Target Constituents Research Articles

Projecting an Organizational Identity: Lessons from Employment Advertisements

This paper considers employment advertisements as an organizational attempt to advance an image under routine (rather than crisis) conditions. The analyses identify the steps necessary to create a positive image among target constituents. A three-stage process is identified of (a) attracting attention, (b) presenting a positive organizational identity, and (c) validating this identity. The first stage reflects the competition for target persons' attention, an issue not typically raised in analyses of organizational identity. The second and third stages rely on a general set of tactics that engage four psychological mechanisms:

High-performance thin-layer chromatographic determination of six major ginsenosides in Panax ginseng

A densitometric determination of six major ginsenosides in Panax ginseng, separated by high-performance thin-layer chromatography (HPTLC), was optimized. Simple extraction and clean-up methods of the target constituents and the development of standardized conditions of chromatoplates with a quaternary-solvents system allowed an efficient saponins recovery from the plant material and their selective separation. After exposure of the chromatograms to thionyl chloride vapors and further heating, stable reaction products of ginsenosides, which showed absorption maxima at λ=275 nm as well as a fluorescence ( λ excitation=366 nm, λ emission=400 nm), allowed the application of a sensitive and reproducible method for their simultaneous determination. The method was validated by spiking the ginseng extracts with pure standards.

A Model for Pulsed Activation Accounting for Circulation, Extraction, and Makeup

A model has been developed to accurately calculate the nuclide inventories of the target constituents of Inertial Fusion Energy (IFE) reactors such as HYLIFE-II. It can explicitly account for (1) the combined effects of activation during target implosion (by a high-amplitude flux) and while passing through the reactor chamber (by a low-amplitude flux); (2) decay during circulation in the primary coolant loop, after extraction from the coolant loop, and before re-insertion into the reactor chamber as a new target; (3) continuous extraction and feed-in of target material; and (4) replacement of part of the activation products by makeup materials. The solution strategy uses transition factors – the ratio of the amount of created nuclides to the initial amount – for each system component.

Conversion algorithm for ERDA multielement spectra and its application to thin-film problems

A computer program was designed for the conversion of element-resolved energy spectra obtained from elastic recoil detection analysis into composition depth profiles. The algorithm is described in detail. An important feature of the program is that the contribution of the analyzed elements to the stopping power is accounted for self-consistently. Extensions of the algorithm address the problem of the simultaneous analysis of recoil and forward scattering events, respectively, and of distortions in the recoil spectra due to the presence of target constituents with isotopic distributions that cannot be resolved when using standard ionization chambers for recoil detection. Two examples are given to demonstrate how one may benefit from the capabilities of the conversion program in the context of specific thin film problems. The first example addresses compositional changes in Si 3N 4/C bilayers due to N-ion implantation, while the second one is dealing with the problem of impurity accumulation at the hexagonal-to-cubic phase boundary in BN films.

Field Implementation of a Winsor Type I Surfactant/Alcohol Mixture for in Situ Solubilization of a Complex LNAPL as a Single-Phase Microemulsion

A Winsor Type I surfactant/alcohol mixture was used as an in situ flushing agent to solubilize a multicomponent nonaqueous phase liquid (NAPL) as a single-phase microemulsion (SPME) in a hydraulically isolated test cell at Hill Air Force Base (AFB), Utah. The surfactant (polyoxyethylene(10) oleyl ether) and alcohol (1-pentanol) together comprised 5.5 wt % of the flushing solution. The NAPL was extremely complex, containing more than 200 constituents and a ‘pitch' fraction that was not solvent-extractable. The NAPL removal effectiveness of the SPME flood was evaluated using information from soil cores, partitioning tracer tests, and NAPL constituent breakthrough curves (BTCs) measured at three extraction wells. Soil core data indicated that approximately 90−95% of the most prevalent NAPL constituents were removed from the cell by the SPME flood. A comparison of pre- and postflushing partitioning tracer data indicated that about 72% of the measured NAPL volume was removed by the SPME flood. Integration of NAPL constituent BTCs indicated 55−75% removal of the target NAPL constituents when partitioning tracer data were used to estimate the initial amount of NAPL present and 60−175% removal of two target constituents when soil core data were used to estimate the amount of NAPL initially present. These results indicate that the SPME flood effectively removed the NAPL constituents of concern, but an insoluble anthropogenic residue was left behind.

Influence of Target Structure on Film Stress in WTI Sputtering

ABSTRACTIn this report, the effect of sputtering target microstructure on the deposited film stress was investigated. By controlling the metallurgical process, two types of W-10wt%Ti target constituents, namely single-phase and multiple-phase WTi, were prepared. The former one was composed of W-rich (βTi,W) phase only, the latter one was with W, W-rich (βTi,W) and Ti-rich (βTi,W) phases. The stress of the films deposited on 12.7 cm diameter silicon oxide wafers from the single-phase target tends to be more compressive than that from the multiple-phase target. By increasing wafer temperature, the compressive stress was linearly decreased. In addition, the level of film stress was also affected by the film thickness and other sputtering parameters. To understand the causes for the differences in film stress between the multiple-phase and singlephase derived films, an evaluation of the film structure using a field-emission scanning electron microscope (FE-SEM) and mechanical testing using a nano-indentation instrument were performed. Finer domains with denser laminar structure were observed on the films deposited from the single-phase target. However, no significant difference in mechanical properties was found between these two from the nano-indentation measurements. It is envisioned that the more uniform solid solution between the W and Ti in the films obtained by sputtering the single-phase targets generates a higher compressive stress when deposited on the silicon oxide wafers resulting in a higher compressive stress.

Mineral processing characteristics of natural zeolites from the Aritayn Formation of northeast Jordan

The inferior grade of natural zeolite ores in comparison to their synthetic counterparts has been identified as a possible factor responsible for the relatively small market share of the former. This paper describes the results of laboratory-scale mineral processing trials carried out on relatively low-grade natural zeolite ores from the Aritayn Formation of northeast Jordan to improve their purity through removal of unwanted gangue constituents. Appropriate sample preparation and mineral processing methods were selected which utilised contrasts in texture, particle-size, hardness, specific gravity and magnetic susceptibility between gangue and target constituents to achieve beneficiation. Sample preparation by autogenous comminution was able to selectively liberate zeolite minerals from the surface of pyroclasts and therefore was an effective method of pre-concentration. Subsequently, using widely-available magnetic and gravity separation equipment, a high-grade concentrate containing 89% zeolite was produced at a recovery of 37% from a lapilli tuff of 47% head grade.

Dynamics of laser ablation plume penetration through low pressure background gases

The dynamics of laser-ablated yttrium plume propagation through background argon have been investigated with fast time- and spatially-resolved plasma diagnostics in order to characterize a general phenomenon believed to be important to film growth by pulsed laser deposition (PLD). During expansion into low-pressure background gases, the ion flux in the laser ablation plasma plume is observed to split into fast and slow components over a limited range of distances including those typically utilized for PLD. Optical absorption and emission spectroscopy are employed to simultaneously identify populations of both excited and ground states of Y and Y+. These are correlated with intensified-CCD (ICCD) photographs of visible plume luminescence and ion fluxes recorded with fast ion probes. These measurements indicate that plume-splitting in background gases is consistent with scattering of target constituents by ambient gas atoms. The momentum transfer from these collisions produces a transition from the initial, ‘‘vacuum’’ velocity distribution into a velocity distribution which is significantly slowed in accordance with shock or drag propagation models.

Methods to control internal stress in Co-Cr sputtered films on polymer tape for curl-free recording tape

Co-Cr sputtered films have large enough internal stress to curl the polymer substrate. The internal stress σ seemed to be caused by energetic particles recoiling from targets and impinging on the growing film. Consideration of the collision process at the target plane suggested that Kr ions recoil less easily at target plane than Ar because Kr ions have a larger atomic mass than that of the target constituent. Experimental results showed that lower P Ar causes higher compressive σ, but films deposited in Kr gas tend to reveal tensile σ and good crystallinity. Another method to control σ of Co-Cr films is to prepare films at relatively high working gas pressure. However, the crystallinity and c-axis orientation of these films tend to be degraded. A two-step sputtering method may be applied to overcome the degradation of crystallinity of these films. A 100 Å thick Co-Cr underlayer prepared at low working gas pressure contributed significantly in improving the crystallinity and c-axis orientation of the Co-Cr layers prepared at high working gas pressure.

Combined use of the equivalent point method and a multicomponent time-temperature integrator in thermal process evaluation: influence of kinetic characteristics and reference temperature

Possibilities for and restrictions to the combined use of a multi component time-temperature integrator (TTI) and the equivalent point method (EPM) to quantify the impact of a thermal process were considered in this theoretical study. The impact on Clostridium botulinum spores, chosen as target quality attribute in this study can be represented fairly by an ‘equivalent point’ when the activation energies of the constituents making up the multicomponent TTI are close to the activation energy of the target quality attribute (error ⩽1%) but substantial errors (up to 60%) may arise when the activation energies of target and multicomponent TTI constituents differ largely. By reconsidering the temperature histories with three different reference temperatures (∞, 423K, 394.1 K). the importance of this rescaling parameter was found to be negligible. The combined use of a multicomponent TTI and the EPM to quantify the impact of a thermal process will require careful verification.

Characterization and in situ fluorescence diagnostic of the deposition of YBa2Cu3O7-x thin films by pseudo-spark electron beam ablation

The pseudo-spark electron beam ablation (PSA) technique is a comparatively simple and inexpensive method of depositing thin films of oxide materials. The effects of both the breakdown voltage of the discharge and the oxygen pressure on the power density of a pulsed electron beam and on the efficiency of the PSA process are studied. The PSA technique is applied to the deposition of YBa2Cu3O7-x thin films on single crystal SrTiO3 and MgO substrates. Thin films with zero resistance transition temperature around 87 K have been prepared at breakdown voltages from 18 to 25 kV. The role of the oxygen pressure in the PSA process, which is typically one order of magnitude less than that for a typical laser ablation system, is discussed. In situ spectral analysis of the radiative emission from the plasma plume has also been performed at different breakdown voltages of the discharge in an attempt to understand the behaviour of the target constituents in response to intensive pulsed electron beams.

Deposition of MoSi 2 thin films by laser ablation from free-falling particles

Thin films of molybdenum silicides were deposited by a new method in which mixtures of small, free-falling particles are heated by focused 10.6 μm radiation from a pulsed carbon dioxide laser in an ultrahigh vacuum chamber. The composition of the resulting films was adjustable and controlled by the selection of particle sizes and their relative numbers. It was found that collecting substrates positioned in the rearward hemisphere along the direction of the laser beam had films which were nearly free of defects. Recoil pressure exerted by the affluent vapor had the tendency to drive target residue into the forward hemisphere. Compositional analysis of the deposited films was performed using Rutherford backscattering spectroscopy. The measured values of atomic concentration are consistent with surface evaporation of the particles and are in close agreement with the values calculated from the specific surface areas of the target constituents and theoretical mass evaporation rates. Laser heating of molybdenum disilicide particles was found to produce silicon-rich Mo-Si films. Auger depth profiles of residual target particles which were collected on forward substrates were enriched in molybdenum.

Element distributions at depth from an iterative analysis of RBS spectra

The depth to which Rutherford backscattering (RBS) profiling can be applied has previously been restricted by statistics and the kinematic loss factor of the elements involved. We have developed an iterative technique by which exact depth profiling may be extended much further. High resolution spectra are taken with the target and detector at two or more different angles to the beam. Computer analysis is then applied to obtain the depth distribution of the elements involved. For a target composed of two elements, two angles suffice for the analysis, but more spectra are required for a larger number of elementary target constituents. The limit of depth resolution arises primarily from counting statistics and detector resolution, although we shall show that apparently there may also be a theoretical limit since successive iterations employ smaller and smaller depths.

Preferential sputtering of FeSi(100) single crystal surfaces by argon, neon, and krypton ion bombardment

Changes in the FeSi(100) surface composition, due the preferential sputtering, have been studied using Ar +, Ne + and Kr + ions in the energy range 300–3000 eV and Auger electron spectroscopy (AES). In the given energy range, silicon was found to be preferentially sputtered by argon, neon and krypton bombardment, this effect being more pronounced at low ion energies. The sputtering yield ratio (density corrected) K si K Fe was not found to be much different at low energies (> 500 eV), but at higher energies, between 500 and 3000 eV, differs considerably for the three projectiles used. The surface composition change depends on the projectile energy. The effects were less pronounced with the mass of the ions. The results are discussed taking into account projectile-to-surface energy transfer effects and energy dissipation through elastic collision cascade in alloys. The main effects come from the mass difference of the target constituent elements and not from the mass difference between projectile and target.

Ion-beam mixing of multilayered targets ballistic effects

In this work a Monte-Carlo method of dynamical type is used to simulate the ion-beam mixing of a composite, multilayered target. The calculation refers to a Ni-Ta structure, on a silicon substrate, bombarded with As+ ions and elucidates the effect of the dose and of the target structure on the intermixing of the target constituents.

Effects of target constituent mass difference on collision cascade induced composition changes in binary alloys

The cascade simulation code MARLOWE has been used to examine low dose composition changes caused by 5 keV Xe ions normally incident on a homogeneous polycrystalline target composed of 50%-50% Lu and Fe. The depth profile of the collision cascade induced atomic concentration of Lu is calculated and yields an excess of Lu in the surface, in agreement with the published results using the code TRIDYN. Calculation of the distributions of recoil Lu and Fe ions originating in particular layers indicate, however, that the heavier mass ion is driven deeper into the target, on the average, than the lighter mass ion—contrary to general perceptions.

La politique fédérale canadienne au singulier et au pluriel

RésuméComment peuvent s'expliquer la différence et la ressemblance entre les différents partis politiques au Canada? Voilà la question à laquelle nous tentons de répondre dans cet article en comparant les positions des trois partis politiques dominants sur cinq thèmes: l'avortement, la peine capitale, le chômage, le déficit, le gel de l'armement nucléaire. Les relations que les partis politiques entretiennent entre eux et avec les populations qu'ils veulent représenter, puis les exigences de la vie en société contraignent le discours politique à s'uniformiser. Cette homogénéisation n'empêche pas toutefois l'émergence de philosophies et de stratégies politiques originates.

A comparison of secondary ion emission from polycrystalline metals under MeV and keV heavy ion bombardment

Mass spectra of positive secondary ions emitted from polycrystalline metal targets bombarded by 70 MeV 79Br 7+ and 100 keV 40ar + ions have been measured under similar conditions in order to identify changes which may be attributed to the increased energy of the projectile. Presented here are results obtained from Al, Ti, V, and Ni foils. A significant enhancement of some low-mass target constituents relative to the atomic metal ions is observed with MeV ion bombardment. Most prominent is the increase in abundance of 16O + secondary ions.

RBS data processing. I: Analysis of non-stoichiometric targets

Abstract A technique which allows the depth distribution of an N-elemental target composition from Rutherford backscattering spectra to be obtained is presented. Using this technique one can calculate the ratio of the atomic concentration of each element to the total atomic concentration at some depth. The depth scale is determined in atoms/cm2. The contributions from all target constituents to the stopping of probe ions are taken into account. The stopping power is given by Bragg's rule. The individual RBS yields from N-1 constituents are required to apply the technique.

The energy distributions of atoms sputtered from HfC

The energy spectra of Hf and C atoms sputtered from an HfC target with a 6 keV Xe + beam have been measured. It was found that the target constituents of widely different masses were sputtered with energy distributions of the same form. The results are compared with the collision cascade theory for compound targets.