings show that 30 wt.% Nafion loading in the anode shows the best performance in the miniature, passive DFAFC. Nafion also serves as a binder to help hold the catalyst nanoparticles onto the proton exchange membrane (PEM). The DFAFC anode temporarily needs to be regenerated by raising the anode potential to around 0.8 V vs. RHE to oxidize CO bound to the surface, but the Pourbaix diagram predicts that Pd will corrode at these potentials. We found that an anode loading of 30 wt.% Nafion showed the best stability, of the three Nafion loadings chosen, for reducing the amount of loss of electrochemically active area due to high regeneration potentials. Only 58% of the area was lost after 600 potential cycles in formic acid compared to 96 and 99% for 10 wt.% and 50 wt.% loadings, respectively. Lastly we present cyclic voltammetry data that suggest that the Nafion adds to the production of CO during oxidation of formic acid for 12 h at 0.3 V vs. RHE. The resulting data showed that an increase in CO coverage was observed with increasing Nafion content in the anode catalyst layer.

  10. Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications.

    PubMed

    Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T C Mike

    2015-12-04

    This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young's modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO₂• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

  11. Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications

    PubMed Central

    Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T.C. Mike

    2015-01-01

    This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young’s modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO2• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications. PMID:26690232

  12. High Performance and Cost-Effective Direct Methanol Fuel Cells: Fe-N-C Methanol-Tolerant Oxygen Reduction Reaction Catalysts.

    PubMed

    Sebastián, David; Serov, Alexey; Artyushkova, Kateryna; Gordon, Jonathan; Atanassov, Plamen; Aricò, Antonino S; Baglio, Vincenzo

    2016-08-09

    Direct methanol fuel cells (DMFCs) offer great advantages for the supply of power with high efficiency and large energy density. The search for a cost-effective, active, stable and methanol-tolerant catalyst for the oxygen reduction reaction (ORR) is still a great challenge. In this work, platinum group metal-free (PGM-free) catalysts based on Fe-N-C are investigated in acidic medium. Post-treatment of the catalyst improves the ORR activity compared with previously published PGM-free formulations and shows an excellent tolerance to the presence of methanol. The feasibility for application in DMFC under a wide range of operating conditions is demonstrated, with a maximum power density of approximately 50 mW cm(-2) and a negligible methanol crossover effect on the performance. A review of the most recent PGM-free cathode formulations for DMFC indicates that this formulation leads to the highest performance at a low membrane-electrode assembly (MEA) cost. Moreover, a 100 h durability test in DMFC shows suitable applicability, with a similar performance-time behavior compared to common MEAs based on Pt cathodes.

  13. Three-dimensional multiscale analysis of degradation of nano- and micro-structure in direct methanol fuel cell electrodes after methanol starvation

    NASA Astrophysics Data System (ADS)

    Netzeband, Christian; Arlt, Tobias; Wippermann, Klaus; Lehnert, Werner; Manke, Ingo

    2016-09-01

    This study investigates the ageing effects on the microstructure of the anode catalyst layer of direct methanol fuel cells (DMFC) after complete methanol starvation. To this end the samples of two methanol-depleted membrane electrode assemblies (MEA) have been compared with a pristine reference sample. A three-dimensional characterization of the anode catalyst layer (ACL) structure on a nanometer scale has been conducted by focused ion beam (FIB)/scanning electron microscope (SEM) tomography. The FIB/SEM tomography allows for a detailed analysis of statistic parameters of micro-structured materials, such as porosity, tortuosity and pore size distributions. Furthermore, the SEM images displayed a high material contrast between the heavy catalyst metals (Pt/Ru) and the relatively light carbon support, which made it possible to map the catalyst distribution in the acquired FIB/SEM tomographies. Additional synchrotron X-ray tomographies have been conducted in order to obtain an overview of the structural changes of all the components of a section of the MEAs after methanol depletion.

  14. Polymer electrolytes based on sulfonated polysulfone for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Lufrano, F.; Baglio, V.; Staiti, P.; Arico', A. S.; Antonucci, V.

    This paper reports the development and characterization of sulfonated polysulfone (SPSf) polymer electrolytes for direct methanol fuel cells. The synthesis of sulfonated polysulfone was performed by a post sulfonation method using trimethyl silyl chlorosulfonate as a mild sulfonating agent. Bare polysulfone membranes were prepared with two different sulfonation levels (60%, SPSf-60 and 70%, SPSf-70), whereas, a composite membrane of SPSf-60 was prepared with 5 wt% silica filler. These membranes were investigated in direct methanol fuel cells (DMFCs) operating at low (30-40 °C) and high temperatures (100-120 °C). DMFC power densities were about 140 mW cm -2 at 100 °C with the bare SPSf-60 membrane and 180 mW cm -2 at 120 °C with the SPSf-60-SiO2 composite membrane. The best performance achieved at ambient temperature using a membrane with high degree of sulfonation (70%, SPSf-70) was 20 mW cm -2 at atmospheric pressure. This makes the polysulfone-based DMFC suitable for application in portable devices.

  15. Characterization of direct methanol fuel cell (DMFC) applications with H 2SO 4 modified chitosan membrane

    NASA Astrophysics Data System (ADS)

    Osifo, Peter O.; Masala, Aluwani

    Chitosan (Chs) flakes were prepared from chitin materials that were extracted from the exoskeleton of Cape rock lobsters in South Africa. The Chs flakes were prepared into membranes and the Chs membranes were modified by cross-linking with H 2SO 4. The cross-linked Chs membranes were characterized for the application in direct methanol fuel cells. The Chs membrane characteristics such as water uptake, thermal stability, proton resistance and methanol permeability were compared to that of high performance conventional Nafion 117 membranes. Under the temperature range studied 20-60 °C, the membrane water uptake for Chs was found to be higher than that of Nafion. Thermal analysis revealed that Chs membranes could withstand temperature as high as 230 °C whereas Nafion 117 membranes were stable to 320 °C under nitrogen. Nafion 117 membranes were found to exhibit high proton resistance of 284 s cm -1 than Chs membranes of 204 s cm -1. The proton fluxes across the membranes were 2.73 mol cm -2 s -1 for Chs- and 1.12 mol cm -2 s -1 Nafion membranes. Methanol (MeOH) permeability through Chs membrane was less, 1.4 × 10 -6 cm 2 s -1 for Chs membranes and 3.9 × 10 -6 cm 2 s -1 for Nafion 117 membranes at 20 °C. Chs and Nafion membranes were fabricated into membrane electrode assemblies (MAE) and their performances measure in a free-breathing commercial single cell DMFC. The Nafion membranes showed a better performance as the power density determined for Nafion membranes of 0.0075 W cm -2 was 2.7 times higher than in the case of Chs MEA.

  16. Microwave synthesis of polymer-embedded Pt-Ru catalyst for direct methanol fuel cell.

    PubMed

    Bensebaa, Farid; Farah, Abdiaziz A; Wang, Dashan; Bock, Christina; Du, Xiaomei; Kung, Judy; Le Page, Yvon

    2005-08-18

    Platinum-ruthenium nanoparticles stabilized within a conductive polymer matrix are prepared using microwave heating. Polypyrrole di(2-ethylhexyl) sulfosuccinate, or PPyDEHS, has been chosen for its known electrical conductivity, thermal stability, and solubility in polar organic solvents. A scalable and quick two-step process is proposed to fabricate alloyed nanoparticles dispersed in PPyDEHS. First a mixture of PPyDEHS and metallic precursors is heated in a microwave under reflux conditions. Then the nanoparticles are extracted by centrifugation. Physical characterization by TEM shows that crystalline and monodisperse alloyed nanoparticles with an average size of 2.8 nm are obtained. Diffraction data show that crystallite size is around 2.0 nm. Methanol electro-oxidation data allow us to propose these novel materials as potential candidates for direct methanol fuel cells (DMFC) application. The observed decrease in sulfur content in the polymer upon incorporation of PtRu nanoparticles may have adversely affected the measured catalytic activity by decreasing the conductivity of PPyDEHS. Higher concentration of polymer leads to lower catalyst activity. Design and synthesis of novel conductive polymers is needed at this point to enhance the catalytic properties of these hybrid materials.

  17. Artificial Intelligence Techniques for the Estimation of Direct Methanol Fuel Cell Performance

    NASA Astrophysics Data System (ADS)

    Hasiloglu, Abdulsamet; Aras, Ömür; Bayramoglu, Mahmut

    2016-04-01

    Artificial neural networks and neuro-fuzzy inference systems are well known artificial intelligence techniques used for black-box modelling of complex systems. In this study, Feed-forward artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS) are used for modelling the performance of direct methanol fuel cell (DMFC). Current density (I), fuel cell temperature (T), methanol concentration (C), liquid flow-rate (q) and air flow-rate (Q) are selected as input variables to predict the cell voltage. Polarization curves are obtained for 35 different operating conditions according to a statistically designed experimental plan. In modelling study, various subsets of input variables and various types of membership function are considered. A feed -forward architecture with one hidden layer is used in ANN modelling. The optimum performance is obtained with the input set (I, T, C, q) using twelve hidden neurons and sigmoidal activation function. On the other hand, first order Sugeno inference system is applied in ANFIS modelling and the optimum performance is obtained with the input set (I, T, C, q) using sixteen fuzzy rules and triangular membership function. The test results show that ANN model estimates the polarization curve of DMFC more accurately than ANFIS model.

  18. Stable operation of air-blowing direct methanol fuel cells with high performance

    NASA Astrophysics Data System (ADS)

    Park, Jun-Young; Lee, Jin-Hwa; Kim, Jirae; Han, Sangil; Song, Inseob

    A membrane electrode assembly (MEA) that is a combination of a catalyst-coated membrane (CCM) for the anode and a catalyst-coated substrate (CCS) for the cathode is studied under air-blower conditions for direct methanol fuel cells (DMFCs). Compared with MEAs prepared by only the CCS method, the performance of DMFC MEAs employing the combination method is significantly improved by 30% with less methanol crossover. This feature can be attributed to an enhanced electrode|membrane interface in the anode side and significantly higher catalyst efficiency. Furthermore, DMFC MEAs designed by the combination method retain high power density without any degradation, while the CCM-type cell shows a downward tendency in electrochemical performance under air-blower conditions. This may be due to MEAs with CCM have a much more difficult structure of catalytic active sites in the cathode to eliminate the water produced by electrochemical reaction. In addition, DMFCs produced via combination methods exhibit a lower water crossover flux than CCS alternatives, due to the comparatively dense structure of the CCM anode. Hence, DMFCs with a combination MEA structure demonstrate the feasibility of a small fuel cell system employing the low noise of a fan, instead of a noisy and large capacity air pump, for portable electronic devices.

  19. Highly active nitrogen-doped nanocarbon electrocatalysts for alkaline direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Kruusenberg, Ivar; Ratso, Sander; Vikkisk, Merilin; Kanninen, Petri; Kallio, Tanja; Kannan, Arunachala M.; Tammeveski, Kaido

    2015-05-01

    Direct methanol fuel cells are assembled and evaluated using Fumatech FAA3 alkaline anion exchange membrane. Two novel metal-free cathode catalysts are synthesised, investigated and compared with the commercial Pt-based catalyst. In this work nitrogen-doped few-layer graphene/multi-walled carbon nanotube (N-FLG/MWCNT) composite and nitrogen-doped MWCNT (N-MWCNT) catalyst are prepared by pyrolysing the mixture of dicyandiamide (DCDA) and carbon nanomaterials at 800 °C. The resulting cathode catalyst material shows a remarkable electrocatalytic activity for oxygen reduction reaction (ORR) in 0.1 M KOH solution employing the rotating disk electrode (RDE) method. Fuel cell tests are performed by using 1 M methanol as anode and pure oxygen gas cathode feed. The maximum power density obtained with the N-FLG/MWCNT material (0.72 mW cm-2) is similar to that of the Pt/C catalyst (0.72 mW cm-2), whereas the N-MWCNT material shows higher peak power density (0.92 mW cm-2) than the commercial Pt/C catalyst.

  20. The electrolyte challenge for a direct methanol-air polymer electrolyte fuel cell operating at temperatures up to 200 C

    NASA Technical Reports Server (NTRS)

    Savinell, Robert; Yeager, Ernest; Tryk, Donald; Landau, Uziel; Wainright, Jesse; Gervasio, Dominic; Cahan, Boris; Litt, Morton; Rogers, Charles; Scherson, Daniel

    1993-01-01

    Novel polymer electrolytes are being evaluated for use in a direct methanol-air fuel cell operating at temperatures in excess of 100 C. The evaluation includes tests of thermal stability, ionic conductivity, and vapor transport characteristics. The preliminary results obtained to date indicate that a high temperature polymer electrolyte fuel cell is feasible. For example, Nafion 117 when equilibrated with phosphoric acid has a conductivity of at least 0.4 Omega(exp -1)cm(exp -1) at temperatures up to 200 C in the presence of 400 torr of water vapor and methanol vapor cross over equivalent to 1 mA/cm(exp 2) under a one atmosphere methanol pressure differential at 135 C. Novel polymers are also showing similar encouraging results. The flexibility to modify and optimize the properties by custom synthesis of these novel polymers presents an exciting opportunity to develop an efficient and compact methanol fuel cell.

  1. SHAPE SELECTIVE NANO-CATALYSTS: TOWARD DIRECT METHANOL FUEL CELLS APPLICATIONS

    SciTech Connect

    Murph, S.

    2010-06-16

    A series of bimetallic core-shell-alloy type Au-Pt nanomaterials with various morphologies, aspect ratios and compositions, were produced in a heterogenous epitaxial fashion. Gold nanoparticles with well-controlled particle size and shape, e.g. spheres, rods and cubes, were used as 'seeds' for platinum growth in the presence of a mild reducing agent, ascorbic acid and a cationic surfactant cethyltrimethyl ammonium bromide (CTAB). The reactions take place in air and water, and are quick, economical and amenable for scaling up. The synthesized nanocatalysts were characterized by electron microscopy techniques and energy dispersive X-ray analysis. Nafion membranes were embedded with the Au-Pt nanomaterials and analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM) for their potential in direct methanol fuel cells applications.

  2. Catalyst inks and method of application for direct methanol fuel cells

    DOEpatents

    Zelenay, Piotr; Davey, John; Ren, Xiaoming; Gottesfeld, Shimshon; Thomas, Sharon C.

    2004-02-24

    Inks are formulated for forming anode and cathode catalyst layers and applied to anode and cathode sides of a membrane for a direct methanol fuel cell. The inks comprise a Pt catalyst for the cathode and a Pt--Ru catalyst for the anode, purified water in an amount 4 to 20 times that of the catalyst by weight, and a perfluorosulfonic acid ionomer in an amount effective to provide an ionomer content in the anode and cathode surfaces of 20% to 80% by volume. The inks are prepared in a two-step process while cooling and agitating the solutions. The final solution is placed in a cooler and continuously agitated while spraying the solution over the anode or cathode surface of the membrane as determined by the catalyst content.

  3. A monolithic integrated micro direct methanol fuel cell based on sulfo functionalized porous silicon

    NASA Astrophysics Data System (ADS)

    Wang, M.; Lu, Y. X.; Liu, L. T.; Wang, X. H.

    2016-11-01

    In this paper, we demonstrate a monolithic integrated micro direct methanol fuel cell (μDMFC) for the first time. The monolithic integrated μDMFC combines proton exchange membrane (PEM) and Pt nanocatalysts, in which PEM is achieved by the functionalized porous silicon membrane and 3D Pt nanoflowers being synthesized in situ on it as catalysts. Sulfo groups functionalized porous silicon membrane serves as a PEM and a catalyst support simultaneously. The μDMFC prototype achieves an open circuit voltage of 0.3 V, a maximum power density of 5.5 mW/cm2. The monolithic integrated μDMFC offers several desirable features such as compatibility with micro fabrication techniques, an undeformable solid PEM and the convenience of assembly.

  4. Directed assembly of nanomaterials for miniaturized sensors by dip-pen nanolithography using precursor inks

    NASA Astrophysics Data System (ADS)

    Su, Ming

    The advent of nanomaterials with enhanced properties and the means to pattern them in a controlled fashion have paved the way to construct miniaturized sensors for improved detection. However it remains a challenge for the traditional methods to create such sensors and sensor arrays. Dip pen nanolithography (DPN) can form nanostructures on a substrate by controlling the transfer of molecule inks. However, previous DPN can not pattern solid materials on insulating surfaces, which are necessary to form functional electronic devices. In the dissertation, the concept of reactive precursor inks for DPN is developed for the generation of solid functional nanostructures of the following materials: organic molecule, sol-gel material, and conducting polymer. First, the covalent bonding is unnecessary for DPN as shown in the colored ink DPN; therefore the numbers of molecules that can be patterned is extended beyond thiol or thiolated molecules. Subsequently, a reactive precursor strategy (sol) is developed to pattern inorganic or organic/inorganic composite nanostructures on silicon based substrates. The method works by hydrolysis of metal precursors in the water meniscus and allows the preparation of solid structures with controlled geometry beyond the individual molecule level. Then the SnO 2 nanostructures patterned between the gaps of electrodes are tested as gas sensors. Proof-of-concept experiments are demonstrated on miniaturized sensors that show fast response and recovery to certain gases. Furthermore, an eight-unit sensor array is fabricated on a chip using SnO2 sols that are doped with different metals. The multiplexed device can recognize different gases by comparing the response patterns with the reference patterns of known gases generated on the same array. At last, the idea of precursor ink for DPN is extended to construct conducting polymer based devices. By using an acid promoted polymerization approach, conducting polymers are patterned on silicon dioxide

  5. Direct methane conversion to methanol. Annual report, October 1993--September 1994

    SciTech Connect

    Noble, R.D.; Falconer, J.L.

    1995-01-01

    We proposed to demonstrate the effectiveness of a catalytic membrane reactor (a ceramic membrane combined with a catalyst) to selectively produce methanol by partial oxidation of methane. Methanol is used as a chemical feedstock, gasoline additive, and turbine fuel. Methane partial oxidation using a catalytic membrane reactor has been determined as one of the promising approaches for methanol synthesis from methane. In the original proposal, the membrane was used to selectively remove methanol from the reaction zone before carbon oxides form, thus increasing the methanol yield. Methanol synthesis and separation in one step would also make methane more valuable for producing chemicals and fuels. However, all the membranes tested in this laboratory lost their selectivity under the reaction conditions. A modified non-isothermal, non-permselective membrane reactor then was built and satisfactory results were obtained. The conversion and selectivity data obtained in this laboratory were better than that of the most published studies.

  6. Recent advances in direct methanol fuel cells at Los Alamos National Laboratory

    NASA Astrophysics Data System (ADS)

    Ren, Xiaoming; Zelenay, Piotr; Thomas, Sharon; Davey, John; Gottesfeld, Shimshon

    This paper describes recent advances in the science and technology of direct methanol fuel cells (DMFCs) made at Los Alamos National Laboratory (LANL). The effort on DMFCs at LANL includes work devoted to portable power applications, funded by the Defense Advanced Research Project Agency (DARPA), and work devoted to potential transport applications, funded by the US DOE. We describe recent results with a new type of DMFC stack hardware that allows to lower the pitch per cell to 2 mm while allowing low air flow and air pressure drops. Such stack technology lends itself to both portable power and potential transport applications. Power densities of 300 W/l and 1 kW/l seem achievable under conditions applicable to portable power and transport applications, respectively. DMFC power system analysis based on the performance of this stack, under conditions applying to transport applications (joint effort with U.C. Davis), has shown that, in terms of overall system efficiency and system packaging requirements, a power source for a passenger vehicle based on a DMFC could compete favorably with a hydrogen-fueled fuel cell system, as well as with fuel cell systems based on fuel processing on board. As part of more fundamental studies performed, we describe optimization of anode catalyst layers in terms of PtRu catalyst nature, loading and catalyst layer composition and structure. We specifically show that, optimized content of recast ionic conductor added to the catalyst layer is a sensitive function of the nature of the catalyst. Other elements of membrane/electrode assembly (MEA) optimization efforts are also described, highlighting our ability to resolve, to a large degree, a well-documented problem of polymer electrolyte DMFCs, namely "methanol crossover". This was achieved by appropriate cell design, enabling fuel utilization as high as 90% in highly performing DMFCs.

  7. Study of catalysis for solid oxide fuel cells and direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Jiang, Xirong

    Fuel cells offer the enticing promise of cleaner electricity with lower environmental impact than traditional energy conversion technologies. Driven by the interest in power sources for portable electronics, and distributed generation and automotive propulsion markets, active development efforts in the technologies of both solid oxide fuel cell (SOFC) and direct methanol fuel cell (DMFC) devices have achieved significant progress. However, current catalysts for fuel cells are either of low catalytic activity or extremely expensive, presenting a key barrier toward the widespread commercialization of fuel cell devices. In this thesis work, atomic layer deposition (ALD), a novel thin film deposition technique, was employed to apply catalytic Pt to SOFC, and investigate both Pt skin catalysts and Pt-Ru catalysts for methanol oxidation, a very important reaction for DMFC, to increase the activity and utilization levels of the catalysts while simultaneously reducing the catalyst loading. For SOFCs, we explored the use of ALD for the fabrication of electrode components, including an ultra-thin Pt film for use as the electrocatalyst, and a Pt mesh structure for a current collector for SOFCs, aiming for precise control over the catalyst loading and catalyst geometry, and enhancement in the current collect efficiency. We choose Pt since it has high chemical stability and excellent catalytic activity for the O2 reduction reaction and the H2 oxidation reaction even at low operating temperatures. Working SOFC fuel cells were fabricated with ALD-deposited Pt thin films as an electrode/catalyst layer. The measured fuel cell performance reveals that comparable peak power densities were achieved for ALD-deposited Pt anodes with only one-fifth of the Pt loading relative to a DC-sputtered counterpart. In addition to the continuous electrocatalyst layer, a micro-patterned Pt structure was developed via the technique of area selective ALD. By coating yttria-stabilized zirconia, a

  8. Direct observation of hexamethylbenzenium radical cations generated during zeolite methanol-to-olefin catalysis: an ESR study.

    PubMed

    Kim, Sun Jung; Jang, Hoi-Gu; Lee, Jun Kyu; Min, Hyung-Ki; Hong, Suk Bong; Seo, Gon

    2011-09-07

    The generation of hexamethylbenzenium radical cations as the key reaction intermediate in chabazite-type molecular sieve acids (i.e., H-SAPO-34 and H-SSZ-13) during the methanol-to-olefin process has been directly evidenced by ESR spectroscopy.

  9. Non-syngas direct steam reforming of methanol to hydrogen and carbon dioxide at low temperature.

    PubMed

    Yu, Kai Man Kerry; Tong, Weiyi; West, Adam; Cheung, Kevin; Li, Tong; Smith, George; Guo, Yanglong; Tsang, Shik Chi Edman

    2012-01-01

    A non-syngas direct steam reforming route is investigated for the conversion of methanol to hydrogen and carbon dioxide over a CuZnGaO(x) catalyst at 150-200 °C. This route is in marked contrast with the conventional complex route involving steam reformation to syngas (CO/H2) at high temperature, followed by water gas shift and CO cleanup stages for hydrogen production. Here we report that high quality hydrogen and carbon dioxide can be produced in a single-step reaction over the catalyst, with no detectable CO (below detection limit of 1 ppm). This can be used to supply proton exchange membrane fuel cells for mobile applications without invoking any CO shift and cleanup stages. The working catalyst contains, on average, 3-4 nm copper particles, alongside extremely small size of copper clusters stabilized on a defective ZnGa2O4 spinel oxide surface, providing hydrogen productivity of 393.6 ml g(-1)-cat h(-1) at 150 °C.

  10. Passive cathodic water/air management device for micro-direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Peng, Hsien-Chih; Chen, Po-Hon; Chen, Hung-Wen; Chieng, Ching-Chang; Yeh, Tsung-Kuang; Pan, Chin; Tseng, Fan-Gang

    A high efficient passive water/air management device (WAMD) is proposed and successfully demonstrated in this paper. The apparatus consists of cornered micro-channels and air-breathing windows with hydrophobicity arrangement to regulate liquids and gases to flow on their predetermined pathways. A high performance water/air separation with water removal rate of about 5.1 μl s -1 cm -2 is demonstrated. The performance of the proposed WAMD is sufficient to manage a cathode-generated water flux of 0.26 μl s -1 cm -2 in the micro-direct methanol fuel cells (μDMFCs) which are operated at 100 mW cm -2 or 400 mA cm -2. Furthermore, the condensed vapors can also be collected and recirculated with the existing micro-channels which act as a passive water recycling system for μDMFCs. The durability testing shows that the fuel cells equipped with WAMD exhibit improved stability and higher current density.

  11. Quantitative study of ruthenium cross-over in direct methanol fuel cells during early operation hours

    NASA Astrophysics Data System (ADS)

    Schoekel, A.; Melke, J.; Bruns, M.; Wippermann, K.; Kuppler, F.; Roth, C.

    2016-01-01

    In direct methanol fuel cells (DMFC), ruthenium cross-over is an important degradation phenomenon. The loss of ruthenium from the anode, its transport through the membrane and its deposition onto the cathode are detrimental to the fuel cell performance and limit the fuel cell's lifetime. Here we present a quantitative study on the fraction of ruthenium being transferred from the anode to the cathode during early operation hours (0-100 h) of a DMFC. Already during fabrication of the MEA ruthenium is transferred to the cathode. In our pristine MEAs about 0.024 wt% Ru could be found in the cathode catalyst. The cell potential during operation seems to have only a minor influence on the dissolution process. In contrast, the operation time appears to be much more important. Our data hint at two dissolution processes: a fast process dominating the first hours of operation and a slower process, which is responsible for the ongoing ruthenium transfer during the fuel cell lifetime. After 2 h held at open circuit conditions the Ru content of the cathode side was 10 times higher than in the pristine MEA. In contrast, the slower process increased that amount only by a factor of two over the course of another 100 h.

  12. Novel mesoporous carbon ceramics composites as electrodes for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Gallo, Jean Marcel R.; Gatti, Giorgio; Graizzaro, Alessandro; Marchese, Leonardo; Pastore, Heloise O.

    2011-10-01

    In this work, a new family of materials for electrodes of direct methanol fuel cell (DMFC) is presented. Mesoporous carbon ceramics (MCCs) are obtained by the addition of commercial graphite into the synthesis gel of SBA-15 mesoporous silica with SiO2/C weight ratios of 1/1 and 1/3. X-ray diffraction confirms both the formation of organized silica and the presence of graphite, and nitrogen physisorption measurements show that the presence of a graphitic phase does not interfere in the silica pore diameter although it diminishes the surface area. The MCCs modified with Pt or PtRu are tested as DMFC electrodes and compared with the commercial support Vulcan XC-72R. When used as cathode, the system using MCC-SBA-15 with SiO2/C weight ratios of 1/1 presents a negligible performance, while the MCC-SBA-15 with SiO2/C weight ratios of 1/3 is 2.9 times less active than the commercial support. On the other side, when used as anode, the MCC-SBA-15 with SiO2/C weight ratios of 1/3 displays performances comparable to Vulcan XC-72R.

  13. High throughput evaluation of perovskite-based anode catalysts for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Deshpande, Kishori; Mukasyan, Alexander; Varma, Arvind

    Liquid feed direct methanol fuel cells (DMFC) are promising candidates for portable power applications. However, owing to the problems associated with expensive Pt-based catalysts, viz., CO poisoning, a promising approach is to use complex oxides of the type ABO 3 (A = Sr, Ce, La, etc. and B = Co, Fe, Ni, Pt, Ru, etc.). In the current work, a variety of ABO 3 and A 2BO 4 type non-noble and partially substituted noble metal high surface area compounds were synthesized by an effective and rapid aqueous combustion synthesis (CS). Their catalytic activity was evaluated by using "High Throughput Screening Unit"-NuVant System, which compares up to 25 compositions simultaneously under DMFC conditions. It was found that the Sr-based perovskites showed performance comparable with the standard Pt-Ru catalyst. Further, it was observed that the method of doping SrRuO 3 with Pt influenced the activity. Specifically, platinum added during aqueous CS yielded better catalyst than when added externally at the ink preparation stage. Finally, it was also demonstrated that the presence of SrRuO 3 significantly enhanced the catalytic properties of Pt, leading to superior performance even at lower noble metal loadings.

  14. Reliability and availability analysis of low power portable direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Sisworahardjo, N. S.; Alam, M. S.; Aydinli, G.

    This paper presents a methodology for modeling and calculating the reliability and availability of low power portable direct methanol fuel cells (DMFCs). System reliability and availability are critical factors for improving market acceptance and for determining the competitiveness of the low power DMFC. Two techniques have been used for analyzing the system reliability and availability requirements for various system components. Reliability block diagram (RBD) is formed based on the failure rates of irreparable system components. A state-space method is developed to calculate system availability using the Markov model (MM). The state-space method incorporates three different states-operational, derated, and fully faulted states. Since most system components spend their lifetime in performing normal functional task, this research is focused mainly on this operational period. The failure and repair rates for repairable DMFC systems are estimated on the basis of a homogeneous Poisson process (HPP) and exponential distribution. Extensive analytical modeling and simulation study has been performed to verify the effectiveness of the proposed technique.

  15. Fabrication of low-methanol-permeability sulfonated poly(phenylene oxide) membranes with hollow glass microspheres for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Ahn, Kisang; Kim, Myeongjin; Kim, Kiho; Ju, Hyun; Oh, Ilgeun; Kim, Jooheon

    2015-02-01

    Organic/inorganic composite membranes, based on sulfonated poly(phenylene oxide) (SPPO) and hollow glass microspheres (HGMs), with various compositions are prepared for use as proton exchange membranes in direct methanol fuel cells (DMFCs). Reaction time between chlorosulfonic acid solution and PPO is controlled to improve proton conductivity of the SPPO membrane. As a result, SPPO at 38.2% sulfonation is selected as the optimum degree of sulfonation. Afterwards, SPPO is successfully introduced onto the surfaces of HGMs to increase their dispersion in the SPPO matrix. The ion exchange capacities (IEC) and proton conductivities of the membranes decrease with increasing amounts of the SPPO-HGMs, because of the decrease of ionic sites with increasing HGM content. The SPPO-HGM composite membranes exhibit proton conductivities ranging from 0.0350 to 0.0212 S cm-1 and low methanol permeability ranging from 1.02 × 10-6 to 3.41 × 10-7 cm2 s-1 at 20 °C. Furthermore, the SPPO-HGM 9 wt%/SPPO membrane presents a maximum power density of 81.5 mW cm-2 and open circuit voltage of 0.70 V.

  16. Self-assembled platinum nanoparticles on sulfonic acid-grafted graphene as effective electrocatalysts for methanol oxidation in direct methanol fuel cells

    PubMed Central

    Lu, Jinlin; Li, Yanhong; Li, Shengli; Jiang, San Ping

    2016-01-01

    In this article, sulfonic acid-grafted reduced graphene oxide (S-rGO) were synthesized using a one-pot method under mild conditions, and used as Pt catalyst supports to prepare Pt/S-rGO electrocatalysts through a self-assembly route. The structure, morphologies and physicochemical properties of S-rGO were examined in detail by techniques such as atomic force microscope (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The S-rGO nanosheets show excellent solubility and stability in water and the average particle size of Pt nanoparticles supported on S-rGO is ~3.8 nm with symmetrical and uniform distribution. The electrocatalytic properties of Pt/S-rGO were investigated for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). In comparison to Pt supported on high surface area Vulcan XC-72 carbon (Pt/VC) and Pt/rGO, the Pt/S-rGO electrocatalyst exhibits a much higher electrocatalytic activity, faster reaction kinetics and a better stability. The results indicate that Pt/S-rGO is a promising and effective electrocatalyst for MOR of DMFCs. PMID:26876468

  17. Self-assembled platinum nanoparticles on sulfonic acid-grafted graphene as effective electrocatalysts for methanol oxidation in direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Lu, Jinlin; Li, Yanhong; Li, Shengli; Jiang, San Ping

    2016-02-01

    In this article, sulfonic acid-grafted reduced graphene oxide (S-rGO) were synthesized using a one-pot method under mild conditions, and used as Pt catalyst supports to prepare Pt/S-rGO electrocatalysts through a self-assembly route. The structure, morphologies and physicochemical properties of S-rGO were examined in detail by techniques such as atomic force microscope (AFM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The S-rGO nanosheets show excellent solubility and stability in water and the average particle size of Pt nanoparticles supported on S-rGO is ~3.8 nm with symmetrical and uniform distribution. The electrocatalytic properties of Pt/S-rGO were investigated for methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). In comparison to Pt supported on high surface area Vulcan XC-72 carbon (Pt/VC) and Pt/rGO, the Pt/S-rGO electrocatalyst exhibits a much higher electrocatalytic activity, faster reaction kinetics and a better stability. The results indicate that Pt/S-rGO is a promising and effective electrocatalyst for MOR of DMFCs.

  18. Molecular simulation of polyphosphazenes as gas separation and direct methanol fuel cell membranes

    NASA Astrophysics Data System (ADS)

    Hu, Naiping

    in the crystalline supercell to a higher-energy, lower-ordered structure in the mesophase. In the study of PBMP as potential direct methanol fuel cell membranes, the structures, equilibrium water swelling, methanol and water self-diffusion coefficients, and proton conductivity of sulfonated PBMP (crosslinked and non-crosslinked) have been simulated by molecular dynamics methods using a modified COMPASS force field. Both the equilibrium water swelling and the densities obtained for hydrated PBMP cells agree with the experimental values. In addition, the results of self-diffusion coefficients showed that methanol self-diffusion is only affected by the extent of crosslinking but self-diffusion of the hydronium ion is not affected. The results of proton conductivity suggest that at low hydration levels, proton and hydronium ion diffusion coefficients are both very low and the polymer is non-conducting; however increasing water content results in both greater hydronium ion diffusion and higher proton conductivity.

  19. Direct identification of prohibited substances in cosmetics and foodstuffs using ambient ionization on a miniature mass spectrometry system.

    PubMed

    Ma, Qiang; Bai, Hua; Li, Wentao; Wang, Chao; Li, Xinshi; Cooks, R Graham; Ouyang, Zheng

    2016-03-17

    Significantly simplified work flows were developed for rapid analysis of various types of cosmetic and foodstuff samples by employing a miniature mass spectrometry system and ambient ionization methods. A desktop Mini 12 ion trap mass spectrometer was coupled with paper spray ionization, extraction spray ionization and slug-flow microextraction for direct analysis of Sudan Reds, parabens, antibiotics, steroids, bisphenol and plasticizer from raw samples with complex matrices. Limits of detection as low as 5 μg/kg were obtained for target analytes. On-line derivatization was also implemented for analysis of steroid in cosmetics. The developed methods provide potential analytical possibility for outside-the-lab screening of cosmetics and foodstuff products for the presence of illegal substances.

  20. Application of green chemistry techniques to prepare electrocatalysts for direct methanol fuel cells.

    PubMed

    Shimizu, Kenichi; Wang, Joanna S; Wai, Chien M

    2010-03-25

    A series of green techniques for synthesizing carbon nanotube-supported platinum nanoparticles and their high electrocatalytic activity toward methanol fuel cell applications are reported. The techniques utilize either the supercritical fluid carbon dioxide or water as a medium for depositing platinum nanoparticles on surfaces of multiwalled or single-walled carbon nanotubes. The catalytic properties of the carbon nanotubes-supported Pt nanoparticle catalysts prepared by four different techniques are compared for anodic oxidation of methanol and cathodic reduction of oxygen using cyclic voltammetry. One technique using galvanic exchange of Pt(2+) in water with zerovalent iron present on the surfaces of as-grown single-walled carbon nanotubes produces a Pt catalyst that shows an unusually high catalytic activity for reduction of oxygen but a negligible activity for oxidation of methanol. This fuel-selective catalyst may have a unique application as a cathode catalyst in methanol fuel cells to alleviate the problems caused by crossover of methanol through the polymer electrolyte membrane.

  1. In and ex situ characterization of an anion-exchange membrane for alkaline direct methanol fuel cell (ADMFC)

    NASA Astrophysics Data System (ADS)

    Santasalo-Aarnio, Annukka; Hietala, Sami; Rauhala, Taina; Kallio, Tanja

    2011-08-01

    Anion exchange membrane fumasep® FAA-2 was characterized with ex and in situ methods in order to estimate the membranes' suitability as an electrolyte for an alkaline direct methanol fuel cell (ADMFC). The interactions of this membrane with water, hydroxyl ions and methanol were studied with both calorimetry and NMR and compared with the widely used proton exchange membrane Nafion® 115. The results indicate that FAA-2 has a tighter structure and more homogeneous distribution of ionic groups in contrast to the clustered structure of Nafion, moreover, the diffusion of OH- ions through this membrane is clearly slower compared to water molecules. The permeability of methanol through the FAA-2 membrane was found to be an order of magnitude lower than for Nafion. Fuel cell experiments in 1 mol dm-3 methanol with FAA-2 resulted in OCV of 0.58 V and maximum power density of 0.32 mW cm-2. However, even higher current densities were obtained with highly concentrated fuels. This implies that less water is needed for fuel dilution, thereby decreasing the mass of the fuel cell system. In addition, electrochemical impedance spectroscopy for the ADMFC was used to determine ohmic resistance of the cell facilitating the further membrane development.

  2. Facile synthesis of Pt-Pd@Silicon nanostructure as an advanced electrocatalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Ensafi, Ali A.; Jafari-Asl, M.; Rezaei, B.; Abarghoui, M. Mokhtari; Farrokhpour, H.

    2015-05-01

    In this work, platinum-palladium (Pt-Pd) is assembled in-situ on the surface of porous silicon flour (PSiF) through chemical reduction of PtCl62-/PdCl42- and oxidation of the precursor solution SiF64-. The components and the morphological properties of the Pt-Pd on PSiF is investigated by means of transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction techniques. In the next stage, screen printed graphene electrode (SPGE) is prepared by electro-reduction of exfoliated graphene oxide at the surface of a screen printed carbon electrode (SPCE), which is subsequently characterized by FT-IR, Raman spectroscopy, FE-SEM, and electrochemical methods. Finally, a combination of Pt-Pd@PSi nanostructure and SPGE is used for the electro-oxidation of methanol in direct methanol fuel cell. The electrochemical results demonstrate that the Pt-Pd@PSiF-SPGE exhibits an excellent electrocatalytic activity for methanol oxidation. In addition, the electron transfer kinetic of methanol oxidation on Pt-Pd@PSiF-SPGE is investigated by electrochemical impedance spectroscopy. The results showed that the surface of Pt-Pd@PSiF-SPGE is not affected (poisoned) by intermediate products such as CO.

  3. Ni2P Makes Application of the PtRu Catalyst Much Stronger in Direct Methanol Fuel Cells.

    PubMed

    Chang, Jinfa; Feng, Ligang; Liu, Changpeng; Xing, Wei

    2015-10-12

    PtRu is regarded as the best catalyst for direct methanol fuel cells, but the performance decay resulting from the loss of Ru seriously hinders commercial applications. Herein, we demonstrated that the presence of Ni2 P largely reduces Ru loss, which thus makes the application of PtRu much stronger in direct methanol fuel cells. Outstanding catalytic activity and stability were observed by cyclic voltammetry. Upon integrating the catalyst material into a practical direct methanol fuel cell, the highest maximum power density was achieved on the PtRu-Ni2P/C catalyst among the reference catalysts at different temperatures. A maximum power density of 69.9 mW cm(-2) at 30 °C was obtained on PtRu-Ni2P/C, which is even higher than the power density of the state-of-the-art commercial PtRu catalyst at 70 °C (63.1 mW cm(-2)). Moreover, decay in the performance resulting from Ru loss was greatly reduced owing to the presence of Ni2 P, which is indicative of very promising applications.

  4. Direct methane conversion to methanol. Final report, April 13, 1995--September 30, 1996

    SciTech Connect

    Noble, R.D.; Falconer, J.L.

    1998-01-01

    We proposed to demonstrate the effectiveness of a catalytic membrane reactor (a ceramic membrane combined with a catalyst) to selectively produce methanol by partial oxidation of methane. Methanol is used as a chemical feed stock, gasoline additive, and turbine fuel. Methane partial oxidation using a catalytic membrane reactor has been determined as one of the promising approaches for methanol synthesis from methane. Methanol synthesis and separation in one step would also make methane more valuable for producing chemicals and fuels. Another valuable fuel product is H{sub 2}. Its separation from other gasification products would make it very valuable as a chemical feedstock and clean fuel for fuel cells. Gasification of coal or other organic fuels as a source of H{sub 2} produces compounds (CO, CO{sub 2}, and H{sub 2}O) that require high temperature (1000-1500 degrees F) and high pressure (600-1000 psia) separations. A zeolite membrane layer on a mechanically stable ceramic or stainless steel support would have ideal applications for this type of separation.

  5. Bimetallic Nickel/Ruthenium Catalysts Synthesized by Atomic Layer Deposition for Low-Temperature Direct Methanol Solid Oxide Fuel Cells.

    PubMed

    Jeong, Heonjae; Kim, Jun Woo; Park, Joonsuk; An, Jihwan; Lee, Tonghun; Prinz, Fritz B; Shim, Joon Hyung

    2016-11-09

    Nickel and ruthenium bimetallic catalysts were heterogeneously synthesized via atomic layer deposition (ALD) for use as the anode of direct methanol solid oxide fuel cells (DMSOFCs) operating in a low-temperature range. The presence of highly dispersed ALD Ru islands over a porous Ni mesh was confirmed, and the Ni/ALD Ru anode microstructure was observed. Fuel cell tests were conducted using Ni-only and Ni/ALD Ru anodes with approximately 350 μm thick gadolinium-doped ceria electrolytes and platinum cathodes. The performance of fuel cells was assessed using pure methanol at operating temperatures of 300-400 °C. Micromorphological changes of the anode after cell operation were investigated, and the content of adsorbed carbon on the anode side of the operated samples was measured. The difference in the maximum power density between samples utilizing Ni/ALD Ru and Pt/ALD Ru, the latter being the best catalyst for direct methanol fuel cells, was observed to be less than 7% at 300 °C and 30% at 350 °C. The improved electrochemical activity of the Ni/ALD Ru anode compared to that of the Ni-only anode, along with the reduction of the number of catalytically active sites due to agglomeration of Ni and carbon formation on the Ni surface as compared to Pt, explains this decent performance.

  6. Highly dispersed Pt-Ni nanoparticles on nitrogen-doped carbon nanotubes for application in direct methanol fuel cells.

    PubMed

    Jiang, Shujuan; Ma, Yanwen; Tao, Haisheng; Jian, Guoqiang; Wang, Xizhang; Fan, Yining; Zhu, Jianmin; Hu, Zheng

    2010-06-01

    Binary Pt-Ni alloyed nanoparticles supported on nitrogen-doped carbon nanotubes (NCNTs) have been facilely constructed without pre-modification by making use of the active sites in NCNTs due to the N-participation. So-obtained binary Pt-Ni alloyed nanoparticles have been highly dispersed on the outer surface of the support with the size of about 3-4 nm. The electrochemical properties of the catalysts for methanol oxidation have been systematically evaluated. Binary Pt-Ni alloyed composites with molar ratio (Pt:Ni) of 3:2 and 3:1 present enhanced electrocatalytic activities and improved tolerance to CO poisoning as well as the similar stability, in comparison with the commercial Pt/C catalyst and the monometallic Pt/NCNTs catalysts. These results imply that so-constructed nanocomposite catalysts have the potential for applications in direct methanol fuel cells.

  7. Analysis of the electrochemical characteristics of a direct methanol fuel cell based on a Pt-Ru/C anode catalyst

    SciTech Connect

    Arico, A.S.; Creti, P.; Mantegna, R.

    1996-12-31

    This paper deals with a vapour-feed direct methanol fuel cell (DMFC) based on a Nafion 117{reg_sign} solid polymer electrolyte. Pt-Ru/C and Pt/C catalysts were employed for methanol oxidation and oxygen reduction, respectively. Structure and surface chemistry of catalysts were investigated by X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Membrane/electrode assembly (M&E) was prepared by using a {open_quotes}paste process{close_quotes} method. Electrical power densities of about 150 mW cm{sup -2} were obtained at 95{degrees} C with Pt loadings of 0.8 and 0.5 mg cm{sup -2} at anode and cathode respectively.

  8. Polyphosphazene-Based Proton-Exchange Membranes for Direct Liquid Methanol Fuel Cells

    DTIC Science & Technology

    2005-11-04

    sulfonic acid site), as shown in Figure 9 and (ii) the neutralization of some sulfonic acid groups in SPOP due to complexation with PBI (see Figure 10...polybenzimidazole (for acid -base complexation crosslinking) prior to membrane casting. Some of the films containing poly[bis(3- methylphenoxy)phosphazene...sulfonated poly[bis(phenoxy)phosphazene] (SPOP) and polybenzimidazole ( PBI ) worked particularly well in a DMFC (at 60oC 1.0 M methanol, and ambient

  9. Performance of composite Nafion/PVA membranes for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Mollá, Sergio; Compañ, Vicente

    2011-03-01

    This work has been focused on the characterization of the methanol permeability and fuel cell performance of composite Nafion/PVA membranes in function of their thickness, which ranged from 19 to 97 μm. The composite membranes were made up of Nafion® polymer deposited between polyvinyl alcohol (PVA) nanofibers. The resistance to methanol permeation of the Nafion/PVA membranes shows a linear variation with the thickness. The separation between apparent and true permeability permits to give an estimated value of 4.0 × 10-7 cm2 s-1 for the intrinsic or true permeability of the bulk phase at the composite membranes. The incorporation of PVA nanofibers causes a remarkable reduction of one order of magnitude in the methanol permeability as compared with pristine Nafion® membranes. The DMFC performances of membrane-electrode assemblies prepared from Nafion/PVA and pristine Nafion® membranes were tested at 45, 70 and 95 °C under various methanol concentrations, i.e., 1, 2 and 3 M. The nanocomposite membranes with thicknesses of 19 μm and 47 μm reached power densities of 211 mW cm-2 and 184 mW cm-2 at 95 °C and 2 M methanol concentration. These results are comparable to those found for Nafion® membranes with similar thickness at the same conditions, which were 210 mW cm-2 and 204 mW cm-2 respectively. Due to the lower amount of Nafion® polymer present within the composite membranes, it is suggested a high degree of utilization of Nafion® as proton conductive material within the Nafion/PVA membranes, and therefore, significant savings in the consumed amount of Nafion® are potentially able to be achieved. In addition, the reinforcement effect caused by the PVA nanofibers offers the possibility of preparing membranes with very low thickness and good mechanical properties, while on the other hand, pristine Nafion® membranes are unpractical below a thickness of 50 μm.

  10. Vertically aligned carbon nanotubes/carbon fiber paper composite to support Pt nanoparticles for direct methanol fuel cell application

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Yi, Xi-bin; Liu, Shuo; Fan, Hui-Li; Ju, Wei; Wang, Qi-Chun; Ma, Jie

    2017-03-01

    Vertically aligned carbon nanotubes (VACNTs) grown on carbon fiber paper (CFP) by plasma enhanced chemical vapor deposition is introduced as a catalyst support material for direct methanol fuel cells (DMFCs). Well dispersed Pt nanoparticles on VACNTs surface are prepared by impregnation-reduction method. The VACNTs on CFP possess well-maintained alignment, large surface area and good electrical conductivity, which leading to the formation of Pt particles with a smaller size and enhance the Pt utilization rate. The structure and nature of resulting Pt/VACNTs/CFP catalysts for methanol oxidation are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscope (SEM). With the aid of VACNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway, which leads to enhance the catalytic activity and Pt utilization rate. Compared with the Pt/XC-72/CFP electrode, the electrochemical measurements results display that the Pt/VACNTs/CFP catalyst shows much higher electrocatalytic activity and better stability for methanol oxidation. In addition, the oxidation current from 200 to 1200 s decayed more slowly for the Pt/VACNTs/CFP than that of the Pt/XC-72/CFP catalysts, indicating less accumulation of adsorbed CO species. All those results imply that the Pt/VACNTs/CFP has a great potential for applications in DMFCs.

  11. Position dependent analysis of membrane electrode assembly degradation of a direct methanol fuel cell via electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter; Zamel, Nada; Gerteisen, Dietmar

    2013-11-01

    The performance of a direct methanol fuel cell MEA degraded during an operational period of more than 3000 h in a stack is locally examined using electrochemical impedance spectroscopy. Therefore, after disassembling the MEA is cut into small pieces and analyzed in a 1 cm2 test cell. Using a reference electrode, we were capable of measuring the anode and cathode spectra separately. The spectra of the segments at different positions do not follow a specified trend from methanol inlet to outlet of the stack flow field. The anode spectra were analyzed with an equivalent circuit simulation. The conductance of the charge transfer was found to increase with current density up to a point where a raising limitation process of the complex methanol oxidation dominates, which is not a bottleneck at low current density. Further, an increase of the double layer capacitance with current density was observed. The diffusion resistance was calculated as an effective diffusion coefficient in the order of 10-10 m2 s-1; implying that the diffusion limitation is not the bulk diffusion in the backing layer. Finally, the degree of poisoning of the catalysts by carbon monoxide was measured as a pseudo inductive arc and decreases with increasing current.

  12. High-Performance Alkaline Direct Methanol Fuel Cell using a Nitrogen-Postdoped Anode

    DTIC Science & Technology

    2014-01-01

    methanol strip- ping voltammetry {MSV) technique.rm Notably, CO stripping curves could not be obtained for either the N-doped PtRu/C or the undoped... voltammetry ChemSusChem 2014, 7, 1 -4 2 These are not the final page numbers! 7171 (;~ lElHSUSI.:III ~·:M Table 1. Comparison of our ADMFC...rate of 5 mV s-1 at 25 oc. The ECSA of the cathode was measured by cyclic voltammetry (CV). The cathode of the MEA was fed with 2M NaOH for 30 min at

  13. Electrochemical Reduction of Carbon Dioxide to Methanol by Direct Injection of Electrons into Immobilized Enzymes on a Modified Electrode.

    PubMed

    Schlager, Stefanie; Dumitru, Liviu Mihai; Haberbauer, Marianne; Fuchsbauer, Anita; Neugebauer, Helmut; Hiemetsberger, Daniela; Wagner, Annika; Portenkirchner, Engelbert; Sariciftci, Niyazi Serdar

    2016-03-21

    We present results for direct bio-electrocatalytic reduction of CO2 to C1 products using electrodes with immobilized enzymes. Enzymatic reduction reactions are well known from biological systems where CO2 is selectively reduced to formate, formaldehyde, or methanol at room temperature and ambient pressure. In the past, the use of such enzymatic reductions for CO2 was limited due to the necessity of a sacrificial co-enzyme, such as nicotinamide adenine dinucleotide (NADH), to supply electrons and the hydrogen equivalent. The method reported here in this paper operates without the co-enzyme NADH by directly injecting electrons from electrodes into immobilized enzymes. We demonstrate the immobilization of formate, formaldehyde, and alcohol dehydrogenases on one-and-the-same electrode for direct CO2 reduction. Carbon felt is used as working electrode material. An alginate-silicate hybrid gel matrix is used for the immobilization of the enzymes on the electrode. Generation of methanol is observed for the six-electron reduction with Faradaic efficiencies of around 10%. This method of immobilization of enzymes on electrodes offers the opportunity for electrochemical application of enzymatic electrodes to many reactions in which a substitution of the expensive sacrificial co-enzyme NADH is desired.

  14. Electrochemical Reduction of Carbon Dioxide to Methanol by Direct Injection of Electrons into Immobilized Enzymes on a Modified Electrode

    PubMed Central

    Dumitru, Liviu Mihai; Haberbauer, Marianne; Fuchsbauer, Anita; Neugebauer, Helmut; Hiemetsberger, Daniela; Wagner, Annika; Portenkirchner, Engelbert; Sariciftci, Niyazi Serdar

    2016-01-01

    Abstract We present results for direct bio‐electrocatalytic reduction of CO2 to C1 products using electrodes with immobilized enzymes. Enzymatic reduction reactions are well known from biological systems where CO2 is selectively reduced to formate, formaldehyde, or methanol at room temperature and ambient pressure. In the past, the use of such enzymatic reductions for CO2 was limited due to the necessity of a sacrificial co‐enzyme, such as nicotinamide adenine dinucleotide (NADH), to supply electrons and the hydrogen equivalent. The method reported here in this paper operates without the co‐enzyme NADH by directly injecting electrons from electrodes into immobilized enzymes. We demonstrate the immobilization of formate, formaldehyde, and alcohol dehydrogenases on one‐and‐the‐same electrode for direct CO2 reduction. Carbon felt is used as working electrode material. An alginate–silicate hybrid gel matrix is used for the immobilization of the enzymes on the electrode. Generation of methanol is observed for the six‐electron reduction with Faradaic efficiencies of around 10 %. This method of immobilization of enzymes on electrodes offers the opportunity for electrochemical application of enzymatic electrodes to many reactions in which a substitution of the expensive sacrificial co‐enzyme NADH is desired. PMID:26890322

  15. Polypyrrole layered SPEES/TPA proton exchange membrane for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Neelakandan, S.; Kanagaraj, P.; Sabarathinam, R. M.; Nagendran, A.

    2015-12-01

    Hybrid membranes based on sulfonated poly(1,4-phenylene ether ether sulfone) (SPEES)/tungstophosphoric acid (TPA) were prepared. SPEES/TPA membrane surfaces were modified with polypyrrole (Ppy) by in situ polymerization method to reduce the TPA leaching. The morphology and electrochemical property of the surface coated membranes were studied by SEM, AFM, water uptake, ion exchange capacity, proton conductivity, methanol permeability and tensile strength. The water uptake and the swelling ratio of the surface coated membranes decreased with increasing the Ppy layer. The surface roughness of the hybrid membrane was decreased with an increase in Ppy layer on the membrane surface. The methanol permeability of SPEES/TPA-Ppy4 hybrid membrane was significantly suppressed and found to be 2.1 × 10-7 cm2 s-1, which is 1.9 times lower than pristine SPEES membrane. The SPEES/TPA-Ppy4 membrane exhibits highest relative selectivity (2.86 × 104 S cm-3 s) than the other membrane with low TPA leaching. The tensile strength of hybrid membranes was improved with the introduction of Ppy layer. Combining their lower swelling ratio, high thermal stability and selectivity, SPEES/TPA-Ppy4 membranes could be a promising material as PEM for DMFC applications.

  16. Development of molecular and solid catalysts for the direct low-temperature oxidation of methane to methanol.

    PubMed

    Palkovits, Regina; von Malotki, Christian; Baumgarten, Martin; Müllen, Klaus; Baltes, Christian; Antonietti, Markus; Kuhn, Pierre; Weber, Jens; Thomas, Arne; Schüth, Ferdi

    2010-02-22

    The direct low-temperature oxidation of methane to methanol is demonstrated on a highly active homogeneous molecular catalyst system and on heterogeneous molecular catalysts based on polymeric materials possessing ligand motifs within the material structure. The N-(2-methylpropyl)-4,5-diazacarbazolyl-dichloro-platinum(II) complex reaches significantly higher activity compared to the well-known Periana system and allows first conclusions on electronic and structural requirements for high catalytic activity in this reaction. Interestingly, comparable activities could be achieved utilizing a platinum modified poly(benzimidazole) material, which demonstrates for the first time a solid catalyst with superior activity compared to the Periana system. Although the material shows platinum leaching, improved activity and altered electronic properties, compared to the conventional Periana system, support the proposed conclusions on structure-activity relationships. In comparison, platinum modified triazine-based catalysts show lower catalytic activity, but rather stable platinum coordination even after several catalytic cycles. Based on these systems, further development of improved solid catalysts for the direct low-temperature oxidation of methane to methanol is feasible.

  17. Platinum supported on functionalized ordered mesoporous carbon as electrocatalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Calvillo, L.; Lázaro, M. J.; García-Bordejé, E.; Moliner, R.; Cabot, P. L.; Esparbé, I.; Pastor, E.; Quintana, J. J.

    Ordered mesoporous carbon (OMC) with a specific area of 570 m 2 g -1 was synthesised using mesoporous silica SBA-15 as template. OMC was used as platinum catalyst support using the method of reduction with NaBH 4. Before deposition of platinum, the texture and surface chemistry of the support were modified by oxidation treatments in liquid phase using nitric acid as oxidative agent. During the oxidation process, oxygen surface groups were created, whereas ordered porous structure was maintained, as temperature programmed desorption and transmission electronic microscopy showed, respectively. Platinum supported materials were well dispersed over the mesoporous support and its catalytic performance towards methanol oxidation improved when compared with commercial carbon (Vulcan XC-72).

  18. Direct Methanol Fuel Cell Power Supply For All-Day True Wireless Mobile Computing

    SciTech Connect

    Brian Wells

    2008-11-30

    PolyFuel has developed state-of-the-art portable fuel cell technology for the portable computing market. A novel approach to passive water recycling within the MEA has led to significant system simplification and size reduction. Miniature stack technology with very high area utilization and minimalist seals has been developed. A highly integrated balance of plant with very low parasitic losses has been constructed around the new stack design. Demonstration prototype systems integrated with laptop computers have been shown in recent months to leading OEM computer manufacturers. PolyFuel intends to provide this technology to its customers as a reference design as a means of accelerating the commercialization of portable fuel cell technology. The primary goal of the project was to match the energy density of a commercial lithium ion battery for laptop computers. PolyFuel made large strides against this goal and has now demonstrated 270 Wh/liter compared with lithium ion energy densities of 300 Wh/liter. Further, more incremental, improvements in energy density are envisioned with an additional 20-30% gains possible in each of the next two years given further research and development.

  19. The influence of methanol on the chemical state of PtRu anodes in a high-temperature direct methanol fuel cell studied in situ by synchrotron-based near-ambient pressure x-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Saveleva, Viktoriia A.; Daletou, Maria K.; Savinova, Elena R.

    2017-01-01

    Synchrotron radiation-based near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) has recently become a powerful tool for the investigation of interfacial phenomena in electrochemical power sources such as batteries and fuel cells. Here we present an in situ NAP-XPS study of the anode of a high-temperature direct methanol fuel cell with a phosphoric acid-doped hydrocarbon membrane, which reveals an enhanced flooding of the Pt3Ru anode with phosphoric acid in the presence of methanol. An analysis of the electrode surface composition depending on the cell voltage and on the presence of methanol reveals the strong influence of the latter on the extent of Pt oxidation and on the transformation of Ru into Ru (IV) hydroxide.

  20. Kinetic analysis of carbon monoxide and methanol oxidation on high performance carbon-supported Pt-Ru electrocatalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Velázquez-Palenzuela, Amado; Centellas, Francesc; Garrido, José Antonio; Arias, Conchita; Rodríguez, Rosa María; Brillas, Enric; Cabot, Pere-Lluís

    The kinetic parameters of carbon monoxide and methanol oxidation reactions on a high performance carbon-supported Pt-Ru electrocatalyst (HP 20% 1:1 Pt-Ru alloy on Vulcan XC-72 carbon black) have been studied using cyclic voltammetry and rotating disk electrode (RDE) techniques in 0.50 M H 2SO 4 and H 2SO 4 (0.06-0.92 M) + CH 3OH (0.10-1.00 M) solutions at 25.0-45.0 °C. CO oxidation showed an irreversible behaviour with an adsorption control giving an exchange current density of 2.3 × 10 -6 A cm -2 and a Tafel slope of 113 mV dec -1 (α = 0.52) at 25.0 °C. Methanol oxidation behaved as an irreversible mixed-controlled reaction, probably with generation of a soluble intermediate (such as HCHO or HCOOH), showing an exchange current density of 7.4 × 10 -6 A cm -2 and a Tafel slope of 199 mV dec -1 (α = 0.30) at 25.0 °C. Reaction orders of 0.5 for methanol and -0.5 for proton were found, which are compatible with the consideration of the reaction between Pt-CO and Ru-OH species as the rate-determining step, being the initial methanol adsorption adjustable to a Temkin isotherm. The activation energy calculated through Arrhenius plots was 58 kJ mol -1, practically independent of the applied potential. Methanol oxidation on carbon-supported Pt-Ru electrocatalyst was improved by multiple potential cycles, indicating the generation of hydrous ruthenium oxide, RuO xH y, which enhances the process.

  1. Controlled synthesis of Pt/CS/PW12-GNs composite as an anodic electrocatalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Zhongshui; Lei, Fengling; Ye, Lingting; Zhang, Xiaofeng; Lin, Shen

    2015-04-01

    Controlled assembly in aqueous solution was used to synthesize the well-organized Pt/CS/PW12-GNs composite. By the aid of linear cationic polysaccharide chitosan, 2-D distribution worm-like Pt nanoparticles with their length and width of 15-20 and 3-4 nm, respectively, were formed on the surface of CS/PW12-GNs using HCOOH as a reducing agent at room temperature. The introduction of CS leads to well dispersion of worm-like Pt nanoparticles, the electroactivity of H3PW12O40 (PW12) alleviates CO poisoning toward Pt particles, and graphene nanosheets (GNs) ensure excellent electrical conductivity of the composites. The combined action among different components results in significantly enhanced catalytic activity of Pt/CS/PW12-GNs toward methanol oxidation and better tolerance of CO. The as-synthesized Pt/CS/PW12-GNs exhibit the forward peak current density of 445 mA mg-1, which is much higher than that (220 mA mg-1) for Pt/C-JM (the commercially available Johnson Matthey Hispec4000 catalyst, simplified as Pt/C-JM) and some recently reported Pt/graphene-based nanomaterials. The construction of 2-D distribution worm-like Pt nanoparticles and facile wet chemical synthesis strategy provide a promising way to develop superior performance electrocatalysts for direct methanol fuel cells applications.

  2. Proton electrolyte membrane properties and direct methanol fuel cell performance. II. Fuel cell performance and membrane properties effects

    NASA Astrophysics Data System (ADS)

    Silva, V. S.; Schirmer, J.; Reissner, R.; Ruffmann, B.; Silva, H.; Mendes, A.; Madeira, L. M.; Nunes, S. P.

    In order to study the relationship between the properties of proton electrolyte membranes (PEMs), obtained through standard characterization methods, and the direct methanol fuel cell (DMFC) performance, inorganic-organic hybrid membranes, modified via in situ hydrolysis, were used in a membrane electrolyte assembly (MEA) for DMFC application. The membranes, the characterization of which was performed in the previous paper of this series, were based on sulfonated poly(ether ether ketone) (sPEEK) with a sulfonation degree (SD) of 87% and were loaded with different amounts of zirconium oxide (5.0, 7.5, 10.0, 12.5 wt.%). The standard characterization methods applied were impedance spectroscopy (proton conductivity), water uptake, and pervaporation (permeability to methanol). The MEAs were characterized investigating the DMFC current-voltage polarization curves, constant voltage current (CV, 35 mV), and open-circuit voltage (OCV). The fuel cell ohmic resistance (null phase angle impedance, NPAI) and CO 2 concentration in the cathode outlet were also measured. The characterization results show that the incorporation of the inorganic oxide in the polymer network decreases the DMFC current density for CV experiments, CO 2 concentration in the cathode outlet for both OCV and CV experiments and, finally, the maximum power density output. The opposite effect was verified in terms of the NPAI (ohmic resistance) for both OCV and CV experiments. A good agreement was found between the studied DMFC performance parameters and the characterization results evaluated by impedance spectroscopy, water uptake and pervaporation experiments.

  3. Investigation of Ruthenium Dissolution in Advanced Membrane Electrode Assemblies for Direct Methanol Based Fuel Cell Stacks

    NASA Technical Reports Server (NTRS)

    Valdez, Thomas I.; Firdosy, S.; Koel, B. E.; Narayanan, S. R.

    2005-01-01

    Dissolution of ruthenium was observed in the 80-cell stack. Duration testing was performed in single cell MEAs to determine the pathway of cell degradation. EDAX analysis on each of the single cell MEAs has shown that the Johnson Matthey commercial catalyst is stable in DMFC operation for 250 hours, no ruthenium dissolution was observed. Changes in the hydrophobicity of the cathode backing papers was minimum. Electrode polarization analysis revealed that the MEA performance loss is attributed to changes in the cathode catalyst layer. Ruthenium migration does not seem to occur during cell operation but can occur when methanol is absent from the anode compartment, the cathode compartment has access to air, and the cells in the stack are electrically connected to a load (Shunt Currents). The open-to-air cathode stack design allowed for: a) The MEAs to have continual access to oxygen; and b) The stack to sustain shunt currents. Ruthenium dissolution in a DMFC stack can be prevented by: a) Developing an internally manifolded stacks that seal reactant compartments when not in operation; b) Bringing the cell voltages to zero quickly when not in operation; and c) Limiting the total number of cells to 25 in an effort to limit shunt currents.

  4. Poly (vinylidene fluoride-co-hexafluoropropylene)/polybenzimidazole blend nanofiber supported Nafion membranes for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Shih-Hua; Lin, Hsiu-Li

    2014-07-01

    This article presents preparation of poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-co-HFP) and polybenzimidazole (PBI) blend electrospun nanofiber (PVFP-BI) films from N,N‧-dimethyl acetamide (DMAc)/acetone mixture solutions. Using the PVFP-BI nanofiber film (thickness ∼13-15 μm) as a supporting material for impregnating Nafion resin solution, Nafion/PVFP-BI composite membranes (thickness ∼50 μm) are prepared and direct methanol fuel cell (DMFC) tests are performed. Better DMFC performance of the Nafion/PVFP-BI composite membrane than the commercial Nafion-117 (thickness ∼175 μm) and Nafion-212 (thickness ∼50 μm) membranes when blending with 5-10 wt.% of PBI in the PVFP-BI nanofiber support film is demonstrated.

  5. Investigation of methanol oxidation on a highly active and stable Pt–Sn electrocatalyst supported on carbon–polyaniline composite for application in a passive direct methanol fuel cell

    SciTech Connect

    Amani, Mitra; Kazemeini, Mohammad; Hamedanian, Mahboobeh; Pahlavanzadeh, Hassan; Gharibi, Hussein

    2015-08-15

    Highlights: • PtSn/C-PANI performed superior in the MOR compared with a commercial PtRu/C. • Catalytic activity of PtRu/C was highly reduced during the accelerated durability test. • Anode of the PtSn/C-PANI in a passive DMFC lowered methanol crossover by 30%. - Abstract: Polyaniline fiber (PANI) was synthesized and utilized to fabricate a vulcan–polyaniline (C-PANI) composite. Pt/C-PANI and PtSn/C-PANI electro-catalysts with different Pt:Sn atomic ratios were prepared by the impregnation method. These electro-catalysts, along with commercial PtRu/C (Electrochem), were characterized with respect to their structural and electrochemical properties in methanol oxidation reaction (MOR). PtSn(70:30)/C-PANI showed excellent performance in MOR, the obtained maximum current density being about 40% and 50% higher than that for PtRu/C and Pt/C-PANI, respectively. It was also found that the CO tolerance and stability of PtSn(70:30)/C-PANI was considerably higher than that of PtRu/C. Finally, the performance of these two materials was compared in a passive direct methanol fuel cell (DMFC). The DMFC test results demonstrated that the membrane electrode assembly (MEA) prepared using PtSn(70:30)/C-PANI anode catalyst performed more satisfactorily in terms of maximum power density and lower methanol crossover.

  6. Undoped and boron doped diamond nanoparticles as platinum and platinum-ruthenium catalyst support for direct methanol fuel cell application

    NASA Astrophysics Data System (ADS)

    La Torre Riveros, Lyda

    electron microscopy (SEM), energy dispersive analysis (EDX), infrared spectroscopy (IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), prompt gamma neutron activation analysis (PGNAA), and X-ray photoelectron spectroscopy (XPS). In order to demonstrate the utility of the catalyst obtained, the samples were tested in an electrochemical cell using methanol as a probe solution. As was performed with the undoped DNPs and BDDNPs, the ink paste method was used to prepare the electrodes with Pt/DNP, Pt-Ru/DNP, Pt/BDDNP and Pt-Ru/BDDNP catalytic systems, to perform the electrochemical experiments. The Pt and Pt-Ru modified diamond electrodes were tested with cyclic voltammetry in 0.5 M H2SO4 as electrolyte support showing hydrogen adsorption/desorption at platinum surfaces. CO gas adsorption/desorption experiments were also performed to determine the active surface area of Pt when Ru is present. Methanol oxidation current peaks were obtained when the electrodes were tested in a 1.0 M methanol/0.5 M H2SO4 solution. The experimental results demonstrated that diamond nanoparticles are useful as an electrode material. A fuel cell is a device which transforms the chemical energy of a fuel directly into electrical energy. As previously mentioned, the aim of this research is to demonstrate the utility of undoped DNPs and BDDNPs as catalytic supports, which was performed by testing the catalytic systems obtained in a single fuel cell station at different temperatures to observe the cell performance.

  7. Miniature Earthmover

    NASA Technical Reports Server (NTRS)

    1996-01-01

    International Machinery Corporation (IMC) developed a miniature earthmover, the 1/8 scale Caterpillar D11N Track-type Tractor, with trademark product approval and manufacturing/marketing license from Caterpillar, Inc. Through Marshall Space Flight Center assistance, the company has acquired infrared remote control technology, originally developed for space exploration. The technology is necessary for exports because of varying restrictions on radio frequency in foreign countries. The Cat D11N weighs only 340 pounds and has the world's first miniature industrial internal combustion engine. The earthmover's uses include mining, construction and demolition work, and hazardous environment work. IMC also has designs of various products for military use and other Caterpillar replicas.

  8. The Methanol Economy Project

    SciTech Connect

    Olah, George; Prakash, G. K.

    2014-02-01

    The Methanol Economy Project is based on the concept of replacing fossil fuels with methanol generated either from renewable resources or abundant natural (shale) gas. The full methanol cycle was investigated in this project, from production of methanol through bromination of methane, bireforming of methane to syngas, CO2 capture using supported amines, co-electrolysis of CO2 and water to formate and syngas, decomposition of formate to CO2 and H2, and use of formic acid in a direct formic acid fuel cell. Each of these projects achieved milestones and provided new insights into their respective fields.

  9. A review on durability issues and restoration techniques in long-term operations of direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Mehmood, Asad; Scibioh, M. Aulice; Prabhuram, Joghee; An, Myung-Gi; Ha, Heung Yong

    2015-11-01

    Direct methanol fuel cells (DMFCs) remain attractive among advanced energy conversion technologies due to their high energy density and simple system configuration. Although they made an early market entry but failed to attain a large-scale commercialization mainly because of their inferior performance sustainment in lifetime operations and high production costs. There have been lots of R&D efforts made to upgrade the long-term durability of DMFCs to a commercially acceptable standard. These rigorous efforts have been useful in gaining insights about various degradation mechanisms and their origins. This review first briefly describes the recent progress in lifetime enhancement of DMFC technology reported by various groups in academia and industry. Then, it is followed by comprehensive discussions on the major performance degradation routes and associated physico-chemical origins, and influence of operational parameters, together with the methods which have been employed to alleviate and restore the performance losses. Finally, a brief summary of the presented literature survey is provided in conjunction with some possible future research directions.

  10. Short term changes in methanol emission and pectin methylesterase activity are not directly affected by light in Lycopersicon esculentum

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Li, L.; Timko, M. P.; Mak, J. E.; Lerdau, M. T.

    2011-01-01

    Plants are an important source of atmospheric methanol (MeOH), the second most abundant organic gas after methane. Factors regulating phytogenic MeOH production are not well constrained in current MeOH emission models. Previous studies have indicated that light may have a direct influence on MeOH production. As light is known to regulate cell wall expansion, it was predicted that light would stimulate MeOH production through the pectin methylesterase (PME) pathway. MeOH emissions normalized for stomatal conductance (gs) did not, however, increase with light over short time scales (20-30 min). After experimentally controlling for gs and temperature, no light activation of PME activity or MeOH emission was observed. The results clearly demonstrate that light does not directly influence short-term changes in MeOH production and emission. Our data suggest that substrate limitation may be important in regulating MeOH production over short time scales. Future investigation of the long-term impacts of light on MeOH production may increase understanding of MeOH emission dynamics at the seasonal time scale.

  11. Short term changes in methanol emission and pectin methylesterase activity are not directly affected by light in Lycopersicon esculentum

    NASA Astrophysics Data System (ADS)

    Oikawa, P. Y.; Li, L.; Timko, M. P.; Mak, J. E.; Lerdau, M. T.

    2011-04-01

    Plants are an important source of atmospheric methanol (MeOH), the second most abundant organic gas after methane. Factors regulating phytogenic MeOH production are not well constrained in current MeOH emission models. Previous studies have indicated that light may have a direct influence on MeOH production. As light is known to regulate cell wall expansion, it was predicted that light would stimulate MeOH production through the pectin methylesterase (PME) pathway. MeOH emissions normalized for stomatal conductance (gs) did not, however, increase with light over short time scales (20-30 min). After experimentally controlling for gs and temperature, no light activation of PME activity or MeOH emission was observed. The results clearly demonstrate that light does not directly influence short-term changes in MeOH production and emission. Our data suggest that substrate limitation may be important in regulating MeOH production over short time scales. Future investigation of the long-term impacts of light on MeOH production may increase understanding of MeOH emission dynamics at the seasonal time scale.

  12. Study on the electronic properties and molecule adsorption of W18O49 nanowires as a catalyst support in the cathodes of direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Karim, N. A.; Kamarudin, S. K.; Shyuan, L. K.; Yaakob, Z.; Daud, W. R. W.; Kadhum, A. A. H.

    2015-08-01

    Catalyst supports have been used to increase the catalytic activity of reactions in the cathode of Direct Methanol Fuel Cells (DMFCs). The properties of tungsten oxide (W18O49) nanowires were studied, and their adsorption capability was evaluated using density functional theory. The electronic properties of the bulk material and two different diameter nanowires were calculated. Moreover, the molecules involved in adsorption were carbon monoxide, methanol, oxygen and hydrogen peroxide. The results showed that the high adsorption energy produced is primarily the result of the adsorption of methanol, followed by that of hydrogen peroxide, carbon monoxide and oxygen. The negative adsorption energies obtained showed that the adsorption reactions were exothermic, and only oxygen was stable. Therefore, a new surface model was described where cobalt atoms were adsorbed on tungsten atoms on the surface of a 12 Å nanowire. In this new nanowire doped with cobalt atoms, the adsorption energy was reduced.

  13. Molecular modeling of the morphology and transport properties of two direct methanol fuel cell membranes: phenylated sulfonated poly(ether ether ketone ketone) versus Nafion

    SciTech Connect

    Devanathan, Ramaswami; Idupulapati, Nagesh B.; Dupuis, Michel

    2012-08-14

    We have used molecular dynamics simulations to examine membrane morphology and the transport of water, methanol and hydronium in phenylated sulfonated poly ether ether ketone ketone (Ph-SPEEKK) and Nafion membranes at 360 K for a range of hydration levels. At comparable hydration levels, the pore diameter is smaller, the sulfonate groups are more closely packed, the hydronium ions are more strongly bound to sulfonate groups, and the diffusion of water and hydronium is slower in Ph-SPEEKK relative to the corresponding properties in Nafion. The aromatic carbon backbone of Ph-SPEEKK is less hydrophobic than the fluorocarbon backbone of Nafion. Water network percolation occurs at a hydration level ({lambda}) of {approx}8 H{sub 2}O/SO{sub 3}{sup -}. At {lambda} = 20, water, methanol and hydronium diffusion coefficients were 1.4 x 10{sup -5}, 0.6 x 10{sup -5} and 0.2 x 10{sup -5} cm{sup 2}/s, respectively. The pore network in Ph-SPEEKK evolves dynamically and develops wide pores for {lambda} > 20, which leads to a jump in methanol crossover and ion transport. This study demonstrates the potential of aromatic membranes as low-cost challengers to Nafion for direct methanol fuel cell applications and the need to develop innovative strategies to combat methanol crossover at high hydration levels.

  14. Efficient anodic and direct phenol-arene C,C cross-coupling: the benign role of water or methanol.

    PubMed

    Kirste, Axel; Elsler, Bernd; Schnakenburg, Gregor; Waldvogel, Siegfried R

    2012-02-22

    C,C cross-coupling reactions for the synthesis of nonsymmetrical biaryls represent one of the most significant transformations in contemporary organic chemistry. A variety of useful synthetic methods have been developed in recent decades, since nonsymmetrical biaryls play an evident role in natural product synthesis, as ligand systems in homogeneous catalysis and materials science. Transformation of simple arenes by direct C,H activation belongs to the cutting-edge strategies for creating biaryls; in particular the 2-fold C,H activation is of significant interest. However, in most examples very costly noble metal catalysts, ligand systems, and significant amount of waste-producing oxidants are required. Electrochemical procedures are considered as inherently "green" methods, because only electrons are required and therefore, no reagent waste is produced. Here, we report a metal-free electrochemical method for cross-coupling between phenols and arenes using boron-doped diamond (BDD) anodes in fluorinated media. Our sustainable approach requires no leaving functionalities. Employing water or methanol as mediator represents the key improvement for achieving nonsymmetrical biaryls with superb selectivity and synthetic attractive yields.

  15. Human Pulp Response to Direct Pulp Capping and Miniature Pulpotomy with MTA after Application of Topical Dexamethasone: A Randomized Clinical Trial

    PubMed Central

    Mousavi, Seyed Amir; Ghoddusi, Jamileh; Mohtasham, Nooshin; Shahnaseri, Shirin; Paymanpour, Payam; Kinoshita, Jun-Ichiro

    2016-01-01

    Introduction: The aim of this randomized clinical trial was to compare the histologic pulp tissue response to one-step direct pulp capping (DPC) and miniature pulpotomy (MP) with mineral trioxide aggregate (MTA) after application of dexamethasone in healthy human premolars. Methods and Materials: Forty intact premolars from 10 orthodontic patients, were randomly chosen for DPC (n=20) or MP (n=20). In 10 teeth from each group, after exposure of the buccal pulp horn, topical dexamethasone was applied over the pulp. In all teeth the exposed/miniaturely resected pulp tissue was covered with MTA and cavities were restored with glass ionomer. Teeth vitality was evaluated during the next 7, 21, 42, and 60 days. Signs and/or symptoms of irreversible pulpitis or pulp necrosis were considered as failure. According to the orthodontic schedule, after 60 days the teeth were extracted and submitted for histological examination. The Kruskal-Wallis and Fisher’s exact tests were used for statistical analysis of the data (P=0.05). Results: Although dexamethasone specimens showed less inflammation, calcified bridge, pulpal blood vasculature, collagen fibers and granulation tissue formation were not significantly different between the groups (P>0.05). Conclusion: Topical dexamethasone did not hindered pulp healing but reduced the amount of underlying pulpal tissue inflammation after DPC and MP in healthy human premolars. PMID:27141213

  16. Measurement of the current distribution in a direct methanol fuel cell-Confirmation of parallel galvanic and electrolytic operation within one cell

    NASA Astrophysics Data System (ADS)

    Sauer, Dirk Uwe; Sanders, Tilman; Fricke, Birger; Baumhöfer, Thorsten; Wippermann, Klaus; Kulikovsky, Andrei A.; Schmitz, Heinz; Mergel, Jürgen

    Current production in fuel cells is typically unequally distributed along the cell surface due to inhomogeneous concentration of reactants and temperature. The inhomogeneities in fuel cells can result in reduced output power and accelerated ageing. To quantify the inhomogeneities a measurement system has been developed which allows measuring the local distribution of current and temperature in hydrogen and direct methanol fuel cells. With this system we are able to directly observe the coexistence of galvanic and electrolytic domains in a single channel direct methanol fuel cell (the electrolytic domain is the domain where electrolysis occurs in contrast to the galvanic domain where the fuel cell process takes place). The measurement device also allows for the measurement locally resolved impedance spectra.

  17. Platinum and palladium nano-structured catalysts for polymer electrolyte fuel cells and direct methanol fuel cells.

    PubMed

    Long, Nguyen Viet; Thi, Cao Minh; Yong, Yang; Nogami, Masayuki; Ohtaki, Michitaka

    2013-07-01

    In this review, we present the synthesis and characterization of Pt, Pd, Pt based bimetallic and multi-metallic nanoparticles with mixture, alloy and core-shell structure for nano-catalysis, energy conversion, and fuel cells. Here, Pt and Pd nanoparticles with modified nanostructures can be controllably synthesized via chemistry and physics for their uses as electro-catalysts. The cheap base metal catalysts can be studied in the relationship of crystal structure, size, morphology, shape, and composition for new catalysts with low cost. Thus, Pt based alloy and core-shell catalysts can be prepared with the thin Pt and Pt-Pd shell, which are proposed in low and high temperature proton exchange membrane fuel cells (PEMFCs), and direct methanol fuel cells (DMFCs). We also present the survey of the preparation of Pt and Pd based catalysts for the better catalytic activity, high durability, and stability. The structural transformations, quantum-size effects, and characterization of Pt and Pd based catalysts in the size ranges of 30 nm (1-30 nm) are presented in electro-catalysis. In the size range of 10 nm (1-10 nm), the pure Pt catalyst shows very large surface area for electro-catalysis. To achieve homogeneous size distribution, the shaped synthesis of the polyhedral Pt nanoparticles is presented. The new concept of shaping specific shapes and morphologies in the entire nano-scale from nano to micro, such as polyhedral, cube, octahedra, tetrahedra, bar, rod, and others of the nanoparticles is proposed, especially for noble and cheap metals. The uniform Pt based nanosystems of surface structure, internal structure, shape, and morphology in the nanosized ranges are very crucial to next fuel cells. Finally, the modifications of Pt and Pd based catalysts of alloy, core-shell, and mixture structures lead to find high catalytic activity, durability, and stability for nano-catalysis, energy conversion, fuel cells, especially the next large-scale commercialization of next

  18. Effects of piston surface treatments on performance and emissions of a methanol-fueled, direct injection, stratified charge engine

    NASA Astrophysics Data System (ADS)

    West, B.; Green, J. B.

    1994-07-01

    The purpose of this study was to investigate the effects of thermal barrier coatings and/or surface treatments on the performance and emissions of a methanol-fueled, direct-injection, stratified-charge (DISC) engine. A Ricardo Hydra Mark III engine was used for this work and in previous experiments at Oak Ridge National Laboratory (ORNL). The primary focus of the study was to examine the effects of various piston insert surface treatments on hydrocarbon (HC) and oxides of nitrogen (NO(x)) emissions. Previous studies have shown that engines of this class have a tendency to perform poorly at low loads and have high unburned fuel emissions. A blank aluminum piston was modified to employ removable piston bowl inserts. Four different inserts were tested in the experiment: aluminum, stainless steel with a 1.27-mm (0.050-in.) air gap (to act as a thermal barrier), and two stainless steel/air-gap inserts with coatings. Two stainless steel inserts were dimensionally modified to account for the coating thickness (1.27-mm) and coated identically with partially stabilized zirconia (PSZ). One of the coated inserts then had an additional seal-coat applied. The coated inserts were otherwise identical to the stainless steel/air-gap insert (i.e., they employed the same 1.27-mm air gap). Thermal barrier coatings were employed in an attempt to increase combustion chamber surface temperatures, thereby reducing wall quenching and promoting more complete combustion of the fuel in the quench zone. The seal-coat was applied to the zirconia to reduce the surface porosity; previous research suggested that despite the possibly higher surface temperatures obtainable with a ceramic coating, the high surface area of a plasma-sprayed coating may actually allow fuel to adhere to the surface and increase the unburned fuel emissions and fuel consumption.

  19. Miniaturizing RFID for magnamosis.

    PubMed

    Jiang, Hao; Chen, Shijie; Kish, Shad; Loh, Lokkee; Zhang, Junmin; Zhang, Xiaorong; Kwiat, Dillon; Harrison, Michael; Roy, Shuvo

    2014-01-01

    Anastomosis is a common surgical procedure using staples or sutures in an open or laparoscopic surgery. A more effective and much less invasive alternative is to apply the mechanical pressure on the tissue over a few days [1]. Since the pressure is produced by the attractive force between two permanent magnets, the procedure is called magnamosis[1]. To ensure the two magnets are perfectly aligned during the surgery, a miniaturized batteryless Radio Frequency IDentification (RFID) tag is developed to wirelessly telemeter the status of a pressure sensitive mechanical switch. Using the multi-layer circular spiral coil design, the diameter of the RFID tag is shrunk to 10, 15, 19 and 27 mm to support the magnamosis for children as well as adults. With the impedance matching network, the operating distance of these four RFID tags are longer than 10 cm in a 20 × 22 cm(2) area, even when the tag's normal direction is 45° off the antenna's normal direction. Measurement results also indicate that there is no noticeable degradation on the operating distance when the tag is immersed in saline or placed next to the rare-earth magnet. The miniaturized RFID tag presented in this paper is able to support the magnamosis and other medical applications that require the miniaturized RFID tag.

  20. Comparison of Pt-based binary and ternary alloy anode catalysts for polymer electrolyte direct methanol fuel cells

    SciTech Connect

    Liu, R.; Ley, K.L.; Pu, C.

    1996-12-31

    As an anode catalyst, Pt is highly active for the adsorption and dehydrogenation of methanol, however, the surface is poisoned by CO. To oxidize CO to CO{sub 2}, a second oxygen atom is required from an adjacent adsorbed water molecule. Bifunctional alloys composed of Pt and a second metal M, able to activate H{sub 2}O (forming -OH{sub ads}) at low potentials, are candidate materials for methanol electro-oxidation catalysts A proposed mechanism is: Figure 2 shows that metals which enhance methanol oxidation activity when alloyed with Pt have similar M-O bond strengths (see bold print), suggesting that the best binary alloy catalysts have second metals that are optimized with respect to the ability to oxidatively adsorb water. and the ability to dissociate M-O bonds to yield CO{sub 2}.

  1. Office Chromatography: Precise printing of sample solutions on miniaturized thin-layer phases and utilization for scanning Direct Analysis in Real Time mass spectrometry.

    PubMed

    Häbe, Tim T; Morlock, Gertrud E

    2015-09-25

    Office Chromatography combines achievements in office technologies with miniaturized planar chromatography. In the life sciences, printing of materials became an accepted technique, whereas in separation science, the use of printers for chromatography is at its infancy. A bubble-jet printer was modified for exact application on miniaturized plates. Technical modifications included the removal of all unnecessary parts and the improvement of the positioning system, purge unit and sample supply system. Evaluation was performed via a slide scanner and image evaluation software. Printing of a food dye mixture solution (n=5) led to a calculated mean deposition volume of 13±1nL/mm(2) per print-cycle. A mean determination coefficient (R(2); n=5) of 0.9990 was obtained for application of increasing volumes, executed via increasing band widths of 50-200μm (corresponding to 2-8nL). Using larger band widths and multiple print jobs, deposition volumes of up to the microliter scale represented an alternative to cost-intensive standard equipment. After print, separation, detection and digital evaluation of five food dyes, mean R(2) (n=5) were obtained between 0.9977 and 0.9995. The accuracy of printing was proven by mean recovery rates of 101-105% with repeatabilities of 3-7% (%RSD, n=5). The transfer to nanostructured ultrathin-layer plates proved the synergetic potential of these fields of research. First, this modified printer was suited for printing of finely graduated scales of three preservatives for determination of the spatial resolution of scanning Direct Analysis in Real Time mass spectrometry.

  2. Novel method for the synthesis of hydrophobic Pt-Ru nanoparticles and its application to preparing a Nafion-free anode for the direct methanol fuel cell.

    PubMed

    Tu, Hung-Chi; Wang, Wen-Lin; Wan, Chi-Chao; Wang, Yung-Yun

    2006-08-17

    Pt-Ru alloy is a bimetallic catalyst most commonly used in the direct methanol fuel cell (DMFC). In this paper, a new process to synthesize an unsupported Pt-Ru colloid has been introduced. The characteristics of synthesized nanoparticles were identified by XRD, TEM/EDX, and SEM, and it shows that Ru atoms are incorporated into the Pt fcc structure and the well-dispersed particles (diameter approximately 4 nm) possess a Pt-rich feature. This catalyst shows a hydrophobic characteristic which can adsorb very well on the hydrophobic-treated carbon paper or carbon cloth without the need of Nafion. Accordingly, this method can avoid particle agglomeration, and the synthesized catalyst demonstrates strong adsorption with carbon paper. In addition, this colloid-type Nafion-free catalyst was measured via linear sweep voltammetry (LSV) and exhibited electrochemical activity for methanol oxidation comparable to the commercial one with Nafion binding.

  3. Operating characteristics of direct methanol fuel cell using a platinum-ruthenium catalyst supported on porous carbon prepared from mesophase pitch

    NASA Astrophysics Data System (ADS)

    Nam, Kidon; Jung, Doohwan; Kim, Sang-Kyung; Peck, Donghyun; Ryu, Seungkon

    The characteristics of a platinum-ruthenium catalyst supported on porous carbon (PC) are analysed by X-ray diffraction, scanning electron microscopy, cyclic voltammetry and chemisorption techniques. Single-cell tests are carried out in order to compare the performance of these catalysts as an anode in a direct methanol fuel cell with respect to that of a commercial-grade catalyst. The methanol oxidation rate on a Pt-Ru catalyst supported on PC with a pore size of 20 nm is about 35% higher than that on a commercial E-TEK catalyst. The catalyst (Pt-Ru/K20) in the single-cell test gives a power density of 90 and 126 mW cm -2 under air and oxygen at 60 °C, respectively. These values are 15-16% higher than those obtained with a commercial E-TEK catalyst.

  4. Pt loaded two-dimensional TaC-nanosheet/graphene hybrid as an efficient and durable electrocatalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    He, Chunyong; Tao, Juzhou

    2016-08-01

    Poor electrocatalytic activity, insufficient operation durability and low carbon monoxide (CO) tolerance of the Pt-based catalysts are key challenges facing the direct methanol fuel cells (DMFCs) as promising electrochemical energy conversion device. We here present a new effort to catalyst designed by depositing Pt nanoparticles on two-dimensional (2D) TaC-nanosheet/graphene hybird (Pt/TaC-G) to obtain notable improvement in electrocatalytic performance over the commercial Pt/C. Experiment results from both X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) support that a strong synergetic chemical coupling interaction between the Pt nanoparticles and the 2D TaC-G significantly enhanced electrocatalytic activity for methanol oxidation reaction (MOR). This process can improve the CO tolerance as well as durability of MOR catalysts simultaneously, making it a promising general approach to design and optimize the next generation electrocatalysts in DMFCs.

  5. An in-situ nano-scale swelling-filling strategy to improve overall performance of Nafion membrane for direct methanol fuel cell application

    NASA Astrophysics Data System (ADS)

    Li, Jing; Fan, Kun; Cai, Weiwei; Ma, Liying; Xu, Guoxiao; Xu, Sen; Ma, Liang; Cheng, Hansong

    2016-11-01

    A novel in-situ nano-scale swelling-filling (SF) strategy is proposed to modify commercial Nafion membranes for performance enhancement of direct methanol fuel cells (DMFCs). A Nafion membrane was filled in-situ with proton conductive macromolecules (PCMs) in the swelling process of a Nafion membrane in a PCM solution. As a result, both proton conductivity and methanol-permeation resistivity of the SF-treated Naifion membrane was substantially improved with the selectivity nearly doubled compared to the original Nafion membrane. The mechanical strength of the optimal SF treated Nafion membrane was also enforced due to the strong interaction between the PCM fillers and the Nafion molecular chains. As a result, a DMFC equipped with the SF-treated membrane yielded a 33% higher maximum power density than that offered by the DMFC with the original Nafion membrane.

  6. Direct quantitative gas chromatographic separation of C2-C6 fatty acids, methanol, and ethyl alcohol in aqueous microbial fermentation media.

    PubMed

    Rogosa, M; Love, L L

    1968-02-01

    A method is described for the direct quantitative gas chromatographic separation of C(2)-C(6) lower fatty acid homologues, methanol, and ethyl alcohol in aqueous microbial fermentation media. A hydrogen flame detector and a single-phase solid column packing, comprising beads of a polyaromatic resin (polystyrene cross-linked with divinyl benzene), were employed. Direct injections of 1 to 10 muliters of aqueous culture supernatant fluids were made. Quantitative recoveries of C(2)-C(6) acids added to culture supernatant fluids were obtained.

  7. Direct Quantitative Gas Chromatographic Separation of C2-C6 Fatty Acids, Methanol, and Ethyl Alcohol in Aqueous Microbial Fermentation Media

    PubMed Central

    Rogosa, M.; Love, L. L.

    1968-01-01

    A method is described for the direct quantitative gas chromatographic separation of C2-C6 lower fatty acid homologues, methanol, and ethyl alcohol in aqueous microbial fermentation media. A hydrogen flame detector and a single-phase solid column packing, comprising beads of a polyaromatic resin (polystyrene cross-linked with divinyl benzene), were employed. Direct injections of 1 to 10 μliters of aqueous culture supernatant fluids were made. Quantitative recoveries of C2-C6 acids added to culture supernatant fluids were obtained. PMID:5645415

  8. Direct growth of NiCo2O4 nanostructures on conductive substrates with enhanced electrocatalytic activity and stability for methanol oxidation

    NASA Astrophysics Data System (ADS)

    Qian, Lei; Gu, Li; Yang, Li; Yuan, Hongyan; Xiao, Dan

    2013-07-01

    In this report, NiCo2O4 nanostructures with different morphologies were directly grown on conductive substrates (stainless steel and ITO) by a facile electrodeposition method in addition to a post-annealing process. The morphology changes on different conductive substrates are discussed in detail. The NiCo2O4 on stainless steel (SS) had a high surface area (119 m2 g-1) and was successfully used in the electrocatalytic oxidation of methanol. The electrocatalytic performance was investigated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS) measurements. Impressively, the NiCo2O4 showed much higher electrocatalytic activity, lower overpotential and greater stability compared to that of only NiO or Co3O4 synthesized by the same method. The higher electrocatalytic activity is due to the high electron conductivity, large surface area of NiCo2O4 and the fast ion/electron transport in the electrode and at the electrolyte-electrode interface. This is important for further development of high performance non-platinum electrocatalysts for application in direct methanol fuel cells.In this report, NiCo2O4 nanostructures with different morphologies were directly grown on conductive substrates (stainless steel and ITO) by a facile electrodeposition method in addition to a post-annealing process. The morphology changes on different conductive substrates are discussed in detail. The NiCo2O4 on stainless steel (SS) had a high surface area (119 m2 g-1) and was successfully used in the electrocatalytic oxidation of methanol. The electrocatalytic performance was investigated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS) measurements. Impressively, the NiCo2O4 showed much higher electrocatalytic activity, lower overpotential and greater stability compared to that of only NiO or Co3O4 synthesized by the same method. The higher electrocatalytic activity is due to the high electron conductivity

  9. TiO2/bi A-SPAES(Ds 1.0) composite membranes for proton exchange membrane in direct methanol fuel cell (DMFC).

    PubMed

    Zhang, Ni; Zhong, Chuanqing; Xie, Bing; Liu, Huiling; Wang, Xingzu

    2014-09-01

    A series of TiO2/bi A-SPAES(Ds 1.0) composite membranes with various contents of nano-sized TiO2 particles were prepared through sol-gel method. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These membranes were used for proton exchange membrane (PEM) for performance evaluation in direct methanol fuel cell (DMFC). These composite membranes showed good thermal stability and mechanical strength. It was found that the water uptake of these membranes enhanced with the TiO2 amount increasing in these composite membranes. Meanwhile, the introduction of TiO2 particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities of these composite membranes with 8% TiO2 particles (0.120 S/cm and 0.128 S/cm) were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) at 80 degrees C and 100 degrees C. Specially, the methanol diffusion coefficient (1.2 x 10(-7) cm2/s) of the composite membrane with 8% TiO2 content was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm2/s). As a result, the TiO2/bi A-SPAES composite membrane was considered as a promising material for PEM in DMFC.

  10. Application of Mössbauer spectroscopy in industrial heterogeneous catalysis: effect of oxidant on FePO4 material phase transformations in direct methanol synthesis from methane

    NASA Astrophysics Data System (ADS)

    Dasireddy, Venkata D. B. C.; Khan, Faiza B.; Hanzel, Darko; Bharuth-Ram, Krish; Likozar, Blaž

    2017-11-01

    The effect of the FePO4 material phase transformation in the direct selective oxidation of methane to methanol was studied using various oxidants, i.e. O2, H2O and N2O. The phases of the heterogeneous catalyst applied, before and after the reactions, were characterized by M¨ossbauer spectroscopy. The main reaction products were methanol, carbon monoxide and carbon dioxide, whereas formaldehyde was produced in rather minute amounts. The Mössbauer spectra showed the change of the initial catalyst material, FePO4 (tridymite-like phase (tdm)), to the reduced metal form, iron(II) pyrophosphate, Fe2P2O7, and thereafter, the material phase change was governed by the oxidation with individual oxidizing species.Mössbauer spectroscopy measurements applied along with X-ray diffraction (XRD) studies on fresh, reduced and spent catalytic materials demonstrated a transformation of the catalyst to a mixture of phases which depended on operating process conditions. Generally, activity was low and should be a subject of further material optimization and engineering, while the selectivity towards methanol at low temperatures applied was adequate. The proceeding redox mechanism should thus play a key role in catalytic material design, while the advantage of iron-based heterogeneous catalysts primarily lies in them being comparably inexpensive and comprising non-critical raw materials only.

  11. A miniature origami biofuel cell based on a consumed cathode.

    PubMed

    Yu, You; Han, Yujie; Lou, Baohua; Zhang, Lingling; Han, Lei; Dong, Shaojun

    2016-11-10

    Considerable interest has been focused on miniature biofuel cells (BFCs) because of their portability and possibility to be implantable. Origami devices with hollow channels will provide novel insight into the assembly methods of miniature BFCs. Herein a miniature origami BFC has been fabricated from a MnO2-graphite flake consumed solid-state cathode. For further practical applications, miniature origami BFCs can directly generate energy from soft drinks.

  12. Miniaturized autonomous robot

    NASA Astrophysics Data System (ADS)

    Ishihara, Hidenori; Fukuda, Toshio

    1998-01-01

    Many projects developing the miniaturized autonomous robot have been carried out in the whole world. This paper deals with our challenges developing a miniaturized autonomous robot. The miniaturized autonomous robot is defined as the miniaturized closed-loop system with micro processor, microactuators and microsensors. We have developed the micro autonomous robotic system (MARS) consisting of the microprocessor, microsensors, microactuators, communication units and batteries. The MARS controls itself by the downloaded program supplied through the IR communication system. In this paper, we demonstrate several performance of the MARS, and discuss the properties of the miniaturized autonomous robot.

  13. Direct growth of NiCo2O4 nanostructures on conductive substrates with enhanced electrocatalytic activity and stability for methanol oxidation.

    PubMed

    Qian, Lei; Gu, Li; Yang, Li; Yuan, Hongyan; Xiao, Dan

    2013-08-21

    In this report, NiCo2O4 nanostructures with different morphologies were directly grown on conductive substrates (stainless steel and ITO) by a facile electrodeposition method in addition to a post-annealing process. The morphology changes on different conductive substrates are discussed in detail. The NiCo2O4 on stainless steel (SS) had a high surface area (119 m(2) g(-1)) and was successfully used in the electrocatalytic oxidation of methanol. The electrocatalytic performance was investigated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS) measurements. Impressively, the NiCo2O4 showed much higher electrocatalytic activity, lower overpotential and greater stability compared to that of only NiO or Co3O4 synthesized by the same method. The higher electrocatalytic activity is due to the high electron conductivity, large surface area of NiCo2O4 and the fast ion/electron transport in the electrode and at the electrolyte-electrode interface. This is important for further development of high performance non-platinum electrocatalysts for application in direct methanol fuel cells.

  14. Novel method for investigation of two-phase flow in liquid feed direct methanol fuel cells using an aqueous H 2O 2 solution

    NASA Astrophysics Data System (ADS)

    Bewer, T.; Beckmann, T.; Dohle, H.; Mergel, J.; Stolten, D.

    One major issue in the development of direct methanol fuel cells (DMFC) is the management of the evolving CO 2 gas bubbles in the flow fields. These bubbles influence the flow distribution and therefore the power density of a cell. In this paper, a novel method for in situ production of bubbles in a test cell made of perspex is presented. The method is based on the decomposition of hydrogen peroxide solution (H 2O 2) to oxygen and water in aqueous media at the presence of a catalyst. By using an appropriate H 2O 2-concentration, the gas evolution rate can be set to same order of magnitude as in real direct methanol fuel cells. This approach allows the simulation of the flow distribution in DMFC by simple low-cost hardware. As no current conducting parts are needed, the whole dummy cell can be made of perspex to ensure a complete visibility of the flow. In a perspex flow cell with an active area of 600 cm 2, the flow homogeneity as a function of gas evolution rate, flow field and manifold design was investigated. Experiments show that splayed manifolds have a superior performance concerning flow uniformity compared to other designs. The use of grid structures as a flow field gives good bubble transport at all investigated current densities.

  15. NiO/CeO2-ZnO nano-catalysts for direct synthesis of dimethyl carbonate from methanol and carbon dioxide.

    PubMed

    Kang, Ki Hyuk; Lee, Chang Hoon; Kim, Dong Baek; Jang, Boknam; Song, In Kyu

    2014-11-01

    XNiO/CeO2(0.7)-ZnO(0.3) (X = 0, 1, 5, 10, and 15) nano-catalysts were prepared by a wet impregnation method with a variation of NiO content (X, wt%). The prepared catalysts were then applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Successful formation of XNiO/CeO2(0.7)-ZnO(0.3) nano-catalysts was confirmed by XRD and ICP-AES analyses. Acidity and basicity of XNiO/CeO2-ZnO were measured by NH3-TPD (temperature-programmed desorption) and CO2-TPD experiments, respectively, with an aim of elucidating the effect of acidity and basicity of the catalysts on the catalytic performance in the reaction. It was revealed that the catalytic activity of XNiO/CeO2(0.7)-ZnO(0.3) was closely related to both acidity and basicity of the catalysts. The amount of dimethyl carbonate produced over XNiO/CeO2(0.7)-ZnO(0.3) increased with increasing acidity and basicity of the catalysts. Thus, both acidity and basicity of the catalysts played important roles in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.

  16. Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over CeO2(X)-ZnO(1-X) nano-catalysts.

    PubMed

    Kang, Ki Hyuk; Joe, Wangrae; Lee, Chang Hoon; Kim, Mieock; Kim, Dong Baek; Jang, Boknam; Song, In Kyu

    2013-12-01

    CeO2(X)-ZnO(1-X) (X = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) nano-catalysts were prepared by a co-precipitation method with a variation of CeO2 content (X, mol%), and they were applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Successful formation of CeO2(X)-ZnO(1-X) nano-catalysts was well confirmed by XRD analysis. The amount of DMC produced over CeO2(X)-ZnO(1-X) catalysts exhibited a volcano-shaped curve with respect to CeO2 content. Acidity and basicity of CeO2(X)-ZnO(1-X) nano-catalysts were measured by NH3-TPD and CO2-TPD experiments, respectively, to elucidate the effect of acidity and basicity on the catalytic performance in the reaction. It was revealed that the catalytic performance of CeO2(X)-ZnO(1-X) nano-catalysts was closely related to the acidity and basicity of the catalysts. Amount of dimethyl carbonate increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, CeO2(0.7)-ZnO(0.3) with the largest acidity and basicity showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.

  17. Activity and stability studies of titanates and titanate-carbon nanotubes supported Ag anode catalysts for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Mohamed, Mohamed Mokhtar; Khairy, M.; Eid, Salah

    2016-02-01

    Titanate-SWCNT; synthesized via exploiting the interaction between TiO2 anatase with oxygen functionalized SWCNT, supported Ag nanoparticles and Ag/titanate are characterized using XRD, TEM-EDX-SAED, N2 adsorption, Photoluminescence, Raman and FTIR spectroscopy. These samples are tested for methanol electrooxidation via using cyclic voltammetry (CV) and impedance measurements. It is shown that Ag/titanate nanotubes exhibited superior electrocatalytic performance for methanol oxidation (4.2 mA cm-2) than titanate-SWCNT, Ag/titanate-SWCNT and titanate. This study reveals the existence of a strong metal-support interaction in Ag/titanate as explored via formation of Ti-O-Ag bond at 896 cm-1 and increasing surface area and pore volume (103 m2 g-1, 0.21 cm3 g-1) compared to Ag/titanate-SWCNT (71 m2 g-1, 0.175 cm3 g-1) that suffers perturbation and defects following incorporation of SWCNT and Ag. Embedding Ag preferably in SWCNT rather than titanate in Ag/titanate-SWCNT disturbs the electron transfer compared to Ag/titanate. Charge transfer resistance depicted from Nyquist impedance plots is found in the order of titanate > Ag/titanate-SWCNT > titanate-SWCNT > Ag/titanate. Accordingly, Ag/titanate indicates a slower current degradation over time compared to rest of catalysts. Conductivity measurements indicate that it follows the order Ag/titanate > Ag/titanate-SWCNT > titanate > titanate-SWCNT declaring that SWCNT affects seriously the conductivity of Ag(titanate) due to perturbations caused in titanate and sinking of electrons committed by Ago through SWCNT.

  18. Sn-doped TiO2 modified carbon to support Pt anode catalysts for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Yabei; Liu, Chuntao; Liu, Yanying; Feng, Bo; Li, Li; Pan, Hengyu; Kellogg, Williams; Higgins, Drew; Wu, Gang

    2015-07-01

    Catalyst supports are known to play important role in governing overall catalyst activity and durability. Here, a new type of SnO2-TiO2 solid solution (TixSn1-xO2) support was prepared via a solvothermal method with substitution of Ti4+ by Sn4+ in the TiO2 lattice. Furthermore, the TixSn1-xO2 was combined with conventional carbon black (Vulcan XC-72) to prepare a hybrid support (TixSn1-xO2-C) for depositing Pt nanoparticles. The ratios of Sn vs. Ti in the solid-solution and TixSn1-xO2vs. XC-72 were systematically optimized in terms of their performance as supports for methanol oxidation. Compared to Pt/TiO2-C and commercial Pt/C catalysts, the best performing Pt/Ti0.9Sn0.1O2-C catalyst exhibited the highest activity, evidenced by methanol oxidation and CO stripping experiments. The well-dispersed Pt nanoparticles (2-3 nm) are mostly deposited on the boundaries of Ti0.9Sn0.1O2 and carbon blacks. Formation of the special triple junction structure can play an important role in improving Pt utilization with increased electrochemical active surface areas (ESA) of Pt. In addition, the enhanced activity for Pt supported on Ti0.9Sn0.1O2-C is due to high content of OH group on Ti0.9Sn0.1O2 along with the strengthened metal-supports interactions. Both promote the oxidation of poisoning CO absorbed on Pt active sites.

  19. Fluorescence-based high throughput screening for noble metal-free and platinum-poor anode catalysts for the direct methanol fuel cell.

    PubMed

    Welsch, F G; Stöwe, K; Maier, W F

    2011-09-12

    We describe here the results of a high throughput screening study for direct methanol fuel cell (DMFC) anode catalysts consisting of new elemental combinations with an optical high-throughput screening method, which allows the quantitative evaluation of the electrochemical activity of catalysts. The method is based on the fluorescence of protonated quinine generated during electrooxidation of methanol. The high-throughput screening included noble-metal free binary and ternary mixed oxides of the elements Al, Co, Cr, Cu, Fe, Mn, Mo, Nb, Ni, Ta, Ti, Zn, and Zr in the oxidized form as well as after prior reduction in hydrogen. In addition 318 ternary and quaternary Pt-containing materials composed out of the mixed oxides of Bi, Ce, Co, Cr, Cu, Fe, Ga, Ge, In, La, Mn, Mo, Nb, Nd, Ni, Pr, Sb, Sn, Ta, Te, Ti, V, Zn, and Zr with a molar Pt-ratio of 10% and 30% were screened. Validation and long time experiments of the hits were performed by cyclovoltammetry (CV). The microstructural stability of the electrode preparations of the lead compositions was studied by X-ray diffraction (XRD) pattern analysis.

  20. Synthesis of PtRu nanoparticles from the hydrosilylation reaction and application as catalyst for direct methanol fuel cell.

    PubMed

    Huang, Junchao; Liu, Zhaolin; He, Chaobin; Gan, Leong Ming

    2005-09-08

    Nanosized Pt, PtRu, and Ru particles were prepared by a novel process, the hydrosilylation reaction. The hydrosilylation reaction is an effective method of preparation not only for Pt particles but also for other metal colloids, such as Ru. Vulcan XC-72 was selected as catalyst support for Pt, PtRu, and Ru colloids, and TEM investigations showed nanoscale particles and narrow size distribution for both supported and unsupported metals. All Pt and Pt-rich catalysts showed the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure, whereas the Ru and Ru-rich alloys were more typical of a hexagonal close-packed (hcp) structure. As evidenced by XPS, most Pt and Ru atoms in the nanoparticles were zerovalent, except a trace of oxidation-state metals. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results concluded that some alloy catalysts showed higher catalytic activities and better CO tolerance than the Pt-only catalyst; Pt56Ru44/C have displayed the best electrocatalytic performance among all carbon-supported catalysts.

  1. Lamellar crystals as proton conductors to enhance the performance of proton exchange membrane for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Zhao, Yuning; Jiang, Zhongyi; Xiao, Lulu; Xu, Tao; Wu, Hong

    2011-08-01

    Zirconium glyphosate (ZrG) is a solid proton conductor with layered crystal structure. The inorganic veneer sheets of ZrG are covalently intercalated by glyphosate molecules with carboxylic acid end groups (-COOH). The existence of abundant -COOH groups both inside and on the surface of ZrG provides additional proton-conducting channels facilitating the proton conduction through and around the inorganic crystals. ZrG is incorporated into the sulfonated polyether ether ketone (SPEEK) matrices to prepare proton-conducting hybrid membranes. The conductivity of the hybrid membranes is higher than the pristine SPEEK membrane, and increases with increasing ZrG content. Furthermore, the enhancement of the proton conductivity is more obvious at elevated temperatures. At 25 °C, the proton conductivity of the hybrid membrane with 16 wt% ZrG is 1.4 times higher than that of the pristine membrane. When the temperature increases to 55 °C, the conductivity of the hybrid membrane with 8 wt% ZrG is more than twice that of the pristine SPEEK membrane. The prolonged and tortuous pathways originated from the incorporation of inorganic crystals lead to reduced methanol permeability. The selectivity of the hybrid membrane is increased by as much as 72% compared to the pristine SPEEK membrane.

  2. Miniaturization of a Hydrogen Plant

    SciTech Connect

    Holladay, Jamie D.; Jones, Evan O.; Dagle, Robert A.; Xia, Gordon; Cao, Chunshe; Wang, Yong

    2005-09-01

    The development of a miniaturized hydrogen plant is discussed. The micro-scale system is capable of producing 1-5 sccm hydrogen that could be used as a fuel supply in a small fuel cell to produce <1 W power. The paper describes the developmental approach, significant unit operations, material selection, and reactor design. The final microscale fuel processing system is composed of a catalytic combustor, catalytic methanol reformer, selective methanation reactor, and the necessary vaporizers and heat exchangers. The fuel processing system is less than 0.3 cm3 and less than 1 gram mass. Thermal efficiencies as high as 33% for hydrogen production were achieved. When a methanation reactor was incorporated into the system, a carbon monoxide level of less than 100 ppm was reached, but at a reduced system efficiency. Further development work includes increasing efficiency through improved system integration.

  3. Miniature drag force anemometer

    NASA Technical Reports Server (NTRS)

    Krause, L. N.; Fralick, G. C.

    1977-01-01

    A miniature drag force anemometer is described which is capable of measuring dynamic velocity head and flow direction. The anemometer consists of a silicon cantilevered beam 2.5 mm long, 1.5 mm wide, and 0.25 mm thick with an integrated diffused strain gage bridge, located at the base of the beam, as the force measuring element. The dynamics of the beam are like that of a second order system with a natural frequency of about 42 kHz and a damping coefficient of 0.007. The anemometer can be used in both forward and reversed flow. Measured flow characteristics up to Mach 0.6 are presented along with application examples including turbulence measurements.

  4. Miniature propulsion systems

    NASA Astrophysics Data System (ADS)

    Campbell, John G.

    1992-07-01

    Miniature solenoid valves, check valves and a hydrazine gas generator typify the miniaturization used in the liquid propulsion system for the Army Light Weight Exo-Atmospheric Projectile (LEAP). The pressure control subsystem uses a solenoid valve weighing 24 grams to control flow of helium to pressurize the propellant tanks. The attitude control subsystem uses a gas generator weighing 71 grams to produce decomposed hydrazine as the gaseous propellant for miniature 1 lbf ACS thrusters weighing 5.4 grams. The successful use of these miniature components in development tests and a hover test of the LEAP is described.

  5. Enhanced oxygen reduction reaction activity of iron-containing nitrogen-doped carbon nanotubes for alkaline direct methanol fuel cell application

    NASA Astrophysics Data System (ADS)

    Ratso, Sander; Kruusenberg, Ivar; Sarapuu, Ave; Rauwel, Protima; Saar, Rando; Joost, Urmas; Aruväli, Jaan; Kanninen, Petri; Kallio, Tanja; Tammeveski, Kaido

    2016-11-01

    Non-precious metal catalysts for electrochemical oxygen reduction reaction are synthesised by pyrolysis of multi-walled carbon nanotubes in the presence of nitrogen and iron precursors. For the physico-chemical characterisation of the catalysts transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction are used. The electrocatalytic activity of the catalysts for oxygen reduction is studied in 0.1 M KOH solution using the rotating disk electrode method. The Fe-containing nitrogen-doped carbon nanotubes exhibit an enhanced electrocatalytic performance as compared to metal-free counterparts and their electrocatalytic activity is comparable to that of commercial Pt/C catalyst. Alkaline direct methanol fuel cell tests also show performance close to Pt/C. Thus, these materials can be considered as promising cathode catalysts for application in alkaline fuel cells.

  6. New approaches towards novel composite and multilayer membranes for intermediate temperature-polymer electrolyte fuel cells and direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Branco, Carolina Musse; Sharma, Surbhi; de Camargo Forte, Maria Madalena; Steinberger-Wilckens, Robert

    2016-06-01

    This review analyses the current and existing literature on novel composite and multilayer membranes for Polymer Electrolyte Fuel Cell applications, including intermediate temperature polymer electrolyte fuel cell (IT-PEFC) and direct methanol fuel cell (DMFC) systems. It provides a concise scrutiny of the vast body of literature available on organic and inorganic filler based polymer membranes and links it to the new emerging trend towards novel combinations of multilayered polymer membranes for applications in DMFC and IT-PEFC. The paper carefully explores the advantages and disadvantages of the most common preparation techniques reported for multilayered membranes such as hot-pressing, casting and dip-coating and also summarises various other fresh and unique techniques employed for multilayer membrane preparation.

  7. The use of a dynamic hydrogen electrode as an electrochemical tool to evaluate plasma activated carbon as electrocatalyst support for direct methanol fuel cell

    SciTech Connect

    Carmo, Marcelo Roepke, Thorsten; Scheiba, Frieder; Roth, Christina; Moeller, Stephan; Fuess, Hartmut; Poco, Joao G.R.; Linardi, Marcelo

    2009-01-08

    The objectives of this study were to functionalize the carbon black surface by chemically introducing oxygenated groups using plasma technology. This should enable a better interaction of the carbon support with the metallic catalyst nanoparticles, hindering posterior support particle agglomeration and preventing loss of active surface. PtRu/C nanoparticles were anchored on the carbon supports by the impregnation method and direct reduction with hydrazine. Physical characterization of the materials was carried out using energy dispersive X-ray analysis and transmission electron microscopy. The screen printing technique was used to produce membrane electrode assemblies for single cell tests in methanol/air (DMFC). Tests were carried out using the dynamic hydrogen electrode as an electrochemical tool to evaluate the anode and cathode behavior separately.

  8. Reduction of carbon dioxide gas formation at the anode of a direct methanol fuel cell using chemically enhanced solubility

    NASA Astrophysics Data System (ADS)

    Lundin, Michael D.; McCready, Mark J.

    The production of CO 2 gas at the DMFC anode leads to dramatic increases in pumping power requirements and reduced power output because of mass transfer limitations as bubble trains form in the channels of larger stacks. Experimental observations taken in a 5 cm 2 DMFC test cell operated at 60 °C, 1 atm, and with a methanol/water fuel flow rates of 5-10 cm 3 min -1 indicate that the rate of bubble formation can be reduced by increasing the fuel flow because more liquid is available for the CO 2 to dissolve in. Further observations indicate that KOH and LiOH added to the fuel eliminates CO 2 gas formation in situ at low concentrations because of the greatly increased solubility that results. A mathematical model for the volumetric rate of CO 2 gas production that includes effects of temperature and solubility is developed and extended to include the effects of hydroxide ions in solution. The model is used to predict the onset location of gas formation in the flow field as well as the void fraction at any point in the flow field. Predictions from the model agree very well with our experiments. Model predictions explain differences in the initial location of bubble formation for fuel solutions pre-saturated with CO 2 as opposed to CO 2-free solutions. Experiments with KOH and LiOH added to fuel solutions confirm the validity of the model extension that includes solubility that is enhanced by chemical reaction. Experiments with LiOH, KOH, and ammonium hydroxide show that the long-term durability of standard Pt-Ru/Nafion ®/Pt membrane electrode assemblies is compromised because of the presence of lithium, potassium, and ammonium cations that interact with the Nafion ® membrane and result in increasing the ohmic limitations of the polymer electrolyte membrane. Experiments with Ca(OH) 2, while reducing gas formation, precipitate the product CaCO 3 out of solution too rapidly for downstream filtering, blocking channels in the flow field.

  9. Miniature robots can assist in laparoscopic cholecystectomy.

    PubMed

    Oleynikov, D; Rentschler, M; Hadzialic, A; Dumpert, J; Platt, S R; Farritor, S

    2005-04-01

    Laparoscopy reduces patient trauma but eliminates the surgeon's ability to directly view and touch the surgical environment. Although current robot-assisted laparoscopy improves the surgeon's ability to manipulate and visualize the target organs, the instruments and cameras remain constrained by the entry incision. This limits tool tip orientation and optimal camera placement. This article focuses on developing miniature in vivo robots to assist surgeons during laparoscopic surgery by providing an enhanced field of view from multiple angles and dexterous manipulators not constrained by the abdominal wall fulcrum effect. Miniature camera robots were inserted through a small incision into the insufflated abdominal cavity of an anesthetized pig. Trocar insertion and other laparoscopic tool placements were then viewed with these robotic cameras. The miniature robots provided additional camera angles that improved surgical visualization during a cholecystectomy. These successful prototype trials have demonstrated that miniature in vivo robots can provide surgeons with additional visual information that can increase procedural safety.

  10. Investigating the direct and indirect influences of light on short-term changes in methanol production and emission in Lycopersicon esculentum

    NASA Astrophysics Data System (ADS)

    Oikawa, P.; Li, L.; Timko, M.; Mak, J. E.; Lerdau, M.

    2010-12-01

    Plant-produced methanol (MeOH) is the largest source of MeOH to the atmosphere where it is the second most abundant organic gas after methane. Current MeOH emission models are limited by their inability to predict changes in MeOH production in plants, a process still not well understood. Previous modeling studies indicated that light may have a direct influence on phytogenic MeOH production. As light is known to regulate cell wall expansion, we predicted light to stimulate MeOH production through the pectin methylesterase (PME) pathway. After normalizing MeOH emissions for stomatal conductance, we were unable to detect a MeOH emission response to light over short time scales (20-30min). After experimentally controlling for stomatal conductance and temperature, no light activation of PME activity or MeOH emission was observed. Our results clearly demonstrate the lack of a direct influence of light on short-term changes in MeOH production and emission. Future investigation of the long-term impacts of light on MeOH production is needed as light history may be an important factor for predicting MeOH emission over diurnal and seasonal time scales.

  11. Method for making methanol

    DOEpatents

    Mednick, R. Lawrence; Blum, David B.

    1986-01-01

    Methanol is made in a liquid-phase methanol reactor by entraining a methanol-forming catalyst in an inert liquid and contacting said entrained catalyst with a synthesis gas comprising hydrogen and carbon monoxide.

  12. Method for making methanol

    DOEpatents

    Mednick, R. Lawrence; Blum, David B.

    1987-01-01

    Methanol is made in a liquid-phase methanol reactor by entraining a methanol-forming catalyst in an inert liquid and contacting said entrained catalyst with a synthesis gas comprising hydrogen and carbon monoxide.

  13. Method of steam reforming methanol to hydrogen

    DOEpatents

    Beshty, Bahjat S.

    1990-01-01

    The production of hydrogen by the catalyzed steam reforming of methanol is accomplished using a reformer of greatly reduced size and cost wherein a mixture of water and methanol is superheated to the gaseous state at temperatures of about 800.degree. to about 1,100.degree. F. and then fed to a reformer in direct contact with the catalyst bed contained therein, whereby the heat for the endothermic steam reforming reaction is derived directly from the superheated steam/methanol mixture.

  14. Development of tunable miniature piezoelectric-based scanners validated by the combination of two scanners in a direct image relay technique

    NASA Astrophysics Data System (ADS)

    Shadfan, Adam Harbi; Pawlowski, Michal Emanuel; Tkaczyk, Tomasz S.

    2016-01-01

    Miniature piezoelectric actuators are commonly used as a compact means to relay images for numerous endoscopic applications. These scanners normally consist of an electrically driven lead zirconate titanate (PZT) tube that oscillates an optical fiber at its resonant frequency. The diameter and length of the PZT and fiber, the attachment of the fiber to the PZT, as well as the driving signal determine the main characteristics of the scan-frequency and amplitude of vibration. We present a new, robust, and repeatable method for producing miniature PZT actuators. The described technology allows for continuous tuning of the scanner mechanical properties during the assembly stage, enabling adjustment of resonant frequency and subsequent amplitude of vibration without a priori knowledge of the fiber's mechanical properties. The method consists of manufacturing high-precision fiber-holding plastic inserts with diamond turning lathes that allow for the fiber length to be quickly varied and locked during operation in order to meet the preferred performance. This concept of tuned PZTs was demonstrated with an imaging technique that combined two scanners oscillating in unison at the ends of a single optical fiber to relay images without the need to correlate the driving signal with a detector.

  15. Handheld interface for miniature sensors

    NASA Astrophysics Data System (ADS)

    Kedia, Sunny; Samson, Scott A.; Farmer, Andrew; Smith, Matthew C.; Fries, David; Bhansali, Shekhar

    2005-02-01

    Miniaturization of laboratory sensors has been enabled by continued evolution of technology. Field portable systems are often desired, because they reduce sample handling, provide rapid feedback capability, and enhance convenience. Fieldable sensor systems should include a method for initiating the analysis, storing and displaying the results, while consuming minimal power and being compact and portable. Low cost will allow widespread usage of these systems. In this paper, we discuss a reconfigurable Personal Data Assistant (PDA) based control and data collection system for use with miniature sensors. The system is based on the Handspring visor PDA and a custom designed motherboard, which connects directly to the PDA microprocessor. The PDA provides a convenient and low cost graphical user interface, moderate processing capability, and integrated battery power. The low power motherboard provides the voltage levels, data collection, and input/output (I/O) capabilities required by many MEMS and miniature sensors. These capabilities are relayed to connectors, where an application specific daughterboard is attached. In this paper, two applications are demonstrated. First, a handheld nucleic acid sequence-based amplification (NASBA) detection sensor consisting of a heated and optical fluorescence detection system is discussed. Second, an electrostatically actuated MEMS micro mirror controller is realized.

  16. Two new methanol converters

    SciTech Connect

    Westerterp, K.R.; Bodewes, T.N.; Vrijiand, M.S.A.; Kuczynski, M. )

    1988-11-01

    Two novel converter systems were developed for the manufacture of methanol from synthesis gas: the Gas-Solid-Solid Trickle Flow Reactor (GSSTFR) and the Reactor System with Interstage Product Removal (RSIPR). In the GSSTFR version, the product formed at the catalyst surface is directly removed from the reaction zone by means of a solid adsorbent. This adsorbent continuously trickles over the catalyst bed. High reactant conversions up to 100% can be achieved in a single pass so that the usual recycle loop for the unconverted reactants is absent or greatly reduced in size. In the RSIPR version, high conversions per pass are achieved in a series of adiabatic or isothermal fixed bed reactors with selective product removal in absorbers between the reactor stages. The feasibility and economics of the two systems are discussed on the basis of 1,000 tpd methanol plants compared with a low-pressure Lurgi system.

  17. Miniature spinning as a fiber quality assessment tool

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Miniature spinning has long been used to assess cotton varieties in a timely manner. It has been an accepted fact that the quality of miniature spinning is less than optimal, but that it allows a direct comparison between cottons during varietal studies. Recently, researchers have made processing ...

  18. Rapid starting methanol reactor system

    DOEpatents

    Chludzinski, Paul J.; Dantowitz, Philip; McElroy, James F.

    1984-01-01

    The invention relates to a methanol-to-hydrogen cracking reactor for use with a fuel cell vehicular power plant. The system is particularly designed for rapid start-up of the catalytic methanol cracking reactor after an extended shut-down period, i.e., after the vehicular fuel cell power plant has been inoperative overnight. Rapid system start-up is accomplished by a combination of direct and indirect heating of the cracking catalyst. Initially, liquid methanol is burned with a stoichiometric or slightly lean air mixture in the combustion chamber of the reactor assembly. The hot combustion gas travels down a flue gas chamber in heat exchange relationship with the catalytic cracking chamber transferring heat across the catalyst chamber wall to heat the catalyst indirectly. The combustion gas is then diverted back through the catalyst bed to heat the catalyst pellets directly. When the cracking reactor temperature reaches operating temperature, methanol combustion is stopped and a hot gas valve is switched to route the flue gas overboard, with methanol being fed directly to the catalytic cracking reactor. Thereafter, the burner operates on excess hydrogen from the fuel cells.

  19. Methanol poisoning

    MedlinePlus

    ... with has an exposure, call your local emergency number (such as 911), or your local poison center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.

  20. Superamphiphobic miniature boat fabricated by laser micromachining

    NASA Astrophysics Data System (ADS)

    Yin, Kai; Dong, Xinran; Zhang, Fan; Wang, Cong; Duan, Ji'an

    2017-03-01

    We fabricated a superamphiphobic miniature boat with marked drag reduction and excellent loading capacity using femtosecond laser direct writing technology. The as-prepared superamphiphobic surface of the boat exhibited apparent contact angles larger than 150° toward both water and oil. Miniature boats with the superamphiphobic surface slid effortlessly on both water and oil-polluted water surfaces, with an increase in sliding distance by up to 52% and load increase of up to 27% compared with those of a boat with an untreated surface. A potential mechanism that explains the excellent performance of the superamphiphobic miniature boat was also discussed. This work provides a simple and economically viable strategy to obtain advanced surfaces for use in microfluidics and marine engineering.

  1. Chemistry "en Miniature"

    NASA Astrophysics Data System (ADS)

    Roesky, Herbert W.

    1997-04-01

    By using the video camera projector system we are improving the techniques which are employed in various schools. This is an important reason for employing "Chemistry en Miniature", as this method provides a new means of demonstrating chemical experiments in a lecture hall.

  2. Miniaturized Environmental Monitoring Instrumentation

    SciTech Connect

    C. B. Freidhoff

    1997-09-01

    The objective of the Mass Spectrograph on a Chip (MSOC) program is the development of a miniature, multi-species gas sensor fabricated using silicon micromachining technology which will be orders of magnitude smaller and lower power consumption than a conventional mass spectrometer. The sensing and discrimination of this gas sensor are based on an ionic mass spectrograph, using magnetic and/or electrostatic fields. The fields cause a spatial separation of the ions according to their respective mass-to-charge ratio. The fabrication of this device involves the combination of microelectronics with micromechanically built sensors and, ultimately, vacuum pumps. The prototype of a chemical sensor would revolutionize the method of performing environmental monitoring for both commercial and government applications. The portable unit decided upon was the miniaturized gas chromatograph with a mass spectrometer detector, referred to as a GC/MS in the analytical marketplace.

  3. Miniaturization in Biocatalysis

    PubMed Central

    Fernandes, Pedro

    2010-01-01

    The use of biocatalysts for the production of both consumer goods and building blocks for chemical synthesis is consistently gaining relevance. A significant contribution for recent advances towards further implementation of enzymes and whole cells is related to the developments in miniature reactor technology and insights into flow behavior. Due to the high level of parallelization and reduced requirements of chemicals, intensive screening of biocatalysts and process variables has become more feasible and reproducibility of the bioconversion processes has been substantially improved. The present work aims to provide an overview of the applications of miniaturized reactors in bioconversion processes, considering multi-well plates and microfluidic devices, update information on the engineering characterization of the hardware used, and present perspective developments in this area of research. PMID:20479988

  4. Miniaturized photoacoustic spectrometer

    DOEpatents

    Okandan, Murat; Robinson, Alex; Nielson, Gregory N.; Resnick, Paul J.

    2016-08-09

    A low-power miniaturized photoacoustic sensor uses an optical microphone made by semiconductor fabrication techniques, and optionally allows for all-optical communication to and from the sensor. This allows integration of the photoacoustic sensor into systems with special requirements, such as those that would be reactive in an electrical discharge condition. The photoacoustic sensor can also be operated in various other modes with wide application flexibility.

  5. Miniature ceramic fuel cell

    DOEpatents

    Lessing, Paul A.; Zuppero, Anthony C.

    1997-06-24

    A miniature power source assembly capable of providing portable electricity is provided. A preferred embodiment of the power source assembly employing a fuel tank, fuel pump and control, air pump, heat management system, power chamber, power conditioning and power storage. The power chamber utilizes a ceramic fuel cell to produce the electricity. Incoming hydro carbon fuel is automatically reformed within the power chamber. Electrochemical combustion of hydrogen then produces electricity.

  6. Miniature Airflow Sensor

    NASA Technical Reports Server (NTRS)

    Kershner, D. D.

    1984-01-01

    Miniature flow-angle and airspeed sensor quickly mounted on light aircraft wing with two-sided tape since conventional sensors are restricted to large aircraft. Sensor operates as free-trailing wind vane selfalineing in airstream through two independent axes. Vane attached to wing surface through hollow mounting boom that fits on mounting plate attached to wing with two-sided neoprene-foam tape. Method shown strong enough for loads of low-speed flight.

  7. Pd and Pt-Ru anode electrocatalysts supported on multi-walled carbon nanotubes and their use in passive and active direct alcohol fuel cells with an anion-exchange membrane (alcohol = methanol, ethanol, glycerol)

    NASA Astrophysics Data System (ADS)

    Bambagioni, Valentina; Bianchini, Claudio; Marchionni, Andrea; Filippi, Jonathan; Vizza, Francesco; Teddy, Jacques; Serp, Philippe; Zhiani, Mohammad

    Palladium and platinum-ruthenium nanoparticles supported on multi-walled carbon nanotubes (MWCNT) are prepared by the impregnation-reduction procedure. The materials obtained, Pd/ MWCNT and Pt-Ru/ MWCNT, are characterized by TEM, ICP-AES and XRPD. Electrodes coated with Pd/ MWCNT are scrutinized for the oxidation of methanol, ethanol or glycerol in 2 M KOH solution in half cells. The catalyst is very active for the oxidation of all alcohols, with glycerol providing the best performance in terms of specific current density and ethanol showing the lowest onset potential. Membrane-electrode assemblies have been fabricated using Pd/ MWCNT anodes, commercial cathodes and anion-exchange membrane and evaluated in both single passive and active direct alcohol fuel cells fed with aqueous solutions of 10 wt.% methanol, 10 wt.% ethanol or 5 wt.% glycerol. Pd/ MWCNT exhibits unrivalled activity as anode electrocatalyst for alcohol oxidation. The analysis of the anode exhausts shows that ethanol is selectively oxidized to acetic acid, detected as acetate ion in the alkaline media of the reaction, while methanol yields carbonate and formate. A much wider product distribution, including glycolate, glycerate, tartronate, oxalate, formate and carbonate, is obtained from the oxidation of glycerol. The results obtained with Pt-Ru/ MWCNT anodes in acid media are largely inferior to those provided by Pd/ MWCNT electrodes in alkaline media.

  8. Miniature drag-force anemometer

    NASA Technical Reports Server (NTRS)

    Krause, L. N.; Fralick, G. C.

    1977-01-01

    A miniature drag-force anemometer is described which is capable of measuring dynamic velocity head and flow direction. The anemometer consists of a silicon cantilever beam 2.5 mm long, 1.5 mm wide, and 0.25 mm thick with an integrated diffused strain-gage bridge, located at the base of the beam, as the force measuring element. The dynamics of the beam are like those of a second-order system with a natural frequency of about 42 kHz and a damping coefficient of 0.007. The anemometer can be used in both forward and reversed flow. Measured flow characteristics up to Mach 0.6 are presented along with application examples including turbulence measurements.

  9. Miniaturized flow injection analysis system

    DOEpatents

    Folta, J.A.

    1997-07-01

    A chemical analysis technique known as flow injection analysis is described, wherein small quantities of chemical reagents and sample are intermixed and reacted within a capillary flow system and the reaction products are detected optically, electrochemically, or by other means. A highly miniaturized version of a flow injection analysis system has been fabricated utilizing microfabrication techniques common to the microelectronics industry. The microflow system uses flow capillaries formed by etching microchannels in a silicon or glass wafer followed by bonding to another wafer, commercially available microvalves bonded directly to the microflow channels, and an optical absorption detector cell formed near the capillary outlet, with light being both delivered and collected with fiber optics. The microflow system is designed mainly for analysis of liquids and currently measures 38{times}25{times}3 mm, but can be designed for gas analysis and be substantially smaller in construction. 9 figs.

  10. Miniaturized flow injection analysis system

    DOEpatents

    Folta, James A.

    1997-01-01

    A chemical analysis technique known as flow injection analysis, wherein small quantities of chemical reagents and sample are intermixed and reacted within a capillary flow system and the reaction products are detected optically, electrochemically, or by other means. A highly miniaturized version of a flow injection analysis system has been fabricated utilizing microfabrication techniques common to the microelectronics industry. The microflow system uses flow capillaries formed by etching microchannels in a silicon or glass wafer followed by bonding to another wafer, commercially available microvalves bonded directly to the microflow channels, and an optical absorption detector cell formed near the capillary outlet, with light being both delivered and collected with fiber optics. The microflow system is designed mainly for analysis of liquids and currently measures 38.times.25.times.3 mm, but can be designed for gas analysis and be substantially smaller in construction.

  11. Compact Fuel-Cell System Would Consume Neat Methanol

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram; Kindler, Andrew; Valdez, Thomas

    2007-01-01

    In a proposed direct methanol fuel-cell electric-power-generating system, the fuel cells would consume neat methanol, in contradistinction to the dilute aqueous methanol solutions consumed in prior direct methanol fuel-cell systems. The design concept of the proposed fuel-cell system takes advantage of (1) electro-osmotic drag and diffusion processes to manage the flows of hydrogen and water between the anode and the cathode and (2) evaporative cooling for regulating temperature. The design concept provides for supplying enough water to the anodes to enable the use of neat methanol while ensuring conservation of water for the whole fuel-cell system.

  12. Mars Miniature Science Instruments

    NASA Technical Reports Server (NTRS)

    Kim, Soon Sam; Hayati, Samad; Lavery, David; McBrid, Karen

    2006-01-01

    For robotic Mars missions, all the science information is gathered through on-board miniature instruments that have been developed through many years of R&D. Compared to laboratory counterparts, the rover instruments require miniaturization, such as low mass (1-2 kg), low power (> 10 W) and compact (1-2 liter), yet with comparable sensitivity. Since early 1990's, NASA recognized the need for the miniature instruments and launched several instrument R&D programs, e.g., PIDDP (Planetary Instrument Definition and Development). However, until 1998, most of the instrument R&D programs supported only up to a breadboard level (TRL 3, 4) and there is a need to carry such instruments to flight qualifiable status (TU 5, 6) to respond to flight AOs (Announcement of Opportunity). Most of flight AOs have only limited time and financial resources, and can not afford such instrument development processes. To bridge the gap between instrument R&D programs and the flight instrument needs, NASA's Mars Technology Program (MTP) created advanced instrumentation program, Mars Instrument Development Project (MIDP). MIDP candidate instruments are selected through NASA Research Announcement (NRA) process [l]. For example, MIDP 161998-2000) selected and developed 10 instruments, MIDP II (2003-2005) 16 instruments, and MIDP III (2004-2006) II instruments.Working with PIs, JPL has been managing the MIDP tasks since September 1998. All the instruments being developed under MIDP have been selected through a highly competitive NRA process, and employ state-of-the-art technology. So far, four MIDP funded instruments have been selected by two Mars missions (these instruments have further been discussed in this paper).

  13. Miniature Laser Magnetometer

    NASA Technical Reports Server (NTRS)

    Slocum, Robert; Brown, Andy

    2011-01-01

    A conceptual design has been developed for a miniature laser magnetometer (MLM) that will measure the scalar magnitude and vector components of near-Earth magnetic fields. The MLM incorporates a number of technical innovations to achieve high-accuracy and high-resolution performance while significantly reducing the size of the laser-pumped helium magnetometer for use on small satellites and unmanned aerial vehicles (UAVs). and electronics sections that has the capability of measuring both the scalar magnetic field magnitude and the vector magnetic field components. Further more, the high-accuracy scalar measurements are used to calibrate and correct the vector component measurements in order to achieve superior vector accuracy and stability. The correction algorithm applied to the vector components for calibration and the same cell for vector and scalar measurements are major innovations. The separate sensor and electronics section of the MLM instrument allow the sensor to be installed on a boom or otherwise located away from electronics and other noisy magnetic components. The MLM s miniaturization will be accomplished through the use of advanced miniaturized components and packaging methods for the MLM sensor and electronics. The MLM conceptual design includes three key innovations. The first is a new non-magnetic laser package that will allow the placement of the laser pump source near the helium cell sensing elements. The second innovation is the design of compact, nested, triaxial Braunbek coils used in the vector measurements that reduce the coil size by a factor of two compared to existing Helmholtz coils with similar field-generation performance. The third innovation is a compact sensor design that reduces the sensor volume by a factor of eight compared to MLM s predecessor.

  14. Miniature electrical connector

    DOEpatents

    Casper, Robert F.

    1976-01-01

    A miniature coaxial cable electrical connector includes an annular compressible gasket in a receptacle member, the gasket having a generally triangular cross section resiliently engaging and encircling a conically tapered outer surface of a plug member to create an elongated current leakage path at their interface; means for preventing rotation of the plug relative to the receptacle; a metal sleeve forming a portion of the receptacle and encircling the plug member when interconnected; and a split ring in the plug having outwardly and rearwardly projecting fingers spaced from and encircling a portion of a coaxial cable and engageable with the metal sleeve to interlock the receptacle and plug.

  15. Miniaturized optical wavelength sensors

    NASA Astrophysics Data System (ADS)

    Kung, Helen Ling-Ning

    Recently semiconductor processing technology has been applied to the miniaturization of optical wavelength sensors. Compact sensors enable new applications such as integrated diode-laser wavelength monitors and frequency lockers, portable chemical and biological detection, and portable and adaptive hyperspectral imaging arrays. Small sensing systems have trade-offs between resolution, operating range, throughput, multiplexing and complexity. We have developed a new wavelength sensing architecture that balances these parameters for applications involving hyperspectral imaging spectrometer arrays. In this thesis we discuss and demonstrate two new wavelength-sensing architectures whose single-pixel designs can easily be extended into spectrometer arrays. The first class of devices is based on sampling a standing wave. These devices are based on measuring the wavelength-dependent period of optical standing waves formed by the interference of forward and reflected waves at a mirror. We fabricated two different devices based on this principle. The first device is a wavelength monitor, which measures the wavelength and power of a monochromatic source. The second device is a spectrometer that can also act as a selective spectral coherence sensor. The spectrometer contains a large displacement piston-motion MEMS mirror and a thin GaAs photodiode flip-chip bonded to a quartz substrate. The performance of this spectrometer is similar to that of a Michelson in resolution, operating range, throughput and multiplexing but with the added advantages of fewer components and one-dimensional architecture. The second class of devices is based on the Talbot self-imaging effect. The Talbot effect occurs when a periodic object is illuminated with a spatially coherent wave. Periodically spaced self-images are formed behind the object. The spacing of the self-images is proportional to wavelength of the incident light. We discuss and demonstrate how this effect can be used for spectroscopy

  16. Miniature cold gas thrusters

    NASA Astrophysics Data System (ADS)

    Bzibziak, R. J., Sr.

    1992-07-01

    Cold gas thrusters provide a safe, inexpensive, lightweight and reliable means of propulsive control for small satellites, projectiles and maneuvering control systems. Moog Inc. has designed and developed a family of miniature cold gas thrusters for use on Strategic Defense Iniative flight simulation experiments, sounding rockets, small satellite applications, astronaut control systems, and close proximity maneuvering systems for Space System. Construction features such as coil assembly, core assembly, armature assembly, external housing and valve body are discussed. The design approach, performance characteristics and functional description of cold gas thrusters designed for various applications are presented.

  17. Miniaturized radiation chirper

    DOEpatents

    Umbarger, C. John; Wolf, Michael A.

    1980-01-01

    The disclosure relates to a miniaturized radiation chirper for use with a small battery supplying on the order of 5 volts. A poor quality CdTe crystal which is not necessarily suitable for high resolution gamma ray spectroscopy is incorporated with appropriate electronics so that the chirper emits an audible noise at a rate that is proportional to radiation exposure level. The chirper is intended to serve as a personnel radiation warning device that utilizes new and novel electronics with a novel detector, a CdTe crystal. The resultant device is much smaller and has much longer battery life than existing chirpers.

  18. Imidazolium-functionalized poly(ether ether ketone) as membrane and electrode ionomer for low-temperature alkaline membrane direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Yan, Xiaoming; Gu, Shuang; He, Gaohong; Wu, Xuemei; Benziger, Jay

    2014-03-01

    A series of imidazolium-functionalized poly(ether ether ketone)s (PEEK-ImOHs) were successfully synthesized by a two-step chloromethylation-Menshutkin reaction followed by hydroxide exchange. PEEK-ImOH membranes with ion exchange capacity (IEC) ranging from 1.56 to 2.24 mmol g-1 were prepared by solution casting. PEEK-ImOHs show selective solubility in aqueous solutions of acetone and tetrahydrofuran, but are insoluble in lower alcohols. PEEK-ImOH membranes with IEC of 2.03 mmol g-1 have high hydroxide conductivity (52 mS cm-1 at 20 °C), acceptable water swelling ratio (51% at 60 °C), and great tensile strength (78 MPa), and surprising flexibility (elongation-to-break of 168%), and high thermal stability (Decomposition temperature: 193 °C). In addition, PEEK-ImOH membranes show low methanol permeability (1.3-6.9 × 10-7 cm2 s-1). PEEK-ImOH membrane was tested in methanol/O2 fuel cell as both the HEM and the ionomer impregnated into the catalyst layer; the open circuit voltage is 0.84 V and the peak power density is 31 mW cm-2.

  19. Preparation of main-chain-type and side-chain-type sulfonated poly(ether ether ketone) membranes for direct methanol fuel cell applications

    NASA Astrophysics Data System (ADS)

    Tsai, Jie-Cheng; Lin, Chien-Kung

    Novel main-chain-type and side-chain-type sulphonated poly(ether ether ketone)s (MS-SPEEKs) are synthesised by reacting the sulphonic acid groups of pristine SPEEKs with 2-aminoethanesulphonic acid to improve the nano-phase separated morphology of the material. 1H NMR and FT-IR spectroscopy are employed to determine the structure and composition of main-chain-type and side-chain-type sulphonated polymers. Flexible and tough membranes with reasonable thermal properties are obtained. The MS-SPEEKs show good hydrolytic stability, and water uptake values ranging from 15% to 30% are observed. Compared to Nafion 117 ®, the methanol permeability of the MS-SPEEKs is dramatically reduced to 8.83 × 10 -8 cm 2 s -1 to 3.31 × 10 -7 cm 2 s -1. The proton conductivity increases with increasing temperature, reaching 0.013-0.182 S cm -1. A maximum power density and open circuit voltage of 115 mW cm -2 and 0.830 V are obtained at 80 °C, respectively, which is significantly greater than the values generated with Nafion 117 ®. The introduction of pendent side-chain-type sulphonic acid groups increases the single-cell performance by more than approximately 20%; thus, the lower water diffusivity, methanol permeability, electro-osmotic drag coefficient and high cell performance indicated that MS-SPEEK is a promising candidate for DMFC applications.

  20. Miniature Reversal Electron-Attachment Detector

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara

    1994-01-01

    Miniature reversal electron-attachment detector (miniREAD) enables direct injection of air or vapor at atmospheric pressure from monitored area into mass-spectrometric instrument to detect explosives, narcotics, or other substances, vapors of which suspected of being present in low concentrations. In comparison with older reversal electron-attachment detector, miniREAD simpler in design; more rugged; and easier to build, repair, and maintain. In addition, probably more sensitive.

  1. Computer-Aided High Precision Verification Of Miniature Spring Structure

    NASA Astrophysics Data System (ADS)

    Bow, Sing T.; Wang, Da-hao; Chen, Tsung-sheng; Newell, Darrell E.

    1990-01-01

    A system is proposed for the high precision on-line verification of the minia-ture spring structure, including overall height, diameters of various coils as well as pitches between neighboring coils of the miniature conical springs. High preci-sion measurements without physical contact and short processing time are achieved. Deformations of any kind on the conical springs can be identified even from the worst viewing direction.

  2. Miniature snapshot multispectral imager

    NASA Astrophysics Data System (ADS)

    Gupta, Neelam; Ashe, Philip R.; Tan, Songsheng

    2011-03-01

    We present a miniature snapshot multispectral imager based on using a monolithic filter array that operates in the short wavelength infrared spectral region and has a number of defense and commercial applications. The system is low-weight, portable with a miniature platform, and requires low power. The imager uses a 4×4 Fabry-Pérot filter array operating from 1487 to 1769 nm with a spectral bandpass ~10 nm. The design of the filters is based on using a shadow mask technique to fabricate an array of Fabry-Pérot etalons with two multilayer dielectric mirrors. The filter array is installed in a commercial handheld InGaAs camera, replacing the imaging lens with a custom designed 4×4 microlens assembly with telecentric imaging performance in each of the 16 subimaging channels. We imaged several indoor and outdoor scenes. The microlens assembly and filter design is quite flexible and can be tailored for any wavelength region from the ultraviolet to the longwave infrared, and the spectral bandpass can also be customized to meet sensing requirements. In this paper we discuss the design and characterization of the filter array, the microlens optical assembly, and imager and present imaging results.

  3. Miniature electrically operated diaphragm valve

    DOEpatents

    Adkins, Douglas R.; Spletzer, Barry L.; Wong, Chungnin C.; Frye-Mason, Gregory C.; Fischer, Gary J.; Hesketh, Peter J.

    2001-01-01

    The present invention provides a miniature electrically operated valve that can stand off significant pressures, that can be inexpensively produced, and that can be made to operate without continuous electrical power. A valve according to the present invention comprises a housing and a beam mounted with the housing. A diaphragm mounted with the housing forms a sealed fluid volume. An electromagnetic energy source, such as an electromagnetic coil, mounts with the housing and when energized urges the beam in one direction. The beam can be urged in the opposing direction by passive means or by reversing the polarity of the electromagnetic energy source or by a second electromagnetic energy source. Two fluid ports mount with the housing. A first fluid port mounts so that, as the beam is urged in one direction or the opposite, the beam urges the diaphragm to move between engaging and substantially sealing the fluid port and disengaging and not substantially sealing the fluid port. A seat can be mounted with the diaphragm to aid in sealing the fluid port. Latching mechanisms such as permanent magnets can be mounted so that the valve remains in the open or closed positions without continuous electrical power input. Fluid can flow through the housing between the two fluid ports when the diaphragm does not seal the first fluid port, but can be prevented from flowing by urging the beam so that the diaphragm seals the first fluid port. Various embodiments accommodate various latching mechanisms, electromagnetic energy sources, number of fluid ports, and diaphragm design considerations.

  4. Fast-Track, One-Step E. coli Detection: A Miniaturized Hydrogel Array Permits Specific Direct PCR and DNA Hybridization while Amplification.

    PubMed

    Beyer, Antje; Pollok, Sibyll; Rudloff, Anne; Cialla-May, Dana; Weber, Karina; Popp, Jürgen

    2016-09-01

    A timesaving and convenient method for bacterial detection based on one-step, one-tube deoxyribonucleic acid (DNA) hybridization on hydrogel array while target gene amplification is described. The hydrogel array is generated by a fast one-pot synthesis, where N,N'-dimethylacrylamide/polyethyleneglycol(PEG1900 )-bisacrylamide mixture polymerizes via radical photoinitiation by visible light within 20 min concomitant with in situ capture probe immobilization. These DNA-functionalized hydrogel droplets arrayed on a planar glass surface are placed in the polymerase chain reaction (PCR) mixture during the thermal amplification cycles. The bacterial cells can be implemented in a direct PCR reaction, omitting the need for prior template DNA extraction. The resulting fluorescence signal is immediately detectable after the end of the PCR (1 h) following one short washing step by microscopy. Therefore a valid signal can be reached within 1.5 h including 10 min for pipetting and placement of the tubes and chips. The performance of this novel hydrogel DNA array was successfully proven with varying cell numbers down to a limit of 10(1) Escherichia coli cells.

  5. Transesterification of waste vegetable oil under pulse sonication using ethanol, methanol and ethanol–methanol mixtures

    SciTech Connect

    Martinez-Guerra, Edith; Gude, Veera Gnaneswar

    2014-12-15

    Highlights: • Pulse sonication effect on transesterification of waste vegetable oil was studied. • Effects of ethanol, methanol, and alcohol mixtures on FAMEs yield were evaluated. • Effect of ultrasonic intensity, power density, and its output rates were evaluated. • Alcohol mixtures resulted in higher biodiesel yields due to better solubility. - Abstract: This study reports on the effects of direct pulse sonication and the type of alcohol (methanol and ethanol) on the transesterification reaction of waste vegetable oil without any external heating or mechanical mixing. Biodiesel yields and optimum process conditions for the transesterification reaction involving ethanol, methanol, and ethanol–methanol mixtures were evaluated. The effects of ultrasonic power densities (by varying sample volumes), power output rates (in W), and ultrasonic intensities (by varying the reactor size) were studied for transesterification reaction with ethanol, methanol and ethanol–methanol (50%-50%) mixtures. The optimum process conditions for ethanol or methanol based transesterification reaction of waste vegetable oil were determined as: 9:1 alcohol to oil ratio, 1% wt. catalyst amount, 1–2 min reaction time at a power output rate between 75 and 150 W. It was shown that the transesterification reactions using ethanol–methanol mixtures resulted in biodiesel yields as high as >99% at lower power density and ultrasound intensity when compared to ethanol or methanol based transesterification reactions.

  6. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    1999-01-01

    A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

  7. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, S.; Kumar, R.; Krumpelt, M.

    1999-08-17

    A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

  8. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, S.; Kumar, R.; Krumpelt, M.

    1999-08-24

    A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

  9. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    2001-01-01

    A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

  10. Miniature spectrally selective dosimeter

    NASA Astrophysics Data System (ADS)

    Adams, R. R.; MacConochie, I. O.; Poole, B. D., Jr.

    1980-10-01

    A miniature spectrally selective dosimeter capable of measuring selected bandwidths of radiation exposure on small mobile areas is described. This is achieved by the combination of photovoltaic detectors, electrochemical integrators (E-cells) and filters in a small compact case which can be easily attached in close proximity to and substantially parallel to the surface being measured. In one embodiment two photovoltaic detectors, two E-cells, and three filters are packaged in a small case with attaching means consisting of a safety pin. In another embodiment, two detectors, one E-cell, three filters are packaged in a small case with attaching means consisting of a clip to clip over a side piece of an eye glass frame.

  11. Miniature, ruggedized data collector

    NASA Astrophysics Data System (ADS)

    Jackson, Scott; Calcutt, Wade; Knobler, Ron; Jones, Barry; Klug, Robert

    2009-05-01

    McQ has developed a miniaturized, programmable, ruggedized data collector intended for use in weapon testing or data collection exercises that impose severe stresses on devices under test. The recorder is designed to survive these stresses which include acceleration and shock levels up to 100,000 G. The collector acquires and stores up to four channels of signal data to nonvolatile memory for later retrieval by a user. It is small (< 7 in3), light weight (< 1 lb), and can operate from various battery chemistries. A built-in menuing system, accessible via a USB interface, allows the user to configure parameters of the recorder operation, such as channel gain, filtering, and signal offsets, and also to retrieve recorded data for analysis. An overview of the collector, its features, performance, and potential uses, is presented.

  12. Miniature spectrally selective dosimeter

    NASA Technical Reports Server (NTRS)

    Adams, R. R.; Macconochie, I. O.; Poole, B. D., Jr. (Inventor)

    1980-01-01

    A miniature spectrally selective dosimeter capable of measuring selected bandwidths of radiation exposure on small mobile areas is described. This is achieved by the combination of photovoltaic detectors, electrochemical integrators (E-cells) and filters in a small compact case which can be easily attached in close proximity to and substantially parallel to the surface being measured. In one embodiment two photovoltaic detectors, two E-cells, and three filters are packaged in a small case with attaching means consisting of a safety pin. In another embodiment, two detectors, one E-cell, three filters are packaged in a small case with attaching means consisting of a clip to clip over a side piece of an eye glass frame.

  13. Miniaturized fundus camera

    NASA Astrophysics Data System (ADS)

    Gliss, Christine; Parel, Jean-Marie A.; Flynn, John T.; Pratisto, Hans S.; Niederer, Peter F.

    2003-07-01

    We present a miniaturized version of a fundus camera. The camera is designed for the use in screening for retinopathy of prematurity (ROP). There, but also in other applications a small, light weight, digital camera system can be extremely useful. We present a small wide angle digital camera system. The handpiece is significantly smaller and lighter then in all other systems. The electronics is truly portable fitting in a standard boardcase. The camera is designed to be offered at a compatible price. Data from tests on young rabbits' eyes is presented. The development of the camera system is part of a telemedicine project screening for ROP. Telemedical applications are a perfect application for this camera system using both advantages: the portability as well as the digital image.

  14. Miniature Latching Valve

    NASA Technical Reports Server (NTRS)

    Johnson, A. David; Benson, Glendon M.

    2008-01-01

    A miniature latching valve has been invented to satisfy a need for an electrically controllable on/off pneumatic valve that is lightweight and compact and remains in the most recently commanded open or closed state when power is not supplied. The valve includes a poppet that is moved into or out of contact with a seat to effect closure or opening, respectively, of the flow path. Motion of the poppet is initiated by electrical heating of one of two opposing pairs of nickel/titanium shape-memory alloy (SMA) wires above their transition temperature: heated wires contract to their remembered length, applying tension to pull the poppet toward or away from the seat. A latch consisting mainly of a bistable Belleville washer (a conical spring) made of a hardened stainless steel operates between two stable positions corresponding to the fully closed or fully open state, holding the poppet in one of these positions when power is not applied to either pair of SMA wires. To obtain maximum actuation force and displacement, the SMA wires must be kept in tension. The mounting fixtures at the ends of the wires must support large tensile stresses without creating stress concentrations that would limit the fatigue lives of the wires. An earlier design provided for each wire to be crimped in a conical opening with a conical steel ferrule that was swaged into the opening to produce a large, uniformly distributed holding force. In a subsequent design, the conical ferrule was replaced with a larger crimped cylindrical ferrule depicted in the figure. A major problem in designing the valve was to protect the SMA wires from a bake-out temperature of 300 C. The problem was solved by incorporating the SMA wires into an actuator module that is inserted into a barrel of the valve body and is held in place by miniature clip rings.

  15. Dietary methanol and autism.

    PubMed

    Walton, Ralph G; Monte, Woodrow C

    2015-10-01

    The authors sought to establish whether maternal dietary methanol during pregnancy was a factor in the etiology of autism spectrum disorders. A seven item questionnaire was given to women who had given birth to at least one child after 1984. The subjects were solicited from a large primary care practice and several internet sites and separated into two groups - mothers who had given birth to a child with autism and those who had not. Average weekly methanol consumption was calculated based on questionnaire responses. 550 questionnaires were completed by women who gave birth to a non-autistic child. On average these women consumed 66.71mg. of methanol weekly. 161 questionnaires were completed by women who had given birth to an autistic child. The average estimated weekly methanol consumption for this group was 142.31mg. Based on the results of the Wilcoxon rank sum-test, we see a significant difference between the reported methanol consumption rates of the two groups. This study suggests that women who have given birth to an autistic child are likely to have had higher intake of dietary sources of methanol than women who have not. Further investigation of a possible link of dietary methanol to autism is clearly warranted.

  16. Multi-functional reactively-sputtered copper oxide electrodes for supercapacitor and electro-catalyst in direct methanol fuel cell applications

    NASA Astrophysics Data System (ADS)

    Pawar, Sambhaji M.; Kim, Jongmin; Inamdar, Akbar I.; Woo, Hyeonseok; Jo, Yongcheol; Pawar, Bharati S.; Cho, Sangeun; Kim, Hyungsang; Im, Hyunsik

    2016-02-01

    This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu2O and CuO can be obtained by controlling the oxygen flow rate. The electrochemical energy storage properties of the films are investigated by carrying out cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The electrochemical analysis reveals that the Cu2O and CuO electrodes have high specific capacitances of 215 and 272 F/g in 6 M KOH solution with a capacity retention of about 80% and 85% after 3000 cycles, respectively. Cyclic voltammetry and chronoamperometry are used to study the electrochemical energy conversion properties of the films via methanol electro-oxidation. The results show that the Cu2O and CuO electrodes are electro-catalytically active and highly stable.

  17. Novel proton exchange membranes based on cardo poly(arylene ether sulfone/nitrile)s with perfluoroalkyl sulfonic acid moieties for passive direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Zheng, Jifu; He, Qingyi; Gao, Nian; Yuan, Ting; Zhang, Suobo; Yang, Hui

    2014-09-01

    A new series of cardo poly(arylene ether sulfone/nitrile)s FSPES-x with perfluoroalkyl sulfonic acid groups have been successfully prepared by the perfluorosulfonic acid lactone ring-opening reaction without using any metal or base catalysts. These materials have been characterized by IR, NMR and TGA. The results indicate that this simple and metal-free method of preparation is highly efficient for controlling both the degree of perfluorosulfonation and the position of the sulfonate group and no side reactions such as crosslinking is observed. The FSPES-x membranes (IEC = 1.17-1.64 m equiv g-1) show the desired characteristics such as good film-forming ability, excellent thermal and mechanical properties, low methanol permeability, high conductivity (up to 0.083 S cm-1 at room temperature), as well as appropriate cell performance compared to Nafion®117. With these properties, such fluorinated sulfonic acid side-chain-type polymers are promising PEM materials for application in fuel cells.

  18. Multi-functional reactively-sputtered copper oxide electrodes for supercapacitor and electro-catalyst in direct methanol fuel cell applications

    PubMed Central

    Pawar, Sambhaji M.; Kim, Jongmin; Inamdar, Akbar I.; Woo, Hyeonseok; Jo, Yongcheol; Pawar, Bharati S.; Cho, Sangeun; Kim, Hyungsang; Im, Hyunsik

    2016-01-01

    This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu2O and CuO can be obtained by controlling the oxygen flow rate. The electrochemical energy storage properties of the films are investigated by carrying out cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The electrochemical analysis reveals that the Cu2O and CuO electrodes have high specific capacitances of 215 and 272 F/g in 6 M KOH solution with a capacity retention of about 80% and 85% after 3000 cycles, respectively. Cyclic voltammetry and chronoamperometry are used to study the electrochemical energy conversion properties of the films via methanol electro-oxidation. The results show that the Cu2O and CuO electrodes are electro-catalytically active and highly stable. PMID:26888077

  19. High performance and durable nanostructured TiN supported Pt50-Ru50 anode catalyst for direct methanol fuel cell (DMFC)

    NASA Astrophysics Data System (ADS)

    Patel, Prasad Prakash; Datta, Moni Kanchan; Jampani, Prashanth H.; Hong, Daeho; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.

    2015-10-01

    The design of high performance and durable electro-catalyst has been of particular interest for DMFC anodes. Pt(Ru) has been considered the most active DMFC anode catalyst. In this work, the reaction kinetics of Pt(Ru) electro-catalyst has been improved by synthesizing high active surface area Pt50(Ru50) catalyst supported on highly conductive nanostructured titanium nitride, TiN. The Pt(Ru)/TiN has been synthesized by a complexed sol-gel (CSG) process using non-halide precursors of Pt and Ru. High surface area Pt(Ru)/TiN shows promising electrochemical performance for methanol oxidation, showing ∼52% improved catalytic activity at ∼0.65 V (vs NHE) and stability/durability in comparison with commercial JM-Pt(Ru). Single cell DMFC performance shows 56% improved maximum power density and superior electrochemical stability for CSG-Pt(Ru)/TiN compared to that of commercial JM-Pt(Ru). This is attributed to the uniform dispersion of Pt(Ru) achieved on the nanostructured TiN (support) yielding higher electrochemical active surface area and lower charge transfer resistance than commercial JM-Pt(Ru). Thus, the present study demonstrates the potential of nanostructured TiN as a support for Pt(Ru) based anode electro-catalyst for DMFC applications.

  20. Preparation and characterization of nanocomposite membranes made of poly(2,6-dimethyl-1,4-phenylene oxide) and montmorillonite for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Hasani-Sadrabadi, Mohammad Mahdi; Emami, Shahriar Hojjati; Moaddel, Homayoun

    Partially sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (sulfonated PPO) with various degrees of sulfonation were prepared. The solutions were mixed with organically modified montmorillonite (MMT) to prepare membranes by solvent casting. By increasing the sulfonation degree up to 40% for membranes without MMT, ion exchange capacity, water uptake and proton conductivity reached 2.59 mequiv. g -1, 21% and 0.0182 S cm -1, respectively. The Fourier transfer infrared (FTIR) analysis of sulfonated membranes revealed absorption bands at 1060 and 1100-1300 cm -1 for sulfur-oxygen S dbnd O bonds. X-ray diffraction analysis showed the exfoliated structure of clay in polymeric matrices. A sulfonated PPO/MMT membrane with 27% sulfonation and 2.0 wt% MMT loading showed a membrane selectivity of approximately 63,500 compared to 40,500 for Nafion ® 117, and also a higher power density (125 mW cm -2) than Nafion ® 117 (108 mW cm -2) for single cell DMFC in a 5 M methanol feed.

  1. Associated species in vaporized methanol-formaldehyde solutions

    SciTech Connect

    Silverman, D.C.; Freeman, J.J.

    1983-07-01

    Analysis of vaporized methanolic formaldehyde (50 mol % methanol) by gas chromatography revealed a sum of mole percents of formaldehyde, water, and methanol greater than 100%. This inconsistency was not found with vaporized solutions containing 1 or 10 mol % methanol. Direct evidence for an adduct of methanol and formaldehyde (CH/sub 3/OCH/sub 2/OH) in the vapor phase was found by use of infrared spectroscopy. The spectrum exhibited an absorption at 1140 cm/sup -1/ corresponding to a C-O-C stretch. Reasonable agreement was found between the C-O-C mole percent estimated from infrared spectroscopy, the increased amount of material detected by gas chromatography, and the estimated equilibrium mole percent of the adduct CH/sub 3/OCH/sub 2/OH. These results confirm that in completely vaporized methanolic formaldehyde at 373 to 423 K, one type of adduct predominates. It contains one molecule each of formaldehyde and methanol.

  2. Homogeneous catalyst formulations for methanol production

    DOEpatents

    Mahajan, Devinder; Sapienza, Richard S.; Slegeir, William A.; O'Hare, Thomas E.

    1990-01-01

    There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.13 ), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

  3. Homogeneous catalyst formulations for methanol production

    DOEpatents

    Mahajan, Devinder; Sapienza, Richard S.; Slegeir, William A.; O'Hare, Thomas E.

    1991-02-12

    There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.-), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

  4. Transesterification of waste vegetable oil under pulse sonication using ethanol, methanol and ethanol-methanol mixtures.

    PubMed

    Martinez-Guerra, Edith; Gude, Veera Gnaneswar

    2014-12-01

    This study reports on the effects of direct pulse sonication and the type of alcohol (methanol and ethanol) on the transesterification reaction of waste vegetable oil without any external heating or mechanical mixing. Biodiesel yields and optimum process conditions for the transesterification reaction involving ethanol, methanol, and ethanol-methanol mixtures were evaluated. The effects of ultrasonic power densities (by varying sample volumes), power output rates (in W), and ultrasonic intensities (by varying the reactor size) were studied for transesterification reaction with ethanol, methanol and ethanol-methanol (50%-50%) mixtures. The optimum process conditions for ethanol or methanol based transesterification reaction of waste vegetable oil were determined as: 9:1 alcohol to oil ratio, 1% wt. catalyst amount, 1-2 min reaction time at a power output rate between 75 and 150 W. It was shown that the transesterification reactions using ethanol-methanol mixtures resulted in biodiesel yields as high as >99% at lower power density and ultrasound intensity when compared to ethanol or methanol based transesterification reactions.

  5. The Methanol Multibeam Survey

    NASA Astrophysics Data System (ADS)

    Green, James A.; Cohen, R. J.; Caswell, J. L.; Fuller, G. A.; Brooks, K.; Burton, M. G.; Chrysostomou, A.; Diamond, P. J.; Ellingsen, S. P.; Gray, M. D.; Hoare, M. G.; Masheder, M. R. W.; McClure-Griffiths, N.; Pestalozzi, M.; Phillips, C.; Quinn, L.; Thompson, M. A.; Voronkov, M.; Walsh, A.; Ward-Thompson, D.; Wong-McSweeney, D.; Yates, J. A.; Cox, J.

    2007-03-01

    A new 7-beam methanol multibeam receiver is being used to survey the Galaxy for newly forming massive stars, that are pinpointed by strong methanol maser emission at 6.668 GHz. The receiver, jointly constructed by Jodrell Bank Observatory (JBO) and the Australia Telescope National Facility (ATNF), was successfully commissioned at Parkes in January 2006. The Parkes-Jodrell survey of the Milky Way for methanol masers is two orders of magnitude faster than previous systematic surveys using 30-m class dishes, and is the first systematic survey of the entire Galactic plane. The first 53 days of observations with the Parkes telescope have yielded 518 methanol sources, of which 218 are new discoveries. We present the survey methodology as well as preliminary results and analysis.

  6. Methanol Cannon Demonstrations Revisited.

    ERIC Educational Resources Information Center

    Dolson, David A.; And Others

    1995-01-01

    Describes two variations on the traditional methanol cannon demonstration. The first variation is a chain reaction using real metal chains. The second example involves using easily available components to produce sequential explosions that can be musical in nature. (AIM)

  7. The Whole new world of miniature technology

    SciTech Connect

    Gillespie, L.K.

    1980-07-01

    In the past ten years, miniaturization of both electrical and mechanical parts has significantly increased. Documentation of the design and production capabilities of miniaturization in the electronics industry is well-defined. Literature on the subject of miniaturization of metal piece parts, however, is hard to find. Some of the current capabilities in the manufacture of miniature metal piece parts or miniature features in larger piece parts are discussed.

  8. Miniature Chemical Sensor

    SciTech Connect

    Andrew C. R. Pipino

    2004-12-13

    A new chemical detection technology has been realized that addresses DOE environmental management needs. The new technology is based on a variant of the sensitive optical absorption technique, cavity ring-down spectroscopy (CRDS). Termed evanescent-wave cavity ring-down spectroscopy (EW-CRDS), the technology employs a miniature solid-state optical resonator having an extremely high Q-factor as the sensing element, where the high-Q is achieved by using ultra-low-attenuation optical materials, ultra-smooth surfaces, and ultra-high reflectivity coatings, as well as low-diffraction-loss designs. At least one total-internal reflection (TIR) mirror is integral to the resonator permitting the concomitant evanescent wave to probe the ambient environment. Several prototypes have been designed, fabricated, characterized, and applied to chemical detection. Moreover, extensions of the sensing concept have been explored to enhance selectivity, sensitivity, and range of application. Operating primarily in the visible and near IR regions, the technology inherently enables remote detection by optical fiber. Producing 11 archival publications, 5 patents, 19 invited talks, 4 conference proceedings, a CRADA, and a patent-license agreement, the project has realized a new chemical detection technology providing >100 times more sensitivity than comparable technologies, while also providing practical advantages.

  9. The Asian methanol market

    SciTech Connect

    Nagase, Hideki

    1995-12-31

    For the purpose of this presentation, Asia has been broadly defined as a total of 15 countries, namely Japan, Korea, Taiwan, China, Hong Kong, the Philippines, Thailand, Malaysia, Singapore, Indonesia, Myanmar, India, Vietnam, Australia and New Zealand. In 1994 and the first half of 1995, the methanol industry and its derivative industries experienced hard time, because of extraordinarily high methanol prices. In spite of this circumstance, methanol demand in Asian countries has been growing steadily and remarkably, following Asian high economic growth. Most of this growth in demand has been and will continue to be met by outside supply. However, even with increased import of methanol from outside of Asia, as a result of this growth, Asian trade volume will be much larger in the coming years. Asian countries must turn their collective attention to making logistics and transportation for methanol and its derivatives more efficient in the Asian region to make better use of existing supply resources. The author reviews current economic growth as his main topic, and explains the forecast of the growth of methanol demand and supply in Asian countries in the near future.

  10. Miniature Bipolar Electrostatic Ion Thruster

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2006-01-01

    The figure presents a concept of a bipolar miniature electrostatic ion thruster for maneuvering a small spacecraft. The ionization device in the proposed thruster would be a 0.1-micron-thick dielectric membrane with metal electrodes on both sides. Small conical holes would be micromachined through the membrane and electrodes. An electric potential of the order of a volt applied between the membrane electrodes would give rise to an electric field of the order of several mega-volts per meter in the submicron gap between the electrodes. An electric field of this magnitude would be sufficient to ionize all the molecules that enter the holes. In a thruster-based on this concept, one or more propellant gases would be introduced into such a membrane ionizer. Unlike in larger prior ion thrusters, all of the propellant molecules would be ionized. This thruster would be capable of bipolar operation. There would be two accelerator grids - one located forward and one located aft of the membrane ionizer. In one mode of operation, which one could denote the forward mode, positive ions leaving the ionizer on the backside would be accelerated to high momentum by an electric field between the ionizer and an accelerator grid. Electrons leaving the ionizer on the front side would be ejected into free space by a smaller accelerating field. The equality of the ion and electron currents would eliminate the need for an additional electron- or ion-emitting device to keep the spacecraft charge-neutral. In another mode of operation, which could denote the reverse mode, the polarities of the voltages applied to the accelerator grids and to the electrodes of the membrane ionizer would be the reverse of those of the forward mode. The reversal of electric fields would cause the ion and electrons to be ejected in the reverse of their forward mode directions, thereby giving rise to thrust in the direction opposite that of the forward mode.

  11. Methanol in dark clouds

    NASA Technical Reports Server (NTRS)

    Friberg, P.; Hjalmarson, A.; Madden, S. C.; Irvine, W. M.

    1988-01-01

    The first observation of methanol in cold dark clouds TMC 1, L 134 N, and B 335 is reported. In all three clouds, the relative abundance of methanol was found to be in the range of 10 to the -9th (i.e., almost an order of magnitude more abundant than acetaldehyde), with no observable variation between the clouds. Methanol emission showed a complex velocity structure; in TMC 1, clear indications of non-LTE were observed. Dimethyl ether was searched for in L 134 N; the upper limit of the column density of dimethyl ether in L 134 N was estimated to be 4 x 10 to the 12th/sq cm, assuming 5 K rotation temperature and LTE. This limit makes the abundance ratio (CH3)2O/CH3OH not higher than 1/5, indicating that dimethyl ether is not overabundant in this dark cloud.

  12. Miniaturized Cassegrainian concentrator concept demonstration

    NASA Astrophysics Data System (ADS)

    Patterson, R. E.; Rauschenbach, H. S.

    High concentration ratio photovoltaic systems for space applications have generally been considered impractical because of perceived difficulties in controlling solar cell temperatures to reasonably low values. A miniaturized concentrator system is now under development which surmounts this objection by providing acceptable solar cell temperatures using purely passive cell cooling methods. An array of identical miniaturized, rigid Cassegrainian optical systems having a low f-number with resulting short dimensions along their optical axes are rigidly mounted into a frame to form a relatively thin concentrator solar array panel. A number of such panels, approximately 1.5 centimeters thick, are wired as an array and are folded against one another for launch in a stowed configuration. Deployment on orbit is similar to the deployment of conventional planar honeycomb panel arrays or flexible blanket arrays. The miniaturized concept was conceived and studied in the 1978-80 time frame. Progress in the feasibility demonstration to date is reported.

  13. World methanol situation poses challenge in process design

    SciTech Connect

    Haggin, J.

    1984-07-16

    A review is presented of the technology and economics of methanol production processes. Synthesis gas production based on methane or coal are compared. Since methane-based synthesis gas is hydrogen rich and coal-based synthesis gas is carbon rich, the combination of both processes, as suggested by the M.W. Kellogg Co., should be economically attractive. A liquid-phase synthesis in the developmental stages and two reactor configurations under consideration for its use are discussed. The Wentworth system of catalytic processing, a Lurgi process using coal and methane for methanol, a Lurgi process for utilizing methanol in a variation of the Mobil methanol-to-gasoline process, and another Lurgi process to produce a methanol fuel mixture for direct use as a motor fuel, consisting of methanol and oxygenates, are also discussed.

  14. Miniature information displays: primary applications

    NASA Astrophysics Data System (ADS)

    Alvelda, Phillip; Lewis, Nancy D.

    1998-04-01

    Positioned to replace current liquid crystal display technology in many applications, miniature information displays have evolved to provide several truly portable platforms for the world's growing personal computing and communication needs. The technology and functionality of handheld computer and communicator systems has finally surpassed many of the standards that were originally established for desktop systems. In these new consumer electronics, performance, display size, packaging, power consumption, and cost have always been limiting factors for fabricating genuinely portable devices. The rapidly growing miniature information display manufacturing industry is making it possible to bring a wide range of highly anticipated new products to new markets.

  15. Methanol from coal

    NASA Technical Reports Server (NTRS)

    Miller, D. R.

    1978-01-01

    Economic feasibility of methanol or methyl fuel produced from coal using existing technology is discussed. Other factors considered include environmental, safety, toxicity, transportation, so storage, ease of burning, and retrofitting of present boilers. Demonstrations of its uses as a boiler fuel and as a turbine fuel are cited.

  16. Maximizing strain in miniaturized dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Rosset, Samuel; Araromi, Oluwaseun; Shea, Herbert

    2015-04-01

    We present a theoretical model to optimise the unidirectional motion of a rigid object bonded to a miniaturized dielectric elastomer actuator (DEA), a configuration found for example in AMI's haptic feedback devices, or in our tuneable RF phase shifter. Recent work has shown that unidirectional motion is maximized when the membrane is both anistropically prestretched and subjected to a dead load in the direction of actuation. However, the use of dead weights for miniaturized devices is clearly highly impractical. Consequently smaller devices use the membrane itself to generate the opposing force. Since the membrane covers the entire frame, one has the same prestretch condition in the active (actuated) and passive zones. Because the passive zone contracts when the active zone expands, it does not provide a constant restoring force, reducing the maximum achievable actuation strain. We have determined the optimal ratio between the size of the electrode (active zone) and the passive zone, as well as the optimal prestretch in both in-plane directions, in order to maximize the absolute displacement of the rigid object placed at the active/passive border. Our model and experiments show that the ideal active ratio is 50%, with a displacement twice smaller than what can be obtained with a dead load. We expand our fabrication process to also show how DEAs can be laser-post-processed to remove carefully chosen regions of the passive elastomer membrane, thereby increasing the actuation strain of the device.

  17. Photocatalytic conversion of methane to methanol

    SciTech Connect

    Taylor, C.E.; Noceti, R.P.; D`Este, J.R.

    1995-12-31

    A long-term goal of our research group is the exploration of novel pathways for the direct oxidation of methane to liquid fuels, chemicals, and intermediates. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol is attractive. The products of reaction, methanol and hydrogen, are both commercially desirable, methanol being used as is or converted to a variety of other chemicals, and the hydrogen could be utilized in petroleum and/or chemical manufacturing. Methane is produced as a by-product of coal gasification. Depending upon reactor design and operating conditions, up to 18% of total gasifier product may be methane. In addition, there are vast proven reserves of geologic methane in the world. Unfortunately, a large fraction of these reserves are in regions where there is little local demand for methane and it is not economically feasible to transport it to a market. There is a global research effort under way in academia, industry, and government to find methods to convert methane to useful, more readily transportable and storable materials. Methanol, the initial product of methane oxidation, is a desirable product of conversion because it retains much of the original energy of the methane while satisfying transportation and storage requirements. Investigation of direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of the current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol, is attractive. Research in the laboratory is directed toward applying the techniques developed for the photocatalytic splitting of the water and the photochemical conversion of methane.

  18. Preclinical evaluation of a miniaturized Deep Brain Stimulation electrode lead.

    PubMed

    Villalobos, Joel; Fallon, James B; McNeill, Peter M; Allison, Rachel K; Bibari, Olivier; Williams, Chris E; McDermott, Hugh J

    2015-01-01

    The effect of miniaturizing the electrode lead for Deep Brain Stimulation (DBS) therapy was investigated in this work. A direct comparison was made between a miniature lead (0.65 mm diameter) and a lead of standard size (1.3 mm). Acute in vivo implantation in two cat brains was performed to evaluate surgical trauma and confirm capacity to target thalamic nuclei. Insertion into a homogeneous gel model of neural tissue was used to compare insertion forces while visualizing the process. The standard size cannula, used first to guide lead insertion, required substantially higher insertion force compared with the miniature version and produced a significantly larger region of tissue disruption. The characteristic hemorrhage and edema extended 119-352 μm from the implanted track surface of the miniature lead and cannula, while these extended 311-571 μm for the standard size lead and cannula. A miniature DBS implant can reduce the extent of trauma and could potentially help improve neural function preservation after functional neurosurgery.

  19. Miniature Blimps for Surveillance and Collection of Samples

    NASA Technical Reports Server (NTRS)

    Jones, Jack

    2004-01-01

    Miniature blimps are under development as robots for use in exploring the thick, cold, nitrogen atmosphere of Saturn's moon, Titan. Similar blimps can also be used for surveillance and collection of biochemical samples in buildings, caves, subways, and other, similar structures on Earth. The widely perceived need for means to thwart attacks on buildings and to mitigate the effects of such attacks has prompted consideration of the use of robots. Relative to rover-type (wheeled) robots that have been considered for such uses, miniature blimps offer the advantage of ability to move through the air in any direction and, hence, to perform tasks that are difficult or impossible for wheeled robots, including climbing stairs and looking through windows. In addition, miniature blimps are expected to have greater range and to cost less, relative to wheeled robots.

  20. Visual thread quality for precision miniature mechanisms

    SciTech Connect

    Gillespie, L.K.

    1981-04-01

    Threaded features have eight visual appearance factors which can affect their function in precision miniature mechanisms. The Bendix practice in deburring, finishing, and accepting these conditions on miniature threads is described as is their impact in assemblies of precision miniature electromechanical assemblies.

  1. Neat methanol fuel cell power plant

    NASA Astrophysics Data System (ADS)

    Abens, S.; Farooque, M.

    1985-12-01

    Attention is given to a fuel cell development effort which has been directed, by ease-of-supply, low weight, and low volume criteria toward the use of undiluted methanol. Partial oxidation and internal water recovery concepts are incorporated, allowing the onboard dilution of methanol fuel through mixing with exhaust-recovered water. This scheme is successfully demonstrated for the case of a 3 kW unit employing commercial cross flow heat exchangers, as well as for a 5 kW reformer flue exhaust water recovery design with U.S. Air force baseload stationary applications. The USAF powerplant has an overall thermal efficiency of 32 percent at rated load.

  2. The Development of Methanol Industry and Methanol Fuel in China

    SciTech Connect

    Li, W.Y.; Li, Z.; Xie, K.C.

    2009-07-01

    In 2007, China firmly established itself as the driver of the global methanol industry. The country became the world's largest methanol producer and consumer. The development of the methanol industry and methanol fuel in China is reviewed in this article. China is rich in coal but is short on oil and natural gas; unfortunately, transportation development will need more and more oil to provide the fuel. Methanol is becoming a dominant alternative fuel. China is showing the rest of the world how cleaner transportation fuels can be made from coal.

  3. Biotechnological production of methanol from waste biomass

    SciTech Connect

    Kozak, R.; Morris, D.

    1995-12-01

    The production of methanol (CH{sub 3}OH) from waste biomass is possible through the use of genetically modified bacteria. The biomass to methanol conversion process makes use of a naturally occurring, direct aerobic enzymatic system referred to as oxidative demethylation. Methoxy groups are stripped off of lignin and lignin like plant substances (approximately fifty percent of all plant biomass) and hydrolyzed to form methanol. Since the biotech process is stoichiometric, potentially every methoxy group in the lignin feedstock can be converted to methanol fuel. Approximately 30-35% of lignin is a methoxy compound that can be converted. Biotechnological conversion could produce up to 100 gallons/ton or 20 billion gallons a year of methanol from waste biomass. Current work has focused on the genetic modification of the enzymatic conversion process to reach commercial production. The goals of this research are; increase product yields, implement an operon {open_quotes}switch{close_quotes} mechanism to exploit multiple feedstocks, and produce environmentally safe by-products. Progress on these topics will be reported.

  4. High-level direct-dynamics variational transition state theory calculations including multidimensional tunneling of the thermal rate constants, branching ratios, and kinetic isotope effects of the hydrogen abstraction reactions from methanol by atomic hydrogen.

    PubMed

    Meana-Pañeda, Rubén; Truhlar, Donald G; Fernández-Ramos, Antonio

    2011-03-07

    We report a detailed theoretical study of the hydrogen abstraction reaction from methanol by atomic hydrogen. The study includes the analysis of thermal rate constants, branching ratios, and kinetic isotope effects. Specifically, we have performed high-level computations at the MC3BB level together with direct dynamics calculations by canonical variational transition state theory (CVT) with the microcanonically optimized multidimensional tunneling (μOMT) transmission coefficient (CVT/μOMT) to study both the CH(3)OH+H→CH(2)OH+H(2) (R1) reaction and the CH(3)OH+H→CH(3)O+H(2) (R2) reaction. The CVT/μOMT calculations show that reaction R1 dominates in the whole range 298≤T (K)≤2500 and that anharmonic effects on the torsional mode about the C-O bond are important, mainly at high temperatures. The activation energy for the total reaction sum of R1 and R2 reactions changes substantially with temperature and, therefore, the use of straight-line Arrhenius plots is not valid. We recommend the use of new expressions for the total R1 + R2 reaction and for the R1 and R2 individual reactions.

  5. A novel organic/inorganic polymer membrane based on poly(vinyl alcohol)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid/3-glycidyloxypropyl trimethoxysilane polymer electrolyte membrane for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Lue, Shingjiang Jessie; Shih, Jeng-Ywan

    2011-05-01

    Poly(vinyl alcohol)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS)/3-glycidyloxypropyl)trimethoxysilane (PVA/PAMPS/GPTMS) organic/inorganic proton-conducting polymer membranes are prepared by a solution casting method. PAMPS is a polymeric acid commonly used as a primary proton donor, while 3-(glycidyloxypropyl)trimethoxysilane (GPTMS) is an inorganic precursor forming a semi-interpenetrating network (SIPN). Varying amounts of sulfosuccinic acid (SSA) are used as the cross-linker and secondary proton source. The characteristic properties of PVA/PAMPS/GPTMS composite membranes are investigated by thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), micro-Raman spectroscopy and the AC impedance method. Direct methanol fuel cells (DMFCs) made of PVA/PAMPS/GPTMS composite membranes are assembled and examined. Experimental results indicate that DMFCs employing an inexpensive, non-perfluorinated, organic/inorganic SIPN membrane achieve good electrochemical performance. The highest peak power density of a DMFC using PVA/PAMPS/GPTMS composite membrane with 2 M CH3OH solution fuel at ambient temperature is 23.63 mW cm-2. The proposed organic/inorganic proton-conducting membrane based on PVA/PAMPS/GPTMS appears to be a viable candidate for future DMFC applications.

  6. Eucomic acid methanol monosolvate

    PubMed Central

    Li, Guo-Qiang; Li, Yao-Lan; Wang, Guo-Cai; Liang, Zhi-Hong; Jiang, Ren-Wang

    2011-01-01

    In the crystal structure of the title compound [systematic name: 2-hy­droxy-2-(4-hy­droxy­benz­yl)butane­dioic acid methanol monosolvate], C11H12O6·CH3OH, the dihedral angles between the planes of the carboxyl groups and the benzene ring are 51.23 (9) and 87.97 (9)°. Inter­molecular O—H⋯O hydrogen-bonding inter­actions involving the hy­droxy and carb­oxy­lic acid groups and the methanol solvent mol­ecule give a three-dimensional structure. PMID:22091200

  7. Formation and spectra of clathrate hydrates of methanol and methanol-ether mixtures

    NASA Astrophysics Data System (ADS)

    Williams, Kenneth Dixon; Devlin, J. Paul

    1997-10-01

    Infrared spectra of mixed clathrate hydrates, with either ethylene oxide (EO) or tetrahydrofuran (THF) and methanol molecules as the guest species, have been obtained from thin films prepared by vapor deposition of D 2O mixtures in the 115-130 K range. Although methanol acts as a suppressant to the direct vapor deposition of a type I clathrate with EO, nearly complete conversion of 115 K amorphous codeposits, to the crystalline mixed clathrate, occurs upon warming near 150 K. By contrast, the type II clathrate of THF shows an increased crystalline quality when methanol is included in the vapor deposits of the mixed clathrate hydrate at 130 K. The observation of the OD stretch-mode band of weakly bonded CD 3OD near 2575 cm -1 is part of the evidence that the methanol molecules are encaged. However, as shown theoretically by Tanaka, the clathrate hydrates of methanol, even when mixed with an ether help gas, are not stable structures but form at low temperatures because of kinetic factors, only to decompose in the 140-160 K range. Attempts to prepare a simple type I or type II clathrate hydrate of methanol have produced mixed results. Limited amounts of clathrate hydrate form during deposition but annealing does not result in complete conversion to crystalline clathrates, particularly for host : guest ratios of 17 : 1.

  8. The toxicity of methanol

    SciTech Connect

    Tephly, T.R. )

    1991-01-01

    Methanol toxicity in humans and monkeys is characterized by a latent period of many hours followed by a metabolic acidosis and ocular toxicity. This is not observed in most lower animals. The metabolic acidosis and blindness is apparently due to formic acid accumulation in humans and monkeys, a feature not seen in lower animals. The accumulation of formate is due to a deficiency in formate metabolism which is, in turn, related, in part, to low hepatic tetrahydrofolate (H{sub 4}folate). An excellent correlation between hepatic H{sub 4} folate and formate oxidation rates has been shown within and across species. Thus, humans and monkeys possess low hepatic H{sub 4}folate levels, low rates of formate oxidation and accumulation of formate after methanol. Formate, itself, produces blindness in monkeys in the absence of metabolic acidosis. In addition to low hepatic H{sub 4}folate concentrations, monkeys and humans also have low hepatic 10-formyl H{sub 4}folate dehydrogenase levels, the enzyme which is the ultimate catalyst for conversion of formate to carbon dioxide. This review presents the basis for the role of folic acid-dependent reactions in the regulation of methanol toxicity.

  9. California methanol assessment. Volume 2: Technical report

    NASA Technical Reports Server (NTRS)

    Otoole, R.; Dutzi, E.; Gershman, R.; Heft, R.; Kalema, W.; Maynard, D.

    1983-01-01

    Energy feedstock sources for methanol; methanol and other synfuels; transport, storage, and distribution; air quality impact of methanol use in vehicles, chemical methanol production and use; methanol utilization in vehicles; methanol utilization in stationary applications; and environmental and regulatory constraints are discussed.

  10. Toward a miniaturized fundus camera.

    PubMed

    Gliss, Christine; Parel, Jean-Marie; Flynn, John T; Pratisto, Hans; Niederer, Peter

    2004-01-01

    Retinopathy of prematurity (ROP) describes a pathological development of the retina in prematurely born children. In order to prevent severe permanent damage to the eye and enable timely treatment, the fundus of the eye in such children has to be examined according to established procedures. For these examinations, our miniaturized fundus camera is intended to allow the acquisition of wide-angle digital pictures of the fundus for on-line or off-line diagnosis and documentation. We designed two prototypes of a miniaturized fundus camera, one with graded refractive index (GRIN)-based optics, the other with conventional optics. Two different modes of illumination were compared: transscleral and transpupillary. In both systems, the size and weight of the camera were minimized. The prototypes were tested on young rabbits. The experiments led to the conclusion that the combination of conventional optics with transpupillary illumination yields the best results in terms of overall image quality.

  11. Miniature x-ray source

    DOEpatents

    Trebes, James E.; Stone, Gary F.; Bell, Perry M.; Robinson, Ronald B.; Chornenky, Victor I.

    2002-01-01

    A miniature x-ray source capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature x-ray source comprises a compact vacuum tube assembly containing a cathode, an anode, a high voltage feedthru for delivering high voltage to the anode, a getter for maintaining high vacuum, a connection for an initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is highly x-ray transparent and made, for example, from boron nitride. The compact size and potential for remote operation allows the x-ray source, for example, to be placed adjacent to a material sample undergoing analysis or in proximity to the region to be treated for medical applications.

  12. Organic photodiodes for biosensor miniaturization.

    PubMed

    Wojciechowski, Jason R; Shriver-Lake, Lisa C; Yamaguchi, Mariko Y; Füreder, Erwin; Pieler, Roland; Schamesberger, Martin; Winder, Christoph; Prall, Hans Jürgen; Sonnleitner, Max; Ligler, Frances S

    2009-05-01

    Biosensors have successfully demonstrated the capability to detect multiple pathogens simultaneously at very low levels. Miniaturization of biosensors is essential for use in the field or at the point of care. While microfluidic systems reduce the footprint for biochemical processing devices and electronic components are continually becoming smaller, optical components suitable for integration--such as LEDs and CMOS chips--are generally still too expensive for disposable components. This paper describes the integration of polymer diodes onto a biosensor chip to create a disposable device that includes both the detector and the sensing surface coated with immobilized capture antibody. We performed a chemiluminescence immunoassay on the OPD substrate and measured the results using a hand-held reader attached to a laptop computer. The miniaturized biosensor with the disposable slide including the organic photodiode detected Staphylococcal enterotoxin B at concentrations as low as 0.5 ng/mL.

  13. Miniature x-ray source

    DOEpatents

    Trebes, James E.; Bell, Perry M.; Robinson, Ronald B.

    2000-01-01

    A miniature x-ray source utilizing a hot filament cathode. The source has a millimeter scale size and is capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature source consists of a compact vacuum tube assembly containing the hot filament cathode, an anode, a high voltage feedthru for delivering high voltage to the cathode, a getter for maintaining high vacuum, a connector for initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is fabricated from highly x-ray transparent materials, such as sapphire, diamond, or boron nitride.

  14. Portable direct methanol fuel cell systems

    NASA Technical Reports Server (NTRS)

    Narayanan, S. R.; Valdez, T. I.

    2002-01-01

    This article includes discussion of the specific power and power density requirements for various portable system applications, the status of stack technology, progress in the implementation of balance-of-plant designs, and a summary of the characteristics of various DMFC portable power source demonstrations.

  15. Aerosol feed direct methanol fuel cell

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew (Inventor); Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor)

    2002-01-01

    Improvements to fuel cells include introduction of the fuel as an aerosol of liquid fuel droplets suspended in a gas. The particle size of the liquid fuel droplets may be controlled for optimal fuel cell performance by selection of different aerosol generators or by separating droplets based upon size using a particle size conditioner.

  16. Miniaturized pressurization system

    DOEpatents

    Whitehead, John C.; Swink, Don G.

    1991-01-01

    The invention uses a fluid stored at a low pressure and provides the fluid at a high pressure. The invention allows the low pressure fluid to flow to a fluid bore of a differential pump and from the pump to a fluid pressure regulator. After flowing through the regulator the fluid is converted to a gas which is directed to a gas bore of the differential pump. By controlling the flow of gas entering and being exhausted from the gas bore, the invention provides pressure to the fluid. By setting the regulator, the high pressure fluid can be set at predetermined values. Because the invention only needs a low pressure fluid, the inventive apparatus has a low mass, and therefore would be useful in rocket propulsion systems.

  17. Organic Photodiodes for Biosensor Miniaturization

    DTIC Science & Technology

    2009-01-01

    1 pW/mm2. Using this system, sandwich immunoassays were performed on the OPD substrate for detection of Staphylococcal enterotoxin B (SEB). Results...demonstrated the capability to detect multiple pathogens simultaneously at very low levels. Miniaturization of biosensors is essential for use in the field or...the sensing surface coated with immobilized capture antibody. We performed a chemiluminescence immunoassay on the OPD substrate and measured the results

  18. Neuromuscular Functions on Experimental Acute Methanol Intoxication

    PubMed Central

    Moral, Ali Reşat; Çankayalı, İlkin; Sergin, Demet; Boyacılar, Özden

    2015-01-01

    Objective The incidence of accidental or suicidal ingestion of methyl alcohol is high and methyl alcohol intoxication has high mortality. Methyl alcohol intoxication causes severe neurological sequelae and appears to be a significant problem. Methyl alcohol causes acute metabolic acidosis, optic neuropathy leading to permanent blindness, respiratory failure, circulatory failure and death. It is metabolised in the liver, and its metabolite formic acid has direct toxic effects, causing oxidative stress, mitochondrial damage and increased lipid peroxidation associated with the mechanism of neurotoxicity. Methanol is known to cause acute toxicity of the central nervous system; however, the effects on peripheral neuromuscular transmission are unknown. In our study, we aimed to investigate the electrophysiological effects of experimentally induced acute methanol intoxication on neuromuscular transmission in the early period (first 24 h). Methods After approval by the Animal Experiment Ethics Committee of Ege University, the study was carried out on 10 Wistar rats, each weighing about 200 g. During electrophysiological recordings and orogastric tube insertion, the rats were anaesthetised using intra-peritoneal (IP) injection of ketamine 100 mg kg−1 and IP injection of xylazine 10 mg kg−1. The rats were given 3 g kg−1 methyl alcohol by the orogastric tube. Electrophysiological measurements from the gastrocnemius muscle were compared with baseline. Results Latency measurements before and 24 h after methanol injection were 0.81±0.11 ms and 0.76±0.12 ms, respectively. CMAP amplitude measurements before and 24 h after methanol injection were 9.85±0.98 mV and 9.99±0.40 mV, respectively. CMAP duration measurements before and 24 h after methanol injection were 9.86±0.03 ms and 9.86±0.045 ms, respectively. Conclusion It was concluded that experimental methanol intoxication in the acute phase (first 24 h) did not affect neuromuscular function. PMID:27366524

  19. Miniature Laser Tracker

    DOEpatents

    Vann, Charles S.

    2003-09-09

    This small, inexpensive, non-contact laser sensor can detect the location of a retroreflective target in a relatively large volume and up to six degrees of position. The tracker's laser beam is formed into a plane of light which is swept across the space of interest. When the beam illuminates the retroreflector, some of the light returns to the tracker. The intensity, angle, and time of the return beam is measured to calculate the three dimensional location of the target. With three retroreflectors on the target, the locations of three points on the target are measured, enabling the calculation of all six degrees of target position. Until now, devices for three-dimensional tracking of objects in a large volume have been heavy, large, and very expensive. Because of the simplicity and unique characteristics of this tracker, it is capable of three-dimensional tracking of one to several objects in a large volume, yet it is compact, light-weight, and relatively inexpensive. Alternatively, a tracker produces a diverging laser beam which is directed towards a fixed position, and senses when a retroreflective target enters the fixed field of view. An optically bar coded target can be read by the tracker to provide information about the target. The target can be formed of a ball lens with a bar code on one end. As the target moves through the field, the ball lens causes the laser beam to scan across the bar code.

  20. Portable, miniaturized, fibre delivered, multimodal CARS exoscope.

    PubMed

    Smith, Brett; Naji, Majid; Murugkar, Sangeeta; Alarcon, Emilio; Brideau, Craig; Stys, Peter; Anis, Hanan

    2013-07-15

    We demonstrate for the first time, a portable multimodal coherent anti-Stokes Raman scattering microscope (exoscope) for minimally invasive in-vivo imaging of tissues. This device is based around a micro-electromechanical system scanning mirror and miniaturized optics with light delivery accomplished by a photonic crystal fibre. A single Ti:sapphire femtosecond pulsed laser is used as the light source to produce CARS, two photon excitation fluorescence and second harmonic generation images. The high resolution and distortion-free images obtained from various resolution and bio-samples, particularly in backward direction (epi) successfully demonstrate proof of concept, and pave the path towards future non or minimally-invasive in vivo imaging.

  1. Methanol-Air Batteries.

    DTIC Science & Technology

    1977-01-01

    Cells charged with 120 ml of anolyte , consisting of 6 M methanol in 11 M KOH, have operated for 2,230 hours under cyclic load drains of 50 mA for 13...minutes and 2 A for 1 second. One cell operated for more than 8,000 hours with periodic refilling of fresh anolyte , demonstrating the long serviceable...life of the electrode components. Fuel utilization efficiencies as high as 84% have been obtained from cells charged with an anolyte solution of

  2. Environmental controls over methanol emission from leaves

    NASA Astrophysics Data System (ADS)

    Harley, P.; Greenberg, J.; Niinemets, É.; Guenther, A.

    2007-12-01

    Methanol is found throughout the troposphere, with average concentrations second only to methane among atmospheric hydrocarbons. Proposed global methanol budgets are highly uncertain, but all agree that at least 60% of the total source arises from the terrestrial biosphere and primary emissions from plants. However, the magnitude of these emissions is also highly uncertain, and the environmental factors which control them require further elucidation. Using a temperature-controlled leaf enclosure, we measured methanol emissions from leaves of six plant species by proton transfer reaction mass spectrometry, with simultaneous measurements of leaf evapotranspiration and stomatal conductance. Rates of emission at 30°C varied from 0.2 to 38 μg g (dry mass)-1 h-1, with higher rates measured on young leaves, consistent with the production of methanol via pectin demethylation in expanding foliage. On average, emissions increased by a factor of 2.3 for each 10°C increase in leaf temperature. At constant temperature, emissions were also correlated with co-varying incident photosynthetic photon flux density and rates of stomatal conductance. The data were analyzed using the emission model developed by Niinemets and Reichstein (2003a, b), with the incorporation of a methanol production term that increased exponentially with temperature. It was concluded that control of emissions, during daytime, was shared by leaf temperature and stomatal conductance, although rates of production may also vary diurnally in response to variations in leaf growth rate in expanding leaves. The model, which generally provided reasonable simulations of the measured data during the day, significantly overestimated emissions on two sets of measurements made through the night, suggesting that production rates of methanol were reduced at night, perhaps because leaf growth was reduced or possibly through a direct effect of light on production. Although the short-term dynamics of methanol emissions can

  3. Miniaturization in x ray and gamma ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Iwanczyk, Jan S.; Wang, Yuzhong J.; Bradley, James G.

    1993-01-01

    The paper presents advances in two new sensor technologies and a miniaturized associated electronics technology which, when combined, can allow for very significant miniaturization and for the reduction of weight and power consumption in x-ray and gamma-ray spectroscopy systems: (1) Mercuric iodide (HgI2) x-ray technology, which allows for the first time the construction of truly portable, high-energy resolution, non-cryogenic x-ray fluorescence (XRF) elemental analyzer systems, with parameters approaching those of laboratory quality cryogenic instruments; (2) the silicon avalanche photodiode (APD), which is a solid-state light sensitive device with internal amplification, capable of uniquely replacing the vacuum photomultiplier tube in scintillation gamma-ray spectrometer applications, and offering substantial improvements in size, ruggedness, low power operation and energy resolution; and (3) miniaturized (hybridized) low noise, low power amplification and processing electronics, which take full advantage of the favorable properties of these new sensors and allow for the design and fabrication of advanced, highly miniaturized x-ray and gamma-ray spectroscopy systems. The paper also presents experimental results and examples of spectrometric systems currently under construction. The directions for future developments are discussed.

  4. Miniaturization of flight deflection measurement system

    NASA Technical Reports Server (NTRS)

    Fodale, Robert (Inventor); Hampton, Herbert R. (Inventor)

    1990-01-01

    A flight deflection measurement system is disclosed including a hybrid microchip of a receiver/decoder. The hybrid microchip decoder is mounted piggy back on the miniaturized receiver and forms an integral unit therewith. The flight deflection measurement system employing the miniaturized receiver/decoder can be used in a wind tunnel. In particular, the miniaturized receiver/decoder can be employed in a spin measurement system due to its small size and can retain already established control surface actuation functions.

  5. Transport of methanol by pipeline

    SciTech Connect

    Not Available

    1985-04-01

    This report examines and evaluates the problems and considerations that could affect the feasibility of transporting methanol by pipeline. The following are the major conclusions: Though technical problems, such as methanol water contamination and materials incompatibility, remain to be solved, none appears insolvable. Methanol appears to be less toxic, and therefore to represent less of a health hazard, than gasoline, the fuel for which methanol is expected to substitute. The primary safety hazards of methanol, fire and explosion, are no worse than those of gasoline. The environmental hazards that can be associated with methanol are not as significant as those of petroleum. Provided quantities of throughput sufficient to justify pipeline transport are available, there appear to be no economic impediments to the transport of methanol by pipeline. Based on these, it appears that it can be concluded that the pipelining of methanol, whether via an existing petroleum pipeline or a new methanol-dedicated pipeline, is indeed feasible. 66 refs., 3 figs., 27 tabs.

  6. Methanol and acetaldehyde fluxes over ryegrass

    NASA Astrophysics Data System (ADS)

    Custer, Thomas; Schade, Gunnar

    2007-09-01

    Oxygenated volatile organic compounds (OVOCs) play an active role in tropospheric chemistry but our knowledge concerning their release and ultimate fate is limited. However, the recent introduction of Proton Transfer Reaction Mass Spectrometry (PTRMS) has improved our capability to make direct field observations of OVOC mixing ratios and fluxes. We used PTRMS in an eddy covariance setup to measure selected OVOC exchange rates above a well-characterized agricultural plot in Northern Germany. In fall 2003, mixing ratios of methanol and acetaldehyde 2 m above the field ranged from 1 to 10 and 0.4 to 2.1 ppb, respectively, well correlated with one another. Fluxes of both gases were followed for growing Italian ryegrass (Lolium multiflorum) over a significant portion of its life cycle. Diurnally fluctuating emissions of methanol and very small acetaldehyde fluxes were observed up to the cutting and removal of the grass. Methanol emissions were exponentially related to ambient temperatures and appeared to be higher during the grass' rapid leaf area expansion and after a rain event. Acetaldehyde exchanges averaged over the whole period indicated very slow deposition. Our measurements confirm previous, similar results, as well as presumptions that grasses are comparatively low methanol emitters compared to non-grass species.

  7. Personal miniature electrophysiological tape recorder

    NASA Technical Reports Server (NTRS)

    Green, H.

    1981-01-01

    The use of a personal miniature electrophysiological tape recorder to measure the physiological reactions of space flight personnel to space flight stress and weightlessness is described. The Oxford Instruments Medilog recorder, a battery-powered, four-channel cassette tape recorder with 24 hour endurance is carried on the person and will record EKG, EOG, EEG, and timing and event markers. The data will give information about heart rate and morphology changes, and document adaptation to zero gravity on the part of subjects who, unlike highly trained astronauts, are more representative of the normal population than were the subjects of previous space flight studies.

  8. Personal miniature electrophysiological tape recorder

    NASA Astrophysics Data System (ADS)

    Green, H.

    1981-11-01

    The use of a personal miniature electrophysiological tape recorder to measure the physiological reactions of space flight personnel to space flight stress and weightlessness is described. The Oxford Instruments Medilog recorder, a battery-powered, four-channel cassette tape recorder with 24 hour endurance is carried on the person and will record EKG, EOG, EEG, and timing and event markers. The data will give information about heart rate and morphology changes, and document adaptation to zero gravity on the part of subjects who, unlike highly trained astronauts, are more representative of the normal population than were the subjects of previous space flight studies.

  9. Miniature Autonomous Robotic Vehicle (MARV)

    SciTech Connect

    Feddema, J.T.; Kwok, K.S.; Driessen, B.J.; Spletzer, B.L.; Weber, T.M.

    1996-12-31

    Sandia National Laboratories (SNL) has recently developed a 16 cm{sup 3} (1 in{sup 3}) autonomous robotic vehicle which is capable of tracking a single conducting wire carrying a 96 kHz signal. This vehicle was developed to assess the limiting factors in using commercial technology to build miniature autonomous vehicles. Particular attention was paid to the design of the control system to search out the wire, track it, and recover if the wire was lost. This paper describes the test vehicle and the control analysis. Presented in the paper are the vehicle model, control laws, a stability analysis, simulation studies and experimental results.

  10. 33 CFR 13.01-40 - Miniature medals and bars.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... GENERAL DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-40 Miniature medals and bars. (a) Miniature Gold and Silver Lifesaving Medals and bars...

  11. 33 CFR 13.01-40 - Miniature medals and bars.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... GENERAL DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-40 Miniature medals and bars. (a) Miniature Gold and Silver Lifesaving Medals and bars...

  12. 33 CFR 13.01-40 - Miniature medals and bars.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... GENERAL DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-40 Miniature medals and bars. (a) Miniature Gold and Silver Lifesaving Medals and bars...

  13. 33 CFR 13.01-40 - Miniature medals and bars.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... GENERAL DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-40 Miniature medals and bars. (a) Miniature Gold and Silver Lifesaving Medals and bars...

  14. 33 CFR 13.01-40 - Miniature medals and bars.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... GENERAL DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-40 Miniature medals and bars. (a) Miniature Gold and Silver Lifesaving Medals and bars...

  15. Lightweight, Miniature Inertial Measurement System

    NASA Technical Reports Server (NTRS)

    Tang, Liang; Crassidis, Agamemnon

    2012-01-01

    A miniature, lighter-weight, and highly accurate inertial navigation system (INS) is coupled with GPS receivers to provide stable and highly accurate positioning, attitude, and inertial measurements while being subjected to highly dynamic maneuvers. In contrast to conventional methods that use extensive, groundbased, real-time tracking and control units that are expensive, large, and require excessive amounts of power to operate, this method focuses on the development of an estimator that makes use of a low-cost, miniature accelerometer array fused with traditional measurement systems and GPS. Through the use of a position tracking estimation algorithm, onboard accelerometers are numerically integrated and transformed using attitude information to obtain an estimate of position in the inertial frame. Position and velocity estimates are subject to drift due to accelerometer sensor bias and high vibration over time, and so require the integration with GPS information using a Kalman filter to provide highly accurate and reliable inertial tracking estimations. The method implemented here uses the local gravitational field vector. Upon determining the location of the local gravitational field vector relative to two consecutive sensors, the orientation of the device may then be estimated, and the attitude determined. Improved attitude estimates further enhance the inertial position estimates. The device can be powered either by batteries, or by the power source onboard its target platforms. A DB9 port provides the I/O to external systems, and the device is designed to be mounted in a waterproof case for all-weather conditions.

  16. Miniaturized neural interfaces and implants

    NASA Astrophysics Data System (ADS)

    Stieglitz, Thomas; Boretius, Tim; Ordonez, Juan; Hassler, Christina; Henle, Christian; Meier, Wolfgang; Plachta, Dennis T. T.; Schuettler, Martin

    2012-03-01

    Neural prostheses are technical systems that interface nerves to treat the symptoms of neurological diseases and to restore sensory of motor functions of the body. Success stories have been written with the cochlear implant to restore hearing, with spinal cord stimulators to treat chronic pain as well as urge incontinence, and with deep brain stimulators in patients suffering from Parkinson's disease. Highly complex neural implants for novel medical applications can be miniaturized either by means of precision mechanics technologies using known and established materials for electrodes, cables, and hermetic packages or by applying microsystems technologies. Examples for both approaches will be introduced and discussed. Electrode arrays for recording of electrocorticograms during presurgical epilepsy diagnosis have been manufactured using approved materials and a marking laser to achieve an integration density that is adequate in the context of brain machine interfaces, e.g. on the motor cortex. Microtechnologies have to be used for further miniaturization to develop polymer-based flexible and light weighted electrode arrays to interface the peripheral and central nervous system. Polyimide as substrate and insulation material will be discussed as well as several application examples for nerve interfaces like cuffs, filament like electrodes and large arrays for subdural implantation.

  17. OTEC energy via methanol production

    SciTech Connect

    Avery, W.H.; Richards, D.; Niemeyer, W.G.; Shoemaker, J.D.

    1983-01-01

    The conceptual design of an 160 MW/sub e/ OTEC plantship has been documented; it is designed to produce 1000 tonne/day of fuel-grade methanol from coal slurry shipped to the plantship, using oxygen and hydrogen from the on-board electrolysis of water. Data and components are used that were derived by Brown and Root Development, Inc. (BARDI) in designing a barge-mounted plant to make methanol from natural gas for Litton Industries and in the design and construction of a coal-to-ammonia demonstration plant in operation at Muscle Shoals, Alabama, for the Tennessee Valley Authority (TVA). The OTEC-methanol plant design is based on the use of the Texaco gasifier and Lurgi synthesis units. The sale price of OTEC methanol delivered to port from this first-of-a-kind plant is estimated to be marginally competitive with methanol from other sources at current market prices.

  18. Scaffoldless engineered enzyme assembly for enhanced methanol utilization

    DOE PAGES

    Price, J. Vincent; Chen, Long; Whitaker, W. Brian; ...

    2016-10-24

    Methanol is an important feedstock derived from natural gas and can be chemically converted into commodity and specialty chemicals at high pressure and temperature. Although biological conversion of methanol can proceed at ambient conditions, there is a dearth of engineered microorganisms that use methanol to produce metabolites. In nature, methanol dehydrogenase (Mdh), which converts methanol to formaldehyde, highly favors the reverse reaction. Thus, efficient coupling with the irreversible sequestration of formaldehyde by 3-hexulose-6-phosphate synthase (Hps) and 6-phospho-3-hexuloseisomerase (Phi) serves as the key driving force to pull the pathway equilibrium toward central metabolism. An emerging strategy to promote efficient substrate channelingmore » is to spatially organize pathway enzymes in an engineered assembly to provide kinetic driving forces that promote carbon flux in a desirable direction. Here, we report a scaffoldless, self-assembly strategy to organize Mdh, Hps, and Phi into an engineered supramolecular enzyme complex using an SH3–ligand interaction pair, which enhances methanol conversion to fructose-6-phosphate (F6P). To increase methanol consumption, an “NADH Sink” was created using Escherichia coli lactate dehydrogenase as an NADH scavenger, thereby preventing reversible formaldehyde reduction. Combination of the two strategies improved in vitro F6P production by 97-fold compared with unassembled enzymes. The beneficial effect of supramolecular enzyme assembly was also realized in vivo as the engineered enzyme assembly improved whole-cell methanol consumption rate by ninefold. This approach will ultimately allow direct coupling of enhanced F6P synthesis with other metabolic engineering strategies for the production of many desired metabolites from methanol.« less

  19. Scaffoldless engineered enzyme assembly for enhanced methanol utilization.

    PubMed

    Price, J Vincent; Chen, Long; Whitaker, W Brian; Papoutsakis, Eleftherios; Chen, Wilfred

    2016-10-24

    Methanol is an important feedstock derived from natural gas and can be chemically converted into commodity and specialty chemicals at high pressure and temperature. Although biological conversion of methanol can proceed at ambient conditions, there is a dearth of engineered microorganisms that use methanol to produce metabolites. In nature, methanol dehydrogenase (Mdh), which converts methanol to formaldehyde, highly favors the reverse reaction. Thus, efficient coupling with the irreversible sequestration of formaldehyde by 3-hexulose-6-phosphate synthase (Hps) and 6-phospho-3-hexuloseisomerase (Phi) serves as the key driving force to pull the pathway equilibrium toward central metabolism. An emerging strategy to promote efficient substrate channeling is to spatially organize pathway enzymes in an engineered assembly to provide kinetic driving forces that promote carbon flux in a desirable direction. Here, we report a scaffoldless, self-assembly strategy to organize Mdh, Hps, and Phi into an engineered supramolecular enzyme complex using an SH3-ligand interaction pair, which enhances methanol conversion to fructose-6-phosphate (F6P). To increase methanol consumption, an "NADH Sink" was created using Escherichia coli lactate dehydrogenase as an NADH scavenger, thereby preventing reversible formaldehyde reduction. Combination of the two strategies improved in vitro F6P production by 97-fold compared with unassembled enzymes. The beneficial effect of supramolecular enzyme assembly was also realized in vivo as the engineered enzyme assembly improved whole-cell methanol consumption rate by ninefold. This approach will ultimately allow direct coupling of enhanced F6P synthesis with other metabolic engineering strategies for the production of many desired metabolites from methanol.

  20. Environmental study of miniature slip rings

    NASA Technical Reports Server (NTRS)

    Radnik, J. L.

    1967-01-01

    Investigation studied the long term operation of miniature slip ring assembles in high vacuum of space and included the influence of ring, brush, and insulator materials on electrical noise and mechanical wear. Results show that soft metal vapor plating and niobium diselenide miniature slip rings are beneficial.

  1. Anthrax vaccine associated deaths in miniature horses.

    PubMed

    Wobeser, Bruce K

    2015-04-01

    During a widespread anthrax outbreak in Canada, miniature horses were vaccinated using a live spore anthrax vaccine. Several of these horses died from an apparent immune-mediated vasculitis temporally associated with this vaccination. During the course of the outbreak, other miniature horses from different regions with a similar vaccination history, clinical signs, and necropsy findings were found.

  2. Miniature reaction chamber and devices incorporating same

    DOEpatents

    Mathies, Richard A.; Woolley, Adam T.

    2000-10-17

    The present invention generally relates to miniaturized devices for carrying out and controlling chemical reactions and analyses. In particular, the present invention provides devices which have miniature temperature controlled reaction chambers for carrying out a variety of synthetic and diagnostic applications, such as PCR amplification, nucleic acid hybridization, chemical labeling, nucleic acid fragmentation and the like.

  3. California methanol assessment. Volume 1: Summary report

    NASA Technical Reports Server (NTRS)

    Otoole, R.; Dutzi, E.; Gershman, R.; Heft, R.; Kalema, W.; Maynard, D.

    1983-01-01

    The near term methanol industry, the competitive environment, long term methanol market, the transition period, air quality impacts of methanol, roles of the public and private sectors are considered.

  4. Regulation of intracellular formaldehyde toxicity during methanol metabolism of the methylotrophic yeast Pichia methanolica.

    PubMed

    Wakayama, Keishi; Yamaguchi, Sakiko; Takeuchi, Akihito; Mizumura, Tasuku; Ozawa, Shotaro; Tomizuka, Noboru; Hayakawa, Takashi; Nakagawa, Tomoyuki

    2016-11-01

    In this study we found that the methylotrophic yeast Pichia methanolica showed impaired growth on high methanol medium (>5%, or 1.56 M, methanol). In contrast, P. methanolica grew well on glucose medium containing 5% methanol, but the growth defects reappeared on glucose medium supplemented with 5 mM formaldehyde. During methanol growth of P. methanolica, formaldehyde accumulated in the medium up to 0.3 mM before it was consumed rapidly based on cell growth. These findings indicate that the growth defect of P. methanolica on high methanol media is not caused directly by methanol toxicity, but rather by formaldehyde, which is a key toxic intermediate of methanol metabolism. Moreover, during methanol growth of P. methanolica, expression of enzymes in the methanol-oxidation pathway were induced before the alcohol oxidase isozymes Mod1p and Mod2p, and Mod1p expression was induced before Mod2p. These results suggest that to avoid excess accumulation of formaldehyde-the toxic intermediate of methanol metabolism-P. methanolica grown on methanol strictly regulates the order in which methanol-metabolizing enzymes are expressed.

  5. Advances in Miniaturized Instruments for Genomics

    PubMed Central

    2014-01-01

    In recent years, a lot of demonstrations of the miniaturized instruments were reported for genomic applications. They provided the advantages of miniaturization, automation, sensitivity, and specificity for the development of point-of-care diagnostics. The aim of this paper is to report on recent developments on miniaturized instruments for genomic applications. Based on the mature development of microfabrication, microfluidic systems have been demonstrated for various genomic detections. Since one of the objectives of miniaturized instruments is for the development of point-of-care device, impedimetric detection is found to be a promising technique for this purpose. An in-depth discussion of the impedimetric circuits and systems will be included to provide total consideration of the miniaturized instruments and their potential application towards real-time portable imaging in the “-omics” era. The current excellent demonstrations suggest a solid foundation for the development of practical and widespread point-of-care genomic diagnostic devices. PMID:25114919

  6. Methanol Uptake by Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, L. T.; Essin, A. M.; Golden, D. M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The global methanol budget is currently unbalanced, with source terms significantly larger than the sinks terms. To evaluate possible losses of gaseous methanol to sulfate aerosols, the solubility and reactivity of methanol in aqueous sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosols is under investigation. Methanol will partition into sulfate aerosols according to its Henry's law solubility. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H*, for cold (196 - 220 K) solutions ranging between 45 and 70 wt % H2SO4. We have found that methanol solubility ranges from approx. 10(exp 5) - 10(exp 7) M/atm for UT/LS conditions. Solubility increases with decreasing temperature and with increasing sulfuric acid content. Although methanol is slightly more soluble than are acetone and formaldehyde, current data indicate that uptake by clean aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These solubility measurements include uptake due to physical solvation and any rapid equilibria which are established in solution. Reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H is not significant over our experimental time scale for solutions below 80 wt % H2SO4. To confirm this directly, results obtained using a complementary equilibrium measurement technique will also be presented.

  7. Atmospheric deposition of methanol over the Atlantic Ocean.

    PubMed

    Yang, Mingxi; Nightingale, Philip D; Beale, Rachael; Liss, Peter S; Blomquist, Byron; Fairall, Christopher

    2013-12-10

    In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air-sea methanol transfer along a ∼10,000-km north-south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air-sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface-an important term for improving air-sea gas exchange models.

  8. Platinum Nickel Nanowires as Methanol Oxidation Electrocatalysts

    DOE PAGES

    Alia, Shaun M.; Pylypenko, Svitlana; Neyerlin, Kenneth C.; ...

    2015-08-27

    We investigated platinum(Pt) nickel (Ni) nanowires (PtNiNWs) as methanol oxidation reaction (MOR) catalysts in rotating disk electrode (RDE) half-cells under acidic conditions. Pt-ruthenium (Ru) nanoparticles have long been the state of the art MOR catalyst for direct methanol fuel cells (DMFCs) where Ru provides oxophilic sites, lowering the potential for carbon monoxide oxidation and the MOR onset. Ru, however, is a precious metal that has long term durability concerns. Ni/Ni oxide species offer a potential to replace Ru in MOR electrocatalysis. PtNiNWs were investigated for MOR and oxygen annealing was investigated as a route to improve catalyst performance (mass activitymore » 65% greater) and stability to potential cycling. Our results presented show that PtNiNWs offer significant promise in the area, but also result in Ni ion leaching that is a concern requiring further evaluation in fuel cells.« less

  9. Platinum Nickel Nanowires as Methanol Oxidation Electrocatalysts

    SciTech Connect

    Alia, Shaun M.; Pylypenko, Svitlana; Neyerlin, Kenneth C.; Kocha, Shyam S.; Pivovar, Bryan S.

    2015-08-27

    We investigated platinum(Pt) nickel (Ni) nanowires (PtNiNWs) as methanol oxidation reaction (MOR) catalysts in rotating disk electrode (RDE) half-cells under acidic conditions. Pt-ruthenium (Ru) nanoparticles have long been the state of the art MOR catalyst for direct methanol fuel cells (DMFCs) where Ru provides oxophilic sites, lowering the potential for carbon monoxide oxidation and the MOR onset. Ru, however, is a precious metal that has long term durability concerns. Ni/Ni oxide species offer a potential to replace Ru in MOR electrocatalysis. PtNiNWs were investigated for MOR and oxygen annealing was investigated as a route to improve catalyst performance (mass activity 65% greater) and stability to potential cycling. Our results presented show that PtNiNWs offer significant promise in the area, but also result in Ni ion leaching that is a concern requiring further evaluation in fuel cells.

  10. Miniature hybrid optical imaging lens

    DOEpatents

    Sitter, Jr., David N.; Simpson, Marc L.

    1997-01-01

    A miniature lens system that corrects for imaging and chromatic aberrations, the lens system being fabricated from primarily commercially-available components. A first element at the input to a lens housing is an aperture stop. A second optical element is a refractive element with a diffractive element closely coupled to, or formed a part of, the rear surface of the refractive element. Spaced closely to the diffractive element is a baffle to limit the area of the image, and this is closely followed by a second refractive lens element to provide the final correction. The image, corrected for aberrations exits the last lens element to impinge upon a detector plane were is positioned any desired detector array. The diffractive element is fabricated according to an equation that includes, as variables, the design wavelength, the index of refraction and the radius from an optical axis of the lens system components.

  11. Miniature hybrid optical imaging lens

    DOEpatents

    Sitter, D.N. Jr.; Simpson, M.L.

    1997-10-21

    A miniature lens system that corrects for imaging and chromatic aberrations is disclosed, the lens system being fabricated from primarily commercially-available components. A first element at the input to a lens housing is an aperture stop. A second optical element is a refractive element with a diffractive element closely coupled to, or formed a part of, the rear surface of the refractive element. Spaced closely to the diffractive element is a baffle to limit the area of the image, and this is closely followed by a second refractive lens element to provide the final correction. The image, corrected for aberrations exits the last lens element to impinge upon a detector plane were is positioned any desired detector array. The diffractive element is fabricated according to an equation that includes, as variables, the design wavelength, the index of refraction and the radius from an optical axis of the lens system components. 2 figs.

  12. Overview of the miniaturization technologies

    NASA Astrophysics Data System (ADS)

    Warrington, Robert O., Jr.

    1995-09-01

    This overview paper will cover the miniaturization technologies as applied to microelectromechanical systems (MEMS) or micromanufacturing. Technologies reviewed will include bulk and surface micromachining of silicon, the high-aspect ratio technologies including deep X-ray lithography (LIGA) and photo sensitive polyimide, and the complementary processes which include micro-drilling, milling, turning, and electrical discharge machining, laser based micromachining and focussed ion beam micromachining. Examples of each of the process technologies will be given and a capabilities comparison among the technologies will be presented. A historical comparison of MEMS with the vlsi industry will be made and the current status and market forecast for these technologies will be presented. A brief comparison of US research with current research in Japan and Europe will be made along with comments about the status of US research, including current research projects at the Institute for Micromanufacturing.

  13. Miniature laser ignited bellows motor

    NASA Technical Reports Server (NTRS)

    Renfro, Steven L.; Beckman, Tom M.

    1994-01-01

    A miniature optically ignited actuation device has been demonstrated using a laser diode as an ignition source. This pyrotechnic driven motor provides between 4 and 6 lbs of linear force across a 0.090 inch diameter surface. The physical envelope of the device is 1/2 inch long and 1/8 inch diameter. This unique application of optical energy can be used as a mechanical link in optical arming systems or other applications where low shock actuation is desired and space is limited. An analysis was performed to determine pyrotechnic materials suitable to actuate a bellows device constructed of aluminum or stainless steel. The aluminum bellows was chosen for further development and several candidate pyrotechnics were evaluated. The velocity profile and delivered force were quantified using an non-intrusive optical motion sensor.

  14. Miniature mechanical transfer optical coupler

    DOEpatents

    Abel, Philip [Overland Park, KS; Watterson, Carl [Kansas City, MO

    2011-02-15

    A miniature mechanical transfer (MT) optical coupler ("MMTOC") for optically connecting a first plurality of optical fibers with at least one other plurality of optical fibers. The MMTOC may comprise a beam splitting element, a plurality of collimating lenses, and a plurality of alignment elements. The MMTOC may optically couple a first plurality of fibers disposed in a plurality of ferrules of a first MT connector with a second plurality of fibers disposed in a plurality of ferrules of a second MT connector and a third plurality of fibers disposed in a plurality of ferrules of a third MT connector. The beam splitting element may allow a portion of each beam of light from the first plurality of fibers to pass through to the second plurality of fibers and simultaneously reflect another portion of each beam of light from the first plurality of fibers to the third plurality of fibers.

  15. Miniaturized digital holography sensor for distal three-dimensional endoscopy.

    PubMed

    Kolenovic, Ervin; Osten, Wolfgang; Klattenhoff, Reiner; Lai, Songcan; von Kopylow, Christoph; Jüptner, Werner

    2003-09-01

    A miniaturized sensor head for endoscopic measurements based on digital holography is described. The system was developed to measure the shape and the three-dimensional deformation of objects located at places to which there is no access by common measurement systems. A miniaturized optical sensor, including a complete digital holographic interferometer with a CCD camera, is placed at the end of a flexible endoscope. The diameter of the head is smaller than 10 mm. The system enables interferometric measurements to be made at speeds of as many as five reconstructions per second, and it can be used outside the laboratory under normal environmental conditions. Shape measurements are performed with two wavelengths for contouring, and the deformation is measured by digital holographic interferometry. To obtain full three-dimensional data in displacement measurements we illuminate the object sequentially from three different illumination directions. To increase the lateral resolution we use temporal phase shifting.

  16. Determining mechanical behavior of solid materials using miniature specimens

    DOEpatents

    Manahan, M.P.; Argon, A.S.; Harling, O.K.

    1986-02-04

    A Miniaturized Bend Test (MBT) capable of extracting and determining mechanical behavior information from specimens only so large as to have at least a volume or smallest dimension sufficient to satisfy continuum behavior in all directions is disclosed. The mechanical behavior of the material is determined from the measurements taken during the bending of the specimen and is processed according to the principles of linear or nonlinear material mechanics or both. In a preferred embodiment the determination is carried out by a code which is constructed according to the finite element method, and the specimen used for the determinations is a miniature disk simply supported for central loading at the axis on the center of the disk. 51 figs.

  17. The Responsivity of a Miniaturized Passive Implantable Wireless Pressure Sensor

    PubMed Central

    Jiang, Hao; Lan, Di; Goldman, Ken; Etemadi, Mozziyar; Shahnasser, Hamid; Roy, Shuvo

    2011-01-01

    A miniature batteryless implantable wireless pressure sensor that can be used deep inside the body is desired by the medical community. MEMS technology makes it possible to achieve high responsivity that directly determines the operating distance between a miniature implanted sensor and the external RF probe, while providing the read-out. In this paper, for the first time, an analytical expression of the system responsivity versus the sensor design is derived using an equivalent circuit model. Also, the integration of micro-coil inductors and pressure sensitive capacitors on a single silicon chip using MEMS fabrication techniques is demonstrated. Further, the derived analytical design theory is validated by the measured responsivity of these sensors. PMID:25309965

  18. Determining mechanical behavior of solid materials using miniature specimens

    DOEpatents

    Manahan, Michael P.; Argon, Ali S.; Harling, Otto K.

    1986-01-01

    A Miniaturized Bend Test (MBT) capable of extracting and determining mechanical behavior information from specimens only so large as to have at least a volume or smallest dimension sufficient to satisfy continuum behavior in all directions. The mechanical behavior of the material is determined from the measurements taken during the bending of the specimen and is processed according to the principles of linear or nonlinear material mechanics or both. In a preferred embodiment the determination is carried out by a code which is constructed according to the finite element method, and the specimen used for the determinations is a miniature disk simply supported for central loading at the axis on the center of the disk.

  19. Miniaturization of planar horn motors

    NASA Astrophysics Data System (ADS)

    Sherrit, Stewart; Ostlund, Patrick N.; Chang, Zensheu; Bao, Xiaoqi; Bar-Cohen, Yoseph; Widholm, Scott E.; Badescu, Mircea

    2012-04-01

    There is a great need for compact, efficient motors for driving various mechanisms including robots or mobility platforms. A study is currently underway to develop a new type of piezoelectric actuators with significantly more strength, low mass, small footprint, and efficiency. The actuators/motors utilize piezoelectric actuated horns which have a very high power density and high electromechanical conversion efficiency. The horns are fabricated using our recently developed novel pre-stress flexures that make them thermally stable and increases their coupling efficiency. The monolithic design and integrated flexures that pre-stresses the piezoelectric stack eliminates the use of a stress bolt. This design allows embedding solid-state motors and actuators in any structure so that the only macroscopically moving parts are the rotor or the linear translator. The developed actuator uses a stack/horn actuation and has a Barth motor configuration, which potentially generates very large torque and speeds that do not require gearing. Finite element modeling and design tools were investigated to determine the requirements and operation parameters and the results were used to design and fabricate a motor. This new design offers a highly promising actuation mechanism that can potentially be miniaturized and integrated into systems and structures. It can be configured in many shapes to operate as multi-degrees of freedom and multi-dimensional motors/actuators including unidirectional, bidirectional, 2D and 3D. In this manuscript, we are reporting the experimental measurements from a bench top design and the results from the efforts to miniaturize the design using 2×2×2 mm piezoelectric stacks integrated into thin plates that are of the order of 3 × 3 × 0.2 cm.

  20. Miniaturization of Planar Horn Motors

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Ostlund, Patrick N.; Chang, Zensheu; Bao, Xiaoqi; Bar-Cohen, Yoseph; Widholm, Scott E.; Badescu, Mircea

    2012-01-01

    There is a great need for compact, efficient motors for driving various mechanisms including robots or mobility platforms. A study is currently underway to develop a new type of piezoelectric actuators with significantly more strength, low mass, small footprint, and efficiency. The actuators/motors utilize piezoelectric actuated horns which have a very high power density and high electromechanical conversion efficiency. The horns are fabricated using our recently developed novel pre-stress flexures that make them thermally stable and increases their coupling efficiency. The monolithic design and integrated flexures that pre-stresses the piezoelectric stack eliminates the use of stress bolt. This design allows embedding solid-state motors and actuators in any structure so that the only macroscopically moving parts are the rotor or the linear translator. The developed actuator uses a stack/horn actuation and has a Barth motor configuration, which potentially generates very large torque and speeds that do not require gearing. Finite element modeling and design tools were investigated to determine the requirements and operation parameters and the results were used to design and fabricate a motor. This new design offers a highly promising actuation mechanism that can potentially be miniaturized and integrated into systems and structures. It can be configured in many shapes to operate as multi-degrees of freedom and multi-dimensional motors/actuators including unidirectional, bidirectional, 2D and 3D. In this manuscript, we are reporting the experimental measurements from a bench top design and the results from the efforts to miniaturize the design using 2x2x2 mm piezoelectric stacks integrated into thin plates that are of the order of3 x 3x 0.2 cm.

  1. Development of a miniaturized deformable mirror controller

    NASA Astrophysics Data System (ADS)

    Bendek, Eduardo; Lynch, Dana; Pluzhnik, Eugene; Belikov, Ruslan; Klamm, Benjamin; Hyde, Elizabeth; Mumm, Katherine

    2016-07-01

    High-Performance Adaptive Optics systems are rapidly spreading as useful applications in the fields of astronomy, ophthalmology, and telecommunications. This technology is critical to enable coronagraphic direct imaging of exoplanets utilized in ground-based telescopes and future space missions such as WFIRST, EXO-C, HabEx, and LUVOIR. We have developed a miniaturized Deformable Mirror controller to enable active optics on small space imaging mission. The system is based on the Boston Micromachines Corporation Kilo-DM, which is one of the most widespread DMs on the market. The system has three main components: The Deformable Mirror, the Driving Electronics, and the Mechanical and Heat management. The system is designed to be extremely compact and have lowpower consumption to enable its use not only on exoplanet missions, but also in a wide-range of applications that require precision optical systems, such as direct line-of-sight laser communications, and guidance systems. The controller is capable of handling 1,024 actuators with 220V maximum dynamic range, 16bit resolution, and 14bit accuracy, and operating at up to 1kHz frequency. The system fits in a 10x10x5cm volume, weighs less than 0.5kg, and consumes less than 8W. We have developed a turnkey solution reducing the risk for currently planned as well as future missions, lowering their cost by significantly reducing volume, weight and power consumption of the wavefront control hardware.

  2. Biological conversion of biogas to methanol using methanotrophs isolated from solid-state anaerobic digestate.

    PubMed

    Sheets, Johnathon P; Ge, Xumeng; Li, Yueh-Fen; Yu, Zhongtang; Li, Yebo

    2016-02-01

    The aim of this work was to isolate methanotrophs (methane oxidizing bacteria) that can directly convert biogas produced at a commercial anaerobic digestion (AD) facility to methanol. A methanotrophic bacterium was isolated from solid-state anaerobic digestate. The isolate had characteristics comparable to obligate methanotrophs from the genus Methylocaldum. This newly isolated methanotroph grew on biogas or purified CH4 and successfully converted biogas from AD to methanol. Methanol production was achieved using several methanol dehydrogenase (MDH) inhibitors and formate as an electron donor. The isolate also produced methanol using phosphate with no electron donor or using formate with no MDH inhibitor. The maximum methanol concentration (0.43±0.00gL(-1)) and 48-h CH4 to methanol conversion (25.5±1.1%) were achieved using biogas as substrate and a growth medium containing 50mM phosphate and 80mM formate.

  3. A rapid procedure for the in situ assay of periplasmic, PQQ-dependent methanol dehydrogenase in intact single bacterial colonies.

    PubMed

    Vemuluri, Venkata Ramana; Shaw, Shreya; Autenrieth, Caroline; Ghosh, Robin

    2017-03-23

    Mechanistic details of methanol oxidation catalyzed by the periplasmically-located pyrroloquinoline quinone-dependent methanol dehydrogenase of methylotrophs can be elucidated using site-directed mutants. Here, we present an in situ colony assay of methanol dehydrogenase, which allows robotic screening of large populations of intact small colonies, and regrowth of colonies for subsequent analysis.

  4. Torsion-rotation intensities in methanol

    NASA Astrophysics Data System (ADS)

    Pearson, John

    Methanol exists in numerous kinds of astronomical objects featuring a wide range of local conditions. The light nature of the molecule coupled with the internal rotation of the methyl group with respect to the hydroxyl group results in a rich, strong spectrum that spans the entire far-infrared region. As a result, any modest size observational window will have a number of strong methanol transitions. This has made it the gas of choice for testing THz receivers and to extract the local physical conditions from observations covering small frequency windows. The latter has caused methanol to be dubbed the Swiss army knife of astrophysics. Methanol has been increasingly used in this capacity and will be used even more for subsequent investigations into the Herschel archive, and with SOFIA and ALMA. Interpreting physical conditions on the basis of a few methanol lines requires that the molecular data, line positions, intensities, and collision rates, be complete, consistent and accurate to a much higher level than previously required for astrophysics. The need for highly reliable data is even more critical for modeling the two classes of widespread maser action and many examples of optical pumping through the torsional bands. Observation of the torsional bands in the infrared will be a unique opportunity to directly connect JWST observations with those of Herschel, SOFIA, and ALMA. The theory for the intensities of torsion-rotation transitions in a molecule featuring a single internally rotating methyl group is well developed after 70 years of research. However, other than a recent very preliminary and not completely satisfactory investigation of a few CH3OH torsional bands, this theory has never been experimentally tested for any C3V internal rotor. More alarming is a set of recent intensity calibrated microwave measurements that showed deviations relative to calculations of up to 50% in some ground state rotational transitions commonly used by astronomers to extract

  5. An ecosystem-scale perspective of the net land methanol flux. Synthesis of micrometeorological flux measurements

    SciTech Connect

    Wohlfahrt, G.; Amelynck, C.; Ammann, C.; Arneth, A.; Bamberger, I.; Goldstein, A. H.; Gu, L.; Guenther, A.; Hansel, A.; Heinesch, B.; Holst, T.; Hörtnagl, L.; Karl, T.; Laffineur, Q.; Neftel, A.; McKinney, K.; Munger, J. W.; Pallardy, S. G.; Schade, G. W.; Seco, R.; Schoon, N.

    2015-07-09

    Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates, reflecting uncertainties in the approaches used to model and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land–atmosphere methanol exchange. Our study shows that the controls of plant growth on production, and thus the methanol emission magnitude, as well as stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; however, they are neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow for full advantage to be taken of

  6. An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements

    PubMed Central

    Wohlfahrt, G.; Amelynck, C.; Ammann, C.; Arneth, A.; Bamberger, I.; Goldstein, A. H.; Gu, L.; Guenther, A.; Hansel, A.; Heinesch, B.; Holst, T.; Hörtnagl, L.; Karl, T.; Laffineur, Q.; Neftel, A.; McKinney, K.; Munger, J. W.; Pallardy, S. G.; Schade, G. W.; Seco, R.; Schoon, N.

    2015-01-01

    Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land–atmosphere methanol exchange. Our study shows that the controls of plant growth on the production, and thus the methanol emission magnitude, and stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow taking full advantage of the rich

  7. An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements

    NASA Astrophysics Data System (ADS)

    Wohlfahrt, G.; Amelynck, C.; Ammann, C.; Arneth, A.; Bamberger, I.; Goldstein, A. H.; Gu, L.; Guenther, A.; Hansel, A.; Heinesch, B.; Holst, T.; Hörtnagl, L.; Karl, T.; Laffineur, Q.; Neftel, A.; McKinney, K.; Munger, J. W.; Pallardy, S. G.; Schade, G. W.; Seco, R.; Schoon, N.

    2015-01-01

    Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land-atmosphere methanol exchange. Our study shows that the controls of plant growth on the production, and thus the methanol emission magnitude, and stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow taking full advantage of the rich

  8. An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements

    NASA Astrophysics Data System (ADS)

    Wohlfahrt, G.; Amelynck, C.; Ammann, C.; Arneth, A.; Bamberger, I.; Goldstein, A. H.; Gu, L.; Guenther, A.; Hansel, A.; Heinesch, B.; Holst, T.; Hörtnagl, L.; Karl, T.; Laffineur, Q.; Neftel, A.; McKinney, K.; Munger, J. W.; Pallardy, S. G.; Schade, G. W.; Seco, R.; Schoon, N.

    2015-07-01

    Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates, reflecting uncertainties in the approaches used to model and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land-atmosphere methanol exchange. Our study shows that the controls of plant growth on production, and thus the methanol emission magnitude, as well as stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; however, they are neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow for full advantage to be taken of

  9. An ecosystem-scale perspective of the net land methanol flux. Synthesis of micrometeorological flux measurements

    DOE PAGES

    Wohlfahrt, G.; Amelynck, C.; Ammann, C.; ...

    2015-07-09

    Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates, reflecting uncertainties in the approaches used to model and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis ofmore » the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land–atmosphere methanol exchange. Our study shows that the controls of plant growth on production, and thus the methanol emission magnitude, as well as stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; however, they are neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow for full advantage to be

  10. An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements.

    PubMed

    Wohlfahrt, G; Amelynck, C; Ammann, C; Arneth, A; Bamberger, I; Goldstein, A H; Gu, L; Guenther, A; Hansel, A; Heinesch, B; Holst, T; Hörtnagl, L; Karl, T; Laffineur, Q; Neftel, A; McKinney, K; Munger, J W; Pallardy, S G; Schade, G W; Seco, R; Schoon, N

    2015-01-27

    Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land-atmosphere methanol exchange. Our study shows that the controls of plant growth on the production, and thus the methanol emission magnitude, and stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow taking full advantage of the rich

  11. Methanol unity frays, discounting returns

    SciTech Connect

    Morris, G.D.L.

    1997-02-05

    This article reviews the price variation in methanol for February 1997 and how the company Methanex compares to other producers. The discrepancy between posting prices and transaction prices is noted.

  12. Liquid-Feed Methanol Fuel Cell With Membrane Electrolyte

    NASA Technical Reports Server (NTRS)

    Surampudi, Subbarao; Narayanan, S. R.; Halpert, Gerald; Frank, Harvey; Vamos, Eugene

    1995-01-01

    Fuel cell generates electricity from direct liquid feed stream of methanol/water solution circulated in contact with anode, plus direct gaseous feed stream of air or oxygen in contact with cathode. Advantages include relative simplicity and elimination of corrosive electrolytic solutions. Offers potential for reductions in size, weight, and complexity, and for increases in safety of fuel-cell systems.

  13. Liquid methanol under a static electric field

    SciTech Connect

    Cassone, Giuseppe; Giaquinta, Paolo V.; Saija, Franz; Saitta, A. Marco

    2015-02-07

    We report on an ab initio molecular dynamics study of liquid methanol under the effect of a static electric field. We found that the hydrogen-bond structure of methanol is more robust and persistent for field intensities below the molecular dissociation threshold whose value (≈0.31 V/Å) turns out to be moderately larger than the corresponding estimate obtained for liquid water. A sustained ionic current, with ohmic current-voltage behavior, flows in this material for field intensities above 0.36 V/Å, as is also the case of water, but the resulting ionic conductivity (≈0.40 S cm{sup −1}) is at least one order of magnitude lower than that of water, a circumstance that evidences a lower efficiency of proton transfer processes. We surmise that this study may be relevant for the understanding of the properties and functioning of technological materials which exploit ionic conduction, such as direct-methanol fuel cells and Nafion membranes.

  14. Indonesia to build methanol plant

    SciTech Connect

    Alperowicz, N.

    1992-08-05

    P.T. Kaltim Methanol Industri (Jakarta), a company set up to build a new methanol plant in Indonesia, expects to award contracts for the construction of a new plant, Indonesia's second methanol unit, by the end of this year. P.T. Kaltim Methanol is a private company owned by P.T. Humpuss, an industrial group active in transport, airlines, and shipping of LNG and methanol. The 2,000-m.t./day plant will be built at Bontang, Kalimantan Island, close to the fertilizer producer P.T. Pupuk Kaltim and near the country's largest natural gas reserves. The site is also a deepsea port, handy for transportation of ready product. Three groups are in discussions with the investor on plant supply as well as methanol offtake deals. They are H G/Kockner; John Brown/Davy/Lucky Goldstar, offering the ICI process independently; and Lurgi/Metallgesellschaft (MG), proposing the Lurgi process. At least 60% of the output is expected to be exported, and both ICI and MG are understood to be interested in selling product from the future plant. Japan, Southeast Asia, and the US are targeted.

  15. Acute methanol toxicity in minipigs

    SciTech Connect

    Dorman, D.C.; Dye, J.A.; Nassise, M.P.; Ekuta, J.; Bolon, B.

    1993-01-01

    The pig has been proposed as a potential animal model for methanol-induced neuro-ocular toxicosis in humans because of its low liver tetrahydrofolate levels and slower rate of formate metabolism compared to those of humans. To examine the validity of this animal model, 12 4-month-old female minipigs (minipig YU) were given a single oral dose of water or methanol at 1.0, 2.5, or 5.0 g/kg body wt by gavage (n = 3 pigs/dose). Dose-dependent signs of acute methanol intoxication, which included mild CNS depression, tremors, ataxia, and recumbency, developed within 0.5 to 2.0 hr, and resolved by 52 hr. Methanol- and formate-dosed pigs did not develop optic nerve lesions, toxicologically significant formate accumulation, or metabolic acidosis. Based on results following a single dose, female minipigs do not appear to be overtly sensitive to methanol and thus may not be a suitable animal model for acute methanol-induced neuroocular toxicosis.

  16. Scanning Miniature Microscopes without Lenses

    NASA Technical Reports Server (NTRS)

    Wang, Yu

    2009-01-01

    The figure schematically depicts some alternative designs of proposed compact, lightweight optoelectronic microscopes that would contain no lenses and would generate magnified video images of specimens. Microscopes of this type were described previously in Miniature Microscope Without Lenses (NPO - 20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43 and Reflective Variants of Miniature Microscope Without Lenses (NPO 20610), NASA Tech Briefs, Vol. 26, No. 9 (September 1999), page 6a. To recapitulate: In the design and construction of a microscope of this type, the focusing optics of a conventional microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. Elimination of focusing optics reduces the size and weight of the instrument and eliminates the need for the time-consuming focusing operation. The microscopes described in the cited prior articles contained two-dimensional CCDs registered with two-dimensional arrays of microchannels and, as such, were designed to produce full two-dimensional images, without need for scanning. The microscopes of the present proposal would contain one-dimensional (line image) CCDs registered with linear arrays of microchannels. In the operation of such a microscope, one would scan a specimen along a line perpendicular to the array axis (in other words, one would scan in pushbroom fashion). One could then synthesize a full two-dimensional image of the specimen from the line-image data acquired at one-pixel increments of position along the scan. In one of the proposed microscopes, a beam of unpolarized light for illuminating the specimen would enter from the side. This light would be reflected down onto the specimen by a nonpolarizing beam splitter attached to the microchannels at their lower ends. A portion of the light incident on the specimen would be reflected upward, through the beam splitter and along the microchannels, to form an image on the CCD. If the

  17. Contact stresses calculated for miniature slip rings

    NASA Technical Reports Server (NTRS)

    Albright, F. G.; Domerest, K. E.; Horton, J. C.

    1965-01-01

    Using mathematical formulations to plot the graphs of the contact preload versus the Hertzian load, calculations of unit loading of the preloaded brushes on slip rings can be made. This optimizes the design of contact brushes and miniature slip rings.

  18. Using Miniature Landforms in Teaching Geomorphology.

    ERIC Educational Resources Information Center

    Petersen, James F.

    1986-01-01

    This paper explores the uses of true landform miniatures and small-scale analogues and suggests ways to teach geomorphological concepts using small-scale relief features as illustrative examples. (JDH)

  19. Miniature infrared data acquisition and telemetry system

    NASA Technical Reports Server (NTRS)

    Stokes, J. H.; Ward, S. M.

    1985-01-01

    The Miniature Infrared Data Acquisition and Telemetry (MIRDAT) Phase 1 study was performed to determine the technical and commercial feasibility of producing a miniaturized electro-optical telemetry system. This system acquires and transmits experimental data from aircraft scale models for realtime monitoring in wind tunnels. During the Phase 1 study, miniature prototype MIRDAT telemetry devices were constructed, successfully tested in the laboratory and delivered to the user for wind tunnel testing. A search was conducted for commercially available components and advanced hybrid techniques to further miniaturize the system during Phase 2 development. A design specification was generated from laboratory testing, user requirements and discussions with component manufacturers. Finally, a preliminary design of the proposed MIRDAT system was documented for Phase 2 development.

  20. A Miniature Controllable Flapping Wing Robot

    NASA Astrophysics Data System (ADS)

    Arabagi, Veaceslav Gheorghe

    The agility and miniature size of nature's flapping wing fliers has long baffled researchers, inspiring biological studies, aerodynamic simulations, and attempts to engineer their robotic replicas. Flapping wing flight is characterized by complex reciprocating wing kinematics, transient aerodynamic effects, and very small body lengths. These characteristics render robotic flapping wing aerial vehicles ideal for surveillance and defense applications, search and rescue missions, and environment monitoring, where their ability to hover and high maneuverability is immensely beneficial. One of the many difficulties in creating flapping wing based miniature robotic aerial vehicles lies in generating a proper wing trajectory that would result in sufficient lift forces for hovering and maneuvering. Since design of a flapping wing system is a balance between overall weight and the number of actuated inputs, we take the approach of having minimal controlled inputs, allowing passive behavior wherever possible. Hence, we propose a completely passive wing pitch reversal design that relies on wing inertial dynamics, an elastic energy storage mechanism, and low Reynolds number aerodynamic effects. Theoretical models, compiling previous research on piezoelectric actuators, four-bar transmissions, and aerodynamics effects, are developed and used as basis for a complete numerical simulation. Limitations of the model are discussed in comparison to experimental results obtained from a working prototype of the proposed passive pitch reversal flapping wing mechanism. Given that the mechanism is under-actuated, methods to control lift force generation by actively varying system parameters are proposed, discussed, and tested experimentally. A dual wing aerial platform is developed based on the passive pitch reversal wing concept. Design considerations are presented, favoring controllability and structural rigidity of the final platform. Finite element analysis and experimental

  1. Design considerations for miniaturized optical neural probes

    NASA Astrophysics Data System (ADS)

    Rudmann, Linda; Ordonez, Juan S.; Stieglitz, Thomas

    2016-03-01

    Neural probes are designed to selectively record from or stimulate nerve cells. In optogenetics it is desirable to build miniaturized and long-term stable optical neural probes, in which the light sources can be directly and chronically implanted into the animals to allow free movement and behavior. Because of the size and the beam shape of the available light sources, it is difficult to target single cells as well as spatially localized networks. We therefore investigated design considerations for packages, which encapsulate the light source hermetically and have integrated hemispherical lens structures that enable to focus the light onto the desired region, by optical simulations. Integration of a biconvex lens into the package lid (diameter = 300 μm, material: silicon carbide) increased the averaged absolute irradiance ηA by 298 % compared to a system without a lens and had a spot size of around 120 μm. Solely integrating a plano-convex lens (same diameter and material) results in an ηA of up to 227 %.

  2. Miniaturized Plasma and Neutral Diagnostics for JIMO

    NASA Technical Reports Server (NTRS)

    McHarg, M. G.; Enloe, C. L.; Krause, L. A.; Herrero, F. A.

    2003-01-01

    We describe a miniaturized suite of instruments which provides both bulk energy resolved plasma properties and coarse neutral mass spectroscopy suitable for measurements on the Jupiter Icy Moons Orbiter (JIMO). The suite is comprised of two instruments; the Miniaturized Electro-Static Analyzer (MESA), and the Flat Plasma Spectrometer (FLAPS), designed to measure the near earth environment on the Air Force Academy small satellite missions Falconsat-2 and 3.

  3. Metamaterials for Miniaturization of Optical Components

    DTIC Science & Technology

    2014-09-24

    AFRL-OSR-VA-TR-2014-0226 METAMATERIALS FOR MINIATURIZATION OF OPTICAL COMPONENTS Aleksandr Figotin UNIVERSITY OF CALIFORNIA IRVINE Final Report 09/24...8-98) v Prescribed by ANSI Std. Z39.18 10/09/2014 Final 30/06/2011-30/06/2014 METAMATERIALS FOR MINIATURIZATION OF OPTICAL COMPONENTS FA9550-11-1...relativistic and spinorial aspects of our neoclassical electromagnetic theory. Metamaterials , fundamentals of electromagnetic theory, dissipation, magnetic

  4. Miniature Electrostatic Ion Thruster With Magnet

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2006-01-01

    A miniature electrostatic ion thruster is proposed that, with one exception, would be based on the same principles as those of the device described in the previous article, "Miniature Bipolar Electrostatic Ion Thruster". The exceptional feature of this thruster would be that, in addition to using electric fields for linear acceleration of ions and electrons, it would use a magnetic field to rotationally accelerate slow electrons into the ion stream to neutralize the ions.

  5. Miniaturized GPS/MEMS IMU integrated board

    NASA Technical Reports Server (NTRS)

    Lin, Ching-Fang (Inventor)

    2012-01-01

    This invention documents the efforts on the research and development of a miniaturized GPS/MEMS IMU integrated navigation system. A miniaturized GPS/MEMS IMU integrated navigation system is presented; Laser Dynamic Range Imager (LDRI) based alignment algorithm for space applications is discussed. Two navigation cameras are also included to measure the range and range rate which can be integrated into the GPS/MEMS IMU system to enhance the navigation solution.

  6. Unusual case of methanol poisoning

    SciTech Connect

    Shapiro, L.; Henderson, M. . Dept. of Chemical Pathology); Madi, S.; Mellor, L. . Dept. of Medicine, and Pharmacy)

    1993-01-09

    A 31-year-old man with a history of alcohol abuse presented to the accident and emergency department complaining of blurred vision. 4 h previously he had drunk 300 mL de-icer fluid. Electrolytes, urea, creatinine, glucose, and blood-gas analysis were normal. Measured osmolality, however, was 368 mosmol/kg with a calculated osmolality of 300 mosmol/kg, which indicated a greatly increased osmolar gap. He was therefore given 150 mL whisky and admitted. Methanol was later reported as 200 mg/dL. Ethylene glycol was not detected, but another glycol, propylene glycol, was present at 47 mg/dL. 10 h after ingestion an intravenous infusion of ethanol was started and he was hemodialysed for 7 h. After dialysis he was given a further 100 mL whisky and the rate of ethanol infusion was reduced to 11 g per h. Methanol and ethanol were measured twice daily until methanol was under 10/mg/dL: The recommendation is that blood ethanol be maintained between 100 and 200 mg/dL during treatment of methanol poisoning. This concentration was not achieved, presumably because of the high rate of ethanol metabolism often found in alcoholics. Antifreeze solutions commonly contain methanol and ethylene glycol. Sometimes propylene glycol is substituted because it has properties similar to those of ethylene glycol but is less toxic. The authors postulate that propylene glycol inhibited the metabolism of methanol in the patient, thus sparing him from the toxic effects of methanol.

  7. Miniature curved artificial compound eyes

    PubMed Central

    Floreano, Dario; Pericet-Camara, Ramon; Viollet, Stéphane; Ruffier, Franck; Brückner, Andreas; Leitel, Robert; Buss, Wolfgang; Menouni, Mohsine; Expert, Fabien; Juston, Raphaël; Dobrzynski, Michal Karol; L’Eplattenier, Geraud; Recktenwald, Fabian; Mallot, Hanspeter A.; Franceschini, Nicolas

    2013-01-01

    In most animal species, vision is mediated by compound eyes, which offer lower resolution than vertebrate single-lens eyes, but significantly larger fields of view with negligible distortion and spherical aberration, as well as high temporal resolution in a tiny package. Compound eyes are ideally suited for fast panoramic motion perception. Engineering a miniature artificial compound eye is challenging because it requires accurate alignment of photoreceptive and optical components on a curved surface. Here, we describe a unique design method for biomimetic compound eyes featuring a panoramic, undistorted field of view in a very thin package. The design consists of three planar layers of separately produced arrays, namely, a microlens array, a neuromorphic photodetector array, and a flexible printed circuit board that are stacked, cut, and curved to produce a mechanically flexible imager. Following this method, we have prototyped and characterized an artificial compound eye bearing a hemispherical field of view with embedded and programmable low-power signal processing, high temporal resolution, and local adaptation to illumination. The prototyped artificial compound eye possesses several characteristics similar to the eye of the fruit fly Drosophila and other arthropod species. This design method opens up additional vistas for a broad range of applications in which wide field motion detection is at a premium, such as collision-free navigation of terrestrial and aerospace vehicles, and for the experimental testing of insect vision theories. PMID:23690574

  8. Miniature Ion-Array Spectrometer

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2006-01-01

    A figure is shown that depicts a proposed miniature ion-mobility spectrometer that would share many features of design and operation of the instrument described in another article. The main differences between that instrument and this one would lie in the configuration and mode of operation of the filter and detector electrodes. A filter electrode and detector electrodes would be located along the sides of a drift tube downstream from the accelerator electrode. These electrodes would apply a combination of (1) a transverse AC electric field that would effect differential transverse dispersal of ions and (2) a transverse DC electric field that would drive the dispersed ions toward the detector electrodes at different distances along the drift tube. The electric current collected by each detector electrode would be a measure of the current, and thus of the abundance of the species of ions impinging on that electrode. The currents collected by all the detector electrodes could be measured simultaneously to obtain continuous readings of abundances of species. The downstream momentum of accelerated ions would be maintained through neutralization on the electrodes; the momentum of the resulting neutral atoms would serve to expel gases from spectrometer, without need for a pump.

  9. Miniature curved artificial compound eyes.

    PubMed

    Floreano, Dario; Pericet-Camara, Ramon; Viollet, Stéphane; Ruffier, Franck; Brückner, Andreas; Leitel, Robert; Buss, Wolfgang; Menouni, Mohsine; Expert, Fabien; Juston, Raphaël; Dobrzynski, Michal Karol; L'Eplattenier, Geraud; Recktenwald, Fabian; Mallot, Hanspeter A; Franceschini, Nicolas

    2013-06-04

    In most animal species, vision is mediated by compound eyes, which offer lower resolution than vertebrate single-lens eyes, but significantly larger fields of view with negligible distortion and spherical aberration, as well as high temporal resolution in a tiny package. Compound eyes are ideally suited for fast panoramic motion perception. Engineering a miniature artificial compound eye is challenging because it requires accurate alignment of photoreceptive and optical components on a curved surface. Here, we describe a unique design method for biomimetic compound eyes featuring a panoramic, undistorted field of view in a very thin package. The design consists of three planar layers of separately produced arrays, namely, a microlens array, a neuromorphic photodetector array, and a flexible printed circuit board that are stacked, cut, and curved to produce a mechanically flexible imager. Following this method, we have prototyped and characterized an artificial compound eye bearing a hemispherical field of view with embedded and programmable low-power signal processing, high temporal resolution, and local adaptation to illumination. The prototyped artificial compound eye possesses several characteristics similar to the eye of the fruit fly Drosophila and other arthropod species. This design method opens up additional vistas for a broad range of applications in which wide field motion detection is at a premium, such as collision-free navigation of terrestrial and aerospace vehicles, and for the experimental testing of insect vision theories.

  10. Investigation of the In-Situ Oxidation of Methanol in Fuel Cells.

    DTIC Science & Technology

    1981-09-01

    ability of the catalyst to tolerate carbon monoxide. Finally, a performance curve was obtained for the anodic oxidation of methanol : CH3OH ... CH3OH + H20 •» C02 + 3H2 In present methanol -air fuel cell power plants , the steam reforming process is usually carried out in a unit which is...KCY YIO"(CS (Continue on reverse ride it neeessnry and identity ay block number) Fuel Cell Platinum Catalysts Methanol Direct Oxidation Internal

  11. Engineering electromagnetic metamaterials and methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Yen, Tajen

    2005-07-01

    Electromagnetic metamaterials represent a group of artificial structures, whose dimensions are smaller than subwavelength. Due to electromagnetic metamaterials' collective response to the applied fields, they can exhibit unprecedented properties to fascinate researchers' eyes. For instance, artificial magnetism above terahertz frequencies and beyond, negative magnetic response, and artificial plasma lower than ultraviolet and visible frequencies. Our goal is to engineer those novel properties aforementioned at interested frequency regions and further optimize their performance. To fulfill this task, we developed exclusive micro/nano fabrication techniques to construct magnetic metamaterials (i.e., split-ring resonators and L-shaped resonators) and electric metamaterials (i.e., plasmonic wires) and also employed Taguchi method to study the optimal design of electromagnetic metamaterials. Moreover, by integrating magnetic and electric metamaterials, we have been pursuing to fabricate so-called negative index media---the Holy Grail enables not only to reverse conventional optical rules such as Snell's law, Doppler shift, and Cerenkov radiation, but also to smash the diffraction limit to realize the superlensing effect. In addition to electromagnetic metamaterials, in this dissertation we also successfully miniaturize silicon-based methanol fuel cells by means of micro-electrical-mechanical-system technique, which promise to provide an integrated micro power source with excellent performance. Our demonstrated power density and energy density are one of the highest in reported documents. Finally, based on the results of metamaterials and micro fuel cells, we intend to supply building blocks to complete an omnipotent device---a system with sensing, communication, computing, power, control, and actuation functions.

  12. Methanol conversion to higher hydrocarbons

    SciTech Connect

    Tabak, S.A.

    1994-12-31

    Several indirect options exist for producing chemicals and transportation fuels from coal, natural gas, or biomass. All involve an initial conversion step to synthesis gas (CO and H{sub 2}). Presently, there are two commercial technologies for converting syngas to liquids: Fischer-Tropsch, which yields a range of aliphatic hydrocarbons with molecular weights determined by Schulz-Flory kinetics, and methanol synthesis. Mobil`s diversity of technology for methanol conversion gives the methanol synthesis route flexibility for production of either gasoline, distillate or chemicals. Mobil`s ZSM-5 catalyst is the key in several processes for producing chemicals and transportation fuels from methanol: MTO for light olefins, MTG for gasoline, MOGD for distillates. The MTG process has been commercialized in New Zealand since 1985, producing one-third of the country`s gasoline supply, while MTO and MOGD have been developed and demonstrated at greater than 100 BPD scale. This paper will discuss recent work in understanding methanol conversion chemistry and the various options for its use.

  13. Miniature Ion-Mobility Spectrometer

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2006-01-01

    The figure depicts a proposed miniature ion-mobility spectrometer that would be fabricated by micromachining. Unlike prior ion-mobility spectrometers, the proposed instrument would not be based on a time-of-flight principle and, consequently, would not have some of the disadvantageous characteristics of prior time-of-flight ion-mobility spectrometers. For example, one of these characteristics is the need for a bulky carrier-gas-feeding subsystem that includes a shutter gate to provide short pulses of gas in order to generate short pulses of ions. For another example, there is need for a complex device to generate pulses of ions from the pulses of gas and the device is capable of ionizing only a fraction of the incoming gas molecules; these characteristics preclude miniaturization. In contrast, the proposed instrument would not require a carrier-gas-feeding subsystem and would include a simple, highly compact device that would ionize all the molecules passing through it. The ionization device in the proposed instrument would be a 0.1-micron-thick dielectric membrane with metal electrodes on both sides. Small conical holes would be micromachined through the membrane and electrodes. An electric potential of the order of a volt applied between the membrane electrodes would give rise to an electric field of the order of several megavolts per meter in the submicron gap between the electrodes. An electric field of this magnitude would be sufficient to ionize all the molecules that enter the holes. Ionization (but not avalanche arcing) would occur because the distance between the ionizing electrodes would be less than the mean free path of gas molecules at the operating pressure of instrument. An accelerating grid would be located inside the instrument, downstream from the ionizing membrane. The electric potential applied to this grid would be negative relative to the potential on the inside electrode of the ionizing membrane and would be of a magnitude sufficient to

  14. The Revised Version of Class I Methanol Maser Catalog

    NASA Astrophysics Data System (ADS)

    Larionov, G. M.; Litovchenko, I. D.; Val'tts, I. E.; Alakoz, A. V.

    2011-05-01

    The revised version of the class I methanol maser catalog is presented. It contains 198 sources in total. New class I methanol masers detected in the direction of EGOs (38 sources) were added to the previous list containing ˜ 160 sources (the list have been published in the first version of this catalog - see reference in the text). Electronic version of the catalog has been generated in the form of html file - http://www.asc.rssi.ru/MMI. A statistical analysis was carried out within 2' around a maser position to find an identification of class I methanol masers with any objects typical for star-forming regions - UCHII regions, IRAS sources, dark clouds, bipolar outflows, CS lines as of dense gas tracer, and other masers (class II methanol masers, OH and H_2O). Class I methanol masers identification was made with short-wave infrared objects EGO (extended green objects), which are tracers of bipolar outflows in young stellar objects. It was shown that in the new version of catalog more than 50% of class I methanol masers are identified with bipolar outflow - given EGOs as bipolar outflows (compared with the result of 22% in the first version of the catalog that contains no information about EGO). This result is a strong evidence in favor of the fact that EGOs are indeed active bipolar outflows. At the same time it is important to note, that none of the bipolar outflow, already registered in the direction of class I methanol maser, did not coincide with EGO (with the exception of G45.47+0.07). The results are submitted in a form of a diagram.

  15. Miniature EVA Software Defined Radio

    NASA Technical Reports Server (NTRS)

    Pozhidaev, Aleksey

    2012-01-01

    As NASA embarks upon developing the Next-Generation Extra Vehicular Activity (EVA) Radio for deep space exploration, the demands on EVA battery life will substantially increase. The number of modes and frequency bands required will continue to grow in order to enable efficient and complex multi-mode operations including communications, navigation, and tracking applications. Whether conducting astronaut excursions, communicating to soldiers, or first responders responding to emergency hazards, NASA has developed an innovative, affordable, miniaturized, power-efficient software defined radio that offers unprecedented power-efficient flexibility. This lightweight, programmable, S-band, multi-service, frequency- agile EVA software defined radio (SDR) supports data, telemetry, voice, and both standard and high-definition video. Features include a modular design, an easily scalable architecture, and the EVA SDR allows for both stationary and mobile battery powered handheld operations. Currently, the radio is equipped with an S-band RF section. However, its scalable architecture can accommodate multiple RF sections simultaneously to cover multiple frequency bands. The EVA SDR also supports multiple network protocols. It currently implements a Hybrid Mesh Network based on the 802.11s open standard protocol. The radio targets RF channel data rates up to 20 Mbps and can be equipped with a real-time operating system (RTOS) that can be switched off for power-aware applications. The EVA SDR's modular design permits implementation of the same hardware at all Network Nodes concept. This approach assures the portability of the same software into any radio in the system. It also brings several benefits to the entire system including reducing system maintenance, system complexity, and development cost.

  16. High torque miniature rotary actuator

    NASA Astrophysics Data System (ADS)

    Nalbandian, Ruben

    2005-07-01

    This paper summarizes the design and the development of a miniature rotary actuator (36 mm diameter by 100 mm length) used in spacecraft mechanisms requiring high torques and/or ultra-fine step resolution. This actuator lends itself to applications requiring high torque but with strict volume limitations which challenge the use of conventional rotary actuators. The design challenge was to develop a lightweight (less than 500 grams), very compact, high bandwidth, low power, thermally stable rotary actuator capable of producing torques in excess of 50 N.m and step resolutions as fine as 0.003 degrees. To achieve a relatively high torsional stiffness in excess of 1000 Nm/radian, the design utilizes a combination of harmonic drive and multistage planetary gearing. The unique design feature of this actuator that contributes to its light weight and extremely precise motion capability is a redundant stepper motor driving the output through a multistage reducing gearbox. The rotary actuator is powered by a high reliability space-rated stepper motor designed and constructed by Moog, Inc. The motor is a three-phase stepper motor of 15 degree step angle, producing twenty-four full steps per revolution. Since micro-stepping is not used in the design, and un-powered holding torque is exhibited at every commanded step, the rotary actuator is capable of reacting to torques as high as 35 Nm by holding position with the power off. The output is driven through a gear transmission having a total train ratio of 5120:1, resulting in a resolution of 0.003 degrees output rotation per motor step. The modular design of the multi-stage output transmission makes possible the addition of designs having different output parameters, such as lower torque and higher output speed capability. Some examples of an actuator family based on this growth capability will be presented in the paper.

  17. Miniaturized cathodic arc plasma source

    DOEpatents

    Anders, Andre; MacGill, Robert A.

    2003-04-15

    A cathodic arc plasma source has an anode formed of a plurality of spaced baffles which extend beyond the active cathode surface of the cathode. With the open baffle structure of the anode, most macroparticles pass through the gaps between the baffles and reflect off the baffles out of the plasma stream that enters a filter. Thus the anode not only has an electrical function but serves as a prefilter. The cathode has a small diameter, e.g. a rod of about 1/4 inch (6.25 mm) diameter. Thus the plasma source output is well localized, even with cathode spot movement which is limited in area, so that it effectively couples into a miniaturized filter. With a small area cathode, the material eroded from the cathode needs to be replaced to maintain plasma production. Therefore, the source includes a cathode advancement or feed mechanism coupled to cathode rod. The cathode also requires a cooling mechanism. The movable cathode rod is housed in a cooled metal shield or tube which serves as both a current conductor, thus reducing ohmic heat produced in the cathode, and as the heat sink for heat generated at or near the cathode. Cooling of the cathode housing tube is done by contact with coolant at a place remote from the active cathode surface. The source is operated in pulsed mode at relatively high currents, about 1 kA. The high arc current can also be used to operate the magnetic filter. A cathodic arc plasma deposition system using this source can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  18. The path of carbon in photosynthesis: improved crop yields with methanol.

    PubMed Central

    Nonomura, A M; Benson, A A

    1992-01-01

    Foliar sprays of aqueous 10-50% methanol increased growth and development of C3 crop plants in arid environments. The effects of low levels (< 1 ml per plant) of methanol were observed for weeks after the brief time necessary for its rapid metabolism. Within several hours, foliar treatment with methanol resulted in increased turgidity. Plants treated with nutrient-supplemented methanol showed up to 100% increases in yields when maintained under direct sunlight in desert agriculture. In the shade and when winter crops were treated with methanol, plants showed no improvement of growth. When repeatedly treated with nutrient-supplemented methanol, shaded plants showed symptoms of toxicity. Repeated methanol treatments with glycine caused increased turgidity and stimulated plant growth without injury under indirect sunlight, but indoors with artificial illumination, foliar damage developed after 48 hr. Addition of glycerophosphate to glycine/methanol solutions allowed treatment of artificially illuminated plants indoors without injury. Plants with C4 metabolism showed no increase in productivity by methanol treatment. Plants given many applications of aqueous methanol showed symptoms of nutrient deficiency. Supplementation with a source of nitrogen sustained growth, eliminating symptoms of deficiency. Adjustment of carbon/nitrogen ratios was undertaken in the field by decreasing the source of nitrogen in the final application, resulting in early maturation; concomitantly, irrigation requirements were reduced. PMID:1409701

  19. Highly methanol-tolerant platinum electrocatalyst derived from poly(vinylpoyrrolidone) coating

    NASA Astrophysics Data System (ADS)

    Yang, Zehui; Ling, Ying; Zhang, Yunfeng; Yang, Ming

    2017-02-01

    The design and fabrication of a methanol-tolerant electrocatalyst is still one of the most important issues in direct methanol fuel cells (DMFCs). Here, we focus on the design of a cathodic electrocatalyst in DMFCs and describe a new methanol-tolerant electrocatalyst fabricated from poly(vinylpyrrolidone) (PVP) coating on platinum nanoparticles assisted by hydrogen bonding between PVP and polybenzimidazole (PBI). The PVP layer has a negligible effect on the oxygen reduction reaction (ORR) activity, while the methanol oxidation reaction is retarded by the PVP layer. The PVP-coated electrocatalyst shows higher ORR activity under various methanol concentrations in the electrolyte, suggesting that the PVP-coated electrocatalyst has a higher methanol tolerance. Also, the PVP-coated electrocatalyst loses only 14% of the electrochemical surface area after 5000 potential cycles from 0.6-1.0 V versus the reversible hydrogen electrode, indicating better Pt stability than non-coated (27%) and commercial (38%) electrocatalysts due to the unique sandwich structure formed by the PVP and PBI. The power density of the PVP-coated electrocatalyst is four to five times higher compared to non-coated and commercial electrocatalysts with 12 M methanol feeding to the anode side, respectively. PVP coating is important for the enhancement of Pt stability and methanol tolerance. This study offers a new method for preparing a low-cost and high-methanol-tolerant Pt electrocatalyst, and useful information for real DMFC application to eliminate the methanol crossover problem in the cathode side.

  20. Battery-driven miniature LDA system with semiconductor laser diode

    NASA Astrophysics Data System (ADS)

    Damp, S.

    1988-06-01

    A one-component miniature system with dimensions of 11 by 4 by 4 cubic centimeters for laser-Doppler anemometry (LDA) is described. As power supply a 12V battery or any other source with the capability to drive a current up to 200mA can be used. The system contains the whole electronics to drive the used laser diode is a safe way. The electronics to amplify and buffer the LDA-signal which is received by a PIN-diode is included. The output of the system can directly fit a filterbank for example. Possible applications in rough environments are mentioned. Measurements show the reliability of the system.

  1. Advances in miniature spectrometer and sensor development

    NASA Astrophysics Data System (ADS)

    Malinen, Jouko; Rissanen, Anna; Saari, Heikki; Karioja, Pentti; Karppinen, Mikko; Aalto, Timo; Tukkiniemi, Kari

    2014-05-01

    Miniaturization and cost reduction of spectrometer and sensor technologies has great potential to open up new applications areas and business opportunities for analytical technology in hand held, mobile and on-line applications. Advances in microfabrication have resulted in high-performance MEMS and MOEMS devices for spectrometer applications. Many other enabling technologies are useful for miniature analytical solutions, such as silicon photonics, nanoimprint lithography (NIL), system-on-chip, system-on-package techniques for integration of electronics and photonics, 3D printing, powerful embedded computing platforms, networked solutions as well as advances in chemometrics modeling. This paper will summarize recent work on spectrometer and sensor miniaturization at VTT Technical Research Centre of Finland. Fabry-Perot interferometer (FPI) tunable filter technology has been developed in two technical versions: Piezoactuated FPIs have been applied in miniature hyperspectral imaging needs in light weight UAV and nanosatellite applications, chemical imaging as well as medical applications. Microfabricated MOEMS FPIs have been developed as cost-effective sensor platforms for visible, NIR and IR applications. Further examples of sensor miniaturization will be discussed, including system-on-package sensor head for mid-IR gas analyzer, roll-to-roll printed Surface Enhanced Raman Scattering (SERS) technology as well as UV imprinted waveguide sensor for formaldehyde detection.

  2. [Optical Design of Miniature Infrared Gratings Spectrometer Based on Planar Waveguide].

    PubMed

    Li, Yang-yu; Fang, Yong-hua; Li, Da-cheng; Liu, Yang

    2015-03-01

    In order to miniaturize an infrared spectrometer, we analyze the current optical design of miniature spectrometers and propose a method for designing a miniature infrared gratings spectrometer based on planar waveguide. Common miniature spectrometer uses miniature optical elements to reduce the size of system, which also shrinks the effective aperture. So the performance of spectrometer has dropped. Miniaturization principle of planar waveguide spectrometer is different from the principle of common miniature spectrometer. In planar waveguide spectrometer, the propagation of light is limited in a thin planar waveguide, which looks like the whole optical system is squashed flat. In the direction parallel to the planar waveguide, the light through the slit is collimated, dispersed and focused. And a spectral image is formed in the detector plane. This propagation of light is similar to the light in common miniature spectrometer. In the direction perpendicular to the planar waveguide, light is multiple reflected by the upper and lower surfaces of the planar waveguide and propagates in the waveguide. So the size of corresponding optical element could be very small in the vertical direction, which can reduce the size of the optical system. And the performance of the spectrometer is still good. The design method of the planar waveguide spectrometer can be separated into two parts, Czerny-Turner structure design and planar waveguide structure design. First, by using aberration theory an aberration-corrected (spherical aberration, coma, focal curve) Czerny-Turner structure is obtained. The operation wavelength range and spectral resolution are also fixed. Then, by using geometrical optics theory a planar waveguide structure is designed for reducing the system size and correcting the astigmatism. The planar waveguide structure includes a planar waveguide and two cylindrical lenses. Finally, they are modeled together in optical design software and are optimized as a whole. An

  3. Two SMA-Actuated Miniature Mechanisms

    NASA Technical Reports Server (NTRS)

    Willey, Cliff E.

    2005-01-01

    The figures depict two miniature mechanisms actuated by strips made of shape-memory alloy (SMA). A typical SMA is a nickel-titanium alloy known by the trade name "Flexinol" or "Nitinol." In preparation for a typical application, a suitably sized and shaped piece of an SMA is deformed by a predetermined amount at the lower of two operating temperatures, then mounted in a mechanism. When stroking of the mechanism in one direction is desired, the piece of SMA is heated above a transition temperature to make it return to the "remembered" undeformed state. When stroking of the mechanism in the opposite direction is desired, the SMA is cooled below the transition temperature to make it return to the deformed state. Also, the SMA alloy chosen for a specific application is one that has a transition temperature somewhat above the ambient temperature, so that stroking in one direction or the opposite direction can be achieved by heating the SMA, or refraining from heating the SMA, respectively, above the transition temperature. In the present mechanisms as in typical other SMA mechanisms, the heating is effected by electric currents applied via electrical contacts at the ends of the SMA strips. The purpose served by the mechanism of Figure 1 is to lock or release a flexible latch attachment. In preparation for use in this mechanism, two initially straight SMA strips are deformed into curved springs that, when mounted in the mechanism at ambient temperature, clamp the knob at the lower end of the flexible latch attachment. When heated above their transition temperature by an electric current, the SMA strips return to their original straight configuration, thereby releasing the knob. This mechanism is redundant in the sense that as long as at least one of the two SMA strips straightens when commanded to do so, the knob is released. The mechanism of Figure 2 is suited to any of a variety of applications in which there are requirements for a small mechanism that affords

  4. A Laser Interferometric Miniature Sensor

    SciTech Connect

    Carr, Dustin W., PhD.; Baldwin, Patrick C.; Milburn, Howard; Robinson, David

    2011-09-12

    This is the second year of a Phase II Small Business Innovation Research (SBIR) contract geared towards the development of a new seismic sensor. Ground-based seismic monitoring systems have proven to be very capable in identifying nuclear tests, and can provide somewhat precise information on the location and yield of the explosive device. Making these measurements, however, currently requires very expensive and bulky seismometers that are difficult to deploy in places where they are most needed. A high performance, compact device can enable rapid deployment of large scale arrays, which can in turn be used to provide higher quality data during times of critical need. The use of a laser interferometer-based device has shown considerable promise, while also presenting significant challenges. The greatest strength of this optical readout technique is the ability to decouple the mechanical design from the transducer, thus enabling a miniaturized design that is not accessible with conventional sensing techniques. However, the nonlinearity in the optical response must be accounted for in the sensor output. Previously, we had proposed using a force-feedback approach to position the sensor at a point of maximum linearity. However, it can be shown that the combined nonlinearities of the optical response and the force-feedback curve necessarily results in a significant amount of unwanted noise at low frequencies. Having realized this, we have developed a new approach that eliminates force feedback, allowing the proof mass to move freely at all times. This takes advantage of some advanced optical spatial filtering that was developed at Symphony Acoustics for other types of sensors, and was recently adapted to this work. After processing the signals in real time, the digital output of the device is intrinsically linear, and the sensor can operate at any orientation with the same level of resolution, while instantly adapting to significant changes in orientation. Ultimately, we

  5. Physical characteristics of bright Class I methanol masers

    NASA Astrophysics Data System (ADS)

    Leurini, S.; Menten, K. M.; Walmsley, C. M.

    2016-07-01

    Context. Class I methanol masers are thought to be tracers of interstellar shock waves. However, they have received relatively little attention mostly as a consequence of their low luminosities compared to other maser transitions. This situation has changed recently and Class I methanol masers are now routinely used as signposts of outflow activity especially in high extinction regions. The recent detection of polarisation in Class I lines now makes it possible to obtain direct observational information about magnetic fields in interstellar shocks. Aims: We make use of newly calculated collisional rate coefficients for methanol to investigate the excitation of Class I methanol masers and to reconcile the observed Class I methanol maser properties with model results. Methods: We performed large velocity gradient calculations with a plane-parallel slab geometry appropriate for shocks to compute the pump and loss rates which regulate the interactions of the different maser systems with the maser reservoir. We study the dependence of the pump rate coefficient, the maser loss rate, and the inversion efficiency of the pumping scheme of several Class I masers on the physics of the emitting gas. Results: We predict inversion in all transitions where maser emission is observed. Bright Class I methanol masers are mainly high-temperature (>100 K) high-density (n(H2) ~ 107-108 cm-3) structures with methanol maser emission measures, ξ, corresponding to high methanol abundances close to the limits set by collisional quenching. Our model predictions reproduce reasonably well most of the observed properties of Class I methanol masers. Class I masers in the 25 GHz series are the most sensitive to the density of the medium and mase at higher densities than other lines. Moreover, even at high density and high methanol abundances, their luminosity is predicted to be lower than that of the 44 GHz and 36 GHz masers. Our model predictions also reflect the observational result that the

  6. Techniques for sensing methanol concentration in aqueous environments

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram R. (Inventor); Chun, William (Inventor); Valdez, Thomas I. (Inventor)

    2001-01-01

    An analyte concentration sensor that is capable of fast and reliable sensing of analyte concentration in aqueous environments with high concentrations of the analyte. Preferably, the present invention is a methanol concentration sensor device coupled to a fuel metering control system for use in a liquid direct-feed fuel cell.

  7. Infrared Spectrum of Methanol: A First-Year Student Experiment.

    ERIC Educational Resources Information Center

    Boehm, Garth; Dwyer, Mark

    1981-01-01

    Describes an experiment providing an experimental introduction to vibrational spectroscopy and experience in using an elementary vacuum line. The experiment, using a gas cell charged with methanol, is completed in a three-hour laboratory period and is directed toward understanding vibrational spectroscopy rather than the diagnostic value of the…

  8. Miniature photometric stereo system for textile surface structure reconstruction

    NASA Astrophysics Data System (ADS)

    Gorpas, Dimitris; Kampouris, Christos; Malassiotis, Sotiris

    2013-04-01

    In this work a miniature photometric stereo system is presented, targeting the three-dimensional structural reconstruction of various fabric types. This is a supportive module to a robot system, attempting to solve the well known "laundry problem". The miniature device has been designed for mounting onto the robot gripper. It is composed of a low-cost off-the-shelf camera, operating in macro mode, and eight light emitting diodes. The synchronization between image acquisition and lighting direction is controlled by an Arduino Nano board and software triggering. The ambient light has been addressed by a cylindrical enclosure. The direction of illumination is recovered by locating the reflection or the brightest point on a mirror sphere, while a flatfielding process compensates for the non-uniform illumination. For the evaluation of this prototype, the classical photometric stereo methodology has been used. The preliminary results on a large number of textiles are very promising for the successful integration of the miniature module to the robot system. The required interaction with the robot is implemented through the estimation of the Brenner's focus measure. This metric successfully assesses the focus quality with reduced time requirements in comparison to other well accepted focus metrics. Besides the targeting application, the small size of the developed system makes it a very promising candidate for applications with space restrictions, like the quality control in industrial production lines or object recognition based on structural information and in applications where easiness in operation and light-weight are required, like those in the Biomedical field, and especially in dermatology.

  9. FY 2007 Miniature Spherical Retroreflectors Final Report

    SciTech Connect

    Anheier, Norman C.; Bernacki, Bruce E.; Krishnaswami, Kannan

    2008-02-20

    Miniature spherical retroreflectors, less than 8 millimeters in diameter, are currently being developed to enhance remote optical detection of nuclear proliferation activities. These retroreflecting spheres resemble small, sand-colored marbles that have the unique optical property of providing a strong reflection directly back to the source (i.e., retroreflecting) when illuminated with a laser. The addition of specific coatings, sensitive to specific chemicals or radioactive decay in the environment, can be applied to the surface of these retroreflectors to provide remote detection of nuclear proliferation activities. The presence of radioactive decay (e.g., alpha, gamma, neutron) or specific chemicals in the environment (e.g., TBP, acids) will change the optical properties of the spheres in a predictable fashion, thus indicating the presence or absence of the target materials. One possible scenario might employ an airborne infrared laser system (e.g., quantum-cascade lasers) to illuminate a section of ground littered with these retroreflective spheres. Depending on the coating and the presence of a specific chemical or radioisotope in the environment, the return signal would be modified in some predictable fashion because of fluorescence, frequency shifting, intensity attenuation/enhancement, or change in polarization. Research conducted in FY 2007 focused on developing novel optical fabrication processes and exploiting the unique material properties of chalcogenide infrared-transparent glass (germanium-arsenic-sulfur-tellurium compounds) to produce highly efficient retroreflectors. Pacific Northwest National Laboratory’s approach provides comparable performance to the ideal graded index sphere concept, developed by R. K. Luneburg in 1944 (Luneburg 1944), while greatly reducing the complexity in fabrication by utilizing chalcogenide glass materials and compression-molding processes.

  10. Goniometry and Limb Girth in Miniature Dachshunds

    PubMed Central

    Thomovsky, Stephanie A.; Chen, Annie V.; Kiszonas, Alecia M.; Lutskas, Lori A.

    2016-01-01

    Purpose. To report the mean and median pelvic limb joint angles and girth measurements in miniature Dachshunds presenting with varying degrees of pelvic limb weakness secondary to thoracolumbar intervertebral disc extrusion. Methods. 15 miniature Dachshunds who presented to WSU-VTH for thoracolumbar disc extrusion. Dachshunds varied in neurologic status from ambulatory paraparetic to paraplegic at the time of measurements. Results. There were no significant differences in joint angles or girth among the three groups (ambulatory paraparetic, nonambulatory paraparetic, or paraplegic) (P > 0.05). When group was disregarded and values for extension, flexion, and girth combined, no differences existed. Conclusions. Goniometry and limb girth measurements can successfully be made in the miniature Dachshund; however, the shape of the Dachshund leg makes obtaining these values challenging. There were no differences in joint angle or girth measurements between dogs with varying neurologic dysfunction at the time of measurement. PMID:27403455

  11. FY 2006 Miniature Spherical Retroreflectors Final Report

    SciTech Connect

    Anheier, Norman C.; Bernacki, Bruce E.; Krishnaswami, Kannan

    2006-12-28

    Research done by the Infrared Photonics team at Pacific Northwest National Laboratory (PNNL) is focused on developing miniature spherical retroreflectors using the unique optical and material properties of chalcogenide glass to reduce both performance limiting spherical aberrations. The optimized optical performance will provide efficient signal retroreflection that enables a broad range of remote detection scenarios for mid-wave infrared (MWIR) and long-wave infrared (LWIR) sensing applications. Miniature spherical retroreflectors can be developed to aid in the detection of signatures of nuclear proliferation or other chemical vapor or radiation signatures. Miniature spherical retroreflectors are not only well suited to traditional LIDAR methods for chemical plume detection and identification, but could enable remote detection of difficult semi-volatile chemical materials or low level radiation sources.

  12. Compact Miniaturized Antenna for 210 MHz RFID

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Chun, Kue

    2008-01-01

    This paper describes the design and simulation of a miniaturized square-ring antenna. The miniaturized antenna, with overall dimensions of approximately one tenth of a wavelength (0.1 ), was designed to operate at around 210 MHz, and was intended for radio-frequency identification (RFID) application. One unique feature of the design is the use of a parasitic element to improve the performance and impedance matching of the antenna. The use of parasitic elements to enhance the gain and bandwidth of patch antennas has been demonstrated and reported in the literature, but such use has never been applied to miniaturized antennas. In this work, we will present simulation results and discuss design parameters and their impact on the antenna performance.

  13. Acral mutilation syndrome in a miniature pinscher.

    PubMed

    Bardagí, M; Montoliu, P; Ferrer, L; Fondevila, D; Pumarola, M

    2011-01-01

    Acral mutilation syndrome (AMS) is a rare canine hereditary sensory neuropathy that results in progressive mutilation of the distal extremities and which has been reported only in German short-haired pointers, English pointers, English springer spaniels and French spaniels. The present report describes a case of AMS in an 18-month-old female miniature pinscher with progressive self-mutilation of the hind feet. The dog did not respond to any treatment and was humanely destroyed at the age of 30 months. Microscopical findings post mortem were restricted to the nervous system and were compatible with AMS. This is the first case of AMS described in a miniature pinscher. It is not known if the disease was the result of a point mutation in this particular dog or if the miniature pinscher breed will evolve to become a breed predisposed to AMS.

  14. Fabrication method for miniature plastic gripper

    DOEpatents

    Benett, W.J.; Krulevitch, P.A.; Lee, A.P.; Northrup, M.A.; Folta, J.A.

    1998-07-21

    A miniature plastic gripper is described actuated by inflation of a miniature balloon and method of fabricating same. The gripper is constructed of either heat-shrinkable or heat-expandable plastic tubing and is formed around a mandrel, then cut to form gripper prongs or jaws and the mandrel removed. The gripper is connected at one end with a catheter or tube having an actuating balloon at its tip, whereby the gripper is opened or dosed by inflation or deflation of the balloon. The gripper is designed to removably retain a member to which is connected a quantity or medicine, plugs, or micro-components. The miniature plastic gripper is inexpensive to fabricate and can be used for various applications, such as gripping, sorting, or placing of micron-scale particles for analysis. 8 figs.

  15. Miniature plastic gripper and fabrication method

    DOEpatents

    Benett, William J.; Krulevitch, Peter A.; Lee, Abraham P.; Northrup, Milton A.; Folta, James A.

    1997-01-01

    A miniature plastic gripper actuated by inflation of a miniature balloon and method of fabricating same. The gripper is constructed of either heat-shrinkable or heat-expandable plastic tubing and is formed around a mandrel, then cut to form gripper prongs or jaws and the mandrel removed. The gripper is connected at one end with a catheter or tube having an actuating balloon at its tip, whereby the gripper is opened or closed by inflation or deflation of the balloon. The gripper is designed to removably retain a member to which is connected a quantity or medicine, plugs, or micro-components. The miniature plastic gripper is inexpensive to fabricate and can be used for various applications, such as gripping, sorting, or placing of micron-scale particles for analysis.

  16. Fabrication method for miniature plastic gripper

    DOEpatents

    Benett, William J.; Krulevitch, Peter A.; Lee, Abraham P.; Northrup, Milton A.; Folta, James A.

    1998-01-01

    A miniature plastic gripper actuated by inflation of a miniature balloon and method of fabricating same. The gripper is constructed of either heat-shrinkable or heat-expandable plastic tubing and is formed around a mandrel, then cut to form gripper prongs or jaws and the mandrel removed. The gripper is connected at one end with a catheter or tube having an actuating balloon at its tip, whereby the gripper is opened or dosed by inflation or deflation of the balloon. The gripper is designed to removably retain a member to which is connected a quantity or medicine, plugs, or micro-components. The miniature plastic gripper is inexpensive to fabricate and can be used for various applications, such as gripping, sorting, or placing of micron-scale particles for analysis.

  17. Miniature plastic gripper and fabrication method

    DOEpatents

    Benett, W.J.; Krulevitch, P.A.; Lee, A.P.; Northrup, M.A.; Folta, J.A.

    1997-03-11

    A miniature plastic gripper actuated by inflation of a miniature balloon and method of fabricating same are disclosed. The gripper is constructed of either heat-shrinkable or heat-expandable plastic tubing and is formed around a mandrel, then cut to form gripper prongs or jaws and the mandrel removed. The gripper is connected at one end with a catheter or tube having an actuating balloon at its tip, whereby the gripper is opened or closed by inflation or deflation of the balloon. The gripper is designed to removably retain a member to which is connected a quantity or medicine, plugs, or micro-components. The miniature plastic gripper is inexpensive to fabricate and can be used for various applications, such as gripping, sorting, or placing of micron-scale particles for analysis. 8 figs.

  18. Method and system for assembling miniaturized devices

    DOEpatents

    Montesanti, Richard C.; Klingmann, Jeffrey L.; Seugling, Richard M.

    2013-03-12

    An apparatus for assembling a miniaturized device includes a manipulator system including six manipulators operable to position and orient components of the miniaturized device with submicron precision and micron-level accuracy. The manipulator system includes a first plurality of motorized axes, a second plurality of manual axes, and force and torque and sensors. Each of the six manipulators includes at least one translation stage, at least one rotation stage, tooling attached to the at least one translation stage or the at least one rotation stage, and an attachment mechanism disposed at a distal end of the tooling and operable to attach at least a portion of the miniaturized device to the tooling. The apparatus also includes an optical coordinate-measuring machine (OCMM) including a machine-vision system, a laser-based distance-measuring probe, and a touch probe. The apparatus also includes an operator control system coupled to the manipulator system and the OCMM.

  19. FY 2005 Miniature Spherical Retroreflectors Final Report

    SciTech Connect

    Anheier, Norman C.; Bernacki, Bruce E.; Johnson, Bradley R.; Riley, Brian J.; Sliger, William A.

    2005-12-01

    Research done by the Infrared Photonics team at Pacific Northwest National Laboratory (PNNL) is focused on developing miniature spherical retroreflectors using the unique optical and material properties of chalcogenide glass to reduce both performance limiting spherical and chromatic aberrations. The optimized optical performance will provide efficient signal retroreflection that enables a broad range of remote detection scenarios for mid-wave infrared (MWIR) and long-wave infrared (LWIR) sensing applications. Miniature spherical retroreflectors can be developed to aid in the detection of signatures of nuclear proliferation or other chemical vapor or radiation signatures. Miniature spherical retroreflectors are not only well suited to traditional bistatic LIDAR methods for chemical plume detection and identification, but could enable remote detection of difficult semi-volatile chemical materials or low level radiation sources.

  20. Presynaptic miniature GABAergic currents in developing interneurons.

    PubMed

    Trigo, Federico F; Bouhours, Brice; Rostaing, Philippe; Papageorgiou, George; Corrie, John E T; Triller, Antoine; Ogden, David; Marty, Alain

    2010-04-29

    Miniature synaptic currents have long been known to represent random transmitter release under resting conditions, but much remains to be learned about their nature and function in central synapses. In this work, we describe a new class of miniature currents ("preminis") that arise by the autocrine activation of axonal receptors following random vesicular release. Preminis are prominent in gabaergic synapses made by cerebellar interneurons during the development of the molecular layer. Unlike ordinary miniature postsynaptic currents in the same cells, premini frequencies are strongly enhanced by subthreshold depolarization, suggesting that the membrane depolarization they produce belongs to a feedback loop regulating neurotransmitter release. Thus, preminis could guide the formation of the interneuron network by enhancing neurotransmitter release at recently formed synaptic contacts.

  1. Fatal methanol poisoning: features of liver histopathology.

    PubMed

    Akhgari, Maryam; Panahianpour, Mohammad Hadi; Bazmi, Elham; Etemadi-Aleagha, Afshar; Mahdavi, Amirhosein; Nazari, Saeed Hashemi

    2013-03-01

    Methanol poisoning has become a considerable problem in Iran. Liver can show some features of poisoning after methanol ingestion. Therefore, our concern was to examine liver tissue histopathology in fatal methanol poisoning cases in Iranian population. In this study, 44 cases of fatal methanol poisoning were identified in a year. The histological changes of the liver were reviewed. The most striking features of liver damage by light microscopy were micro-vesicular steatosis, macro-vesicular steatosis, focal hepatocyte necrosis, mild intra-hepatocyte bile stasis, feathery degeneration and hydropic degeneration. Blood and vitreous humor methanol concentrations were examined to confirm the proposed history of methanol poisoning. The majority of cases were men (86.36%). In conclusion, methanol poisoning can cause histological changes in liver tissues. Most importantly in cases with mean blood and vitreous humor methanol levels greater than 127 ± 38.9 mg/dL more than one pathologic features were detected.

  2. Injector spray characterization of methanol in reciprocating engines

    SciTech Connect

    Dodge, L.; Naegeli, D.

    1994-06-01

    This report covers a study that addressed cold-starting problems in alcohol-fueled, spark-ignition engines by using fine-spray port-fuel injectors to inject fuel directly into the cylinder. This task included development and characterization of some very fine-spray, port-fuel injectors for a methanol-fueled spark-ignition engine. After determining the spray characteristics, a computational study was performed to estimate the evaporation rate of the methanol fuel spray under cold-starting and steady-state conditions.

  3. Discovery of methanol electro-oxidation catalysts by combinatorial analysis

    SciTech Connect

    Mallouk, T.E.; Reddington, E.; Pu, C.

    1996-12-31

    Hydrogen fuel cells are likely to become a major energy source in the next century, but they are not ideal for all applications. A safe alternative fuel with a high energy density will be necessary for transportation and mobile applications. Direct methanol-air fuel cells (DMFCs) are an attractive alternative to hydrogen fuel cells because of the high energy density and low cost of methanol as a fuel. However, in order for DMFCs to become commercially viable, better electrocatalysts for the anode reaction need to be developed. This paper describes a combinatorial technique for generating an array of electrodes with varying metal compositions.

  4. Continuous flow nitration in miniaturized devices

    PubMed Central

    2014-01-01

    Summary This review highlights the state of the art in the field of continuous flow nitration with miniaturized devices. Although nitration has been one of the oldest and most important unit reactions, the advent of miniaturized devices has paved the way for new opportunities to reconsider the conventional approach for exothermic and selectivity sensitive nitration reactions. Four different approaches to flow nitration with microreactors are presented herein and discussed in view of their advantages, limitations and applicability of the information towards scale-up. Selected recent patents that disclose scale-up methodologies for continuous flow nitration are also briefly reviewed. PMID:24605161

  5. Jarvik 2000 pump technology and miniaturization.

    PubMed

    Jarvik, Robert

    2014-01-01

    Blood-pump miniaturization has made amazing progress, reducing the pump diameter to one-tenth of the size of previous positive displacement pumps. In particular, axial-flow-pump technology allows tiny pumps running at high speeds to deliver from 2 to 10 L/min. A review of the background inventions of the Jarvik 2000 technology is presented, together with the reason that making pumps smaller than demanded by the particular application for which they are designed is counterproductive. Pump miniaturization is nearing its practical limit. The optimization of performance and patient outcomes should remain our primary design goal.

  6. Batch fabrication of precision miniature permanent magnets

    DOEpatents

    Christenson, Todd R.; Garino, Terry J.; Venturini, Eugene L.

    2002-01-01

    A new class of processes for fabrication of precision miniature rare earth permanent magnets is disclosed. Such magnets typically have sizes in the range 0.1 to 10 millimeters, and dimensional tolerances as small as one micron. Very large magnetic fields can be produced by such magnets, lending to their potential application in MEMS and related electromechanical applications, and in miniature millimeter-wave vacuum tubes. This abstract contains simplifications, and is supplied only for purposes of searching, not to limit or alter the scope or meaning of any claims herein.

  7. Miniature rotating transmissive optical drum scanner

    NASA Technical Reports Server (NTRS)

    Lewis, Robert (Inventor); Parrington, Lawrence (Inventor); Rutberg, Michael (Inventor)

    2013-01-01

    A miniature rotating transmissive optical scanner system employs a drum of small size having an interior defined by a circumferential wall rotatable on a drum axis, an optical element positioned within the interior of the drum, and a light-transmissive lens aperture provided at an angular position in the circumferential wall of the drum for scanning a light beam to or from the optical element in the drum along a beam azimuth angle as the drum is rotated. The miniature optical drum scanner configuration obtains a wide scanning field-of-view (FOV) and large effective aperture is achieved within a physically small size.

  8. Miniature biotelemeter gives multichannel wideband biomedical data

    NASA Technical Reports Server (NTRS)

    Carraway, J. B.

    1972-01-01

    A miniature biotelemeter was developed for sensing and transmitting multiple channels of biomedical data over a radio link. The design of this miniature, 10-channel, wideband (5 kHz/channel), pulse amplitude modulation/ frequency modulation biotelemeter takes advantage of modern device technology (e.g., integrated circuit operational amplifiers, complementary symmetry/metal oxide semiconductor logic, and solid state switches) and hybrid packaging techniques. The telemeter is being used to monitor 10 channels of neuron firings from specific regions of the brain in rats implanted with chronic electrodes. Design, fabrication, and testing of an engineering model biotelemeter are described.

  9. Fermentation of methanol in the sheep rumen.

    PubMed

    Pol, A; Demeyer, D I

    1988-03-01

    Sheep fed a hay-concentrate diet were adapted to pectin administration and ruminal infusion of methanol. Both treatments resulted in a strong increase in the rate of methanogenesis from methanol. Quantitative data show that methanol was exclusively converted into methane. Treatments did not influence ruminal volatile fatty acid percentages.

  10. Methanol Uptake By Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    To evaluate the role of upper tropospheric and lower stratospheric aerosols in the global budget of methanol, the solubility and reactivity of CH3OH in aqueous sulfuric acid solutions are under investigation. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H(*), for methanol dissolution into 45 to 70 percent by weight H2SO4. We find that methanol solubility ranges from 10(exp 5) to 10(exp 8) M/atm and increases with decreasing temperature and with increasing sulfuric acid content. These solubility measurements include uptake due to physical solvation and all rapid equilibria which are established in solution. Our data indicate that simple uptake by aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These results differ from those recently reported in the literature, and an explanation of this disparity will be presented. In addition to solvation, reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H may proceed in the atmosphere but is not significant under our experimental conditions. Results obtained using a complementary equilibrium measurement technique confirm this directly. In addition, the extent of methanol sequestration via formation of mono- and dimethylsulfate will be evaluated under several atmospheric conditions.

  11. Observations of the Zeeman effect in Class I methanol masers

    NASA Astrophysics Data System (ADS)

    Pratim Sarma, Anuj; Momjian, Emmanuel

    2017-01-01

    We present observations of the Zeeman effect in Class I methanol maser sources toward high mass star forming regions. Toward DR21(OH), we have detected the Zeeman effect at 44 GHz in a 219 Jy/beam maser centered at an LSR velocity of 0.83 km/s, and we find $zB_\\text{los} = 53.5 \\pm 2.7$ Hz. If 44 GHz methanol masers are excited at $10^{7-8}$ cm$^{-3}$, then magnetic fields in DR21(OH) should be ~10 mG. Our detected $zB_\\text{los}$ would then imply that the Zeeman splitting factor for the 44 GHz methanol maser line should be ~5 Hz/mG. Such small values for z would not be surprising, since the methanol molecule is non-paramagnetic, like H2O. Since there are no direct measurements or calculations of the 44 GHz methanol maser Zeeman splitting factor to date, such empirical attempts could prove valuable in building a repository of measurements from which to gain an understanding of the magnitude of z.

  12. A bottom-up perspective of the net land methanol flux: synthesis of global eddy covariance flux measurements

    NASA Astrophysics Data System (ADS)

    Wohlfahrt, Georg; Amelynck, Crist; Ammann, Christof; Arneth, Almut; Bamberger, Ines; Goldstein, Allen; Hansel, Armin; Heinesch, Bernhard; Holst, Thomas; Hörtnagl, Lukas; Karl, Thomas; Neftel, Albrecht; McKinney, Karena; Munger, William; Schade, Gunnar; Schoon, Niels

    2014-05-01

    Methanol (CH3OH) is, after methane, the second most abundant VOC in the troposphere and globally represents nearly 20% of the total biospheric VOC emissions. With typical concentrations of 1-10 ppb in the continental boundary layer, methanol plays a crucial role in atmospheric chemistry, which needs to be evaluated in the light of ongoing changes in land use and climate. Previous global methanol budgets have approached the net land flux by summing up the various emission terms (namely primary biogenic and anthropogenic emissions, plant decay and biomass burning) and by subtracting dry and wet deposition, resulting in a net land flux in the range of 75-245 Tg y-1. The data underlying these budget calculations largely stem from small-scale leaf gas exchange measurements and while recently column-integrated remotely sensed methanol concentrations have become available for constraining budget calculations, there have been few attempts to contrast model calculations with direct net ecosystem-scale methanol flux measurements. Here we use eddy covariance methanol flux measurements from 8 sites in Europe and North America to study the magnitude of and controls on the diurnal and seasonal variability in the net ecosystem methanol flux. In correspondence with leaf-level literature, our data show that methanol emission and its strong environmental and biotic control (by temperature and stomatal conductance) prevailed at the more productive (agricultural) sites and at a perturbed forest site. In contrast, at more natural, less productive sites substantial deposition of methanol occurred, in particular during periods of surface wetness. These deposition processes are poorly represented by currently available temperature/light and/or production-driven modelling algorithms. A new framework for modelling the bi-directional land-atmosphere methanol exchange is proposed which accounts for the production of methanol in leaves, the regulation of leaf methanol emission by stomatal

  13. Development and in vitro testing of a miniature robotic system for computer-assisted colonoscopy.

    PubMed

    Dario, P; Carrozza, M C; Pietrabissa, A

    1999-01-01

    In this article we present a new concept for computer-assisted colonoscopy based on a miniature robot capable of propelling itself semiautonomously along the colon. The miniature robot is designed to perform the same functions as current colonoscopy systems-i.e., visualization and tissue sampling for biopsy-and exploits an innovative inchworm-like locomotion principle based on adhering to the colon wall by vacuum suction. The miniature robot is connected by a thin and flexible umbilical cable to an external control unit; this unit provides pneumatic actuation signals in the appropriate sequence to the miniature robot, and information on the robot's functioning to the endoscopist, who can either teleoperate or directly supervise its operation. A prototype colonoscopy system using this robot has been fabricated and tested in vitro, with promising results. The proposed concept has strong potential for further development, since miniaturization and functional integration of instrumentation and tools, together with computer assistance, not only make colonoscopy more acceptable, but can also open up a wide range of new applications in endoluminal diagnosis, therapy, and surgery.

  14. A novel process for methanol synthesis

    SciTech Connect

    Tierney, J.W.; Wender, I.

    1990-01-01

    A bench-salce reactor is being used to conduct studies of the conversion of synthesis gas to methanol by a novel process. During the last quarter, we investigated the nature of the reactions involved and the nature of the Cu-chromite catalyst being used. There is evidence that methanol is formed via a two step reaction with a methyl formate intermediate rather than by the direct hydrogenation of CO. The carbonylation reaction predominantly takes place in the liquid phase while the hydrogenolysis reaction is restricted to the surface of Cu-chromite. At steady state, the carbonylation reaction taking place in the region close to the Cu-chromite surface is probably the main source of MeF. This model also explains the increased tolerance of the process to CO. A mechanistic model is proposed to explain the interaction of different species in the reaction mixture. The topography of the Cu-chromite surface is also investigated by X-ray diffraction and scanning electron microscopy. 15 refs., 5 figs., 1 tab.

  15. Evidence for Conversion of Methanol to Formaldehyde in Nonhuman Primate Brain.

    PubMed

    Zhai, Rongwei; Zheng, Na; Rizak, Joshua; Hu, Xintian

    2016-01-01

    Many studies have reported that methanol toxicity to primates is mainly associated with its metabolites, formaldehyde (FA) and formic acid. While methanol metabolism and toxicology have been best studied in peripheral organs, little study has focused on the brain and no study has reported experimental evidence that demonstrates transformation of methanol into FA in the primate brain. In this study, three rhesus macaques were given a single intracerebroventricular injection of methanol to investigate whether a metabolic process of methanol to FA occurs in nonhuman primate brain. Levels of FA in cerebrospinal fluid (CSF) were then assessed at different time points. A significant increase of FA levels was found at the 18th hour following a methanol injection. Moreover, the FA level returned to a normal physiological level at the 30th hour after the injection. These findings provide direct evidence that methanol is oxidized to FA in nonhuman primate brain and that a portion of the FA generated is released out of the brain cells. This study suggests that FA is produced from methanol metabolic processes in the nonhuman primate brain and that FA may play a significant role in methanol neurotoxicology.

  16. Monocular-Vision-Based Autonomous Hovering for a Miniature Flying Ball

    PubMed Central

    Lin, Junqin; Han, Baoling; Luo, Qingsheng

    2015-01-01

    This paper presents a method for detecting and controlling the autonomous hovering of a miniature flying ball (MFB) based on monocular vision. A camera is employed to estimate the three-dimensional position of the vehicle relative to the ground without auxiliary sensors, such as inertial measurement units (IMUs). An image of the ground captured by the camera mounted directly under the miniature flying ball is set as a reference. The position variations between the subsequent frames and the reference image are calculated by comparing their correspondence points. The Kalman filter is used to predict the position of the miniature flying ball to handle situations, such as a lost or wrong frame. Finally, a PID controller is designed, and the performance of the entire system is tested experimentally. The results show that the proposed method can keep the aircraft in a stable hover. PMID:26057040

  17. Monocular-Vision-Based Autonomous Hovering for a Miniature Flying Ball.

    PubMed

    Lin, Junqin; Han, Baoling; Luo, Qingsheng

    2015-06-05

    This paper presents a method for detecting and controlling the autonomous hovering of a miniature flying ball (MFB) based on monocular vision. A camera is employed to estimate the three-dimensional position of the vehicle relative to the ground without auxiliary sensors, such as inertial measurement units (IMUs). An image of the ground captured by the camera mounted directly under the miniature flying ball is set as a reference. The position variations between the subsequent frames and the reference image are calculated by comparing their correspondence points. The Kalman filter is used to predict the position of the miniature flying ball to handle situations, such as a lost or wrong frame. Finally, a PID controller is designed, and the performance of the entire system is tested experimentally. The results show that the proposed method can keep the aircraft in a stable hover.

  18. Miniaturized Raman instrumentation detects carotenoids in Mars-analogue rocks from the Mojave and Atacama deserts.

    PubMed

    Vítek, P; Jehlička, J; Edwards, H G M; Hutchinson, I; Ascaso, C; Wierzchos, J

    2014-12-13

    This study is primarily focused on proving the potential of miniaturized Raman systems to detect any biomolecular and mineral signal in natural geobiological samples that are relevant for future application of the technique within astrobiologically aimed missions on Mars. A series of evaporites of varying composition and origin from two extremely dry deserts were studied, namely Atacama and Mojave. The samples represent both dry evaporitic deposits and recent evaporitic efflorescences from hypersaline brines. The samples comprise halite and different types of sulfates and carbonates. The samples were analysed in two different ways: (i) directly as untreated rocks and (ii) as homogenized powders. Two excitation wavelengths of miniaturized Raman spectrometers were compared: 532 and 785 nm. The potential to detect carotenoids as biomarkers on Mars compared with the potential detection of carbonaceous matter using miniaturized instrumentation is discussed.

  19. Miniature Surface Plasmon Polariton Amplitude Modulator by Beat Frequency and Polarization Control

    PubMed Central

    Chang, Cheng-Wei; Lin, Chu-En; Yu, Chih-Jen; Yeh, Ting-Tso; Yen, Ta-Jen

    2016-01-01

    The miniaturization of modulators keeps pace for the compact devices in optical applications. Here, we present a miniature surface plasmon polariton amplitude modulator (SPPAM) by directing and interfering surface plasmon polaritons on a nanofabricated chip. Our results show that this SPPAM enables two kinds of modulations. The first kind of modulation is controlled by encoding angular-frequency difference from a Zeeman laser, with a beat frequency of 1.66 MHz; the second of modulation is validated by periodically varying the polarization states from a polarization generator, with rotation frequencies of 0.5–10 k Hz. In addition, the normalized extinction ratio of our plasmonic structure reaches 100. Such miniaturized beat-frequency and polarization-controlled amplitude modulators open an avenue for the exploration of ultrasensitive nanosensors, nanocircuits, and other integrated nanophotonic devices. PMID:27558516

  20. Two Views of Islam: Ceramic Tile Design and Miniatures.

    ERIC Educational Resources Information Center

    Macaulay, Sara Grove

    2001-01-01

    Describes an art project focusing on Islamic art that consists of two parts: (1) ceramic tile design; and (2) Islamic miniatures. Provides background information on Islamic art and step-by-step instructions for designing the Islamic tile and miniature. Includes learning objectives and resources on Islamic tile miniatures. (CMK)

  1. 21 CFR 890.1615 - Miniature pressure transducer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Miniature pressure transducer. 890.1615 Section... Miniature pressure transducer. (a) Identification. A miniature pressure transducer is a device intended for medical purposes to measure the pressure between a device and soft tissue by converting mechanical...

  2. 21 CFR 890.1615 - Miniature pressure transducer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Miniature pressure transducer. 890.1615 Section... Miniature pressure transducer. (a) Identification. A miniature pressure transducer is a device intended for medical purposes to measure the pressure between a device and soft tissue by converting mechanical...

  3. Methanol induces low temperature resilient methanogens and improves methane generation from domestic wastewater at low to moderate temperatures.

    PubMed

    Saha, Shaswati; Badhe, Neha; De Vrieze, Jo; Biswas, Rima; Nandy, Tapas

    2015-01-01

    Low temperature (<20 °C) limits bio-methanation of sewage. Literature shows that hydrogenotrophic methanogens can adapt themselves to low temperature and methanol is a preferred substrate by methanogens in cold habitats. The study hypothesizes that methanol can induce the growth of low-temperature resilient, methanol utilizing, hydrogenotrophs in UASB reactor. The hypothesis was tested in field conditions to evaluate the impact of seasonal temperature variations on methane yield in the presence and absence of methanol. Results show that 0.04% (v/v) methanol increased methane up to 15 times and its effect was more pronounced at lower temperatures. The qPCR analysis showed the presence of Methanobacteriales along with Methanosetaceae in large numbers. This indicates methanol induced the growth of both the hydrogenotrophic and acetoclastic groups through direct and indirect routes, respectively. This study thus demonstrated that methanol can impart resistance in methanogenic biomass to low temperature and can improve performance of UASB reactor.

  4. Methanol production method and system

    DOEpatents

    Chen, Michael J.; Rathke, Jerome W.

    1984-01-01

    Ethanol is selectively produced from the reaction of methanol with carbon monoxide and hydrogen in the presence of a transition metal carbonyl catalyst. Methanol serves as a solvent and may be accompanied by a less volatile co-solvent. The solution includes the transition metal carbonyl catalysts and a basic metal salt such as an alkali metal or alkaline earth metal formate, carbonate or bicarbonate. A gas containing a high carbon monoxide to hydrogen ratio, as is present in a typical gasifer product, is contacted with the solution for the preferential production of ethanol with minimal water as a byproduct. Fractionation of the reaction solution provides substantially pure ethanol product and allows return of the catalysts for reuse.

  5. Miniature Housings for Electronics With Standard Interfaces

    NASA Technical Reports Server (NTRS)

    Howard, David E.; Smith, Dennis A.; Alhorn, Dean C.

    2006-01-01

    A family of general-purpose miniature housings has been designed to contain diverse sensors, actuators, and drive circuits plus associated digital electronic readout and control circuits. The circuits contained in the housings communicate with the external world via standard RS-485 interfaces.

  6. The technology of miniature acoustic element arrays

    NASA Technical Reports Server (NTRS)

    Bom, N.; Lancee, C. T.; Ridder, J.; Ligtvoet, C.; Roelandt, J.

    1975-01-01

    Various aspects of miniature element array construction are discussed. Some initial results on optimization of lateral resolution with a special focusing technique in linear array design is presented, together with the constructional details. Furthermore the construction of a catheter tip array is treated in detail.

  7. Miniaturization of a biomedical gas sensor.

    PubMed

    Mirtaheri, Peyman; Omtveit, Tore; Klotzbuecher, Thomas; Grimnes, Sverre; Martinsen, Orjan G; Tønnessen, Tor Inge

    2004-12-01

    In a previous study, we concluded that a conductivity based PCO2 sensor is an attractive solution for early detection of ischemia and presented two design geometries. For organ surface measurements, the planar design was suitable but it was difficult to insert the sensor into the tissue. A cylindrical design solution was favored for insertion due to the large membrane contact area and easy placement in a medical catheter. Since the previous cylindrical prototype was large and could damage the tissue, a more miniaturized sensor was needed. In the current paper, we present a miniaturized sensor with an outer diameter of 1 mm. The applied technology for manufacturing the sensor was a combination of mechanical turning, excimer laser drilling and conventional molding technique. The materials applied were PEEK (polyetherether ketone), PI (polyimide) with gold layers and polysiloxane. The membrane had to be gas permeable while acting as a barrier for ion transport, and was made of polysiloxane and had a thickness of 100-150 microm. The miniaturized sensor was tested for calibration, response time, drifting and pressure sensitivity. The results show that the miniaturized PCO2 sensor is capable of rapid and stable measurements both in vitro and ex vivo. The result from this study will be applied for the industrial manufacturing of such a biomedical sensor as a clinical product.

  8. A miniature mass spectrometer for hydrazine detection

    NASA Technical Reports Server (NTRS)

    Houseman, J.; Sinha, M. P.

    2003-01-01

    A Miniature Mass Spectrometer (MMS) with a focal plane (Mattauch-Herzog) geometry has been developed at the Jet Propulsion Laboratory. The MMS has the potential to meet the NASA requirements of 10 parts per billion sensitivity for Hydrazine detection, as well as the requirements for instant response, portability, and low maintenance.

  9. Miniature Paintings: Small Size, Big Impact!

    ERIC Educational Resources Information Center

    Hicks, Bill

    2011-01-01

    This article describes a miniature painting project that allows students to research a master painter and then replicate the work on a smaller scale. This lesson focuses on the students' ability to learn to identify style, subject matter, themes, and content in painting through the study of historical paintings, and the application of various…

  10. Miniature Marimbas: Migrant Workers' Memories of Home.

    ERIC Educational Resources Information Center

    Howell, Jayne

    1995-01-01

    Three Mexican migrant workers attending classes at Geneseo (New York) Migrant Center used leftover art materials to represent their home village in miniature. A spontaneous artistic expression, the objects allowed the men an opportunity to reminisce and reinforce cultural and interpersonal ties, and gave insight about their background and culture…

  11. Heterogeneous Chemistry Involving Methanol in Tropospheric Clouds

    NASA Technical Reports Server (NTRS)

    Tabazadeh, A.; Yokelson, R. J.; Singh, H. B.; Hobbs, P. V.; Crawford, J. H.; Iraci, L. T.

    2004-01-01

    In this report we analyze airborne measurements to suggest that methanol in biomass burning smoke is lost heterogeneously in clouds. When a smoke plume intersected a cumulus cloud during the SAFARI 2000 field project, the observed methanol gas phase concentration rapidly declined. Current understanding of gas and aqueous phase chemistry cannot explain the loss of methanol documented by these measurements. Two plausible heterogeneous reactions are proposed to explain the observed simultaneous loss and production of methanol and formaldehyde, respectively. If the rapid heterogeneous processing of methanol, seen in a cloud impacted by smoke, occurs in more pristine clouds, it could affect the oxidizing capacity of the troposphere on a global scale.

  12. Trinidad to build fifth methanol plant

    SciTech Connect

    1997-04-09

    Lurgi confirms it has been awarded a lump sum turnkey contract to build Trinidad`s fifth methanol plant. The facility will be owned by Titan Methanol, whose shareholders are Beacon Group Energy Investment Fund (75%) Amoco Chemical (15%), and Saturn Methanol (10%). The 2,500-m.t./day unit at Point Lisas, which is scheduled to come onstream at the end of 1999, will be Trinidad`s largest methanol unit. Saturn Methanol will be responsible for methanol offtake. Lurgi will use its combined reforming process for the gas section of the unit and its low-pressure methanol synthesis technology. Lurgi has used the same processes in plants in Malaysia and Indonesia.

  13. The toxicity of inhaled methanol vapors

    SciTech Connect

    Kavet, R.; Nauss, K.M. )

    1990-01-01

    Methanol could become a major automotive fuel in the U.S., and its use may result in increased exposure of the public to methanol vapor. Nearly all of the available information on methanol toxicity in humans relates to the consequences of acute, rather than chronic, exposures. Acute methanol toxicity evolves in a well-understood pattern and consists of an uncompensated metabolic acidosis with superimposed toxicity to the visual system. The toxic properties of methanol are rooted in the factors that govern both the conversion of methanol to formic acid and the subsequent metabolism of formate to carbon dioxide in the folate pathway. In short, the toxic syndrome sets in if formate generation continues at a rate that exceeds its rate of metabolism. Current evidence indicates that formate accumulation will not challenge the metabolic capacity of the folate pathway at the anticipated levels of exposure to automotive methanol vapor.117 references.

  14. Miniature Scroll Pumps Fabricated by LIGA

    NASA Technical Reports Server (NTRS)

    Wiberg, Dean; Shcheglov, Kirill; White, Victor; Bae, Sam

    2009-01-01

    Miniature scroll pumps have been proposed as roughing pumps (low - vacuum pumps) for miniature scientific instruments (e.g., portable mass spectrometers and gas analyzers) that depend on vacuum. The larger scroll pumps used as roughing pumps in some older vacuum systems are fabricated by conventional machining. Typically, such an older scroll pump includes (1) an electric motor with an eccentric shaft to generate orbital motion of a scroll and (2) conventional bearings to restrict the orbital motion to a circle. The proposed miniature scroll pumps would differ from the prior, larger ones in both design and fabrication. A miniature scroll pump would include two scrolls: one mounted on a stationary baseplate and one on a flexure stage (see figure). An electromagnetic actuator in the form of two pairs of voice coils in a push-pull configuration would make the flexure stage move in the desired circular orbit. The capacitance between the scrolls would be monitored to provide position (gap) feedback to a control system that would adjust the drive signals applied to the voice coils to maintain the circular orbit as needed for precise sealing of the scrolls. To minimize power consumption and maximize precision of control, the flexure stage would be driven at the frequency of its mechanical resonance. The miniaturization of these pumps would entail both operational and manufacturing tolerances of <1 m. Such tight tolerances cannot be achieved easily by conventional machining of high-aspect-ratio structures like those of scroll-pump components. In addition, the vibrations of conventional motors and ball bearings exceed these tight tolerances by an order of magnitude. Therefore, the proposed pumps would be fabricated by the microfabrication method known by the German acronym LIGA ( lithographie, galvanoformung, abformung, which means lithography, electroforming, molding) because LIGA has been shown to be capable of providing the required tolerances at large aspect ratios.

  15. Miniature Grating for Spectrally-Encoded Endoscopy

    PubMed Central

    Kang, Dongkyun; Martinez, Ramses V.; Whitesides, George M.

    2013-01-01

    Spectrally-encoded endoscopy (SEE) is an ultraminiature endoscopy technology that acquires high-definition images of internal organs through a sub-mm endoscopic probe. In SEE, a grating at the tip of the imaging optics diffracts the broadband light into multiple beams, where each beam with a distinctive wavelength is illuminated on a unique transverse location of the tissue. By encoding one transverse coordinate with the wavelength, SEE can image a line of the tissue at a time without using any beam scanning devices. This feature of the SEE technology allows the SEE probe to be miniaturized to sub-mm dimensions. While previous studies have shown that SEE has the potential to be utilized for various clinical imaging applications, the translation of SEE for medicine has been hampered by challenges in fabricating the miniature grating inherent to SEE probes. This paper describes a new fabrication method for SEE probes. The new method uses a soft lithographic approach to pattern a high-aspect-ratio grating at the tip of the miniature imaging optics. Using this technique, we have constructed a 500-μm-diameter SEE probe. The miniature grating at the tip of the probe had a measured diffraction efficiency of 75%. The new SEE probe was used to image a human finger and formalin fixed mouse embryos, demonstrating the capability of this device to visualize key anatomic features of tissues with high image contrast. In addition to providing high quality imaging SEE optics, the soft lithography method allows cost-effective and reliable fabrication of these miniature endoscopes, which will facilitate the clinical translation of SEE technology. PMID:23503940

  16. Multiple stage miniature stepping motor

    DOEpatents

    Niven, William A.; Shikany, S. David; Shira, Michael L.

    1981-01-01

    A stepping motor comprising a plurality of stages which may be selectively activated to effect stepping movement of the motor, and which are mounted along a common rotor shaft to achieve considerable reduction in motor size and minimum diameter, whereby sequential activation of the stages results in successive rotor steps with direction being determined by the particular activating sequence followed.

  17. Towards designing miniature surfing robots

    NASA Astrophysics Data System (ADS)

    Jafari Kang, Saeed; Vandadi, Vahid; Masoud, Hassan

    2016-11-01

    We theoretically study the surfing motion of chemically and thermally active particles located at a flat liquid-gas interface that sits above a liquid layer of finite depth. The particles' activity creates and maintains a surface tension gradient resulting in the auto-surfing. It is intuitively perceived that Marangoni surfers propel towards the direction with a higher surface tension. Remarkably, we find that the surfers may propel in the lower surface tension direction depending on their geometry and proximity to the bottom of the liquid layer. In particular, our analytical calculations for Stokes flow and diffusion-dominated scalar (i.e. chemical concentration and temperature) fields indicate that spherical particles undergo reverse Marangoni propulsion under confinement whereas disk-shaped surfers always move in the expected direction. We extend our results by proposing an approximate formula for the propulsion speed of oblate spheroidal particles based on the speeds of spheres and disks. Overall, our findings pave the way for designing microsurfers capable of operating in bounded environments.

  18. Miniature electron microscope beam column optics

    NASA Astrophysics Data System (ADS)

    Loyd, Jody Stuart

    This investigation is in the area of electrostatic lens design with the overarching goal of contributing to the creation of a miniaturized scanning electron microscope (SEM) for use in mineralogical analysis or detection of signs of life on the surface of Mars. Such an instrument could also have application in the exploration of Earth's moon, planetary moons, asteroids, or comets. Other embodiments could include tabletop or field portable SEMs for use on Earth. The scope of this research is in the design of a beam column that attains focusing, demagnification, and aberration control within the smallest achievable package. The goals of planetary exploration and of spaceflight in general impose severe constraints on the instrument's mass and electrical power consumption, while favoring a robust design of small size and high rigidity that is also simple to align. To meet these requirements a design using electrostatic lenses was favored because of the lower power requirement and mass of electrostatic versus magnetic lenses, their relatively simple construction, as well as inherently easier shielding from extraneous fields. In modeling the lens field, a hybrid of a Boundary Element Method (BEM) and a Fourier series solution was employed, whereby an initial solution from the BEM is used to derive the bounding potential of a cylindrical subdomain for the subsequent Fourier series solution. The approach is applicable to many problems in physics and combines the inherent precision of this series solution with the flexibility of BEM to describe practical, non-idealized electrode shapes. The resulting lens field in the Fourier series subdomain is of higher precision, thereby allowing smaller errors in subsequent calculations of electron ray paths. The effects of aberrations are thus easier to observe in tracing non-paraxial rays. A significant speed increase in tracing rays is also observed. The modeling technique has been validated by reproducing example ray-traces through

  19. Interrogation of electrical connector faults using miniaturized UWB sources

    NASA Astrophysics Data System (ADS)

    Tokgöz, Çaǧata; Dardona, Sameh

    2017-01-01

    A diagnostic method for the detection, identification, and characterization of precursors of faults due to partial insertion of pin-socket contacts within electrical connectors commonly used in avionics systems is presented. It is demonstrated that a miniaturized ultrawideband (UWB) source and a minispectrum analyzer can be employed to measure resonant frequency shifts in connector S parameters as a small and low-cost alternative to a large and expensive network analyzer. The transfer function of an electrical connector is represented as a ratio of the spectra measured using the spectrum analyzer with and without the connector. Alternatively, the transfer function is derived in terms of the connector S parameters and the reflection coefficients at both ports of the connector. The transfer function data obtained using this derivation agreed well with its representation as a measured spectral ratio. The derivation enabled the extraction of the connector S parameters from the measured transfer function data as a function of the insertion depth of a pin-socket contact within the connector. In comparison with the S parameters measured directly using a network analyzer at multiple insertion depths, the S parameters extracted from the measured transfer function showed consistent and reliable representation of the electrical connector fault. The results demonstrate the potential of integrating a low-cost miniaturized UWB device into a connector harness for real-time detection of precursors to partially inserted connector faults.

  20. Metabolic methanol: molecular pathways and physiological roles.

    PubMed

    Dorokhov, Yuri L; Shindyapina, Anastasia V; Sheshukova, Ekaterina V; Komarova, Tatiana V

    2015-04-01

    Methanol has been historically considered an exogenous product that leads only to pathological changes in the human body when consumed. However, in normal, healthy individuals, methanol and its short-lived oxidized product, formaldehyde, are naturally occurring compounds whose functions and origins have received limited attention. There are several sources of human physiological methanol. Fruits, vegetables, and alcoholic beverages are likely the main sources of exogenous methanol in the healthy human body. Metabolic methanol may occur as a result of fermentation by gut bacteria and metabolic processes involving S-adenosyl methionine. Regardless of its source, low levels of methanol in the body are maintained by physiological and metabolic clearance mechanisms. Although human blood contains small amounts of methanol and formaldehyde, the content of these molecules increases sharply after receiving even methanol-free ethanol, indicating an endogenous source of the metabolic methanol present at low levels in the blood regulated by a cluster of genes. Recent studies of the pathogenesis of neurological disorders indicate metabolic formaldehyde as a putative causative agent. The detection of increased formaldehyde content in the blood of both neurological patients and the elderly indicates the important role of genetic and biochemical mechanisms of maintaining low levels of methanol and formaldehyde.

  1. Miniature Heat Transport System for Nanosatellite Technology

    NASA Technical Reports Server (NTRS)

    Douglas, Donya M,

    1999-01-01

    The scientific understanding of key physical processes between the Sun and the Earth require simultaneous measurements from many vantage points in space. Nano-satellite technologies will enable a class of constellation missions for the NASA Space Science Sun-Earth Connections. This recent emphasis on the implementation of smaller satellites leads to a requirement for development of smaller subsystems in several areas. Key technologies under development include: advanced miniaturized chemical propulsion; miniaturized sensors; highly integrated, compact electronics; autonomous onboard and ground operations; miniatures low power tracking techniques for orbit determination; onboard RF communications capable of transmitting data to the ground from far distances; lightweight efficient solar array panels; lightweight, high output battery cells; lightweight yet strong composite materials for the nano-spacecraft and deployer-ship structures. These newer smaller systems may have higher power densities and higher thermal transport requirements than seen on previous small satellites. Furthermore, the small satellites may also have a requirement to maintain thermal control through extended earth shadows, possibly up to 8 hours long. Older thermal control technology, such as heaters, thermostats, and heat pipes, may not be sufficient to meet the requirements of these new systems. Conversely, a miniature two-phase heat transport system (Mini-HTS) such as a Capillary Pumped Loop (CPL) or Loop Heat Pipe (LBP) is a viable alternative. A Mini-HTS can provide fine temperature control, thermal diode action, and a highly efficient means of heat transfer. The Mini-HTS would have power capabilities in the range of tens of watts or less and provide thermal control over typical spacecraft ranges. The Mini-HTS would allow the internal portion of the spacecraft to be thermally isolated from the external radiator, thus protecting the internal components from extreme cold temperatures during an

  2. Millimeter/submillimeter Spectroscopy to Measure the Branching Ratios for Methanol Photolysis

    NASA Astrophysics Data System (ADS)

    McCabe, Morgan N.; Powers, Carson Reed; Zinga, Samuel; Widicus Weaver, Susanna L.

    2016-06-01

    Methanol is one of the most abundant and important molecules in the interstellar medium, playing a key role in driving more complex organic chemistry both on grain surfaces and through gas-phase ion-molecule reactions. Methanol photolysis produces many radicals such as hydroxyl, methoxy, hydroxymethyl, and methyl that may serve as the building blocks for more complex organic chemistry in star-forming regions. The branching ratios for methanol photolysis may govern the relative abundances of many of the more complex species already detected in these environments. However, no direct, comprehensive, quantitative measurement of methanol photolysis branching ratios is available. Using a 193 nm excimer laser, the gas phase photolysis of methanol was studied in the (sub)millimeter range, where the rotational spectroscopic signatures of the photolysis products were probed. Here we present preliminary results from this experiment.

  3. Research Progress on the Indirect Hydrogenation of Carbon Dioxide to Methanol.

    PubMed

    Du, Xian-Long; Jiang, Zheng; Su, Dang Sheng; Wang, Jian-Qiang

    2016-02-19

    Methanol is a sustainable source of liquid fuels and one of the most useful organic chemicals. To date, most of the work in this area has focused on the direct hydrogenation of CO2 to methanol. However, this process requires high operating temperatures (200-250 °C), which limits the theoretical yield of methanol. Thus, it is desirable to find a new strategy for the efficient conversion of CO2 to methanol at relatively low reaction temperatures. This Minireview seeks to outline the recent advances on the indirect hydrogenation of CO2 to methanol. Much emphasis is placed on discussing specific systems, including hydrogenation of CO2 derivatives (organic carbonates, carbamates, formates, cyclic carbonates, etc.) and cascade reactions, with the aim of critically highlighting both the achievements and remaining challenges associated with this field.

  4. Towards a methanol economy based on homogeneous catalysis: methanol to H2 and CO2 to methanol.

    PubMed

    Alberico, E; Nielsen, M

    2015-04-21

    The possibility to implement both the exhaustive dehydrogenation of aqueous methanol to hydrogen and CO2 and the reverse reaction, the hydrogenation of CO2 to methanol and water, may pave the way to a methanol based economy as part of a promising renewable energy system. Recently, homogeneous catalytic systems have been reported which are able to promote either one or the other of the two reactions under mild conditions. Here, we review and discuss these developments.

  5. Miniature sensor suitable for electronic nose applications

    NASA Astrophysics Data System (ADS)

    Pinnaduwage, Lal A.; Gehl, Anthony C.; Allman, Steve L.; Johansson, Alicia; Boisen, Anja

    2007-05-01

    A major research effort has been devoted over the years for the development of chemical sensors for the detection of chemical and explosive vapors. However, the deployment of such chemical sensors will require the use of multiple sensors (probably tens of sensors) in a sensor package to achieve selective detection. In order to keep the overall detector unit small, miniature sensors with sufficient sensitivity of detection will be needed. We report sensitive detection of dimethyl methylphosphonate (DMMP), a stimulant for the nerve agents, using a miniature sensor unit based on piezoresistive microcantilevers. The sensor can detect parts-per-trillion concentrations of DMMP within 10s exposure times. The small size of the sensor makes it ideally suited for electronic nose applications.

  6. SMARBot: a modular miniature mobile robot platform

    NASA Astrophysics Data System (ADS)

    Meng, Yan; Johnson, Kerry; Simms, Brian; Conforth, Matthew

    2008-04-01

    Miniature robots have many advantages over their larger counterparts, such as low cost, low power, and easy to build a large scale team for complex tasks. Heterogeneous multi miniature robots could provide powerful situation awareness capability due to different locomotion capabilities and sensor information. However, it would be expensive and time consuming to develop specific embedded system for different type of robots. In this paper, we propose a generic modular embedded system architecture called SMARbot (Stevens Modular Autonomous Robot), which consists of a set of hardware and software modules that can be configured to construct various types of robot systems. These modules include a high performance microprocessor, a reconfigurable hardware component, wireless communication, and diverse sensor and actuator interfaces. The design of all the modules in electrical subsystem, the selection criteria for module components, and the real-time operating system are described. Some proofs of concept experimental results are also presented.

  7. Miniature, Variable-Speed Control Moment Gyroscope

    NASA Technical Reports Server (NTRS)

    Bilski, Steve; Kline-Schoder, Robert; Sorensen, Paul

    2011-01-01

    The Miniature Variable-Speed Control Moment Gyroscope (MVS-CMG) was designed for small satellites (mass from less than 1 kg up to 500 kg). Currently available CMGs are too large and heavy, and available miniature CMGs do not provide sufficient control authority for use on practical satellites. This primarily results from the need to greatly increase the speed of rotation of the flywheel in order to reduce the flywheel size and mass. This goal was achieved by making use of a proprietary, space-qualified, high-speed (100,000 rpm) motor technology to spin the flywheel at a speed ten times faster than other known miniature CMGs under development. NASA is supporting innovations in propulsion, power, and guidance and navigation systems for low-cost small spacecraft. One of the key enabling technologies is attitude control mechanisms. CMGs are particularly attractive for spacecraft attitude control since they can achieve higher torques with lower mass and power than reaction wheels, and they provide continuous torque capability that enables precision pointing (in contrast to on-off thruster control). The aim of this work was to develop a miniature, variable-speed CMG that is sized for use on small satellites. To achieve improved agility, these spacecraft must be able to slew at high rate, which requires attitude control actuators that can apply torques on the order of 5 N-m. The MVS-CMG is specifically designed to achieve a high-torque output with a minimum flywheel and system mass. The flywheel can be run over a wide range of speeds, which is important to help reduce/eliminate potential gimbal lock, and can be used to optimize the operational envelope of the CMG.

  8. Degenerative myelopathy in an adult miniature poodle.

    PubMed

    Matthews, N S; de Lahunta, A

    1985-06-01

    Degenerative myelopathy was diagnosed at necropsy of an adult Miniature Poodle with a 33-month history of progressive pelvic limb ataxia and proprioceptive deficit. Microscopic examination of the cord revealed diffuse degenerative myelopathy. Degenerative myelopathy is usually seen in adult, large-breed dogs and progresses over a period of months. In this case, the myelopathy progressed slowly and the degree of paralysis became more extensive than usually seen.

  9. A miniature tilting pad gas lubricated bearing

    NASA Technical Reports Server (NTRS)

    Sixsmith, H.; Swift, W. L.

    1983-01-01

    This paper describes the design and development of a miniature tilting pad gas bearing developed for use in very small turbomachines. The bearings have been developed for cryogenic turboexpanders with shaft diameters down to about 0.3 cm and rotational speeds up to one million rpm. Cryogenic expansion turbines incorporating this type of bearing should be suitable for refrigeration rates down to about 10 w.

  10. Sub miniaturized laser doppler velocimeter sensor

    NASA Technical Reports Server (NTRS)

    Gharib, Morteza (Inventor); Modaress, Darius (Inventor); Taugwalder, Frederic (Inventor)

    2003-01-01

    A miniaturized laser Doppler velocimeter is formed in a housing that is preferably 3 mm in diameter or less. A laser couples light to a first diffractive optical element that is formed on the fiber end. The light is coupled to a lens that also includes a diffractive optical element. The same lens is also used to collect receive light, and receives includes another diffractive optical element to collect that received light.

  11. High Q Miniature Sapphire Acoustic Resonator

    NASA Technical Reports Server (NTRS)

    Wang, Rabi T.; Tjoelker, R. L.

    2010-01-01

    We have demonstrated high Q measurements in a room temperature Miniature Sapphire Acoustic Resonator (MSAR). Initial measurements of bulk acoustic modes in room temperature sapphire at 39 MHz have demonstrated a Q of 8.8 x 10(exp 6). The long term goal of this work is to integrate such a high Q resonator with small, low noise quartz oscillator electronics, providing a fractional frequency stability better than 1 x 10(exp -14) @ 1s.

  12. In Situ Geochemical Analysis and Age Dating of Rocks Using Laser Ablation-Miniature Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva P.; Hecht, Michael H.; Hurowitz, Joel A.

    2012-01-01

    A miniaturized instrument for performing chemical and isotopic analysis of rocks has been developed. The rock sample is ablated by a laser and the neutral species produced are analyzed using the JPL-invented miniature mass spectrometer. The direct sampling of neutral ablated material and the simultaneous measurement of all the elemental and isotopic species are the novelties of this method. In this laser ablation-miniature mass spectrometer (LA-MMS) method, the ablated neutral atoms are led into the electron impact ionization source of the MMS, where they are ionized by a 70-eV electron beam. This results in a secondary ion pulse typically 10-100 microsecond wide, compared to the original 5-10-nanosecond laser pulse duration. Ions of different masses are then spatially dispersed along the focal plane of the magnetic sector of the miniature mass spectrometer and measured in parallel by a modified CCD (charge-coupled device) array detector capable of detecting ions directly. Compared to conventional scanning techniques, simultaneous measurement of the ion pulse along the focal plane effectively offers a 100% duty cycle over a wide mass range. LAMMS offers a more quantitative assessment of elemental composition than techniques that detect laser-ionized species produced directly in the ablation process because the latter can be strongly influenced by matrix effects that vary with the structure and geometry of the surface, the laser beam, and the ionization energies of the elements. The measurement of high-precision isotopic ratios and elemental composition of different rock minerals by LAMMS method has been demonstrated. The LA-MMS can be applied for the absolute age determination of rocks. There is no such instrument available presently in a miniaturized version that can be used for NASA space missions. Work is in progress in the laboratory for geochronology of rocks using LA-MMS that is based on K-Ar radiogenic dating technique.

  13. Strain controlled cyclic tests on miniaturized specimens

    NASA Astrophysics Data System (ADS)

    Procházka, R.; Džugan, J.

    2017-02-01

    The paper is dealing with strain controlled cyclic tests using a non-contact strain measurement based on digital image correlation techniques on proportional sizes of conventional specimens. The cyclic behaviour of 34CrNiMo6 high-strength steel was investigated on miniaturized round specimens with diameter of 2mm that were compared with specimens in accordance with ASTM E606 standards. The cycle asymmetry coefficient was R= -1. This application is intended to be used for life time assessment of in service components in future work which enables to carried out a group of mechanical tests from a limited amount of the experimental material. The attention was paid to confirm the suitability of the proposed size miniaturization geometry, testing set up and procedure. The test results obtained enabled to construct Manson-Coffin curves and assess fatigue parameters. The purpose of this study is to present differences between cyclic curves and cyclic parameters which have been evaluated based on conventional and miniaturized specimens.

  14. Stability-Augmentation Devices for Miniature Aircraft

    NASA Technical Reports Server (NTRS)

    Wood, RIchard M.

    2005-01-01

    Non-aerodynamic mechanical devices are under consideration as means to augment the stability of miniature autonomous and remotely controlled aircraft. Such aircraft can be used for diverse purposes, including military reconnaissance, radio communications, and safety-related monitoring of wide areas. The need for stability-augmentation devices arises because adverse meteorological conditions generally affect smaller aircraft more strongly than they affect larger aircraft: Miniature aircraft often become uncontrollable under conditions that would not be considered severe enough to warrant grounding of larger aircraft. The need for the stability-augmentation devices to be non-aerodynamic arises because there is no known way to create controlled aerodynamic forces sufficient to counteract the uncontrollable meteorological forces on miniature aircraft. A stability-augmentation device of the type under consideration includes a mass pod (a counterweight) at the outer end of a telescoping shaft, plus associated equipment to support the operation of the aircraft. The telescoping shaft and mass pod are stowed in the rear of the aircraft. When deployed, they extend below the aircraft. Optionally, an antenna for radio communication can be integrated into the shaft. At the time of writing this article, the deployment of the telescoping shaft and mass pod was characterized as passive and automatic, but information about the deployment mechanism(s) was not available. The feasibility of this stability-augmentation concept was demonstrated in flights of hand-launched prototype aircraft.

  15. Miniature standoff Raman probe for neurosurgical applications

    NASA Astrophysics Data System (ADS)

    Stevens, Oliver A. C.; Hutchings, Joanne; Gray, William; Vincent, Rosa Louise; Day, John C.

    2016-08-01

    Removal of intrinsic brain tumors is a delicate process, where a high degree of specificity is required to remove all of the tumor tissue without damaging healthy brain. The accuracy of this process can be greatly enhanced by intraoperative guidance. Optical biopsies using Raman spectroscopy are a minimally invasive and lower-cost alternative to current guidance methods. A miniature Raman probe for performing optical biopsies of human brain tissue is presented. The probe allows sampling inside a conventional stereotactic brain biopsy system: a needle of length 200 mm and inner diameter of 1.8 mm. By employing a miniature stand-off Raman design, the probe removes the need for any additional components to be inserted into the brain. Additionally, the probe achieves a very low internal silica background while maintaining good collection of Raman signal. To illustrate this, the probe is compared with a Raman probe that uses a pair of optical fibers for collection. The miniature stand-off Raman probe is shown to collect a comparable number of Raman scattered photons, but the Raman signal to background ratio is improved by a factor of five at Raman shifts below ˜500 cm-1. The probe's suitability for use on tissue is demonstrated by discriminating between different types of healthy porcine brain tissue.

  16. Miniature Robotic Spacecraft for Inspecting Other Spacecraft

    NASA Technical Reports Server (NTRS)

    Fredrickson, Steven; Abbott, Larry; Duran, Steve; Goode, Robert; Howard, Nathan; Jochim, David; Rickman, Steve; Straube, Tim; Studak, Bill; Wagenknecht, Jennifer; Lemke, Matthew; Wade, Randall; Wheeler, Scott; Baggerman, Clinton

    2004-01-01

    A report discusses the Miniature Autonomous Extravehicular Robotic Camera (Mini AERCam)-- a compact robotic spacecraft intended to be released from a larger spacecraft for exterior visual inspection of the larger spacecraft. The Mini AERCam is a successor to the AERCam Sprint -- a prior miniature robotic inspection spacecraft that was demonstrated in a space-shuttle flight experiment in 1997. The prototype of the Mini AERCam is a demonstration unit having approximately the form and function of a flight system. The Mini AERCam is approximately spherical with a diameter of about 7.5 in. (.19 cm) and a weight of about 10 lb (.4.5 kg), yet it has significant additional capabilities, relative to the 14-in. (36-cm), 35-lb (16-kg) AERCam Sprint. The Mini AERCam includes miniaturized avionics, instrumentation, communications, navigation, imaging, power, and propulsion subsystems, including two digital video cameras and a high-resolution still camera. The Mini AERCam is designed for either remote piloting or supervised autonomous operations, including station keeping and point-to-point maneuvering. The prototype has been tested on an air-bearing table and in a hardware-in-the-loop orbital simulation of the dynamics of maneuvering in proximity to the International Space Station.

  17. An Experimental Study of Methanol Reformation.

    DTIC Science & Technology

    1979-12-01

    1973, p. 1300) show how methanol compares to other alterna- tives. In addition, the production of methanol from syngas is a proven commercial...technology, and the syngas can be coal-derived (Wilk 1978, p. 56). The disadvantages of methanol concern the fact that more will have to be carried than...the chief engineer’s job to continue research and upgrading into 1980. 2.2 Design Parameters The following limitations were placed on the new system

  18. Miniaturized micro-optical scanners

    NASA Astrophysics Data System (ADS)

    Motamedi, M. Edward; Andrews, Angus P.; Gunning, William J.; Khoshnevisan, Moshen

    1994-11-01

    Optical beam scanners are critical components for airborne and space-based laser radar, on- machine-inspection systems, factory automation systems, and optical communication systems. We describe here a laser beam steering system based on dithering two complementary (positive and negative) microlens arrays. When the two microlens arrays are translated relative to one another in the plane parallel to their surfaces, the transmitted light beam is scanned in two directions. We have demonstrated scanning speeds up to 300 Hz with a pair of 6-mm- aperture microlens arrays designed for input from a HeNe laser. The output beam covers a discrete 16 X 16 spot scan pattern with about 3.6 mrad separation and only 400 (mu) rad of beam divergence, in close agreement with design predictions. This demo system is relatively compact; less than 2 in. on a side. We also describe several near-term applications, some critical design trade-offs, and important fabrication and design issues.

  19. Miniature quadrupole mass spectrometer array

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)

    1997-01-01

    The present invention provides a minature quadrupole mass spectrometer array for the separation of ions, comprising a first pair of parallel, planar, nonmagnetic conducting rods each having an axis of symmetry, a second pair of planar, nonmagnetic conducting rods each having an axis of symmetry parallel to said first pair of rods and disposed such that a line perpendicular to each of said first axes of symmetry and a line perpendicular to each of said second axes of symmetry bisect each other and form a generally 90 degree angle. A nonconductive top positioning plate is positioned generally perpendicular to the first and second pairs of rods and has an aperture for ion entrance along an axis equidistant from each axis of symmetry of each of the parallel rods, a nonconductive bottom positioning plate is generally parallel to the top positioning plate and has an aperture for ion exit centered on an axis equidistant from each axis of symmetry of each of the parallel rods, means for maintaining a direct current voltage between the first and second pairs of rods, and means for applying a radio frequency voltage to the first and second pairs of rods.

  20. Miniature quadrupole mass spectrometer array

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)

    1998-01-01

    The present invention provides a minature quadrupole mass spectrometer array for the separation of ions, comprising a first pair of parallel, planar, nonmagnetic conducting rods each having an axis of symmetry, a second pair of planar, nonmagnetic conducting rods each having an axis of symmetry parallel to said first pair of rods and disposed such that a line perpendicular to each of said first axes of symmetry and a line perpendicular to each of said second axes of symmetry bisect each other and form a generally 90 degree angle. A nonconductive top positioning plate is positioned generally perpendicular to the first and second pairs of rods and has an aperture for ion entrance along an axis equidistant from each axis of symmetry of each of the parallel rods, a nonconductive bottom positioning plate is generally parallel to the top positioning plate and has an aperture for ion exit centered on an axis equidistant from each axis of symmetry of each of the parallel rods, means for maintaining a direct current voltage between the first and second pairs of rods, and means for applying a radio frequency voltage to the first and second pairs of rods.

  1. Design, fabrication and characterization of miniaturized high resolution camera modules

    NASA Astrophysics Data System (ADS)

    Kuehn, M.; Goetz, M.; Mueller, C.; Reinecke, H.

    2014-05-01

    Camera systems become more and more important in everyday life. Some of those systems place special requirements concerning the environmental conditions they are exposed to especially in harsh environment. High temperature and humidity difficult to access areas require individual packaging and joining technologies for the setup of a camera module. Environmental conditions have an influence on optical design and tolerance calculation. In case of high temperatures the different thermal expansion coefficients of the used materials lead to stress in joints, lenses and their fittings. This, in turn, can lead to a loss of adjustment of the mechanical and optical components that have a direct influence on the optical performance of the camera module. The recent work shows the development of miniaturized high resolution camera modules designed for use in harsh environment applications.

  2. Spectroscopic characterization of a contemporary Indian miniature painting.

    PubMed

    Cardeira, Ana Mafalda; Longelin, Stéphane; Le Gac, Agnès; Nogueira, Isabel; Carvalho, Maria Luísa; Manso, Marta

    2013-12-01

    A case study on a contemporary Indian miniature was carried out through the application of different spectroscopic techniques. Painting support, pigments, and dyes were largely characterized by means of energy dispersive x-ray fluorescence and Raman microspectroscopy directly on the artwork. Regarding golden motifs and silvered areas, for which these techniques have not provided enough information, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy was used as a complementary technique. The painting support was identified as the Bombyx mori silk. Among the colorant matters, several pigments were identified such as chrome yellow, lithopone, hematite, lamp black, mica-titania pearlescent pigment, and tin-based metallic silver, and dyes such as phthalocyanine blue and the recent synthetic pigment red PR9 naphthol AS. All this materials will provide evidence in the support of the contemporary production of the artwork for future studies.

  3. Biogeochemical Cycle of Methanol in Anoxic Deep-Sea Sediments.

    PubMed

    Yanagawa, Katsunori; Tani, Atsushi; Yamamoto, Naoya; Hachikubo, Akihiro; Kano, Akihiro; Matsumoto, Ryo; Suzuki, Yohey

    2016-06-25

    The biological flux and lifetime of methanol in anoxic marine sediments are largely unknown. We herein reported, for the first time, quantitative methanol removal rates in subsurface sediments. Anaerobic incubation experiments with radiotracers showed high rates of microbial methanol consumption. Notably, methanol oxidation to CO2 surpassed methanol assimilation and methanogenesis from CO2/H2 and methanol. Nevertheless, a significant decrease in methanol was not observed after the incubation, and this was attributed to the microbial production of methanol in parallel with its consumption. These results suggest that microbial reactions play an important role in the sources and sinks of methanol in subseafloor sediments.

  4. Evolution in miniaturized column liquid chromatography instrumentation and applications: An overview.

    PubMed

    Nazario, Carlos E D; Silva, Meire R; Franco, Maraíssa S; Lanças, Fernando M

    2015-11-20

    The purpose of this article is to underline the miniaturized LC instrumental system and describe the evolution of commercially available systems by discussing their advantages and drawbacks. Nowadays, there are already many miniaturized LC systems available with a great variety of pump design, interface and detectors as well as efficient columns technologies and reduced connections devices. The solvent delivery systems are able to drive the mobile phase without flow splitters and promote gradient elution using either dual piston reciprocating or syringe-type pumps. The mass spectrometry as detection system is the most widely used detection system; among many alternative ionization sources direct-EI LC-MS is a promising alternative to APCI. In addition, capillary columns are now available showing many possibilities of stationary phases, inner diameters and hardware materials. This review provides a discussion about miniaturized LC demonstrating fundamentals and instrumentals' aspects of the commercially available miniaturized LC instrumental system mainly nano and micro LC formats. This review also covers the recent developments and trends in instrumentation, capillary and nano columns, and several applications of this very important and promising field.

  5. Pt-decorated 3D architectures built from graphene and graphitic carbon nitride nanosheets as efficient methanol oxidation catalysts.

    PubMed

    Huang, Huajie; Yang, Shubin; Vajtai, Robert; Wang, Xin; Ajayan, Pulickel M

    2014-08-13

    Homogeneous dispersion of ultrafine Pt nanoparticles on 3D architectures constructed of graphene and exfoliated graphitic carbon nitride results in hybrids with 3D porous structures, large surface area, high nitrogen content, and good electrical conductivity. This leads to excellent electrocatalytic activity, unusually high poison tolerance, and reliable stability for methanol oxidation, making them of interest as catalysts in direct methanol fuel cells.

  6. Catalytic conversion of methane to methanol on Cu-SSZ-13 using N2O as oxidant.

    PubMed

    Ipek, B; Lobo, R F

    2016-11-08

    Direct catalytic methanol production from methane is achieved on Cu-SSZ-13 zeolite catalysts using N2O as the oxidant. The methanol production rate on Cu-SSZ-13 (on a per gram basis) was more than twice the rate on Cu-mordenite and more than four times the rate on Cu-ZSM-5.

  7. Methanol Steam Reforming for Hydrogen Production

    SciTech Connect

    Palo, Daniel R.; Dagle, Robert A.; Holladay, Jamie D.

    2007-09-11

    Review article covering developments in methanol steam reforming in the context of PEM fuel cell power systems. Subjects covered include methanol background, use, and production, comparison to other fuels, power system considerations, militrary requirements, competing technologies, catalyst development, and reactor and system development and demonstration.

  8. Antidote review: fomepizole for methanol poisoning.

    PubMed

    Mycyk, Mark B; Leikin, Jerrold B

    2003-01-01

    Fomepizole (Antizol) was recently approved by the US Food and Drug Administration for treatment of methanol poisoning. By inhibiting the hepatic enzyme alcohol dehydrogenase, it presents formation of toxic metabolites with far fewer consequences than traditional ethanol therapy. It appears that fomepizole will become standard therapy for methanol intoxication as it is for ethylene glycol poisoning.

  9. Developmental and Reproductive Toxicology of Methanol

    EPA Science Inventory

    Methanol is a high production volume chemical used as a feedstock for chemical syntheses and as a solvent and fuel additive. Methanol is acutely toxic to humans, causing acidosis, blindness in death at high dosages, but its developmental and reproductive toxicity in humans is poo...

  10. Miniature loops in the solar corona

    NASA Astrophysics Data System (ADS)

    Barczynski, K.; Peter, H.; Savage, S. L.

    2017-03-01

    Context. Magnetic loops filled with hot plasma are the main building blocks of the solar corona. Usually they have lengths of the order of the barometric scale height in the corona that is 50 Mm. Aims: Previously it has been suggested that miniature versions of hot loops exist. These would have lengths of only 1 Mm barely protruding from the chromosphere and spanning across just one granule in the photosphere. Such short loops are well established at transition region temperatures (0.1 MK), and we investigate if such miniature loops also exist at coronal temperatures (>1 MK). Methods: We used extreme UV (EUV) imaging observations from the High-resolution Coronal Imager (Hi-C) at an unprecedented spatial resolution of 0.3'' to 0.4''. Together with EUV imaging and magnetogram data from the Solar Dynamics Observatory (SDO) and X-Ray Telescope (XRT) data from Hinode we investigated the spatial, temporal and thermal evolution of small loop-like structures in the solar corona above a plage region close to an active region and compared this to a moss area within the active region. Results: We find that the size, motion and temporal evolution of the loop-like features are consistent with photospheric motions, suggesting a close connection to the photospheric magnetic field. Aligned magnetograms show that one of their endpoints is rooted at a magnetic concentration. Their thermal structure, as revealed together with the X-ray observations, shows significant differences to moss-like features. Conclusions: Considering different scenarios, these features are most probably miniature versions of hot loops rooted at magnetic concentrations at opposite sides of a granule in small emerging magnetic loops (or flux tubes).

  11. Fabrication of miniaturized electrostatic deflectors using LIGA

    SciTech Connect

    Jackson, K.H.; Khan-Malek, C.; Muray, L.P.

    1997-04-01

    Miniaturized electron beam columns ({open_quotes}microcolumns{close_quotes}) have been demonstrated to be suitable candidates for scanning electron microscopy (SEM), e-beam lithography and other high resolution, low voltage applications. In the present technology, microcolumns consist of {open_quotes}selectively scaled{close_quotes} micro-sized lenses and apertures, fabricated from silicon membranes with e-beam lithography, reactive ion beam etching and other semiconductor thin-film techniques. These miniaturized electron-optical elements provide significant advantages over conventional optics in performance and ease of fabrication. Since lens aberrations scale roughly with size, it is possible to fabricate simple microcolumns with extremely high brightness sources and electrostatic objective lenses, with resolution and beam current comparable to conventional e-beam columns. Moreover since microcolumns typically operate at low voltages (1 KeV), the proximity effects encountered in e-beam lithography become negligible. For high throughput applications, batch fabrication methods may be used to build large parallel arrays of microcolumns. To date, the best reported performance with a 1 keV cold field emission cathode, is 30 nm resolution at a working distance of 2mm in a 3.5mm column. Fabrication of the microcolumn deflector and stigmator, however, have remained beyond the capabilities of conventional machining operations and semiconductor processing technology. This work examines the LIGA process as a superior alternative to fabrication of the deflectors, especially in terms of degree of miniaturization, dimensional control, placement accuracy, run-out, facet smoothness and choice of suitable materials. LIGA is a combination of deep X-ray lithography, electroplating, and injection molding processes which allow the fabrication of microstructures.

  12. Development of Californium-252 Miniature Source Assemblies

    SciTech Connect

    Notspecified, N. A.

    2007-06-26

    The purpose of this CRADA between ORNL and lsotron, Inc. is to develop miniature californium-252 sources configured for remote handling that can be used in neutron brachytherapy for treatment of cancer. Brachytherapy places the · radioactive source at or near the site of the tumor, using a catheter. The CRADA ran from late 1999 through November 2005. The heart of a Cf-252 source is the radioactive core wire, which is sealed inside a metallic source capsule. Previous Cf-252 medical sources were based on a cermet wire with californium oxide dispersed in palladium, typically >1-mm diameter and <0.1% Cf-252 by weight. Previously, the standard medical source in the U.S. was the Applicator Tube (AT) source. 23-mm long, 2.8-mm diameter, with ~30 {micro}g of Cf-252, and which required manual loading into patients by medical staff. The goal of this work was to develop capabilities and technology to fabricate higher-intensity Cf-252 sources attached to a positioning cable, with overall diameter approaching that of exist ing photon (iridium-192) brachytherapy sources (i.e., ~1.1 mm). This work was successful in developing and demonstrating new technologies and procedures for the fabrication of miniaturized Cf-252 sources. CRADA-designed equipment reduced the wire diameters significantly (patent pending). Short wire segments were cut and successfully welded inside capsules meeting the miniaturization goals. A batch of seven prototype sources was prepared that met fabrication specifications. Although their neutron emissions were not maximized, they were still several times more intense than the previous AT sources. Very robust source-to-cable attachment methods were demonstrated (patent issued). A shipping canister was designed and built to contain the completed source assembly. lsotron designed and built a computer-controlled remote afterloader system to deliver the new sources for treatments.

  13. Miniaturized Mid-Infrared Sensor Technologies

    SciTech Connect

    Kim, S; Young, C; Mizaikoff, B

    2007-08-16

    Fundamental vibrational and rotational modes associated with most inorganic and organic molecules are spectroscopically accessible within the mid-infrared (MIR; 3-20 {micro}m) regime of the electromagnetic spectrum. The interaction between MIR photons and organic molecules provides particularly sharp transitions, which - despite the wide variety of organic molecules - provide unique MIR absorption spectra reflecting the molecularly characteristic arrangement of chemical bonds within the probed molecules via the frequency position of the associated vibrational and rotational transitions. Given the inherent molecular selectivity and achievable sensitivity, MIR spectroscopy provides an ideal platform for optical sensing applications. Despite this potential, early MIR sensing applications were limited to localized applications due to the size of the involved instrumentation, and limited availability of appropriately compact MIR optical components including light sources, detectors, waveguides, and spectrometers. During the last decades, engineering advances in photonics and optical engineering have facilitated the translation of benchtop-style MIR spectroscopy into miniaturized optical sensing schemes providing a footprint compatible with portable instrumentation requirements for field deployable analytical tools. In this trend article, we will discuss recent advances and future strategies for miniaturizing MIR sensor technology. The Beer-Lambert law implies that achievable limit of detection (LOD) for any optical sensor system improves by increasing the interaction length between photons and target analyte species such as e.g., folding the optical path multiple times as in multi-pass gas phase sensing; however, this governing paradigm naturally leads to an increase in system dimensions. Hence, miniaturization of optical sensing system requires scaling down of each optical component, yet improving the performance of each optical element within a smaller form factor for

  14. Miniature Focusing Time-of-Flight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Kanik, Isik; Srivastava, Santosh

    2005-01-01

    An improved miniature time-of-flight mass spectrometer has been developed in a continuing effort to minimize the sizes, weights, power demands, and costs of mass spectrometers for such diverse applications as measurement of concentrations of pollutants in the atmosphere, detecting poisonous gases in mines, and analyzing exhaust gases of automobiles. Advantageous characteristics of this mass spectrometer include the following: It is simple and rugged. Relative to prior mass spectrometers, it is inexpensive to build. There is no need for precise alignment of its components. Its mass range is practically unlimited Relative to prior mass spectrometers, it offers high sensitivity (ability to measure relative concentrations as small as parts per billion). Its resolution is one dalton (one atomic mass unit). An entire mass spectrum is recorded in a single pulse. (In a conventional mass spectrometer, a spectrum is recorded mass by mass.) The data-acquisition process takes only seconds. It is a lightweight, low-power, portable instrument. Although time-of-flight mass spectrometers (TOF-MSs) have been miniaturized previously, their performances have not been completely satisfactory. An inherent adverse effect of miniaturization of a TOF-MS is a loss of resolution caused by reduction of the length of its flight tube. In the present improved TOF-MS, the adverse effect of shortening the flight tube is counteracted by (1) using charged-particle optics to constrain ion trajectories to the flight-tube axis while (2) reducing ion velocities to increase ion flight times. In the present improved TOF-MS, a stream of gas is generated by use of a hypodermic needle. The stream of gas is crossed by an energy-selected, pulsed beam of electrons (see Figure 1). The ions generated by impingement of the electrons on the gas atoms are then focused by three cylindrical electrostatic lenses, which constitute a segmented flight tube. After traveling along the flight tube, the ions enter a charged

  15. A miniature tactical Rb frequency standard

    NASA Technical Reports Server (NTRS)

    Kwon, T. M.; Dagle, R.; Debley, W.; Dellamano, H.; Hahn, T.; Horste, J.; Lam, L. K.; Magnuson, R.; Mcclelland, T.

    1984-01-01

    Work on an innovative design for miniature rubidium frequency standards has reached the pre-production demonstration stage at Litton Guidance and Control Systems. Pre-production units were built and tested under contract to the Rome Air Development Center of the U.S. Air Force Systems Command. The units, which are designed for use in tactical military applications, feature fast warm-up, low power consumption, and vibration insensitivity. The output stability under vibration is maintained without the need for external shock-mounts. The design objectives and test results are discussed.

  16. Miniature Robotic Submarine for Exploring Harsh Environments

    NASA Technical Reports Server (NTRS)

    Behar, Alberto; Bruhn, Fredrik; Carsey, Frank

    2004-01-01

    The miniature autonomous submersible explorer (MASE) has been proposed as a means of scientific exploration -- especially, looking for signs of life -- in harsh, relatively inaccessible underwater environments. Basically, the MASE would be a small instrumented robotic submarine (see figure) that could launch itself or could be launched from another vehicle. Examples of environments that might be explored by use of the MASE include subglacial lakes, deep-ocean hydrothermal vents, acidic or alkaline lakes, brine lenses in permafrost, and ocean regions under Antarctic ice shelves.

  17. Endocrine alopecia in a miniature poodle.

    PubMed

    Allan, F J; Jones, B R; Purdie, E C

    1995-06-01

    Hypothyroidism and concurrent sex hormone imbalance associated with alopecia was diagnosed in a 5 year-old entire male Miniature Poodle. The dog had a 3-year history of alopecia, seborrhoea and recurrent superficial pyoderma. Abnormal thyrotropin releasing hormone stimulation test results supported a diagnosis of hypothyroidism. Partial hair regrowth occurred after interstitial cell tumours, which were present in both testicles, were removed by castration. Complete hair regrowth, however, occurred only after thyroid hormone supplementation. This case highlighted difficulties which may be encountered when interpreting serum hormone concentrations and endocrine function tests.

  18. Miniaturized bendable 400 MHz artificial magnetic conductor

    NASA Astrophysics Data System (ADS)

    Presse, Anthony; Tarot, Anne-Claude

    2016-04-01

    A bendable artificial magnetic conductor (AMC) with a resonant frequency of 400 MHz is proposed. The dimensions of the unit cell are 50 × 50 mm2 or 0.07 × 0.07 λ0. The miniaturization is achieved with closely coupled patches printed on each side of a 0.127-mm-thick dielectric substrate. This last one is stacked on a flexible 3-mm-thick silicone over a ground plane. An AMC prototype is simulated and manufactured. Also, a printed inverted-F antenna is used to highlight the bandwidth of the AMC.

  19. Miniature ruggedized optical correlator for flight testing

    NASA Astrophysics Data System (ADS)

    Karins, James P.; Mills, Stuart A.; Szegedi, N. J.; Ryan, James R.; Kelly, Louis G., Jr.; Goldstein, Dennis H.; Augustus, Eric P.; Wangler, Richard J.

    1994-03-01

    An electro-optic processor (EOP) incorporating a miniature ruggedized optical correlator (MROC) has been fabricated for use on a remotely piloted vehicle (RPV). The EOP consists of a single-board computer for system control, a MaxVideo 20 card for interfacing to the sensor and performing image processing functions, and an MROC module. The MROC and associated electronics (SLM drive electronics, CCD readout electronics, laser controller, preprocessor, and controller) are configured in a chassis that is placed into an RPV with a visible camera for signal input and a telemetry system for output of the optical processor to the ground.

  20. Surface-micromachined miniature rf switch

    NASA Astrophysics Data System (ADS)

    Guo, Fangmin; Lai, Zongsheng; Zhu, Ziqiang; Fan, Zhong; Long, Yongfu; Yang, Gen Q.; Ge, Xiaohong; Chen, Siqin; Xie, Jianfang

    2001-09-01

    A surface micromachined miniature switch has been made on silicon substrate using an electroplated gold micro-beam as the cantilevered arm, a chromium-to-gold electrical contact, and electrostatic actuation as the switching mechanism. The switch has an electrical isolation of -30dB in the 'off' state and an insertion loss of 4-7dB form 1 to 10 Ghz with a return loss of -15dB in the 'on' state. The high insertion loss has attributed to generation of parasitic current in low resistivity of the silicon substrate.