Analytical study of catalytic reactors for hydrazine decomposition. One and two dimensional steady-state programs, computer programs manual

Programs manual for one-dimensional and two- dimensional steady state models of catalyzed hydrazine decomposition reaction chamber

Internal photoemission from quantum well heterojunction superlattices by phononless free-carrier absorption

The possibility of phononless free-carrier absorption in quantum well heterojunction superlattices was investigated. Order of magnitude calculation showed that the absorption coefficient was significantly enhanced over the phonon-assisted process. Important aspects of the enhancement in the design of infrared photodetectors are discussed

Efficacy of laser preionization with a semiconductor source and propene addition

It is established that propene is an effective additive instabilising uv preionised CO2 TEA laser discharges: its effect being particularly pronounced with semiconductor-edge preionised lasers where the preionisation levels are shown to be low

Detection of early osteogenic commitment in primary cells using Raman spectroscopy

Major challenges in the development of novel implant surfaces for artificial joints include osteoblast heterogeneity and the lack of a simple and sensitive in vitro assay to measure early osteogenic responses. Raman spectroscopy is a label-free, non-invasive and non-destructive vibrational fingerprinting optical technique that is increasingly being applied to detect biochemical changes in cells. In this study Raman spectroscopy has been used to obtain bone cell-specific spectral signatures and to identify any changes therein during osteoblast commitment and differentiation of primary cells in culture. Murine calvarial osteoblasts (COBs) were extracted and cultured and studied by Raman spectroscopy over a 14 day culture period. Distinct osteogenic Raman spectra were identified after 3 days of culture with strong bands detected for mineral: phosphate ν3 (1030 cm−1) and B-type carbonate (1072 cm−1), DNA (782 cm−1) and collagen matrix (CH2 deformation at 1450 cm−1) and weaker phosphate bands (948 and 970 cm−1). Early changes were detected by Raman spectroscopy compared to a standard enzymatic alkaline phosphatase (ALP) assay and gene expression analyses over this period. Proliferation of COBs was confirmed by fluorescence intensity measurements using the Picogreen dsDNA reagent. Changes in ALP levels were evident only after 14 days of culture and mRNA expression levels for ALP, Col1a1 and Sclerostin remained constant during the culture period. Sirius red staining for collagen deposition also revealed little change until day 14. In contrast Raman spectroscopy revealed the presence of amorphous calcium phosphate (945–952 cm−1) and carbonated apatite (957–962 cm−1) after only 3 days in culture and octacalcium phosphate (970 cm−1) considered a transient mineral phase, was detected after 5 days of COBs culture. PCA analysis confirmed clear separation between time-points. This study highlights the potential of Raman spectroscopy to be utilised for the early and specific detection of proliferation and differentiation changes in primary cultures of bone cells

Strong absorption and selective thermal emission from a mid-infrared metamaterial

We demonstrate thin-film metamaterials with resonances in the mid-infrared wavelength range. Our structures are numerically modeled and experimentally characterized by reflection and angularly-resolved thermal emission spectroscopy. We demonstrate strong and controllable absorption resonances across the mid-infrared wavelength range. In addition, the polarized thermal emission from these samples is shown to be highly selective and largely independent of emission angles from normal to 45 degrees. Experimental results are compared to numerical models with excellent agreement. Such structures hold promise for large-area, low-cost metamaterial coatings for control of gray- or black-body thermal signatures, as well as for possible mid-IR sensing applications.Comment: The following article has been submitted to Appl. Phys. Lett. After it is published, it will be found at http://apl.aip.org/. 14 pages including 4 figure page

Temperature perturbation model of the opto-galvanic effect in CO2-laser discharges

A detailed discharge model of the opto-galvanic effect in molecular laser gas mixtures is developed based on the temperature perturbation or discharge cooling mechanism of Smith and Brooks (1979). Excellent agreement between the model and experimental results in CO2 laser gas mixtures is obtained. The model should be applicable to other molecular systems where the OGE is being used for laser stabilisation and as a spectroscopic tool

Electronic transport in Si:P delta-doped wires

Despite the importance of Si:P delta-doped wires for modern nanoelectronics, there are currently no computational models of electron transport in these devices. In this paper we present a nonequilibrium Green's function model for electronic transport in a delta-doped wire, which is described by a tight-binding Hamiltonian matrix within a single-band effective-mass approximation. We use this transport model to calculate the current-voltage characteristics of a number of delta-doped wires, achieving good agreement with experiment. To motivate our transport model we have performed density-functional calculations for a variety of delta-doped wires, each with different donor configurations. These calculations also allow us to accurately define the electronic extent of a delta-doped wire, which we find to be at least 4.6 nm.Comment: 13 pages, 11 figure

Aerosol seeding systems for the NSWC wind tunnels

Four types of laskin nozzles which are used to generate the primary aerosol mist are illustrated. This mist may be used directly as laser doppler velocimeters (LDV) particles. However, in general, a wide range of particle size exists at this stage and requires the use of some type of mono-dispersion refinement technique. These nozzles rely on the shearing action of high speed air near a column of seeding liquid. Typically, olive oil or dioctyl phthalate (DOP) is used, but within the past year solid polystyrene particles in an alcohol suspension have been used with great success. Air, at a typical pressure of five psig, is supplied to the top of the nozzle which is merely a hollow tube. This air issues radially from one or more small jets located near the collar close to the bottom of the tube. When the collar is submerged in the seeding liquid, the hollow columns located in the collar become filled with liquid. The air from the jet shears the liquid into the fine mist

Cereal Leaf Beetle (Coleoptera: Chrysomelidae) Influence of Seeding Rate of Oats on Populations

In field and greenhouse studies, more cereal leaf beetle [Oulema melanopus (Lin- naeus)] eggs and larvae were found per unit area on spring oats, Avena sativa L., planted either at intermediate (54 kg/ha) or high (136 kg/ha) seeding rates, than when planted at a lower seeding rate (14 kg/ha). However, there were fewer eggs and larvae per stem in plantings of the high or intermediate rates than in those of the lower rate. Oats should not be planted at less than the recommended rates in beetle-infested areas

Method of forming thin window drifted silicon charged particle detector Patent

Method of forming thin window drifted silicon charged particle detecto