TRITIUM RELEASE CHARACTERISTICS OF Al-Li ALLOYS EXAMINED BY LIQUID SCINTILLATION TECHNIQUE

1987 ◽  
Vol 48 (C3) ◽  
pp. C3-541-C3-545 ◽  
Author(s):  
H. SAITO ◽  
Y. ISHIDA ◽  
H. YOSHIDA
Keyword(s):  
Liquid Scintillation ◽  
Tritium Release

STEROID FORMATION IN PORCINE OVARIAN TISSUE IN VITRO

1970 ◽  
Vol 63 (3) ◽  
pp. 441-453 ◽  
Author(s):  
Asbjørn Aakvaag
Keyword(s):  
Liquid Scintillation ◽  
Specific Activity ◽  
Ovarian Tissue ◽  
Gas Liquid Chromatography ◽  
Similar Concentration ◽  
Endogenous Substrates ◽  
Exogenous Progesterone ◽  
Relative Utilization ◽  
Radioactive Substrate

ABSTRACT Slices of non-luteinized porcine ovaries have been incubated in the presence or absence of human chorionic gonadotrophin (HCG) and exogenous radioactive substrates. Progesterone, 17α-hydroxyprogesterone and androstenedione were isolated in a radiochemically pure form. The chemical mass and the specific activity were determined by gas liquid chromatography and liquid scintillation spectrometry. HCG stimulated the rate of formation of androstenedione in the absence of exogenous substrates with a factor of 4–8. In the presence of pregnenolone or progesterone at a concentration of about 2 × 10−6 mol/l the stimulatory effect of HCG was either abolished or markedly reduced. The conversion of exogenous progesterone to androstenedione was reduced in response to HCG indicating that the capacity of the tissue to convert progesterone to androstenedione was limited, and that the limit was reached at this rather low substrate concentration. These findings furthermore suggest that the endogenous rather than the exogenous radioactive substrate will be »preferred« by the tissue. The observations demonstrate the necessity of measuring both the radioactivity and the chemical mass of the products in investigations of this type using radioactive substrates. The formation of progesterone from endogenous substrates was also stimulated by HCG. [1-14C] acetate and [7α-3H]cholesterol were not utilized by the tissue for steroid formation. Exogenous [4-14C] pregnenolone and [7α-3H] progesterone in similar concentration were both utilized for production of 17α-hydroxyprogesterone and androstenedione. HCG had no effect on the relative utilization of the radioactive substrates.

Toxicity, Uptake, and Distribution of Simazine in Canna hybrida `King Humbert': Implications for Phytoremediation

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 484e-485
Author(s):  
Patrick C. Wilson ◽  
Ted Whitwell ◽  
Steven J. Klaine
Keyword(s):  
Mass Production ◽  
Photosynthetic Efficiency ◽  
Liquid Scintillation ◽  
Herbicidal Activity ◽  
Fresh Mass ◽  
Contaminated Water ◽  
Golf Courses ◽  
Plant Tolerance ◽  
Nutrient Media ◽  
Potential Use

This research focuses on the potential use of Canna hybrida `King Humbert' for removing simazine from contaminated water generated at golf courses and ornamental nurseries. Because of simazine's herbicidal activity, it is important for levels in solution not to exceed plant tolerance levels. Tolerance levels for C. hybrida were determined by dosing plants for 7 d with 0, 0.01, 0.03, 0.1, 0.3, 1.0, or 3.0 mg simazine/L nutrient media. Measurements of 7-d fresh mass production and photosynthetic efficiency (Fv/Fm) were taken. Simazine uptake and distribution within the plant was determined by dosing plants with 2.03 mCi 14C-simazine (0.243 mg/L) for 1, 3, 5, or 7 d. Plant tissues were analyzed by combustion and liquid scintillation counting. Fresh mass production was reduced 66% and 78% for plants exposed to 1.0 and 3.0 mg/L, respectively. Likewise, photosynthetic efficiency was reduced to 66% and 40% of the controls at the same respective concentrations. Plant uptake of simazine accounted for 13%, 34%, 48%, and 65% of the original simazine in the dosing solution after 1-, 3-, 5-, and 7-d exposure, respectively. This simazine was distributed primarily between roots and leaves.

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