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1

A silicon-based fuel cell micro power system using a microfabrication technique  

Microsoft Academic Search

This paper reports a silicon-based polymer electrolyte membrane (PEM) fuel cell micro power system in which a high active surface area catalyst layer was monolithically integrated with the major components of the PEM fuel cell (gas diffusion layer, flow field, fuel reservoir and current collector). A sputtering method was used to apply the catalyst on a roughly textured substrate. A

Zhiyong Xiao; Guizhen Yan; Chunhua Feng; Philip C. H. Chan; I.-Ming Hsing

2006-01-01

2

Silicon-based bridge wire micro-chip initiators for bismuth oxide-aluminum nanothermite  

Microsoft Academic Search

We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 °C melting point solder alloy bonding procedure and integrated with a bismuth oxide-aluminum nanothermite energetic

C. S. Staley; C. J. Morris; R. Thiruvengadathan; S. J. Apperson; K. Gangopadhyay; S. Gangopadhyay

2011-01-01

3

Silicon-based metallic micro grid for electron field emission  

NASA Astrophysics Data System (ADS)

A micro-scale metal grid based on a silicon frame for application to electron field emission devices is introduced and experimentally demonstrated. A silicon lattice containing aperture holes with an area of 80 × 80 µm2 and a thickness of 10 µm is precisely manufactured by dry etching the silicon on one side of a double-polished silicon wafer and by wet etching the opposite side. Because a silicon lattice is more rigid than a pure metal lattice, a thin layer of Au/Ti deposited on the silicon lattice for voltage application can be more resistant to the geometric stress caused by the applied electric field. The micro-fabrication process, the images of the fabricated grid with 88% geometric transparency and the surface profile measurement after thermal feasibility testing up to 700 °C are presented.

Kim, Jaehong; Jeon, Seok-Gy; Kim, Jung-Il; Kim, Geun-Ju; Heo, Duchang; Shin, Dong Hoon; Sun, Yuning; Lee, Cheol Jin

2012-10-01

4

Development and characterization of a silicon-based micro direct methanol fuel cell  

Microsoft Academic Search

A silicon-based micro direct methanol fuel cell (?DMFC) for portable applications has been developed and its electrochemical characterization carried out in this study. Anode and cathode flowfields with channel and rib width of 750?m and channel depth of 400?m were fabricated on Si wafers using the microelectromechanical system (MEMS) technology. A membrane-electrode assembly (MEA) was specially fabricated to mitigate methanol

G. Q. Lu; C. Y. Wang; T. J. Yen; X. Zhang

2004-01-01

5

Silicon-based bridge wire micro-chip initiators for bismuth oxide-aluminum nanothermite  

NASA Astrophysics Data System (ADS)

We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 °C melting point solder alloy bonding procedure and integrated with a bismuth oxide-aluminum nanothermite energetic composite. The electro-thermal conversion efficiency of the initiators is enhanced by the use of a nanoporous silicon bed which impedes thermal coupling between the bridge wire and bulk silicon substrate while maintaining the structural integrity of the device. Electrical behaviors of the ignition elements are investigated to extract minimum input power and energy requirements of 382.4 mW and 26.51 µJ, respectively, both in the absence and presence of an injected bismuth oxide-aluminum nanothermite composition. Programmed combustion of bismuth oxide-aluminum nanothermite housed within these initiators is demonstrated with a success rate of 100% over a 30 to 80 µJ range of firing energies and ignition response times of less than 2 µs are achieved in the high input power operation regime. The micro-initiators reported here are intended for use in miniaturized actuation technologies.

Staley, C. S.; Morris, C. J.; Thiruvengadathan, R.; Apperson, S. J.; Gangopadhyay, K.; Gangopadhyay, S.

2011-11-01

6

Porous Silicon-Based Gas Sensors and Miniature Hydrogen Cells  

NASA Astrophysics Data System (ADS)

The current-voltage (I-V) characteristics of Au/porous silicon (PS)/Si Schottky-type structures in humid, CO, and H2S gas atmospheres were investigated. It was found that the gas atmosphere influences the I-V characteristics, particularly the reverse current in Au/PS/Si and Au/PS structures. The reverse current in the H2S atmosphere was 103 times larger than that in room-temperature (300 K) air [45% relative humidity (RH)]. The generation of an open-circuit voltage (up to 480 mV) at the Au/PS interface in humid, CO, and H2S atmospheres was detected. The humidity- and gas-stimulated effect of voltage generation in the Au/PS/Si structures was reversible with a response time of 60 s. The quite high sensitivities to humidity, CO, and H2S (about 9 mV/RH, 4 mV/ppm, and 2 mV/ppm, respectively) indicate the possibility of using the obtained Au/PS/Si structures as both gas sensors and miniature hydrogen fuel cells. The mechanism for the gas-stimulated generation of electricity in the Au/PS structures is discussed and is considered to be similar to that of the proton exchange membrane in hydrogen fuel cells.

Dzhafarov, Tayyar; Yuksel, Sureyya Aydin; Lus, Cigdem Oruc

2008-10-01

7

Micro-Raman spectroscopy of refractive index microstructures in silicone-based hydrogel polymers created by high-repetition-rate femtosecond laser micromachining  

Microsoft Academic Search

Micro-Raman spectroscopy was used to study silicone-based hydrogel polymers after being modified by 800 nm, 27 fs laser pulses from a Ti:sapphire oscillator at 93 MHz repetition rate. When the irradiation con- ditions were below the optical breakdown threshold of the polymers, no significant changes in the Raman spec- tra and background fluorescence were observed even when refractive index changes

Li Ding; Luiz Gustavo Cancado; Lukas Novotny; Wayne H. Knox; Neil Anderson; Dharmendra Jani; Jeffrey Linhardt; Richard I. Blackwell; Jay F. Künzler

2009-01-01

8

Wettability modification of polysilicon for stiction reduction in silicon based micro-electromechanical structures  

NASA Astrophysics Data System (ADS)

Surface micromachining using deposited polysilicon films is a technology that is widely used for the fabrication of micro-electromechanical structures. One of the biggest yield and reliability problems in the fabrication of such structures is "stiction" or adhesion to the substrate. This may occur during the drying step that is required after wet processing and/or during use of a device. Deposition of self-assembled monolayer coatings is one of the most successful approaches to chemical modification of silicon surfaces to reduce stiction. This approach involves making the surfaces of pre-oxidized polysilicon highly hydrophobic. As a result, microstructures come out of the final water rinse extremely dry without being broken or adhered to the substrate. Available technology requires that these coatings are applied from organic media . However, increasing pressure on semiconductor companies to reduce the generation of organic wastes has sparked interest in the feasibility of applying these coatings from aqueous media. The objective of this research was to develop the chemistry and techniques for the application of hydrophobic coatings on polysilicon from aqueous media. The results obtained from three commercially available water dispersible silanes and cationic alkoxysilanes are discussed. Key experimental variables that were investigated are concentration of reactive silane, type of oxidation pretreatment of polysilicon, pH and temperature of the silane dispersion and curing temperature of the coating. The stability of the dispersions was characterized by viscosity measurements. The formation and quality of the films were studied using atomic force microscopy (AFM), ellipsometry, dynamic contact angle measurements and electrochemical impedance spectroscopy (EIS). The coatings showed contact angles greater than 100°. It was found using AFM that the structure of these films is a continuous film with some particulates attributed to bulk polymerization of the precursor molecule in water. EIS results indicated that the coatings had low porosity as well as high charge transfer resistance across the silicon/HF interface. Ellipsometric analysis showed that thickness of these coatings is roughly a (statistical) monolayer. The stability improvement of the dispersions by the addition of quaternary ammonium cationic surfactants is also discussed.

Almanza-Workman, Angeles Marcia

9

Silicon-based micro direct methanol fuel cell with an N-inputs-N-outputs anode flow pattern  

Microsoft Academic Search

A micro direct methanol fuel cell (?DMFC) is suitable for use in notebook computers, mobile phones, and other digital products.\\u000a To resolve the poor mass-transport efficiency problem in the anode flow channel, this paper presents an N-inputs-N-outputs\\u000a parallel flow pattern with rectangular convexes to reinforce methanol mass transport and reduce concentration polarization.\\u000a The simulation results show that the N-inputs-N-outputs parallel

YuFeng Zhang; LuWen Wang; ZhenYu Yuan; ShiBo Wang; JianMin Li; XiaoWei Liu

2011-01-01

10

Hydroinertia gas bearings for micro spinners  

NASA Astrophysics Data System (ADS)

Externally pressurized gas bearings with large bearing clearance are successfully used in ultra-high-speed micro spinners. For example, a micro spinner 4 mm in diameter is stably operated at more than 20 krps and its whirl ratio exceeds 20. In such bearings, the inertia effect of the gas flow in bearing clearance becomes predominant and its Mach number exceeds 1. As a result, gas pressure in the bearing clearance becomes negative. These bearings are called hydroinertia gas bearings, in contrast to the conventional hydrostatic gas bearings. Static characteristics of hydroinertia gas bearings are analyzed by considering the viscous effect of gas as wall friction, and the optimum design of hydroinertia gas bearings is shown. Experimental results on micro spinners and trial design of hydroinertia gas bearings for micro gas turbines are also discussed.

Hikichi, Kousuke; Goto, Satoshi; Togo, Shinichi; Tanaka, Shuji; Isomura, Kousuke

2005-09-01

11

Use of gas jet techniques to prepare microcrystalline silicon based solar cells at high i-layer deposition rates  

SciTech Connect

Using a Gas Jet thin film deposition technique, microcrystalline silicon ({micro}c-Si) materials were prepared at rates as high as 15--20 {angstrom}/s. The technique involves the use of a gas jet flow that is subjected to a high intensity microwave source. The quality of the material has been optimized through the variation of a number of deposition conditions including the substrate temperature, the gas flows, and the applied microwave power. The best films were made using deposition rates near 16 {angstrom}/s. These materials have been used as i-layers for red light absorbing, nip single-junction solar cells. Using a 610nm cutoff filter which only allows red light to strike the device, pre-light soaked currents as high as 10 mA/cm{sup 2} and 2.2--2.3% red-light pre-light soaked peak power outputs have been obtained for cells with i-layer thicknesses near 1 micron. This compares with currents of 10--11 mA/cm{sup 2} and 4% initial red-light peak power outputs obtained for high efficiency amorphous silicon germanium alloy (a-SiGe:H) devices. The AM1.5 white light efficiencies for these microcrystalline cells are 5.9--6.0%. While the efficiencies for the a-SiGe:H cells degrade by 15--20% after long term light exposure, the efficiencies for the microcrystalline cells before and after prolonged light exposure are similar, within measurement error. Considering these results, the Gas Jet deposition method is a promising technique for the deposition of {micro}c-Si solar cells due to the ability to achieve reasonable stable efficiencies for cells at i-layer deposition rates (16 {angstrom}/s) which make large-scale production economically feasible.

Jones, S.J.; Crucet, R.; Deng, X.; Doehler, J.; Kopf, R.; Myatt, A.; Tsu, D.V.; Izu, M.

1999-07-01

12

Hydroinertia gas bearings for micro spinners  

Microsoft Academic Search

Externally pressurized gas bearings with large bearing clearance are successfully used in ultra-high-speed micro spinners. For example, a micro spinner 4 mm in diameter is stably operated at more than 20 krps and its whirl ratio exceeds 20. In such bearings, the inertia effect of the gas flow in bearing clearance becomes predominant and its Mach number exceeds 1. As

Kousuke Hikichi; Satoshi Goto; Shinichi Togo; Shuji Tanaka; Kousuke Isomura

2005-01-01

13

Environmental Barrier Coatings for Silicon-Based Ceramics.  

National Technical Information Service (NTIS)

Silicon-based ceramics, such as SiC fiber-reinforced SiC (SiC/SiC ceramic matrix composites (CMC) and monolithic silicon nitride (Si3N4), are prime candidates for hot section structural components of next generation gas turbine engines. Silicon-based cera...

K. N. Lee D. S. Fox R. C. Robinson N. P. Bansal

2001-01-01

14

The micro slit gas detector  

NASA Astrophysics Data System (ADS)

We describe the first tests with a new proportional gas detector. Its geometry consists of slits opened in a copper metallized kapton foil with 30?m anode strips suspended in these openings. In this way, the multiplication process is similar to a standard MSGC. The fundamental difference is the absence of an insulating substrate around the anode. Also the material budget is significantly reduced, and the problems related to charging-up or polarization are removed. Ageing properties of this detector are under study.

Claude Labbé, J.; Gómez, F.; Nún~ez, T.; Pazos, A.; Vázquez, P.

1999-06-01

15

Micro gas bearings fabricated by deep X-ray lithography  

Microsoft Academic Search

Micro bearing systems for Micro Electromechanical Systems (MEMS) have drawn attention for several decades as critical components for micro rotating machinery. Ideally, frictionless bearings are needed, and in practice, micro gas bearings approach the ideal. Typically, bearings function as a separate component, assembled onto sliding counterparts. However, in micro scale devices, assembly procedures are known to be very tedious and

D. Kim; S. Lee; Y. Jin; Y. Desta; M. D. Bryant; J. Goettert

2004-01-01

16

Humidity-independent portable air-hydrogen fuel cells with slotted silicon based gas-distributing plates  

NASA Astrophysics Data System (ADS)

We have studied the characteristics of small-scale air-hydrogen fuel cells (FCs) operating in a free-breathing cathode regime. The cells are provided with a new gas-distributing element on the cathode side, which is based on a silicon plate with narrow through slots (slotted Si plate). It is shown that the use of a slotted Si plate significantly weakens the dependence of the FC characteristics on the humidity of environment in a broad temperature range. Indeed, at a fixed temperature, the FC power only changed within 10% when the relative humidity of the ambient air varied between 50 and 98%.

Astrova, E. V.; Andronikov, D. A.; Gorokhov, M. V.; Zelenina, N. K.; Kozhevin, V. M.; Terukov, E. I.; Tomasov, A. A.; Gurevich, S. A.

2010-06-01

17

Silicon based plasmonic coupler.  

PubMed

Plasmonics is a field in which the light matter interaction can be controlled at the nanoscale by patterning the material surface to achieve enhanced optical effects. Realisation of micron sized silicon based plasmonic devices will require efficient coupling of light from an optical fibre grating coupler into silicon compatible plasmonic waveguides. In this paper we have investigated a silicon based plasmonic coupler with a very short taper length, which confines and focuses light from a broad input fibre opening into a plasmonic waveguide at the apex of the structure. A simple transfer matrix model was also developed to analyse the transmission performance of the coupler with respect to its key physical parameters. The proposed plasmonic coupler was optimised with respect to its different structural parameters using finite element simulations. A maximum coupling efficiency of 72% for light coupling from a 6.2 ?m wide input opening into a 20 nm slit width was predicted. The simulated result also predicted an insertion loss of ? 2.0 dB for light coupling into a 300 nm single mode SOI waveguide from a plasmonic structure with a 10.4 ?m input opening width and a taper length of only 3.15 ?m. Furthermore, the application of the optimised plasmonic coupler as a splitter was investigated, in which the structure simultaneously splits and couples light with a predicted coupling efficiency of ? 37 % (or a total coupling efficiency of 73%) from a 6.22 ?m input opening into two 50 nm wide plasmonic waveguides. PMID:23037272

Thomas, Roney; Ikonic, Zoran; Kelsall, R W

2012-09-10

18

Silicon-based nanoenergetic composites  

SciTech Connect

Fundamental combustion properties of silicon-based nano-energetic composites was studied by performing equilibrium calculations, 'flame tests', and instrumented burn-tube tests. That the nominal maximum flame temperature and for many Si-oxidizer systems is about 3000 K, with exceptions. Some of these exceptions are Si-metal oxides with temperatures ranging from 2282 to 2978 K. Theoretical maximum gas production of the Si composites ranged from 350-6500 cm{sup 3}/g of reactant with NH{sub 4}ClO{sub 4} - Si producing the most gas at 6500 cm{sup 3}/g and Fe{sub 2}O{sub 3} producing the least. Of the composites tested NH{sub 4}ClO{sub 4} - Si showed the fastest burning rates with the fastest at 2.1 km/s. The Si metal oxide burning rates where on the order of 0.03-75 mls the slowest of which was nFe{sub 2}O{sub 3} - Si.

Asay, Blaine [Los Alamos National Laboratory; Son, Steven [PURDUE UNIV; Mason, Aaron [PURDUE UNIV; Yarrington, Cole [PURDUE UNIV; Cho, K Y [PURDUE UNIV; Gesner, J [PSU; Yetter, R A [PSU

2009-01-01

19

Design of micro-sensor-array detector for toxic gas  

Microsoft Academic Search

To quickly measure the trace concentration of the single component toxic gas (e.g. sarin), a micro-array toxic gas detector is designed. A 3 x 3 gas sensor array with metalloporphyrins as sensitive materials is introduced. A micro-capsule that can be easy to be loaded and unloaded is designed for the gas reaction. A fiber-array optical path is designed, which is

Hai-Yang Liao; Peng Tian

2010-01-01

20

An improved micro-combustor design for micro gas turbine engine and numerical analysis  

Microsoft Academic Search

An improved design to stabilize the combustion in a micro gas turbine engine is proposed and analysed through computational modelling in this paper. The new design distinguishes from the original MIT design by adding another wafer layer of micro channel to regulate the fluid flow velocity distribution and direction near the combustor entrance. As a result, the fuel\\/air mixture flow

Meng Wu; Jinsong Hua; Kurichi Kumar

2005-01-01

21

Gas Sensors Based on Piezoelectric Micro-Diaphragm Transducer  

Microsoft Academic Search

We have fabricated high sensitive gas sensor based on piezoelectrically driven micro-diaphragm transducers. The micro-diaphragm transducer was fabricated using micro-electro-mechanical-system (MEMS) technique. The diol based sol-gel derived Pb(Zr0.52,Ti0.48)O3(PZT) film was used as a piezoelectric actuating layer. We have used the resonant frequency change of micro-diaphragm transducer upon mass increase as a sensing signal. The resonant frequency values were measured by

Jaichan Lee; Sanghun Shin; Jun-Kyu Paik; Nae-Eung Lee; Hyo-Derk Park; Jun-Shik Park

2005-01-01

22

Fabrication and characterization of micro-gas sensor for nitrogen oxides gas detection  

Microsoft Academic Search

WO3-based thin film micro-gas sensor was fabricated and the NOx gas sensing as well as electrical properties have been investigated. To obtain the optimal heat distribution, the structure of micro-hot plate was designed from the result of finite element simulation and was prepared by backside etching with KOH solution.The micro-hot plate was made out of N\\/O\\/N diaphragm with the thickness

Dae-Sik Lee; Jun-Woo Lim; Sang-Mun Lee; Jeung-Soo Huh; Duk-Dong Lee

2000-01-01

23

Information preservation methods for modeling micro-scale gas flows  

NASA Astrophysics Data System (ADS)

Micro-scale gas flow is a rapidly growing research field driven by microsystems technology. Experiments have shown that fluid mechanics of these flows are not the same as those experienced in the macroscopic world. However, theoretical analysis is difficult because those flows are generally in the slip or transitional flow regime, and it is hard to investigate the detailed flow fields experimentally due to the small physical dimensions of microsystems. There are several numerical approaches that can model some micro-scale gas flows. Generally, continuum-based methods are numerically efficient, but physically limited; kinetic-based methods are physically accurate, but numerically expensive. Hence, it is necessary to develop a general-purpose numerical approach to understand micro-scale gas flows. This dissertation is devoted to developing a numerical approach for modeling general micro-scale gas flows with reasonable efficiency and accuracy. In the first stage, a particle method called the information preservation (IP) method, proposed by Fan and Shen based on the direct simulation Monte Carlo (DSMC) method, is developed to simulate general micro-scale gas flows. The IP method greatly reduces the statistical scatter associated with particle methods by using macroscopic information preserved in microscopic particles to sample the flow field. Thus low-speed micro-scale gas flows can be simulated using the IP method with reasonable numerical cost. In the second stage, a hybrid approach is designed by coupling the IP method and a Navier-Stokes solver for modeling micro-scale gas flows with better numerical efficiency. The IP method and the Navier-Stokes solver are strongly coupled using an adaptive continuum/particle interface. Using the hybrid approach, we investigate gas flows over micro-scale flat plates. We find that the normalized drag coefficient CDM on a flat plate having zero thickness depends on Re/M0.8 when 1micro air vehicles.

Sun, Quanhua

24

Manufacturing of micro gas bearing for power MEMS applications using nanopowder metallurgy processing  

Microsoft Academic Search

This paper introduces manufacturing of tilting pad gas bearing with a diameter of 5 mm and a length of 0.5~1mm for power MEMS (Micro Electomechanical Systems) applications. Potential applications include micro gas turbines (100W) for mobile robots, turbo compressors\\/micro blower for micro fuel cells, micro bearings for pediatric heart, etc. Ultra fine gas bearing for micro component is so complicated

Soo-Jung Son; Chul-Jin Choi; Daejung Kim; Jong-Hyun Kim; Suk-Sang Chang

2010-01-01

25

Design of micro-sensor-array detector for toxic gas  

NASA Astrophysics Data System (ADS)

To quickly measure the trace concentration of the single component toxic gas (e.g. sarin), a micro-array toxic gas detector is designed. A 3 x 3 gas sensor array with metalloporphyrins as sensitive materials is introduced. A micro-capsule that can be easy to be loaded and unloaded is designed for the gas reaction. A fiber-array optical path is designed, which is based on the principle that gas sensors will show different colors after reaction with the toxic gas. The tricolor information about the concentration of gas is collected by the color liner CCD. A control handling system with C8051F021 MCU as the core is implemented and embedded into the detector to perform the functions of gas sampling, data collection and analysis calculation. Data acquisition experimental results show that the proposed scheme can effectively collect the color information after gas reaction. Moreover, the system has many important advantages, such as small size, compact structure, high degree of automation, fast detection speed and high performance-cost ratio, etc.

Liao, Hai-Yang; Tian, Peng

2010-08-01

26

A micro channel integrated gas flow sensor for high sensitivity  

Microsoft Academic Search

In order to enhance measurement accuracy, a gas mass flow sensor integrated with micro channels is proposed in this paper. The uniqueness of this flow sensor is that there is thermal convection effect on two sides of diaphragm, which results in a more sensitive temperature distribution. The temperature characteristics of the novel flow sensor are simulated at different flow rates,

Bolin Yu; Zhiyin Gan; Shu Cao; Jingping Xu; Sheng Liu

2008-01-01

27

Influence of the bearing number on micro gas bearing system  

Microsoft Academic Search

This paper employs a numerical method combining the differential transformation method and the finite difference method to study the bifurcation behavior of a rigid rotor supported by a micro gas bearing system. The numerical results reveal a complex dynamic behavior comprising periodic, sub-harmonic, and quasi-periodic responses of the rotor center. Furthermore, the results reveal the changes which take place in

Cheng-Chi Wang; Her-Terng Yau; Yen-Liang Yeh; Ming-Jyi Jang; Jing-Fung Lin

2009-01-01

28

MICRO-MACHINED THIN FILM HYDROGEN GAS SENSORS  

Microsoft Academic Search

The ability to detect gaseous hydrogen is of critical importance to acceptance and utilization of hydrogen as an energy carrier. Micro-machined gas sensors are a new generation of sensor technology combining existing integrated circuit fabrication technology with novel deposition and etching processing. This results in a new device structure, known as a \\

Frank DiMeo; Ing-Shin Chen; Philip Chen; Jeffrey Neuner Michele Stawasz; James Welch; A. Rohrl

29

Silicon-Based Optoelectronics: Progress and Challenges  

Microsoft Academic Search

We review the status of silicon-based optoelectronics with emphasis on light emitting diodes. Erbium-doped Si, por-Si and silicon-based superlattices and nanostructures are discussed. The origin behind light emission in silicon with feature sizes below about 60 nm still remains poorly understood.

Tamim P. Sidiki; Clivia M. Sotomayor Torres

1999-01-01

30

Operation of a Micro Strip Gas Counter equipped with a Gas Electron Multiplier  

NASA Astrophysics Data System (ADS)

This paper reports on the operation of a Micro Strip Gas Counter (MSGC) equipped with a Gas Electron Multiplier (GEM) filled with Ar/CO2, Ne/CO2 and Ne/DME/CO2. We present measurements of the detection efficiency for minimum ionizing particles, and of the electron drift velocity and transverse diffusion coefficient in the counting gases considered.

Beaumont, W.; Beckers, T.; Bouhali, O.; de Troy, J.; Udo, F.; Velde, C. Vander; van Doninck, W.; van Dyck, Ch.; Vanlaer, P.; van Lancker, L.; Zhukov, V.

1999-08-01

31

PREFACE: 1st European Conference on Gas Micro Flows (GasMems 2012)  

NASA Astrophysics Data System (ADS)

The aim of the 1st European Conference on Gas Micro Flows is to advance research in Europe and worldwide in the field of gas micro flows as well as to improve global fundamental knowledge and to enable technological applications. Gas flows in microsystems are of great importance and touch almost every industrial field (e.g. fluidic microactuators for active control of aerodynamic flows, vacuum generators for extracting biological samples, mass flow and temperature micro-sensors, pressure gauges, micro heat-exchangers for the cooling of electronic components or for chemical applications, and micro gas analyzers or separators). The main characteristic of gas microflows is their rarefaction, which for device design often requires modelling and simulation both by continuous and molecular approaches. In such flows various non-equilibrium transport phenomena appear, while the role played by the interaction between the gas and the solid device surfaces becomes essential. The proposed models of boundary conditions often need an empirical adjustment strongly dependent on the micro manufacturing technique. The 1st European Conference on Gas Micro Flows is organized under the umbrella of the recently established GASMEMS network (www.gasmems.eu/) consisting of 13 participants and six associate members. The main objectives of the network are to structure research and train researchers in the fields of micro gas dynamics, measurement techniques for gaseous flows in micro experimental setups, microstructure design and micro manufacturing with applications in lab and industry. The conference takes place on June 6-8 2012, at the Skiathos Palace Hotel, on the beautiful island of Skiathos, Greece. The conference has received funding from the European Community's Seventh Framework Programme FP7/2007-2013 under grant agreement ITN GASMEMS no. 215504. It owes its success to many people. We would like to acknowledge the support of all members of the Scientific Committee and of all referees for their thorough reviews and evaluation of the full papers. Above all, we would like to sincerely thank all authors for their valuable contributions to these proceedings as well as all the participants for creating a stimulating atmosphere through their presentations and discussions and making this conference a great success. Dr Arjan Frijns Editor and Event Coordinator Prof. Dimitris Valougeorgis Local Organizer Prof. Stéphane Colin Network Coordinator Dr Lucien Baldas Assistant Network Coordinator The PDF also contains details of the Conference Organizers.

Frijns, Arjan; Valougeorgis, Dimitris; Colin, Stéphane; Baldas, Lucien

2012-05-01

32

Process for strengthening silicon based ceramics  

DOEpatents

A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

Kim, Hyoun-Ee (Oak Ridge, TN); Moorhead, A. J. (Knoxville, TN)

1993-01-01

33

Process for strengthening silicon based ceramics  

DOEpatents

A process for strengthening silicon based ceramic monolithic materials and composite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400{degrees}C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts, or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

Kim, Hyoun-Ee; Moorhead, A.J.

1991-03-07

34

Amorphous Silicon Based Neutron Detector  

SciTech Connect

Various large-scale neutron sources already build or to be constructed, are important for materials research and life science research. For all these neutron sources, neutron detectors are very important aspect. However, there is a lack of a high-performance and low-cost neutron beam monitor that provides time and temporal resolution. The objective of this SBIR Phase I research, collaboratively performed by Midwest Optoelectronics, LLC (MWOE), the University of Toledo (UT) and Oak Ridge National Laboratory (ORNL), is to demonstrate the feasibility for amorphous silicon based neutron beam monitors that are pixilated, reliable, durable, fully packaged, and fabricated with high yield using low-cost method. During the Phase I effort, work as been focused in the following areas: 1) Deposition of high quality, low-defect-density, low-stress a-Si films using very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) at high deposition rate and with low device shunting; 2) Fabrication of Si/SiO2/metal/p/i/n/metal/n/i/p/metal/SiO2/ device for the detection of alpha particles which are daughter particles of neutrons through appropriate nuclear reactions; and 3) Testing of various devices fabricated for alpha and neutron detection; As the main results: · High quality, low-defect-density, low-stress a-Si films have been successfully deposited using VHF PECVD on various low-cost substrates; · Various single-junction and double junction detector devices have been fabricated; · The detector devices fabricated have been systematically tested and analyzed. · Some of the fabricated devices are found to successfully detect alpha particles. Further research is required to bring this Phase I work beyond the feasibility demonstration toward the final prototype devices. The success of this project will lead to a high-performance, low-cost, X-Y pixilated neutron beam monitor that could be used in all of the neutron facilities worldwide. In addition, the technologies developed here could be used to develop X-ray and neutron monitors that could be used in the future for security checks at the airports and other critical facilities. The project would lead to devices that could significantly enhance the performance of multi-billion dollar neutron source facilities in the US and bring our nation to the forefront of neutron beam sciences and technologies which have enormous impact to materials, life science and military research and applications.

Xu, Liwei

2004-12-12

35

A study of semiconducting glass micro-strip gas chambers  

NASA Astrophysics Data System (ADS)

The properties of Micro Strip Gas Chambers, built on semiconducting glasses, S8900 and, for the first time, Moscow glass with bulk resistivity /rho=3/cdot1012/ /Omega[/cdot]cm, are presented. The radiation hardness (aging) of the detectors in an argon dimethyl ether gas mixture is measured. Initially, a gain drop of, at best, 12% after an accumulated charge of 1 mC/cm, is detected. The aging rate is found to be dependent on the flow rate of the gas. After modifications to the gas system, a gain drop of 6%, after an accumulated charge of 45 mC/cm, is measured. This is equivalent to 4.5 years of operation at CERN's Large Hadron Collider, a next generation high luminosity accelerator. The construction of the gas system is described in detail. Count rate and gain modulations are measured in large pitch MSGCs. The magnitude of the gain modulation is found to be correlated to the applied anode and drift voltage. However, the magnitude of the count rate modulation does not depend on the applied voltages. The performance of glass and sapphire substrate MSGCs with chromium and molybdenum electrodes, overcoated with carbon, hydrogenated amorphous silicon, and semiconducting glass layers is reported.

Gerndt, Ekkehard Karl Ernst

36

Applied modelling for bio and lean gas fired micro gas turbines  

Microsoft Academic Search

Summary This contribution presents the outcome of applied computational fluid dynamics (CFD) for analysis of combustion technologies to find an efficient firing mode for use of bio and low calorific gaseous fuels in micro gas turbine combustors. The combustion technologies considered are based on the new concepts of flameless oxidation (FLOX®) and continued staged air (COSTAIR). Both concepts ensure through

A. Al-Halbouni; A. Giese; M. Flamme; K. Goerner

2006-01-01

37

Integrated Micro-Machined Hydrogen Gas Sensor. Final Report  

SciTech Connect

This report details our recent progress in developing novel MEMS (Micro-Electro-Mechanical Systems) based hydrogen gas sensors. These sensors couple novel thin films as the active layer on a device structure known as a Micro-HotPlate. This coupling has resulted in a gas sensor that has several unique advantages in terms of speed, sensitivity, stability and amenability to large scale manufacture. This Phase-I research effort was focused on achieving the following three objectives: (1) Investigation of sensor fabrication parameters and their effects on sensor performance. (2) Hydrogen response testing of these sensors in wet/dry and oxygen-containing/oxygen-deficient atmospheres. (3) Investigation of the long-term stability of these thin film materials and identification of limiting factors. We have made substantial progress toward achieving each of these objectives, and highlights of our phase I results include the demonstration of signal responses with and without oxygen present, as well as in air with a high level of humidity. We have measured response times of <0.5 s to 1% H{sub 2} in air, and shown the ability to detect concentrations of <200 ppm. These results are extremely encouraging and suggest that this technology has substantial potential for meeting the needs of a hydrogen based economy. These achievements demonstrate the feasibility of using micro-hotplates structures in conjunction with palladium+coated metal-hydride films for sensing hydrogen in many of the environments required by a hydrogen based energy economy. Based on these findings, they propose to continue and expand the development of this technology in Phase II.

Frank DiMeo, Jr.

2000-10-02

38

An aging study of a gas electron multiplier with micro-strip gas chamber readout  

SciTech Connect

The authors have performed an aging study of a Gas Electron Multiplier (GEM) readout with a Micro-Strip Gas Chamber (MSGC). The GEM is constructed from Kapton and copper, and the MSGC is constructed from semiconductive glass and gold. When the detector (GEM+MSGC) is operated in an argon-dimethyl ether (DME) gas mixture and irradiated with a 5.4 keV photon beam, about 220 mC/cm of charge can be accumulated without degradation of the detector performance. This corresponds to about 20 years of operation at the LHC.

Miyamoto, J.; Shipsey, I.P.I. [Purdue Univ., W. Lafayette, IN (United States). Dept. of Physics

1999-06-01

39

Silicon-based rectangular hollow integrated waveguides  

Microsoft Academic Search

This paper describes the simulation, fabrication and characterization of silicon-based rectangular hollow waveguides. Numerical evaluation of such structures has been done using both modal propagation and ray tracing, low total losses and multimodal behavior, even for small core sizes, are predicted. Since light propagation in rectangular hollow waveguides strongly depends on the Fresnel coefficients at the facets, the technological processes

V. J. Cadarso; A. Llobera; I. Salinas; D. Izquierdo; I. Garcés; C. Domínguez

2008-01-01

40

Gold Nanoparticle Chemiresistor Arrays for Micro-Gas Chromatography Applications  

NASA Astrophysics Data System (ADS)

Thiolate-monolayer-protected gold nanoparticle (MPN) chemiresistors were studied as the sensing devices for micro-gas chromatography (microGC) systems. Because transport through chemiresistors is dominated by tunneling, they are highly sensitive. In order to improve their limit of detection, their fundamental noise was studied. Chemiresistors exhibit 1/f type noise where noise scales inversely with frequency. Chemiresistor noise was found to scale inversely with MPN film thickness. We lowered the noise prefactor of a 50x60 microm2 chemiresistor by coating a thick rather than monolayer MPN film. Electron beam induced crosslinking (EBIX) of the MPN film slightly reduced chemiresistor noise. A technique for patterning chemiresistor arrays with MPN films using EBIX was developed, and an array with four distinct MPNs was fabricated in an area ˜600 microm 2. This is the smallest chemiresistor array reported to date. Chemiresistors were exposed to vapors and provided differential sensitivities comparable to those from larger uncrosslinked chemiresistors. Chemiresistors were studied to assess their long term stability. Chemiresistors exhibited decreases in resistance over time that is likely caused by loss of MPN ligands. Temperature dependent current-voltage measurements verified the resistance change was not due to changes in the size of the MPN core. While resistance could change by orders of magnitude, vapor sensitivity did not show significant changes. Heating increased the change in resistance, but chemiresistors remained responsive after being held at 80°C for a cumulative 400 hours. It was unknown whether tunneling in the MPN film is through the highest unoccupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO). A new technique was explored to distinguish tunneling through the HOMO and LUMO by measuring the induced thermoelectric voltage caused by a temperature difference across the MPN film. For integration into a microGC system, we fabricated a chemiresistor array on the surface of a 2.2x2.2 mm2readout circuitry chip creating a monolithic sensor system. A model for determining the optimal sensor size for a microGC system is presented. While noise is inversely proportional to chemiresistor volume, the amount of analyte detectable is proportional to volume making smaller chemiresistors able to detect lesser amounts of analyte.

Covington, Elizabeth Laura

41

Micro-miniature gas chromatograph column disposed in silicon wafers  

DOEpatents

A micro-miniature gas chromatograph column is fabricated by forming matching halves of a circular cross-section spiral microcapillary in two silicon wafers and then bonding the two wafers together using visual or physical alignment methods. Heating wires are deposited on the outside surfaces of each wafer in a spiral or serpentine pattern large enough in area to cover the whole microcapillary area inside the joined wafers. The visual alignment method includes etching through an alignment window in one wafer and a precision-matching alignment target in the other wafer. The two wafers are then bonded together using the window and target. The physical alignment methods include etching through vertical alignment holes in both wafers and then using pins or posts through corresponding vertical alignment holes to force precision alignment during bonding. The pins or posts may be withdrawn after curing of the bond. Once the wafers are bonded together, a solid phase of very pure silicone is injected in a solution of very pure chloroform into one end of the microcapillary. The chloroform lowers the viscosity of the silicone enough that a high pressure hypodermic needle with a thumbscrew plunger can force the solution into the whole length of the spiral microcapillary. The chloroform is then evaporated out slowly to leave the silicone behind in a deposit.

Yu, Conrad M. (Antioch, CA)

2000-01-01

42

Micro-miniature gas chromatograph column disposed in silicon wafers  

SciTech Connect

A micro-miniature gas chromatograph column is fabricated by forming matching halves of a circular cross-section spiral microcapillary in two silicon wafers and then bonding the two wafers together using visual or physical alignment methods. Heating wires are deposited on the outside surfaces of each wafer in a spiral or serpentine pattern large enough in area to cover the whole microcapillary area inside the joined wafers. The visual alignment method includes etching through an alignment window in one wafer and a precision-matching alignment target in the other wafer. The two wafers are then bonded together using the window and target. The physical alignment methods include etching through vertical alignment holes in both wafers and then using pins or posts through corresponding vertical alignment holes to force precision alignment during bonding. The pins or posts may be withdrawn after curing of the bond. Once the wafers are bonded together, a solid phase of very pure silicone is injected in a solution of very pure chloroform into one end of the microcapillary. The chloroform lowers the viscosity of the silicone enough that a high pressure hypodermic needle with a thumbscrew plunger can force the solution into the whole length of the spiral microcapillary. The chloroform is then evaporated out slowly to leave the silicone behind in a deposit.

Yu, C.M.

2000-05-30

43

Growth of carbon nanotubes by Fe-catalyzed chemical vapor processes on silicon-based substrates  

Microsoft Academic Search

In this paper, a site-selective catalytic chemical vapor deposition synthesis of carbon nanotubes on silicon-based substrates has been developed in order to get horizontally oriented nanotubes for field effect transistors and other electronic devices. Properly micro-fabricated silicon oxide and polysilicon structures have been used as substrates. Iron nanoparticles have been obtained both from a thin Fe film evaporated by e-gun

Renato Angelucci; Rita Rizzoli; Vincenzo Vinciguerra; Maria Fortuna Bevilacqua; Sergio Guerri; Franco Corticelli; Mara Passini

2007-01-01

44

Fabrication of a gas flow device consisting of micro-jet pump and flow sensor  

Microsoft Academic Search

A gas-flow device consisting of a valveless micro jet pump and flow sensor has been designed and fabricated using a Si micromachining process. The valveless micro pump is composed of a piezoelectric lead zirconate titanate (PZT) diaphragm actuator and flow channels. The design of the valvless pump focuses on a crosss junction formed by the neck of the pump chamber

Katsuhiko Tanaka; Van T. Dau; Tomonori Otake; Thien X. Dinh; Susumu Sugiyama

2008-01-01

45

New Concept of Micro-Gas-Turbine-Based Cogeneration Package for Performance Improvement in Practical Use  

NASA Astrophysics Data System (ADS)

As energy consumption is rapidly increasing in the commercial sector in Japan, the market potential for a micro-gas turbine is expected to grow significantly if thermal efficiency is improved further. One way of improving thermal efficiency is to introduce a steam injection system that uses steam from the heat recovery steam generator. We have recently carried out several tests using a micro-gas turbine (Capstone C60). Test results show that this new device utilizing steam injection can improve some key performance parameters for output, thermal efficiency and emissions. The stable operation of the micro-gas turbine with steam injection was confirmed under various operating conditions. On the basis of the above findings, we hereby propose the use of a micro-gas-turbine-based cogeneration package with steam injection driven by a heat recovery steam generator (HRSG) with supplementary firing.

Mochizuki, Kenichiro; Shibata, Satoshi; Inoue, Umeo; Tsuchiya, Toshiaki; Sotouchi, Hiroko; Okamoto, Masanori

46

Nanolasers grown on silicon-based MOSFETs.  

PubMed

We report novel indium gallium arsenide (InGaAs) nanopillar lasers that are monolithically grown on (100)-silicon-based functional metal-oxide-semiconductor field effect transistors (MOSFETs) at low temperature (410 °C). The MOSFETs maintain their performance after the nanopillar growth, providing a direct demonstration of complementary metal-oxide-semiconudctor (CMOS) compatibility. Room-temperature operation of optically pumped lasers is also achieved. To our knowledge, this is the first time that monolithically integrated lasers and transistors have been shown to work on the same silicon chip, serving as a proof-of-concept that such integration can be extended to more complicated CMOS integrated circuits. PMID:22714204

Lu, Fanglu; Tran, Thai-Truong D; Ko, Wai Son; Ng, Kar Wei; Chen, Roger; Chang-Hasnain, Connie

2012-05-21

47

Porous silicon based biomaterials for bone tissue engineering  

NASA Astrophysics Data System (ADS)

An ideal material for orthopaedic tissue engineering should be biocompatible, biodegradable, osteoconductive, osteoinductive, mechanically stable, and widely available. Porous silicon (PSi), a silicon based material fulfills these criteria. It is biocompatible and biodegradable, and supports hydroxyapatite nucleation. The micro/nano-architecture of PSi may regulate cell behavior. The surface chemistry of PSi is flexible so that the interfacial properties between this material and living cells can be tailored easily by chemical modifications. In this work, we have demonstrated that PSi can support and promote primary osteoblast growth, protein matrix synthesis, and mineralization both in vitro and in vivo. The osteoconductivity of PSi can be controlled by altering the micro/nano architecture of porous interface. Macro-scale porous silicon (MacPSi), with pore openings of approximately 1 mum, has the highest osteoconductive potential in vitro. We have further developed a hybrid biomaterial by coating MacPSi with recombinant adenovirus vectors encoding bone morphogenetic proteins, thus making the material osteoinductive both in vitro and in vivo. With this material, we are closer to an osteoconductive and osteoinductive medical device with drug delivery functions. The knowledge obtained in this study on the interaction between living cells and a semiconductor material will also be the foundation for further development of electronic and optoelectronic biointerfaced devices.

Sun, Wei

48

Thermal-Power Consumption and Heat Transfer Coefficients in Micro-thin-film Gas Sensors  

Microsoft Academic Search

The thermal-power consumption is a important parameter of gas sensor. The temperature distribution of thin film gas sensor, temperature of metal guard, the dissipating heat of lead-wires and the regularity of sensors heat transfer coefficient varying with size of heat-transfer surface and working temperature was studied. The formula of thermal-power consumption of micro-thin-film gas sensors yielded in this paper, from

Liu Xiaojian; Qu Lu; Li Donghua; Xing Jianping; Qiu Nanwan

2006-01-01

49

Carbon nanotube and graphene based gas micro-sensors fabricated by dielectrophoresis on silicon  

Microsoft Academic Search

A gas sensor based upon an array of reduced graphene oxide (RGO) and single wall carbon nanotube (SWNT) micro-assemblies is presented. Due to the nature of their structure and exceptional surface-to-volume ratio, graphene sheets and carbon nanotubes demonstrate unparalleled chemisorption properties, providing greater sensitivities than a bulk material. Micro-assemblies of RGO platelets and SWNT's were created on lithographically patterned electrode

Samuel MacNaughton; Sameer Sonkusale; Sumedh Surwade; Srikanth Ammu; Sanjeev Manohar

2010-01-01

50

Gas pressurized hot embossing for transcription of micro-features  

Microsoft Academic Search

Hot embossing has proven productive for the parallel replication of precision micro-features onto thermoplastic substrates at low cost. During conventional hot embossing, the substrate and the stamp are brought into contact and are compressed directly by the hot plates of the machine. The accuracy and area of replication are limited due to the inherent non-uniform pressure distribution. Si-wafers are too

J.-H. Chang; S.-Y. Yang

2003-01-01

51

High Resolution Double Layer Resist System Using New Silicone Based Negative Resist (SNR)  

Microsoft Academic Search

We propose a new silicone based negative resist (SNR) for a high resolution double layer resist system. SNR shows high sensitivity to an e-beam, D0.5{=}5 muC\\/cm2, with high contrast gamma{=}2, and excellent resistance to reactive ion etching under oxygen gas. A submicron pattern with a high aspect ratio can be easily fabricated with the SNR\\/AZ double layer resist system. It

Masao Morita; Akinobu Tanaka; Saburo Imamura; Toshiaki Tamamura; Osamu Kogure

1983-01-01

52

On the Maxwell gas-wall interaction model for micro/nano gas flows  

NASA Astrophysics Data System (ADS)

A systematic study on the goodness of Maxwell model in the modeling of micro/nano gas flows in the entire Knudsen range is presented. We evaluate the model by examining key macroscopic properties such as temperature, density and pressure, in a couple classical benchmark problems namely thermal Couette and thermal transpiration problems. Our reference solutions are obtained from a hybrid DSMC/MD algorithm developed in house. We have found that while the extended Maxwell model, that is, the Maxwell model with three accommodation coefficients, is in general more accurate than the classical Maxwell model, the differences in the magnitudes of the predicted macroscopic quantities are quite small except the pressure profile of the thermal Couette problem, in which case the classical Maxwell model predicts a pressure trend that is opposite to that predicted by both the extended Maxwell model and the hybrid MD/DSMC simulations. This fact is also demonstrated in our study of the thermal transpiration coefficient, ?. The value predicted by the extended Maxwell model depends highly on the tangential accommodation coefficient which is consistent with the experimental findings, while the classical Maxwell model, as is well known, predicts a coefficient that is independent of the accommodation coefficient. We have also found that there is a correlation between the reflected velocity components. Neither the extended Maxwell model nor the CL model is able to capture this correlation.

Liang, Tengfei; Li, Qi; Ye, Wenjing

2012-11-01

53

Numerical analysis on gas separator with thermal transpiration in micro channels  

NASA Astrophysics Data System (ADS)

A gas separator that can induce a large variation of mole fraction by a small temperature difference in a single membrane is proposed. The separator makes use of two effects: The first effect is the thermal transpiration through microchannels in the membrane; the second is the accumulation of the effect of micro-channels in the counter flow of gas mixture that flows around the membrane. The numerical results show that small gas separation effects of numerous micro-channels are accumulated to induce a large variation of the mole fraction along the membrane. The numerical calculation is carried out by the direct simulation Monte Carlo (DSMC) method and a fluid model based on the mass conservation which is shown to be able to simulate the DSMC result. The performance of the device is investigated for several temperature differences between the two sides of the membrane. The relation to the membrane gas separation by Knudsen diffusion is also discussed.

Sugimoto, Hiroshi; Hibino, Masaya

2012-11-01

54

Efficient liquid atomization using gas flows and novel micro-machining techniques  

Microsoft Academic Search

Micro-machining techniques based upon the use of X-ray lithography and electrodeposition were adapted to the field of two-phase fluid mechanics. Control of the gas\\/liquid interface structure on the micron size scale was shown to have a significant impact on the gas-assisted liquid atomization process. Two series of experiments were conducted in which the goal was to create liquid sprays with

Herman Emil Snyder

1997-01-01

55

Energy resolution in X-ray detecting micro-strip gas counters  

NASA Astrophysics Data System (ADS)

Systematic measurements of the energy resolution available from a Micro-Strip Gas Counter (MSGC) are presented. The effect of factors such as bias potential, gas filling and strip geometry on the energy resolution are examined in detail and related to a simple model. The geometry of the MSGC is adapted to permit ``wall-less'' detection of X-rays and this results in useful improvements in the pulse height spectra.

Bateman, J. E.; Connolly, J. F.; Derbyshire, G. E.; Duxbury, D. M.; Mir, J. A.; Spill, E. J.; Stephenson, R.

2002-05-01

56

Near-wall effects in rarefied gas micro-flows: some modern hydrodynamic approaches  

Microsoft Academic Search

Methods for simulating the critical near-wall region in hydrodynamic models of gas micro-flows are discussed. Two important non-equilibrium flow features – velocity slip at solid walls, and the Knudsen layer (which extends one or two molecular mean free paths into the gas from a surface) – are investigated using different modelling approaches. In addition to a discussion of Maxwell’s slip

Lynne O’Hare; Duncan A. Lockerby; Jason M. Reese; David R. Emerson

2007-01-01

57

The fabrication of all-silicon micro gas chromatography columns using gold diffusion eutectic bonding  

NASA Astrophysics Data System (ADS)

Temperature programming of gas chromatography (GC) separation columns accelerates the elution rate of chemical species through the column, increasing the speed of analysis, and hence making it a favorable technique to speedup separations in microfabricated GCs (micro-GC). Temperature-programmed separations would be preferred in an all-silicon micro-column compared to a silicon-Pyrex® micro-column given that the thermal conductivity and diffusivity of silicon is 2 orders of magnitude higher than Pyrex®. This paper demonstrates how to fabricate all-silicon micro-columns that can withstand the temperature cycling required for temperature-programmed separations. The columns were sealed using a novel bonding process where they were first bonded using a gold eutectic bond, then annealed at 1100 °C to allow gold diffusion into silicon and form what we call a gold diffusion eutectic bond. The gold diffusion eutectic-bonded micro-columns when examined using scanning electron microscopy (SEM), scanning acoustic microscopy (SAM) and blade insertion techniques showed bonding strength comparable to the previously reported anodic-bonded columns. Gas chromatography-based methane injections were also used as a novel way to investigate proper sealing between channels. A unique methane elution peak at various carrier gas inlet pressures demonstrated the suitability of gold diffusion eutectic-bonded channels as micro-GC columns. The application of gold diffusion eutectic-bonded all-silicon micro-columns to temperature-programmed separations (120 °C min-1) was demonstrated with the near-baseline separation of n-C6 to n-C12 alkanes in 35 s.

Radadia, A. D.; Salehi-Khojin, A.; Masel, R. I.; Shannon, M. A.

2010-01-01

58

Fabry-Pérot cavity sensors for multipoint on-column micro gas chromatography detection.  

PubMed

We developed and characterized a Fabry-Pérot (FP) sensor module based micro gas chromatography (microGC) detector for multipoint on-column detection. The FP sensor was fabricated by depositing a thin layer of metal and a layer of gas-sensitive polymer consecutively on the endface of an optical fiber, which formed the FP cavity. Light partially reflected from the metal layer and the polymer-air interface generated an interference spectrum, which shifted as the polymer layer absorbed the gas analyte. The FP sensor module was then assembled by inserting the FP sensor into a hole drilled in the wall of a fused-silica capillary, which can be easily connected to the conventional gas chromatography (GC) column through a universal quick seal column connector, thus enabling on-column real-time detection. We characterized the FP sensor module based microGC detector. Sensitive detection of various gas analytes was achieved with subnanogram detection limits. The rapid separation capability of the FP sensor module assembled with both single- and tandem-column systems was demonstrated, in which gas analytes having a wide range of polarities and volatilities were well-resolved. The tandem-column system obtained increased sensitivity and selectivity by employing two FP sensor modules coated with different polymers, showing great system versatility. PMID:20441156

Liu, Jing; Sun, Yuze; Howard, Daniel J; Frye-Mason, Greg; Thompson, Aaron K; Ja, Shiou-Jyh; Wang, Siao-Kwan; Bai, Mengjun; Taub, Haskell; Almasri, Mahmoud; Fan, Xudong

2010-06-01

59

Multiloop control strategy of a solid oxide fuel cell and micro gas turbine hybrid system  

Microsoft Academic Search

Solid oxide fuel cell and micro gas turbine (SOFC\\/MGT) hybrid system is a promising distributed power technology. In order to ensure the system safe operation as well as long lifetime of the fuel cell, an effective control manner is expected to regulate the temperature and fuel utilization at the desired level, and track the desired power output. Thus, a multi-loop

Xiao-Juan Wu; Xin-Jian Zhu

60

A six-wafer combustion system for a silicon micro gas turbine engine  

Microsoft Academic Search

As part of a program to develop a micro gas turbine engine capable of producing 10-50 W of electrical power in a package less than one cubic centimeter in volume, we present the design, fabrication, packaging, and experimental test results for the 6-wafer combustion system for a silicon microengine. Comprising the main nonrotating functional components of the engine, the device

A. Mehra; Xin Zhang; A. A. Ayon; I. A. Waitz; M. A. Schmidt; C. M. Spadaccini

2000-01-01

61

CFD IN THE DESIGN OF AN ULTRA MICRO GAS TURBINE COMBUSTION CHAMBER  

Microsoft Academic Search

This paper addresses the design process of a combustor for an ultra micro gas turbine in general and the role of CFD in this process in particular. First, however the physical chal- lenges arising from the scale reduction of the devices are reviewed in order to understand the restrictions upon the design space. Based on these challenges, some strategies for

J. Trilla; D. Verstraete; N. de Bruyn; P. Hendrick

62

New Concept of Micro-Gas-Turbine-Based Cogeneration Package for Performance Improvement in Practical Use  

Microsoft Academic Search

As energy consumption is rapidly increasing in the commercial sector in Japan, the market potential for a micro-gas turbine is expected to grow significantly if thermal efficiency is improved further. One way of improving thermal efficiency is to introduce a steam injection system that uses steam from the heat recovery steam generator. We have recently carried out several tests using

Kenichiro Mochizuki; Satoshi Shibata; Umeo Inoue; Toshiaki Tsuchiya; Hiroko Sotouchi; Masanori Okamoto

2006-01-01

63

Porous silicon-based photonic crystals optical devices for polarization band-pass filtering and sensing applications  

NASA Astrophysics Data System (ADS)

We report on the design of porous silicon based polarization band-pass filters, which is not only have excellent optical properties with p-polarization transmittance and s-polarization reflectance in the NIR field, but also can be used for excellent biosensor and gas sensing applications.

Lü, Xiao-yi; Tao, Xue; Jia, Zhen-hong

2008-11-01

64

High-Speed Gas Bearings for Micro-Turbomachinery  

Microsoft Academic Search

\\u000a The mechanical design and architecture of high-speed rotating machinery, independent of size or scale, are strongly governed\\u000a by the rotordynamic behavior of the spool and its bearing arrangement. Large-scale gas turbine engines yield multi-spool shaft\\u000a constructions where the rolling contact bearings are close to the centerline of the engine supporting the shaft and disk assemblies\\u000a as shown in Fig. 6.1

Zoltán S. Spakovszky

65

Numerical simulations of gas-liquid two-phase flows in a micro porous structure  

NASA Astrophysics Data System (ADS)

The lattice Boltzmann method for two-phase fluid flows is applied to the simulations of gas-liquid two-phase flows in a micro porous structure for various capillary numbers at low Reynolds numbers. The behaviors of the gas-liquid interface and the velocities of the two-phase fluid in the structure are simulated, and the permeability of gas and liquid through the structure are estimated from the calculated results. By changing the void fraction, the contact angle of the interface on walls, and the surface tension, the effect of these properties on the behaviors and the permeability of the two-phase flows in the micro porous structure is investigated. It is found that the permeability of liquid flows depends on the contact angle and it increases for hydrophobic walls. It is also seen that liquid flows are choked in pores for large void fractions and low capillary numbers.

Tomiyasu, J.; Inamuro, T.

2009-04-01

66

Micro-flame ionization detector with a novel structure for portable gas chromatograph.  

PubMed

A micro-flame ionization detector (micro-FID) for portable gas chromatograph (GC) based on conventional mechanical fabrication techniques was developed and evaluated. Structure was redesigned and dimensions were optimized for best performance. Air is introduced from upper part of the detector, flowing downwards into the burning chamber along a narrow round gap between the collection electrode and the inner wall of the detector body, forming a uniform flow field around the burning jet. The lowest detection limit of the mu-FID was 5x10(-13)g/s for n-decane, with a linear response range of five orders of magnitude. The consumption of gases is only 10 ml/min for hydrogen, and 120 ml/min for air, that is about 1/3 of the gases required for conventional FIDs. A comparative study between the micro-FID and commercial FID was also performed that proved the advantages of the micro-FID. The micro-FID is simple in structure, low heating power, and low consumption of gases that not only decrease the cost of running, but also increase the portability of GC for filed applications. PMID:20678662

Wang, Jianwei; Wang, Hua; Duan, Chunfeng; Guan, Yafeng

2010-06-11

67

MICRO-HEAT ENGINES, GAS TURBINES, AND ROCKET ENGINES THE MIT MICROENGINE PROJECT  

Microsoft Academic Search

This is a report on work in progress on microelectrical and mechanical systems (MEMS)-based gas turbine en- gines, turbogenerators, and rocket engines currently un- der development at MIT. Fabricated in large numbers in parallel using semiconductor manufacturing techniques, these engines are based on micro-high speed rotating machinery with the same power density as that achieved in their more familiar, full-sized

A. H. Epstein; S. D. Senturia; O. Al-Midani; A. Ayon; K. Breuer; K-S Chen; F. E. Ehrich; E. Esteve; L. Frechette; G. Gauba; R. Ghodssi; C. Groshenry; S. Jacobson; J. L. Kerrebrock; J. H. Lang; J. Lopata; A. Mehra; J. O. Mur Miranda; S. Nagle; D. J. Orr; E. Piekos; M. A. Schmidt; G. Shirley; S. M. Spearing; C. S. Tan; I. A. Waitz

1997-01-01

68

Thermal analysis of silicon carbide based micro hotplates for metal oxide gas sensors  

Microsoft Academic Search

This paper reports on the thermal analysis of a novel micro hotplate design for metal oxide gas sensors. The hotplate is a 500?m×500?m square shaped membrane made of 2?m thick polycrystalline 3C–SiC on a silicon substrate suspended by four legs. The membrane is heated by an on chip platinum thin film heater. For reasons of a short response time and

G. Wiche; A. Berns; H. Steffes; E. Obermeier

2005-01-01

69

A non-sealed solid oxide fuel cell micro-stack with two gas channels  

Microsoft Academic Search

Non-sealed solid oxide fuel cell (NS-SOFC) micro-stacks with two gas channels were fabricated and operated successfully under various CH4\\/O2 gas mixtures in a box-like stainless-steel chamber. The cells with an anode-facing-cathode configuration were connected in serial by zigzag sliver sheets. Each cell consisted of the Ni\\/yttria-stabilized zirconia (YSZ) anode, the YSZ electrolyte, and the Sm0.2Ce0.8O1.9-impregnated (La0.75Sr0.25)0.95MnO3 cathode. In this configuration,

Yanting Tian; Zhe Lü; Bo Wei; Zhihong Wang; Mingliang Liu; Wenyuan Li; Xiqiang Huang; Wenhui Su

2011-01-01

70

Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor  

NASA Astrophysics Data System (ADS)

Electron energy spectra of Xe atoms at He filled micro-plasma afterglow gas analyzer were observed using Collisional Electron Spectroscopy (CES) method [1]. According to CES, diffusion path confinement for characteristic electrons makes it possible to measure electrons energy distribution function (EEDF) at a high (up to atmospheric) gas pressure. Simple geometry micro-plasma CES sensor consists of two plane parallel electrodes detector and microprocessor-based acquisition system providing current-voltage curve measurement in the afterglow of the plasma discharge. Electron energy spectra are deduced as 2-nd derivative of the measured current-voltage curve to select characteristic peaks of the species to be detected. Said derivatives were obtained by the smoothing-differentiating procedure using spline least-squares approximation of a current-voltage curve. Experimental results on CES electron energy spectra at 10-40 Torr in pure He and in admixture with 0.3% Xe are discussed. It demonstrates a prototype of the new miniature micro-plasma sensors for industry, safety and healthcare applications. [1]. A.A.Kudryavtsev, A.B.Tsyganov. US Patent 7,309,992. Gas analysis method and ionization detector for carrying out said method, issued December 18, 2007.

Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander

2012-10-01

71

A role for graphene in silicon-based semiconductor devices.  

PubMed

As silicon-based electronics approach the limit of improvements to performance and capacity through dimensional scaling, attention in the semiconductor field has turned to graphene, a single layer of carbon atoms arranged in a honeycomb lattice. Its high mobility of charge carriers (electrons and holes) could lead to its use in the next generation of high-performance devices. Graphene is unlikely to replace silicon completely, however, because of the poor on/off current ratio resulting from its zero bandgap. But it could be used to improve silicon-based devices, in particular in high-speed electronics and optical modulators. PMID:22094694

Kim, Kinam; Choi, Jae-Young; Kim, Taek; Cho, Seong-Ho; Chung, Hyun-Jong

2011-11-16

72

Gas-liquid two-phase flows in rectangular polymer micro-channels  

NASA Astrophysics Data System (ADS)

This study addresses gas-liquid two-phase flows in polymer (PMMA) micro-channels with non-molecularly smooth and poorly wetting walls (typical contact angle of 65°) unlike previous studies conducted on highly wetting molecularly smooth materials (e.g., glass/silicon). Four fundamentally different topological flow regimes (Capillary Bubbly, Segmented, Annular, Dry) were identified along with two transitory ones (Segmented/Annular, Annular/Dry) and regime boundaries were identified from the two different test chips. The regime transition boundaries were influenced by the geometry of the two-phase injection, the aspect ratio of the test micro-channels, and potentially the chip material as evidenced from comparisons with the results of previous studies. Three principal Segmented flow sub-regimes (1, 2, and 3) were identified on the basis of quantified topological characteristics, each closely correlated with two-phase flow pressure drop trends. Irregularity of the Segmented regimes and related influencing factors were addressed and discussed. The average bubble length associated with the Segmented flows scaled approximately with a power law of the liquid volumetric flow ratio, which depends on aspect ratio, liquid superficial velocity, and the injection system. A simplified semi-empirical geometric model of gas bubble and liquid plug volumes provided good estimates of liquid plug length for most of the segmented regime cases and for all test-channel aspect ratios. The two-phase flow pressure drop was measured for the square test channels. Each Segmented flow sub-regime was associated with different trends in the pressure drop scaled by the viscous scale. These trends were explained in terms of the quantified flow topology (measured gas bubble and liquid plug lengths) and the number of bubble/plug pairs. Significant quantitative differences were found between the two-phase pressure drop in the polymer micro-channels of this study and those obtained from previous glass/silicon micro-channel studies, indicating that the effect of wall surface properties is important. Pressure drop trends on the capillary scale along gas bubbles extracted from the measurements in square micro-channels indicated a linear dependence on the Capillary number and did not agree with those predicted by highly idealized theory primarily because explicit and implicit assumptions in the theory were not relevant to practical conditions in this study.

Kim, Namwon; Evans, Estelle T.; Park, Daniel S.; Soper, Steven A.; Murphy, Michael C.; Nikitopoulos, Dimitris E.

2011-08-01

73

A role for graphene in silicon-based semiconductor devices  

Microsoft Academic Search

As silicon-based electronics approach the limit of improvements to performance and capacity through dimensional scaling, attention in the semiconductor field has turned to graphene, a single layer of carbon atoms arranged in a honeycomb lattice. Its high mobility of charge carriers (electrons and holes) could lead to its use in the next generation of high-performance devices. Graphene is unlikely to

Jae-Young Choi; Taek Kim; Seong-Ho Cho; Hyun-Jong Chung; Kinam Kim

2011-01-01

74

Silicon-based Packaging Platform for Light Emitting Diode  

Microsoft Academic Search

In this paper, we demonstrate a silicon-based packaging platform for a package component of light emitting diode (LED) by silicon bulk micromachining technologies and using a silicon substrate with embedded solder interconnections to dissipate heat and match thermal expansion coefficient (CTE). The objective is to develop an LED package that can overcome LED life, high operating voltage, package degradation and

C. Tsou; Y. S. Huang; G. W. Lin

2005-01-01

75

The Characterization of Silicon-Based Molecular Devices  

Microsoft Academic Search

In order to realize molecular electronic (ME) technology, an intermediate integration with more traditional silicon-based technologies will likely be required. However, there has been little effort to develop the metrology needed to enable the fabrication and characterization of CMOS-compatible ME devices. In this work, we used two different characterization techniques to evaluate the potential of molecular electronic device materials with

N. Gergel-Hackett; C. A. Hacker; L. J. Richter; O. A. Kirillov; C. A. Richter

2007-01-01

76

Enhanced reflection from arrays of silicon based inverted nanocones  

NASA Astrophysics Data System (ADS)

We report enhanced reflection displayed by arrays of silicon based inverted nanocones. Theoretical studies suggest that such arrays display enhanced reflection and photonic band gaps within the optical and near infrared regions. Measured results show three to four fold enhancement in reflection and agree well with calculations. Such arrays can be used to enhance infrared reflection in photovoltaic devices which mostly contribute towards heating.

Butt, Haider; Dai, Qing; Rajasekharan, Ranjith; Wilkinson, Timothy D.; Amaratunga, Gehan A. J.

2011-09-01

77

Toward a scalable, silicon-based quantum computing architecture  

Microsoft Academic Search

Advances in quantum devices have brought scalable quantum computation closer to reality. We focus on the system-level issues of how quantum devices can be brought together to form a scalable architecture. In particular, we examine promising silicon-based proposals. We discover that communication of quantum data is a critical resource in such proposals. We find that traditional techniques using quantum SWAP

Dean Copsey; Mark Oskin; Francois Impens; Tzvetan Metodiev; A. Cross; F. T. Chong; I. L. Chuang; J. Kubiatowicz

2003-01-01

78

Efficient liquid atomization using gas flows and novel micro-machining techniques  

NASA Astrophysics Data System (ADS)

Micro-machining techniques based upon the use of X-ray lithography and electrodeposition were adapted to the field of two-phase fluid mechanics. Control of the gas/liquid interface structure on the micron size scale was shown to have a significant impact on the gas-assisted liquid atomization process. Two series of experiments were conducted in which the goal was to create liquid sprays with Sauter mean diameters below 50 mum while improving the energy transfer from the pressurized gas to creating liquid surface area. Pressurized internal two-phase flows were created using a variety of methods to introduce the gas to the liquid. Modification of the internal flow structures, from annular to slug to bubbly, were related to changes in the external liquid breakup processes. Observations of small droplet production caused by the disintegration of an expanding gas bubble produced the second series of tests in which a liquid film was directly impinged by thousands of tiny gas jets, ranging in diameter from 50 to 7 mum. High speed, high magnification photography was utilized along with phase Doppler particle sizing to document the impact of micro-orifice size, and quality on the resulting spray field. A change of atomization regime was observed when the gas flow orifices were reduced in size from 50 to 7 mum in diameter. The smaller gas jets operated in a unique atomization mode which yielded reduced drop sizes from energy inputs comparable to values reported for flash atomization, without the solubility or phase change restrictions of that atomization technique. The drop sizes were shown to be a function of film thickness to the one third power, and were insensitive to gas pressure and gas type. The new drop ejection mechanism of liquid atomization allows for both the efficient production of sprays with SMD values below 20 mum, and provides the unique capability of de-coupling the drop size from the drop velocity. This characteristic could provide enhanced designer control of a spray mixing process.

Snyder, Herman Emil

79

Simulation of micro gas bubble generation of uniform diameter in an ultrasonic field by a boundary element method  

Microsoft Academic Search

Micro gas bubbles of uniform diameter are generated periodically when liquid under pressure near the tip of a cylindrical needle is oscillated by an ultrasonic wave. Here, using a boundary element method, we simulated this gas-liquid interface behavior previously reported by Makuta et al. [J. Fluid Mech. 548, 113 (2006)]. Although the simulation model is simple because the flow field

Toshinori Makuta; Fumio Takemura

2006-01-01

80

Direct measurement of neutral gas heating in a radio-frequency electrothermal plasma micro-thruster  

NASA Astrophysics Data System (ADS)

Direct measurements and modelling of neutral gas heating in a radio-frequency (13.56 MHz) electrothermal collisional plasma micro-thruster have been performed using rovibrational band matching of the second positive system of molecular nitrogen (N2) for operating pressures of 4.5 Torr down to 0.5 Torr. The temperature measured with decreasing pressure for 10 W power input ranged from 395 K to 530 K in pure N2 and from 834 K to 1090 K in argon with 1% N2. A simple analytical model was developed which describes the difference in temperatures between the argon and nitrogen discharges.

Greig, A.; Charles, C.; Hawkins, R.; Boswell, R.

2013-08-01

81

Frequency response of atmospheric pressure gas breakdown in micro/nanogaps  

NASA Astrophysics Data System (ADS)

In this paper, we study gas breakdown in micro/nanogaps at atmospheric pressure from low RF to high millimeter band. For gaps larger than about 10 ?m, the breakdown voltage agrees with macroscale vacuum experiments, exhibiting a sharp decrease at a critical frequency, due to transition between the boundary- and diffusion-controlled regimes, and a gradual increase at very high frequencies as a result of inefficient energy transfer by field. For sub-micron gaps, a much lower breakdown is obtained almost independent of frequency because of the dominance of field emission.

Semnani, Abbas; Venkattraman, Ayyaswamy; Alexeenko, Alina A.; Peroulis, Dimitrios

2013-08-01

82

Headspace Solid Phase Micro Extraction Gas Chromatographic Determination of Fenthion in Human Serum  

PubMed Central

A simple and effective analytical procedure was developed for the determination of fenthion residues in human serum samples. The sample treatment was performed using the headspace solid-phase micro extraction with polyacrylate fiber, which has the advantage to require low amount of serum (1 mL) without tedious pre-treatment. The quantification of fenthion was carried out by gas chromatography-mass spectrometry and the recoveries ranged from 79 to 104% at two spiking levels for 6 replicates. Detection and quantification limits were calculated as 1.51 and 4.54 ng/mL of serum respectively. Two fenthion metabolites fenoxon and fenthion–sulfoxide were also identified.

Kasiotis, Konstantinos M.; Souki, Helen; Tsakirakis, Angelos N.; Carageorgiou, Haris; Theotokatos, Spiridon A.; Haroutounian, Serkos A.; Machera, Kyriaki

2008-01-01

83

78 FR 21100 - Grant of Authority for Subzone Status; Dow Corning Corporation (Silicon-Based Products); Midland, MI  

Federal Register 2010, 2011, 2012, 2013

...Subzone Status; Dow Corning Corporation (Silicon-Based Products); Midland, MI Pursuant...certain manufacturing authority at the silicon- based products manufacturing facility...activity related to the manufacturing of silicon-based products at the facility of...

2013-04-09

84

Silicon-based monolithically integrated whispering-gallery mode resonators with buried waveguides  

NASA Astrophysics Data System (ADS)

We report on the realization and characterization of a silicon-based integrated optical platform which implements a vertical coupling scheme between a Whispering-gallery type microresonator and a buried dielectric waveguide. The vertical coupling allows for the separation of the resonator and the waveguide into different planes, which enables one to realize the optical components in different materials/thicknesses. The high optical quality of this cavity micro-optical system follows from the accurate planarization of the waveguide topography, which is achieved by multiple depositions-and- reflows of a borophosphosilicate glass over strip waveguides. Importantly, we demonstrate the feasibility of our approach for wafer-scale mass fabrication of freestanding planar resonators suspended in air and coupled to integrated bus waveguides. This opens the door for the realization of stable all-integrated resonator systems for optomechanical and metrological applications and has the potential to substitute today's complicated fiber-taper coupling schemes.

Ghulinyan, M.; Ramiro Manzano, F.; Guider, R.; Prtljaga, N.; Pucker, G.; Pavesi, L.

2012-05-01

85

Enhancement of Gas Response of ZnO Micro-nano Structured Films through O2 Plasma Treatment  

Microsoft Academic Search

Layers of ZnO micro-nano structures were deposited on quartz substrates and subsequently plasma treated in O2 and N2. It was found that exposure to O2 plasma enhanced gas response to ethanol vapor of the ZnO layers by a factor eight, while exposure to N2 plasma deteriorated the gas response. The gas response enhancement upon O2 plasma treatment could be correlated

Ippei Nagatomo; Ryohei Uchino; Yanbo Li; Masaki Shuzo; Ichiro Yamada; Jean-Jacques Delaunay

2009-01-01

86

Energy Resolution and Counting Properties of Micro-Strip Gas Counter for X-Ray Detecting  

NASA Astrophysics Data System (ADS)

A two-dimensional micro-strip Gas Chamber (MSGC) with a 20 × 20 mm2 detection area had been developed. The MSGC had a thin diamond film of 10 ?m deposited on a silicon wafer as substrate and lots of micro-strip anode and cathode electrodes made by multi-chip module technology. Energy resolution and pulse signal under 5.9 keV 55Fe X-rays were measured by a multi-channel energy spectrometer with different voltage under room temperature in atmospheric pressure. Results indicated high signal-to-noise ratio, count rate ?103 Hz and stable gas gain of the MSGC were obtained. When Ar:CH4=90:10, drift voltage, cathode voltage and anode voltage was -1000 V, -650 V and 0 V, respectively. However, the energy resolution of 12.3% for 5.9 keV 55Fe X-rays was achieved. The effects of cathode voltage and drift voltage on energy resolution and count rate were also obtained.

Su, Qingfeng; Xia, Yiben; Wang, Linjun; Yang, Ying; Shi, Weimin

87

A study of micro-strip gas chambers for the measurement of ionizing radiation  

NASA Astrophysics Data System (ADS)

This dissertation presents some empirical and theoretical studies of micro-strip gas chambers (MSGC) with emphasis on their gain and energy resolution characteristics. The analysis was extended to the micro-gap chamber (MGC), which is a new and enhanced type of MSGC. MSGCs and MGCs are newly developed detectors of ionizing radiation closely related to the well-established multi-wire proportional counter. In MSGCs, the wires are replaced by alternating narrow anode strips and wider cathode strips deposited on an insulator by the photolithography technique. In MGCs, a continuous cathode plane is used instead of strips and a thin and narrow insulator separates the anode strip and the cathode. Because of the reduced distance between the anode and the cathode compared with that of wire chambers, it is possible to create an extremely intense local electric field near the anode surface. Thus, MSGCs and MGCs can be operated with fairly low applied voltages to achieve practical gas gain. MSGCs and MGCs also have excellent rate capabilities and position resolutions. In addition, MSGCs and MGCs have demonstrated slightly better energy resolution than wire chambers. The present study has emphasized gas gain measurements with different detector geometries, electrostatic field calculations, and the statistical behavior of the gas amplification process. Results from gain measurements were consistent with predictions from the electrostatic models for different MSGC structures. A new type of configuration involving germanium extended cathodes was evaluated experimentally to address the problem of sparking at high anode voltage. It was possible to obtain a relatively high gas gain with the new structure. Short-term drift of the gas gain was also minimized. In the study of the avalanche statistics, it was demonstrated by modeling the electric field configurations that MSGCs and MGCs are expected to show lower variances of the gas amplification compared with the conventional wire chamber. This reduced variance is due to the larger electric field gradients inherent in these configurations, and is likely to be a contributing factor to the better energy resolution reported from MSGCs and MGCs.

Miyamoto, Jun

1997-08-01

88

Investigation of the Frequency Shift of a SAD Circuit Loop and the Internal Micro-Cantilever in a Gas Sensor  

PubMed Central

Micro-cantilever sensors for mass detection using resonance frequency have attracted considerable attention over the last decade in the field of gas sensing. For such a sensing system, an oscillator circuit loop is conventionally used to actuate the micro-cantilever, and trace the frequency shifts. In this paper, gas experiments are introduced to investigate the mechanical resonance frequency shifts of the micro-cantilever within the circuit loop(mechanical resonance frequency, MRF) and resonating frequency shifts of the electric signal in the oscillator circuit (system working frequency, SWF). A silicon beam with a piezoelectric zinc oxide layer is employed in the experiment, and a Self-Actuating-Detecting (SAD) circuit loop is built to drive the micro-cantilever and to follow the frequency shifts. The differences between the two resonating frequencies and their shifts are discussed and analyzed, and a coefficient ? related to the two frequency shifts is confirmed.

Guan, Liu; Zhao, Jiahao; Yu, Shijie; Li, Peng; You, Zheng

2010-01-01

89

Microbial assay for tryptophan using silicon-based transducer  

Microsoft Academic Search

A potentiometric microbial assay for tryptophan was devised using silicon-based transducer and auxotrophic bacteria, and the chemical performances are discussed. Escherichia coli WP2, an auxotrophic mutant requiring tryptophan for its growth, was used as tryptophan recognition element, and extracellular pH changes resulting from metabolic activity was monitored by the light-addressable potentiometric sensor (LAPS). The potentiometric sensor detected the acidification of

Atsushi Seki; Kazunari Kawakubo; Mitsuhiro Iga; Satoshi Nomura

2003-01-01

90

Silicon-based packaging platform for light-emitting diode  

Microsoft Academic Search

A novel concept of silicon-based packaging platform with microreflector and embedded electrode-guided interconnections was development for a package component of a light-emitting diode (LED). TracePro and ANSYS software were respectively used to understand the optical and thermal characteristics of the package component. Simulation results show the microreflector at several certain specific dimensions can be used to achieve high brightness, and

Chingfu Tsou; Yu-Sheng Huang

2006-01-01

91

Silicon Based Anodes for Li-Ion Batteries  

SciTech Connect

Silicon is environmentally benign and ubiquitous. Because of its high specific capacity, it is considered one of the most promising candidates to replace the conventional graphite negative electrode used in today's Li ion batteries. Silicon has a theoretical specific capacity of nearly 4200 mAh/g (Li21Si5), which is 10 times larger than the specific capacity of graphite (LiC6, 372 mAh/g). However, the high capacity of silicon is associated with huge volume changes (more than 300 percent) when alloyed with lithium, which can cause severe cracking and pulverization of the electrode and lead to significant capacity loss. Significant scientific research has been conducted to circumvent the deterioration of silicon based anode materials during cycling. Various strategies, such as reduction of particle size, generation of active/inactive composites, fabrication of silicon based thin films, use of alternative binders, and the synthesis of 1-D silicon nanostructures have been implemented by a number of research groups. Fundamental mechanistic research has also been performed to better understand the electrochemical lithiation and delithiation process during cycling in terms of crystal structure, phase transitions, morphological changes, and reaction kinetics. Although efforts to date have not attained a commercially viable Si anode, further development is expected to produce anodes with three to five times the capacity of graphite. In this chapter, an overview of research on silicon based anodes used for lithium-ion battery applications will be presented. The overview covers electrochemical alloying of the silicon with lithium, mechanisms responsible for capacity fade, and methodologies adapted to overcome capacity degradation observed during cycling. The recent development of silicon nanowires and nanoparticles with significantly improved electrochemical performance will also be discussed relative to the mechanistic understanding. Finally, future directions on the development of silicon based anodes will be considered.

Zhang, Jiguang; Wang, Wei; Xiao, Jie; Xu, Wu; Graff, Gordon L.; Yang, Zhenguo; Choi, Daiwon; Li, Xiaolin; Wang, Deyu; Liu, Jun

2012-06-15

92

A silicon-based shear force sensor: development and characterization  

Microsoft Academic Search

A silicon-based shear force sensitive sensor is developed using microfabrication technology. Four ion-implanted piezoresistors are embedded in a silicon diaphragm and used as independent strain gauges. An epoxy mesa is built-up on top of the diaphragm to convert an applied force to a distributed stress. Both the normal and the shear components of an applied force can be resolved from

Lin Wang; David J. Beebe

2000-01-01

93

Silicon-Based Plasmonics for On-Chip Photonics  

Microsoft Academic Search

Silicon-based photonic devices dissipate substantially less power and provide a significantly greater information bandwidth than electronic components. Unfortunately, large-scale integration of photonic devices has been limited by their large, wavelength-scale size and the weak optical response of Si. Surface plasmons may overcome these two limitations. Combining the high localization of electronic waves with the propagation properties of optical waves, plasmons

Jennifer A. Dionne; Luke A. Sweatlock; Matthew T. Sheldon; A. Paul Alivisatos; Harry A. Atwater

2010-01-01

94

[Research on improving sensitivity of the characteristic spectrum in micro-gas monitor].  

PubMed

In order to realize the indoor micro noxious gas real-time monitor, and enhance measuring accuracy based on the characteristic spectrum examination method, a characteristic wavelengths filtration window was designed, in which the container is full with the highly concentrated testing gas. The container with the highly concentrated testing gas was used as the filtration window, the standard air as the reference window, the air chamber sufficient testing gas for testing density. The experiment demonstrated that using the WQF-520-FTIR infrared spectroscope to obtain the infrared absorption spectrum of dipropyl sebacate, there were mainly four characteristic wavelength lines: 3.385 26, 3.417.64, 5.797 11, and 8.561 65 microm, and the corresponding extinction was 1.520 0, 1.542 1, 2.431 8 and 1.352 6 respectively. The smallest content examined was 50 ppb, but using the characteristic wavelengths filtration window, the method could realize the 10(-4) nm magnitude alignment. The sensitivity was enhanced nearly 10 times, and the characteristic wavelengths filtration window method has the merits of high sensitivity, no discontinuity, real-time examination, and so on. PMID:20827993

Sun, Yun-qiang; Lu, Xu-tao

2010-07-01

95

Analytical estimation of neutron yield in a micro gas-puff X pinch  

SciTech Connect

In this paper, we present the basic concepts for developing a micro x pinch as a small-scale neutron source. For compact sources, these concepts offer repetitive function at higher yields and pulsing rates than competing methods. The uniqueness of these concepts arises from the use of microelectronic technology to reduce the size of the target plasma and to efficiently heat the target gas. The use of repetitive microelectromechanical systems (MEMs) gas puff technology, as compared to cryogenic wires or solid targets (for the beam-target alternatives), has the potential to be robust and have a long lifetime because the plasma is not created from solid surfaces. The modeling suggests that a 50 J at the wall plug pulse could provide >10{sup 5} tritium (DT) neutrons and 10{sup 3} deuterium (DD) neutrons at temperatures of a few keV. At 1 kHz, this would be >10{sup 8} and 10{sup 6} neutrons per second, DT and DD, respectively, with a 250 {mu}m anode-cathode gap. DT gas puff devices may provide >10{sup 12} neutrons/s operating at 1 kHz and requiring 100 kW. The MEMs approach offers potentially high pulse rates and yields.

Derzon, M. S.; Galambos, P. C. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Hagen, E. C. [NSTec, North Las Vegas, Nevada 89031 (United States)

2012-12-01

96

New micro-pattern gas detector based on a 2D position readout mesh  

NASA Astrophysics Data System (ADS)

Micro-pattern gas detectors (MPGD) could become suitable devices to carry out time-resolved X-ray diffraction experiments in the sub-millisecond time scale at synchrotron radiation facilities. Nevertheless, these devices are not free of problems. Among other problems are the build-up of ions in the detector components and the susceptibility of the materials in the structure to dielectric breakdown. Here, we present a new MPGD design we have called micro reading mesh chamber (MRMC). Its layout is based on a resistive anode, support pillars and a mesh formed by two planes of pick-up strips. In order to prevent charging up, a common problem with GEMs and MPGD in general, a minimum amount of dielectric material has been used in the design. The aim has been to avoid dielectric near the drift paths of the ions. To prevent dielectric breakdown, a resistive anode with guard rings at the base of the pillars has been designed. Finally, to improve the cathode signals quality, we use a mesh to read the avalanche. In this manner the size of the induced charge is larger than in more conventional geometries.

Fernández Banqué, F.; Ramos-Lerate, I.; Martínez, J. C.; Beltrán, D.; Bordas, J.; Key, M.

2007-04-01

97

Development of a MicroStrip Gas Chamber as a Time-Resolved Area Detector.  

PubMed

A two-dimensional microstrip gas chamber (MSGC) has been developed with a 10 cm-square detection area and an ultrafast read-out system. The MSGC was made using multi-chip module (MCM) technology, and has a very thin substrate of 17 micro m and many anodes and back strips, both with 200 micro m pitches. The new read-out system, in which the hit addresses of the electrodes were sequentially encoded to the hit positions by a synchronous clock, handles data rates of up to 10(7) events s(-1) from MSGCs. This enables the acquisition of fast and sequential digital images. Furthermore, since the MSGC is a real photon-counting detector, the timing of the photons, to an accuracy of a few tens of nanoseconds, and energy can be recorded. Here, the performance of the MSGC system as a real-time area detector is reported, and the abilities of this system are discussed. PMID:15263488

Tanimori, T; Aoki, S; Nishi, Y; Ochi, A

1998-05-01

98

Rapid, sensitive, and multiplexed on-chip optical sensors for micro-gas chromatography.  

PubMed

We developed and characterized a rapid, sensitive and integrated optical vapor sensor array for micro-gas chromatography (?GC) applications. The sensor is based on the Fabry-Pérot (FP) interferometer formed by a micrometre-thin vapor-sensitive polymer layer coated on a silicon wafer. The thickness and the refractive index of the polymer vary in response to the vapor analyte, resulting in a change in the reflected intensity of the laser impinged on the sensor. In our study, four different polymers were coated on four wells pre-etched on a silicon wafer to form a spatially separated sensor array. A CMOS imager was employed to simultaneously monitor the polymers' response, thus enabling multiplexed detection of a vapor analyte passing through the GC column. A sub-second detection time was demonstrated. In addition, a sub-picogram detection limit was achieved, representing orders of magnitude improvement over the on-chip vapor sensors previously reported. PMID:22245960

Reddy, Karthik; Guo, Yunbo; Liu, Jing; Lee, Wonsuk; Oo, Maung Kyaw Khaing; Fan, Xudong

2012-01-16

99

Rarefied-gas heat transfer in micro- and nanoscale Couette flows.  

PubMed

The physics of the heat conduction and viscous dissipation in rarefied gases is analyzed and discussed. A heat transfer model valid for arbitrary Knudsen numbers, defined as the ratio of the molecular mean free path to the characteristic length of channels, is derived by treating the heat transfer behavior in the slip and transition regimes as an intermediate function of continuum heat transfer model and free molecular heat transfer model. Comparison studies reveal that this model not only shows good agreement with the numerical results based on the direct simulation Monte Carlo method, but also has some unique features that can overcome the deficiencies existing in the previous models. Therefore, this model is capable to study the heat transport phenomena in very dilute gas Couette flows through micro/nanochannels more accurately. PMID:20365361

Zhou, W D; Liu, B; Yu, S K; Hua, W

2010-01-26

100

Cathode sheath and hydrogen Balmer lines modelling in a micro-hollow gas discharge  

NASA Astrophysics Data System (ADS)

We present a model of the cathode sheath (CS) processes responsible for the broadening of the hydrogen Balmer beta line recorded from a micro-hollow gas discharge (MHGD) and used for simultaneous diagnostics of plasma and CS parameters. The MHGD was generated in a microhole (diameter 100 ?m at narrow side and 130 ?m at wider side) of a gold-alumina-gold sandwich in the pressure ranges: (100-900) mbar in argon with traces of hydrogen, and (100-400) mbar in pure hydrogen. The electron number density is determined from the plasma broadened line width of the central part of Balmer beta profile, while the average value of electric field strength in the CS and the CS thickness are determined from the extended line wings induced by the dc Stark effect.

Spasojevi?, Dj

2012-11-01

101

A Hybrid Continuum / Particle Approach for Micro-Scale Gas Flows  

NASA Astrophysics Data System (ADS)

A hybrid continuum/particle approach is proposed for micro scale gas flows in this paper. The approach couples the DSMC-IP method and a Navier-Stokes solver with an adaptive interface. The continuum solver uses the particle cells as ghost cells because the IP method preserves the hydrodynamic information that the continuum solver uses. In order to generate particles from the continuum side, two strategies are proposed. The first one uses a condition similar to the Marshak condition in generating particles through the interface. The second strategy adopts buffer cells and reservoir cells, which avoids directly generating particles. The interface is determined by a continuum breakdown parameter that is evaluated in every time step. In order to track the interface, a mapping technique is used in the code. Numerical examples show that the hybrid approach couples the continuum solver and the particle method very smoothly. Simulated results also show the effects of the cutoff value of the continuum breakdown parameter.

Sun, Quanhua; Boyd, Iain D.; Candler, Graham V.

2003-05-01

102

Development of the scalable readout system for micro-pattern gas detectors and other applications  

NASA Astrophysics Data System (ADS)

Developed within RD51 Collaboration for the Development of Micro-Pattern Gas Detectors Technologies, the Scalable Readout System (SRS) is intended as a general purpose multi-channel readout solution for a wide range of detector types and detector complexities. The scalable architecture, achieved using multi-Gbps point-to-point links with no buses involved, allows the user to tailor the system size to his needs. The modular topology enables the integration of different front-end ASICs, giving the user the possibility to use the most appropriate front-end for his purpose or to build a heterogeneous experimental apparatus which integrates different front-ends into the same DAQ system. Current applications include LHC upgrade activities, geophysics or homeland security applications as well as detector R&D. The system architecture, development and running experience will be presented, together with future prospects, ATCA implementation options and application possibilities.

Martoiu, S.; Muller, H.; Tarazona, A.; Toledo, J.

2013-03-01

103

Characteristics analysis and dynamic responses of micro-gas-lubricated journal bearings with a new slip model  

Microsoft Academic Search

In this paper, a new slip model based on kinetic theory of gases for gas-lubricated journal bearings in micro-electro-mechanical systems (MEMS) is applied using a physical approach. The corresponding modified governing equation and mathematic model are presented and the flow rate is plotted versus the inverse Knudsen number. Pressure distributions along the gas bearing at various Knudsen numbers and bearing

Wen-Ming Zhang; Guang Meng; Hai Huang; Jian-Bin Zhou; Jie-Yu Chen; Di Chen

2008-01-01

104

Demonstration of a silicon-based quantum cellular automata cell  

NASA Astrophysics Data System (ADS)

We report on the demonstration of a silicon-based quantum cellular automata (QCA) unit cell incorporating two pairs of metallically doped (n+) phosphorus-implanted nanoscale dots, separated from source and drain reservoirs by nominally undoped tunnel barriers. Metallic cell control gates, together with Al-AlOx single electron transistors for noninvasive cell-state readout, are located on the device surface and capacitively coupled to the buried QCA cell. Operation at subkelvin temperatures was demonstrated by switching of a single electron between output dots, induced by a driven single electron transfer in the input dots. The stability limits of the QCA cell operation were also determined.

Mitic, M.; Cassidy, M. C.; Petersson, K. D.; Starrett, R. P.; Gauja, E.; Brenner, R.; Clark, R. G.; Dzurak, A. S.; Yang, C.; Jamieson, D. N.

2006-07-01

105

Determination of priority organic micro-pollutants in water by gas chromatography coupled to triple quadrupole mass spectrometry  

Microsoft Academic Search

A multiclass method has been developed for screening, quantification and confirmation of organic micro-pollutants in water by gas chromatography coupled to mass spectrometry with a triple quadrupole analyzer. The work has been focused on the determination of more than 50 compounds belonging to different chemical families: 19 organochlorine and organophosphorus insecticides, 6 herbicides, 7 polychlorinated biphenyls, 16 polycyclic aromatics hydrocarbons,

E. Pitarch; C. Medina; T. Portolés; F. J. López; F. Hernández

2007-01-01

106

Thermodynamic optimization for an open cycle of an externally fired micro gas turbine (EFmGT). Part 1: Thermodynamic modelling  

Microsoft Academic Search

The principle of optimally tuning the air flow rate and subsequent distribution of pressure drops is applied to optimize the performance of a thermodynamic model for an open regenerative cycle of an externally fired micro gas turbine power plant with pressure drop irreversibilities by using finite-time thermodynamics and considering the size constraints of the real plant. There are eight flow

Lingen Chen; Wanli Zhang; Fengrui Sun

2011-01-01

107

Simultaneous determination of chlorinated organic compounds from environmental samples using gas chromatography coupled with a micro electron capture detector and micro-plasma atomic emission detector  

NASA Astrophysics Data System (ADS)

Water and sediment samples were screened simultaneously for the presence of polychlorinated organic compounds using gas chromatography (GC) coupled with an micro electron capture detector (?-ECD) and a newly developed helium plasma based on a micro-atomic emission detector (?-AED). The GC column effluent was split 15:85 between two detectors. In this way, two chromatograms, one obtained by ?-ECD and another by ?-AED, were recorded simultaneously. ?-, ?-hexachlorocyclohexane and p, p'-DDE were detected. RSDs of the monitoring results from the two detection methods were <20% for the three compounds. A detection limit of 8.5 pg and at least 3 orders of magnitude of linear range for ?-AED was observed.

Quan, Xie; Chen, Shuo; Platzer, Bernhard; Chen, Jingwen; Gfrerer, Marion

2002-01-01

108

A novel micropreconcentrator employing a laminar flow patterned heater for micro gas chromatography  

NASA Astrophysics Data System (ADS)

A simple micromachined process based on one photomask is developed for a novel micropreconcentrator (µPCT) used in a micro gas chromatograph (µGC). Unique thick silver heating microstructures with a high surface area for microheater of µPCT are fabricated by combining the microfluidic laminar flow technique and the Tollens’ reaction within a microchannel. Silver deposition using this laminar flow patterning technique provides a higher deposition rate and easier microfabrication compared to conventional micromachined technologies for thick metal microstructures (>200 µm). An amorphous and porous carbon film that functions as an adsorbent is grown on microheaters inside the microchannel. The µPCT can be heated to >300 °C rapidly by applying a constant electrical power of ˜1 W with a heating rate of 10 °C s-1. Four volatile organic compounds, acetone, benzene, toluene and xylene, are collected through the proposed novel µPCTs and separated successfully using a 17 m long gas chromatography column. The peak widths at half height (PWHHs) of the four compounds are relatively narrow (<6 s), and the minimum PWHH of 3.75 s is obtained for acetone. The preconcentration factors are >38 000 for benzene and toluene.

Tian, W.-C.; Wu, T. H.; Lu, C.-J.; Chen, W. R.; Sheen, H. J.

2012-06-01

109

Mass flow rate prediction of pressure-temperature-driven gas flows through micro/nanoscale channels  

NASA Astrophysics Data System (ADS)

In this paper, we study mass flow rate of rarefied gas flow through micro/nanoscale channels under simultaneous thermal and pressure gradients using the direct simulation Monte Carlo (DSMC) method. We first compare our DSMC solutions for mass flow rate of pure temperature-driven flow with those of Boltzmann-Krook-Walender equation and Bhatnagar-Gross-Krook solutions. Then, we focus on pressure-temperature-driven flows. The effects of different parameters such as flow rarefaction, channel pressure ratio, wall temperature gradient and flow bulk temperature on the thermal mass flow rate of the pressure-temperature-driven flow are examined. Based on our analysis, we propose a correlated relation that expresses normalized mass flow rate increment due to thermal creep as a function of flow rarefaction, normalized wall temperature gradient and pressure ratio over a wide range of Knudsen number. We examine our predictive relation by simulation of pressure-driven flows under uniform wall heat flux (UWH) boundary condition. Walls under UWH condition have non-uniform temperature distribution, that is, thermal creep effects exist. Our investigation shows that developed analytical relation could predict mass flow rate of rarefied pressure-driven gas flows under UWH condition at early transition regime, that is, up to Knudsen numbers of 0.5.

Akhlaghi, Hassan; Roohi, Ehsan

2013-02-01

110

Porous silicon-based biosensor for pathogen detection.  

PubMed

A porous silicon-based biosensor for rapid detection of bacteria was fabricated. Silicon (0.01 ohmcm, p-type) was anodized electrochemically in an electrochemical Teflon cell containing ethanoic hydrofluoric acid solution to produce sponge-like porous layer of silicon. Anodizing conditions of 5 mA/cm2 for 85 min proved best for biosensor fabrication. A single-tube chemiluminescence-based assay, previously developed, was adapted to the biosensor for detection of Escherichia coli. Porous silicon chips were functionalized with a dioxetane-Polymyxin B (cell wall permeabilizer) mixture by diffusion and adsorption on to the porous surface. The reaction of beta-galactosidase enzyme from E. coli with the dioxetane substrate generated light at 530 nm. Light emission for the porous silicon biosensor chip with E. coli was significantly greater than that of the control and planar silicon chip with E. coli (P<0.01). Sensitivity of the porous silicon biosensor was determined to be 101-102 colony forming units (CFU) of E. coli. The porous silicon-based biosensor was fabricated and functionalized to successfully detect E. coli and has potential applications in food and environmental testing. PMID:15626624

Mathew, Finny P; Alocilja, Evangelyn C

2005-02-15

111

Characteristics analysis and dynamic responses of micro-gas-lubricated journal bearings with a new slip model  

NASA Astrophysics Data System (ADS)

In this paper, a new slip model based on kinetic theory of gases for gas-lubricated journal bearings in micro-electro-mechanical systems (MEMS) is applied using a physical approach. The corresponding modified governing equation and mathematic model are presented and the flow rate is plotted versus the inverse Knudsen number. Pressure distributions along the gas bearing at various Knudsen numbers and bearing numbers are plotted and the load carrying capacities are also obtained. A numerical analysis of a rigid rotor supported by gas-lubricated journal bearings is presented for dynamic behaviour. The slip flow effect on the properties, including pressure distribution, load carrying capacity and dynamic coefficients, of the micro-gas-lubricated journal bearings and dynamic responses of the micro rotor-bearing system are estimated and analysed in detail. It is shown that the dynamic coefficients increase with increasing bearing number except for two damping coefficients and the rotor-bearing system runs at a much higher rotating speed to keep stable when slip flow occurs. Moreover, the oscillation period of the rotor operating with the slip model is longer than that with the continuum flow. In addition, the whirl frequency is reduced from 0.422 to 0.079 under the slip effect. Therefore, the results of this study contribute to a further understanding of the characteristics and nonlinear dynamics of gas-film rotor-bearing systems in MEMS.

Zhang, Wen-Ming; Meng, Guang; Huang, Hai; Zhou, Jian-Bin; Chen, Jie-Yu; Chen, Di

2008-08-01

112

Effectiveness of a Micro Gas Turbine Cogeneration System using in a Residential Area  

NASA Astrophysics Data System (ADS)

For energy conservation and CO2 reduction, cogeneration systems may be useful. This paper shows the effectiveness of the cogeneration system, used in a residential area and designed to supply heat by hot water pipelines. The cogeneration system consists of a micro gas turbine (MGT) generator and a boiler. Entire heat load is supplied by the MGT or boiler, while an electric load may be supplied by an electric power company. Optimal diameter of the hot water pipeline becomes large when the load density becomes low. Total heat supply loss is less then 10% for moderate temperature region. However, it exceeds 20% for a sparse load in the cold region. The MGT should generates heat just required by the load for the primary energy or cost minimum operation. In the moderate temperature region, primary energy reduction ratio is positive in almost all cases, while it becomes negative in the cold region. On the other hand, CO2 emission almost always decreases in some extent. In the warm or moderate temperature region, MGT cogeneration systems are effective for energy conservation. They are also effective for CO2 reduction in almost all cases.

Kawamoto, Teru; Yamada, Masahiro

113

Silicon-based sleeve devices for chemical reactions  

DOEpatents

A silicon-based sleeve type chemical reaction chamber is described that combines heaters, such as doped polysilicon for heating, and bulk silicon for convection cooling. The reaction chamber combines a critical ratio of silicon and silicon nitride to the volume of material to be heated (e.g., a liquid) in order to provide uniform heating, yet low power requirements. The reaction chamber will also allow the introduction of a secondary tube (e.g., plastic) into the reaction sleeve that contains the reaction mixture thereby alleviating any potential materials incompatibility issues. The reaction chamber may be utilized in any chemical reaction system for synthesis or processing of organic, inorganic, or biochemical reactions, such as the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction, which are examples of a synthetic, thermal-cycling-based reaction. The reaction chamber may also be used in synthesis instruments, particularly those for DNA amplification and synthesis. 32 figs.

Northrup, M.A.; Mariella, R.P. Jr.; Carrano, A.V.; Balch, J.W.

1996-12-31

114

Silicon-based sleeve devices for chemical reactions  

DOEpatents

A silicon-based sleeve type chemical reaction chamber that combines heaters, such as doped polysilicon for heating, and bulk silicon for convection cooling. The reaction chamber combines a critical ratio of silicon and silicon nitride to the volume of material to be heated (e.g., a liquid) in order to provide uniform heating, yet low power requirements. The reaction chamber will also allow the introduction of a secondary tube (e.g., plastic) into the reaction sleeve that contains the reaction mixture thereby alleviating any potential materials incompatibility issues. The reaction chamber may be utilized in any chemical reaction system for synthesis or processing of organic, inorganic, or biochemical reactions, such as the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction, which are examples of a synthetic, thermal-cycling-based reaction. The reaction chamber may also be used in synthesis instruments, particularly those for DNA amplification and synthesis.

Northrup, M. Allen (Berkeley, CA); Mariella, Jr., Raymond P. (Danville, CA); Carrano, Anthony V. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

1996-01-01

115

Air-hydrogen fuel cell with two-level slotted silicon-based electrode  

NASA Astrophysics Data System (ADS)

The design of a two-level slotted silicon-based electrode and a technology of its manufacturing by anisotropic etching of (110)-oriented Si wafers are described. The electrode contains two layers, one with wide channels and another with narrow slots. The first layer provides gas transport in an air-hydrogen fuel cell (FC), while the second layer can perform the functions of (i) a catalyst carrier and (ii) a gas-diffusion layer. It is shown that, by filling the narrow-slot layer with a carbon-platinum catalytic ink, it is possible to obtain a higher specific power on the anode due to an increase in the effective area as compared to that of a flat catalyst carrier. The operation of the two-level slotted electrode as a gas-diffusion layer was studied for an FC operating in a free-breathing cathode regime. This FC is characterized by increased power compared to that with a carbon paper and a single-level slotted Si electrode.

Astrova, E. V.; Tomasov, A. A.; Goryachev, D. N.; Zelenina, N. K.; Terukova, E. E.

2010-05-01

116

Magneto-ballistic transport through micro-structured junctions on a curved two-dimensional electron gas  

Microsoft Academic Search

We investigate theoretically the ballistic transport in a two-dimensional electron gas, which is rolled up as a tube and is micro-structured into a Hall bar. A uniform magnetic field applied to such a curved surface results in a non-uniform perpendicular magnetic field. The bend resistances become asymmetric with respect to the orientation of the magnetic field due to the varying

G. Papp; F. M. Peeters

2009-01-01

117

In-situ formation of nanoparticles within a silicon-based matrix  

DOEpatents

A method for encapsulating nanoparticles with an encapsulating matrix that minimizes aggregation and maintains favorable properties of the nanoparticles. The matrix comprises silicon-based network-forming compounds such as ormosils and polysiloxanes. The nanoparticles are synthesized from precursors directly within the silicon-based matrix.

Thoma, Steven G. (Albuquerque, NM); Wilcoxon, Jess P. (Albuquerque, NM); Abrams, Billie L. (Albuquerque, NM)

2008-06-10

118

Visualization of the gas flow in fuel cell bipolar plates using molecular flow seeding and micro-particle image velocimetry  

NASA Astrophysics Data System (ADS)

Main components of proton exchange membrane fuel cells are bipolar plates that electrically connect the electrodes and provide a gas flow to the membrane. We investigate the flow in the channel structures of bipolar plates. Flow seeding is used to visualize the propagating and mixing gas stream. It is shown that a part of the gas is transported perpendicularly to the channel structure. An analysis of the diffusion compared with the convection shows different transport behavior for both flow directions. Additionally, the convective flow field is investigated in detail near the channel wall using Micro-PIV in a Reynolds-number-scaled liquid fluid system. For a more exact comparison of the experimental setups, flow seeding in both gas and liquid systems is performed.

Hecht, Christian; van der Schoot, Nadine; Kronemayer, Helmut; Wlokas, Irenaeus; Lindken, Ralph; Schulz, Christof

2012-03-01

119

A highly tunable silicone-based magnetic elastomer with nanoscale homogeneity  

NASA Astrophysics Data System (ADS)

Magnetic elastomers have been widely pursued for sensing and actuation applications. Silicone-based magnetic elastomers have a number of advantages over other materials such as hydrogels, but aggregation of magnetic nanoparticles within silicones is difficult to prevent. Aggregation inherently limits the minimum size of fabricated structures and leads to non-uniform response from structure to structure. We have developed a novel material that is a complex of a silicone polymer (polydimethylsiloxane-co-aminopropylmethylsiloxane) adsorbed onto the surface of magnetite (?-Fe2O3) nanoparticles 7–10 nm in diameter. The material is homogenous at very small length scales (<100 nm) and can be crosslinked to form a flexible magnetic material, which is ideally suited for the fabrication of micro- to nanoscale magnetic actuators. The loading fraction of magnetic nanoparticles in the composite can be varied smoothly from 0 to 50 wt% without loss of homogeneity, providing a simple mechanism for tuning actuator response. We evaluate the material properties of the composite across a range of nanoparticle loading, and demonstrate a magnetic-field-induced increase in compressive modulus as high as 300%. Furthermore, we implement a strategy for predicting the optimal nanoparticle loading for magnetic actuation applications, and show that our predictions correlate well with experimental findings.

Evans, Benjamin A.; Fiser, Briana L.; Prins, Willem J.; Rapp, Daniel J.; Shields, Adam R.; Glass, Daniel R.; Superfine, R.

2012-02-01

120

Simulation and characterization of silicon-based 0.5-MHz ultrasonic nozzles  

NASA Astrophysics Data System (ADS)

This paper compares the simulation results with the experimental results of impedance analysis and longitudinal vibration measurement of micro-fabricated 0.5 MHz silicon-based ultrasonic nozzles. Impedance analysis serves as a good diagnostic tool for evaluation of longitudinal vibration of the nozzles. Each nozzle is made of a piezoelectric drive section and a silicon-resonator consisting of multiple Fourier horns each with half wavelength design and twice amplitude magnification. The experimental results verified the simulation prediction of one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude gain at the nozzle tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical value of 2n. Using this design, very high vibration amplitude at the nozzle tip can be achieved with no reduction in the tip cross sectional area. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization.

Song, Y. L.; Tsai, S. C.; Chen, W. J.; Chou, Y. F.; Tseng, T. K.; Tsai, C. S.

2004-01-01

121

Gas transport through nano and micro composites of natural rubber (NR) and their blends with carboxylated styrene butadiene rubber (XSBR) latex membranes  

Microsoft Academic Search

The gas permeability coefficient of nano and micro composites of natural rubber, carboxylated styrene butadiene rubber and 70:30 natural rubber\\/carboxylated styrene butadiene rubber blend membranes has been investigated with special reference to type of filler, gases, filler loading and pressure. The layered silicates such as sodium bentonite and sodium fluorohectorite were the nanofillers used and the conventional micro fillers were

Ranimol Stephen; C. Ranganathaiah; Siby Varghese; Kuruvilla Joseph; Sabu Thomas

2006-01-01

122

Gas-Particle Two-Phase Jet Flow from Slot Nozzle and Micro-Blasting Process  

Microsoft Academic Search

Recently, the micro-blasting process has been widely used to process brittle material, and a conventional circular nozzle has been commonly used. But the cutting performance of a circular nozzle does not process a large area well, so the use of a slot nozzle is considered. In this study, in order to improve the cutting performance of the micro-blasting nozzle, a

Masaki Sugimoto; Toshihiko Shakouchi; Kohei Hayakawa; Moriyasu Izawa

2006-01-01

123

A parylene-filled-trench technique for thermal isolation in silicon-based microdevices  

NASA Astrophysics Data System (ADS)

Microdevices prepared in a silicon substrate have been widely used in versatile fields due to the matured silicon-based microfabrication technique and the excellent physical properties of silicon material. However, the high thermal conductivity of silicon restricts its application in most thermal microdevices, especially devices comprising different temperature zones. In this work, a parylene-filled-trench technique was optimized to realize high-quality thermal isolation in silicon-based microdevices. Parylene C, a heat transfer barricading material, was deposited on parallel high-aspect-ratio trenches, which surrounded the isolated target zones. After removing the remnant silicon beneath the trenches by deep reactive ion etching from the back side, a high-quality heat transfer barrier was obtained. By using narrow trenches, only 5 µm thick parylene was required for a complete filling, which facilitated multi-layer interconnection thereafter. The parylene filling performance inside the high-aspect-ratio trench was optimized by two approaches: multiple etch-deposition cycling and trench profile controlling. A 4 × 6 array, in which each unit was kept at a constant temperature and was well thermally isolated individually, was achieved on a silicon substrate by using the present parylene-filled-trench technique. The preliminary experimental results indicated that the present parylene-filled-trench structure exhibited excellent thermal isolation performance, with a very low power requirement of 0.134 mW (K mm2)-1 for heating the isolated silicon unit and a high thermal isolation efficiency of 72.5% between two adjacent units. Accompanied with high-quality isolation performance, the microdevices embedded the present parylene-filled-trench structure to retain a strong mechanical connection larger than 400 kPa between two isolated zones, which is very important for a high-reliability-required micro-electro-mechanical-system (MEMS) device. Considering its room-temperature processing essence, the present parylene-filled-trench technique is believed to be a promising isolation method in the post-complementary metal oxide semiconductor MEMS integration.

Lei, Yinhua; Wang, Wei; Yu, Huaiqiang; Luo, Yingcun; Li, Ting; Jin, Yufeng; Zhang, Haixia; Li, Zhihong

2009-03-01

124

Root canal hydrophobization by dentinal silanization: improvement of silicon-based endodontic treatment tightness.  

PubMed

A new strategy to improve silicon-based endodontic treatment tightness by dentine hydrophobization is presented in this work: root dentine was silanized to obtain a hydrophobic dentine-sealer interface that limits fluid penetration. This strategy was based on the grafting of aliphatic carbon chains on the dentine through a silanization with the silane end groups [octadecyltrichlorosilane (OTS) and octadecyltriethoxysilane]. Dentine surface was previously pretreated, applying ethylenediaminetetraacetic acid and sodium hypochlorite, to expose hydroxyl groups of collagen for the silane grafting. Collagen fibers exposure after pretreatment was visible with scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy showed their correct exposition for the silanization (amide I and II, with 1630, 1580, and 1538 cm?¹ peaks corresponding to the vibration of C=O and C--N bonds). The grafting of aliphatic carbon chains was confirmed by FTIR (peaks at 2952 and 2923 cm?¹ corresponding to the stretching of C--H bonds) and by the increasing of the water contact angle. The most efficient hydrophobization was obtained with OTS in ethyl acetate, with a water contact angle turning from 51° to 109°. Gas and liquid permeability tests showed an increased seal tightness after silanization: the mean gas and water flows dropped from 2.02 × 10?? to 1.62 × 10?? mol s?¹ and from 10.8 × 10?³ to 5.4 × 10?³ µL min?¹, respectively. These results show clear evidences to turn hydrophilic dentine surface into a hydrophobic surface that may improve endodontic sealing. PMID:23359546

Collart Dutilleul, Pierre-Yves; Fonseca, Cesar Gaitán; Zimányi, László; Romieu, Olivier; Pozos-Guillén, Amaury J; Semetey, Vincent; Cuisinier, Frédéric; Pérez, Elías; Levallois, Bernard

2013-01-29

125

Basic Study on Capillary Flow between Liquid-Liquid-Gas Interface for Fluid Handling in Space and Micro Actuators  

NASA Astrophysics Data System (ADS)

In fluid phenomena, the effects of wettability and surface tension become dominant as the scale becomes smaller. Since these forces become dominant in a micro-gravitational field, this study was focused on the similarities between micro scale systems and a micro-gravitational field. We attempted to control a fluid by actively controlling the wettability and surface tension. It was discovered that a new type of spontaneous flow occurs when a drop of silicon oil is placed on a layer of fluorinart. This flow is attributed to evaporation, since the flow stops when the system is accommodated in a hermetically sealed vessel. The thickness of the silicon oil drops is thought to be about 1 mm. As can be seen from the velocity distribution the driving force of this flow appears to originate at the point of intersection between a gas and two liquids. An experimental device that applied this driving force was manufactured in order to produce rotational force. The impeller of this device distributes wettability. When the impeller was floated on the fluorinert and when a silicon droplet dyed red with a syringe was adhered only to one blade of the impeller, the impeller began to rotate spontaneously. This kind of surface tension phenomena is useful not only for space but also for micro machines.

Sakurai, M.; Yoshihara, S.; Ohnishi, M.

126

Miniature liquid flow sensor and feedback control of electroosmotic and pneumatic flows for a micro gas analysis system.  

PubMed

Accurate liquid flow control is important in most chemical analyses. In this work, the measurement of liquid flow in microliters per minute was performed, and feedback control of the flow rate was examined. The flow sensor was arranged on a channel made in a polydimethylsiloxane (PDMS) block. The center of the channel was cooled by a miniature Peltier device, and the change in temperature balance along the channel formed by the flow was measured by two temperature sensors. Using this flow sensor, feedback flow control was examined with two pumping methods. One was the electroosmotic flow method, made by applying a high voltage (HV) between the reagent and waste reservoirs; the other was the piezo valve method, in which a micro-valve-seat was fabricated in a PDMS cavity with a silicone diaphragm. The latter was adopted for a micro gas analysis system (microGAS) for measuring atmospheric H2S and SO2. The obtained baselines were stable, and better limits of detection were obtained. PMID:16429774

Ohira, Shin-Ichi; Toda, Kei

2006-01-01

127

Optimization of a micro-strip gas chamber as a two-dimensional neutron detector using gadolinium converter  

NASA Astrophysics Data System (ADS)

A micro-strip gas chamber (MSGC) has been under development as a two-dimensional position sensitive detector for neutron scattering experiments at the high-intensity proton accelerator facilities. The MSGC requirements as a neutron detector are high counting rate, high detection efficiency, high positional resolution, stability and large area coverage. The purpose of this paper is to verify the properties of Gadolinium as a MSGC converter. The arrangements of a capillary plate and MSGC gas pressure have been optimized by simulation of a Gadolinium converter. As a result of that, a position resolution of 160?m and n/? ratio of 200 were obtained at the gas pressure of 0.02atm. In view of ?-ray sensitivity, the further improvement is required for practical applications.

Masaoka, Sei; Nakamura, Tatsuya; Yamagishi, Hideshi; Soyama, Kazuhiko

2003-11-01

128

Micro Industry Equipments  

NASA Astrophysics Data System (ADS)

Advanced states of art of MEMS (Micro Electro Mechanical Systems) technology have been applied to micro industry equipments. These are electrostatically levitated ring rotor gyroscope and micro energy source for self moving machines like robots, maintenance systems used in narrow spaces, components for multi-column electron beam lithography and multi-probe data storage, micro gas control systems, micro/nano mold, micro contactor and thermal RF relay for LSI testing and nano-instruments which performs high sensitivity and spatial resolution.

Esashi, Masayoshi; Ono, Takahito; Tanaka, Shuji

129

Design optimization and stamper fabrication of light guiding plates using silicon based micro-features  

Microsoft Academic Search

This study applies a novel fabrication process of molding stamper that combines anisotropic wet etching of silicon-on-insulator (SOI) wafers with electroforming to produce precision stampers. Micron-size features, such as trapezoidal grooves and prisms, can be accurately fabricated and distributed. Because the feature geometry and the distribution can be accurately realized using the proposed scheme, the design optimization of light guide

Jyh-Cheng Yu; Pei-Kai Hsu

2009-01-01

130

Vapor-Induced Solid-Liquid-Solid Process for Silicon-based Nanowire Growth  

SciTech Connect

Silicon based nanowires have been grown from commercial silicon powders under conditions of differing oxygen and carbon activities. Nanowires grown in the presence of carbon sources consisted of a crystalline SiC core with an amorphous SiOx shell. The thickness of SiOx shell decreased as the oxygen concentration in the precursor gases was lowered. Nanowires grown in a carbon-free environment consisted of amorphous silicon oxide with a typical composition of SiO1.8. The growth rate of nanowires decreased with decreasing oxygen content in the precursor gases. SiO1.8 nanowires exhibited an initial discharge capacity of ~ 1,300 mAh/g and better stability than those of silicon powders. A Vapor Induced Solid-Liquid-Solid (VI-SLS) mechanism is proposed to explain the nanowire growth (including silicon and other metal based nanowires) from powder sources. In this approach, both a gas source and a solid powder source are required for nanowire growth. This mechanism is consistent with experimental observations and can also be used to guide the design and growth of other nanowires.

Zhang, Jiguang; Liu, Jun; Wang, Donghai; Choi, Daiwon; Fifield, Leonard S.; Wang, Chong M.; Xia, Guanguang; Nie, Zimin; Yang, Zhenguo; Pederson, Larry R.; Graff, Gordon L.

2010-03-10

131

Integrated Micro-Machined Hydrogen Gas Sensors. (Final Report, September 1, 1999-August 31, 2004).  

National Technical Information Service (NTIS)

The widespread use of hydrogen as both an industrial process gas and an energy storage medium requires fast, selective detection of hydrogen gas. This report discusses the development of a new type of solid-state hydrogen gas sensor that couples novel met...

F. DiMeo

2005-01-01

132

Modeling mid-infrared continuous-wave silicon-based Raman lasers  

Microsoft Academic Search

We present the first modeling results for the Stokes and anti-Stokes output of a mid-infrared continuous-wave silicon-based Raman laser. These emission characteristics are generated by the use of an iterative resonator model, the loss terms of which we adapted for the case of silicon-based Raman lasers operating in the mid-infrared spectral domain. These loss terms contain besides linear losses also

Nathalie Vermeulen; Christof Debaes; Hugo Thienpont

2007-01-01

133

Use of a MicroStrip Gas Chamber conductive capillary plate for time-resolved X-ray area detection  

NASA Astrophysics Data System (ADS)

The stable operation of MicroStrip Gas Chamber (MSGC) was successfully performed using glass capillary plate as an intermediate gas multiplier. Detection area of 95mm2 was available and fine position resolution of 90?m using digital readout was attained. A charge-up problem of capillary plate under intense radiation source was perfectly removed by surface conductivity inside of capillaries. The quantitative measurements using MSGC is now available in X-ray imaging. This paper also presents novel applications of X-ray diffraction studies and their preliminary results using an MSGC. Rapid measurements for X-ray crystallography of the order of a few tens of seconds were attained successfully.

Ochi, Atsuhiko; Tanimori, Toru; Nishi, Yuji; Nishi, Yasuro; Nagayoshi, Tsutomu; Ohashi, Yuji; Uekusa, Hidehiro; Toyokawa, Hidenori

2002-01-01

134

Characterization and Modeling of Segmental Dynamics in Silicone Based Nanocomposites  

SciTech Connect

The addition of nano-particles with novel chemical, optical, or barrier properties further opens the door to the development of so-called multifunctional materials (1). Key to developing robust, tailored composites is a detailed understanding of the structural contributions to the engineering properties of the composite and how they may change with time in harsh service conditions. The segmental dynamics and local order underlie much of the fundamental physics that influence the performance of elastomers and can serve as important diagnostics for reinforcement and other fundamental properties (e.g., network topology, cross-link density, the number and distance between chemical and physical (entanglements) cross-links, the type and volume fraction of filler) and thus provide a route to this fundamental understanding. {sup 1}H MQ-NMR spectroscopy has shown the ability to provide more reliable and quantitative information regarding the elastomer network structure and heterogeneities (2). {sup 1}H MQ-NMR methods allow for the measurement of absolute residual dipolar couplings (<{Omega}{sub d}>) and thus the segmental/cooperative dynamics Thus, the MQ-NMR method allows for the direct measure of network topology and in many cases, filler-particle interactions. The ability of MD methods to uncover structural motifs and dynamics at the atomistic scale is well known. In polymer systems, however, the relationship to bulk material properties can be somewhat tenuous due to often limited number of atoms and short time durations that can be studied. Extending these MD simulations to large assemblies of atoms and extending them to longer times using state of the art computational resources has allowed us to probe some useful relationships. MD provides static and dynamic properties for a collection of particles that allow atomic scale insights that are difficult to gain otherwise. We have been exploiting these methods to characterize the effects of network structure and filler content on a number of silicone based nanocomposite systems. This data is providing improved insight into the structural contributions to the changes in segmental dynamics. Here we provide an overview of our ongoing work toward understanding the influence of the network structure on the physical and chemical properties of advanced composite elastomers, including material performance in severe environments (high temperature, high strains, high radiation fluxes).

Maxwell, R S; Baumann, T; Gee, R; Maiti, A; Patel, M; Lewicki, J

2009-03-27

135

Recent Progress in Silicon-Based MEMS Field Emission Thrusters  

NASA Astrophysics Data System (ADS)

The Indium Field Emission Thruster (In-FET) is a highly characterized and space-proven device based on space-qualified liquid metal ion sources. There is also extensive experience with liquid metal ion sources for high-brightness semiconductor fabrications and inspection Like gridded ion engines, In-FETs efficiently accelerate ions through a series of high voltage electrodes. Instead of a plasma discharge to generate ions, which generates a mixture of singly and doubly charged ions as well as neutrals, indium metal is melted (157°C) and fed to the tip of a capillary tube where very high local electric fields perform more-efficient field emission ionization, providing nearly 100% singly charged species. In-FETs do not have the associated losses or lifetime concerns of a magnetically confined discharge and hollow cathode in ion thrusters. For In-FETs, propellant efficiencies ~100% stipulate single-emitter currents <=10?A, perhaps as low as 5?A of current. This low emitter current results in <=0.5 W/emitter. Consequently, if the In-FET is to be used for future Human and Robotic missions under President Bush's Exploration plan, a mechanism to generate very high power levels is necessary. Efficient high-power operation requires many emitter/extractor pairs. Conventional fabrication techniques allow 1-10 emitters in a single module, with pain-staking precision required. Properly designed and fabricated In-FETs possess electric-to-jet efficiency >90% and a specific mass <0.25 kg/kWe. MEMS techniques allow reliable batch processing with ~160,000 emitters in a 10×10-cm array. Developing a 1.5kW 10×10-cm module is a necessary stepping-stone for >500 kWe systems where groups of 9 or 16 modules, with a single PPU/feed system, form the building blocks for even higher-power exploration systems. In 2003, SNL and ARCS produced a MEMS-based In-FET 5×5 emitter module with individually addressable emitter/extractor pairs on a 15×15mm wafer. The first MEMS thruster prototype has already been tested to demonstrate the proof-of-concept in laboratory-scale testing. In this paper we discuss progress that has been achieved in the past year on fabricating silicon-based MEMS In-FETs.

Lenard, Roger X.; Kravitz, Stanley H.; Tajmar, Martin

2005-02-01

136

Efficient Time-Step Coupling For Hybrid Continuum/Molecular Modelling of Unsteady Micro-Scale Gas Flows  

NASA Astrophysics Data System (ADS)

In this paper we describe a numerical method for the efficient time-accurate coupling of hybrid continuum/molecular micro gas flow solvers. Hybrid approaches are commonly used when non-equilibrium effects in the flow field are spatially localized; in these regions a more accurate, but typically more expensive, solution procedure is adopted. Although this can greatly increase efficiency in steady flows, in unsteady flows the evolution of the solution as a whole is restricted by the maximum time step allowed by the molecular-based/kinetic model; numerically speaking, this is a stiff problem. In the method presented in this paper we exploit time-scale separation, when it exists, to partially decouple the temporal evolution of the two parts of the hybrid model. This affords major computational savings. The method is a modified/extended version of the seamless heterogeneous multiscale method (SHMM). Our approach allows multiple micro steps (molecular steps) before coupling with the macro (continuum) solver: we call this a multi-step SHMM. This maintains the main advantages of SHMM (computational speed-up and flexible application) while improving on accuracy and greatly reducing the number of continuum computations and instances of coupling required. The improved accuracy of the multi-step SHMM is demonstrated for two canonical one-dimensional transient flows (oscillatory Poiseuille and oscillatory Couette flow) and for rarefied-gas oscillatory Poiseuille flow.

Lockerby, Duncan A.; Duque-Daza, Carlos A.; Borg, Matthew K.; Reese, Jason M.

2012-05-01

137

Rapid, micro-scale preparation and very fast gas chromatographic separation of cod liver oil fatty acid methyl esters.  

PubMed

The present research is focussed on the optimization of a fast and economically convenient method for the sample preparation and gas chromatographic separation of fatty acids contained in lipidic samples. This, as part of a wider project that has, as ultimate goal, the automation of this specific analytical procedure. The developed approach was applied to the analysis of cod liver oil, a highly complex lipid characterized by a wide nutritional interest. Derivatization was carried out by using low quantities (microL amounts) of a reagent and solvent, while the derived fatty acid methyl esters (FAMEs) were separated in 120 s on a 10 m x 0.1 mm i.d. polar micro-bore column. The total analysis time required for six samples was approximately 45 min (7.5 min/sample), considering a simultaneous process of methylation and GC separation of previously prepared samples. The results obtained were compared to those derived from conventional applications on the same sample. With regard to the validation of the rapid method, peak area/retention time repeatability, linear range, limit of detection (LOD) and quantitation (LOQ) were determined. Peak assignment was carried out by exploiting bidimensional group-type mapping information obtained in a comprehensive gas chromatographic application. PMID:16500061

Mondello, Luigi; Tranchida, Peter Quinto; Dugo, Paola; Dugo, Giovanni

2006-02-24

138

Selective oxidations in micro-structured catalytic reactors—For gas-phase reactions and specifically for fuel processing for fuel cells  

Microsoft Academic Search

This review on selective oxidations is split into two parts. The first part concerns catalytic gas-phase oxidation reactions in micro-reactors, typically being performed in wall-coated micro-channels [V. Hessel, G. Kolb, J.C. Schouten, V. Cominos, C. Hofmann, H. Löwe, G. Nikolaidis, R. Zapf, A. Ziogas, E.R. Delsman, M.H.J.M. de Croon, O. de la Iglesia, R. Mallada, J. Santamaria, in: S. Ernst,

G. Kolb; V. Hessel; V. Cominos; C. Hofmann; H. Löwe; G. Nikolaidis; R. Zapf; A. Ziogas; E. R. Delsman; J. C. Schouten; O. de la Iglesia; R. Mallada; J. Santamaria

2007-01-01

139

Nanostructure Engineered Chemical Sensors for Hazardous Gas and Vapor Detection.  

National Technical Information Service (NTIS)

A nanosensor technology has been developed using nanostructures, such as single walled carbon nanotubes (SWNTs) and metal oxides nanowires or nanobelts, on a pair of interdigitated electrodes (IDE) processed with a silicon based microfabrication and micro...

J. Li Y. Lu

2005-01-01

140

Self-assembling of micro-patterned titanium oxide films for gas sensors  

Microsoft Academic Search

Metal oxide nanoparticles are interesting building blocks for realizing films for a number of applications that include bio- and -chemical sensing. In the present work TiO2 nanoparticles have been used for a self-assembling procedure to realize lined-up micro-patterned titanium oxide films. The high surface-to-volume ratio makes these structures suitable to adsorb gases. Morphological, compositional and structural characterization have been performed

A. Serra; E. Filippo; A. Buccolieri; M. Di Giulio; D. Manno

2009-01-01

141

DETERMINATION OF CHLOROETHENES IN ENVIRONMENTAL BIOLOGICAL SAMPLES USING GAS CHROMATOGRAPHY COUPLED WITH SOLID PHASE MICRO EXTRACTION  

EPA Science Inventory

An analytical method has been developed to determine the chloroethene series, tetrachloroethene (PCE), trichloroethene (TCE),cisdichloroethene (cis-DCE) andtransdichloroethene (trans-DCE) in environmental biotreatment studies using gas chromatography coupled with a solid phase mi...

142

Optimum Operation Condition on Distributed Power Supply System with Micro Gas Turbine/Solid Oxide Fuel Cell  

NASA Astrophysics Data System (ADS)

In order to find the optimum operation condition of a distributed power supply system of 30kW class micro gas turbine (MGT) and solid oxide fuel cell (SOFC) hybrid system with the combination of line electric power and supplied gas, a system analysis has been performed. In this study, an absorption chiller and a boiler were mounted to utilize the exhausted heat from the MGT/SOFC system. The time variation of energy consumption in 24 hours for house and market models was taken into consideration for the calculation of the energy saving ratio of the present system. The operation ratio defined with the ratio of power supply of MGT/SOFC system to the power required at the peak load was changed as a parameter. From the comparison with the system using line power and gas, it is found that the present system shows high energy saving ratio around 0.4 of the operation ratio, but the energy saving ratio severely decreases in the range of high operation ratio. In this study, it is revealed that the thermal storage system effectively improves the energy saving ratio especially for the house model in winter season.

Suzuki, Hiroshi; Yamada, Miki; Usui, Hiromoto; Komoda, Yoshiyuki

143

A multi-phase, micro-dispersion reactor for the continuous production of methane gas hydrate  

SciTech Connect

A continuous-jet hydrate reactor originally developed to generate a CO2 hydrate stream has been modified to continuously produce CH4 hydrate. The reactor has been tested in the Seafloor Process Simulator (SPS), a 72-L pressure vessel available at Oak Ridge National Laboratory. During experiments, the reactor was submerged in water inside the SPS and received water from the surrounding through a submersible pump and CH4 externally through a gas booster pump. Thermodynamic conditions in the hydrate stability regime were employed in the experiments. The reactor produced a continuous stream of CH4 hydrate, and based on pressure values and amount of gas injected, the conversion of gas to hydrate was estimated. A conversion of up to 70% was achieved using this reactor.

Taboada Serrano, Patricia L [ORNL; Ulrich, Shannon M [ORNL; Szymcek, Phillip [ORNL; McCallum, Scott [Oak Ridge Associated Universities (ORAU); Phelps, Tommy Joe [ORNL; Palumbo, Anthony Vito [ORNL; Tsouris, Costas [ORNL

2009-01-01

144

Simultaneous micro steam distillation\\/solvent extraction for the isolation of semivolatile flavor compounds from cinnamon and their separation by series coupled-column gas chromatography  

Microsoft Academic Search

Simultaneous micro steam distillation\\/solvent extraction is an efficient method of extracting semivolatile flavor and fragrance compounds from cinnamon for subsequent separation by series coupled-column gas chromatography. With pentane as the extraction solvent and an extraction time of 1.5 h clean extracts requiring no further sample preparation prior to gas Chromatographic analysis are obtained. It is shown that adulteration of cinnamon

Arya Jayatilaka; Salwa K. Poole; Colin F. Poole; Tina M. P. Chichila

1995-01-01

145

The performance evaluation of a micro/nano-scaled cooler working with an ideal Bose gas  

NASA Astrophysics Data System (ADS)

Based on the size effect of a confined ideal Bose gas, the design concept of a quantum cooler is originally put forward. The cooler consists of two long tubes with the same length but different sizes of cross section, which are filled up with the ideal Bose gas, and is operated between two heat reservoirs. Expressions for the refrigeration rate and coefficient of performance (COP) of the cooler are derived. The effects of the size effect on the refrigeration rate and COP are discussed. The general performance characteristics of the cooler are revealed.

Guo, Juncheng; Su, Guozhen; Chen, Jincan

2012-01-01

146

Smart multi-channel two-dimensional micro-gas chromatography for rapid workplace hazardous volatile organic compounds measurement.  

PubMed

We developed a novel smart multi-channel two-dimensional (2-D) micro-gas chromatography (?GC) architecture that shows promise to significantly improve 2-D ?GC performance. In the smart ?GC design, a non-destructive on-column gas detector and a flow routing system are installed between the first dimensional separation column and multiple second dimensional separation columns. The effluent from the first dimensional column is monitored in real-time and decision is then made to route the effluent to one of the second dimensional columns for further separation. As compared to the conventional 2-D ?GC, the greatest benefit of the smart multi-channel 2-D ?GC architecture is the enhanced separation capability of the second dimensional column and hence the overall 2-D GC performance. All the second dimensional columns are independent of each other, and their coating, length, flow rate and temperature can be customized for best separation results. In particular, there is no more constraint on the upper limit of the second dimensional column length and separation time in our architecture. Such flexibility is critical when long second dimensional separation is needed for optimal gas analysis. In addition, the smart ?GC is advantageous in terms of elimination of the power intensive thermal modulator, higher peak amplitude enhancement, simplified 2-D chromatogram re-construction and potential scalability to higher dimensional separation. In this paper, we first constructed a complete smart 1 × 2 channel 2-D ?GC system, along with an algorithm for automated control/operation of the system. We then characterized and optimized this ?GC system, and finally employed it in two important applications that highlight its uniqueness and advantages, i.e., analysis of 31 workplace hazardous volatile organic compounds, and rapid detection and identification of target gas analytes from interference background. PMID:23303462

Liu, Jing; Seo, Jung Hwan; Li, Yubo; Chen, Di; Kurabayashi, Katsuo; Fan, Xudong

2013-01-09

147

MACRO- MICRO-PURGE SOIL GAS SAMPLING METHODS FOR THE COLLECTION OF CONTAMINANT VAPORS  

EPA Science Inventory

Purging influence on soil gas concentrations for volatile organic compounds (VOCs), as affected by sampling tube inner diameter and sampling depth (i.e., dead-space purge volume), was evaluated at different field sites. A macro-purge sampling system consisted of a standard hollo...

148

Comparative Studies of the Performance of High-Speed Gas Bearings for Micro-Turbo Machines.  

National Technical Information Service (NTIS)

Developed micromachine gas turbine generator for robotics & man- portable power sources operation at ultra-high speed (870,000rpm for 10mm compressor). Developed Hydrodynamic Herringbone/Spiral groove bearing to reach design speed and completed test on pe...

S. Togo

2006-01-01

149

Canopy Photosynthesis and Transpiration in Micro-Gravity: Gas Exchange Measurements Aboard MIR  

NASA Astrophysics Data System (ADS)

The SVET Greenhouse on-board the Orbital Station Mir was used to measure canopy photosynthesis and transpiration rates for the first time in space. During the Greenhouse IIB experiment on Mir (June - January 1997), carbon and water vapor fluxes from two wheat (cv. Superdwarf) canopies were measured using the US developed Gas Exchange Measurement System (GEMS). Gas analyzers capable of resolving CO2 concentration differences of 5 ?mol mol-1 against a background of 0.9% CO2, are necessary to measure photosynthetic and respiratory rates on Mir. The ability of the GEMS gas analyzers to measure these CO2 concentration differences was determined during extensive ground calibrations. Similarly, the sensitivity of the analyzers to water vapor was sufficient to accurately measure canopy evapotranspiration. Evapotranspiration, which accounted for over 90% of the water added to the root zone, was estimated using gas exchange and used to estimate substrate moisture content. This paper presents canopy photosynthesis and transpiration data during the peak vegetative phase of development in microgravity

Monje, O.; Bingham, G. E.; Carman, J. G.; Campbell, W. F.; Salisbury, F. B.; Eames, B. K.; Sytchev, V.; Levinskikh, M. A.; Podolsky, I.

150

Fundamental Study of Gas and Vapor Bubble Dynamics in Micro-Channels.  

National Technical Information Service (NTIS)

The aim of this project was to carry out a fundamental study of the basic: Physics underlying the applications of gas and vapor bubbles in heat transfer systems, pumps, actuators, and other small-scale systems. Since these applications require a detailed ...

A. Prosperetti W. N. Sharpe

1999-01-01

151

Stability of Micro Tubular SOFCs Operated with Synthetic Wood Gases and Wood Gas Components  

Microsoft Academic Search

In this work maximum concentrations of the impurities hydrogen chloride and hydrogen sulfide in synthetic wood gas for operation of a solid oxide fuel cell (SOFC) at different working temperatures and flow conditions are reported. Additionally, an analysis of the influence of the impurity concentrations during the heating up and cooling down phases of the SOFC is given. The paper

G. Buchinger; P. Hinterreiter; T. Raab; S. Griesser; V. Lawlor; K. Klein; S. Kuehn; W. Sitte; D. Meissner

2007-01-01

152

Quantitative measurement of gas pressure drop along T-shaped micro channels by interferometry  

Microsoft Academic Search

The study of gas flows in microchannels has received considerably more attention in the literature from a simulation perspective than an experimental. The majority of the experimental work has emphasis on the global measurements at the inlet or exit of the microchannel instead locally along it. In this paper some efforts were made to measure the pressure drop along T-shaped

Y Li; S Joseph; S Colin; L Baldas; C Barrot; S Orieux; D Newport; J J Brandner

2012-01-01

153

Determination of benzodiazepines in human urine and plasma with solvent modified solid phase micro extraction and gas chromatography; rationalisation of method development using experimental design strategies  

Microsoft Academic Search

Solid phase micro extraction (SPME) and gas chromatographic analysis was used for the analysis of several benzodiazepines (oxazepam, diazepam, nordiazepam, flunitrazepam and alprazolam) in human urine and plasma. Several factors likely to affect the analyte recovery were screened in a fractional factorial design in order to examine their effect on the extraction recovery. Parameters found significant in the screening were

Karianne Johansen Reubsaet; Hans Ragnar Norli; Peter Hemmersbach; Knut E Rasmussen

1998-01-01

154

Design and part-load performance of a hybrid system based on a solid oxide fuel cell reactor and a micro gas turbine  

Microsoft Academic Search

This paper addresses the design and off-design analysis of a hybrid system (HS) based on the coupling of a recuperated micro gas turbine (MGT) with a high temperature solid oxide fuel cell (SOFC) reactor. The SOFC reactor model is presented and discussed, taking into account the influence of the reactor lay-out, the current density, the air utilisation factor, the cell

P. Costamagna; L. Magistri; A. F. Massardo

2001-01-01

155

Study of node flow fields of micro direct methanol fuel cells  

Microsoft Academic Search

To improve the low mass transfer efficiency and poor performance of micro direct methanol fuel cells (?DMFCs), a detailed study on the micro direct methanol fuel cell flow field structure is developed in this paper. Since the flow field structure plays an important role in increasing the performance of cells. Silicon-based self-breathing ?DMFCs with the gird, parallel, single serpentine, double

Yijiang Cao; Wenchao Zhang; Siteng Huang; Xilian Wang; Yufeng Zhang; Xiaowei Liu

2011-01-01

156

Determination of priority organic micro-pollutants in water by gas chromatography coupled to triple quadrupole mass spectrometry.  

PubMed

A multiclass method has been developed for screening, quantification and confirmation of organic micro-pollutants in water by gas chromatography coupled to mass spectrometry with a triple quadrupole analyzer. The work has been focused on the determination of more than 50 compounds belonging to different chemical families: 19 organochlorine and organophosphorus insecticides, 6 herbicides, 7 polychlorinated biphenyls, 16 polycyclic aromatics hydrocarbons, 2 brominated diphenyl ethers, and 3 octyl/nonyl phenols and pentachlorobenzene. Most of these analytes are included in the list of priority substances in the framework on European Water Policy. Analyte extraction was performed by solid phase extraction using C18 cartridges, and five isotopically labeled standards were added before extraction as surrogates. Analyses were performed by gas chromatography with tandem mass spectrometry (MS/MS) in electron impact mode. Accuracy and precision were evaluated by means of recovery experiments using water samples fortified at two concentration levels (25 and 250 ng L(-1)), with satisfactory results for most of analytes. The excellent selectivity and sensitivity reached in selected reaction monitoring mode allowed us satisfactory quantification and confirmation at levels as low as 25 ng L(-1). Two MS/MS transitions were acquired for each analyte, using the Q/q intensity ratio as a confirmatory parameter. The method developed was applied to the analysis of surface, ground and wastewater samples collected from the Valencia Region (Spain). Analytical methodology using negative chemical ionization mode was also validated for the organochlorine compounds selected, showing a superior sensitivity and lower detection limits. PMID:17386553

Pitarch, E; Medina, C; Portolés, T; López, F J; Hernández, F

2006-10-19

157

Pulsed plasma-enhanced chemical vapor deposition (P-PECVD) of silicon based materials with a low-frequency dielectric barrier discharge (DBD)  

NASA Astrophysics Data System (ADS)

This work studied a P-PECVD process for the deposition of silicon based materials. In the process, the RF power is applied in specific ``on'' and ``off'' cycles. The process is operated in a DBD configuration at atmospheric pressure. In this pressure range, vapor phase growth typically dominates conventional processes, rather than the desired film growth. Our work has found by using the P-PECVD process, gas phase growth was eliminated and adhesion to the substrate was achieved. A growth process similar to atomic layer deposition (ALD) and conventional PECVD processing will be discussed.

Oldham, Christopher J.; King, Matthew R.; Guarnieri, C. Richard; Cuomo, Jerome J.

2008-10-01

158

Influence of the Adsorbent Material in the Performances of a Micro Gas Preconcentrator  

NASA Astrophysics Data System (ADS)

This paper presents the evaluation of different adsorbents for the improvement of the performances of a gas preconcentrator by targeting the adsorption of a large range of volatiles organics compounds (VOCs) The objectives of this work are to find the adequate adsorbent for a given gas target in specific experimental conditions and to select an efficient deposition process. Results related to the characterization of carbon nanopowders, carbon nanotubes (single walled (SWCNTs) and multi walled (MWCNTs)) and polymer (Tenax TA) for the development of a device for benzene preconcentration are reported. These results provide guidelines to define the right adsorbent for the preconcentration of benzene according to some specific criterions such as a large specific surface, a high adsorption capacity and low desorption temperature.

Camara, E. H. M.; Breuil, P.; Briand, D.; Guillot, L.; Pijolat, C.; Viricelle, J. P.; de Rooij, N. F.

2009-05-01

159

Micro gas-flow sensor with integrated heat sink and flow guide  

Microsoft Academic Search

A microsensor for gas-flow sensing applications with high sensitivity (700 mV at a flow velocity of 2.7 m s?1 and a supply voltage of 3 V), low power consumption (8 mW at 55 K over-temperature and an airflow velocity of 0.8 m s?1) and short response time is presented. A heat sink and flow guide integrated on the backside of

Li Qiu; Stefan Hein; Ernst Obermeier; Axel Schubert

1996-01-01

160

Tin oxide gas sensor fabricated using CMOS micro-hotplates and in-situ processing  

Microsoft Academic Search

A monolithic tin oxide (SnO2) gas sensor realized by commercial CMOS foundry fabrication (MOSIS) and postfabrication processing techniques is reported. The device is composed of a sensing film that is sputter-deposited on a silicon micromachined hotplate. The fabrication technique requires no masking and utilizes in situ process control and monitoring of film resistivity during film growth. Microhotplate temperature is controlled

John S. Suehle; Richard E. Cavicchi; Michael Gaitan; Steve Semancik

1993-01-01

161

NanoWire Grown Micro Thin Film Sensors and Their Gas Sensing Properties  

Microsoft Academic Search

SnO2 nanowires were grown on the surface of SnO2 thin film by heat treatment of metal Sn film under Ar gas flow at atmospheric pressure. Generally, the nanowires of metal oxide semiconductors are known to be grown at low pressure (below 0.02 Torr) and at high temperature (over 1,000 ?). The deposited Sn metal films were annealed at temperatures of

Sang-Rok Lee; Kap-Duk Song; Yang-Rye Lim; Byung-Su Joo; Duk-Dong Lee

162

Study of the backside signal of micro-strip gas counters on electronic conducting glass  

SciTech Connect

Microstrip gas counters (MSGC) on electronic conducting glass such as Schott S8900 have a very stable long-time behavior. However, this glass is available in relatively thick plates only. A thick substrate limits the performances of two-dimensional detectors by attenuating the signal of the backside electrode which carries the second position coordinate. A structure with open cathodes, where the central area of each cathode is non-metallized, reduces the screening effect. By increasing the cathode-backside potential difference, the backside signal increases considerably. Its amplitude becomes even equal to the anode signal when the cathodes are not connected to an external potential. As in the present mode the cathode strips do not contribute to the amplification process, this naturally leads to a structure where the cathodes are removed. Another advantage of this new structure design is the very high gas amplification which can be achieved. However, as the ions are discharged by a current through the substrate, the voltage drop caused by this current gives rise to counting rate dependence of the gas amplification.

Cicognani, G.; Feltin, D.; Guerard, B.; Oed, A. [Inst. Laue Langevin, Grenoble (France)

1998-06-01

163

Sequential Processes in Palladium-Catalyzed Silicon-Based Cross-Coupling  

PubMed Central

Although developed somewhat later, silicon-based cross-coupling has become a viable alternative to the more conventional Suzuki-Miyaura, Stille-Kosugi-Migita, and Negishi cross-coupling reactions because of its broad substrate scope, high stability of silicon-containing reagents, and low toxicity of waste streams. An empowering and yet underappreciated feature unique to silicon-based cross-coupling is the wide range of sequential processes available. In these processes, simple precursors are first converted to complex silicon-containing cross-coupling substrates, and the subsequent silicon-based cross-coupling reaction affords an even more highly functionalized product in a stereoselective fashion. In so doing, structurally simple and inexpensive starting materials are quickly transformed into value-added and densely substituted products. Therefore, sequential processes are often useful in constructing the carbon backbones of natural products. In this review, studies of sequential processes involving silicon-based cross-coupling are discussed. Additionally, the total syntheses that utilize these sequential processes are also presented.

Denmark, Scott E.; Liu, Jack H.-C.

2012-01-01

164

Porous silicon-based humidity sensor with interdigital electrodes and internal heaters  

Microsoft Academic Search

A novel design of a one wafer side processed porous silicon-based humidity sensor with interdigital electrodes is presented. An integrated heater element over the porous layer provides the effective heating and the low power consumption of the device. Reliable contacts between metal and porous Si are formed via crystalline n-Si islands within the porous layer, formed by exploiting the selectivity

P. Fürjes; A. Kovács; Cs. Dücso?; M. Ádám; B. Müller; U. Mescheder

2003-01-01

165

Liquid loading of silicon-based cantilevers using electrowetting actuation for microspotting applications  

Microsoft Academic Search

An array of silicon-based cantilevers, so-called Bioplume, that can actively be loaded with liquid solutions was designed and fabricated for microspotting applications. Each cantilever incorporates a slit and a reservoir for liquid storage, and droplet formation occurs by a direct contact deposition technique. The loading scheme, based on the use of continuous electrowetting, was implemented either by patterning metallic electrodes

Thierry Leïchlé; Daisuke Saya; Jean-Bernard Pourciel; Fabrice Mathieu; Liviu Nicu; Christian Bergaud

2006-01-01

166

Experimental and Computer Modelling Studies of Metastability of Amorphous Silicon Based Solar Cells  

Microsoft Academic Search

We present a combination of experimental and computer modelling studies of the light induced degradation in the performance of amorphous silicon based single junction solar cells. Of particular interest in this study is the degradation kinetics of different types of amorphous silicon single junction solar cells and the role of dangling bond states in mediating or driving the degradation mechanism.

Geoffrey Munyeme

2003-01-01

167

The recovery of latent fingermarks and DNA using a silicone-based casting material  

Microsoft Academic Search

There are many techniques available for the recovery of fingermarks at scenes of crime including the possibility of taking casts of the marks. Casts can be advantageous in cases where other destructive recovery techniques might not be suitable, such as when recovering finger marks deposited on valued or immobile items.In this research, Isomark™ (a silicone-based casting material) was used to

Rita Shalhoub; Ignacio Quinones; Carole Ames; Bryan Multaney; Stuart Curtis; Haj Seeboruth; Stephen Moore; Barbara Daniel

2008-01-01

168

An integrated approach for optimal design of micro gas turbine combustors  

NASA Astrophysics Data System (ADS)

The present work presents an approach for the optimized design of small gas turbine combustors, that integrates a 0-D code, CFD analyses and an advanced game theory multi-objective optimization algorithm. The output of the 0-D code is a baseline design of the combustor, given the required fuel characteristics, the basic geometry (tubular or annular) and the combustion concept (i.e. lean premixed primary zone or diffusive processes). For the optimization of the baseline design a simplified parametric CAD/mesher model is then defined and submitted to a CFD code. Free parameters of the optimization process are position and size of the liner hole arrays, their total area and the shape of the exit duct, while different objectives are the minimization of NOx emissions, pressure losses and combustor exit Pattern Factor. A 3D simulation of the optimized geometry completes the design procedure. As a first demonstrative example, the integrated design process was applied to a tubular combustion chamber with a lean premixed primary zone for a recuperative methane-fuelled small gas turbine of the 100 kW class.

Fuligno, Luca; Micheli, Diego; Poloni, Carlo

2009-06-01

169

Toward a Micro Gas Chromatograph/Mass Spectrometer (GC/MS) System  

NASA Astrophysics Data System (ADS)

Miniature mass filters (e.g., quadrupoles, ion traps) have been the subject of several miniaturization efforts. A project is currently in progress at JPL to develop a miniaturized Gas Chromatograph/Mass Spectrometer (GC/MS) system, incorporating and/or developing miniature system components including turbomolecular pumps, scroll type roughing pump, quadrupole mass filter, gas chromatograph, precision power supply and other electronic components. The preponderance of the system elements will be fabricated using microelectromechanical systems (MEMS) techniques. The quadrupole mass filter will be fabricated using an X-ray lithography technique producing high precision, 5x5 arrays of quadrupoles with pole lengths of about 3 mm and a total volume of 27 cubic mm. The miniature scroll pump will also be fabricated using X-ray lithography producing arrays of scroll stages about 3 mm in diameter. The target detection range for the mass spectrometer is 1 to 300 atomic mass units (AMU) with are solution of 0.5 AMU. This resolution will allow isotopic characterization for geochronology, atmospheric studies and other science efforts dependant on the understanding of isotope ratios of chemical species. This paper will discuss the design approach, the current state-of-the art regarding the system components and the progress toward development of key elements. The full system is anticipated to be small enough in mass, volume and power consumption to allow in situ chemical analysis on highly miniaturized science craft for geochronology, atmospheric characterization and detection of life experiments applicable to outer planet roadmap missions.

Wiberg, D. V.; Eyre, F. B.; Orient, O.; Chutjian, A.; Garkarian, V.

2001-01-01

170

Modeling Transport in Gas Chromatography Columns for the Micro-ChemLab  

SciTech Connect

The gas chromatography (GC) column is a critical component in the microsystem for chemical detection ({mu}ChemLab{trademark}) being developed at Sandia. The goal is to etch a meter-long GC column onto a 1-cm{sup 2} silicon chip while maintaining good chromatographic performance. Our design strategy is to use a modeling and simulation approach. We have developed an analytical tool that models the transport and surface interaction process to achieve an optimized design of the GC column. This analytical tool has a flow module and a separation module. The flow module considers both the compressibility and slip flow effects that may significantly influence the gas transport in a long and narrow column. The separation module models analyte transport and physico-chemical interaction with the coated surface in the GC column. It predicts the column efficiency and performance. Results of our analysis will be presented in this paper. In addition to the analytical tool, we have also developed a time-dependent adsorption/desorption model and incorporated this model into a computational fluid dynamics (CFD) code to simulate analyte transport and separation process in GC columns. CFD simulations can capture the complex three-dimensional flow and transport dynamics, whereas the analytical tool cannot. Different column geometries have been studied, and results will be presented in this paper. Overall we have demonstrated that the modeling and simulation approach can guide the design of the GC column and will reduce the number of iterations in the device development.

ADKINS,DOUGLAS R.; FRYE-MASON,GREGORY CHARLES; HUDSON,MARY L.; KOTTENSTETTE,RICHARD; MATZKE,CAROLYN M.; SALINGER,ANDREW G.; SHADID,JOHN N.; WONG, CHUNGNIN CHANN

1999-09-01

171

Hybrid preconcentrator/focuser module for determinations of explosive marker compounds with a micro-scale gas chromatograph.  

PubMed

This article describes the development and characterization of a partially selective preconcentrator/focuser (PCF) module for a field-portable micro-scale gas chromatograph (?GC) designed to rapidly determine trace levels of two vapor-phase markers of the explosive trinitrotoluene (TNT): 2,3-dimethyl-2,3-dinitrobutane (DMNB) and 2,4-dinitrotoluene (2,4-DNT). The PCF module has three primary components. The first is a high-volume sampler, comprising a resistively-heated 6-cm long stainless steel tube packed with tandem beds of the graphitized carbons Carbopack B (C-B, 30 mg) and Carbopack Y (C-Y, 15 mg), which traps the markers but permits more volatile interferences to pass through largely unretained. The second component is a microfocuser (?F), comprising a 4.2×9.8 mm Si chip containing a deep-reactive-ion-etched (DRIE) cavity packed with 2mg of C-B, a Pyrex cap, integrated heaters, and etched fluidic channels. The third component is a commercial polymer-membrane filter used as a pre-trap to remove particles and adsorbed low volatility interferences. Markers captured in the sampler are thermally desorbed and transferred to the ?F, and then thermally desorbed/injected from the ?F into a downstream separation (micro)column and detected. Scrubbed ambient air is used as carrier gas. The adsorbent capacities, baseline temperatures, sampling and desorption flow rates, and heating profiles were optimized for each PCF module component while minimizing the analysis time. An overall transfer efficiency of 86% was achieved at marker concentrations of ~0.2-2.6 ppb. In the final configuration the PCF module requires just 60s to collect a 1-L sample (3 L/min), focus (40 mL/min), and inject the markers (3 mL/min), producing half-maximum injection peak widths of ~2 and 5 s, and preconcentration factors of 4500 and 1800, for DMNB and 2,4-DNT, respectively. PMID:23357747

Serrano, Gustavo; Sukaew, Thitiporn; Zellers, Edward T

2013-01-09

172

Measurement of Thermoelectric Properties of Amorphous Silicon Based Thin Films  

NASA Astrophysics Data System (ADS)

It is important to understand thermal transport behavior in materials for technological and fundamental physics applications. Many efforts have been made in the past for explaining thermal conduction in solids. It has been observed that thermal transport properties may change with reducing size of the sample, especially as sample size approaches the nanoscale regime. The deviation in these properties, mainly in thermal conductivity, may change the choice of the material for different applications such as thermoelectricity. Thermoelectric materials are a possible source of sustainable energy and can play an important role in the fight against the present energy crisis. Recently, better thermoelectric materials have become available in bulk form as compared to thin film form, with higher figure of merit (ZT = alpha2sigma T=k). ZT is a dimensionless quantity which is used to characterize the performance of thermoelectric materials in terms of the efficiency. Figure of merit (ZT) depends on three fundamental properties including thermal conductivity (k) which is challenging to measure for thin films. This is due to several reasons such as large or more than one background contribution and radiation heating above 100 K. Precise measurements of thermopower (alpha) also become critical for thin films in order to calculate ZT and the efficiency. For devices which rely on thin film technology it is important to have an accurate knowledge of how a material behaves as a thin film in a wide range of temperature. All three of these properties are a function of charge carrier concentration as well as of temperature. In my thesis, I will present novel experimental techniques and measurements of thermoelectric properties in amorphous based thin films over a wide range of temperature. Amorphous Si alloys are expected to have high efficiency for thermoelectric purposes because of their low thermal conductivity and the fact that we can control the charge carrier concentration for optimized thermopower(alpha) and electrical conductivity(sigma) by controlling the dopant concentration. Thermal properties of pure amorphous thin films are also potentially useful in micro- or nano fabrication techniques such as electrically insulating integrated devices. ii

Sultan, Rubina

173

Silicon Carbide Micro-devices for Combustion Gas Sensing under Harsh Conditions  

SciTech Connect

A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen-containing species in chemically reactive, high temperature environments. For fast and stable sensor response measurements, a gate activation process is required. Activation of all sensors took place by switching back and forth between oxidizing (1.0% oxygen in nitrogen) and reducing (10% hydrogen in nitrogen) gases for several hours at a sensor temperature {ge}620 C. All 52 devices on the sensor chip were activated simultaneously by flooding the entire chip with gas. The effects of activation on surface morphology and structure of Pt gates before and after activation were investigated. The optical images obtained from Pt gates demonstrated a clear transition from a smooth and shiny surface to a grainy and cloudy surface morphology. XRD scans collected from Pt gates suggest the presence of an amorphous layer and species other than Pt (111) after activation. The reliability of the gate insulator of our metal-oxide-SiC sensors for long-term device operation at 630 C was studied. We find that the dielectric is stable against breakdown due to electron injection from the substrate with gate leakage current densities as low at 5nA/cm{sup 2} at 630 C. We also designed and constructed a new nano-reactor capable of high gas flow rates at elevated pressure. Our reactor, which is a miniature version of an industrial reactor, is designed to heat the flowing gas up to 700 C. Measurements in ultrahigh vacuum demonstrated that hydrogen sulfide readily deposits sulfur on the gate surface, even at the very high hydrogen/hydrogen sulfide ratios (10{sup 3}-10{sup 5}) expected in applications. Once deposited, the sulfur adversely affects sensor response, and could not be removed by exposure to hydrogen at the temperatures and pressures accessible in the ultrahigh vacuum experiments. Oxygen exposures, however, were very effective at removing sulfur, and the device performance after sulfur removal was indistinguishable from performance before exposure to H{sub 2}S.

Ruby N. Ghosh; Reza Loloee; Roger G. Tobin; Yung Ho Kahng

2006-04-01

174

A multidimensional micro gas chromatograph employing a parallel separation multi-column chip and stop-flow ?GC × ?GCs configuration.  

PubMed

A dual-chip, multidimensional micro gas chromatographic module was designed, built and evaluated. Column chips were fabricated on a silicon wafer with an etched rectangular channel 100 ?m (width) × 250 ?m (depth) using a deep reactive ion etching (DRIE) process. The column chip for the first GC dimension was 3 m long and was coated with polydimethylsiloxane (DB-1) as the stationary phase. The columns on the second dimensional chip were etched with the same width and depth as the first chip, but the flow channel was split into three parallel columns, 1 m long, on the same sized silicon chip (i.e., 3 cm × 3 cm). These three parallel columns on the second chip were coated with polyethylene oxide (DB-Wax), trifluoropropylpolymethylsilicone (OV-210) and cyanopropylmethylphenylmethylpolysilicone (OV-225), accordingly, in order to provide diversified chromatographic retention. These two chips were connected via a stop-flow configuration to simultaneously generate multiple two-dimensional gas chromatograms for every analysis. This stop-flow ?GC × ?GCs design allowed the first column to function as a pre-separator and as a sequencing injector for the second parallel-separation chip. Fifteen volatile organic compounds with boiling points that ranged from 80-131 °C with various functional groups were tested using this ?GC × ?GCs module. Three discrete 2-D chromatograms were generated simultaneously, which demonstrated the advantages of simultaneously combining GC × GC with parallel separation GCs in microchip chromatography. The total traveling length in the column was only 4 m for each eluted peak and fully resolved separation was achieved through the cross reference among triplet 2-D chromatograms. PMID:23381092

Chen, Bo-Xun; Hung, Te-Yu; Jian, Rih-Sheng; Lu, Chia-Jung

2013-04-01

175

Silicon Carbide Micro-devices for Combustion Gas Sensing under Harsh Conditions  

SciTech Connect

A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device, Pt/SiO{sub 2}/SiC that can detect hydrogen-containing species in chemically reactive, high temperature (600 C) environments. We demonstrate that the device can be used as a hydrogen monitor in syngas applications of common interferants as well as sulfur and water vapor. These measurements were made in the Catalyst Screening Unit at NETL, Morgantown under atmospheric conditions. The sensor response to hydrogen gas at 350 C is 240 mV/decade, this is significantly higher than the device response to room temperature gas or that predicted from vacuum chamber studies. The enhanced catalytic activity of the platinum sensing film under energy plant operating conditions was investigated via AFM, x-ray diffraction, TEM and x-ray photoelectron spectroscopy. Our characterization indicated that exposure to high temperature gases significantly modifies the morphology of the Pt catalytic film and the Pt/SiO{sub 2} interfacial region, which we tentatively attribute to the enhanced hydrogen sensitivity of the sensing film. A model for the hydrogen/oxygen response of the SiC device under atmospheric conditions was developed. It is based on two independent phenomena: a chemically induced shift in the metal-semiconductor work function difference and the passivation/creation of charged states at the SiO{sub 2}-SiC interface. The optimum operating set point for the SiC sensor with respect to response time and long term reliability was determined to be close to mid-gap. Ultrahigh vacuum (UHV) techniques were used to investigate the effects of sulfur contamination on the Pt gate. Exposure to hydrogen sulfide, even in the presence of hydrogen or oxygen at partial pressures of 20-600 times greater than the H2S level, rapidly coated the gate with a monolayer of sulfur. Although hydrogen exposure could not remove the adsorbed sulfur, oxygen was effective at removing sulfur with no evidence of irreversible changes in device behavior. The role of oxygen in the functioning of the SiC sensors was also investigated. All of the results are consistent with oxygen acting through its surface reactions with hydrogen, including the need for oxygen to reset the device to a fully hydrogen-depleted state and competition between hydrogen oxidation and hydrogen diffusion to metal/oxide interface sites. A strong sensor response to the unsaturated linear hydrocarbon propene (C{sub 3}H{sub 6}) was observed.

Ruby Ghosh; Reza Loloee; Roger Tobin

2008-09-30

176

SILICON CARBIDE MICRO-DEVICES FOR COMBUSTION GAS SENSING UNDER HARSH CONDITIONS  

SciTech Connect

A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen containing species in chemically reactive, high temperature environments. For these capacitive sensors we have determined that the optimum sensor operating point in terms of sensor lifetime and response time is at midgap. Detailed measurements of the oxide leakage current as a function of temperature were performed to investigate the high temperature reliability of the devices. In addition, robust metallization and electrical contacting techniques have been developed for device operation at elevated temperatures. To characterize the time response of the sensor responses in the millisecond range, a conceptually new apparatus has been built. Using laser induced fluorescence imaging techniques we have shown that the gas underneath the sensor can be completely exchanged with a time constant under 1 millisecond. Ultrahigh vacuum studies of the surface chemistry of the platinum gate have shown that sensor deactivation by adsorbed sulfur is a possible problem. Investigations on the chemical removal of sulfur by catalytic oxidation or reduction are continuing.

Ruby N. Ghosh; Peter Tobias; Roger G. Tobin

2004-10-01

177

The CMS micro-strip gas chamber project - development of a high-resolution tracking detector for harsh radiation environments  

NASA Astrophysics Data System (ADS)

Thirty-two large-area Micro-Strip Gas Chambers were tested in a high-intensity, 350 MeV pion beam at PSI to prove that we had reached a Milestone for the Compact Muon Solenoid (CMS) experiment. The particle rate was approximately 6kHz/mm2, distributed over the whole active area of the detectors, and this rate was maintained for a total integrated time of 493 h. All of the chambers were operated with signal-to-noise values at or above that corresponding to 98% hit detection efficiency at CMS; the average /S/N was 31. No indications of any gain instabilities or ageing effects were observed. In the official 3-week Milestone period, three strips from a total of 16384 were damaged, a result which is 20 times lower than the minimal requirement for CMS. The spark rate of the detectors was very low and decreased with time to an average of one spark per chamber per day. The cathode voltages of 24 of the chambers were increased over a one week period to investigate the behaviour of the detectors at higher gains; the maximum /S/N value was 2.4 times that at the normal working point. No significant increase in spark rate or strip loss rate was detected and the chambers operated stably. The detector efficiencies and imaging capabilities were also investigated. The MSGC design features and the assembly and test methodologies that enabled us to achieve these results are reported.

Bellazzini, R.; Bozzo, M.; Brez, A.; Cattai, A.; Gariano, G.; Latronico, L.; Loni, R.; Lumb, N.; Moggi, A.; Morelli, A.; Papanestis, A.; Reale, S.; Salaris, C.; Spandre, G.; Massai, M. M.; Spezziga, M. A.; Toropin, A.

2001-01-01

178

Nanoscale phosphorus atom arrays created using STM for the fabrication of a silicon based quantum computer.  

SciTech Connect

Quantum computers offer the promise of formidable computational power for certain tasks. Of the various possible physical implementations of such a device, silicon based architectures are attractive for their scalability and ease of integration with existing silicon technology. These designs use either the electron or nuclear spin state of single donor atoms to store quantum information. Here we describe a strategy to fabricate an array of single phosphorus atoms in silicon for the construction of such a silicon based quantum computer. We demonstrate the controlled placement of single phosphorus bearing molecules on a silicon surface. This has been achieved by patterning a hydrogen mono-layer 'resist' with a scanning tunneling microscope (STM) tip and exposing the patterned surface to phosphine (PH3) molecules. We also describe preliminary studies into a process to incorporate these surface phosphorus atoms into the silicon crystal at the array sites. Keywords: Quantum computing, nanotechriology scanning turincling microscopy, hydrogen lithography

O'Brien, J. L. (Jeremy L.); Schofield, S. R. (Steven R.); Simmons, M. Y. (Michelle Y.); Clark, R. G. (Robert G.); Dzurak, A. S. (Andrew S.); Curson, N. J. (Neil J.); Kane, B. E. (Bruce E.); McAlpine, N. S. (Neal S.); Hawley, M. E. (Marilyn E.); Brown, G. W. (Geoffrey W.)

2001-01-01

179

Silicon-based cross-coupling reactions in the total synthesis of natural products.  

PubMed

Unlike other variants of transition-metal-catalyzed cross-coupling reactions, those based on organosilicon donors have not been used extensively in natural product synthesis. However, recent advances such as: 1) the development of mild reaction conditions, 2) the expansion of substrate scope, 3) the development of methods to stereoselectively and efficiently introduce the silicon-containing moiety, 4) the development of a large number of sequential processes, and 5) the advent of bifunctional bis(silyl) linchpin reagents, signify the coming of age of silicon-based cross-coupling reactions. The following case studies illustrate how silicon-based cross-coupling reactions play a strategic role in constructing carbon-carbon bonds in selected target molecules. PMID:20333628

Denmark, Scott E; Liu, Jack H-C

2010-04-12

180

Effect of different surface treatments on tensile bond strength of silicone-based soft denture liner  

Microsoft Academic Search

Failure of the bond between the acrylic resin and resilient liner material is commonly encountered in clinical practice. The\\u000a purpose of this study was to investigate the effect of different surface treatments (sandblasting, Er:YAG, Nd:YAG, and KTP\\u000a lasers) on tensile bond strength of silicone-based soft denture liner. Polymethyl methacrylate test specimens were fabricated\\u000a and each received one of eight surface

Hakan Akin; Faik Tugut; Burcu Mutaf; Gulsah Akin; A. Kemal Ozdemir

181

Self-assembly of octadecyltrichlorosilane monolayers on silicon-based substrates by chemical vapor deposition  

Microsoft Academic Search

Increasingly, organosilane self-assembled monolayers (SAMs) are used to modify the surfaces of silicon-based sensors and atomic force microscope (AFM) probes. Organosilane SAMs are preferred due to their fast and easy preparation, stability, and applicability to a wide range of substrates. The traditional dip coating method from solution often yields ill-defined particulate aggregates on the two-dimensional SAM. The presence of such

Jinping Dong; Anfeng Wang; K. Y. Simon Ng; Guangzhao Mao

2006-01-01

182

Silicon based flow sensors used for mean velocity and turbulence measurements  

Microsoft Academic Search

Small and directional sensitive silicon based sensors for velocity measurements have been designed and fabricated using microelectronic technology. Single-chip as well as double-chip sensors for the determination of mean velocity and turbulent stresses have been developed. To determine the performance of these silicon sensors, comparisons with conventional hot-wire sensors were done in a well-defined two-dimensional turbulent flat plate boundary layer

L. Lofdahl; G. Stemme; B. Johansson

1992-01-01

183

Single-Crystalline Silicon-Based Heterojunction Photodiode Arrays on Flexible Plastic Substrates  

Microsoft Academic Search

A silicon-based photodiode array was fabricated on a flexible polyethylene terephthalate substrate using a trans- fer printing technique. A heterojunction structure composed of a 15-nm-thick highly doped hydrogenated amorphous-silicon (n + a-Si:H) layer and a 3-µm-thick p-type single-crystal silicon (p c-Si) membrane layer was adopted as the active layer of the flexible photodiode. The highly ordered photodiode array formed on

Sangwook Lee; Juree Hong; Ja Hoon Koo; Seulah Lee; Kwanghyun Lee; Seongil Im; Taeyoon Lee

2011-01-01

184

A silicon-based integrated NMOS-p-i-n photoreceiver  

Microsoft Academic Search

For large-volume optoelectronics applications, the low cost, manufacturability and reliability of silicon MOSFET technology are advantageous. In addition, silicon photodetectors operate quite efficiently at the 850 nm wavelength of economical AlGaAs light sources. In this paper, we report on a silicon-based monolithic optical receiver. The fabrication of the integrated lightwave receiver was carried out on a nominally undoped p-type Si

L. D. Garrett; J. Qi; C. L. Schow; J. C. Campbell

1996-01-01

185

Solder joint failure analysis using FEM techniques of a silicon based system-in-package  

Microsoft Academic Search

A silicon-based system-in-a-package (SiP) was designed that integrates all of a desktop computer's high-performance ICs, including CPU, cache memory, memory controller, and Ethernet, USB and ATAPI I\\/O interfaces. The primary benefits provided by this integration are the ability to operate the backside CPU\\/cache bus at full frontside speeds, as well as optimized power dissipation and thermal management. The term SiP

Martin Goetz; B. Zahn

2000-01-01

186

Microstructure Study of Amorphous Silicon-Based Semiconductors by Small Angle X-Ray Scattering  

Microsoft Academic Search

Small angle X-ray scattering (SAXS) has been used to study the microstructure of amorphous silicon based semiconductor thin films. Changes in the SAXS data versus systematically-varied deposition conditions such as the deposition power, substrate temperature, Ar, He and H _2 dilution for a-Si:H samples, as well as Ge and C contents for alloy samples are demonstrated. The results show that

Yan Chen

1994-01-01

187

Compact wireless neural recording system for small animals using silicon-based probe arrays  

Microsoft Academic Search

This paper reports on a compact, small-scale neural recording system combining state-of-art silicon-based probe arrays with a light-weight 32-channel wireless head stage. The system is equipped with two- and four-shaft, comb-shaped probe arrays connected to highly flexible ribbon cables enabling a reliable and controlled insertion of probe arrays through the intact dura mater into the medial prefrontal cortex and nucleus

Patrick Ruther; Tobias Holzhammer; Stanislav Herwik; P. Dylan Rich; Jeffrey W. Dalley; Oliver Paul; Tahl Holtzman

2011-01-01

188

A silicon-based, three-dimensional neural interface: manufacturing processes for an intracortical electrode array  

Microsoft Academic Search

A method is described for the manufacture of a three-dimensional electrode array geometry for chronic intracortical stimulation. This silicon based array consists of a 4.2*4.2*0.12 mm thick monocrystalline substrate, from which project 100 conductive, silicon needles sharpened to facilitate cortical penetration. Each needle is electrically isolated from the other needles, and is about 0.09 mm thick at its base and

Patrick K. Campbell; Kelly E. Jones; Robert J. Huber; Kenneth W. Horch; Richard A. Normann

1991-01-01

189

A contribution to spectroscopic diagnostics and cathode sheath modeling of micro-hollow gas discharge in argon  

SciTech Connect

In this paper, the hydrogen Balmer beta line shape from a micro-hollow gas discharge (MHGD) in argon with traces of hydrogen is used for simultaneous diagnostics of plasma and cathode sheath (CS) parameters. For this purpose, a simple model of relevant processes responsible for the line broadening is introduced and applied to the Balmer beta profile recorded from a MHGD generated in the microhole (diameter 100 {mu}m at narrow side and 130 {mu}m at wider side) of a gold-alumina-gold sandwich in the pressure range (100-900 mbar). The electron number density N{sub e} in the range (0.4-4.5) x 10{sup 20} m{sup -3} is determined from the width of the central part of the Balmer beta line profile, while, from the extended wings of the Balmer beta profile, induced by dc Stark effect, the next three parameters are determined: the average value E{sub a} of electric field strength in the CS in the range (16-95 kV/cm), the electric field strength E{sub 0} at the cathode surface in the range (32-190 kV/cm), and the CS thickness z{sub g} in the range (18-70 {mu}m). All four MHGD parameters, N{sub e}, E{sub a}, E{sub 0}, and z{sub g}, compare reasonably well with results of the modeling experiment by M. J. Kushner [J. Phys. D: Appl. Phys. 38, 1633 (2005)]. The results for N{sub e} are compared with other emission experiments.

Cvejic, M.; Spasojevic, Dj.; Sisovic, N. M.; Konjevic, N. [Faculty of Physics, University of Belgrade, P.O. Box 368, Belgrade 11001 (Serbia)

2011-08-01

190

The micro void neutron detector  

NASA Astrophysics Data System (ADS)

The Gas-filled Micro Void Particle Detector is based on gas-filled micro voids placed in an external electric field. This detector presents common features of solid state and gas filled devices as internal amplification, unlimited size and shape, dense, high efficiency parallax reducing structure. The gas filling in the void and/or the wall of the micro void serves as radiation detector. The working principle was tested on syntactic foam composed of glass micro bubbles embedded in an epoxy matrix.

Kocsis, Menyhért

2004-08-01

191

Etching process for improving the strength of a laser-machined silicon-based ceramic article  

DOEpatents

A process is disclosed for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength. 1 figure.

Copley, S.M.; Tao, H.; Todd-Copley, J.A.

1991-06-11

192

Silicon-Based Thermoelectrics: Harvesting Low Quality Heat Using Economically Printed Flexible Nanostructured Stacked Thermoelectric Junctions  

SciTech Connect

Broad Funding Opportunity Announcement Project: UIUC is experimenting with silicon-based materials to develop flexible thermoelectric devices—which convert heat into energy—that can be mass-produced at low cost. A thermoelectric device, which resembles a computer chip, creates electricity when a different temperature is applied to each of its sides. Existing commercial thermoelectric devices contain the element tellurium, which limits production levels because tellurium has become increasingly rare. UIUC is replacing this material with microscopic silicon wires that are considerably cheaper and could be equally effective. Improvements in thermoelectric device production could return enough wasted heat to add up to 23% to our current annual electricity production.

None

2010-03-01

193

Monolithic silicon-based 16-QAM modulator using two plasmonic phase shifters  

NASA Astrophysics Data System (ADS)

We propose a compact silicon-based modulator for 16-point quadrature amplitude modulation (16-QAM) with a simple structure using two phase shifters. The phase shifters employ low-loss hybrid plasmon waveguide, consisting of a conductor-gap-dielectric structure filled with polymer. Combining the strong optical confinement ability of the plasmonic waveguide with the highly nonlinear characteristic of the polymer, the proposed 16-QAM modulator can achieve a compact footprint, high-speed operation, and low power consumption, potentially allowing for high-density on-chip integration and broadband long-haul optical transmission.

Li, Fei; Xu, Mu; Hu, Xiaofeng; Wu, Jiayang; Wang, Tao; Su, Yikai

2013-01-01

194

Optical biosensing of bacteria and cells using porous silicon based, photonic lamellar gratings  

NASA Astrophysics Data System (ADS)

We report on a method to extend the optical sensing capabilities of conventional RIFTS (reflective interferometric Fourier transform spectroscopy) biosensors for real-time detection of large microorganisms, such as bacteria and cells. Using macro porous silicon based 2D arrays of phase (lamellar) grating, we demonstrate that the zero-order optical reflectivity exhibits a similar interference pattern to that obtained for ordinary RIFTS biosensors, which can be Fourier transformed into optical thickness and exploited for biosensing. The sensing capabilities are demonstrated for Escherichia coli bacteria that were captured inside the macro-pores. The entrapment process is monitored and verified by confocal laser scanning microscopy.

Mirsky, Y.; Nahor, A.; Edrei, E.; Massad-Ivanir, N.; Bonanno, L. M.; Segal, E.; Sa'ar, A.

2013-07-01

195

Research on amorphous-silicon-based, thin-film photovoltaic devices, task B  

NASA Astrophysics Data System (ADS)

This report describes the results of Phase 1 of research undertaken to study area-related problems associated with the performance of amorphous silicon based photovoltaic submodules. Objectives are to determine the optimum submodule configuration; demonstrate proof-of-concept, single-junction submodules with 10 percent conversion efficiency over an area larger than 900 sq cm; and demonstrate proof-of-concept tandem submodules with 9 percent conversion efficiency over an area larger than 900 sq cm. The research was divided into three subtask areas: semiconductor materials, nonsemiconductor materials, and submodules.

Delahoy, A. E.; Eser, E.; Kampas, F.

1989-03-01

196

Etching process for improving the strength of a laser-machined silicon-based ceramic article  

DOEpatents

A process for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength.

Copley, Stephen M. (Palos Verdes, CA); Tao, Hongyi (Covina, CA); Todd-Copley, Judith A. (Palos Verdes, CA)

1991-01-01

197

Humidity dependence of charge transport through DNA revealed by silicon-based nanotweezers manipulation.  

PubMed

The study of the electrical properties of DNA has aroused increasing interest since the last decade. So far, controversial arguments have been put forward to explain the electrical charge transport through DNA. Our experiments on DNA bundles manipulated with silicon-based actuated tweezers demonstrate undoubtedly that humidity is the main factor affecting the electrical conduction in DNA. We explain the quasi-Ohmic behavior of DNA and the exponential dependence of its conductivity with relative humidity from the adsorption of water on the DNA backbone. We propose a quantitative model that is consistent with previous studies on DNA and other materials, like porous silicon, subjected to different humidity conditions. PMID:17827222

Yamahata, Christophe; Collard, Dominique; Takekawa, Tetsuya; Kumemura, Momoko; Hashiguchi, Gen; Fujita, Hiroyuki

2007-09-07

198

Silicon-based hybrid luminescent/magnetic porous nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

Silicon-based porous nanoparticles showing at the same time intense visible luminescence and magnetic response were fabricated. The hybrid luminescent/magnetic nanoparticles (hLMNPs) were fabricated by the electrodeposition of cobalt and iron into nanostructured porous silicon. These nanoparticles were subsequently functionalized and internalized into cells. The hybrid behavior of the hLMNPs is a relevant feature for the development of research tools as nontoxic cellular tracker for progenitor cells and consequently able to be used in many strategies of cellular therapy. Additionally, the hLMNPs can be functionalized with various biomolecules that will endow them with new functionalities.

Muñoz-Noval, Álvaro; Sánchez-Vaquero, Vanessa; Torres-Costa, Vicente; Gallach, Darío; Manso-Silván, Miguel; García-Ruiz, Josefa P.; Hernando-Pérez, M.; de Pablo, P. J.; Martín-Palma, Raúl J.

2011-01-01

199

Synthesis and devolatilization of M-97 NVB silicone gum compounded into silica reinforced silicone base  

SciTech Connect

Silica reinforced silicon bases having 0.31 weight percent vinyl content were prepared by using a blend of low and high vinyl content devolatilized M-97 NVB silicone gum. The M-97 NVB is a custom dimethyl-, diphenyl-, methylvinylsiloxane gum. The silicon gum was devolatilized to evaluate the anticipated improved handling characteristics. Previous procured batches of M-97 NVB had not been devolatilized and difficult handling problems were encountered. The synthesis, devolatilization, and compound processes for the M-97 NVB silicone gum are discussed.

Schneider, J.W.

1986-06-01

200

Selective Functionalization of Silicon Micro\\/Nanowire Sensors via Localized Joule Heating  

Microsoft Academic Search

A novel approach to achieve localized surface functionalization of silicon-based micro and nanoscale linear structures (e.g., silicon nanowire sensors) is proposed in this paper. This method is based upon the protection of silicon surface by hydrophobic polymer layers such as polytetrafluoroethylene (PTFE). These layers are used as a protective, patterning barrier against surface functionalization of silicon or silicon oxide surface.

Inkyu Park; Zhiyong Li; A. P. Pisano

2007-01-01

201

Design and simulation of SOI-MEMS electrostatic vibration energy harvester for micro power generation  

Microsoft Academic Search

The micro power generation using vibration energy sources appears to be attractive due to its applicability on many situations and environmental conditions. The electrostatic energy harvester has various advantageous over piezoelectric and electromagnetic systems such as reduction in fabrication process complexity and cost, feasibility on MEMS and IC integration, improves the possibility level of integration with silicon based microelectronics and

Othman Sidek; Muhammad Afif Khalid; Mohammad Zulfikar Ishak; Muhamad Azman Miskam

2011-01-01

202

[Pplications of multi-micro-volume pressure-assisted derivatization reaction device for analysis of polar heterocyclic aromatic amines by gas chromatography-mass spectrometry].  

PubMed

A multi-micro-volume pressure-assisted derivatization reaction device has been designed and made for the silylation derivatization of polar heterocyclic aromatic amines by N-(tert-butyldimethylsilyl )-N-methyl-trifluoroacetamide (MTBSTFA) with 1% catalyst tert-butyldimethylchlorosilane (TBDMCS) at a high temperature. The tert-butyldimethylsilyl derivatives then could be automatically analyzed by gas chromatography-mass spectrometry. Using the pressure-assisted device, the silylation reaction may occur at a temperature higher than the boiling points of the reagents, and several micro-volume samples can be simultaneously pretreated in the same device to shorten the sample-preparation time and to improve the repeatability. The derivatization conditions including the headspace volume of the vial, the evaporative surface area of the reagent, derivatization temperature and time have been discussed for the use of the pressure-assisted device. The experimental results proved that the device is an effective way for the simultaneous derivatization of several micro-volume samples at a high temperature. Compared with a common device, the derivative amounts were obviously increased when using the pressure-assisted device at 90 degrees C. Quantitative derivatization can be achieved even at 150 degrees C while there was no common device could be applied at such a high temperature due to the heavy losses of reagents by evaporation. However, no obviously higher reaction speed has been observed in such a circumstance with a higher temperature and a higher pressure using the pressure-assisted device. PMID:23667982

Wang, Yiru; Chen, Fangxiang; Shi, Yamei; Tan, Connieal; Chen, Xi

2013-01-01

203

An efficient room-temperature silicon-based light-emitting diode  

NASA Astrophysics Data System (ADS)

There is an urgent requirement for an optical emitter that is compatible with standard, silicon-based ultra-large-scale integration (ULSI) technology. Bulk silicon has an indirect energy bandgap and is therefore highly inefficient as a light source, necessitating the use of other materials for the optical emitters. However, the introduction of these materials is usually incompatible with the strict processing requirements of existing ULSI technologies. Moreover, as the length scale of the devices decreases, electrons will spend increasingly more of their time in the connections between components; this interconnectivity problem could restrict further increases in computer chip processing power and speed in as little as five years. Many efforts have therefore been directed, with varying degrees of success, to engineering silicon-based materials that are efficient light emitters. Here, we describe the fabrication, using standard silicon processing techniques, of a silicon light-emitting diode (LED) that operates efficiently at room temperature. Boron is implanted into silicon both as a dopant to form a p-n junction, as well as a means of introducing dislocation loops. The dislocation loops introduce a local strain field, which modifies the band structure and provides spatial confinement of the charge carriers. It is this spatial confinement which allows room-temperature electroluminescence at the band-edge. This device strategy is highly compatible with ULSI technology, as boron ion implantation is already used as a standard method for the fabrication of silicon devices.

Ng, Wai Lek; Lourenço, M. A.; Gwilliam, R. M.; Ledain, S.; Shao, G.; Homewood, K. P.

2001-03-01

204

The spatial resolution of silicon-based electron detectors in beta-autoradiography.  

PubMed

Thin tissue autoradiography is an imaging modality where ex-vivo tissue sections are placed in direct contact with autoradiographic film. These tissue sections contain a radiolabelled ligand bound to a specific biomolecule under study. This radioligand emits beta - or beta+ particles ionizing silver halide crystals in the film. High spatial resolution autoradiograms are obtained using low energy radioisotopes, such as (3)H where an intrinsic 0.1-1 microm spatial resolution can be achieved. Several digital alternatives have been presented over the past few years to replace conventional film but their spatial resolution has yet to equal film, although silicon-based imaging technologies have demonstrated higher sensitivity compared to conventional film. It will be shown in this work how pixel size is a critical parameter for achieving high spatial resolution for low energy uncollimated beta imaging. In this work we also examine the confounding factors impeding silicon-based technologies with respect to spatial resolution. The study considers charge diffusion in silicon and detector noise, and this is applied to a range of radioisotopes typically used in autoradiography. Finally an optimal detector geometry to obtain the best possible spatial resolution for a specific technology and a specific radioisotope is suggested. PMID:20197603

Cabello, Jorge; Wells, Kevin

2010-03-02

205

Next Generation Silicon Based Detector Characterization in the LASI Lab at Arizona State University  

NASA Astrophysics Data System (ADS)

We present preliminary results of comprehensive characterization we performed on a Cassini flight spare 1024 x 1024 silicon based CCD, to ensure that our methods are accurate, and a 1024 x 1024 NIR/Red optimized delta-doped, anti-reflection coated silicon based CCD provided by the Nanoscience and Advanced Detector Arrays Group at JPL. We also present here a new facility for CCD calibration and testing at the Laboratory of Astronomical and Space Instrumentation (LASI) at Arizona State University. The current process includes calibration from the optical to near-infrared with future considerations to calibrate into the ultraviolet. We measure several important CCD characterization parameters including, but not limited to; the quantum efficiency, optimum operating temperature, read noise, dark current, gain, linearity and reproducibility. A unique feature of the calibration is the coplanar positioning of the photodiode and CCD. The CCD is stabilized at optimum operating temperature while the photodiode is held at the equilibrium ambient temperature inside an Infrared Laboratories ND-5 Series Dewar. FITS image acquisition is done using the Voodoo software provided with the LEACH controller while control of the monochrometer is done using LABVIEW. All of the image processing is done using an IDL and LABVIEW interface. This work is supported by the Jet Propulsion Laboratory under Award Number 1275804.

Veach, Todd; Scowen, P.; Nikzad, S.

2007-05-01

206

Coherent singlet-triplet oscillations in a silicon-based double quantum dot.  

PubMed

Silicon is more than the dominant material in the conventional microelectronics industry: it also has potential as a host material for emerging quantum information technologies. Standard fabrication techniques already allow the isolation of single electron spins in silicon transistor-like devices. Although this is also possible in other materials, silicon-based systems have the advantage of interacting more weakly with nuclear spins. Reducing such interactions is important for the control of spin quantum bits because nuclear fluctuations limit quantum phase coherence, as seen in recent experiments in GaAs-based quantum dots. Advances in reducing nuclear decoherence effects by means of complex control still result in coherence times much shorter than those seen in experiments on large ensembles of impurity-bound electrons in bulk silicon crystals. Here we report coherent control of electron spins in two coupled quantum dots in an undoped Si/SiGe heterostructure and show that this system has a nuclei-induced dephasing time of 360 nanoseconds, which is an increase by nearly two orders of magnitude over similar measurements in GaAs-based quantum dots. The degree of phase coherence observed, combined with fast, gated electrical initialization, read-out and control, should motivate future development of silicon-based quantum information processors. PMID:22258613

Maune, B M; Borselli, M G; Huang, B; Ladd, T D; Deelman, P W; Holabird, K S; Kiselev, A A; Alvarado-Rodriguez, I; Ross, R S; Schmitz, A E; Sokolich, M; Watson, C A; Gyure, M F; Hunter, A T

2012-01-18

207

A silicon-based electrochemical sensor for highly sensitive, specific, label-free and real-time DNA detection  

NASA Astrophysics Data System (ADS)

We herein present a new kind of silicon-based electrochemical sensor using a gold nanoparticles-decorated silicon wafer (AuNPs@Si) as a high-performance electrode, which is facilely prepared via in situ AuNPs growth on a silicon wafer. Particularly significantly, the resultant electrochemical sensor is efficacious for label-free DNA detection with high sensitivity due to the unique merits of the prepared silicon-based electrode. Typically, DNA at remarkably low concentrations (1–10 fM) could be readily detected without requiring additional signal-amplification procedures, which is better than or comparable to the lowest DNA concentration ever detected via well-studied signal-amplification-assisted electrochemical sensors. Moreover, the silicon-based sensor features high specificity, allowing unambiguous discrimination of single-based mismatches. We further show that real-time DNA assembly is readily monitored via recording the intensity changes of current signals due to the robust thermal stability of the silicon-based electrode. The unprecedented advantages of the silicon-based electrochemical sensor would offer new opportunities for myriad sensing applications.

Guo, Yuanyuan; Su, Shao; Wei, Xinpan; Zhong, Yiling; Su, Yuanyuan; Huang, Qing; Fan, Chunhai; He, Yao

2013-11-01

208

A silicon-based electrochemical sensor for highly sensitive, specific, label-free and real-time DNA detection.  

PubMed

We herein present a new kind of silicon-based electrochemical sensor using a gold nanoparticles-decorated silicon wafer (AuNPs@Si) as a high-performance electrode, which is facilely prepared via in situ AuNPs growth on a silicon wafer. Particularly significantly, the resultant electrochemical sensor is efficacious for label-free DNA detection with high sensitivity due to the unique merits of the prepared silicon-based electrode. Typically, DNA at remarkably low concentrations (1-10 fM) could be readily detected without requiring additional signal-amplification procedures, which is better than or comparable to the lowest DNA concentration ever detected via well-studied signal-amplification-assisted electrochemical sensors. Moreover, the silicon-based sensor features high specificity, allowing unambiguous discrimination of single-based mismatches. We further show that real-time DNA assembly is readily monitored via recording the intensity changes of current signals due to the robust thermal stability of the silicon-based electrode. The unprecedented advantages of the silicon-based electrochemical sensor would offer new opportunities for myriad sensing applications. PMID:24113314

Guo, Yuanyuan; Su, Shao; Wei, Xinpan; Zhong, Yiling; Su, Yuanyuan; Huang, Qing; Fan, Chunhai; He, Yao

2013-10-10

209

Heterobimetallic cuprates consisting of a redox-switchable, silicon-based metalloligand: synthesis, structures, and electronic properties.  

PubMed

A series of bimetallic silyl halido cuprates consisting of the new tripodal silicon-based metalloligand [?(3)N-Si(3,5-Me2pz)3Mo(CO)3](-) is presented (pz = pyrazolyl). This metalloligand is straightforwardly accessible by reacting the ambidentate ligand tris(3,5-dimethylpyrazolyl)silanide ({Si(3,5-Me2pz)3}(-)) with [Mo(CO)3(?(6)-toluene)]. The compound features a fac-coordinated tripodal chelating ligand and an outward pointing, "free" pyramidal silyl donor, which is easily accessible for a secondary coordination to other metal centers. Several bimetallic silyl halido cuprates of the general formula [CuX{?-?(1)Si:?(3)N-Si(3,5-Me2pz)3Mo(CO)3}](-) (X = Cl, Br, I) have been synthesized. The electronic and structural properties of these complexes were probed in detail by X-ray diffraction analysis, electrospray mass spectrometry, infrared-induced multiphoton dissociation studies, cyclic voltammetry, spectroelectrochemistry, gas-phase photoelectron spectroscopy, as well as UV/Vis and fluorescence spectroscopy. The heterobimetallic complexes contain linear two-coordinate copper(I) entities with the shortest silicon-copper distances reported so far. Oxidation of the anionic complexes in methylene chloride and acetonitrile solutions at E(1/2)(0( = -0.60 and -0.44?V (vs. ferrocene/ferrocenium (Fc/Fc(+))), respectively, shows substantial reversibility. Based on various results obtained from different characterization methods, as well as density functional theory calculations, these oxidation events were attributed to the Mo(0)/Mo(I) redox couple. PMID:23737399

Styra, Steffen; González-Gallardo, Sandra; Armbruster, Felix; Oña-Burgos, Pascual; Moos, Eric; Vonderach, Matthias; Weis, Patrick; Hampe, Oliver; Grün, Anneken; Schmitt, Yvonne; Gerhards, Markus; Menges, Fabian; Gaffga, Maximilian; Niedner-Schatteburg, Gereon; Breher, Frank

2013-06-04

210

Preparation of rich handles soft cellulosic fabric using amino silicone based softener. Part-I: Surface smoothness and softness properties.  

PubMed

A series of amino silicone based softeners with different emulsifiers were prepared and adsorbed onto the surfaces of cotton and blends of cotton/polyester fabrics. Factors affecting the performance properties of the finished substrate such as post-treatment with amino functional silicone based softener varying different emulsifiers in their formulations and its concentration on different processed fabrics were studied. Fixation of the amino-functional silicone softener onto/or within the cellulose structure is accompanied by the formation of semi-inter-penetrated network structure thereby enhancing both the extent of crosslinking and networking as well as providing very high softness. The results of the experiments indicate that the amino silicone can form a hydrophobic film on both cotton and blends of cotton/polyester fabrics and its coating reduces the surface roughness significantly. Furthermore, the roughness becomes lesser with an increase in the applied strength of amino silicone based softener. PMID:21255604

Zia, Khalid Mahmood; Tabassum, Shazia; Barkaat-ul-Hasin, Syed; Zuber, Mohammad; Jamil, Tahir; Jamal, Muhammad Asghar

2011-01-19

211

Silicon-based reproducible and active surface-enhanced Raman scattering substrates for sensitive, specific, and multiplex DNA detection  

NASA Astrophysics Data System (ADS)

Silicon-based active and reproducible surface-enhanced Raman scattering (SERS) substrate, i.e., silver nanoparticles decorated-silicon wafers (AgNPs@Si), is employed for constructing high-performance sensors. Significantly, the AgNPs@Si, facilely prepared via in situ AgNPs growth on silicon wafers, features excellent SERS reproducibility and high enhancement factor. Our experiment further demonstrates such resultant silicon-based SERS substrate is efficacious for multiplex, sensitive, and specific DNA detection. In particular, single-base mismatched DNA with low concentrations is readily discriminated by using the AgNPs@Si. Moreover, the silicon-based sensor exhibits adequate multiplexing capacity, enabling unambiguous identification of the dual-target DNA detection.

Jiang, Z. Y.; Jiang, X. X.; Su, S.; Wei, X. P.; Lee, S. T.; He, Y.

2012-05-01

212

Experimental and theoretical study of gas\\/solid mass transfer in metallic filters as supports for micro-structured catalysts  

Microsoft Academic Search

Commercial sintered metallic micro-fibers have been investigated in view of their adoption as enhanced catalyst carriers. The material herein studied has high porosity (86%) and very high interfacial area (22400m2\\/m3), thus appearing promising for application in fast, mass-transfer limited catalytic processes. It was catalytically activated by calcination and impregnation with Pt, and tested in the model reaction of CO oxidation.

G. Groppi; E. Tronconi; G. Bozzano; M. Dente

2010-01-01

213

Detection of ethanol in human body fluids by headspace solid-phase micro extraction (SPME)\\/capillary gas chromatography  

Microsoft Academic Search

Ethanol has been found extractable from human whole blood and urine samples by headspace solid-phase micro extraction (SPME) with a Carbowax\\/divinylbenzene-coated fiber. After heating a vial containing the body fluid sample with ethanol, and isobutanol as internal standard (IS) at 70°C in the presence of (NH4)2SO4, a Carbowax\\/divinylbenzene-coated SPME fiber was exposed in the headspace of the vial to allow

T. Kumazawal; H. Seno; X.-P. Lee; A. Ishii; O. Suzuki; K. Sato

1996-01-01

214

Multifunctional silicon-based light emitting device in standard complementary metal—oxide—semiconductor technology  

NASA Astrophysics Data System (ADS)

A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 ?m complementary metal—oxide—semiconductor technology. This device is capable of versatile working modes: it can emit visible to near infra-red (NIR) light (the spectrum ranges from 500 nm to 1000 nm) in reverse bias avalanche breakdown mode with working voltage between 8.35 V—12 V and emit NIR light (the spectrum ranges from 900 nm to 1300 nm) in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.

Wang, Wei; Huang, Bei-Ju; Dong, Zan; Chen, Hong-Da

2011-01-01

215

Protection of concrete structures in immersion service from biological fouling with silicone-based coatings  

SciTech Connect

The unrestricted growth of aquatic organisms (macrofouling) on surfaces of submerged concrete intake structures and circulating water systems of power plants is a significant problem in the industry, resulting in substantial operating and maintenance costs. Traditional chemical approaches to control the problem are under increasing legislative scrutiny, and regulatory actions that limit chemical discharge and require toxic use reduction may also further curtail the use of biocides. Nontoxic, silicon-based foul release coating systems appear to be an especially attractive solution to conventional treatment methods; however, criteria for coating selection and successful application are not well defined due to the relatively limited use of this technology in the industry. This article presents case histories from two utilities, reviews their testing and coating selection strategies, and discusses the application difficulties with coating-aged concrete surfaces in immersion service.

Wiebe, D.; Connor, J.; Dolderer, G.; Riha, R.; Dyas, B.

1997-05-01

216

Compact wireless neural recording system for small animals using silicon-based probe arrays.  

PubMed

This paper reports on a compact, small-scale neural recording system combining state-of-art silicon-based probe arrays with a light-weight 32-channel wireless head stage. The system is equipped with two- and four-shaft, comb-shaped probe arrays connected to highly flexible ribbon cables enabling a reliable and controlled insertion of probe arrays through the intact dura mater into the medial prefrontal cortex and nucleus accumbens of rats. The in vivo experiments applied the 5-choice serial reaction time task (5-CSRTT) using freely behaving rats in order to understand the neural basis of sustained visual attention and impulsivity. The long-term stability of the system allowed local field potential (LFP) activity to be recorded without a significant decrement in signal quality for up to 28 weeks, and similarly, we were able to follow single unit activity for up to 4 weeks. PMID:22254797

Ruther, Patrick; Holzhammer, Tobias; Herwik, Stanislav; Rich, P Dylan; Dalley, Jeffrey W; Paul, Oliver; Holtzman, Tahl

2011-01-01

217

Preparation of rich handles soft cellulosic fabric using amino silicone based softener, part II: colorfastness properties.  

PubMed

The preparation of amino silicone based softeners with different emulsifiers was carried out and adsorbed onto the surfaces of cotton and blends of cotton/polyester fabrics. The softened fabrics have high surface area, so poorly performance in washing and rubbing fastness. It is obvious from the results of colorfastness to rubbing and washing that some of the samples of the dyed fabric treated with prepared softeners have shown some poor rating as compared to the untreated fabrics. However the other two samples have shown acceptable rubbing fastness results without losing softness and permanent handle. It can be observed that washing of the printed treated fabric remains unaffected almost in all the studied samples. Moreover, the application of the prepared softeners has imparted anti pilling property to the fabric. It can be seen that there is a remarkable increase in weights of treated fabrics as compared to the untreated fabrics. PMID:21300085

Zuber, Mohammad; Zia, Khalid Mahmood; Tabassum, Shazia; Jamil, Tahir; Barkaat-Ul-Hasin, Syed; Khosa, Muhammad Kaleem

2011-02-12

218

CMOS compatible silicon-based Mach-Zehnder optical modulators with improved extinction ratio  

NASA Astrophysics Data System (ADS)

Improved Extinction Ratio of 25 dB was demonstrated in silicon based optical modulators on CMOS platform in China. The measurement results agree with the simulation, followed by a discussion about the effects of both propagation loss in Mach-Zehnder arms and power ratio at beam splitters and combiners. The analyses indicate that many considerations have to be taken into design and development of the compatible fabrication of these integrated silicon photonics, especially for the improved extinction ratio of optical modulators. In this summary, we propose the integrated optical modulators in SOI by use of the compatible CMOS processes under the modern CMOS foundry in Chinese homeland. And the measured results were shown, the fast response modulator with the data transmission rate of 10 Gbps.

Li, Zhiyong; Zhou, Liang; Hu, Yingtao; Xiao, Xi; Yu, Yude; Yu, Jinzhong

2011-11-01

219

Neutralization of space charge in magnetic field by electrons supplied from silicon based field emitter arrays  

NASA Astrophysics Data System (ADS)

Neutralization of the space charge in a magnetic field by the electrons supplied from a silicon based field emitter array (Si-FEA) was experimentally investigated. In this report, we have studied the trajectory of electrons emitted from a Si-FEA. The relationship between these electrons and diverging ion beam was experimentally studied. As a result, we have found that both the emitting position and the energy of the electrons were important to neutralize the diverging ion beam. In case the magnetic field was stronger than 15 mT, the electrons were trapped by the magnetic field and so removed from the ion beam, as the result, the ion beam was diverged. Ion beam neutralization was well done using low energy electrons less than 5 eV.

Daimaru, Tomohiro; Sakai, Shigeki; Gotoh, Yasuhito

2012-11-01

220

Effectiveness of a silicon-based root canal sealer for filling of simulated lateral canals.  

PubMed

The purpose of this in vitro study was to evaluate the ability of a silicon-based root canal sealer, compared to zinc oxide and eugenol and an epoxy resin-based sealers, for filling of simulated lateral canals. Thirty extracted single-rooted human teeth were selected, conventional access was made and the working length was established 1 mm from the apical foramen. Three simulated lateral canals, one in each root third (coronal, middle and apical) were prepared in both the mesial and distal surfaces of each tooth using a size 15 reamer adapted to a low-speed handpiece. Each root canal was instrumented using ProTaper rotary files up to file F3 at the working length, and then irrigated with 2.5% NaOCl followed by EDTA. The teeth were assigned to 3 groups (n=10), according to the root canal sealer: Roeko Seal (Group 1), Sealer 26 (group 2) and Grossman's sealer (Group 3). Gutta-percha cold lateral condensation technique was performed in all groups. Postoperative radiographs were taken and the images were projected for evaluation of the quality of lateral canal filling. Data were submitted to statistical analysis by Kruskal Wallis test at 5% significance level. The results showed that Grossman's sealer filled a larger number of lateral canals than Roeko Seal (p<0.05) and Sealer 26 (p<0.01). It may be concluded that Roeko Seal silicone-based root canal sealer was not as effective as the Grossman's sealer for filling of simulated lateral canals. The lateral canals localized in the apical third of the root were more difficult to be filled. PMID:17639195

Barbizam, João Vicente Baroni; Souza, Matheus; Cecchin, Doglas; Dabbel, Jakob

2007-01-01

221

One-dimensional/two-dimensional hybridization for self-supported binder-free silicon-based lithium ion battery anodes  

NASA Astrophysics Data System (ADS)

A unique silicon-based anode for lithium ion batteries is developed via the facile hybridization of one-dimensional silicon nanowires and two-dimensional graphene sheets. The resulting paper-like film holds advantages highly desirable for not only accommodating the volume change of silicon, but also facilitating the fast transport of electron and lithium ions.

Wang, Bin; Li, Xianglong; Luo, Bin; Jia, Yuying; Zhi, Linjie

2013-01-01

222

Properties of Indium--Zinc-Oxide Films Synthesized by Radio Frequency Magnetron Sputtering Based on Gas Phase Monitoring Using Multi-Micro Hollow Cathode Lamp  

NASA Astrophysics Data System (ADS)

Indium--zinc-oxide (IZO) films were synthesized by radio frequency magnetron sputtering. In order to clarify the mechanisms of IZO film formation, the absolute densities of In and Zn atoms were measured simultaneously by absorption spectroscopy employing the multi-micro hollow cathode lamp. Their densities were measured to be 109 to 1011 cm-3 and increased with pressure from 1 to 10 Pa. The density ratios of In to Zn in the gas phase corresponded to the ratios of film composition, and the relative amount of Zn atom increased with decreasing pressure. Carrier density increased with decreasing density ratio of In to Zn owing to the increase in the number of oxygen vacancies, which was clarified from the O 1s spectra obtained by X-ray photoelectron spectroscopy. A low resistivity of 10-6 ? m and an optical transmission of over 80% in the visible region were achieved at a pressure of 1 Pa.

Inoue, Mari; Ohta, Takayuki; Takota, Naoki; Tsuchitani, Shigeki; Takashima, Seigo; Yamakawa, Koji; Kano, Hiroyuki; Takeda, Keigo; Hori, Masaru; Ito, Masafumi

2012-11-01

223

Hierarchical modeling of heat transfer in silicon-based electronic devices  

Microsoft Academic Search

Heat transfer modeling in electronic devices has gained importance over the last decade in the design of better performing devices. The trend towards miniaturization of these devices has led to components that operate in the micro and nano-meter and in the micro and pico-second ranges. When the characteristic dimensions of the electronic components are comparable to or smaller than the

Javier V. Goicochea Pineda; Marcela Madrid; Cristina Amon

2008-01-01

224

Mobile monitoring along a street canyon and stationary forest air monitoring of formaldehyde by means of a micro-gas analysis system.  

PubMed

A micro-gas analysis system (?GAS) was developed for mobile monitoring and continuous measurements of atmospheric HCHO. HCHO gas was trapped into an absorbing/reaction solution continuously using a microchannel scrubber in which the microchannels were patterned in a honeycomb structure to form a wide absorbing area with a thin absorbing solution layer. Fluorescence was monitored after reaction of the collected HCHO with 2,4-pentanedione (PD) in the presence of acetic acid/ammonium acetate. The system was portable, battery-driven, highly sensitive (limit of detection = 0.01 ppbv) and had good time resolution (response time 50 s). The results revealed that the PD chemistry was subject to interference from O(3). The mechanism of this interference was investigated and the problem was addressed by incorporating a wet denuder. Mobile monitoring was performed along traffic roads, and elevated HCHO levels in a street canyon were evident upon mapping of the obtained data. The system was also applied to stationary monitoring in a forest in which HCHO formed naturally via reaction of biogenic compounds with oxidants. Concentrations of a few ppbv-HCHO and several-tens of ppbv of O(3) were then simultaneously monitored with the ?GAS in forest air monitoring campaigns. The obtained 1 h average data were compared with those obtained by 1 h impinger collection and offsite GC-MS analysis after derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBOA). From the obtained data in the forest, daily variations of chemical HCHO production and loss are discussed. PMID:22508343

Toda, Kei; Tokunaga, Wataru; Gushiken, Yosuke; Hirota, Kazutoshi; Nose, Teppei; Suda, Daisaku; Nagai, Jun; Ohira, Shin-Ichi

2012-04-17

225

Effects of nonlocal plasmons in gapped graphene micro-ribbon array and two-dimensional electron gas on near-field electromagnetic response in the deep subwavelength regime.  

PubMed

A self-consistent theory involving Maxwell's equations and a density-matrix linear-response theory is solved for an electromagnetically coupled doped graphene micro-ribbon array (GMRA) and a quantum well (QW) electron gas sitting at an interface between a half-space of air and another half-space of a doped semiconductor substrate, which supports a surface-plasmon mode in our system. The coupling between a spatially modulated total electromagnetic (EM) field and the electron dynamics in a Dirac-cone of a graphene ribbon, as well as the coupling of the far-field specular and near-field higher-order diffraction modes, are included in the derived electron optical-response function. Full analytical expressions are obtained with nonlocality for the optical-response functions of a two-dimensional electron gas and a graphene layer with an induced bandgap, and are employed in our numerical calculations beyond the long-wavelength limit (Drude model). Both the near-field transmissivity and reflectivity spectra, as well as their dependence on different configurations of our system and on the array period, ribbon width, graphene chemical potential of QW electron gas and bandgap in graphene, are studied. Moreover, the transmitted E-field intensity distribution is calculated to demonstrate its connection to the mixing of specular and diffraction modes of the total EM field. An externally tunable EM coupling among the surface, conventional electron-gas and massless graphene intraband plasmon excitations is discovered and explained. Furthermore, a comparison is made between the dependence of the graphene-plasmon energy on the ribbon's width and chemical potential in this paper and the recent experimental observation given by [Nat. Nanotechnol.6, 630-634 (2011)] for a GMRA in the terahertz-frequency range. PMID:23385917

Huang, Danhong; Gumbs, Godfrey; Roslyak, Oleksiy

2013-02-01

226

Single-crystal-silicon-based microinstrument to study friction and wear at MEMS sidewall interfaces  

NASA Astrophysics Data System (ADS)

Since the advent of microelectromechanical systems (MEMS) technology, friction and wear are considered as key factors that determine the lifetime and reliability of MEMS devices that contain contacting interfaces. However, to date, our knowledge of the mechanisms that govern friction and wear in MEMS is insufficient. Therefore, systematically investigating friction and wear at MEMS scale is critical for the commercial success of many potential MEMS devices. Specifically, since many emerging MEMS devices contain more sidewall interfaces, which are topographically and chemically different from in-plane interfaces, studying the friction and wear characteristics of MEMS sidewall surfaces is important. The microinstruments that have been used to date to investigate the friction and wear characteristics of MEMS sidewall surfaces possess several limitations induced either by their design or the structural film used to fabricate them. Therefore, in this paper, we report on a single-crystal-silicon-based microinstrument to study the frictional and wear behavior of MEMS sidewalls, which not only addresses some of the limitations of other microinstruments but is also easy to fabricate. The design, modeling and fabrication of the microinstrument are described in this paper. Additionally, the coefficients of static and dynamic friction of octadecyltrichlorosilane-coated sidewall surfaces as well as sidewall surfaces with only native oxide on them are also reported in this paper.

Ansari, N.; Ashurst, W. R.

2012-02-01

227

Experimental and Computer Modelling Studies of Metastability of Amorphous Silicon Based Solar Cells  

NASA Astrophysics Data System (ADS)

We present a combination of experimental and computer modelling studies of the light induced degradation in the performance of amorphous silicon based single junction solar cells. Of particular interest in this study is the degradation kinetics of different types of amorphous silicon single junction solar cells and the role of dangling bond states in mediating or driving the degradation mechanism. The approach taken in this study has enabled has to examine how light induced degradation is affected by both the structural and material improvement. The study encompasses the application of the microscopic models describing the creation and distribution of midgap defect states to numerical simulation of the as-deposited and degraded states of a solar cell. We have developed computer modeling schemes for simulating the degraded state of amorphous silicon solar cells taking into account the nature and distributions of dangling bond states during illumination. The results of our simulations are in good agreement with the experimentally observed increase in the dangling bond density of states during illumination. Although there is still an uncertainty in the microscopic processes occurring in amorphous silicon during illumination, with the methods developed in this study, it is possible to have reasonable assessment of the physical quantities that play an important role in the light induced degradation of amorphous silicon solar cells.

Munyeme, Geoffrey

2003-03-01

228

Numerical analysis of silicon-based horizontal multiple-slotted waveguides with slanted sidewalls  

NASA Astrophysics Data System (ADS)

A silicon-based horizontal multiple-slotted waveguide with slanted sidewalls is analyzed by using a full-vectorial mode solver based on the finite element method. The results show that the mode classification of the present waveguide structures is different from that of the conventional ones (e.g., typical rib waveguides, optical fibers), both symmetric and anti-symmetric fundamental (and higher-order) quasi-TE and quasi-TM modes exist due to the strong coupling of high-index silicon layers. The field distributions, effective indexes, and optical field confinement factors, both in quasi-TE and quasi-TM modes, as functions of the top width and sidewalls angle of the waveguides, and the refractive index and thickness of the slots are investigated in detail, where the single-mode regime, non-birefringence condition, and maximum optical confinement factor are obtained. From the numerical results, a single-mode waveguide structure for fundamental symmetric quasi-TM modes with the power confinement factor of 80% and the normalized power density of 120 ?m-2 is achieved.

Xiao, Jinbiao; Xia, Saisai; Li, Wenliang; Sun, Xiaohan

2013-03-01

229

High-frequency, silicon-based ultrasonic nozzles using multiple Fourier horns.  

PubMed

This paper presents the design, simulation, and characterization of microfabricated 0.5 MHz, silicon-based, ultrasonic nozzles. Each nozzle is made of a piezoelectric drive section and a silicon resonator consisting of multiple Fourier horns, each with half wavelength design and twice amplitude magnification. Results of finite element three-dimensional (3-D) simulation using a commercial program predicted existence of one resonant frequency of pure longitudinal vibration. Both impedance analysis and measurement of longitudinal vibration confirmed the simulation results with one pure longitudinal vibration mode at the resonant frequency in excellent agreement with the design value. Furthermore, at the resonant frequency, the measured longitudinal vibration amplitude at the nozzle tip increases as the number of Fourier horns (n) increases in good agreement with the theoretical values of 2(n). Using this design, very high vibration amplitude gain at the nozzle tip can be achieved with no reduction in the tip cross-sectional area for contact of liquid to be atomized. Therefore, the required electric drive power should be drastically reduced, decreasing the likelihood of transducer failure in ultrasonic atomization. PMID:15128214

Tsai, Shirley C; Song, Yu L; Tseng, Terry K; Chou, Yuan F; Chen, Wei J; Tsai, Chen S

2004-03-01

230

A silicon-based, three-dimensional neural interface: manufacturing processes for an intracortical electrode array.  

PubMed

A method has been developed for the manufacture of a "three-dimensional" electrode array geometry for chronic intracortical stimulation. This silicon based array consists of a 4.2 x 4.2 x 0.12 mm thick monocrystalline substrate, from which project 100 conductive, silicon needles sharpened to facilitate cortical penetration. Each needle is electrically isolated from the other needles, and is about 0.09 mm thick at its base and 1.5 mm long. The sharpened end of each needle is coated with platinum to facilitate charge transfer into neural tissue. The following manufacturing processes were used to create this array. 1) Thermomigration of 100 aluminum pads through an n-type silicon block. This creates trails of highly conductive p+ silicon isolated from each other by opposing pn junctions. 2) A combination of mechanical and chemical micromachining which creates individual penetrating needles of the p+ silicon trails. 3) Metal deposition to create active electrode areas and electrical contact pads. 4) Array encapsulation with polyimide. The geometrical, mechanical, and electrical properties of these arrays should make them well suited as interfaces to cortical tissue. PMID:1937509

Campbell, P K; Jones, K E; Huber, R J; Horch, K W; Normann, R A

1991-08-01

231

Capillary micro-switches  

Microsoft Academic Search

A capillary surface is a liquid\\/liquid or liquid\\/gas interface whose shape is determined by surface tension. Capillary surfaces occur when the capillary length is large compared to the container scale, as happens for typical liquids against gas on the sub-millimeter scale on Earth and on the meter scale in the micro-gravity environment of space vehicles. Manipulating capillary surfaces has emerged

Paul Steen; Claude Matalanis; Amir Hirsa; Christhopher Cox

2002-01-01

232

In vivo silicon-based flexible radio frequency integrated circuits monolithically encapsulated with biocompatible liquid crystal polymers.  

PubMed

Biointegrated electronics have been investigated for various healthcare applications which can introduce biomedical systems into the human body. Silicon-based semiconductors perform significant roles of nerve stimulation, signal analysis, and wireless communication in implantable electronics. However, the current large-scale integration (LSI) chips have limitations in in vivo devices due to their rigid and bulky properties. This paper describes in vivo ultrathin silicon-based liquid crystal polymer (LCP) monolithically encapsulated flexible radio frequency integrated circuits (RFICs) for medical wireless communication. The mechanical stability of the LCP encapsulation is supported by finite element analysis simulation. In vivo electrical reliability and bioaffinity of the LCP monoencapsulated RFIC devices are confirmed in rats. In vitro accelerated soak tests are performed with Arrhenius method to estimate the lifetime of LCP monoencapsulated RFICs in a live body. The work could provide an approach to flexible LSI in biointegrated electronics such as an artificial retina and wireless body sensor networks. PMID:23617401

Hwang, Geon-Tae; Im, Donggu; Lee, Sung Eun; Lee, Jooseok; Koo, Min; Park, So Young; Kim, Seungjun; Yang, Kyounghoon; Kim, Sung June; Lee, Kwyro; Lee, Keon Jae

2013-04-30

233

Implementation of quantum logic operations and creation of entanglement in a silicon-based quantum computer with constant interaction  

Microsoft Academic Search

We describe how to implement quantum logic operations in a silicon-based\\u000aquantum computer with phosphorus atoms serving as qubits. The information is\\u000astored in the states of nuclear spins and the conditional logic operations are\\u000aimplemented through the electron spins using nuclear-electron hyperfine and\\u000aelectron-electron exchange interactions. The electrons in our computer should\\u000astay coherent only during implementation of one

G. P. Berman; G. W. Brown; M. E. Hawley; D. I. Kamenev; V. I. Tsifrinovich

2005-01-01

234

Implementation of quantum logic operations and creation of entanglement in a silicon-based quantum computer with constant interaction  

Microsoft Academic Search

We describe how to implement quantum logic operations in a silicon-based quantum computer with phosphorus atoms serving as qubits. The information is stored in the states of nuclear spins and the conditional logic operations are implemented through the electron spins using nuclear-electron hyperfine and electron-electron exchange interactions. The electrons in our computer should stay coherent only during implementation of one

G. P. Berman; G. W. Brown; M. E. Hawley; D. I. Kamenev; V. I. Tsifrinovich

2005-01-01

235

Microcrystalline single and double junction silicon based solar cells entirely prepared by HWCVD on textured zinc oxide substrate  

Microsoft Academic Search

Microcrystalline silicon based single junction pin and amorphous-microcrystalline double junction pinpin solar cells were fabricated entirely by hot-wire chemical vapor deposition on textured zinc oxide substrates. The short circuit current density for microcrystalline pin cells shows an increase of 20–25% compared to unetched zinc oxide, indicating a better light trapping on textured zinc oxide substrate. The best initial conversion efficiency

P. Kumar; M. Kupich; W. Bock; R. O. Dusane; B. Schroeder

2006-01-01

236

Electrochemical performance of lithium ion battery, nano-silicon-based, disordered carbon composite anodes with different microstructures  

Microsoft Academic Search

Nano-silicon-based disordered carbon composites prepared by mechanical milling and pyrolysis have been examined as anodes of a lithium ion cell. Electrochemical measurements show that the charge–discharge capacity of disordered carbon composites incorporating both silicon-polyparaphenylene (Si-PPP) and silicon-polyvinyl chloride (Si-PVC) with differing silicon contents, decreases with increasing pyrolysis temperature. Si-PVC-based materials have a better cycle life than those based on Si-PPP

Xiang-Wu Zhang; Prashanth K. Patil; Chunsheng Wang; A. John Appleby; Frank. E Little; David L Cocke

2004-01-01

237

In-vivo implant mechanics of flexible, silicon-based ACREO microelectrode arrays in rat cerebral cortex  

Microsoft Academic Search

The mechanical behavior of an electrode during implantation into neural tissue can have a profound effect on the neural connections and signaling that takes place within the tissue. The objective of the present work was to investigate the in vivo implant mechanics of flexible, silicon-based ACREO microelectrode arrays recently developed by the VSAMUEL consortium (European Union, grant #IST-1999-10073). We have

Winnie Jensen; Ken Yoshida; Ulrich G. Hofmann

2006-01-01

238

Microcrystalline silicon tunnel junctions for amorphous silicon-based multijunction solar cells  

SciTech Connect

The formation of tunnel junctions for applications in amorphous silicon (a-Si:H) based multijunction n-i-p solar cells has been studied using real time optics. The junction structure investigated in detail here consists of a thin ({approximately} 200 {angstrom}) layer of n-type microcrystalline silicon ({micro}c-Si:H) on top of an equally thin layer of p-type {micro}c-Si:H, the latter deposited on thick ({approximately} 2,000 {angstrom}) intrinsic a-Si:H. Such a structure has been optimized in an attempt to obtain single-phase {micro}c-Si:H with a high crystallite packing density and large grain size for both layers of the tunnel junction. They have explored the conditions under which grain growth is continuous across the p/n junction and conditions under which renucleation of n-layer grains can be ensured at the junction. one important finding of this study is that the optimum conditions for single-phase, high-density {micro}c-Si:H n-layers are different depending on whether the substrate is a {micro}c-Si:H p-layer or is a H{sub 2}-plasma treated or untreated a-Si:H i-layer. Thus, the top-most {micro}c-Si:H layer of the tunnel junction must be optimized in the multijunction device configuration, rather than in single cell configurations on a-Si:H i-layers. The observations are explained using an evolutionary phase diagram for a-Si:H and {micro}c-Si:H film growth versus thickness and H{sub 2}-dilution ratio, in which the boundary between the two phases is strongly substrate-dependent.

Ferlauto, A.S.; Koh, J.; Rovira, P.I.; Wronski, C.R.; Collins, R.W.

1999-07-01

239

Characterization of Pt-doped SnO2 catalyst for a high-performance micro gas sensor.  

PubMed

The atomic scale structure and its dependence on Pt concentration of a Pt-doped SnO2 (Pt-SnO2) thin film produced by a sputter-deposition method was investigated, which showed high-performance as a methane gas sensor. Extended X-ray absorption fine structure (EXAFS) and X-ray diffraction (XRD) analyses showed that Pt-SnO2 has a rutile structure similar to SnO2 crystals at less than 10 at% Pt where the Pt ion was located at the Sn position in the rutile structure. There was no evidence that Pt metal clusters were formed in the Pt-SnO2 films. The Pt-SnO2 structure became amorphous at greater than 11 at% Pt. We found a good correlation between the methane activity and local structure of Pt. PMID:24045584

Murata, Naoyoshi; Suzuki, Takuya; Kobayashi, Makoto; Togoh, Fumiaki; Asakura, Kiyotaka

2013-10-01

240

Moment tensor inversion for two micro-earthquakes occurring inside the Háje gas storage facilities, Czech Republic  

NASA Astrophysics Data System (ADS)

Broadband data from the P?íbram seismological network was used to investigate the source of two earthquakes, with magnitudes M w = 0.2 and 0.4 respectively, occurring in the period of October-November 2009 in the Háje natural gas storage area (Czech Republic). Both events were located inside the limits of the storage area and at depths similar to those of the underground caverns where the gas is stored. We applied an inversion technique using the software ISOLA for moment tensor retrieval in order to assess the source process of both events and recognize whether a significant isotropic component existed that could be interpreted as a possible cavern collapse. We also performed an uncertainty analysis so as to confirm the reliability of the focal mechanism solutions and we controlled the consistency between the inverted focal mechanisms and those calculated using the P-waves first motions. Our results showed that the nodal plane orientation, the centroid depth, and the magnitude remained stable. Furthermore, we calculated synthetic waveforms for collapse-type ruptures and compared them with the original records. The match between the synthetic and the original data was very poor supporting the interpretation of the shear character of the events. The combination of the inversion results, which indicated significant double-couple components and of the synthetic tests, which supported the inexistence of an isotropic component at the source, led to the conclusion that the possibility of rocks falling from the ceiling of the caverns or a cavern collapse is highly unlikely.

Benetatos, Christoforos; Málek, Ji?í; Verga, Francesca

2013-04-01

241

Preparation and properties of novel silicone-based flexible optical waveguide  

NASA Astrophysics Data System (ADS)

UV curable novel silicone polymers, Nano-Hybrid Silicone (NHS), having high thermal stability, low-shrinkage and high transparency were developed. The optical waveguide could be fabricated by direct UV exposed patterning method, since photolithograph using NHS could be available. Two kinds of NHS for optical waveguide were developed, one is for optical waveguide on Si substrate and the other is for film optical waveguide. The optical losses of these waveguides measured by cut-back method at 850 nm were significantly low, and indicated 0.05 dB/cm (Si substrate waveguide) and less than 0.1 dB/cm (film waveguide) respectively. Heat durable tests of these waveguides were carried out for surface packaging technologies under lead free solder melting temperature, and no significant changes of optical loss were observed. Especially with the waveguide on Si substrate, the optical loss increase was less than 0.02 dB/cm without changing of shape after the heat resistance test at 270 degrees Celsius for 10 minutes. UV durable tests of these waveguide were also carried out for the adhesion using UV curable resin on electric board. No change was observed with optical waveguide capability after UV exposure (10 J/cm2 at 365 nm). Furthermore, value movement of optical loss was small at preliminary tests of heat-cycling and reliability under the high temperature and humidity condition according to Telcordia specification. Due to their various processes durability, the waveguides made with novel silicone-based material are expected to be suitable for practical uses.

Hara, Kenji; Ishikawa, Yoshihiro; Shoji, Yoshikazu

2006-11-01

242

Interaction of silicon-based quantum dots with gibel carp liver: oxidative and structural modifications  

NASA Astrophysics Data System (ADS)

Quantum dots (QDs) interaction with living organisms is of central interest due to their various biological and medical applications. One of the most important mechanisms proposed for various silicon nanoparticle-mediated toxicity is oxidative stress. We investigated the basic processes of cellular damage by oxidative stress and tissue injury following QD accumulation in the gibel carp liver after intraperitoneal injection of a single dose of 2 mg/kg body weight Si/SiO2 QDs after 1, 3, and 7 days from their administration. QDs gradual accumulation was highlighted by fluorescence microscopy, and subsequent histological changes in the hepatic tissue were noted. After 1 and 3 days, QD-treated fish showed an increased number of macrophage clusters and fibrosis, while hepatocyte basophilia and isolated hepatolytic microlesions were observed only after substantial QDs accumulation in the liver parenchyma, at 7 days after IP injection. Induction of oxidative stress in fish liver was revealed by the formation of malondialdehyde and advanced oxidation protein products, as well as a decrease in protein thiol groups and reduced glutathione levels. The liver enzymatic antioxidant defense was modulated to maintain the redox status in response to the changes initiated by Si/SiO2 QDs. So, catalase and glutathione peroxidase activities were upregulated starting from the first day after injection, while the activity of superoxide dismutase increased only after 7 days. The oxidative damage that still occurred may impair the activity of more sensitive enzymes. A significant inhibition in glucose-6-phosphate dehydrogenase and glutathione-S-transferase activity was noted, while glutathione reductase remained unaltered. Taking into account that the reduced glutathione level had a deep decline and the level of lipid peroxidation products remained highly increased in the time interval we studied, it appears that the liver antioxidant defense of Carassius gibelio does not counteract the oxidative stress induced 7 days after silicon-based QDs exposure in an efficient manner.

Stanca, Loredana; Petrache, Sorina Nicoleta; Serban, Andreea Iren; Staicu, Andrea Cristina; Sima, Cornelia; Munteanu, Maria Cristina; Z?rnescu, Otilia; Dinu, Diana; Dinischiotu, Anca

2013-05-01

243

Silicon based multilayer photoelectrodes for photoelectrolysis of water to produce hydrogen from the sun  

NASA Astrophysics Data System (ADS)

The main objective of this work is to study different materials for the direct photosynthesis of hydrogen from water. A variety of photocatalysts such as titanium dioxide, titanium oxy-nitride, silicon carbide, and gallium nitride are being investigated by others for the clean production of hydrogen for fuel cells and hydrogen economy. Our approach was to deposit suitable metallic regions on photocatalyst nanoparticles to direct the efficient synthesis of hydrogen to a particular site for convenient collection. We studied different electrode metals such as gold, platinum, titanium, palladium, and tungsten. We also studied different solar cell materials such as silicon (p- and n-types), silicon carbide and titanium dioxide semiconductors in order to efficiently generate electrons under illumination. We introduced a novel silicon-based multilayer photosynthesis device to take advantage of suitable properties of silicon and tungsten to efficiently produce hydrogen. The device consisted of a silicon (0.5mm) substrate, a deposited atomic layer of Al2O 3 (1nm), a doped polysilicon (0.1microm), and finally a tungsten nanoporous (5-10nm) layer acting as an interface electrode with water. The Al2O 3 layer was introduced to reduce leakage current and to prevent the spreading of the diffused p-n junction layer between the silicon and doped polysilicon layers. The surface of the photoelectrode was coated with nanotextured tungsten nanopores (TNP), which increased the surface area of the electrodes to the electrolyte, assisting in electron-hole mobility, and acting as a photocatalyst. The reported device exhibited a fill factor (%FF) of 27.22% and solar-to-hydrogen conversion efficiency of 0.03174%. This thesis describes the structures of the device, and offers a characterization and comparison between different photoelectrodes.

Faruque, Faisal

244

Evaluation of solid-phase micro-extraction coupled to gas chromatography-mass spectrometry for the headspace analysis of volatile compounds in cocoa products.  

PubMed

The aroma profile of cocoa products was investigated by headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). SPME fibers coated with 100 microm polydimethylsiloxane coating (PDMS), 65 microm polydimethylsiloxane/divinylbenzene coating (PDMS-DVB), 75 microm carboxen/polydimethylsiloxane coating (CAR-PDMS) and 50/30 microm divinylbenzene/carboxen on polydimethylsiloxane on a StableFlex fiber (DVB/CAR-PDMS) were evaluated. Several extraction times and temperature conditions were also tested to achieve optimum recovery. Suspensions of the samples in distilled water or in brine (25% NaCl in distilled water) were investigated to examine their effect on the composition of the headspace. The SPME fiber coated with 50/30 microm DVB/CAR-PDMS afforded the highest extraction efficiency, particularly when the samples were extracted at 60 degrees C for 15 min under dry conditions with toluene as an internal standard. Forty-five compounds were extracted and tentatively identified, most of which have previously been reported as odor-active compounds. The method developed allows sensitive and representative analysis of cocoa products with high reproducibility. Further research is ongoing to study chocolate making processes using this method for the quantitative analysis of volatile compounds contributing to the flavor/odor profile. PMID:18371766

Ducki, Sylvie; Miralles-Garcia, Javier; Zumbé, Albert; Tornero, Antonio; Storey, David M

2007-09-02

245

Performance Analysis and Optimum Operation Planning of Distributed Energy System Based on Micro Gas Turbine-Solid Oxide Fuel Cell Hybrid Power Generation  

NASA Astrophysics Data System (ADS)

In this paper, the economical and energy saving advantages of the distributed energy system, which consists of a micro gas turbine-solid oxide fuel cell hybrid power generation system, waste heat recovery devices and air-conditioning equipments, are investigated. Firstly, the thermodynamical performance evaluation of the hybrid system with the heat recovery devices is discussed to estimate the energy conversion efficiency of the whole system. Secondly, by using 1inear programming technique, the optimum operation planning of the cogeneration plant based on the hybrid system is discussed to predict the reduction of the primary fuel consumption and utility cost. Throughout detailed investigation, it is found that the energy conversion efficiency, which includes the waste heat utilization, reaches over 80% (LHV). In addition, the optimum operation of the hybrid system, of which power generation capacity is appropriate for the energy demand, achieve the highly effective energy saving against the traditional energy supply scheme, that is, the fuel reduction reaches around 40% to the conventional value.

Morita, Aina; Kimijima, Shinji

246

Forensic analysis of a single particle of partially burnt gunpowder by solid phase micro-extraction-gas chromatography-nitrogen phosphorus detector.  

PubMed

Solid phase micro-extraction (SPME) was adopted to extract organic gun shot residues (OGSRs) from a single particle of partially burnt gunpowder. The partially burnt particle samples were collected from gun shot residue (GSR) deposited near the target areas. OGSRs, such as diphenylamine (DPA), methyl centralite (MC), ethyl centralite (EC), from only one single particle of partially burnt gunpowder were successfully extracted by SPME and analyzed by a gas chromatography coupled to a nitrogen phosphorus detector (GC-NPD). The results confirmed that the new extraction procedure is capable of extracting trace amount of MC and EC as signature molecules for the identification of GSR. The method represents a solvent-free extraction as a complementary analytical procedure for the forensic analysis of GSR-related evidences. The new extraction scheme with the capability of analyzing single particle of partially burnt gunpowder can also be applied to the identification of explosive residues, such as in post-blast investigations of improvised explosive devices. PMID:19375082

Burleson, Garrett Lee; Gonzalez, Brittney; Simons, Kelsie; Yu, Jorn C C

2009-04-01

247

Headspace, solid-phase micro-extraction, gas chromatographic-mass spectrometric analysis of terpenoids in the latex of Euphorbia species.  

PubMed

The volatile and semi-volatile terpenoids in the latex of Euphorbia amygdaloides, E. exigua, E. helioscopia, and E. peplus were analyzed by headspace, solid-phase micro-extraction (HS-SPME), coupled with gas chromatography-mass spectrometry. The volatiles were extracted using a 100 microm polydimethylsiloxane SPME fiber under optimized extraction conditions. The compounds detected encompassed a range of chemical classes, but only terpenoids were evaluated. Only sesquiterpene hydrocarbons were detected in the tested samples of E. exigua, E. helioscopia, and E. peplus, with beta-caryophyllene being the major one, but were never recorded in latex samples of E. amygdaloides, in which only the diterpene hydrocarbon kaur-16-ene was detected. Alpha-Humulene was consistently found in samples of E. helioscopia, and E. peplus, but never in those of the other two species. These preliminary results show that the developed procedure is suitable for the analysis of small samples of Euphorbia latex and that, for each individual species, there is very little qualitative difference between samples, regardless of either place or date of collection. PMID:23472461

Patel, Asmita V; Sumner, Stephen; Thompson, H Leslie; Blunden, Gerald; Wright, David; Liu, Jun-Feng; Zan, Jun-Feng

2013-01-01

248

Investigation of textured back reflectors for microcrystalline silicon based solar cells  

SciTech Connect

Microcrystalline silicon ({micro}c-Si:H) solar cells require an effective light trapping in the near infrared (NIR) to enhance the long wavelength spectral response. For this purpose the authors investigated back reflectors based on texture-etched ZnO/Ag stacks prepared on glass substrates by magnetron sputtering. With decreasing sputter pressure the resulting surface texture of the glass/Ag/ZnO substrates after etching exhibits a larger feature size and root mean square roughness. The increase in feature size corresponds to an increase of diffuse reflectivity. Applied in microcrystalline solar cells prepared by VHF plasma enhanced chemical vapor deposition (PECVD), the reflectors showing the largest feature size (prepared at the lowest possible sputter pressure) yielded the highest long wavelength spectral response. The {micro}c-Si n-i-p cells prepared on the latter back reflector exhibited efficiencies of 6.9% (short circuit current density j{sub sc} = 18.8 mA/cm{sup 2}) and 7.5% (j{sub sc} = 25 mA/cm{sup 2}) for an i-layer thickness of 1 {micro}m and 3.5 {micro}m, respectively.

Kluth, O.; Vetterl, O.; Carius, R.; Finger, F.; Wieder, S.; Rech, B.; Wagner, H.

1999-07-01

249

A Chemical Ionization High-Resolution Time-of-Flight Mass Spectrometer Coupled to a Micro Orifice Volatilization Impactor (MOVI-HRToF-CIMS) for Analysis of Gas and Particle-Phase Organic Species  

Microsoft Academic Search

We describe a new instrument, chemical ionization high-resolution time-of-flight mass spectrometer coupled to a micro-orifice volatilization impactor (MOVI-HRToF-CIMS). The MOVI-HRToF-CIMS instrument is unique in that, within a compact field-deployable package, it provides (1) quantifiable molecular-level information for both gas and particle phase organic species on timescales ranging from ?1 second for gases and 10 - 60 minutes for particle-phase compounds

Reddy L. N. Yatavelli; Felipe Lopez-Hilfiker; Julia D. Wargo; Joel R. Kimmel; Michael J. Cubison; Timothy H. Bertram; Jose L. Jimenez; Marc Gonin; Douglas R. Worsnop; Joel A. Thornton

2012-01-01

250

Elemental analyses of hypervelocity micro-particle impact sites on interplanetary dust experiment sensor surfaces  

Microsoft Academic Search

The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity micro-particles that struck the active sensors with enough energy to breakdown the 0.4 to 1.0 micron thick SiO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A

Charles G. Simon; J. L. Hunter; D. P. Griffis; V. Misra; D. R. Ricks; Jim J. Wortman

1992-01-01

251

A nanoporous silicon membrane electrode assembly for on-chip micro fuel cell applications  

Microsoft Academic Search

Silicon-based fuel cells are under active development for chip-scale electrical power supply. One of the greatest challenges in micro-fuel-cell research is the development of a suitable proton conducting membrane material that is compatible with standard silicon microfabrication technology. In this paper, the use of nanoporous silicon as a novel proton conducting membrane material in a microscale fuel cell membrane electrode

Kuan-Lun Chu; Scott Gold; V. Subramanian; Chang Lu; M. A. Shannon; R. I. Masel

2006-01-01

252

Micro-machined resonator  

DOEpatents

A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

Godshall, N.A.; Koehler, D.R.; Liang, A.Y.; Smith, B.K.

1993-03-30

253

Study of silicone-based materials for the packaging of optoelectronic devices  

NASA Astrophysics Data System (ADS)

The first part of this work is to evaluate the main materials used for the packaging of high power light-emitting diodes (LEDs), i.e., the die attach materials, the encapsulant materials, and high color rendering index(CRI) sol-gel composite materials. All of these materials had been discussed the performance, reliability, and issues in high power LED packages. High power white LEDs are created either from blue or near-ultraviolet chips encapsulated with a yellow phosphor, or from red-green-blue LED light mixing systems. The phosphor excited by blue LED chip was mostly used in experiment of this dissertation. The die attach materials contains filler particles possessing a maximum particle size less than 1.5 mum in diameter blended with epoxy polymer matrix. Such compositions enable thin bond line thickness, which decreases thermal resistance that exists between thermal interface materials and the corresponding mating surfaces. The thermal conductivity of nano silver die attach materials is relatively low, the thermal resistance from the junction to board is just 1.6 KW-1 in the bond line thickness of 5.3 mum, which is much lower than the thermal resistance using conventional die attach materials. The silicone die attach adhesive made in the lab cures through the free radical reaction of epoxy-functional organopolysiloxane and through the hydrosilylation reaction between alkenyl-functional organopolysiloxane and silicone-boned hydrogen-functional organopolysiloxane. By the combination of the free radical reaction and the hydrosilylation reaction, the low-molecular-weight silicone oil will not be out-migrated and not contaminate wire bondability to the LED chip and lead frame. Hence, the silicone die attach adhesive made in the lab can pass all reliability tests, such as operating life test JEDEC 85°C/85RH and room temperature operating life test. For LED encapsulating materials, most of commercial silicone encapsulants still suffer thermal/radiation induced degradations, and thus cause reliability issues and shorten the lifetime. A new high performance silicone has been developed and its performance has been compared with other commercial silicone products in the packaging of high power white LEDs. The high performance silicone also has better results than commercial high refractive index silicone and optical grade epoxy under JEDEC reliability standard for moisture sensitivity test. In synthesis of red dye-doped particles by sol-gel method, it is a novel method to get high color rendering index (CRI) LEDs. These red dye-doped particles, with average diameter of 5 mum, can be mixed with liquid encapsulants to form a uniform distribution in polymer matrix. The red dye-doped particles can be excited by phosphor-emitted yellow light instead of blue light from LED chip. Therefore, warm white LEDs with high CRI can be gotten at high lumen efficiency. The second part of this work is silicone elastomer for biomedical applications, especially in making urological implantable devices. A cross-linked, heat curable, addition-reaction silicone material is prepared. The material may be molded or formed into one or more medical devices. One such medical device could be a catheter used in urological applications. The material is a long term indwelling material that resists encrustation like a metal stent, but is more comfortable because it is silicone-based. The material can be made relatively cheaply compared to metal stents. Furthermore, the material is biocompatible with bladder epithelial cells.

Lin, Yeong-Her

254

Capillary micro-switches  

NASA Astrophysics Data System (ADS)

A capillary surface is a liquid/liquid or liquid/gas interface whose shape is determined by surface tension. Capillary surfaces occur when the capillary length is large compared to the container scale, as happens for typical liquids against gas on the sub-millimeter scale on Earth and on the meter scale in the micro-gravity environment of space vehicles. Manipulating capillary surfaces has emerged as a leading strategy for moving liquids on the micro-scale [1]. Practitioners have yet to take advantage of capillary instability in their design of devices, though. We illustrate how the response diagram of a single switch (bi-stable device) can be constructed from that of two capillary elements, how that of a system of switches (a pair) can be built from that of a single switch and finally how understanding the response of the system guides us to observations of new behavior in the laboratory. Experiments on capillary surfaces use either a soap-film analog (10 centimeter scale) or a liquid/gas (millimeter scale) apparatus. Progress is reported on the application of an array of micro-switches to make a controllable adhesion device, with the aim of effecting droplet transport. 1. Cho, Fan, Moon and Kim, "Towards digital microfluidic circuits: creating, transporting, cutting and merging liquid droplets by electrowetting-based actuation." Proc. 15th IEEE Int'l Conf. on MEMS, January 2002.

Steen, Paul; Matalanis, Claude; Hirsa, Amir; Cox, Christhopher

2002-11-01

255

Gas Producing Micro-Reaction  

NSDL National Science Digital Library

In this chemistry activity, learners use common chemicals and metals to examine reactions that produce gaseous substances. Learners will identify the gases produced and write a balanced equation for each reaction. Use this activity to also introduce learners to single displacement and double displacement reactions, two types of chemical reactions.

House, The S.

2013-05-15

256

Silicon Based Solid Oxide Fuel Cell Chip for Portable Consumer Electronics -- Final Technical Report  

SciTech Connect

LSI’s fuel cell uses efficient Solid Oxide Fuel Cell (“SOFC”) technology, is manufactured using Micro Electrical Mechanical System (“MEMS”) fabrication methods, and runs on high energy fuels, such as butane and ethanol. The company’s Fuel Cell on a Chip™ technology enables a form-factor battery replacement for portable electronic devices that has the potential to provide an order-of-magnitude run-time improvement over current batteries. Further, the technology is clean and environmentally-friendly. This Department of Energy funded project focused on accelerating the commercialization and market introduction of this technology through improvements in fuel cell chip power output, lifetime, and manufacturability.

Alan Ludwiszewski

2009-06-29

257

Structural and Oxidative Changes in the Kidney of Crucian Carp Induced by Silicon-Based Quantum Dots  

PubMed Central

Silicon-based quantum dots were intraperitoneally injected in Carassius auratus gibelio specimens and, over one week, the effects on renal tissue were investigated by following their distribution and histological effects, as well as antioxidative system modifications. After three and seven days, detached epithelial cells from the basal lamina, dilated tubules and debris in the lumen of tubules were observed. At day 7, nephrogenesis was noticed. The reduced glutathione (GSH) concentration decreased in the first three days and started to rise later on. The superoxide dismutase (SOD) activity increased only after one week, whereas catalase (CAT) was up-regulated in a time-dependent manner. The activities of glutathione reductase (GR) and glutathione peroxidise (GPX) decreased dramatically by approximately 50% compared to control, whereas the glutathione-S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH) increased significantly after 3 and 7 days of treatment. Oxidative modifications of proteins and the time-dependent increase of Hsp70 expression were also registered. Our data suggest that silicon-based quantum dots induced oxidative stress followed by structural damages. However, renal tissue is capable of restoring its integrity by nephron development.

Petrache, Sorina Nicoleta; Stanca, Loredana; Serban, Andreea Iren; Sima, Cornelia; Staicu, Andreia Cristina; Munteanu, Maria Cristina; Costache, Marieta; Burlacu, Radu; Zarnescu, Otilia; Dinischiotu, Anca

2012-01-01

258

Design and evaluation of a low nitrogen oxides natural gas-fired conical wire-mesh duct burner for a micro-cogeneration unit  

NASA Astrophysics Data System (ADS)

A novel low NOx conical wire-mesh duct burner was designed, built and tested in the present research. This thesis documents the design process and the in-depth evaluation of this novel duct burner for the development of a more efficient micro-cogeneration unit. This duct burner provides the thermal energy necessary to raise the microturbine exhaust gases temperature to increase the heat recovery capability. The duct burner implements both lean-premixed and surface combustion techniques to achieve low NOx and CO emissions. The design of the duct burner was supported by a qualitative flow visualization study for the duct burner premixer to provide insight into the premixer flow field (mixing process). Different premixer geometries were used to control the homogeneity of the fuel-oxidant mixture at the exit of the duct burner premixer. Laser sheet illumination (LSI) technique was used to capture images of the mixing process, for each configuration studied. A quasi-quantitative analysis technique was developed to rank the different premixer geometries in terms of mixing effectiveness. The premixer geometries that provided better mixing were selected and used for the combustion tests. The full-scale gas-fired duct burner was installed in the exhaust duct of a micro-cogeneration unit for the evaluation. Three wire-mesh burners with different pressure drops were used. Each burner has a conical shape made from FeCrAL alloy mat and was designed based on a heat release per unit area of 2500 kW/m2 and a total heat release of 240kW at 100 percent excess air. The local momentum of the gaseous mixture introduced through the wire-mesh was adjusted so that the flame stabilized outside the burner mesh (surface combustion). Cold flow tests (i.e., the duct burner was off, but the microturbine was running) were conducted to measure the effect of different duct burner geometrical parameters on flow split between the combustion zone and the bypass channel, and on pressure drop across the duct burner. A considerable amount of detailed parametric experimental data was collected to investigate the performance characteristics of the duct burner. The variables studied (firing rate, mass flow ratio, conical burner pressure drop, blockage ratio, conical burner shield length, premixer geometry and inlet conditions) were all found to play an important role on emissions (NOx and CO), overall duct burner pressure drop and flame stability. The range of firing rates at which surface combustion was maintained for the duct burner was defined by direct observation of the burner surface and monitoring of the temperature in the combustion zone. Flame images were captured for qualitative assessment. The combustion tests results presented in this thesis proved that the design procedures that were implemented to design this novel microturbine conical wire-mesh duct burner were successful. During the course of the combustion tests, the duct burner displayed stable, low emissions operation throughout the surface firing rate range of 148 kW to 328 kW (1574 kW/m 2 to 3489 kW/m2). Emissions of less than 5 ppm (corrected to 15 percent 02) for NOx and CO emissions were recorded, while the duct burner successfully raised the microturbine exhaust gases temperature from about 227°C to as high as 700°C. The overall duct burner pressure drop throughout was consistently below the design limit of 249 Pa.

Ramadan, Omar Barka Ab

259

Micro-liquid flow sensor  

Microsoft Academic Search

A simple to realise micro-liquid flow sensor with high sensitivity is presented. The sensor is based on well known thermal anemometer principles. An analytical model for the sensor behaviour applicable for gas\\/liquid fluids is presented. The realisation process of the sensor is described. Model and experimental results agree well. The sensor is simple to integrate with other micro-liquid handling components

Theo S. J. Lammerink; Niels R. Tas; Miko Elwenspoek; Jan H. J. Fluitman

1993-01-01

260

Three-dimensional analysis of heat transfer in a micro-heat sink with single phase flow  

Microsoft Academic Search

A detailed numerical simulation of forced convection heat transfer occurring in silicon-based microchannel heat sinks has been conducted using a simplified three-dimensional conjugate heat transfer model (2D fluid flow and 3D heat transfer). The micro-heat sink model consists of a 10 mm long silicon substrate, with rectangular microchannels, 57 ?m wide and 180 ?m deep, fabricated along the entire length.

J. Li; G. P. Peterson; P. Cheng

2004-01-01

261

Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof  

DOEpatents

An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications is disclosed. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al[sub x]N[sub y]O[sub z] layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al[sub x]N[sub y]O[sub z] layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

Sarin, V.K.

1990-08-21

262

Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof  

SciTech Connect

An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al.sub.x N.sub.y O.sub.z layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al.sub.x N.sub.y O.sub.z layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

Sarin, Vinod K. (Lexington, MA)

1990-01-01

263

Investigation of silicon-based nanostructure morphology and chemical termination on laser desorption ionization mass spectrometry performance.  

PubMed

We have evaluated the laser desorption ionization mass spectrometry (LDI-MS) performance of six nanostructured silicon surfaces of different morphologies and chemical functionalizations. The substrates have been synthesized either by metal-assisted etching method or by vapor-liquid-solid (VLS) growth technique. In addition to the commercial nanostructured silicon-based surface (NALDI) target plates, serving as reference, the homemade surfaces have been evaluated in mass spectrometry experiments conducted with peptide solutions mimicking tryptic digests. LDI surfaces synthesized by metal-assisted etching method were the most efficient in terms of signal intensities and number of detected peptides. The surface providing the best LDI-MS performance was composed of two nanostructured layers. Interestingly, we also observed a significant influence of the type of organic coating (hydrocarbon vs fluorocarbon) on peptide ionization discrimination. PMID:23163782

Dupré, Mathieu; Enjalbal, Christine; Cantel, Sonia; Martinez, Jean; Megouda, Nacéra; Hadjersi, Toufik; Boukherroub, Rabah; Coffinier, Yannick

2012-11-30

264

Chemical surface modifications for the development of silicon-based label-free integrated optical (IO) biosensors: a review.  

PubMed

Increasing interest has been paid to label-free biosensors in recent years. Among them, refractive index (RI) optical biosensors enable high density and the chip-scale integration of optical components. This makes them more appealing to help develop lab-on-a-chip devices. Today, many RI integrated optical (IO) devices are made using silicon-based materials. A key issue in their development is the biofunctionalization of sensing surfaces because they provide a specific, sensitive response to the analyte of interest. This review critically discusses the biofunctionalization procedures, assay formats and characterization techniques employed in setting up IO biosensors. In addition, it provides the most relevant results obtained from using these devices for real sample biosensing. Finally, an overview of the most promising future developments in the fields of chemical surface modification and capture agent attachment for IO biosensors follows. PMID:23622959

Bañuls, María-José; Puchades, Rosa; Maquieira, Ángel

2013-01-23

265

Appearances of internal micro bubbling, multiple micro explosions, multiple micro jets and micro diffusion flames around an abruptly heated micro plastic-resin particle  

Microsoft Academic Search

Heating, gasifying and burning processes of a micro plastic-resin particle, which has a diameter of about 200?m and is suddenly exposed to a hot oxidizing atmosphere, are observed and optically processed by combining a micro schlieren system with a high-speed CCD video camera. The following three devised approaches are introduced: the use of an oxidizing combustion gas downstream of a

Yojiro Ishino; Ryuji Yamakita; Norio Ohiwa

2007-01-01

266

Forensic analysis of a single particle of partially burnt gunpowder by solid phase micro-extraction–gas chromatography-nitrogen phosphorus detector  

Microsoft Academic Search

Solid phase micro-extraction (SPME) was adopted to extract organic gun shot residues (OGSRs) from a single particle of partially burnt gunpowder. The partially burnt particle samples were collected from gun shot residue (GSR) deposited near the target areas. OGSRs, such as diphenylamine (DPA), methyl centralite (MC), ethyl centralite (EC), from only one single particle of partially burnt gunpowder were successfully

Garrett Lee Burleson; Brittney Gonzalez; Kelsie Simons; Jorn C. C. Yu

2009-01-01

267

Tensile bond strength of silicone-based soft denture liner to two chemically different denture base resins after various surface treatments.  

PubMed

This study evaluated the effect of various surface treatments on the tensile bond strength of a silicone-based soft denture liner to two chemically different denture base resins, heat-cured polymethyl methacrylate (PMMA), and light-activated urethane dimethacrylate or Eclipse denture base resin. PMMA test specimens were fabricated and relined with a silicone-based soft denture liner (group AC). Eclipse test specimens were prepared according to the manufacturer's recommendation. Before they were relined with a silicone-based soft denture liner, each received one of three surface treatments: untreated (control, group EC), Eclipse bonding agent applied (group EB), and laser-irradiated (group EL). Tensile bond strength tests (crosshead speed = 5 mm/min) were performed for all specimens, and the results were analyzed using the analysis of variance followed by Tukey's test (p = 0.05). Eclipse denture base and PMMA resins presented similar bond strengths to the silicone-based soft denture liner. The highest mean force was observed in group EL specimens, and the tensile bond strengths in group EL were significantly different (p < 0.05) from those in the other groups. PMID:22447403

Akin, Hakan; Tugut, Faik; Guney, Umit; Kirmali, Omer; Akar, Turker

2012-03-25

268

Design and Fabrication Issues of a Silicon-Based Vibration Powered Electric Energy Generator Using Parallel Plate and In-Plane Mechanism  

Microsoft Academic Search

This paper focuses on the design and fabrication issues of a silicon-based, vibration powered, electric energy generator. Its architecture is based on the parallel plate configuration. It uses electrostatic damping of variable MEMS capacitor as the energy converting mechanism. Variable capacitance is achieved by in-plane movement of the top electrode. Hence capacitance variation is achieved by means of change in

A. M. Paracha; P. Basset; C. L. P. Lim; F. Marty; P. Poulichet; G. Amendola; T. Bourounia

2006-01-01

269

Lattice gas simulations of dynamical geometry in one dimension: One contribution of 21 to a Theme 'Connecting scales: micro, meso and macro processes'  

Microsoft Academic Search

We present numerical results obtained using a lattice gas model with dynamical geometry. The (irreversible) macroscopic behaviour of the geometry (size) of the lattice is discussed in terms of a simple scaling theory and obtained numerically. The emergence of irreversible behaviour from the reversible microscopic lattice gas rules is discussed in terms of the constraint that the macroscopic evolution be

Peter J. Love; Bruce M. Boghosian; David A. Meyer

2004-01-01

270

Generation of 200-microJ, sub-25-fs deep-UV pulses using a noble-gas-filled hollow fiber.  

PubMed

High-energy 110-fs pulses of a KrF excimer laser system were spectrally broadened by self-phase modulation in a neon-filled hollow fiber and subsequently compressed by a grating pair. In this way, 25-fs pulses with energies as high as 200 microJ were generated at 248 nm. The pulses were characterized by an all-reflective single-shot transient grating frequency-resolved optical gating. PMID:19649077

Nagy, Tamas; Simon, Peter

2009-08-01

271

Advanced etching of silicon based on deep reactive ion etching for silicon high aspect ratio microstructures and three-dimensional micro- and nanostructures  

Microsoft Academic Search

Different processes involving an inductively coupled plasma reactor are presented either for deep reactive ion etching or for isotropic etching of silicon. On one hand, high aspect ratio microstructures with aspect ratio up to 107 were obtained on sub-micron trenches. Application to photonic MEMS is presented. Isotropic etching is also used either alone or in combination with anisotropic etching to

F. Marty; L. Rousseau; B. Saadany; B. Mercier; O. Français; Y. Mita; T. Bourouina

2005-01-01

272

Ion beam synthesis of carbon assisted nanosystems in silicon based substrates  

NASA Astrophysics Data System (ADS)

The systematic study of the formation of beta-SiC formed by low energy carbon ion (C-) implantation into Si followed by high temperature annealing is presented. The research is performed to explore the optimal annealing conditions. The formation of crystalline beta-SiC is clearly observed in the sample annealed at 1100 °C for a period of 1 hr. Quantitative analysis is performed in the formation of beta-SiC by the process of implantation of different carbon ion fluences of 1x1017, 2x1017, 5x1017, and 8x1017 atoms /cm2 at an ion energy of 65 keV into Si. It is observed that the average size of beta-SiC crystals decreased and the amount of beta-SiC crystals increased with the increase in the implanted fluences when the samples were annealed at 1100°C for 1 hr. However, it is observed that the amount of beta-SiC linearly increased with the implanted fluences up to 5x1017 atoms /cm2. Above this fluence the amount of beta-SiC appears to saturate. The stability of graphitic C-C bonds at 1100°C limits the growth of SiC precipitates in the sample implanted at a fluence of 8x1017 atoms /cm2 which results in the saturation behavior of SiC formation in the present study. Secondly, the carbon cluster formation process in silica and the characterization of formed clusters is presented. Silicon dioxide layers ˜500 nm thick are thermally grown on a Si (100) wafer. The SiO2 layers are then implanted with 70 keV carbon ion at a fluence of 5x1017 atoms/cm2 . The implanted samples are annealed at 1100 °C for different time periods of 10 min., 30 min., 60 min., 90 min., and 120 min.,in the mixture of argon and hydrogen gas (96 % Ar + 4% hydrogen). Photoluminescence spectroscopy revealed UV to visible emission from the samples. A detail mechanism of the photoluminescence and its possible origin is discussed by correlating the structural and optical properties of the samples. Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction spectroscopy, photoluminescence spectroscopy, and transmission electron microscopy are used to characterize the samples.

Poudel, Prakash Raj

273

In situ deposition behavior of silica-based layers and its effect on thermal degradation of IN713 turbine blades during operation of a micro-gas turbine  

Microsoft Academic Search

This study examined the in situ deposition behavior of silica-based layers on IN713 turbine blades during the operation of a 13kgf-class gas turbine at a rotation speed of 20,000\\/min as well as its effect on the degradation of the metallic substrate. Tetraethylorthosilicate (TEOS) was mixed with the fuel (liquid petroleum gas, LPG) and burned to generate silica-based coating precursors for

Min Tae Kim; Doo Soo Kim; Won Young Oh

2010-01-01

274

Full breast digital mammography with an amorphous silicon-based flat panel detector: physical characteristics of a clinical prototype.  

PubMed

The physical characteristics of a clinical prototype amorphous silicon-based flat panel imager for full-breast digital mammography have been investigated. The imager employs a thin thallium doped CsI scintillator on an amorphous silicon matrix of detector elements with a pixel pitch of 100 microm. Objective criteria such as modulation transfer function (MTF), noise power spectrum, detective quantum efficiency (DQE), and noise equivalent quanta were employed for this evaluation. The presampling MTF was found to be 0.73, 0.42, and 0.28 at 2, 4, and 5 cycles/mm, respectively. The measured DQE of the current prototype utilizing a 28 kVp, Mo-Mo spectrum beam hardened with 4.5 cm Lucite is approximately 55% at close to zero spatial frequency at an exposure of 32.8 mR, and decreases to approximately 40% at a low exposure of 1.3 mR. Detector element nonuniformity and electronic gain variations were not significant after appropriate calibration and software corrections. The response of the imager was linear and did not exhibit signal saturation under tested exposure conditions. PMID:10757607

Vedantham, S; Karellas, A; Suryanarayanan, S; Albagli, D; Han, S; Tkaczyk, E J; Landberg, C E; Opsahl-Ong, B; Granfors, P R; Levis, I; D'Orsi, C J; Hendrick, R E

2000-03-01

275

In vivo validation of custom-designed silicon-based microelectrode arrays for long-term neural recording and stimulation.  

PubMed

We developed and validated silicon-based neural probes for neural stimulating and recording in long-term implantation in the brain. The probes combine the deep reactive ion etching process and mechanical shaping of their tip region, yielding a mechanically sturdy shank with a sharpened tip to reduce insertion force into the brain and spinal cord, particularly, with multiple shanks in the same array. The arrays' insertion forces have been quantified in vitro. Five consecutive chronically-implanted devices were fully functional from 3 to 18 months. The microelectrode sites were electroplated with iridium oxide, and the charge injection capacity measurements were performed both in vitro and after implantation in the adult feline brain. The functionality of the chronic array was validated by stimulating in the cochlear nucleus and recording the evoked neuronal activity in the central nucleus of the inferior colliculus. The arrays' recording quality has also been quantified in vivo with neuronal spike activity recorded up to 566 days after implantation. Histopathology evaluation of neurons and astrocytes using immunohistochemical stains indicated minimal alterations of tissue architecture after chronic implantation. PMID:22020666

Han, Martin; Manoonkitiwongsa, Panya S; Wang, Cindy X; McCreery, Douglas B

2011-10-18

276

In Vivo Validation of Custom-Designed Silicon-Based Microelectrode Arrays for Long-Term Neural Recording and Stimulation  

PubMed Central

We developed and validated silicon-based neural probes for neural stimulating and recording in long-term implantation in the brain. The probes combine the deep reactive ion etching process and mechanical shaping of their tip region, yielding a mechanically sturdy shank with a sharpened tip to reduce insertion force into the brain and spinal cord, particularly, with multiple shanks in the same array. The arrays’ insertion forces have been quantified in vitro. Five consecutive chronically-implanted devices were fully functional from 3 to 18 months. The microelectrode sites were electroplated with iridium oxide, and the charge injection capacity measurements were performed both in vitro and after implantation in the adult feline brain. The functionality of the chronic array was validated by stimulating in the cochlear nucleus and recording the evoked neuronal activity in the central nucleus of the inferior colliculus. The arrays’ recording quality has also been quantified in vivo with neuronal spike activity recorded up to 566 days after implantation. Histopathology evaluation of neurons and astrocytes using immunohistochemical stains indicated minimal alterations of tissue architecture after chronic implantation.

Manoonkitiwongsa, Panya S.; Wang, Cindy X.; McCreery, Douglas B.

2012-01-01

277

Silicon Based System for Single-Nucleotide-Polymorphism Detection: Chip Fabrication and Thermal Characterization of Polymerase Chain Reaction Microchamber  

NASA Astrophysics Data System (ADS)

A single nucleotide polymorphism (SNP) is a difference in the DNA sequence of one nucleotide only. We recently proposed a lab-on-a-chip (LoC) system which has the potentiality of fast, sensitive and highly specific SNP detection. Most of the chip components are silicon based and fabricated within a single process. In this paper, the newly developed fabrication method for the silicon chip is presented. The robust and reliable process allows etching structures on the same chip with very different aspect ratios. The characterization of a crucial component to the LoC SNP detector, the microreactor where DNA amplification is performed, is also detailed. Thanks to innovative design and fabrication methodologies, the microreactor has an excellent thermal isolation from the surrounding silicon substrate. This allows for highly localized temperature control. Furthermore, the microreactor is demonstrated to have rapid heating and cooling rates, allowing for rapid amplification of the target DNA fragments. Successful DNA amplification in the microreactor is demonstrated.

Majeed, Bivragh; Jones, Ben; Tezcan, Deniz S.; Tutunjyan, Nina; Haspeslagh, Luc; Peeters, Sara; Fiorini, Paolo; Beeck, Maaike Op de; Hoof, Chris Van; Hiraoka, Maki; Tanaka, Hiroyuki; Yamashita, Ichiro

2012-04-01

278

Endovascular micro tools  

Microsoft Academic Search

Endovascular micro tools mean the catheter-like systems with micro devices which are put into arteries and veins. An intravascular micro active catheter system is the most famous type of endovascular micro tools and it consists of active bending catheter and some functional catheters such as guide wire, balloon catheter, angioscope, drug delivery catheters, micro surgery tools and so on. These

Jun Keun Chang; Seok Chung; Yongku Lee; Seung-Ki Lee; Sang Sik Yang; Shin-Yong Moon; Johanes Tschepe; Youngjoon Chee; Dong-Chul Han

2000-01-01

279

Study of p-type and intrinsic materials for amorphous silicon based solar cells  

NASA Astrophysics Data System (ADS)

This dissertation summarizes the research work on the investigation and optimization of high efficiency hydrogenated amorphous silicon (a-Si:H) based thin film n-i-p single-junction and multi-junction solar cells, deposited using radio frequency (RF) and very high frequency (VHF) plasma enhanced chemical vapor deposition (PECVD) techniques. The fabrication and characterization of high quality p-type and intrinsic materials for a-Si:H based solar cells have been systematically and intensively studied. Hydrogen dilution, substrate temperature, gas flow rate, RF- or VHF-power density, and films deposition time have been optimized to obtain "on-the-edge" materials. To understand the material structure of the silicon p-layer providing a high Voc a-Si:H solar cell, hydrogenated amorphous, protocrystalline, and nanocrystalline silicon p-layers have been prepared using RF-PECVD and characterized by Raman spectroscopy and high resolution transmission electronic microscopy (HRTEM). It was found that the optimum Si:H p-layer for n-i-p a-Si:H solar cells is composed of fine-grained nanocrystals with crystallite sizes in the range of 3-5 nm embedded in an amorphous network. Using the optimized p-layer, an a-Si:H single-junction solar cell with a very high Voc value of 1.042 V and a FF value of 0.74 has been obtained. a-Si:H, a-SiGe:H and nc-Si:H i-layers have been prepared using RF- and VHF-PECVD techniques and monitored by different optical and electrical characterizations. Single-junction a-Si:H, a-SiGe and nc-Si:H cells have been developed and optimized. Intermediate bandgap a-SiGe:H solar cells achieved efficiencies over 12.5%. On the basis of optimized component cells, we achieved a-Si:Hla-SiGe:H tandem solar cells with efficiencies of ˜12.9% and a-Si:H/a-SiGe:H/a-SiGe:H triple-junction cells with efficiencies of ˜12.03%. VHF-PECVD technique was used to increase the deposition rates of the narrow bandgap materials. The deposition rate for a-SiGe:H i-layer attained 9 A/sec and the solar cell had a V oc of 0.588 V, Jsc of 20.4 mA/cm2, FF of 0.63, and efficiency of 7.6%. Preliminary research on the preparation of a-Si:Hlnc-Si:H tandem solar cells and a-Si:Hla-SiGe:Hlnc-Si:H triple-junction cells has also been undertaken using VHF nc-Si:H bottom cells with deposition rates of 6 A/sec. All I-V measurements were carried out under AM1.5G (100 MW/cm2) and the cell area was 0.25 cm2.

Du, Wenhui

280

High volume methane gas hydrate deposits in fine grained sediments from the Krishna-Godavari Basin: Analysis from Micro CT scanning  

NASA Astrophysics Data System (ADS)

The Indian National Gas Hydrate Program (NGHP) Expedition 1, of 2006, investigated several methane gas hydrate deposits on the continental shelf around the coast of India. Using pressure coring techniques (HYACINTH and PCS), intact gas-hydrate bearing, fine-grained sediment cores were recovered during the expedition. Once recovered, these cores were rapidly depressurized and submerged in liquid nitrogen, therefore preserving the structure and form of the hydrate within the host sediment. High resolution X-Ray CT scanning was later employed to image the internal structure of the gas hydrate, analyze the trends in vein orientation, and collect volumetric data. A scanning resolution of 0.08mm allowed for a detailed view of the three-dimensional distribution of the hydrate within the sediment from which detailed analysis of vein orientation could be made. Two distinct directions of vein growth were identified in each core section studied, which suggested the presence of a specific stress regime in the Krishna-Godavari basin during hydrate formation. In addition, image segmentation of gas hydrate from the sediment allowed for volumetric analysis of the hydrate content within each core section. Results from this analysis showed that high volumes of gas hydrate, up to approximately 70% of the pore space, were present. This high volume of methane gas hydrate can have a significant impact on the stability of the host sediment if dissociation of the hydrate were to occur in-situ, through the development of excess pore pressure, increase in water content and change in salinity of the host sediment.

Rees, E. V.; Clayton, C.; Priest, J.; Schultheiss, P. J.

2009-12-01

281

Fabrication of a MEMS micro-hotplate  

NASA Astrophysics Data System (ADS)

With the development of microelectronics and micromachining technology, micro-hotplate as a micro-heater is a very important component in micro-sensor. So far, it has wide applications in pressure detection, gas detection and so on. In this paper, a micro-hotplate based on micro-bridge structure was designed and fabricated. Here we present a micro-hotplate with SOI (silicon-on-insulator) as the substrate and metal Au as the heating electrode material. It shows low thermal conductivity coefficient, good electrical insulation, low power consumption, and excellent resistance to high temperature and low pressure. Some IC (integrated circuit) processes such as magnetron sputtering of Ni/Cr, ion beam sputtering of Au, dry and wet etching processes are employed to fabricate the device. Anisotropic wet etching of silicon and thin film deposition were mainly studied. To protect the front side micro structure during the wet etching process, a special apparatus was designed and fabricated. The optimization process for anisotropic wet etching was obtained for releasing the micro-bridge after a large number of experiments and the micro-hotplate was successfully fabricated. The electrical, thermal characteristics of the micro-hotplate were tested and approved it a well functional device.

Yi, Xian; Lai, Jianjun; Liang, Huafeng; Zhai, Xiaofeng

2011-02-01

282

Surface Functionalization with Phosphazene Substrates. Part II. Theoretical and Experimental Investigations of the Interactions of Hexachlorocyclophosphazene with Hydroxylated Silicon-based Surfaces  

Microsoft Academic Search

The interaction of hexachlorocyclophosphazene (HCCP) with the hydroxylated silicon-based surfaces is studied by a combination\\u000a of XPS experimental analysis and theoretical ab initio simulations, including the estimate of the energy barriers via CI-NEB method to determine the minimum energy reaction paths.\\u000a Several possible, stable chemisorbed configurations are found to exist, whose structural, energetic, and electronic properties have been analyzed in

Pier Luigi Silvestrelli; Mario Gleria; Roberto Milani; Angelo Boscolo Boscoletto

2006-01-01

283

Rapid detection and identification of biological and chemical agents by immunoassay, gene probe assay and enzyme inhibition using a silicon-based biosensor  

Microsoft Academic Search

A rapid biosensor assay procedure that utilizes biotin–streptavidin mediated filtration capture onto nitrocellulose membrane, in conjunction with a silicon-based light-addressable potentiometric sensor (LAPS) was developed for detection and identification of biological and chemical threat agents. Sandwich immunoassays, nucleic acid hybridization assays and enzyme inhibition assays are described. For immunoassays, the lower limits of detection (LOD) per 100-?l sample were approximately

William E Lee; H. Gail Thompson; John G Hall; Douglas E Bader

2000-01-01

284

Preparation and characterisation of silicone-based coatings filled with carbon nanotubes and natural sepiolite and their application as marine fouling-release coatings  

Microsoft Academic Search

This article reports on the preparation and partial characterisation of silicone-based coatings filled with low levels of either synthetic multiwall carbon nanotubes (MWCNTs) or natural sepiolite (NS). The antifouling and fouling-release properties of these coatings were explored through laboratory assays involving representative soft-fouling (Ulva) and hard-fouling (Balanus) organisms. The bulk mechanical properties of the coatings appeared unchanged by the addition

Alexandre Beigbeder; Philippe Degee; Sheelagh L. Conlan; Robert J. Mutton; Anthony S. Clare; Michala E. Pettitt; Maureen E. Callow; James A. Callow; Philippe Dubois

2008-01-01

285

Fabrication and calibration of silicon-based ball-tip optical ammonia sensor for on-line in-situ detection in water system  

Microsoft Academic Search

This paper describes the design, development and characterization of a silicon-based ball-tip optical fiber sensor for monitoring ammonia concentration in solutions. It is an extrinsic optic fiber sensor which is based on the light transmission absorption mode. An effective method has been developed to mix the pH indicator with PDMS as the sensing material by using ultrasound stirring, and a

Jianing Li

2011-01-01

286

Investigation of a silicon-based one-dimensional phononic crystal plate via the super-cell plane wave expansion method  

Microsoft Academic Search

The super-cell plane wave expansion method is employed to calculate band structures for the design of a silicon-based one-dimensional phononic crystal plate with large absolute forbidden bands. In this method, a low impedance medium is introduced to replace the free stress boundary, which largely reduces the computational complexity. The dependence of band gaps on structural parameters is investigated in detail.

Xue-Feng Zhu; Sheng-Chun Liu; Tao Xu; Tie-Hai Wang; Jian-Chun Cheng

2010-01-01

287

A silicon-based, all-passive, 60 GHz, 4-element, phased-array beamformer featuring a differential, reflection-type phase shifter  

Microsoft Academic Search

This paper presents an all-passive, 4-element, phased-array beamformer based on a differential, reflection-type phase shifter (RTPS) operating in the 60GHz band. The RTPS consists of a differential, vertically-coupled, coupled-line hybrid and variable, parallel-LC, resonant, reflective loads, both of which enable low-loss millimeter-wave operation. The design considerations for a silicon-based implementation of all the beamformer elements are discussed in detail. In

Harish Krishnaswamy; Alberto Valdes-Garcia; Jie-Wei Lai

2010-01-01

288

Design and development of wafer-level short wave infrared micro-camera  

NASA Astrophysics Data System (ADS)

Low cost IR Sensors are needed for a variety of Defense and Commercial Applications as low cost imagers for various Army and Marine missions. SiGe based IR Focal Planes offers a low cost alternative for developing wafer-level shortwave infrared micro-camera that will not require any cooling and can operate in the Visible-NIR band. The attractive features of SiGe based IRFPA's will take advantage of Silicon based technology, that promises small feature size and compatibility with the low power silicon CMOS circuits for signal processing. SiGe technology offers a low cost alternative for developing Visible-NIR sensors that will not require any cooling and can operate from 0.4- 1.7 microns. The attractive features of SiGe based IRFPA's will take advantage of Silicon based technology that can be processed on 12-inch silicon substrates, that can promise small feature size and compatibility with the Silicon CMOS circuit for signal processing. In this paper, we will discuss the design and development of Wafer-Level Short Wave Infrared (SWIR) Micro-Camera. We will discuss manufacturing approaches and sensor configurations for short wave infrared (SWIR) focal plane arrays (FPAs) that significantly reduce the cost of SWIR FPA packaging, optics and integration into micro-systems.

Sood, Ashok K.; Richwine, Robert A.; Pethuraja, Gopal; Puri, Yash R.; Lee, Je-Ung; Haldar, Pradeep; Dhar, Nibir K.

2013-06-01

289

Ultrasonic assisted headspace single drop micro-extraction and gas chromatography with nitrogen-phosphorus detector for determination of organophosphorus pesticides in soil.  

PubMed

This work describes optimization of headspace single drop micro-extraction for extraction of five organophosphorus pesticides; thionazin, sulfotep, dimethoate, disulfoton and parathion in soil. Ultrasound has also been used successfully to improve and accelerate the extraction of the analytes from the sample. The optimized extraction performance was obtained when the experimental parameters were set as follows; 3.0 ?L of octanol as extraction solvent, high ionic strength (20% sodium chloride), 1:1 (w/v) sample dilution with water, extraction temperature at 60 °C for 30 min; applying ultrasound and without any pH adjustment. The optimized method was linear over the calibration range (5-200 and 10-300 for different analytes) with limits of detection of 0.1-2.0 ng g(-1). The enrichment factor for OPPs was 1.4-12.7 and the method was also reproducible with the relative standard deviations (RSD%) of 2.1-6.9%. PMID:23498130

Salemi, Amir; Rasoolzadeh, Reihaneh; Nejad, Massumeh Mohebbi; Vosough, Maryam

2013-02-08

290

Strain-balanced silicon-germanium materials for near-IR photodetection in silicon-based optical interconnects  

NASA Astrophysics Data System (ADS)

Strain-balanced silicon-germanium superlattices grown on high quality compositionally graded buffers, or virtual substrates, make a complete range of alloy composition and biaxial strain combinations accessible. This structure is a unique way to achieve high quantum efficiency near IR photodetection for silicon-based optical interconnects. The growth of the strain-balanced superlattices by molecular beam epitaxy (MBE) and ultra high vacuum chemical vapor deposition (UHV-CVD) is presented and the role of adsorbed hydrogen during UHV- CVD growth is addressed. Hydrogen adsorption on the growth surface proved a useful technique to minimize coherent strain relaxation at the higher growth temperatures required for UHV-CVD silicon-germanium growth. The near IR absorption spectrum of the strained silicon-germanium materials possible using strain- balanced superlattices is critically required in the design of a photodetector. A model based on deformation potential theory and semiconductor absorption physics is used to predict the absorption coefficient as a function of strain and alloy composition. Photocurrent junction spectroscopy of strain-balanced silicon-germanium materials is used to confirm the results of the model. The effects of threading dislocations associated with the compositionally graded buffers on the bulk leakage current of photodiodes is determined using electron-beam induced current imaging techniques to measure dislocation density. The correlation between dislocation density and leakage current yielded a current per dislocation line length of 200 pA ?m-1. Coupling strategies for the integration of high dielectric contrast polycrystalline silicon/SiO 2 strip waveguides and silicon-germanium photodetectors are presented. The high optical power densities possible with the polycrystalline silicon waveguides permits the miniaturization of photodetectors. The effects of integration and miniaturization on photodetector performance are discussed. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139- 4307. Ph. 617-253-5668; Fax 617-253-1690.)

Giovane, Laura Marie

291

Breast imaging using an amorphous silicon-based full-field digital mammographic system: stability of a clinical prototype.  

PubMed

An amorphous silicon-based full-breast imager for digital mammography was evaluated for detector stability over a period of 1 year. This imager uses a structured CsI:TI scintillator coupled to an amorphous silicon layer with a 100-micron pixel pitch and read out by special purpose electronics. The stability of the system was characterized using the following quantifiable metrics: conversion factor (mean number of electrons generated per incident x-ray), presampling modulation transfer function (MTF), detector linearity and sensitivity, detector signal-to-noise ratio (SNR), and American College of Radiology (ACR) accreditation phantom scores. Qualitative metrics such as flat field uniformity, geometric distortion, and Society of Motion Picture and Television Engineers (SMPTE) test pattern image quality were also used to study the stability of the system. Observations made over this 1-year period indicated that the maximum variation from the average of the measurements were less than 0.5% for conversion factor, 3% for presampling MTF over all spatial frequencies, 5% for signal response, linearity and sensitivity, 12% for SNR over seven locations for all 3 target-filter combinations, and 0% for ACR accreditation phantom scores. ACR mammographic accreditation phantom images indicated the ability to resolve 5 fibers, 4 speck groups, and 5 masses at a mean glandular dose of 1.23 mGy. The SMPTE pattern image quality test for the display monitors used for image viewing indicated ability to discern all contrast steps and ability to distinguish line-pair images at the center and corners of the image. No bleeding effects were observed in the image. Flat field uniformity for all 3 target-filter combinations displayed no artifacts such as gridlines, bad detector rows or columns, horizontal or vertical streaks, or bad pixels. Wire mesh screen images indicated uniform resolution and no geometric distortion. PMID:11110258

Vedantham, S; Karellas, A; Suryanarayanan, S; D'Orsi, C J; Hendrick, R E

2000-11-01

292

Silicon based reconfigurable antennas  

Microsoft Academic Search

Summary form only given. Selects solid-state plasmas generated by PIN junctions to effectively implement various reconfigurable antennas. Other alternative technologies include MEMs switches to reconfigure antennas. PIN junctions can also be utilized as switches, and can replace MEMs to reconfigure antennas where speed of response is an issue. We have utilized these PIN junctions to dynamically define plasma regions with

A. Fathy; A. Rosen; F. McGinty; G. Taylor; S. Perlow; M. ElSherbiny

2000-01-01

293

Silicon-based optoelectronics  

Microsoft Academic Search

The decade of the 1990's is an opportune time for scientists and engineers to create cost-effective silicon “superchips” that merge silicon photonics with advanced silicon electronics on a silicon substrate. We can expect significant electrooptical devices from Column IV materials (Si, Ge, C and Sn) for a host of applications. The best devices will use strained-layer epitaxy, doped heterostructures, and

R. A. Soref

1993-01-01

294

Ex situ oxidation of IN713 turbine blades in situ deposited with silica layers during operation of a micro-gas turbine  

Microsoft Academic Search

The long-term stability of silica layers deposited in situ on the IN713 turbine blades was investigated by surveying an ex\\u000a situ thermally cycled oxidation test in air at 1050 °C. Two types of in situ coatings were prepared by burning tetraethylorthosilicate\\u000a with fuel during a 100-min operation of a 13 kgf-class gas turbine. The degradation of the blades upon the

Min Tae Kim; Doo Soo Kim

2011-01-01

295

Atomic-scale modeling of chemical vapor deposition processes from new complicated gas-phase mixtures for micro- and nanoelectronic applications  

NASA Astrophysics Data System (ADS)

Low-pressure chemical vapor deposition (CVD) is one of the most important processes for obtaining thin films widely used in semiconductor and in IC technology. Because of the baffling complexity of deposition process the usually-used approaches in CVD modeling include a great number of empiric non-calculated parameters, and this drawback becomes a grave disadvantage if one needs to model the process with new reagents and materials which were not used before. So we place primary emphasis upon the development of non-empirical deposition models that rely on phenomenological theories and experimental data only to a minimal extent. We are presenting the atomistic-scale models and software package throughout the entire deposition process that are based mainly on the first principles and ab initio methods. The main modeling stages are studied and discussed in detail, namely: atomistic modeling of gas-phase and surface reactions, determination of the basic chemical and physical mechanisms for the considered gas mixtures, calculations of the reactions rates for elementary reactions and acts, Monte Carlo and/or molecular dynamics simulation of the thin film growth, and modeling of macrokinetic processes in realistic deposition flow-reactor chamber. The modeling results for thin films deposition from actual gas mixtures are given. The physical properties of films as well as their stoichiometric composition and structure in dependence of process conditions are discussed.

Makhviladze, T. M.; Sarychev, M. E.

2009-01-01

296

Micropump and venous valve by micro stereo lithography  

NASA Astrophysics Data System (ADS)

Micro Stereo Lithography (MSL) is a poor man's LIGA for fabricating high aspect ratio MEMS devices in UV curable semiconducting polymers using either two computer-controlled low inertia galvanometric mirrors with the aid of focusing lens or an array of optical fibers. For 3D MEMS devices, the polymers need to have conductive and possibly piezoelectric or ferroelectric properties. Such polymers are being developed at Penn State resulting in microdevices for fluid and drug delivery. Applications may include implanted medical delivery system, artificial heart valves, chemical and biological instruments, fluid delivery in engines, pump coolants and refrigerants for local cooling of electronic components. With the invention of organic thin film transistor, now it is possible to fabricate 3D polymeric MEMS devices with built-in-electronics similar to silicon based microelectronics.

Varadan, Vijay K.; Varadan, Vasundara V.

2000-06-01

297

Principle of operation of micro pattern detectors  

NASA Astrophysics Data System (ADS)

Microstrip Gas Chambers (MSGC's), Small Gap and Groove detectors with an optional GEM foil are a recent development of gaseous micro-pattern detectors providing a cost efficient solution for a tracking detector. They provide good spatial resolution (~35 ?m) and can operate in high radiation environments (up to ~104 particles/mm2). The laboratory course on micro pattern detectors tried to give an understanding of the layout and basic functioning of these detectors. .

Cattai, A.; Malina, R.

2000-09-01

298

The 1.00 MeV proton radiation resistance studies of amorphous silicon-based alloy solar cells  

NASA Astrophysics Data System (ADS)

Amorphous silicon based (a-Si) alloy solar cells have been proposed as candidates for space applications. However, before space-born applications of a-Si cells can take place, the influence of the harsh space environment on the cells operating characteristics needs to be determined. The focus of this work is to investigate and model the effects of 1.00 MeV proton irradiation in the fluence range 10(exp l4) to 10(exp l5) cm(exp -2) and their annealing in the temperature range 0 to 200 C on the current density-voltage (J-V) and quantum efficiency (QE) characteristics of a-Si solar cells. 1.00 MeV protons degrade the J-V characteristics of a-Si cells. Single-junction a-Si:H cells show higher radiation resistance than either single-junction a-Si(sub x)Ge(sub l-x):H or dual-junction a-Si:H cells. The J(sub SC) is related to the fluence and electron drift-length/i-layer thickness ratio. The FF and eta/eta(sub O) are modeled as a function of fluence. Our experimental results were generally found to be in harmony with our simple models. Significant annealing of the J-V characteristics were observed at temperatures of 0 C and 22 C. A one-hour anneal at 200 C restored the J-V characteristics of the a-Si cells to their virgin values. Using first-order kinetics, the annealing of Jsc, FF and Eta/Eta(sub O) were modeled as a function of fast and slow annealing defects, and good agreement was found. The 1.00 MeV protons degraded the QE in a non-uniform fashion. The peak of the QE shifted toward the blue end of the spectrum. The QE of the a-Si cells was modeled as a function of thickness and electron drift-length. The experimental data were found to be in acceptable agreement with our simple model. The J(sub SC) was calculated from the convolution of the QE and AM1.5G spectrum. An average error of 45.3 percent (QE measured without light bias), and 6.8 percent (light biased QE) was observed between the calculated and measured J(sub SC). The J(sub SC) under AM0 illumination was calculated from the measured J(sub SC) under AM1.5G illumination .

Abdulaziz, Salman Saib

299

Microstructure, oxidation behavior and mechanical behavior of lens deposited niobium-titanium-silicon and niobium-titanium-silicon based alloys  

NASA Astrophysics Data System (ADS)

With current high temperature structural materials such as nickel based superalloys being pushed to the limits of suitable operating conditions, there comes a need for replacement materials with even higher temperature capabilities. Niobium silicon based systems have been shown to have superior density normalized strength at elevated temperatures when compared to currently used alloys. The drawbacks associated with the niobium silicon system are due to catastrophic oxidation behavior at elevated temperatures. Alloying addition have been shown to increase the oxidation resistance near suitable levels, but also decrease the high temperature strength and increases creep rates when compared to the binary alloy system. The microstructure of the material is similar to metal matrix composites in which high melting temperature silicides are dispersed in a niobium based matrix phase. The silicides produce high temperature strength while the niobium based matrix increases the room temperature properties such as fracture toughness. The bulk of the research has been conducted on directionally solidified material which has a coarse microstructure due to the slow cooling rates associated with the processing condition. The current research uses a powder metallurgy process termed Laser Engineered Net Shaping, or LENS, to produce material with a significantly refined microstructure due to fast cooling rates associated with the laser process. Several compositions of alloys were examined and the ideal processing parameters were determined for each alloy. The resulting microstructures show a refinement of the microstructure as expected with a fine scale distribution of Nb5Si3 and Nb3Si dispersed in a niobium based matrix phase. The high temperature oxidation behavior of the LENS deposited alloys was comparable to alloys produced using other techniques. A non protective oxide scale formed on samples exposed for only 0.5 hours but was not protective and showed large amounts of spallation at extended exposure times. The increase in grain boundaries and interfaces did not significantly increase the internal oxidation rate despite increased oxidation rates along these defects. The high temperature compression behavior was comparable to other alloys and processing techniques despite having a lower silicon content and therefore a smaller volume fraction of strengthening phase present. Dissolved oxygen levels in the LENS deposits appeared to be responsible for the increased strength at elevated temperatures. The oxygen levels in LENS processed alloys were higher than material produced by other processing techniques. The current work illustrates that the LENS processing techniques is a viable processing method for niobium silicide based materials and potentially increases the strength of the material.

Dehoff, Ryan Richard

300

Packaging a Liquid Metal ESD with Micro-Scale Mercury Droplet.  

National Technical Information Service (NTIS)

Micro-Gas-Analyzers have many applications in detecting chemical compounds present in the air. MEMS valves are used to perform sampling of gasses, as they enable control of fluid flow at the micro level. Current generation electrostatically actuated MEMS ...

2012-01-01

301

Evanescent straight tapered-fiber coupling of ultra-high Q optomechanical micro-resonators in a low-vibration helium-4 exchange-gas cryostat  

NASA Astrophysics Data System (ADS)

We developed an apparatus to couple a 50-?m diameter whispering-gallery silica microtoroidal resonator in a helium-4 cryostat using a straight optical tapered-fiber at 1550 nm wavelength. On a top-loading probe specifically adapted for increased mechanical stability, we use a specifically-developed ``cryotaper'' to optically probe the cavity, allowing thus to record the calibrated mechanical spectrum of the optomechanical system at low temperatures. We then demonstrate excellent thermalization of a 63-MHz mechanical mode of a toroidal resonator down to the cryostat's base temperature of 1.65 K, thereby proving the viability of the cryogenic refrigeration via heat conduction through static low-pressure exchange gas. In the context of optomechanics, we therefore provide a versatile and powerful tool with state-of-the-art performances in optical coupling efficiency, mechanical stability, and cryogenic cooling.

Rivière, R.; Arcizet, O.; Schliesser, A.; Kippenberg, T. J.

2013-04-01

302

In situ deposition behavior of silica-based layers and its effect on thermal degradation of IN713 turbine blades during operation of a micro-gas turbine  

NASA Astrophysics Data System (ADS)

This study examined the in situ deposition behavior of silica-based layers on IN713 turbine blades during the operation of a 13 kgf-class gas turbine at a rotation speed of 20,000/min as well as its effect on the degradation of the metallic substrate. Tetraethylorthosilicate (TEOS) was mixed with the fuel (liquid petroleum gas, LPG) and burned to generate silica-based coating precursors for deposition from the flame. Two deposition conditions were adopted. For condition 1 (C1), the silicon-to-carbon ratio in the mixed fuel was set at 0.1 mol% for the first 5 min and at zero mol% for the final 95 min in a 100-min operation. For condition 2 (C2), the ratio was set at 0.005 mol% during the entire 100 min operation. The total TEOS feed was the same under both conditions. C1 resulted in a rather uniform and thicker (5-10 ?m on the pressure side) porous silica-based coating on the blade than C2. The in situ deposited layer of C1 was well preserved on the blade and protected the underlying metallic substrate from oxidation during the entire 100 min operation. The layer on the C2 blades was ˜5 ?m thick at the region near to root, but was too thin in the other areas on the blade to be protective. The early build-up of a porous layer to an effective thickness on the blades produced a thermal barrier toward the substrate as well as a diffusion barrier toward the oxidizing elements during operation.

Kim, Min Tae; Kim, Doo Soo; Oh, Won Young

2010-09-01

303

Research on high-efficiency, multiple-gap, multi-junction amorphous silicon-based alloy thin-film solar cells  

NASA Astrophysics Data System (ADS)

This research program is directed toward the advancement of understanding of amorphous silicon-based alloys and their use in small area multi-junction solar cells. The program is divided into subtasks on materials research, single-junction solar cell research, and multi-junction solar cell research. In this report we discuss progress made during the period from March through August 1989. A major focus of the program was to achieve improvement in the performance of the back reflector and the antireflection coating to optimize cell performance. Computer simulation work was also carried out to analyze performance trade-offs between triple and tandem a-Si alloy solar cells.

Guha, S.

1990-07-01

304

Task B: Research on stable, high-efficiency, large-area, amorphous-silicon-based submodules: Semiannual subcontract report, 1 February 1987--31 July 1987  

Microsoft Academic Search

This semiannual report presents results of research on stable, high-efficiency, large-area, amorphous-silicon-based submodules. High conversion efficiencies (up to 11.95%) were obtained in small-area, single-junction, a-Si solar cells by using textured tin oxide, superlattice p-layers, graded carbon concentrations near the p-i interface, and highly relective ITO\\/silver back contacts. Researchers also fabricated single-junction a-SiC and a-SiGe p-i-n cells with efficiencies of 9%--11%.

D. E. Carlson; R. R. Arya; M. S. Bennett; A. Catalano; R. V. DAiello; C. R. Dickson; C. M. Fortmann; B. Goldstein; J. Morris; J. L. Newton

1988-01-01

305

Rapid and simple determination of psychotropic phenylalkylamine derivatives in human hair by gas chromatography-mass spectrometry using micro-pulverized extraction.  

PubMed

A gas chromatography-mass spectrometric (GC-MS) method was developed and validated for the determination of five psychotropic phenylalkylamine derivatives (amphetamine, AP; methamphetamine, MA; 3,4-methylenedioxyamphetamine, MDA; 3,4-methylenedioxymethamphetamine, MDMA; norketamine, NKT) in human hair. Hair samples (10mg) were washed with distilled water and acetone, mechanically pulverized for 1.5 min with a bead mill, and then incubated in 1 mL of methanol under ultrasonication at 50 degrees C for 1h. The resulting solutions were evaporated to dryness, derivatized using heptafluorobutyric anhydride (HFBA) at 50 degrees C for 30 min, and analyzed by GC-MS. The linear ranges were 0.1-20.0 ng/mg for AP and MA and 0.05-20.0 ng/mg for MDA, MDMA, and NKT, with the coefficients of determination (r(2)>0.9982). The intra-day and inter-day precisions were within 11.5% and 12.8%, respectively. The intra-day and inter-day accuracies were -4.1% to 5.8% and -6.6% to 4.2%, respectively. The limits of detections (LODs) for each compound were lower than 0.028 ng/mg. The recoveries were in the range of 78.9-101.2%. Based on these results, the method proved to be effective for the rapid and simple determination of phenylalkylamine derivatives in hair specimens. PMID:20060242

Kim, Jin Young; Shin, Soon Ho; Lee, Jae Il; In, Moon Kyo

2010-01-13

306

Determination of malondialdehyde in human blood by headspace-solid phase micro-extraction gas chromatography-mass spectrometry after derivatization with 2,2,2-trifluoroethylhydrazine.  

PubMed

Malondialdehyde (MDA) has been proposed as a useful biomarker of lipoperoxidation in biological samples, and more developed analytical methods are necessary. A simple and sensitive gas chromatography-mass spectrometry (HS-SPME-GC-MS) was described for the determination of malondialdehyde (MDA) in blood. Acetone-d(6) was used as internal standard. MDA and acetone d6 in blood reacted for 40 min at 50 degrees C with 2,2,2-trifluoroethylhydrazine in headspace vial and simultaneously the formed TFEH derivatives were vaporized and adsorbed on polydimethylsiloxane-divinylbenzene (PDMS-DVB). The compounds were desorbed for 1 min at 240 degrees C and injected in GC-MS. The reaction solution showed good recoveries at pH 4.0. In the established condition, the method detection limit (MDL) was 0.4 microg/L in 0.1 mL blood sample and the relative standard deviation was less than 8% at the concentration of 25.0 and 50.0 microg/L. The mean concentrations of MDA in normal human blood (n=20) were measured to be 187.9 microg/L (2.61 micromol/L). PMID:19800854

Shin, Ho-Sang

2009-09-20

307

Determination of volatile N-nitrosamines in meat products by microwave-assisted extraction coupled with dispersive micro solid-phase extraction and gas chromatography--chemical ionisation mass spectrometry.  

PubMed

A sensitive procedure, microwave-assisted extraction (MAE) coupled dispersive micro solid-phase extraction (D-?-SPE), was developed to extract N-nitrosodimethylamine (NDMA) and other six volatile N-nitrosamines (NAms) from meat products. Parameters affecting the efficiency of MAE and D-?-SPE were systematically investigated. For MAE, 5-g of a homogenised meat sample was extracted with 30 mL of a sodium hydroxide (0.025 M) solution at 100 °C for 10 min. The optimum D-?-SPE conditions were immersing 100mg of Carboxen™ 1000 adsorbent in the MAE extract. After vigorously shaking for 30 min, the NAms were then desorbed by treatment with 200 ?L of dichloromethane. A 10 ?L aliquot was determined by gas chromatography with chemical ionisation mass spectrometry (GC-CI-MS) using the selected-ion-storage (SIS) mode. The limits of quantitation (LOQs) were 0.03-0.36 ng/g. Preliminary results revealed that NDMA was present in the highest concentration, ranging from 0.8 to 3.2 ng/g. PMID:23265481

Huang, Man-Chun; Chen, Hsin-Chang; Fu, Ssu-Chieh; Ding, Wang-Hsien

2012-11-08

308

Preparation of polypyrrole-coated magnetic particles for micro solid-phase extraction of phthalates in water by gas chromatography-mass spectrometry analysis.  

PubMed

In this work, polypyrrole (PPy)-coated Fe(3)O(4) magnetic microsphere were successfully synthesized, and applied as a magnetic sorbent to extract and concentrate phthalates from water samples. The PPy-coated Fe(3)O(4) magnetic microspheres had the advantages of large surface area, convenient and fast separation ability. The PPy coating of magnetic microspheres contributed to preconcentration of phthalates from water sample, due to the ?-? bonding between PPy coating and the analytes. Also, the coating could prevent aggregation of the microspheres, and improve their dispersibility. In this study, seven kinds of phthalates were selected as model analytes, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-iso-butyl phthalate (DIBP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DNOP), and gas chromatography-mass spectrometry (GC-MS) was introduced to detect the phthalates after sample pretreatment. Important parameters of the extraction procedure were investigated, and optimized including eluting solvent, the amount of Fe(3)O(4)@PPy particles, and extraction time. After optimization, the procedure took only 15 min to extract and concentrate analytes with high efficiency. Validation experiments showed that the optimized method had good linearity (0.985-0.998), precision (3.4-11.7%), high recovery (91.1-113.4%), and the limits of detection were from 0.006 to 0.068 ?g/L. The results indicated that the novel method had advantages of convenience, good sensitivity, high efficiency, and it could also be applied successfully to analyze phthalates in real water sample. PMID:21315359

Meng, Jiaoran; Bu, Jing; Deng, Chunhui; Zhang, Xiangmin

2011-01-27

309

Invited Article: A materials investigation of a phase-change micro-valve for greenhouse gas collection and other potential applications  

NASA Astrophysics Data System (ADS)

The deleterious consequences of climate change are well documented. Future climate treaties might mandate greenhouse gas (GHG) emissions measurement from signatories in order to verify compliance. The acquisition of atmospheric chemistry would benefit from low cost, small size/weight/power of microsystems. In this paper, we investigated several key materials science aspects of a phase-change microvalve (PC?V) technology with low power/size/weight/cost for ubiquitous GHG sampling. The novel design, based on phase-change material low-melting-point eutectic metal alloys (indium-bismuth, InBi and tin-lead, SnPb), could be actuated at temperatures as low as 72 °C. Valve manufacturing was based on standard thick and thin-film processes and solder technologies that are commonly used in industry, enabling low-cost, high-volume fabrication. Aging studies showed that it was feasible to batch fabricate the PC?Vs and store them for future use, especially in the case of SnPb alloys. Hermetic sealing of the valve prototypes was demonstrated through helium leak testing, and Mil spec leak rates less than 1 × 10-9 atm cm3/s were achieved. This confirms that the sample capture and analysis interval can be greatly expanded, easing the logistical burdens of ubiquitous GHG monitoring. Highly conservative and hypothetical CO2 bias due to valve actuation at altitude in 1 cm3 microsamplers would be significantly below 1.0 and 2.2 ppmv for heat-treated InBi and SnPb solders, respectively. The CO2 bias from the PC?V scales well, as a doubling of sampler volume halved the bias. We estimated the shelf life of the SnPb PC?Vs to be at least 2.8 years. These efforts will enable the development of low cost, low dead volume, small size/weight microsystems for monitoring GHGs and volatile organic compounds.

Manginell, Ronald P.; Moorman, Matthew W.; Rejent, Jerome A.; Vianco, Paul T.; Grazier, Mark J.; Wroblewski, Brian D.; Mowry, Curtis D.; Achyuthan, Komandoor E.

2012-03-01

310

A micro-machined resonator  

DOEpatents

This invention is comprised of a micro-machined resonator, typically quartz, with upper and lower micromachinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrodes through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

Godshall, N.A.; Koehler, D.R.; Liang, A.Y.; Smith, B.K.

1991-12-31

311

Micro-ejector to supply fuel–air mixture to a micro-combustor  

Microsoft Academic Search

Micro-ejectors to supply fuel–air mixture to micro-combustors were fabricated and tested. The ejector sucks air using the jet of vaporized liquid gas ejected from a nozzle by its own vapor pressure, and needs no moving part and electric power supply. A tapered nozzle and a Laval nozzle were fabricated by the deep reactive ion etching of silicon. Using the Laval

Daisuke Satoh; Shuji Tanaka; Kazushi Yoshida; Masayoshi Esashi

2005-01-01

312

Room temperature micro-hydrogen-generator  

Microsoft Academic Search

A new compact and cost-effective hydrogen-gas generator has been made that is well suited for supplying hydrogen to a fuel-cell for providing base electrical power to hand-carried appliances. This hydrogen-generator operates at room temperature, ambient pressure and is orientation-independent. The hydrogen-gas is generated by the heterogeneous catalytic hydrolysis of aqueous alkaline borohydride solution as it flows into a micro-reactor. This

Don Gervasio; Sonja Tasic; Frederic Zenhausern

2005-01-01

313

Concentric Micro-Nebulizer for Direct Sample Insertion.  

National Technical Information Service (NTIS)

A concentric micro-nebulizer and method for introducing liquid samples into a plasma established in a plasma torch including a first tube connected to a source of plasma gas. The concentric micro-nebulizer has inner and outer concentric tubes extending up...

V. A. Fassel G. W. Rice K. E. Lawrence

1984-01-01

314

Method and Device for Creating a Micro Plasma Jet.  

National Technical Information Service (NTIS)

A microhollow cathode discharge assembly capable of generating a low temperature, atmospheric pressure plasma micro jet is disclosed. The microhollow assembly has at two electrodes: an anode and a cathode separated by a dielectric. A microhollow gas passa...

A. A. H. Mohamed J. F. Kolb K. H. Schoenbach

2005-01-01

315

Experimental investigation on a membrane distillation based micro-separator  

Microsoft Academic Search

In this work a novel micro-separator combining the sweep gas membrane distillation principle with micro-fluidic channels was designed and tested for the separation of a mixture of methanol and water with a low to high methanol concentration. The performance of the new separation device was studied with different liquid–vapor\\/gas membrane contactors with respect to the separation factor and the distillate

Chafika Adiche; Kai Sundmacher

2010-01-01

316

Development, validation and application of a methodology based on solid-phase micro extraction followed by gas chromatography coupled to mass spectrometry (SPME/GC-MS) for the determination of pesticide residues in mangoes.  

PubMed

A method was developed for the simultaneous analysis of 14 pesticide residues (clofentezine, carbofuran, diazinon, methyl parathion, malathion, fenthion, thiabendazole, imazalil, bifenthrin, permethrin, prochloraz, pyraclostrobin, difenoconazole and azoxystrobin) in mango fruit, based on solid-phase micro extraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Different parameters of the method were evaluated, such as fiber type, extraction mode (direct immersion and headspace), temperature, extraction and desorption times, stirring velocities and ionic strength. The best results were obtained using polyacrylate fiber and direct immersion mode at 50 degrees C for 30 min, along with stirring at 250 rpm and desorption for 5 min at 280 degrees C. The method was validated using mango samples spiked with pesticides at concentration levels ranging from 33.3 to 333.3 microg kg(-1). The average recoveries (n=3) for the lowest concentration level ranged from 71.6 to 117.5%, with relative standard deviations between 3.1 and 12.3%, respectively. Detection and quantification limits ranged from 1.0 to 3.3 microg kg(-1) and from 3.33 to 33.33 microg kg(-1), respectively. The optimized method was then applied to 16 locally purchased mango samples, all of them containing the pesticides bifenthrin and azoxystrobin in concentrations of 18.3-57.4 and 12.7-55.8 microg kg(-1), respectively, although these values were below the MRL established by Brazilian legislation. The method proved to be selective, sensitive, and with good precision and recovery rates, presenting LOQ below the MRL admitted by Brazilian legislation. PMID:20188930

Menezes Filho, Adalberto; dos Santos, Fábio Neves; Pereira, Pedro Afonso de Paula

2009-12-16

317

Development of a Silicon-Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System  

Microsoft Academic Search

Princeton Plasma Physics Laboratory, in collaboration with the Naval Research Laboratory, is currently investigating various novel materials (single-crystal silicon, <100>, <110>, and <111>) for use as electron beam transmission windows in a krypton fluoride (KrF) excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). The chosen

C. A. Gentile; H. M. Fan; J. W. Hartfield; R. J. Hawryluk; P. J. Heitzenroeder; C. H. Jun; L. P. Ku; P. H. LaMarche; M. C. Myers; J. J. Parker; R. F. Parsells; M. Payen; S. Raftopoulos; J. D. Sethian; F Hegeler

2003-01-01

318

Research on high-efficiency, multiple-gap, multi-junction amorphous silicon-based alloy thin-film solar cells  

SciTech Connect

This research program is directed toward the advancement of understanding of amorphous silicon-based alloys and their use in small area multi-junction solar cells. The program is divided into subtasks on materials research, single-junction solar cell research, and multi-junction solar cell research. In this report we discuss progress made during the period from March through August 1989. A major focus of the program was to achieve improvement in the performance of the back reflector and the antireflection coating to optimize cell performance. Computer simulation work was also carried out to analyze performance trade-offs between triple and tandem a-Si alloy solar cells. 10 refs., 27 figs., 5 tabs.

Guha, S. (Energy Conversion Devices, Inc., Troy, MI (USA))

1990-07-01

319

Electrical and luminescence properties of silicon-based tunnel transit-time light-emitting diodes p{sup +}/n{sup +}/n-Si:Er  

SciTech Connect

The electrical and luminescence properties of silicon-based tunnel transit-time light-emitting diodes (LEDs) p{sup +}/n{sup +}/n-Si:Er, emitting under reverse bias on the p{sup +}/n{sup +} junction in the breakdown regime, have been investigated. The room-temperature emission power at the wavelength {lambda} {approx} 1.5 {mu}m ({approx}5 {mu}W), external quantum efficiency ({approx}10{sup -5}), and excitation efficiency of erbium ions ({approx}2 x 10{sup -20} cm{sup 2} s) have been determined. At the same excitation efficiency, tunnel transit-time LEDs exhibit higher emission power in comparison with p{sup +}/n-Si:Er diode structures. The experimental results are compared with the model predictions for these structures. The factors limiting the electroluminescence intensity and impact excitation efficiency for erbium ions in tunnel transit-time LEDs are discussed.

Shmagin, V. B., E-mail: shm@ipm.sci-nnov.ru [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Kuznetsov, V. P. [Lobachevsky State University, Physicotechnical Research Institute (Russian Federation); Kudryavtsev, K. E. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Obolensky, S. V. [Lobachevsky State University (Russian Federation); Kozlov, V. A.; Krasil'nik, Z. F. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2010-11-15

320

A progress report on the LDRD project entitled {open_quotes}Microelectronic silicon-based chemical sensors: Ultradetection of high value molecules{close_quotes}  

SciTech Connect

This work addresses a new kind of silicon based chemical sensor that combines the reliability and stability of silicon microelectronic field effect devices with the highly selective and sensitive immunoassay. The sensor works on the principle that thin SiN layers on lightly doped Si can detect pH changes rapidly and reversibly. The pH changes affect the surface potential, and that can be quickly determined by pulsed photovoltage measurements. To detect other species, chemically sensitive films were deposited on the SiN where the presence of the chosen analyte results in pH changes through chemical reactions. A invention of a cell sorting device based on these principles is also described. A new method of immobilizing enzymes using Sandia`s sol-gel glasses is documented and biosensors based on the silicon wafer and an amperometric technique are detailed.

Hughes, R.C.

1996-09-01

321

Investigation of a silicon-based one-dimensional phononic crystal plate via the super-cell plane wave expansion method  

NASA Astrophysics Data System (ADS)

The super-cell plane wave expansion method is employed to calculate band structures for the design of a silicon-based one-dimensional phononic crystal plate with large absolute forbidden bands. In this method, a low impedance medium is introduced to replace the free stress boundary, which largely reduces the computational complexity. The dependence of band gaps on structural parameters is investigated in detail. To prove the validity of the super-cell plane wave expansion, the transmitted power spectra of the Lamb wave are calculated by using a finite element method. With the detailed computation, the band-gap of a one-dimensional plate can be designed as required with appropriate structural parameters, which provides a guide to the fabrication of a Lamb wave phononic crystal.

Zhu, Xue-Feng; Liu, Sheng-Chun; Xu, Tao; Wang, Tie-Hai; Cheng, Jian-Chun

2010-04-01

322

Variable leak gas source  

DOEpatents

A variable leak gas source and a method for obtaining the same which includes filling a quantity of hollow glass micro-spheres with a gas, storing said quantity in a confined chamber having a controllable outlet, heating said chamber above room temperature, and controlling the temperature of said chamber to control the quantity of gas passing out of said controllable outlet. Individual gas filled spheres may be utilized for calibration purposes by breaking a sphere having a known quantity of a known gas to calibrate a gas detection apparatus.

Henderson, Timothy M. (Ann Arbor, MI); Wuttke, Gilbert H. (Ann Arbor, MI)

1977-01-01

323

Sensitive detection of protein and miRNA cancer biomarkers using silicon-based photonic crystals and a resonance coupling laser scanning platform.  

PubMed

Enhancement of the fluorescent output of surface-based fluorescence assays by performing them upon nanostructured photonic crystal (PC) surfaces has been demonstrated to increase signal intensities by >8000×. Using the multiplicative effects of optical resonant coupling to the PC in increasing the electric field intensity experienced by fluorescent labels ("enhanced excitation") and the spatially biased funneling of fluorophore emissions through coupling to PC resonances ("enhanced extraction"), PC enhanced fluorescence (PCEF) can be adapted to reduce the limits of detection of disease biomarker assays, and to reduce the size and cost of high sensitivity detection instrumentation. In this work, we demonstrate the first silicon-based PCEF detection platform for multiplexed biomarker assay. The sensor in this platform is a silicon-based PC structure, comprised of a SiO2 grating that is overcoated with a thin film of high refractive index TiO2 and is produced in a semiconductor foundry for low cost, uniform, and reproducible manufacturing. The compact detection instrument that completes this platform was designed to efficiently couple fluorescence excitation from a semiconductor laser to the resonant optical modes of the PC, resulting in elevated electric field strength that is highly concentrated within the region <100 nm from the PC surface. This instrument utilizes a cylindrically focused line to scan a microarray in <1 min. To demonstrate the capabilities of this sensor-detector platform, microspot fluorescent sandwich immunoassays using secondary antibodies labeled with Cy5 for two cancer biomarkers (TNF-? and IL-3) were performed. Biomarkers were detected at concentrations as low as 0.1 pM. In a fluorescent microarray for detection of a breast cancer miRNA biomarker miR-21, the miRNA was detectable at a concentration of 0.6 pM. PMID:23963502

George, Sherine; Chaudhery, Vikram; Lu, Meng; Takagi, Miki; Amro, Nabil; Pokhriyal, Anusha; Tan, Yafang; Ferreira, Placid; Cunningham, Brian T

2013-08-20

324

Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates  

DOEpatents

A process is disclosed for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900--1500 C and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

Sarin, V.K.

1991-07-30

325

Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates  

SciTech Connect

A process for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900.degree.-1500.degree. C. and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

Sarin, Vinod K. (Lexington, MA)

1991-01-01

326

Micro matrix data marking  

US Patent & Trademark Office Database

The invention provides methods and systems for the application and reading of micro markings for coding of information for placement on the surfaces of individual very small devices. In preferred embodiments, a two dimensional micro matrix of markings or dots is realized on a scale of a 25 um cell size and smaller.

Blackall; Eric (Richardson, TX); Teggatz; Ross (McKinney, TX)

2013-10-08

327

Micro hydroelectric power stations  

Microsoft Academic Search

This book is a concise, comprehensive presentation of all aspects of hydro-power exploitation using micro-power stations. It offers engineers guidance to techniques for assessing the power available from a given stream, designing and building siteworks, selecting the appropriate turbine types for given conditions, and measuring and controlling environmental hazards associated with micro-hydro installations.

L. Monition; L. LeNir; J. Roux

1985-01-01

328

Micro and nano robotics  

Microsoft Academic Search

The paper presents two techniques for controlling of micro\\/nano robots. The first one uses so called visual servoing techniques, where the robot tip position is measured with a camera. The position of the robot tip is extracted from the live video picture, so on-line position feedback control can be established. The experimental results of 2 DOF micro robot neural network

R. Safaric; J. Cas; G. Skorc; S. I. Protsenko

2009-01-01

329

Simultaneous determination of bisphenol A and bisphenol B in beverages and powdered infant formula by dispersive liquid-liquid micro-extraction and heart-cutting multidimensional gas chromatography-mass spectrometry.  

PubMed

The purpose of this study was to establish a reliable, cost-effective, fast and simple method to quantify simultaneously both bisphenol A (BPA) and bisphenol B (BPB) in liquid food matrixes such as canned beverages (soft drinks and beers) and powdered infant formula using dispersive liquid-liquid micro-extraction (DLLME) with in-situ derivatisation coupled with heart-cutting gas chromatography-mass spectrometry (GC-MS). For the optimisation of the DLLME procedure different amounts of various extractive and dispersive solvents as well as different amounts of the derivative reagent were compared for their effects on extraction efficiency and yields. The optimised procedure consisted of the injection of a mixture containing tetrachloroethylene (extractant), acetonitrile (dispersant) and acetic anhydride (derivatising reagent) directly into an aliquot of beverage samples or into an aqueous extract of powdered milk samples obtained after a pretreatment of the samples. Given the compatibility of the solvents used, and the low volumes involved, the procedure was easily associated with GC-MS end-point determination, which was accomplished by means of an accurate GC dual column (heart-cutting) technique. Careful optimisation of heart-cutting GC-MS conditions, namely pressure of front and auxiliary inlets, have resulted in a good analytical performance. The linearity of the matrix-matched calibration curves was acceptable, with coefficients of determination (r2) always higher than 0.99. Average recoveries of the BPA and BPB spiked at two concentration levels into beverages and powdered infant formula ranged from 68% to 114% and the relative standard deviation (RSD) was <15%. The limits of detection (LOD) in canned beverages were 5.0 and 2.0 ng l(-1) for BPA and BPB, respectively, whereas LOD in powdered infant formula were 60.0 and 30.0 ng l(-1), respectively. The limits of quantification (LOQ) in canned beverages were 10.0 and 7.0 ng l-1 for BPA and BPB, respectively, whereas LOQ in powdered infant formula were 200.0 and 100.0 ng l(-1), respectively. BPA was detected in 21 of 30 canned beverages (ranging from 0.03 to 4.70 µg l(-1)) and in two of seven powdered infant formula samples (0.23 and 0.40 µg l(-1)) collected in Portugal. BPB was only detected in canned beverages being positive in 15 of 30 samples analysed (ranging from 0.06 to 0.17 µg l(-1)). This is the first report about the presence of BPA and BPB in canned beverages and powdered infant formula in the Portuguese market. PMID:21240700

Cunha, S C; Almeida, C; Mendes, E; Fernandes, J O

2011-02-17

330

Micro-bubble formation with organic membrane in a multiphase microfluidic system  

Microsoft Academic Search

This paper describes the continuous and uniform organic encapsulated micro-bubble generation system in a water flow microchannel including a lumped gas and organic injection junction. The micro-bubble was formed by the blow of organic phase into a water phase in microchannel and the gas was encapsulated in the thin organic membrane. Multiphase microchemical systems provide the large interfacial area, fast

Takahiro Arakawa; Takahiro Yamamoto; Shuichi Shoji

2008-01-01

331

Influence of initial micro-porosity of target on material ejection under nanosecond laser pulses  

Microsoft Academic Search

Heating and explosive destruction of the near surface volume of metal with initial micro-porosity under nanosecond laser pulse is simulated. It is shown that presence of initial micro-porosity may influence and modify the ejection mechanisms from melt and from solid phase. Thermal and gas dynamic processes in a gas bubble growing in laser irradiated melt are analysed. Experiments show rather

Yu. Chivel; M. Petrushina; I. Smurov

2007-01-01

332

Microcrystalline silicon germanium: An attractive bottom-cell material for thin-film silicon-based tandem-solar-cells  

SciTech Connect

The authors have prepared hydrogenated microcrystalline silicon germanium by plasma enhanced CVD of a mixture of silane and germane gas diluted with hydrogen. The growth conditions have been systematically controlled to obtain large ({approximately}400{angstrom}) crystallites of silicon-germanium as observed using Raman scattering and x-ray diffraction. The dangling bond (germanium) density has been reduced to <5 x 10{sup 16} cm{sup {minus}3} at low substrate temperatures ({approximately}150 C). The optical absorption spectra of the 50% Ge containing material is red-shifted compared to microcrystalline silicon, consistent with a reduction of the indirect optical gap to 0.9 eV. Schottky type cells fabricated using Au on an n{sup +} crystalline silicon substrate confirm that the long wavelength response is remarkably enhanced in this material.

Ganguly, Gautam; Ikeda, Toru; Kajiwara, Kei; Matduda, Akihisa

1997-07-01

333

FTIR spectroscopy for the hermeticity assessment of micro-cavities  

Microsoft Academic Search

This paper presents an alternative method for the hermeticity assessment of micro-cavities. The method consists in monitoring the internal gas pressure of a cavity by Fourier Transform Infra Red (FTIR) spectroscopy, and then deducing the cavity’s leak rate from the pressure variations. In order to carry out the IR transmission measurements, nitrous oxide was chosen as bombing gas due to

D. Veyrié; D. Lellouchi; J.-L. Roux; F. Pressecq; A. Tetelin; C. Pellet

2005-01-01

334

Enhancement of silicon using micro-patterned surfaces of thin films.  

PubMed

Micro-textured biomaterials might enhance cytocompatibility of silicon-based micro-electro-mechanical system (bio-MEMS) dummies. Photolithography-physical vapour deposition was used to produce diamond-like carbon (DLC) or Ti squares and circles on silicon, and also their inverse replicas; then DLC and Ti were compared for their guiding potential, using a SaOS-2 cell model. Scanning electron microscopy at 48 hours indicated cells were well-spread on large-sized patterns (several cells on one pattern) and assumed the geometrical architecture of underlying features. Medium-sized patterns (slightly smaller than solitary indicator cells) were inhabited by singular cells, which stretched from one island to another, assuming longitudinal or branching morphologies. On small-sized patterns (much smaller than individual cells;rpar; cells covered large micro-textured areas, but cellular filopodia bypassed the bare silicon. Immunofluorescence and confocal laser scanning microscopy indicated that the actin cytoskeleton and vinculin-containing adhesion junctions were present on the patterned areas, but not on the bare silicon. Cell density/coverage disclosed a 3.4-3.7-fold preference for the biomaterial patterns over silicon substrate (p 0.001). Differences in the cellular response between materials were lost at 120 hours when cells were confluent. The working hypothesis was proven; enhancement by micro-patterning depends on the pattern size, shape and material and can be used to improve biocompatibility during the initial integration phase of the device. PMID:20379964

Kaivosoja, Emilia; Myllymaa, Sami; Kouri, Vesa-Petteri; Myllymaa, Katja; Lappalainen, Reijo; Konttinen, Yrjö T

2010-04-09

335

Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System  

SciTech Connect

The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, <100>, <110> and <111>) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W {center_dot} cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated with 500 nm thin-film silicon nitride (Si{sub 3}N{sub 4}), has been fabricated. The window consists of 81 square panes with a thickness of 0.019 mm {+-} 0.001 mm. Stiffened (orthogonal) sections are 0.065 mm in width and 0.500 mm thick (approximate). Appended drawing (Figure 1) depicts the window configuration. Assessment of silicon (and silicon nitride) material properties and CAD modeling and analysis of the window design suggest that silicon may be a viable solution to inherent parameters and constraints.

C.A. Gentile; H.M. Fan; J.W. Hartfield; R.J. Hawryluk; F. Hegeler; P.J. Heitzenroeder; C.H. Jun; L.P. Ku; P.H. LaMarche; M.C. Myers; J.J. Parker; R.F. Parsells; M. Payen; S. Raftopoulos; J.D. Sethian

2002-11-21

336

Synthesis of silicon-based infrared semiconductors in the Ge-Sn system using molecular chemistry methods.  

PubMed

Growth reactions based on a newly developed deuterium-stabilized Sn hydride [(Ph)SnD(3)] with Ge(2)H(6) produce a new family of Ge-Sn semiconductors with tunable band gaps and potential applications in high-speed, high-efficiency infrared optoelectronics. Metastable diamond-cubic films of Ge(1-x)Sn(x) alloys are created by chemical vapor deposition at 350 degrees C on Si(100). These exhibit unprecedented thermal stability and superior crystallinity despite the 17% lattice mismatch between the constituent materials. The composition, crystal structure, electronic structure, and optical properties of these materials are characterized by Rutherford backscattering, high-resolution electron microscopy, and X-ray diffraction, as well as Raman, IR, and spectroscopic ellipsometry. Electron diffraction reveals monocrystalline and perfectly epitaxial layers with lattice constants intermediate between those of Ge and alpha-Sn. X-ray diffraction in the theta-2theta mode shows well-defined peaks corresponding to random alloys, and in-plane rocking scans of the (004) reflection confirm a tightly aligned spread of the crystal mosaics. RBS ion-channeling including angular scans confirm that Sn occupies substitutional lattice sites and also provide evidence of local ordering of the elements with increasing Sn concentration. The Raman spectra show bands corresponding to Ge-Ge and Sn-Ge vibrations with frequencies consistent with random tetrahedral alloys. Resonance Raman and ellipsometry spectra indicate a band-gap reduction relative to Ge. The IR transmission spectra suggest that the band gap decreases monotonically with increasing Sn fraction. The synthesis, characterization, and gas-phase electron diffraction structure of (Ph)SnD(3) are also reported. PMID:11686702

Taraci, J; Zollner, S; McCartney, M R; Menendez, J; Santana-Aranda, M A; Smith, D J; Haaland, A; Tutukin, A V; Gundersen, G; Wolf, G; Kouvetakis, J

2001-11-01

337

Micro-Meteorological Measurements.  

National Technical Information Service (NTIS)

Documentation of meteorological parameters occurring just prior to, during, and for a period after each of the four events of the series was the primary object of Project 2.4 (Micro-meteorological measurements). The meteorological parameters desired were ...

R. W. Titus

1965-01-01

338

Micro Piezoelectric Ultrasonic Motors.  

National Technical Information Service (NTIS)

This paper reviews recent developments of micro ultrasonic rotary motors using piezoelectric resonant vibrations. Following the historical background, four ultrasonic motors recently developed at Penn State University are introduced: windmill, PZT tube, m...

K. Uchino S. Cagatay B. Koc S. Dong P. Bouchilloux

2003-01-01

339

Micro film cooling performance  

Microsoft Academic Search

A novel idea for micro film cooling experiment is proposed and conducted. Both fabrication of a micro film-cooled device and evaluation of its performance are presented. The film cooling device is placed in a wind tunnel system for evaluation with the blowing parameter (M) ranging from 1 to 12.5 and the film jet slot heights of 25?m, 45?m and 50?m,

P. L. Li; H. S. Ko; D. Z. Jeng; C. W. Liu; C. Gau

2009-01-01

340

Digital MicroPropulsion  

Microsoft Academic Search

Arrays of “Digital Propulsion” micro-thrusters have been fabricated and tested. A three-layer sandwich is fabricated containing micro-resistors, thrust chambers, and rupture diaphragms. A propellant is loaded into the chambers, which are then sealed. When the resistor is heated sufficiently, the propellant ignites raising the pressure in the chamber and rupturing the diaphragm. An impulse is imparted as the high-pressure fluid

S. W. Janson; R. B. Cohen; E. K. Antonsson

1999-01-01

341

MicroGrids  

Microsoft Academic Search

The MicroGrid concept assumes a cluster of loads and microsources (<100 kW) operating as a single controllable system that provides both power and heat to its local area. This concept provides a new paradigm for defining the operation of distributed generation. To the utility the MicroGrid can be thought of as a controlled cell of the power system. For example

R. H. Lasseter

2002-01-01

342

Microplasmas and micro-jets  

NASA Astrophysics Data System (ADS)

Microplasmas are now widely investigated, one of their advantages being to generate a plasma at relatively high pressure close to the Paschen minimum (Schoenbach et al. 1997). Here, the microplasma is generated in a microhollow cathode type configuration made of a hole drilled through a metal/dielectric/metal sandwich (Schoenbach et al. 1997). One of the electrodes acts as the cathode (K) and the other as the anode (A1). The hole diameter ranges from 100 to 400 mu m and the pressure ranges from 50 to 500 Torr. When a second electrode (A2) is added, a large volume of plasma plume may be generated between A1 and A2, at a low electric field (1-20Td depending upon the gas) (Stark et al. 1999). A microhollow cathode type discharge operates in three different regimes depending on the plasma current: abnormal, self-pulsing and normal regime. The self-pulsing regime is achieved in the range of 1-100 kHz, in argon, helium, nitrogen and oxygen. The self-pulsing frequency is controlled by the microplasma device capacitance, the gas breakdown voltage, and the average discharge current (Rousseau et al. 2006, Aubert et al. 2007). i) First, in pure argon, the radial dependence of atoms excitation mechanisms and of the electronic density is studied inside the micro-hole. Imaging of the emission from the microplasma is performed with a spatial resolution of few mu m. The electron density is estimated from the Stark broadening of the H beta-line. The radial distribution of the emission intensities of an Ar atomic line and an Ar^+ ionic line are used for the excitation study. Ar and Ar^+ lines are excited in the cathode sheath edge by beam electrons accelerated within the sheath. These two excitations show the decay of the energy of electrons in negative glow. The Ar line presents also production of excited atoms by recombination of argon ions with electrons at the center of the micro-hole.Work is in progress to evaluate the contribution of the static electric field on the strak broadening ii) Second, in oxygen containing mixture, a flowing micro-jet is generated: the reactor used is separated in 2 rooms by the MHC. Thus, the gas is constrained to flow only through the microhole and the quantity of treated gas is well known. The gas flow is supersonic in most operating conditions at the exit of the microhole; despite a very large injected power density (typically 10^4 W cm^-), the gas heating does not exceed few hundreds of degrees, so that the plasma is non equilibrium. Different measurements are realized on the plume in pure O_2 and in Air. O_3 concentration has been measured by UV absorption spectroscopy; NO and NO_2 have been measured by tuneable diode laser absorption spectroscopy (TDLAS) in the infrared region (Ropcke et al. 2006). The production of NO and NO_2 in air mixture scales as universal function of the injected power, independently of the working regime (continuous or self-pulsing).

Lazzaroni, C.; Aubert, X.; Marinov, D.; Guaitella, O.; Stancu, G.; Welzel, S.; Pipa, A.; Ropcke, J.; Sadeghi, N.; Rousseau, A.

2008-07-01

343

Development of Micro Catalytic Combustor with Pt/Al2O3 Thin Films  

NASA Astrophysics Data System (ADS)

Catalytic combustion of butane in micro-scale conduits is investigated. Nano-porous alumina formed through anodic oxidation of aluminum is employed for the support of platinum catalyst. Combustion starts at 250°C, and a heat release rate up to 710MW/m3 is achieved in a 0.6mm ID tube. It is found that the surface reaction speed is a limiting factor for the overall reaction rate. A prototype silicon-based catalytic combustor is designed and fabricated using MEMS technologies. The Pt/alumina catalyst layer is successfully integrated onto a silicon microchannel, and a Pyrex lid is anodically bonded onto the Si substrate. It is found in a preliminary experiment that the MEMS combustor also works well, but gives somewhat smaller reaction rate due to the thinner catalytic layer.

Suzuki, Yuji; Saito, Joichi; Kasagi, Nobuhide

344

Hard and Soft Micro- and Nanofabrication: An Integrated Approach to Hydrogel Based Biosensing and Drug Delivery  

PubMed Central

We review efforts to produce microfabricated glucose sensors and closed loop insulin delivery systems. These devices function due to the swelling and shrinking of glucose-sensitive microgels that are incorporated into silicon-based microdevices. The glucose response of the hydrogel is due to incorporated phenylboronic acid (PBA) side chains. It is shown that in the presence of glucose, these polymers alter their swelling properties, either by ionization or by formation of glucose-mediated reversible crosslinks. Swelling pressures impinge on microdevice structures, leading either to a change in resonant frequency of a microcircuit, or valving action. Potential areas for future development and improvement are described. Finally, an asymmetric nano-microporous membrane, which may be integrated with the glucose sensitive devices, is described. This membrane, formed using photolithography and block polymer assembly techniques, can be functionalized to enhance its biocompatibility and solute size selectivity. The work described here features the interplay of design considerations at the supramolecular, nano, and micro scales.

Siegel, Ronald A.; Gu, Yuandong; Lei, Ming; Baldi, Antonio; Nuxoll, Eric E.; Ziaie, Babak

2010-01-01

345

Effect of materials for micro-electro-mechanical systems on PCR yield.  

PubMed

In this study we analyzed the surface properties of different silicon-based materials used for micro-electro-mechanical systems (MEMS) production, such as thermally grown silicon oxide, plasma-enhanced chemical vapor deposition (PECVD)-treated silicon oxide, reactive-ion etch (RIE)-treated silicon oxide, and Pyrex. Substrates were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to define the surface chemical and morphological properties, and by fluorescence microscopy to directly assess the absorption of the different polymerase chain reaction (PCR) components. By using microchips fabricated with the same materials we investigated their compatibility with PCR reactions, exploiting the use of different enzymes and reagents or proper surface treatments. We established the best conditions for DNA amplification in silicon/Pyrex microdevices depending on the type of device and fabrication method used and the quality of reagents, rather than on the passivation treatment or increment in standard Taq polymerase concentration. PMID:19455320

Potrich, Cristina; Lunelli, Lorenzo; Forti, Stefania; Vozzi, Diego; Pasquardini, Laura; Vanzetti, Lia; Panciatichi, Cristina; Anderle, Mariano; Pederzolli, Cecilia

2009-05-20

346

Neutralization of space charge on high-current low-energy ion beam by low-energy electrons supplied from silicon based field emitter arrays  

SciTech Connect

Neutralization of space charge on a high-current and low-energy ion beam was attempted to reduce the divergence with an aid of low-energy electrons supplied from silicon based field emitter arrays (Si-FEAs). An argon ion beam with the energy of 500 eV and the current of 0.25 mA was produced by a microwave ion source. The initial beam divergence and the emittance were measured at the entrance of the analysis chamber in order to estimate the intrinsic factors for beam divergence. The current density distribution of the beam after transport of 730 mm was measured by a movable Faraday cup, with and without electron supply from Si-FEAs. A similar experiment was performed with tungsten filaments as an electron source. The results indicated that the electron supply from FEA had almost the same effect as the thermionic filament, and it was confirmed that both electron sources can neutralize the ion beam.

Gotoh, Yasuhito; Tsuji, Hiroshi; Taguchi, Shuhei; Ikeda, Keita; Kitagawa, Takayuki; Ishikawa, Junzo; Sakai, Shigeki [Dept. of Electron. Sci. Eng., Kyoto Univ. Kyotodaigaku-Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan); Dept. of Electron. Information Eng., Chubu Univ., 1200, Matsumoto-cho, Kasugai, Aichi 487-8501 (Japan); Nissin Ion Equipment Co., Ltd., 575 Kuze-Tonoshiro-cho, Minami-ku, Kyoto 601-8502 (Japan)

2012-11-06

347

Rapid detection and identification of biological and chemical agents by immunoassay, gene probe assay and enzyme inhibition using a silicon-based biosensor.  

PubMed

A rapid biosensor assay procedure that utilizes biotin streptavidin mediated filtration capture onto nitrocellulose membrane, in conjunction with a silicon-based light-addressable potentiometric sensor (LAPS) was developed for detection and identification of biological and chemical threat agents. Sandwich immunoassays, nucleic acid hybridization assays and enzyme inhibition assays are described. For immunoassays, the lower limits of detection (LOD) per 100-microl sample were approximately 5 pg/ml for protein (Staphylococcal enterotoxin B), 2 ng/ml for virus (Newcastle disease virus), and 20 ng/ml for vegetative bacteria (Brucella melitensis). In a dual gene probe assay format, the LOD was 0.30 fmol (1.8 x 10(8) copies per 60-microl) of single stranded target DNA. Enzyme inhibition assays on the LAPS using acetylcholinesterase were able to detect soman and sarin in aqueous samples at 2 and 8 pg (100 and 600 pM), respectively. The assays were easy to perform and required a total time equal to the reaction period plus about 15 min for filtering, washing and sensing. The assay format is suitable for detection of a wide range of infectious and toxic substances. New assays can be developed and optimized readily, often within 1 or 2 days. PMID:10945454

Lee, W E; Thompson, H G; Hall, J G; Bader, D E

2000-01-01

348

Neutralization of space charge on high-current low-energy ion beam by low-energy electrons supplied from silicon based field emitter arrays  

NASA Astrophysics Data System (ADS)

Neutralization of space charge on a high-current and low-energy ion beam was attempted to reduce the divergence with an aid of low-energy electrons supplied from silicon based field emitter arrays (Si-FEAs). An argon ion beam with the energy of 500 eV and the current of 0.25 mA was produced by a microwave ion source. The initial beam divergence and the emittance were measured at the entrance of the analysis chamber in order to estimate the intrinsic factors for beam divergence. The current density distribution of the beam after transport of 730 mm was measured by a movable Faraday cup, with and without electron supply from Si-FEAs. A similar experiment was performed with tungsten filaments as an electron source. The results indicated that the electron supply from FEA had almost the same effect as the thermionic filament, and it was confirmed that both electron sources can neutralize the ion beam.

Gotoh, Yasuhito; Tsuji, Hiroshi; Taguchi, Shuhei; Ikeda, Keita; Kitagawa, Takayuki; Ishikawa, Junzo; Sakai, Shigeki

2012-11-01

349

13C NMR, micro-FTIR and fluorescence spectra, and pyrolysis-gas chromatograms of coalified foliage of late Carboniferous medullosan seed ferns, Nova Scotia, Canada: Implications for coalification and chemotaxonomy  

Microsoft Academic Search

The cuticles and cuticle-free compressions of three Carboniferous medullosan seed-fern leaf species (Macroneuropteris scheuchzeri, Neuropteris ovata var. simonii and Alethopteris lesquereuxii) were analyzed by elemental, 13C nuclear magnetic resonance (NMR), micro-FTIR (Fourier transform infrared) and coal petrographic techniques. The 13C NMR spectra of the cuticle-free compressions and the associated whole coal (high volatile A\\/B bituminous coal rank) are generally similar

Paul C Lyons; William H Orem; Maria Mastalerz; Erwin L Zodrow; Angelika Vieth-Redemann; R. Marc Bustin

1995-01-01

350

Tolerance compensation in micro-optics  

NASA Astrophysics Data System (ADS)

In contrast to microelectronics which may be considered two-dimensional in first approximation, micro-optical systems extend over three dimensions. Due to the lack of a uniform material system, complex micro-optical systems are constructed using a modular concept. The modular setup of such hybrid systems results in an isolated manufacture of the individual components and their later assembly in a single system. Designing a micro-optical system, all relevant requirements and constraints defined by the manufacturing processes and the application of the system in a real ambience must be considered. Furthermore, every individual manufacturing step adds its own tolerances to the system. To maintain the overall function of a system under the given manufacturing conditions, the system design has to be robust with respect to the expected tolerances. The system's robustness will result from considering process knowledge in the state of modeling already. Process knowledge of non-silicate manufacturing processes is collected and stored in a knowledge database. On basis of these data, process-dependent inaccuracies and tolerances can be used to design robust functional components and functional units (subsystems). This approach of robust, tolerance compensating design is applied to the design of an infrared gas sensor, a micro-optical distance sensor, and a lens of variable refraction power.

Sieber, I.; Dickerhof, M.; Schmidt, A.

2009-08-01

351

Fabrication of micro gear by micro powder injection molding  

Microsoft Academic Search

Micro components made from polymers can be easily processed but they may not be suitable for all applications. One example\\u000a is where good mechanical properties are required. Thus, the fabrication of micro components from non-polymeric materials such\\u000a as metals and ceramics is essential. In this paper, the fabrication of 316L stainless steel micro gear by micro powder injection\\u000a molding is

N. H. Loh; S. B. Tor; B. Y. Tay; Y. Murakoshi; R. Maeda

2008-01-01

352

Micro-meso-macro  

Microsoft Academic Search

Building on the ontology of evolutionary realism recently proposed by Dopfer and Potts (forthcoming), we develop an analytical framework for evolutionary economics with a micro-meso-macro architecture. The motive for reconception is to make clear the highly complex and emergent nature of existence and change in economic evolution. For us, the central insight is that an economic system is a population

Kurt Dopfer; John Foster; Jason Potts

2004-01-01

353

Multistage thermoelectric micro coolers  

Microsoft Academic Search

Multistage thermoelectric coolers have been used for a long time because they offer a larger temperature difference than single stage thermoelectric coolers. MEMS technology leads to the possibility to fabricate multistage thermoelectric micro coolers in batches without much increase in complexity compared to single stage cooler fabrication. In this paper, we discuss the design of multistage thermoelectric coolers to optimize

Ronggui Yang; C. Gang; G. J. Snyder; J.-P. Fleurial

2002-01-01

354

Micro cutting in the micro lathe turning system  

Microsoft Academic Search

As an application of cutting for the manufacture of micro mechanical parts and as a trial of the development of a miniature machining system matching the micro size of the work piece, a micro lathe turning system has been developed. A work material 0.3 mm in diameter is clamped and cut to a minimum of 10 ?m in diameter with

Zinan Lu; Takeshi Yoneyama

1999-01-01

355

Nanoporous Silicon Based Energetic Materials.  

National Technical Information Service (NTIS)

Energetic materials are an important component of military defense systems and are used in applications ranging from explosives to gun and missile propulsion. Energetic materials are used in a number of critical defense components ranging from shaped char...

D. Kapoor P. Redner S. Limaye S. Subramanian T. Tiegs

2008-01-01

356

Stretchable Micro-Electrode Array.  

National Technical Information Service (NTIS)

This paper focuses on the design consideration, fabrication processes and preliminary testing of the stretchable micro-electrode array. We are developing an implantable, stretchable micro-electrode array using polymer-based microfabrication techniques. Th...

M. Maghribi J. Hamilton D. Polka K. Rose T. Wilson P. Krulevitch

2002-01-01

357

Micro teleoperation with haptic interface  

Microsoft Academic Search

In this paper, we discuss about micro teleoperation with haptic interfaces. We developed the micro teleoperation systems for micro tasks, such as assembly or manufacturing. We will show about structure of master\\/slave manipulators, its control and experimental results of teleoperation with these manipulators in this paper. We introduce the haptic interface that give operators the presence as if he\\/she touches

N. Ando; M. Ohta; H. Hashimoto

2000-01-01

358

Micro teleoperation with parallel manipulator  

Microsoft Academic Search

In this paper, we discuss about micro teleoperation with haptic interfaces. We developed the micro teleoperation systems for micro tasks, such as assembly or manufacturing. We show about structure of master\\/slave manipulators, its control and experimental results of teleoperation with the manipulators in this paper. We introduce the haptic interface that provides operators the sense as if he\\/she touches the

Noriaki ANDO; Masahito OHTA; H. Hashimoto

2000-01-01

359

Micro-structured electrode arrays: atmospheric pressure plasma processes and applications  

Microsoft Academic Search

Micro-structured electrode (MSE) arrays allow to generate large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode dimensions in the micro-range realized by means of modern micro-machining and galvanic techniques are small enough to generate sufficiently high electric field strengths to ignite gas discharges applying only moderate radio frequency (13.56 MHz) voltages (80–390 V in

L. Baars-Hibbe; P. Sichler; C. Schrader; C. Geßner; K.-H. Gericke; S. Büttgenbach

2003-01-01

360

The effect of nozzle design on laser micro-machining of M2 tool steels  

Microsoft Academic Search

This paper shows how computational techniques have been used to develop axi-symmetric, straight, sonic-line, minimum length micro nozzles that are suitable for laser micro-machining applications. Gas jets are used during laser micro-machining processing applications to shield the interaction zone between laser and workpiece material, and they determine the machining efficiency of such applications. The paper discusses the nature of laser–material

M. J. Jackson; G. M. Robinson; M. D. H. Gill; W. O’Neill

2005-01-01

361

Effects of choking on flow and heat transfer in micro-channels  

Microsoft Academic Search

The gas flows through micro-channels are encountered in many engineering applications such as the cooling devices of electronic chips, semiconductors, micro-electro-mechanical systems (MEMS), etc. Many works have been performed to investigate the flow and heat transfer characteristics generally occurring in the micro channels. According to these investigations, the majority of heat was transferred in the entrance region of the channel,

Vincent Lijo; Heuy Dong Kim; Toshiaki Setoguchi

362

Micros in geoscience libraries  

SciTech Connect

Microcomputers in geoscience libraries provide efficiency in record keeping; printing of labels; compiling and printing of: monthly acquisition lists, up-to-date theses-dissertation listing; periodical/serial listing as well as providing fast access to bibliographic information on specific topics via in-house data bases. The Pirtle Geology Library, University of Kentucky has three microcomputers, a Radio Shack TRS-80, Model 12 and two Digital Rainbow 100's. The micros have proven efficient for internal projects, saving materials and staff time. Externally, patrons are pleased with the fast retrieval of up-to-date geoscience information and with the speedy access to the specific subject data bases. This paper will describe the time saving projects which can be performed on the micros as well as explain the problems of creating original data bases for access to geoscience bibliographic references.

Hall, V.S.

1985-01-01

363

Micro-Geomechanics  

NSDL National Science Digital Library

This paper discusses the neglect of micro-mechanics in soil mechanics, and seeks to establish a role that will benefit both the research worker and the practitioner. In support of the mathematical construct of "plasticity", micro-mechanics introduces observations of grain crushing and re-arrangement. Not only does this help to explain the dimensionally inconsistent concept of the normal compression line, it goes some way to unifying our understanding ofsands and clays. Indeed, bridging the grain-continuum duality is the key to raising the confidence of practitioners both in the meaningfulness of certain constitutive modeling parameters and in the scaling rules applied to the behavior of small scale physical models.

Bolton, M. D.; Cheng, Y. P.

2008-07-31

364

An electromagnetic micro dynamometer  

Microsoft Academic Search

Performance of a planar magnetic VR micromotor is evaluated using an electromagnetically controlled load and planar gear coupling. Fabrication is based on extended LIGA processing methods. A new coil construction technique is described which uses wound micro-coils on a LIGA defined pre-fonn. A maximum rotational speed of 17,500 rpm is achieved for a 1000 pm diameter rotor with a maximum

T. R. Christenson; J. Klein; H. Guckel

1995-01-01

365

Micro-fluidic interconnect  

Microsoft Academic Search

An apparatus for simultaneously aligning and interconnecting microfluidic ports is presented. Such interconnections are required to utilize microfluidic devices fabricated in Micro-Electromechanical-Systems (MEMS) technologies, that have multiple fluidic access ports (e.g. 100 micron diameter) within a small footprint, (e.g. 3 mm.times.6 mm). Fanout of the small ports of a microfluidic device to a larger diameter (e.g. 500 microns) facilitates packaging

Murat Okandan; Paul C. Galambos; Gilbert L. Benavides; Dale L. Hetherington

2006-01-01

366

Micro borehole drilling platform  

SciTech Connect

This study by CTES, L.C. meets two main objectives. First, evaluate the feasibility of using coiled tubing (CT) to drill 1.0 inches-2.5 inches diameter directional holes in hard rocks. Second, develop a conceptual design for a micro borehole drilling platform (MBDP) meeting specific size, weight, and performance requirements. The Statement of Work (SOW) in Appendix A contains detailed specifications for the feasibility study and conceptual design.

NONE

1996-10-01

367

Scanning micro-sclerometer  

DOEpatents

A scanning micro-sclerometer measures changes in contact stiffness and correlates these changes to characteristics of a scratch. A known force is applied to a contact junction between two bodies and a technique employing an oscillating force is used to generate the contact stiffness between the two bodies. As the two bodies slide relative to each other, the contact stiffness changes. The change is measured to characterize the scratch.

Oliver, Warren C. (Knoxville, TN); Blau, Peter J. (Oak Ridge, TN)

1994-01-01

368

Scanning micro-sclerometer  

DOEpatents

A scanning micro-sclerometer measures changes in contact stiffness and correlates these changes to characteristics of a scratch. A known force is applied to a contact junction between two bodies and a technique employing an oscillating force is used to generate the contact stiffness between the two bodies. As the two bodies slide relative to each other, the contact stiffness changes. The change is measured to characterize the scratch. 2 figs.

Oliver, W.C.; Blau, P.J.

1994-11-01

369

Polymer Micro-scrolls  

Microsoft Academic Search

This research focuses on the spontaneous formation of geometric structures of Au-coated crosslinked polydimethylsiloxane (PDMS) films. The Au-PDMS bilayer is fabricated on a rigid glass substrate that is pre-coated with a sacrificial layer of polyacrylic acid (PAA). Upon dissolution of the PAA, micro-scale, equilibrated structures are formed in a water bath due to a residual stress in the bi-layer film.

Kyriaki Kalaitzidou; Alfred J. Crosby

2007-01-01

370

Quantitative micro-CT  

NASA Astrophysics Data System (ADS)

Micro-CT for bone structural analysis has progressed from an in-vitro laboratory technique to devices for in-vivo assessment of small animals and the peripheral human skeleton. Currently, topological parameters of bone architecture are the primary goals of analysis. Additional measurement of the density or degree of mineralization (DMB) of trabecular and cortical bone at the microscopic level is desirable to study effects of disease and treatment progress. This information is not commonly extracted because of the challenges of accurate measurement and calibration at the tissue level. To assess the accuracy of micro-CT DMB measurements in a realistic but controlled situation, we prepared bone-mimicking watery solutions at concentrations of 100 to 600 mg/cm3 K2PO4H and scanned them with micro-CT, both in glass vials and microcapillary tubes with inner diameters of 50, 100 and 150 ?m to simulate trabecular thickness. Values of the linear attenuation coefficients ? in the reconstructed image are commonly affected by beam hardening effects for larger samples and by partial volume effects for small volumes. We implemented an iterative reconstruction technique to reduce beam hardening. Partial voluming was sought to be reduced by excluding voxels near the tube wall. With these two measures, improvement on the constancy of the reconstructed voxel values and linearity with solution concentration could be observed to over 90% accuracy. However, since the expected change in real bone is small more measurements are needed to confirm that micro-CT can indeed be adapted to assess bone mineralization at the tissue level.

Prevrhal, Sven

2005-09-01

371

Autonomous, agile micro-satellites and supporting technologies  

SciTech Connect

This paper updates the on-going effort at Lawrence Livermore National Laboratory to develop autonomous, agile micro-satellites (MicroSats). The objective of this development effort is to develop MicroSats weighing only a few tens of kilograms, that are able to autonomously perform precision maneuvers and can be used telerobotically in a variety of mission modes. The required capabilities include satellite rendezvous, inspection, proximity-operations, docking, and servicing. The MicroSat carries an integrated proximity-operations sensor-suite incorporating advanced avionics. A new self-pressurizing propulsion system utilizing a miniaturized pump and non-toxic mono-propellant hydrogen peroxide was successfully tested. This system can provide a nominal 25 kg MicroSat with 200-300 m/s delta-v including a warm-gas attitude control system. The avionics is based on the latest PowerPC processor using a CompactPCI bus architecture, which is modular, high-performance and processor-independent. This leverages commercial-off-the-shelf (COTS) technologies and minimizes the effects of future changes in processors. The MicroSat software development environment uses the Vx-Works real-time operating system (RTOS) that provides a rapid development environment for integration of new software modules, allowing early integration and test. We will summarize results of recent integrated ground flight testing of our latest non-toxic pumped propulsion MicroSat testbed vehicle operated on our unique dynamic air-rail.

Breitfeller, E; Dittman, M D; Gaughan, R J; Jones, M S; Kordas, J F; Ledebuhr, A G; Ng, L C; Whitehead, J C; Wilson, B

1999-07-19

372

Methods and systems for micro bearings  

DOEpatents

A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

Stalford, Harold L.

2012-10-09

373

Micro Turbines from the Standpoint of Potential Users  

Microsoft Academic Search

This paper describes some micro turbine aspects from the standpoint of potential users. First, some of the pros and the cons of small gas turbines compared to other competing technologies are given. The discussed aspects are mainly focussed on technical advantages and disadvantages as it is hard to predict how fast and to what extent the different technologies (including that

Ir Roland Decuypere; Dries Verstraete

2005-01-01

374

Simulation studies of RF excited micro-cavity discharges for micro-propulsion applications  

NASA Astrophysics Data System (ADS)

A detailed computational modelling study of the micro-cavity discharge (MCD) thruster is presented. The MCD thruster concept incorporates a microdischarge with dielectric covered electrodes operated using alternating current (ac) excitation. The thruster geometry comprises a constant area pipe section followed by a divergent micro-nozzle. Two ring electrodes are embedded in the wall of the pipe section with the downstream electrode close to the pipe-micronozzle intersection. A microdischarge plasma is generated in argon propellant gas flowing through the thruster. A detailed plasma dynamics model coupled with the compressible Navier-Stokes equations is used to study the flow and plasma phenomenon in the thruster. Results show a highly pulsed microdischarge with plasma densities of ˜1019 m-3 and current densities ˜700 mA cm-2 for an ac excitation in the radio frequency (RF) regime of 10 and 20 MHz. The dominant gas heating mechanism in these discharges is through ion Joule heating. Higher electron densities and spatially dominant thermal source terms are observed for the 20 MHz excitation compared with 10 MHz excitation. The addition of 20% nitrogen to the flow resulted in much better performance compared with the pure argon cases. A peak gas temperature rise ˜200 K is seen for a cycle-averaged power deposition of 76 mW. For the conditions explored in this study, the overall specific impulse of the thruster operating with the microdischarge plasma is found to be about 25% higher than a corresponding cold gas case.

Sitaraman, H.; Raja, L. L.

2012-05-01

375

Performance analysis and design optimization of micro-jet impingement heat sink  

NASA Astrophysics Data System (ADS)

This study evaluated a silicon-based micro-jet impingement heat sink for electronic cooling applications. First, the pressure-drop and thermal characteristics were investigated for steady incompressible and laminar flow by solving three-dimensional Navier-Stokes equations, and the performance enhancement was carried out through parametric and optimization studies. Several parallel and staggered micro-jet configurations consisting of a maximum of 16 jet impingements were tested. The effectiveness of the micro-jet configurations, i.e. inline 2 × 2, 3 × 3 and 4 × 4 jets, and staggered 5-jet and 13-jet arrays with nozzle diameters 50, 76, and 100 ?m, were analyzed at various flow rates for the maximum temperature-rise and pressure-drop characteristics. A design with a staggered 13-jet array showed the best performance among the various configurations investigated in the present study. The design optimization based on three-dimensional numerical analysis, surrogate modeling and a multi-objective evolutionary algorithm were carried out to understand the thermal resistance and pumping power correlation of the micro-jet impingement heat sink. Two design variables, the ratio of height of the channel and nozzle diameter, and the ratio of nozzle diameter and interjet spacing, were chosen for design optimization. The global Pareto-optimal front was achieved for overall thermal resistance and required pumping power of the heat sink. The Pareto-optimal front revealed existing correlation between pumping power and thermal resistance of the heat sink. Of the range of Pareto-optimal designs available, some representative designs were selected and their functional relationships among the objective functions and design variables were examined to understand the Pareto-optimal sensitivity and optimal design space. A minimum of 66 °C of maximum-temperature-rise was obtained for a heat flux of 100 W/cm2 at a pressure drop of about 24 kPa.

Husain, Afzal; Kim, Sun-Min; Kim, Kwang-Yong

2013-11-01

376

Advanced Micro Turbine System (AMTS) -C200 Micro Turbine -Ultra-Low Emissions Micro Turbine  

SciTech Connect

In September 2000 Capstone Turbine Corporation commenced work on a US Department of Energy contract to develop and improve advanced microturbines for power generation with high electrical efficiency and reduced pollutants. The Advanced MicroTurbine System (AMTS) program focused on: (1) The development and implementation of technology for a 200 kWe scale high efficiency microturbine system (2) The development and implementation of a 65 kWe microturbine which meets California Air Resources Board (CARB) emissions standards effective in 2007. Both of these objectives were achieved in the course of the AMTS program. At its conclusion prototype C200 Microturbines had been designed, assembled and successfully completed field demonstration. C65 Microturbines operating on natural, digester and landfill gas were also developed and successfully tested to demonstrate compliance with CARB 2007 Fossil Fuel Emissions Standards for NOx, CO and VOC emissions. The C65 Microturbine subsequently received approval from CARB under Executive Order DG-018 and was approved for sale in California. The United Technologies Research Center worked in parallel to successfully execute a RD&D program to demonstrate the viability of a low emissions AMS which integrated a high-performing microturbine with Organic Rankine Cycle systems. These results are documented in AMS Final Report DOE/CH/11060-1 dated March 26, 2007.

Capstone Turbine Corporation

2007-12-31

377

Femtosecond laser polymerization of hybrid/integrated micro-optical elements and their characterization  

NASA Astrophysics Data System (ADS)

The femtosecond laser-induced multi-photon polymerization of a zirconium-silicon based sol-gel photopolymer was employed for the fabrication of a series of micro-optical elements with single and combined optical functions: convex and Fresnel lenses, gratings, solid immersion lenses on a glass slide and on the tip of an optical fiber. The microlenses were produced as polymer caps of varying radii from 10 to 90 µm. The matching of refractive indices between the polymer and substrate was exploited for the creation of composite glass-resist structures which functioned as single lenses. Using this principle, solid immersion lenses were fabricated and their performance demonstrated. The magnification of the composite solid immersion lenses corresponded to the calculated values. The surface roughness of the lenses was below ~ 30 nm, acceptable for optical applications in the visible range. In addition, the integration of micro-optical elements onto the tip of an optical fiber was demonstrated. To increase the efficiency of the 3D laser polymerization, the lenses were formed by scanning only the outer shell and polymerizing the interior by exposure to UV light.

Malinauskas, Mangirdas; Žukauskas, Albertas; Purlys, Vytautas; Belazaras, Kastytis; Momot, Andrej; Paipulas, Domas; Gadonas, Roaldas; Piskarskas, Algis; Gilbergs, Holger; Gaidukevi?i?t?, Arun?; Sakellari, Ioanna; Farsari, Maria; Juodkazis, Saulius

2010-12-01

378

Micro Bunches Workshop Proceedings  

SciTech Connect

These proceedings represent papers presented at the Micro Bunches Workshop held at the Brookhaven National Laboratory. The workshop was sponsored by the U.S. Department of Energy. The topics discussed include new technologies for producing short bunches such as RF electron guns with laser driven photocathodes in linacs and storage rings. The workshop was organized to gather researchers in the production of short bunches in electron linacs and storage rings together with the users of coherent radiation. There were 53 papers presented at the workshop and 51ave been abstracted for the Energy Science and Technology database.(AIP)

Blum, E.; Dienes, M.; Murphy, J. [Brookhaven National Laboratory, Upton, NY 11973 (United States)

1996-07-01

379

Electrochemical micro sensor  

DOEpatents

A micro-amperometric electrochemical sensor for detecting the presence of a pre-determined species in a fluid material is disclosed. The sensor includes a smooth substrate having a thin coating of solid electrolytic material deposited thereon. The working and counter electrodes are deposited on the surface of the solid electrolytic material and adhere thereto. Electrical leads connect the working and counter electrodes to a potential source and an apparatus for measuring the change in an electrical signal caused by the electrochemical oxidation or reduction of the species. Alternatively, the sensor may be fabricated in a sandwich structure and also may be cylindrical, spherical or other shapes.

Setter, Joseph R. (Naperville, IL); Maclay, G. Jordan (Maywood, IL)

1989-09-12

380

MICRO TUTOR PRODUCTS  

NSDL National Science Digital Library

MICRO TUTOR PRODUCTS announces the first formal course designed to give teachers all the expertise they need to put their class on a MOO. Beginning with 'What is a MOO?', the course assumes no previous MOO experience, yet soon each student will be creating MOO objects, designing their online classrooms, and even doing just a little MOO programming. Completion of the course assignments, as well as a personal design-and-application Project, will result in the awarding of a course certificate for the student's permanent resume. More information, as well as registration details, can be found at:

381

Micro-fluidic interconnect  

SciTech Connect

An apparatus for simultaneously aligning and interconnecting microfluidic ports is presented. Such interconnections are required to utilize microfluidic devices fabricated in Micro-Electromechanical-Systems (MEMS) technologies, that have multiple fluidic access ports (e.g. 100 micron diameter) within a small footprint, (e.g. 3 mm.times.6 mm). Fanout of the small ports of a microfluidic device to a larger diameter (e.g. 500 microns) facilitates packaging and interconnection of the microfluidic device to printed wiring boards, electronics packages, fluidic manifolds etc.

Okandan, Murat (Albuquerque, NM); Galambos, Paul C. (Albuquerque, NM); Benavides, Gilbert L. (Los Ranchos, NM); Hetherington, Dale L. (Albuquerque, NM)

2006-02-28

382

Micro-column plasma emission liquid chromatograph  

DOEpatents

In a direct current plasma emission spectrometer for use in combination with a micro-column liquid chromatograph, an improved plasma source unit. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

Gay, Don D. (Aiken, SC)

1984-01-01

383

Zinc oxide micro-spheres with faceted surfaces produced by laser ablation of zinc targets  

NASA Astrophysics Data System (ADS)

We report the fabrication of ZnO micro-spheres using high-power laser ablation of Zn metal in the presence of oxygen gas background without use of any catalysts or additives. The centre-symmetric geometrical structures of ZnO micro-spheres exhibit clear pentagonal and hexagonal facets with different sizes. A discussion of the growth mechanisms based on a model of subsurface micro-explosion boiling followed by laser-surface sintering of assembled particles has been proposed to explain the formation of the ZnO micro-spheres.

Chen, Ming; Liu, Xiangdong; Liu, Yuehua; Zhao, Mingwen

2012-05-01

384

Mechano-micro\\/nano systems  

Microsoft Academic Search

In recent years, the researches about Micro\\/Nano Systems are down actively in the bio-medical research fields, DNA research fields, chemical analysis systems fields, etc. In the results, a new materials and new functions in the systems are developed. In this invited paper, Mechano-Micro\\/Nano Systems, especially, motion systems are introduced. First, the research activities concerning the Mechano-Micro\\/Nano Systems in the world(MST2003,

Mikio Horie

2004-01-01

385

Concentric micro-nebulizer for direct sample insertion  

DOEpatents

A concentric micro-nebulizer and method for introducing liquid samples into a plasma established in a plasma torch including a first tube connected to a source of plasma gas. The concentric micro-nebulizer has inner and outer concentric tubes extending upwardly within the torch for connection to a source of nebulizer gas and to a source of liquid solvent and to a source of sample liquid. The inner tube is connected to the source of liquid solvent and to the source of sample liquid and the outer tube is connected to the source of nebulizer gas. The outer tube has an orifice positioned slightly below the plasma when it is established, with the inner and outer tubes forming an annulus therebetween with the annular spacing between the tubes at said orifice being less than about 0.05mm. The dead volume of the inner tube is less than about 5 microliters.

Fassel, V.A.; Rice, G.W.; Lawrence, K.E.

1984-03-06

386

Concentric micro-nebulizer for direct sample insertion  

DOEpatents

A concentric micro-nebulizer and method for introducing liquid samples into a plasma established in a plasma torch including a first tube connected to a source of plasma gas. The concentric micro-nebulizer has inner and outer concentric tubes extending upwardly within the torch for connection to a source of nebulizer gas and to a source of liquid solvent and to a source of sample liquid. The inner tube is connected to the source of liquid solvent and to the source of sample liquid and the outer tube is connected to the source of nebulizer gas. The outer tube has an orifice positioned slightly below the plasma when it is established, with the inner and outer tubes forming an annulus therebetween with the annular spacing between the tubes at said orifice being less than about 0.05 mm. The dead volume of the inner tube is less than about 5 microliters.

Fassel, Velmer A. (Ames, IA); Rice, Gary W. (Nevada, IA); Lawrence, Kimberly E. (Ames, IA)

1986-03-11

387

Micro stereo lithography for 3D MEMS devices  

NASA Astrophysics Data System (ADS)

Micro Stereo Lithography (MSL) is a poor man's LIGA for fabricating high aspect ratio MEMS devices in UV curable semiconducting polymers using either two computer-controlled low inertia galvanometric mirrors with the aid of focusing lens or an array of optical fibers. This technique has also been successfully used recently for fabricating 3D metallic and ceramic MEMS devices. Microfabrication techniques such as bulk micromachining and surface micromachining currently employed to conceive MEMS are largely derived from the standard IC and microelectronics technology. Even though many MEMS devices with integrated electronics have been achieved by using the traditional micromachining techniques, some limitations have nevertheless to be underlined: (1) these techniques are very expensive and need specific installations as well as a cleanroom environment, (2) the materials that can be used up to now are restricted to silicon and metals, (3) the manufacture of 3D parts having curved surfaces or an important number of layers is not possible. Moreover, for some biological applications, the materials used for sensors must be compatible with human body and the actuators need to have high strain and displacement which the current silicon based MEMS do not provide. It is thus natural for the researchers to 'look' for alternative methods to make 3D sensors and actuators using polymeric based materials. For MSL techniques to be successful as their silicon counterparts, one has to come up with multifunctional polymers. These multifunctional polymers have not only a high sensing capability but also a high strain and actuation performance. With the invention of organic thin film transistor, now it seems possible to fabricate polymeric based MEMS devices with built-in- electronics. Moreover, with combined architecture techniques, one can integrate silicon devices with the polymeric ones without much difficulty. In this paper, the applications of MSL for polymer and ceramic based microstructures and MEMS are discussed with some examples.

Varadan, Vijay K.; Varadan, Vasundara V.

2001-08-01

388

Measurement of micro Bubbles generated by a pressurized dissolution method  

NASA Astrophysics Data System (ADS)

Diameters of micro-bubbles are apt to range from about one mm to several-hundred mm, and therefore, it is difficult to measure a correct diameter distribution using a single measurement method. In this study, diameters of bubbles generated by a pressurized dissolution method are measured by using phase Doppler anemometry (PDA) and an image processing method, which is based on the Sobel filter and Hough transform. The diameter distribution and the Sauter mean diameter of micro bubbles are evaluated based on the diameters measured by both methods. Experiments are conducted for several mass flow rates of dissolved gas and of air bubbles entrained in the upstream of the decompression nozzle to examine effects of the entrained bubbles on bubble diameter. As a result, the following conclusions are obtained: (1) Diameter distribution of micro bubbles can be accurately measured for a wide range of diameter by using PDA and the image processing method. (2) The mean diameter of micro-bubbles generated by gasification of dissolved gas is smaller than that generated by breakup of air bubbles entrained in the upstream of the decompression nozzle. (3) The mean bubble diameter increases with the entrainment of air bubbles in the upstream of the decompression nozzle at a constant mass flow rate of dissolved gas.

Hosokawa, S.; Tanaka, K.; Tomiyama, A.; Maeda, Y.; Yamaguchi, S.; Ito, Y.

2009-02-01

389

A micro surface tension pump (MISPU) in a glass microchip.  

PubMed

A non-membrane micro surface tension pump (MISPU) was fabricated on a glass microchip by one-step glass etching. It needs no material other than glass and is driven by digital gas pressure. The MISPU can be seen working like a piston pump inside the glass microchip under a microscope. The design of the valves (MISVA) and pistons (MISTON) was based on the surface tension theory of the micro surface tension alveolus (MISTA). The digital gas pressure controls the moving gas-liquid interface to open or close the input and output MISVAs to refill or drive the MISTON for pumping a liquid. Without any moving parts, a MISPU is a kind of long-lasting micro pump for micro chips that does not lose its water pumping efficiency over a 20-day period. The volumetric pump output varied from 0 to 10 nl s(-1) when the pump cycle time decreased from 5 min to 15 s. The pump head pressure was 1 kPa. PMID:20957289

Peng, Xing Yue Larry

2010-10-19

390

Automated headspace-solid-phase micro extraction-retention time locked-isotope dilution gas chromatography-mass spectrometry for the analysis of organotin compounds in water and sediment samples.  

PubMed

An automated method for the simultaneous determination of six important organotin compounds namely monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPhT), diphenyltin (DPhT) and triphenyltin (TPhT) in water and sediment samples is described. The method is based on derivatization with sodium tetraethylborate followed by automated headspace-solid-phase micro extraction (SPME) combined with GC-MS under retention time locked (RTL) conditions. Home-synthesized deuterated organotin analogues were used as internal standards. Two high abundant fragment ions corresponding to the main tin isotopes Sn118 and Sn120 were chosen; one for quantification and one as qualifier ion. The method was validated and excellent figures of merit were obtained. Limits of quantification (LOQs) are from 1.3 to 15 ng l(-1) (ppt) for water samples and from 1.0 to 6.3 microg kg(-1) (ppb) for sediment samples. Accuracy for sediment samples was tested on spiked real-life sediment samples and on a reference PACS-2 marine harbor sediment. The developed method was used in a case-study at the harbor of Antwerp where sediment samples in different areas were taken and subsequently screened for TBT contamination. Concentrations ranged from 15 microg kg(-1) in the port of Antwerp up to 43 mg kg(-1) near a ship repair unit. PMID:16038329

Devosa, Christophe; Vliegen, Maarten; Willaert, Bart; David, Frank; Moens, Luc; Sandra, Pat

2005-06-24

391

An Experimental Study on the Fabrication of Glass-based Acceleration Sensor Body Using Micro Powder Blasting Method  

PubMed Central

This study investigated the feasibility of the micro powder blasting technique for the micro fabrication of sensor structures using the Pyrex glass to replace the existing silicon-based acceleration sensor fabrication processes. As the preliminary experiments, the effects of the blasting pressure, the mass flow rate of abrasive and the number of nozzle scanning times on erosion depth of the Pyrex and the soda lime glasses were examined. From the experimental results, optimal blasting conditions were selected for the Pyrex glass machining. The dimensions of the designed glass sensor was 1.7×1.7×0.6mm for the vibrating mass, and 2.9×0.7×0.2mm for the cantilever beam. The machining results showed that the dimensional errors of the machined glass sensor ranged from 3 ?m in minimum to 20 ?m in maximum. These results imply that the micro powder blasting method can be applied for the micromachining of glass-based acceleration sensors to replace the exiting method.

Park, Dong-Sam; Yun, Dae-Jin; Cho, Myeong-Woo; Shin, Bong-Cheol

2007-01-01

392

Formation of titanium carbide coating with micro-porous structure  

NASA Astrophysics Data System (ADS)

Micro-porous titanium carbide coating was successfully synthesized in a vacuum gas carburizing furnace by using a sequential diffusion technology. The composition and structure of the as-synthesized TiC were examined by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and glow discharge mass spectrometry (GDMS), and scanning electron microscopy (SEM). All of the XRD, XPS and GDMS analysis results indicate that carbon atoms effectively diffused into the titanium alloys and formed a uniform acicular TiC coating with micro-porous structure.

Luo, Yong; Ge, Shirong; Jin, Zhongmin; Fisher, John

2010-03-01

393

Infrared micro-optics technologies  

NASA Astrophysics Data System (ADS)

Bodenseewerk GmbH generally works on challenging projects comprising Microsystems, e.g. micro-optics (micro-lenses, micro-mirrors). We utilize state-of-the-art laboratory equipment and simulation software (e.g. optical design with ZEMAX, ASAP and GLAD). Our recent activities on the development of several infrared micro-optical devices focus on high speed imaging of scenes with high angular resolution including the analysis of physical properties of the detected light (e.g. spectral content, polarization) utilizing staring IR sensors with focal-plane-arrays operating in a snap shot mode at high frame rates. We report about the development of so called micro-optical multiplexers which: (a) comprise micro-optical arrays and electro-mechanical micro-actuators, (b) image several fields of view with high resolution onto a single focal-plane-array, (c) image several fields of view with enhanced spatial resolution [by the factor of four compared to (b)] in a modified realization onto one focal-plane-array and (d) analyze the spectral content of an image using a single-band photon detector-array and multi-frame processing. The micro-opto-electro-mechanical multiplexer (MOEM) systems all consist of a primary objective, a MOEM image-steering respectively image coding device and a secondary objective. The primary objective images one or more suitable formed individual fields of view onto a common intermediate image plane. The MOEM devices comprise combinations of focusing and defocusing micro-lens-arrays, micro-shutter-arrays and micro-filter-arrays which are mounted parallel to each other near the intermediate image plane. The MOEM devices exhibit their above mentioned function modes by laterally displacing the micro-arrays with the help of modern micro-actuators. The secondary objective is utilized as relay optical stage. A modern common focal-plane-array is used as detector device. The micro-actuators responsible for the relative displacement of the micro-arrays are highly miniaturized while maintaining large displacement ranges and high linearity, reproducable positioning and reliability. This paper outlines the general sensor concept, explains the underlying principles and delineates the optical systems layout. Recent hardware realizations useful in military applications concerning image and laser beam steering are presented.

Krogmann, Dirk; Tholl, Hans D.

2004-08-01

394

FUEL CELL/MICRO-TURBINE COMBINED CYCLE  

SciTech Connect

A wide variety of conceptual design studies have been conducted that describe ultra-high efficiency fossil power plant cycles. The most promising of these ultra-high efficiency cycles incorporate high temperature fuel cells with a gas turbine. Combining fuel cells with a gas turbine increases overall cycle efficiency while reducing per kilowatt emissions. This study has demonstrated that the unique approach taken to combining a fuel cell and gas turbine has both technical and economic merit. The approach used in this study eliminates most of the gas turbine integration problems associated with hybrid fuel cell turbine systems. By using a micro-turbine, and a non-pressurized fuel cell the total system size (kW) and complexity has been reduced substantially from those presented in other studies, while maintaining over 70% efficiency. The reduced system size can be particularly attractive in the deregulated electrical generation/distribution environment where the market may not demand multi-megawatt central stations systems. The small size also opens up the niche markets to this high efficiency, low emission electrical generation option.

Larry J. Chaney; Mike R. Tharp; Tom W. Wolf; Tim A. Fuller; Joe J. Hartvigson

1999-12-01

395

Methods and systems for positioning micro elements  

DOEpatents

A micro device may comprise a substrate, a first micro structure coupled to the substrate, a second micro structure coupled to the substrate, and port configured to receive an input. The first micro structure is configured to move into engagement with the second micro structure in response to the input.

Stalford; Harold L. (Norman, OK)

2012-03-13

396

MICRO AIR VEHICLE SURVEILLANCE PLATFORM  

Microsoft Academic Search

This paper discusses the design and development of a Micro Air Vehicle (MAV) platform focusing on aerodynamic design; material durability and precision; and propulsion system integration. The purpose of the MAV is to compete in the surveillance mission at the 2006 International Micro Air Vehicle Competition (IMAVC). A low Reynolds number airfoil and planform was designed and validated through wind

Michael Koelemay; Andrew Streett; Michael Reid; Shane Healey; Matteo Blanc; Joe Calandro; Josh Joseph; John Lemmon; Adam Gillis

2006-01-01

397

A Reinnervating MicroRNA  

NSDL National Science Digital Library

Over the past 15 years, critical roles for microRNA have been established in regulating cell proliferation, differentiation and development, and death. Williams et al. define a role for a microRNA (miR-206) in reinnervating the neuromuscular junction after injury and improving survival in a mouse model of the neurodegenerative disease amyotrophic lateral sclerosis (ALS).

Robert Brown (University of Massachusetts Medical School;)

2009-12-11

398

Appearances of Multiple Micro Explosions, Micro Jets and Micro Diffusion Flames around an Abruptly Heated Micro PET-Resin Particle  

Microsoft Academic Search

Evaporating and burning processes of a micro polyethylene terephthalate resin particle (abbreviated to PET-resin particle), which has a diameter of about 200 µm and is suddenly exposed to a hot oxidizing atmosphere, are observed and analyzed by combining the devised micro schlieren system with a high- speed CCD video camera. In this investigation the following devised approaches are introduced; the

Ryuji Yamakita; Yojiro Ishino; Norio Ohiwa

399

Micro rotary machine and methods for using same  

SciTech Connect

A micro rotary machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft comprises a horizontal shaft and is operable to be rotated by the micro actuator. A micro tool is coupled to the micro shaft and is operable to perform work in response to motion of the micro shaft.

Stalford, Harold L. (Norman, OK)

2012-04-17

400

Study on Micro Electrochemical Machining at Micro to Meso-scale  

Microsoft Academic Search

Electrochemical machining (ECM) is an anodic dissolution process of metal as anode ion by ion, and micro-ECM is a promising micro machining method at micro to mesoscale. Thus, a micro-ECM setup was developed to fabricate micro parts and explore the feasibility of micro-ECM at micro to mesoscale, including the design of high-frequency micro-energy pulse power supply. By using the detection

Wansheng Zhao; Xiaohai Li; Zhenlong Wang

2006-01-01

401

Micro thrust and heat generator  

DOEpatents

A micro thrust and heat generator has a means for providing a combustion fuel source to an ignition chamber of the micro thrust and heat generator. The fuel is ignited by a ignition means within the micro thrust and heat generator's ignition chamber where it burns and creates a pressure. A nozzle formed from the combustion chamber extends outward from the combustion chamber and tappers down to a narrow diameter and then opens into a wider diameter where the nozzle then terminates outside of said combustion chamber. The pressure created within the combustion chamber accelerates as it leaves the chamber through the nozzle resulting in pressure and heat escaping from the nozzle to the atmosphere outside the micro thrust and heat generator. The micro thrust and heat generator can be microfabricated from a variety of materials, e.g., of polysilicon, on one wafer using surface micromachining batch fabrication techniques or high aspect ratio micromachining techniques (LIGA).

Garcia, Ernest J. (Albuquerque, NM)

1998-01-01

402

Micro thrust and heat generator  

DOEpatents

A micro thrust and heat generator have a means for providing a combustion fuel source to an ignition chamber of the micro thrust and heat generator. The fuel is ignited by a ignition means within the micro thrust and heat generator`s ignition chamber where it burns and creates a pressure. A nozzle formed from the combustion chamber extends outward from the combustion chamber and tappers down to a narrow diameter and then opens into a wider diameter where the nozzle then terminates outside of said combustion chamber. The pressure created within the combustion chamber accelerates as it leaves the chamber through the nozzle resulting in pressure and heat escaping from the nozzle to the atmosphere outside the micro thrust and heat generator. The micro thrust and heat generator can be microfabricated from a variety of materials, e.g., of polysilicon, on one wafer using surface micromachining batch fabrication techniques or high aspect ratio micromachining techniques (LIGA). 30 figs.

Garcia, E.J.

1998-11-17

403

Industrial applications for LIGA-fabricated micro heat exchangers  

NASA Astrophysics Data System (ADS)

One of the well-known benefits of micro scale is enhanced heat transfer. This fact provides the motivation for fabricating a variety of micro heat exchangers using derivatives of the LIGA micromachining process. These heat exchangers can be made of polymers, nickel (electroplated or electroless), or ceramics (Si3N4 and alumina are presently being investigated). These heat exchangers are envisioned for applications such as gas turbine blades, mechanical seals and/or bearings, boilers, condensers, radiators, evaporators, electronic component cooling, and catalytic converters. In this paper, methods to fabricate an array of heat exchangers for different applications are described. In addition, simple analytic models that illustrate the motivation for fabricating micro cross flow heat exchanges are shown to compare favorably with experimental heat transfer results.

Kelly, Kevin W.; Harris, Chad; Stephens, Lyndon S.; Marques, Christophe; Foley, Dan

2001-10-01

404

Thermal measurement and analysis of micro devices using thermography  

NASA Astrophysics Data System (ADS)

Sensors and actuators become much smaller as parts of MEMS devices. Some of them run based on the thermal principle and thermal characteristics directly determine their performance. For example, micro-hotplate structures are incorporated into integrated gas sensors to heat the sensing thin film to a determinate temperature with a high sensitivity. The micro-machined accelerometer with no proof mass is based on free convection of a tiny hot air bubble in an enclosed chamber. The temperature profile of its heater is a key factor influencing the feature of the accelerometer. A thermally actuated membrane micro-pumpo can drive fluid by periodical heating of materials with different thermal expansion coefficients and consequent periodical vibration. An IR thermography with a microscopic set was applied in their thermal measurement to optimize these devices.

Gu, Y. Q.; Zhang, Ronghai; Zhu, Dezhong

2003-04-01

405

Micro Eddy Current Testing by micro magnetic sensor array  

SciTech Connect

A micro Eddy Current Testing (ECT) system for planar thin specimens made of INCONEL 600 with flaws was proposed and developed. A micro ECT probe used here consists of a conventional pancake-type coil as an exciting coil and a micro magnetic sensor array as a set of pickup coils. Magnetic field perturbation due to a flaw was measured with high spatial resolution and signal-to-noise (S/N) ratio. The measured signals from the array were compared with numerical results obtained by a three-dimensional A-[phi] code. It was confirmed that the Micro ECT system has the potential to evaluate the length and depth of a flaw with better accuracy than that of a conventional pancake-type ECT in the stream generator tubings in a pressurized water nuclear reactor.

Uesaka, Mitsuru; Nakanishi, Takahiro; Miya, Kenzo (Univ. of Tokyo, Ibaraki (Japan). Nuclear Engineering Research Lab.); Komatsu, Hidenobu; Aoki, Kazuhiko (Nuclear Fuel Industries, Ltd., Osaka (Japan)); Kasai, Kazuo (Sumitomo Precision Co. Ltd., Hyogo (Japan))

1995-01-01

406

Magnetostatic micro-resonators.  

NASA Astrophysics Data System (ADS)

Small scale magnetostatic wave devices are potentially important for on-chip filters for communication systems and more exotic gated spin wave devices. We describe experimental results that measure transmission and reflection resonances in micron size resonators coupled to coplanar waveguides. Ferromagnetic CoZrTa films were sputtered onto Si wafers covered by SiO2 and lithographically patterned into stripes and crosses of varying length and width. Magnetostatic waves were excited and detected by overlaying coupling loops patterned as shorted coplanar waveguides. Transmission and reflection S-parameters of fabricated structures were measured in the frequency range (0-50)GHz. Transmission and reflection resonances strongly dependent on the geometry of the ferromagnetic device and applied magnetic field are observed. The results are modeled as standing magneto static waves in micro-resonators. We discuss effect of biasing magnetic fields, approaches to enhanced coupling to the magnetostatic resonators, magnetostatic wave interferometers and magnetization controlled magnetostatic wave switching in junctions. This work is supported by the Nanoelectronics Research Initiative (NRI) - Western Institute of Nanoelectronics (WIN)

Kozhanov, Alexander; Griffith, Zach; Rodwell, Mark; Allen, Jim; Lee, Dok Won; Wang, Shan; Jacob, Ajey

2008-03-01

407

Development of a fiber coating based on molecular sol-gel imprinting technology for selective solid-phase micro extraction of caffeine from human serum and determination by gas chromatography/mass spectrometry.  

PubMed

In this work, a molecular sol-gel imprinting approach has been introduced to produce a fiber coating for selective direct immersion solid-phase microextraction (SPME) of caffeine. The polymerization mixture was composed of vinyl trimethoxysilane and methacrylic acid as vinyl sol-gel precursor and functional monomer, respectively. Caffeine was used as template molecule during polymerization process. The prepared fibers could be coupled directly to gas chromatography/mass spectrometry (GC/MS) and used for trace analysis of caffeine in a complex sample such as human serum. The parameters influencing SPME such as time, temperature and stirring speed were optimized. The prepared coating showed good selectivity towards caffeine in the presence of some structurally related compounds. Also, it offered high imprinting capability in comparison to bare fiber and non-imprinted coating. Linear range for caffeine detection was 1-80 ?g mL(-1) and the limit of detection was 0.1 ?g mL(-1). The intra-day and inter-day precisions of the peak areas for five replicates were 10 and 16%, respectively. PMID:22541818

Rajabi Khorrami, Afshin; Rashidpur, Amene

2012-04-04

408

Energy and CO 2 emissions performance assessment of residential micro-cogeneration systems with dynamic whole-building simulation programs  

Microsoft Academic Search

Micro-cogeneration, also termed micro combined heat and power (MCHP) or residential cogeneration, is an emerging technology with the potential to provide energy efficiency and environmental benefits by reducing primary energy consumption and associated greenhouse gas emissions. The distributed generation nature of the technology also has the potential to reduce losses due to electrical transmission and distribution inefficiencies and to alleviate

Viktor Dorer; Andreas Weber

2009-01-01

409

Design and fabrication of a low-power and nanoporous micro-hotplate for chemical sensor applications with high sensitivity  

Microsoft Academic Search

The paper describes a conceptual platform development, including design, simulation and manufacture in nanoporous biomedical and chemical sensor applications. We exploit anodic aluminum oxidation (AAO) technology to produce an excellent nanoporous surface for fast gas detection, and combine with micro-electromechanical systems (MEMS) process to implement micro-sized devices with low power consumption. In order to compare the substantial difference between nanoporous

Sheng-Po Wu; Yong-Sheng Huang; Chih-Cheng Lu; Jen-Tzong Jeng

2010-01-01

410

NEAR REAL-TIME ON GC ANALYSIS OF VOLATILE ORGANIC COMPOUNDS USING AN ON-LINE MICRO-TAP  

EPA Science Inventory

Micro-traps act as sample preconcentrators for gas chromatography (GC) that can be used to make repetitive injections every few seconds. hermal desorption micro-trap is made from a short segment of thin tubing containing an adsorbent or a chromatographic stationary phase. arrier ...

411

A very large area Micro Pixel Chamber  

NASA Astrophysics Data System (ADS)

A Micro Pixel Chamber, called “?-PIC”, is a gaseous 2D imaging detector with a fine pixel electrode based on the Printed Circuit Board technology, and we developed it for the X/gamma-ray imaging and the tracking of the charged particles [A. Ochi, et al., Nucl. Instr. and Meth. A 478 (2002) 196; T. Nagayoshi, et al., Nucl. Instr. and Meth. A 525 (2004) 20.]. The previous ?-PIC has a fine position resolution, a high gas gain, a good gas gain uniformity and the stable operation. Although the detection area of the previous ?-PIC (˜10×10cm) is not large enough for a variety of the application, for example an MeV gamma-ray Compton camera [T. Tanimori, et al., New Astron. Rev. 48 (2004) 263.] and dark matter search [T. Tanimori, et al., Phys. Lett. B 578 (2004) 241.]. Therefore, we developed a new ?-PIC having a ˜30×30cm detection area. The structure and the pitch of the electrode are same as those of the previous ?-PIC. There are 768×768 pixels in the whole area. This ?-PIC (TOSHIBA SN041129-1) is operated with a stable gas gain of ˜3500 and a maximum gain of ˜7000 at the center region, and the variety of the gain was 16.7% RMS. An X-ray image of the whole area was also taken by the irradiation of the X-rays from 109Cd (22 keV) to the whole detection area.

Takada, A.; Hattori, K.; Kabuki, S.; Kubo, H.; Miuchi, K.; Nagayoshi, T.; Nishimura, H.; Okada, Y.; Orito, R.; Sekiya, H.; Takeda, A.; Tanimori, T.; Ueno, K.

2007-04-01

412

Aluminum doped hydrogenated nanocrystalline cubic silicon carbide films deposited by VHF-PECVD for p-type window layer of silicon based thin-film solar cells  

Microsoft Academic Search

Aluminum doped (Al-doped) p-type nc-3C-SiC:H films were successfully depsoited by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) at a low substrate temperature of about 360°C using dimethylaluminum hydride (DMAH) as an Al dopant. Dark conductivity and activation energy of the films were strongly influenced by H2\\/MMS gas flow ratio. A dark conductivity of a 27-nm-thick film was improved

Daisuke Hamashita; Shinsuke Miyajima; Akira Yamada; Makoto Konagai

2010-01-01

413

Micro-stereo-lithography system  

NASA Astrophysics Data System (ADS)

We have realized Micro-stereo-lithography technology and system. It can make micro 3D structures more reasonable throughput than existing systems. It has less 2 micron resolutions in the XY directions and 5 micron resolution in the Z layer. We developed a high resolution optical-apparatus, some new photo-polymerizing polymers and a mechanism to coat the thin film of the polymer. Our system can offer various structures with over-hung, hollowed and spiral shape with reasonable resolution and quick turnaround time by maskless technology. We show these results, for example, micro turbine, micro coil and photonic crystal. We hope these technologies will be useful for various fields in the future, for example, nano-imprint, industrial parts and medical fields.

Yoshimoto, T.; Miyaki, I.; Yaze, H.; Maruka, Y.; Ri, N.; Teramoto, T.; Morohoshi, K.; Koyagi, Y.

2006-04-01

414

Statistical characteristic and parameter characterization of 3D surface micro-topography on micro-EDM  

Microsoft Academic Search

The characteristic of three-dimensional (3D) surface micro-topography of micro-EDM plays an important role on the component function properties. In this paper, two types of 3D surface micro-topography, which machined by micro-electrical discharge machining forming (micro-EDMF) and micro-wire electrical discharge machining (micro-WEDM), have been measured by the atomic force microscope (AFM) instrument after the surface data have been reshaped and denoised

Haijuan Ding; Libin Guo; Hai Cui

2009-01-01

415

Stretchable MicroElectrode Array  

Microsoft Academic Search

This paper focuses on the design consideration, fabrication processes and preliminary testing of the stretchable micro-electrode array. We are developing an implantable, stretchable micro-electrode array using polymer-based microfabrication techniques. The device will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces and electroplated electrodes. The metal features

M Maghribi; D Polla; K Rose; T Wilson; P Krulevitch

2002-01-01

416

Micro air vehicle navigation system  

Microsoft Academic Search

A description of the design, operation, and test results of a Micro-Electro-Mechanical (MEMS)-based navigation system for the Micro Air Vehicle (MAV) is presented. The MAV is a small Unmanned Aerial Vehicle (UAV) built by Honeywell. It is one of the first applications to use Honeywell's new HG1930 MEMS inertial measurement unit (IMU). The raw IMU measurements are transmitted via a

B. B. Mohr; D. L. Fitzpatrick

2008-01-01

417

The rf Micro-Hollow Device  

NASA Astrophysics Data System (ADS)

The rf Micro-Hollow Device (rfMHD) is a new micro-plasma source with which we aim to provide sub 10 micron plasmas and densities >10^22 m-3. Applications include targeted processing for electronic & bio-materials, gas sensors and light sources. The micron-scale dimensions and near atmospheric pressure operation give new physics at turn on and during steady state operation. RfMHDs of 25 microns diameter have been demonstrated[1]; they ignite readily and operate stably at powers less than 10W. The rfMHD device will be introduced and its operation described. Results from electrical and optical measurements & their analysis will be presented. Potential processes contributing to ignition & sustainment will be discussed. The prospects of operating with smaller source diameters & the science required to describe operation at these reduced scales will be addressed. The rfMHD will be presented in the context of biomedical applications currently of interest to this centre.[4pt] [1] Mahony, Gans, Graham, Maguire & Petrovic, 2008 Appl Phys Lett 93 011501

Maguire, P. D.; Mahony, C. M. O.; Greenan, J.; Gans, T.; O'Connell, D.; Graham, W. G.

2009-10-01

418

Micro cryogenic coolers for IR imaging  

NASA Astrophysics Data System (ADS)

Joule-Thomson micro cryogenic coolers (MCCs) are a preferred approach for small and low power cryocoolers. With the same heat lift, MCC's power input can be only 1/10 of a thermoelectric cooler's input, and MCC's size can be only 1/10 of a Stirling cooler's size. With futuristic planar MCC and with high frequency MEMS compressors to be developed, its size can be reduced another order of magnitude. Such "invisible" cryocoolers may revolutionize future IR imaging systems. We will review our studies on the feasibility of MCC with an emphasis on: 1) high thermal isolation levels reaching 89,000 K/W; 2) custom-designed gas mixtures with refrigeration capabilities increased by 10X and pressure ratio reduced to only 4:1; 3) compressors with low pressure ratios; and 4) excellent scalability for further size reduction.

Lewis, Ryan; Wang, Yunda; Cooper, Jill; Lin, Martin M.; Bright, Victor M.; Lee, Y. C.; Bradley, Peter E.; Radebaugh, Ray; Huber, Marcia L.

2011-05-01

419

Influence of bubble size on micro-bubble drag reduction  

NASA Astrophysics Data System (ADS)

Micro-bubble drag reduction experiments were conducted in a turbulent water channel flow. Compressed nitrogen was used to force flow through a slot injector located in the plate beneath the boundary layer of the tunnel test section. Gas and bubbly mixtures were injected into a turbulent boundary layer (TBL), and the resulting friction drag was measured downstream of the injector. Injection into tap water, a surfactant solution (Triton X-100, 20 ppm), and a salt-water solution (35 ppt) yielded bubbles of average diameter 476, 322 and 254 ?m, respectively. In addition, lipid stabilized gas bubbles (44 ?m) were injected into the boundary layer. Thus, bubbles with d + values of 200 to 18 were injected. The results indicate that the measured drag reduction by micro-bubbles in a TBL is related strongly to the injected gas volumetric flow rate and the static pressure in the boundary layer, but is essentially independent of the size of the micro-bubbles over the size range tested.

Shen, Xiaochun; Ceccio, Steven L.; Perlin, Marc

2006-09-01

420

Electromagnetic micro power generator — A comprehensive survey  

Microsoft Academic Search

This paper presents a comprehensive survey on vibration powered electromagnetic micro generator, which harvest mechanical energy from environment and convert this energy into useful electrical power for micro system and sensor node. The on-going research works on electromagnetic micro generator are reviewed as a background of this paper. Basic theories of micro generator to produce power from ambient motion by

Wong Chin Chye; Zuraini Dahari; Othman Sidek; Muhammad Azman Miskam

2010-01-01

421

Microscopic Approaches to Decomposition and Burning Processes of a Micro Plastic Resin Particle under Abrupt Heating  

NASA Astrophysics Data System (ADS)

To elucidate the possibility and availability of thermal recycling of waste plastic resin from a basic and microscopic viewpoint, a series of abrupt heating processes of a spherical micro plastic particle having a diameter of about 200 ?m is observed, when it is abruptly exposed to hot oxidizing combustion gas. Three ingenious devices are introduced and two typical plastic resins of polyethylene terephthalate and polyethylene are used. In this paper the dependency of internal and external appearances of residual plastic embers on the heating time and the ingredients of plastic resins is optically analyzed, along with appearances of internal micro bubbling, multiple micro explosions and jets, and micro diffusion flames during abrupt heating. Based on temporal variations of the surface area of a micro plastic particle, the apparent burning rate constant is also evaluated and compared with those of well-known volatile liquid fuels.

Ohiwa, Norio; Ishino, Yojiro; Yamamoto, Atsunori; Yamakita, Ryuji

422

Use of MicroMaps for Satellite Validation and Potential UAV Applications  

Microsoft Academic Search

The MicroMAPS instrument is a nadir-viewing, gas filter-correlated radiometer which operates in the 4.67 micrometer fundamental band of carbon monoxide. Originally designed and built for a space mission, this CO remote sensor is being flown in support of satellite validation and science instrument demonstrations for potential UAV applications. The MicroMAPS CO instrument was flown for the first time during the

V. S. Connors; G. W. Sachse; P. E. Hopkins; W. W. McMillan

2005-01-01

423

MicroMAPS CO Measurements over North America and Europe during Summer-Fall 2004  

Microsoft Academic Search

The MicroMAPS instrument is a nadir-viewing, gas filter-correlated radiometer which operating in the 4.67 micrometer fundamental band of carbon monoxide. Originally designed and built for a space mission, this CO remote sensor is being flown in support of satellite validation and science instrument demonstrations for potential UAV applications. The MicroMAPS instrument system, as flown on Proteus, was designed by a

V. S. Connors; P. E. Hopkins; H. G. Reichle; W. H. Morrow; W. W. McMillan; M. Sandy

2006-01-01

424

High-resolution Burnett simulations of micro Couette flow and heat transfer  

Microsoft Academic Search

A high-order continuum model for micro-scale flows is investigated. The Burnett equations are applied to the steady-state micro Couette flow of a Maxwellian monatomic gas. Solutions to these equations are shown to be stable for all Knudsen numbers (Kn) up to the limit of the equations’ validity (Kn?1). The reason why previous researchers have failed to obtain solutions to this

Duncan A. Lockerby; Jason M. Reese

2003-01-01

425

Micro manipulation based on micro physics-strategy based on attractive force reduction and stress measurement  

Microsoft Academic Search

Micro manipulation is required for assembling and maintenance works of micro machines and their parts. This paper proposes a handling strategy for micro objects based on micro physics. Attractive forces are modeled and their reduction methods are presented. The authors show experimental results of reducing these forces. Based on the proposed reduction methods, the authors present a new micro manipulation

F. Arai; D. Ando; T. Fukuda; Y. Nonoda; T. Oota

1995-01-01

426

Fabrication of high-density micro holes by upward batch micro EDM  

Microsoft Academic Search

A large number of micro holes are needed for biomedical parts, ink-jet nozzles and micro droplet spraying parts. In this study, an inexpensive machining approach for producing a batch of micro holes is proposed. A set of previously introduced w-EDM mechanisms is employed to horizontally cut the batch micro electrodes precisely. Through the process arrangement, the micro electrodes and workpiece

Shun-Tong Chen

2008-01-01

427

Micro-range micro-doppler for dismount classification  

NASA Astrophysics Data System (ADS)

This paper presents a processing technique that can be used to detect and classify pedestrians group based on the micro- Doppler signature gathered with a millimeter wave radar. The evaluation of the number of pedestrians moving in a group can be a difficult task using a traditional micro-Doppler spectrogram because of a tendency for people to partially synchronize their steps when walking together. The new approach, based on multi-range variation as well as the micro-Doppler variations, provides promising results. The range-spectrogram processing technique was developed and tested using a database composed of hundreds of pedestrian and vehicle signatures gathered in an urban test site over a two year period in a variety of weather conditions. We associate image detections with radar detections through motion extracted from both radar and imagery. We also explain how radar and video together can produce an inexpensive alternative to 3-D imaging.

Tahmoush, Dave

2013-05-01

428

Gas Hydrate: Possible Source of Energy from Ocean  

Microsoft Academic Search

Gas hydrate is a solid material, formed from water and hydrocarbon (mainly methane) having micro particle weight, which is also known as clathrate. It is extensively distributed in oceanic and polar sediments, where the temperature is very low and the pressure is very high. Under such conditions, methane gas gets crystallized and converts into solid gas hydrate. Large number of

Harsh K Gupta

2004-01-01

429

Using a helical micro-tool in micro-EDM combined with ultrasonic vibration for micro-hole machining  

NASA Astrophysics Data System (ADS)

This paper presents a novel process using micro-electro-discharge- machining (micro-EDM) combined with ultrasonic vibration by a helical micro-tool electrode to drill and finish micro-holes. During the machining processes, a micro-tool is directly fabricated by wire electro-discharge grinding (WEDG) using micro-EDM combined with various methods for machining the micro-hole and by ultrasonic vibration to finish the hole wall. In this work, circular micro-holes are machined in a high nickel alloy by cylindrical and helical electrodes. Using a helical micro-tool electrode for micro-EDM combined with ultrasonic vibration (HE-MEDM-UV) can substantially reduce the EDM gap, taper and machining time for deep micro-hole drilling. In addition, using a helical micro-tool with micro ultrasonic vibration finishing (HE-MUVF), good surface quality and less taper of the hole wall can be obtained by applying a suitable electrode step variation, rotational speed and ultrasonic amplitude with a machining time of approximately 25 min. According to scanning electron microscopy (SEM) micrographs and atomic force microscopy (AFM) measurement, HE-MUVF can indeed improve the surface roughness from 1.345 µm Rmax before finishing to 0.58 µm Rmax after HE-MUVF. This result demonstrates that using HE-MEDM-UV combined with MUVF can yield micro-holes of precise shape and smooth surface.

Hung, Jung-Chou; Lin, Jui-Kuan; Yan, Biing-Hwa; Liu, Hung-Sung; Ho, Ping-Hsing

2006-12-01

430

Mechano-micro/nano systems  

NASA Astrophysics Data System (ADS)

In recent years, the researches about Micro/Nano Systems are down actively in the bio-medical research fields, DNA research fields, chemical analysis systems fields, etc. In the results, a new materials and new functions in the systems are developed. In this invited paper, Mechano-Micro/Nano Systems, especially, motion systems are introduced. First, the research activities concerning the Mechano-Micro/Nano Systems in the world(MST2003, MEMS2003 and MEMS2004) and in Japan(Researech Projects on Nanotechnology and Materials in Ministry of Education, Culture, Sports, Science and Technology) are shown. Secondary, my research activities are introduced. As my research activities, (1) a comb-drive static actuator for the motion convert mechanisms, (2) a micro-nano fabrication method by use of FAB(Fast Atom Beam) machines, (3) a micro optical mirror manipulator for inputs-outputs optical switches, (4) a miniature pantograph mechanism with large-deflective hinges and links made of plastics are discussed and their performances are explained.

Horie, Mikio

2004-10-01

431

The Micro Pulsed Plasma Thruster  

NASA Astrophysics Data System (ADS)

There is an increased requirement for microsatellites to support such future missions as formation-flying space-based radar, space control, and on-orbit satellite servicing. Devices that can provide precise impulse bit in the 10 micro Newton range may be enabling for a new fleet of 25-kg class spacecraft supporting these missions. In response to this need the Air Force Research Laboratory is developing a miniaturized propulsion unit: the Micro Pulsed Plasma Thruster (Micro-PPT). Like a standard PPT, The Micro-PPT uses a surface discharge across the face of a solid Teflon(TM) propellant to create and accelerate a combination of plasma and neutral vapor. However the Micro-PPT substantially differs from the standard design by using a self-igniting discharge and eliminating the separate igniter and trigger circuit from the thruster. This simplification enables the order-of- magnitude reductions in the thruster size and operational power level required to meet the microsatellite propulsion requirement.

Spanjers, Gregory G.; Schilling, John H.; Engelman, Scott; Spores, Ronald A.

1999-05-01

432

Micro hot plate-based sensor array system for the detection of environmentally relevant gases.  

PubMed

A monolithic stand-alone gas sensor system is presented, which includes on a single chip an array of three metal oxide-coated micro hot plates with integrated MOS-transistor heaters, as well as a specifically designed digital system architecture. An octagonal-shaped micro hot plate design with MOS-transistor heaters has been adopted for the three gas sensors. The integrated circuitry includes a programmable digital temperature regulation, digital sensor readout units, and a standard serial interface. The programmable digital temperature controllers enable individual regulation of the micro hot plate temperatures in constant or dynamic mode. Nanocrystalline tin oxide thick films with different Pd dopings (undoped, 0.2 and 3 wt %) were used. Gas test measurements for environmentally relevant gases were carried out and evidenced detection limits of less than 1 ppm for carbon monoxide, or 100 ppm for methane, both at 40% relative humidity. Temperature modulation techniques were successfully applied for improved analyte discrimination. PMID:17007499

Graf, M; Frey, U; Taschini, S; Hierlemann, A

2006-10-01

433

Micro electric propulsion feasibility  

NASA Astrophysics Data System (ADS)

Miniature, 50 kg class, strategic satellites intended for extended deployment in space require an on-board propulsion capability to perform needed attitude control adjustments and drag compensation maneuvers. Even on such very small spacecraft, these orbit maintenance functions can be significant and result in a substantial propellant mass requirement. Development of advanced propulsion technology could reduce this propellant mass significantly, and thereby maximize the payload capability of these spacecraft. In addition, spacecraft maneuverability could be enhanced and/or multi-year mission lifetimes realized. These benefits cut spacecraft replacement costs, and reduce services needed to maintain the launch vehicles. For SDIO brilliant pebble spacecraft, a miniaturized hydrazine propulsion system provides both boost and divert thrust control. This type of propulsion system is highly integrated and is capable of delivering large thrust levels for short time periods. However, orbit maintenance functions such as drag make-up require only very small velocity corrections. Using the boost and/or divert thrusters for these small corrections exposes this highly integrated propulsion system to continuous on/off cycling and thereby increases the risk of system failure. Furthermore, since drag compensation velocity corrections would be orders of magnitude less than these thrusters were designed to deliver, their effective specific impulse would be expected to be lower when operated at very short pulse lengths. The net result of these effects would be a significant depletion of the on-board hydrazine propellant supply throughout the mission, and a reduced propulsion system reliability, both of which would degrade the interceptors usefulness. In addition to SDIO brilliant pebble spacecraft, comparably small spacecraft can be anticipated for other future strategic defense applications such as surveillance and communication. For such spacecraft, high capability and reliability, minimal detectability and low cost are requirements. All these miniature spacecraft share a common characteristic: because of their on-board electronic equipment they have, by design, solar order 50-100 W. In a relative sense, such spacecraft are power rich when compared to other larger spacecraft. This power rich situation is offset by very tight mass budgets, which make reductions in propellant mass requirements a key issue in meeting overall spacecraft minimum mass goals. In principle, power rich and propellant poor brilliant pebbles class spacecraft can benefit from using high specific impulse electric propulsion to reduce chemical propellant mass requirements. However, at power levels of order 50 W, arcjets cannot be made to function, ion thrusters are too complex and heavy and resistojets have too low a specific impulse. Recognizing these capability limitations in existing electric propulsion technology, the SDIO/IST sponsored the Phase I SBIR Micro Electric Propulsion (MEP) thruster study described in this report.

Aston, Graeme; Aston, Martha

1992-11-01

434

Development of Micro UAV Swarms  

NASA Astrophysics Data System (ADS)

Some complex application scenarios for micro UAVs (Unmanned Aerial Vehicles) call for the formation of swarms of multiple drones. In this paper a platform for the creation of such swarms is presented. It consists of modified commercial quadrocopters and a self-made ground control station software architecture. Autonomy of individual drones is generated through a micro controller equipped video camera. Currently it is possible to fly basic maneuvers autonomously, such as take-off, fly to position, and landing. In the future the camera's image processing capabilities will be used to generate additional control information. Different co-operation strategies for teams of UAVs are currently evaluated with an agent based simulation tool. Finally complex application scenarios for multiple micro UAVs are presented.

Bürkle, Axel; Leuchter, Sandro

435

[Investigation on the electron density of a micro-plasma jet operated at atmospheric pressure].  

PubMed

In the present paper, a micro-hollow cathode discharge setup was used to generate micro-plasma jet in flowing mixture of Ar and N2 at atmospheric pressure. The characteristics of the micro-plasma jet were investigated by means of optical method and electrical one. It has been found that breakdown occurs in the gas between the two electrodes when the input power of electric source is increased to a certain value. Plasma appears along the gas flow direction when the mixed gas flows from the aperture of the micro-hollow cathode, and the length of plasma reaches 4 mm. The discharge current is quasi-continuous, and the duration of discharge pulse is about 0.1 micros. Electron density was studied by using Einstein equation and Stark broadening of spectral lines from the emission spectrum respectively. It was found that the results of electron density calculated by the two methods are consistent with the order of 10(15) x cm(-3). It was also found that the electron density is almost independent of power. A qualitative explanation to the phenomenon is given based on the gas discharge theory. PMID:20827964

Li, Xue-chen; Zhao, Na; Liu, Wei-yuan; Liu, Zhi-qiang

2010-07-01

436

Micro-hole machining using micro-EDM combined with electropolishing  

Microsoft Academic Search

This paper presents a novel process of using micro-electro-discharge- machining (micro-EDM) combined with electropolishing to improve the surface roughness of micro-holes. During the machining process, a tool is fabricated by wire electro-discharge grinding (WEDG) directly by using micro-EDM for machining the micro-hole and by electropolishing to finish the hole wall. In this work, various micro-holes are machined on the high

Jung-Chou Hung; Biing-Hwa Yan; Hung-Sung Liu; Han-Ming Chow

2006-01-01

437

Elemental analyses of hypervelocity micro-particle impact sites on interplanetary dust experiment sensor surfaces  

NASA Astrophysics Data System (ADS)

The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity micro-particles that struck the active sensors with enough energy to breakdown the 0.4 to 1.0 micron thick SiO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. These discharge features, which include 50 micron diameter areas where the aluminum top layer has been vaporized, facilitate the location of the impacts. The high purity Al-SiO2-Si substrates allow detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) is used to create two-dimensional elemental ion intensity maps of micro-particle impact sites on the IDE sensors. The element intensities in the central craters of the impacts are corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results are used to classify the particles' origins as 'manmade', 'natural' or 'indeterminate'. The last classification results from the presence of too little impactor residue (a frequent occurrence on leading edge impacts), analytical interference from high background contamination, the lack of information on silicon residue, the limited usefulness of data on aluminum in the central craters, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters, of these features. A total of 35 impacts on leading edge sensors and 22 impacts on trailing edge sensors were analyzed.

Simon, Charles G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. R.; Wortman, Jim J.

1992-06-01

438

Study of a microstrip gas detector for the Compact Muon Solenoid experiment.  

National Technical Information Service (NTIS)

The micro-strip gas chambers (MSGC) were realized due to the technological advances in the field of micro-electronics. The wire of usual gas counters is replaced in these detectors by metallic stripes as a periodic sequence of electrodes (anodes and catho...

J. Clergeau

1997-01-01

439

Surface form metrology of micro-optics  

NASA Astrophysics Data System (ADS)

This keynote starts from an overview of micro-optics from fundamental functions, fabrication methods and applications in precision engineering and nanotechnology. State-of-the-art measuring systems for surface form metrology of microoptics with micro-structured surfaces, including diffractive micro-optics such as diffraction gratings and refractive micro-optics such as micro lenses and micro-lens arrays, are then be presented. The measuring systems introduced in the presentation are classified into scanning probe microscope-based systems, mechanical stylus profiling systems and optical evaluation systems. Related research activities carried out in the authors' group are also highlighted.

Xu, Bin; Jia, Zhigang; Li, Xinghui; Chen, Yuan-Liu; Shimizu, Yuki; Ito, So; Gao, Wei

2013-06-01

440

Feasibility study of the wave disk micro-engine operation  

NASA Astrophysics Data System (ADS)

The development of micro turbine engines has been strongly intensified in recent years. Since turbo-component efficiency has become very low due to the downsizing effect, the micro wave rotor is expected to be applied for the improvement of the performance of ultra-micro gas turbines, increasing the cycle pressure ratio. But wave rotors can also be used in another configuration. Here replacement of steady flow engine components by unsteady flow devices is proposed and analyzed. Applying a combustion chamber only and using oblique blades to form the rotor cells, net power can be taken from the rotor. In that way the use of an inefficient, micro-scale turbo unit can be omitted. Conventional construction of unsteady devices in the form of a wave rotor cannot be realized in MEMS technology. The new idea of a wave disk gives the possibility of an easy implementation of a wave engine in MEMS technology. In the proposed solution the wave disk plays the role of an active compression-decompression unit and torque generator. Appropriate port geometry with straight or oblique blades forming the disk channels generates torque. The engine disk rotates with a speed much lower than the conventional turbo unit and simplifies the bearing problem. Also the construction of an electric generator could be simpler. This paper presents the proposed flow schemes, thermodynamic cycle, exemplary engine construction and some preliminary results of simulation of the MEMS wave engine utilizing the wave disk geometry.

Piechna, Janusz R.

2006-09-01

441

Micro-agglomerate flotation for deep cleaning of coal  

SciTech Connect

We are investigating the use of a hybrid process - Micro-agglomerate flotation - which is a combination of oil-agglomeration and froth flotation. The basic concept is to use small quantities of oil to promote the formation of dense micro-agglomerates with minimal entrapment of water and mineral particles, and to use froth flotation to extract these micro-agglomerates from the water/dispersed-mineral phase. Since the floating units are agglomerates (about 30--50 [mu]m in size) rather than individual coal particles (1--10 [mu]m) the problems of froth overload and water/mineral carryover should be significantly alleviated. Micro-agglomerate flotation has considerable potential for the practical deep cleaning of coal on a commercial scale. In principle, it should be possible to achieve both high selectivity and high yield at reasonable cost. The process requires only conventional, off-the-shelf equipment and reagent usage (oil, surfactants, etc.) should be small. There are, however, complications. The process involves at least five phases: two or more solids (coal and mineral), two liquids (oil and water) and one gas (air). It is necessary to maintain precise control over the chemistry of the liquid phases in order to promote the interfacial reactions and interactions between phases necessary to ensure selectivity. Kinetics as well as thermodynamic factors may be critical in determining overall system response.

Chander, S.; Hogg, R.

1993-01-01

442

Gas and Gas Pains  

MedlinePLUS

... inflammatory bowel disease, such as ulcerative colitis or Crohn's disease. Antibiotics. In some cases of excess gas, antibiotic ... you eat and drink. Don't smoke. Cigarette smoking can increase the amount of air you swallow. ...

443

Micro-bubble Enhanced Sonoporation  

Microsoft Academic Search

A gene transfer system that uses ultrasound, known as sonoporation, has recently been developed, and it is known that micro-bubbles can help gene transfection in this technique. However, the mechanism and optimal induction conditions have not yet been fully clarified. We examined the factors that affect the gene induction rate, and attempted to devise a method for high-efficiency gene induction.

Rie Tachibana; Akio Okamoto; Kiyoshi Yoshinaka; Shu Takagi; Yoichiro Matsumoto

2010-01-01