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1

Stresa, Italy, 26-28 April 2006 A SILICON-BASED MICRO GAS TURBINE ENGINE FOR POWER GENERATION  

E-print Network

of Manufacturing Technology, Singapore 658075 2 MEMS & Packaging Research Lab, AIST, Tsukuba, 305-8564 Japan 3 technology is proposed by MIT [1-3]. Tohoku University has also fabricated three-dimensional micro turbines using micro milling [4-5]. In micro heat engine system, both the heat loss and chamber wall cooling

Paris-Sud XI, Université de

2

The high versatility of silicon based micro-optical modulators  

NASA Astrophysics Data System (ADS)

"One product, one process": This MEMS law is true for micro-optical modulators, too and thus puts a high load on every product and technology development team. On the other hand the law expresses nothing but the high versatility of the underlying usually silicon based technology. A huge variety of applications where an electromagnetic wave experiences a spatial-temporal modulation makes use of this technology: High resolution as well as ultra-compact displays, optical switches in telecommunication as well as data storage devices, spectrometers e. g. for quality control, as well as adaptive optics and pattern generation to mention only a few. The applications completely differ with regard to the requirements in almost all aspects. The most important drivers to use silicon based micro-optical modulators are high accuracy, high bandwidth and high miniaturization. A continuous further development of the technology can be reported. Novel optical, mechanical and electrical working principles are investigated to meet future requirements. After a short overview of the most typical applications of silicon based micro-optical modulators the high versatility of this technology is detailed by means of selected devices and applications. Single 1D and 2D micro mirrors with diameters of up to 4 mm e. g. for projection, imaging and spectroscopy are as well presented and discussed as micro mirror arrays comprising up to 1 million analog deflectable mirrors for image generation and phase modulation in microlithography and adaptive optics.

Schenk, Harald

2009-02-01

3

Micro focusing deformable mirror fabricated by combination with silicon based and nonsilicon based micromachining  

Microsoft Academic Search

In this work, a micro focusing deformable mirror is designed for fabricated by combination with silicon and nonsilicon based micromachining. The upper electrode and mirror is designed and made by traditional silicon based micromachining in silicon substrate. And lower electrode is fabricated at aluminum substrate. However, the lower electrode is fabricated by nonsislicon based micromachining. From results of numerical analysis,

Meng-Ju Lin

2009-01-01

4

Validation of the Compatibility Between a Porous Silicon-Based Gas Sensor Technology and Standard Microelectronic Process  

Microsoft Academic Search

The compatibility of a recently proposed porous silicon formation procedure for gas sensor integration with a commercial microelectronic process is analyzed. Porous silicon-based gas sensors have been produced on a test chip by means of a post-processing approach that enables silicon anodization in selected areas. The effects of the post-processing procedure on electronic circuits, integrated on the test chip as

G. Barillaro; P. Bruschi; G. M. Lazzerini; L. M. Strambini

2010-01-01

5

Integration of a silicon-based microprobe into a gear measuring instrument for accurate measurement of micro gears  

NASA Astrophysics Data System (ADS)

The integration of silicon micro probing systems into conventional gear measuring instruments (GMIs) allows fully automated measurements of external involute micro spur gears of normal modules smaller than 1 mm. This system, based on a silicon microprobe, has been developed and manufactured at the Institute for Microtechnology of the Technische Universität Braunschweig. The microprobe consists of a silicon sensor element and a stylus which is oriented perpendicularly to the sensor. The sensor is fabricated by means of silicon bulk micromachining. Its small dimensions of 6.5 mm × 6.5 mm allow compact mounting in a cartridge to facilitate the integration into a GMI. In this way, tactile measurements of 3D microstructures can be realized. To enable three-dimensional measurements with marginal forces, four Wheatstone bridges are built with diffused piezoresistors on the membrane of the sensor. On the reverse of the membrane, the stylus is glued perpendicularly to the sensor on a boss to transmit the probing forces to the sensor element during measurements. Sphere diameters smaller than 300 µm and shaft lengths of 5 mm as well as measurement forces from 10 µN enable the measurements of 3D microstructures. Such micro probing systems can be integrated into universal coordinate measuring machines and also into GMIs to extend their field of application. Practical measurements were carried out at the Physikalisch-Technische Bundesanstalt by qualifying the microprobes on a calibrated reference sphere to determine their sensitivity and their physical dimensions in volume. Following that, profile and helix measurements were carried out on a gear measurement standard with a module of 1 mm. The comparison of the measurements shows good agreement between the measurement values and the calibrated values. This result is a promising basis for the realization of smaller probe diameters for the tactile measurement of micro gears with smaller modules.

Ferreira, N.; Krah, T.; Jeong, D. C.; Metz, D.; Kniel, K.; Dietzel, A.; Büttgenbach, S.; Härtig, F.

2014-06-01

6

Monolithically-integrated MicroChemLab for gas-phase chemical analysis.  

SciTech Connect

Sandia National Labs has developed an autonomous, hand-held system for sensitive/selective detection of gas-phase chemicals. Through the sequential connection of microfabricated preconcentrators (PC), gas chromatography columns (GC) and a surface acoustic wave (SAW) detector arrays, the MicroChemLab{trademark} system is capable of selective and sensitive chemical detection in real-world environments. To date, interconnection of these key components has primarily been achieved in a hybrid fashion on a circuit board modified to include fluidic connections. The monolithic integration of the PC and GC with a silicon-based acoustic detector is the subject of this work.

Kottenstette, Richard Joseph; Adkins, Douglas Ray; Manley, Robert George; Lewis, Patrick Raymond; Bauer, Joseph M.; Manginell, Ronald Paul; Okandan, Murat; Shul, Randy John; Sokolowski, Sara Suzette

2003-06-01

7

Micro-gas-sensor with conducting polymers  

Microsoft Academic Search

In this paper design and fabrication of micro-gas-sensors, the deposition of four different poly(pyrrole) (PPY) thin films as chemoresistor in the micro-gas-sensors by electrochemical processing and chemical oxidation, and characterisation these films by FTIR, SEM, surface test instrument (WYKO NT2000) and optical microscopy, are reported. The effect of anions in PPY thin films, thickness and surface roughness of the PPY

Q. Fang; D. G. Chetwynd; J. A. Covington; C.-S. Toh; J. W. Gardner

2002-01-01

8

Bottoming micro-Rankine cycles for micro-gas turbines  

Microsoft Academic Search

This paper investigates the possibility of enhancing the performances of micro-gas turbines through the addition of a bottoming organic Rankine cycle which recovers the thermal power of the exhaust gases typically available in the range of 250–300°C. The ORC cycles are particularly suitable for the recovery of heat from sources at variable temperatures, and for the generation of medium to

Costante Invernizzi; Paolo Iora; Paolo Silva

2007-01-01

9

MEMS micropump for a Micro Gas Analyzer  

E-print Network

This thesis presents a MEMS micro-vacuum pump designed for use in a portable gas analysis system. It is designed to be pneumatically-driven and as such does not have self-contained actuation (the focus of future work). ...

Sharma, Vikas, 1979-

2009-01-01

10

Micro-combustor for gas turbine engine  

DOEpatents

An improved gas turbine combustor (20) including a basket (26) and a multiplicity of micro openings (29) arrayed across an inlet wall (27) for passage of a fuel/air mixture for ignition within the combustor. The openings preferably have a diameter on the order of the quenching diameter; i.e. the port diameter for which the flame is self-extinguishing, which is a function of the fuel mixture, temperature and pressure. The basket may have a curved rectangular shape that approximates the shape of the curved rectangular shape of the intake manifolds of the turbine.

Martin, Scott M. (Oviedo, FL)

2010-11-30

11

Micro-cantilever array and its application in gas sensor  

Microsoft Academic Search

Micro-cantilever array was made by micromachining technology. Its mechanical characteristic was analyzed. A gas sensor based micro-cantilever array was presented. The different material sensing layers were fabricated on the different micro-cantilever surface respectively; the physical or chemical absorption alters the mass of micro-cantilever, accordingly, the mechanical characteristic of micro-cantilever was changed. The vibration characteristics of beam array and its changes

Wu Pan; Ning Li

2008-01-01

12

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

13

ANN Modeling of Micro-Machined Gas Sensor Signals  

Microsoft Academic Search

In this paper, an integrated micro-machined gas sensor array, associated with pattern recognition (PARC) techniques, such as artificial neural networks (ANNs), is designed. The proposed sensor design use a number of different sensitive films such as SnO2, TiO2, ZnO, or organic sensitive films to detect different gases. The application of micro-machined Si-based gas sensors in air quality management and emission

Mohamed Gamal El-din; Walied A. Moussa

2005-01-01

14

Microfabricated silicon gas chromatographic micro-channels: fabrication and performance  

SciTech Connect

Using both wet and plasma etching, we have fabricated micro-channels in silicon substrates suitable for use as gas chromatography (GC) columns. Micro-channel dimensions range from 10 to 80 {micro}m wide, 200 to 400 {micro}m deep, and 10 cm to 100 cm long. Micro-channels 100 cm long take up as little as 1 cm{sup 2} on the substrate when fabricated with a high aspect ratio silicon etch (HARSE) process. Channels are sealed by anodically bonding Pyrex lids to the Si substrates. We have studied micro-channel flow characteristics to establish model parameters for system optimization. We have also coated these micro-channels with stationary phases and demonstrated GC separations. We believe separation performance can be improved by increasing stationary phase coating uniformity through micro-channel surface treatment prior to stationary phase deposition. To this end, we have developed microfabrication techniques to etch through silicon wafers using the HARSE process. Etching completely through the Si substrate facilitates the treatment and characterization of the micro- channel sidewalls, which domminate the GC physico-chemical interaction. With this approach, we separately treat the Pyrex lid surfaces that form the top and bottom surfaces of the GC flow channel.

Matzke, C.M.; Kottenstette, R.J.; Casalnuovo, S.A.; Frye-Mason, G.C.; Hudson, M.L.; Sasaki, D.Y.; Manginell, R.P.; Wong, C.C.

1998-11-01

15

Measuring micro-organism gas production  

NASA Technical Reports Server (NTRS)

Transducer, which senses pressure buildup, is easy to assemble and use, and rate of gas produced can be measured automatically and accurately. Method can be used in research, in clinical laboratories, and for environmental pollution studies because of its ability to detect and quantify rapidly the number of gas-producing microorganisms in water, beverages, and clinical samples.

Wilkins, J. R.; Pearson, A. O.; Mills, S. M.

1973-01-01

16

Gas Flow Sensing with a Piezoresistive Micro-Cantilever  

Microsoft Academic Search

This study exploits a bending-up cantilever caused by residual stress to manufacture a micro gas flow sensor. MEMS techniques are used to deposit a silicon nitride layer on a silicon wafer to create a piezoresistive structure. A platinum layer is deposited on the silicon nitride layer to form a resistor and the structure is then etched to form a freestanding

Yu-Hsiang Wang; Chia-Yen Lee; Rong-Hua Ma; Lung-Ming Fu

2006-01-01

17

Silicon based organic semiconductor laser  

NASA Astrophysics Data System (ADS)

The authors demonstrate silicon based visible lasers as potential optical interconnects by combining silicon processed resonators and solution processed light-emitting polymers. The high refractive index and absorption coefficient of silicon at these wavelengths were addressed by developing distributed Bragg reflector resonators on a silicon-on-insulator substrate. The performance of the hybrid structure was characterized and analyzed in comparison to an all-silica counterpart and mechanisms for controlling the number of longitudinal modes and for tuning the emission wavelength were explored.

Vasdekis, A. E.; Moore, S. A.; Ruseckas, A.; Krauss, T. F.; Samuel, I. D. W.; Turnbull, G. A.

2007-07-01

18

Development of high-speed micro-gas bearings for three-dimensional micro-turbo machines  

Microsoft Academic Search

A micro-high-speed bearing test rig has been designed and fabricated to develop air bearings for a micro-machine gas turbine. The micro-machine gas turbine requires bearings of diameter 4 mm to operate stably at 870 000 rpm. Based on the preliminary analysis, it has been found that a large bearing gap and very high rotor balance are required to achieve low

Kousuke Isomura; Shuji Tanaka; Shin-ichi Togo; Masayoshi Esashi

2005-01-01

19

A micro gas chromatography column with a micro thermal conductivity detector for volatile organic compound analysis  

NASA Astrophysics Data System (ADS)

In this paper, a micro gas chromatography (?GC) system contained a ?GC column and a micro thermal conductivity detector (?TCD) was proposed. In order to reduce the volume of the system, some micro heaters were integrated on the surface and backside of the GC column, which could provide a robust temperature programming capability and rapidly increase the temperature of the ?GC column. In addition, a silicon-glass ?TCD with four-thermistor thermal conductivity cells that can offer significant advantages over previously reported designs including low dead volume, good thermal isolation, and elimination of the thermal noise was proposed in this paper. Experimental results have indicated that the ?GC system with a detection limit of several ppm concentration levels separated and detected the benzene, toluene, and styrene in less than 3 min, and the ?GC system also exhibited a good linear response in the test range.

Sun, J. H.; Cui, D. F.; Chen, X.; Zhang, L. L.; Cai, H. Y.; Li, H.

2013-02-01

20

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

21

Development of a catalytic combustion system for the MIT Micro Gas Turbine Engine  

E-print Network

As part of the MIT micro-gas turbine engine project, the development of a hydrocarbon-fueled catalytic micro-combustion system is presented. A conventionally-machined catalytic flow reactor was built to simulate the ...

Peck, Jhongwoo, 1976-

2003-01-01

22

Hot gas stream application in micro-bonding technique  

NASA Astrophysics Data System (ADS)

This paper presents a new concept for bonding micro-parts with dimensions in the range of 50 ?m to 300 ?m. Two different kinds of adhesives - polyurethane adhesive foil and hot melt glue - were applied to a basic substrate by different techniques. The focused and concentrated hot gas stream softened glue which had been applied in a solid state. Micro-parts were then embossed in the softened glue, or covered and shielded by it. In this way, a rigid and compact bond was obtained after cooling. For the positioning of micro-parts (optical fibers), it has been necessary to manufacture adequate V-grooves. Finite element analyses using the ANSYS TM program package were performed in order to evaluate parameters which govern the heat transfer to the adhesive and substrate respectively. Experimental results are in good agreement with results obtained by the numerical simulations. The advantages of this new approach are small system size, low capital costs, simple usage, applicability to many material combinations, easy integration into existing production lines, etc.

Andrijasevic, Daniela; Giouroudi, Ioanna; Smetana, Walter; Boehm, Stefan; Brenner, Werner

2006-01-01

23

Micro\\/nanoporous membrane based gas–water separation in microchannel  

Microsoft Academic Search

In this paper, a method coupling micro\\/nanoporous membranes with microchannels for the gas\\/water separation in microscale\\u000a has been demonstrated. The principle of separation is based on the basic properties of membranes—wetted micro\\/nanoporous hydrophilic\\u000a membranes can block gas due to a large water surface tension in the entrance of micro\\/nano pores to withstand the gas pressure,\\u000a while it allows water to

Xiaoshan Zhu

2009-01-01

24

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

25

On-Column Micro Gas Chromatography Detection with Capillary-Based Optical Ring Resonators  

E-print Network

On-Column Micro Gas Chromatography Detection with Capillary-Based Optical Ring Resonators Siyka I their utility. In contrast, in gas chromatography (GC), gaseous samples are separated based on their interaction

Fan, Xudong "Sherman"

26

Development of Micro-Heaters with Optimized Temperature Compensation Design for Gas Sensors  

PubMed Central

One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20ms, indicating a very high efficiency of pulse driving. PMID:22163756

Hwang, Woo-Jin; Shin, Kyu-Sik; Roh, Ji-Hyoung; Lee, Dae-Sung; Choa, Sung-Hoon

2011-01-01

27

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

28

A Micro Gas Sensor Using TiO2 Nanotubes to Detect Volatile Organic Compounds  

NASA Astrophysics Data System (ADS)

To develop a portable gas sensor with low power consumption, we deposited a micro size sensing film (100×100 µm2) on a Si substrate with an integrated micro heater and electrodes constructed using micro-electro-mechanical system (MEMS) technology. TiO2 nanotubes ca. 500 nm long with a 50 nm diameter were used to sense and detect volatile organic compounds (VOCs). We demonstrate that the MEMS sensor responded well to ethanol and toluene in air at elevated temperatures, such as 500 °C, which suggests that it is a promising battery-operable micro gas sensor for detecting VOCs.

Kida, Tetsuya; Seo, Min-Hyun; Suematsu, Koichi; Yuasa, Masayoshi; Kanmura, Yuichi; Shimanoe, Kengo

2013-04-01

29

Storage sizing for embedding of local gas production in a micro gas grid  

NASA Astrophysics Data System (ADS)

In this paper we study the optimal control of a micro grid of biogas producers. The paper considers the possibility to have a local storage device for each producer, who partly consumes his own production, i.e. prosumer. In addition, connected prosumers can sell stored gas to create revenue from it. An optimization model is employed to derive the size of storage device and to provide a pricing mechanism in an effort to value the stored gas. Taking into account physical grid constraints, the model is constructed in a centralized scheme of model predictive control. Case studies show that there is a relation between the demand and price profiles in terms of peaks and lows. The price profiles generally follow each other. The case studies are employed as well to to study the impacts of model parameters on deriving the storage size.

Alkano, D.; Nefkens, W. J.; Scherpen, J. M. A.; Volkerts, M.

2014-12-01

30

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

31

GAS PHASE EXPOSURE HISTORY DERIVED FROM MATERIAL PHASE CONCENTRATION PROFILES USING SOLID PHASE MICRO-EXTRACTION  

EPA Science Inventory

EPA Identifier: F8P31059 Title: Gas Phase Exposure History Derived from Material Phase Concentration Profiles Using Solid Phase Micro-Extraction Fellow (Principal Investigator): Jonathan Lewis McKinney Institution: University of Missouri - ...

32

Recognizing indoor formaldehyde in binary gas mixtures with a micro gas sensor array and a neural network  

Microsoft Academic Search

Low-concentration formaldehyde (HCHO) together with ethanol\\/toluene\\/acetone\\/alpha-pinene (as an interference gas of HCHO) is detected with a micro gas sensor array, composed of eight tin oxide (SnO2) thin film gas sensors with Au, Cu, Pt or Pd metal catalysts. The characteristics of the multi-dimensional signals from the eight sensors are evaluated. A multilayer neural network with an error backpropagation (BP) learning

Pin Lv; Zhenan Tang; Guangfen Wei; Jun Yu; Zhengxing Huang

2007-01-01

33

Gas/liquid sensing via chemotaxis of Euglena cells confined in an isolated micro-aquarium.  

PubMed

We demonstrate on-chip gas/liquid sensing by using the chemotaxis of live bacteria (Euglena gracilis) confined in an isolated micro-aquarium, and gas/liquid permeation through porous polydimethylsiloxane (PDMS). The sensing chip consisted of one closed micro-aquarium and two separated bypass microchannels along the perimeter of the micro-aquarium. Test gas/liquid and reference samples were introduced into the two individual microchannels separately, and the gas/liquid permeated through the PDMS walls and dissolved in the micro-aquarium water, resulting in a chemical concentration gradient in the micro-aquarium. By employing the closed micro-aquarium isolated from sample flows, we succeeded in measuring the chemotaxis of Euglena for a gas substance quantitatively, which cannot be achieved with the conventional flow-type or hydro-gel-type microfluidic devices. We found positive (negative) chemotaxis for CO2 concentrations below (above) 15%, with 64 ppm as the minimum concentration affecting the cells. We also observed chemotaxis for ethanol and H2O2. By supplying culture medium via the microchannels, the Euglena culture remained alive for more than 2 months. The sensing chip is thus useful for culturing cells and using them for environmental toxicity/nutrition studies by monitoring their motion. PMID:23934095

Ozasa, Kazunari; Lee, Jeesoo; Song, Simon; Hara, Masahiko; Maeda, Mizuo

2013-10-21

34

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

35

Micro-and nanostructured silicon-based superomniphobic surfaces.  

PubMed

We report on the fabrication of silicon nanostructured superhydrophobic and superoleophobic surfaces also called "superomniphobic" surfaces. For this purpose, silicon interfaces with different surface morphologies, single or double scale structuration, were investigated. These structured surfaces were chemically treated with perfluorodecyltrichlorosilane (PFTS), a low surface energy molecule. The morphology of the resulting surfaces was characterized using scanning electron microscopy (SEM). Their wetting properties: static contact angle (CA) and contact angle hysteresis (CAH) were investigated using liquids of various surface tensions. Despite that we found that all the different morphologies display a superhydrophobic character (CA>150° for water) and superoleophobic behavior (CA ? 140° for hexadecane), values of hysteresis are strongly dependent on the liquid surface tension and surface morphology. The best surface described in this study was composed of a dual scale texturation i.e. silicon micropillars covered by silicon nanowires. Indeed, this surface displayed high static contact angles and low hysteresis for all tested liquids. PMID:24370432

Nguyen, Thi Phuong Nhung; Boukherroub, Rabah; Thomy, Vincent; Coffinier, Yannick

2014-02-15

36

Gas transport by thermal transpiration in micro-channels -- A numerical study  

SciTech Connect

A reliable micro gas pump is an essential element to the development of many micro-systems for chemical gas analyses. At Sandia, the authors are exploring a different pumping mechanism, gas transport by thermal transpiration. Thermal transpiration refers to the rarefied gas dynamics developed in a micro-channel with a longitudinal temperature gradient. To investigate the potential of thermal transpiration for gas pumping in micro-systems, the authors have performed simulations and model analysis to design micro-devices and to assess their design performance before the fabrication process. The effort is to apply ICARUS (a Direct Simulation Monte Carlo code developed at Sandia) to characterize the fluid transport and evaluate the design performance. The design being considered has two plenums at different temperatures (hot and cold) separated by a micro-channel of 0.1 micron wide and 1 micron long. The temperature difference between the two plenums is 30 kelvin. ICARUS results, a quasi-steady analysis, predicts a net flow through the micro-channel with a velocity magnitude of about 0.4 m/s due to temperature gradient at the wall (thermal creep flow) at the early time. Later as the pressure builds up in the hot plenum, flow is reversed. Eventually when the system reaches steady state equilibrium, the net flow becomes zero. The thermal creep effect is compensated by the thermo-molecular pressure effect. This result demonstrates that it is important to include the thermo-molecular pressure effect when designing a pumping mechanism based on thermal transpiration. The DSMC technique can model this complex thermal transpiration problem.

Wong, C.C.; Hudson, M.L.; Potter, D.L.; Bartel, T.J.

1998-08-01

37

Ion-Feedback Suppression for Gaseous Photomultipliers with Micro Pattern Gas Detectors  

NASA Astrophysics Data System (ADS)

Gaseous photomultiplier tubes (Gas-PMTs) with micro-pattern gas detectors (MPGDs) sensitive to visible light are under development. A micro-pattern gas detector of Kapton GEM is found to be incompatible with bi-alkali photocathode, while a glass capillary plate has no problem. A new production method for a hole type MPGD has been developed. In the development of Gas-PMTs the suppression of ion-feedback is crucial because the ion-feedback limits the gain of the Gas-PMT and cause aging effects of the photocathode. Studies on ion-feedback suppression using a simulation with Gar?eld and Maxwell 3D programs are presented.

Matsumoto, K.; Sumiyoshi, T.; Tokanai, F.; Sakurai, H.; Gunji, S.; Sugiyama, H.; Okada, T.

38

Fast temperature programmed sensing for micro-hotplate gas sensors  

Microsoft Academic Search

We describe an operating mode of a gas sensor that greatly enhances the capability of the device to determine the composition of a sensed gas. The device consists of a micromachined hotplate with integrated heater, heat distribution plate, electrical contact pads, and sensing film. The temperature programmed sensing (TPS) technique uses millisecond timescale temperature changes to modify the rates for

R. E. Cavicchi; J. S. Suehle; K. G. Kreider; M. Gaitan; P. Chaparala

1995-01-01

39

Gas flow in miniaturized nozzles for micro-thrusters  

Microsoft Academic Search

A new satellite philosophy, developed during the last two decades, suggests to make satellites smaller and lighter rather than bigger and heavier. In other words, large (?m3), single system satellites are being replaced by ?eets of small (?dm3), so-called micro-satellites. Future developmentsmay result in swarms ofmicro satellites ?ying through space in formation. Together they would perform the same tasks as

F. La Torre

2011-01-01

40

Environmental Barrier Coatings for Silicon-Based Ceramics  

NASA Technical Reports Server (NTRS)

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 ceramics, however, suffer from rapid surface recession in combustion environments due to volatilization of the silica scale via reaction with water vapor, a major product of combustion. Therefore, application of silicon-based ceramic components in the hot section of advanced gas turbine engines requires development of a reliable method to protect the ceramic from environmental attack. An external environmental barrier coating (EBC) is considered a logical approach to achieve protection and CP long-term stability. The first generation EBC consisted of two layers, mullite (3Al2O3-2SiO2) bond coat and yttria-stabilized zirconia (YSZ, ZrO2-8 Wt.% Y2O3) top coat. Second generation EBCs, with substantially improved performance compared with the first generation EBC, were developed in the NASA High Speed Research-Enabling Propulsion Materials (HSR-EPM) Program. The first generation EBC consisted of two layers, mullite (3Al2O3-2SiO2) bond coat and yttria-stabilized zirconia (YSZ, ZrO2-8 wt.% Y2O3) top coat. Second generation EBCs, with substantially improved performance compared with the first generation EBC, were developed in the NASA High Speed Research-Enabling Propulsion Materials (HSR-EPM) Program (5). They consist of three layers, a silicon first bond coat, a mullite or a mullite + BSAS (BaO(1-x)-SrO(x)-Al2O3-2SiO2) second bond coat, and a BSAS top coat. The EPM EBCs were applied on SiC/SiC CMC combustor liners in three Solar Turbines (San Diego, CA) Centaur 50s gas turbine engines. The combined operation of the three engines has accumulated over 24,000 hours without failure (approximately 1,250 C maximum combustor liner temperature), with the engine in Texaco, Bakersfield, CA, accumulating about 14,000 hours. As the commercialization of Si-based ceramic components in gas turbines is on the horizon, a major emphasis is placed on EBCs for two reasons. First, they are absolute necessity for the protection of Si-based ceramics from water vapor. Second, they can enable a major enhancement in the performance of gas turbines by creating temperature gradients with the incorporation of a low thermal conductivity layer. Thorough understanding of current state-of-the-art EBCs will provide the foundation upon which development of future EBCs will be based. Phase stability and thermal conductivity of EPM EBCs are published elsewhere. This paper will discuss the chemical/environmental durability and silica volatility of EPM EBCs and their impact on the coating's upper temperature limit.

Lee, Kang N.; Fox, Dennis S.; Robinson, Raymond C.; Bansal, Narottam P.

2001-01-01

41

AMORPHOUS SILICON-BASED MINIMODULES WITH SILICONE ELASTOMER ENCAPSULATION  

E-print Network

AMORPHOUS SILICON-BASED MINIMODULES WITH SILICONE ELASTOMER ENCAPSULATION Aarohi Vijh 1 fabricated one and two cell, amorphous silicon based mini-modules encapsulated with a modern silicone. This yellowing upon exposure to UV light is a characteristic of most carbon-based polymers. Silicon

Deng, Xunming

42

Deng & Schiff, Amorphous Silicon Based Solar Cells rev. 7/30/2002, Page 1 Amorphous Silicon Based Solar Cells  

E-print Network

Deng & Schiff, Amorphous Silicon Based Solar Cells rev. 7/30/2002, Page 1 Amorphous Silicon Based Solar Cells Xunming Deng and Eric A. Schiff Table of Contents 1 Overview 3 1.1 Amorphous Silicon: The First Bipolar Amorphous Semiconductor 3 1.2 Designs for Amorphous Silicon Solar Cells: A Guided Tour 6

Deng, Xunming

43

Compatibility of RPECVD silicon dioxide with depletion gate materials for silicon-based nanostructures  

Microsoft Academic Search

The focus of this work has been upon deposited oxide and gate materials suitable for use in silicon-based nanostructures. The latter use e-beam patterned depletion gates in order to create three-dimensional confinement of electrons in the 2-dimensional electron gas of a metal-oxide-semiconductor field effect transistor (MOSFET) inversion layer. Remote Plasma Enhanced chemical Vapor Deposition (RPECVD) silicon dioxide was selected as

Mary Jo Rack

1998-01-01

44

Adaptable Chip-Level Microfluidic Packaging for a Micro-Scale Gas Chromatograph  

E-print Network

Adaptable Chip-Level Microfluidic Packaging for a Micro-Scale Gas Chromatograph Nathan Ward1 the microfluidic package with non-sorbent epoxy. The stability and efficacy of the integrated detector cell. Keywords-microfluidics; chip-level packaging; µGC; chemiresistor array I. INTRODUCTION AND MOTIVATIONS

Mason, Andrew

45

Micro gas bearings fabricated by deep X-ray lithography D. Kim, S. Lee, Y. Jin, Y. Desta, M. D. Bryant, J. Goettert  

E-print Network

Micro gas bearings fabricated by deep X-ray lithography D. Kim, S. Lee, Y. Jin, Y. Desta, M. D. Bryant, J. Goettert Abstract Micro bearing systems for Micro Electrome- chanical Systems (MEMS) have, frictionless bearings are needed, and in practice, micro gas bearings approach the ideal. Typically, bearings

Bryant, Michael D.

46

Silicon based microfluidic cell for terahertz frequencies  

NASA Astrophysics Data System (ADS)

We present a detailed analysis of the design, fabrication and testing of a silicon based, microfluidic cell, for transmission terahertz time-domain spectroscopy. The sensitivity of the device is tested through a range of experiments involving primary alcohol/water mixtures. The dielectric properties of these solutions are subsequently extracted using a Nelder-Mead search algorithm, and are in good agreement with literature values obtained via alternative techniques. Quantities in the order of 2 ?mol can be easily distinguished for primary alcohols in solution, even with the subwavelength optical path lengths used. A further display of the device sensitivity is shown through the analysis of commercial whiskeys, where there are clear, detectable differences between samples. Slight absorption variations were identified between samples of the same commercial brand, owing to a 2.5% difference in their alcoholic content. Results from data taken on subsequent days after system realignment are also presented, confirming the robustness of the technique, and the data extraction algorithm used. One final experiment, showing the possible use of this device to analyze aqueous biological samples is detailed; where biotin, a molecule known for its specific terahertz absorptions, is analyzed in solution. The device sensitivity is once again displayed, where quantities of 3 nmol can be clearly detected between samples.

Baragwanath, A. J.; Swift, G. P.; Dai, D.; Gallant, A. J.; Chamberlain, J. M.

2010-07-01

47

Micro-size gas turbines create market opportunities  

SciTech Connect

Power plants in the 25 to 250 kW-size range will enable utilities, IPPs and ESCOs to provide economic power for a variety of applications. Small, low-cost, highly efficient gas turbines provide the utility industry with a four-generation technology that features numerous benefits and potential applications. These include firm power to isolated communities, commercial centers and industries; peak shaving for utility systems to reduce the incremental cost of additional loads; peak shaving for large commercial and industrial establishments to reduce demand charges, as well as standby, emergency power and uninterruptible power supply (UPS).

Scott, W.G. [International Power and Light (United States)

1997-09-01

48

Micro gas preconcentrator made of a film of single-walled carbon nanotubes Shuji Takada*Takashi Nakai*Theerapol Thurakitseree*  

E-print Network

Micro gas preconcentrator made of a film of single-walled carbon nanotubes Shuji Takada-Jacques Delaunay*, *** and Ichiro Yamada*, *** The development of a micro gas preconcentrator is crucial for the realization of miniaturized gas chromatography (micro-GC) systems which are expected to open up new

Maruyama, Shigeo

49

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

NASA Astrophysics Data System (ADS)

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 and from iron nitrate solutions accurately dispersed on the substrates. Single-walled nanotubes with diameters as small as 1 nm, bridging polysilicon and silicon dioxide “pillars”, have been grown. The morphology and structure of CNTs have been characterized by SEM, AFM and Raman spectroscopy.

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

2007-03-01

50

Computational approaches to silicon-based nanostructures  

NASA Astrophysics Data System (ADS)

This study has three goals. First, we would like to develop computational tools that are suitable for the analysis and optimization of semiconductor device structures where quantum effects are important, as for example quantum wires and quantum dots but also ultra-narrow Metal-Oxide-Semiconductor (MOS) conduction channels at room temperature. Here, we describe these structures by the coupled system of the Schrodinger and the Poisson equation. We discuss solution strategies for both equations and outline an original iteration approach that uses a predictor-corrector procedure for solving the coupled system self-consistently. Second, we would like to apply these tools to investigate the lateral scalability limits of conduction channels in several MOS structures, at room temperature, with the goal to understand for which geometries and under which operating conditions a narrow channel approaching the quantum-wire limit can maintain reasonable isolation. We find that a good trade-off in performance and manufacturability is obtained for structures with T-shaped gate metallization. The calculations presented here also show that, depending on gate geometry and channel doping, it should be possible to operate a quasi-monomode silicon based quantum wire at room temperature. Finally, a full-band approach for the solution of Schrodinger's equation based on Fast Fourier Transforms is described. Using this simulation method, it becomes possible to solve Schrodinger's equation in the one band approximation for arbitrary band structures, putting a more complete description of high energy states and realistic temperatures within reach. Two example applications concerning non-parabolic effects in silicon quantum structures are presented, a MOS quantum capacitor and a MOS quantum cavity. Future directions for further extending this numerical method are discussed.

Trellakis, Alexandros

2000-10-01

51

Transient Flow Dynamics in Optical Micro Well Involving Gas Bubbles  

NASA Technical Reports Server (NTRS)

The Lab-On-a-Chip Application Development (LOCAD) team at NASA s Marshall Space Flight Center is utilizing Lab-On-a-Chip to support technology development specifically for Space Exploration. In this paper, we investigate the transient two-phase flow patterns in an optic well configuration with an entrapped bubble through numerical simulation. Specifically, the filling processes of a liquid inside an expanded chamber that has bubbles entrapped. Due to the back flow created by channel expansion, the entrapped bubbles tend to stay stationary at the immediate downstream of the expansion. Due to the huge difference between the gas and liquid densities, mass conservation issues associated with numerical diffusion need to be specially addressed. The results are presented in terms of the movement of the bubble through the optic well. Bubble removal strategies are developed that involve only pressure gradients across the optic well. Results show that for the bubble to be moved through the well, pressure pulsations must be utilized in order to create pressure gradients across the bubble itself.

Johnson, B.; Chen, C. P.; Jenkins, A.; Spearing, S.; Monaco, L. A.; Steele, A.; Flores, G.

2006-01-01

52

Mini and micro-gas turbines for combined heat and power  

Microsoft Academic Search

The use of mainframe gas turbines for power generation has increased in recent years and is likely to continue to increase. The proportion of power generation using combined heat and power is also growing mainly due to efficiency improvements and environmental benefits.Mini- and micro-turbines offer a number of potential advantages compared to other technologies for small-scale power generation, particularly for

P. A. Pilavachi

2002-01-01

53

Theoretical and Numerical Studies of Noncontinuum Gas-Phase Heat Conduction in Micro\\/Nano Devices  

Microsoft Academic Search

This article presents a comprehensive study of various modeling techniques for noncontinuum gas-phase heat conduction encountered in micro\\/nano devices over a broad range of Knudsen number. A new slip model is proposed for slip flows and an analytical approach is developed for collisionless steady-state heat conduction inside a fully diffuse enclosure. Excellent agreements with direct simulation Monte Carlo (DSMC) simulations

Taishan Zhu; Wenjing Ye

2010-01-01

54

COMPUTING THE NEAR-WALL REGION IN GAS MICRO AND NANOFLUIDICS: CRITICAL KNUDSEN LAYER PHENOMENA  

Microsoft Academic Search

In order to capture critical near-wall phenomena in gas micro- and nano?ows within conventional CFD codes, we present scaled Navier-Stokes-Fourier (NSF) constitu- tive relations. Our scaling is mathematically equivalent to applying an 'efiective' viscosity to the original constitutive relations. An expression for this 'efiective' transport coe-cient is obtained from the half-space Kramer's ?ow problem. The advantage of our model over

Jason M. Reese; Yingsong Zheng; Duncan A. Lockerbyy

2006-01-01

55

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

NASA Astrophysics Data System (ADS)

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 and one outlet and two opposite inlet channnels. The structure allows differences in the fluidic resistance and fluidic momentum inside the channels during each pump vibration cycle, which leads to the gas flow being rectified without valves. Before the Si micro-pump was developed, a prototype of it was fabricated using polymethyl methacrylate (PMMA) and a conventional machining techinique, and experiments on it confirmed the working principles underlying the pump. The Si micro-pump was designed and fabricated based on these working principles. The Si pump was composed of a Si flow channel plate and top and botom covers of PMMA. The flow channels were easily fabricated by using a silicon etching process. To investigate the effects of the step nozzle structure on the gas flow rate, two types of pumps with different channel depths (2D- and 3D-nozzle structures) were designed, and flow simulations were done using ANSYS-Fluent software. The simulations and excperimental data revealed that the 3D-nozzle structure is more advantageous than the 2D-nozzle structure. A flow rate of 4.3 ml/min was obtained for the pump with 3D-nozzle structure when the pump was driven at a resonant frequency of 7.9 kHz by a sinusoidal voltage of 40Vpp. A hot wire was fabricated as a gas-flow sensor near the outlet port on the Si wafer.

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

2008-12-01

56

Heat recovery from a micro-gas turbine by vapour jet refrigeration systems  

Microsoft Academic Search

The coproduction of electrical, thermal and refrigerating power is a well-known strategy which can significantly improve the efficiency of energy systems. Often in such tri-generation systems the refrigerating power is obtained by means of absorption cycles. This paper deals with the potential use of ejector-powered refrigerating cycles for heat recovery from a micro-gas turbine. At first, ejector performance is analyzed

Costante Invernizzi; Paolo Iora

2005-01-01

57

Efficient gas sensitivity in mixed bismuth ferrite micro (cubes) and nano (plates) structures  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Micro (cubes) structure embedded in nano (plates) of bismuth ferrite was prepared by a chemical method. ? These structures were characterized by XRD and SEM. ? LPG, CO{sub 2} and NH{sub 4} gases were exposed. ? Properties related to gas sensors were measured and reported. -- Abstract: Mixed micro (cubes) and nano (plates) structures of bismuth ferrite (BFO) have been synthesized by a simple and cost-effective wet-chemical method. Structural, morphological and phase confirmation characteristics are measured using X-ray diffraction, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis techniques. The digital FE-SEM photo-images of BFO sample confirmed an incubation of discrete micro-cubes into thin and regularly placed large number of nano-plates. The bismuth ferrite, with mixed structures, films show considerable performance when used in liquefied petroleum (LPG), carbon dioxide (CO{sub 2}) and ammonium (NH{sub 3}) gas sensors application. Different chemical entities in LPG have made it more efficient with higher sensitivity, recovery and response times compared to CO{sub 2} and NH{sub 3} gases. Furthermore, effect of palladium surface treatment on the gas sensitivity and the charge transfer resistances of BFO mixed structures is investigated and reported.

Waghmare, Shivaji D.; Jadhav, Vijaykumar V.; Gore, Shaym K. [Center for Nanomaterials and Energy Devices, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra (India)] [Center for Nanomaterials and Energy Devices, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra (India); Yoon, Seog-Joon; Ambade, Swapnil B. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Seoul 133-1791 (Korea, Republic of)] [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Seoul 133-1791 (Korea, Republic of); Lokhande, B.J. [Department of Physics, Solapur University, Solapur (India)] [Department of Physics, Solapur University, Solapur (India); Mane, Rajaram S., E-mail: rsmane_2000@yahoo.com [Center for Nanomaterials and Energy Devices, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra (India); Han, Sung-Hwan, E-mail: shhan@hanyang.ac.kr [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Seoul 133-1791 (Korea, Republic of)] [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Seoul 133-1791 (Korea, Republic of)

2012-12-15

58

MEMS & BioMEMS Chip-Scale Quadrupole Mass Filters for a Micro Gas Analyzer ...................................................................................................................MS.1  

E-print Network

MEMS & BioMEMS Chip-Scale Quadrupole Mass Filters for a Micro Gas Analyzer...................................................................................................................MS.2 MEMS-based Plasma Probes for Spacecraft Re-entry Monitoring.........................................................................MS.4 Direct Patterning of Metallic MEMS through Microcontact Printing

Reif, Rafael

59

A comparison of ground source heat pumps and micro-combined heat and power as residential greenhouse gas reduction strategies  

E-print Network

Both ground source heat pumps operating on electricity and micro-combined heat and power systems operating on fossil fuels offer potential for the reduction of green house gas emissions in comparison to the conventional ...

Guyer, Brittany (Brittany Leigh)

2009-01-01

60

Treatment to Control Adhesion of Silicone-Based Elastomers  

NASA Technical Reports Server (NTRS)

Seals are used to facilitate the joining of two items, usually temporarily. At some point in the future, it is expected that the items will need to be separated. This innovation enables control of the adhesive properties of silicone-based elastomers. The innovation may also be effective on elastomers other than the silicone-based ones. A technique has been discovered that decreases the level of adhesion of silicone- based elastomers to negligible levels. The new technique causes less damage to the material compared to alternative adhesion mitigation techniques. Silicone-based elastomers are the only class of rubber-like materials that currently meet NASA s needs for various seal applications. However, silicone-based elastomers have natural inherent adhesive properties. This stickiness can be helpful, but it can frequently cause problems as well, such as when trying to get items apart. In the past, seal adhesion was not always adequately addressed, and has caused in-flight failures where seals were actually pulled from their grooves, preventing subsequent spacecraft docking until the seal was physically removed from the flange via an extravehicular activity (EVA). The primary method used in the past to lower elastomer seal adhesion has been the application of some type of lubricant or grease to the surface of the seal. A newer method uses ultraviolet (UV) radiation a mixture of UV wavelengths in the range of near ultraviolet (NUV) and vacuum ultraviolet (VUV) wavelengths.

deGroh, Henry C., III; Puleo, Bernadette J.; Waters, Deborah L.

2013-01-01

61

Low-power-Consumption metal oxide NO2 gas sensor based on micro-heater and screen printing technology.  

PubMed

An NO2 micro gas sensor was fabricated based on a micro-heater using tin oxide nano-powders for effective gas detection and monitoring system with low power consumption and high sensitivity. The processes of the fabrication were acceptable to the conventional CMOS processes for mass-production. Semiconducting SnO2 nano-powders were synthesized via the co-precipitation method; and to increase the sensitivity of the NO2 gas rare metal dopants were added. In the structure of the micro-heater, the resistances of two semi-circular Pt heaters were connected to the spreader for thermal uniformity. The resistance of each heater becomes an electrically equal Wheatstone-bridge, which was divided in half by the heat spreading structure. Based on the aforementioned design, a low-power-consumption micro-heater was fabricated using the CMOS-compatible MEMS processes. A bridge-type micro-heater based on the Si substrate was fabricated via surface micro-machining. The NO2 sensing properties of a screen-printed tin oxide thick film device were measured The micro gas sensors showed substantial sensitivity down to 0.5 ppm NO2 at a low power consumption (34.2 mW). PMID:22966607

Moon, S E; Lee, H K; Choi, N J; Lee, J; Yang, W S; Kim, J; Jong, J J; Yoo, D J

2012-07-01

62

Packaging of a silicon-based biochip  

NASA Astrophysics Data System (ADS)

We present a sophisticated method for the packaging of a micro-electro-mechanical biochip, which leaves the sensitive surface area of the chip uncovered to allow for direct contact to aqueous environment. Together with adequate integration in a fluidic cartridge, the packaging method allows for the realization of a lab-on-chip (LOC). A fluidic interface to the cartridge is provided as well as electrical interfaces to the biochip electronics located in a readout instrument. The biochip features a central membrane and electrodes, both located in the central chip area, and bond pads distributed along the rim of the chip. The packaging method ensures a hermetic separation between the membrane sensing area interfaced to liquids and the bond pad area. Challenging was the fact that both, the freely moving membrane and the bond pads for electrical interconnection are positioned very close to each other on the same chip surface area. We mounted the biochip into a recess of a rigid printed circuit board and electrically connected it to the latter with a proprietary MicroFlex Interconnection (MFI) technology. A customized coating method using a specially shaped silicone casting-mold ensured a very thin, hermetic encapsulation, which left the membrane safe and freely accessible.

Velten, Thomas; Biehl, Margit; Haberer, Werner; Koch, Timo; Ortiz, Pedro; Keegan, Neil; Spoors, Julia; Hedley, John; McNeil, Calum

2009-02-01

63

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

64

Integration of a wave rotor to an ultra-micro gas turbine (UmuGT)  

NASA Astrophysics Data System (ADS)

Wave rotor technology has shown a significant potential for performance improvement of thermodynamic cycles. The wave rotor is an unsteady flow machine that utilizes shock waves to transfer energy from a high energy fluid to a low energy fluid, increasing both the temperature and the pressure of the low energy fluid. Used initially as a high pressure stage for a gas turbine locomotive engine, the wave rotor was commercialized only as a supercharging device for internal combustion engines, but recently there is a stronger research effort on implementing wave rotors as topping units or pressure gain combustors for gas turbines. At the same time, Ultra Micro Gas Turbines (UmuGT) are expected to be a next generation of power source for applications from propulsion to power generation, from aerospace industry to electronic industry. Starting in 1995, with the MIT "Micro Gas Turbine" project, the mechanical engineering research world has explored more and more the idea of "Power MEMS". Microfabricated turbomachinery like turbines, compressors, pumps, but also electric generators, heat exchangers, internal combustion engines and rocket engines have been on the focus list of researchers for the past 10 years. The reason is simple: the output power is proportional to the mass flow rate of the working fluid through the engine, or the cross-sectional area while the mass or volume of the engine is proportional to the cube of the characteristic length, thus the power density tends to increase at small scales (Power/Mass=L -1). This is the so-called "cube square law". This work investigates the possibilities of incorporating a wave rotor to an UmuGT and discusses the advantages of wave rotor as topping units for gas turbines, especially at microscale. Based on documented wave rotor efficiencies at larger scale and subsidized by both, a gasdynamic model that includes wall friction, and a CFD model, the wave rotor compression efficiency at microfabrication scale could be estimated at about 70%, which is much higher than the obtained efficiency obtained for centrifugal compressors in a microfabricated gas turbine. This dissertation also proposes several designs of ultra-micro wave rotors, including the novel concept of a radial-flow configuration. It describes a new and simplified design procedure as well as numerical simulations of these wave rotors. Results are obtained using FLUENT, a Computational Fluid Dynamics (CFD) commercial code. The vast information about the unsteady processes occurring during simulation is visualized. Last, two designs for experimental tests have been created, one for a micro shock tube and one for the ultra-micro wave rotor. Theoretical and numerical results encourage the idea that at microscale, compression by shock waves may be more efficient than by conventional centrifugal compressors, thus making the ultra-micro wave rotor (UmuWR) a feasible idea for enhancing (upgrading) UmuGT.

Iancu, Florin

2005-12-01

65

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

66

Direct observations of gas-hydrate formation in natural porous media on the micro-scale  

NASA Astrophysics Data System (ADS)

Gas hydrates (GH) are crystalline, inclusion compounds consisting of hydrogen-bonded water network encaging small gas molecules such as methane, ethane, CO2, etc (Sloan and Koh 2008). Natural gas hydrates are found worldwide in marine sediments and permafrost regions as a result of a reaction of biogenic or thermogenic gas with water under elevated pressure. Although a large amount of research on GH has been carried out over the years, the micro-structural aspects of GH growth, and in particular the contacts with the sedimentary matrix as well as the details of the distribution remain largely speculative. The present study was undertaken to shed light onto the well-established but not fully understood seismic anomalies, in particular the unusual attenuation of seismic waves in GH-bearing sediments, which may well be linked to micro-structural features. Observations of in-situ GH growth have been performed in a custom-build pressure cell (operating pressures up to several bar) mounted at the TOMCAT beam line of SLS/ PSI. In order to provide sufficient absorption contrast between phases and reduce pressure requirements for the cell we have used Xe instead of CH4. To the best of our knowledge this represents the first direct observation of GH growth in natural porous media with sub-micron spatial resolution and gives insight into the nucleation location and growth process of GH. The progress of the formation of sI Xe-hydrate in natural quartz sand was observed with a time-resolution of several minutes; the runs were conducted with an excess of a free-gas phase and show that the nucleation starts at the gas-water interface. Initially, a GH film is formed at this interface with a typical thickness of several ?m; this film may well be permeable to gas as suggested in the past - which would explain the rapid transport of gas molecules for further conversion of water to hydrate, completed in less than 20 min. Clearly, initially the growth is directed mainly into the liquid (and not into the gas phase as sometimes suggested). The observations of the 2D slices after full transformation show for all systems studied that hydrates tend to concentrate in the center of pore spaces and do not adhere in a systematic manner to quartz grains. Whether or not a thin film of water remained at the quartz-GH interface after completion of the reaction is presently under investigation. Sloan, E.D., Koh, C.A., (2008) Clathrate hydrates of natural gases. CRC Press, Boca Raton, FL.

Chaouachi, M.; Sell, K.; Falenty, A.; Enzmann, F.; Kersten, M.; Pinzer, B.; Saenger, E. H.; Kuhs, W. F.

2013-12-01

67

THETRIS: A MICRO-SCALE TEMPERATURE AND GAS RELEASE MODEL FOR TRISO FUEL  

SciTech Connect

The dominating mechanism in the passive safety of gas-cooled, graphite-moderated, high-temperature reactors (HTRs) is the Doppler feedback effect. These reactor designs are fueled with sub-millimeter sized kernels formed into TRISO particles that are imbedded in a graphite matrix. The best spatial and temporal representation of the feedback effect is obtained from an accurate approximation of the fuel temperature. Most accident scenarios in HTRs are characterized by large time constants and slow changes in the fuel and moderator temperature fields. In these situations a meso-scale, pebble and compact scale, solution provides a good approximation of the fuel temperature. Micro-scale models are necessary in order to obtain accurate predictions in faster transients or when parameters internal to the TRISO are needed. Since these coated particles constitute one of the fundamental design barriers for the release of fission products, it becomes important to understand the transient behavior inside this containment system. An explicit TRISO fuel temperature model named THETRIS has been developed and incorporated into the CYNOD-THERMIX-KONVEK suite of coupled codes. The code includes gas release models that provide a simple predictive capability of the internal pressure during transients. The new model yields similar results to those obtained with other micro-scale fuel models, but with the added capability to analyze gas release, internal pressure buildup, and effects of a gap in the TRISO. The analyses show the instances when the micro-scale models improve the predictions of the fuel temperature and Doppler feedback. In addition, a sensitivity study of the potential effects on the transient behavior of high-temperature reactors due to the presence of a gap is included. Although the formation of a gap occurs under special conditions, its consequences on the dynamic behavior of the reactor can cause unexpected responses during fast transients. Nevertheless, the strong Doppler feedback forces the reactor to quickly stabilize.

J. Ortensi; A.M. Ougouag

2011-12-01

68

Mass flow rate and pressure distribution of gas through three-dimensional micro-channels  

NASA Astrophysics Data System (ADS)

An effective method to predict the mass flow rate and pressure distribution of gas through three dimensional micro-channels with different cross-section shapes has been proposed. For rectangular cross sections often employed in experiment, the present solutions versus measured data of Zohar et al. (2002) show that the side walls significantly affect the mass flow rates as the aspect ratio is smaller than 10, whereas the non-dimensional pressure distributions, mainly determined by the inlet-to-outlet pressure ratio, are insensitive to the aspect ratio.

Jiang, Jianzheng; Fan, Jing

2014-12-01

69

A Smart Single-Chip Micro-Hotplate-Based Gas Sensor System in CMOS-Technology  

Microsoft Academic Search

This paper presents a monolithic chemical gas sensor system fabricated in industrial CMOS-technology combined with post-CMOS micromachining. The system comprises metal-oxide-covered (SnO2) micro-hotplates and the necessary driving and signal-conditioning circuitry. The SnO2 sensitive layer is operated at temperatures between 200 and 350°C. The on-chip temperature controller regulates the temperature of the membrane up to 350°C with a resolution of 0.5°C.

Diego Barrettino; Markus Graf; Martin Zimmermann; Christoph Hagleitner; Andreas Hierlemann; Henry Baltes

2004-01-01

70

Absorption line profile recovery based on TDLS and MEMS micro-mirror for photoacoustic gas sensing.  

PubMed

A novel and efficient absorption line recovery technique is presented. A micro-electromechanical systems (MEMS) mirror driven by an electrothermal actuator is used to generate laser intensity modulation through the mirror reflection. Tunable diode laser spectroscopy (TDLS) and photoacoustic spectroscopy (PAS) are used to recover the target absorption line profile which is compared with the theoretical Voigt profile. The target gas is 0.01% acetylene (C2H2) in a nitrogen host gas. The laser diode wavelength is swept across the P17 absorption line of acetylene at 1535.4 nm by a current ramp, and an erbium-doped fibre amplifier (EDFA) is used to enhance the optical intensity and increase the signal-to-noise ratio (SNR). A SNR of about 35 is obtained with 100 mW laser power from the EDFA. Good agreement is achieved between the experimental results and the theoretical simulation for the P17 absorption line profile. PMID:21942030

Li, Li; Arsad, Norhana; Stewart, George; Thursby, Graham; Uttamchandani, Deepak; Culshaw, Brian; Yi-ding, Wang

2011-07-01

71

Micro computed tomography and CFD simulation of drop deposition on gas diffusion layers  

NASA Astrophysics Data System (ADS)

Fuel cells are electrochemical power generation system which may achieve high energy efficiencies with environmentally friendly emissions. Among the different types, Proton Exchange Membrane fuel cells (PEMFC) seem at present one of the most promising choices. A very important component of a PEMFC is the gas diffusion layer (GDL), which has the primary role of managing water in the cell, allowing reactant gases transport to the catalyst layer while keeping the membrane correctly hydrated and preventing electrode flooding. Therefore, GDLs have to be porous and very hydrophobic. Carbon clothes or carbon papers coated with a hydrophobizing agent – typically a fluoropolymer – are used. Given the complex chemistry and morphology of the GDLs, wettability analyses on them present some critical issues when using the conventional contact angle measurement techniques. In this paper, the deposition of a drop on a GDL (produced using polytetrafluoroethylene-co-perfluoroalcoxy vinyl ether as the fluorinated polymer) was investigated by means of micro computed tomography (microCT) and numerical simulation. The microCT facility operational at the University of Bergamo was used to acquire a 3D tomography of a water drop deposed on a sample GDL. The reconstructed drop dataset allows thorough understanding of the real drop shape, of its contact area and contact line. The GDL dataset was used to create a realistic mesh for the numerical simulation of the drop deposition, which was performed using the OpenFOAM® interFOAM solver.

Guilizzoni, M.; Santini, M.; Lorenzi, M.; Knisel, V.; Fest-Santini, S.

2014-11-01

72

Porous silicon based narrow line-width rugate filters  

NASA Astrophysics Data System (ADS)

We report on the design and fabrication of porous silicon based rugate filters. We have achieved narrow line-width, high reflectivity optical filters made entirely from silicon by continuously varying of the refractive index of Si and apodizing the index profile of the structure.

Ilyas, S.; Böcking, T.; Kilian, K.; Reece, P. J.; Gooding, J.; Gaus, K.; Gal, M.

2007-02-01

73

Viscoelastic Properties of Silicone-Based Magnetorheological Elastomers  

Microsoft Academic Search

Magnetorheological (MR) elastomers are composite materials consisting of magnetic particles in elastomer matrices, whose mechanical properties can be influenced by applying a magnetic field. Main parameters which determine the behavior of these smart materials are the concentration of the magnetic particles and the mechanical stiffness of the elastomer matrix. The viscoelastic properties of silicone-based MR elastomers are outlined in terms

Holger Böse

2007-01-01

74

Numerical analysis of micro-/nanoscale gas-film lubrication of sliding surface with complicated structure  

NASA Astrophysics Data System (ADS)

It has been reported that the friction between a partially polished diamond-coated surface and a metal surface was drastically reduced to zero when they are slid at a few m/s. Since the sliding was noiseless, it seems that the diamond-coated surface was levitated over the counter surface and the sliding mechanism was the gas film lubrication. Recently, the mechanism of levitation of a slider with a micro/nanoscale surface structure on a rotating disk was theoretically clarified [S. Yonemura et al., Tribol. Lett., (2014), doi:10.1007/s11249-014-0368-2]. Probably, the partially polished diamond-coated surface may be levitated by high gas pressure generated by the micro/nanoscale surface structure on it. In this study, in order to verify our deduction, we performed numerical simulations of sliding of partially polished diamond-coated surface by reproducing its complicated surface structure using the data measured by an atomic force microscope (AFM). As a result, we obtained the lift force which is large enough to levitate the slider used in the experiment.

Kawagoe, Yoshiaki; Yonemura, Shigeru; Isono, Susumu; Takeno, Takanori; Miki, Hiroyuki; Takagi, Toshiyuki

2014-12-01

75

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

NASA Astrophysics Data System (ADS)

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 micro channel by using interferometry. The two side channels were served as gas entrances and they were both open to air and the channel outlet was being vacuumed during experiments. A Mach-Zehnder interference microscopy was built for the measurement of gas pressure drop along the mixing channel. Some points along the mixing channel were selected for interferometric measurements. Simulations were first developed in unsteady condition by using Ansys Fluent to verify the nonexistence of transient phenomena of gas flow in the defined condition and then run again in steady condition to get the theoretical pressure drop that was would be used for comparison with experimental results.

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

2012-05-01

76

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

77

Fault diagnosis for micro-gas turbine engine sensors via wavelet entropy.  

PubMed

Sensor fault diagnosis is necessary to ensure the normal operation of a gas turbine system. However, the existing methods require too many resources and this need can't be satisfied in some occasions. Since the sensor readings are directly affected by sensor state, sensor fault diagnosis can be performed by extracting features of the measured signals. This paper proposes a novel fault diagnosis method for sensors based on wavelet entropy. Based on the wavelet theory, wavelet decomposition is utilized to decompose the signal in different scales. Then the instantaneous wavelet energy entropy (IWEE) and instantaneous wavelet singular entropy (IWSE) are defined based on the previous wavelet entropy theory. Subsequently, a fault diagnosis method for gas turbine sensors is proposed based on the results of a numerically simulated example. Then, experiments on this method are carried out on a real micro gas turbine engine. In the experiment, four types of faults with different magnitudes are presented. The experimental results show that the proposed method for sensor fault diagnosis is efficient. PMID:22163734

Yu, Bing; Liu, Dongdong; Zhang, Tianhong

2011-01-01

78

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

79

Fault Diagnosis for Micro-Gas Turbine Engine Sensors via Wavelet Entropy  

PubMed Central

Sensor fault diagnosis is necessary to ensure the normal operation of a gas turbine system. However, the existing methods require too many resources and this need can’t be satisfied in some occasions. Since the sensor readings are directly affected by sensor state, sensor fault diagnosis can be performed by extracting features of the measured signals. This paper proposes a novel fault diagnosis method for sensors based on wavelet entropy. Based on the wavelet theory, wavelet decomposition is utilized to decompose the signal in different scales. Then the instantaneous wavelet energy entropy (IWEE) and instantaneous wavelet singular entropy (IWSE) are defined based on the previous wavelet entropy theory. Subsequently, a fault diagnosis method for gas turbine sensors is proposed based on the results of a numerically simulated example. Then, experiments on this method are carried out on a real micro gas turbine engine. In the experiment, four types of faults with different magnitudes are presented. The experimental results show that the proposed method for sensor fault diagnosis is efficient. PMID:22163734

Yu, Bing; Liu, Dongdong; Zhang, Tianhong

2011-01-01

80

Outdoor degradation of thin film amorphous silicon based PV modules  

NASA Astrophysics Data System (ADS)

One of the main problems in thin film silicon based modules is the deterioration of their performance upon exposure to light. The presented work focuses on a methodology for evaluation of thin-film photovoltaic module degradation behavior under real operating conditions. The outdoor degradation of double junction a-Si:H/a-Si:H modules was investigated using automated measurement setup for a period of two years. A deterioration of the module's maximum power was observed due to the well known Staebler-Wronski effect, which main causes are the decrease of open circuit voltage and the fill factor of the module. The obtained results can be correlated to the technology and construction of the thin film silicon based modules.

Berov, M.; Ivanov, P.; Tuytuyndziev, N.; Vitanov, P.

2014-12-01

81

Gas transport evaluation in lithium-air batteries with micro/nano-structured cathodes  

NASA Astrophysics Data System (ADS)

Inefficient gas transport in the porous cathode is disastrous for the lithium-air battery to achieve a high electrochemical performance. Previous evaluation of the cathode diffusivity relies on indirect calculations based on multiple V-I data obtained over the intact battery system, which inevitably induces evaluation uncertainty and material waste. In this report, an electrochemical device is designed for the out-of-cell diffusivity measurement in the lithium-air battery with micro/nano-sized cathodes. With the measured diffusivity, a few electrochemical parameters including the limiting current density and the concentration polarization associated with the porous cathodes can thus be directly evaluated. The work facilitates the development of highly-efficient cathode materials in the general field of metal-air battery field.

Wang, Xiaoning; Wen, Kechun; Song, Yuanqiang; Ye, Luhan; Zhang, Kelvin H. L.; Pan, Yu; Lv, Weiqiang; Liao, Yulong; He, Weidong

2015-01-01

82

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

83

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

84

Corrosion of silicon-based ceramics in combustion environments  

Microsoft Academic Search

Silicon-based ceramics and composites are prime candidates for heat engines and heat exchanger structural components. In such applications these materials are exposed to combustion gases and deposit-forming corrodents. In this paper combustion environments are defined for various applications. These environments lead to five main types of corrosive degradation: passive oxidation, deposit-induced corrosion, active oxidation, scale\\/substrate interactions, and scale volatility. Each

Nathan S. Jacobson

1993-01-01

85

Physics of amorphous silicon based alloy field-effect transistors  

Microsoft Academic Search

In this paper we develop a new theory to describe the characteristics of amorphous silicon based alloy field-effect transistors. We show that the transition from below to above threshold operation occurs when the Fermi level in the accumulation region moves from the deep to tail localized states in the energy gap. The current-voltage and capacitance-voltage characteristics are related to the

M. Shur; M. Hack

1984-01-01

86

Micro Econometric Modelling of Household Energy Use: Testing for Dependence between Demand for Electricity and Natural Gas  

Microsoft Academic Search

This paper contains a micro econometric analysis of household electricity and natural gas demand for a cross section of 2,885 Danish households observed in 1996. The sample includes fulltime employed couples in single-family houses. The specification of the model is guided by an explorative nonparametric data analysis. The analysis reveals, among other things, the fairly surprising result that demand for

Søren Leth-Petersen

2002-01-01

87

A micro-scale model for predicting contact resistance between bipolar plate and gas diffusion layer in PEM fuel cells  

Microsoft Academic Search

Contact resistance between the bipolar plate (BPP) and the gas diffusion layer (GDL) in a proton exchange membrane (PEM) fuel cell constitutes a significant portion of the overall fuel cell electrical resistance under the normal operation conditions. Most current methods for contact resistance estimation are experimental and there is a lack of well developed theoretical methods. A micro-scale numerical model

Y. Zhou; G. Lin; A. J. Shih; S. J. Hu

2007-01-01

88

Imaging gas and plasma interactions in the surface-chemical modification of polymers using micro-plasma jets  

Microsoft Academic Search

This paper reports on the correlation between gas flow and plasma behaviour in the outflow of a micro-atmospheric pressure plasma jet operating in helium using both 2D optical imaging and Schlieren photography. Schlieren photography shows that the helium outflow changes from laminar to turbulent conditions after distances between 20 and 50 mm from the nozzle. Above a flow rate of

Jun-Seok Oh; Olumuyiwa T. Olabanji; Craig Hale; Raffaello Mariani; Konstantinos Kontis; James W. Bradley

2011-01-01

89

Correlated column micro gas chromatography instrumentation for the vapor detection of contraband drugs in cargo containers  

NASA Astrophysics Data System (ADS)

We have developed an instrument based on Micro Gas Chromatography ((mu) GC) for rapid, handheld detection of vapor signatures from contraband drugs in cargo containers. For this application, a key requirement is the ability to distinguish the vapor signatures of contraband drugs against the highly variable chemical backgrounds encountered in cargo containers. To achieve this, we split the sample and run it simultaneously on two (mu) GCs with different stationary phases using correlated column chromatography. This effectively expands `detection space' and greatly enhances the chemical selectively. As part of this effort, we have also developed an extensive correlated chromatography database of chemical vapor signatures for both contraband drugs and representative backgrounds obtained by sampling incoming cargo containers under the supervision of U.S. Customs inspectors. Our experience shows that significant vapor buildup occurs in these containers resulting in strong and variable chemical backgrounds. Typical GC signatures observed have 10 - 20 strong components with a variable number of weaker components. The signatures reflect the very large variation in the contents and extent of packing of cargo containers, and show that vapor-based chemical detectors will require a large dynamic range to be effective. Gas chromatography is well suited for this. Furthermore it appears that a correlated (mu) GC instrument can provide rapid, handheld detection which fits into existing operational scenarios for the inspection of cargo containers for contraband.

Holland, Paul M.; Mustacich, Robert V.; Everson, James F.; Foreman, William; Leone, Michael; Sanders, Ann H.; Naumann, Walter J.

1994-10-01

90

X-ray Polarization Measurements with a Micro-pattern Gas Polarimeter  

NASA Technical Reports Server (NTRS)

The benefits of Astrophysical X-ray polarization measurements have been discussed in the literature for decades and with respect to a variety of detectors. Despite this, a dedicated polarimeter for the measurement of Astrophysical sources has not flown since the 1970's, when the definitive measurement of the Crab Nebula was made. More recently, an indirect measurement of the polarization of two gamma-ray bursts has been extracted from BATSE data, re-emphasizing the importance of polarization measurements in constraining a physical model. We describe a sensitive and, and extremely versatile, photoelectric polarimeter using a micro-pattern gas detector, with an 80micron pixel ASIC anode, to image the primary photoelectron track. The detector can be optimized to a preferred energy range between 1 keV and 50 keV. We present measurements of polarized 4.5 keV X-rays and unpolarized 6 keV X-rays obtained with a prototype detector using Carbon Dioxide gas.

Hill, J. E.; Black, J. K.; Deines-Jones, P.; Jahoda, K.; Bellazzini, R.; Brez, A.; Costa, E.; Kaaret, P.; Minuti, M.; Spandre, G.; Swank, J. H.

2006-01-01

91

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

92

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

93

Coating Silicon-Based Ceramics With Durable Mullite  

NASA Technical Reports Server (NTRS)

Improved plasma-spraying process deposits mullite on silicon carbide substrates. Prevents formation of amorphous mullite by maintaining high temperature of sprayed deposite to allow crystallization to occur. Deposited mullite adheres to substrate and exhibits little or no cracking during thermal cycling. Provides substantially greater resistance to oxidation in dry air and corrosion by molten salt. Process expected useful in depositing mullite on substrates made of other silicon-based ceramics and other ceramic substrates having coefficients of thermal expansion similar to those of mullite.

Miller, Robert A.; Jacobson, Nathan S.; Lee, Kang N.

1996-01-01

94

Thermal/environmental barrier coating system for silicon-based materials  

NASA Technical Reports Server (NTRS)

A coating system for a substrate containing a silicon-based material, such as silicon carbide-containing ceramic matrix materials containing silicon carbide and used to form articles exposed to high temperatures, including the hostile thermal environment of a gas turbine engine. The coating system includes a layer of barium strontium aluminosilicate (BSAS) as a bond coat for a thermal-insulating top coat. As a bond coat, the BSAS layer serves to adhere the top coat to a SiC-containing substrate. The BSAS bond coat exhibits sufficient environmental resistance such that, if the top coat should spall, the BSAS bond coat continues to provide a level of environmental protection to the underlying SiC-containing substrate.

Spitsberg, Irene T. (Inventor); Wang, Hongyu (Inventor)

1999-01-01

95

Simulating the charge dispersion phenomena in Micro Pattern Gas Detectors with a resistive anode  

NASA Astrophysics Data System (ADS)

The Time Projection Chamber (TPC) for the International Linear Collider (ILC) will need to measure about 200 track points with a transverse resolution close to 100 ?m. The resolution goal is beyond the capability of the conventional proportional wire/cathode pad TPC and Micro-Pattern Gas Detectors (MPGD) are being developed to meet the challenge. The standard MPGD readout techniques will, however, have difficulty in achieving the ILC-TPC resolution goal with the 2×6 mm 2 wide pads as was initially envisioned. Proposals for smaller width pads will improve the resolution but will require a larger number of readout channels and increase the TPC detector cost and complexity. The new MPGD readout concept of charge dispersion has the potential to achieve the ILC-TPC resolution goal without resorting to narrower pads. This was recently demonstrated in cosmic ray tests of a small prototype TPC read out with MPGDs using the charge dispersion technique. Here we describe the simulation of the charge dispersion phenomena for the MPGD-TPC. The detailed simulation includes initial ionization clustering, electron drift, diffusion effects, the intrinsic detector pulse-shape and electronics effects. The simulation is in excellent agreement with the experimental data and can be used to optimize the MPGD charge dispersion readout for the TPC.

Dixit, M. S.; Rankin, A.

2006-10-01

96

A silicon-based cluster state quantum computer  

E-print Network

It has been over ten years since Kane's influential proposal for a silicon-based nuclear spin quantum computer using phosphorous donors. Since then, silicon-based architectures have been refined as the experimental challenges associated with the original proposal have become better understood, while simultaneously a number of powerful and generic models for quantum computation have emerged. Here, I discuss how the cluster state or "one-way" model for quantum computing might be advantageously applied to donors in silicon, with the potential to substantially reduce the practical requirements of a successful implementation. The essence of the scheme is to use the electron spin associated with a donor to weave an entangled network between 31P donor nuclear spins. This resource has been shown to have exceptional coherence times and supports universal quantum computation through local measurements on the nuclear spins. Some of the key ingredients, such as global spin manipulation, have been robustly established, while others, such as single spin measurement, have seen much progress in recent years. A key challenge will be the demonstration of electron transfer between donors that preserves spin coherence.

John J. L. Morton

2009-05-25

97

Cooling performance of silicon-based thermoelectric device on high power LED  

Microsoft Academic Search

In this paper, a new thermal management application of silicon-based thermoelectric (TE) device on high power LED is unveiled. The silicon-based TE device is fabricated by the microfabrication and flip-chip assembly process. Thermal images photographed by infrared camera demonstrate the cooling function of the silicon-based TE devices. Because the LED chip is encapsulated in a package, the junction temperature of

Jen-Hau Cheng; Chun-Kai Liu; Yu-Lin Chao; Ra-Min Tain

2005-01-01

98

Effect of modifying micro-additions on the corrosion resistance of oil and gas pipeline welded joints  

Microsoft Academic Search

The effect of modifying additions of REE, AEE, and Zr on the corrosion resistance of oil and gas pipeline welded joints is\\u000a studied. Optimum concentrations are established for micro-additions of cerium, yttrium, calcium, barium, and zirconium to\\u000a fuzed metal providing good welded joint corrosion properties. Mathematical models are obtained for engineering and predicted\\u000a estimates of the service life for welded

V. D. Makarenko; I. O. Makarenko; A. N. Khalin; V. V. Ob’edkova; M. Yu. Mukhin; E. N. Galich

2009-01-01

99

Fabrication and ethanol-sensing properties of micro gas sensor based on electrospun SnO 2 nanofibers  

Microsoft Academic Search

SnO2 nanofibers were obtained by electrospinning of a poly(vinyl alcohol) (PVA)\\/SnCl4·5H2O solution. A novel micro gas sensor based on the SnO2 nanofibers was successfully fabricated. The morphology and crystal structure of the fibers were analyzed by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD), and the ethanol-sensing properties of the sensor were tested. The results showed

Yang Zhang; Xiuli He; Jianping Li; Zhenjiang Miao; Feng Huang

2008-01-01

100

Fabrication of a gas sensor array with micro-wells for VOCs gas sensing based on polymer/carbon nanotube thin films  

NASA Astrophysics Data System (ADS)

In this paper, gas sensor array with micro-well was designed and prepared by Micro Electro-Mechanical Systems (MEMS) technology. The micro-well and interdigital electrodes of sensor array were prepared using photolithography process, reactive ion etching (RIE) process, wet etching and conventional vacuum evaporation. In the manufacture process of the gas sensor array, KOH wet etching process was mainly discussed. The optimum etching processing parameters were as follows: 30 wt% KOH solution at 80 °C, a cooling back-flow device and a magnetic stirrer. The multi-walled carbon nanotubes (MWCNTs)-polyethyleneoxide (PEO) and MWNTs-Polyvinylpyrrolidone (PVP) composite films were utilized as sensitive layers to test gas-sensing properties. Response performances of MWCNTs- PEO and MWNTs-PVP composite films to toluene vapor and methanol vapor at room temperature were investigated. The results revealed that the sensor array showed a larger sensitivity to toluene vapor than to methanol vapor. In addition, the sensing mechanisms were studied as well.

Xie, Guangzhong; Xie, Tao; Zhu, Tao; Jiang, Yadong; Tai, Huiling

2014-08-01

101

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

102

Measurement of gas-liquid two-phase flow in micro-pipes by a capacitance sensor.  

PubMed

A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes. PMID:25587879

Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

2014-01-01

103

Measurement of Gas-Liquid Two-Phase Flow in Micro-Pipes by a Capacitance Sensor  

PubMed Central

A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes. PMID:25587879

Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

2014-01-01

104

Theory for hydrostatic gas journal bearings for micro-electro-mechanical systems  

E-print Network

The goal of the MIT micro-engine project is to develop high-speed rotating Power MEMS (Micro-Electro-Mechanical Systems) using computer chip fabrication technologies. To produce high power (10-50 W) in a small volume (less ...

Liu, Lixian, Ph. D. Massachusetts Institute of Technology

2005-01-01

105

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

106

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

107

A Highly Tunable Silicone-Based Magnetic Elastomer with Nanoscale Homogeneity.  

PubMed

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 which is a complex of a silicone polymer (polydimethylsiloxane-co-aminopropylmethylsiloxane) adsorbed onto the surface of magnetite (?-Fe(2)0(3)) 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 - 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. PMID:22184482

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

2012-02-01

108

A Highly Tunable Silicone-Based Magnetic Elastomer with Nanoscale Homogeneity  

PubMed Central

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 which is a complex of a silicone polymer (polydimethylsiloxane-co-aminopropylmethylsiloxane) adsorbed onto the surface of magnetite (?-Fe203) 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 – 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. PMID:22184482

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

2011-01-01

109

Mat. Res. Soc. Symp. Proc. Vol. 609 2000 Materials Research Society Preparation of Microcrystalline Silicon Based Solar Cells at High i-layer  

E-print Network

of Microcrystalline Silicon Based Solar Cells at High i-layer Deposition Rates Using a Gas Jet Technique S.J. Jones and other regions with a more randomly oriented microstructure. These materials have been used as i-layers thicker µc-Si i-layers in a similar amount of time to those used for high quality a-SiGe:H i-layers (rates

Deng, Xunming

110

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

111

External laser intensity modulation based on a MEMS micro-mirror for photo-acoustic gas sensing  

NASA Astrophysics Data System (ADS)

An external laser intensity modulation system based on a micro-electromechanical systems (MEMS) mirror is presented in this paper, for application to gas sensing. The micro mirror is driven by the electrothermal actuator. The rotation direction is decided by the relative position between the driving actuator and the axis of micro-mirror. In contrast to the traditional technique of current modulation of tunable diode lasers where wavelength modulation (WM) is combined with intensity modulation (IM), the IM can be separated from WM and wavelength tuning through the external modulation furnished by the mirror reflection. The MEMS mirror with 10?m thick structure material layer and 100nm thick gold coating is formed as a circular mirror with 2mm diameter. The mirror is attached to an electrothermal actuator and is fabricated on a chip that is wire-bonded and placed on a PCB holder. There are four electrothermal actuators orthogonal to each other that are connected to the circular mirror. Double-loop serpentine springs are used to attach the four actuators to the micro mirror. Each three-beam actuator is attached to a spring at one end that connects the actuator to the mirror and fixed to the substrate at the other end. The actuators are of two different types regarding length: 1.8 mm from hereon called the long actuator and 1.35 mm called the short actuator. Characterizing the frequency response and measuring the modulation performance of the MEMS mirror is presented in this work. Intensity modulation depth from very low values to about 100 percent can be achieved through adjusting the MEMS mirror's reflection position and driving voltage. The intensity-modulated laser source is used for photoacoustic gas sensing in order to recover the target gas absorption line profile based on tunable diode laser spectroscopy. The target gas is 1 percent acetylene balanced by nitrogen and the target absorption line is P17 of acetylene at 1535.39nm. Good agreement between experimental results and theoretical simulations is obtained.

Li, Li; Stewart, George; Thursby, Graham; Arsad, Norhana; Uttamchandani, Deepak; Culshaw, Brian; Wang, Yiding

2010-10-01

112

Investigation on the heat transfer characteristics during flow boiling of liquefied natural gas in a vertical micro-fin tube  

NASA Astrophysics Data System (ADS)

This paper presents an experimental investigation on the heat transfer characteristics of liquefied natural gas flow boiling in a vertical micro-fin tube. The effect of heat flux, mass flux and inlet pressure on the flow boiling heat transfer coefficients was analyzed. The Kim, Koyama, and two kinds of Wellsandt correlations with different Ftp coefficients were used to predict the flow boiling heat transfer coefficients. The predicted results showed that the Koyama correlation was the most accurate over the range of experimental conditions.

Xu, Bin; Shi, Yumei; Chen, Dongsheng

2014-03-01

113

Breakdown study of DC silicon micro-discharge L Schwaederle1  

E-print Network

on silicon based micro-cavity discharge devices carried out in helium at pressure ranging from 100 to 1000Breakdown study of DC silicon micro-discharge devices L Schwaederl´e1 , M K Kulsreshath1 , L J. The influence of geometrical and operating parameters on the electrical characteristics of dc micro-cavity

Paris-Sud XI, Université de

114

Optimized temperature modulation of micro-hotplate gas sensors through pseudorandom binary sequences  

Microsoft Academic Search

In recent years, modulating the working temperature of metal-oxide gas sensors has been one of the most widely used methods to enhance sensor selectivity. When the working temperature of a gas sensor is modulated, the kinetics of the gas-sensor interaction are altered, and this leads to characteristic response patterns. Many works have shown that it is possible to identify and

Alexander Vergara; Eduard Llobet; Jesús Brezmes; Xavier Vilanova; Peter Ivanov; Isabel Gràcia; Carles Cané; Xavier Correig

2005-01-01

115

Photocurable silicon-based materials for imprinting lithography  

NASA Astrophysics Data System (ADS)

Step and flash imprint lithography (SFIL) is low cost, high resolution patterning process and has found its way into a multitude of front end of the line (FEOL) and back end of the line (BEOL) applications. SFIL-R, a reverse tone variant of SFIL, and imprintable dielectrics are examples of such applications, and both require the design of specialized, silicon-based materials. Polyhedral oligomeric silsesquioxane (POSS) liquids were modified through a dual functionalization strategy to introduce photosensitive acrylate and thermally curable benzocyclobutane (BCB) groups to the molecule. The optimal functional group ratio was observed to be 3:5 acrylate to BCB, and the result was an imprintable dielectric with good mechanical properties and minimal post-exposure shrinkage. Thermal gravimetric analysis (TGA) revealed good thermal stability with minimal mass loss under annealing conditions of 400°C for 2 hours. Si-14 was designed to be a non-volatile, etch-resistant planarization layer for SFIL-R application. A polydimethylsiloxane (PDMS) derivative was modified to introduce acrylate functional groups and side branching for photosensitivity and low viscosity, respectively. Characterization of the material showed ideal planarization characteristics - low volatility (0.77 Torr at 25°C), low viscosity (15.1 cP), and minimal post-exposure shrinkage (5.1%).

Hao, Jianjun; Lin, Michael W.; Palmieri, Frank; Nishimura, Yukio; Chao, Huang-Lin; Stewart, Michael D.; Collins, Austin; Jen, Kane; Willson, C. Grant

2007-03-01

116

Development of new method of ?(13)C measurement for trace hydrocarbons in natural gas using solid phase micro-extraction coupled to gas chromatography isotope ratio mass spectrometry.  

PubMed

Compound specific isotope analysis (CSIA) of normal-level hydrocarbons (C1-C4) in natural gas is often successfully used in natural gas origin identification and classification, but little progress so far has been made for trace level hydrocarbons (C5-C14) in natural gas. In this study, we developed a method for rapid analysis of carbon isotopic ratios for trace hydrocarbons in natural gas samples. This method can be described as a combined approach characterized by solid phase micro-extraction (SPME) technique coupled to gas chromatography isotope ratio mass spectrometry (GC/IRMS). In this study, the CAR-PDMS fiber was chosen as the SPME adsorptive material after comparative experiments with other four fibers, and the parameters, including equilibration time, extraction temperature and desorption time, for efficient extraction of trace hydrocarbons were systematically optimized. The results showed the carbon isotopic fractionation was not observed as a function of equilibration time and extraction temperature. And the ?(13)C signatures determined by SPME-GC/IRMS were in good agreement with the known ?(13)C values of C5-C14 measured by GC-IRMS, and the accuracy is generally within ±0.5‰. Five natural gas samples were analyzed using this method, and the ?(13)C values for C5-C14 components were obtained with satisfied repeatability. The SPME-GC/IRMS approach fitted with CAR-PDMS fiber is well suited for the preconcentration of trace hydrocarbons and provides so far the most reliable carbon isotopic analysis for trace compounds in natural gas. PMID:25465020

Li, Zhongping; Wang, Xibin; Li, Liwu; Zhang, Mingjie; Tao, Mingxin; Xing, Lantian; Cao, Chunhui; Xia, Yanqing

2014-11-01

117

Micro-fabricated membrane gas valves with a non-stiction coating deposited by C4F8/Ar plasma  

NASA Astrophysics Data System (ADS)

Micro-fabricated gas valves with C4F8/Ar treatment at the sealing interface are designed, fabricated and characterized to passively control gases in a micro gas analysis system. The check valves form a seal between a polished Si/SiO2 substrate and a smooth polyimide (PI) membrane. The smooth PI membrane touches the SiO2 surface, giving rise to relatively strong van der Waals adhesion, and under humid conditions hydrogen-bonded stiction can occur at the interface between PI and SiO2. To prevent stiction from dominating adhesion, the valve-seat surface was treated with a hydrophobic CFn thin film, which was formed by exposing the surface to C4F8/Ar inductively coupled plasma (ICP) at low power. The valves without a non-stiction coating did not open with inlet pressures up to 210 kPa. With a non-stiction coating, the valves showed an average initial opening pressure of 59.25 kPa. In order to further reduce the opening pressure, 40% of the valve-seat area is reduced. After modification, the average opening pressure is reduced to 32.5 kPa. After the initial opening, the average in-use opening pressure was 16.9 kPa before area modification, and 13.1 kPa after the modification. The valve has been tested up to 10 000 open/close cycles under dry N2 gas flow, and an additional 3000 open/close cycles under humid N2 gas flow. The average forward flow conductance of the valves before modification was 1.1 sccm kPa-1, and the conductance after modification was 1.41 sccm kPa-1. The measured leakage is between 0.0003 and 0.004 sccm up to 35 kPa reverse pressure.

Han, Jeahyeong; Flachsbart, Bruce; Masel, Rich I.; Shannon, Mark A.

2008-09-01

118

Characteristic regimes of premixed gas combustion in high-porosity micro-fibrous porous media  

Microsoft Academic Search

Dynamical behaviour of the premixed flame propagating in the inert high-porosity micro-fibrous porous media has been studied numerically. Effects of mixture filtration velocity, equivalence ratio and burner transverse size on the flame structure have been investigated and the regions of existence of different combustion regimes have been determined. It was found that the influence of the hydrodynamic instability on the

R. Fursenko; S. Minaev; K. Maruta; H. Nakamura; H. Yang

2010-01-01

119

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

120

Nested potassium hydroxide etching and protective coatings for silicon-based microreactors  

E-print Network

We have developed a multilayer, multichannel silicon-based microreactor that uses elemental fluorine as a reagent and generates hydrogen fluoride as a byproduct. Nested potassium hydroxide etching (using silicon nitride ...

de Mas, Nuria

121

10.1098/rsta.2003.1221 Progress in silicon-based quantum computing  

E-print Network

10.1098/rsta.2003.1221 Progress in silicon-based quantum computing By R. G. Clark1 , R. Brenner1 Engineering and Telecommunications, University of New South Wales, Sydney 2052, Australia 3Centre for Quantum

Goan, Hsi-Sheng

122

Using a silicone-based dressing as a primary wound contact layer.  

PubMed

The use of silicone-based dressings as a primary contact layer for wound care can prevent epithelial stripping, pain and sensitivity and have been widely available for nearly 20 years. Cuticell Contact from BSN medical is the latest silicone-based dressing to add to the armoury of the wound care clinician. Using documented case studies the author explores the reasoning behind why clinicians should consider re-examining the use of silicone dressings. PMID:25382127

Derbyshire, Adam

2014-11-01

123

Fabrication of silicon-based shape memory alloy micro-actuators  

NASA Technical Reports Server (NTRS)

Thin film shape memory alloy has been integrated with silicon in a new actuation mechanism for microelectromechanical systems. This paper compares nickel-titanium film with other actuators, describes recent results of chemical milling processes developed to fabricate shape memory alloy microactuators in silicon, and describes simple actuation mechanisms which have been fabricated and tested.

Johnson, A. David; Busch, John D.; Ray, Curtis A.; Sloan, Charles L.

1992-01-01

124

Efficient and scalable single mode waveguide coupling on silicon based substrates  

NASA Astrophysics Data System (ADS)

One of the key challenges in Silicon based optical interconnect system remains to be the efficient coupling of optical signals from the submicron size on-chip waveguides to standard single mode (SM) fibers with low insertion loss (IL) and relaxed alignment tolerance. Large optical alignment tolerance allows optical connectors to be attached to on-chip waveguides passively using standard semiconductor pick-and-place assembly tools that have placement accuracies of 10- 15?m. To facilitate the assembly, optical fiber coupling elements need to be modular and compact. They have to also have low profile to avoid blocking air flow or mechanical interference with other elements of the package. In this paper we report the development of a two-dimensional (2D) SM optical fiber coupling architecture that consists of Si based photonic lightwave circuit (PLC) substrate and a high-density micro-lensed fiber optic connector. The system is compact, efficient and has large optical alignment tolerance. At 1300nm an insertion loss of 2.4dB and 1.5dB was measured for the PLC module and the fiber optic connector, respectively. When the PLC module and connector was aligned together, a total insertion loss of 7.8dB was demonstrated with x,y alignment tolerance of 40?m for 1dB optical loss. The SM optical coupling architecture presented here is scalable, alignment tolerant and has the potential to be manufactured in high volume. To our knowledge, such a system has not been reported in the literature so far.

Mohammed, E.; Tseng, R.; Rawlings, B.; Liff, S.; Ban, I.; McFarlane, W.; Reshotko, M.; Chang, P.

2014-03-01

125

Effect of Polytetrafluoroethylene (PTFE) and micro porous layer (MPL) on thermal conductivity of fuel cell gas diffusion layers: Modeling and  

E-print Network

Effect of Polytetrafluoroethylene (PTFE) and micro porous layer (MPL) on thermal conductivity-structural characteristics, additive materials such as Polytetrafluoroethylene (PTFE) and micro porous layer (MPL

Bahrami, Majid

126

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...

127

A low-power pressure-and temperature-programmed separation system for a micro gas chromatograph.  

SciTech Connect

This thesis presents the theory, design, fabrication and testing of the microvalves and columns necessary in a pressure- and temperature-programmed micro gas chromatograph ({micro}GC). Two microcolumn designs are investigated: a bonded Si-glass column having a rectangular cross section and a vapor-deposited silicon oxynitride (Sion) column having a roughly circular cross section. Both microcolumns contain integrated heaters and sensors for rapid, controlled heating. The 3.2 cm x 3.2 cm, 3 m-long silicon-glass column, coated with a non-polar polydimethylsiloxane (PDMS) stationary phase, separates 30 volatile organic compounds (VOCs) in less than 6 min. This is the most efficient micromachined column reported to date, producing greater than 4000 plates/m. The 2.7 mm x 1.4 mm Sion column eliminates the glass sealing plate and silicon substrate using deposited dielectrics and is the lowest power and fastest GC column reported to date; it requires only 11 mW to raise the column temperature by 100 C and has a response time of 11s and natural temperature ramp rate of 580 C/min. A 1 m-long PDMS-coated Sion microcolumn separates 10 VOCs in 52s. A system-based design approach was used for both columns.

Sacks, Richard D. (University of Michigan, Ann Arbor, MI); Robinson, Alex Lockwood (Advanced Sensor Technologies, Albuquerque, NM); Lambertus, Gordon R. (University of Michigan, Ann Arbor, MI); Potkay, Joseph A. (University of Michigan, Ann Arbor, MI); Wise, Kensall D. (University of Michigan, Ann Arbor, MI)

2006-10-01

128

Numerical analysis of gas separator with thermal transpiration in micro channels II  

NASA Astrophysics Data System (ADS)

A membrane gas separator which operates with only a small temperature difference across a membrane is designed, and its capability is numerically proved. The separator system consists of three Knudsen pumps - a motionless pump that utilizes the thermal transpiration of the rarefied gas. Each pump is composed of a porous membrane and one channel along each of the two surfaces of the membrane. Two of the pumps induce a variation of mole fraction using a combination of the thermal transpiration and pressure driven flow through the membrane, and the other one provides the former two pumps with a required pressure difference. This paper reports the first numerical calculations that demonstrate a neon-argon binary gas mixture can be separated into pure neon gas and argon gas with the proposed design. The temperature difference is no more than 90 K, and the total length of the membrane is ˜ 15 cm at standard ambient temperature and pressure. The production rate of the separator is proportional to the width of the membrane. For example, when the width is 10 cm, the flow rates of the product gases are 0.8 sccm for argon and 1.9 sccm for neon.

Nakaye, Shoeji; Sugimoto, Hiroshi

2014-12-01

129

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

130

Effect of micropillar density on separation efficiency of semi-packed micro gas chromatographic columns  

Microsoft Academic Search

In this report, the effect on the separation efficiency of the density of square micropillars in semi-packed gas chromatography columns are investigated. Two columns with the same pillar arrangement but different pillar density were experimentally characterized and simulated. The experimental results show that the high pillar density column is 1.2 times superior to the low pillar density column with respect

Sho Nishiyama; Takashi Nakai; Masaki Shuzo; Jean-Jacques Delaunay; Ichiro Yamada

2009-01-01

131

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...

132

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

133

Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph  

NASA Astrophysics Data System (ADS)

In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

2012-07-01

134

Micro- and nano-scale hollow TiO{sub 2} fibers by coaxial electrospinning: Preparation and gas sensing  

SciTech Connect

We report the preparation of micro- and nano-scale hollow TiO{sub 2} fibers using a coaxial electrospinning technique and their gas sensing properties in terms of CO. The diameter of hollow TiO{sub 2} fibers can be controlled from 200 nm to several micrometers by changing the viscosity of electrospinning solutions. Lower viscosities produce slim hollow nanofibers. In contrast, fat hollow microfibers are obtained in the case of higher viscosities. A simple mathematical expression is presented to predict the change in diameter of hollow TiO{sub 2} fibers as a function of viscosity. The successful control over the diameter of hollow TiO{sub 2} fibers is expected to bring extensive applications. To test a potential use of hollow TiO{sub 2} fibers in chemical gas sensors, their sensing properties to CO are investigated at room temperature. - Graphical abstract: Microstructures of as-prepared and calcined hollow TiO{sub 2} fibers prepared by the electrospinning technique with a coaxial needle. Dynamic response at various CO concentrations for the sensor fabricated with the hollow TiO{sub 2} fibers. Highlights: > Hollow TiO{sub 2} fibers were synthesized using a coaxial electrospinning technique. > Their diameter can be controlled by changing the viscosity of electrospinning solutions. > Lower viscosities produce slim hollow nanofibers. > In contrast, fat hollow microfibers are obtained in the case of higher viscosities. > Successful control over the diameter of hollow TiO{sub 2} fibers will bring extensive applications.

Zhang Jin; Choi, Sun-Woo [School of Materials Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Kim, Sang Sub, E-mail: sangsub@inha.ac.kr [School of Materials Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of)

2011-11-15

135

A programmable palm-size gas analyzer for use in micro-autonomous systems  

NASA Astrophysics Data System (ADS)

Gas analysis systems having small size, low power, and high selectivity are badly needed for defense (detection of explosives and chemical warfare agents), homeland security, health care, and environmental applications. This paper presents a palm-size gas chromatography system having analysis times of 5-50sec, detection limits less than 1ppb, and an average power dissipation less than one watt. It uses no consumables. The three-chip fluidic system consists of a preconcentrator, a 25cm-3m separation column, and a chemi-resistive detector and is supported by a microcomputer and circuitry for programmable temperature control. The entire system, including the mini-pump and battery, occupies less than 200cc and is configured for use on autonomous robotic vehicles.

Gordenker, Robert J. M.; Wise, Kensall D.

2012-06-01

136

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

137

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

138

SQI-CMOS based single crystal silicon micro-heaters for gas sensors  

Microsoft Academic Search

Here we report on novel high temperature gas sensors that have been fabricated using an SOI (silicon-on-insulator) -CMOS process and deep RIE back-etching. These sensors offer ultra-low power consumption, low unit cost, and excellent thermal stability. The highly-doped single crystal silicon (SCS) layer of a standard SOI-CMOS process, which is traditionally used to form the source and drain regions of

T. Iwaki; J. A. Covington; J. W. Gardner; F. Udrea; C. S. Blackman; I. P. Parkin

2006-01-01

139

Stresa, Italy, 26-28 April 2006 RECENT DEVELOPMENTS IN MEMS-BASED MICRO FUEL CELLS  

E-print Network

Stresa, Italy, 26-28 April 2006 RECENT DEVELOPMENTS IN MEMS-BASED MICRO FUEL CELLS Tristan Pichonat ABSTRACT Micro fuel cells (µ-FC) represent promising power sources for portable applications. Today, one describes the latest developments of a new porous silicon- based miniature fuel cell. Using a silane grafted

Boyer, Edmond

140

Silicon-based two dimensional tunable photonic crystal devices  

NASA Astrophysics Data System (ADS)

Photonic crystal devices are capable of controlling the flow of light in ultra compact scales. Silicon two dimensional (2D) nanostructures are well developed in the integrated circuit (IC) industry. Silicon is transparent to infrared light and has high refractive index which makes silicon an ideal material for photonic crystals in the infrared spectrum. Silicon 2D photonic crystals have attracted a lot of interest for showing feasibility of photonic integrated circuits. Typical photonic crystal devices are waveguides or cavities, which were developed as mostly passive devices. Various methods can be used to make photonic crystals tunable. In this work, silicon 2D tunable photonic crystal devices are studied using thermo-optic effect of silicon. In addition, this research presents one-step lithography to form micro and nano combined structures for the two-dimensional slab photonic crystals.

Choi, Kyung-Hak

141

Calibration of solid-phase micro-extraction for quantitative analysis by gas chromatography.  

PubMed

Calibration of SPME by the injection of liquid standard solution is a common method for SPME quantitative analysis by gas chromatography. The feasibility of this calibration method relies on the assumption that sample transfer efficiencies are the same for both the liquid injection and the SPME fiber injection. Sample transfer efficiencies for liquid injection and SPME fiber injection were studied in this paper. The results showed that the sample transfer efficiency for liquid injection was affected by several factors, such as the dimensions of the liner, the presence of the wool, and the temperature of the injector. The sample transfer efficiency for SPME fiber injection was affected by the cross-sectional area of the space between the column and the liner, the carrier gas flow rate, and the length of the column inside the liner. An equation was proposed to estimate the sample loss rate for SPME injection. It was found that the use of a direct injection (DI) liner and program temperature vaporizing provides high sample transfer efficiencies, for both liquid injection and SPME fiber injection. When a common SPME straight liner is used, large outer diameter (o.d.) pre-column will help to achieve high sample transfer efficiency. PMID:16298180

Ouyang, Gangfeng; Chen, Yong; Setkova, Lucie; Pawliszyn, Janusz

2005-12-01

142

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

143

A finite element analysis of a silicon based double quantum dot structure  

E-print Network

We present the results of a finite-element solution of the Laplace equation for the silicon-based trench-isolated double quantum-dot and the capacitively-coupled single-electron transistor device architecture. This system is a candidate for charge and spin-based quantum computation in the solid state, as demonstrated by recent coherent-charge oscillation experiments. Our key findings demonstrate control of the electric potential and electric field in the vicinity of the double quantum-dot by the electric potential applied to the in-plane gates. This constitutes a useful theoretical analysis of the silicon-based architecture for quantum information processing applications.

S. Rahman; J. Gorman; C. H. W. Barnes; D. A. Williams; H. P. Langtangen

2005-12-21

144

A novel porous silicon-based multilayer dielectric-grating structures for diffraction-based sensing  

NASA Astrophysics Data System (ADS)

Porous silicon material and device has attracted more attention for use as biochemical optical sensors. In this paper, A novel porous silicon-based multilayer dielectric-grating structures by adding high-reflectivity porous silicon stacks between the substrate and grating was fabricated, and the porous silicon grating height was set to be about 200 nm, the grating period was 4 ?m, the air filling factor was 50%. A new better method of preparing this porous silicon-based multilayer dielectric-grating structures have also been employed.

Mo, Jiaqing; Liu, Yajun; Lv, Changwu; Lv, Xiaoyi; Jia, Zhenhong

2014-11-01

145

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

2013-03-01

146

PCB-integrated metallic thermal micro-actuators  

Microsoft Academic Search

The development of thermal micro-actuators on printed circuit boards is described. The fabricated metal actuators are shown to have similar displacement characteristics when compared with silicon-based devices described in the literature. The actuators are benchmarked with respect to power consumption, stroke, and response time. It is further demonstrated that simple analytical estimates for the response time are in good agreement

Eniko T. Enikov; Kalin Lazarov

2003-01-01

147

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

148

Thermal Balance Analysis of a Micro-Thermoelectric Gas Sensor Using Catalytic Combustion of Hydrogen  

PubMed Central

A thermoelectric gas sensor (TGS) with a combustion catalyst is a calorimetric sensor that changes the small heat of catalytic combustion into a signal voltage. We analyzed the thermal balance of a TGS to quantitatively estimate the sensor parameters. The voltage signal of a TGS was simulated, and the heat balance was calculated at two sections across the thermoelectric film of a TGS. The thermal resistances in the two sections were estimated from the thermal time constants of the experimental signal curves of the TGS. The catalytic combustion heat Qcatalyst required for 1 mV of ?Vgas was calculated to be 46.1 ?W. Using these parameters, we find from simulations for the device performance that the expected Qcatalyst for 200 and 1,000 ppm H2 was 3.69 ?W and 11.7 ?W, respectively. PMID:24451468

Nagai, Daisuke; Akamatsu, Takafumi; Itoh, Toshio; Izu, Noriya; Shin, Woosuck

2014-01-01

149

Heterogeneous metal-oxide nanowire micro-sensor array for gas sensing  

NASA Astrophysics Data System (ADS)

Vanadium oxide, manganese oxide, tungsten oxide, and nickel oxide nanowires were investigated for their applicability as chemiresistive gas sensors. Nanowires have excellent surface-to-volume ratios which yield higher sensitivities than bulk materials. Sensing elements consisting of these materials were assembled in an array to create an electronic nose platform. Dielectrophoresis was used to position the nanomaterials onto a microfabricated array of electrodes, which was subsequently mounted onto a leadless chip carrier and printed circuit board for rapid testing. Samples were tested in an enclosed chamber with vapors of acetone, isopropanol, methanol, and aqueous ammonia. The change in resistance of each assembly was measured. Responses varied between nanowire compositions, each demonstrating unique and repeatable responses to different gases; this enabled direct detection of the gases from the ensemble response. Sensitivities were calculated based on the fractional resistance change in a saturated environment and ranged from 6 × 10-4 to 2 × 10-5%change ppm-1.

DeMeo, Dante; MacNaughton, Sam; Wang, Zhilong; Zhang, Xinjie; Sonkusale, Sameer; Vandervelde, Thomas E.

2014-04-01

150

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

151

The Response of a Gas in a Micro-channel to Periodic Boundary Heating  

NASA Astrophysics Data System (ADS)

We study the flow-field generated in a one-dimensional wall-bounded gas layer due to periodic small-amplitude time variation in the temperature of its boundaries. We focus on the Navier-Stokes limit, where the layer width is large compared to the mean free path and the characteristic time-scale of temperature variations is long compared with the mean free time between collisions. The viscous-compressible Navier-Stokes equations with slip-flow boundary conditions are solved analytically for the case of sinusoidal heating. The analysis is then extended to study the system response to arbitrary periodic heating. Results are presented for both triangle- and square-wave heating profiles. These solutions are found to be in good agreement with low-variance Monte-Carlo simulations of the Boltzmann equation, validating the present analysis as an accurate and simple alternative to expensive molecular computations. In addition, the analysis is applied for quantitative examination of the conditions for breakdown of the slip-flow description in non-isothermal flows.

Manela, Avshalom; Radtke, Gregg A.

2011-05-01

152

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

153

Acoustic phonon engineering of thermal properties of silicon-based nanostructures  

E-print Network

Acoustic phonon engineering of thermal properties of silicon- based nanostructures N D Zincenco1@ee.ucr.edu Abstract. We have theoretically studied the influence of the nanostructure cladding materials on the phonon this model we have shown that the nanostructure claddings with the low sound velocity decrease the phonon

154

Silicon Based Double-layer 1x12 Multimode Interference Coupler for Three-dimensional  

E-print Network

Silicon Based Double-layer 1x12 Multimode Interference Coupler for Three-dimensional Photonic-chip vertically integrated three-dimensional (3D) photonic integrated circuit (PIC). Double-layer 1x12 multimode using double-bonded silicon-on-insulator (SOI) wafers. Double-layer 1x12 Multimode Interference (MMI

Chen, Ray

155

Sensitivity analysis of packaging effect of silicon-based piezoresistive pressure sensor  

Microsoft Academic Search

The silicon-based pressure sensor is one of the major applications in the MEMS device. Nowadays, the silicon piezoresistive pressure sensor is a mature technology in the industry, but its requirement in terms of sensing accuracy and stability is more rigorous than that of many advanced applications. The major factor affecting the sensing stability of the piezoresistive pressure sensor is its

Tsung-Lin Chou; Chen-Hung Chu; Chun-Te Lin; Kuo-Ning Chiang

2009-01-01

156

Tunable silicon-based light sources using erbium doped liquid crystals S. M. Weissa  

E-print Network

Tunable silicon-based light sources using erbium doped liquid crystals S. M. Weissa Department for the tunable light sources consist of porous silicon microcavities infiltrated with erbium doped nematic liquid crystals. Erbium ions are the luminescence source, porous silicon microcavities narrow the emission band

Weiss, Sharon

157

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. PMID:23293392

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

2012-01-01

158

Performance study of silica-on-silicon based multimode interference (MMI) optical coupler  

NASA Astrophysics Data System (ADS)

In recent years, the silica-on-silicon based multimode interference (MMI) optical waveguide is an interesting research topic. It is being advanced various researches on the silica based MMI coupler. This paper represents the considerations of the optimal design of the silica-on-silicon based MMI optical coupler for better performance. For that, we have illustrated the simulation results on a particular case of the 4×4 silica-on-silicon based MMI coupler. From the simulation results, it is seen that the performance of the MMI coupler depends on multiple width and length combinations of the MMI waveguide. The results also show that the width of the multimode waveguide could not be too small or too large for optimal performance, and at the widths, 100 ?m, 120 ?m and 130 ?m, the performance could be optimized and be almost 0.62-0.64 in a given length range. Finally, the results have been compared with the optical coupler presently available in the market and show that the silica-on-silicon based MMI coupler is much more efficient in terms of losses and the performance associated with it and the size of the coupler.

Chowdhury, A. Zahed

2014-03-01

159

Design and Optimization of Silicon-Based Patch Antennas Using Time-Domain Techniques  

E-print Network

Design and Optimization of Silicon-Based Patch Antennas Using Time-Domain Techniques G. DeJean, N. Bushyager, E. Dalton, M. M. Tentzeris, and J. Papapolymerou Georgia Electronic Design Center, School of ECE-based microstrip patch antenna are presented. The antenna structure includes an additional layer of low

Papapolymerou, Ioannis "John"

160

Scaling laws for thermal conductivity of crystalline nanoporous silicon based on molecular dynamics simulations  

E-print Network

was predicted using non-equilibrium molecular dynamics simulations. The Stillinger-Weber potential for silicon predicted by molecular dynamics simulations for spherical pores (present study) as well as for cylindricalScaling laws for thermal conductivity of crystalline nanoporous silicon based on molecular dynamics

Pilon, Laurent

161

A Comparative Efficiency Study of Silicon-based Solid State Transformers  

E-print Network

Terms--Solid State Transformer, Efficiency, Soft Switch- ing I. INTRODUCTION Power electronic converter-based with four-level flying capacitor front end; and (4) a single-stage ac-ac DAB converter-based SST (SST4A Comparative Efficiency Study of Silicon-based Solid State Transformers Hengsi Qin and Jonathan W

Kimball, Jonathan W.

162

High Efficiency and High Rate Deposited Amorphous Silicon-Based Solar Cells  

E-print Network

1 High Efficiency and High Rate Deposited Amorphous Silicon-Based Solar Cells PHASE I Annual Rate Deposition of Amorphous Silicon Films Using Hot-Wire CVD With Coil- Shaped Filament Section 5 Phase Diagram for Deposition of Amorphous and Microcrystalline Silicon #12;3 List of Figures Figure 2

Deng, Xunming

163

Hyperuniformity in amorphous silicon based on the measurement of the infinite-wavelength limit  

E-print Network

Hyperuniformity in amorphous silicon based on the measurement of the infinite-wavelength limit-purity amorphous-silicon (a-Si) samples for the purpose of determining their degree of hyperuniformity. A perfectly patterns using a "collec- tive-coordinate" approach (4). Determining where amorphous silicon falls

Torquato, Salvatore

164

A novel micro-structure ethanol gas sensor with low power consumption based on La 0.7Sr 0.3FeO 3  

Microsoft Academic Search

A micro-structure ethanol gas sensor on a silicon substrate based on the nano complex oxide La0.7Sr0.3FeO3 was successfully designed and fabricated. The heater electrode and signal electrode were designed on the same plane in order to reduce the cross-talk and make the fabrication easier. The results of the simulations are used to improve the temperature distribution on the sensor. Compared

L. Liu; Tong Zhang; Q. Qi; Lei Zhang; Weiyou Chen; Baokun Xu

2007-01-01

165

Miniaturized GC/MS instrumentation for in situ measurements: micro gas chromatography coupled with miniature quadrupole array and paul ion trap mass spectrometers  

NASA Technical Reports Server (NTRS)

Miniaturized chemical instrumentation is needed for in situ measurements in planetary exploration and other spaceflight applications where factors such as reduction in payload requirements and enhanced robustness are important. In response to this need, we are 'continuing to develop miniaturized GC/MS instrumentation which combines chemical separations by gas chromatography (GC) with mass spectrometry (MS) to provide positive identification of chemical compounds in complex mixtures of gases, such as those found in the International Space Station's cabin atmosphere. Our design approach utilizes micro gas chromatography components coupled with either a miniature quadrupole mass spectrometer array (QMSA) or compact, high-resolution Paul ion trap.

Holland, P.; Chutjian, A.; Darrach, M.; Orient, O.

2002-01-01

166

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

167

Some recent advances in multi-material micro- and nano-manufacturing  

Microsoft Academic Search

The increasing demand for micro-products and components can be met only partly by the lithography-based micro-electromechanical\\u000a systems fabrication processes that originated from the silicon-based microelectronics revolution of the late twentieth century.\\u000a In particular, such processes have limitations when applied to new micro-devices which require the use of a variety of materials\\u000a and complex 3D microstructures with high aspect ratios. In

E. B. Brousseau; S. S. Dimov; D. T. Pham

2010-01-01

168

Micro mechatronics and micro actuators  

Microsoft Academic Search

Micro mechatronics is the synergetic integration of both mechanical and electronic systems based on scaling effects in the micro world. A micro mechatronics system is expected to be the key component of the mechanical system, such as in electronic automotive technologies. Micro mechatronics requires the organic combination of micro devices such as micro processor, micro sensor, and micro actuator. Among

Hidenoni Ishihara; Fumihito Arai; Toshio Fukuda

1996-01-01

169

Analysis of silicon-based optical racetrack resonator for acceleration sensing  

NASA Astrophysics Data System (ADS)

Silicon based racetrack resonator are demonstrated as highly sensitive acceleration sensor. The sensor consists of a straight waveguide coupled with a racetrack resonator, and a crossbeam seismic mass serving as the vibration unit. The resonant wavelength, which depends on the optical phase change per round trip, is sensitive to external accelerations due to the waveguide increment and stress-optic effect. With a 30-dB signal-to-noise ratio measurement system, the detection limit and dynamic range are theoretically obtained as high as 4.8×10-4 g under the frequency of acceleration below 200 Hz. The new silicon-based accelerometer will have great potential in seismic prospecting due to its high sensitivity, light weight and immunity to electromagnetic interference.

Mo, Wenqin; Wu, Huaming; Gao, Dingshan; Zhou, Zhiping

2010-10-01

170

Computer simulation of amorphous silicon based alloy p-i-n solar cells  

Microsoft Academic Search

We report on the results of a computer simulation of amorphous silicon-based alloy p-i-n solar cells based on the complete set of transport equations. Our model takes into account the spatial and energy variations of the localized state spectrum, nonuniform doping profiles, and nonuniform optical excitation. The computed dark and light current-voltage characteristics are in good agreement with experimental data.

M. Hack; M. Shur

1983-01-01

171

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

172

A Fully Integrated Silicon-Based 40-V Thermal Ink Jet IC  

Microsoft Academic Search

A fully-integrated silicon-based thermal ink jet printhead which produces high speed, laser-quality printing at 300 spots per inch resolution is described. Monolithic integration of the 5-V logic circuitry, 13-V predriver circuitry, 40-V MOSFETs, and 192 n+ polysilicon heater elements requires multiple process and device design trade-offs. The TIJ printhead is customer replaceable and must be protected from far greater static

William G. Hawkins; Cathie J. Burke; Thomas E. Watrobski; Thomas A. Tellier; Sophie Verdonckt-Vandebroek; T. Paul Chow

1992-01-01

173

Experimental verification of the feasibility of a 100 W class micro-scale gas turbine at an impeller diameter of 10 mm  

NASA Astrophysics Data System (ADS)

The feasibility of a 100 W class micro-scale gas turbine with a centrifugal impeller of 10 mm diameter has been studied by experimentally verifying the four major component performance requirements found from cycle analysis. The rotor is required to rotate at 870 000 rpm to generate the compressor pressure ratio 3, and it has successfully been achieved by using hydroinertia gas bearings. A compressor efficiency higher than that required by the target cycle has been measured. After correcting the effect of the heat leakage, approximately 65% of the compressor adiabatic efficiency is estimated to be achievable. The combustor has achieved stable self-sustained combustion at a combustion efficiency higher than 99.9%. The heat conduction analysis based on measured data showed that it is possible to keep the compressor below 170 °C when the turbine inlet temperature is 1050 °C. All four requirements are proven to be achievable, and hence, the feasibility of the micro-scale gas turbine at an impeller of 10 mm diameter has successfully been proven at component level.

Isomura, Kousuke; Murayama, Motohide; Teramoto, Susumu; Hikichi, Kousuke; Endo, Yuki; Togo, Shinichi; Tanaka, Shuji

2006-09-01

174

222Rn detection at the microBq/m3 range in nitrogen gas and a new Rn purification technique for liquid nitrogen  

PubMed

For the Borexino solar neutrino experiment a concentration line for 222Rn from a large volume of nitrogen gas has been constructed. It is based on cryo-adsorption in a charcoal trap of very low intrinsic 226Ra contamination. Consequently, the blank for activity from the daughter nuclide 222Rn is very low. 222Rn is recorded with proportional counters. This allows the detection of Rn at concentrations below the microBq/m3 level in gaseous nitrogen. The removal of radon from liquid nitrogen is achieved by direct adsorption in the liquid phase. 222Rn-measurements on evaporated nitrogen with and without previous purification are reported. PMID:10724427

Heusser; Rau; Freudiger; Laubenstein; Balata; Kirsten

2000-03-01

175

An electrochemical micro actuator  

Microsoft Academic Search

In this paper an investigation of the feasibility of a new electrochemical micro actuator is presented. The actuator is fabricated using silicon micro-machining techniques. A gas pressure is generated by electrolysis of an aqueous electrolyte solution. The build up pressure is used to change the deflection of a membrane. The actuator has three states: the electrolysis state, in which the

M. W. Hamberg; C. R. Neagu; J. G. E. Gardeniers; D. J. Ijntema; M. C. Elwenspoek

1995-01-01

176

[Applications 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

177

Performance of a Micro-Strip Gas Chamber for event wise, high rate thermal neutron detection with accurate 2D position determination  

NASA Astrophysics Data System (ADS)

A two-dimensional (2D) position sensitive detector for neutron scattering applications based on low-pressure gas amplification and micro-strip technology was built and tested with an innovative readout electronics and data acquisition system. This detector contains a thin solid neutron converter and was developed for time- and thus wavelength-resolved neutron detection in single-event counting mode, which improves the image contrast in comparison with integrating detectors. The prototype detector of a Micro-Strip Gas Chamber (MSGC) was built with a solid natGd/CsI thermal neutron converter for spatial resolutions of about 100 ?m and counting rates up to 107 neutrons/s. For attaining very high spatial resolutions and counting rates via micro-strip readout with centre-of-gravity evaluation of the signal amplitude distributions, a fast, channel-wise, self-triggering ASIC was developed. The front-end chips (MSGCROCs), which are very first signal processing components, are read out into powerful ADC-FPGA boards for on-line data processing and thereafter via Gigabit Ethernet link into the data receiving PC. The workstation PC is controlled by a modular, high performance dedicated software suite. Such a fast and accurate system is crucial for efficient radiography/tomography, diffraction or imaging applications based on high flux thermal neutron beam. In this paper a brief description of the detector concept with its operation principles, readout electronics requirements and design together with the signals processing stages performed in hardware and software are presented. In more detail the neutron test beam conditions and measurement results are reported. The focus of this paper is on the system integration, two dimensional spatial resolution, the time resolution of the readout system and the imaging capabilities of the overall setup. The detection efficiency of the detector prototype is estimated as well.

Mindur, B.; Alimov, S.; Fiutowski, T.; Schulz, C.; Wilpert, T.

2014-12-01

178

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

179

Formation mechanism of silicon based luminescence material using a photo chemical etching method  

Microsoft Academic Search

A photo chemical etching method to form a silicon based luminescence material on crystalline silicon has been studied. An n-type Si wafer (100) having resisitivity of 0.22–0.38 or 35–45 Ohm\\/cm was photo chemically etched in a mixture of HF and H2O2 (HF:H2O2=100:17?250), and He–Ne laser (633 nm) was irradiated onto the wafer surface through the solution. A photoluminescence spectrum from

Naokatsu Yamamoto; Hiroshi Takai

2001-01-01

180

Deformation-induced bandgap tuning of 2D silicon-based photonic crystals.  

PubMed

We address the issue of tuning the absolute bandgap in 2D silicon-based photonic crystals by mechanical deformation. The moving least-square (MLS) method, recently proposed by the authors for photonic bandgap materials, is employed for the real-space computation of band structures. The uniaxial tension mode is shown to be more effective for bandgap tuning than both pure and simple shear deformations. We verify that bandgap modifications are strongly influenced by the deformation-induced distortion of interfaces between inclusions and matrix. This result ensures the usefulness of real-space technique for the accurate calculation of strained photonic bandgap materials. PMID:19471392

Jun, Sukky; Cho, Young-Sam

2003-10-20

181

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

182

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

183

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

184

Plasma monitoring and PECVD process control in thin film silicon-based solar cell manufacturing  

NASA Astrophysics Data System (ADS)

A key process in thin film silicon-based solar cell manufacturing is plasma enhanced chemical vapor deposition (PECVD) of the active layers. The deposition process can be monitored in situ by plasma diagnostics. Three types of complementary diagnostics, namely optical emission spectroscopy, mass spectrometry and non-linear extended electron dynamics are applied to an industrial-type PECVD reactor. We investigated the influence of substrate and chamber wall temperature and chamber history on the PECVD process. The impact of chamber wall conditioning on the solar cell performance is demonstrated.

Gabriel, Onno; Kirner, Simon; Klick, Michael; Stannowski, Bernd; Schlatmann, Rutger

2014-02-01

185

Tracer gas dispersion in ducts—study of a new compact device using arrays of sonic micro jets  

Microsoft Academic Search

One of the most feasible ways to measure duct airflows is by tracer gas techniques, especially for complex situations when the duct lengths are short as well as their access, which makes extremely difficult or impossible other methods to be implemented. One problem associated with the implementation of tracer gas technique when the ducts lengths are short is due to

A. Rocha Silva; Clito F. Afonso

2004-01-01

186

Au-loaded In 2O 3 nanofibers-based ethanol micro gas sensor with low power consumption  

Microsoft Academic Search

Au-loaded In2O3 nanofibers, with different Au concentrations from 0.1wt% to 0.4wt%, were successfully prepared by an electrospinning method and characterized via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the fibers with diameters ranged from 80 to 100nm were made up of cubic In2O3. The nanofibers were deposited on a silicon substrate with micro hot-plate and

Xiujuan Xu; Huitao Fan; Yantong Liu; Lijie Wang; Tong Zhang

187

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

188

General mortality from 1944 through 1994 for a silicon-based chemical company.  

PubMed

The objective of this study is to reevaluate the statistically significant elevated risk of lung cancer among men with >or=20 years of employment at Dow Corning Corporation, a manufacturer of silicon-based materials. The cohort included 712 deaths among 8266 employees who were hired from 1943 to 1992 with follow-up through 1994. Standardized mortality ratios (SMRs) were calculated for 63 causes of death. Analysis confirmed a statistically significant increased mortality from cancer of the bronchus, trachea, and lung among men, prior to 1985, who jointly classified with >or=30 years of work duration and >or=30 years since first employed. SMRs for lung cancer after 1985, however, were not statistically significant and were inconsistent across work duration and years since first employed intervals. The study provides no evidence for elevated mortality among Dow Corning workers since the 1991 cohort mortality study. This study describes the updated mortality experience of a large employee cohort from a major silicon-based manufacturer. It illustrates that a well-designed mortality study can be a key component of employee health surveillance efforts in an industrial setting with potential hazardous workplace exposures. PMID:17495695

Bowlin, Steven J; Clark, Brian D; Prebay, Rachelle K; Klein, Patti J; Perkins, Laura L

2007-05-01

189

Design, Fabrication and Prototype testing of a Chip Integrated Micro PEM Fuel Cell Accumulator combined On-Board Range Extender  

NASA Astrophysics Data System (ADS)

In this work we present the design, fabrication and prototype testing of Chip Integrated Micro PEM Fuel Cell Accumulator (CI?-PFCA) combined On-Board Range Extender (O-BRE). CI?-PFCA is silicon based micro-PEM fuel cell system with an integrated hydrogen storage feature (palladium metal hydride), the run time of CI?-PFCA is dependent on the stored hydrogen, and in order to extend its run time an O-BRE is realized (catalytic hydrolysis of chemical hydride, NaBH4. Combining the CI?-PFCA and O-BRE on a system level have few important design requirements to be considered; hydrogen regulation, gas -liquid separator between the CI?-PFCA and the O-RE. The usage of traditional techniques to regulate hydrogen (tubes), gas-liquid phase membranes (porous membrane separators) are less desirable in the micro domain, due to its space constraint. Our approach is to use a passive hydrogen regulation and gas-liquid phase separation concept; to use palladium membrane. Palladium regulates hydrogen by concentration diffusion, and its property to selectively adsorb only hydrogen is used as a passive gas-liquid phase separator. Proof of concept is shown by realizing a prototype system. The system is an assembly of CI?-PFCA, palladium membrane and the O-BRE. The CI?-PFCA consist of 2 individually processed silicon chips, copper supported palladium membrane realized by electroplating followed by high temperature annealing process under inter atmosphere and the O-BRE is realized out of a polymer substrate by micromilling process with platinum coated structures, which functions as a catalyst for the hydrolysis of NaBH4. The functionality of the assembled prototype system is demonstrated by the measuring a unit cell (area 1 mm2) when driven by the catalytic hydrolysis of chemical hydride (NaBH4 and the prototype system shows run time more than 15 hours.

Balakrishnan, A.; Mueller, C.; Reinecke, H.

2014-11-01

190

IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 52, NO. 3, MARCH 2005 419 Silicon-Based Micro-Fourier Spectrometer  

E-print Network

concepts were transferred from the macro to the microscale like grating spectrometers [1], [2], Fabry on a sensor chip. Grating spectrometers and classical Fourier spectrometer do not allow for the dense-Fourier Spectrometer Dietmar Knipp, Member, IEEE, Helmut Stiebig, Sameer R. Bhalotra, Student Member, IEEE, Eerke Bunte

Miller, David A. B.

191

A comparative study of in-flow and micro-patterning biofunctionalization protocols for nanophotonic silicon-based biosensors.  

PubMed

Reliable immobilization of bioreceptors over any sensor surface is the most crucial step for achieving high performance, selective and sensitive biosensor devices able to analyze human samples without the need of previous processing. With this aim, we have implemented an optimized scheme to covalently biofunctionalize the sensor area of a novel nanophotonic interferometric biosensor. The proposed method is based on the ex-situ silanization of the silicon nitride transducer surface by the use of a carboxyl water soluble silane, the carboxyethylsilanetriol sodium salt (CTES). The use of an organosilane stable in water entails advantages in comparison with usual trialkoxysilanes such as avoiding the generation of organic waste and leading to the assembly of compact monolayers due to the high dielectric constant of water. Additionally, cross-linking is prevented when the conditions (e.g. immersion time, concentration of silane) are optimized. This covalent strategy is followed by the bioreceptor linkage on the sensor area surface using two different approaches: an in-flow patterning and a microcontact printing using a biodeposition system. The performance of the different bioreceptor layers assembled is compared by the real-time and label-free immunosensing of the proteins BSA/mAb BSA, employed as a model molecular pair. Although the results demonstrated that both strategies provide the biosensor with a stable biological interface, the performance of the bioreceptor layer assembled by microcontact printing slightly improves the biosensing capabilities of the photonic biosensor. PMID:23168044

González-Guerrero, Ana Belén; Alvarez, Mar; García Castaño, Andrés; Domínguez, Carlos; Lechuga, Laura M

2013-03-01

192

Micro-Raman Mapping of 3C-SiC Thin Films Grown by Solid–Gas Phase Epitaxy on Si (111)  

PubMed Central

A series of 3C-SiC films have been grown by a novel method of solid–gas phase epitaxy and studied by Raman scattering and scanning electron microscopy (SEM). It is shown that during the epitaxial growth in an atmosphere of CO, 3C-SiC films of high crystalline quality, with a thickness of 20 nm up to few hundreds nanometers can be formed on a (111) Si wafer, with a simultaneous growth of voids in the silicon substrate under the SiC film. The presence of these voids has been confirmed by SEM and micro-Raman line-mapping experiments. A significant enhancement of the Raman signal was observed in SiC films grown above the voids, and the mechanisms responsible for this enhancement are discussed. PMID:20730078

2010-01-01

193

Speciation analysis of organotin compounds in human urine by headspace solid-phase micro-extraction and gas chromatography with pulsed flame photometric detection.  

PubMed

A new headspace solid-phase micro-extraction (HS-SPME) method followed by gas chromatography with pulsed flame photometric detection (GC-PFPD) analysis has been developed for the simultaneous determination of 11 organotin compounds, including methyl-, butyl-, phenyl- and octyltin derivates, in human urine. The methodology has been validated by the analysis of urine samples fortified with all analytes at different concentration levels, and recovery rates above 87% and relative precisions between 2% and 7% were obtained. Additionally, an experimental-design approach has been used to model the storage stability of organotin compounds in human urine, demonstrating that organotins are highly degraded in this medium, although their stability is satisfactory during the first 4 days of storage at 4 °C and pH=4. Finally, this methodology was applied to urine samples collected from harbor workers exposed to antifouling paints; methyl- and butyltins were detected, confirming human exposure in this type of work environment. PMID:24840433

Valenzuela, Aníbal; Lespes, Gaëtane; Quiroz, Waldo; Aguilar, Luis F; Bravo, Manuel A

2014-07-01

194

Fluid inclusion volatile analysis by gas chromatography with photoionization micro-thermal conductivity detectors: Applications to magmatic MoS 2 and other H 2 O-CO 2 and H 2 OCH 4 fluids  

Microsoft Academic Search

Eighteen fluid inclusion volatile peaks have been detected and identified from 1-2 g samples (quartz) by gas chromatography using heated (~105°C) on-line crushing, helium carrier gas, a single porous polymer column (HayeSep R; 10' × 1\\/8'':100\\/120#; Ni alloy tubing), two temperature programme conditions for separate sample aliquots, micro-thermal conductivity (TCD) and photoionization detectors (PID; 11.7 eV lamp), and off-line digital

C. J. Bray; E. T. C. Spooner

1992-01-01

195

Fluid inclusion volatile analysis by gas chromatography with photoionization\\/micro-thermal conductivity detectors: Applications to magmatic MoS sub 2 and other H sub 2 O-CO sub 2 and H sub 2 OCH sub 4 fluids  

Microsoft Academic Search

Eighteen fluid inclusion volatile peaks have been detected and identified from 1-2 g samples (quartz) by gas chromatography using heated on-line crushing, helium carrier gas, a single porous polymer column, two temperature programmed conditions for separate sample aliquots, micro-thermal conductivity (TCD) and photoionization detectors (PID), and off-line digital peak processing. In order of retention time these volatile peaks are: Nâ,

C. J. Bray; E. T. C. Spooner

1992-01-01

196

Gas  

MedlinePLUS

... swallow and the breakdown of undigested food by bacteria in the large intestine. Certain foods may cause gas. Foods that produce gas in one person may not cause gas in another. You can reduce the amount of gas you have by Drinking lots of water and non-fizzy drinks Eating more slowly so ...

197

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

2012-05-01

198

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

199

Silicon-based resonant-cavity-enchanced photodiode with a buried SiO2 reflector  

NASA Astrophysics Data System (ADS)

We report on a silicon-based resonant cavity photodiode with a buried silicon dioxide layer as the bottom reflector. The buried oxide is created by using a separation by implantation of oxygen technique. The device shows large Fabry-Pérot oscillations. Resonant peaks and antiresonant troughs are observed as a function of the wavelength, with a peak responsivity of about 50 mA/W at 650 and 709 nm. The leakage current density is 85 pA/mm2 at -5 V, and the average zero-bias capacitance is 12 pF/mm2. We also demonstrate that the buried oxide prevents carriers generated deep within the substrate from reaching the top contacts, thus removing any slow carrier diffusion tail from the impulse response.

Sinnis, V. S.; Seto, M.; 't Hooft, G. W.; Watabe, Y.; Morrison, A. P.; Hoekstra, W.; de Boer, W. B.

1999-03-01

200

High-performance binary blazed grating coupler used in silicon-based hybrid photodetector integration  

NASA Astrophysics Data System (ADS)

An efficient and high-performance binary blazed grating coupler was designed based on silicon-on-insulator (SOI) used for silicon-based hybrid photodetector integration in an arrayed waveguide grating demodulation integrated microsystem. A relatively high coupling efficiency was obtained to optimize mode matching by the finite-difference time-domain method by choosing appropriate grating parameters, including period, etching depth, and fill factor. Coupling efficiency output at 1550 nm for the TE mode reached 68%. This value was >60% in the wavelength range of 1450 to 1600 nm, specifically 71.4% around 1478 nm. An InP/InGaAs photodetector and SOI wafer were integrated by using benzocyclobutene (BCB) bonding. When the thickness of the BCB bonding layer was 440 nm, power absorption efficiency at 1550 nm for the TE mode reached 78.5%, whereas efficiency reached ˜81.8% around 1475 nm.

Li, Hongqiang; Liu, Yu; Miao, Chunjiao; Zhang, Meiling; Zhou, Wenqian; Tang, Chunxiao; Li, Enbang

2014-09-01

201

Silicon-based photonic crystals fabricated using proton beam writing combined with electrochemical etching method.  

PubMed

A method for fabrication of three-dimensional (3D) silicon nanostructures based on selective formation of porous silicon using ion beam irradiation of bulk p-type silicon followed by electrochemical etching is shown. It opens a route towards the fabrication of two-dimensional (2D) and 3D silicon-based photonic crystals with high flexibility and industrial compatibility. In this work, we present the fabrication of 2D photonic lattice and photonic slab structures and propose a process for the fabrication of 3D woodpile photonic crystals based on this approach. Simulated results of photonic band structures for the fabricated 2D photonic crystals show the presence of TE or TM gap in mid-infrared range. PMID:22824206

Dang, Zhiya; Breese, Mark Bh; Recio-Sánchez, Gonzalo; Azimi, Sara; Song, Jiao; Liang, Haidong; Banas, Agnieszka; Torres-Costa, Vicente; Martín-Palma, Raúl José

2012-01-01

202

Silicon-based photonic crystals fabricated using proton beam writing combined with electrochemical etching method  

NASA Astrophysics Data System (ADS)

A method for fabrication of three-dimensional (3D) silicon nanostructures based on selective formation of porous silicon using ion beam irradiation of bulk p-type silicon followed by electrochemical etching is shown. It opens a route towards the fabrication of two-dimensional (2D) and 3D silicon-based photonic crystals with high flexibility and industrial compatibility. In this work, we present the fabrication of 2D photonic lattice and photonic slab structures and propose a process for the fabrication of 3D woodpile photonic crystals based on this approach. Simulated results of photonic band structures for the fabricated 2D photonic crystals show the presence of TE or TM gap in mid-infrared range.

Dang, Zhiya; Breese, Mark BH; Recio-Sánchez, Gonzalo; Azimi, Sara; Song, Jiao; Liang, Haidong; Banas, Agnieszka; Torres-Costa, Vicente; Martín-Palma, Raúl José

2012-07-01

203

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

2012-02-01

204

Corrosion-Prevention Capabilities of a Water-Borne, Silicone-Based, Primerless Coating  

NASA Technical Reports Server (NTRS)

Comparative tests have been performed to evaluate the corrosion-prevention capabilities of an experimental paint of the type described in Water-Borne, Silicone-Based, Primerless Paints, NASA Tech Briefs, Vol. 26, No. 11 (November 2002), page 30. To recapitulate: these paints contain relatively small amounts of volatile organic solvents and were developed as substitutes for traditional anticorrosion paints that contain large amounts of such solvents. An additional desirable feature of these paints is that they can be applied without need for prior application of primers to ensure adhesion. The test specimens included panels of cold-rolled steel, stainless steel 316, and aluminum 2024-T3. Some panels of each of these alloys were left bare and some were coated with the experimental water-borne, silicone-based, primerless paint. In addition, some panels of aluminum 2024-T3 and some panels of a fourth alloy (stainless steel 304) were coated with a commercial solvent-borne paint containing aluminum and zinc flakes in a nitrile rubber matrix. In the tests, the specimens were immersed in an aerated 3.5-weight-percent aqueous solution of NaCl for 168 hours. At intervals of 24 hours, the specimens were characterized by electrochemical impedance spectroscopy (EIS) and measurements of corrosion potentials. The specimens were also observed visually. As indicated by photographs of specimens taken after the 168-hour immersion (see figure), the experimental primerless silicone paint was effective in preventing corrosion of stainless steel 316, but failed to protect aluminum 2024-T3 and cold-rolled steel. The degree of failure was greater in the case of the cold-rolled steel. On the basis of visual observations, EIS, and corrosion- potential measurements, it was concluded that the commercial aluminum and zinc-filled nitrile rubber coating affords superior corrosion protection to aluminum 2024-T3 and is somewhat less effective in protecting stainless steel 304.

Calle, Luz Marina; MacDowell, Louis G.; Vinje, Rubie D.

2005-01-01

205

1 Purdue Micro Pattern Gas Detector R&D Miyamoto, Shipsey, Guirl (undergrad), Kane (undergrad), May (undergrad)  

E-print Network

machine and a vacuum oven. In addition through the School of Electrical and Computer Engineering (ECE for quality control, through the Department of Biological Sciences to gas analysis (chromatography and mass, and liquid kapton thin film MPGDs and the development of the first plastic MPGD with two dimensional

206

Neutral gas temperature maps of the pin-to-plate Argon micro discharge into the ambient air  

E-print Network

This study is designed to explore the two dimensional temperature maps of the atmospheric argon discharge consisting of pin-to-plane electrodes supplied by a high voltage DC source. After checking the stability of the micro discharge, the two dimensional image plane focused by a quartz lens was scanned by the fiber probe driven by a 3D Mobile Platform. The rotational and vibrational temperatures are calculated using nitrogen emissions collected by the high resolution spectrometer and high sensitive intensified charge coupled device (ICCD). The rotational temperature varies from 1558.15 K to 2621.14 K and vibrational temperature varies from 3010.38 K to 3774.69 K, indicating a great temperature gradient due to small discharge size. The temperature maps show a lateral expansion and a sharp truncation in the radial direction. A double layers discharge is identified, where an arc discharge coats the glow discharge.

Xu, Shaofeng; Majeed, Asif

2015-01-01

207

An Experimental Study on the Fabrication of Glass-based Acceleration Sensor Body Using Micro Powder Blasting Method  

Microsoft Academic Search

This study investigated the feasibility of the micr o powder blasting technique for the micro fabrication of sensor structures using th e Pyrex glass to replace the existing silicon-based acceleration sensor fabrication proce sses. As the preliminary experiments, the effects of the blasting pressure, the mass flow rat e of abrasive and the number of nozzle scanning times on erosion

Dong-Sam Park; Dae-Jin Yun; Myeong-Woo Cho; Bong-Cheol Shin

2007-01-01

208

Future advances: Stretchable silicon-based electronics http://www.whatistheword.com/story/SciTech_418.html 1 of 1 12/21/2005 5:57 PM  

E-print Network

for the electronics industry. "Stretchable silicon offers different capabilities than can be achieved with standardFuture advances: Stretchable silicon-based electronics http://www.whatistheword.com/story/SciTech_418.html 1 of 1 12/21/2005 5:57 PM Future advances: Stretchable silicon-based electronics WASHINGTON

Rogers, John A.

209

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

Microsoft Academic Search

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

Ryan Richard Dehoff

2008-01-01

210

Temperature-Controlled Growth of Silicon-Based Nanostructures by Thermal Evaporation of SiO Powders  

E-print Network

-10 laser ablation of metal- containing Si target11-14 or metal-free Si/SiO2 target,11,15 and thermal-10 and laser ablation.11-15 In thermal evaporation, oxides were found to play a dominant role in the nucleationTemperature-Controlled Growth of Silicon-Based Nanostructures by Thermal Evaporation of SiO Powders

Wang, Zhong L.

211

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

2013-11-01

212

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

213

Understanding and mitigating DNA induced corrosion in porous silicon based biosensors  

NASA Astrophysics Data System (ADS)

Porous silicon structures have been demonstrated as effective biosensors due to their large surface area, size-selective filtering capabilities, and tunable optical properties. However, porous silicon surfaces are highly susceptible to oxidation and corrosion in aqueous environments and solutions containing negative charges. In DNA sensing applications, porous silicon corrosion can mask the DNA binding signal as the typical increase in refractive index that results from a hybridization event can be countered by the decrease in refractive index due to corrosion of the porous silicon matrix. Such signal ambiguity should be eliminated in practical devices. In this work, we carefully examined the influence of charge density and surface passivation on the corrosion process in porous silicon waveguides in order to control this process in porous silicon based biosensors. Both increased DNA probe density and increased target DNA concentration enhance the corrosion process, leading to an overall blueshift of the waveguide resonance. While native porous silicon structures degrade upon prolonged exposure to solutions containing negative charges, porous silicon waveguides that are sufficiently passivated to prevent oxidation/corrosion in aqueous solution exhibit a saturation effect in the corrosion process, which increases the reliability of the sensor. For practical implementation of porous silicon DNA sensors, the negative charges from DNA must be mitigated. We show that a redshift of the porous silicon waveguide resonance results from either replacing the DNA target with neutral charge PNA or introducing Mg2+ ions to shield the negative charges of DNA.

Zhao, Yiliang; Lawrie, Jenifer L.; Laibinis, Paul E.; Weiss, Sharon M.

2014-03-01

214

On-Wafer Measurement of a Silicon-Based CMOS VCO at 324 GHz  

NASA Technical Reports Server (NTRS)

The world s first silicon-based complementary metal oxide/semiconductor (CMOS) integrated-circuit voltage-controlled oscillator (VCO) operating in a frequency range around 324 GHz has been built and tested. Concomitantly, equipment for measuring the performance of this oscillator has been built and tested. These accomplishments are intermediate steps in a continuing effort to develop low-power-consumption, low-phase-noise, electronically tunable signal generators as local oscillators for heterodyne receivers in submillimeter-wavelength (frequency > 300 GHz) scientific instruments and imaging systems. Submillimeter-wavelength imaging systems are of special interest for military and law-enforcement use because they could, potentially, be used to detect weapons hidden behind clothing and other opaque dielectric materials. In comparison with prior submillimeter- wavelength signal generators, CMOS VCOs offer significant potential advantages, including great reductions in power consumption, mass, size, and complexity. In addition, there is potential for on-chip integration of CMOS VCOs with other CMOS integrated circuitry, including phase-lock loops, analog- to-digital converters, and advanced microprocessors.

Samoska, Lorene; Man Fung, King; Gaier, Todd; Huang, Daquan; Larocca, Tim; Chang, M. F.; Campbell, Richard; Andrews, Michael

2008-01-01

215

Design of a compact polarization rotator for silicon-based slot waveguides  

NASA Astrophysics Data System (ADS)

A design scheme of compact polarization rotator (PR) for silicon-based slot waveguides is proposed, where the slot including the upper claddings is filled with liquid crystals (LCs). With this design, the transverse field components of eigenmodes supported by the slot waveguides have almost identical amplitudes due to the anisotropic features of the LCs, leading to a high modal hybridness, which plays a pivotal role in designing an efficient PR. As a consequence, the input TE (TM) mode can be converted efficiently to the TM (TE) mode at the output port within a short length. The numerical results show that a PR of 11.3?m in length at the operating wavelength of 1.55?m is achieved with the extinction ratio and insertion loss of 12.6 (11.5) dB and 0.22 (0.30) dB, for TE-to-TM (TM-to-TE) conversion, respectively. Moreover, field evolution along the propagation distance through the PR is also demonstrated.

Xu, Yin; Wang, Jiayuan; Xiao, Jinbiao; Sun, Xiaohan

2014-07-01

216

Angular dependence of the magnetoresistance effect in a silicon based p-n junction device.  

PubMed

We report a pronounced angular dependence of the magnetoresistance (MR) effect in a silicon based p-n junction device at room temperature by manipulating the space charge region of the p-n junction under a magnetic field. For the p-n junction device with various space charge region configurations, we find that all the angular dependence of the MR effect is proportional to sin(2)(?), where the ? is the angle between the magnetic field and the driving current. With increasing the magnetic field and driving current, the anisotropic MR effect is obviously improved. At room temperature, under a magnetic field 2 T and driving current 20 mA, the MR ratio is about 50%, almost one order of amplitude larger than that in the magnetic material permalloy. Our results reveal an interpretation of the MR effect in the non-magnetic p-n junction in terms of the Lorentz force and give a new way for the development of future magnetic sensors with non-magnetic p-n junctions. PMID:24561960

Wang, Tao; Si, Mingsu; Yang, Dezheng; Shi, Zhong; Wang, Fangcong; Yang, Zhaolong; Zhou, Shiming; Xue, Desheng

2014-04-21

217

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

218

Synthesis of new 18F-radiolabeled silicon-based nitroimidazole compounds.  

PubMed

The syntheses of new nitroimidazole compounds using silicon-[(18)F]fluorine chemistry for the potential detection of tumor hypoxia are described. [(18)F]silicon-based compounds were synthesized by coupling 2-nitroimidazole with silyldinaphtyl or silylphenyldi-tert-butyl groups and labeled by fluorolysis or isotopic exchange. Dinaphtyl compounds (6, 10) were labeled in 56-71% yield with a specific activity of 45 GBq/?mol, however these compounds ([(18)F]7 and [(18)F]11) were not stable in plasma. Phenyldi-tert-butyl compounds were labeled in 70% yield with a specific activity of 3 GBq/?mol by isotopic exchange, or in 81% yield by fluorolysis of siloxanes with a specific activity of 45 GBq/?mol. The labeled compound [(18)F]18 was stable in plasma and excreted by the liver and kidneys in vivo. In conclusion, the fluorosilylphenyldi-tert-butyl (SiFA) group is more stable in plasma than fluorosilyldiphenyl moiety. Thus, compound [(18)F]18 is suitable for further in vivo assessments. PMID:23665140

Joyard, Yoann; Azzouz, Rabah; Bischoff, Laurent; Papamicaël, Cyril; Labar, Daniel; Bol, Anne; Bol, Vanessa; Vera, Pierre; Grégoire, Vincent; Levacher, Vincent; Bohn, Pierre

2013-07-01

219

18F-Labeled Silicon-Based Fluoride Acceptors: Potential Opportunities for Novel Positron Emitting Radiopharmaceuticals  

PubMed Central

Background. Over the recent years, radiopharmaceutical chemistry has experienced a wide variety of innovative pushes towards finding both novel and unconventional radiochemical methods to introduce fluorine-18 into radiotracers for positron emission tomography (PET). These “nonclassical” labeling methodologies based on silicon-, boron-, and aluminium-18F chemistry deviate from commonplace bonding of an [18F]fluorine atom (18F) to either an aliphatic or aromatic carbon atom. One method in particular, the silicon-fluoride-acceptor isotopic exchange (SiFA-IE) approach, invalidates a dogma in radiochemistry that has been widely accepted for many years: the inability to obtain radiopharmaceuticals of high specific activity (SA) via simple IE. Methodology. The most advantageous feature of IE labeling in general is that labeling precursor and labeled radiotracer are chemically identical, eliminating the need to separate the radiotracer from its precursor. SiFA-IE chemistry proceeds in dipolar aprotic solvents at room temperature and below, entirely avoiding the formation of radioactive side products during the IE. Scope of Review. A great plethora of different SiFA species have been reported in the literature ranging from small prosthetic groups and other compounds of low molecular weight to labeled peptides and most recently affibody molecules. Conclusions. The literature over the last years (from 2006 to 2014) shows unambiguously that SiFA-IE and other silicon-based fluoride acceptor strategies relying on 18F? leaving group substitutions have the potential to become a valuable addition to radiochemistry. PMID:25157357

Bernard-Gauthier, Vadim; Wängler, Carmen; Wängler, Bjoern; Schirrmacher, Ralf

2014-01-01

220

Signal Amplification by 1/f Noise in Silicon-Based Nanomechanical  

E-print Network

are somewhat similar to a neurobiological system-rat skin neurons-in the effect that colored noise has-on-insulator (SOI) wafer. Figure 1 includes a micro- graph of the device, showing actuation and detection electrodes

221

High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents.  

PubMed

To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-?m-deep, and 60-?m-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m. PMID:24899869

Li, Yi; Du, Xiaosong; Wang, Yang; Tai, Huiling; Qiu, Dong; Lin, Qinghao; Jiang, Yadong

2014-01-01

222

Optimization and application of headspace-solid-phase micro-extraction coupled with gas chromatography-mass spectrometry for the determination of volatile compounds in cherry wines.  

PubMed

A simple, rapid and solvent-free multi-residue method has been developed and applied to confirm and quantify a series of volatile compounds in five cherry wines by gas chromatography coupled with mass spectrometry (GC-MS). Four parameters (e.g., coating material of fiber, temperature and time of extraction, and addition of sodium chloride in the solution) of headspace solid-phase micro-extraction (HS-SPME) were optimized, resulting in the best extraction condition including 50/30?m DVB/CAR/PDMS fiber, 45min and 50°C of SPME, and 2g of sodium chloride addition in the wine during the extraction. The SPME had LODs and LOQs ranging from 0.03 to 7.27?gL(-1) and 0.10 to 24.24?gL(-1) for analytic compounds, respectively. Repeatability and reproducibility values were all below 19.8%, with mean values of 12.7% and 10.5%, respectively. Regression coefficients (R(2)) of detective linearity of the standard curves was higher than 0.9852. Moreover, relative recoveries of analytical targets were achieved in a range of 60.7-125.6% with good relative standard deviation values (?20.6%). In addition, a principal component analysis (PCA) was used to analyze the aroma profiles of the wines, which indicated that five samples were distinctly divided into two groups based on their different geographical origins and volatile compounds. PMID:25544009

Xiao, Zuobing; Zhou, Xuan; Niu, Yunwei; Yu, Dan; Zhu, Jiancai; Zhu, Guangyong

2015-01-26

223

Effect of Polytetrafluoroethylene (PTFE) and micro porous layer (MPL) on thermal conductivity of fuel cell gas diffusion layers: Modeling and experiments  

NASA Astrophysics Data System (ADS)

Through-plane thermal conductivity of 14 SIGRACET gas diffusion layers (GDLs), including series 24 & 34, as well as 25 & 35, and of micro porous layer (MPL) is accurately measured under different compression, ranging from 2 to 14 bar, at a nominal temperature of 60 °C. The effect of compression, PTFE loading, and of MPL on thermal conductivity and contact resistance is investigated experimentally, and measurements are presented for the first time for the contact resistance between an MPL and a GDL for an MPL-coated GDL substrate. A new and robust mechanistic model is presented for predicting the through-plane thermal conductivity of GDLs treated with PTFE and is successfully verified with the present experimental data. The model predicts the experimentally-observed reduction in thermal conductivity as a result of PTFE treatment, and provides detailed insights on the functional dependence of thermal conductivity on geometric parameters, compression, and PTFE. The model can be used in performance modeling and in design of polymer electrolyte membrane fuel cells.

Sadeghifar, Hamidreza; Djilali, Ned; Bahrami, Majid

2014-02-01

224

High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents  

NASA Astrophysics Data System (ADS)

To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-?m-deep, and 60-?m-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m.

Li, Yi; Du, Xiaosong; Wang, Yang; Tai, Huiling; Qiu, Dong; Lin, Qinghao; Jiang, Yadong

2014-05-01

225

High-separation efficiency micro-fabricated multi-capillary gas chromatographic columns for simulants of the nerve agents and blister agents  

PubMed Central

To achieve both high speed and separation efficiency in the separation of a mixture of nerve and blister agent simulants, a high-aspect-ratio micro-fabricated multi-capillary column (MCC, a 50-cm-long, 450-?m-deep, and 60-?m-wide four-capillary column) was fabricated by the application of the microelectromechanical system (MEMS) techniques. Mixtures of chemical warfare agent (CWA) simulants - dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and methyl salicylate - were used as samples. The fabricated MCC allowed for the separation of all the components of the gaseous mixture within 24 s, even when the difference in boiling point was 4°C, as in the case of TEP and methyl salicylate. Furthermore, interfering agents - dichloromethane, ethanol, and toluene - were also included in the subsequent gaseous mixture samples. The boiling point of these six components ranged from 78°C to 219°C. All six components were clearly separated within 70 s. This study is the first to report the clear separation of gas mixtures of components with close boiling points. The column efficiency was experimentally determined to be 12,810 plates/m. PMID:24899869

2014-01-01

226

Sensitive and robotic determination of bromate in sea water and drinking deep-sea water by headspace solid-phase micro extraction and gas chromatography-mass spectrometry.  

PubMed

A robotic method has been established for the determination of bromate in sea water and drinking deep-sea water. Bromate in water was converted into volatile derivative, which was measured with headspace solid-phase micro extraction and gas chromatography-mass spectrometry (HS-SPME GC-MS). Derivatization reagent and the HS-SPME parameters (selection of fibre, extraction/derivatization temperature, heating time and; the morality of HCl) were optimized and selected. Under the established conditions, the detection and the quantification limits were 0.016 ?g L(-1) and 0.051 ?g L(-1), respectively, and the intra- and inter-day relative standard deviation was less than 7% at concentrations of 1.0 and 10.0 ?g L(-1). The calibration curve showed good linearity with r(2)=0.9998. The common ions Cl(-), NO(3)(-), SO(4)(2-), HPO(4)(2-), H(2)PO(4)(-), K(+), Na(+), NH(4)(+), Ca(2+), Mg(2+), Ba(2+), Mn(4+), Mn(2+), Fe(3+) and Fe(2+) did not interfere even when present in 1000-fold excess over the active species. The method was successfully applied to the determination of bromate in sea water and drinking deep-sea water. PMID:22840702

Lim, Hyun-Hee; Shin, Ho-Sang

2012-09-01

227

A carbon foam with a bimodal micro–mesoporous structure prepared from larch sawdust for the gas-phase toluene adsorption  

SciTech Connect

Highlights: ? Network carbon foam containing a bimodal pore distribution was prepared from Larch. ? Liquefaction route was used for the preparation of morphology controllable carbon. ? Pore structure of carbon foam was controlled through KOH activation. - Abstract: A carbon foam with a bimodal micro–mesopore distribution, was prepared by submitting larch sawdust to liquefaction, resinification, foaming, carbonization and KOH activation. The morphology, pore texture and crystal microstructure was characterized by scanning and transmission electron microscopy, nitrogen adsorption analysis and X-ray powder diffraction. A honeycomb structure with adjacent cells was observed for the precursor of carbon foam. After KOH activation, the cell wall of precursor shrunk and broke. This lead to the formation of a well-connected 3D network and developed ligament pore structure (surface area of 554–1918 m{sup 2}/g) containing bimodal pores, 2.1 and 3.9 nm in diameter. The porous carbon foam prepared at 700 °C exhibited a much higher gas-phase toluene removal than commercial activated carbon fiber owing to the 3D network and bimodal pore structure.

Liu, Shouxin, E-mail: liushouxin@126.com [Key Laboratory of Bio-Based Material Science and Technology of The Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Huang, Zhanhua; Wang, Rui [Key Laboratory of Bio-Based Material Science and Technology of The Ministry of Education, Northeast Forestry University, Harbin 150040 (China)

2013-07-15

228

Compatibility of cobalt and chromium depletion gates with RPECVD upper gate oxide for silicon-based nanostructures  

Microsoft Academic Search

Three-dimensional confinement of electrons in silicon-based nanodevices may be achieved using a dual gate structure to confine carriers laterally in a 2D MOSFET inversion layer. We have investigated the temperature stability of cobalt and chromium for thin depletion gates, using remote plasma enhanced chemical vapour deposited (RPECVD) 0268-1242\\/13\\/8A\\/022\\/img9 for the deposited dielectric. The thermal stability of the oxide\\/metal\\/oxide structure for

M. J. Rack; A. D. Gunther; M. Khoury; D. Vasileska; D. K. Ferry; M. Sidorov

1998-01-01

229

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

PubMed Central

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. PMID:23718202

2013-01-01

230

Compatibility study of thin passivation layers with hydrazine for silicon-based MEMS microthruster  

NASA Astrophysics Data System (ADS)

In this work, the compatibility studies of silicon and its different multilayer structures with hydrazine for possible applications to MEMS have been reported. Grazing incidence x-ray diffraction patterns of the r.f. sputtered Si/SiO2/Si3N4 stack layer show preferably oriented crystalline structure after hydrazine treatment at different temperatures. The Fourier transform infrared spectroscopic measurement reveals that local bonding of the constituent atoms of the surface layers, where Si-O bond is replaced partially by Si-N bond while treated. Further, the surface morphology carried out by atomic force microscopy exhibits the tendency of reducing surface roughness with the increase in temperature during hydrazine treatment. From the axisymmetric drop shape analysis (ADSA), it is observed that static contact angle changes slightly for different wettability nature of solid surface due to aggregation of crystallites in the valley of the surface fluctuation and anisotropic modification in preferred orientation of the film surface. On the basis of equation of state theory with approximation of solid surface-liquid, interfacial energy was applied to determine the solid surface free energy providing the limited variation in different stack layers. Lastly, the J-V characteristic of the stack layer treated by hydrazine at different temperatures shows multiple current conduction regions with the same current density for varying electric field. Therefore, among various single or multilayer silicon-based thin film combinations, the Si/SiO2/Si3N4 stack layer is the most promising passivation layer for hydrazine-based MEMS applications.

Kundu, Pijus; Ghosh, Avijit; Das, Soumen; Bhattacharyya, T. K.

2012-03-01

231

Triple junction amorphous silicon based flexible photovoltaic submodules on polyimide substrates  

NASA Astrophysics Data System (ADS)

This dissertation provides the first detailed description of the fabrication of flexible, monolithically interconnected photovoltaic sub-modules based on triple-junction amorphous silicon (a-Si) cell technology. There are several problems encountered when progressing from small area (0.25 cm2) solar cells to series interconnected modules that are three orders of magnitude larger in area. This work involved the development of techniques required to overcome some of those problems, and the application of these in order to successfully fabricate triple-junction a-Si based solar sub-modules 10cm x 30cm (4'' x 12'') in size. The solar cells were fabricated on Kapton-VN and Upilex-S polyimide films. Polyimide films were chosen because polyimides have the highest thermal and dimensional stability of any polymer commercially available in film form. Chromium or molybdenum tie-coat layers were introduced between the polyimide and back-reflector films in order to improve film adhesion, which is otherwise unsatisfactory. An improved electrochemical shunt passivation process (light assisted shunt passivation) was developed and used to passivate shunts in the cells. Shunt passivation is especially important for larger area solar cells. A combination of laser (dry) and wet chemical processing was used for the series interconnection. A laser-weld based interconnection scheme was chosen, for its compatibility with the shunt passivation process. The cells were encapsulated with the terpolymer THV (St. Gobain) and Tefzel (Dupont), using a vacuum laminator that was specially built for this purpose. To summarize, triple-junction-amorphous-silicon-based, series interconnected photovoltaic submodules of size 10 cm x 30 cm were fabricated on lightweight and flexible substrates. The modules have an aperture area of approximately 200 cm 2. An initial AM1.5 efficiency of 4.75% (5.34% in natural sunlight) was obtained for a module with an aperture area of 204 cm2. The specific power of this module is approximately 40 W/kg.

Vijh, Aarohi

2005-07-01

232

Modliser l'ADN avec Graphite-MicroMgas Modeling DNA with Graphite-MicroMgas  

E-print Network

Modéliser l'ADN avec Graphite-MicroMégas Modeling DNA with Graphite-MicroMégas Samuel Hornus reconstruire virtuellement les assemblages de protéines et d'ADN. Il ne s'agit pas uniquement d'illustrer en 3D de l'ADN. Techniquement, MicroMé- gas est un plugin du logiciel Graphite, qui est une plateforme de

Lévy, Bruno

233

Effects of silicon-based fertilizer applications on the development and reproduction of insect pests associated with greenhouse-grown crops.  

E-print Network

?? The purpose of this comprehensive study was to investigate the effects of silicon-based fertilizer applications in promoting host-plant resistance to certain piercing-sucking insects feeding… (more)

Hogendorp, Brian K.

2009-01-01

234

Measurement of non-enteric emission fluxes of volatile fatty acids from a California dairy by solid phase micro-extraction with gas chromatography/mass spectrometry  

NASA Astrophysics Data System (ADS)

Dairies are a major source of volatile organic compounds (VOCs) in California's San Joaquin Valley; a region that experiences high ozone levels during summer. Short-chain carboxylic acids, or volatile fatty acids (VFAs), are believed to make up a large fraction of VOC emissions from these facilities, although there are few studies to substantiate this. In this work, a method using a flux chamber coupled to solid phase micro-extraction (SPME) fibers followed by analysis using gas chromatography/mass spectrometry was developed to quantify emissions of six VFAs (acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid and 3-methyl butanoic acid) from non-enteric sources. The technique was then used to quantify VFA fluxes from a small dairy located on the campus of California State University Fresno. Both animal feed and animal waste are found to be major sources of VFAs, with acetic acid contributing 70-90% of emissions from the sources tested. Measured total acid fluxes during spring (with an average temperature of 20 °C) were 1.84 ± 0.01, 1.06 ± 0.08, (1.3 ± 0.5) × 10 -2, (1.7 ± 0.2) × 10 -2 and (1.2 ± 0.5) × 10 -2 g m -2 h -1 from silage, total mixed rations, flushing lane, open lot and lagoon sources, respectively. VFA emissions from the sources tested total 390 ± 80 g h -1. The data indicate high fluxes of VFAs from dairy facilities, but differences in the design and operation of dairies in the San Joaquin Valley as well as seasonal variations mean that additional measurements must be made to accurately determine emissions inventories for the region.

Alanis, Phillip; Sorenson, Mark; Beene, Matt; Krauter, Charles; Shamp, Brian; Hasson, Alam S.

235

Identification of metabolites from liquid chromatography-coulometric array detection profiling: gas chromatography-mass spectrometry and refractionation provide essential information orthogonal to LC-MS/microNMR.  

PubMed

Liquid chromatography-coulometric array detection (LC-EC) is a sensitive, quantitative, and robust metabolomics profiling tool that complements the commonly used mass spectrometry (MS) and nuclear magnetic resonance (NMR)-based approaches. However, LC-EC provides little structural information. We recently demonstrated a workflow for the structural characterization of metabolites detected by LC-EC profiling combined with LC-electrospray ionization (ESI)-MS and microNMR. This methodology is now extended to include (i) gas chromatography (GC)-electron ionization (EI)-MS analysis to fill structural gaps left by LC-ESI-MS and NMR and (ii) secondary fractionation of LC-collected fractions containing multiple coeluting analytes. GC-EI-MS spectra have more informative fragment ions that are reproducible for database searches. Secondary fractionation provides enhanced metabolite characterization by reducing spectral overlap in NMR and ion suppression in LC-ESI-MS. The need for these additional methods in the analysis of the broad chemical classes and concentration ranges found in plasma is illustrated with discussion of four specific examples: (i) characterization of compounds for which one or more of the detectors is insensitive (e.g., positional isomers in LC-MS, the direct detection of carboxylic groups and sulfonic groups in (1)H NMR, or nonvolatile species in GC-MS), (ii) detection of labile compounds, (iii) resolution of closely eluting and/or coeluting compounds, and (iv) the capability to harness structural similarities common in many biologically related, LC-EC-detectable compounds. PMID:24657819

Gathungu, Rose M; Bird, Susan S; Sheldon, Diane P; Kautz, Roger; Vouros, Paul; Matson, Wayne R; Kristal, Bruce S

2014-06-01

236

Investigation of the Biodegradation of Chlorinated Ethenes at the Pore-Scale Using Silicon- Based Micromodels  

NASA Astrophysics Data System (ADS)

Groundwater contamination by chlorinated ethenes is a matter of serious concern in industrialized countries due to the hazardous nature of these solvents. Biodegradation of these contaminants has proved to be the most cost-effective remediation technology to solve this problem. One of the most common degradation pathways is anaerobic reductive dechlorination, in which chlorinated ethenes are successively reduced from PCE to TCE to DCE to Vinyl chloride and finally to ethene, an environmentally benign substance. The success rates of this degradation with batch cultures are not often repeatable in column or field scale experiments due to the complexities associated with the heterogeneous porous medium. Hence it is important to understand degradation phenomena at the pore-scale in order to devise successful remediation techniques at a larger scale. In this study, 1 cm2 silicon based micromodels were used to simulate the subsurface at the pore-scale. The microbial culture used was Dehalospirillum multivorans. A solution of PCE (0.2 mM) and lactate (1 mM) was fed continuously into the micromodel at a rate of 0.001ml/min, which translated to a Darcy velocity in the porous matrix of 9.6m/day. Micromodels were observed with epi-fluorescence and DIC microscopy with a microscope equipped with an automated stage, CCD camera and an image analysis system. Activity within the micromodel was verified by the presence of cis-DCE in the effluent, which indicated that 95% of the PCE had been degraded. Visible biomass was also observed within a few weeks of starting PCE feeding both by DIC and fluorescence microscopy. The active and inactive zones of degradation were identified by the use of pH sensitive fluorescent dyes. The aggregates of cell biomass were quantified based on their area and perimeter in the images. These measurements indicated that after a few weeks, the biomass had reached a steady-state with new cells growing at the same rate as the sloughing of old biomass. This is the first time an anaerobic organism had been successfully grown in a micromodel. Further experiments are being planned to conduct biodegradation experiments with mixed cultures in the presence of competing electron acceptors and with PCE as a separate phase in the micromodel.

Nambi, I. M.; Werth, C. J.; Sanford, R. A.

2001-05-01

237

Silicon-Based Optical Waveguide Modulators and Mode-Locked TITANIUM:SAPPHIRE Laser Dynamics.  

NASA Astrophysics Data System (ADS)

Single-mode deeply-etched silicon-germanium/silicon (SiGe/Si) rib waveguides have been fabricated and characterized with low propagation losses and strong guiding. Such a waveguide structure is suitable for bent waveguide devices and provides efficient field overlapping, which is needed for devices requiring strong nonlinear coupling. Using the deeply-etched waveguide technique, we have fabricated Si/SiGe/Si Mach-Zehnder modulators, which show strong single-mode waveguiding but only small electro -optic modulation has been observed so far. Another Si modulator is a Fabry-Perot interferometer. We have demonstrated all-optical modulation at 1.3 ?m and 1.5 ?m in the reflection mode of the asymmetric Si Fabry-Perot interferometer by a control light beam at 0.85 mum. Both switching -on and switching-off operations are demonstrated by transversely moving the etalon. In addition, we have analyzed that silicon carbide (SiC) waveguides exhibit low loss for fundamental modes and high loss for higher-order modes at wavelengths from 0.6 to 1.6 mum. Electro-optic modulation is analyzed with a SiC-on-SiO_2 waveguide structure. Such modulators are potential candidates for high-speed electro-optic modulation for silicon-based optoelectronic devices. Furthermore, we studied the dynamics of a Kerr -lens self-mode-locked Ti:sapphire laser, generating 40 -fs pulses and tunable from 750 nm to 920 nm. A moving mirror was first proposed as a starting mechanism for self -mode locking and the starting dynamics is studied in detail. In addition, periodic pulse-train amplitude modulations have been observed and studied. The observation of the amplitude modulation further confirms the dynamic Kerr-lens self -focusing model of self-mode locking in Ti:sapphire lasers and helps us better understand the laser performance. Furthermore, dual-wavelength mode locking is observed over a broad tuning range, which would be very useful for two-wavelength subpicosecond optical sampling, such as pump-probe experiments that require different wavelengths for pumping and probing.

Liu, Yanming

238

Millimeter-wave silicon-based ultra-wideband automotive radar transceivers  

NASA Astrophysics Data System (ADS)

Since the invention of the integrated circuit, the semiconductor industry has revolutionized the world in ways no one had ever anticipated. With the advent of silicon technologies, consumer electronics became light-weight and affordable and paved the way for an Information-Communication-Entertainment age. While silicon almost completely replaced compound semiconductors from these markets, it has been unable to compete in areas with more stringent requirements due to technology limitations. One of these areas is automotive radar sensors, which will enable next-generation collision-warning systems in automobiles. A low-cost implementation is absolutely essential for widespread use of these systems, which leads us to the subject of this dissertation---silicon-based solutions for automotive radars. This dissertation presents architectures and design techniques for mm-wave automotive radar transceivers. Several fully-integrated transceivers and receivers operating at 22-29 GHz and 77-81 GHz are demonstrated in both CMOS and SiGe BiCMOS technologies. Excellent performance is achieved indicating the suitability of silicon technologies for automotive radar sensors. The first CMOS 22-29-GHz pulse-radar receiver front-end for ultra-wideband radars is presented. The chip includes a low noise amplifier, I/Q mixers, quadrature voltage-controlled oscillators, pulse formers and variable-gain amplifiers. Fabricated in 0.18-mum CMOS, the receiver achieves a conversion gain of 35-38.1 dB and a noise figure of 5.5-7.4 dB. Integration of multi-mode multi-band transceivers on a single chip will enable next-generation low-cost automotive radar sensors. Two highly-integrated silicon ICs are designed in a 0.18-mum BiCMOS technology. These designs are also the first reported demonstrations of mm-wave circuits with high-speed digital circuits on the same chip. The first mm-wave dual-band frequency synthesizer and transceiver, operating in the 24-GHz and 77-GHz bands, are demonstrated. All circuits except the oscillators are shared between the two bands. A multi-functional injection-locked circuit is used after the oscillators to reconfigure the division ratio inside the phase-locked loop. The synthesizer is suitable for integration in automotive radar transceivers and heterodyne receivers for 94-GHz imaging applications. The transceiver chip includes a dual-band low noise amplifier, a shared downconversion chain, dual-band pulse formers, power amplifiers, a dual-band frequency synthesizer and a high-speed programmable baseband pulse generator. Radar functionality is demonstrated using loopback measurements.

Jain, Vipul

239

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.

2014-01-28

240

A Compact and Highly Efficient Silicon-Based Asymmetric Mach—Zehnder Modulator with Broadband Spectral Operation  

NASA Astrophysics Data System (ADS)

An asymmetric Mach—Zehnder electro-optic modulator is demonstrated by using a silicon-based p-i-n diode embedded in compact 200 ?m long phase shifters. The measured figure of merit V?L = 0.23 V ·mm shows highly efficient modulation by the device, and an open eye-diagram at 3.2 Gbit/s confirmed its fast electro-optic response. Integrated with the grating coupler, the device exhibits a broad operational wavelength range of 70 nm with a uniform 18 dB extinction ratio covering the C-band and part L-band of optical communication.

Zhou, Liang; Li, Zhi-Yong; Xiao, Xi; Xu, Hai-Hua; Fan, Zhong-Chao; Han, Wei-Hua; Yu, Yu-De; Yu, Jin-Zhong

2011-07-01

241

A review: mid-infrared photonic crystals in silicon and porous silicon based on ion beam irradiation  

NASA Astrophysics Data System (ADS)

Silicon and porous silicon based photonic crystals are key aspects of photonic circuits with good compatibility with integrated circuits. Here a brief review is carried out on the fabrication of mid infrared photonic crystals using experimental processes of combining ion beam irradiation and electrochemical anodisation of silicon. Experimental processes have been developed to fabricate high aspect ratio trenches in porous silicon, high aspect ratio silicon pillars, buried channels in porous silicon, and multilevel freestanding silicon wires. These structures have the potential to be used for photonic crystals. Several 2D, quasi-3D and 3D mid infrared photonic crystals in porous silicon and silicon have been designed and fabricated.

Dang, Zhiya; Breese, Mark; Liu, Dongqing; Turaga, Shuvan Prashant; Azimi, Sara; Song, Jiao; Banas, Agnieszka; Recio-Sánchez, Gonzalo

2014-11-01

242

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

243

Micro-structured electrode arrays  

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 ?m-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 (RF, 13.56MHz) voltages (80–390V in Ne,

Lutz Baars-Hibbe; Christian Schrader; Philipp Sichler; Thorben Cordes; Karl-Heinz Gericke; Stephanus Büttgenbach; Siegfried Draeger

2004-01-01

244

Biocompatibility Assessment of Si-based Nano- and Micro-particles  

PubMed Central

Silicon is one of the most abundant chemical elements found on the Earth. Due to its unique chemical and physical properties, silicon based materials and their oxides (e.g. silica) have been used in several industries such as building and construction, electronics, food industry, consumer products and biomedical engineering/medicine. This review summarizes studies on effects of silicon and silica nano- and micro-particles on cells and organs following four main exposure routes, namely, intravenous, pulmonary, dermal and oral. Further, possible genotoxic effects of silica based nanoparticles are discussed. The review concludes with an outlook on improving and standardizing biocompatibility assessment for nano- and micro-particles. PMID:22634160

Jaganathan, Hamsa; Godin, Biana

2012-01-01

245

Structural and oxidative changes in the kidney of crucian carp induced by silicon-based quantum dots.  

PubMed

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. PMID:22949855

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

246

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. PMID:22949855

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

247

Fabrication of stabilized piezoelectric thick film for silicon-based MEMS device  

NASA Astrophysics Data System (ADS)

Electrical properties of piezoelectric thick films with controlled microstructure were investigated. In order to enhance the electromechanical properties (e.g. d31, d33) of a thick film by control of its microstructure, a mixed powder, referred to as BNP, consisting of both nano-sized and micro-sized piezoelectric particles, was employed as a starting precursor in the film fabrication process. According to a scanning electron microscopy study, it is shown that a BNP thick film exhibits the densest homogeneous microstructures. According to surface area measurements, the BNP thick film was sufficiently densified without an additional infiltration process of Pb(Zr1-xTix)O3 sol for densification. The screen-printed BNP thick film possesses a dielectric constant and a remanent polarization much higher than those of a thick film composed of only micro-sized piezoelectric particles by a factor of more than two. This suggests the potential application of the BNP thick film, in conjunction with a silicon substrate, to a micromachined monolithic PZT thick film device on the silicon substrate.

Kwon, T. Y.; Kim, Y. B.; Eom, K.; Yoon, D. S.; Lee, H. L.; Kim, T. S.

2007-09-01

248

A thermally self-sustained micro-power plant with integrated micro-solid oxide fuel cells, micro-reformer and functional micro-fluidic carrier  

NASA Astrophysics Data System (ADS)

Low temperature micro-solid oxide fuel cell (micro-SOFC) systems are an attractive alternative power source for small-size portable electronic devices due to their high energy efficiency and density. Here, we report on a thermally self-sustainable reformer-micro-SOFC assembly. The device consists of a micro-reformer bonded to a silicon chip containing 30 micro-SOFC membranes and a functional glass carrier with gas channels and screen-printed heaters for start-up. Thermal independence of the device from the externally powered heater is achieved by exothermic reforming reactions above 470 °C. The reforming reaction and the fuel gas flow rate of the n-butane/air gas mixture controls the operation temperature and gas composition on the micro-SOFC membrane. In the temperature range between 505 °C and 570 °C, the gas composition after the micro-reformer consists of 12 vol.% to 28 vol.% H2. An open-circuit voltage of 1.0 V and maximum power density of 47 mW cm-2 at 565 °C is achieved with the on-chip produced hydrogen at the micro-SOFC membranes.

Scherrer, Barbara; Evans, Anna; Santis-Alvarez, Alejandro J.; Jiang, Bo; Martynczuk, Julia; Galinski, Henning; Nabavi, Majid; Prestat, Michel; Tölke, René; Bieberle-Hütter, Anja; Poulikakos, Dimos; Muralt, Paul; Niedermann, Philippe; Dommann, Alex; Maeder, Thomas; Heeb, Peter; Straessle, Valentin; Muller, Claude; Gauckler, Ludwig J.

2014-07-01

249

Focused ion beam high resolution grayscale lithography for silicon-based nanostructures  

SciTech Connect

Nanofabrication techniques providing a fine control over the profile of silicon structures are of great importance for nanophotonics, plasmonics, sensing, micro- and nano fluidics, and biomedical applications. We report on the applicability of focused ion beam for the fine grayscale lithography, which yields surface profiles that are customized at nanoscale. The approach is based on a correlation between the ion beam irradiation dose of inorganic resist and the mask etching rate in the reactive ion etching. An exceptional property of this method is the number of gray tones that are not limited by the resist characteristics. We apply the process to fabricate unique periodic nanostructures with a slope angle varying across the structure and a period as small as 200?nm.

Erdmanis, M., E-mail: mikhail.erdmanis@aalto.fi; Tittonen, I. [Department of Micro- and Nanosciences, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland)

2014-02-17

250

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

251

THz-wave generation via difference frequency mixing in strained silicon based waveguide utilizing its second order susceptibility ?((2)).  

PubMed

Terahertz (THz) wave generation via difference frequency mixing (DFM) process in strain silicon membrane waveguides by introducing the straining layer is theoretically investigated. The Si(3)N(4) straining layer induces anisotropic compressive strain in the silicon core and results in the appearance of the bulk second order nonlinear susceptibility ?((2)) by breaking the crystal symmetry. We have proposed waveguide structures for THz wave generation under the DFM process by .using the modal birefringence in the waveguide core. Our simulations show that an output power of up to 0.95 mW can be achieved at 9.09 THz. The strained silicon optical device may open a widow in the field of the silicon-based active THz photonic device applications. PMID:25090484

Saito, Kyosuke; Tanabe, Tadao; Oyama, Yutaka

2014-07-14

252

High temperature electrical conductivity and thermal decomposition of phenolic- and silicon-based dielectrics for fireset housings  

SciTech Connect

The temperature dependence of the electrical conductivity and thermal decomposition characteristics of several phenolic- and silicone-based materials of interest for fireset case housings have been measured to 600 to 700/sup 0/C. The materials are phenolic or silicone resins reinforced with glass chopped fabric or cloth. The conductivity temperature dependence was measured during decomposition in a nitrogen atmosphere at a heating rate of approx. 10/sup 0/C/minute. Applied electric fields were from 4 x 10/sup 2/ to 4 x 10/sup 3/ volts/cm. Thermal decomposition characteristics were investigated by mass spectroscopy in vacuum and thermal gravimetric analysis in nitrogen and air. Nearly ohmic voltage-current characteristics were obtained, except where decomposition and/or outgassing was pronounced.

Johnson, R.T. Jr.; Biefeld, R.M.

1981-08-01

253

InGaAlAsPN: A Materials System for Silicon Based Optoelectronics and Heterostructure Device Technologies  

NASA Technical Reports Server (NTRS)

A new material system is proposed for silicon based opto-electronic and heterostructure devices; the silicon lattice matched compositions of the (In,Ga,Al)-(As,P)N 3-5 compounds. In this nitride alloy material system, the bandgap is expected to be direct at the silicon lattice matched compositions with a bandgap range most likely to be in the infrared to visible. At lattice constants ranging between those of silicon carbide and silicon, a wider bandgap range is expected to be available and the high quality material obtained through lattice matching could enable applications such as monolithic color displays, high efficiency multi-junction solar cells, opto-electronic integrated circuits for fiber communications, and the transfer of existing 3-5 technology to silicon.

Broekaert, T. P. E.; Tang, S.; Wallace, R. M.; Beam, E. A., III; Duncan, W. M.; Kao, Y. -C.; Liu, H. -Y.

1995-01-01

254

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

255

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. 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

256

Synthesis of silicon-based nanoparticles by 10.6 ?m nanosecond CO2 laser ablation in liquid  

NASA Astrophysics Data System (ADS)

Silicon-based nanoparticles were produced by irradiating a single-crystal silicon target with 10.6 ?m nanosecond transverse excited atmospheric (TEA) pulsed CO2 laser in de-ionized water. The effects of the laser pulse energies and repetition rate were studied. To reveal the role of thermal effects, a low laser repetition rate has been applied, excluding the interaction of the laser beam with the previously generated cavitation bubble. The analysis of the influence of the laser pulse energies and the laser repetition rate showed that the increase of the laser pulse energies leads to an increase of the nanoparticle size. An explanation of such results was proposed and the importance of the role of the target surface temperature in the ablation process is discussed.

Popovic, D. M.; Chai, J. S.; Zekic, A. A.; Trtica, M.; Momcilovic, M.; Maletic, S.

2013-02-01

257

Recent Developments in Mems-Based Micro Fuel Cells  

E-print Network

Micro fuel cells ($\\mu$-FC) represent promising power sources for portable applications. Today, one of the technological ways to make $\\mu$-FC is to have recourse to standard microfabrication techniques used in the fabrication of micro electromechanical systems (MEMS). This paper shows an overview on the applications of MEMS techniques on miniature FC by presenting several solutions developed throughout the world. It also describes the latest developments of a new porous silicon-based miniature fuel cell. Using a silane grafted on an inorganic porous media as the proton-exchange membrane instead of a common ionomer such as Nafion, the fuel cell achieved a maximum power density of 58 mW cm-2 at room temperature with hydrogen as fuel.

Pichonat, T

2007-01-01

258

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

259

Understanding Micro Plasmas  

E-print Network

Micro plasmas are operated around atmospheric pressure exhibiting pronounced non-equilibrium characteristics, i.e. they possess energetic electrons while ions and neutrals remain cold. They have gained significant interest due to their enormous application potential e.g. in the biomedical, surface modification and light source areas, just to name a few. Many different configurations are in use. Their understanding and quantification is mandatory for further progress in applications. We report on recent progress in the diagnostics and simulation of the entire micro plasma system from gas introduction, via the plasma discharge up to the samples at the example of a plasma jet operated in He/O2 in an ambient air environment.

Winter, J; Böke, M; Ellerweg, D; Hemke, T; Knake, N; Mussenbrock, T; Niermann, B; Schröder, D; der Gathen, V Schulz-von; von Keudell, A

2011-01-01

260

The influence of applying the additional continuous laser on the synthesis of silicon-based nanoparticles by picosecond laser ablation in liquid  

NASA Astrophysics Data System (ADS)

Silicon-based nanoparticles are synthesized by picosecond laser ablation in liquid using silicon single-crystal plates as targets. We demonstrated that applying the additional continuous laser immediately prior to and during the ablation changed the size distribution and oxygen content of the nanoparticles produced. This opens up the possibility of using the continuous laser as a simple tool for tailoring nanoparticle properties.

Popovic, D. M.; Chai, J. S.; Zekic, A. A.; Trtica, M.; Stasic, J.; Sarvan, M. Z.

2014-11-01

261

Graphene and New Electronic Materials Silicon-based electronics will reach its fundamental limits over the next 6-10 years. This will  

E-print Network

and therefore on the electronics industry. Alternative materials, processes, and devices must be developedGraphene and New Electronic Materials Silicon-based electronics will reach its fundamental limits over the next 6-10 years. This will have a significant impact on future electronic devices and circuits

Li, Mo

262

Development of a liquid-fueled micro-combustor  

E-print Network

Advances in Micro-Electro-Mechanical Systems (MEMS) have made possible the development of shirtbutton-sized gas turbine engines for use as portable power sources. As part of an effort to develop a microscale gas turbine ...

Peck, Jhongwoo, 1976-

2008-01-01

263

Flow injection solid-phase extraction using multi-walled carbon nanotubes packed micro-column for the determination of polycyclic aromatic hydrocarbons in water by gas chromatography-mass spectrometry.  

PubMed

A flow injection solid-phase extraction preconcentration system using a multi-walled carbon nanotubes (MWCNTs) packed micro-column was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in water by gas chromatography-mass spectrometry (GC-MS). The preconcentration of PAHs on the MWCNTs was carried out based on the adsorption retention of analytes by on-line introducing the sample into the micro-column system. Methanol was introduced to elute the retained analytes for GC-MS analysis using selected ion monitoring (SIM) mode. Important influence factors were studied in detail, such as sample acidity, sample flow rate, eluent flow rate and volume, dimensions of MWCNTs and amounts of packing material. Limits of detection of 16 PAHs for an extraction of 50 mL water sample were in the range of 0.001-0.15 microg L(-1), and the precisions (RSD) were in the range of 4-14%. The optimized method was successfully applied to the determination of 16 PAHs in surface waters, with recoveries in the range of 72-93% for real spiked sample. PMID:20236647

Wu, Hong; Wang, Xuecui; Liu, Bing; Lu, Jie; Du, Baixiang; Zhang, Luxin; Ji, Jingjing; Yue, Qiaoyu; Han, Baoping

2010-04-23

264

Thermal conductivity of a graphite bipolar plate (BPP) and its thermal contact resistance with fuel cell gas diffusion layers: Effect of compression, PTFE, micro porous layer (MPL), BPP out-of-flatness and cyclic load  

NASA Astrophysics Data System (ADS)

This paper reports on measurements of thermal conductivity of a graphite bipolar plate (BPP) as a function of temperature and its thermal contact resistance (TCR) with treated and untreated gas diffusion layers (GDLs). The thermal conductivity of the BPP decreases with temperature and its thermal contact resistance with GDLs, which has been overlooked in the literature, is found to be dominant over a relatively wide range of compression. The effects of PTFE loading, micro porous layer (MPL), compression, and BPP out-of-flatness are also investigated experimentally. It is found that high PTFE loadings, MPL and even small BPP out-of-flatness increase the BPP-GDL thermal contact resistance dramatically. The paper also presents the effect of cyclic load on the total resistance of a GDL-BPP assembly, which sheds light on the behavior of these materials under operating conditions in polymer electrolyte membrane fuel cells.

Sadeghifar, Hamidreza; Djilali, Ned; Bahrami, Majid

2015-01-01

265

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

266

An algorithm for selection and design of hybrid power supplies for MEMS with a case study of a micro-gas chromatograph system  

NASA Astrophysics Data System (ADS)

The Wireless Integrated Microsystems (WIMS)-environmental monitor testbed (EMT) is a multi-component microelectromechanical system (MEMS), incorporating complementary metal oxide semiconductor (CMOS) materials for high-precision circuits used for integrated sensors such as micro-g accelerometers, micro-gyroscopes, and pressure sensors. The WIMS-EMT duty cycle, like many autonomous MEMS systems, has low-power standby periods for sensing, and high-power pulses for R/F transmission and reception. In this paper, we present results of three strategies for providing power to this system, including (1) specification of a single, aggregate power supply, resulting in a single battery electrochemistry and cell size; (2) specification of several power supplies, by a priori division of power sources by power range; and (3) specification of an arbitrary number of power "bundles," based on available space in the device. The second approach provided the best results of mass (0.032 kg) and volume (0.028 L) among the three approaches. The second and third approaches provided the best battery lifetime results; both systems produced lifetimes in excess of 2E3 h. Future work will incorporate CMOS operational amplifier (op-amp) technologies to accommodate large voltage fluxes in many MEMS devices, and implementation of our approaches into a user-friendly code.

Cook, K. A.; Sastry, A. M.

267

PREFACE: E-MRS 2012 Spring Meeting, Symposium M: More than Moore: Novel materials approaches for functionalized Silicon based Microelectronics  

NASA Astrophysics Data System (ADS)

More than Moore explores a new area of Silicon based microelectronics, which reaches beyond the boundaries of conventional semiconductor applications. Creating new functionality to semiconductor circuits, More than Moore focuses on motivating new technological possibilities. In the past decades, the main stream of microelectronics progresses was mainly powered by Moore's law, with two focused development arenas, namely, IC miniaturization down to nano scale, and SoC based system integration. While the microelectronics community continues to invent new solutions around the world to keep Moore's law alive, there is increasing momentum for the development of 'More than Moore' technologies which are based on silicon technologies but do not simply scale with Moore's law. Typical examples are RF, Power/HV, Passives, Sensor/Actuator/MEMS or Bio-chips. The More than Moore strategy is driven by the increasing social needs for high level heterogeneous system integration including non-digital functions, the necessity to speed up innovative product creation and to broaden the product portfolio of wafer fabs, and the limiting cost and time factors of advanced SoC development. It is believed that More than Moore will add value to society on top of and beyond advanced CMOS with fast increasing marketing potentials. Important key challenges for the realization of the 'More than Moore' strategy are: perspective materials for future THz devices materials systems for embedded sensors and actuators perspective materials for epitaxial approaches material systems for embedded innovative memory technologies development of new materials with customized characteristics The Hot topics covered by the symposium M (More than Moore: Novel materials approaches for functionalized Silicon based Microelectronics) at E-MRS 2012 Spring Meeting, 14-18 May 2012 have been: development of functional ceramics thin films New dielectric materials for advanced microelectronics bio- and CMOS compatible material systems piezoelectric films and nanostructures Atomic Layer Deposition (ALD) of oxides and nitrides characterization and metrology of very thin oxide layers We would like to take this opportunity to thank the Scientific Committee and Local Committee for bringing together a coherent and high quality Symposium at E-MRS 2012 Spring Meeting. Christian Wenger, Jean Fompeyrine, Christophe Vallée and Jean-Pierre Locquet Organizing Committee of Symposium M September 2012

Wenger, Christian; Fompeyrine, Jean; Vallée, Christophe; Locquet, Jean-Pierre

2012-12-01

268

Connecting the Micro-dynamics to the Emergent Macro-variables: Self-Organized Criticality and Absorbing Phase Transitions in the Deterministic Lattice Gas  

E-print Network

We reinvestigate the Deterministic Lattice Gas introduced as a paradigmatic model of the 1/f spectra (Phys. Rev. Lett. V26, 3103 (1990)) arising according to the Self-Organized Criticality scenario. We demonstrate that the density fluctuations exhibit an unexpected dependence on systems size and relate the finding to effective Langevin equations. The low density behavior is controlled by the critical properties of the gas at the absorbing state phase transition. We also show that the Deterministic Lattice Gas is in the Manna universality class of absorbing state phase transitions. This is in contrast to expectations in the literature which suggested that the entirely deterministic nature of the dynamics would put the model in a different universality class. To our knowledge this is the first fully deterministic member of the Manna universality class.

Andrea Giometto; Henrik Jeldtoft Jensen

2011-10-12

269

Connecting the Micro-dynamics to the Emergent Macro-variables: Self-Organized Criticality and Absorbing Phase Transitions in the Deterministic Lattice Gas  

E-print Network

We reinvestigate the Deterministic Lattice Gas introduced as a paradigmatic model of the 1/f spectra (Phys. Rev. Lett. V26, 3103 (1990)) arising according to the Self-Organized Criticality scenario. We demonstrate that the density fluctuations exhibit an unexpected dependence on systems size and relate the finding to effective Langevin equations. The low density behavior is controlled by the critical properties of the gas at the absorbing state phase transition. We also show that the Deterministic Lattice Gas is in the Manna universality class of absorbing state phase transitions. This is in contrast to expectations in the literature which suggested that the entirely deterministic nature of the dynamics would put the model in a different universality class. To our knowledge this is the first fully deterministic member of the Manna universality class.

Giometto, Andrea

2011-01-01

270

Gas-surface interactions using accommodation coefficients for a dilute and a dense gas in a micro- or nanochannel: Heat flux predictions using combined molecular dynamics and Monte Carlo techniques  

NASA Astrophysics Data System (ADS)

The influence of gas-surface interactions of a dilute gas confined between two parallel walls on the heat flux predictions is investigated using a combined Monte Carlo (MC) and molecular dynamics (MD) approach. The accommodation coefficients are computed from the temperature of incident and reflected molecules in molecular dynamics and used as effective coefficients in Maxwell-like boundary conditions in Monte Carlo simulations. Hydrophobic and hydrophilic wall interactions are studied, and the effect of the gas-surface interaction potential on the heat flux and other characteristic parameters like density and temperature is shown. The heat flux dependence on the accommodation coefficient is shown for different fluid-wall mass ratios. We find that the accommodation coefficient is increasing considerably when the mass ratio is decreased. An effective map of the heat flux depending on the accommodation coefficient is given and we show that MC heat flux predictions using Maxwell boundary conditions based on the accommodation coefficient give good results when compared to pure molecular dynamics heat predictions. The accommodation coefficients computed for a dilute gas for different gas-wall interaction parameters and mass ratios are transferred to compute the heat flux predictions for a dense gas. Comparison of the heat fluxes derived using explicit MD, MC with Maxwell-like boundary conditions based on the accommodation coefficients, and pure Maxwell boundary conditions are discussed. A map of the heat flux dependence on the accommodation coefficients for a dense gas, and the effective accommodation coefficients for different gas-wall interactions are given. In the end, this approach is applied to study the gas-surface interactions of argon and xenon molecules on a platinum surface. The derived accommodation coefficients are compared with values of experimental results.

Nedea, S. V.; van Steenhoven, A. A.; Markvoort, A. J.; Spijker, P.; Giordano, D.

2014-05-01

271

Theory and experimental validation of cross-flow micro-channel heat exchanger module with reference to high Mach aircraft gas turbine engines  

Microsoft Academic Search

This study explores the design, analysis, and performance assessment of a new class of heat exchangers intended for high Mach aircraft gas turbine engines. Because the compressor air that is used to cool turbine blades and other components in a high Mach engine is itself too hot, aircraft fuel is needed to precool the compressor air, cooling is achieved with

Robert Nacke; Brittany Northcutt; Issam Mudawar

2011-01-01

272

iHWG-?NIR: a miniaturised near-infrared gas sensor based on substrate-integrated hollow waveguides coupled to a micro-NIR-spectrophotometer.  

PubMed

A miniaturised gas analyser is described and evaluated based on the use of a substrate-integrated hollow waveguide (iHWG) coupled to a microsized near-infrared spectrophotometer comprising a linear variable filter and an array of InGaAs detectors. This gas sensing system was applied to analyse surrogate samples of natural fuel gas containing methane, ethane, propane and butane, quantified by using multivariate regression models based on partial least square (PLS) algorithms and Savitzky-Golay 1(st) derivative data preprocessing. The external validation of the obtained models reveals root mean square errors of prediction of 0.37, 0.36, 0.67 and 0.37% (v/v), for methane, ethane, propane and butane, respectively. The developed sensing system provides particularly rapid response times upon composition changes of the gaseous sample (approximately 2 s) due the minute volume of the iHWG-based measurement cell. The sensing system developed in this study is fully portable with a hand-held sized analyser footprint, and thus ideally suited for field analysis. Last but not least, the obtained results corroborate the potential of NIR-iHWG analysers for monitoring the quality of natural gas and petrochemical gaseous products. PMID:24867650

Rohwedder, J J R; Pasquini, C; Fortes, P R; Raimundo, I M; Wilk, A; Mizaikoff, B

2014-07-21

273

Critical evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following high-pressure gas and micro-particle abrasion.  

PubMed

Infundibular caries of the equine maxillary cheek teeth is an important disorder that can lead to dental fracture or apical infection. Treatment by removing food debris and carious dental tissue from affected infundibulae using high-pressure abrasion with aluminium hydroxide micro-particles, followed by filling the cleaned defect with endodontic restorative materials is a recommended treatment. However, although anecdotally considered a successful treatment option, there is currently no objective evidence to support this claim. Forty maxillary cheek teeth (CT) that contained 55 infundibulae with caries (mainly grade 2) were extracted post-mortem from 21 adult horses. Five of the CT were sectioned prior to treatment to facilitate visual examination of the carious infundibulae. The remaining carious infundibulae were cleaned using high-pressure abrasion with aluminium hydroxide particles and five CT were sectioned to assess the efficacy of this cleaning process. The remaining 30 CT containing 39 carious infundibulae were then filled with a composite restorative material. The efficacy of this restoration was assessed by computed tomography imaging followed by direct visual examination after sectioning the teeth. Only 46% (18/39) of restored infundibulae, all with shallow (mean 9.6?mm deep) defects, were fully cleaned of food debris and carious material, and filled with restorative material to their full depth. Of these 18, 11 had peripheral defects around the restoration, leaving just 18% (7/39) of restorations without any gross defects. The remaining 54% (21/39) of infundibulae (mean depth of infundibular caries defect, 18.3?mm) still contained food debris and/or carious material in more apical locations, with infundibulae with the deepest caries defects being the least effectively cleaned. The findings of this study indicate that high-pressure micro-particle abrasion is only effective in cleaning food debris from shallow, carious CT infundibulae and consequently, the majority of subsequent infundibular restorations are imperfect. PMID:24792205

Dixon, P M; Savill, D; Horbyl, A; Reardon, R J M; Liuti, T

2014-06-01

274

Application of floating silicon-based linear multielectrode arrays for acute recording of single neuron activity in awake behaving monkeys.  

PubMed

One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady recording of action potentials of many single neurons for as long as possible. Here, we present single neuron data obtained during acute recordings mainly from premotor cortices of three macaque monkeys using a silicon-based linear multielectrode array. The most important aspect of these probes, compared with similar models commercially available, is that, once inserted into the brain using a dedicated insertion device providing an intermediate probe fixation by means of vacuum, they can be released and left floating in the brain. On the basis of our data, these features appear to provide (i) optimal physiological conditions for extracellular recordings, (ii) good or even excellent signal-to-noise ratio depending on the recorded brain area and cortical layer, and (iii) extreme stability of the signal over relatively long periods. The quality of the recorded signal did not change significantly after several penetrations into the same restricted cortical sector, suggesting limited tissue damage due to probe insertion. These results indicate that these probes offer several advantages for acute neurophysiological experiments in awake monkeys, and suggest the possibility to employ them for semichronic or even chronic studies. PMID:24434299

Bonini, Luca; Maranesi, Monica; Livi, Alessandro; Bruni, Stefania; Fogassi, Leonardo; Holzhammer, Tobias; Paul, Oliver; Ruther, Patrick

2014-08-01

275

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. PMID:22020666

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

2012-01-01

276

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

PubMed Central

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 ?m. 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 ~55% at close to zero spatial frequency at an exposure of 32.8 mR, and decreases to ~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, Srinivasan; Karellas, Andrew; Suryanarayanan, Sankararaman; Albagli, Douglas; Han, Sung; Tkaczyk, Eric J.; Landberg, Cynthia E.; Opsahl-Ong, Beale; Granfors, Paul R.; Levis, Ilias; D’Orsi, Carl J.; Hendrick, R. Edward

2008-01-01

277

Nonlinear phenomenon in monocrystalline silicon based PV module for low power system: Lead acid battery for low energy storage  

NASA Astrophysics Data System (ADS)

In the present work, we report the indoor photo-electrical measurements of monocrystalline silicon based photovoltaic (PV) module associated with 4 Ah lead acid battery as a storage unit for low power PV system applications. Concerning the PV module, our measurements show, at low illumination regime, that the short circuit current ISC increases linearly with the illumination power levels. Moreover, for high illumination levels, the mechanism of bimolecular recombination and space charge limitation may be intensified and hence the short current of the PV module ISCMod depends sublinearly on the incident optical power; the behavior is nonlinear. For the open circuit voltage of the PV module VOCMod measurements, a linear variation of the VOCMod versus the short circuit current in semi-logarithmic scale has been noticed. The diode ideality factor n and diode saturation current Is have been investigated; the values of n and Is are approximately of 1.3 and 10-9 A, respectively. In addition, we have shown, for different discharging-charging currents rates (i.e. 0.35 A, 0.2 A and 0.04 A), that the battery voltage decreases with discharging time as well as discharging battery capacity, and on the other hand it increases with the charging time and will rise up until it maximized value. The initial result shows the possibility to use such lead acid battery for low power PV system, which is generally designed for the motorcycle battery.

El Amrani, A.; El Amraoui, M.; El Abbassi, A.; Messaoudi, C.

2014-11-01

278

Response of silicon-based linear energy transfer spectrometers: implication for radiation risk assessment in space flights.  

PubMed

There is considerable interest in developing silicon-based telescopes because of their compactness and low power requirements. Three such telescopes have been flown on board the Space Shuttle to measure the linear energy transfer spectra of trapped, galactic cosmic ray, and solar energetic particles. Dosimeters based on single silicon detectors have also been flown on the Mir orbital station. A comparison of the absorbed dose and radiation quality factors calculated from these telescopes with that estimated from measurements made with a tissue equivalent proportional counter show differences which need to be fully understood if these telescopes are to be used for astronaut radiation risk assessments. Instrument performance is complicated by a variety of factors. A Monte Carlo-based technique was developed to model the behavior of both single element detectors in a proton beam, and the performance of a two-element, wide-angle telescope, in the trapped belt proton field inside the Space Shuttle. The technique is based on: (1) radiation transport intranuclear-evaporation model that takes into account the charge and angular distribution of target fragments, (2) Landau-Vavilov distribution of energy deposition allowing for electron escape, (3) true detector geometry of the telescope, (4) coincidence and discriminator settings, (5) spacecraft shielding geometry, and (6) the external space radiation environment, including albedo protons. The value of such detailed modeling and its implications in astronaut risk assessment is addressed. PMID:11858255

Badhwar, G D; O'Neill, P M

2001-07-11

279

Response of Silicon-Based Linear Energy Transfer Spectrometers: Implication for Radiation Risk Assessment in Space Flights  

NASA Technical Reports Server (NTRS)

There is considerable interest in developing silicon-based telescopes because of their compactness and low power requirements. Three such telescopes have been flown on board the Space Shuttle to measure the linear energy transfer spectra of trapped, galactic cosmic ray, and solar energetic particles. Dosimeters based on single silicon detectors have also been flown on the Mir orbital station. A comparison of the absorbed dose and radiation quality factors calculated from these telescopes with that estimated from measurements made with a tissue equivalent proportional counter show differences which need to be fully understood if these telescopes are to be used for astronaut radiation risk assessments. Instrument performance is complicated by a variety of factors. A Monte Carlo-based technique was developed to model the behavior of both single element detectors in a proton beam, and the performance of a two-element, wide-angle telescope, in the trapped belt proton field inside the Space Shuttle. The technique is based on: (1) radiation transport intranuclear-evaporation model that takes into account the charge and angular distribution of target fragments, (2) Landau-Vavilov distribution of energy deposition allowing for electron escape, (3) true detector geometry of the telescope, (4) coincidence and discriminator settings, (5) spacecraft shielding geometry, and (6) the external space radiation environment, including albedo protons. The value of such detailed modeling and its implications in astronaut risk assessment is addressed. c2001 Elsevier Science B.V. All rights reserved.

Badhwar, G. D.; O'Neill, P. M.

2001-01-01

280

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

E-print Network

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 Control-Not gate. The exchange interaction is constant and selective excitations are provided by a magnetic field gradient. The quantum logic operations are implemented by rectangular radio-frequency pulses. This architecture is scalable and does not require manufacturing nanoscale electronic gates. As shown in this paper parameters of a quantum protocol can be derived analytically even for a computer with a large number of qubits using our perturbation approach. We present the protocol for initialization of the nuclear spins and the protocol for creation of entanglement. All analytical results are tested numerically using a two-qubit system.

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

2005-12-21

281

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

Microsoft Academic Search

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-d6 was used as internal standard. MDA and acetone d6 in blood reacted for 40min at 50°C with 2,2,2-trifluoroethylhydrazine in headspace

Ho-Sang Shin

2009-01-01

282

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

Microsoft Academic Search

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 1.5min with a bead mill, and then incubated in 1mL of methanol under ultrasonication at 50°C

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

2010-01-01

283

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

284

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

285

Facile and scalable synthesis of silicon-based nanocomposites with slitlike nanopores: a solid-state exfoliation reaction using layered CaSi?.  

PubMed

Silicon-based nanocomposites with slitlike nanopores were prepared by heating a mixture of layered CaSi2 and NiCl2. The formation mechanism is based on a solid-state exfoliation reaction wherein the formation of CaCl2 promotes the extraction of Ca from CaSi2, thereby exfoliating the layered structure. The nanocomposites showed anode capacity for lithium ion batteries up to 804?mA?h?g(-1). PMID:25145780

Oh, Song-Yul; Imagawa, Haruo; Itahara, Hiroshi

2014-11-01

286

Magnetic micro-actuator  

Microsoft Academic Search

The characteristics of three types of magnetic microactuators made by silicon-based microfabrication are described. The microfabrication, actuator configuration, and dynamic characteristics of a fabricated microactuator with a planar coil are examined. This microactuator is shown to operate in the nanometer range. It has a conical soft-magnetic tip 10 microns high with a one-turn copper coil. This actuator will be applied

K. Yanagisawa; A. Tago; T. Ohkubo; H. Kuwano

1991-01-01

287

A method to detect diphenylamine contamination of apple fruit and storages using headspace solid phase micro-extraction and gas chromatography/mass spectroscopy.  

PubMed

Analysis of headspace concentrations of diphenylamine using solid phase micro-extraction (SPME) was examined for its suitability to detect DPA contamination and off-gassing in apple (Malus domestica) fruit, storage rooms and storage materials. Four SPME fibre coatings including polydimethylsiloxane (PDMS, 100 ?m), PDMS/divinylbenzene (PDMS/DVB), Polyacrylate (PA) and PDMS 7 ?m were evaluated. The average limits of detection and of quantification for head space DPA ranged from 0.13 to 0.72 ?g L(-1) and 0.42 to 2.35 ?g L(-1), respectively. Polyacrylate was identified to be the most suitable and compatible fibre for DPA analysis in apple samples, because of its high sensitivity to DPA and low fruit volatile interferences. SPME techniques were further applied to study contamination of DPA in apples, storage rooms and packaging materials. DPA was found in the air of storage rooms containing apples that were not treated with DPA. Wood and plastic bin material, bin liners, and foam insulation all adsorbed and off-gassed DPA and could be potential sources of contamination of untreated apples. PMID:24799236

Song, Jun; Forney, Charles F; Jordan, Michael A

2014-10-01

288

Effect of Surface Treatment on the Flexural Strength of Denture Base Resin and Tensile Strength of Autopolymerizing Silicone Based Denture Liner Bonded to Denture Base Resin: An In Vitro Study  

Microsoft Academic Search

Silicone based denture liners are superior to acrylic based denture liners but it has a problem of failure of adhesion with\\u000a the denture base. To evaluate the effect on the tensile bond strength of silicone based liner and flexural strength of denture\\u000a base resin when the latter is treated with different chemical etchants prior to the application of the resilient

Saloni Gupta

2010-01-01

289

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

290

Introduction Micro-view 1  

E-print Network

Introduction Micro-view 1 Micro-view 2 Micro-view 3 Micro-Mechanics of Granular Flow at Large / EM08.pdf LATEX #12;Introduction Micro-view 1 Micro-view 2 Micro-view 3 Large strain phenomena Three micro-mechanical views Introduction Granular "genre": Dense packings Slow loading Granular phenomena

Kuhn, Matthew R.

291

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

292

Fluid flow in micro-channels  

Microsoft Academic Search

We consider the problem of liquid and gas flow in micro-channels under conditions of a small Knudsen and Mach numbers, that correspond to continuum model. Data from the literature on pressure drop in circular, rectangle, triangular and trapezoidal micro-channels with hydrodynamic diameter ranging from 1.01?m to 4010?m are analyzed. The Reynolds number at transition from laminar to turbulent flow is

G. Hetsroni; A. Mosyak; E. Pogrebnyak; L. P. Yarin

2005-01-01

293

Process development of silicon-silicon carbide hybrid structures for micro-engines (January 2002)  

E-print Network

MEMS-based gas turbine engines are currently under development at MIT for use as a button-sized portable power generator or micro-aircraft propulsion sources. Power densities expected for the micro-engines require very ...

Choi, D.

294

MEMS-based hydrogen gas sensors  

Microsoft Academic Search

The widespread use of hydrogen as both an industrial process gas and an energy storage medium requires fast, selective detection of hydrogen gas. This paper reports the development of a new type of solid-state hydrogen gas sensor that couples novel metal hydride thin films with a micro-electro-mechanical system (MEMS) structure known as a micro-hotplate. Micro-hotplate structures are fabricated via surface

Frank DiMeo; Ing-Shin Chen; Philip Chen; Jeffrey Neuner; Andreas Roerhl; James Welch

2006-01-01

295

High-efficiency approach for fabricating MTE rotor by micro-EDM and micro-extrusion  

NASA Astrophysics Data System (ADS)

Micro-gas turbine engine (MTE) rotor is an important indicator of its property, therefore, the manufacturing technology of the microminiature rotor has become a hot area of research at home and abroad. At present, the main manufacturing technologies of the MTE rotor are directed forming fabrication technologies. However, these technologies have a series of problems, such as complex processing technology high manufacturing cost, and low processing efficiency, and so on. This paper takes advantage of micro electric discharge machining (micro-EDM) in the field of microminiature molds manufacturing, organizes many processing technologies of micro-EDM reasonably to improve processing accuracy, presents an integrated micro-EDM technology and its process flow to fabricate MTE rotor die, and conducts a series of experiments to verify efficiency of this integrated micro-EDM. The experiments results show that the MTE rotor die has sharp outline and ensure the good consistency of MTE rotor blades. Meanwhile, the MTE rotor die is applied to micro extrusion equipment, and technologies of micro-EDM and micro forming machining are combined based on the idea of the molds manufacturing, so the MTE rotor with higher aspect ratio and better consistency of blades can be manufactured efficiently. This research presents an integrated micro-EDM technology and its process flow, which promotes the practical process of MTE effectively.

Geng, Xuesong; Chi, Guanxin; Wang, Yukui; Wang, Zhenlong

2014-07-01

296

Micro-machined thermo-conductivity detector  

DOEpatents

A micro-machined thermal conductivity detector for a portable gas chromatograph. The detector is highly sensitive and has fast response time to enable detection of the small size gas samples in a portable gas chromatograph which are in the order of nanoliters. The high sensitivity and fast response time are achieved through micro-machined devices composed of a nickel wire, for example, on a silicon nitride window formed in a silicon member and about a millimeter square in size. In addition to operating as a thermal conductivity detector, the silicon nitride window with a micro-machined wire therein of the device can be utilized for a fast response heater for PCR applications.

Yu, Conrad (Antioch, CA)

2003-01-01

297

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

298

Fabrication of silicon-based nano-structures and their scaling effects on mechanical and electrical properties  

NASA Astrophysics Data System (ADS)

Silicon-based nanostructures are essential building blocks for nanoelectronic devices and nano-electromechanical systems (NEMS), and their mechanical and electrical properties play an important role in controlling the functionality and reliability of the nano-devices. The objective of this dissertation is twofold: The first is to investigate the mechanical properties of silicon nanolines (SiNLs) with feature size scaled into the tens of nanometer level. And the second is to study the electron transport in nickel silicide formed on the SiNLs. For the first study, a fabrication process was developed to form nanoscale Si lines using an anisotropic wet etching technique. The SiNLs possessed straight and nearly atomically flat sidewalls, almost perfectly rectangular cross sections and highly uniform linewidth at the nanometer scale. To characterize mechanical properties, an atomic force microscope (AFM) based nanoindentation system was employed to investigate three sets of silicon nanolines. The SiNLs had the linewidth ranging from 24 nm to 90 nm, and the aspect ratio (Height/linewidth) from 7 to 18. During indentation, a buckling instability was observed at a critical load, followed by a displacement burst without a load increase, then a fully recoverable deformation upon unloading. For experiments with larger indentation displacements, irrecoverable indentation displacements were observed due to fracture of Si nanolines, with the strain to failure estimated to be from 3.8% to 9.7%. These observations indicated that the buckling behavior of SiNLs depended on the combined effects of load, line geometry, and the friction at contact. This study demonstrated a valuable approach to fabrication of well-defined Si nanoline structures and the application of the nanoindentation method for investigation of their mechanical properties at the nanoscale. For the study of electron transport, a set of nickel monosilicide (NiSi) nanolines with feature size down to 15 nm was fabricated. The linewidth effect on nickel silicide formation has been studied using high-resolution transmission electron microscopy (HRTEM) for microstructural analysis. Four point probe electrical measurements showed that the residual resistivity of the NiSi lines at cryogenic temperature increased with decreasing line width, indicating effect of increased electron sidewall scattering with decreased line width. A mean free path for electron transport at room temperature of 5 nm was deduced, which suggests that nickel silicide can be used without degradation of device performance in nanoscale electronics.

Li, Bin

299

Micro direct methanol fuel cell with perforated silicon-plate integrated ionomer membrane  

NASA Astrophysics Data System (ADS)

This article describes the fabrication and characterization of a silicon based micro direct methanol fuel cell using a Nafion ionomer membrane integrated into a perforated silicon plate. The focus of this work is to provide a platform for micro- and nanostructuring of a combined current collector and catalytic electrode. AC impedance spectroscopy is utilized alongside IV characterization to determine the influence of the plate perforation geometries on the cell performance. It is found that higher ratios of perforation increases peak power density, with the highest achieved being 2.5 mW cm-2 at a perforation ratio of 40.3%. The presented fuel cells also show a high volumetric peak power density of 2  mW cm-3 in light of the small system volume of 480  ?L, while being fully self contained and passively feed.

Larsen, J. V.; Dalslet, B. T.; Johansson, A.-C.; Kallesøe, C.; Thomsen, E. V.

2014-07-01

300

Graphene oxide-based dispersive micro-solid phase extraction for separation and preconcentration of nicotine from biological and environmental water samples followed by gas chromatography-flame ionization detection.  

PubMed

Graphene oxide (GO) has showed great potential to use as an adsorbent in sample preparation procedures. In this research, GO was used as an effective adsorbent in a simple GO-based dispersive micro-solid phase extraction (GO-D-µ-SPE) method for isolation and preconcentration of nicotine prior to gas chromatography-flame ionization detection (GC-FID). The prepared GO was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), thermogravimetric analysis/differential thermal analysis (TGA/DTA), and ultraviolet-visible (UV-vis) absorption spectroscopy techniques. Various experimental parameters affecting the extraction recovery, including the amount of GO, extraction time, pH of the sample solution, salt concentration, and desorption conditions were investigated and optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 5-2000 ng mL(-1) with a determination coefficient of 0.9987. The limit of detection (LOD) of the method at a signal to noise ratio of 3 was 1.5 ng mL(-1). The linearity was in the concentration range of 5-2000 ng mL(-1) with a determination coefficient of 0.9987. Intraday and inter-day precisions were obtained equal to 2.7% and 5.2%, respectively. The method was successfully applied to the nicotine analysis in biological and water samples with the recoveries in the range of 88.7-109.7%. PMID:25159381

Mahpishanian, Shokouh; Sereshti, Hassan

2014-12-01

301

Micro-grooved heat transfer combustor wall  

NASA Technical Reports Server (NTRS)

A gas turbine engine hot section combustor liner is provided a non-film cooled portion of a heat transfer wall having a hot surface and a plurality of longitudinally extending micro-grooves disposed in the portion of the wall along the hot surface in a direction parallel to the direction of the hot gas flow. The depth of the micro-grooves is very small and on the order of magnitude of a predetermined laminar sublayer of a turbulent boundary layer. The micro-grooves are sized so as to inhibit heat transfer from the hot gas flow to the hot surface of the wall while reducing NOx emissions of the combustor relative to an otherwise similar combustor having a liner wall portion including film cooling apertures. In one embodiment the micro-grooves are about 0.001 inches deep and have a preferred depth range of from about 0.001 inches to 0.005 inches and which are square, rectangular, or triangular in cross-section and the micro-grooves are spaced about one width apart.

Ward, Steven D. (Inventor)

1994-01-01

302

Investigation of bonding properties of denture bases to silicone-based soft denture liner immersed in isobutyl methacrylate and 2-hydroxyethyl methacrylate  

PubMed Central

PURPOSE The purpose of this study was to investigate the bonding properties of denture bases to silicone-based soft denture liners immersed in isobutyl methacrylate (iBMA) and 2-hydroxyethyl methacrylate (HEMA) for various lengths of time. MATERIALS AND METHODS Polymethyl methacrylate (PMMA) test specimens were fabricated (75 mm in length, 12 mm in diameter at the thickest section, and 7 mm at the thinnest section) and then randomly assigned to five groups (n=15); untreated (Group 1), resilient liner immersed in iBMA for 1 minute (Group 2), resilient liner immersed in iBMA for 3 minutes (Group 3), resilient liner immersed in HEMA for 1 minute (Group 4), and resilient liner immersed in HEMA for 3 minutes (Group 5). The resilient liner specimens were processed between 2 PMMA blocks. Bonding strength of the liners to PMMA was compared by tensile test with a universal testing machine at a crosshead speed of 5 mm/min. Data were evaluated by 1-way ANOVA and post hoc Tukey-Kramer multiple comparisons tests (?=0.05). RESULTS The highest mean value of force was observed in Group 3 specimens. The differences between groups were statistically significant (P<.05), except between Group 1 and Group 4 (P=.063). CONCLUSION Immersion of silicone-based soft denture liners in iBMA for 3 minutes doubled the tensile bond strength between the silicone soft liner and PMMA denture base materials compared to the control group. PMID:24843397

Tugut, Faik; Mutaf, Burcu; Guney, Umit

2014-01-01

303

Fabrication of a Flexible Micro CO Sensor for Micro Reformer Applications  

PubMed Central

Integration of a reformer and a proton exchange membrane fuel cell (PEMFC) is problematic due to the presence in the gas from the reforming process of a slight amount of carbon monoxide. Carbon monoxide poisons the catalyst of the proton exchange membrane fuel cell subsequently degrading the fuel cell performance, and necessitating the sublimation of the reaction gas before supplying to fuel cells. Based on the use of micro-electro-mechanical systems (MEMS) technology to manufacture flexible micro CO sensors, this study elucidates the relation between a micro CO sensor and different SnO2 thin film thicknesses. Experimental results indicate that the sensitivity increases at temperatures ranging from 100–300 °C. Additionally, the best sensitivity is obtained at a specific temperature. For instance, the best sensitivity of SnO2 thin film thickness of 100 nm at 300 °C is 59.3%. Moreover, a flexible micro CO sensor is embedded into a micro reformer to determine the CO concentration in each part of a micro reformer in the future, demonstrating the inner reaction of a micro reformer in depth and immediate detection. PMID:22163494

Lee, Chi-Yuan; Chang, Chi-Chung; Lo, Yi-Man

2010-01-01

304

Fabrication of a flexible micro CO sensor for micro reformer applications.  

PubMed

Integration of a reformer and a proton exchange membrane fuel cell (PEMFC) is problematic due to the presence in the gas from the reforming process of a slight amount of carbon monoxide. Carbon monoxide poisons the catalyst of the proton exchange membrane fuel cell subsequently degrading the fuel cell performance, and necessitating the sublimation of the reaction gas before supplying to fuel cells. Based on the use of micro-electro-mechanical systems (MEMS) technology to manufacture flexible micro CO sensors, this study elucidates the relation between a micro CO sensor and different SnO2 thin film thicknesses. Experimental results indicate that the sensitivity increases at temperatures ranging from 100-300 °C. Additionally, the best sensitivity is obtained at a specific temperature. For instance, the best sensitivity of SnO2 thin film thickness of 100 nm at 300 °C is 59.3%. Moreover, a flexible micro CO sensor is embedded into a micro reformer to determine the CO concentration in each part of a micro reformer in the future, demonstrating the inner reaction of a micro reformer in depth and immediate detection. PMID:22163494

Lee, Chi-Yuan; Chang, Chi-Chung; Lo, Yi-Man

2010-01-01

305

Micro Handling Devices Supported by Electrostatic Forces  

Microsoft Academic Search

The handling of micro parts made of dielectric material can be affected by electrostatic forces. This work presents new handling devices taking advantage of electrostatic forces. These forces are generated by simple configurations of electrodes or by charges located on surfaces of insulators. High resolution force measurements show electrostatic effects such as gas discharges and leak currents. Active neutralization was

J. Hesselbach; J. Wrege; A. Raatz

2007-01-01

306

Micro-fabricated electrolytic micro-bubblers  

Microsoft Academic Search

Rectangular node electrodes were developed with micro-fabrication techniques in order to produce an electrolytic micro-bubbler which, while subjected to a convective flow, can generate bubbles of nearly uniform size with mean diameters of 50?m or less. The devices were fabricated and placed in both a quiescent tap water chamber and a water channel operating at laminar flow rates. The effect

S. Lee; W. Sutomo; C. Liu; E. Loth

2005-01-01

307

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

2011-04-01

308

Increasing Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.  

DOEpatents

High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

Li, Yaun-Min (Langhorne, PA); Bennett, Murray S. (Langhorne, PA); Yang, Liyou (Plainsboro, NJ)

1999-08-24

309

Increased Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.  

DOEpatents

High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

Li, Yaun-Min (Langhorne, PA); Bennett, Murray S. (Langhorne, PA); Yang, Liyou (Plainsboro, NJ)

1997-07-08

310

Fluid inclusion volatile analysis by gas chromatography with photoionization micro-thermal conductivity detectors: Applications to magmatic MoS 2 and other H 2O-CO 2 and H 2O-CH 4 fluids  

NASA Astrophysics Data System (ADS)

Eighteen fluid inclusion volatile peaks have been detected and identified from 1-2 g samples (quartz) by gas chromatography using heated (~105°C) on-line crushing, helium carrier gas, a single porous polymer column (HayeSep R; 10' × 1/8?: 100/120#; Ni alloy tubing), two temperature programme conditions for separate sample aliquots, micro-thermal conductivity (TCD) and photoionization detectors (PID; 11.7 eV lamp), and off-line digital peak processing. In order of retention time these volatile peaks are: N 2, Ar, CO, CH 4, CO 2, C 2H 4, C 2H 6, C 2H 2, COS, C 3H 6, C 3H 8, C 3H 4 (propyne), H 2O (22.7 min at 80°C), SO 2, ± iso- C4H10 ± C4H8 (1-butene) ± CH3SH, C 4H 8 (iso-butylene), (?) C 4H 6 (1,3 butadiene) and ± n- C4H10 ± C4H8 (trans-2-butene) (80 and -70°C temperature programme conditions combined). H 2O is analysed directly. O 2 can be analysed cryogenically between N 2 and Ar, but has not been detected in natural samples to date in this study. H 2S, SO 2, NH 3, HCl, HCN, and H 2 ca nnot be analysed at present. Blanks determined by crushing heat-treated Brazilian quartz (800-900°C/4 h) are zero for 80°C temperature programme conditions, except for a large, unidentified peak at ~64 min, but contain H 2O, CO 2, and some low molecular weight hydrocarbons at -70°C temperature conditions due to cryogenic accumulation from the carrier gas and subsequent elution. TCD detection limits are ~30 ppm molar in inclusions; PID detection limits are ~ 1 ppm molar in inclusions and lower for unsaturated hydrocarbons (e.g., ~0.2 ppm for C 2H 4; ~ 1 ppb for C 2H 2; ~0.3 ppb for C 3H 6). Precisions (1?) are ~ ±1-2% and ~ ± 13% for H 2O in terms of total moles detected; the latter value is equivalent to ±0.6 mol% at the 95 mol% H 2O level. Major fluid inclusion volatile species have been successfully analysed on a ~50 mg fluid inclusion section chip (~7 mm × ~10 mm × ~100 ?m). Initial inclusion volatile analyses of fluids of interpreted magmatic origin from the Cretaceous Boss Mtn. monzogranite stock-related MoS 2 deposit, central British Columbia of ~97 mol% H 2O, ~3% CO 2, ~ 140-150 ppm N 2, and ~16-39 ppm CH 4 (~300-350°C) are reasonable in comparison with high temperature (~400-900°C) volcanic gas analyses from four, active calc-alkaline volcanoes; e.g., the H 2O contents of volcanic gases from the White Island (New Zealand), Mount St. Helens (Washington, USA), Merapi (Bali, Indonesia), and Momotombo (Nicaragua) volcanoes are 88-95%, >90% (often >95%), 88-95% and ~93%, respectively; CO 2 contents are ~3-10%, 1-10%, 3-8%, and ~3.5%. CO 2/N 2 ratios for the Boss Mtn. MoS 2 fluids of ~ 190-220 are in the range for known volcanic gas ratios (e.g., ~ 150- 240; White Island). The ?S content of the Boss Mtn. MoS 2 fluid prior to S loss by sulphide precipitation may have been ~2 mol% since CO 2/?S molar ratios of analysed high-temperature volcanic gases are ~ 1.5. This estimate is supported by ?S contents for White Island, Merapi and Momotombo volcanic gases of ~2%, ~0.5-2.5%, and ~2%. COS has been determined in H 2O-CO 2 fluid inclusions of interpreted magmatic origin from the Boss Mtn. MoS 2 deposit and the Tanco zoned granitic pegmatite, S.E. Manitoba at ~50-100 ppm molar levels, which are consistent with levels in volcanic gases. It appears that low, but significant, concentrations of C 2-C 4 alkanes (~ 1-20 ppm), C 2-C 4 alkenes (~ 1-480 ppb) and alkynes (e.g., C 3H 4) have been detected in magmatically derived fluids (Boss Mtn. MoS 2 deposit; Tanco granitic pegmatite). Significantly higher, low molecular weight hydrocarbon concentrations have been determined in a CH 4-rich (~ 2%), externally derived fluid of possible metamorphic or deep crustal origin trapped as inclusions in metasomatic wall-rock tourmaline adjacent to the Tanco pegmatite (e.g., 300/470 ppm C 2H 6; 50/90 ppm C 3H 8; 3-60 ppm C 2H 4/C 3H 6 n-C 4H 10).

Bray, C. J.; Spooner, E. T. C.

1992-01-01

311

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

312

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

313

High rate behavior and discharge limits in micro-pattern detectors  

Microsoft Academic Search

We present and discuss a set of systematic measurements, carried out with gaseous proportional micro-pattern detectors, in order to assess their maximum gain when irradiated with high-rate soft X-rays and heavily ionizing alpha particles. The inventory of detectors tested includes: micro-strip micromegas, micro-dot, gas electron multiplier, CAT (compteur à trous), trench (or groove), micro-CAT (or WELL) detectors, as well as

A Bressan; M Hoch; P Pagano; Leszek Ropelewski; Fabio Sauli; S F Biagi; A F Buzulutskov; M Gruwé; G De Lentdecker; D Mörmann; A Sharma

1998-01-01

314

High rate behavior and discharge limits in micro-pattern detectors  

Microsoft Academic Search

We present and discuss a set of systematic measurements, carried out with gaseous proportional micro-pattern detectors, in order to assess their maximum gain when irradiated with high-rate soft X-rays and heavily ionizing alpha particles. The inventory of detectors tested includes: micro-strips, micromegas, micro-dot, gas electron multiplier, CAT (compteur à trous), trench (or groove), micro-CAT (or WELL) detectors, as well as

A. Bressan; M. Hoch; P. Pagano; L. Ropelewski; F. Sauli; S. Biagi; A. Buzulutskov; M. Gruwé; G De Lentdecker; D. Moermann; A. Sharma

1999-01-01

315

Integrated Micro Nano Systems Integrated Micro Nano Systems  

E-print Network

#12;Integrated Micro Nano Systems 2 #12;Integrated Micro Nano Systems 3 Val Jones (Ed.) Symposium on Integrated Micro Nano Systems: Convergence of bio and nanotechnologies, Enschede, The Netherlands, June 2006 Micro Nano Systems 4 #12;Integrated Micro Nano Systems 5 Preface In order to explore the convergence

Al Hanbali, Ahmad

316

The Nano-Micro Interface Bridging the Micro  

E-print Network

The Nano-Micro Interface Bridging the Micro and Nano Worlds. Edited by Hans-Jörg Fecht and Matthias- tion among researchers. The book The Nano-Micro Interface: Bridging the Micro and Nano Worlds fills one of these gaps. More specifically, this book, as its subtitle indicates, bridges the micro and nano worlds

Cao, Guozhong

317

MicroSight Optics  

SciTech Connect

MicroSight is an innovative gunsight technology that allows a marksman's eye to focus on both the front gunsight and the intended target. The MicroSight improves both firearm safety and performance by imaging two objects at different focal distances. The MicroSight was developed at Idaho National Laboratory, and has been licensed by Apollo Optical Systems. You can learn more about INL's research programs at http://www.facebook.com/idahonationallaboratory.

None

2010-01-01

318

Micro-organ device  

NASA Technical Reports Server (NTRS)

A method for fabricating a micro-organ device comprises providing a microscale support having one or more microfluidic channels and one or more micro-chambers for housing a micro-organ and printing a micro-organ on the microscale support using a cell suspension in a syringe controlled by a computer-aided tissue engineering system, wherein the cell suspension comprises cells suspended in a solution containing a material that functions as a three-dimensional scaffold. The printing is performed with the computer-aided tissue engineering system according to a particular pattern. The micro-organ device comprises at least one micro-chamber each housing a micro-organ; and at least one microfluidic channel connected to the micro-chamber, wherein the micro-organ comprises cells arranged in a configuration that includes microscale spacing between portions of the cells to facilitate diffusion exchange between the cells and a medium supplied from the at least one microfluidic channel.

Gonda, Steve R. (Inventor); von Gustedt-Gonda, legal representative, Iris (Inventor); Chang, Robert C. (Inventor); Starly, Binil (Inventor); Culbertson, Christopher (Inventor); Holtorf, Heidi L. (Inventor); Sun, Wei (Inventor); Leslie, Julia (Inventor)

2013-01-01

319

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

DOEpatents

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

320

Microsystems Micro and Nano Technologies  

E-print Network

Microsystems Micro and Nano Technologies Automatic control Networks Dependable computing Robotics and multifunctional micro and nano systems · Micro and nano technologies integrating new functional organic and AI Interaction with life Pervasive Intelligence #12;MINAS MICRO AND NANO SYSTEMS RESEARCH AREA MICRO

Ingrand, François

321

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

322

High-speed thin-film transistors on single-crystalline, unstrained- and strained-silicon-based nanomembranes  

NASA Astrophysics Data System (ADS)

This research focuses on developing high-performance single-crystal Si-based nanomembranes and high-frequency thin-film transistors (TFTs) using these nanomembranes on flexible plastic substrates. Unstrained Si or SiGe nanomembranes with thickness of several tens to a couple of hundred nanometers are derived from silicon-on-insulator (SOI) or silicon-germanium-on-insulator (SGOI) and are subsequently transferred and integrated with flexible plastic host substrates via a one-step dry printing technique. Biaxial tensile-strained Si membranes that utilize elastic strain-sharing between Si and additionally grown SiGe thin films are also successfully integrated with plastic host substrates and exhibit predicted strain status and negligible density of dislocations. Biaxial tensile strain enhances electron mobility and lowers Schottky contact resistance. As a result, flexible TFTs built on the strained Si-membranes demonstrate much higher electron effective mobility and higher drive current than the unstrained counterpart. The dependence of drive current and transconductance on uniaxial tensile strain introducing by mechanical bending is also discussed. A novel combined "hot-and-cold" TFT fabrication process is developed specifically for realizing a wide spectrum of micro-electronics that can exhibit RF performance and can be integrated on low-temperature plastic substrate. The "hot" process that consists of ion implant and high-temperature annealing for desired doping type, profile, and concentration is realized on the bulk SOI/SGOI substrates followed by the "cold" process that includes room-temperature silicon-monoxide (SiO) deposition as gate dielectric layer to ensure the process compatibility with low-temperature, low-cost plastics. With these developments flexible Si-membrane n-type RF TFTs for analog applications and complementary TFTs for digital applications are demonstrated for the first time. RF TFTs with 1.5-mum channel length have demonstrated record-high f T and fmax values of 2.04 and 7.8 GHz, respectively. A small-signal equivalent circuit model study on the RF TFTs reveals the physics of how device layout affects fT and f max, which paves the way for further performance optimization and realization of integrated circuit on flexible substrate in the future.

Yuan, Hao-Chih

323

Analysis of Membrane Lipids of Airborne Micro-Organisms  

NASA Technical Reports Server (NTRS)

A method of characterization of airborne micro-organisms in a given location involves (1) large-volume filtration of air onto glass-fiber filters; (2) accelerated extraction of membrane lipids of the collected micro-organisms by use of pressurized hot liquid; and (3) identification and quantitation of the lipids by use of gas chromatography and mass spectrometry. This method is suitable for use in both outdoor and indoor environments; for example, it can be used to measure airborne microbial contamination in buildings ("sick-building syndrome"). The classical approach to analysis of airborne micro-organisms is based on the growth of cultureable micro-organisms and does not provide an account of viable but noncultureable micro-organisms, which typically amount to more than 90 percent of the micro-organisms present. In contrast, the present method provides an account of all micro-organisms, including cultureable, noncultureable, aerobic, and anaerobic ones. The analysis of lipids according to this method makes it possible to estimate the number of viable airborne micro-organisms present in the sampled air and to obtain a quantitative profile of the general types of micro-organisms present along with some information about their physiological statuses.

MacNaughton, Sarah

2006-01-01

324

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

325

Micro Contacts and Micro Manipulation with MEMS Actuator Arrays  

E-print Network

Micro Contacts and Micro Manipulation with MEMS Actuator Arrays Karl­Friedrich B¨ohringer Bruce sensors, actuators, computation, and communication in a single micro device [7]. It is widely expected technology for MEMS (micro electro mechanical systems) increase the availability and diversity

Donald, Bruce Randall

326

Collective Motion of Micro-organisms from Field Theoretical Viewpoint  

E-print Network

We analyze the collective motion of micro-organisms in the fluid and consider the problem of the red tide. The red tide is produced by the condensation of the micro-organisms, which might be a similar phenomenon to the condensation of the strings. We propose a model of the generation of the red tide. By considering the interaction between the micro- organisms mediated by the velocity fields in the fluid, we derive the Van der Waals type equation of state, where the generation of the red tide can be regarded as a phase transition from the gas of micro-organisms to the liquid. (The number density of micro-organisms which generates the red tide is order estimated.)

Shin'ichi Nojiri; Masako Kawamura; Akio Sugamoto

1995-12-13

327

Development of air micro plasma source using a magnetic loop with operation at modulated ultra high frequencies  

Microsoft Academic Search

Summary form only given. Micro plasma sources are a rapidly growing area of study in plasma sciences, attracting widespread attention due to the large number of possible applications such as biomedical sterilizers, plasma displays, and chemical analyzers. The micro plasma operating power, gas, and pressure are three main issues to address in order to make portable micro plasma devices.We report

M. Taghioskoui; J. Perlow; M. Zaghloul

2010-01-01

328

Polypyrrole micro actuators  

Microsoft Academic Search

The doping and undoping of conjugated polymers is accompanied by a volume change. This volume change can be used to make micro-actuators. We have built polypyrrole (PPy) gold bilayer structures. The volume change of PPy induces a bending of the bilayer. We have made micro-actuators based on this principle, which have been examined with video-microscopy. Some applications for these microactuators

Edwin W. H. Jager; Elisabeth Smela; Olle Inganäs; Ingemar Lundström

1999-01-01

329

The Mars Development of a Micro-Isolation Valve  

NASA Technical Reports Server (NTRS)

A feasibility investigation for a newly proposed microfabricated, normally-closed isolation valve was initiated. The micro-isolation valve is silicon based and relies on the principle of melting a silicon plug, opening an otherwise sealed flow passage. This valve may thus serve a similar role as a conventional pyrovalve and is intended for use in micropropulsion systems onboard future microspacecraft, having wet masses of no more than 10-20 kg, as well as in larger scale propulsion systems having only low flow rate requirements, such as ion propulsion or Hall thruster systems. Two key feasibility issues - melting of the plug and pressure handling capability - were addressed. Thermal finite element modeling showed that valves with plugs having widths between 10 and 50 gm have power requirements of only 10 . 30 Watts to open over a duration of 0.5 ms or less. Valve chips featuring 5 0 micron plugs were burst pressure tested and reached maximum pressure values o f 2900 psig (19.7 Mpa).

Mueller, Juergen; Vargo, Steven; Forgrave, John; Bame, David; Chakraborty, Indrani; Tang, William

1999-01-01

330

Microcrystalline silicon oxides for silicon-based solar cells: impact of the O/Si ratio on the electronic structure  

NASA Astrophysics Data System (ADS)

Hydrogenated microcrystalline silicon oxide (?c-SiOx:H) layers are one alternative approach to ensure sufficient interlayer charge transport while maintaining high transparency and good passivation in Si-based solar cells. We have used a combination of complementary x-ray and electron spectroscopies to study the chemical and electronic structure of the (?c-SiOx:H) material system. With these techniques, we monitor the transition from a purely Si-based crystalline bonding network to a silicon oxide dominated environment, coinciding with a significant decrease of the material's conductivity. Most Si-based solar cell structures contain emitter/contact/passivation layers. Ideally, these layers fulfill their desired task (i.e., induce a sufficiently high internal electric field, ensure a good electric contact, and passivate the interfaces of the absorber) without absorbing light. Usually this leads to a trade-off in which a higher transparency can only be realized at the expense of the layer's ability to properly fulfill its task. One alternative approach is to use hydrogenated microcrystalline silicon oxide (?c-SiOx:H), a mixture of microcrystalline silicon and amorphous silicon (sub)oxide. The crystalline Si regions allow charge transport, while the oxide matrix maintains a high transparency. To date, it is still unclear how in detail the oxygen content influences the electronic structure of the ?c-SiOx:H mixed phase material. To address this question, we have studied the chemical and electronic structure of the ?c-SiOx:H (0 <= x = O/Si <=1) system with a combination of complementary x-ray and electron spectroscopies. The different surface sensitivities of the employed techniques help to reduce the impact of surface oxides on the spectral interpretation. For all samples, we find the valence band maximum to be located at a similar energy with respect to the Fermi energy. However, for x > 0.5, we observe a pronounced decrease of Si 3s - Si 3p hybridization in favor of Si 3p - O 2p hybridization in the upper valence band. This coincides with a significant increase of the material's resistivity, possibly indicating the breakdown of the conducting crystalline Si network. Silicon oxide layers with a thickness of several hundred nanometres were deposited in a PECVD (plasma-enhanced chemical vapor deposition) multi chamber system using an excitation frequency of 13.56 MHz with a plasma power density of 0.3 W/cm2. Glass (Corning type Eagle) and mono-crystalline silicon wafer substrates were coated in the same run at a substrate temperature of 185°C. The deposition pressure was 4 mbar and the substrate-electrode distance 20 mm. Mixtures of silane (SiH4), 1% TMB (B(CH3)3) diluted in helium, hydrogen (H2), and carbon dioxide (CO2) gases were used at flow rates of 1.25 - 0.18/0.32/500/0 - 1.07) sccm (standard cubic centimeters per minute) for the deposition of ?c-SiOx:H(B) layers. By changing the CO2/SiH4 gas flow rate ratio from 0 to 6, ?c-SiOx:H(B) layers with a composition of 0 <=? x = O/Si ?<= 1 were prepared using a constant sum of SiH4 and CO2. The TMB flow and the H2 flow were kept constant within the series. For more details see Ref. [1]. The oxygen content in the films was determined using Rutherford Backscattering Spectroscopy (RBS). With RBS, the area-related atomic density of oxygen and silicon can be determined (+/- 2% [2]), and thus x can be calculated. This quantity considers only the number of silicon / oxygen atoms and not the number of atoms of other elements, such as hydrogen, which is also incorporated to a considerable extent: up to 20% in ?c-SiOx:H (measured using the hydrogen effusion method). To avoid charging effects, the measurements were performed on films deposited on a substrate of mono-crystalline silicon wafers. The electrical conductivity was measured in the planar direction of the film in a vacuum cryostat, using voltages from - 100 V to + 100 V. For that two co-planar Ag contacts were evaporated on the film with a gap of 0.5 mm - 5 mm. In the present study, the

Bär, M.; Starr, D. E.; Lambertz, A.; Holländer, B.; Alsmeier, J.-H.; Weinhardt, L.; Blum, M.; Gorgoi, M.; Yang, W.; Wilks, R. G.; Heske, C.

2014-10-01

331

Continuous flowing micro-reactor for aqueous reaction at temperature higher than 100?°C.  

PubMed

Some aqueous reactions in biological or chemical fields are accomplished at a high temperature. When the reaction temperature is higher than 100?°C, an autoclave reactor is usually required to elevate the boiling point of the water by creating a high-pressure environment in a closed system. This work presented an alternative continuous flowing microfluidic solution for aqueous reaction with a reaction temperature higher than 100?°C. The pressure regulating function was successfully fulfilled by a small microchannel based on a delicate hydrodynamic design. Combined with micro heater and temperature sensor that integrated in a single chip by utilizing silicon-based microfabrication techniques, this pressure regulating microchannel generated a high-pressure/high-temperature environment in the upstream reaction zone when the reagents continuously flow through the chip. As a preliminary demonstration, thermal digestion of aqueous total phosphorus sample was achieved in this continuous flowing micro-reactor at a working pressure of 990?kPa (under the working flow rate of 20 nl/s) along with a reaction temperature of 145?°C. This continuous flowing microfluidic solution for high-temperature reaction may find applications in various micro total analysis systems. PMID:24404024

Xie, Fei; Wang, Baojun; Wang, Wei; Dong, Tian; Tong, Jianhua; Xia, Shanhong; Wu, Wengang; Li, Zhihong

2013-01-01

332

Continuous flowing micro-reactor for aqueous reaction at temperature higher than 100?°C  

PubMed Central

Some aqueous reactions in biological or chemical fields are accomplished at a high temperature. When the reaction temperature is higher than 100?°C, an autoclave reactor is usually required to elevate the boiling point of the water by creating a high-pressure environment in a closed system. This work presented an alternative continuous flowing microfluidic solution for aqueous reaction with a reaction temperature higher than 100?°C. The pressure regulating function was successfully fulfilled by a small microchannel based on a delicate hydrodynamic design. Combined with micro heater and temperature sensor that integrated in a single chip by utilizing silicon-based microfabrication techniques, this pressure regulating microchannel generated a high-pressure/high-temperature environment in the upstream reaction zone when the reagents continuously flow through the chip. As a preliminary demonstration, thermal digestion of aqueous total phosphorus sample was achieved in this continuous flowing micro-reactor at a working pressure of 990?kPa (under the working flow rate of 20 nl/s) along with a reaction temperature of 145?°C. This continuous flowing microfluidic solution for high-temperature reaction may find applications in various micro total analysis systems. PMID:24404024

Xie, Fei; Wang, Baojun; Wang, Wei; Dong, Tian; Tong, Jianhua; Xia, Shanhong; Wu, Wengang; Li, Zhihong

2013-01-01

333

Research on defects and transport in amorphous-silicon-based semiconductors. Final subcontract report, 20 February 1991--19 April 1994  

SciTech Connect

This report describes work on three individual tasks as follows. (1) Electron and hole drift measurements in a-Si{sub 1-x}Ge{sub x}:H and a-Si{sub 1-x}C{sub x}:H p-i-n solar cells. Multijunction solar cells incorporating modified band gap a-Si:H in a triple-junction structure are generally viewed as the most promising avenue for achieving an amorphous silicon-based solar call with 15% stabilized conversion efficiency. The specific objective of this task was to document the mobilities and deep-trapping mobility-lifetime products for electrons and holes in a-Si{sub 1-x}Ge{sub x}:H and a-Si{sub 1-x}C{sub x}:H alloys materials. (2) Electroabsorption measurements and built-in potential (V{sub bi}) in solar cells. V{sub bi} in a p-i-n solar call may be limiting the open-circuit voltage (V{sub oc}) in wide-band-gap cells (E{sub g} > 1.8 eV) currently under investigation as the top cell for 15% triple junction devices. The research addressed four issues that need to be resolved before the method can yield an error less than 0.1 V for V{sub bi}. The details are presented in this report. (3) Defect relaxation and Shockley-Read kinetics in a-Si:H. Quantitative modeling of solar cells is usually based on Shockley-Read kinetics.`` An important assumption of this approach is that the rate of emission of a photocarrier trapped on a defect is independent of quasi-Fermi level location.

Schiff, E.A.; Antoniadis, H.; Gu, Q.; Lee, J.K.; Wang, Q.; Zafar, S. [Syracuse Univ., NY (United States)

1994-09-01

334

A silicon-based photocathode for water reduction with an epitaxial SrTiO3 protection layer and a nanostructured catalyst.  

PubMed

The rapidly increasing global demand for energy combined with the environmental impact of fossil fuels has spurred the search for alternative sources of clean energy. One promising approach is to convert solar energy into hydrogen fuel using photoelectrochemical cells. However, the semiconducting photoelectrodes used in these cells typically have low efficiencies and/or stabilities. Here we show that a silicon-based photocathode with a capping epitaxial oxide layer can provide efficient and stable hydrogen production from water. In particular, a thin epitaxial layer of strontium titanate (SrTiO3) was grown directly on Si(001) by molecular beam epitaxy. Photogenerated electrons can be transported easily through this layer because of the conduction-band alignment and lattice match between single-crystalline SrTiO3 and silicon. The approach was used to create a metal-insulator-semiconductor photocathode that, under a broad-spectrum illumination at 100?mW cm(-2), exhibits a maximum photocurrent density of 35?mA?cm(-2) and an open circuit potential of 450?mV; there was no observable decrease in performance after 35 hours of operation in 0.5?M H2SO4. The performance of the photocathode was also found to be highly dependent on the size and spacing of the structured metal catalyst. Therefore, mesh-like Ti/Pt nanostructured catalysts were created using a nanosphere lithography lift-off process and an applied-bias photon-to-current efficiency of 4.9% was achieved. PMID:25437745

Ji, Li; McDaniel, Martin D; Wang, Shijun; Posadas, Agham B; Li, Xiaohan; Huang, Haiyu; Lee, Jack C; Demkov, Alexander A; Bard, Allen J; Ekerdt, John G; Yu, Edward T

2015-01-01

335

A silicon-based photocathode for water reduction with an epitaxial SrTiO3 protection layer and a nanostructured catalyst  

NASA Astrophysics Data System (ADS)

The rapidly increasing global demand for energy combined with the environmental impact of fossil fuels has spurred the search for alternative sources of clean energy. One promising approach is to convert solar energy into hydrogen fuel using photoelectrochemical cells. However, the semiconducting photoelectrodes used in these cells typically have low efficiencies and/or stabilities. Here we show that a silicon-based photocathode with a capping epitaxial oxide layer can provide efficient and stable hydrogen production from water. In particular, a thin epitaxial layer of strontium titanate (SrTiO3) was grown directly on Si(001) by molecular beam epitaxy. Photogenerated electrons can be transported easily through this layer because of the conduction-band alignment and lattice match between single-crystalline SrTiO3 and silicon. The approach was used to create a metal–insulator–semiconductor photocathode that, under a broad-spectrum illumination at 100?mW cm?2, exhibits a maximum photocurrent density of 35?mA?cm?2 and an open circuit potential of 450?mV there was no observable decrease in performance after 35 hours of operation in 0.5?M H2SO4. The performance of the photocathode was also found to be highly dependent on the size and spacing of the structured metal catalyst. Therefore, mesh-like Ti/Pt nanostructured catalysts were created using a nanosphere lithography lift-off process and an applied-bias photon-to-current efficiency of 4.9% was achieved.

Ji, Li; McDaniel, Martin D.; Wang, Shijun; Posadas, Agham B.; Li, Xiaohan; Huang, Haiyu; Lee, Jack C.; Demkov, Alexander A.; Bard, Allen J.; Ekerdt, John G.; Yu, Edward T.

2015-01-01

336

Method of fabricating a micro machine  

DOEpatents

A micro machine may be in or less than the micrometer domain. The micro machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft is operable to be driven by the micro actuator. A tool is coupled to the micro shaft and is operable to perform work in response to at least motion of the micro shaft.

Stalford, Harold L

2014-11-11

337

Micro-Organ Devices  

NASA Technical Reports Server (NTRS)

Micro-organ devices (MODs) are being developed to satisfy an emerging need for small, lightweight, reproducible, biological-experimentati on apparatuses that are amenable to automated operation and that imp ose minimal demands for resources (principally, power and fluids). I n simplest terms, a MOD is a microfluidic device containing a variety of microstructures and assemblies of cells, all designed to mimic a complex in vivo microenvironment by replicating one or more in vivo micro-organ structures, the architectures and composition of the extr acellular matrices in the organs of interest, and the in vivo fluid flows. In addition to microscopic flow channels, a MOD contains one or more micro-organ wells containing cells residing in microscopic e xtracellular matrices and/or scaffolds, the shapes and compositions o f which enable replication of the corresponding in vivo cell assembl ies and flows.

Gonda, Steven R.; Leslie, Julia; Chang, Robert C.; Starly, Binil; Sun, Wei; Culbertson, Christopher; Holtorf, Heidi

2009-01-01

338

Silicon micro-mold  

DOEpatents

The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

Morales, Alfredo M. (Livermore, CA)

2006-10-24

339

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

340

Method of Manufacturing Micro-Disperse Particles of Sodium Borohydride  

DOEpatents

A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

Kravitz, Stanley H. (Placitas, NM); Hecht, Andrew M. (Sandia Park, NM); Sylwester. Alan P. (Albuquerque, NM); Bell, Nelson S. (Albuquerque, NM)

2008-09-23

341

==================== !"#$%&'()*+,-+./,0)12 Development of Micro Ejector for Butane Catalytic Combustor  

E-print Network

with the excessive heat of the exhaust gas. The advantage of using ejector is that air-entrainment is achieved Combustor Inlet Outlet Liquid Fuel Container Micro Nozzle Ejector Valve Exhaust Heat Reformer, Heat Engine Combustor, Convergent-divergent Nozzle, Ejector, Back pressure. Fig. 1 Configuration of micro heat

Kasagi, Nobuhide

342

Distributed electrostatic micro actuator  

Microsoft Academic Search

A micro actuator that is called a distributed electrostatic actuator, because it consists of many driving units, and that is driven by electrostatic force is described. Each driving unit has wavelike electrodes, which are insulated and pull each other by the electrostatic force. The deformation of this actuator depends on the electrostatic force, the elasticity of the structure, and the

Motoharu Yamaguchi; Shuji Kawamura; Kazuyuki Minami; Masayoshi Esashi

1993-01-01

343

Micro Actuators Electrostatic actuator  

E-print Network

film #12;W for PVDF film #12;Electrical to Mechanical l W t #12;#12;Bimorph Piezoelectric Actuators #12Micro Actuators ·Electrostatic actuator - comb drive actuator ·Magnetic actuator ·Thermal actuator ·Piezoelectric actuator ·Shape memory alloy actuator ·Pneumatic actuator Ref: AIP Handbook of Modern Sensors http

Leu, Tzong-Shyng "Jeremy"

344

Micro Vortex Generators  

NASA Technical Reports Server (NTRS)

An in house video made to show how NASA Langley scientists have found ways to improve airplane performance. Micro Vortex Generators placed on airplane wings can reduce drag, increase lift, and reduce fuel consumption. Nice animation and real footage of planes with this technology.

2000-01-01

345

Breakthrough: micro-electronic photovoltaics  

ScienceCinema

Sandia developed tiny glitter-sized photovoltaic (PV) cells that could revolutionize solar energy collection. The crystalline silicon micro-PV cells will be cheaper and have greater efficiencies than current PV collectors. Micro-PV cells require relatively little material to form well-controlled, highly efficient devices. Cell fabrication uses common microelectric and micro-electromechanical systems (MEMS) techniques.

Okandan, Murat; Gupta, Vipin

2014-06-23

346

Breakthrough: micro-electronic photovoltaics  

SciTech Connect

Sandia developed tiny glitter-sized photovoltaic (PV) cells that could revolutionize solar energy collection. The crystalline silicon micro-PV cells will be cheaper and have greater efficiencies than current PV collectors. Micro-PV cells require relatively little material to form well-controlled, highly efficient devices. Cell fabrication uses common microelectric and micro-electromechanical systems (MEMS) techniques.

Okandan, Murat; Gupta, Vipin

2012-04-23

347

Micro Assembly By High Rate CVD Using CW UV Laser  

Microsoft Academic Search

We have developed micro assembiy technique which uses polymer as adhesive, deposited by laser assisted CVD. The laser deposition system adopted following techniques to increase deposition rate. Continuous wave (CvV) ultraviolet (UV) laser was used. The substrate was cooled to condense the source gas (vinyl acetate) on the surface. The maximum deposition rate by the laser deposition system was about

Masahisa Sugihara; K. Minarni; Masayoshi Esashi

1995-01-01

348

Pneumatic Micro Dispenser Chip for Portable Micro Analysis Devices  

NASA Astrophysics Data System (ADS)

The prototype of the pneumatic micro dispenser chip for portable micro analysis devices was developed successfully. This micro dispenser succeeded to divide liquid into 1µL without any dead volume by decompressing and the compressing air in only one micro pump. The dispensing operation is achieved by the original micro liquid detecting method and four hat-shaped check valves. The detecting method utilized the refraction of the infrared rays LED. Not only passage of the fluid into the channel but also its existence can be detected as TTL level signal. The hat-shaped silicone rubber valve which functions itself as a unidirectional passive valve was proposed. The check valve with low opening pressure (3kPa) and high inverse pressure (over 300kPa) was developed successfully. This micro dispenser chip is useful for portable micro analysis devices.

Hasegawa, Tadahiro; Tsuji, Toshiyuki; Ikuta, Koji

349

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

350

Methods and systems for micro transmissions  

DOEpatents

Methods and systems for micro transmissions for a micro machine may comprise an input shaft assembly coupled to a micro actuator, an output shaft assembly coupled to a micro shaft, and one or more power conversion elements operable to convert a first type of movement from the micro actuator into a second, disparate type of movement for the micro shaft.

Stalford, Harold L

2014-12-23

351

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

352

MicroMatters  

NSDL National Science Digital Library

The BioEd Online Project at Baylor University's College of Medicine continues to release new educational resources for persons in the fields of health science, medicine, and biology. Their MicroMatters project creates "teaching materials and online resources in microbiology and infectious diseases," and is a welcome addition to BioEd's existing materials. MicroMatters is a short magazine designed to teach students about communicable diseases, how microbes are spread, various epidemics throughout history, and the immune system and vaccines. Educators may want to use this magazine in conjunction with other classroom activities, or they could also recommend it to other educators who are looking to address similar topics in their own classrooms.

2008-02-11

353

Micro pulse laser radar  

NASA Astrophysics Data System (ADS)

An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

Spinhirne, James D.

1993-08-01

354

Micro pulse laser radar  

NASA Astrophysics Data System (ADS)

An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

Spinhirne, James

1992-08-01

355

Micro pulse laser radar  

NASA Technical Reports Server (NTRS)

An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

Spinhirne, James D. (inventor)

1993-01-01

356

Micro coring apparatus  

NASA Technical Reports Server (NTRS)

A micro-coring apparatus for lunar exploration applications, that is compatible with the other components of the Walking Mobile Platform, was designed. The primary purpose of core sampling is to gain an understanding of the geological composition and properties of the prescribed environment. This procedure has been used extensively for Earth studies and in limited applications during lunar explorations. The corer is described and analyzed for effectiveness.

Collins, David; Brooks, Marshall; Chen, Paul; Dwelle, Paul; Fischer, Ben

1989-01-01

357

MicroWorlds  

NSDL National Science Digital Library

MicroWorlds is a web site containing a set of educational resources highlighting research in materials sciences at Berkeley Lab's Advanced Light Source (ALS). The ALS is a national user facility that generates intense light for scientific and technological research. The site contains several teacher resources including "Exploring the Material World"; three Classroom Teaching Modules, focusing on what makes a material hard, brittle, or a good electrical conductor.

2008-08-06

358

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

359

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

360

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

361

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

362

Micro-mechanics of micro-composites  

NASA Technical Reports Server (NTRS)

The Structural Dynamics branch at NASA LaRC is working on developing an active passive mount system for vibration control. Toward this end a system utilizing piezoelectric actuators is currently being utilized. There are limitations to the current system related to space applications under which it is desired to eliminate deformations in the actuators associated with thermal effects. In addition, a material that is readily formable into complex shapes and whose mechanical properties can be optimized with regards to vibration control would be highly desirable. Microcomposite material are currently under study to service these needs. Microcomposite materials are essentially materials in which particles on the scale of microns are bound together with a polyimide (LaRC Si) that has been developed at LaRC. In particular a micro-composite consisting of LaRC Si binder and piezoelectric ceramic particles shows promise in satisfying the needs of the active passive mount project. The LaRC/ Si microcomposite has a unique combination of piezoelectric properties combined with a near zero coefficient of thermal expansion and easy machinability. The goal of this ASEE project is to develop techniques to analytically determine important material properties necessary to characterize the dynamic properties of actuators and mounts made from the LaRC Si / ceramic microcomposite. In particular, a generalized method of cells micromechanics originally developed at NASA Lewis is employed to analyze the microstructural geometry of the microcomposites and predict the overall mechanical properties of the material. A testing program has been established to evaluate and refine the GMC approach to these materials. In addition, a theory of mixtures analysis is being developed that utilizes the GMC micromechanics information to analyze complex behavior of the microcomposite material which has a near zero CTE.

Donovan, Richard P.

1995-01-01

363

The development of a gas chromatographic-mass spectrometric analytical procedure for the determination of lipids, proteins and resins in the same paint micro-sample avoiding interferences from inorganic media.  

PubMed

This paper presents a GC-MS analytical procedure for determining proteinaceous materials, glycerolipids, natural waxes and terpenoid resins in the same paint micro-sample. The procedure is also reliable when high amounts of interfering inorganic pigments, dryers and charges are present. The characterisation of proteinaceous binders in a paint sample can be subject to analytical interferences by inorganic materials. Such materials may form complexes with functional groups of proteins, thus preventing their efficient derivatisation, which is necessary prior to GC analysis. For this reason an analytical procedure has been developed based on two extractions and a clean-up step, in order to obtain two fractions: a lipid-resinous fraction and a proteinaceous fraction. The lipid-resinous fraction is subjected to salification/saponification assisted by microwaves, followed by acidification, extraction, derivatisation and GC-MS analysis. The proteinaceous fraction is analysed by GC-MS after hydrolysis and derivatisation of the freed amino acids. The desalting step is applied before the hydrolysis, and is based on the use of the monolithic sorbent tip technology with a C4 stationary phase. Reference paint replicas of egg, casein and animal glue were prepared with and without several metals containing pigments, and used to develop and validate the analytical procedure. The procedure proved to be efficient in desalting the proteinaceous materials both from cations and anions. Although non quantitative, it is reliable in the analysis of samples whose content of extractable proteins is <1 microg, thus showing it to be suitable for the characterisation of paint samples. An example of how the analytical procedure was used to characterise a sample from a 15th century panel painting is also discussed. PMID:19586633

Bonaduce, Ilaria; Cito, Marcello; Colombini, Maria Perla

2009-08-01

364

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

365

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

366

Micro-/nanofluidics based cell electroporation  

PubMed Central

Non-viral gene delivery has been extensively explored as the replacement for viral systems. Among various non-viral approaches, electroporation has gained increasing attention because of its easy operation and no restrictions on probe or cell type. Several effective systems are now available on the market with reasonably good gene delivery performance. To facilitate broader biological and medical applications, micro-/nanofluidics based technologies were introduced in cell electroporation during the past two decades and their advances are summarized in this perspective. Compared to the commercially available bulk electroporation systems, they offer several advantages, namely, (1) sufficiently high pulse strength generated by a very low potential difference, (2) conveniently concentrating, trapping, and regulating the position and concentration of cells and probes, (3) real-time monitoring the intracellular trafficking at single cell level, and (4) flexibility on cells to be transfected (from single cell to large scale cell population). Some of the micro-devices focus on cell lysis or fusion as well as the analysis of cellular properties or intracellular contents, while others are designed for gene transfection. The uptake of small molecules (e.g., dyes), DNA plasmids, interfering RNAs, and nanoparticles has been broadly examined on different types of mammalian cells, yeast, and bacteria. A great deal of progress has been made with a variety of new micro-/nanofluidic designs to address challenges such as electrochemical reactions including water electrolysis, gas bubble formation, waste of expensive reagents, poor cell viability, low transfection efficacy, higher throughput, and control of transfection dosage and uniformity. Future research needs required to advance micro-/nanofluidics based cell electroporation for broad life science and medical applications are discussed. PMID:23405056

Wang, Shengnian; Lee, L. James

2013-01-01

367

Micro CVD diamond heat sink  

NASA Astrophysics Data System (ADS)

Chemical vapor deposition (CVD) diamond film has broad application prospect as heat sink in microelectronic field for its excellent thermal conductivity. The micro CVD diamond heat sinks with the size of 50?m×100?m×2000?m were prepared using mould copy technique. The micro silicon moulds for deposition of micro CVD diamond heat sinks were fabricated using inductivity coupling plasma (ICP) etching process. Micro CVD diamond heat sinks were synthesized under 2% methane and 98% hydrogen by hot filament CVD (HFCVD) method. The micro CVD diamond heat sinks were investigated by SEM, Raman and photo thermal deflection. The results show that favorable micro CVD heat sinks having a thermal conductivity of 960W·m-1·K-1 can be prepared by mould copy technique.

Lu, Wenzhuang; Ai, Guoping; Li, Pin; Sun, Yuli; Zhang, Dan; Zuo, Dunwen

2013-08-01

368

Stringy and Membranic Theory of Swimming of Micro-organisms  

E-print Network

When the swimming of micro-organisms is viewed from the string and membrane theories coupled to the velocity field of the fluid, a number of interesting results are derived; 1) importance of the area (or volume) preserving algebra, 2) usefulness of the $N$-point Reggeon (membranic) amplitudes, and of the gas to liquid transition in case of the red tide issues, 3) close relation between the red tide issue and the generation of Einstein gravity, and 4) possible understanding of the three different swimming ways of micro-organisms from the singularity structure of the shape space.

Masako Kawamura; Shin'ichi Nojiri; Akio Sugamoto

1996-03-21

369

Micro-fluidic interconnect  

DOEpatents

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

370

Carbon-based micro-ball and micro-crystal deposition using filamentary pulsed atmospheric pressure plasma  

NASA Astrophysics Data System (ADS)

Thin plasma filaments are produced by the propagation of ionization waves from a spiked driven electrode in a quartz tube in an argon/methane gas mixture (2400 sccm/2 sccm) at atmospheric pressure. The position of the touch point of filaments on the substrate surface is controlled in our experiment by applying various suitable substrate configurations and geometries of the grounded electrode. The gas conditions at the touch point are varied from argon to ambient air. Based on microphotography and discharge current waveforms, the duration of the filament touching the substrate is estimated to be about one microsecond. Carbon-based materials are deposited during this time at the touch points on the substrate surface. Micro-balls are produced if the filament touch points are saved from ambient air by the argon flow. Under an air admixture, micro-crystals are formed. The dimension of both materials is approximately one micrometre (0.5-2 µm) and corresponds to about 1010-1012 carbon atoms. Neither the diffusion of neutral species nor drift of ions can be reason for the formation of such a big micro-material during this short period of filament-substrate interaction. It is possible that charged carbon-based materials are formed in the plasma channel and transported to the surface of the substrate. The mechanism of this transport and characterization of micro-materials, which are formed under different gas conditions in our experiment, will be studied in the future.

Pothiraja, Ramasamy; Bibinov, Nikita; Awakowicz, Peter

2014-08-01

371

Controlled Bacterial Micro-actuation  

Microsoft Academic Search

The integration and exploitation of biological components onto micronanorobots and modern engineered microsystems such as Micro-Electro-Mechanical Systems (MEMS), lab-on-a-chip, or Micro-Total-Analysis Systems (muTAS) offer new possibilities. In particular, the flagellar motor found in many bacteria is a compact and extremely effective biological micro-actuator that is presently impossible to match with modern engineering techniques while requiring no electrical power to operate,

Sylvain Martel

2006-01-01

372

Visualization of cavitating micro jets  

NASA Astrophysics Data System (ADS)

The paper deals with one experimental set up integrated for research of the cavitating micro flows, which is incipient behind the micro channel or micro discharge nozzle outlet port. Experimental system is integrated from three major systems: hydraulic circuit with installed discharge nozzle (or micro channel), subsystem for data acquisition and data processing (DAQ system) and vision system compound of high speed video camera and pulse light source with highfrequency repetition. First few results of experiments (parameters such as inlet pressure, downstream pressure were changed) is also discussed.;

Olšiak, Róbert; Knížat, Branislav; Mlkvik, Marek

2012-04-01

373

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

374

Hybrid gas bearings with controlled supply pressure to eliminate rotor vibrations while crossing system critical speeds  

E-print Network

Micro-turbomachinery (MTM) implements gas bearings in compact units of enhanced mechanical reliability. Gas bearings, however, have little damping and are prone to wear during frequent rotor start-up and shut down conditions. Externally pressurized...

Ryu, Keun

2009-05-15

375

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

376

Micro rotary machine and methods for using same  

DOEpatents

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

377

Improved fatty acid detection in micro-algae and aquatic meiofauna species using a direct thermal desorption interface combined with comprehensive gas chromatography-time-of-flight mass spectrometry.  

PubMed

Comprehensive two-dimensional gas chromatography (GC x GC) with time-of-flight mass spectrometry detection is used to profile the fatty acid composition of whole/intact aquatic microorganisms such as the common fresh water green algae Scenedesmus acutus and the filamentous cyanobacterium Limnothrix sp. strain MRI without any sample preparation steps. It is shown that the technique can be useful in the identification of lipid markers in food-web as well as environmental studies. For instance, new mono- and diunsaturated fatty acids were found in the C(16) and C(18) regions of the green algae S. acutus and the filamentous cyanobacterium Limnothrix sp. strain MRI samples. These fatty acids have not, to our knowledge, been detected in the conventional one-dimensional (1D) GC analysis of these species due to either co-elution and/or their presence in low amounts in the sample matrix. In GC x GC, all congeners of the fatty acids in these microorganisms could be detected and identified due to the increased analyte detectability and ordered structures in the two-dimensional separation space. The combination of direct thermal desorption (DTD)-GC x GC-time-of-flight mass spectrometry (ToF-MS) promises to be an excellent tool for a more accurate profiling of biological samples and can therefore be very useful in lipid biomarker research as well as food-web and ecological studies. PMID:18295771

Akoto, Lawrence; Stellaard, Frans; Irth, Hubertus; Vreuls, René J J; Pel, Roel

2008-04-01

378

Multivariate analysis of mainstream tobacco smoke particulate phase by headspace solid-phase micro extraction coupled with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.  

PubMed

A method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (TOFMS) was developed and applied to evaluate profiles of volatile compounds present in mainstream tobacco smoke particulate matter trapped on glass fiber filters. Six SPME fibers were tested for the extraction capacities toward selected compounds, showing the best results for the polyacrylate fiber. The optimization of the extraction conditions was carried out using multivariate response surface methodology. Two cigarette types differing in a filter design were analyzed using optimized conditions. A template was built in order to generate comprehensive chemical information, which conceded obtaining consistent information across 24 chromatograms. Principal component analysis (PCA) allowed a clear differentiation of the studied cigarette types. Fisher ratio analysis allowed identification of compounds responsible for the chemical differences between the cigarette samples. Of the selected 143 most important ones, 134 analytes were reduced by the active carbon filter, while for nine, classical cellulose acetate filter was more efficient. PMID:25454146

Brokl, Micha?; Bishop, Louise; Wright, Christopher G; Liu, Chuan; McAdam, Kevin; Focant, Jean-François

2014-11-28

379

A Micro-Ultrastable Oscillator (micro-US0) for Micro/Nano Sciencecraft  

NASA Technical Reports Server (NTRS)

Syntonics LLC developed a prototype micro-Ultra Stable Oscillator (micro-USO) under a Space Base Technology Grant (NAGS-10395). Syntonics conducted the micro-USO Program in two phases. In Phase I, we developed a set of verified analytical models (including thermal, electrical, and control models) for a baseline USO, conducted a series of six technology studies, and built three approx.9OOg prototype units. These prototypes provided a tool for evaluating competing design topologies. In Phase II we prepared the conceptual design of a approx.100-15Og micro-USO.

2003-01-01

380

Focused Ion Beam micro machining and micro assembly Hongyi Yang, Svetan Rachev  

E-print Network

Focused Ion Beam micro machining and micro assembly Hongyi Yang, Svetan Rachev Precision components at the micro-scale is critical to the development of micro systems. This paper presents the technique to manipulate micro/nano parts at the micro/nano-scale using an integrated Focused Ion Beam (FIB

Paris-Sud XI, Université de

381

Micro-Particles as Electrostatic Probes for Plasma Sheath Diagnostic  

SciTech Connect

An interesting aspect in the research of complex (dusty) plasmas is the experimental study of the interaction of micro-particles of different sizes with the surrounding plasma for diagnostic purpose. In the plasma micro-disperse particles are negatively charged and confined in the sheath. The particles are trapped by an equilibrium of gravity, electric field force and ion drag force. From the behavior, local electric fields can be determined, e.g. particles are used as electrostatic probes. In combination with additional measurements of the plasma parameters with Langmuir probes and thermal probes as well as by comparison with an analytical sheath model, the structure of the sheath can be described. In the present work we focus on the behavior of micro-particles of different sizes and several plasma parameters e.g. the gas pressure and the rf-power.

Wolter, Matthias; Haass, Moritz; Ockenga, Taalke; Kersten, Holger [IEAP, University Kiel, Kiel (Germany); Blazec, Joseph [Department of Physics, University of South Bohemia (Czech Republic); Basner, Ralf [Leibniz-Institute for Plasma Science and Technology, Greifswald (Germany)

2008-09-07

382

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

383

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

384

Fabrication of a normally-closed microvalve utilizing lithographically defined silicone micro O-rings  

NASA Astrophysics Data System (ADS)

The focus of this work is on the development of a simple and variable process chain for the integration of flexible silicone material into silicon-based microfluidic devices. A normally-closed microvalve is chosen as a demonstrator device, as it combines features that are not easily obtained from silicon devices alone, especially, a high leak tightness of up to 1 bar pressure difference in the closed state and a high forward flow of several mL min^{-1} in the open state. For this purpose, a photopatternable silicone is used as a deformable circular valve lip between a piezoelectrically actuated membrane and a valve seat, similar to a micro O-ring with a width of 50 µm. The microvalve is piezo actuated by monolayer piezo actuators with a peak-to-peak driving voltage of V_{p{--p}} = 200 V. The micro O-ring is pre-deformed by 2.8 µm during the valve fabrication process to yield the normally-closed behavior. A dry film resist lamination technology is developed for this critical process step to mate the two silicon wafers with the actuation membrane, the valve seat and the silicone O-ring in between at a well-defined distance. The dry film resist is used in a multifunctional way, not only to pre-deform the valve lip, but also to define the geometry of the valve chamber and to ensure a leak-tight connection of both wafers. Altogether, a peak value for the on- to off-ratio of the normally-closed microvalve higher than 30 000 is measured. This opens a wide range of potential applications, e.g. in micro-dosing, drug delivery, ?-TAS and microfluidics for biological or chemical applications in general.

Lemke, T.; Kloeker, J.; Biancuzzi, G.; Huesgen, T.; Goldschmidtboeing, F.; Woias, P.

2011-02-01

385

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

386

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

387

Graduate Program Micro-and Nanostructures  

E-print Network

Graduate Program Micro- and Nanostructures in Optoelectronics and Photonics Project leaders Physics Contact Research Training Group Micro- and Nanostructures in Optoelectronics and Photonics Prof. H Lecture "Micro- and nanostructures in optoelectronics and photonics": Topical research areas

Hellebrand, Sybille

388

Micro ion frequency standard  

NASA Astrophysics Data System (ADS)

We are developing a highly miniaturized trapped ion clock to probe the 12.6 GHz hyperfine transition in the 171Yb+ ion. The clock development is being funded by the Integrated Micro Primary Atomic Clock Technology (IMPACT) program from DARPA where the stated goals are to develop a clock that consumes 50 mW of power, has a size of 5 cm3, and has a long-term frequency stability of 10-14 at one month. One of the significant challenges will be to develop miniature single-frequency lasers at 369 nm and 935 nm and the optical systems to deliver light to the ions and to collect ion fluorescence on a detector.

Schwindt, Peter D. D.; Jau, Yuan-Yu; Partner, Heather; Serkland, Darwin K.; Boye, Robert; Fang, Lu; Casias, Adrian; Manginell, Ronald P.; Moorman, Matthew; Prestage, John; Yu, Nan

2011-06-01

389

Micro UV detector  

NASA Astrophysics Data System (ADS)

A lightweight, tactical biological agent detection network offers the potential for a detect-to-warn capability against biological aerosol attacks. Ideally, this capability can be achieved by deploying the sensors upwind from the protected assets. The further the distance upwind, the greater the warning time. The technological challenge to this concept is the biological detection technology. Here, cost, size and power are major factors in selecting acceptable technologies. This is in part due to the increased field densities needed to cover the upwind area and the fact that the sensors, when deployed forward, must operate autonomously for long periods of time with little or no long-term logistical support. The Defense Advanced Research Project Agency"s (DARPA) Solid-state Ultraviolet Optical Source (SUVOS) program offers an enabling technology to achieving a detector compatible with this mission. As an optical source, these devices emit excitation wavelengths known to be useful in the detection of biological aerosols. The wavelength band is absorbed by the biological aerosol and results in visible fluorescence. Detection of a biological aerosol is based on the observed intensity of this fluorescence signal compared to a background reference. Historically this has been accomplished with emission sources that are outside the boundaries for low cost, low power sensors. The SUVOS technology, on the other hand, provides the same basic wavelengths needed for the detection process in a small, low power package. ECBC has initiated an effort to develop a network array based on micro UV detectors that utilize the SUVOS technology. This paper presents an overview of the micro UV detector and some of the findings to date. This includes the overall design philosophy, fluid flow calculations to maximize presentation of aerosol particles to the sources, and the fluorescence measurements.

Cabalo, Jerry B.; Sickenberger, Richard; Underwood, William J.; Sickenberger, David W.

2004-09-01

390

Micro-UV detector  

NASA Astrophysics Data System (ADS)

A lightweight, tactical biological agent detection network offers the potential for a detect-to-warn capability against biological aerosol attacks. Ideally, this capability can be achieved by deploying the sensors upwind from the protected assets. The further the distance upwind, the greater the warning time. The technological challenge to this concept is the biological detection technology. Here, cost, size and power are major factors in selecting acceptable technologies. This is in part due to the increased field densities needed to cover the upwind area and the fact that the sensors, when deployed forward, must operate autonomously for long periods of time with little or no long-term logistical support. The Defense Advanced Research Project Agency"s (DARPA) Solid-state Ultraviolet Optical Source (SUVOS) program offers an enabling technology to achieving a detector compatible with this mission. As an optical source, these devices emit excitation wavelengths known to be useful in the detection of biological aerosols. The wavelength band is absorbed by the biological aerosol and results in visible fluorescence. Detection of a biological aerosol is based on the observed intensity of this fluorescence signal compared to a background reference. Historically this has been accomplished with emission sources that are outside the boundaries for low cost, low power sensors. The SUVOS technology, on the other hand, provides the same basic wavelengths needed for the detection process in a small, low power package. ECBC has initiated an effort to develop a network array based on micro UV detectors that utilize the SUVOS technology. This paper presents an overview of the micro UV detector and some of the findings to date. This includes the overall design philosophy, fluid flow calculations to maximize presentation of aerosol particles to the sources, and the fluorescence measurements.

Cabalo, Jerry B.; Sickenberger, Richard; Underwood, William J.; Sickenberger, David W.

2004-12-01

391

Novel micro-pneumatic actuator for MEMS  

Microsoft Academic Search

This paper presents a micro-pneumatic actuator utilizing a new actuation principle for micro-mechanical systems. As a first application, a micro-gripper driven by two bellow-type micro-pneumatic actuators, is described. The basic structures of the micro-pneumatic actuator and the micro-gripper are fabricated by silicon dry etching in a single etching step. The device consists of a Pyrex–silicon–Pyrex sandwich structure which was assembled

Sebastian Bütefisch; Volker Seidemann; Stephanus Büttgenbach

2002-01-01

392

Polymer-functionalized single-walled carbon nanotubes as a novel sol-gel solid-phase micro-extraction coated fiber for determination of poly-brominated diphenyl ethers in water samples with gas chromatography-electron capture detection.  

PubMed

Single-walled carbon nanotubes (SWNTs) were functionalized with a hydroxyl-terminated silicone oil (TSO-OH). It is synthesized by the reactions of carbonyl chloride groups on the surface of SWNTs and hydroxyl groups of silicone oil (TSO-OH). The functionalized product SWNTs-TSO-OH was first used as precursor and selective stationary phase to prepare the sol-gel derived poly(SWNTs-TSO-OH) solid-phase microextraction (SPME) fiber for determination of polybrominated diphenyl ethers (PBDEs) in water samples. The possible major reaction of the sol-gel coating process was discussed and confirmed by IR spectra, Raman spectroscopy, and scanning electron microscopy. Some parameters of SPME fiber for the determination of PBDEs were investigated by headspace SPME/gas chromatography with electron-capture detection (HS-SPME/GC-ECD). Compared with the commercial SPME fiber, the new coated fiber showed higher extraction efficiency to PBDEs, better thermal stability (over 340 degrees C), and longer life span (over 200 times). All of these advantages are mainly due to the incorporation of SWNTs, which enhanced the pi-pi interaction with PBDEs and increased the surface area of extraction in contact with the sample. Moreover, the sol-gel coating technology additionally provided the porous structure of the 3-D silica network and the strong chemical binding provided which also will improve the extraction efficiency. Under optimized conditions, the method detection limits for seven PBDEs were 0.08-0.8 ng/L (S/N = 3) and the precision (RSD, n = 5) was 2.2-7.5% at the 50 ng/L level. The linearity of the developed method is in the range of 5-500 ng/L with coefficients of correlation greater than 0.995. The developed method was successfully applied for the analysis of trace PBDEs in reservoir water and wastewater samples. The recoveries obtained at spiking 50 ng/L were between 74% and 109% (n = 5) for PBDEs in water samples. PMID:19364140

Zhang, Weiya; Sun, Yin; Wu, Caiying; Xing, Jun; Li, Jianying

2009-04-15

393

Simulations for gas flows in microgeometries using the direct simulation Monte Carlo method  

Microsoft Academic Search

Micro gas flows are often encountered in MEMS devices and classical CFD could not accurately predict the flow and thermal behavior due to the high Knudsen number. Therefore, the gas flow in microgeometries was investigated using the direct simulation Monte Carlo (DSMC) method. New treatments for boundary conditions are verified by simulations of micro-Poiseuille flow, compared with the previous boundary

Moran Wang; Zhixin Li

2004-01-01

394

Dual liquid and gas chromatograph system  

DOEpatents

A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

Gay, Don D. (Aiken, SC)

1985-01-01

395

Gas Gangrene  

MedlinePLUS

... Issues > Conditions > Skin > Gas Gangrene Health Issues Listen Gas Gangrene Article Body Gangrene describes the death of ... this is the case, the disease is called gas gangrene or clostridial myonecrosis (myo refers to muscle, ...

396

Gas gangrene  

MedlinePLUS

Tissue infection - Clostridial; Gangrene - gas; Myonecrosis; Clostridial infection of tissues ... Gas gangrene is most often caused by a bacterium called Clostridium perfringens. It also can be caused ...

397

Fig. 1: Micro-fluidic Temperature micro-sensor. A New millimeter-wave micro-fluidic Temperature  

E-print Network

1,16mm 525µm 880µm 100µm Fig. 1: Micro-fluidic Temperature micro-sensor. A New millimeter-wave micro-fluidic Temperature sensor for wireless passive radar interrogation S. Bouaziz, F. Chebila, A-250, U.S.A. Abstract-- This paper presents a micro-fluidic temperature sensor that uses a variable radar

Paris-Sud XI, Université de

398

Nano-scale NiSi and n-type silicon based Schottky barrier diode as a near infra-red detector for room temperature operation  

SciTech Connect

The fabrication of nano-scale NiSi/n-Si Schottky barrier diode by rapid thermal annealing process is reported. The characterization of the nano-scale NiSi film was performed using Micro-Raman Spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The thickness of the film (27?nm) has been measured by cross-sectional Secondary Electron Microscopy and XPS based depth profile method. Current–voltage (I–V) characteristics show an excellent rectification ratio (I{sub ON}/I{sub OFF}?=?10{sup 5}) at a bias voltage of ±1?V. The diode ideality factor is 1.28. The barrier height was also determined independently based on I–V (0.62?eV) and high frequency capacitance–voltage technique (0.76?eV), and the correlation between them has explained. The diode photo-response was measured in the range of 1.35–2.5??m under different reverse bias conditions (0.0–1.0?V). The response is observed to increase with increasing reverse bias. From the photo-responsivity study, the zero bias barrier height was determined to be 0.54?eV.

Roy, S. [Centre for Nanotechnology and Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Centre of Excellence in Nanoelectronics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Midya, K.; Duttagupta, S. P., E-mail: sdgupta@ee.iitb.ac.in [Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India); Centre of Excellence in Nanoelectronics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Ramakrishnan, D. [Department of Earth Science, Indian Institute of Technology Bombay, Mumbai 400076 (India)

2014-09-28

399

Knudsen torque on heated micro beams  

NASA Astrophysics Data System (ADS)

Thermally induced mechanical loading has been shown to have significant effects on micro/nano objects immersed in a gas with a non-uniform temperature field. While the majority of existing studies and related applications focus on forces, we investigate the torque, and thus the rotational motion, produced by such a mechanism. Using the asymptotic analysis in the near continuum regime, the Knudsen torque acting on an asymmetrically located uniformly heated microbeam in a cold enclosure is investigated. The existence of a non-zero net torque is demonstrated. In addition, it has been found that by manipulating the system configuration, the rotational direction of the torque can be changed. Two types of rotational motion of the microbeam have been identified: the pendulum motion of a rectangular beam, and the unidirectional rotation of a cylindrical beam. A rotational frequency of 4 rpm can be achieved for the cylindrical beam with a diameter of 3?m at Kn = 0.005. Illustrated by the simulations using the direct simulation of Monte Carlo, the Knudsen torque can be much increased in the transition regime, demonstrating the potential of Knudsen torque serving as a rotation engine for micro/nano objects.

Li, Qi; Liang, Tengfei; Ye, Wenjing

2014-12-01

400

Microfabrication of high temperature micro-reactors for continuous flow isotope ratio mass spectrometry  

Microsoft Academic Search

Robust, high temperature micro-reactors for on-line conversion of organic compounds were microfabricated in high purity fused\\u000a silica to enable stable isotopic compositional analysis of individual compounds in mixtures using advanced gas chromatography\\u000a (GC) separation techniques, such as fast GC and comprehensive 2D GC, coupled to isotope ratio mass spectrometry (IRMS). These\\u000a micro-reactors could also be manufactured at larger channel dimensions

Herbert J. TobiasJ; J. Thomas Brenna

2010-01-01

401

Levitated micro-accelerometer.  

SciTech Connect

The objective is a significant advancement in the state-of-the-art of accelerometer design for tactical grade (or better) applications. The design goals are <1 milli-G bias stability across environments and $200 cost. This quantum leap in performance improvement and cost reduction can only be achieved by a radical new approach, not incremental improvements to existing concepts. This novel levitated closed-loop accelerometer is implemented as a hybrid micromachine. The hybrid approach frees the designer from the limitations of any given monolithic process and dramatically expands the available design space. The design can be tailored to the dynamic range, resolution, bandwidth, and environmental requirements of the application while still preserving all of the benefits of monolithic MEMS fabrication - extreme precision, small size, low cost, and low power. An accelerometer was designed and prototype hardware was built, driving the successful development and refinement of several 'never been done before' fabrication processes. Many of these process developments are commercially valuable and are key enablers for the realization of a wide variety of useful micro-devices. While controlled levitation of a proof mass has yet to be realized, the overall design concept remains sound. This was clearly demonstrated by the stable and reliable closed-loop control of a proof mass at the test structure level. Furthermore, the hybrid MEMS implementation is the most promising approach for achieving the ambitious cost and performance targets. It is strongly recommended that Sandia remain committed to the original goal.

Warne, Larry Kevin; Schmidt, Carrie Frances; Peterson, Kenneth Allen; Kravitz, Stanley H.; Renn, Rosemarie A.; Peter, Frank J.; Kinney, Ragon D.; Gilkey, Jeffrey C.

2004-06-01

402

Revealing lithium-silicide phase transformations in nano-structured silicon based lithium ion batteries via in-situ NMR spectroscopy  

E-print Network

(~50 nm, as measured by a quartz crystal balance) was evaporated onto 200 ?m-thick carbon fibre based gas diffusion layer support (CFGDL: SGL group, GDL24AA, 99.9 % carbon) and onto 20 ?m-thick stainless steel (SS) (SUS304, Agar Scientific... then opened in the Ar glovebox, washed with DMC, dried for 10 min in vacuum and immediately packed in the rotor for the NMR measurements. All the 7Li NMR shifts were referenced to 1 M LiCl (at 0 ppm) as an external reference. Identification of a suitable...

Ogata, K.; Salager, E.; Kerr, C. J.; Fraser, A. E.; Ducati, C.; Morris, A. J.; Hofmann, S.; Grey, C. P.

2014-02-03

403

Patterned graphene functionalization via mask-free scanning of micro-plasma jet under ambient condition  

SciTech Connect

In this work, a mask-free method is introduced for patterned nitrogen doping of graphene using a micro-plasma jet under ambient condition. Raman and X-ray photoelectron spectroscopy spectra indicate that nitrogen atoms are incorporated into the graphene lattice with the two-dimensional spatial distribution precisely controlled in the range of mm down to 10??m. Since the chemistry of the micro-plasma jet can be controlled by the choice of the gas mixture, this direct writing process with micro-plasma jet can be a versatile approach for patterned functionalization of graphene with high spatial resolution. This could have promising applications in graphene-based electronics.

Ye, Dong; Yu, Yao, E-mail: ensiyu@mail.hust.edu.cn; Liu, Lin [School of Materials Science and Engineering, Huazhong University of Science and Technology, 430074 Wuhan (China)] [School of Materials Science and Engineering, Huazhong University of Science and Technology, 430074 Wuhan (China); Wu, Shu-Qun; Lu, Xin-Pei [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)] [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Wu, Yue [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3255 (United States)] [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3255 (United States)

2014-03-10

404

A micro controlled peripheral processor  

Microsoft Academic Search

This paper discusses the design and construction of a micro controlled mini-computer used as peripheral processor unit for the PDP-11\\/20 in the Electrical and Computer Engineering Laboratory at the University of Massachusetts at Amherst. The instruction set for this computer is determined by the micro code in a read only memory (ROM) and is therefore flexible: Changing the ROM results

E. T. Barron; R. M. Glorioso

1973-01-01

405

Development of Micro UAV Swarms  

Microsoft Academic Search

\\u000a Some complex application scenarios for micro UAVs (Unmanned Aerial Vehicles) call for the formation of swarms of multiple\\u000a drones. In this paper a platform for the creation of such swarms is presented. It consists of modified commercial quadrocopters\\u000a and a self-made ground control station software architecture. Autonomy of individual drones is generated through a micro controller\\u000a equipped video camera. Currently

Axel Bürkle; Sandro Leuchter

2009-01-01

406

Investigation of the performance of an optimised MicroCAT, a GEM and their combination by simulations and current measurements  

NASA Astrophysics Data System (ADS)

A Micro compteur à Trous (MicroCAT) structure which is used for avalanche charge multiplication in gas filled radiation detectors has been optimised with respect to maximum electron transparency and minimum ion feedback. We report on the charge transfer behaviour and the achievable gas gain of this device. A three-dimensional electron and ion transfer simulation is compared to results derived from electric current measurements. Similarly, we present studies of the charge transfer behaviour of a Gas Electron Multiplier (GEM) by current measurements and simulations. Finally, we investigate the combination of the MicroCAT and the GEM by measurements with respect to the performance at different voltage settings, gas mixtures and gas pressures.

Orthen, A.; Wagner, H.; Besch, H. J.; Menk, R. H.; Walenta, A. H.; Werthenbach, U.

2003-03-01

407

Center for Micro-and Nanotechnologies  

E-print Network

Center for Micro- and Nanotechnologies Technische Universität Ilmenau Biannual Report 2005/2006 Institute of Micro- and Nanotechnologies #12;Editorial Board: Editor: Principal of the TU Ilmenau, Prof. Dr and Koch, Weimar Funding: µ-Comp e. V. #12;Institute of Micro- and Nanotechnologies Center for Micro

Knobloch,Jürgen

408

Micro thrust and heat generator  

SciTech Connect

The present invention relates generally to micromachines such as microengines or micromotors. More specifically, the invention is directed to a micro rocket which functions as a source of heat and thrust, and utilizes chemical energy to drive or power micromechanical apparatuses. The invention is adaptable to applications involving defense, bio-medical, manufacturing, consumer product, aviation, automotive, computer, inspection, and safety systems. 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 micromachine techniques (LIGA).

Garcia, E.J.

1995-12-31

409

Silicon Carbide-Based Hydrogen and Hydrocarbon Gas Detection  

NASA Technical Reports Server (NTRS)

Hydrogen and hydrocarbon detection in aeronautical applications is important for reasons of safety and emissions control. The use of silicon carbide as a semiconductor in a metal-semiconductor or metal-insulator-semiconductor structure opens opportunities to measure hydrogen and hydrocarbons in high temperature environments beyond the capabilities of silicon-based devices. The purpose of this paper is to explore the response and stability of Pd-SiC Schottky diodes as gas sensors in the temperature range from 100 to 400 C. The effect of heat treating on the diode properties as measured at 100 C is explored. Subsequent operation at 400 C demonstrates the diodes' sensitivity to hydrogen and hydrocarbons. It is concluded that the Pd-SiC Schottky diode has potential as a hydrogen and hydrocarbon sensor over a wide range of temperatures but further studies are necessary to determine the diodes' long term stability.

Hunter, Gary W.; Neudeck, Philip G.; Chen, Liang-Yu; Knight, D.; Liu, C. C.; Wu, Q. H.R

1995-01-01

410

Micro Weather Station  

NASA Technical Reports Server (NTRS)

Improved in situ meteorological measurements in the troposphere and stratosphere are needed for studies of weather and climate, both as a primary data source and as validation for remote sensing instruments. Following the initial development and successful flight validation of the surface acoustic wave (SAW) hygrometer, the micro weather station program was directed toward the development of an integrated instrument, capable of accurate, in situ profiling of the troposphere, and small enough to fly on a radiosonde balloon for direct comparison with standard radiosondes. On April 23, 1998, working with Frank Schmidlin and Bob Olson of Wallops Island Flight Facility, we flew our instrument in a dual payload experiment, for validation and direct comparison with a Vaisala radiosonde. During that flight, the SAW dewpoint hygrometer measured frostpoint down to -76T at 44,000 feet. Using a laptop computer in radio contact with the balloon, we monitored data in real time, issued the cutdown command, and recovered the payload less than an hour after landing in White Sands Missile Range, 50 miles from the launch site in Hatch, New Mexico. Future flights will extend the intercomparison, and attempt to obtain in situ meteorological profiles from the surface through the tropopause. The SAW hygrometer was successfully deployed on the NASA DC8 as part of NASA's Third Convection and Moisture Experiment (CAMEX-3) during August and September, 1998. This field campaign was devoted to the study of hurricane tracking and intensification using NASA-funded aircraft. In situ humidity data from the SAW hygrometer are currently being analyzed and compared with data from other instruments on the DC8 and ER2 aircraft. Additional information is contained in the original.

Hoenk, Michael E.

1999-01-01

411

Desktop Micro Forming System for Micro Pattern on the Metal Substrate  

E-print Network

Desktop Micro Forming System for Micro Pattern on the Metal Substrate Hye-Jin Lee1,1 , Jung. In this Research, the desktop micro forming manufacturing system has been developed. A micro forming system has been achieved in Japan and its developed micro press is limited to single forming process. To coincide

Paris-Sud XI, Université de

412

Micro-manipulation of silicate micro-sized particles for biological applications  

E-print Network

Micro-manipulation of silicate micro-sized particles for biological applications David Hériban micro-manipulation station able to grasp, transport and release ten micrometers objects. Devoted and release it in the bacteria liquid medium. I. INTRODUCTION Micro-manipulation is a feature key in micro

Paris-Sud XI, Université de

413

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. PMID:20036310

Siegel, Ronald A.; Gu, Yuandong; Lei, Ming; Baldi, Antonio; Nuxoll, Eric E.; Ziaie, Babak

2010-01-01

414

Development of silicon optics for an integrated micro-optical system-on-a-chip  

NASA Astrophysics Data System (ADS)

Development of silicon-based passive optical components such as reflectors, waveguides, and beam splitters coupled with active elements such as light emitters and detectors enable miniaturisation of a low-cost system-on-a-chip sensing device. In this work, we investigate methods to fabricate passive silicon elements on a chip. We use a combination of wet and dry etching techniques to realise angled and vertical sidewalls normal to the surface of a silicon wafer, respectively. For wet etching, we used Triton-X, a surfactant, added to an alkaline solution TMAH as the etchant. This allows perfect 45° inclined sidewalls to be fabricated. Dry etching using DRIE is to be performed on the reverse-side of the same wafer to realize through-hole vias with straight vertical sidewalls. A final Au metal layer can then be coated onto the sidewalls to realize reflective surfaces. Photolithography masks used in the wet and dry etch processes were designed and fabricated. By careful alignment of these masks using a mask aligner, we can fabricate a combination of inclined and vertical sidewalls to build optical reflectors and beam splitters with complex geometries. When integrated with active Si-optical devices, a fully integrated micro-optical system-on-a-chip can be realised.

Ng, David C.; Kandasamy, Sasikaran; Skafidas, Efstratios

2013-12-01

415

A secure WDM ring access network employing silicon micro-ring based remote node  

NASA Astrophysics Data System (ADS)

A secure and scalable wavelength-division-multiplexing (WDM) ring-based access network is proposed and demonstrated using proof-of-concept experiments. In the remote node (RN), wavelength hopping for specific optical networking unit (ONU) is deployed by using silicon micro-ring resonators (SMR). Using silicon-based devices could be cost-effective for the cost-sensitive access network. Hence the optical physical layer security is introduced. The issues of denial of service (DOS) attacks, eavesdropping and masquerading can be made more difficult in the proposed WDM ring-based access network. Besides, the SMRs with different dropped wavelengths can be cascaded, such that the signals pass through the preceding SMRs can be dropped by a succeeding SMR. This can increase the scalability of the RN for supporting more ONUs for future upgrade. Here, error-free 10 Gb/s downlink and 1.25 Gb/s uplink transmission are demonstrated to show the feasibility of the proposed network.

Sung, Jiun-Yu; Chow, Chi-Wai; Yeh, Chien-Hung; Xu, Ke; Hsu, Chin-Wei; Su, Hong-Quan; Tsang, Hon-Ki

2014-08-01

416

Micro-layered-photolithography for Micro-Fabrication and Micro-Molding  

E-print Network

A novel process based on the principle of layered photolithography has been proposed and tested for making real three-dimensional micro-structures. An experimental setup was designed and built for doing experiments on this ...

Tang, Y.

417

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

418

Reconstruction algorithms for laboratory microCT/microXRF system  

NASA Astrophysics Data System (ADS)

An integrated microCT/microXRF system has been designed and built at SkyScan. The two sub-systems are aligned. The microCT provides 3D morphological information of the sample, which can be also used for attenuation correction during microXRF reconstruction. The microXRF, based on a pin-hole collimator and a photon-counting energy-sensitive 2Ddetector, obtains 2D projections of 3D chemical composition inside the sample with 50-70 microns spatial resolution. The reconstruction of 3D microXRF scans is challenging because of very low photon counting statistics due to limited power of laboratory x-ray sources and the strong self-absorption of the low-energy fluorescence photons. We have developed a maximum-likelihood expectation-maximization (ML-EM) algorithm based on Poisson model. This algorithm has proven to be rather robust and good reconstructions have been obtained with sample scans. Regularization is necessary to achieve stable reconstruction. One method is to apply smoothing between iterations. Two different smoothing kernels have been evaluated: 3D symmetric Gaussian kernel and minimization of total variation. For further improvement, a multi-ray resolution recovery technique has been evaluated. The self-absorption is currently compensated by a simplified method: the correction coefficients are pre-calculated and obtained by forward-projecting the attenuation map for both the primary X-rays and the fluorescence photons. The attenuation maps at the energy of fluorescence photons are approximated from the CT image.

Liu, Xuan; Bruyndonckx, Peter; Sasov, Alexander

2010-09-01

419

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

NASA Technical Reports Server (NTRS)

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.

1992-01-01

420

Micro Machining Enhances Precision Fabrication  

NASA Technical Reports Server (NTRS)

Advanced thermal systems developed for the Space Station Freedom project are now in use on the International Space Station. These thermal systems employ evaporative ammonia as their coolant, and though they employ the same series of chemical reactions as terrestrial refrigerators, the space-bound coolers are significantly smaller. Two Small Business Innovation Research (SBIR) contracts between Creare Inc. of Hanover, NH and Johnson Space Center developed an ammonia evaporator for thermal management systems aboard Freedom. The principal investigator for Creare Inc., formed Mikros Technologies Inc. to commercialize the work. Mikros Technologies then developed an advanced form of micro-electrical discharge machining (micro-EDM) to make tiny holes in the ammonia evaporator. Mikros Technologies has had great success applying this method to the fabrication of micro-nozzle array systems for industrial ink jet printing systems. The company is currently the world leader in fabrication of stainless steel micro-nozzles for this market, and in 2001 the company was awarded two SBIR research contracts from Goddard Space Flight Center to advance micro-fabrication and high-performance thermal management technologies.

2007-01-01

421

A development of experimental system for macro-micro teleoperation  

Microsoft Academic Search

Micro components of micro machines, such as mechanisms, gears, sensors and actuators which are almost invisible, have been made by recent advance of mechanical and electronic engineering. The production of micro machines, however, requires new technologies for assembling micro parts into complete micro machines. Macro-micro teleoperation is one of the key technologies for constructing micro machines and will help human

Kenji KANEKO; Hiroki TOKASHIKI; Kazuo TANIE; Kiyoshi KOMORIYA

1995-01-01

422

Experimental study of micro electrical discharge machining discharges  

NASA Astrophysics Data System (ADS)

Micro electrical discharge machining (?EDM) is an atmospheric-pressure plasma-assisted technology that uses point-to-plane discharges in liquid dielectrics to remove microscopic quantities of electrically conductive materials. In this work, an innovative ?EDM prototype machine was specifically designed and fabricated to produce and control single spark discharges, thus, resolving the typical limitations of (multi-discharge) commercial machines. The work analyses the type of discharge and the micro-plasma electron-density values obtained for 0.5-38 ?m gap sizes, 3-10 000 ?s pulse durations, 75-250 V low breakdown voltages, and 1-20 A discharge currents, using different combinations of metallic electrodes in oil and in water. Results allow fitting, for micro-scale and low voltages, an empirical law between the maximum gap-size for breakdown, the breakdown voltage, and the effective stress-time. The electron density ne is obtained by optical emission spectroscopy diagnostics of the H?-line Stark broadening (yielding ne˜1016-1017 cm-3, i.e., ionization degrees of ˜2×10-5-10-4) and by a semi-empirical resistive plasma model. The model uses the experimental values of several electrical and geometrical quantities, and of the gas pressure estimated as ˜60 bar-2 kbar from measurements of the plasma mechanical action, obtained using a force sensor. The quantitative information of this phenomenological study can assist the optimization of this micro-fabrication technique.

Bragança, I. M. F.; Rosa, P. A. R.; Dias, F. M.; Martins, P. A. F.; Alves, L. L.

2013-06-01

423

Stabilizing factors of the molecular structure in silicon-based peptidomimetics in gas-phase and water solution. Assessment of the correlation between different descriptors of hydrogen bond strength.  

PubMed

The use of DFT (B3LYP and M06L) and ab initio (MP2) computational methods allowed us to perform a thorough conformational study of N-[dihydroxy (methyl)silyl]methylformamide (DHSF) and 3-[dihydroxy (methyl) silyl] propanamide (DHSP), that could be considered simplified models of the environment of the silanediol group in silicon gem-diols that have proven efficiency as protease inhibitors. We have found a total of 13 molecular conformations that represent minima in the potential energy surfaces of DHSF (six conformers) and DHSP (seven conformers). The key feature in their molecular structure is the occurrence of intramolecular hydrogen bonding between the hydroxyl and aminocarbonyl groups. We have estimated the strength of each individual hydrogen bond in the mentioned species using the descriptors proposed by three different methodologies, i.e., the quantum theory of atoms in molecules (QTAIM), the natural bond orbitals population analysis (NBO), and the so-called empirical Rozenberg's enthalpy-distance relationship. We have found a good correlation among the calculated values for the different descriptors within the whole set of conformers in the molecular systems in this study. We have also discussed the predicted order of stabilities of the different conformers of each species in terms of the so-called ring anomeric effect (RAE) and generalized anomeric effect (GAE). Finally, we also analyzed the discrepancies found in the order of stability when going from the isolated molecule approximation to water solution (PCM). PMID:23900857

Rodríguez Ortega, María Pilar Gema; Montejo, Manuel; López González, Juan Jesús

2013-10-01

424

Zeolite-dye micro lasers  

E-print Network

We present a new class of micro lasers based on nanoporous molecular sieve host-guest systems. Organic dye guest molecules of 1-Ethyl-4-(4-(p-Dimethylaminophenyl)-1,3-butadienyl)-pyridinium Perchlorat were inserted into the 0.73-nm-wide channel pores of a zeolite AlPO$_4$-5 host. The zeolitic micro crystal compounds where hydrothermally synthesized according to a particular host-guest chemical process. The dye molecules are found not only to be aligned along the host channel axis, but to be oriented as well. Single mode laser emission at 687 nm was obtained from a whispering gallery mode oscillating in a 8-$\\mu$m-diameter monolithic micro resonator, in which the field is confined by total internal reflection at the natural hexagonal boundaries inside the zeolitic microcrystals.

Vietze, U; Laeri, F; Ihlein, G; Schüth, F; Limburg, B; Abraham, M

1998-01-01

425

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

426

Simple gas chromatographic system for analysis of microbial respiratory gases  

NASA Technical Reports Server (NTRS)

Dual column ambient temperature system, consisting of pair of capillary columns, microbead thermistor detector and micro gas-sampling valve, is used in remote life-detection equipment for space experiments. Performance outweighs advantage gained by utilizing single-column systems to reduce weight, conserve carrier gas and operate at lower power levels.

Carle, G. C.

1972-01-01

427

The growth and harvesting of algae in a micro-gravity environment  

NASA Technical Reports Server (NTRS)

Algae growth in a micro-gravity environment is an important factor in supporting man's permanent presence in space. Algae can be used to produce food, oxygen, and pure water in a manned space station. A space station is one example of a situation where a Controlled Ecological Life Support System (CELSS) is imperative. In setting up a CELSS with an engineering approach at the Aerospace department of the University of Colorado, questions concerning algae growth in micro-g have arisen. The Get Away Special (GAS) Fluids Management project is a means through which many questions about the effects of a micro-g environment on the adequacy of growth rates, the viability of micro-organisms, and separation of gases and solids for harvesting purposes can be answered. In order to be compatible with the GAS tests, the algae must satisfy the following criteria: (1) rapid growth rates, (2) sustain viability over long periods of non-growth storage, and (3) very brief latency from storage to rapid growth. Testing indicates that the overall growth characteristics of Anacystis Nidulans satisfy the specifications of GAS's design constraints. In addition, data acquisition and the method of growth instigation are two specific problems being examined, as they will be encountered in interfacing with the GAS project. Flight testing will be two-fold, measurement of algae growth in micro-g and separation of algae from growth medium in an artificial gravitation field. Post flight results will provide information on algae viability in a micro-g environment as reflected by algal growth rates in space. Other post flight results will provide a basis for evaluating techniques for harvesting algae. The results from the GAS project will greatly assist the continuing effort of developing the CELSS and its applications for space.

Wiltberger, Nancy L.

1987-01-01

428

Transferts INFO 2A -2009-2010 Rpartition des groupes Salle micro6 (F7) Salle micro3 (H10) Salle micro5 (H10)  

E-print Network

Transferts INFO 2A - 2009-2010 Répartition des groupes Salle micro6 (F7) Salle micro3 (H10) Salle micro5 (H10) CEVALLOS Fernando EL KHOLY Samy ROGLER Pierre DE BOISSEZON Benjamin GOUZENES Quentin DEMOULIN Alexandre PONSOT Emmanuel VALTON Paul Salle micro6 (F7) Salle micro3 (H10) Salle micro5 (H10) AL

Dellandréa, Emmanuel

429

Job Title BIOLOGY GENETICS MICRO TOX TOTAL BIOLOGY GENETICS MICRO TOX TOTAL BIOLOGY GENETICS MICRO TOX TOTAL T/TT Faculty  

E-print Network

Job Title BIOLOGY GENETICS MICRO TOX TOTAL BIOLOGY GENETICS MICRO TOX TOTAL BIOLOGY GENETICS MICRO.00 Job Title NTT Faculty BIOLOGY GENETICS MICRO TOX TOTAL BIOLOGY GENETICS MICRO TOX TOTAL BIOLOGY GENETICS MICRO TOX TOTAL Lecturer 3.76 2.00 5.76 3.76 2.00 - - 5.76 Teaching Asst Professor 8.57 2.00 10

Liu, Paul

430

Micro-machined calorimetric biosensors  

DOEpatents

A method and apparatus are provided for detecting and monitoring micro-volumetric enthalpic changes caused by molecular reactions. Micro-machining techniques are used to create very small thermally isolated masses incorporating temperature-sensitive circuitry. The thermally isolated masses are provided with a molecular layer or coating, and the temperature-sensitive circuitry provides an indication when the molecules of the coating are involved in an enthalpic reaction. The thermally isolated masses may be provided singly or in arrays and, in the latter case, the molecular coatings may differ to provide qualitative and/or quantitative assays of a substance.

Doktycz, Mitchel J. (Knoxville, TN); Britton, Jr., Charles L. (Alcoa, TN); Smith, Stephen F. (Loudon, TN); Oden, Patrick I. (Plano, TX); Bryan, William L. (Knoxville, TN); Moore, James A. (Powell, TN); Thundat, Thomas G. (Knoxville, TN); Warmack, Robert J. (Knoxville, TN)

2002-01-01

431

Gastric-fluid-utilizing micro battery for micro medical devices  

Microsoft Academic Search

A variety of micro medical devices have been developed to provide more advanced and less invasive medical treatment. An effective power supply is crucial to the operation of these devices. Currently, two types of power supply are used: small batteries or radio-power transmission. However, the former limits the operating time of the devices, while radio-power transmission affects other medical devices

Hikaru Jimbo; Norihisa Miki

2008-01-01

432

Fabrication of a Flexible Micro Temperature Sensor for Micro Reformer Applications  

PubMed Central

Micro reformers still face obstacles in minimizing their size, decreasing the concentration of CO, conversion efficiency and the feasibility of integrated fabrication with fuel cells. By using a micro temperature sensor fabricated on a stainless steel-based micro reformer, this work attempts to measure the inner temperature and increase the conversion efficiency. Micro temperature sensors on a stainless steel substrate are fabricated using micro-electro-mechanical systems (MEMS) and then placed separately inside the micro reformer. Micro temperature sensors are characterized by their higher accuracy and sensitivity than those of a conventional thermocouple. To the best of our knowledge, micro temperature sensors have not been embedded before in micro reformers and commercial products, therefore, this work presents a novel approach to integrating micro temperature sensors in a stainless steel-based micro reformer in order to evaluate inner local temperature distributions and enhance reformer performance. PMID:22163817

Lee, Chi-Yuan; Lin, Chien-Hen; Lo, Yi-Man

2011-01-01

433

Evaluation of stability and size distribution of sunflower oil-coated micro bubbles for localized drug delivery  

PubMed Central

Background Micro bubbles were initially introduced as contrast agents for ultrasound examinations as they are able to modify the signal-to-noise ratio in imaging, thus improving the assessment of clinical information on human tissue. Recent developments have demonstrated the feasibility of using these bubbles as drug carriers in localized delivery. In micro fluidics devices for generation of micro bubbles, the bubbles are formed at interface of liquid gas through a strangulation process. A device that uses these features can produce micro bubbles with small size dispersion in a single step. Methods A T-junction micro fluidic device constructed using 3D prototyping was made for the production of mono dispersed micro bubbles. These micro bubbles use sunflower oil as a lipid layer. Stability studies for micro bubbles with diameters different generated from a liquid phase of the same viscosity were conducted to evaluate whether micro bubbles can be used as drug carriers. The biocompatibility of coating layer, the ability to withstand environmental pressure variations combined with echogenicity, are key factors that they can safely play the role of drug transporters. Results The normal distribution curve with small dispersion of the diameter of bubbles validates the process of generating micro bubbles with low value of variation coefficient, i.e., 0.381 at 1.90%. The results also showed the feasibility of using sunflower oil as the lipid matrix with stable population of bubbles over 217 minutes for micro bubbles with an average diameter of 313.04 ?m and 121 minutes for micro bubbles with an average diameter of 73.74 ?m, considering bubbles with air as gaseous phase. Conclusion The results indicate that the micro fluidic device designed can be used for producing micro bubbles with low variation coefficient using sunflower oil as a coating of micro bubbles. These carriers were stable for periods of time that are long enough for clinical applications even when regular air is used as the gas phase. Improved stability can be achieved when biocompatible gas with lower permeability is used. PMID:22995578

2012-01-01

434

Micro mass spectrometer on a chip.  

SciTech Connect

The design, simulation, fabrication, packaging, electrical characterization and testing analysis of a microfabricated a cylindrical ion trap ({mu}CIT) array is presented. Several versions of microfabricated cylindrical ion traps were designed and fabricated. The final design of the individual trap array element consisted of two end cap electrodes, one ring electrode, and a detector plate, fabricated in seven tungsten metal layers by molding tungsten around silicon dioxide (SiO{sub 2}) features. Each layer of tungsten is then polished back in damascene fashion. The SiO{sub 2} was removed using a standard release processes to realize a free-hung structure. Five different sized traps were fabricated with inner radii of 1, 1.5, 2, 5 and 10 {micro}m and heights ranging from 3-24 {micro}m. Simulations examined the effects of ion and neutral temperature, the pressure and nature of cooling gas, ion mass, trap voltage and frequency, space-charge, fabrication defects, and other parameters on the ability of micrometer-sized traps to store ions. The electrical characteristics of the ion trap arrays were determined. The capacitance was 2-500 pF for the various sized traps and arrays. The resistance was in the order of 1-2 {Omega}. The inductance of the arrays was calculated to be 10-1500 pH, depending on the trap and array sizes. The ion traps' field emission characteristics were assessed. It was determined that the traps could be operated up to 125 V while maintaining field emission currents below 1 x 10{sup -15} A. The testing focused on using the 5-{micro}m CITs to trap toluene (C{sub 7}H{sub 8}). Ion ejection from the traps was induced by termination of the RF voltage applied to the ring electrode and current measured on the collector electrode suggested trapping of ions in 1-10% of the traps. Improvements to the to the design of the traps were defined to minimize voltage drop to the substrate, thereby increasing trapping voltage applied to the ring electrode, and to allow for electron injection into, ion ejection from, and optical access to the trapping region.

Cruz, Dolores Y.; Blain, Matthew Glenn; Fleming, James Grant

2005-11-01

435

Ip micro-mobility protocols  

Microsoft Academic Search

Abstract: The IETF Mobile IP Working Group is discussing a number of enhancements to the base protocol to reduce the latency, packet loss... In this article, we discuss a number of "micro-mobility protocols" that extend Mobile IP with fast handoff and paging capabilities. The aim of this article is not to provide an exhaustive survey of these protocols. Rather, we

A. T. Campbell; J. Gomez

2001-01-01

436

Building a MicroSociety  

ERIC Educational Resources Information Center

Talbot Hill Elementary School in Renton, Washington, uses the MicroSociety model to make learning relevant and engaging for its diverse student population. Three afternoons each week, every student participates in a for-profit business, a governmental agency, or a nonprofit organization. Teachers prepare students to participate in the school's…

Dunton, Sheryl

2006-01-01

437

Micro-machined resonator oscillator  

DOEpatents

A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.

Koehler, Dale R. (Albuquerque, NM); Sniegowski, Jeffry J. (Albuquerque, NM); Bivens, Hugh M. (Albuquerque, NM); Wessendorf, Kurt O. (Albuquerque, NM)

1994-01-01

438

Micro-machined resonator oscillator  

DOEpatents

A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a telemetered sensor beacon'' that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20--100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available. 21 figs.

Koehler, D.R.; Sniegowski, J.J.; Bivens, H.M.; Wessendorf, K.O.

1994-08-16

439

Dimensional Micro and Nano Metrology  

Microsoft Academic Search

The need for dimensional micro and nano metrology is evident, and as critical dimensions are scaled down and geometrical complexity of objects is increased, the available technologies appear not sufficient. Major research and development efforts have to be undertaken in order to answer these challenges. The developments have to include new measuring principles and instrumentation, tolerancing rules and procedures as

H. N. Hansen; K. Carneiro; H. Haitjema; L. De Chiffre

2006-01-01

440

Seed microRNA Research  

Technology Transfer Automated Retrieval System (TEKTRAN)

MicroRNAs (miRNAs) are key regulatory molecules that play critical roles in gene expression. The biological functions of miRNAs are important for developmental processes in plants and animals. Little is known about the functions of miRNAs in seeds. To gain a better understand-ing of the regulation o...

441

Micro-Based Genlocking Systems.  

ERIC Educational Resources Information Center

Presents a selective survey of micro-based genlocking systems currently on the market including those systems with open and closed architecture; examines the number and diversity of uses for this hybrid medium, which synchronizes video signals with computer-generated text and graphics; and discusses the role of cause and effect in innovation.

Hurly, Paul

1986-01-01

442

Micro-Encapsulation of Probiotics  

NASA Astrophysics Data System (ADS)

Micro-encapsulation is defined as the technology for packaging with the help of protective membranes particles of finely ground solids, droplets of liquids or gaseous materials in small capsules that release their contents at controlled rates over prolonged periods of time under the influences of specific conditions (Boh, 2007). The material encapsulating the core is referred to as coating or shell.

Meiners, Jean-Antoine

443

Parallel Coupled Micro-Macro Actuators  

E-print Network

This thesis presents a new actuator system consisting of a micro-actuator and a macro-actuator coupled in parallel via a compliant transmission. The system is called the Parallel Coupled Micro-Macro Actuator, or PaCMMA. ...

Morrell, John Bryant

1996-01-01

444

Real time monitoring of temperature of a micro proton exchange membrane fuel cell.  

PubMed

Silicon micro-hole arrays (Si-MHA) were fabricated as a gas diffusion layer (GDL) in a micro fuel cell using the micro-electro-mechanical-systems (MEMS) fabrication technique. The resistance temperature detector (RTD) sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10(-3)/°C, respectively. The best experimental performance was 9.37 mW/cm(2) at an H(2)/O(2) dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C. PMID:22573963

Lee, Chi-Yuan; Lee, Shuo-Jen; Hu, Yuh-Chung; Shih, Wen-Pin; Fan, Wei-Yuan; Chuang, Chih-Wei

2009-01-01

445

Unique properties of 30-{micro}m particles as the catalyst of fluidized-bed reactors  

SciTech Connect

The collapse properties of three kinds of fine particles (19, 30, and 59 {micro}m) are studied with a new type of bed-collapse technique, isolated dilute-phase bed collapse, to determine the dense-phase properties under high superficial gas velocities. The properties of the emulsion and bubble phases are investigated by a video camera. The influence of particle size on particle collapse properties is also discussed. When gas velocities are high the 30-{micro}m particles take the longest to collapse, have the smallest emulsion density, and have largest bubble volumetric fraction. These observations indicate that the 30-{micro}m particles have a property that the others lack.

Yang, G.; Wei, F.; Jin, Y.; Yu, Z.; Wang, Y. [Tsinghua Univ., Beijing (China). Dept. of Chemical Engineering] [Tsinghua Univ., Beijing (China). Dept. of Chemical Engineering

1997-05-01

446

Micro-reactors for characterization of nanostructure-based sensors.  

PubMed

Fabrication and testing of micro-reactors for the characterization of nanosensors is presented in this work. The reactors have a small volume (100 ?l) and are equipped with gas input/output channels. They were machined from a single piece of kovar in order to avoid leaks in the system due to additional welding. The contact pins were electrically insulated from the body of the reactor using a borosilicate sealing glass and the reactor was hermetically sealed using a lid and an elastomeric o-ring. One of the advantages of the reactor lies in its simple assembly and ease of use with any vacuum/gas system, allowing the connection of more than one device. Moreover, the lid can be modified in order to fit a window for in situ optical characterization. In order to prove its versatility, carbon nanotube-based sensors were tested using this micro-reactor. The devices were fabricated by depositing carbon nanotubes over 1 ?m thick gold electrodes patterned onto Si/SiO(2) substrates. The sensors were tested using oxygen and nitrogen atmospheres, in the pressure range between 10(-5) and 10(-1) mbar. The small chamber volume allowed the measurement of fast sensor characteristic times, with the sensors showing good sensitivity towards gas and pressure as well as high reproducibility. PMID:22667654

Savu, R; Silveira, J V; Flacker, A; Vaz, A R; Joanni, E; Pinto, A C; Gobbi, A L; Santos, T E A; Rotondaro, A L P; Moshkalev, S A

2012-05-01

447

Microfabricated thermal conductivity detector for the micro-ChemLab.  

SciTech Connect

This work describes the design, computational prototyping, fabrication, and characterization of a microfabricated thermal conductivity detector ({mu}TCD) to analyze the effluent from a micro-gas chromatograph column ({mu}GC) and to complement the detection efficacy of a surface acoustic wave detector in the micro-ChemLab{trademark} system. To maximize the detection sensitivity, we designed a four-filament Wheatstone bridge circuit where the resistors are suspended by a thin silicon nitride membrane in pyramidal or trapezoidal shaped flow cells. The geometry optimization was carried out by simulation of the heat transfer in the devices, utilizing a boundary element algorithm. Within microfabrication constraints, we determined and fabricated nine sensitivity-optimized geometries of the {mu}TCD. The nine optimal geometries were tested with two different flow patterns. We demonstrated that the perpendicular flow, where the gas directly impinged upon the membrane, yielded a sensitivity that is three times greater than the parallel flow, where the gas passed over the membrane. The functionality of the {mu}TCD was validated with the theoretical prediction and showed a consistent linear response to effluent concentrations, with a detection sensitivity of 1 ppm, utilizing less than 1 W of power.

Chang, Jane P. (University of California, Los Angeles, CA); Cruz, Dolores Y. (University of California, Los Angeles, CA); Blain, Matthew Glenn; Manginell, Ronald Paul; Showalter, Steven Kedrick; Gelbard, Fred

2005-08-01

448

Micro-rheometry Our goal is to develop micro and nano-fluidic tools that  

E-print Network

Micro-rheometry POLYMERS Our goal is to develop micro and nano-fluidic tools that measure are difficult and expensive to produce. Objective Impact and Customers · Our micro and nano-fluidic devices samples of limited quantity. · We have developed a micro-fluidic platform with unprecedented control over

449

EE 337 Engineering micro and nano-systems EE 337 Engineering micro and nano-systems  

E-print Network

EE 337 Engineering micro and nano-systems EE 337 Engineering micro and nano-systems A.F.J. Levi as an introduction to micro and nano-technology, methods to control and exploit the new degrees of freedom delivered by nano-science, and the integration of micro and nano-technology into systems. It is a hands

Levi, Anthony F. J.

450

Micro-speculation, Micro-sandboxing, and Self-Correcting Assertions: Support for Self-Healing  

E-print Network

Micro-speculation, Micro-sandboxing, and Self-Correcting Assertions: Support for Self the notion of Self-Healing Software by introducing three novel tech- niques: micro-sandboxing, micro-level framework to support Application Communities. ii #12;Contents 1 Introduction 1 1.1 Proposal Organization

451

A novel approach for batch production of micro holes by micro EDM  

Microsoft Academic Search

The paper proposed a novel approach of effective production of mass micro holes. A set of micro w-EDM mechanism is designed and mounted on the developed tabletop precision machine tool. The tension of micro wire is precisely controlled by magnetic force. In addition, the micro vibrations of the wire during discharging are effectively suppressed by the developed vibration suppression system.

S. T. Chen; Y. S. Liao

452

1998 Tutorial on Micro Mechatronics and Micro Robotics Powering 3 Dimensional Microrobots: Power Density Limitations \\Lambda  

E-print Network

of these actuators for use in micro­robotic systems. The most important consideration for micro mobile robots significant problem with micro­actuators for robotics is the need for efficient transmissions to obtain large varieties of micro­actuators based on elec­ trostatic and electomagnetic principles have been de­ veloped

Fearing, Ron

453

Externally-resonated linear micro vibromotor for micro Kazuhiro Saitoua and Soungjin J. Wou  

E-print Network

of micro-scale components is presented where a micro linear slider is actuated by vibratory impacts exerted such as electrostatic comb actuators as reported previously.1,2 This selective resonance of the micro cantilever in Figure 2, where a on-substrate linear actuator pushes a inaccurately positioned micro component (e

Saitou, Kazuhiro "Kazu"

454

Micro-manipulation using rotational fluid flows induced by remote magnetic micro-manipulators  

E-print Network

Micro-manipulation using rotational fluid flows induced by remote magnetic micro-manipulators Zhou prior permission of the author and the American Institute of Physics. #12;Micro-manipulation using rotational fluid flows induced by remote magnetic micro-manipulators Zhou Ye,a) Eric Diller,b) and Metin

Sitti, Metin

455

MEMS compatible illumination and imaging micro-optical systems  

Microsoft Academic Search

The development of new MOEMS demands for cooperation between researchers in micromechanics, optoelectronics and microoptics at a very early state. Additionally, microoptical technologies being compatible with structured silicon have to be developed. The microoptical technologies used for two silicon based microsystems are described in the paper. First, a very small scanning laser projector with a volume of less than 2

A. Bräuer; P. Dannberg; J. Duparré; B. Höfer; P. Schreiber; M. Scholles