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1

Digitale Medien

Microwave cavity spectrometer for process monitoring of ethylene oxide sterilization (1993)

Zhu, Z. ; Gibson, C. ; Samuel, A. H. ; [weitere]

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

Review of Scientific Instruments 64 (1993), S. 103-108

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ISSN: 1089-7623

Quelle: AIP Digital Archive

Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik

Notizen: This article reports a novel and simple cavity spectrometer for process monitoring of ethylene oxide sterilization, in which the source frequency, cavity resonant frequency, and gas absorption center frequency are asynchronous with respect to each other, thus, enabling sophisticated signal enhancement techniques to be employed without the need to engage the Stark effect. The operation of the device is such that the source frequency sweeps across a given range (F1 to F2) which contains one of the absorption peaks of the analyte gas (gases) of interest while the cavity resonant frequency Fr is oscillated within the profile of the absorption peak. Signal enhancement is achieved by adding a relatively small magnitude/high-frequency "dither'' signal to the source frequency sweep pattern. The salient information of the gas absorption due to the oscillation of the resonant frequency of the cavity is carried by the "dither'' signal and amplified and extracted by a series of tuned amplifiers and demodulators. Although the device is still at the initial design stage, a working prototype has been constructed in order to test the feasibility of the novel asynchronous modulation technique. This was achieved by successfully demonstrating that the device operates in an expected manner to within a standard error of 8.3%. It is believed that this error largely results from mechanical components. The significance of this error is greatly reduced when the spectrometer is operated in a large signal scanning mode as is the case when we apply the "power saturation'' technique to measure the concentration of ethylene oxide in the resonant cavity. This measurement showed that there is a good linear correlation between the output signal and the concentration of ethylene oxide gas (to within a standard error of 4%).

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.1144422

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2

Digitale Medien

Comparative solvolytic reactivity of bay-region diol epoxides derived from dibenz[a,j]anthracene and dibenzacridines (1990)

Sayer, Jane M. ; Lehr, R. E. ; Kumar, S. ; [weitere]

s.l. : American Chemical Society

Journal of the American Chemical Society 112 (1990), S. 1177-1185

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ISSN: 1520-5126

Quelle: ACS Legacy Archives

Thema: Chemie und Pharmazie

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1021/ja00159a044

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3

Digitale Medien

Refractive Index Measurements in Qualitative Organic Microanalysis (1939)

Kirk, Paul L. ; Gibson, C. S.

s.l. : American Chemical Society

Industrial and engineering chemistry 11 (1939), S. 403-403

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Quelle: ACS Legacy Archives

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1021/ac50135a025

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4

Digitale Medien

CORRESPONDENCE Deposition of Gold on Fabrics (1939)

Gibson, C.

s.l. : American Chemical Society

Industrial & engineering chemistry 31 (1939), S. 1186-1186

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ISSN: 1520-5045

Quelle: ACS Legacy Archives

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1021/ie50357a030

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5

Digitale Medien

Alignment of vorticity and scalar gradient with strain rate in simulated Navier–Stokes turbulence (1987)

Ashurst, Wm. T. ; Kerstein, A. R. ; Kerr, R. M. ; [weitere]

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

Physics of Fluids 30 (1987), S. 2343-2353

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ISSN: 1089-7666

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The alignment between vorticity and eigenvectors of the strain-rate tensor in numerical solutions of Navier–Stokes turbulence is studied. Solutions for isotropic flow and homogeneous shear flow from pseudospectral calculations using 1283 grid points have been examined. The Taylor Reynolds number is 83 or greater. In both flows there is an increased probability for the vorticity to point in the intermediate strain direction and at three-fourths of the sample points this strain is positive (extensive). This propensity for vorticity alignment with a positive intermediate strain is a consequence of angular momentum conservation, as shown by a restricted Euler model of the coupling between strain and vorticity. Probability distributions for intermediate strain, conditioned on total strain, change from a symmetric triangular form at small strain to an asymmetric one for large strain. The most probable value of the asymmetric distribution gives strains in the ratios of 3:1: −4. The evolution of the distribution from a symmetric to an asymmetric form as the strain magnitude increases is essentially the same in both flows, indicating a generic structure of intense turbulence. The alignment between the gradient of a passive scalar and eigenvectors of the strain-rate tensor for Prandtl numbers of 0.1, 0.2, 0.5, and 1.0 has also been studied. There is an increased probability for the scalar gradient to align in the most compressive strain direction, and the average gradient is larger when it is pointing in that direction. Estimates for the scalar dissipation from the turbulent kinetic energy, its dissipation, and the root-mean-square scalar value are in reasonable agreement with calculated scalar dissipation if no explicit Prandtl number dependence is used in the estimate. Statistical analysis of scalar dissipation conditioned on energy dissipation yields a power-law relation between conditioned mean values. Both simulated flows are found to obey the qualitative predictions of the Gurvich–Yaglom (lognormal) intermittency model. Energy and scalar intermittency exponents are estimated and compared to measured values.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.866513

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6

Digitale Medien

Cyclomorphosis in natural populations of Oscillatoria redekei Van Goor (1975)

GIBSON, C. E.

Oxford, UK : Blackwell Publishing Ltd

Freshwater biology 5 (1975), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Evidence is presented of a regular seasonal variation in the filament length of Oscillatoria redekei Van Goor in Lough Neagh. This cycle is not in phase with the seasonal changes of the biomass of the species, but seems to occur in step with the nutrient concentrations. Some possible mechanisms of filament replication are discussed and evidence is presented that mechanical forces are not effective in breaking filaments. The ecological significance of cyclomorphosis in this species is difficult to establish.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2427.1975.tb00141.x

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7

Digitale Medien

Changes in phytoplankton physiology and morphology in response to dissolved nutrients in Lough Neagh, N. Ireland (1979)

GIBSON, C. E. ; STEVENS, R. J.

Oxford, UK : Blackwell Publishing Ltd

Freshwater biology 9 (1979), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: SUMMARY. Cell phosphorus and anthrone-reactive carbohydrate contents were measured over a 6-month period in the phytoplankton of Lough Neagh, N. Ireland. When all the soluble reactive phosphorus had disappeared from the water column, cell phosphorus contents began to decrease, reaching a minimum value of 0.4% ash-free dry weight. At this time, cell carbohydrate contents greatly increased and phosphorus sorption assays showed rapid uptake of orthophosphate. Following a presumed sediment phosphorus release, cell carbohydrate and phosphorus uptake rate decreased greatly and there was a subsequent increase in cell phosphorus content to 1.6% ash-free dry weight. As the cell phosphorus content declined, blue-green algal filaments became progressively shorter. On the basis of these responses it is likely that phosphorus limitation occurred over a 4-week period.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2427.1979.tb01494.x

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8

Digitale Medien

Sinking rates of planktonic diatoms in an unstratified lake: a comparison of field and laboratory observations (1984)

GIBSON, C. E.

Oxford, UK : Blackwell Publishing Ltd

Freshwater biology 14 (1984), S. 0

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ISSN: 1365-2427

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: SUMMARY. 1. Natural population sinking rates were calculated by fitting an exponential regression to 6 years’observations on declining crops of Melosira italica subarctica O. Müll. and Stephanodiscus astraea (Ehr.) Grun.2. Losses were described by an exponential model which yielded still water sinking rates of 0.86 md−1 for M. italica and 0.45md−1 for S. astraea.3. Laboratory measurements of the sinking rate of natural populations showed that the rate increased abruptly from less than 0.2 m d−1 in growing populations to 0.4 m d−1 after silica depletion.4. The measured sinking rate of S. astraea agreed well with that observed in the field. Where as populations of M. italica appeared to sink more quickly in the lake than could be accounted for by laboratory observations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-2427.1984.tb00182.x

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9

Digitale Medien

Bovine amelogenin message heterogeneity: alternative splicing and Y-chromosomal gene transcription (1992)

Gibson, C. W. ; Golub, E. E. ; Abrams, W. R. ; [weitere]

s.l. : American Chemical Society

Biochemistry 31 (1992), S. 8384-8388

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ISSN: 1520-4995

Quelle: ACS Legacy Archives

Thema: Biologie , Chemie und Pharmazie

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1021/bi00150a036

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10

Digitale Medien

Calculation of Minimum Reflux in Distillation Columns (1950)

Shiras, R. N. ; Hanson, D. N. ; Gibson, C. H.

s.l. : American Chemical Society

Industrial & engineering chemistry 42 (1950), S. 871-876

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ISSN: 1520-5045

Quelle: ACS Legacy Archives

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1021/ie50485a034

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