The total cross section for the reaction pp-*ppn Q was measured at nine center-of-mass energies from 1.5 to 23 MeV above threshold. The experiment was carried out with the Indiana Cooler, a recently constructed storage ring. The experimental advantages of an electron-cooled proton beam were utilized. The data cover an energy range where only the lowest possible angular momentum state contributes in the exit channel. The measured energy dependence of the total cross section is not compatible with that predicted by models of s-wave pion production and rescattering. PACS numbers: 25.10,+s, 13.75.Cs, 21.30.+y, 29.25.Fb Meson-exchange models of the nucleon-nucleon (AW) interaction above the pion threshold rely on detailed information about the strongly coupled inelastic channels which must be treated coherently with the elastic interaction. Information on pion production in the NN system is also required in models of pion production or absorption in nuclei. Customarily, the partial waves in the exit channel of NN-* NNK reactions are labeled by Ll, where L is the angular momentum of the nucleon pair and / is the angular momentum of the pion with respect to the nucleon pair. l Within 100 MeV of threshold, because of the short range of the interaction, only Ss, Sp, Ps, and Pp final states contribute significantly; within 25 MeV the Ss configuration should dominate. In addition, the Sp final state is forbidden in the pp-* ppn° reaction.In the pp-^ppK° reaction, the normally dominant pion production via an intermediate A7V system is suppressed, since the N and the A cannot be in a relative S state. The rescattering contribution is also small because the dominant isovector part of low-energy nN scattering cannot contribute. Thus, near threshold, the pp-*ppn° reaction is dominated by the direct-production Born term. 2 The energy dependence of the cross section is customarily expressed in terms of n, the largest possible center-of-mass pion momentum (with nucleons at rest relative to each other) divided by the pion mass. Based on phase-space arguments, the assumption of r/
The activity of acis‐9‐fatty acid hydratase produced by aPseudomonas sp. (NRRL B‐3266) isolated from soil was compared with that of another isolate previously reported (NRRL B‐2994). The presence of appropriate fatty acids for at least 4 hr during aerobic growth in yeast extract medium increased subsequent enzyme activity. Such cells anaerobically hydrated severalcis‐9‐alkenoic acids to 10‐hydroxy fatty acids and aerobically formed 10‐keto acids, which were partially degraded to shorter chain keto acids. Melting point, gas chromatography, infrared, mass spectrometry and optical rotatory dispersion data are given. Six fatty acids havingcis‐9‐unsaturation produced hydrated products, but several enoic acids havingtrans‐9‐unsaturation or double bonds in other than the 9 position were inactive as substrates. The (−)‐10‐hydroxypalmitic acid produced from palmitoleic acid is considered to have the D configuration. Yields of 71% crude crystalline product from 15 g of oleic acid and 53% from 11 g of palmitoleic acid were obtained in 5‐liter anaerobic fermentations with NRRL B‐3266. Methyl esters, triolein and oleyl alcohol were not hydrated.
ABSTRACT:The contribution of various electroencephalographic electrodes in detecting spikes from patients with seizures of suspected anterior temporal origin was prospectively studied with a standard protocol. The following electrodes were studied: International Standard 10-20 positions F7-8 and A1-2, sphenoidal (SP), nasopharyngeal (NP), anterior temporal (Tl-2), mandibular notch surface (MNS), and mandibular notch subdermal (MNSD). Twenty patients were recorded of whom 16 demonstrated anterior temporal spikes. There was no difference in the number of spikes detected by SP, MNS, MNSD, or Tl-2 electrodes (p < 0.05); however these electrodes detected significantly more spikes than NP, F7-8, or A1-2. The SP electrode recorded spikes of highest amplitude (p < 0.05). We conclude that for patients suspected of having seizures of anterior temporal origin, (1) a substantial number of spikes will be missed if only the International Standard electrode system is employed; (2) in comparison to SP electrodes the noninvasive and easily applied MNS or Tl-2 electrodes will detect almost all spikes and should be used in outpatient EEG recordings; (3) NP electrodes provide no information that cannot be obtained by more reliable and better tolerated electrodes.
Maize (Zea mays L.) endosperm suspension cultures are a useful model system for studying biochemical and physiological events in developing maize endosperm. In this report, sugar uptake by the cultures is characterized. Uptake of '4C-labeled fructose and L-glucose was linear with time, while the rate of uptake of radioactivity from sucrose increased over a 120 min period. Both saturable and linear components of uptake were observed for fructose, glucose, sucrose, 1'-deoxy-1'-fluorosucrose, and maltose. Uptake of mannitol, sorbitol, and L-glucose took place at lower rates and was linear with concentration. Rates of incorporation of radioactivity from fructose and glucose exceeded that of sucrose at all concentrations tested. Kinetics of 1'-deoxy-1'-fluorosucrose uptake indicated that '4C from sucrose can be taken up by a saturable carrier of intact sucrose as well as by invertase hydrolysis and subsequent uptake of hexoses. Cell wall invertase was demonstrated histochemically. Further study of fructose uptake at a concentration at which the saturable component predominated revealed sensitivity to metabolic inhibitors, respiratory uncouplers, the nonpermeant sulfhydryl reagent p-chloromercuribenzenesulfonic acid, and nigericin. Uptake was not affected by valinomycin plus K' and was stimulated by fusicoccin. Fructose and glucose uptake was not pH-sensitive below pH 7.0, whereas uptake of radioactivity from sucrose and 1 '-deoxy-1 '-fluorosucrose declined as the pH was increased above 5.0. Fructose uptake was not completely inhibited by glucose and vice versa, suggesting the presence of specific carriers. These results indicate that maize endosperm suspension cultures (a) absorb fructose via a typical, energy-requiring, carrier-mediated proton cotransport system; (b) possess saturable carriers for glucose and sucrose; and (c) also absorb sucrose via hexose uptake after sucrose hydrolysis by extracellular invertase.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.