[en] This letter to the editor reviews background information and background studies of the possible risks of plateout of radon on woman's clothing particularly brassiers, composed almost exclusively of synthetic fibers. 5 refs

[en] Advantage is taken of the non-uniform axial neutron flux density distribution in a nuclear reactor core by using fuel rod spacers of low neutron absorption in high neutron flux density regions and fuel rod spacers of low coolant flow resistance in the lower neutron flux density regions of the core, this spacer combination also providing higher fuel bundle thermal limits

[en] The uneven axial neutron flux distribution in a nuclear reactor core is used by using fuel rod spacers of low neutron absorption in areas of high neutron flux density and fuel rod spacers of low flow resistance to the coolant in areas of low neutral flux density of the core, where this combination of spacers also offers a higher thermal limit of the bundle of fuel elements. (orig.)

[en] Assimilation of ammonium (NH4) into free amino acids and total reduced nitrogen (N) was monitored in both roots and shoots of two-week old rice seedlings supplied with 5 mM 99% (15NH4)2SO4 in aerated hydroponic culture with or without a 2 h preincubation with 1 mM methionine sulfoximine (MSX) an inhibitor of glutamine synthetase (GS) activity. 15NH4 was not assimilated into amino acids when the GS/GOGAT (glutamate synthase) cycle was inhibited by MSX. Inhibition of glutamine synthetase (GS) activity in roots with MSX increased both the amount of NH4 and the abundance of 15N labeled NH4. In contrast, the amount of Gln and Glu, and their proportions as 15N, decreased in roots when GS activity was inhibited. This research confirms the importance of GS/GOGAT in NH4 assimilation in rice roots. 15N-labeled studies indicate that NH4 ions incorporated by roots of rice are transformed primarily into glutamine (Gin) and glutamic acid (Glu) before being converted to other amino acids through transamination. The formation of amino acids such as aspartic acid (Asp) and alanine (Ala) directly from free NH4 in roots also has been reported. Translocation of free NH4 to plant shoots, based on the concentration of free NH4 in xylem exudate, has been reported in tomato, although NH4 in shoots primarily originates from nitrate reduction in the shoot. Photorespiration also can contribute to the accumulation of NH4 in leaves. The GS/GOGAT cycle appears to be primarily responsible for the assimilation of exogenously supplied NH4 and NH4 derived from nitrate reduction in leaves, as well as NH4 derived from photorespiration. Genetic evidence cited to support this conclusion includes the lethal effect of photorespiratory conditions on plant mutants deficient in chloroplast-localized GS and GOGAT activities, and the rapid accumulation of free NH4 in GS-deficient mutants under photorespiratory conditions. The present study was initiated to quantify the in vivo amino acid synthesis in rice root

[en] This paper summarizes some of the plant operation performance improvement techniques developed by the General Electric Company Nuclear Energy Business Operation for the General Electric Boiling Water Reactors (GE BWR's). Through the use of both thermal and plant hardware operating margins, substantial additional flexibility in plant operation can be achieved resulting in significant improvements in plant capacity and availability factor and potential fuel cycle economics for the currently operating or requisition GE BWR plants. This list of techniques includes expanding the BWR thermal power/moderator flow operating domain to the maximum achievable region, operation with a single recirculation loop out of service and operation at rated thermal power with reduced feedwater temperatures. These plant improvements and operating techniques can potentially increase plant capacity factor by 1% to 2% and provide additional fuel cycle economics savings to the GE BWR's owners

[en] An assessment study was performed to determine the feasibility of increasing the core thermal power to approximately 104.2 % of the original licensed rated value in order to obtain an increase in the core steam flow rate of 5 % for a typical General Electric BWR/6 power plant. Areas which are expected to be affected by the increase in the rated thermal power were evaluated in the study. Results of this assessment study show that, overall, the 5 % increase in steam flow and the associated 4.2 % increase in core thermal power are feasible for a typical BWR/6 plant. However, reduced fuel thermal margins may constrain operation at the 104.2 % uprated power level during part of the operating cycle with current GE6/7 fuel designs. Improved GE8B fuel design with a 14.4 kw/ft linear heat generation rate limit, coupled with recently USNRC approved more realistic loss-of-coolant accident licensing models and assumptions, should allow operation at the uprated power level during the entire operating cycle. This assessment conclusion for a typical BWR/6 plant is derived mainly based on the reactor core performance capability of the plant. For specific plant capability assessment application, detailed systems and equipment impact, as uniquely applied to each individual plant, are to be evaluated. It is also felt that, based on assessment results of this study, significant major power uprates beyond the 4 % level is potentially feasible for BWRs in the future with fuel and plant modifications and testing verifications. (author)

[en] The photoreactivity of 3-hydroxy-2,4-dioxo-1,2,3,4 tetrahydropteridine (4) and its possible photochemical conversion to its 1-hydroxy (6) isomer were investigated. The only photoprocess observed was the deoxygenation via the triplet with no formation of 6. The effect of pH on the reaction was determined. Photoreactivity of 1-hydroxy-2-oxo-1,2-dihydropteridine (7) was also examined. Both the neutral molecule and its anion produced the same C-4 oxidation product. The photochemical reaction product was probably formed via the hydrate of 7

[en] Electron beam irradiation effects in SiO₂ have been studied by STEM (Scanning Transmission Electron Microscopy). Oxygen loss and the corresponding transformation from SiO₂ to Si in SiO₂ are confirmed and consistent with previous reports. A ''flower-like'' Si rich area, which might not be observed in STEM BF (Bright Field) or ADF (Annular Dark Field) images, was found in Si plasmon energy filtered images. Quantification of the observations and the formation mechanisms leading to the Si-rich area are discussed

[en] Alkylacetylglycerols are synthesized from 1-alkyl-2-lyso-sn-Gro-3-P via an acetyltransferase (I) and a phosphohydrolase (II). The final step that forms PAF in this pathway is catalyzed by a dithiothreitol-insensitive cholinephosphotransferase. This report describes properties of the acetyltransferase (I) and the phosphohydrolase (II). Results indicate the two activities are distinctly different from acetyl-CoA:1-alkyl-2-lyso-GroPCho acetyltransferase (III) and phosphatidic acid phosphohydrolase (IV), respectively. For example, 12.5 or 25 μM alkyl-lysoGroPCho did not affect the quantity of alkylacetylGroP and alkylacetylGro produced. The pH optimum for (I) was 8.4 as opposed to 6.9 for (III); also (I) and (III) had different sensitivities when microsomes were preincubated at various temperatures. Phosphatidic acid had no effect on the hydrolysis of the phosphate from alkylacetylGroP (II) and the pH optimum of the phosphohydrolase (II) was 6.6. Based on the distribution of marker enzymes, both acetyltransferases (I and III) and the alkylacetylGroP phosphohydrolase (II) are of microsomal origin. The phosphohydrolase (II) activity can be maximally inhibited by adding Na₃VO₄ and NaF to the assays and further decreased by incubating samples at a reduced temperature (23⁰C); under these conditions the amounts of alkylacethlGroP is maximum. The newly identified enzyme activities (I and II) are relatively high in a variety of rat tissues, which suggests this de novo route is responsible for maintaining physiological levels of PAF

[en] L-M cells grown in a lipid-free medium containing ¹⁴C-labeled 9, 12-linoleic acid incorporated most of this acid into glycerolipids as linoleic acid. Only a small amount (3%) was elongated to eicosadienoic acid. No Δ6 desaturation occurred. When the cells were incubated with ¹⁴-C-labeled 8, 11, 14-eicosatrienoic acid, 22% of the activity was found in 5, 8, 11, 14-eicosatetraenoic acid. Treatment of the cells for 24 hr with N-isopropylethanolamine, a choline analog, depressed this desaturation reaction to about 60% of control values. The identity of the tetraene product was established by two different chromatographic analyses of the fatty acid methyl esters. Location of the double bond at position C-5 was determined by ozonolysis and subsequent reduction of the ozonides to aldesters followed by gas-liquid chromatography. These results prove that L-M cells have a Δ5 desaturase and an elongation enzyme converting 18 : 2 to 20 : 2, but lack a Δ6 desaturase