Experimental and theoretical studies of the reaction of atomic oxygen with silane

Article on experimental and theoretical studies of the reaction of atomic oxygen with silane

A Sensitive Assay for Virus Discovery in Respiratory Clinical Samples

In 5–40% of respiratory infections in children, the diagnostics remain negative, suggesting that the patients might be infected with a yet unknown pathogen. Virus discovery cDNA-AFLP (VIDISCA) is a virus discovery method based on recognition of restriction enzyme cleavage sites, ligation of adaptors and subsequent amplification by PCR. However, direct discovery of unknown pathogens in nasopharyngeal swabs is difficult due to the high concentration of ribosomal RNA (rRNA) that acts as competitor. In the current study we optimized VIDISCA by adjusting the reverse transcription enzymes and decreasing rRNA amplification in the reverse transcription, using hexamer oligonucleotides that do not anneal to rRNA. Residual cDNA synthesis on rRNA templates was further reduced with oligonucleotides that anneal to rRNA but can not be extended due to 3′-dideoxy-C6-modification. With these modifications >90% reduction of rRNA amplification was established. Further improvement of the VIDISCA sensitivity was obtained by high throughput sequencing (VIDISCA-454). Eighteen nasopharyngeal swabs were analysed, all containing known respiratory viruses. We could identify the proper virus in the majority of samples tested (11/18). The median load in the VIDISCA-454 positive samples was 7.2 E5 viral genome copies/ml (ranging from 1.4 E3–7.7 E6). Our results show that optimization of VIDISCA and subsequent high-throughput-sequencing enhances sensitivity drastically and provides the opportunity to perform virus discovery directly in patient material

Syngas Production, Storage, Compression and Use in Gas Turbines

This chapter analyses syngas production through pyrolysis and gasification, its compression and its use in gas turbines. Syngas compression can be performed during or after thermal treatment processes. Important points are discussed related to syngas ignition, syngas explosion limit at high temperatures and high pressures and syngas combustion kinetics. Kinetic aspects influence ignition and final emissions which are obtained at the completion of the combustion process. The chapter is organized into four subsections, dealing with (1) innovative syngas production plants, (2) syngas compressors and compression process, (3) syngas ignition in both heterogeneous and homogeneous systems and (4) syngas combustion kinetics and experimental methods. Particular attention is given to ignition regions that affect the kinetics, namely systems that operate at temperatures higher than 1000 K can have strong ignition, whereas those operating at lower temperatures have weak ignition. Keywords: Pyrogas Pyrolysis Ignition Syngas Compression GasificationacceptedVersio

A Combined Pressure Reaction Cell – UHV Chamber With Sample Transfer System

We have designed a high-pressurereaction cell and sample transfer system as an addition to an existing ultrahigh vacuum chamber. The system enables us to study catalyticreactions on both single crystals and polycrystalline foils over a large range of pressures from 10−4 Torr role= presentation style= box-sizing: border-box; display: inline; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; color: rgb(51, 51, 51); font-family: Arial, sans-serif; position: relative; \u3e10−4 Torr10−4 Torr to 1 atm. The key advantage of the setup is that the thermocouple is in direct contact with the sample, providing exact measurement of the sample temperature, while allowing transfer between two different manipulators. We demonstrate the utility of the experimental setup by monitoring oscillations in the rate of carbon monoxide oxidation over a platinum catalyst

Ellipsomicroscopy For Surface Imaging - A Novel Tool to Investigate Surface Dynamics

This article focuses on the technical issues of imaging of dynamic adsorbatepattern formation on platinumsurfaces using laser light to illuminate the area of interest. In particular, ellipsomicroscopy for surface imaging (EMSI) is a powerful tool to follow spatio-temporal patterns of adsorbate layers on catalyst surfaces at arbitrary pressures. This novel method is uniquely sensitive to submonolayer coverages of adsorbates. It expands the range of observable pressure conditions by many orders of magnitude, thus bridging the pressure gap in imaging surface reactions. EMSI is a versatile technique that opens new avenues of potential applications to resolve dynamic surface processes, such as adsorbatediffusion or coating formation

Supersonic combustion processes in a premixed 3D non-uniform-compression scramjet engine

A numerical study was undertaken using the commercial Computational Fluid Dynamics code CFD++ to analyse the ignition behaviour of a three-dimensional non-uniform compression Scramjet. The study concerned itself with understanding how 3D flow features / combustion coupling enables the combustion flame to propagate from higher to lower compression regions within the combustor. A premixed H2/Air mixture with an equivalence ratio of 1 was used to decouple the influence of fuel injection on combustion characteristics. The free stream properties corresponded to a flow enthalpy, total temperature and total pressure of 4.5 MJ/kg (Mach 10), 4676 K and 8 MPa respectively. Three sources of flame propagation into the low compression region were identified: 3D Flow Structures which provide ignition sources within the boundary layer, Radical Transport within a 3D shockinduced boundary layer separation and Thermal Compression from combustion within the high compression region. All three sources had a significant influence in propagating the flame into the low compression region

Supersonic combustion processes in a premixed 3D non-uniform-compression scramjet engine

A numerical study was undertaken using the commercial Computational Fluid Dynamics code CFD++ to analyse the ignition behaviour of a three-dimensional non-uniform compression Scramjet. The study concerned itself with understanding how 3D flow features / combustion coupling enables the combustion flame to propagate from higher to lower compression regions within the combustor. A premixed H2/Air mixture with an equivalence ratio of 1 was used to decouple the influence of fuel injection on combustion characteristics. The free stream properties corresponded to a flow enthalpy, total temperature and total pressure of 4.5 MJ/kg (Mach 10), 4676 K and 8 MPa respectively. Three sources of flame propagation into the low compression region were identified: 3D Flow Structures which provide ignition sources within the boundary layer, Radical Transport within a 3D shockinduced boundary layer separation and Thermal Compression from combustion within the high compression region. All three sources had a significant influence in propagating the flame into the low compression region

Deuterium adsorption on water preadsorbed uranium-niobium alloys

We have investigated the adsorptiodreaction of deuterium on water pre-adsorbed oxidized uranium-niobium alloys at pressures near 1 Torr. Deuterium exposures were conducted at pressures from 1 to 4 Torr at surface temperatures between 300 and 600 K using a fixed dosing time of 30 seconds. Water is preadsorbed at room temperature at a pressure of {approx} 1 Torr for 30 seconds. Subsequent to gaseous exposure the surface temperature of the alloy was increased in a controlled manner and deuterium desorption was monitored using mass spectroscopy. Deuterium is observed to adsorb both at the surface and in the bulk of the uranium-niobium alloys. Water preadsorption prevents deuterium adsorption on all surfaces. The water forms a surface passivation layer at low temperatures that prevents deuterium uptake into the bulk and surface of the sample. As the adsorption temperature of the deuterium increases the amount of deuterium that adsorbs also increases