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31.
The distribution of137Cs through soil layers has been investigated by field sampling. The investigation deals with137Cs concentration found after the Chernobyl accident. The relationship between important soil characteristics, total precipitation and cesium distribution are analyzed. Cesium is strongly sorbed in the top soil layer and its migration downward is limited. Measurements performed over a 3-year period revealed that approximately 20–38 per cent of total137Cs is located in the upper soil layer.  相似文献   
32.
An analytic expression for the total energy of metallic clusters composed ofN identical atoms of valencev and with net chargeQ is obtained by means of a variational solution of the Thomas-Fermi-Weizsäcker energy density functional within the spherical jellium model. The minimum energy is given as an expansion in decreasing powers of the cluster radiusR=r s Z 1/3, withZ=vN andr s the radius per electron of the bulk metal. The coefficients are obtained as functions ofr s . Terms of volume (R 3), surface (R 2), curvature (R), constant (R 0), (1/R) and (1/R 2) are clearly separated in the formula, as well as the different contributions (kinetic, coulombic and exchange-correlation) to each of them. The asymptotic values (R→∞) for the work functions,W(r s ), and surface energies σ(r s ), are compared to analogous semiclassical and Kohn-Sham calculations of jellium-like surfaces and to the experimental values. The size dependent behaviour of chemical potentials, μ(R), electron affinities,AF(R), and ionization potentials,IP(R), are easily obtained for any kind of metallic clusters. In particular we discuss the Coulomb and quantum corrections to the coefficients β, δ in the asymptotic formulae:IP?W+β/R andAF?W+δ/R.  相似文献   
33.
Effects of a nonzero mass for the tau neutrinov τ as well as a right-handed charged-current contribution to the τ?v τ coupling are discussed. Angular correlations of the decay products of τ+τ? ine + e ? annihilation are calculated as functions of \(m_{v_\tau } \) and the relative amount of right-handed τ?v τ coupling.  相似文献   
34.
Summary Synthesis of acetanilide and analogs in good yields has been carried out ing amounts by reacting the aromatic amines with an acetic anhydride-acetic acid mixture. After TLC separation on the same vehicle, the products can be visualized by ultraviolet radiation or by color reactions. A procedure is also described to recover the acetanilides for obtaining infrared spectra by the attenuated total reflection technique.
Zusammenfassung Die Synthese von Acetanilid und analogen Substanzen wurde mit guter Ausbeute in Mikrogrammengen durchgeführt. Man läßt das aromatische Amin mit einer Mischung von Acetanhydrid und Essigsäure reagieren. Nach DC-Trennung in diesem Laufmittel kann man die Reaktionsprodukte im UV oder durch eine Farbreaktion sichtbar machen. Außerdem wurde ein Verfahren beschrieben, die Acetanilide für die IR-Spektroskopie nach der ATR-Methode wiederzugewinnen.


For Part VIII see Mikrochim. Acta [Wien]1971, 662.  相似文献   
35.
Summary This paper describes techniques for separation and purification of steroids on the thin-layer plate. Two or more operations can be performed on the same plate in order to avoid loss of material and product.When a steroid diketone (progesterone) is treated with 2,4-dinitrophenylhydrazine on silica gel, three products are obtainable. These compounds can be readily purified on the same thin-layer plate and converted to the parent steroid by means of stannous chloride in dilute hydrochloric acid.
Zusammenfassung Trennung und Reinigung von Steroiden auf der Dünnschichtplatte werden beschrieben. Zwei oder mehr Operationen lassen sich, um Substanzverluste zu vermeiden, auf derselben Platte ausführen.Wird ein Diketosteroid (Progesteron) mit 2,4-Dinitrophenylhydrazin auf Kieselgel behandelt, so erhält man drei Reaktionsprodukte, die auf derselben Platte leicht gereinigt und mit Zinn(II)-chlorid in verd. Salzsäure in das entsprechende Ausgangssteroid zurückverwandelt werden können.
  相似文献   
36.
Ma X  Wu L  Ito Y  Tian W 《Journal of chromatography. A》2005,1076(1-2):212-215
Preparative separation of methyl gallate in leaves extract of Acer truncatum Bunge was conducted using high-speed counter-current chromatography (HSCCC) with a solvent system composed of ethyl acetate-ethanol-water at volume ratios of 5:1:5 (v/v/v). In a single operation, 57.5 mg of methyl gallate was obtained from 120 mg of the extract. HPLC analyses of the counter-current chromatography (CCC) fraction revealed that the methyl gallate was having over 97% purity. Its structure was identified by 1H NMR and 13C NMR.  相似文献   
37.
Summary A gas Chromatographic procedure for the analysis of carbamates is described. A specially prepared reaction tube, packed with a 10 % mixture of potassium hydroxide in glass beads, is placed inside the injection port of a Perkin-Elmer 900 Gas Chromatograph, in front of the Chromatographic column packed with Porapak Q. S.A solution of the carbamates (0.01–0.1mol) is injected directly into the gas Chromatograph. The carbamates are reacted with the alkali present in the reaction tube and the alcohols produced are separated, detected and recorded. Standard calibration graphs of the alcohols are prepared in the same manner and the quantities of carbamates are determined. The procedure is fast and quantitative.
Zusammenfassung Ein gaschromatisches Verfahren für die Analyse von Carbamaten wurde beschrieben. Ein spezielles Reaktionsrohr, beschickt mit 10% iger Kalilauge auf Glasperlen, wird innerhalb der Injektionsöffnung eines Gaschromatographen Perkin-Elmer 900 vor dem mit Poropak Q. S. gefüllten Chromatographierohr angebracht. Die Carbamatlösung (0,01 bis 0,1 Mol) wird direkt injiziert. Die Carbamate reagieren mit dem im Reaktionsrohr befindlichen Alkali, die dabei entstandenen Alkohole werden getrennt, nachgewiesen und registriert. In gleicher Weise ermittelte Standard-Eichkurven der Alkohole dienen zur Bestimmung der Carbamate. Das Verfahren ist rasch und quantitativ.


For Part II see Mikrochim. Acta [Wien]1966, 55. Inquiries and requests for reprints of this series of papers should be addressed to Prof. T. S. Ma, Department of Chemistry, City University of New York, Brooklyn, N.Y. 11210, U.S.A.  相似文献   
38.
39.
A reversed-phase LC–MS method with quadrupole-time of flight (QTOF) detection has been developed for the determination of four dinitro-toluenesulfonic acids and two amino-nitro-toluenesulfonic acids in groundwater. The analytes were separated by HPLC with 0.1% (v/v) formic acid as mobile phase modifier compatible with mass spectrometric detection. QTOF-MS analysis with negative ion electrospray ionization afforded good selectivity and sensitivity for analysis of the dinitro- and amino-nitro-toluenesulfonic acids. Structure elucidation and confirmation were accomplished by tandem mass spectrometry. Characteristic ions resulting from the loss of NO, NO2, and SO2 from the [M–H] ions were detected. An intense fragment ion at m/z 80 representing the [SO3] ion was detected for all dinitro- and amino-nitro-toluenesulfonic acids. Solid-phase extraction using a co-polymer cartridge was developed for preconcentration of the analytes from water. Good recovery (>85%) was achieved when 0.1% formic acid was added into the water samples before extraction. Method detection limits ranged from 10 to 76 ng L–1 for the targeted compounds when 10 mL water was analyzed. Groundwater samples collected from wells close to a former ammunition plant in Stadtallendorf, Germany, were analyzed for the dinitro- and amino-nitro-toluenesulfonic acids.  相似文献   
40.
This study investigated the visible-light catalysis mediated by zeolite NaY on the oxidation of dyes with H2O2. The results demonstrated that zeolite NaY acts as a sink for the electron from the photo-excited dye in the heterogeneous catalysis. Furthermore, the electron can effectively activate H2O2 to produce ·OH radical that is a powerful oxidant for the oxidation of dye at room temperature. The effects of the framework topology, Si/Al ratio, and exchangeable cation of the zeolite on the oxidation of various dyes were also shown.  相似文献   
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