1,066 research outputs found
Redescription of the Neotropical species Trichodischia soror Bigot, 1885 (Diptera: Tachinidae), with a new generic synonymy
Trichodischia Bigot, 1885 is a Neotropical genus with a confusing taxonomic history. This was initially composed of two species: T. caerulea Bigot, 1885 and T. soror Bigot, 1885. Later, the genus Trichoraea Cortés, 1974 was erected for T. caerulea. When reviewing the taxonomic history of both species, we discovered that both genera have been considered synonymous based on erroneous information and without a formal synonymy being proposed. Herein, we redescribed T. soror, provide images of adults and describe the male terminalia for the first time. In addition, by examining the type material, we propose Trichoraea as a junior synonym of Trichodischia, syn. nov., confirm T. caerulea comb. rest. and T. soror as valid species and provide some comments about the taxonomy and host record of the genus
Development of a low temperature co-fired ceramic fuel processor for the micro-scale solid oxide fuel cell system
The miniaturized solid oxide fuel cells (µ-SOFCs) has become an intensively studied device for portable power generation technology due to its wide choice of hydrocarbon fuels, its high energy density and its great operation efficiency. It is being considered as a battery replacement [1]. The µ-SOFC system, which aims to provide electrical energy (≤ 10 W) at an operating temperature of ca. 550°C, consists of a fuel cell unit for the electrochemical conversion [2-3]; a fuel processing unit for the thermal start-up, fuel reforming and total oxidation of exhausts [4-5]; a system packaging that insulates the fuel cell unit from the operating temperature to the ambient as well as provides fluidic and electronic connections [6-8]; and an electronics module for regulating the power output. As a core module of the entire µ-SOFC system, various fuel processing units have been proposed and developed. Most of those modules have been based on microelectromechanical systems (MEMS), which however shows several critical limitations with regard to electrical and fluidic connections and system integration [9-10]. Here we propose a ceramic based meso-scale gas processer combined with thick film and low-temperature co-fired ceramic technology (LTCC). With an overall size of 12 × 30 × 10 mm3, the ceramic processor, made of Heraeus HeroLock 2000 LTCC materials, mainly functions as a meso-scale hotplate that has a cantilever shape to effectively decouple the heat at the hot zone produced by the start-up heater and/or exothermic fuel processing reactions from the cold zone, in which the temperature is near ambient and thus compatible with normal electrical and fluidic connections (Figure 1). Embedded cavities were integrated into the processor during the fabrication process by using a progressive lamination technique. A thick-film crack-free catalyst paste, containing rhodium-doped ceria-zirconia nanoparticles, was dispensed into the reaction chambers as packed catalytic beds for the processing reactions. An integrated thick-film platinum (Heraeus CL11-6109) heater provides the start-up energy for the exothermic reforming reaction of butane or methane as well as total oxidation reactions. Such a meso-scale monolithic ceramic reactor can carry out the gas processing in a thermally self-sustaining manner, rendering itself to be a functional packaging of the entire µ-SOFC system in the future. In this work, the fabrication process of the gas processor will be discussed in detail, and the results of the fuel processing reactions such as reforming, total oxidation and thermal start-up will be presented as well. References: [1] Bieberle-Hütter, A., Beckel, D., et al. Journal of Power Sources, 177(1), 123–130, (2008) [2] Rey-Mermet, S. and Muralt, P. Solid State Ionics, 179(27–32), 1497-1500, (2008) [3] Evans, A., Bieberle-Hütter, A., et al. Monatshefte für Chemie - Chemical Monthly, 140(9), 975–983, (2009) [4] Shao, Z., Haile, S. M., et al. Nature, 435(7043), 795–798, (2005) [5] Santis-Alvarez, A. J., Nabavi, M., et al. Energy & Environmental Science, 4(8), 3041, (2011) [6] Jiang, B., Maeder, T., Muralt, P. Proceedings, Power MEMS 2010, Leuven (BE), 2010 [7] Jiang, B., Muralt, P., et al. Sensors and Actuators B: Chemical, 175, 218–224, (2012) [8] Maeder, T., Jiang, B., et al. Proceedings, 7th International Conference on Ceramic Interconnect and Ceramic Microsystems Technologies (CICMT), San Diego (USA), 2011 [9] Hotz, N., Osterwalder, N., et al. Chemical Engineering Science, 63(21), 5193–5201, (2008) [10] Vaccaro, S., Malangone, L., Ciambelli, P. Industrial & Engineering Chemistry Research, 49(21), 10924–10933, (2010
A low-temperature co-fired ceramic micro-reactor system for high-efficiency on-site hydrogen production
A ceramic-based, meso-scale fuel processor for on-board production of syngas fuel was demonstrated for applications in micro-scale solid-oxide fuel cells (mu-SOFCs). The processor had a total dimension of 12 mm x 40 mm x 2 mm, the gas reforming micro reactor occupying the hot end of a cantilever had outer dimensions of 12 x 18 mm. The device was fabricated through a novel progressive lamination process in low-temperature co-fired ceramic (LTCC) technology. Both, heating function and desired fluidic structures were integrated monolithically into the processor. Using catalytic partial oxidation of a hydrocarbon fuel (propane) as a reaction model, a thermally self-sustaining hydrogen production was achieved. The output flow is sufficiently high to drive an optimized single membrane mu SOFC cell of about the same footprint as the micro reactor. Microsystem design, fabrication, catalyst integration as well as the chemical characterization are discussed in detail. (C) 2014 Elsevier B.V. All rights reserved
A novel fuel processing platform for micro-scale solid oxide fuel cells
Recently, the development of micro-scale solid oxide fuel cells (µ-SOFCs) has become a promising research topic in the area of portable energy production. A µ-SOFC system, which can provide 1 to 2 W electrical power under an operating temperature of 550°C 1-2, mainly consists of a fuel processor, an electrochemical power generator, and a post combustor. The role of the fuel processor is to generate a hydrogen-rich product stream that is fed to the power generation module. In previous works, various micromachined fuel reformers based on microelectromechanical system (MEMS) technology have been demonstrated to achieve high-yield syngas generation from liquid hydrocarbons 3-5. However, MEMS-based micro-reformers require time-consuming and expensive fabrication processes, and face critical issues concerning electrical and fluidic interconnects. Conversely, 'traditional' thick film-technology is a simple and low-cost fabrication route, allows integration of a wide palette of materials by a convenient printing technique, and has a proven track record in harsh environments 6. Here, we propose to apply thick-film technology to a fuel-processing platform for the development of µ-SOFC systems. The thick-film based fuel processor consists of a self-sensing heating element, a fluidic carrier comprising a catalyst chamber, and a ceramic substrate. The heating element consists of two independent thick-film platinum conductor meanders, which are screen printed at the bottom of the fluidic carrier, and provide relatively homogeneous heating of the catalytic reforming zone up to 700°C 7. Due to their temperature dependence of resistance, the thick-film Pt heaters double as temperature sensors and thus allow integrated temperature control of the fuel processing. The fluidic carrier was made of two pieces of (12 mm × 75 mm × 0.7 mm) borosilicate glass (Schott AF32), bonded by a screen-printed glass frit seal (Ferro IP760c), which also patterns the fluidic channels in the carrier. Multiple glass paste prints allow for building up the channel height (i.e. distance between glass plates) up to ca. 150 µm. The catalyst is placed into an open chamber on the top plate of the fluidic carrier by dispensing, and is capped by a piece of AF32 glass (12 mm x 13.8 mm) using the same glass frit bonding technique. The elongated shape of the fluidic carrier and low thermal conductivity of the glass efficiently decouples the heat generated in the "hot" catalyst area from the other "cold" end of the carrier, allowing conventional low-temperature electrical and fluidic interconnections. With a heating power below 8 W, the platform is able to quickly heat the active zone to 700°C, while maintaining the electrical and fluidic connections below 50°C. The performance of isobutane reforming was evaluated, studying the impact of design parameters such as the catalyst chamber dimension, and geometry of the thick-film Pt resistor. The talk will present and discuss the studied fabrication processes including the glass frit and catalyst paste formulation, screen printing and dispensing processes, and show the performance of the platform with results obtained on thermal characterization and gas reforming. The heat output of exothermic reactions is well observed. Keywords solid oxide fuel cell, fuel processer, hydrogen production Reference [1] S. Rey-Mermet and Paul Muralt, Solid State Ionics, 179 (2008) 1497 -1500 [2] A. Bieberle-Hütter et al., Journal of Power Source, 177 (2008) 123-130 [3] J. D. Holladay et al., Chemical Reviews, 104(2004) 4767-4789 [4] K. Yoshida et al., Journal of Micromechanical and Microengineering, 16 (2006) S191-S197 [5] A. J. Santi-Alvarez et al., Energy & Environmental Science, 4 (2011) 3041-3050 [6] T. Maeder et al., Proceedings of 7th CICMT, San Diego (USA), 2011 [7] B. Jiang et al., Sensors and Actuators B, 2012, under revie
A nanoparticle bed micro-reactor with high syngas yield for moderate temperature micro-scale SOFC power plants
This work introduces and investigates the a novel compact catalytic nanoparticle bed micro-fabricated reactor suitable for utilization in small-scale intermediate-temperature micro-SOFC systems. It is shown that the presented micro-reactor is able to produce syngas (CO + H2) efficiently from n-butane and propane at temperatures between 550 – 620 °C by means of catalytic partial oxidation (CPOX) using Rh-doped nanoparticles embedded in a foam-like porous ceramic bed as a catalyst. The novel micro-fabricated reactor system is experimentally tested using a carrier specially designed for heating the reactor as well as feeding the fuel and receiving the reaction product gases. Optimization of the syngas production is performed by varying fuel dilutions and reactor temperatures. The performance of the micro-reactor was investigated in two modes: (1) Continuous heating mode, in which two built-in heaters underneath the carrier are kept on throughout the reforming reaction. This simulates the operating state of a micro-SOFC system where the post-combustor provides heat to the micro-reformer continuously. (2) Thermally self-sustained mode, in which the heaters are turned off after the CPOX has been ignited. An estimation of the heat losses of both testing modes is also given. The present micro-reactor is able to achieve syngas yield as high as 60 % for n-butane and 50 % for propane in the continuous heating mode, which is a substantial improvement to state-of-the-art micro-reactors
A low-temperature co-fired ceramic micro-reactor system for high-efficiency on-site hydrogen production
CD69 is a TGF-β/1α,25-dihydroxyvitamin D3 target gene in monocytes
CD69 is a transmembrane lectin that can be expressed on most hematopoietic cells. In monocytes, it has been functionally linked to the 5-lipoxygenase pathway in which the leukotrienes, a class of highly potent inflammatory mediators, are produced. However, regarding CD69 gene expression and its regulatory mechanisms in monocytes, only scarce data are available. Here, we report that CD69 mRNA expression, analogous to that of 5-lipoxygenase, is induced by the physiologic stimuli transforming growth factor-β (TGF-β) and 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) in monocytic cells. Comparison with T- and B-cell lines showed that the effect was specific for monocytes. CD69 expression levels were increased in a concentration-dependent manner, and kinetic analysis revealed a rapid onset of mRNA expression, indicating that CD69 is a primary TGF-β/1α,25(OH)2D3 target gene. PCR analysis of different regions of the CD69 mRNA revealed that de novo transcription was initiated and proximal and distal parts were induced concomitantly. In common with 5-lipoxygenase, no activation of 0.7 kb or ~2.3 kb promoter fragments by TGF-β and 1α,25(OH)2D3 could be observed in transient reporter assays for CD69. Analysis of mRNA stability using a transcription inhibitor and a 3′UTR reporter construct showed that TGF-β and 1α,25(OH)2D3 do not influence CD69 mRNA stability. Functional knockdown of Smad3 clearly demonstrated that upregulation of CD69 mRNA, in contrast to 5-LO, depends on Smad3. Comparative studies with different inhibitors for mitogen activated protein kinases (MAPKs) revealed that MAPK signalling is involved in CD69 gene regulation, whereas 5-lipoxygenase gene expression was only partly affected. Mechanistically, we found evidence that CD69 gene upregulation depends on TAK1-mediated p38 activation. In summary, our data indicate that CD69 gene expression, conforming with 5-lipoxygenase, is regulated monocyte-specifically by the physiologic stimuli TGF-β and 1α,25(OH)2D3 on mRNA level, although different mechanisms account for the upregulation of each gene
Syngas generation from n-butane with an integrated MEMS assembly for gas processing in micro-solid oxide fuel cell systems
An integrated system of a microreformer and a carrier allowing for syngas generation from liquefied petroleum gas (LPG) for micro-SOFC application is discussed. The microreformer with an overall size of 12.7 mm × 12.7 mm × 1.9 mm is fabricated with micro-electro-mechanical system (MEMS) technologies. As a catalyst, a special foam-like material made from ceria-zirconia nanoparticles doped with rhodium is used to fill the reformer cavity of 58.5 mm3. The microreformer is fixed onto a microfabricated structure with built-in fluidic channels and integrated heaters, the so-called functional carrier. It allows for thermal decoupling of the cold inlet gas and the hot fuel processing zone. Two methods for heating the microreformer are compared in this study: a) heating in an external furnace and b) heating with the two built-in heaters on the functional carrier. With both methods, high butane conversion rates of 74%–85% are obtained at around 550 °C. In addition, high hydrogen and carbon monoxide yields and selectivities are achieved. The results confirm those from classical lab reformers built without MEMS technology (N. Hotz et al., Chem. Eng. Sci., 2008, 63, 5193; N. Hotz et al., Appl. Catal., B, 2007, 73, 336). The material combinations and processing techniques enable syngas production with the present MEMS based microreformer with high performance for temperatures up to 700°C. The functional carrier is the basis for a new platform, which can integrate the micro-SOFC membranes and the gas processing unit as subsystem of an entire micro-SOFC system
A nanoparticle bed micro-reactor with high syngas yield for moderate temperature micro-scale SOFC power plants
Violation of the fluctuation-dissipation theorem in glassy systems: basic notions and the numerical evidence
This review reports on the research done during the past years on violations
of the fluctuation-dissipation theorem (FDT) in glassy systems. It is focused
on the existence of a quasi-fluctuation-dissipation theorem (QFDT) in glassy
systems and the currently supporting knowledge gained from numerical simulation
studies. It covers a broad range of non-stationary aging and stationary driven
systems such as structural-glasses, spin-glasses, coarsening systems,
ferromagnetic models at criticality, trap models, models with entropy barriers,
kinetically constrained models, sheared systems and granular media. The review
is divided into four main parts: 1) An introductory section explaining basic
notions related to the existence of the FDT in equilibrium and its possible
extension to the glassy regime (QFDT), 2) A description of the basic analytical
tools and results derived in the framework of some exactly solvable models, 3)
A detailed report of the current evidence in favour of the QFDT and 4) A brief
digression on the experimental evidence in its favour. This review is intended
for inexpert readers who want to learn about the basic notions and concepts
related to the existence of the QFDT as well as for the more expert readers who
may be interested in more specific results.Comment: 120 pages, 37 figures. Topical review paper . Several typos and
misprints corrected, new references included and others updated. to be
published in J. Phys. A (Math. Gen.
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