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171.
Molecular hydrogen yields are reported for cupric sulfate solutions irradiated with high-energy heavy ions. The data are sparse but appear to be consistent with expectations from current theoretical models of the track structure of these ions. By considering these data in conjunction with previously published yields from other systems, estimates of the total water decomposition yields, G'-H2O, have been made. 相似文献
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N.Thomas Christman Lyle H. Hamilton 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1982,229(2)
A new instrument has been developed which offers many advantages over instruments presently utilized for the measurement of breath-hydrogen used to evaluate the intestinal absorption of sugars. The gas analyzer has a solid-state sensor which is more specific for hydrogen than most conventional chromatographic detectors. Air can be used as the carrier gas and can be circulated with a small internal pump, thereby eliminating large carrier gas tanks and pressure regulators. The intersample time is approximately 2 min, allowing rapid serial analysis of breath samples. A unique feature allows a short-term memory circuit to recall the signal and present it on a digital panel meter in parts per million. Recorder terminals on the back permit the generation of a permanent record, if desired. The gas analyzer is small, lightweight and simple to operate. Its application to the serial measurement of hydrogen in alveolar air after ingestion of sugars is demonstrated. 相似文献
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Quantitation of S-adenosylmethionine decarboxylase protein 总被引:3,自引:0,他引:3
A method for the specific labeling of the active site of S-adenosylmethionine decarboxylase was developed. The method consisted of incubating cell extracts with 3H-decarboxylated S-adenosylmethionine and sodium cyanoborohydride in the presence of a spermidine synthase inhibitor. Under these conditions, S-adenosylmethionine decarboxylase was labeled specifically and stoichiometrically. This procedure was used (a) to establish that the subunit molecular weight of S-adenosylmethionine decarboxylase from rat liver, prostate, and psoas and from mouse SV-3T3 cells was 32 000, (b) to titrate the number of active molecules of S-adenosylmethionine decarboxylase in various cell extracts, and (c) to provide a high specific activity labeled preparation of S-adenosylmethionine decarboxylase for use in radioimmunoassay of this enzyme. Competitive radioimmunoassays using this labeled antigen had a sensitivity such that 3 fmol (0.1 ng) of enzyme protein could be quantitated. The rapid loss of S-adenosylmethionine decarboxylase which occurred when SV-3T3 cells were exposed to exogenous polyamines was shown to be due to a rapid decline in the amount of enzyme protein measured both by titration of the active site and by radioimmunoassay. 相似文献
176.
12-O-Tetradecanoyl-phorbol 13-acetate is a very effective tumor promotor and inflammatory agent and can act as a mitogen for a subset of T lymphocytes. We report here that even short exposure of lymphocytes to 12-O-tetradecanoyl-phorbol 13-acetate changes the balance between the levels of neutral ribonuclease and ribonuclease inhibitor. The most dramatic change occurs in a B-lymphocyte-enriched population. We find that most, if not all, of the neutral ribonuclease activity in circulating lymphocytes is associated with this population and that this activity is lost with exposure to 12-O-tetradecanoyl-phorbol 13-acetate. Both 12-O-tetradecanoyl-phorbol 13-acetate and phytohaemagglutinin increase the level of ribonuclease inhibitor in T cells. However, phytohaemagglutinin has no effect on the ribonuclease or inhibitor level of the B-cell-enriched population. 相似文献
177.
S. Shukla D. GoswamiW.D. Graham A.W. HodgesM.C. Christman J.M. Knowles 《Ecological Engineering》2011,37(8):1158-1163
Ditch fencing and culvert cattle crossing Best Management Practice (BMP) was evaluated in this study with regard to phosphorus (P) and nitrogen (N) load reductions and economic feasibility in the Lake Okeechobee (LO) basin. The BMP was implemented at a 170 m section of a drainage ditch within a ranch in the LO basin and flow and concentration (N and P) data at the upstream and downstream of the ditch were collected for one pre-BMP (June-October, 2005) and three post-BMP (June-October, 2006-2008) periods. During the pre-BMP period, downstream total P (TP) load was 20% (67.0 kg) higher than the upstream, indicating the cattle crossing to be a source of P. Downstream loads of TP in 2006 and 2008 (post-BMP periods) became 26% (14.7 kg) and 11% (85.9 kg) lower than the upstream loads, respectively indicating that the BMP reduced the P loads. The site was a sink for N for all periods except the 2007. Unusual dry conditions during 2007 resulted in the addition of P and N at the BMP site, probably due to the release of P and N from soil and plants. Average of three post-BMP period load showed a 10% reduction of TP loads at the downstream (251.8 kg) compared to the upstream (281.0 kg) location. To consider potential P contributions from the soil and plant, two scenarios, conservative and liberal, were considered to estimate P load reductions due to the BMP. For the conservative scenario, P contribution from soil and plant was considered, while for liberal it was not. Reductions in P loads for conservative and liberal scenarios were 0.35 and 0.44 kg/day, respectively. Phosphorus removal cost for the conservative scenario was $12.61/kg of P, which is considerably less than the cost of other P reduction strategies in the basin. Overall, results show that the BMP can reduce P concentration and loads from ranches without causing adverse impact on cattle production. 相似文献
178.
Reed Cody C. Merrill Amy G. Drew W. Mark Christman Beth Hutchinson Rachel A. Keszey Levi Odell Melissa Swanson Sherman Verburg Paul S. J. Wilcox Jim Hart Stephen C. Sullivan Benjamin W. 《Ecosystems》2021,24(5):1125-1141
Ecosystems - As the largest biogeochemically active terrestrial reserve of carbon (C), soils have the potential to either mitigate or amplify rates of climate change. Ecosystems with large C stocks... 相似文献
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Vladimir Ilievski Yale Cho Priya Katwala Heriberto Rodriguez Margaret Tulowiecka David Kurian Lara Leoni John W. Christman Terry G. Unterman Keiko Watanabe 《PloS one》2015,10(8)