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Abstract  

The feasibility of using trace multielement data obtained from neutron activation analysis to identify the source of crude oil residues was recently demonstrated. This paper presents the concentrations of Br, Co, Cr, Sb, Sc, Zn, and V/Ni, for 30 crude oil residues collected from beaches (beach asphalt), using 1 g samples. The method does not require chemical separation or post-irradiation concentration. The average standard deviation for the V/Ni ratio was ±0.39.

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Periodica Mathematica Hungarica
Authors:
D. Szász
,
L. Kovács
, and
J. Mayer
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Thermogravimetry and vapor pressure moisture

Applications to determination of residual moisture in BCG vaccine

Journal of Thermal Analysis and Calorimetry
Authors:
J May
,
A Del Grosso
,
N Etz
,
R Wheeler
, and
L Rey

Abstract  

Thermogravimetry (TG), thermogravimetry/mass spectrometry (TG/MS), and loss-on-drying methodology are used to provide residual moisture results for freeze-dried biological products regulated by the US Food and Drug Administration. Residual moisture specifications must be met in order to ensure freeze-dried biological product potency and stability throughout the licensed product's shelf life. TG, TG/MS, loss-on-drying and vapor pressure moisture measurements are compared for a BCG Vaccine. Comparisons are made between residual moisture data for the freeze-dried cake and vapor pressure moisture determinations in the space above the freeze-dried cake in the final container. Vapor pressure moisture precision data is presented for α-interferon and BCG vaccine. Impact of residual moisture and vapor pressure moisture upon product stability is presented.

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Abstract  

The cyclotron production of21Na, via the20Ne(d, n)21Na and the20Ne(3He, pn)21Na and20Ne(3He, 2n)21Mg 21Na nuclear reactions, has been investigated. Transfer of21Na from the production target to the medical application site some 10 m distant was achieved by gas phase and liquid phase systems, both of which are described. Under optimal conditions 111 MBq·ml–1 (3 mCi·ml–1) of21Na were available at the dispensing reservoir 10 m distant from the production target, when irradiating with a 5 A deuteron beam current. Incident deuteron energy was degraded to below 3.0 MeV by a 350 m Al entrance foil, to avoid production of18F. The charge distribution of21Na inside the production target and inside the gas phase transfer tube at distances of 1 m and 15 m were determined, and are reported along with data from similar studies during18F production via the20Ne(d, )18F reaction.21Na accumulated primarily at the cathode, indicating the production of positively charged species, whereas18F was equally distributed between the electrodes in a production target constructed especially for measuring the charge distribution of the radioactive species.

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Abstract  

Liquid scintillation counting of radionuclides emitting beta radiation with Emax>2 MeV has been investigated. Fluor volume effects were similar to those for low energy beta radiation, and pulse height spectra broadened in a predictable manner with no pulse clipping up to 4.913 MeV. Large changes in sample channels ratio due to color quenching resulted in progressively smaller losses of counting efficiency as beta energy increased. Counting efficiences were estimated to be near 100 percent for34Clm,36Cl,32P and38Cl. Cerenkov counting of38Cl by liquid scintillation counter was volume dependent for both counting efficiency and pulse height spectrum. Counting efficiencies for34Clm,36Cl,32P and38Cl were estimated to be 57.0, 7.5, 42.7 and 66.3%, respectively. Pulse height spectra were shifted to greater pulse heights as a function of beta Emax, supporting the possibility of energy discrimination for beta emitters by Cerenkov pulse height spectrum analysis. The advantage of singles Cerenkov counting over coincidence Cerenkov counting was greatest for36Cl and least for38Cl; this advantage was amplified more for samples of36Cl which had been color quenched than for similarly quenched samples of38Cl or32P.

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