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Digitale Medien

Stability of ion-implanted layers on MgO under ultrasonic cavitation (1996)

Romana, L. J. ; Rankin, J. ; Brewster, J. R. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 80 (1996), S. 2781-2787

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The effects of ion implantation and ultrasonic cavitation on the near-surface region of MgO single crystals were investigated. For 150 keV, room-temperature implantations of Ar+ or K+ at 5×1016–1017 ions cm−2 into a (100)-oriented surface of MgO, a dilatometric swelling of the implanted layer is observed perpendicular to the implanted surface. When these strained surface layers are then subjected to an ultrasonic (∼20 kHz) cavitation treatment, uniform layers (∼100–200 nm) can be removed from the MgO surface in a controlled manner. The thickness of the removed layer is directly related to the duration of the ultrasonic irradiation, but does not exceed the depth of the implanted species. When MgO implanted with Ar+ or Kr+ at fluences of 5×1016–1017 ions cm−2 is subsequently irradiated with 2 MeV He+ ions at 1016–1017 ions cm−2, the region exposed to the He+ beam is effectively "stabilized'' and is not removed by the ultrasonic treatment. K+ or Ar+ implantations at 〈5×1016 ions cm−2 produced no swelling of the layer, and subsequent ultrasonic irradiation with an energy flux of ∼120 W cm−2 did not remove the crystal surface as determined by profilometry. For MgO implanted with (approximately-greater-than)2×1017 ions cm−2, the implanted layer is highly strained and detaches from the underlying crystal without exposure to ultrasonic-cavitation effects. These findings are discussed in terms of the stressed states of the implanted layers, and their potential applications to the mechanical "etching'' of ceramics are considered.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.363195

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Digitale Medien

Density-Dependent Growth and Survival of Penaeus setiferus and Penaeus vannamei in a Semi-Closed Recirculating System (1996)

Williams, A. S. ; Davis, D. A. ; Arnold, C. R.

Oxford, UK : Blackwell Publishing Ltd

Journal of the World Aquaculture Society 27 (1996), S. 0

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ISSN: 1749-7345

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract.— Two growth trials utilizing Penaeus vannamei and Penaeus setiferus were conducted at densities of 28.4, 56.8, 85.2, 113.6, 170.4, 227.3 and 284.1/ m2 in an indoor recirculating system. There was an inverse linear relationship between stocking density and growth among both species. The relationship between final weight and stocking density is described by the following linear equation: P. setiferus, Y =−0.00619X ± 4.46, adj. r2= 0.8572;.P. vannamei, Y=−0.00717X ± 7.39, adj. r2= 0.6230. Although the responses in terms of growth depressions were similar, P. setiferus growth was lower than that of P. vannamei. There was an inverse relationship between stocking density and survival for P. setiferus. Survival of P. vannamei was highly variable but was negatively correlated with density. Based on the results of the present study, P. setiferus has a similar tolerance of high density as that of P. vannamei and hence may be suitable for intensive culture systems. However, depressed growth rates of P. setiferus, which do not appear to be due to effects of water quality or density, must be solved if growth rates similar to P. vannamei are to be realized.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1749-7345.1996.tb00600.x

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Digitale Medien

Measurement uncertainty in analytical chemistry (1996)

Williams, A.

Springer

Accreditation and quality assurance 1 (1996), S. 14-17

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ISSN: 1432-0517

Schlagwort(e): Key words Measurement ; Uncertainty ; Analysis

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract It is now becoming recognised in the measurement community that as well as reporting the measured value it is also essential to give its uncertainty. Without a knowledge of the uncertainty, it is impossible for the users of the result to know what confidence can be placed in it and it is also impossible to assess the comparability of different measurements of the same parameter. However, problems arise with the use of such terminology as error, accuracy, inaccuracy and uncertainty that has everyday connotations as well as formal definitions for use in metrology. The paper gives a resume of the reasons why it is important to evaluate and report the uncertainty on a result in a consistent manner. A description is given of the concept of uncertainty, which highlights the difference between it and error, accuracy or inaccuracy. This is followed by a discussion of the recommendations made by the "ISO – Guide to the Expression of Uncertainty in Measurement" for the evaluation and reporting of uncertainty. The methodology for evaluating uncertainty is described and the advantages of using suitable reference materials are discussed. Finally, the benefits to both the analytical laboratory and the user of the results from the evaluation and reporting of uncertainty are considered.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s007690050027

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Digitale Medien

Health state valuations from the general public using the Visual Analogue Scale (1996)

Gudex, C. ; Dolan, P. ; Kind, P. ; [weitere]

Springer

Quality of life research 5 (1996), S. 521-531

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ISSN: 1573-2649

Schlagwort(e): EuroQol ; health status measurement ; social preferences ; visual analogue scale

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract In the clinical and economic evaluation of health care, the value of benefit gained should be determined from a public perspective. The objective of this study was to establish relative valuations attached to different health states to form the basis for a ‘social tariff’ for use in quantifying patient benefit from health care. Three thousand three hundred and ninety-five interviews were conducted with a representative sample of the adult British population. Using the EuroQol health state classification and a visual analogue scale (VAS), each respondent valued 15 health states producing, in total, direct valuations for 45 states. Two hundred and twenty-one re-interviews were conducted approximately 10 weeks later. A near complete, and logically consistent, VAS data set was generated with good test-retest reliability (mean ICC=0.78). Both social class and education had a significant effect, where higher median valuations were given by respondents in social classes III–V and by those with intermediate or no educational qualifications. These effects were particularly noticeable for more severe states. The use of such valuations in a social tariff raises important issues regarding the use of the VAS method itself to elicit valuations for hypothetical health states, the production of separate tariffs according to social class and/or education and the appropriate measure of central tendency.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00439226

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Digitale Medien

Remote in situ analytical spectroscopy and its applications in the nuclear industry (1996)

Davies, C. M. ; Telle, H. H. ; Williams, A. W.

Springer

Fresenius' Zeitschrift für analytische Chemie 355 (1996), S. 895-899

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ISSN: 1618-2650

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract An experimental system based on Laser Induced Breakdown Spectroscopy (LIBS) has been used to analyze various ferrous samples. A fibre optic system has been used to transmit the incident laser pulse which produces the plasma plume at the surface of the analyte and to transmit back to a spectrometer the optical radiation emitted by the plasma. The measuring system may therefore be placed remote from the analyte which may be situated in a hostile environment such as an operating nuclear reactor. Results show that the system is capable of detecting chromium, nickel, manganese, molybdenum, silicon and vanadium at concentrations smaller than 5×10−4 g/g

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s0021663550895

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