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81.
An organic binding polymer based on polyacrylonitrile (PAN) was used for the preparation of the composite exchanger containing ammonium molybdophosphate (AMP) as the active component. Due to the improvement of granulometric properties of powdered AMP with a binding polymer, an exchanger suitable for the application in column operations was prepared. Study of the properties of the exchanger AMP-PAN proved that kinetics of cesium sorption, capacity of the exchanger for cesium and desorption of cesium are not influenced by the binding polymer. The composite exchanger AMP-PAN described is therefore suitable for the selective separation and concentration of cesium and purification of radioactive wastes from137Cs. 相似文献
82.
Štefan Toma Anton Gáplovský Milan Hudeček Zuzanna Langfelderová 《Monatshefte für Chemie / Chemical Monthly》1985,116(3):357-364
The electronic absorption spectra of 22 arylferrocenes and their arylferricenium salts with pentacyanopropenide (PCNP) were recorded. The attemptedHammett correlation of max of the d-d transition bands of arylferrocenes revealed that this band is substituent dependent only for strong electron-withdrawing substituents. Excellent correlation of max of the d-d transition bands with + constants was found in the case of arylferricenium cations. Good correlations of max was also found with theE
1/2 oxidation potentials measured by cyclic voltametry.
Substituentenabhängigkeit des d-d-Überganges in den Elektronenabsorptions-Spektren von Arylferrocenen und entsprechenden Arylferricenium-Salzen
Zusammenfassung Elektronenabsorptions-Spektren von 22 Arylferrocenen und ihren Arylferricenium-Pentacyanopropenid-Salzen wurden gemessen. VersuchteHammett-Korrelationen des längstwelligen d-d-Überganges (max) zeigten, daß diese Bande nur von stark elektronenanziehende Substituenten abhängig ist. Im Fall der Arylferricenium-Kationen wurde eine ausgezeichnete Korrelation zwischen max der d-d-Bande und den +-Konstanten festgestellt. Eine gute Korrelation der max-Werte wurde auch mit denE 1/2 Oxidationspotentialen gefunden, die durch cyclische Voltametrie meßbar sind.相似文献
83.
Comparison of equilibrium and nonequilibrium models of a CSTR with total condenser focused on the multiple steady states and
dynamic behaviour was carried out. The steady-state behaviour of the model system, MTBE synthesis from methanol and isobutene
in a reactive distillation column, was studied in terms of the input parameters, i. e. feed flow rate of methanol or butenes, reflux ratio, and mass of catalyst. The dynamic behaviour of the system during the
start-up was investigated and perturbations of manipulated variables were found to cause transitions between the parallel
steady states.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
84.
Dijana Šimkūnaitė Emilija Ivaškevič Aleksandras Kaliničenko Antanas Steponavičius 《Journal of Solid State Electrochemistry》2006,10(7):447-457
The early stages of Cu electrodeposition onto Pt(poly) have been investigated in 0.5 M H2SO4 + 0.01 M CuSO4 solution without or with H2SeO3 when a molar concentration ratio [Cu(II)]/[Se(IV)] ≥ 2×102 using electrochemical and ex situ AFM techniques. The overpotential deposition of Cu has been performed onto a Pt surface precovered independently with Cu in amount close to an equivalent monolayer. Chronoamperometric results have been shown to follow an instantaneous 3D nucleation and diffusion-controlled growth model. The values of diffusion coefficient D for Cu2+, number of nuclei N and average nuclei radius r
av have been calculated. In the local regions of the surface, the separate large agglomerates composed of the different diameter clusters have been revealed in both cases, but, in the presence of the H2SeO3, they attained a distinct chain-like configuration. Some morphological characteristics have been reported. 相似文献
85.
Lucija Jukić Urška Bratušek Marko Škof Jurij Svete Branko Stanovnik 《Chemistry of Heterocyclic Compounds》1996,32(11-12):1295-1299
A novel approach to the synthesis of 3-acylindolizines and the transformations of some acids into tryptophane analogues are described. Reaction of ethyl 2-pyridinylacetate and methyl 2-quinolinylacetate with N-trifluoroacetyl-5-bromo-4-oxonorvaline methylester led to N-trifluoroacetyl-3-(1-ethoxycarbonylindolizinyl-2) alanine methyl ester and N-trifluoroacetyl-3-(3-methoxycarbonylpyrrolo [1,2-a]quinolinyl-2) alanine methyl ester, respectively. Treatment of ethyl 2-pyridinylacetate and 2-pyridinylacetonitrile, first with N,N-dimethylformamide dimethyl acetal (DMFDMA), followed by reaction with phenacyl bromide, gave the corresponding 3-benzoylindolizines, while the reaction of ethyl 2-pyridinylacetate and 2-pyridinylacetonitrile with DMFDMA, followed by treatment with (S)-N-trifluoroacetyl-5-bromo-4-oxonorvaline methyl ester, gave the corresponding N-trifluoroacetyl-4-oxo-4-(indolizinyl-3)homoalanine methyl esters. 相似文献
86.
The effect of TMTD on the polymerization of methyl methacrylate was studied. The plot of shows a maximum ascribed to participation of TMTD-radicals in cross (P′ + RS′) and mutual-termination (RS′ + RS′). The total polymerization rate is then well expressed by a derived relation. Study of the influence of TMTD on the molecular weight of polymethylmethacrylate allows characterization of the transfer process. 相似文献
87.
88.
Conclusions We conclude that the occurrence of a maximum in the magnetization versus temperature curve observed under certain circumstances on U3P4 is not connected with its intrinsic magnetic structure, but substantially depends on the form in which the material is studied (polycrystalline powder, single crystal, single crystal powders with various dimensions of grains). This phenomenon seems to be affected by quenching of the state from the region of low anisotropy at higher temperature in the small particles with a strong tendency to single domain behaviour and thus it may be a consequence of rotation magnetization process in the fields relatively small for U3P4. The assertion about transitions between magnetic ordering, sometimes proposed in the literature on the basis of observed anomalies in the temperature course of magnetization without simultaneous confirmation by neutron diffraction, should be accepted with some reservation, especially in the case of simple uranium compounds. However, another situation arises for pseudobinary alloys of ferro- and antiferromagnetic components (e.g. UP0·75S0·25) where such transitions were confirmed both by magnetic methods and by neutron diffraction studies [13].The authors would like to express their thanks to Ing. A.Meovský for careful preparation of samples. 相似文献
89.
90.
S. Paszkiewicz A. Szymczyk Z. Špitalský M. Soccio J. Mosnáček T. A. Ezquerra Z. Rosłaniec 《Journal of Polymer Science.Polymer Physics》2012,50(23):1645-1652
Nanocomposites based on poly(ethylene terephthalate) (PET) and expanded graphite (EG) have been prepared by in situ polymerization. Morphology of the nanocomposites has been examined by electronic microscopy. The relationship between the preparation method, morphology, and electrical conductivity was studied. Electronic microscopy images reveal that the nanocomposites exhibit well dispersed graphene platelets. The incorporation of EG to the PET results in a sharp insulator‐to‐conductor transition with a percolation threshold (?c) as low as 0.05 wt %. An electrical conductivity of 10?3 S/cm was achieved for 0.4 wt % of EG. The low percolation threshold and relatively high electrical conductivity are attributed to the high aspect ratio, large surface area, and uniform dispersion of the EG sheets in PET matrix. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献