Integrated Micro Fuel Processor And Flow Delivery Infrastructure

Apparatus for transporting a fluid, atomizers, reactors, integrated fuel processing apparatus, combinations thereof, methods of atomizing reactants, methods of moving fluids, methods of reverse-flow in a reactor, and combinations thereof, are provided. One exemplary apparatus for transporting a fluid, among others, includes: a channel for receiving a fluid; a sensor for determining an internal condition of the fluid in the channel; and a channel actuator in communication with the sensor for changing a cross-sectional area of the channel based on the internal condition, wherein the change in cross-sectional area controls a parameter selected from a pressure and a fluid flow.Georgia Tech Research Corporatio

Single-step growth of graphene and graphene-based nanostructures by plasma-enhanced chemical vapour deposition

The realization of many promising technological applications of graphene and graphene-based nanostructures depends on the availability of reliable, scalable, high-yield and low-cost synthesis methods. Plasma enhanced chemical vapor deposition (PECVD) has been a versatile technique for synthesizing many carbon-based materials, because PECVD provides a rich chemical environment, including a mixture of radicals, molecules and ions from hydrocarbon precursors, which enables graphene growth on a variety of material surfaces at lower temperatures and faster growth than typical thermal chemical vapor deposition. Here we review recent advances in the PECVD techniques for synthesis of various graphene and graphene-based nanostructures, including horizontal growth of monolayer and multilayer graphene sheets, vertical growth of graphene nanostructures such as graphene nanostripes with large aspect ratios, direct and selective deposition of monolayer and multi-layer graphene on nanostructured substrates, and growth of multi-wall carbon nanotubes. By properly controlling the gas environment of the plasma, it is found that no active heating is necessary for the PECVD growth processes, and that high-yield growth can take place in a single step on a variety of surfaces, including metallic, semiconducting and insulating materials. Phenomenological understanding of the growth mechanisms are described. Finally, challenges and promising outlook for further development in the PECVD techniques for graphene-based applications are discussed

FIB-SEM Three-Dimensional Tomography for Characterization of Carbon-Based Materials

A review on the recent advances of the three-dimensional (3D) characterization of carbon-based materials was conducted by focused ion beam-scanning electron microscope (FIB-SEM) tomography. Current studies and further potential applications of the FIB-SEM 3D tomography technique for carbon-based materials were discussed. The goal of this paper is to highlight the advances of FIB-SEM 3D reconstruction to reveal the high and accurate resolution of internal structures of carbon-based materials and provide suggestions for the adoption and improvement of the FIB-SEM tomography system for a broad carbon-based research to achieve the best examination performances and enhance the development of innovative carbon-based materials

NASA SBIR abstracts of 1990 phase 1 projects

The research objectives of the 280 projects placed under contract in the National Aeronautics and Space Administration (NASA) 1990 Small Business Innovation Research (SBIR) Phase 1 program are described. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses in response to NASA's 1990 SBIR Phase 1 Program Solicitation. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 280, in order of its appearance in the body of the report. The document also includes Appendixes to provide additional information about the SBIR program and permit cross-reference in the 1990 Phase 1 projects by company name, location by state, principal investigator, NASA field center responsible for management of each project, and NASA contract number

Karbiidist sünteesitud poorsete mittegrafiitsete süsinike struktuuride uurimine ning nende mõju H2 liikuvusele

Väitekirja elektrooniline versioon ei sisalda publikatsiooneAktiveeritud süsiniku, mida kasutatakse toidumürgistuse raviks, leiab apteegiriiulitelt. See on peamiselt süsinikust koosnev materjal, mis sisaldab palju imeväikeseid augukesi ja avausi ehk poore. Need poorid moodustuvad kaardus ja defektsete grafeenist koosnevate lehekeste (ehk ühekihilise grafiidi) kihtide vahele. Aktiveeritud söega laias laastus sarnaste omadustega poorseid materjale kasutatakse palju ka muudes rakendustes. Üks põnevamaid neist on seotud energia salvestamisega. Nimelt on poorne süsinik keemiliselt üsna stabiilne, samas odav materjal, mis juhib hästi elektrit. Tänu nendele omadustele sobib poorne süsinik hästi energiasalvestus ja -muundamisseadmete nagu patareide, polümeerelektrolüütmembraankütuseelementide ja superkondensaatorite elektroodimaterjaliks. Tartu Ülikooli Füüsikalise keemia õppetoolis on sünteesitud ja elektroodimaterjalidena katsetatud tohutul hulgal eri sorte poorseid süsinikke. Üks süsinikmaterjalide liike, mida on süstemaatiliselt uuritud, on karbiididest sünteesitud süsinikmaterjalid. Karbiidid on ühendid, mis koosnevad tüüpiliselt kahest elemendist, millest üks on süsinik. Üks viise, kuidas karbiidist saab puhast süsinikku sünteesida, on panna valitud karbiid kõrgel temperatuuril (ehk sünteesitemperatuuril) reageerima klooriga. Muud reaktsioonisaadused uhutakse gaasivoos minema, reaktsiooninõusse jääb alles väga spetsiifiliste omadustega süsinikmaterjal. Mõnes mõttes võib sellest süsinikamaterjalist mõelda, kui algse karbiidi “skeletist”. Näiteks superkondensaatoreid tootev Eesti ettevõte Skeleton kasutab oma toodetes osaliselt just karbiidist sünteesitud süsinikmaterjale. Selles doktoritöös uuriti, kuidas muutub karbiidist sünteesitud süsiniku struktuur, kui sünteesitemperatuur on erinev või kuidas mõjutab struktuuri see, milline lähtekarbiid valiti. Selgus, et kui valitakse kõrgem sünteesitemperatuur, siis süsiniku sisse moodustuvad laiemad, vähem defektsed grafeenikihid. Osade lähtekarbiidide (Mo2C, VC) puhul kasvas sünteesitemperatuuri suurenedes ka graafeenikihtide virna kõrgus, kuid enamikes karbiisist sünteesitud süsinikes, mida uuriti, grafeenikihtide hulk sünteesitemperatuurist ei sõltunud. Molübdeenkarbiidist sünteesitud süsinike poorset struktuuri, mis muutub sünteesitemperatuuriga väga palju, vaadeldi lähemalt väikesenurgahajumise meetoditega. Selgus, et sünteesitemperatuuri kasvades keskmine poori läbimõõt suurenes ja moodustusid järjest siledamad ja rohkem pilu-kujulised poorid. Veel uuriti, kuidas karbiidist sünteesitud süsiniku poorne struktuur mõjutab seda, kui hästi lõksustab süsinikmaterjal vesiniku molekule. Selgus, et väike kogus vesinikku ränikarbiidist sünteesitud süsiniku poorides, oli tugevalt kinnipeetud, sisuliselt liikumatu, ka suhteliselt kõrgel temperatuuril 120 K (vesinik veeldub 20 K juures). Väike kogus vesinikku titaankarbiidist sünteesitud süsiniku poorides käitus sarnaselt vedel vesinikuga temperatuuril kuni 70 K. Seevastu väike kogus vesinikku, mis oli adsorbeerunud molübdeenkarbiidist sünteesitud süsiniku poorides ei olnud kuigi tugevalt kinnipeetud ja selle difusioon oli üsna kiire ka madalatel temperatuuridel. Selgus, et vesiniku lõksustamisel on oluline alla 1 nm läbimõõduga pooride hulk, mis on ränikarbiidist sünteesitud süsinikmaterjalis suurim. Veel on oluline asjaolu ka poori kuju, sest kuigi 1 nm pooride hulk oli nii räni kui ka titaankarbiidist sünteesitud süsinikes sarnane, oli ränikarbiidist sünteesitud süsinikus, mille keskmine poori kuju on sfääriline, H2 tugevamalt lõksustunud.Activated carbon can be found in the pharmacy and is used to cure food poisoning. It consists mostly of carbon and contains numerous minute holes and tunnels, which are called pores. There pores are formed in between the curved graphene (i.e. one-layered graphite) layers, which contain many defects. Carbon materials with similar properties to activated carbons have many different applications. One of these lies in the field of energy (or hydrogen) storage devices. Namely, since porous carbons are very stable, yet cheap materials, which conduct electricity, these materials are widely used as electrode materials in energy storage/conversion devices such as batteries, polymer electrolyte fuel cells and supercapacitors. In the chair of Physical Chemistry of the University of Tartu, numerous different porous carbon materials have been synthesized and used as electrode materials. One of the most widely studied types of porous carbons has been carbide-derived carbons (CDCs). Carbides are chemical compounds, that typically consist of two elements, one of which is carbon. In order to synthesize a CDC, the reaction between a precursor carbide and chlorine gas at high temperature (i.e. the synthesis temperature) is typically conducted. As a result of this reaction, only pure carbon material particles are left in the reaction vessel, since other products of the reaction are washed away with excess gas. In a way the synthesized carbon can be seen as the „skeleton“ of the precursor carbide. Actually, the Estonian company Skeleton, that produces supercapacitors, partly uses CDCs in its products. In this PhD thesis, the differences in the microstructure of CDCs, with respect to the synthesis temperature and/or the precursor carbide, was studied. It was seen that higher synthesis temperatures resulted in the formation of wider platelets of graphene, which contained less defects. In the case of some precursor carbides (Mo2C, VC), also the average height of the stack of graphene platelets increased, but for most studied CDC materials the height of the stack remained independent of the synthesis temperature. The porous structure of molybdenum carbide derived carbon is highly dependent on the synthesis temperature and this was studied in detail with small-angle scattering methods. It was seen that as the synthesis temperature of the CDC increased, the pores in the CDC became smoother and the average shape of the pores became more slit-like. In addition, the diffusion of hydrogen in the pores of three different CDC materials was studied with quasi-elastic neutron scattering. It was established, that a small amount of hydrogen is very strongly confined (i.e. practically immobile) in the subnanometer pores of silicon carbide derived carbon up to relatively high temperature of 120 K (hydrogen liquefies at 20 K). However, the mobility of a small amount of H2 in the pores of titanium carbide derived carbon showed similar characteristics to liquid hydrogen up to temperature of 70 K. The third CDC, in which the mobility of H2 was studied was derived from molybdenum carbide. The pores in molybdenum carbide derived carbon were not very effective in confining hydrogen, since the diffusion of hydrogen was seen to be quite quick already in the case of low temperatures and low H2 amounts. It was seen that a large amount of subnanometer pores is paramount for the successful confinement of H2 in a porous carbon material, since the carbon derived from silicon carbide contained the most of subnanometer pores. In addition, the shape of the pore also impacts the success of the confinement of H2. Namely, the amount of subnanometer pores was similar for both silicon and titanium carbide derived carbon materials, but H2 was more strongly confined in silicon carbide derived carbons, in which the average shape of the pore is spherical.https://www.ester.ee/record=b548582

Macroporous Silicon: Technology and Applications

Macroporous silicon (MPS) is a versatile material that since its origin in the early 1990s has seen intense research and has found applications in many fields. MPS is a key technology in photonic crystals research, and optic and photonic applications are its main applications. However, this chapter is devoted to several of the non‐photonic uses of MPS. In particular, new electronic and MEMS devices and applications will be described. Furthermore, in this chapter, the technology of MPS fabrication will be presented