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71.
A potassium electrode utilizing a solution of valinomycin in diphenylether and a porous membrane is compared with selectrodes in which the diphenylether has been replaced by a suitable plasticizer and the porous membrane support by a polymer net-work. The development of the polymer membrane allows the use of simplified selectrode construction with a “solid-state” calomel reference system; Rules for a successful choice of a suitable solvent-polymer combination are suggested and used for development of new Polyvinylchloride- and polyurethane-based membranes. 相似文献
72.
C. C. Pavel K. Popa N. Bilba A. Cecal D. Cozma A. Pui 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(2):243-248
The microporous titanosilicate ETS-10 synthesized from gel with following molar composition: 1.0 Na2O: 1.49 SiO2 : 0.2 TiO2 : 0.6 KF : 1.28 HCl : 39.5 H2O was subjected to sorption of radioactive cations 115Cd2+, 204Hg2+, 60Co2+ and 137Cs+ (M) from aqueous solution, in the absence of ionic competition. The uptake of these cations on the ETS-10 was compared by means of the distribution coefficient (Kd) versus contact time and sorption capacity (R) at equilibrium. The FT-IR spectra of M-ETS-10 sorption products exhibit a modification of the absorption band, principally at 381 cm-1. 相似文献
73.
Both particle packed (25 cm x 0.46 cm I.D. SUPELCOSIL 5 microm C18) and monolithic type (10 cm x 0.46 cm I.D. Merck Chromolith Performance C18) reversed-phase substrates were dynamically coated with a carboxybetaine type zwitterionic surfactant ((dodecyldimethyl-amino) acetic acid) and investigated as stationary phases for use in zwitterionic ion chromatography (ZIC). Investigations into eluent concentration and pH were carried out using KCl eluents containing 0.2 mM of the carboxybetaine surfactant to stabilise the column coatings. It was found that eluent concentration decreased anion retention whilst simultaneously increasing peak efficiencies, which may be due to the dissociation of intra- and inter-molecular salts of the carboxybetaine surfactant under higher ionic strength conditions. The Effect of eluent pH was an increase in anion retention with decreased eluent pH due to the increased protonation of the weak acid terminal group of the carboxybetaine, causing both a relative increase in the positive charge of the stationary phase and less repulsion of the anions by the dissociated weak acid group. The carboxybetaine-coated monolithic phase was applied to rapid anion separations using elevated flow rates and flow rate gradients. 相似文献
74.
An improved version of the disposable multichannel immunochemical biosensor for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) based on a screen-printed amperometric transducer and monoclonal antibodies (MAb) against 2,4-D is reported. Entrapment within a thin Nafion film was used for the direct immobilization of MAb at the electrode surface. The amount of the tracer (2,4-D conjugated to acetylcholinesterase) bound in a competitive immunochemical reaction was determined amperometrically using acetylthiocholine iodide as substrate. The measuring procedure (times of incubation with tracer and substrate, pH, tracer concentration) was optimized. The sensor was able to detect less than 0.01 μg/L of free 2,4-D in water. One analysis (8 samples) was completed in 30 min (20 min for immunochemical reaction, 5 min incubation with substrate, 5 min measurement). The performance of the immunosensor (two configurations) was evaluated on real samples (tap water) with added 2,4-D. The determined amounts (mean values 0.097 to 0.105 and 0.89 to 1.13) corresponded well with the added contents of 2,4-D (0.100 and 1.00 μg/L, respectively). 相似文献
75.
We propose a model for the production of extra (additional) lepton pairs in deep inelastic lepton-hadron scattering, e+e– annihilation and large pT processes. Extra lepton pairs are supposed to be originated by annihilations of quarks and antiquarks created during the space-time evolution of quark initiated jets. This mechanism yields predominantly dileptons with rather low masses. Predictions following from the model are compared with the recent data on trimuon production in neutrino-nucleon interactions. It is also suggested that internal hard processes can lead to dileptons with both small and large masses. The latter mechanism has rather small cross section but it is particularly interesting from the point of view of the simple quark-parton model.Dedicated to Academician Václav Votruba on the occasion of his seventieth birthday. 相似文献
76.
Acta Mathematica Hungarica - 相似文献
77.
Optical absorption of vitreous GeSb2Se4 was studied in spectral region 0.7–25 μm. At low absorption levels near the edge the absorption coefficient K depends exponentially on energy. At high absorption levels the quadratical energy dependence of K is observed. In the present work we determined the optical energy gap Eoptg = 1.29 eV and discussed the temperature dependence of the absorption coefficient. Measured reflectivity curves were used to estimate the value of the refractive index of GeSb2Se4 (). Vitreous GeSb2Se4 is also transparent in the spectral interval 2–15.7 μm. 相似文献
78.
M. Ri
ka H. ebkov Besedi
ov J. Doupovec J. Strcelský 《Crystal Research and Technology》1976,11(12):1245-1254
HgJ2 single crystals both pure and doped were grown from an acetone solution using the method of the slow solvent evaporation. The iodides NaJ, KJ, SrJ2, CdJ2, NH4J were used as doping materials in concentrations from 0.01 to 2.0 wt%. The grown crystals were studied with respect to the influence of impurity doping on the electric conductivity and the phase transitions at atmospheric pressure (the DTA method) and high pressure as well (with the help of the high pressure optical cell). 相似文献
79.
Silvia Dulanská Boris Remenec Ján Bilohuštin Miroslav Labaška Dušan Galanda 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2189-2192
This paper describes the use of IBC’s AnaLig® Sr-01 molecular recognition technology product to effectively and selectively pre-concentrate, separate, and recover strontium from urine samples. This method uses two-stage columns separation consisting of two different commercial products Eichrom’s Pre-filter Material and AnaLig® Sr-01 column from IBC Advanced Technologies. This method does not involve co-precipitation of strontium as phosphates and oxalates from urine samples. The new rapid method separates strontium-90 with high chemical recovery. 相似文献
80.
M. Králorá H. Mouchorá J. Janoušek 《Isotopes in environmental and health studies》2013,49(11):435-436
Es war Ziel dieser Arbeit, zu ermitteln, welchen Einfluß höhere Dosen von Stickstoffdüngemitteln in Form von KNO3 auf die Menge des in der Pflanze fixierten Luftstickstoffs haben. Als Versuchspflanze wählten wir Pferdebohnen (Vicia faba, Chlumetzer Abart) wegen ihrer vielseitigen Verwendung in der Landwirtschaft und ihrer besonderen experimentellen Eignung. 相似文献