These are representative sample records from related to your search topic.
For comprehensive and current results, perform a real-time search at

A Silicon-Based Micro Gas Turbine Engine for Power Generation  

E-print Network

This paper reports on our research in developing a micro power generation system based on gas turbine engine and piezoelectric converter. The micro gas turbine engine consists of a micro combustor, a turbine and a centrifugal compressor. Comprehensive simulation has been implemented to optimal the component design. We have successfully demonstrated a silicon-based micro combustor, which consists of seven layers of silicon structures. A hairpin-shaped design is applied to the fuel/air recirculation channel. The micro combustor can sustain a stable combustion with an exit temperature as high as 1600 K. We have also successfully developed a micro turbine device, which is equipped with enhanced micro air-bearings and driven by compressed air. A rotation speed of 15,000 rpm has been demonstrated during lab test. In this paper, we will introduce our research results major in the development of micro combustor and micro turbine test device.

Shan, X -C; Maeda, R; Sun, Y F; Wu, M; Hua, J S




E-print Network

Roter Blades Turbine NGV Exhaust Nozzle Fig. 2 Implementation of the micro gas turbine engineStresa, Italy, 26-28 April 2006 A SILICON-BASED MICRO GAS TURBINE ENGINE FOR POWER GENERATION X. C in developing a micro power generation system based on gas turbine engine and piezoelectric converter. The micro

Paris-Sud XI, Université de


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

Microsoft Academic Search

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

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



Study of energy transfer in silicon-based micro-ring resonators  

NASA Astrophysics Data System (ADS)

Physical model, time-domain model, transmission spectra and energy transfer diagram of silicon-based micro-ring resonators based on the parallel waveguide structure are analyzed in this paper, in which transmission spectrum is obtained by Matlab, and the energy transfer process is analyzed by Rsoft. According to the analyses of the models and results, the energy transfer process in this type of resonator is clear to a great extent. The experimental results show that when the input signal is stable, the energy of the micro-ring resonator and the drop port tends to be steady after the input optical signal is coupled in the coupling region, which proves that the silicon-based micro-ring resonators can select specific optical signal if the input optical signal satisfies the resonance condition. However, if the resonance condition is not met, filtering function, optical switch function and signal selection function can be realized. Therefore, the analysis and simulation of energy transfer in silicon-based micro-ring resonators can not only enrich the silicon micro-ring resonator theory, but also provide new theoretical basis and method for the design and optimization of existing optoelectronic devices.

Li, Xin-juan; Wu, Rong; Hu, Yu-feng; Hu, Li-xin; Guo, Jian-cheng



Surface roughness of (110) orientation silicon based micro heat exchanger channel  

Microsoft Academic Search

Using microfabrication techniques, we can etch large numbers of small size, high precision channels into (110)-oriented silicon with KOH to construct extremely efficient micro heat exchanger. In this paper, the micro channel surface roughness are investigated as a function of the solution temperature and concentration. The results presented here are intended to provide help in the selection of etch parameter

Shung-Wen Kang; Jong-Shun Chen; Jong-Yun Hung



Porous silicon based orientation independent, self-priming micro direct ethanol fuel cell  

Microsoft Academic Search

The design, fabrication and testing of an orientation independent, self-priming micro direct ethanol fuel cell (DEFC) is presented. The electrodes of the fuel cell are fabricated using macro-porous silicon technology. The capillary force generated by the pores has the ability of “wicking” the fuel towards the electrode irrespective of the orientation of the cell, resulting in a uniform and regulated

Shyam Aravamudhan; Abdur Rub Abdur Rahman; Shekhar Bhansali



Survivability of a silicon-based microelectronic gas-detector structure for high-temperature flow applications  

Microsoft Academic Search

This investigation addresses the important question of whether or not silicon-based micromachined chemical sensors are a viable option for gas sensing in harsh, high-temperature flow applications such as automotive exhaust. Data are presented on the thermal and mechanical stability and long-term functionality of micromachined silicon devices containing ultra-thin Pt\\/TiOx films supported on a heated multilayer silicon oxide\\/silicon nitride membrane. These

Sanjay V Patel; Michael DiBattista; John L Gland; Johannes W Schwank



Safe gas handling and system design for the large scale production of amorphous silicon based solar cells  

NASA Astrophysics Data System (ADS)

Solarex is one of the leaders in amorphous silicon based photovoltaic production and research. The large scale production environment presents unique safety concerns related to the quantity of dangerous materials as well as the number of personnel handling these materials. The safety measures explored by this work include gas detection systems, training, and failure resistant gas handling systems. Our experiences with flow restricting orifices in the CGA connections and the use of steel cylinders is reviewed. The hazards and efficiency of wet scrubbers for silane exhausts are examined. We have found it to be useful to provide the scrubbler with temperature alarms.

Fortmann, C. M.; Farley, M. V.; Smoot, M. A.; Fieselmann, B. F.



Porous silicon based micro-opto-electro-mechanical-systems (MOEMS) components for free space optical interconnects  

NASA Astrophysics Data System (ADS)

One of the major challenges confronting the current integrated circuits (IC) industry is the metal "interconnect bottleneck". To overcome this obstacle, free space optical interconnects (FSOIs) can be used to address the demand for high speed data transmission, multi-functionality and multi-dimensional integration for the next generation IC. One of the crucial elements in FSOIs system is to develop a high performance and flexible optical network to transform the incoming optical signal into a distributed set of optical signals whose direction, alignment and power can be independently controlled. Among all the optical materials for the realization of FSOI components, porous silicon (PSi) is one of the most promising candidates because of its unique optical properties, flexible fabrication methods and integration with conventional IC material sets. PSi-based Distributed Bragg Reflector (DBR) and Fabry-Perot (F-P) structures with unique optical properties are realized by electrochemical etching of silicon. By incorporating PSi optical structures with Micro-Opto-Electro-Mechanical-Systems (MOEMS), several components required for FSOI have been developed. The first type of component is the out-of-plane freestanding optical switch. Implementing a PSi DBR structure as an optically active region, the device can realize channel selection by changing the tilting angle of the micromirror supported by the thermal bimorph actuator. All the fabricated optical switches have reached kHz working frequency and life time of millions of cycles. The second type of component is the in-plane tunable optical filter. By introducing PSi F-P structure into the in-plane PSi film, a thermally tunable optical filter with a sensitivity of 7.9nm/V has been realized for add/drop optical signal selection. Also, for the first time, a new type of PSi based reconfigurable diffractive optical element (DOE) has been developed. By using patterned photoresist as a protective mask for electrochemical etching, the freestanding PSi-based MOEMS DOE has been created as a beam splitter to redistribute the incoming optical signal with onto desired detector arrays. All the developed devices are realized in array fashion and can be addressed and controlled individually. The combination of PSi and MOEMS opens the door for a new generation of silicon compatible optical interconnects.

Song, Da


Design, fabrication, and characterization of a planar, silicon-based, monolithically integrated micro laminar flow fuel cell with a bridge-shaped microchannel cross-section  

NASA Astrophysics Data System (ADS)

We report the fabrication of a planar, silicon-based, monolithically integrated micro laminar flow fuel cell (?LFFC) using standard MEMS and IC-compatible fabrication technologies. The ?LFFC operates with acid supported solutions of formic acid and potassium permanganate, as a fuel and oxidant respectively. The micro-fuel cell design features two in-plane anodic and cathodic microchannels connected via a bridge to confine the diffusive liquid-liquid interface away from the electrode areas and to minimize crossover. Palladium high-active-surface-area catalyst was selectively integrated into the anodic microchannel by electrodeposition, whereas no catalyst was required in the cathodic microchannel. A three-dimensional (3D) diffusion-convection model was developed to study the behavior of the diffusion zone and to extract appropriate cell-design parameters and operating conditions. Experimentally, we observed peak power densities as high as 26 mW cm-2 when operating single cells at a flow rate of 60 ?L min-1 at room temperature. The miniature membraneless fuel cell design presented herein offers potential for on-chip power generation, which has long been prohibited by integration complexities associated with the membrane.

López-Montesinos, P. O.; Yossakda, N.; Schmidt, A.; Brushett, F. R.; Pelton, W. E.; Kenis, P. J. A.



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



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-



Capacitive blade tip clearance measurements for a micro gas turbine  

Microsoft Academic Search

The efficiency of a gas turbine has an inverse relationship with the clearance between the rotor blades and the casing. Recent efforts in miniaturization of micro gas turbine engines have created new challenge in tip clearance measurement. This paper describes the development of a tip clearance measurement system, based on capacitive measurement for a palm-top micro gas turbine engine. The

Tibor Fabian; Sangkyun Kang; F. Prinz



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



Development of a MEMS-based micro combustor for a micro gas turbine engine  

NASA Astrophysics Data System (ADS)

This paper reports on design, fabrication and characterisation of a MEMS-based micro combustor for micro power generation systems. The first micro combustor implemented was a static gas turbine engine. The micro combustor was composed of seven silicon wafers and fabricated using deep reactive ion etching (DRIE). The size of the prototype was 21mmx21mmx4.4 mm. The combustor was assembled, aligned, ignited and tested under a fixture jig. The temperature near the exit of the combustor reached 1550 K, when the mass flow rate and fuel/air equivalence ratio were 0.06 g/sec and 0.8, respectively.

Shan, Xue Chuan; Jin, Yu F.; Wang, Zhen F.; Wong, Chee Khuen; Murakoshi, Y.; Maeda, Ryutaro



Gas detection with micro- and nano-engineered optical fibers  

NASA Astrophysics Data System (ADS)

This paper overviews recent development in gas detection with micro- and nano-engineered optical fibers, including hollow-core fibers, suspended-core fibers, tapered optical micro/nano fibers, and fiber-tip micro-cavities. Both direct absorption and photoacoustic spectroscopy based detection schemes are discussed. Emphasis is placed on post-processing stock optical fibers to achieve better system performance. Our recent demonstration of distributed methane detection with a ˜75-m long of hollow-core photonic bandgap fiber is also reported.

Jin, W.; Ho, H. L.; Cao, Y. C.; Ju, J.; Qi, L. F.



Design and prototyping of micro centrifugal compressor for ultra micro gas turbine  

Microsoft Academic Search

In order to establish the design methodology of an ultra micro centrifugal compressor, which is the most important component\\u000a of an ultra micro gas turbine unit, a 10 times size of the final target compressor (impeller outer diameter 40 mm, corrected\\u000a rotational speed 220,000 r\\/min) was designed. The problems to be solved for downsizing were examined and a 2-dimensional impeller

Shimpei Mizuki; Toshiyuki Hirano; Yoshiyuki Koizumi; Gaku Minorikawa; Hoshio Tsujita; Mitsuo Iwahara; Ronglei Gu; Yutaka Ohta; Eisuke Outa



Design of micro-sensor-array detector for toxic gas  

NASA Astrophysics Data System (ADS)

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

Liao, Hai-yang; Tian, Peng




Microsoft Academic Search

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

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


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.



Stirling engines for gas fired micro-cogen and cooling  

SciTech Connect

This paper describes the design and performance of free-piston Stirling engine-alternators particularly suited for use as natural gas fired micro-cogen and cooling devices. Stirling based cogen systems offer significant potential advantages over internal combustion engines in efficiency, to maintain higher efficiencies at lower power levels than than combustion engines significantly expands the potential for micro-cogen. System cost reduction and electric prices higher than the U.S. national average will have a far greater effect on commercial success than any further increase in Stirling engine efficiency. There exist niche markets where Stirling engine efficiency. There exist niche markets where Stirling based cogen systems are competitive. Machines of this design are being considered for production in the near future as gas-fired units for combined heat and power in sufficiently large quantities to assure competitive prices for the final unit.

Lane, N.W.; Beale, W.T. [Sunpower, Inc., Athens, OH (United States)




Microsoft Academic Search

Micro-turbo chargers were manufactured and operated to test the compressor of a palmtop gas turbine generator at low temperature (< 100 °C). Impellers are 10 mm in diameter and have 3-dimensional blades machined using a 5-axis NC milling machine. The performance of the compressor were measured at 50 % (435,000 rpm) and 60 % (530,000 rpm) of the rated rotational

Shuji Tanaka; Kousuke Isomura; Shin-ichi Togo; Kousuke Hikichi; Satoshi Goto; Masayoshi Esashi


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 ( 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



Design and prototyping of micro centrifugal compressor for ultra micro gas turbine  

NASA Astrophysics Data System (ADS)

In order to establish the design methodology of an ultra micro centrifugal compressor, which is the most important component of an ultra micro gas turbine unit, a 10 times size of the final target compressor (impeller outer diameter 40 mm, corrected rotational speed 220,000 r/min) was designed. The problems to be solved for downsizing were examined and a 2-dimensional impeller was chosen as the first model due to its productivity. The conventional 1D prediction method and CFD were used. The prototyped compressor was tested by using cold air at the reduced speed of 110,000 r/min. Following to the 10 times model, a 5 times size of the final target model having fully 3-dimensional shape (impeller outer diameter 20mm, corrected rotational speed 500,000 r/min) was designed and tested by using hot gas at the reduced speed of 250,000 r/min.

Mizuki, Shimpei; Hirano, Toshiyuki; Koizumi, Yoshiyuki; Minorikawa, Gaku; Tsujita, Hoshio; Iwahara, Mitsuo; Gu, Ronglei; Ohta, Yutaka; Outa, Eisuke



Silicon-Based Optoelectronics: Progress and Challenges  

Microsoft Academic Search

We review the status of silicon-based optoelectronics with emphasis on light emitting diodes. Erbium-doped Si, por-Si and silicon-based superlattices and nanos- tructures are discussed. The origin behind light emission in silicon with feature sizes below about 60 nm still remains poorly understood. The development of Si-based optoelectronics has at least two driving forces: the nat- ural scientic endeavour to understand

Tamim P. SIDIKI; M. Sotomayor TORRES


Process for strengthening silicon based ceramics  

SciTech Connect

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

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



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



Applied modelling for bio and lean gas fired micro gas turbines  

Microsoft Academic Search

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

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



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



Data Processing from Micro-Plasma Gas Analytical Sensor  

NASA Astrophysics Data System (ADS)

Theoretical consideration of signal formation at micro-plasma gas analyzer based on Collisional Electron Spectroscopy (CES) and experimental results on CES sensor are presented. It is demonstrated that a diffusion path confinement for characteristic electrons provides a possibility to measure electrons energy distribution function (EEDF) and to find characteristic spectra of species at high (up to atmospheric) gas pressure. Simple micro-plasma CES sensor of two plane parallel electrode configuration with current-voltage measurement in afterglow discharge may be operated in two possible modes. The first mode presumes application of classic 2-nd derivative of current-voltage curve to select characteristic peaks in electron energy spectra of the species to be detected. In the case of a deeper collisional dissipation of characteristic peaks, a 3-rd derivative may be used. Said derivatives were obtained by differentiating of a spline providing least-squares approximation of current-voltage curve. Model and experimental electron energy spectra of pair He metastables collisions in dependence of inter-electrode gap are discussed.

Mustafaev, Alexander; Tsyganov, Alexander



Integrated Micro-Machined Hydrogen Gas Sensor. Final Report  

SciTech Connect

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

Frank DiMeo, Jr.



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"


Micro gas analyzers for environmental and medical applications.  


In this review, novel microsystems and microdevices to measure gaseous species for environmental analysis and medical diagnostics are described. Miniaturization of analyzers makes field measurements affordable. As well, high sensitivity and good time resolution can be achieved by miniaturization. Some such devices have already been successfully applied to real environmental analyses. Mobile monitoring is available with the use of micro gas analyzers to investigate the natural environment, air pollution and to detect nerve or explosive gases released accidentally or through terrorist activities. Miniature devices are also attractive for medical analyses. Gases produced from the human body reflect gases contained in the blood and certain metabolic conditions. Noninvasive monitoring using miniature devices is available in hospitals and in a patient's home. Many investigations have been conducted using wet and dry chemistry methods for both applications. Instruments employing wet chemistries, which comprise liquid droplets, liquid film, miniature diffusion scrubbers, and microfluidic devices have been studied. Among the instruments using dry methods, miniature samplers, portable gas chromatographs, and microfabricated gas chromatographs have all been investigated. These instruments are expected to usher in a new era of environmental monitoring and will find uses in many medical applications. PMID:18558107

Ohira, Shin-Ichi; Toda, Kei



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




E-print Network

23 Abstract: This paper presents the optimization of a micro gas preconcentrator based on a micro gas chromatography (-GC)31 [6, 7, 8, 9, 10] , ion mobility spectrometry (IMS) and electronic nose (E.S. Environmental Protection44 Agency) to 500ppb in ambient air and 5ppb in drinking water . While in France

Paris-Sud XI, Université de



Microsoft Academic Search

MIT is developing micro-electro-mechanical systems (MEMS)-based gas turbine engines, turbogenerators, and rocket engines. Fabricated in large numbers in parallel using semicon- ductor manufacturing techniques, these engines-on-a-chip are based on micro-high speed rotating machinery with power den- sities approaching those of their more familiar, full-sized breth- ren. The micro-gas turbine is a 2 cm diameter by 3 mm thick Si or

Alan H. Epstein; Stuart A. Jacobson; Jon M. Protz; Luc G. Frechette



Silicon-based thermal comfort sensing device  

Microsoft Academic Search

Based on a thermal mannequin model, we have designed and fabricated a silicon-based TCS (thermal comfort sensing) devices. The thermal comfort sensor appears to be highly sensitive to air flow and fairly sensitive to radiation, but is quite insensitive to humidity. A PMV (predicted mean vote) indicator has been fabricated using the TCS device and the experimental results in a

Jong-Uk Bu; Tae-Yoon Kim; In-Sik Kim; Young-Sam Jun; Young-Cho Shim; Sung-Tae Kim



Nano and micro stripe based metal oxide thin film gas sensor  

Microsoft Academic Search

Functional metal oxide micro and nanostructures for the detection of gas are a very promising candidate for future gas-sensors. Due to reduced size and thus an increased surface to volume ratio nanosized sensitive structures offer a high potential for increasing sensitivity. A top down sputtering approach for gas sensors with nano-sized gas sensitive metal oxide areas is presented. Oxidised silicon

Stefan Palzer; Emmanuel Moretton; Francisco Hernandez Ramirez; Albert Romano-Rodriguez; Juan Ramon Morante; Jürgen Wöllenstein



Development of Pressure-Sensitive Channel Chip for Micro Gas Flows  

NASA Astrophysics Data System (ADS)

Optical measurement techniques are useful for experimental studies on micro gas flows, which enable us to non-intrusively measure the flows with a high spatial resolution. The pressure-sensitive paint (PSP) technique, which is based on the emission of photons from luminophore, is a potential diagnostic tool for pressure measurement of micro gas flows. However, measurements by conventional PSPs are limited to the sub-millimeter order spatial resolution of ca. 200 ?m, indicating the difficulty of the micro scale measurements. The present study proposes pressure-sensitive channel chip (PSCC) which is a micro channel with the capability of measuring pressure. We focused on the poly (dimethylsiloxane) (PDMS) micro-molding technique, which is one of the most popular techniques to fabricate a micro channel easily. Moreover, PDMS is a polymer used as a binder in PSP because of high optical transparency, gas permeability, and gas diffusivity. Thus, we developed a micro channel by the PDMS micro-molding technique with mixing a pressure-sensitive luminophore into PDMS: i.e. a micro channel fabricated by PSP, which is named PSCC. A flow through a micro converging-diverging nozzle with the throat width of 120 ?m was demonstrated. The pressure distribution on the nozzle surface was successfully obtained by PSCC.

Matsuda, Yu; Yamaguchi, Hiroki; Niimi, Tomohide



Impurity analyses of high-purity carbon monoxide gas using micro gas chromatography for development as a certified reference material.  


High-purity carbon monoxide (CO) gas as a certified reference material (CRM) was analyzed using a micro gas chromatograph (micro-GC) with a micro thermal conductivity detector. The main reason to select the micro-GC was its compact size to provide a safe experimental environment. Thus, both the CO gas cylinder and the micro-GC were placed inside a draft shield with a limited small space. Peaks of several impurities were found in chromatograms of the micro-GC. The main impurities in the CO gas were helium, hydrogen, oxygen, nitrogen and carbon dioxide. It was found that helium was the impurity of the highest concentration. High-accuracy calibration gas mixtures were used to construct calibration lines for the micro-GC. The mixtures were precisely prepared by the gravimetric blending method. Calibration lines had enough linearity and accuracy for quantitative analyses of the impurities. The values of detection limit of the impurities were 0.7-4?mol/mol. The purity of the high-purity CO gas was around 99.996%, which was the value estimated from the sum of the concentrations of the impurities. PMID:23415447

Matsumoto, Nobuhiro; Watanabe, Takuro; Kato, Kenji



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



Micro-miniature gas chromatograph column disposed in silicon wafers  


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

Yu, Conrad M. (Antioch, CA)



Investigation of H2/CH4 mixed gas plasma post-etching process for ZnO:B front contacts grown by LP-MOCVD method in silicon-based thin-film solar cells  

NASA Astrophysics Data System (ADS)

A new plasma post-etching method, H2/CH4 mixed gas plasma, is introduced to modify ZnO:B films grown by LP-MOCVD technique, successfully relaxing the double trade-offs, i.e., transparency/conductivity trade-off and surface texture/Voc and FF trade-off. To deeply evaluate the post-etching process, optical emission spectroscopy technique is applied to diagnose the plasma condition. Upon different etching power, three distinct possible etching mechanisms are identified by analyzing the evolution of H?*, H?*, CH* emission species in the plasma space. It is demonstrated that H?* and CH* species are responsible for the physical etching process and chemical etching process, respectively, from which a new “soft” surface morphology is formed with a combination of micro- and nano-sized texture. Additionally, H?* species can bond with ZnO and also passivate the grains boundaries, thereby making both the carrier concentration and hall mobility increase. This process is defined as chemical bonding process. Finally, pin-type a-Si:H single-junction solar cells with an optimized device structure is grown on the etched ZnO:B substrate. The corresponding electrical parameters, such as Jsc, Voc and FF, are simultaneously improved compared with the solar cell deposited on as-grown ZnO:B substrate with the same fabrication process. As a consequence, a noteworthy 8.85% conversion-efficiency is achieved with an absorber layer thickness only 160 nm.

Wang, Li; Zhang, Xiaodan; Zhao, Ying; Yamada, Takuto; Naito, Yusuke



Silicon-Based Multiple Microsensors for Sensing Carbon Dioxide, Humidity and Temperature  

Microsoft Academic Search

A silicon based multiple microsensor for sensing carbon dioxide, humidity and temperature has been investigated. The carbon dioxide microsensor was designed based on gas permeable membrane and ion-sensing field effect transistor structures. The humidity microsensor was designed based on metal-oxide -semiconductor transistor with a polyimide sensing film. The temperature microsensor was also designed based on diode -sensing structure. The multiple

Hsing-Cheng Chang



Progress in amorphous silicon based multijunction modules  

SciTech Connect

Advances in amorphous silicon based alloys and device structure have led to the demonstration of 10.5% initial efficiency and 9.1% stabilized efficiency on 1 Ft{sup 2} a-Si/a-SiGe tandem junction module. Scale-up to 4 Ft{sup 2} in pilot production has resulted in the best initial efficiency of 9.75% as measured by NREL, which should result in a stabilized efficiency over 8%. Presently the 4 Ft{sup 2} modules have an average initial efficiency of 8.75% and a stabilized average efficiency of about 7.5%, as measured by Solarex.

Arya, R.R.; Oswald, R.S.; Li, Y.M. [Solarex Corp., Newtown, PA (United States). Thin-Film Div.] [and others



Polymeric membranes for silicon based (bio)sensors.  


During the last decade, chemical and biochemical sensor research has benefited from the availability of new technologies and materials. New embodiments of classical devices have resulted from the use of e.g., solid state technology for the realization of the transducers. In this paper we describe several examples of membrane deposition techniques used in connection with planar, silicon based electrochemical transducers. Casting and electrochemical deposition of glucose oxidase containing membranes are described for the fabrication of glucose enzyme electrodes. Photolithographic patterning of polyacrylamide hydrogel and of siloxane based gas permeable membrane is used for the realization of an amperometric oxygen sensor and an ISFET-based pCO2 device. The last example is that of a free-chlorine sensor for which the photolithographic patterning of the polyHEMA hydrogel layer is described. PMID:1432578

Arquint, P; van den Berg, A; Strike, D J; de Rooij, N F; Koudelka-Hep, M



New approach to micro-joining by hot gas stream  

Microsoft Academic Search

The design and the realization of a novel approach in joining micro-parts of dimensions up to 300?m in functional units (Hybrid MOEMS) using hot air stream is presented in this paper. A single-mode optical fiber used exemplary as a micro-part in first phase of experiments, has been positioned in mechanically made V-grooves and firmly joined to them by softening adhesives’

Daniela Andrijasevic; Ioanna Giouroudi; Walter Smetana; Stefan Boehm; Johann Zehetner; Werner Brenner



Design and characterization of a silicon base micro heat exchanger  

Microsoft Academic Search

The need for greater computational power and speed in electronic devices has led to increase the circuit density. The large density is associated with larger amounts of heat generation. Most of the time, the free convection is unable to relief the heat from the components. Forced convection in conjunction with enhanced shape of the dissipation radiators are used to accelerate

S. Sadri-Lonbani; M. Kahrizi; I. Stiharu



Micro-and nanostructured silicon-based superomniphobic surfaces.  


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



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

E-print Network

: an X-ray generator for radiation hardness studies, an ultra clean custom stainless steel monitored gas1 Purdue Micro Pattern Gas Detector R&D Personnel: Miyamoto, Shipsey, Guirl (undergrad), Kane types of detector with improved signal to noise performance. The Micro Pattern Gas Detector (MPGD


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.



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.



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



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


An Aging Study of a Gas Electron Multiplier with Micro-Strip Gas Chamber Readout J. Miyamoto and I.P.J Shipsey  

E-print Network

counters has been revolutionized by the introduction of micro-electronic fabrication techniques to define materials and lead to partial detector failure. A large scale beam test conducted at CERN in 1997An Aging Study of a Gas Electron Multiplier with Micro-Strip Gas Chamber Readout J. Miyamoto and I


Modeling and Control of a Gas Micro Turbine Generator by Using a Causal Ordering Graph  

Microsoft Academic Search

A dynamic model of a micro gas turbine generator by using a causal ordering graph is proposed in this paper. This particular graphical representation is used to highlight the causal order of all mathematical equations. It is shown that the obtained model is interesting for developing a Matlab Simulink model and for designing the control strategy. In order to control

P. Li; P. Degobert; B. Francois; B. Robyns



Modeling Goals and Functions of Micro Gas Turbine System by Multilevel Flow Models  

Microsoft Academic Search

Semiotic analysis is often used for describing the inter-relationship of structure, function and behavior of any artifacts as the means for designing various computerized tools for machine diagnosis and operation procedure. In this study, a graphical method called Multilevel Flow Models (MFM) is applied for supporting machine maintenance work of commercially available Micro Gas Turbine System (MGTS), to describe and

Yangping Zhou; Hidekazu Yoshikawa; Wei Wu; Ming Yang; Hirotake Ishii


Preparation of ZnO thin films using MOCVD technique with D 2O\\/H 2O gas mixture for use as TCO in silicon-based thin film solar cells  

Microsoft Academic Search

Zinc oxide (ZnO) thin films have been successfully grown by metal organic chemical vapor deposition (MOCVD) technique using deuterium water (D2O) and water (H2O) mixtures as oxidants for diethylzinc (DEZ). B2H6 was also employed as a dopant gas. It was found that the crystal orientation of ZnO films strongly depends on D2O\\/H2O ratio. As a result, the surface morphology of

Aswin Hongsingthong; Ihsanul Afdi Yunaz; Shinsuke Miyajima; Makoto Konagai



Volatile Reaction Products From Silicon-Based Ceramics in Combustion Environments Identified  

NASA Technical Reports Server (NTRS)

Silicon-based ceramics and composites are prime candidates for use as components in the hot sections of advanced aircraft engines. These materials must have long-term durability in the combustion environment. Because water vapor is always present as a major product of combustion in the engine environment, its effect on the durability of silicon-based ceramics must be understood. In combustion environments, silicon-based ceramics react with water vapor to form a surface silica (SiO2) scale. This SiO2 scale, in turn, has been found to react with water vapor to form volatile hydroxides. Studies to date have focused on how water vapor reacts with high-purity silicon carbide (SiC) and SiO2 in model combustion environments. Because the combustion environment in advanced aircraft engines is expected to contain about 10-percent water vapor at 10-atm total pressure, the durability of SiC and SiO2 in gas mixtures containing 0.1- to 1-atm water vapor is of interest. The reactions of SiC and SiO2 with water vapor were monitored by measuring weight changes of sample coupons in a 0.5-atm water vapor/0.5-atm oxygen gas mixture with thermogravimetric analysis.

Opila, Elizabeth J.



Silicon rich nitride for silicon based laser devices  

E-print Network

Silicon based light sources, especially laser devices, are the key components required to achieve a complete integrated silicon photonics system. However, the fundamental physical limitation of the silicon material as light ...

Yi, Jae Hyung



Silicon-Based Semiconductor Heterostructures: Column IV Bandgap Engineering  

E-print Network

Silicon-Based Semiconductor Heterostructures: Column IV Bandgap Engineering JOHN C. BEAN, FELLOW, IEEE Invited Paper Semiconductor heterostructures greatly enhance the range of possible device no natural semiconductor partner, exploitation of these effects had been confined to com- pound

Bean, John C.


Lifetime characteristics of Micro-Strip Gas Chambers  

NASA Astrophysics Data System (ADS)

Accelerated ageing tests were performed on four test chambers using high intensity 8 keV X-rays. The effects of varying the following chamber parameters were investigated: strip metal (aluminium, gold), substrate type (Schott S8900, Desag D263) and gas mixture ( {Ar}/{DME}, {Ne}/{DME}). After initial poor ageing results from an MSGC fabricated with aluminium strips on an S8900 substrate, chambers consistently withstood total deposited charge values in excess of 100 mC/cm, with no significant loss of gain.

Duerdoth, I. P.; Freestone, J.; Lumb, N.; Snow, S.; Thompson, R. J.



Applications of Gas Imaging Micro-Well Detectors to an Advanced Compton Telescope  

NASA Technical Reports Server (NTRS)

We present a concept for an Advanced Compton Telescope (ACT) based on the use of pixelized gas micro-well detectors to form a three-dimensional electron track imager. A micro-well detector consists of an array of individual micro-patterned proportional counters opposite a planar drift electrode. When combined with thin film transistor array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined by timing the drift of the ionization electrons. The primary advantage of this approach is the excellent tracking of the Compton recoil electron that is possible in a gas volume. Such good electron tracking allows us to reduce the point spread function of a single incident photon dramatically, greatly improving the imaging capability and sensitivity. The polarization sensitivity, which relies on events with large Compton scattering angles, is particularly enhanced. We describe a possible ACT implementation of this technique, in which the gas tracking volume is surrounded by a CsI calorimeter, and present our plans to build and test a small prototype over the next three years.

Bloser, P. F.; Hunter, S. D.; Ryan, J. M.; McConnell, M. L.; Miller, R. S.; Jackson, T. N.; Bai, B.; Jung, S.



THETRIS: A micro-scale temperature and gas release model for TRISO fuel  

Microsoft Academic Search

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 submillimeter-sized kernels formed into tristructural-isotropic (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. Micro-scale models

Javier Ortensi; Brian Boer; Abderrafi M. Ougouag



Design and fabrication of high-temperature micro-hotplates for drop-coated gas sensors  

Microsoft Academic Search

This paper reports on the optimisation of micromachined hotplates for gas-sensing applications designed to stand high-temperature coating processes and modes of operation. Different thin film materials, geometry and dimensions have been investigated regarding their power consumption, temperature distribution over the sensing area and robustness when annealed at high temperature. In comparison with oxide films, the micro-hotplates made of nitride were

D Briand; A Krauss; B van der Schoot; U Weimar; N Barsan; W Göpel; N. F de Rooij



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: [Center for Nanomaterials and Energy Devices, School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra (India); Han, Sung-Hwan, E-mail: [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)



Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor  

NASA Astrophysics Data System (ADS)

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

Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander



Micro gas analysis system for measurement of atmospheric hydrogen sulfide and sulfur dioxide.  


A honeycomb structure microchannel scrubber was developed to achieve efficient and stable gas collection. A thin porous membrane was pasted on a microchannel by the adhesive force of a fresh polydimethylsiloxane surface. The microchannel scrubber achieved much more efficient gas collection than conventional impingers and diffusion scrubbers. Two sets of the microchannel scrubbers and detectors were integrated in a 10 cm x 9 cm plastic board to create a micro gas analysis system (microGAS) for simultaneous measurements of H2S and SO2. The whole system including a battery was incorporated in a carrying case 34 cm W x 16 cm D x 17 cm H for use in the field. Liquid flows at 30 microl min(-1) were obtained by bimetal micropumps. The estimated detection limits were 0.1 ppbv for H2S and 1 ppbv for SO2. The system was demonstrated for real atmospheric gas analysis, and the results agreed well with data concurrently obtained by ion chromatography coupled with a cylindrical diffusion scrubber. The system we developed allowed automated continuous analyses in the field and achieved a much higher time resolution compared to those by ion chromatographic analysis. PMID:16286968

Ohira, Shin-Ichi; Toda, Kei



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)



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.




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



Silicon-based Packaging Platform for Light Emitting Diode  

Microsoft Academic Search

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

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




E-print Network

ADAPTIVE OPTIC CORRECTION USING SILICON BASED DEFORMABLE MIRRORS Julie A. Perreaulta, Thomas G of the power required for conventional DMs. Performance of an adaptive optics system using a pi was achieved. Advantages and limitations of-DMs are described, in relation to conventional adaptive optics


Life cycle analysis of silicon-based photovoltaic systems  

Microsoft Academic Search

The analysis focuses on a comparative evaluation of emissions from conventional private passenger vehicles versus the environmental burdens of electric passenger vehicles. The batteries of electric passenger vehicles are loaded during daily working hours partly via silicon-based PV panels covering the vehicle parking areas (solar service stations), and partly via the public electric grid. The data base refers to Western

W. Huber; G. Kolb



Visualisation by high resolution synchrotron X-ray phase contrast micro-tomography of gas films on submerged superhydrophobic leaves.  


Floods can completely submerge terrestrial plants but some wetland species can sustain O2 and CO2 exchange with the environment via gas films forming on superhydrophobic leaf surfaces. We used high resolution synchrotron X-ray phase contrast micro-tomography in a novel approach to visualise gas films on submerged leaves of common cordgrass (Spartina anglica). 3D tomograms enabled a hitherto unmatched level of detail regarding the micro-topography of leaf gas films. Gas films formed only on the superhydrophobic adaxial leaf side (water droplet contact angle, ?=162°) but not on the abaxial side (?=135°). The adaxial side of the leaves of common cordgrass is plicate with a longitudinal system of parallel grooves and ridges and the vast majority of the gas film volume was found in large ?180?m deep elongated triangular volumes in the grooves and these volumes were connected to each neighbouring groove via a fine network of gas tubules (?1.7?m diameter) across the ridges. In addition to the gas film retained on the leaf exterior, the X-ray phase contrast micro-tomography also successfully distinguished gas spaces internally in the leaf tissues, and the tissue porosity (gas volume per unit tissue volume) ranged from 6.3% to 20.3% in tip and base leaf segments, respectively. We conclude that X-ray phase contrast micro-tomography is a powerful tool to obtain quantitative data of exterior gas features on biological samples because of the significant difference in electron density between air, biological tissues and water. PMID:25175398

Lauridsen, Torsten; Glavina, Kyriaki; Colmer, Timothy David; Winkel, Anders; Irvine, Sarah; Lefmann, Kim; Feidenhans'l, Robert; Pedersen, Ole



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



Integrated Mach-Zehnder micro-interferometer for gas trace remote sensing  

NASA Astrophysics Data System (ADS)

The realisation process and the preliminary tests on the performances of an integrated Mach-Zehnder Interferometer on LiNbO 3 (Lithium Niobate) substrate is presented. The microsystem has been obtained by using medium mass Ion Implantation on X-cut Lithium Niobate crystals. The interferometer is formed by integrated optical channel waveguides; the phase shift between the two optical paths has been obtained, without moving parts, by applying a suitable electric field. The whole device is 60mm long, has a 0.5x1mm2 cross section and weights a few grams. The power consumption is in the milliwatt range. In the present work results obtained in the spectral window (0.4?m-1.1?m) will be presented. The performance of the device, evaluated on standard radiation sources, demonstrates that a spectral resolution better than 0.3nm can be obtained on 400nm spectral windows. The Micro-interferometer has been tested in laboratory with a calibrated cell containing NO II gas and has demonstrated sensitivity in the ppb range if suitable optical paths are used. Its reduced dimensions and weights make these micro-systems ideal for a wide range of applications, spanning from Space Technology, Earth observation for Environment monitoring, to Safety and Security applications.

Chiarini, M.; Bentini, G. G.; Bianconi, M.; Cerutti, A.; Pennestri, G.; Wang, Pengfei; She, Lin; Mazzoldi, P.; Sada, C.



Fabrication of functional mesoscopic ceramic parts for micro gas turbine engines  

NASA Astrophysics Data System (ADS)

The demand for small-size energy sources with high power densities is increasing with the development of miniature devices. New materials and novel manufacturing techniques are essential for developing these energy sources for miniature devices. Micro gas turbine engines can have higher power density per volume and weight due to their higher operating frequencies, which is made possible by the scaling effect. Higher power densities can also lead to redundant systems that have higher reliability than single engine systems. By replacing metal parts with lighter ceramics, power generated per unit mass can be increased further. However, since the ceramic parts are brittle, they suffer from lower reliability. Mesoscopic ceramic parts have higher reliability due to their smaller volume. This can be predicted by Weibull statistics. A fist-size miniature gas turbine engine with silicon nitride parts called "Firefly" is being developed at the Rapid Prototyping Laboratory (RPL), Stanford University and its industrial partners. Firefly's rotor-group and turbine inlet nozzle are made of silicon nitride to achieve light weight and increased efficiency. The Firefly engine's ceramic parts require smooth surface but their complex geometry prevents grinding. The Mold Shape Deposition Manufacturing (Mold SDM) process and its derivative, therefore, are used to fabricate the ceramic parts. Since the process was not fully developed for the fabrication of functional ceramic parts, several process improvements have been made. The manufacturing processes and the fabricated parts are characterized in terms of surface quality, strength, accuracy and build time. The results show that the processes have been developed to the extent that they produce functional ceramic parts for micro gas turbine engines. The functionality of the Mold SDM silicon nitride parts for the Firefly engine is tested. The ceramic inlet nozzles were tested with high temperature gas. The ceramic turbine has been spin tested and it achieved 456,000 rpm. The ceramic compressor was characterized up to 420,000 rpm and the effect of compressor clearance gap for the compressor functionality was measured. Noticeable increases of compression ratio, mass flow rate and efficiency have been observed as the compressor clearance gap decreases from 180 mum to 120 mum.

Kang, Sangkyun


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

Microsoft Academic Search

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

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



X-ray tangential imaging at NSTX with a Micro Pattern Gas Detector based device  

NASA Astrophysics Data System (ADS)

An innovative system for fast 2-D X-ray imaging has been developed at ENEA Frascati, based on a pinhole coupled to a Micro Pattern Gas Detector with a Gas Electron Multiplier as an amplifying stage. The detector is equipped with a 2-D read-out printed circuit board with 144 pixels. This diagnostic images X-ray emission from the plasma at up to 100 kHz in a selectable energy range. A tangential imaging system has been calibrated in the X-ray energy range 3-8 keV and installed on the NSTX experiment at PPPL. Time resolved, 2-D X-ray images of the NSTX plasma core have been obtained with varying fields of view. Comparisons with the magnetic surfaces calculated by the EFIT code using external magnetics alone show good agreement between reconstructed flux surface and the soft-X ray iso-intensity contours for poloidal beta < 0.6. For greater values of poloidal beta, EFIT indicates an increase of the elongation of the flux surfaces from 1.5 to 2.2, while the X-ray images show that the iso-intensity contours become more circular.

Pacella, D.; Tritz, K.; Stutman, D.; Finkenthal, M.; Leigheb, M.; Kaita, R.; Sabbagh, S.



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.



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)



Electroluminescence efficiencies of erbium in silicon-based hosts  

SciTech Connect

We report on room-temperature 1.5??m electroluminescence from trivalent erbium (Er{sup 3+}) ions embedded in three different CMOS-compatible silicon-based hosts: SiO{sub 2}, Si{sub 3}N{sub 4}, and SiN{sub x}. We show that although the insertion of either nitrogen or excess silicon helps enhance electrical conduction and reduce the onset voltage for electroluminescence, it drastically decreases the external quantum efficiency of Er{sup 3+} ions from 2% in SiO{sub 2} to 0.001% and 0.0004% in SiN{sub x} and Si{sub 3}N{sub 4}, respectively. Furthermore, we present strong evidence that hot carrier injection is significantly more efficient than defect-assisted conduction for the electrical excitation of Er{sup 3+} ions. These results suggest strategies to optimize the engineering of on-chip electrically excited silicon-based nanophotonic light sources.

Cueff, Sébastien, E-mail:, E-mail: [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), UMR 6252 CNRS/CEA/Ensicaen/UCBN, Caen 14050 (France) [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), UMR 6252 CNRS/CEA/Ensicaen/UCBN, Caen 14050 (France); School of Engineering, Brown University, Providence, Rhode Island 02912 (United States); Manel Ramírez, Joan; Berencén, Yonder; Garrido, Blas [MIND-IN2UB, Department Electrònica, Universitat de Barcelona, Martí i Franquès 1, Barcelona 08028 (Spain)] [MIND-IN2UB, Department Electrònica, Universitat de Barcelona, Martí i Franquès 1, Barcelona 08028 (Spain); Kurvits, Jonathan A.; Zia, Rashid [School of Engineering, Brown University, Providence, Rhode Island 02912 (United States) [School of Engineering, Brown University, Providence, Rhode Island 02912 (United States); Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Rizk, Richard; Labbé, Christophe, E-mail:, E-mail: [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), UMR 6252 CNRS/CEA/Ensicaen/UCBN, Caen 14050 (France)] [Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP), UMR 6252 CNRS/CEA/Ensicaen/UCBN, Caen 14050 (France)



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



Silicon-Based Optical Modulator with Ferroelectric Layer  

NASA Technical Reports Server (NTRS)

According to a proposal, a silicon dioxide layer in a high-speed, low-power, silicon- based electro-optical modulator would be replaced by a layer of lead zirconate titanate or other ferroelectric oxide material. The purpose of this modification is to enhance the power performance and functionality of the modulator. In its unmodified form, the particular silicon- based electro-optical modulator is of an advanced design that overcomes the speed limitation of prior silicon-based electro- optical modulators. Whereas modulation frequencies of such devices had been limited to about 20 MHz, this modulator can operate at modulation frequencies as high as 1 GHz. This modulator can be characterized as a silicon-waveguide-based metal oxide/semiconductor (MOS) capacitor phase shifter in which modulation of the index of refraction in silicon is obtained by exploiting the free-charge-carrier-plasma dispersion effect. As shown in the figure, the modulator includes an n-doped crystalline silicon slab (the silicon layer of a silicon- on-insulator wafer) and a p-doped polycrystalline silicon rib with a gate oxide layer (the aforementioned silicon dioxide layer) sandwiched between them. Under accumulation conditions, the majority charge carriers in the silicon waveguide modify the index of refraction so that a phase shift is induced in the optical mode propagating in the waveguide. The advantage of using an MOS capacitor phase shifter is that it is possible to achieve high modulation speed because there are no slow carrier-generation or -recombination processes involved in the accumulation operation. The main advantage of the proposed substitution of a ferroelectric oxide layer for the silicon dioxide layer would arise from the spontaneous polarization effect of the ferroelectric layer: This spontaneous polarization would maintain accumulation conditions in the absence of applied voltage. Consequently, once the device had been switched to a given optical state, it would remain in that state, even in the absence of applied voltage (in other words, even with power turned off). A secondary advantage is that because the ferroelectric layer would have an index of refraction larger than that of silicon dioxide, there could be some reduction of optical losses attributable to fabrication of the modulator

Sheldon, Douglas



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



Reliability characterization of silicon-based germanium waveguide photodetectors  

NASA Astrophysics Data System (ADS)

A silicon-based germanium waveguide photodetector was demonstrated and its reliability related items were investigated. For different reverse biases, the slopes of the dark current increment versus stress time curves were first found to be the same, which made the lifetime extrapolation feasible. The lifetime of the photodetector under different bias was predicted by using a simple extrapolation method. In order to maintain the 10-year lifetime of the photodetector, the bias voltage should be kept lower than -3 V. For the first time, the degradation mechanism under stress biases was analyzed in detail by the reaction-diffusion (RD) model. The experimental results agree well with the theoretical derivation based on RD model.

Tu, Zhijuan; Zhou, Zhiping; Wang, Xingjun



Amorphous silicon based nipiin structure for color detection  

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous silicon based nipiin three color detectors with a bias voltage controlled spectral response have been fabricated. These band-gap and mobility-lifetime product engineered structures employed as two terminal devices exhibit a dynamic range above 95 dB. The maximum of the spectral response shifts by variation of the applied voltage. Three linearly independent spectral response curves can be extracted to generate a red-green-blue signal. Conventional spatial color separation with optical filters is transferred into a voltage multiplexed read out sequence. Bias voltage switching under different monochromatic illumination and illumination switching-on transients for different bias voltages are carried out to investigate the time dependent behavior of the photocurrent. Based on these results optimization criteria to accelerate the transient behavior and to determine the maximum frame rate for color detection are presented.

Knipp, D.; Stiebig, H.; Fölsch, J.; Finger, F.; Wagner, H.



Silicon-based sleeve devices for chemical reactions  


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)



Silicon-based sleeve devices for chemical reactions  


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

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



Large optical spectral range dispersion engineered silicon-based photonic crystal  

E-print Network

Large optical spectral range dispersion engineered silicon-based photonic crystal waveguide engineered slow light silicon-based photonic crystal waveguide PIN modulator. Low-dispersion slow light of the optical carrier wavelength over the bandwidth of the fundamental photonic crystal waveguide defect mode

Chen, Ray


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



Fast 2-D soft X-ray imaging device based on micro pattern gas detector  

NASA Astrophysics Data System (ADS)

An innovative fast system for X-ray imaging has been developed at ENEA Frascati (Italy) to be used as diagnostic of magnetic plasmas for thermonuclear fusion. It is based on a pinhole camera coupled to a Micro Pattern Gas Detector (MPGD) having a Gas Electron Multiplier (GEM) as amplifying stage. This detector (2.5 cm × 2.5 cm active area) is equipped with a 2-D read-out printed circuit board with 144 pixels (12 × 12), with an electronic channel for each pixel (charge conversion, shaping, discrimination and counting). Working in photon counting mode, in proportional regime, it is able to get X-ray images of the plasma in a selectable X-ray energy range, at very high photon fluxes (106 ph s-?1mm-2 all over the detector) and high framing rate (up to 100 kHz). It has very high dynamic range, high signal to noise ratio (statistical) and large flexibility in the optical configurations (magnification and views on the plasma). The system has been tested successfully on the Frascati Tokamak Upgrade (FTU), having central electron temperature of a few keV and density of 1020 m-3, during the summer 2001, with a one-dimensional perpendicular view of the plasma. In collaboration with ENEA, the Johns Hopkins University (JHU) and Princeton Plasma Physics (PPPL), this system has been set up and calibrated in the X-ray energy range 2-8 keV and it has been installed, with a two-dimensional tangential view, on the spherical tokamak NSTX at Princeton. Time resolved X-ray images of the NSTX plasma core have been obtained. Fast acquisitions, performed up to 50 kHz of framing rate, allow the study of the plasma evolution and its magneto-hydrodynamic instabilities, while with a slower sampling (a few kHz) the curvature of the magnetic surfaces can be measured. All these results reveal the good imaging properties of this device at high time resolution, despite of the low number of pixels, and the effectiveness of the fine controlled energy discrimination.

Pacella, D.; Bellazzini, R.; Brez, A.; Pizzicaroli, G.



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.



The influence of the gas environment on morphology and chemical composition of surfaces micro-machined with a femtosecond laser  

NASA Astrophysics Data System (ADS)

We investigated the influence of different gas environments on the fabrication of surfaces, homogeneously covered with equally sized and spaced micro-structures. Two types of structures have been successfully micro-machined with a femtosecond laser on titanium surfaces in various atmospheres. The surface chemistry of samples machined in oxygen and helium shows TiO2, while machining in nitrogen leads to an additional share of TiN. The actual surface structure was found to vary significantly as a function of the gas environment. We found that the ablated particles and their surface triggered two consecutive events: The optical properties of the gas environment became non-isotropic which then led to the pulse intensity being redistributed throughout the cross section of the laser beam. Additionally, the effective intensity was further reduced for TiN surfaces due to TiN's high reflectivity. Thus, the settings for the applied raster-scanning machining method had to be adjusted for each gas environment to produce comparable structures. In contrast to previous studies, where only noble gases were found suitable to produce homogeneous patches, we obtained them in an oxygen environment.

Lehr, Jorge; de Marchi, Fabrizio; Matus, Luke; MacLeod, Jennifer; Rosei, Federico; Kietzig, Anne-Marie



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

NASA Astrophysics Data System (ADS)

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

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


Silicon implementation of micro pressure sensor  

Microsoft Academic Search

Pressure sensing is one of the mostly performed measurement encompassing varieties of applications. The latest technology such as silicon based Micro-electromechanical Systems (MEMS) technology is favoured due to its competitive cost and proven performance. In our research, MEMS pressure sensor for biomedical application is investigated. There are a number of stages involved in our research for implementation of a MEMS

Yufridin Wahab; Aladin Zayegh; Rezaul Begg



Numerical analysis of gas and micro-particle interactions in a hand-held shock-tube device.  


A unique hand-held gene gun is employed for ballistically delivering biomolecules to key cells in the skin and mucosa in the treatment of the major diseases. One of these types of devices, called the Contoured Shock Tube (CST), delivers powdered micro-particles to the skin with a narrow and highly controllable velocity distribution and a nominally uniform spatial distribution. In this paper, we apply a numerical approach to gain new insights in to the behavior of the CST prototype device. The drag correlations proposed by Henderson (1976), Igra and Takayama (1993) and Kurian and Das (1997) were applied to predict the micro-particle transport in a numerically simulated gas flow. Simulated pressure histories agree well with the corresponding static and Pitot pressure measurements, validating the CFD approach. The calculated velocity distributions show a good agreement, with the best prediction from Igra & Takayama correlation (maximum discrepancy of 5%). Key features of the gas dynamics and gas-particle interaction are discussed. Statistic analyses show a tight free-jet particle velocity distribution is achieved (570 +/- 14.7 m/s) for polystyrene particles (39 +/- 1 microm), representative of a drug payload. PMID:16917664

Liu, Y; Kendall, M A F



Evaluation of micro flat-tube solid-oxide fuel cell modules using simple gas heating apparatus  

NASA Astrophysics Data System (ADS)

Micro flat-tube solid-oxide fuel cell (SOFC) modules consisting of 1 mm thick, 1.2 cm wide micro flat-tube SOFCs, gas manifold, and insulator have been fabricated and evaluated using simple gas heating apparatus. The cell consists of NiO - yttria stabilized zirconia (YSZ) as an anode (flat-tube support), scandia stabilized zirconia (ScSZ) as an electrolyte, gadolinia doped ceria (GDC) for an interlayer, and (La, Sr)(Fe, Co)O3 (LSCF) - GDC as a cathode, which has been fabricated using cost effective extrusion technique and dip-coating technique. The cell has been investigated between 600 and 650 °C operating temperature and showed the power density at 0.75 V of 0.19 and 0.385 W cm-2, respectively. Using the cell, a five and ten-series modules were assembled and stored in insulator with small gas heaters powered by a 24 V power source for start-up. The module successfully operated using hydrogen and methane fuel.

Suzuki, Toshio; Yamaguchi, Toshiaki; Sumi, Hirofumi; Hamamoto, Koichi; Shimada, Hiroyuki; Fujishiro, Yoshinobu



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

an inherent insta- bility in the hydrodynamic gas bearings [4]. Thrust bear- ings with 4 thrust pads, 3 lm of load capacity [5]. Figure 2 shows hydrodynamic bearing's operational principle at steady state, whereMicro gas bearings fabricated by deep X-ray lithography D. Kim, S. Lee, Y. Jin, Y. Desta, M. D

Bryant, Michael D.


A beam test of prototype time projection chamber using micro-pattern gas detectors at KEK  

NASA Astrophysics Data System (ADS)

We conducted a series of beam tests of prototype TPCs for the international linear collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs as a readout device. The prototype operated successfully in a test beam at KEK under an axial magnetic field of up to 1 T. The analysis of data is now in progress and some of the preliminary results obtained with GEMs and MicroMEGAS are presented along with our interpretation. Also given is the extrapolation of the obtained spatial resolution to that of a large TPC expected as the central tracker of the ILC experiment.

Kobayashi, Makoto



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.



Recent Research on One-Dimensional Silicon-Based Semiconductor Nanomaterials: Synthesis, Structures, Properties and Applications  

Microsoft Academic Search

The field of silicon nanowires (SiNWs) and silicon-based 1D nanostructured heterostructures represent one of the most important research subjects within the nanomaterials family. A series of synthesis approaches of SiNWs and silicon-based 1D nanostructured heterostructures have been developed, and have garnered the greatest attention in the past decades for a variety of applications. This article provides an overview on recent

Zhenyu Zhang; Rujia Zou; Li Yu; Junqing Hu



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.



Recent Progress in Silicon-Based MEMS Field Emission Thrusters  

NASA Astrophysics Data System (ADS)

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

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



Characterization and Modeling of Segmental Dynamics in Silicone Based Nanocomposites  

SciTech Connect

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

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



Study of subsonic–supersonic gas flow through micro\\/nanoscale nozzles using unstructured DSMC solver  

Microsoft Academic Search

We use an extended direct simulation Monte Carlo (DSMC) method, applicable to unstructured meshes, to numerically simulate\\u000a a wide range of rarefaction regimes from subsonic to supersonic flows through micro\\/nanoscale converging–diverging nozzles.\\u000a Our unstructured DSMC method considers a uniform distribution of particles, employs proper subcell geometry, and follows an\\u000a appropriate particle tracking algorithm. Using the unstructured DSMC, we study the

Masoud Darbandi; Ehsan Roohi



Silicon-Based Multiple Microsensors for Sensing Carbon Dioxide, Humidity and Temperature.  

NASA Astrophysics Data System (ADS)

A silicon based multiple microsensor for sensing carbon dioxide, humidity and temperature has been investigated. The carbon dioxide microsensor was designed based on gas permeable membrane and ion-sensing field effect transistor structures. The humidity microsensor was designed based on metal-oxide -semiconductor transistor with a polyimide sensing film. The temperature microsensor was also designed based on diode -sensing structure. The multiple microsensors were designed on the same chip and were fabricated by using standard VLSI processing techniques, micromachining processes and compatible polyimide processes. Small dimension, room temperature operation, fast response, and a relatively large chemical reservoir with an inner temperature controlled resistor are some of the special characteristics of this microsensor. Polyimides PMDA-ODA and 6FDA-ODA were chosen for humidity sensing, CO_2 gas selection and for wafer bonding. The polyimide and solid state compatible processes have been developed to reduce the sensor's dimension, simplify the fabrication process, and lower the production cost. A gaseous CO_2 measurement system was developed for measuring the device characteristics. The reaction parameters of the sensors have been analyzed and discussed to explain their sensing mechanisms. A novel polyimide assisted silicon wafer bonding method was investigated. The polyimide PI-2566 (6FDA-ODA) and the adhesion promoter VM-651 (aminopropyltriethoxysilane) were used as an intermediate material to bond two silicon wafers together. By sawing the bonded wafer and measuring the bond strength it was found that this method gave a uniform and strong bond. The bonding temperature was varied from 235^circC to 400 ^circC and the bond absorption characteristics were identified by analyzing the FTIR spectra. The bonding results are discussed and a bond model for the polyimide assisted silicon wafer bonding is suggested. This bonding process is simple and the yield rate is very high making it widely applicable in the packaging and bonding of standard ICs and microsensors.

Chang, Hsing-Cheng


Remote-Raman and Micro-Raman Studies of Solid CO2, CH4, Gas Hydrates and Ice  

NASA Technical Reports Server (NTRS)

It is well known that on Mars CO2 is the principal constituent of the thin atmosphere and on a seasonal basis CO2 snow and frost coats the polar caps. Also over 25% of the Martian atmosphere freezes out and sublimes again each year. The Mars Odyssey Emission Imaging system (THEMIS) has discovered water ice exposed near the edge of Mars southern perennials cap. In recent years, it has been suggested that in Martian subsurface CO2 may exist as gas hydrate (8CO2 + 44 H2O) with melting temperature of 10C. Since the crust of Mars has been stable for enough time there is also a possibility that methane formed by magmatic processes and/or as a byproduct of anaerobic deep biosphere activity to have raised toward the planet s surface. This methane would have been captured and stored as methane hydrate, which concentrates methane and water. Determination of abundance and distribution of these ices on the surface and in the near surface are of fundamental importance for understanding Martian atmosphere, and for future exploration of Mars. In this work, we have evaluated feasibility of using remote Raman and micro-Raman spectroscopy as potential nondestructive and non-contact techniques for detecting solid CO2, CH4 gas, and gas hydrates as well as water-ice on planetary surfaces.

Sharma, S. K.; Misra, A. K.; Lucey, P. G.; Exarhos, G. J.; Windisch, C. F., Jr.



Silicon-based semimetals and semiconductors for thermoelectric applications  

NASA Astrophysics Data System (ADS)

The direct conversion between heat and electricity can be achieved by thermoelectric devices. Thus, thermoelectricity is considered as not only an environmentally friendly substitute for compressor-based refrigerators but also a promising energy solution to harvest waste heat. State-of-the-art thermoelectric materials are often comprised of expensive tellurium or germanium elements and hence are hardly suitable for mass production. The silicon-based thermoelectrics, e.g. semimetallic CoSi and semiconducting beta -FeSi2 materials we study here, are composed of abundant elements in nature. They are also chemically stable, non-toxic, and mechanically robust. Despite the above benefits, they exhibit relatively lower efficiencies compared to state-of-the-art materials. In this dissertation, we have intended to understand the thermal and electrical transport in these materials and enhance their thermoelectric performance. CoSi possesses one of the highest power factors among thermoelectrics due to the sharp features around the Fermi level in its electronic density of states. In order to improve the performance, the effects of p-type dopants, isoelectronic substitutions, n-type dopants, and double doping were systematically studied for arc-melted CoSi samples. The results show that p-type dopants like iron and gallium and n-type dopants like nickel and palladium deteriorate the electrical properties due to the introduction of excess holes and electrons, respectively. Boron and platinum have very limited solubility in CoSi and the segregated impurity phases at grain boundaries are helpful to improve the electrical properties. The isoelectronic substitutions influence the power factor slightly; however, they result in a drastic decrease in the lattice thermal conductivity and hence an enhancement in the figure of merit. In addition, CoSi samples prepared by powder processing were investigated to further reduce the lattice thermal conductivity. Unfortunately, all the consolidated samples show worse performance than the arc-melted CoSi. beta-FeSi2 is one of the most cost-efficient thermoelectric materials. Its thermoelectric performance can be tuned by cobalt doping and the highest figure of merit is close to 0.4 at 1000 K. Grain size reduction was also used to reduce the lattice thermal conductivity. However, no improvement has been obtained yet. SiC nanoparticles were dispersed into beta-FeSi2 matrix to form a composite structure. With addition of the nanoparticles, the thermal conductivity is slightly decreased associated with a decrease in the power factor. Although the figure of merit is less than that of some Te-based materials, beta-FeSi2-based thermoelectrics may be suitable in large-scale applications where material abundance and cost are concerns.

Sun, Hui



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...


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: [School of Materials Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of)



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


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.



Thermal balance analysis of a micro-thermoelectric gas sensor using catalytic combustion of hydrogen.  


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 Q(catalyst) required for 1 mV of ?V(gas) was calculated to be 46.1 ?W. Using these parameters, we find from simulations for the device performance that the expected Q(catalyst) for 200 and 1,000 ppm H? was 3.69 ?W and 11.7 ?W, respectively. PMID:24451468

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



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



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

Microsoft Academic Search

Microstrip gas counters (MSGC) on electronic conducting glass such as Schott S8900 have a very stable long-time behaviour. However, this glass is available in relatively thick plates only. A thick substrate limits the performances of two-dimensional detectors by attenuating the signal of the backside electrode which carries the second position coordinate. A structure with “open cathodes”, where the central area

G. Cicognani; D. Feltin; B. Guerard; A. Oed



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

SciTech Connect

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

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



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


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



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



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



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



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


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.



Nanostructuring surfaces with conjugated silica colloids deposited using silicon-based microcantilevers  

Microsoft Academic Search

In this paper, the assembly and stability of locally spotted spherical nanoparticles onto various substrates are studied. Arrays of silicon-based microcantilevers, combined with an automated three-stage spotter, are used to deposit picolitre droplets containing 300 nm diameter polyethylene glycol and 150 nm diameter amino conjugated silica nanospheres onto silicon, allylamine and acrylic acid surfaces. Matrices of colloid spots ranging from

Thierry Leïchlé; Miguel Manso Silvan; Pascal Belaubre; Andrea Valsesia; Giacomo Ceccone; François Rossi; Daisuke Saya; Jean-Bernard Pourciel; Liviu Nicu; Christian Bergaud



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]. In the technologically important semiconductors and dielectrics heat is mostly carried by the acoustic phonons small structures, due to the modification of acoustic phonon energy spectra and decrease in the phonon


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.



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



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


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

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




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



The analysis of forensic samples using laser micro-pyrolysis gas chromatography mass spectrometry.  


Laser micropyrolysis gas chromatography-mass spectrometry is used for the analysis of paint, photocopier toner, and synthetic fiber materials to test the forensic potential of this emerging technology. It uses a laser microprobe to selectively target very small parts of the materials for GC-MS analysis. Whereas the paint and the toner samples were amenable to direct laser pyrolysis, the synthetic fibers proved transparent to the 1064 nm laser radiation. The difficulty with the fibers demonstrates that a specific laser wavelength may not be appropriate for all types of materials. Nevertheless, the fibers were able to be indirectly pyrolyzed by impregnation in a strongly absorbing graphite matrix. A vast array of hydrocarbon pyrolysates was detected from the different materials studied. Unique product distributions were detected from each sample and in sufficient detail to facilitate individual molecular characterization (i.e., molecular fingerprinting). The integrity of the laser data were confirmed by comparison to data obtained from the same samples by the more conventional pyroprobe pyrolysis GC-MS method. The high spatial resolution and selectivity of the laser method may be advantageous for specific forensic applications, however, further work may be required to improve the reproducibility of the data. PMID:11569542

Armitage, S; Saywell, S; Roux, C; Lennard, C; Greenwood, P



Development of porous silicon-based miniature fuel cells  

NASA Astrophysics Data System (ADS)

Nowadays the rise in portable electronics requires energy sources compatible with the environmental constraints. We demonstrate, in this paper, how microfabrication techniques allow the development of low-cost miniature fuel cells fully integrated on silicon. Contrary to usual proton-conducting membranes made of ionomers ensuring the proton conductivity of proton-exchange membrane fuel cells (PEMFCs), we present here another way to proceed. It consists in the chemical grafting of molecules bearing acid groups on the pore walls of a porous silicon membrane to mimic the structure of an ionomer, such as Nafion®. We obtain an inorganic, dimensionally stable, proton-conducting membrane with many optimizable parameters such as the pore size and the pore structure of the membrane or the nature of the grafted molecules. Moreover, the use of a silicon substrate offers advantages of serial and parallel integration, the possibility of encapsulation by wafer bonding and gas feed and electrical contacts may be included into the membrane etching process, thanks to simple KOH wet etching processes and metal sputtering.

Pichonat, Tristan; Gauthier-Manuel, Bernard



Development and validation of a solid phase micro-extraction–gas chromatography–mass spectrometry method for the determination of furan in baby-food  

Microsoft Academic Search

An efficient and simple method for the determination of furan in baby-food (vegetables and fruits) by solid phase micro-extraction–gas chromatography–mass spectrometry (SPME–GC–MS) was developed and validated. Experimental design was used to investigate the effects of temperature and time of extraction. The calculated regression model was used to find the experimental conditions providing the optimal SPME extraction yield. Validation was carried

Federica Bianchi; Maria Careri; Alessandro Mangia; Marilena Musci



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



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



Realization of Long-Period Corrugated Grating in Silica-on-Silicon-Based Channel Waveguide  

Microsoft Academic Search

Long-period corrugated grating in silica-on-silicon-based channel waveguide is realized by making periodic corrugation on top of a relatively high-indexed (contrast ap.8%) Ge-doped silica waveguide, which is sandwiched between undoped silica undercladding and boro-phospho-silicate-glass overcladding layers. Resonance wavelength of the 15-mm-long grating is found at ~1581 nm, having negligible polarization dependency at room temperature, with a grating strength of ~11 dB

Suchandan Pal; Ashok Chauhan; Mahendra Singh; Pawan Kumar; Mukesh Sharma; Nirmal Pradhan; Kuldip Singh; C. Dhanavantri



Ash fouling and erosion of silicon-based ceramic expanders in coal-fired power plants  

Microsoft Academic Search

Lysholm-type helical-screw engines (expanders) are proposed as a means of generating electrical power from coal-fired power plants (topping cycle). Ash erosion and deposition (fouling) of silicon-based ceramic materials exposed to coal ash at topping-cycle temperatures (approximately 1270 K) was studied at the Lawrence Livermore Laboratory to select suitable expander materials. Silicon carbide (SiC) or silicon nitride (SiâNâ) blocks exposed to

R. W. Taylor; T. E. Shell



Real time characterization of the preparation of amorphous silicon-based solar cells  

Microsoft Academic Search

Real time spectroscopic ellipsometry (RTSE) has been applied to characterize the p and i layers that compose amorphous silicon-based solar cells prepared in the superstrate configuration using a single-chamber reactor system. In this study, 106-point spectra (1.5-4.5 eV) in the ellipsometry angles (?, ?) are obtained during solar cell preparation with acquisition and repetition times as short as 160 ms

Yiwei Lu; Sangbo Kim; Ing-Shin Chen; Yeeheng Lee; C. M. Fortmann; C. R. Wronski; R. W. Collins



Simple broadband anti-reflective coatings for superstrate-type silicon-based tandem cells  

Microsoft Academic Search

In this paper, the superstrate-type silicon-based tandem cells between air and glass are added to a porous SiO2\\/MgF2 double-layer anti-reflective (DLAR) thin film structure in order to improve the glass substrate low reflectivity in a wide spectral range (400–1200nm), without high reflectivity in the near-infrared region. Practical discussion is presented, as well as experimental results of fabricated films and devices.

Ting-Wei Kuo; Ping-Kuan Chang; Yu-Shuang Yang; Mau-Phon Houng; Na-Fu Wang; Yu-Zen Tsai



High-speed silicon-based integrated optical modulators for optical-fiber telecommunications  

NASA Astrophysics Data System (ADS)

A monolithically integrated silicon-based optical modulator is reviewed with respect to design and high-speed performance. The integrated silicon-based optical modulator consists of nested in-phase/quadrature Mach-Zehnder modulator operated in quadrature phase-shift keying formats. Design and performance of high-speed silicon ribwaveguide phase shifters and high-frequency coplanar-waveguide traveling-wave electrode are presented as key modulator elements which allow high-speed zero-chirp operation of the integrated optical modulator in the quadrature phase-shift keying formats. Transmission performance of the integrated optical modulator in differential quadrature phase-shift keying format is characterized in direct-detection constellation-diagram and bit-error-rate measurements towards 44.6-Gbit/s optical-fiber transmission. High-speed quadrature phase-shift keying operation is characterized in coherent-detection constellation-diagram measurements in C and L bands, and QPSK at bit rates up to 64-Gbit/s is presented. A partial-rib-waveguide polarization rotator, which is essential for 128-Gbit/s small-footprint silicon-based optical modulator for digital coherent communication, is described and high-extinction ratio low-loss polarization conversion over C and L bands is evidenced.

Ogawa, Kensuke



Aug 7, 2008 Researchers in the US unveil a silicon-based CCD camera that mimics the  

E-print Network NEWS Aug 7, 2008 Researchers in the US unveil a silicon-based CCD camera that mimics compared with planar CCD cameras that use simple, single-component imaging lenses." Conventional cameras

Rogers, John A.


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.



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


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



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.




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


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.



Application of mass fabricated silicon-based gold transducers for amperometric biosensors.  


The backside contact, silicon-based transducers with vacuum-deposited gold layer (BSC) are evaluated as the base for electrochemical biosensors construction. Their comparison with commercially available transducers with screen printed gold and traditional gold disc electrode is reported. To determine the advantages and disadvantages of each of gold surfaces mentioned above, the 6-(ferrocenyl)-hexanethiol was used as the indicator. The results revealed the usefulness of BSC chips for the formation of stable self-assembled monolayers (SAMs). After the preliminary analysis, the SAM of thiol-ssDNA was formed on the BSC transducers as recognition layer. The electrochemical analysis in methylene blue solution was carried out after ssDNA immobilization and DNA-DNA hybridization. It is shown that prepared sensors are able to recognize complementary DNA sequence, based on the change in height and the potential shifts of reduction peaks of methylene blue. Obtained results are in full agreement with literature data. The compact size of silicone-based transducers allows to significantly reduce the required volume of tested solutions. PMID:20435527

Zió?kowski, Robert; Górski, ?ukasz; Zaborowski, Micha?; Malinowska, El?bieta



Silicon-based filters, resonators and acoustic channels with phononic crystal structures  

NASA Astrophysics Data System (ADS)

This paper discusses the phenomenon of phononic crystal silicon-based filters, resonators and acoustic channels structured in geometrical periodic arrays created by a single silicon material. Component structured geometrical periodic array refers to a structure of square stubbed rods arranged in repeated arrays on a silicon plate. The study discovered that the band gap of the phononic crystal structure can be modulated under different heights and rotational angles of periodically arrayed square stubbed rods. In addition to band gap modulation, we used the finite element method (FEM) and supercell techniques to analyse the resonance characteristics of defect-containing phononic crystal structures with a larger band gap size design. In addition, the paper also investigated the effects on acoustic channels. Previous studies have already analysed defect-containing resonator and channel phenomenon by the plane-wave expansion method with supercell techniques. However, the FEM can solve numerical issues of extreme difficulty to reach convergence. The results of this study elaborated on the manufacturing feasibility of silicon-based acoustic resonance and filter devices under a complementary metal-oxide-semiconductor synchronization process.

Huang, Zi-Gui



Gas-Liquid Slug Flow in Microchannels  

NASA Astrophysics Data System (ADS)

Slug flow is not only an attractive regime for conducting gas-liquid reactions in microchemical systems. It also provides a normal velocity that enhances liquid mixing for high Peclet number flows, e.g. for particle synthesis. We previously extended the flow regime diagrams initially obtained for micro heat-exchangers to the liquid deficient conditions relevant to microreactors. We use silicon-based single microchannels with rectangular and triangular cross-section and hydraulic diameters of 40-400 microns that are capped with Pyrex to provide for optical access. Ethanol, water, toluene, and nitrogen are the working fluids. Superficial velocities are varied between 0.01 and 10 m/s for the gas and 0.001 and 1 m/s for the liquid with corresponding Capillary and Bond numbers between 0.001 and 0.01. We complement pulsed-laser fluorescence microscopy and confocal scanning microscopy with a non-intrusive optical sensor to monitor the transient flow at sampling rates of 10 kHz. Interfacial area, void fraction, slug velocity U_s, and the transversal velocity component introduced by internal circulation in the liquid are determined. For comparable Peclet numbers, the transverse velocity between channel wall and center is lO0.1 U_s and allows for shorter mixing lengths than reported for micromixers with patterned walls. Gas and liquid are completely separated on-chip subsequent to the mixing step.

Guenther, Axel; de Mas, Nuria; Jhunjhunwala, Manish; Schmidt, Martin A.; Jensen, Klavs F.



Micro\\/Nano X-Ray Tomography Reconstruction Tuning Using SEM Images for PEMFC Gas Diffusion Layers  

Microsoft Academic Search

X-ray micro\\/nano tomography is a powerful tool to reveal inside structures of a sample, either an IC chip or a porous material. A challenge in X-ray tomography is to select a correct threshold to ensure the reconstructed models as close to the reality as possible. This paper presents a study to use scanning electron microscope (SEM) images as references for

H. Ostadi; K. Jiang; P. D. Prewett



Micro-lotus constructed by Fe-doped ZnO hierarchically porous nanosheets: Preparation, characterization and gas sensing property  

Microsoft Academic Search

Preparation of micro-lotus constructed by hierarchically porous Fe-doped ZnO nanosheets via a facile hydrothermal method is reported here. The products have been analyzed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high resolution transmission electron microscope (HRTEM). Results showed that the morphology of the sample did not change

Ang Yu; Jieshu Qian; Hao Pan; Yuming Cui; Meigui Xu; Luo Tu; Qingli Chai; Xingfu Zhou



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.


Rapid analysis of six phthalate esters in wine by ultrasound-vortex-assisted dispersive liquid-liquid micro-extraction coupled with gas chromatography-flame ionization detector or gas chromatography-ion trap mass spectrometry.  


An Ultrasound-Vortex-Assisted Dispersive Liquid-Liquid Micro-Extraction (USVADLLME) procedure coupled with Gas Chromatography-Flame Ionization Detector (GC-FID) or Gas Chromatography-Ion Trap Mass Spectrometry (GC-IT/MS) is proposed for rapid analysis of six phthalate esters in hydroalcoholic beverages (alcohol by volume, alc vol(-1), ?40%). Under optimal conditions, the enrichment factor of the six analytes ranges from 220- to 300-fold and the recovery from 85% to 100.5%. The limit of detection (LOD) and limit of quantification (LOQ) are ?0.022 ?g L(-1) and ?0.075 ?g L(-1), respectively. Intra-day and inter-day precisions expressed as relative standard deviation (RSD), are ?8.2% and ?7.0%, respectively. The whole proposed methodology has demonstrated to be simple, reproducible and sensible for the determination of trace phthalate esters in red and white wine samples. PMID:23498123

Cinelli, Giuseppe; Avino, Pasquale; Notardonato, Ivan; Centola, Angela; Russo, Mario Vincenzo



Silicon-based Lewis acid assisted cinchona alkaloid catalysis: highly enantioselective aza-Michael reaction under solvent-free conditions.  


The study showed that a combination of an achiral silicon-based Lewis acid and chiral Lewis base, such as iodotrimethylsilane (TMSI) and cinchonine, generated a highly enantioselective catalyst system under solvent-free conditions which gave aromatic ?-amino ketones with up to >99% ee. Mechanistic studies demonstrate the enhanced asymmetric induction may be due to the combined and competitive activation of a carbonyl moiety of chalcone with cinchonine and the silicon-based Lewis acid in the aza-Michael reaction. PMID:22087568

Yang, Hua-Meng; Li, Li; Li, Fei; Jiang, Ke-Zhi; Shang, Jun-Yan; Lai, Guo-Qiao; Xu, Li-Wen



Mechanical engineering and design of silicon-based particle tracking devices  

SciTech Connect

The Mechanical Engineering and Electronics Division of the Los Alamos National Laboratory has been investigating silicon-based particle tracking device technology as part of the Superconducting Super Collider-sponsored silicon subsystem collaboration. Structural, thermal, and materials issues have been addressed. This paper discussed detector structural integrity and stability, including detailed finite element models of the silicon chip support and predictive methods used in designing with advanced composite materials. Electronic thermal loading and efficient dissipation of such energy using heat pipe technology has been investigated. The use of materials whose coefficients of thermal expansion are engineered to match silicon or to be near zero, as appropriate, have been explored. Material analysis and test results from radiation, chemical, and static loading are compared with analytical predictions and discussed. 1 ref., 2 figs., 1 tab.

Miller, W.O.; Thompson, T.C.; Gamble, M.T.; Reid, R.S.; Woloshun, K.A.; Dransfield, G.D.; Ziock, H.J.



Design, fabrication, and measurement of two silicon-based ultraviolet and blue-extended photodiodes  

NASA Astrophysics Data System (ADS)

Two silicon-based ultraviolet (UV) and blue-extended photodiodes are presented, which were fabricated for light detection in the ultraviolet/blue spectral range. Stripe-shaped and octagon-ring-shaped structures were designed to verify parameters of the UV-responsivity, UV-selectivity, breakdown voltage, and response time. The ultra-shallow lateral pn junction had been successfully realized in a standard 0.5-?m complementary metal oxide semiconductor (CMOS) process to enlarge the pn junction area, enhance the absorption of UV light, and improve the responsivity and quantum efficiency. The test results illustrated that the stripe-shaped structure has the lower breakdown voltage, higher UV-responsicity, and higher UV-selectivity. But the octagon-ring-shaped structure has the lower dark current. The response time of both structures was almost the same.

Chen, Changping; Wang, Han; Jiang, Zhenyu; Jin, Xiangliang; Luo, Jun



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

PubMed Central

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



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



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


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



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



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


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

Huang, Danhong; Gumbs, Godfrey; Roslyak, Oleksiy



Near infrared and Raman spectroscopy as Process Analytical Technology tools for the manufacturing of silicone-based drug reservoirs  

Microsoft Academic Search

Using near infrared (NIR) and Raman spectroscopy as PAT tools, 3 critical quality attributes of a silicone-based drug reservoir were studied. First, the Active Pharmaceutical Ingredient (API) homogeneity in the reservoir was evaluated using Raman spectroscopy (mapping): the API distribution within the industrial drug reservoirs was found to be homogeneous while API aggregates were detected in laboratory scale samples manufactured

J. Mantanus; E. Rozet; K. Van Butsele; C. De Bleye; A. Ceccato; B. Evrard; Ph. Hubert; E. Ziémons



Micro-Simulation Models of Urban Regions: Anticipating Greenhouse Gas Emissions from Transport and Housing in Austin, Texas  

E-print Network

to shift. For example, for the first time in over two decades, share of new passenger cars increased by 2 to transportation, households use electricity, natural gas and other sources of energy regularly for space conditioning and powering household devices. A closer look at American Housing Survey data (AHS 2005) reveals

Kockelman, Kara M.


Sulfur and iron speciation in gas-rich impact-melt glasses from basaltic shergottites determined by microXANES  

SciTech Connect

Sulfur and iron K XANES measurements were made on GRIM glasses from EET 79001. Iron is in the ferrous state. Sulfur speciation is predominately sulfide coordination but is Fe coordinated in Lith B and, most likely, Ca coordinated in Lith A. Sulfur is abundantly present as sulfate near Martian surface based on chemical and mineralogical investigations on soils and rocks in Viking, Pathfinder and MER missions. Jarosite is identified by Moessbauer studies on rocks at Meridian and Gusev, whereas MgSO{sub 4} is deduced from MgO-SO{sub 3} correlations in Pathfinder MER and Viking soils. Other sulfate minerals such as gypsum and alunogen/S-rich aluminosilicates and halides are detected only in martian meteorites such as shergottites and nakhlites using SEM/FE-SEM and EMPA techniques. Because sulfur has the capacity to occur in multiple valence states, determination of sulfur speciation (sulfide/sulfate) in secondary mineral assemblages in soils and rocks near Mars surface may help us understand whether the fluid-rock interactions occurred under oxidizing or reducing conditions. On Earth, volcanic rocks contain measurable quantities of sulfur present as both sulfide and sulfate. Carroll and Rutherford showed that oxidized forms of sulfur may comprise a significant fraction of total dissolved sulfur, if the oxidation state is higher than {approx}2 log fO{sub 2} units relative to the QFM buffer. Terrestrial samples containing sulfates up to {approx}25% in fresh basalts from the Galapagos Rift on one hand and high sulfide contents present in oceanic basalts on the other indicate that the relative abundance of sulfide and sulfate varies depending on the oxygen fugacity of the system. Basaltic shergottites (bulk) such as Shergotty, EET79001 and Zagami usually contain small amounts of sulfur ({approx}0.5%) as pyrrhotite. But, in isolated glass pockets containing secondary salts (known as GRIM glasses) in these meteorites, sulfur is present in high abundance ({approx}1-12%). To determine sulfur speciation (sulfide, sulfate or elemental sulfur) in these glasses, Gooding et al. and Burgess et al. carried out vacuum pyrolysis experiments on these GRIM glasses (also called Lith C) using quadrupole mass-spectrometric methods. They found that the evolved S-bearing gases from these samples consisted of both SO{sub 2} (from sulfate) and H{sub 2}S (from sulfide) in varying proportions. However, as mass-spectrometric studies do not provide details about spatial association of these S-species in these samples, we have studied the spatial distribution of sulfides and sulfates in GRIM glasses using sulfur K micro-XANES techniques in the present study. The microscale speciation of S may have important implications for the Rb-Sr isotope systematics of EET79001 Lith C glasses. In reference to oxidative weathering of surface basalts on Mars yielding secondary iron sulfates, Solberg and Burns examined a GRIM glass in EET79001 by Moessbauer spectroscopic techniques and showed that the percentage of Fe{sup 3+} in Lith C is <2%. They suggested that the Lith C contains very little Fe{sup 3+} despite the occurrence of oxidized sulfate in them, indicating that the conditions leading to the formation of these glasses were insufficiently oxidizing to produce Fe{sup 3+} from Fe{sup 2+} in these glasses. To understand the implications of these observations for the formation of the GRIM glasses, we determined the oxidation state of Fe in the GRIM glasses using Fe K micro-XANES techniques. The S and Fe K micro-XANES measurements were performed on thin sections from EET79001: 506 from Lith A and 507 from Lith B.

Sutton, S.R.; Rao, M.N.; Nyquist, L.E. (UofC); (Johnson Space Center)



A hybrid sequential deposition fabrication technique for micro fuel cells  

NASA Astrophysics Data System (ADS)

Micro fuel cell systems have elicited significant interest due to their promise for instantly rechargeable, longer duration and portable power. Most micro fuel cell systems are either built as miniaturized plate-and-frame or silicon-based microelectromechanical systems (MEMS). Plate-and-frame systems are difficult to fabricate smaller than 20 cm3. Existing micro fuel cell designs cannot meet the cost, scale and power requirements of some portable power markets. Traditional MEMS scaling advantages do not apply to fuel cells because the minimum area for the fuel cell is fixed by the catalyst area required for a given power output, and minimum volume set by mass transport limitations. We have developed a new hybrid technique that borrows from both micro and macro machining techniques to create fuel cells in the 1-20 cm3 range, suitable for cell phones, PDAs and smaller devices.

Stanley, Kevin G.; Czyzewska, Eva K.; Vanderhoek, Tom P. K.; Fan, Lilian L. Y.; Abel, Keith A.; Wu, Q. M. Jonathan; Parameswaran, M. Ash



Nanostructural defects evidenced in failing silicon-based NMOS capacitors by advanced failure analysis techniques  

NASA Astrophysics Data System (ADS)

An experimental methodology compliant with industrial constraints was deployed to uncover the origin of soft breakdown events in large planar silicon-based NMOS capacitors. Complementary advanced failure analysis techniques were advantageously employed to localize, isolate and observe structural defects at nanoscale. After an accurate localization of the failing area by optical beam-induced resistance change (OBIRCH), focused ion beam (FIB) technique enabled preparing thin specimens adequate for transmission electron microscopy (TEM). Characterization of the gate oxide microstructure was performed by highresolution TEM imaging and energy-filtered spectroscopy. A dedicated experimental protocol relying on iterative FIB thinning and TEM observation enabled improving the quality of electron imaging of defects at atom scale. In that way, the gate oxide integrity was evaluated and an electrical stress-induced silicon epitaxy was detected concomitantly to soft breakdown events appearing during constant voltage stress. The growth of silicon hillocks enables consuming a part of the breakdown energy and may prevent the soft breakdown event to evolve towards a hard breakdown that is catastrophic for device functionality.

Faivre, Emilie; Llido, Roxane; Putero, Magali; Fares, Lahouari; Muller, Christophe



Silicon-based optoelectronic integrated circuit for label-free bio/chemical sensor.  


We demonstrate a silicon-based optoelectronic integrated circuit (OEIC) for label-free bio/chemical sensing application. Such on-chip OEIC sensor system consists of optical grating couplers for vertical light coupling into silicon waveguides, a thermal-tunable microring as a tunable filter, an exposed microring as an optical label-free sensor, and a Ge photodetector for a direct electrical readout. Different from the conventional wavelength-scanning method, we adopt low-cost broadband ASE light source, together with the on-chip tunable filter to generate sliced light source. The effective refractive index change of the sensing microring induced by the sensing target is traced by scanning the supplied electrical power applied onto the tracing microring, and the detected electrical signal is read out by the Ge photodetector. For bulk refractive index sensing, we demonstrate using such OEIC sensing system with a sensitivity of ~15 mW/RIU and a detection limit of 3.9 ?-RIU, while for surface sensing of biotin-streptavidin, we obtain a surface mass sensitivity of S(m) = ~192 µW/ng?mm(-2) and a surface detection limit of 0.3 pg/mm(2). The presented OEIC sensing system is suitable for point-of-care applications. PMID:23938665

Song, Junfeng; Luo, Xianshu; Kee, Jack Sheng; Han, Kyungsup; Li, Chao; Park, Mi Kyoung; Tu, Xiaoguang; Zhang, Huijuan; Fang, Qing; Jia, Lianxi; Yoon, Yong-Jin; Liow, Tsung-Yang; Yu, Mingbin; Lo, Guo-Qiang



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.



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

NASA Astrophysics Data System (ADS)

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

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



Design of a compact crossing for silicon-based slot and strip waveguides  

NASA Astrophysics Data System (ADS)

A compact crossing for silicon-based slot and strip waveguides is proposed by utilizing a strip-multimode waveguide (SMW) crossing at the center and two logarithmically tapered slot-to-strip mode converters at the ports with slot waveguides. For input/output ports with slot waveguides, the guided modes are efficiently transformed through the mode converter and then enter into the SMW (without mode converters for those ports with strip waveguides), where the fields converge at the center of the intersection due to the self-imaging effect. Hence, the size of the input beam is much smaller than the width of the SMW at the crossing center, leading to significant reductions of the crosstalk and radiation loss. The numerical results show that a hybrid waveguide crossing operating at the wavelength of 1.55 ?m with the insertion loss, crosstalk, and reflection of 0.14/0.164, -35.88/-38.79, and -35.35/-40.5 dB for input ports with slot/strip waveguides, respectively, is achieved. Moreover, the fabrication tolerances to the structural parameters are investigated by using a finite-difference time-domain method and evolution of the injected field along the propagation distance through the crossing structure is also demonstrated.

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



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


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

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



Monitoring the emission of volatile organic compounds from flowers of Jasminum sambac using solid-phase micro-extraction fibers and gas chromatography with mass spectrometry detection.  


Solid-phase micro-extraction (SPME) was studied as a solvent free alternative method for the extraction and characterization of volatile compounds in intact and plucked flowers of Jasminum sambac at different day time intervals using gas chromatography (GC-FID) and gas chromatography-quadrupole mass spectrometry. The analytes identified included alcohols, esters, phenolic compounds, and terpenoids. The main constituents identified in the flower aroma using different fibers were cis-3-hexenyl acetate, (E)-beta-ocimene, linalool, benzyl acetate, and (E,E)-alpha-farnesene. The benzyl acetate proportion decreased from morning to afternoon and then increased in evening collections. PDMS fiber showed a high proportion of (E,E)-alpha-farnesene in jasmine floral aroma. Among other constituents identified, cis-3-hexenyl acetate, linalool, and benzyl acetate were major aroma contributors in plucked and living flowers extracts using PDMS/DVB, Carboxen/PDMS, and DVB/Carboxen/PDMS fibers. PDMS/DVB recorded the highest emission for benzyl acetate while the (E)-beta-ocimene proportion was highest in DVB/Carboxen/PDMS when compared with the rest. The highest linalool content, with increasing proportion from morning to noon, was found using mixed coating fibers. Almost negligible volatile adsorption was recorded for the polyacrylate fiber for intact flower aroma, whereas it was most effective for benzyl acetate, followed by indole under plucked conditions. Moreover, the highest amounts extracted, evaluated from the sum of peak areas, were achieved using Carboxen/PDMS, and DVB/Carboxen/PDMS. Introduction of a rapid, and solvent free SPME method for the analysis of multicomponent volatiles can be successfully employed to monitor the extraction and characterization of flower aroma constituents. PMID:21941909

Pragadheesh, Vppalayam Shanmugam; Yadav, Anju; Chanotiya, Chandan Singh; Rout, Prasanta Kumar; Uniyal, Girish Chandra



Preparation of 2,3-disubstituted indoles by sequential Larock heteroannulation and silicon-based cross-coupling reactions  

Microsoft Academic Search

A simple and convergent synthesis of 2,3-disubstituted indoles has been developed using a sequential Larock indole synthesis and silicon-based, cross-coupling reaction. Substituted 2-iodoanilines reacted with an alkynyldimethylsilyl tert-butyl ether to afford indole-2-silanols under the Larock heteroannulation conditions after hydrolysis. The corresponding sodium 2-indolylsilanolate salts successfully engaged in cross-coupling with aryl bromides and chlorides to afford multi-substituted indoles. The development of

Scott E. Denmark; John D. Baird



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


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

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



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


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



4E analysis and multi objective optimization of a micro gas turbine and solid oxide fuel cell hybrid combined heat and power system  

NASA Astrophysics Data System (ADS)

Energy, exergy, economic and environmental (4E) analysis and optimization of a hybrid solid oxide fuel cell and micro gas turbine (SOFC-MGT) system for use as combined generation of heat and power (CHP) is investigated in this paper. The hybrid system is modeled and performance related results are validated using available data in literature. Then a multi-objective optimization approach based on genetic algorithm is incorporated. Eight system design parameters are selected for the optimization procedure. System exergy efficiency and total cost rate (including capital or investment cost, operational cost and penalty cost of environmental emissions) are the two objectives. The effects of fuel unit cost, capital investment and system power output on optimum design parameters are also investigated. It is observed that the most sensitive and important design parameter in the hybrid system is fuel cell current density which has a significant effect on the balance between system cost and efficiency. The selected design point from the Pareto distribution of optimization results indicates a total system exergy efficiency of 60.7%, with estimated electrical energy cost 0.057 $kW-1 h-1, and payback period of about 6.3 years for the investment.

Sanaye, Sepehr; Katebi, Arash



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.  


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



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



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.



Electronic and optical properties of silicon based semiconductors with reduced dimension: A theoretical study  

NASA Astrophysics Data System (ADS)

We have developed efficient theoretical methods to study nanoscale silicon-based semiconductor materials. The Si surface, delta-doped Si semiconductors and Si clusters are studied by Density Functional Theory with Local Density Approximation (DFT-LDA) with plane-wave, DFT-LDA with Wannier orbitals and GW approximation. First, on the Hydrogen-passivated Si surface, the migration of Si atoms is studied with FHIMD package. The result shows a special migration path along the surface dimer row. And further calculation shows that clustering is a possible mechanism for the interruption of the homoepitaxial growth of Si in low temperatures. Second, a planar Wannier orbital scheme is formulated to study phosphorus delta-doped Si. The delta-doped Si is studied at various high doping densities, ranging 1/1024 ML ˜ 1/4 ML, which is 6.6 x 1011cm-2˜1.7 x 10 14cm-2. Our result on the experimental 1/4ML doping shows that the Fermi level is 100meV below conduction band minimum, and the short range interaction effect is small. Last, an efficient GWA method is developed to study Hydrogen passivated Si clusters. The method, using basic group theory and the symmetry of the clusters, makes the GW study of nanoclusters possible. The study shows that the bright light emitted from 1-nm SiH clusters comes from the two excitations in the Si29 H24 cluster. In this work, we have successfully studied silicon surface, phosphorus delta-doped silicon, and Hydrogen passivated silicon clusters. To study the systems efficiently, we have developed planar Wannier formula with envelope functions, and GWA formula in symmetrized plane-wave basis. The formulas are successfully applied to the studied materials. Moreover, the methods can be used to study other nano-materials.

Qian, Gefei


Silicon Based Microchemical Concepts for Miniature Fuel Keyur Shah, R.S. Besser  

E-print Network

Ox Microfabricated Vacuum Insulation d: thickness of insulation Kp: Thermal conductivity at given pressure Insulation bonding under vacuum) ANSYS Thermal Simulation of Insulator Packaged with SR Microreactor Micro Steam Steam Reformer Preferential oxidation Methanol Combustor Unconverted H2 from anode of fuel cell Water H2

Besser, Ronald S.


Continuous soil VOCl measurements with automated flux chambers and micro-ECD gas chromatography coupled with the thermal desorption and cooled injection systems  

NASA Astrophysics Data System (ADS)

The volatile organic chlorinated compounds (VOCl) are important components of the global chlorine budget. The origin of VOCl in the environment was for decades thought to be strictly anthropogenic. Over the past decade, a number of studies have however shown that VOCls are naturally formed in soil, and nowadays this source is recognized as a crucial part of the global biogeochemical chlorine cycle. The relative contribution of soil VOCl to the global chlorine cycle is however unclear, a key reason being that monitoring of soil VOCl is complicated by low concentrations and high variability of emission rates. Static chamber deployments coupled with canister gas sampling and gas chromatography (GC) analysis is the most commonly used method for quantifying VOCl emissions. Static chambers are however of limited use for estimating larger scale fluxes since the method is highly labor intensive (leading low sampling frequency). The poor data resolution resulting from these limitations can strongly bias the data extrapolation. Here, we report a method that would allow more continuous and precise VOCl flux measurements. The study has been carried out in a forest in British Columbia, Canada, using automated dynamic chambers and advanced GC technique. The chamber setup is based on a design that previously has been employed and proven successful for carbon dioxide and soil respiration measurements. The method includes a collar permanently inserted into the ground and an attached dome-shaped cover. The air from the closed chamber is pumped through the on-site sampling device. The cover opens and closes automatically between deployments (40 min in average), which helps to minimize the chamber supervision and obtain more continuous data. Soil VOCl concentrations are commonly at the ppt-level, much lower than atmospheric carbon dioxide, so necessary adjustments were made to the chamber system to pre-concentrate the compounds of interest. During each deployment, soil air from the automated chamber was continuously pumped through the glass tubes filled with carbon-based absorbent (Carbotrap 300) to capture and retain VOCl. At the end of each measurement period, the tubes are brought back to the lab, and the content is analyzed by Agilent 7890 GC/micro-ECD coupled with the Gerstel Thermal Desorption System (TDS) and Cooled Injection System (CIS). The ultra sensitive micro-ECD detection and high-efficiency capillary column (Rtx®-VMS, 20m x 0.18mm ID x 1.0µm) allows rapid separation and quantification of the mid-weight VOCl such as chloroform, carbon tetrachloride, 1,1,1-trichloroethane and bromochloromethane. The GC-method dynamic range is linear within 0.1-200.0ng, and the analytical precision is determined to be 4%. The described system can be used for the analysis of soil/atmosphere exchange of VOCl at the detection limit of 1.9ng m-2 h-1, which is far below previously reported average soil emission levels from forest soils. The high precision GC analysis combined with the automatic chambers makes it possible to study the high spatial and temporal variability of soil VOCl fluxes.

Molodovskaya, M. S.; Svensson, T.; Pitts, A.; Delmonte, J.; Nesic, Z.; Oberg, G.



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.


A novel approach to mixed field dosimetry utilizing prototype silicon based P-I-N diodes  

NASA Astrophysics Data System (ADS)

Novel approaches to mixed beam dosimetry are presented, utilizing silicon based semiconductor detectors. The forward voltage drop across the diode is proportional to neutron induced damage caused by the non-ionizing energy losses (NIEL) and correlates with neutron dose. On the other hand, the current produced in the diode is due to both neutron and gamma interactions (ionizing energy losses IEL) and may be correlated with the total dose. A single diode operated in these two modes of operation thus may be used as a twin detector in mixed fields. A special circuitry has been built to read out the voltage drop increase associated with neutron damage. The circuitry allows online monitoring of voltage drop across the diode and the beam target current simultaneously. A pulsed constant current is used to reduce signal variation due to temperature effects. A modified lead attenuation method has been adopted and successfully applied to determine the neutron sensitivity of PIN diodes of different geometry. The sensitivity is given in mV cGy-1 when the diode is operated in voltage drop mode, or in nC cGy-1 when the diode is operated in charge mode. Sensitivity of the diodes to gamma rays was determined from measurements in a 60Co beam. Neutron and gamma doses were measured at 17 different points. The diodes demonstrated good accuracy in measuring neutron and total dose, agreeing to within the stated uncertainties with results obtained with the twin detector method for 14 of the measured points. Discrepancies were noted in the penumbra, where the dose gradient is highest. In measuring the gamma component all methods agree to within stated uncertainties. The largest uncertainty in the measurements is observed when the gamma dose is very small relative to the neutron dose. The proposed detectors offer the advantages of high spatial resolution, simple instrumentation and immediate availability of the measured dose. Most importantly, a single detector can be used for separating dose components in the mixed beam. These features make the diode detectors well suited for a number of applications including in-vivo dosimetry, intensity modulated neutron radiation therapy (IMNRT) and measurements of penumbra.

Alyousef, Khalid A.


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


Self-assembly micro optical filter  

NASA Astrophysics Data System (ADS)

Optical communication and sensor industry face critical challenges in manufacturing for system integration. Due to the assembly complexity and integration platform variety, micro optical components require costly alignment and assembly procedures, in which many required manual efforts. Consequently, self-assembly device architectures have become a great interest and could provide major advantages over the conventional optical devices. In this paper, we discussed a self-assembly integration platform for micro optical components. To demonstrate the adaptability and flexibility of the proposed optical device architectures, we chose a commercially available MEMS fabrication foundry service - MUMPs (Multi-User MEMS Process). In this work, polysilicon layers of MUMPS are used as the 3-D structural material for construction of micro component framework and actuators. However, because the polysilicon has high absorption in the visible and near infrared wavelength ranges, it is not suitable for optical interaction. To demonstrate the required optical performance, hybrid integration of materials was proposed and implemented. Organic compound materials were applied on the silicon-based framework to form the required optical interfaces. Organic compounds provide good optical transparency, flexibility to form filters or lens and inexpensive manufacturing procedures. In this paper, we have demonstrated a micro optical filter integrated with self-assembly structures. We will discuss the self-assembly mechanism, optical filter designs, fabrication issues and results.

Zhang, Ping (Cerina); Le, Kevin; Malalur-Nagaraja-Rao, Smitha; Hsu, Lun-Chen; Chiao, J.-C.



Silicon based nano-architectures for high power lithium-ion battery anodes  

NASA Astrophysics Data System (ADS)

Lithium-ion batteries have now become an inseparable part of modern day society as the power source for several portable electronics like cell phones, digital cameras and laptops. Their high energy density compared with other electrochemical battery systems has been their most attractive feature. This has lead to a great interest in developing lithium-ion batteries for hybrid and all-electric vehicles. Eventually such vehicles will help drastically reduce the carbon footprint making the environment cleaner and healthier. In spite of their high energy density, Li-ion batteries are known to have poor power densities. This forms a major limitation in their deployment as a power source on vehicles. Electric vehicles need power sources that can provide both high energy and power densities. This requires the development of anode, cathode and electrolyte materials that would transform the capabilities of existing Li-ion batteries. Among anode materials silicon has received great attention because of its very large theoretical capacity of ˜4200 mAh/g based on the alloy Li22Si5. It should be noted that storage of charge in the anode occurs through the alloying of Li with the host anode material. However, the large specific capacity of silicon also results in a ˜400% volume expansion which could lead to pulverization and delamination reducing the cycle life of the electrode. These failure processes are exacerbated at high rates making it extremely difficult to use silicon for high-power Li-ion battery anodes. The major research thrust supporting this Ph.D. thesis involved exploring silicon based nano-architectures that would provide high energy and power densities over a long cycle life. The key technique used to design different nano-architectures was DC Magnetron sputtering with oblique angle deposition. The main development of this research was a functionally strain graded Carbon-Aluminum-Silicon nanoscoop architecture for high-power Li-ion battery anodes. This consisted of Carbon nanorods with an intermediate Aluminum layer finally capped by a nanoscoop of Silicon. The strain gradation arises from the fact that each of these materials has differential volumetric expansions due to different extents of Li uptake. Such a strain gradation from Carbon towards Silicon would provide for a less abrupt transition across the material interfaces thereby reducing interfacial mismatch and improving the tolerance to delamination at very high rates. This nano-architecture provided average capacities of ˜412 mAh/g with a power output of ˜100 kW/kg electrode continuously over 100 cycles. Even when the power output was as high as ˜250 kW/kgelectrode, the average capacity over 100 cycles is still ˜90 mAh/g. Furthermore, scanning electron microscopy and X-ray photoelectron spectroscopy investigations revealed that the functionally strain graded nanostructures were being partially lithiated in the bulk even at high rates. The fact that charge storage was not merely a surface phenomenon supported the high energy densities obtained at high charge/discharge rates. In an attempt to improve the mass loading density of Silicon based nano-architectures, a nano-compliant layer (NCL) supported thin film architecture was also explored. This consisted of an array of oblique nanorods (the nano-compliant layer) sandwiched between the substrate and the thin film. The NCL layer was used to improve the stress tolerance of the thin film thereby allowing the use of bulk thin films as opposed to nanostructures. This would directly improve the mass loading density. Silicon films with Carbon NCLs and Carbon films with Silicon NCLs were both deposited and tested. It was found that Li+ diffusivity is higher in carbon than in silicon by at least two orders of magnitude. This was calculated from cyclic voltammetry tests using the Randles-Sevcik equation. This difference in Li+ diffusivity within the two materials was found to be the C-rate limiting factor for a given nano-architecture design.

Krishnan, Rahul


Liquid-crystal-on-silicon-based optical add/drop multiplexer for orbital-angular-momentum-multiplexed optical links.  


We designed an optical add/drop multiplexer for orbital-angular-momentum (OAM)-multiplexed data links by taking advantage of the ring-shaped intensity profile of OAM beams. We demonstrated adding/dropping a single OAM beam from three multiplexed OAM beams using liquid-crystal-on-silicon-based diffraction optical elements. For multiplexed OAM beams carrying 100 Gbit/s quadrature phase-shift-keying data, a power penalty of <2 dB is observed to achieve a bit-error rate of 2.0×10(-3) for each channel of the add/drop multiplexer. PMID:24281530

Huang, Hao; Yue, Yang; Yan, Yan; Ahmed, Nisar; Ren, Yongxiong; Tur, Moshe; Willner, Alan E



Gas Producing Micro-Reaction  

NSDL National Science Digital Library

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

House, The S.



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


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

SciTech Connect

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

Alan Ludwiszewski



A high efficient micro-proton exchange membrane fuel cell by integrating micro-nano synergical structures  

NASA Astrophysics Data System (ADS)

A silicon-based micro-proton exchange membrane fuel cell (?-PEMFC) which carries out an outstanding cell performance and high efficient catalyst utilization ratio is proposed in this paper by the employment of three micro-nano synergical techniques. Firstly, a novel design incorporating multi-walled carbon nano-tubes (MWCNTs) on radial shaped micro-channel walls to form micro/nano reaction chambers which significantly enhance the reaction surface areas for the performance improvement. In the second, the dispensing of ionomer onto the three-phase zones in the reaction chambers is controlled by different rotation speed and the optimized distribution can therefore be achieved for the improvement of catalyst utilization. In the third, the cell interfacial strength is greatly enhanced by the employment of micro-interlocks for maintaining excellent interface between Nafion membrane and reaction chambers while minimizing the system size. A ?-PEMFC is successfully fabricated by integrating aforementioned synergical micro/nano structures altogether. The best cell efficiency is 26 mW cm-2 which corresponds to a catalyst utilization ratio of 38.2 W g-pt-1, and can be considered among the best performed micro-fuel cells.

Peng, Hsien-Chih; Wang, Chung-Nan; Yeh, Tsung-Kuang; Su, Yu-Chuan; Pan, Chin; Tseng, Fan-Gang



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



Micro-liquid flow sensor  

Microsoft Academic Search

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

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



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.



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


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



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



Experiment: Micro Dispersive Suspension Polymerization of MMA.  

E-print Network

Experiment: Micro Dispersive Suspension Polymerization of MMA. Procedures: 1. Prepare PVA solution the weight of plate+solid 12. After finishing the polymerization, turn off the agitator, nitrogen gas

Choi, Kyu Yong


Zeolites and Other Silicon-Based Promoters in Carbohydrate Chemistry ? ? This article is dedicated to Prof. Joachim Thiem on the occasion of his 68th birthday  

Microsoft Academic Search

Silicon-based materials, namely zeolites, clays, and silica gel have been widely used in organic synthesis, allowing mild reaction conditions and environmentally friendly methodologies. These heterogeneous catalysts are easy to handle, possess nontoxic and noncorrosive character and offer the possibility of recovery and reuse, thus contributing to clean and sustainable organic transformations. Moreover, they present shape-selective properties and provide stereo- and

Amélia P. Rauter; Nuno M. Xavier; Susana D. Lucas; Miguel Santos



Possibilities of monitoring the polymerization process of silicon-based water repellents and consolidants in stones through infrared and Raman spectroscopy  

Microsoft Academic Search

The increasing use of Raman and infrared (IR) portable instruments for in situ diagnosis and characterization of materials and their conservation state in artworks, has led us to investigate in the laboratory the real possibilities that both vibrational spectroscopies could have for monitoring in situ and in real time the polymerization process of silicon-based water repellents and consolidants in stones,

Concepción Domingo; Monica Alvarez de Buergo; Santiago Sánchez-Cortés; Rafael Fort; Jose V. García-Ramos; Miguel Gomez-Heras



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-



In-situ deposition of silica layers during the operation of a micro-gas turbine and their effect on the oxidation of superalloy blades  

Microsoft Academic Search

Silica-based oxide layers were deposited in-situ on turbine blades made from Inconel 713 during the operation of a 13 kgf-class gas turbine, and their effect on the ex-situ oxidation behavior of the blades at 1050 °C was examined. The two turbines\\u000a were driven by burning liquid petroleum gas (LPG), one turbine at a rotation speed of 35,000 rpm for 4

Min Tae Kim; Doo Soo Kim; Won Young Oh



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

Microsoft Academic Search

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

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



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

NASA Astrophysics Data System (ADS)

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

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



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.



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.



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.



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


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



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


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



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



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

Microsoft Academic Search

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

Paul M. Holland; Ara Chutjian; Murray R. Darrach; Otto J. Orient



Facile and Scalable Synthesis of Silicon-Based Nanocomposites with Slitlike Nanopores: A Solid-State Exfoliation Reaction Using Layered CaSi2.  


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



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

Microsoft Academic Search

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

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



Microstructure of amorphous-silicon-based solar cell materials by small-angle x-ray scattering. Annual subcontract report, 6 April 1994--5 April 1995  

SciTech Connect

The general objective of this research is to provide detailed microstructural information on the amorphous-silicon-based, thin-film materials under development for improved multijunction solar cells. The experimental technique used is small-angle x-ray scattering (SAXS) providing microstructural data on microvoid fractions, sizes, shapes, and their preferred orientations. Other microstructural features such as alloy segregation, hydrogen-rich clusters and alloy short-range order are probed.

Williamson, D.L. [Colorado School of Mines, Golden, CO (United States)



Characterisation of different types of hay by solid-phase micro-extraction-gas chromatography mass spectrometry and multivariate data analysis.  


The volatile organic compounds of different ground hay samples from Austria, Italy and Switzerland were collected at 50 degrees C on a Supelco Carbowax Divinylbenzene headspace solid-phase microextraction fibre, separated by capillary gas chromatography on an HP5-ms column running a temperature programme and using helium as carrier gas, detected with a mass sensitive detector and studied with principal component analyses after autoscaling selected variables. The analytes, mainly mono- and sesquiterpenes, were able to cluster differences resulting from the site of production. Coumarin can be used to differentiate hay grown north and south of the main chain of the Alps. Acetic acid is appropriate for distinguishing between hay from Kastelruth and Passeier Valley, two South Tyrolean regions. The average linalool content in aftermath is higher than in hay. PMID:18401854

Valtiner, S M; Bonn, G K; Huck, C W



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


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

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



Improved determination of flavour compounds in butter by solid-phase (micro)extraction and comprehensive two-dimensional gas chromatography  

Microsoft Academic Search

The practicability and potential of comprehensive two-dimensional gas chromatography (GC×GC) coupled to both conventional flame ionisation (FID) and time-of-flight mass spectrometric (TOF-MS) detection, were compared with those of conventional one-dimensional (1D) GC, with the determination of flavour compounds in butter as an application. For polar flavour compounds, which were collected from the aqueous fraction of butter by means of solid-phase

Mohamed Adahchour; Jaap Wiewel; Ramon Verdel; René J. J. Vreuls; Udo A. Th. Brinkman



Development, validation and application of a method to analyze phenols in water samples by solid phase micro extraction-gas chromatography-flame ionization detector  

Microsoft Academic Search

In this work the development, validation and application of method using Solid Phase Microexctration (SPME) for the analyses of five pollutants (phenol, 2-nitrophenol, 2,4-dimethylphenol, 2,4-dichlorophenol and 4-chloro, 3-methyl phenol) in supplying water, using gas chromatography (GC) with flame ionization detector (FID) is described. The optimal conditions obtained for SPME were: fiber type: Poliacrylate (PA); extraction time: 40 minutes; extraction temperature:

Fernando M. Lanças; Igor R. B. Olivares; Priscila M. Alves



IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 22, NO. 1, JANUARY 1, 2010 21 Silicon-Based Thermo-Optically Tunable  

E-print Network

silicon dioxide. A 150-nm-thick NiCr micro-heater was placed directly on top of the PhC struc- ture was characterized with a tunable laser light source in the wavelength range of 1500 ~ 1580 nm. Tuning of focal length in this device was experimentally demonstrated by applying different current through the heater

Lee, Jeong-Bong


Design of micro-ring optical sensors and circuits for integration on optical printed circuit boards (O-PCBs)  

NASA Astrophysics Data System (ADS)

We report on the design of micro-ring resonator optical sensors for integration on what we call optical printed circuit boards (O-PCBs). The objective is to realize application-specific O-PCBs, either on hard board or on flexible board, by integrating micro/nano-scale optical sensors for compact, light-weight, low-energy, high-speed, intelligent, and environmentally friendly processing of information. The O-PCBs consist of two-dimensional planar arrays of micro/nano-scale optical wires, circuits and devices that are interconnected and integrated to perform the functions of sensing and then storing, transporting, processing, switching, routing and distributing optical signals that have been collected by means of sensors. For fabrication, the polymer and organic optical wires and waveguides are first fabricated on a board and are used to interconnect and integrate sensors and other micro/ nano-scale photonic devices. Here, in our study, we focus on the sensors based on the micro-ring structures. We designed bio-sensors using silicon based micro-ring resonator. We investigate the characteristics such as sensitivity and selectivity (or quality factor) of micro-ring resonator for their use in bio-sensing application. We performed simulation studies on the quality factor of micro-ring resonators by varying the radius of the ring resonators and the separation between adjacent waveguides. We introduce the effective coupling coefficient as a realistic value to describe the strength of the coupling in micro-ring resonators.

Lee, El-Hang; Lee, Hyun S.; Lee, S. G.; O, B. H.; Park, S. G.; Kim, K. H.



[Determination of ten photoinitiators in fruit juices and tea beverages by solid-phase micro-extraction coupled with gas chromatography/mass spectrometry].  


A method for the determination of ten photoinitiators (PIs), benzophenone, ethyl 4-dimethylaminobenzoate, 1-hydroxycyclohexyl-phenylketone, 4-methylbenzophenone, 2-ethylhexyl-4-dimethylaminobenzoate, 4-chlorobenzophenone, 2-chlorothioxanthone, 2-isopropylthio-xanthone, 2,2-dimethoxy-2-phenylacetophenone, methyl 2-benzoylbenzoate, in 13 kinds of fruit juice and 3 kinds of tea beverage has been established, using solid-phase micro-extraction (SPME) combined with chromatography/mass spectrometry (GC/MS). At first, the major factors of SPME, extraction time and temperature, were studied through orthogonal experiment. Then the optimal operation conditions were obtained via the refinement of various factors. After the sample was extracted by SPME, it was desorbed for target analytes in sampling inlet for 3 min, and separated on an HP-5MS column, then detected by MS in selected ion monitoring mode, and quantified through calibration curve. The working curves were obtained using sample matrix in order to eliminate the matrix interference. The linear range was from 0.3 microg/L to 60 microg/L and the detection limit range was from 3 ng/L to 16 ng/L. The samples were determined five times with four different spiked levels individually and the relative standard deviations of all the samples were less than 14.5%. This determination method was applied in 16 kinds of packed beverages with different brands and different species. Benzophenone had been detected from all the samples. 4-Methylbenzophenone, 2-ethylhexyl-4-dimethylaminobenzoate, 2-isopropylthioxanthone, 1-hydroxycyclohexyl-phenylketone and 2-chlorothioxanthone had been detected from a portion of samples. Simultaneous determination was achieved for the ten PIs. These results provide a reference to determine the PIs migrated from packing materials in beverage. This method is simple, high sensitive and non-polluting. PMID:24669718

Liu, Pengyan; Chen, Yanjie; Zhao, Chunxia; Tian, Lei



Design and prototyping of micro centrifugal compressor  

Microsoft Academic Search

In order to establish the design methodology of ultra micro centrifugal compressor, which is the most important component\\u000a of ultra micro gas turbine unit, a 10 times of the final target size model was designed, prototyped and tested. The problems\\u000a to be solved for downsizing were examined and 2-dimensional impeller was chosen as the first model due to its productivity.

Shimpei Mizuki; Gaku Minorikawa; Toshiyuki Hirano; Yuichiro Asaga; Naoki Yamaguchi; Yutaka Ohta; Eisuke Outa



Integrated Microfluidic Gas Sensors for Water Monitoring  

NASA Technical Reports Server (NTRS)

A silicon-based microhotplate tin oxide (SnO2) gas sensor integrated into a polymer-based microfluidic system for monitoring of contaminants in water systems is presented. This device is designed to sample a water source, control the sample vapor pressure within a microchannel using integrated resistive heaters, and direct the vapor past the integrated gas sensor for analysis. The sensor platform takes advantage of novel technology allowing direct integration of discrete silicon chips into a larger polymer microfluidic substrate, including seamless fluidic and electrical interconnects between the substrate and silicon chip.

Zhu, L.; Sniadecki, N.; DeVoe, D. L.; Beamesderfer, M.; Semancik, S.; DeVoe, D. L.



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.


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


We developed an apparatus to couple a 50-?m diameter whispering-gallery silica microtoroidal resonator in a helium-4 cryostat using a straight optical tapered-fiber at 1550 nm wavelength. On a top-loading probe specifically adapted for increased mechanical stability, we use a specifically-developed "cryotaper" to optically probe the cavity, allowing thus to record the calibrated mechanical spectrum of the optomechanical system at low temperatures. We then demonstrate excellent thermalization of a 63-MHz mechanical mode of a toroidal resonator down to the cryostat's base temperature of 1.65 K, thereby proving the viability of the cryogenic refrigeration via heat conduction through static low-pressure exchange gas. In the context of optomechanics, we therefore provide a versatile and powerful tool with state-of-the-art performances in optical coupling efficiency, mechanical stability, and cryogenic cooling. PMID:23635182

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



Micro-machined thermo-conductivity detector  


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)



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



Study of the Influence of Construction Materials on the Ageing Properties of High Rate Gas Detectors  

NASA Astrophysics Data System (ADS)

An infrastructure has been set up at the GSI detector laboratory to study the in?uence of construction materials on the ageing properties of gas ?lled detectors such as multi wire proportional chambers (MWPC), gas electron multipliers (GEM) etc. As a ?rst step an ageing test of silicone-based glue (RTV-3145)(Dow Corning) has been performed. In this article details of the experimental set-up and the ?rst result on (RTV3145) will be presented.

Abuhoza, Alhussain; Biswas, S.; Frankenfeld, U.; Hehner, J.; Schmidt, C. J.; Schmidt, H. R.


Novel applications for micro-SOFCs  

NASA Astrophysics Data System (ADS)

The application of micro-solid oxide fuels cells in small systems is discussed. Two types of application are examined, namely, leisure CHP systems and micro-hybrid vehicles. A unique triple layer catalyst-SOFC-catalyst system has been designed utilising propane/butane fuel. The system consists of a co-generating gas burner with a pre-reforming catalyst, a micro-SOFC stack and an oxidation catalyst. The pre-reforming catalyst comprising of Ru metal on Saffil® ceramic wool, was used to partially reform the propane/butane gas prior to entering the fuel cell, preventing carbon formation. The micro-SOFCs were YSZ tubes (Adelan, UK) with nickel/YSZ cermet anodes on the outside and strontium-doped lanthanum manganite cathodes on the inside. Final oxidation was provided by a cordierite honeycomb coated with platinum combustion catalyst producing most of the heat for the fuel cell operation. Initial performance results were obtained and it was shown that a co-generating system could be achieved using a propane/butane fuel supply, piezoelectric ignition system and air supply for the triple catalyst system. The application of this micro-SOFC system for leisure and micro-hybrid vehicles, such as golf trolleys and power-assisted bicycles, is described.

Tompsett, G. A.; Finnerty, C.; Kendall, K.; Alston, T.; Sammes, N. M.


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



Design and fabrication of a cross flow micro heat exchanger  

Microsoft Academic Search

A cross flow micro heat exchanger was designed to maximize heat transfer from a liquid (water-glycol) to a gas (air) for a given frontal area while holding pressure drop across the heat exchanger of each fluid to values characteristic of conventional scale heat exchangers. The predicted performance for these plastic, ceramic, and aluminum micro heat exchangers are compared with each

Chad Harris; Mircea Despa; Kevin Kelly




E-print Network

. In particular, the paper is focused on micro fluidic systems for the purification of cells, uncoated nano such as the micro columns used in the miniaturized chromatographic systems (e.g. electrophoresis, gas chromatography, liquid chromatography) or the chambers used for miniaturized polymerase chain reaction (PCR) systems


Micro-patterned interfaces affecting transport through and along membranes  

Microsoft Academic Search

It is the objective of this thesis to describe how micro-patterned polymeric surfaces can lead to enhanced transport through and along those surfaces. The main focus is on increasing the flux in membrane processes. For gas permeation, micro-lines in a dense polymer can increase the mass transport compared to flat membranes with the same polymer volume. Finite element simulations prove

Alisia Mariska Peters



Boiling of nuclear liquid in the micro-canonical ensemble  

E-print Network

Boiling of nuclear liquid in the micro-canonical ensemble K. Miyazaki E-mail: Abstract New calculus of the liquid-gas phase transition is developed for the boiling of nuclear liquid-dependence of the nuclear symmetry energy and the critical temperature of 1 #12;Boiling of nuclear liquid in the micro


Thermal measurement and analysis of micro devices using thermography  

Microsoft Academic Search

Sensors and actuators become much smaller as parts of MEMS devices. Some of them run based on the thermal principle and thermal characteristics directly determine their performance. For example, micro-hotplate structures are incorporated into integrated gas sensors to heat the sensing thin film to a determinate temperature with a high sensitivity. The micro-machined accelerometer with no proof mass is based

Y. Q. Gu; Ronghai Zhang; Dezhong Zhu



Room temperature micro-hydrogen-generator  

Microsoft Academic Search

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

Don Gervasio; Sonja Tasic; Frederic Zenhausern



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



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


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

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



Performance of large area Micro Pixel Chamber  

E-print Network

A novel gaseous two-dimensional imaging detector "Micro Pixel Chamber (micro-PIC)" has been developed. This detector is based on double sided printed circuit board (PCB). We have developed large area (10cm x 10cm) micro-PICs with 65536 pixel anodes of 400um pitch on a 100um thick insulating substrate. Achieved energy resolution was 30% (FWHM) at 5.9keV, and a gas gain of 7000 was obtained with argon ethane (8:2) gas mixture. This gain is high enough to detect minimum ionizing particles with such a small electrode pitch. Although several discharges occurred during 65 hours continuous operation, the detectors have kept stable operation with high gain. The micro-PIC is a useful detector for many applications e.g. X-ray, gamma ray, and charged particle imaging. The micro electrode structure allows us to measure directions of primary electrons due to incident X-rays or gamma rays, which provide a strong method for X-ray polarimetry and gamma-ray imaging.

T. Nagayoshi; H. Kubo; K. Miuchi; A. Ochi; R. Orito; A. Takada; T. Tanimori; M. Ueno



Microstructure of amorphous-silicon-based solar cell materials by small-angle x-ray scattering. Annual technical report, April 6, 1995--April 5, 1996  

SciTech Connect

The objective of this project is to provide detailed microstructural information on the amorphous silicon based thin film materials under development for improved multijunction solar cells. Correlation of microstructure with opto-electrical properties and device performance is an integral part of the research. During this second phase of our three-year program we have obtained information on the microstructure of materials relevant to the Low-, Mid-, and High-bandgap Teams and the results are appropriately divided into these three types of material as presented below. The experimental methods, data analysis, and interpretation procedures are the same as those described in detail in the phase-one report and in the review paper published last year.

Williamson, D.L. [Colorado School of Mines, Golden, CO (United States)



Improved sensing performance of polycrystalline-silicon based dual-gate ion-sensitive field-effect transistors using high-k stacking engineered sensing membrane  

NASA Astrophysics Data System (ADS)

Improved sensing performance, larger pH sensitivity that breaches the Nernst response limit with excellent stability, was realized on polycrystalline silicon based dual-gate (DG) ion-sensitive field-effect transistors. The capacitive coupling between the top and bottom gate oxides for a DG operation amplified its sensitivity to as high as 325.8 mV/pH. In particular, the SiO2/HfO2/Al2O3 (OHA) layer, proposed as an engineered sensing membrane, significantly reinforced the sensing margin of devices as well as the chemical stability for long-term use. The sensing characteristics of the OHA and conventional SiO2 layer were evaluated for single gate and DG operation modes, respectively.

Jang, Hyun-June; Bae, Tae-Eon; Cho, Won-Ju



A lithium-ion sulfur battery based on a carbon-coated lithium-sulfide cathode and an electrodeposited silicon-based anode.  


In this paper, we report a lithium-ion battery employing a lithium sulfide cathode and a silicon-based anode. The high capacity of the silicon anode and the high efficiency and cycling rate of the lithium sulfide cathode allowed optimal full cell balance. We show in fact that the battery operates with a very stable capacity of about 280 mAh g(-1) at an average voltage of 1.4 V. To the best of our knowledge, this battery is one of the rare examples of lithium-metal-free sulfur battery. Considering the high theoretical capacity of the employed electrodes, we believe that the battery here reported may be of potential interest as high-energy, safe, and low-cost power source for electric vehicles. PMID:24559093

Agostini, Marco; Hassoun, Jusef; Liu, Jun; Jeong, Moongook; Nara, Hiroki; Momma, Toshiyuki; Osaka, Tetsuya; Sun, Yang-Kook; Scrosati, Bruno



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.



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


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

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



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


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




MicroSight Optics  


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




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.  


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



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


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 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)



An Autonomous Gliding Micro  

E-print Network

An Autonomous Palm-Sized Gliding Micro Air Vehicle 1070-9932/07/$25.00©2007 IEEEIEEE Robotics micro air vehicle (MAV) with the final goal of locating and flying toward a target while avoiding composite microstructures, high performance microactuators, low power biomimetic sen- sors, and efficient

Sanders, Seth


Search for Bs0 --> micro+ micro- and B0 --> micro+ micro- decays with 2 fb-1 of pp collisions.  


We have performed a search for B(s)(0) --> micro(+) micro(-) and B(0) --> micro(+) micro(-) decays in pp collisions at square root s = 1.96 TeV using 2 fb(-1) of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron Collider. The observed number of B(s)(0) and B0 candidates is consistent with background expectations. The resulting upper limits on the branching fractions are B(B(s)0) --> micro(+) micro(-)) <5.8 x 10(-8) and B(B(0) --> micro(+) micro(-))<1.8 x 10(-8) at 95% C.L. PMID:18352173

Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'orso, M; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Genser, K; Gerberich, H; Gerdes, D; Giagu, S; Giakoumopolou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; Macqueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oh, S H



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



Microplasmas and micro-jets  

NASA Astrophysics Data System (ADS)

Microplasmas are now widely investigated, one of their advantages being to generate a plasma at relatively high pressure close to the Paschen minimum (Schoenbach et al. 1997). Here, the microplasma is generated in a microhollow cathode type configuration made of a hole drilled through a metal/dielectric/metal sandwich (Schoenbach et al. 1997). One of the electrodes acts as the cathode (K) and the other as the anode (A1). The hole diameter ranges from 100 to 400 mu m and the pressure ranges from 50 to 500 Torr. When a second electrode (A2) is added, a large volume of plasma plume may be generated between A1 and A2, at a low electric field (1-20Td depending upon the gas) (Stark et al. 1999). A microhollow cathode type discharge operates in three different regimes depending on the plasma current: abnormal, self-pulsing and normal regime. The self-pulsing regime is achieved in the range of 1-100 kHz, in argon, helium, nitrogen and oxygen. The self-pulsing frequency is controlled by the microplasma device capacitance, the gas breakdown voltage, and the average discharge current (Rousseau et al. 2006, Aubert et al. 2007). i) First, in pure argon, the radial dependence of atoms excitation mechanisms and of the electronic density is studied inside the micro-hole. Imaging of the emission from the microplasma is performed with a spatial resolution of few mu m. The electron density is estimated from the Stark broadening of the H beta-line. The radial distribution of the emission intensities of an Ar atomic line and an Ar^+ ionic line are used for the excitation study. Ar and Ar^+ lines are excited in the cathode sheath edge by beam electrons accelerated within the sheath. These two excitations show the decay of the energy of electrons in negative glow. The Ar line presents also production of excited atoms by recombination of argon ions with electrons at the center of the micro-hole.Work is in progress to evaluate the contribution of the static electric field on the strak broadening ii) Second, in oxygen containing mixture, a flowing micro-jet is generated: the reactor used is separated in 2 rooms by the MHC. Thus, the gas is constrained to flow only through the microhole and the quantity of treated gas is well known. The gas flow is supersonic in most operating conditions at the exit of the microhole; despite a very large injected power density (typically 10^4 W cm^-), the gas heating does not exceed few hundreds of degrees, so that the plasma is non equilibrium. Different measurements are realized on the plume in pure O_2 and in Air. O_3 concentration has been measured by UV absorption spectroscopy; NO and NO_2 have been measured by tuneable diode laser absorption spectroscopy (TDLAS) in the infrared region (Ropcke et al. 2006). The production of NO and NO_2 in air mixture scales as universal function of the injected power, independently of the working regime (continuous or self-pulsing).

Lazzaroni, C.; Aubert, X.; Marinov, D.; Guaitella, O.; Stancu, G.; Welzel, S.; Pipa, A.; Ropcke, J.; Sadeghi, N.; Rousseau, A.



Narrow Bandstop Filters with Wide and Flattened Sidebands Using Silicon-Based and Suspended Membrane Type of Guided-Mode Resonance Structures  

NASA Astrophysics Data System (ADS)

In this paper, the simple two-layer silicon-based and suspended-membrane-type guided-mode resonance (GMR) filter with a narrow bandstop spectrum as well as wide and flattened sidebands is experimentally demonstrated. The proposed filter based on a free-standing silicon nitride membrane suspended on a silicon substrate is realized by using the anisotropic wet etching to remove the substrate beneath the silicon nitride layer. Both of grating and waveguide structures are fabricated simultaneously on a silicon nitride membrane. Moreover, the silicon dioxide membrane playing a role on modifying the spectral response of proposed GMR filter is deposited beneath the free-standing silicon nitride layer. The resonance wavelength of proposed band-stop filter is controlled at 1580.6 nm with a bandwidth less than 0.92 nm, measured in full-width at half-maximum (FWHM). The improved spectral performance including the sideband can be extended to be 415 nm with the maximum transmittance greater than 93%.

Chang, Chia-Chi; Lan, Hsiao-Chin; Hsiao, Hsu-Liang; Jheng, Jhong-Wei; Lu, I.-Chun; Lee, Yun-Chih; Wu, Mount-Learn



Design of a compact silicon-based slot-waveguide crossing composed of an orthogonal strip multimode waveguide and four logarithmical mode converters  

NASA Astrophysics Data System (ADS)

A compact silicon-based slot-waveguide crossing composed of a slot-to-strip mode converter (at each port) and an orthogonal strip multimode waveguide (SMW) is proposed and designed using a finite difference time domain method. With the mode converter based on logarithmically transitional tapers, the guided modes of the input slot waveguide are efficiently transformed to those of a strip one, and then enter into the SMW, where the fields converge at the centre of the intersection due to the self-imaging effect. As a result, the size of the input beam is much smaller than the width of the SMW at the crossing centre, leading to significant reductions in the crosstalk and radiation loss. The numerical results show that a slot-waveguide crossing operating at a wavelength of 1.55 µm with insertion loss, crosstalk and reflection of 0.131 dB, -37.44 dB and -35.47 dB, respectively, is achieved. Moreover, the fabrication tolerances to the structural parameters are investigated in detail. And the evolution of the injected field along the propagation distance through the slot-waveguide crossing is also demonstrated.

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



Development of micro pixel chamber  

NASA Astrophysics Data System (ADS)

The novel gaseous detector "Micro Pixel Chamber (?-PIC)" has been developed for X-ray, gamma-ray and charged particle imaging. The ?-PIC is made based on a double-sided printing circuit board, by which a large size detector could be produced easily. The operation tests were performed successfully using a 3 cm×3 cm ? -PIC with a 0.4 mm pitch. The gas gain and stability were measured in these tests. There is neither gain reduction nor discharge between anode and cathode at a gain of 10 3 for 5 days continuous operation. Also, no gain decrease was observed up to 10 7 cps(counts per second)/mm 2 intense X-ray irradiation.

Ochi, Atsuhiko; Nagayoshi, Tsutomu; Koishi, Satoshi; Tanimori, Toru; Nagae, Tomofumi; Nakamura, Mirei



Thin film micro carbon dioxide sensor using MEMS process  

Microsoft Academic Search

Pt\\/Na+ ion conductive ceramic thin film\\/Pt\\/carbonate (Na2CO3:BaCO3=1:1.7mol) system CO2 micro gas sensor was fabricated and the sensing properties were investigated. The Na+ ion conductive thin film was prepared by RF magnetron sputtering method. The thin film micro carbon dioxide sensor was prepared by using silicon process combined with MEMS technology.A NASICON thin film (2000–2500Å) as main layer of the device

Yeung-Il Bang; Kap-Duk Song; Byung-Su Joo; Jeung-Soo Huh; Soon-Don Choi; Duk-Dong Lee



Digital MicroPropulsion  

Microsoft Academic Search

Arrays of “Digital Propulsion” micro-thrusters have been fabricated and tested. A three-layer sandwich is fabricated containing micro-resistors, thrust chambers, and rupture diaphragms. A propellant is loaded into the chambers, which are then sealed. When the resistor is heated sufficiently, the propellant ignites raising the pressure in the chamber and rupturing the diaphragm. An impulse is imparted as the high-pressure fluid

S. W. Janson; R. B. Cohen; E. K. Antonsson



Power MEMS 2007, Nov. 28-29, 2007, Freiburg, Germany Fig. 1: Micro quartz combustor. (a) Schematic,  

E-print Network

to the deactivation of catalyst at higher temperature [2]. Micro-scale gas-phase combustor, if feasible, is beneficial a gas cylinder, and air is introduced from a compressor. The CH4 and air flow rates are separately

Kasagi, Nobuhide


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



Micromachined thin-film gas flow sensor for microchemical reactors  

E-print Network

by the emergence of MEMS (Micro Electro Mechanical Systems). Miniaturization of sensors has enabled many new sensors [5], micro heaters [5,8], micro pressure sensors [5], etc. As an early example of a MEMSMicromachined thin-film gas flow sensor for microchemical reactors W C Shin and R S Besser New

Besser, Ronald S.


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


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



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)



Experimental investigation on heat loss and combustion in methane\\/oxygen micro-tube combustor  

Microsoft Academic Search

To understand working features of a micro-tube combustor, combustion of CH4\\/O2 was carried out in three types of micro-tubes with the same outer diameter of 3mm. In the tests, combustion characteristics and heat loss in micro-tubes were studied. It is shown that when equivalence ratio was lower than unity, CH4 was not completely oxidized and a great amount of gas

Junwei Li; Beijing Zhong



Micro eddy current testing by micro magnetic sensor array  

Microsoft Academic Search

A micro Eddy Current Testing (ECT) system for planar thin specimens made of INCONEL 600 with flaws was proposed and developed. A micro ECT probe used here consists of a conventional pancake-type coil as an exciting coil and a micro magnetic sensor array as a set of pickup coils. Magnetic field perturbation due to a flaw was measured with high

Mitsuru Uesaka; Takahiro Nakanishi; Kenzo Miya; Hidenobu Komatsu; Kazuhiko Aoki; Kazuo Kasai



Method of Manufacturing Micro-Disperse Particles of Sodium Borohydride  


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)



Micro32 Fred Microarchitecture  

E-print Network

And, only constrained by cost & mfg limits But how efficiently did we use the transistors? #12; int e of a Square Law #12; int e lâ â Micro32 Fred Pollack 5 Power Efficiency Power is proportional to Die­plate power density in 0.5µ µ Not too long to reach nuclear reactor Hot plate Nuclear Reactor

John, Lizy Kurian


The Micro-Shop.  

ERIC Educational Resources Information Center

To reduce teacher isolation and encourage sharing of expertise, schools should consider brief workshops or 15-minute "micro-shops" on various topics ranging from making electrical circuit boards to setting up a salt-water aquarium. This article and accompanying sidebar discuss benefits and set-up strategies. (MLH)

Steele, Barbara



Multistage thermoelectric micro coolers  

Microsoft Academic Search

Multistage thermoelectric coolers have been used for a long time because they offer a larger temperature difference than single stage thermoelectric coolers. MEMS technology leads to the possibility to fabricate multistage thermoelectric micro coolers in batches without much increase in complexity compared to single stage cooler fabrication. In this paper, we discuss the design of multistage thermoelectric coolers to optimize

Ronggui Yang; C. Gang; G. J. Snyder; J.-P. Fleurial



Optimum Design of Micro Bare-Tube Heat Exchanger Tomohisa OKU, Nobuhide KASAGI and Yuji SUZUKI  

E-print Network

Department of Mechanical Engineering, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-8656, Japan, optimum design is made for three types of micro bare-tube heat exchangers, i.e., heater core and radiator for automobiles, electronic equipement cooling system, and recuperator for micro gas turbine. Key words : Heat

Tokyo, University of


Breakthrough: micro-electronic photovoltaics  


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



Autonomous, agile micro-satellites and supporting technologies  

SciTech Connect

This paper updates the on-going effort at Lawrence Livermore National Laboratory to develop autonomous, agile micro-satellites (MicroSats). The objective of this development effort is to develop MicroSats weighing only a few tens of kilograms, that are able to autonomously perform precision maneuvers and can be used telerobotically in a variety of mission modes. The required capabilities include satellite rendezvous, inspection, proximity-operations, docking, and servicing. The MicroSat carries an integrated proximity-operations sensor-suite incorporating advanced avionics. A new self-pressurizing propulsion system utilizing a miniaturized pump and non-toxic mono-propellant hydrogen peroxide was successfully tested. This system can provide a nominal 25 kg MicroSat with 200-300 m/s delta-v including a warm-gas attitude control system. The avionics is based on the latest PowerPC processor using a CompactPCI bus architecture, which is modular, high-performance and processor-independent. This leverages commercial-off-the-shelf (COTS) technologies and minimizes the effects of future changes in processors. The MicroSat software development environment uses the Vx-Works real-time operating system (RTOS) that provides a rapid development environment for integration of new software modules, allowing early integration and test. We will summarize results of recent integrated ground flight testing of our latest non-toxic pumped propulsion MicroSat testbed vehicle operated on our unique dynamic air-rail.

Breitfeller, E; Dittman, M D; Gaughan, R J; Jones, M S; Kordas, J F; Ledebuhr, A G; Ng, L C; Whitehead, J C; Wilson, B



Research on high-band-gap materials and amorphous-silicon-based solar cells. Annual subcontract report, May 15, 1994--May 14, 1995  

SciTech Connect

We have conducted a survey of thin BP:H and BPC:H films prepared by plasma deposition using phosphine, diborane, tri-methylboron, and hydrogen as precursor gases. The objective of this research is to find out whether such films might offer a superior window layer film for application to wide bandgap a-Si solar cells. The research has shown good optical properties in a-BP:H films, but electrical properties acceptable for use in window layers have not been demonstrated yet. We have also found an interesting, conductive and transparent BPC:H film in a remote deposition region of the reactor, but have been unable to transfer deposition of this film to the standard interelectrode region. We have developed our capability to deposit nip sequence amorphous silicon based solar cells, and have demonstrated an open circuit voltage greater than 0.7 V. We have continued our studies of built-in potentials in a-Si based solar cells using the electroabsorption technique, extending our measurements to include cells with wider bandgap intrinsic layers and Schottky barrier test structures. We have made the first time-of-flight drift mobility measurements on a-Si:H prepared by hot wire (HW) deposition. Initial work has shown that light-soaked HW material can have much better ambipolar diffusion lengths than the plasma-deposited material following extended light soaking. We have performed some theoretical work which addresses a difficulty in understanding photocarrier recombination in a-Si:H first identified by Marvin Silver. In particular, electron-hole recombination is much slower than expected from the well-known {open_quotes}diffusion-controlled{close_quotes} models for Onsager (geminate) recombination and Langevin recombination. This slowness is essential to the success of a-Si in solar cells, but is unexplained. We have done work on high field electron drift mobilities in a-Si:H and on the validity of the Einstein relation connecting the diffusion and drift of holes in a-Si:H.

Schiff, E.A.; Gu, Q.; Jiang, L.; Wang, Q. [Syracuse Univ., NY (United States)



Expanders for micro-CHP systems with organic Rankine cycle  

Microsoft Academic Search

The continual increases in global energy demand and greenhouse gas emissions call for more and more utilisation of sustainable energy sources, such as solar energy, biomass energy, and waste heat. Solar thermal energy, the heat of biomass combustion and waste heat may be used to drive a combined heat and power (CHP) system. In recent years, several micro-CHP systems with

Guoquan Qiu; Hao Liu; Saffa Riffat



Micro Turbines from the Standpoint of Potential Users  

Microsoft Academic Search

This paper describes some micro turbine aspects from the standpoint of potential users. First, some of the pros and the cons of small gas turbines compared to other competing technologies are given. The discussed aspects are mainly focussed on technical advantages and disadvantages as it is hard to predict how fast and to what extent the different technologies (including that

Ir Roland Decuypere; Dries Verstraete



Methods and systems for micro bearings  


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.



Fabrication and evaluation of a free molecule micro-resistojet with thick silicon dioxide insulation and suspension  

NASA Astrophysics Data System (ADS)

A silicon free molecule micro-resistojet (FMMR) with a thermally insulating suspension frame composed of silicon dioxide has been designed, fabricated and tested. The concept was developed to increase the efficiency of FMMRs, especially in silicon-based integrated systems. Fabrication of the thick insulating frame was performed through oxidation of high-aspect ratio silicon trenches. The thermal properties of the 1 cm2 thruster were evaluated using an IR camera, and it was found that when the volume inside the frame is heated more than 200 °C using integrated nickel heaters, the temperature increase in the volume outside the frame is less than 50 °C. During operation in vacuum, the thrust range was calculated to be about 13-1070 µN and the maximum specific impulse 54 s. At maximum thrust, and a power consumption of 1.6 W, the total efficiency of the thruster was 17%. Designs of more efficient and versatile systems are discussed.

Palmer, Kristoffer; Nguyen, Hugo; Thornell, Greger




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.



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.



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




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.



Micro pulse lidar  

Microsoft Academic Search

An eye safe, compact, solid-state lidar for profiling atmospheric cloud and aerosol scattering is described. The transmitter of the micro pulse lidar is a diode pumped microjoule pulse energy, high-repetition-rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver uses a photon counting solid-state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler.

J. D. Spinhirne



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



Zinc oxide micro-spheres with faceted surfaces produced by laser ablation of zinc targets  

NASA Astrophysics Data System (ADS)

We report the fabrication of ZnO micro-spheres using high-power laser ablation of Zn metal in the presence of oxygen gas background without use of any catalysts or additives. The centre-symmetric geometrical structures of ZnO micro-spheres exhibit clear pentagonal and hexagonal facets with different sizes. A discussion of the growth mechanisms based on a model of subsurface micro-explosion boiling followed by laser-surface sintering of assembled particles has been proposed to explain the formation of the ZnO micro-spheres.

Chen, Ming; Liu, Xiangdong; Liu, Yuehua; Zhao, Mingwen



QUBiC4plus: a cost-effective BiCMOS manufacturing technology with elite passive enhancements optimized for 'silicon-based' RF-system-in-package environment  

Microsoft Academic Search

QUBiC4plus is a RF-BiCMOS production technology tailored for 'silicon-based' RF-SiP. The device menu includes 3 varactor styles, 7 resistor types, novel complimentary 24 V PMU devices, hi-k MIM capacitors, RC-triggered ESD protection and a choice between all-silicon, SiGe and SiGe:C bipolar transistors. Buried-p+ guardrings, DTI and very-high resistivity substrates ensure excellent circuit-block isolation and high-quality inductors. The advanced design flow

P. Deixler; T. Letavic; T. Mahatdejkul; Y. Bouttement; R. Brock; P. C. Tan; V. Saikumar; A. Rodriguez; R. Colclaser; P. Kellowan; H. Sun; N. Bell; D. Bower; A. Yao; R. van Langevelde; T. Vanhoucke; W. D. van Noort; G. A. M. Hurkx; D. Crespo; C. Biard; S. Bardy; J. W. Slotboom



Sagnac loop mirror and micro-ring based laser cavity for silicon-on-insulator.  


An integrated laser is a key component in silicon based photonic integrated circuits. Beyond incorporating the gain medium, on-chip cavity design is critical to device performance and yield. Typical recent results involve cavities utilizing distributed Bragg gratings that require ultra-fine feature sizes. We propose to build laser cavity on silicon using a Sagnac loop mirror and a micro-ring wavelength filter for the first time. The Sagnac loop mirror provides broadband reflection, which is simple to fabricate, has an accurately-controlled reflectivity, and negligible excess loss. Single-mode operation is achieved with the intra-cavity micro-ring filter and, using a 248 nm stepper, the laser wavelength can be lithographically controlled within a standard deviation of 3.6 nm. We demonstrate a proof-of-concept device lasing at 1551.7 nm, with 44 dB SMSR, 1.2 MHz linewidth and 4.8 mW on-chip output power. PMID:25089407

Zhang, Yi; Yang, Shuyu; Guan, Hang; Lim, Andy Eu-Jin; Lo, Guo-Qiang; Magill, Peter; Baehr-Jones, Tom; Hochberg, Michael



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.



Micro-column plasma emission liquid chromatograph  


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)



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



Design of micro distribution systems consisting of long channels with arbitrary cross sections  

NASA Astrophysics Data System (ADS)

Gas flows through long micro-channels of various cross sections have been extensively investigated over the years both numerically and experimentally. In various technological applications including microfluidics, these micro-channels are combined together in order to form a micro-channel network. Computational algorithms for solving gas pipe networks in the hydrodynamic regime are well developed. However, corresponding tools for solving networks consisting of micro-channels under any degree of gas rarefaction is very limited. Recently a kinetic algorithm has been developed to simulate gas distribution systems consisting of long circular channels under any vacuum conditions. In the present work this algorithm is generalized and extended into micro-channels of arbitrary cross-section etched by KOH in silicon (triangular and trapezoidal channels with acute angle of 54.74°). Since a kinetic approach is implemented, the analysis is valid and the results are accurate in the whole range of the Knudsen number, while the involved computational effort is very small. This is achieved by successfully integrating the kinetic results for the corresponding single channels into the general solver for designing the gas pipe network. To demonstrate the feasibility of the approach two typical systems consisting of long rectangular and trapezoidal micro-channels are solved.

Misdanitis, S.; Valougeorgis, D.



Micro-/nanofluidics based cell electroporation.  


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



Space project IONOSAT- MICRO - goals and realization  

NASA Astrophysics Data System (ADS)

The IONOSAT-MICRO project is a first stage of IONOSAT program devoted to the multi-point global monitoring of dynamic processes in the ionosphere. The IONOSAT program is planned to be realized in 2015-2020 with the help of three satellites at coordinated low Earth orbits (LEO). IONOSAT-MICRO is the forerunner project scheduled for launch in 2014 at sun-synchronous orbit with the aim to test the IONOSAT mission scientific postulates and preliminary collection of related space data. The main goal of the IONOSAT-MICRO project is the systematic study of the dynamic response of the ionosphere to the influence "from above" (sun, geomagnetic activity) and "from below" (powerful meteorological, seismic and anthropogenic impacts). More in details, the study of following formations in the ionosphere is foreseen: - Space-temporal structure and global distribution of inhomogeneities in neutral atmosphere and ionosphere; - Global structure and dynamics of quasi-stationary electric currents, electric and magnetic fields; - Wave structures and turbulences at different spatial and temporal scales. To realize such a research, the scientific payload of the MICROSAT spacecraft will provide the measurements of following parameters: - Neutral gas and plasma parameters - concentration, temperature; - DC-ELF-VLF electromagnetic field vectors and ELF-VLF plasma current fluctuations; - Total electron content (TEC); - Spectral content of plasma oscillations. Synchronous experiments with ground support facilities - both active and passive ones - are also foreseen. The IONOSAT-MICRO project will be realized onboard of MICROSAT microsatellite platform, manufactured by Yuzhnoye Design Office with new experimental models of ammonia propulsion system, battery, solar arrays and panels with thermal control coating, the in-flight tests of which are also planned in frames of the project. The composition of the scientific equipment developed by the international team of participants and sensors positioning at the platform will be reported. These works are supported by STCU project No 5567 and SSAU contract No 1-16/12.

Korepanov, Valery; Lizunov, Georgii; Fedorov, Oleg



Performance of large area Micro Pixel Chamber  

NASA Astrophysics Data System (ADS)

A novel gaseous two-dimensional imaging detector "Micro Pixel Chamber (?-PIC)" has been developed. This detector is based on double sided printed circuit board (PCB). We have developed large area (10 cm×10 cm) ?-PICs with 65536 pixel anodes of 400 ?m pitch on a 100 ?m thick insulating substrate. Achieved energy resolution was 30% (FWHM) at 5.9 keV, and a gas gain of 7000 was obtained with argon ethane (8:2) gas mixture. This gain is high enough to detect minimum ionizing particles with such a small electrode pitch. Although several discharges occurred during 65 h continuous operation, the detectors have kept stable operation with high gain. The ?-PIC is a useful detector for many applications e.g. X-ray, gamma ray, and charged particle imaging. The micro electrode structure allows us to measure directions of primary electrons due to incident X-rays or gamma rays, which provide a strong method for X-ray polarimetry and gamma-ray imaging.

Nagayoshi, Tsutomu; Kubo, Hidetoshi; Miuchi, Kentaro; Ochi, Atsuhiko; Orito, Reiko; Takada, Atsushi; Tanimori, Toru; Ueno, Masaru



Formation of titanium carbide coating with micro-porous structure  

NASA Astrophysics Data System (ADS)

Micro-porous titanium carbide coating was successfully synthesized in a vacuum gas carburizing furnace by using a sequential diffusion technology. The composition and structure of the as-synthesized TiC were examined by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and glow discharge mass spectrometry (GDMS), and scanning electron microscopy (SEM). All of the XRD, XPS and GDMS analysis results indicate that carbon atoms effectively diffused into the titanium alloys and formed a uniform acicular TiC coating with micro-porous structure.

Luo, Yong; Ge, Shirong; Jin, Zhongmin; Fisher, John



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



Membrane bioreactor for waste gas treatment  

Microsoft Academic Search

SummaryThis thesis describes the design and testing of a membrane bioreactor (MBR) for removal of organic pollutants from air. In such a bioreactor for biological gas treatment pollutants are degraded by micro-organisms. The membrane bioreactor is an alternative to other types of bioreactors for waste gas treatment, such as compost biofilters and bioscrubbers. Propene was used as a model pollutant

M. W. Reij



Methods and systems for positioning micro elements  


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)



Tribological behavior of micro structured surfaces for micro forming tools  

Microsoft Academic Search

Mechanical micro machining processes, like milling and grinding are appropriate technologies for the flexible production of precise molds with complex shapes for metal forming processes. In most cases machining strategies are orientated towards form accuracy of the desired forming tool only. Thus, the generation of tribologically advantageous surfaces is often carried out in subsequent machining steps like honing. In micro

E. Brinksmeier; O. Riemer; S. Twardy



Micro rotary machine and methods for using same  

SciTech Connect

A micro rotary machine may include a micro actuator and a micro shaft coupled to the micro actuator. The micro shaft comprises a horizontal shaft and is operable to be rotated by the micro actuator. A micro tool is coupled to the micro shaft and is operable to perform work in response to motion of the micro shaft.

Stalford, Harold L. (Norman, OK)




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



Infrared micro-optics technologies  

NASA Astrophysics Data System (ADS)

Bodenseewerk GmbH generally works on challenging projects comprising Microsystems, e.g. micro-optics (micro-lenses, micro-mirrors). We utilize state-of-the-art laboratory equipment and simulation software (e.g. optical design with ZEMAX, ASAP and GLAD). Our recent activities on the development of several infrared micro-optical devices focus on high speed imaging of scenes with high angular resolution including the analysis of physical properties of the detected light (e.g. spectral content, polarization) utilizing staring IR sensors with focal-plane-arrays operating in a snap shot mode at high frame rates. We report about the development of so called micro-optical multiplexers which: (a) comprise micro-optical arrays and electro-mechanical micro-actuators, (b) image several fields of view with high resolution onto a single focal-plane-array, (c) image several fields of view with enhanced spatial resolution [by the factor of four compared to (b)] in a modified realization onto one focal-plane-array and (d) analyze the spectral content of an image using a single-band photon detector-array and multi-frame processing. The micro-opto-electro-mechanical multiplexer (MOEM) systems all consist of a primary objective, a MOEM image-steering respectively image coding device and a secondary objective. The primary objective images one or more suitable formed individual fields of view onto a common intermediate image plane. The MOEM devices comprise combinations of focusing and defocusing micro-lens-arrays, micro-shutter-arrays and micro-filter-arrays which are mounted parallel to each other near the intermediate image plane. The MOEM devices exhibit their above mentioned function modes by laterally displacing the micro-arrays with the help of modern micro-actuators. The secondary objective is utilized as relay optical stage. A modern common focal-plane-array is used as detector device. The micro-actuators responsible for the relative displacement of the micro-arrays are highly miniaturized while maintaining large displacement ranges and high linearity, reproducable positioning and reliability. This paper outlines the general sensor concept, explains the underlying principles and delineates the optical systems layout. Recent hardware realizations useful in military applications concerning image and laser beam steering are presented.

Krogmann, Dirk; Tholl, Hans D.



Thermal Characterization of the Micro Bonding Process Using a Hot Air Stream  

Microsoft Academic Search

The possible solution for bonding two different materials with intermediate layer of adhesive at relatively low temperatures in the micro domain is proposed in this paper. A stream of hot gas has been used for melting and softening different kinds of adhesives. After cooling down at room temperature, adhesives harden forming a stable and strong bond. The gas is heated

D. Andrijasevic; I. Giouroudi; W. Smetana; W. Brenner; D. Esinenco



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;)



Benefits of coextruded micro tubing.  


Coextruded tubing products offer additional functions through multiple material combinations and facilitate secondary assembly processes. This article presents four applications in which coextruded micro tubings have solved problems and reaped significant advantages: infusion therapy, regional anaesthesia, micro dialysis and parenteral feeding. PMID:19626950

Ziembinski, R



Calorimetric gas sensor  


A combustible gas sensor is described that uses a resistively heated, noble metal-coated, micromachined polycrystalline Si filament to calorimetrically detect the presence and concentration of combustible gases. The filaments tested to date are 2 {micro}m thick {times} 10{micro}m wide {times} 100, 250, 500, or 1000 {micro}m-long polycrystalline Si; some are overcoated with a 0.25 {micro}m-thick protective CVD Si{sub 3}N{sub 4} layer. A thin catalytic Pt film was deposited by CVD from the precursor Pt(acac){sub 2} onto microfilaments resistively heated to approximately 500 C; Pt deposits only on the hot filament. Using a constant-resistance-mode feedback circuit, Pt-coated filaments operating at ca. 300 C (35 mW input power) respond linearly, in terms of the change in supply current required to maintain constant resistance (temperature), to H{sub 2} concentrations between 100 ppm and 1% in an 80/20 N{sub 2}/O{sub 2} mixture. Other catalytic materials can also be used. 11 figs.

Ricco, A.J.; Hughes, R.C.; Smith, J.H.; Moreno, D.J.; Manginell, R.P.; Senturia, S.D.; Huber, R.J.



Industrial applications for LIGA-fabricated micro heat exchangers  

NASA Astrophysics Data System (ADS)

One of the well-known benefits of micro scale is enhanced heat transfer. This fact provides the motivation for fabricating a variety of micro heat exchangers using derivatives of the LIGA micromachining process. These heat exchangers can be made of polymers, nickel (electroplated or electroless), or ceramics (Si3N4 and alumina are presently being investigated). These heat exchangers are envisioned for applications such as gas turbine blades, mechanical seals and/or bearings, boilers, condensers, radiators, evaporators, electronic component cooling, and catalytic converters. In this paper, methods to fabricate an array of heat exchangers for different applications are described. In addition, simple analytic models that illustrate the motivation for fabricating micro cross flow heat exchanges are shown to compare favorably with experimental heat transfer results.

Kelly, Kevin W.; Harris, Chad; Stephens, Lyndon S.; Marques, Christophe; Foley, Dan



Micro thrust and heat generator  

SciTech Connect

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)



Micro thrust and heat generator  


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.



Micro Environmental Concrete  

NASA Astrophysics Data System (ADS)

Reactive powder concretes (RPC) are characterized by a particle diameter not exceeding 600 ?m and having very high compressive and tensile strengths. This paper describes a new generation of micro concrete, which has an initial as well as a final high physicomechanical performance. To achieve this, 15% by weight of the Portland cement have been substituted by materials rich in Silica (Slag and Dune Sand). The results obtained from the tests carried out on the RPC show that compressive and tensile strengths increase when incorporating the addition, thus improving the compactness of mixtures through filler and pozzolanic effects. With a reduction in the aggregate phase in the RPC and the abundance of the dune sand (southern of Algeria) and slag (industrial by-product of the blast furnace), the use of the RPC will allow Algeria to fulfil economical as well as ecological requirements.

Lanez, M.; Oudjit, M. N.; Zenati, A.; Arroudj, K.; Bali, A.


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



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.



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.



Gas Behavior in Galaxy Formation  

NASA Astrophysics Data System (ADS)

This dissertation focuses on the topic of gas in galaxy formation from three different perspectives: spherical collapse, external radiative heating, and 3D collapse. The physics of galaxy formation is explored via a combination of 1D and 3D calculations. The 1D calculations, have been used to explore both simple analytic models as well as a large number of micro-physical processes (e.g., multi-species chemistry, full multi-spectrum radiative transfer, and the subsequent heating and cooling). The 3D calculations have looked at the effects of external torques and of a hierarchical gas structure, but in an environment with less micro-physics. Through this approach a variety of conclusions have drawn about the formation of bulges and disks; the absorption line signatures of mini-halos and multi-phase gas; and the role of hydrodynamics in simulating galaxy formation.

Kepner, Jeremy Victor


Micro Eddy Current Testing by micro magnetic sensor array  

SciTech Connect

A micro Eddy Current Testing (ECT) system for planar thin specimens made of INCONEL 600 with flaws was proposed and developed. A micro ECT probe used here consists of a conventional pancake-type coil as an exciting coil and a micro magnetic sensor array as a set of pickup coils. Magnetic field perturbation due to a flaw was measured with high spatial resolution and signal-to-noise (S/N) ratio. The measured signals from the array were compared with numerical results obtained by a three-dimensional A-[phi] code. It was confirmed that the Micro ECT system has the potential to evaluate the length and depth of a flaw with better accuracy than that of a conventional pancake-type ECT in the stream generator tubings in a pressurized water nuclear reactor.

Uesaka, Mitsuru; Nakanishi, Takahiro; Miya, Kenzo (Univ. of Tokyo, Ibaraki (Japan). Nuclear Engineering Research Lab.); Komatsu, Hidenobu; Aoki, Kazuhiko (Nuclear Fuel Industries, Ltd., Osaka (Japan)); Kasai, Kazuo (Sumitomo Precision Co. Ltd., Hyogo (Japan))



A very large area Micro Pixel Chamber  

NASA Astrophysics Data System (ADS)

A Micro Pixel Chamber, called " ?-PIC", is a gaseous 2D imaging detector with a fine pixel electrode based on the Printed Circuit Board technology, and we developed it for the X/gamma-ray imaging and the tracking of the charged particles [A. Ochi, et al., Nucl. Instr. and Meth. A 478 (2002) 196; T. Nagayoshi, et al., Nucl. Instr. and Meth. A 525 (2004) 20.]. The previous ?-PIC has a fine position resolution, a high gas gain, a good gas gain uniformity and the stable operation. Although the detection area of the previous ?-PIC (˜10×10 cm2) is not large enough for a variety of the application, for example an MeV gamma-ray Compton camera [T. Tanimori, et al., New Astron. Rev. 48 (2004) 263.] and dark matter search [T. Tanimori, et al., Phys. Lett. B 578 (2004) 241.]. Therefore, we developed a new ?-PIC having a ˜30×30 cm2 detection area. The structure and the pitch of the electrode are same as those of the previous ?-PIC. There are 768×768 pixels in the whole area. This ?-PIC (TOSHIBA SN041129-1) is operated with a stable gas gain of ˜3500 and a maximum gain of ˜7000 at the center region, and the variety of the gain was 16.7% RMS. An X-ray image of the whole area was also taken by the irradiation of the X-rays from 109Cd (22 keV) to the whole detection area.

Takada, A.; Hattori, K.; Kabuki, S.; Kubo, H.; Miuchi, K.; Nagayoshi, T.; Nishimura, H.; Okada, Y.; Orito, R.; Sekiya, H.; Takeda, A.; Tanimori, T.; Ueno, K.



Aerothermal Optimization of Micro-gasturbine Compressor Including Heat Transfer  

Microsoft Academic Search

The aerodynamic design and performance prediction of a two-dimensional compressor for a micro-gas-turbine application is described. Because of the uncommon geometry (2D with large relative clearance) and particular operating conditions (low Reynolds number with large heat transfer) one has first evaluated and calibrated the one-dimensional design and off-design performance prediction method by comparing predictions with those obtained from a three-dimensional

R. A. Van den Braembussche; A. A. I?lek; Z. Alsalihi



Macro-micro Interlocked Simulation for Multiscale Phenomena  

Microsoft Academic Search

A new methodology for the simulation of multiscale pro-cesses, called Macro-Micro Interlocked (MMI) Simulation, is introduced.\\u000a The MMI simulation is carried out by the two-way connection of different numerical models, which may handle macroscopic and\\u000a microscopic dynamics, respectively. The MMI simulation are applied to several multiscale phenomena, for instance, cloud formation,\\u000a gas detonation, and plasma dynamics. The results indicate that

Kanya Kusano; Shigenobu Hirose; Toru Sugiyama; Shinichiro Shima; Akio Kawano; Hiroki Hasegawa



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

NASA Astrophysics Data System (ADS)

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 (ION/IOFF = 105) 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.; Midya, K.; Duttagupta, S. P.; Ramakrishnan, D.



Multiplexed specific label-free detection of NCI-H358 lung cancer cell line lysates with silicon based photonic crystal microcavity biosensors.  


We experimentally demonstrate label-free photonic crystal (PC) microcavity biosensors in silicon-on-insulator (SOI) to detect the epithelial-mesenchymal transition (EMT) transcription factor, ZEB1, in minute volumes of sample. Multiplexed specific detection of ZEB1 in lysates from NCI-H358 lung cancer cells down to an estimated concentration of 2 cells per micro-liter is demonstrated. L13 photonic crystal microcavities, coupled to W1 photonic crystal waveguides, are employed in which resonances show high Q in the bio-ambient phosphate buffered saline (PBS). When the sensor surface is derivatized with a specific antibody, the binding of the corresponding antigen from a complex whole-cell lysate generates a change in refractive index in the vicinity of the photonic crystal microcavity, leading to a change in the resonance wavelength of the resonance modes of the photonic crystal microcavity. The shift in the resonance wavelength reveals the presence of the antigen. The sensor cavity has a surface area of ?11?m(2). Multiplexed sensors permit simultaneous detection of many binding interactions with specific immobilized antibodies from the same bio-sample at the same instant of time. Specificity was demonstrated using a sandwich assay which further amplifies the detection sensitivity at low concentrations. The device represents a proof-of-concept demonstration of label-free, high throughput, multiplexed detection of cancer cells with specificity and sensitivity on a silicon chip platform. PMID:23274197

Chakravarty, Swapnajit; Lai, Wei-Cheng; Zou, Yi; Drabkin, Harry A; Gemmill, Robert M; Simon, George R; Chin, Steve H; Chen, Ray T



Micro-sensors for space applications  

SciTech Connect

Important factors in the application of sensing technology to space applications are low mass, small size, and low power. All of these attributes are enabled by the application of MEMS and micro-fabrication technology to microsensors. Two types of sensors are utilized in space applications: remotes sensing from orbit around the earth or another planetary body, and point sensing in the spacecraft or external to it. Several Sandia projects that apply microfabrication technologies to the development of new sensing capabilities having the potential for space applications will be briefly described. The Micro-Navigator is a project to develop a MEMS-based device to measure acceleration and rotation in all three axes for local area navigation. The Polychromator project is a joint project with Honeywell and MIT to develop an electrically programmable diffraction grating that can be programmed to synthesize the spectra of molecules. This grating will be used as the reference cell in a gas correlation radiometer to enable remote chemical detection of most chemical species. Another area of research where microfabrication is having a large impact is the development of a lab on a chip. Sandia's efforts to develop the {mu}ChemLab{trademark} will be described including the development of microfabricated pre-concentrators, chromatographic columns, and detectors. Smart sensors that allow the spacecraft independent decision making capabilities depend on pattern recognition. Sandia's development of a new pattern recognition methodology that can be used to interpret sensor response as well as for target recognition applications will be described.

Butler, M.A.; Frye-Mason, G.C.; Osbourn, G.C.



Prototyping of ultra micro centrifugal compressor-influence of meridional configuration  

Microsoft Academic Search

In order to investigate the design method for a micro centrifugal compressor, which is the most important component of an\\u000a ultra micro gas turbine, two types of centrifugal impeller with 2-dimensional blade were designed, manufactured and tested.\\u000a These impellers have different shapes of hub on the meridional plane with each other. Moreover, these types of impeller were\\u000a made for the

Toshiyuki Hirano; Tadataka Muto; Hoshio Tsujita



Machining of micro-systems  

Microsoft Academic Search

An increasing trend towards miniaturization of mechanical components necessitates the further development of micro-machining\\u000a techniques in order to produce components within given tolerances. For the dressing of multilayered, metallically bonded,\\u000a fine-grained grinding wheels that are used for micro-grinding the technique of electro contact discharge dressing was developed.\\u000a In the following, the determined interrelations between the variables dressing voltage, limitation of

Berend Denkena; Hans-Werner Hoffmeister; Dennis Hahmann; Marcus Hlavac



Dual liquid and gas chromatograph system  


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)



Development of Micromachine Gas Turbine for Portable Power Generation  

Microsoft Academic Search

Micromachine gas turbine with centrifugal impellers of 10mm diameter fabricated by 5-axis micro-milling is under development at Tohoku University, in conjunction with Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI), Tohoku-Gakuin University, and Sankyo Seiki Mfg. Co., Ltd. The development is currently at the stage of proving the feasibility of the gas turbine cycle by component tests. Micro-combustors have been developed for

Kousuke Isomura; Shuji Tanaka; Shinichi Togo; Hideki Kanebako; Motohide Murayama; Nobuyoshi Saji; Fumihiro Sato; Masayoshi Esashi



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.



Perfectly monodisperse micro-bubble production by novel mechanical means. Scaling laws.  

NASA Astrophysics Data System (ADS)

A continuous stream of controllable, perfectly homogeneous size micro-bubbles (of the order of some microns and larger) can be produced by a novel, extremely simple mechanical means that we call "Flow Focusing" (e.g. see Ganan-Calvo 1998, Phys. Rev. Lett. vol. 80, 285). Using this technique, a capillary gas micro-jet is formed ("focused") by a co-flowing stream of liquid forced through a sub-millimetric orifice. This gas micro-jet undergoes a rapid capillary breakup (e.g. Chandrasekhar 1961 "Hydrodynamic and Hydromagnetic Stability", p. 541) with a strong frequency "self-locking" effect. In this work we present a theoretical model which predicts the micro-bubble size as a function of the physical and geometrical parameters of the system. A complete experimental study is also provided, and the raw data are collapsed into a universal scaling law given by our theoretical model. This novel micro-fluidics phenomenon may have a wide variety of applications ranging from bio-medicine, pharmaceutical specialities, food industry, and even for the mesoscale micro-templating of micro-engineered materials (i.e. photonic crystals, smart materials, etc.).

Ganan-Calvo, Alfonso M.; Gordillo, Jose M.; Ouarti, Nawel; Prevost, Thomas; Sampedro, Jose L.



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.


Recombination rates of human microRNA  

Microsoft Academic Search

The fact that microRNAs play a role in almost all biological processes is well established, as is the importance of recombination in generating genome variability. However, the association between microRNAs and recombination remains largely unknown. In order to investigate the recombination patterns of microRNAs, we performed a comprehensive analysis of the recombination rate of human microRNAs. We observed that microRNAs

Huizhi Zhao; Dong Wang; Bing Liu; Xingpeng Jiang; Jing Zhang; Ming Fan; Zhengjie Fan; Ying Chen; Sonya Wei Song; Wei Gao; Tianzi Jiang; Qinghua Cui



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



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



A robust numerical method for the R13 equations of rarefied gas dynamics: Application to lid driven cavity  

E-print Network

, inkjet printheads, micro heat-exchangers, micro pumps and turbines involve the flow of gas through microchannels as well as heat exchange and chemical reactions. Processes in such micro-systems are characterized describe other rarefaction effects. Microflows are characterized by small length scales or low pressures

Struchtrup, Henning


Micro-Resistojet for Small Satellites  

NASA Technical Reports Server (NTRS)

An efficient micro-resistojet has been developed with thrust in the millinewton level, with a specific impulse of approximately 250 seconds and power input of 20 watts or less that is useful for applications of up to 1,000 hours of operation or more. The essential feature of this invention is a gas-carrying tube surrounding a central heating element. The propellant is flashed into vapor and then passes through a narrow annulus between the tube and the heater where it is cracked (in the case of methanol, into CO and H2) before being discharged through a de Laval nozzle to produce thrust. A multi-layer radiation shield around the gas tube minimizes heat loss. Also, if methanol is used as the propellant, the simultaneous heating and cracking does not need an additional device. This unit would be especially useful for small satellites, with mass up to 100 kg, and for delta v up to 500 m/sec, and is suited for use with green methanol as the propellant where a specific impulse of 220 seconds is expected. Noble metal alloys are the optimal materials of construction. While the microresistojet is especially suited to methanol, many other propellants may be used such as water or, in the case of de-orbiting, many other residual liquids onboard the vehicle.

Brogan, Thomas; Robin, Mike; Delichatsios, Mary; Duggan, John; Hohman, Kurt; Hruby,Vlad



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



Micro-agglomerate flotation for deep cleaning of coal  

SciTech Connect

We are investigating the use of a hybrid process - Micro-agglomerate flotation - which is a combination of oil-agglomeration and froth flotation. The basic concept is to use small quantities of oil to promote the formation of dense micro-agglomerates with minimal entrapment of water and mineral particles, and to use froth flotation to extract these micro-agglomerates from the water/dispersed-mineral phase. Since the floating units are agglomerates (about 30--50 [mu]m in size) rather than individual coal particles (1--10 [mu]m) the problems of froth overload and water/mineral carryover should be significantly alleviated. Micro-agglomerate flotation has considerable potential for the practical deep cleaning of coal on a commercial scale. In principle, it should be possible to achieve both high selectivity and high yield at reasonable cost. The process requires only conventional, off-the-shelf equipment and reagent usage (oil, surfactants, etc.) should be small. There are, however, complications. The process involves at least five phases: two or more solids (coal and mineral), two liquids (oil and water) and one gas (air). It is necessary to maintain precise control over the chemistry of the liquid phases in order to promote the interfacial reactions and interactions between phases necessary to ensure selectivity. Kinetics as well as thermodynamic factors may be critical in determining overall system response.

Chander, S.; Hogg, R.



Surface form metrology of micro-optics  

NASA Astrophysics Data System (ADS)

This keynote starts from an overview of micro-optics from fundamental functions, fabrication methods and applications in precision engineering and nanotechnology. State-of-the-art measuring systems for surface form metrology of microoptics with micro-structured surfaces, including diffractive micro-optics such as diffraction gratings and refractive micro-optics such as micro lenses and micro-lens arrays, are then be presented. The measuring systems introduced in the presentation are classified into scanning probe microscope-based systems, mechanical stylus profiling systems and optical evaluation systems. Related research activities carried out in the authors' group are also highlighted.

Xu, Bin; Jia, Zhigang; Li, Xinghui; Chen, Yuan-Liu; Shimizu, Yuki; Ito, So; Gao, Wei




E-print Network


Liu, Paul


Micro flame-based detector suite for universal gas sensing.  

SciTech Connect

A microflame-based detector suit has been developed for sensing of a broad range of chemical analytes. This detector combines calorimetry, flame ionization detection (FID), nitrogen-phosphorous detection (NPD) and flame photometric detection (FPD) modes into one convenient platform based on a microcombustor. The microcombustor consists in a micromachined microhotplate with a catalyst or low-work function material added to its surface. For the NPD mode a low work function material selectively ionizes chemical analytes; for all other modes a supported catalyst such as platinum/alumina is used. The microcombustor design permits rapid, efficient heating of the deposited film at low power. To perform calorimetric detection of analytes, the change in power required to maintain the resistive microhotplate heater at a constant temperature is measured. For FID and NPD modes, electrodes are placed around the microcombustor flame zone and an electrometer circuit measures the production of ions. For FPD, the flame zone is optically interrogated to search for light emission indicative of deexcitation of flame-produced analyte compounds. The calorimetric and FID modes respond generally to all hydrocarbons, while sulfur compounds only alarm in the calorimetric mode, providing speciation. The NPD mode provides 10,000:1 selectivity of nitrogen and phosphorous compounds over hydrocarbons. The FPD can distinguish between sulfur and phosphorous compounds. Importantly all detection modes can be established on one convenient microcombustor platform, in fact the calorimetric, FID and FPD modes can be achieved simultaneously on only one microcombustor. Therefore, it is possible to make a very universal chemical detector array with as little as two microcombustor elements. A demonstration of the performance of the microcombustor in each of the detection modes is provided herein.

Hamilton, Thomas Warren; Washburn, Cody M.; Moorman, Matthew Wallace; Manley, Robert George; Lewis, Patrick Raymond; Miller, James Edward; Clem, Paul Gilbert; Shelmidine, Gregory J.; Manginell, Ronald Paul; Okandan, Murat



Micro-machined calorimetric biosensors  


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)



MicroRNA and implantation.  


We provide a review of microRNA (miRNA) related to human implantation which shows the potential diagnostic role of miRNAs in impaired endometrial receptivity, altered embryo development, implantation failure after assisted reproduction technology, and in ectopic pregnancy and pregnancies of unknown location. MicroRNAs may be emerging diagnostic markers and potential therapeutic tools for understanding implantation disorders. However, further research is needed before miRNAs can be used in clinical practice for identifying and treating implantation failure. PMID:24882617

Galliano, Daniela; Pellicer, Antonio



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.



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



Process Variability in Micro-Embossing  

E-print Network

A promising technique for the large-scale manufacture of micro-fluidic devices and photonic devices is hot embossing of polymers such as PMMA. Micro-embossing is a deformation process where the workpiece material is heated ...

Hardt, David E.


Numerical simulation of electrokinetically driven micro flows  

E-print Network

Spectral element based numerical solvers are developed to simulate electrokinetically driven flows for micro-fluidic applications. Based on these numerical solvers, basic phenomena and devices for electrokinetic applications in micro and nano flows...

Hahm, Jungyoon



Line trace micro-opto-electro-device  

NASA Astrophysics Data System (ADS)

Since micro robot has merits on small size and flexible movements, it could be used under many situations. A lot of novel designs of micro-robot have been developed recently. However, as miniaturizing the size of the micro-robot, the number of its sensor gets restricted. Then the information from the detectors becomes lack. This makes the micro robot difficult to acquire its status. A micro robot tracing a line has been designed in our lab. With the help of optoelectronic detection and logical algorithm, the micro robot could follow a black line printed on the white ground exactly. The micro robot's intelligence is realized through the program in its microprocessor. The technical details of the micro robot are as follows: dimensions: 30mm*25mm*35**; velocity: 60mm/s.

Yi, Deer; Lu, Si; Yan, Yingbai; Pang, Lin; Jin, Guofan



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



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


Polymer-embedded colloidal lead-sulfide nanocrystals integrated to vertically slotted silicon-based ring resonators for telecom applications  

NASA Astrophysics Data System (ADS)

The main drawback of the rapidly evolving field of silicon photonics lies in the absence of efficient monolithically integrated radiation sources as a consequence of the indirect bandgap of Si and Ge. Relevant alternatives based on the hybrid combination of Si with optically active materials have to be technologically simple, temporally stable, and provide efficient coupling to the Si waveguides. Lead-sulfide nanocrystals (NCs) were blended into a polymer resist suitable for deep-UV- and electron-beam lithography and integrated into Si-based vertically slotted waveguides and ring resonators. The polymer both stabilizes the NC's photoluminescence emission against degradation under ambient conditions and allows lithographic patterning of this compound material. After integration into the optoelectronic structures and upon optical pumping, intense photoluminescence emission from ring resonators was recorded at the output of bus-waveguides. The resonator quality factors were investigated for polymer-NC compounds with NC concentrations in the range between 0.1 and 8 vol%. The spontaneous emission rate enhancement for vertically slotted resonators was estimated to be a factor of two higher as compared to unslotted ones. The stable integration of colloidal NCs as well as the improved light coupling to silicon circuits is an important step in the development of silicon-based hybrid photonics.

Humer, Markus; Guider, Romain; Hackl, Florian; Fromherz, Thomas



Gas sensor with attenuated drift characteristic  

Microsoft Academic Search

A sensor with an attenuated drift characteristic, including a layer structure in which a sensing layer has a layer of diffusional barrier material on at least one of its faces. The sensor may for example be constituted as a hydrogen gas sensor including a palladium\\/yttrium layer structure formed on a micro-hotplate base, with a chromium barrier layer between the yttrium

Ing-Shin Chen; Dimeo Jr. Frank; Philip S. H. Chen; Jeffrey W. Neuner; James Welch; Bryan Hendrix



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

E-print Network

-factories where micro-products are too small to be handled manually by an operator. To improve micro mechanical studies. They have been built with microfabrication processes (DRIE1 ) in SOI 2 wafers in most micro-factories. Many tasks could include micro-objects handling like pick and place, assembly

Paris-Sud XI, Université de


A high-efficiency approach for fabricating mass micro holes by batch micro EDM  

Microsoft Academic Search

This work is a follow-up study based on previous research. The study presents a novel approach for effective production of mass micro holes. Initially, a set of micro w-EDM mechanisms is designed and mounted on the developed precise tabletop CNC machine tool to fabricate the micro electrode array. The tension of the micro wire is precisely controlled by a magnetic

Shun-Tong Chen



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


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.


Abrasive Flow Polishing of Micro Bores  

Microsoft Academic Search

Micro bore finishing for metal and ceramic materials has been a challenge in the manufacturing industry. Unfortunately, little is understood about how to polish a micro bore and how to assess its inner wall quality because it is difficult to access the micro bore for either polishing or measurement. This article reports on a feasibility study of the abrasive flow

Ling Yin; Kuppuswamy Ramesh; Stephen Wan; Xiang Dong Liu; Han Huang; Yu Chan Liu



Tilted Micro Air Jet for Flow Control  

Microsoft Academic Search

In this paper, we present an interesting method to microfabricate a tilted micro air jet generator. We used the well-know deep reactive ion etching (DRIE) technique in order to realize in a silicon substrate a double side etching. For aircraft and cars, micro air jets will take an important place for fluid control. Micro air jets are characterized by their

Julien Malapert; Réda Yahiaoui; Rabah Zeggari; Jean-François Manceau



Micro Channel/Multibus-II Interface Circuit  

NASA Technical Reports Server (NTRS)

Micro Channel/Multibus-II interface circuit provides electrical interconnections enabling communications between Micro Channels of IBM Personal System/2 computers and IEEE 1296 standard Multibus-II parallel system bus (iPSB). Made mostly of commercially available parts, interface enables independent Micro Channels to communicate over iPSB without modification.

D'Ambrose, John J.; Jaworski, Richard C.; Heise, Nyles N.; Thornton, David N.



Laboratory 3D Micro-XRF/Micro-CT Imaging System  

NASA Astrophysics Data System (ADS)

A prototype micro-XRF laboratory system based on pinhole imaging was developed to produce 3D elemental maps. The fluorescence x-rays are detected by a deep-depleted CCD camera operating in photon-counting mode. A charge-clustering algorithm, together with dynamically adjusted exposure times, ensures a correct energy measurement. The XRF component has a spatial resolution of 70 ?m and an energy resolution of 180 eV at 6.4 keV. The system is augmented by a micro-CT imaging modality. This is used for attenuation correction of the XRF images and to co-register features in the 3D XRF images with morphological structures visible in the volumetric CT images of the object.

Bruyndonckx, P.; Sasov, A.; Liu, X.



MicroRNAs — the micro steering wheel of tumour metastases  

Microsoft Academic Search

Recently, microRNAs (miRNAs) have been discovered to have a role in metastasis. Here we describe how miRNAs are involved in advanced stages of tumour progression, stressing their roles as metastasis activators or suppressors, and discuss their possible use in the clinic as predictive markers and as therapeutic strategies for patients with metastases. Furthermore, we develop the concept that the same

Milena S. Nicoloso; Riccardo Spizzo; Masayoshi Shimizu; Simona Rossi; George A. Calin



J. Electrochem. Soc., in press (1998) Micro-Macroscopic Coupled Modeling of Batteries and Fuel Cells  

E-print Network

1 J. Electrochem. Soc., in press (1998) Micro-Macroscopic Coupled Modeling of Batteries and Fuel taken into account. These gas reactions represent an important mechanism for battery overcharge to simulate batteries and fuel cells was described. The model is capable of incorporating interfacial non

Wang, Chao-Yang


J. Electrochem. Soc., in press (1998) MicroMacroscopic Coupled Modeling of Batteries and Fuel Cells  

E-print Network

1 J. Electrochem. Soc., in press (1998) Micro­Macroscopic Coupled Modeling of Batteries and Fuel taken into account. These gas reactions represent an important mechanism for battery overcharge to simulate batteries and fuel cells was described. The model is capable of incorporating interfacial non

Wang, Chao-Yang


ORIGINAL PAPER Determination of organic micro-pollutants such as personal  

E-print Network

ORIGINAL PAPER Determination of organic micro-pollutants such as personal care products by clean-up steps, i.e. solid phase extraction and size exclusion chromatography. The determination is performed by gas chromatography coupled to mass spec- trometry. Stable isotope-labelled compounds

Kolaei, Alireza Rezania


Surface tension effects on adiabatic gasliquid flow across micro pillars Santosh Krishnamurthy, Yoav Peles *  

E-print Network

(Christel et al., 1999), and mi- cro-heat exchangers (KosÃ?ar and Peles, 2006, 2007; Siu-Ho et al., 2007- phase flow characteristics in small length scales. Kawahara et al. (2005) in their study on gas the fundamental stand point, but also to improve the design of many micro systems. In conventional scale

Peles, Yoav


Vacuum 65 (2002) 415425 Plasma spraying of micro-composite thermal barrier coatings  

E-print Network

Vacuum 65 (2002) 415­425 Plasma spraying of micro-composite thermal barrier coatings S. Sharafata. Keywords: Plasma spraying; Gas tunnel-type; Thermal barrier-composite coatings; Aluminum oxide; Zirconium, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan Abstract The thermal barrier coatings

Ghoniem, Nasr M.


ASIAN SYMPOSIUM ON VISUALIZATION, 2003 Visualizing Heterogeneous Flows in Micro Fluidic Devices  

E-print Network

the topographical and chemical properties of the boundary to molecular scale. These properties affect the extent with interesting practical applications in enhanced oil recovery, heat pipes, and micro methanol fuel cells. Gas microchannels fabricated from a silicon wafer using deep reactive ion etching (DRIE) and sealed with Pyrex glass

Cubaud, Thomas


Micro-Tubular Fuel Cells  

NASA Technical Reports Server (NTRS)

Micro-tubular fuel cells that would operate at power levels on the order of hundreds of watts or less are under development as alternatives to batteries in numerous products - portable power tools, cellular telephones, laptop computers, portable television receivers, and small robotic vehicles, to name a few examples. Micro-tubular fuel cells exploit advances in the art of proton-exchange-membrane fuel cells. The main advantage of the micro-tubular fuel cells over the plate-and-frame fuel cells would be higher power densities: Whereas the mass and volume power densities of low-pressure hydrogen-and-oxygen-fuel plate-and-frame fuel cells designed to operate in the targeted power range are typically less than 0.1 W/g and 0.1 kW/L, micro-tubular fuel cells are expected to reach power densities much greater than 1 W/g and 1 kW/L. Because of their higher power densities, micro-tubular fuel cells would be better for powering portable equipment, and would be better suited to applications in which there are requirements for modularity to simplify maintenance or to facilitate scaling to higher power levels. The development of PEMFCs has conventionally focused on producing large stacks of cells that operate at typical power levels >5 kW. The usual approach taken to developing lower-power PEMFCs for applications like those listed above has been to simply shrink the basic plate-and-frame configuration to smaller dimensions. A conventional plate-and-frame fuel cell contains a membrane/electrode assembly in the form of a flat membrane with electrodes of the same active area bonded to both faces. In order to provide reactants to both electrodes, bipolar plates that contain flow passages are placed on both electrodes. The mass and volume overhead of the bipolar plates amounts to about 75 percent of the total mass and volume of a fuel-cell stack. Removing these bipolar plates in the micro-tubular fuel cell significantly increases the power density.

Kimble, Michael C.; Anderson, Everett B.; Jayne, Karen D.; Woodman, Alan S.



Tilted Micro Air Jet for Flow Control  

E-print Network

In this paper, we present an interesting method to microfabricate a tilted micro air jet generator. We used the well-know deep reactive ion etching (DRIE) technique in order to realize in a silicon substrate a double side etching. For aircraft and cars, micro air jets will take an important place for fluid control. Micro air jets are characterized by their speed, frequency and tilt. Usually, this micro air jets are produced by fluidic microsystems. We presented experimental results about micro tilted air jets. A comparison between finite element method simulation, theory and experimental results are performed to define the microsystem geometry leading a specific air jet angle.

Malapert, Julien; Zeggari, Rabah; Manceau, Jean-François



Gas separating  


Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

Gollan, Arye Z. [Newton, MA



Gas separating  


Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

Gollan, Arye (Newton, MA)



Micro-optofluidic Lenses: A review  

PubMed Central

This review presents a systematic perspective on the development of micro-optofluidic lenses. The progress on the development of micro-optofluidic lenses are illustrated by example from recent literature. The advantage of micro-optofluidic lenses over solid lens systems is their tunability without the use of large actuators such as servo motors. Depending on the relative orientation of light path and the substrate surface, micro-optofluidic lenses can be categorized as in-plane or out-of-plane lenses. However, this review will focus on the tunability of the lenses and categorizes them according to the concept of tunability. Micro-optofluidic lenses can be either tuned by the liquid in use or by the shape of the lens. Micro-optofluidic lenses with tunable shape are categorized according to the actuation schemes. Typical parameters of micro-optofluidic lenses reported recently are compared and discussed. Finally, perspectives are given for future works in this field. PMID:20714369

Nguyen, Nam-Trung



Revolution of Sensors in Micro-Electromechanical Systems  

NASA Astrophysics Data System (ADS)

Microsensors realized by micro-electromechanical systems (MEMS) technology play a key role as the input devices of systems. In this report, the following sensors are reviewed: piezoresistive and capacitive pressure sensors, surface acoustic wave (SAW) wireless pressure sensors, tactile sensor networks for robots, accelerometers, angular velocity sensors (gyroscopes), range image sensors using optical scanners, infrared imagers, chemical sensing systems as Fourier transform infrared (FTIR) spectroscopy and gas chromatography, flow sensors for fluids, and medical sensors such as ultrafine optical-fiber blood pressure sensors and implantable pressure sensors.

Esashi, Masayoshi



Micro-/nanostructured mechanical metamaterials.  


Mechanical properties of materials have long been one of the most fundamental and studied areas of materials science for a myriad of applications. Recently, mechanical metamaterials have been shown to possess extraordinary effective properties, such as negative dynamic modulus and/or density, phononic bandgaps, superior thermoelectric properties, and high specific energy absorption. To obtain such materials on appropriate length scales to enable novel mechanical devices, it is often necessary to effectively design and fabricate micro-/nano- structured materials. In this Review, various aspects of the micro-/nano-structured materials as mechanical metamaterials, potential tools for their multidimensional fabrication, and selected methods for their structural and performance characterization are described, as well as some prospects for the future developments in this exciting and emerging field. PMID:22899377

Lee, Jae-Hwang; Singer, Jonathan P; Thomas, Edwin L



Electrospinning of micro spiral fibers  

NASA Astrophysics Data System (ADS)

We describe an easy way to form micro spiral structures resulting from buckling instabilities of an electro jet of a nanoscale polymer fiber of polyvinglpyrrolidone-Cu(NO3)2 (PVP-Cu(NO3)2) sol) and discuss the formation process. We control the morphologies of the fibers into spiral fibers, and free-standing hollow cylinders by connecting an opposite high voltage supply (-5 to -10 kV) on the collector. The microstructured surfaces were observed by scanning electron microscope (SEM). SEM analysis revealed the presence of spirals with diameters of approximately 20 to 30 ?m. The structures formed by the nanofibers could be used in diverse fields of nanotechnology, such as micro planar inductor and nanochannels.

Chang, Guoqing; Zhu, Xuefeng; Warren, Roseanne; Wang, Xu; He, Tianzhen; Lin, Liwei; Shen, Jianyi



Performance of the micro-PIC gaseous area detector in small-angle X-ray scattering experiments.  


The application of a two-dimensional photon-counting detector based on a micro-pixel gas chamber (micro-PIC) to high-resolution small-angle X-ray scattering (SAXS), and its performance, are reported. The micro-PIC is a micro-pattern gaseous detector fabricated by printed circuit board technology. This article describes the performance of the micro-PIC in SAXS experiments at SPring-8. A dynamic range of >10(5) was obtained for X-ray scattering from a polystyrene sphere solution. A maximum counting rate of up to 5 MHz was observed with good linearity and without saturation. For a diffraction pattern of collagen, weak peaks were observed in the high-angle region in one accumulation of photons. PMID:19240335

Hattori, Kaori; Tsuchiya, Ken'ichi; Ito, Kazuki; Okada, Yoko; Fujii, Kotaro; Kubo, Hidetoshi; Miuchi, Kentaro; Takata, Masaki; Tanimori, Toru; Uekusa, Hidehiro



Insect powered micro air vehicles  

Microsoft Academic Search

In this paper we present successful navigation of a mechanically linked insect moth-pair, using light-weight and low-power actuators, demonstrating insect powered micro air vehicles (MAVs). These MAVs can fly for long periods of time, consuming only a small fraction(1%) of power compared to purely mechanical MAVs. We demonstrate strategies for harnessing the high energy-density biofuel and high efficiency muscle actuators

Siva Pulla; Amit Lal



Endoradiosonde needs micro machine technology  

Microsoft Academic Search

Endoradiosondes or radio pills are tiny transmitters which can be swallowed to monitor parameters such as pH in the stomach. These devices were developed in the 1950's. However, numbers of electronic circuits were limited at that time, because no IC and micro-sensors existed. The sondes are still useful to measure various parameters in the gastric tract in a noninvasive way.

Akihiko Uchiyama



The Micro and Macro Worlds  

NSDL National Science Digital Library

This lesson, presented by the National Nanotechnology Infrastructure Network, covers the general concepts of size and scale by discussing the micro and macro worlds. The activity focuses on using scale bars as this is "the most common feature when presenting nanoscale structures or naonoscale science." Students will also learn about different scales of measure which is fundamental to learning about nanotechnology. A Teacher Preparation Guide and PowerPoint slides are included.



Numerical analysis for effect of process parameters of low-current micro-PAW on constricted arc  

Microsoft Academic Search

A model was put forward to simulate the electromagnetic phenomena and fluid field in plasma arc occurring during the low-current\\u000a microplasma arc welding (low-current micro-PAW) process. The effects of the nozzle neck-in and welding current of micro-plasma\\u000a arc on the arc electromagnetic field distribution were discussed. Finally, under the condition of different welding current,\\u000a welding voltage, arc length, shield gas

Pei-quan Xu; Shun Yao; Jian-ping He; Chun-wei Ma; Jiang-wei Ren



Gas Laws  

NSDL National Science Digital Library

In this activity, students study gas laws at a molecular level. They vary the volume of a container at constant temperature to see how pressure changes (Boyle's Law), change the temperature of a container at constant pressure to see how the volume changes with temperature (Charlesâs Law), and experiment with heating a gas in a closed container to discover how pressure changes with temperature (Gay Lussac's Law). They also discover the relationship between the number of gas molecules and gas volume (Avogadro's Law). Finally, students use their knowledge of gas laws to model a heated soda can collapsing as it is plunged into ice water.

Consortium, The C.



Operation of microstrip gas counters with DME-based gas mixtures  

NASA Astrophysics Data System (ADS)

This paper reports on the operation of MicroStrip Gas Counters (MSGC) with several dimethylether (DME)-based gas mixtures. We present measurements of signal amplitude, detection efficiency and spatial resolution for minimum ionizing particles. We also show measurements of electron drift velocity and transverse diffusion coefficient in the counting gases considered. These results are discussed regarding the use of MSGC's for tracking at high-energy physics experiments that have to deal with high particle rates.

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


Human polarimetric micro-doppler  

NASA Astrophysics Data System (ADS)

Modern radars can pick up target motions other than just the principle target Doppler; they pick out the small micro-Doppler variations as well. These can be used to visually identify both the target type as well as the target activity. We model and measure some of the micro-Doppler motions that are amenable to polarimetric measurement. Understanding the capabilities and limitations of radar systems that utilize micro-Doppler to measure human characteristics is important for improving the effectiveness of these systems at securing areas. In security applications one would like to observe humans unobtrusively and without privacy issues, which make radar an effective approach. In this paper we focus on the characteristics of radar systems designed for the estimation of human motion for the determination of whether someone is loaded. Radar can be used to measure the direction, distance, and radial velocity of a walking person as a function of time. Detailed radar processing can reveal more characteristics of the walking human. The parts of the human body do not move with constant radial velocity; the small micro-Doppler signatures are timevarying and therefore analysis techniques can be used to obtain more characteristics. Looking for modulations of the radar return from arms, legs, and even body sway are being assessed by researchers. We analyze these techniques and focus on the improved performance that fully polarimetric radar techniques can add. We perform simulations and fully polarimetric measurements of the varying micro-Doppler signatures of humans as a function of elevation angle and azimuthal angle in order to try to optimize this type of system for the detection of arm motion, especially for the determination of whether someone is carrying something in their arms. The arm is often bent at the elbow, providing a surface similar to a dihedral. This is distinct from the more planar surfaces of the body and allows us to separate the signals from the arm (and knee) motion from the rest of the body. The double-bounce can be measured in polarimetric radar data by measuring the phase difference between HH and VV. Additionally, the cross-pol and co-pol Doppler signatures are analyzed, showing that the HH polarization may perform better on dismounts in open grass.

Tahmoush, David; Silvious, Jerry



Absorption of SO 2 from flue gas using PVDF hollow fiber membranes in a gas–liquid contactor  

Microsoft Academic Search

The micro-porous hydrophobic PVDF hollow fiber membranes were prepared from polyvinylidenefluoride and N-methyl-2-pyrrolidone by the dry-jet wet phase inversion process. The mean pore radius and the effective surface porosity were evaluated by the gas permeation method. The membrane coefficient was evaluated independently from the gas permeation data, gas absorption data, and by using a mathematical model. The membrane morphology was

Hyun Hee Park; Bal Raj Deshwal; In Won Kim; Hyung Keun Lee



Sonoluminescence, shock waves, and micro-thermonuclear fusion  

SciTech Connect

We have performed numerical hydrodynamic simulations of the growth and collapse of a sonoluminescing bubble in a liquid. Our calculations show that spherically converging shock waves are generated during the collapse of the bubble. The combination of the shock waves and a realistic equation of state for the gas in the bubble provides an explanation for the measured picosecond optical pulse widths and indicates that the temperatures near the center of the bubble may exceed 3O eV. This leads naturally to speculation about obtaining micro-thermonuclear fusion in a bubble filled with deuterium (D{sub 2}) gas. Consequently, we performed numerical simulations of the collapse of a D{sub 2} bubble in D{sub 2}0. A pressure spike added to the periodic driving amplitude creates temperatures that may be sufficient to generate a very small, but measurable number of thermonuclear D-D fusion reactions in the bubble.

Moss, W.C.; Clarke, D.B.; White, J.W.; Young, D.A.



Micro-Electronic Nose System  

NASA Astrophysics Data System (ADS)

The ability to "smell" various gas vapors and complex odors is important for many applications such as environmental monitoring for detecting toxic gases as well as quality control in the processing of food, cosmetics, and other chemical products for commercial industries. Mimicking the architecture of the biological nose, a miniature electronic nose system was designed and developed consisting of an array of sensor devices, signal-processing circuits, and software pattern-recognition algorithms. The array of sensors used polymer/carbon-black composite thin-films, which would swell or expand reversibly and reproducibly and cause a resistance change upon exposure to a wide variety of gases. Two types of sensor devices were fabricated using silicon micromachining techniques to form "wells" that confined the polymer/carbon-black to a small and specific area. The first type of sensor device formed the "well" by etching into the silicon substrate using bulk micromachining. The second type built a high-aspect-ratio "well" on the surface of a silicon wafer using SU-8 photoresist. Two sizes of "wells" were fabricated: 500 x 600 mum² and 250 x 250 mum². Custom signal-processing circuits were implemented on a printed circuit board and as an application-specific integrated-circuit (ASIC) chip. The circuits were not only able to measure and amplify the small resistance changes, which corresponded to small ppm (parts-per-million) changes in gas concentrations, but were also adaptable to accommodate the various characteristics of the different thin-films. Since the thin-films were not specific to any one particular gas vapor, an array of sensors each containing a different thin-film was used to produce a distributed response pattern when exposed to a gas vapor. Pattern recognition, including a clustering algorithm and two artificial neural network algorithms, was used to classify the response pattern and identify the gas vapor or odor. Two gas experiments were performed, one at low gas concentrations between 100 and 600 ppm for two gas vapors and the other at high gas concentrations between 2000 ppm and the saturated vapor pressure of three gas vapors. The array of sensors and circuits were able to uniquely detect and measure these gas vapors and showed a linear response to their concentration levels for both experiments. The results also demonstrated that a reduction in the sensor area by two orders of magnitude (from 4.32 mm² to 0.0625 mm²) did not affect the sensor response. By applying pattern-recognition algorithms, the electronic nose system was able to correctly identify the different gas vapors from the pattern responses of the sensor array.

Zee, Frank C.


Improvement of the gas sensor response via silicon ?-preconcentrator  

Microsoft Academic Search

Gas preconcentration is essential for the success of many micro-analytical detector systems and allows the monitoring of the noxious air pollutants in the ppb range. In this paper we use a ?-preconcentrator unit fabricated with silicon technology. The unit consists of a 3D-micro-heater that composed by a grid of suspended silicon bars underneath a polysilicon resistor. The structure allows holding

Peter Ivanov; Fernando Blanco; Isabel Gràcia; N. Sabaté; A. Ruiz; Xavier Vilanova; Xavier Correig; Luis Fonseca; E. Figueras; J. Santander; Carles Cané



Silicon-based products and solutions  

NASA Astrophysics Data System (ADS)

TeraXion started silicon photonics activities aiming at developing building blocks for new products and customized solutions. Passive and active devices have been developed including MMI couplers, power splitters, Bragg grating filters, high responsivity photodetectors, high speed modulators and variable optical attenuators. Packaging solutions including fiber attachment and hybrid integration using flip-chip were also developed. More specifically, a compact packaged integrated coherent receiver has been realized. Good performances were obtained as demonstrated by our system tests results showing transmission up to 4800 km with BER below hard FEC threshold. The package size is small but still limited by the electrical interface. Migrating to more compact RF interface would allow realizing the full benefit of this technology.

Painchaud, Y.; Poulin, M.; Pelletier, F.; Latrasse, C.; Gagné, J.-F.; Savard, S.; Robidoux, G.; Picard, M.-.; Paquet, S.; Davidson, C.-.; Pelletier, M.; Cyr, M.; Paquet, C.; Guy, M.; Morsy-Osman, M.; Chagnon, M.; Plant, D. V.



Electrochemical behaviors of silicon based anode material  

NASA Astrophysics Data System (ADS)

Mixed silicon/graphite anode materials have been prepared by means of simple mechanical milling process. Research reveals that the microstructural changes, accompanying the electrochemical alloying/de-alloying operations lead to a macrostructural deformations of the anodes. The key step for improving of such composites, therefore, could be sought in alternative electrode configurations or textures, preserving the electrodes from the detrimental effect of silicon hosts volume variations.

Yoshio, Masaki; Tsumura, Takaaki; Dimov, Nikolay


Electrochemical behaviors of silicon based anode material  

NASA Astrophysics Data System (ADS)

Mixed silicon-graphite anode materials have been prepared by means of simple mechanical milling process. Research reveals that the microstructural changes, accompanying the electrochemical alloying/de-alloying operations, lead to a macrostructural deformation of the anodes. The key step for improving of such composites therefore could be sought in alternative electrode configurations or textures, preserving the electrodes from the detrimental effect of silicon hosts volume variations.

Yoshio, Masaki; Kugino, Satoshi; Dimov, Nikolay


Amorphous silicon-based microchannel plates  

NASA Astrophysics Data System (ADS)

Microchannel plates (MCP) based on hydrogenated amorphous silicon (a-Si:H) were recently introduced to overcome some of the limitations of crystalline silicon and glass MCP. The typical thickness of a-Si:H based MCPs (AMCP) ranges between 80 and 100 ?m and the micromachining of the channels is realized by deep reactive ion etching (DRIE). Advantages and issues regarding the fabrication process are presented and discussed. Electron amplification is demonstrated and analyzed using Electron Beam Induced Current (EBIC) technique. The gain increases as a function of the bias voltage, limited to -340 V on account of high leakage currents across the structure. EBIC maps on 10° tilted samples confirm that the device active area extend to the entire channel opening. AMCP characterization with the electron beam shows gain saturation and signal quenching which depends on the effectiveness of the charge replenishment in the channel walls.

Franco, Andrea; Riesen, Yannick; Wyrsch, Nicolas; Dunand, Sylvain; Powolny, François; Jarron, Pierre; Ballif, Christophe



Nonconventional (Non-Silicon-Based) Photovoltaic Materials  

NASA Astrophysics Data System (ADS)

Although photovoltaic devices and modules made from crystalline silicon currently dominate the market, many efforts in developing photovoltaics involve the use of alternative materials. Binary and multinary materials with direct band gaps and therefore high absorption coefficients allow for the fabrication of thin-film photovoltaic modules with minimized material use and the possibility for depositing on large areas and alternative substrates such as glass, stainless steel, or polyimide foils. With the great diversity of optoelectronic properties of binary and multinary materials, highly efficient photovoltaic devices fabricated at very low cost are in principle possible. Requirements for efficient photovoltaic devices using nonconventional materials are discussed, and results obtained for photovoltaic devices based on selected binary and multinary materials obtained during the past few decades are summarized.

Unold, T.; Schock, H. W.



Intraspinal gas.  


Intraspinal gas can be observed in a number of pathological settings including degenerative disc disease, infection, tumor or trauma, and in patients who have undergone therapeutic and diagnostic procedures. The air can be epidural, intradural or intradiscal. Intraspinal gas is usually asymptomatic. We report intraspinal gas in three patients, one with cervical, one with thoracic, and one with lumber disc disease and spondylolisthesis. The investigations were all completed at the the same medical center and CT and MRI were done in each case. The gas was in the epidural space in all three patients. These cases provide further evidence that intraspinal gas may persist without causing symptoms, and that resultant symptoms can disappear spontaneously. MRI is not reliable for diagnosing intraspinal gas; CT is recommended. PMID:17430780

Konya, Deniz; Ozgen, Serdar; Sun, Ibrahim H; Pamir, Necmettin M



Micro guidance and control technology overview  

NASA Technical Reports Server (NTRS)

This paper gives an overview of micro-guidance and control technologies and in the process previews of the technology/user and systems issues presented in the guidance and control session at the workshop. We first present a discussion of the advantages of using micro-guidance and control components and then detail six micro-guidance and control thrusts that could have a revolutionary impact on space missions and systems. Specific technologies emerging in the micro-guidance and control field will be examined. These technologies fall into two broad categories: micro-attitude determination (inertial and celestial) and micro-actuation, control and sensing. Finally, the scope of the workshop's guidance and control panel are presented.

Kissel, Glen J.; Hadaegh, Fred Y.



Micro-agglomerate flotation for deep cleaning of coal. Final report  

SciTech Connect

The development of practical technologies for the deep cleaning of coal has been seriously hampered by the problems of carrying out efficient coal/mineral separations at the very fine sizes (often finer than 10 {micro}m) needed to achieve adequate liberation of the mineral matter from the coal matrix. In this investigation a hybrid process--Micro-agglomerate flotation--which is a combination of oil-agglomeration and froth flotation was studied. The basic concept is to use small quantities of oil to promote the formation of dense micro-agglomerates with minimal entrapment of water and mineral particles and to use froth flotation to separate these micro-agglomerates from the water/dispersed-mineral phase. Since the floating units will be relatively large agglomerates (30--50 {micro}m in size) rather than fine coal particles (1--10 {micro}m) the problems of froth overload and water/mineral carryover should be significantly alleviated. There are, however, complications. The process involves at least five phases: two or more solids (coal and mineral), two liquids (oil and water) and one gas (air). It is demonstrated in this study that the process is very sensitive to fluctuations in operating parameters. It is necessary to maintain precise control over the chemistry of the liquid phases as well as the agitation conditions in order to promote selectivity. Both kinetics as well as thermodynamic factors play a critical role in determining overall system response.

Chander, S.; Hogg, R.



A new design of the gaseous imaging detector: Micro Pixel Chamber  

NASA Astrophysics Data System (ADS)

The novel gaseous detector "Micro Pixel Chamber (Micro PIC)" has been developed for X-ray, gamma-ray and charged particle imaging. This detector consists of double sided printing circuit board (PCB). The stable operation of Micro PIC is realized by thick substrate and wide anode strips. One of the most outstanding feature is the process of production and the cost. The base technology of producing Micro PIC is same as producing PCB, then detector with large detection area (more than 10 cm×10 cm) can be made by present technology. Our first tests were performed using a 3 cm×3 cm detection area with a readout of 0.4 mm pitch. The gas gain and stability were measured in these tests. The gas gain of 10 4 was obtained using argon ethane (8:2) gas mixture. Also, there was no discharge between anodes and cathodes in the gain of 10 3 during two days of continuous operation. Although some discharges occurred in the higher gain (approximately 10 4), no critical damage on the detector was found.

Ochi, Atsuhiko; Nagayoshi, Tsutomu; Koishi, Satoshi; Tanimori, Toru; Nagae, Tomofumi; Nakamura, Mirei



Micro-unmanned aerodynamic vehicle  


A MEMS-based micro-unmanned vehicle includes at least a pair of wings having leading wing beams and trailing wing beams, at least two actuators, a leading actuator beam coupled to the leading wing beams, a trailing actuator beam coupled to the trailing wing beams, a vehicle body having a plurality of fulcrums pivotally securing the leading wing beams, the trailing wing beams, the leading actuator beam and the trailing actuator beam and having at least one anisotropically etched recess to accommodate a lever-fulcrum motion of the coupled beams, and a power source.

Reuel, Nigel (Rio Rancho, NM); Lionberger, Troy A. (Ann Arbor, MI); Galambos, Paul C. (Albuquerque, NM); Okandan, Murat (Albuquerque, NM); Baker, Michael S. (Albuquerque, NM)



MicroRNAs in the immune response  

Microsoft Academic Search

MicroRNAs (miRs) were only discovered little more than a decade ago, yet it has become rapidly clear that they are crucial posttranscriptional regulators of gene expression by decreasing the abundance or translational efficiency of mRNAs [Maroney PA, Yu Y, Nilsen TW. MicroRNAs, mRNAs, and translation. Cold Spring Harb Symp Quant Biol 2006;71: 531–5; Nilsen TW. Mechanisms of microRNA-mediated gene regulation

Irene Pedersen; Michael David



Micro windmills to recharge your mobile phone  

E-print Network

0Tweet 0 Micro windmills to recharge your mobile phone Discussion in 'Other Engineering Trades be hosted on your mobile phone and used to charge your mobile phone on the go. Rao's work has seen a greatMicro windmills to recharge your mobile phone | CrazyEngineers 1/19/2014

Chiao, Jung-Chih


The clinical potential of microRNAs  

Microsoft Academic Search

MicroRNAs are small noncoding RNAs that function to control gene expression. These small RNAs have been shown to contribute to the control of cell growth, differentiation and apoptosis, important features related to cancer development and progression. In fact, recent studies have shown the utility of microRNAs as cancer-related biomarkers. This is due to the finding that microRNAs display altered expression

Anuradha Budhu; Junfang Ji; Xin W Wang



MicroRNA and Colorectal Cancer  

Microsoft Academic Search

MicroRNAs are small 19 to 22 nucleotide sequences of RNA that participate in the regulation of cell differentiation, cell\\u000a cycle progression, and apoptosis. MicroRNAs act much like small interfering RNA, annealing with RISC, to cleave messenger\\u000a RNA, and microRNAs exert translational inhibition that is incompletely understood. They are important factors in tumorigenesis\\u000a and have been the subject of research in

Linda Yang; Narasimhaswamy Belaguli; David H. Berger



Micro-Pattern Gaseous Detector Technologies and RD51 Collaboration  

NASA Astrophysics Data System (ADS)

Discoveries in particle physics vitally depend on parallel advances in radiation-detector technologies. A true innovation in detector instrumentation concepts came in 1968, with the development of a fully parallel readout for a large array of sensing elements — the Multi-Wire Proportional Chamber (MWPC), which earned Georges Charpak a Nobel Prize in Physics in 1992. This invention revolutionized particle detection which moved from optical-readout devices (cloud chamber, emulsion or bubble chambers) to the electronics era. Over the past two decades advances in photo-lithography, microelectronics and printed-circuit board (PCB) techniques triggered a major transition in the field of gas detectors from wire structures to the Micro-Pattern Gas Detector (MPGD) concepts. The excellent spatial and time resolution, high rate capability, low mass, large active areas, and radiation hardness make them an invaluable tool to confront future detector challenges at the frontiers of research. The design of the new micro-pattern devices appears suitable for industrial production. Novel devices where MPGDs are directly coupled to the CMOS pixel readout serve as an "electronic bubble chamber" allowing to record space points and tracks in 3D. In 2008, the RD51 collaboration at CERN has been established to further advance technological developments of MPGDs and associated electronic-readout systems, for applications in basic and applied research. This review provides an overview of the state-of-the-art of the MPGD technologies and summarizes ongoing activities within the framework of the RD51 collaboration.

Titov, Maxim; Ropelewski, Leszek



Micro-coil detection of nuclear magnetic resonance for nanofluidic samples  

NASA Astrophysics Data System (ADS)

We have developed a novel dc SQUID system with a micro-coil input circuit to act as a local probe of quantum matter and nanosystems. The planar niobium micro-coil pickup loop is located remotely from the SQUID, coupled through a superconducting twisted pair. A high degree of coupling between the coil and the region of interest of similar dimensions (up to ˜ 100 microns) can be achieved. We report nuclear magnetic resonance (NMR) measurements to characterise the sensitivity of these coils to 3He in the gas phase at 4.2 K in a 30 mT magnetic field.

Shibahara, A.; Casey, A.; Lusher, C. P.; Saunders, J.; Aßmann, C.; Schurig, Th.; Drung, D.



Experimental and Computational Investigation of a RF Plasma Micro-Thruster  

SciTech Connect

A prototype RF plasma micro-thruster has been investigated numerically and experimentally. The experimental results were obtained on a thrust stand capable of micro-Newton resolution. Thrust and mass flow (hence specific impulse) were measured for an argon propellant at mass flows ranging from 0.4 to 5.5 mg/s. An increase over the cold gas thrust of up to 20% was observed for a discharge frequency of 100 MHz and an input power of 77 W. Propulsive efficiency was seen to increase both experimentally and numerically for increasing mass flow and decreasing discharge frequency.

Olliges, J. D. [University of Southern California, Aerospace and Mechanical Engineering, Los Angeles, CA 90089 (United States); Ketsdever, A. D. [Air Force Research Laboratory, Edwards AFB, CA 93524 (United States); Stein, W. B.; Alexeenko, A. A.; Hrbud, I. [Purdue University, School of Aeronautical and Astronautical Engineering, West Lafayette, IN 47907 (United States)



A suite of software for processing MicroED data of extremely small protein crystals  

PubMed Central

Electron diffraction of extremely small three-dimensional crystals (MicroED) allows for structure determination from crystals orders of magnitude smaller than those used for X-ray crystallography. MicroED patterns, which are collected in a transmission electron microscope, were initially not amenable to indexing and intensity extraction by standard software, which necessitated the development of a suite of programs for data processing. The MicroED suite was developed to accomplish the tasks of unit-cell determination, indexing, background subtraction, intensity measurement and merging, resulting in data that can be carried forward to molecular replacement and structure determination. This ad hoc solution has been modified for more general use to provide a means for processing MicroED data until the technique can be fully implemented into existing crystallographic software packages. The suite is written in Python and the source code is available under a GNU General Public License. PMID:24904248

Iadanza, Matthew G.; Gonen, Tamir



Detection biomarkers of lung cancer using mini-GC-PID system integrated with micro GC column and micro pre-concentrator  

PubMed Central

The survival rate of lung cancer can be significantly improved by monitoring biomarkers in exhaled air that indicate diseases in early stage, so it is very important to develop micro analytical systems which can offer a fast, on-site, real-time detecting biomarkers in exhaled air. In this paper, a mini-gas chromatography (GC)-photo-ionization detector (PID) system integrated with a micro GC column and a micro pre-concentrator was developed for forming an inexpensive, fast, and non-invasive diagnostic tool for lung cancer. This system has very strong concentrate ability owing to its integrated micro pre-concentrator, which make the detection of trace components in exhaled air very easy. In addition, the integrated micro GC column can separate complex mixtures, which overcome low resolution and poor anti-interference ability of other instruments. The results indicated that the mini-GC-PID system can effectively separate and detect the biomarkers at parts-per-billion (ppb) level. PMID:25339856



Detection biomarkers of lung cancer using mini-GC-PID system integrated with micro GC column and micro pre-concentrator  

NASA Astrophysics Data System (ADS)

The survival rate of lung cancer can be significantly improved by monitoring biomarkers in exhaled air that indicate diseases in early stage, so it is very important to develop micro analytical systems which can offer a fast, on-site, real-time detecting biomarkers in exhaled air. In this paper, a mini-gas chromatography (GC)-photo-ionization detector (PID) system integrated with a micro GC column and a micro pre-concentrator was developed for forming an inexpensive, fast, and non-invasive diagnostic tool for lung cancer. This system has very strong concentrate ability owing to its integrated micro pre-concentrator, which make the detection of trace components in exhaled air very easy. In addition, the integrated micro GC column can separate complex mixtures, which overcome low resolution and poor anti-interference ability of other instruments. The results indicated that the mini-GC-PID system can effectively separate and detect the biomarkers at parts-per-billion (ppb) level.

Sun, Jianhai; Cui, Dafu; Guan, Fengying; Zhang, Lulu; Chen, Xing; Li, Hui



Analytical approaches in microRNA therapeutics.  


MicroRNAs are non-coding oligonucleotides with regulatory roles in virtually all biological processes. Deregulation of microRNAs lead to impaired cellular function and disease development. Thus, microRNAs are of potential diagnostic and therapeutic relevance. Several technology platforms are currently available for quantitative microRNA analysis and profiling, including the most extensively used PCR-based methods. Each of these technologies has its own advantages and limitations. Mass spectrometry combines low-level detectability with high selectivity and has been used for oligonucleotide sequence analysis. Its use for native microRNA analysis has been limited due to the very low abundance and chemical similarity of microRNAs. However, with the advancement of technology, this analytical method has become a powerful complementary tool for comprehensive analysis of native and synthetic microRNAs. This brief review highlights current developments in the field of microRNA analytics, detection techniques for extracellular microRNAs, their synthetic inhibitors, and the dynamics of their interactions. PMID:24908160

Batkai, Sandor; Thum, Thomas



3D micro-EDM machining technique  

NASA Astrophysics Data System (ADS)

The micro-EDM machining technique has been broadly applied to fabricate 2D and 3D micro-parts. It is difficult to produce a metal mold with dimension from several micrometers and with the accuracy in the level of micrometers . Poor accuracy comes from electrode wear during 3D micro-EDM machining. In this research, an efficient wear compensation cooperated with CAD/CAM path compensation is provided to improve the machining accuracy. In the experiments, by fabricating a micro-gear and sculpturing letters on surface of tiny steel ball, the technique provided in this research shows the expected results successfully.

Kuo, Chia-Lung; Chen, Shung-Tong; Wu, Ying-Jeng E.; Yen, Albert T.



Assembly planning at the micro scale  

SciTech Connect

This paper investigates a new aspect of fine motion planning for the micro domain. As parts approach 1--10 {micro}m or less in outside dimensions, interactive forces such as van der Waals and electrostatic forces become major factors which greatly change the assembly sequence and path plans. It has been experimentally shown that assembly plans in the micro domain are not reversible, motions required to pick up a part are not the reverse of motions required to release a part. This paper develops the mathematics required to determine the goal regions for pick up, holding, and release of a micro-sphere being handled by a rectangular tool.

Feddema, J.T.; Xavier, P.; Brown, R.



Three-Dimensional Characterization of the Vascular Bed in Bone Metastasis of the Rat by Microcomputed Tomography (MicroCT)  

PubMed Central

Background Angiogenesis contributes to proliferation and metastatic dissemination of cancer cells. Anatomy of blood vessels in tumors has been characterized with 2D techniques (histology or angiography). They are not fully representative of the trajectories of vessels throughout the tissues and are not adapted to analyze changes occurring inside the bone marrow cavities. Methodology/Principal Findings We have characterized the vasculature of bone metastases in 3D at different times of evolution of the disease. Metastases were induced in the femur of Wistar rats by a local injection of Walker 256/B cells. Microfil®, (a silicone-based polymer) was injected at euthanasia in the aorta 12, 19 and 26 days after injection of tumor cells. Undecalcified bones (containing the radio opaque vascular casts) were analyzed by microCT, and a first 3D model was reconstructed. Bones were then decalcified and reanalyzed by microCT; a second model (comprising only the vessels) was obtained and overimposed on the former, thus providing a clear visualization of vessel trajectories in the invaded metaphysic allowing quantitative evaluation of the vascular volume and vessel diameter. Histological analysis of the marrow was possible on the decalcified specimens. Walker 256/B cells induced a marked osteolysis with cortical perforations. The metaphysis of invaded bones became progressively hypervascular. New vessels replaced the major central medullar artery coming from the diaphyseal shaft. They sprouted from the periosteum and extended into the metastatic area. The newly formed vessels were irregular in diameter, tortuous with a disorganized architecture. A quantitative analysis of vascular volume indicated that neoangiogenesis increased with the development of the tumor with the appearance of vessels with a larger diameter. Conclusion This new method evidenced the tumor angiogenesis in 3D at different development times of the metastasis growth. Bone and the vascular bed can be identified by a double reconstruction and allowed a quantitative evaluation of angiogenesis upon time. PMID:21464932

Nyangoga, Herve; Mercier, Philippe; Libouban, Helene; Basle, Michel Felix; Chappard, Daniel



Micro-machined three-dimensional micro-optics for integrated free-space optical system  

Microsoft Academic Search

Novel, integrable three-dimensional micro-optical elements have been realized by surface micromachining technology. Rotatable mirrors, lenses and beam-splitters standing perpendicular to the substrate are demonstrated. The optical elements are precisely held at 90° angle to the substrate by side latches. The Si substrate serves as a “micro-optical bench” on which monolithic micro-optical systems consisting of movable and static micro-mirrors, lenses and

L. Y. Lin; S. S. Lee; K. S. J. Pister; M. C. Wu



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

E-print Network

EE 337 Engineering micro and nano-systems Page 1 EE 337 Engineering micro and nano-systems This course is designed 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

Levi, Anthony F. J.


Prioritization of disease microRNAs through a human phenome-microRNAome network  

Microsoft Academic Search

BACKGROUND: The identification of disease-related microRNAs is vital for understanding the pathogenesis of diseases at the molecular level, and is critical for designing specific molecular tools for diagnosis, treatment and prevention. Experimental identification of disease-related microRNAs poses considerable difficulties. Computational analysis of microRNA-disease associations is an important complementary means for prioritizing microRNAs for further experimental examination. RESULTS: Herein, we devised

Qinghua Jiang; Yangyang Hao; Guohua Wang; Liran Juan; Tianjiao Zhang; Mingxiang Teng; Yunlong Liu; Yadong Wang



Development of Exhaust Gas Driven Absorption Chiller-Heater  

NASA Astrophysics Data System (ADS)

Micro gas turbines are expected as engines for the distributed co-generation systems, performing power generation and heat recovery. Waste heat from micro gas turbines are discharged in the form of exhaust gas, and it is simple that exhaust gas is directly supplied to an absorption refrigerator. In this paper, we evaluated various single-double effect absorption cycles for exhaust gas driven absorption refrigerators, and clarified that the difference of performance among these cycles are little. We adopted one of these cycles for the prototype machine, and experimented with it to get the partial load characteristics and the effect of cooling water temperature on the performance. Based on the experimental data, we developed as imulation model of the static characteristics, and studied the direction of improvement.

Inoue, Naoyuki; Endou, Tetsuya; Saito, Kiyoshi; Kawai, Sunao


[N2O production in nitrogen removal by micro-expansion of granular sludge].  


Controlled low dissolved oxygen (DO) in a sequencing batch reactor (SBR) was used to study the realization of micro-expansion of aerobic granular sludge, and the removal efficiency of COD and NH4+ -N as well as the production of the greenhouse gas N2O by the micro-expansion of granular sludge was investigated. The results showed that under the condition of low dissolved oxygen micro-expansion of sludge could be achieved, and the sludge volume index (SVI) was mostly in the range of 150-250 mL x g(-1). The micro-expansion of granular sludge did not have significant influence on the removal of COD and NH4+ -N. The COD removal rate increased from 89.45% to 90.99%, the NH4+ -N removal rate decreased from 77.29% to 68.29%, and the nitrification rate dropped from 38.95 x 10(-3) mg (g x min)(-1) to 33.46 x 10(-3) mg x (g x min)(-1). The micro-expansion of granular sludge had a big influence on the production of N2O, and the N2O production by the micro-expanded granular sludge was 2.42 mg x m(-3), which was 1.26 times of the N2O production of the granular sludge without micro-expansion. The N2O release rate in the micro-expanded granular sludge increased from 3.63 x 10(-3) mg x (L x min)(-1) to 4.72 x 10(-3) mg x (L x min)(-1). PMID:24289001

Chen, Li-li; Gao, Da-wen



Research on the Modulating of the Desktop Micro Forming System to Micro Factory  

Microsoft Academic Search

The micro pump module is used in so many MEMS applications, such as medical, fuel cell, display and chemistry fields. The micro pump module is consisted of actuating component, chamber plate, upper\\/lower fluidic channel plates and thin valve. This micro pump must have a specific performance that is high compressibility and high speed operating response. A polymer thin film is

Hye-Jin Lee; Nak-Kyu Lee; Geun-An Lee; Hyoung-Wook Lee; Seogou Choi; Eun-Duk Chu; Taejoo Kim; Junhee Shin




E-print Network

THE POTENTIAL FOR MICRO-ALGAE AND OTHER "MICRO-CROPS" TO PRODUCE SUSTAINABLE BIOFUELS A REVIEW INTRODUCTION Biofuel derived from algae and other micro-crops has been proposed as an environmentally benign model systems of algae-based biofuel production, exploring potential economic costs and environmental

Edwards, Paul N.


Micro Coriolis Mass Flow Sensor with Extended Range for a Monopropellant Micro Propulsion System  

E-print Network

for the measurement of hydrazine (N2H4, High Purity Grade) propellant flow in micro chemical propulsion systems to the designed bypass ratio. Key words: micro Coriolis flow sensor, hydrazine flow measurement, surface channel of the hydrazine propellant flow. The sensor will first be used for measurement and characterization of the micro


A high-efficiency approach for fabricating mass micro holes by batch micro EDM  

NASA Astrophysics Data System (ADS)

This work is a follow-up study based on previous research. The study presents a novel approach for effective production of mass micro holes. Initially, a set of micro w-EDM mechanisms is designed and mounted on the developed precise tabletop CNC machine tool to fabricate the micro electrode array. The tension of the micro wire is precisely controlled by a magnetic force. Furthermore, micro vibrations of the wire during discharging are effectively suppressed by the developed vibration suppression system. To fabricate the mass micro holes, a microstructure array with a high-aspect ratio of 10 × 10 micro squared electrodes, width and height of 21 µm and 700 µm, respectively, for each electrode and 24 µm spacing between two electrodes is fabricated first by using the proposed 'reverse w-EDM' machining strategy. The electrodes array is directly utilized to drill the mass micro holes by bath micro EDM on the same machine. An array of 900 through-holes of the same size is successfully fabricated via the modified peck-drilling method on a 30 µm thick stainless-steel plate. A tip at the free end of the micro electrode is designed and fabricated as a circular-pyramid shape. Experimental results verified that the spiky end form eliminates debris adhering to the edges of the micro holes. Analytical results demonstrate satisfactory hole geometric accuracy, dimensional accuracy and surface roughness. Furthermore, mass micro holes can be fabricated efficiently using the proposed technique.

Chen, Shun-Tong



Gas Properties  

NSDL National Science Digital Library

Pump gas molecules to a box and see what happens as you change the volume, add or remove heat, change gravity, and more. Measure the temperature and pressure, and discover how the properties of the gas vary in relation to each other.

Simulations, Phet I.; Barbera, Jack; Dubson, Michael; Koch, Linda; Lemaster, Ron; Perkins, Kathy



A Rapid Micro Polymerase Chain Reaction System (GenSpector Micro PCR) for Hepatitis B Virus DNA Detection  

E-print Network

A Rapid Micro Polymerase Chain Reaction System (GenSpector® Micro PCR) for Hepatitis B Virus DNA a rapid micro PCR (polymerase chain reaction) system (GenSpector® Micro PCR) for the application of Technology, PO Box 111, Suwon 440-600, Korea Abstract This paper presents a rapid micro PCR (polymerase chain

Oh, Kwang W.


Micromachining of buried micro channels in silicon  

Microsoft Academic Search

A new method for the fabrication of micro structures for fluidic applications, such as channels, cavities, and connector holes in the bulk of silicon wafers, called buried channel technology (BCT), is presented in this paper. The micro structures are constructed by trench etching, coating of the sidewalls of the trench, removal of the coating at the bottom of the trench,

Meint J. de Boer; R. Willem Tjerkstra; J. W. Berenschot; Henri V. Jansen; G. J. Burger; J. G. E. Gardeniers; Miko Elwenspoek; Berg van den Albert



The shrinking sizes in micro manufacturing  

Microsoft Academic Search

A report on a seminar in “Micro and nano manufacturing” is organised by the UK Manufacturing Technology Association in partnership with the University of Birmingham School of Engineering's Machining Research Group. It covers presentations from UK industry and academia plus two from European organisations. The state of micro and nanomanufacturing in the UK is presented and some of the processes

Brian Rooks



Wafer-scale micro-optics fabrication  

NASA Astrophysics Data System (ADS)

Micro-optics is an indispensable key enabling technology for many products and applications today. Probably the most prestigious examples are the diffractive light shaping elements used in high-end DUV lithography steppers. Highly-efficient refractive and diffractive micro-optical elements are used for precise beam and pupil shaping. Micro-optics had a major impact on the reduction of aberrations and diffraction effects in projection lithography, allowing a resolution enhancement from 250 nm to 45 nm within the past decade. Micro-optics also plays a decisive role in medical devices (endoscopes, ophthalmology), in all laser-based devices and fiber communication networks, bringing high-speed internet to our homes. Even our modern smart phones contain a variety of micro-optical elements. For example, LED flash light shaping elements, the secondary camera, ambient light and proximity sensors. Wherever light is involved, micro-optics offers the chance to further miniaturize a device, to improve its performance, or to reduce manufacturing and packaging costs. Wafer-scale micro-optics fabrication is based on technology established by the semiconductor industry. Thousands of components are fabricated in parallel on a wafer. This review paper recapitulates major steps and inventions in wafer-scale micro-optics technology. The state-of-the-art of fabrication, testing and packaging technology is summarized.

Voelkel, Reinhard



Collector Pressure Losses in Micro Heat Exchangers  

Microsoft Academic Search

As collector losses are expected to play a crucial role in micro heat exchangers, an experimental method is developed to determine these losses. Experiments are performed on a micro heat exchanger consisting of 42 parallel microchannels positioned in a 6 by 7 matrix, with hydraulic diameters in the range of 260-280 mum. The proposed method is successfully applied. From the

M. Baelmans



Nuclear microbatteries for micro and nano Devices  

Microsoft Academic Search

Radioisotopes have many applications. Among the various technologies for micro power generation being investigated, nuclear microbatteries that convert the kinetic energy of charged particles emitted from the radioisotopes into electricity are very attractive for many applications. In this paper, the previous work on developing nuclear microbatteries for micro and nano devices, including two types of microbatteries, betavoltaic microbatteries and direct

Hang Guo; Hui Li; A. Lal; J. Blanchard



Projet TESEER Thermoelectric micro Energy Source  

E-print Network

Projet TESEER Thermoelectric micro Energy Source Enhanced by Electromagnetic Radiation Participants of silicon to be used as a hot-spot for a thermoelectric element. Applications also exists for PV cells) Thermoelectric micro Energy Source Enhanced by Electromagnetic Radiation Objectifs Le projet TESEER consiste

Baudoin, Geneviève


A Micro-Electrochemical Study of Friction Stir Welded Aluminum 6061-T6  

NASA Technical Reports Server (NTRS)

The corrosion behavior of friction stir welded Aluminum alloy 606 1-T6 was studied using a micro-electrochemical cell. The micro-electrochemical cell has a measurement area of about 0.25 square mm which allows for measurement of corrosion properties at a very small scale. The corrosion and breakdown potentials were measured at many points inside and outside the weld along lines perpendicular to the weld. The breakdown potential is approximately equal inside and outside the weld; however, it is lower in the narrow border between the weld and base material. The results of electrochemical measurements were correlated to micro-structural analysis. The corrosion behavior of the friction stir welded samples was compared to tungsten inert gas (TIG) welded samples of the same material.

Hintze, Paul E.; Calle, Luz M.



Micro architecture : architecture for daily social activities within Beijing's hutongs  

E-print Network

This thesis is an attempt to propose the alternative architectural strategy which derives from the Micro Urbanism in the micro-scale realm in the Asian main cities. Based on the Micro Urbanism, the project is to propose a ...

Chao, Yi-Hsiang



Micro-Scale Regenerative Heat Exchanger  

NASA Technical Reports Server (NTRS)

A micro-scale regenerative heat exchanger has been designed, optimized and fabricated for use in a micro-Stirling device. Novel design and fabrication techniques enabled the minimization of axial heat conduction losses and pressure drop, while maximizing thermal regenerative performance. The fabricated prototype is comprised of ten separate assembled layers of alternating metal-dielectric composite. Each layer is offset to minimize conduction losses and maximize heat transfer by boundary layer disruption. A grating pattern of 100 micron square non-contiguous flow passages were formed with a nominal 20 micron wall thickness, and an overall assembled ten-layer thickness of 900 microns. Application of the micro heat exchanger is envisioned in the areas of micro-refrigerators/coolers, micropower devices, and micro-fluidic devices.

Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred



MicroComputed Tomography: Methodology and Applications  

SciTech Connect

Due to the availability of commercial laboratory systems and the emergence of user facilities at synchrotron radiation sources, studies of microcomputed tomography or microCT have increased exponentially. MicroComputed Technology provides a complete introduction to the technology, describing how to use it effectively and understand its results. The first part of the book focuses on methodology, covering experimental methods, data analysis, and visualization approaches. The second part addresses various microCT applications, including porous solids, microstructural evolution, soft tissue studies, multimode studies, and indirect analyses. The author presents a sufficient amount of fundamental material so that those new to the field can develop a relative understanding of how to design their own microCT studies. One of the first full-length references dedicated to microCT, this book provides an accessible introduction to field, supplemented with application examples and color images.




Polymer micro-fiber Bragg grating.  


Polymer micro-fibers with inscribed Bragg gratings are reported in this Letter. Starting with a single-mode polymer optical fiber and implementing a two-stage tapering process, a 16 ?m diameter micro-fiber is fabricated and a Bragg grating is inscribed in it that exhibits a peak reflected wavelength circa 1530 nm. The growth dynamics of the polymer micro-fiber Bragg grating are also observed and analyzed. A maximum reflectivity of 5% is obtained after an exposure time of 3 min to a 50 mW power He-Cd laser of 325 nm wavelength. The temperature and strain characterization results of the micro-fiber Bragg grating with different diameters are also presented. Such polymer micro-fiber Bragg gratings can be used as sensors for high-sensitivity measurements in a number of application areas. PMID:23988957

Rajan, Ginu; Noor, Muhammad Yusof Mohd; Lovell, Nigel H; Ambikaizrajah, Eliathamby; Farrell, Gerald; Peng, Gang-Ding



Micro and Nano Systems for Space Exploration  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the use of micro and nano systems in Space exploration. Included are: an explanation of the rationales behind nano and micro technologies for space exploration, a review of how the devices are fabricated, including details on lithography with more information on Electron Beam (E-Beam) lithography, and X-ray lithography, a review of micro gyroscopes and inchworm Microactuator as examples of the use of MicroElectoMechanical (MEMS) technology. Also included is information on Carbon Nanotubes, including a review of the CVD growth process. These micro-nano systems have given rise to the next generation of miniature X-ray Diffraction, X-ray Fluorescence instruments, mass spectrometers, and terahertz frequency vacuum tube oscillators and amplifiers, scanning electron microscopes and energy dispersive x-ray spectroscope. The nanotechnology has also given rise to coating technology, such as silicon nanotip anti-reflection coating.

Manohara, Harish



Micro-modulated luminescence tomography  

E-print Network

Imaging depth of optical microscopy has been fundamentally limited to millimeter or sub-millimeter due to light scattering. X-ray microscopy can resolve spatial details of few microns deeply inside a sample but the contrast resolution is still inadequate to depict heterogeneous features at cellular or sub-cellular levels. To enhance and enrich biological contrast at large imaging depth, various nanoparticles are introduced and become essential to basic research and molecular medicine. Nanoparticles can be functionalized as imaging probes, similar to fluorescent and bioluminescent proteins. LiGa5O8:Cr3+ nanoparticles were recently synthesized to facilitate luminescence energy storage with x-ray pre-excitation and the subsequently stimulated luminescence emission by visible/near-infrared (NIR) light. In this paper, we suggest a micro-modulated luminescence tomography (MLT) approach to quantify a nanophosphor distribution in a thick biological sample with high resolution. Our numerical simulation studies demonst...

Cong, Wenxiang; Wang, Chao; Wang, Ge



Designing a micro-spacecraft  

NASA Technical Reports Server (NTRS)

Planetary spacecraft design could move toward less complex probes which would cost less then previous highly instrumented missions. The goal then becomes to fly more frequent missions and use commercial, proven hardware to ameliorate development costs. A commonality would be kept in place from spacecraft to spacecraft, with upgrades being introduced only to meet specific objectives or take advantage of advances in commercial hardware. Mission costs are in large part determined by spacecraft mass, so instrumentation must be miniaturized, i.e., the concept of a micro-satellite. A design study for the Cosimi project, which would feature placing a spacecraft on the far side of the solar corona to broadcast radio signals to earth, demonstrates the feasibility of a 20 cm diam rocket and integrated instruments for performing low-cost solar physics experiments. It is concluded, however, that current program start-ups will continue to maximize the mass and instrumentation of spacecraft.

Burke, J. D.



MicroRNAs and atherosclerosis  

PubMed Central

MicroRNAs (miRNAs) are small (~22nucleotide) sequences of RNA that regulate gene expression at posttranscriptional level. MiRNA/mRNA base pairing complementarity provokes mRNA decay and consequent gene silencing. These endogenous gene expression inhibitors were primarily described in cancer but recent exciting findings have also demonstrated a key role in cardiovascular diseases (CVDs) including atherosclerosis. MiRNAs controls endothelial cell (EC), vascular smooth muscle cell (VSMC) and macrophage functions, and thereby regulate the progression of atherosclerosis. MiRNAs expression is modulated by different stimuli involved in every stage of atherosclerosis and conversely miRNAs modulates several pathways implicated in plaque development such as cholesterol metabolism. In the present review, we focus on the importance of miRNAs in atherosclerosis and we further discuss their potential use as biomarkers and therapeutic targets in CVDs. PMID:23512606

Madrigal-Matute, Julio; Rotllan, Noemi; Aranda, Juan F.; Fernandez-Hernando, Carlos



MicroRNAs in cancer.  


MicroRNAs (miRNAs) are small noncoding RNAs that typically inhibit the translation and stability of messenger RNAs (mRNAs), controlling genes involved in cellular processes such as inflammation, cell-cycle regulation, stress response, differentiation, apoptosis, and migration. Thus, miRNAs have been implicated in the regulation of virtually all signaling circuits within a cell, and their dysregulation has been shown to play an essential role in the development and progression of cancer. Here, after a brief description of miRNA genomics, biogenesis, and function, we discuss the effects of miRNA dysregulation in the cellular pathways that lead to the progressive conversion of normal cells into cancer cells and the potential to develop new molecular miRNA-targeted therapies. PMID:24079833

Di Leva, Gianpiero; Garofalo, Michela; Croce, Carlo M



Natural Gas  

NASA Astrophysics Data System (ADS)

Natural gas is a naturally occurring mixture of simple hydrocarbons and nonhydrocarbons that exists as a gas at ordinary pressures and temperatures. In the raw state, as produced from the earth, natural gas consists principally of methane (CH4) and ethane (C2H4), with fractional amounts of propane (C3H8), butane (C4H10), and other hydrocarbons, pentane (C5H12) and heavier. Occasionally, small traces of light aromatic hydrocarbons such as benzene and toluene may also be present.

Maddox, Robert N.; Moshfeghian, Mahmood; Ldol, James D.; Johannes, Arland H.


Machining of micro rotational parts by wire electrical discharge grinding  

Microsoft Academic Search

Micro rotational parts are used in several industrial sectors. Well-known applications are micro shafts of gears, ejector\\u000a pins in forming tools, pin electrodes for micro electrical discharge drilling or micro stamping dies. Depending on the geometrical\\u000a complexity of micro rotational parts different process variants of micro electrical discharge machining characterized by a\\u000a rotating work piece can be used: wire electrical

E. Uhlmann; S. Piltz; D. Oberschmidt



PRD-66 Gas Filter Development  

SciTech Connect

The PRD-66 manufacturing process offers a unique approach to the production of hot gas candle filters for application in Pressurized Fluidized Bed Combustors (PFBC) and Integrated Gas Combined Cycle (IGCC) power systems. Fabricated from readily available and inexpensive raw materials, the PRD-66 process uses an admixture of textile and ceramic concepts to produce an all-oxide filter element containing no refractor ceramic fiber (RCF) residues in the finished products. The use demonstration of textile grade glass yarn as a consumable reactant gives the advantages of fabrication versatility and shape control and a unique micro-layered phase structure in the fired product, resulting in unsurpassed thermal shock resistance and operating temperature capability of greater than 1200{degrees}C in a low-cost package. This high throughput, adaptable process allows tailoring of filter element dimensions and operating properties to specific system needs with short lead times and low cost penalties.

Forsythe, G.D.; Connolly, E.S.



Gas Analyzer  

NASA Technical Reports Server (NTRS)

The M200 originated in the 1970's under an Ames Research Center/Stanford University contract to develop a small, lightweight gas analyzer for Viking Landers. Although the unit was not used on the spacecraft, it was further developed by The National Institute for Occupational Safety and Health (NIOSH). Three researchers from the project later formed Microsensor Technology, Inc. (MTI) to commercialize the analyzer. The original version (Micromonitor 500) was introduced in 1982, and the M200 in 1988. The M200, a more advanced version, features dual gas chromatograph which separate a gaseous mixture into components and measure concentrations of each gas. It is useful for monitoring gas leaks, chemical spills, etc. Many analyses are completed in less than 30 seconds, and a wide range of mixtures can be analyzed.



[Development of a micro-infrared spectrometer based on pulse infrared light source and two-double light route].  


A novel micro infrared spectrometer was designed which is different from traditional grating scanning one. This micro spectrometer introduced an uncooled infrared detector LiTaO3 with high sensitivity and small volume, and a MEMS pulsed infrared light source was adopted as emitter and chopper, which threw off traditional mechanical chopper. Combined with the design of a two-double light route, the volume of micro spectrometer was made even smaller. Primary results show that the design method of micro-infrared spectrometer is feasible, the wavelength range of instrument is wide, from 2000 to 5000 nm, and spectrum bandwidth is about 45 nm, which can be used for the sample analysis, such as plastic films, biologic liquid, environmental gas and so on. PMID:17554937

Du, Xiao-qing; Wen, Zhi-yu; Xiang, Xian-yi; Long, Zai-chuan; Liu, Hai-tao; Chen, Qin



Fabrication of a micro-tool in micro-EDM combined with co-deposited Ni SiC composites for micro-hole machining  

Microsoft Academic Search

This paper presents an in situ process using a micro-tool in micro-electro-discharge-machining combined with co-deposited Ni-SiC composites to drill and finish micro-holes. During the machining process, a micro-tool is fabricated by wire electro-discharge grinding and electrodeposition. The experimental result shows that the suitable parameters obtained for fabricating micro-tools for Ni-SiC composite coatings are a current density of 7 A dm-2,

Jung-Chou Hung; Wei-Chieh Wu; Biing-Hwa Yan; Fuang-Yuan Huang; Kun-Ling Wu



Integrated Mirco-Machined Hydrogen Gas Sensors  

SciTech Connect

The widespread use of hydrogen as both an industrial process gas and an energy storage medium requires fast, selective detection of hydrogen gas. This report discusses the development of a new type of solid-state hydrogen gas sensor that couples novel metal hydride thin films with a MEMS (Micro-Electro-Mechanical System) structure known as a micro-hotplate. In this project, Micro-hotplate structures were overcoated with engineered multilayers that serve as the active hydrogen-sensing layer. The change in electrical resistance of these layers when exposed to hydrogen gas was the measured sensor output. This project focused on achieving the following objectives: (1) Demonstrating the capabilities of micro-machined H2 sensors; (2) Developing an understanding of their performance; (3) Critically evaluating the utility and viability of this technology for life safety and process monitoring applications. In order to efficiently achieve these objectives, the following four tasks were identified: (1) Sensor Design and Fabrication; (2) Short Term Response Testing; (3) Long Term Behavior Investigation; (4) Systems Development. Key findings in the project include: The demonstration of sub-second response times to hydrogen; measured sensitivity to hydrogen concentrations below 200 ppm; a dramatic improvement in the sensor fabrication process and increased understanding of the processing properties and performance relationships of the devices; the development of improved sensing multilayers; and the discovery of a novel strain based hydrogen detection mechanism. The results of this program suggest that this hydrogen sensor technology has exceptional potential to meet the stringent demands of life safety applications as hydrogen utilization and infrastructure becomes more prevalent.

Frank DiMeoJr. Ing--shin Chen



Dual-energy micro-CT imaging of pulmonary airway obstruction: correlation with micro-SPECT  

NASA Astrophysics Data System (ADS)

To match recent clinical dual energy (DE) CT studies focusing on the lung, similar developments for DE micro-CT of the rodent lung are required. Our group has been actively engaged in designing pulmonary gating techniques for micro- CT, and has also introduced the first DE micro-CT imaging method of the rodent lung. The aim of this study was to assess the feasibility of DE micro-CT imaging for the evaluation of airway obstruction in mice, and to compare the method with micro single photon emission computed tomography (micro-SPECT) using technetium-99m labeled macroaggregated albumin (99mTc-MAA). The results suggest that the induced pulmonary airway obstruction causes either atelectasis, or air-trapping similar to asthma or chronic bronchitis. Atelectasis could only be detected at early time points in DE micro-CT images, and is associated with a large increase in blood fraction and decrease in air fraction. Air trapping had an opposite effect with larger air fraction and decreased blood fraction shown by DE micro-CT. The decrease in perfusion to the hypoventilated lung (hypoxic vasoconstriction) is also seen in micro-SPECT. The proposed DE micro-CT technique for imaging localized airway obstruction performed well in our evaluation, and provides a higher resolution compared to micro-SPECT. Both DE micro-CT and micro-SPECT provide critical, quantitative lung biomarkers for image-based anatomical and functional information in the small animal. The methods are readily linked to clinical methods allowing direct comparison of preclinical and clinical results.

Badea, C. T.; Befera, N.; Clark, D.; Qi, Y.; Johnson, G. A.



Formability of Micro-Tubes in Hydroforming  

NASA Astrophysics Data System (ADS)

Micro-hydroforming is a down-scaled metal forming process, based on the expansion of micro-tubes by internal pressurization within a die cavity. The objective of micro-hydroforming is to provide a technology for the economic mass production of complex shaped hollow micro-components. Influence of size effects in metal forming processes increases with scaling down of metal parts. Investigations into the change in formability of micro-tubes due to metal part scaling down constituted an important subject within the conducted fundamental research work. Experimental results are presented, concerning the analysis of the formability of micro-tubes made from stainless steel AISI 304 with an outer diameter of 800 ?m and a wall thickness of 40 ?m. An average ratio of tube wall thickness to grain size of 1.54 of up to 2.56 was analyzed. Miniaturised mechanical standard methods as well as bulge tests with internal hydrostatic pressurization of the tubular specimens were applied to analyze the influence of size-dependent effects. A test device was developed for the bulge experiments which enabled the pressurization of micro-tubes with internal pressures up to 4000 bar. To determine the attainable maximum achievable expansion ratio the tubes were pressurized in the bulge tests with increasing internal pressure until instability due to necking and subsequent bursting occurred. Comparisons with corresponding tests of macro-tubes, made from the here investigated material, showed a change in formability of micro-tubes which was attributed to the scaling down of the hydroforming process. In addition, a restricted applicability of existing theoretical correlations for the determination of the maximum pressure at bursting was observed for down-scaled micro-hydroforming.

Hartl, Christoph; Anyasodor, Gerald; Lungershausen, Joern



Study on micro-fabrication processes in CoFeB\\/MgO\\/CoFeB magnetic tunnel junctions  

Microsoft Academic Search

The effect of reactive ion etching (RIE) micro-fabrication process using methanol (CH3OH) gas on the magnetoresistance properties of CoFeB\\/MgO\\/CoFeB magnetic tunnel junctions (MTJs) was investigated in this paper. The result has been compared with that of the MTJs etched with ion-milling method.

H. Maehara; T. Osada; M. Doi; K. Sakamoto; K. Tsunekawa; D. D. Djayaprawira; Y. Kodaira; N. Watanabe; H. Kubota; A. Fukushima; Y. Otani; S. Yuasa; K. Ando



Novel gas-based detection techniques  

NASA Astrophysics Data System (ADS)

This year we celebrate the 100th birthday of gaseous detectors: Hans Geiger operated the first gas-filled counter in Manchester in 1908. The thin wires, essential for obtaining gas amplification, have been replaced by Micro Pattern Gas Detectors (MPGDs): Micromegas (1995) and GEM (1996). In the GridPix detector, each of the grid holes of a MPGD is equipped with its own electronic readout channel in the form of an active pixel in suitable pixel CMOS chips. By means of MEMS technology, the grid has been integrated with the chip, forming a monolithic readout device for gas volumes. By applying a protection layer made of hydrogenated amorphous silicon, the chips can be made spark proof. New protection layers have been made of silicon nitride. The use of gas as detection material for trackers is compared to Si, and the issue of chamber aging is addressed. New developments are set out: the development of Micro Channel Plates, integrated on pixel chips, the development of electron emission foil, and the realization of TimePix-2: a general-purpose pixel chip with time and amplitude measurement, per pixel, of charge signals.

van der Graaf, Harry



Gas Hydrates: It's A Gas!  

NSDL National Science Digital Library

In this activity, students will investigate the occurrence of gas hydrates on the ocean floor. They will discover the importance of carbon, where carbon is stored on Earth, and that the largest reservoir of carbon is gas hydrates. Students will discover that Earth's climate changes, and how the greenhouse effect works. They will also learn about the potential of hydrates as a major new energy resource and explore the conditions under which hydrates form.


Method of generating hydrogen gas from sodium borohydride  


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)



Characterization of the Micro-Welding Process for Repair of Nickel Base Superalloys  

Microsoft Academic Search

Micro-welding is a low-heat input process whereby a metal or cermet, is deposited by the generation of a low-power arc between\\u000a a consumable electrode and a substrate. The low-heat input of this process offers unique advantages over more common welding\\u000a processes such as gas tungsten arc, plasma arc, laser, and electron beam welding. At present, the repair of turbine blades

J. Durocher; N. L. Richards



Hydrodynamic behaviour of micro/nanoscale Poiseuille flow under thermal creep condition  

NASA Astrophysics Data System (ADS)

Current work investigates the effect of thermal creep on the behavior of rarefied gas flow through micro/nanochannels using the direct simulation Monte Carlo method. Thermal creep effects are studied on velocity profiles, streamwise velocity and pressure, and thermal mass flow rate. The strength of thermal creep is examined at different Knudsen number, channel pressure ratio, and bulk temperature. The thermal mass flow rate variation is investigated over a wide range of flow rarefaction from the slip to free molecular regime.

Akhlaghi, Hassan; Balaj, Mojtaba; Roohi, Ehsan



Catalyzed Combustion of Bipropellants for Micro-Spacecraft Propulsion  

NASA Technical Reports Server (NTRS)

This paper addresses the need to understand the physics and chemistry involved in propellant combustion processes in micro-scale combustors for propulsion systems on micro-spacecraft. These spacecraft are planned to have a mass less than 50 kilograms with attitude control estimated to be in the 10 milli-Newton thrust class. These combustors are anticipated to be manufactured using Micro Electrical Mechanical Systems (MEMS) technology and are expected to have diameters approaching the quenching diameter of the propellants. Combustors of this size are expected to benefit significantly from surface catalysis processes. Miniature flame tube apparatus is chosen for this study because microtubes can be easily fabricated from known catalyst materials and their simplicity in geometry can be used in fundamental simulations for validation purposes. Experimentally, we investigated the role of catalytically active surfaces within 0.4 and 0.8 mm internal diameter microtubes, with special emphases on ignition processes in fuel rich gaseous hydrogen and gaseous oxygen. Flame thickness and reaction zone thickness calculations predict that the diameters of our test apparatus are below the quenching diameter of the propellants in sub-atmospheric tests. Temperature and pressure rise in resistively heated platinum and palladium microtubes was used as an indication of exothermic reactions. Specific data on mass flow versus preheat temperature required to achieve ignition are presented. With a plug flow model, the experimental conditions were simulated with detailed gas-phase chemistry, thermodynamic properties, and surface kinetics. Computational results generally support the experimental findings, but suggest an experimental mapping of the exit temperature and composition is needed.

Schneider, Steven J.; Sung, Chih-Jen; Boyarko, George A.



A novel dual-detector micro-spectrometer  

NASA Astrophysics Data System (ADS)

Infrared analysis is a well-established tool for measuring composition and purity of various materials in industrial-, medical- and environmental applications. Traditional spectrometers, for example Fourier Transform Infrared (FTIR) Instruments are mainly designed for laboratory use and are generally, too large, heavy, costly and delicate to handle for remote applications. With important advances in the miniaturization, ruggedness and cost efficiency we have designed and created a new type of a micromirror spectrometer that can operate in harsh temperature and vibrating environments This device is ideally suited for environmental monitoring, chemical and biological applications as well as detection of biological warfare agents and sensing in important security locations In order to realize such compact, portable and field-deployable spectrometers we have applied MOEMS technology. Thus our novel dual detector micro mirror system is composed of a scanning micro mirror combined with a diffraction grating and other essential optical components in order to miniaturize the basic modular set-up. Especially it periodically disperses polychromatic radiation into its spectral components, which are measured by a combination of a visible (VIS) and near infrared (NIR) single element detector. By means of integrated preamplifiers high-precise measurements over a wide dynamic wavelength range are possible. In addition the spectrometer, including the radiation source, detectors and electronics can be coupled to a minimum-volume liquid or gas-flow cell. Furthermore a SMA connector as a fiber optical input allows easy attachment of fiber based probes. By utilizing rapid prototyping techniques, where all components are directly integrated, the micro mirror spectrometer is manufactured for the 700-1700 nm spectral range. In this work the advanced optical design and integration of the electronic interface will be reviewed. Furthermore we will demonstrate the performance of the system and present characteristic measurement results. Finally advanced packaging issues and test results of the device will be discussed.

Otto, Thomas; Saupe, Ray; Stock, Volker; Bruch, Reinhard; Gruska, Bernd; Gessner, Thomas



Hair-based sensors for micro-autonomous systems  

NASA Astrophysics Data System (ADS)

We seek to harness microelectromechanical systems (MEMS) technologies to build biomimetic devices for low-power, high-performance, robust sensors and actuators on micro-autonomous robot platforms. Hair is used abundantly in nature for a variety of functions including balance and inertial sensing, flow sensing and aerodynamic (air foil) control, tactile and touch sensing, insulation and temperature control, particle filtering, and gas/chemical sensing. Biological hairs, which are typically characterized by large surface/volume ratios and mechanical amplification of movement, can be distributed in large numbers over large areas providing unprecedented sensitivity, redundancy, and stability (robustness). Local neural transduction allows for space- and power-efficient signal processing. Moreover by varying the hair structure and transduction mechanism, the basic hair form can be used for a wide diversity of functions. In this paper, by exploiting a novel wafer-level, bubble-free liquid encapsulation technology, we make arrays of micro-hydraulic cells capable of electrostatic actuation and hydraulic amplification, which enables high force/high deflection actuation and extremely sensitive detection (sensing) at low power. By attachment of cilia (hair) to the micro-hydraulic cell, air flow sensors with excellent sensitivity (< few cm/s) and dynamic range (> 10 m/s) have been built. A second-generation design has significantly reduced the sensor response time while maintaining sensitivity of about 2 cm/s and dynamic range of more than 15 m/s. These sensors can be used for dynamic flight control of flying robots or for situational awareness in surveillance applications. The core biomimetic technologies developed are applicable to a broad range of sensors and actuators.

Sadeghi, Mahdi M.; Peterson, Rebecca L.; Najafi, Khalil



Gas sensor  

SciTech Connect

An electro-chemical cell for quantitatively detecting an acidic or an alkaline gas, e.g. carbon dioxide, includes a sensing electrode which is connected to a top cap by a contact strip and is accessible to the gas to be tested through a hole. The electrode comprises an electro-chemical couple whose potential is pH-dependent (e.g. silver/silver oxide for carbon dioxide) the active material being supported by a nickel gauze to give good current collection. A counter electrode without significant gas access is immersed in an electrolyte whose pH is such that it will change following adsorption of the gas being tested for. A wicking separator ensures an electrolytic path between the two electrodes. The components are contained within a metal can, the top cap being held by folding over the rim. An insulating grommet is fitted between the two electrodes. When using silver/silver oxide for the sensing electrode, the counter electrode may be of the same material and the electrolyte may be potassium carbonate. The current flowing between the electrodes is a measure of the concentration of gas being detected. A reference electrode may also be included.

Tantram, A.D.S.; Finbow, J.R.; Hobbs, B.S.



Impurity intrusion in radio-frequency micro-plasma jets operated in ambient air  

E-print Network

Space and time resolved concentrations of helium metastable atoms in an atmospheric pressure radio-frequency micro-plasma jet were measured using tunable diode laser absorption spectroscopy. Spatial profiles as well as lifetime measurements show significant influences of air entering the discharge from the front nozzle and of impurities originating from the gas supply system. Quenching of metastables was used to deduce quantitative concentrations of intruding impurities. The impurity profile along the jet axis was determined from optical emission spectroscopy as well as their dependance on the feed gas flow through the jet.

Niermann, B; Böke, M; Winter, J



Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning.  


The mastoid air cell system has traditionally been considered to have a passive role in gas exchange and pressure regulation of the middle ear possibly with some acoustic function. However, more evidence has focused on the mucosa of the mastoid, which may play a more active role in regulation of middle ear pressure. In this study we have applied micro-CT scanning on a series of three human temporal bones. This approach greatly enhances the resolution (40-60 ?m), so that we have discovered anatomical details, which has not been reported earlier. Thus, qualitative analysis using volume rendering has demonstrated notable micro-channels connecting the surface of the compact bone directly to the mastoid air cells as well as forming a network of connections between the air cells. Quantitative analysis on 2D slices was employed to determine the average diameter of these micro-channels (158 ?m; range = 40-440 ?m) as well as their density at a localized area (average = 75 cm(-2); range = 64-97 cm(-2)). These channels are hypothesized to contain a separate vascular supply for the mastoid mucosa. However, future studies of the histological structure of the micro-channels are warranted to confirm the hyp