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1Author    T. SpringerRequires cookie*
 Title    High-Resolution Neutron Spectroscopy for the Investigation of Hydrogen Diffusion and Molecular Rotations in Solids  
 Abstract    An introductory survey on applications of high-resolution neutron spectroscopy is presented, dealing with the motion of hydrogen in solids, namely concerning (i) random rotational motions or stationary tunneling states of NH 4 -ions or CH 3 -groups, and (ii) diffusion of hydrogen in alloys. For the rotation of hydrogenous groups in solids, at higher temperatures rotational jumps can be found, whereas quantum states are observed by |J.eV-spectroscopy at temperatures below 50 K. On the other hand, hydrogen diffusion does not reveal pronounced evidence of quantum effects, except for hydrogen in a metal containing impurity atoms. 
  Reference    Z. Naturforsch. 48a, 406—414 (1993); received January 7 1992 
  Published    1993 
  Keywords    Quasielastic neutron scattering, Diffusion, Tunneling 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0406.pdf 
 Identifier    ZNA-1993-48a-0406 
 Volume    48 
2Author    A. Heinrich-Schramm, W. E. Price, H.-D LüdemannRequires cookie*
 Title     
 Abstract    h e In flu e n c e o f D ip o le -D ip o le I n te r a c tio n a n d H y d r o g e n B o n d in g U p o n T r a n s la tio n a l D iffu s iv ity in S im p le F lu id s Self-diffusion coefficients of dimethylether have been measured as a function of temperature (185-458 K) and pressure (up to 200 MPa) by pulse-gradient field spin-echo NMR. Calculated activation volumes (AV*) fall from 15 (10-6 m3/mole) at the highest temperature to 7 (10~6 m3/mole) at the lowest. This trend is in keeping with values for other non-associating liquids. Comparison with self diffusion data for propane and ethanol reveals that the translational diffusivity in dimethylether is influenced by the substance's modest dipole moment (1.3 Debye). The effect is small but measur­ able and becomes more pronounced at lower temperatures. S e lf-D iffu s io n in C o m p re s s e d D im e th y le th e r : 
  Reference    Z. Naturforsch. 50a, 145—148 (1995); received October 5 1994 
  Published    1995 
  Keywords    Dimethylether, Diffusion, High Pressure 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0145.pdf 
 Identifier    ZNA-1995-50a-0145 
 Volume    50 
3Author    N. Ikolaus, N. Estlea, PetrikG. Alvosas3, Christian Zimmermannb, Marwan Dakkourib, Jörg Kärger3Requires cookie*
 Title    Nuclear Spin Relaxation and Water Self-diffusion in Hardening Magnesium Oxychloride Cement  
 Abstract    In this contribution, we report the results of NMR studies of the behaviour of water in a hydrating Sorel cement paste with a composition close to the stoichiometric optimum. Both the transverse spin-relaxation behaviour and water self-diffusion were studied in two separate experiments performed on samples on the basis of the same formulation. While there is a very strong initial decrease in the transverse relaxation time of the water in the paste, the diffusion coefficient is found to decrease mainly at later times of the hydration process where the decrease of the transverse relaxation time has already strongly slowed down. After about 6 h of the hardening process, the signal intensity available for a pulsed gradient diffusometry experiment is not sufficient any more for reliable measurements of the diffusion coefficients. 
  Reference    Z. Naturforsch. 56a, 561—564 (2001); received May 18 2001 
  Published    2001 
  Keywords    Oxychloride Cement, Diffusion, Magnetic Resonance 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0561.pdf 
 Identifier    ZNA-2001-56a-0561 
 Volume    56 
4Author    D. Girlich, H.-D Lüdemann, C. Buttersack, K. BuchholzRequires cookie*
 Title    c , T-Dependence of the Self Diffusion in Concentrated Aqueous Sucrose Solutions  
 Abstract    The self diffusion coefficients D of the water molecules and of sucrose have been deter­ mined by the pulsed field gradient NMR technique over a wide range of temperatures and concentrations (cmax: 70% w/w sue.). All temperature dependencies can be fitted to a Vogel-Tammann-Fulcher equation. The isothermic concentration dependence of D for the sucrose is given by a simple exponential concentration dependence. 
  Reference    Z. Naturforsch. 49c, 258—264 (1994); received December 21993 
  Published    1994 
  Keywords    Diffusion, Sucrose, Water, Aqueous Solution 
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 TEI-XML for    default:Reihe_C/49/ZNC-1994-49c-0258.pdf 
 Identifier    ZNC-1994-49c-0258 
 Volume    49 
5Author    O. Wegener3, R. K. Üchler3, A. W. AtterichbRequires cookie*
 Title      
 Abstract    12STe nuclear spin relaxation (NSR) and electrical conductivity measurements were performed on ultrapure single-crystalline paratellurite (a -T e0 2) between about 50 K and the melting point (1007 K) at various oxygen partial pressures (1 b a r -10"4 bar). At elevated temperatures the NSR rate l / 7 \ and conductivity a are caused by the diffusive motion o f point defects. From the observed p02-dependence of 1/Ti and a a defect model is developed which is shown to be consistent with the experimental data. The m odel involves ionic oxygen interstitials (O"), doubly charged oxygen vacancies (Vo') and charge-com pensating electron holes (h'). The observed pressure dependence suggests that the N SR rate is induced by the m otion of \ q while the conductivity is due to the m obility o f h*. Evaluation o f the data leads to 3.3 eV for the incorporation enthalpy o f oxygen on interstitial sites and to 4.5 eV for the formation enthalpy of oxygen Frenkel pairs (O "-V q'). Further, the chemical diffusion coefficient Dc is found to be caused by the ambipolar diffusion o f OS' and h \ At 950 K we obtained from both the NSR and conductivity experiments D c = (1 ± 0.3) • 10" 5 cm 2/s. 
  Reference    Z. Naturforsch. 49a, 1151 (1994); received August 22 1994 
  Published    1994 
  Keywords    Oxides, Point defects, Diffusion, N M R, Conductivity 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-1151.pdf 
 Identifier    ZNA-1994-49a-1151 
 Volume    49 
6Author    YaA. Ossipyan, N. S. Sidorov, V. I. Kulakov, V. L. Matukhin, A. I. Pogoreltsev, V. N. Anashkin, I. A. Safin, L. E. MatukhinaRequires cookie*
 Title    NQR Studies of Halogen Treated 1-2-3 System  
 Abstract    NQR spectra of copper in polycrystalline samples of iodine treated RBa 2 Cu 3 O y (R = Y, Gd) were studied. The results of all the experiments show evidence for the modifications occurring in the oxygen sublattice in treated compounds. 
  Reference    Z. Naturforsch. 53a, 542—545 (1998); received March 24 1998 
  Published    1998 
  Keywords    NQR-spectra, Superconductors, Treatment, Halogens, Diffusion 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0542.pdf 
 Identifier    ZNA-1998-53a-0542 
 Volume    53 
7Author    M. Arie-Theres, Hauser, Michael WinkRequires cookie*
 Title    Uptake of Alkaloids by Latex Vesicles and Isolated Mesophyll Vacuoles of Chelidonium ntajus (Papaveraceae)  
 Abstract    Latex vacuoles o f Chelidonium majus (Papaveraceae) naturally sequester protoberberine and benzophenanthridine alkaloids. Isolated vesicles take up a number o f other heterologous alkaloids, such as 9,10-dihydroergocryptine, vinblastine, strychnine, nicotine, colchicine, lupanine, and 13-hydroxylupanine, with a strong preference for the indole alkaloids and for nicotine. Kinetic data clearly show that the uptake proceeds via simple diffusion and not by carrier-mediated transport. The alkaloids are concentrated in the vesicles against a concentra­ tion gradient. M gA TP has no influence on alkaloid uptake. It is likely that alkaloids are trapped in the vesicles by chelidonic acid (concentration in latex 58 mM, in vesicles 661 mM) which com plexes these alkaloids and thus prevents their rediffusion out o f the vesicles. Uptake o f these alkaloids by leaf protoplasts and vacuoles o f Ch. majus, by vacuoles o f suspension-cultured cells o f Lupinuspolyphyllus and by rabbit erythrocytes was studied for comparison. 
  Reference    Z. Naturforsch. 45c, 949 (1990); received January 15/May 18 1990 
  Published    1990 
  Keywords    Chelidonium m ajus, Alkaloid Uptake, Vacuole, Latex, Diffusion, Ion-Trap 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0949.pdf 
 Identifier    ZNC-1990-45c-0949 
 Volume    45 
8Author    A. Harfoush, S. Sh, SoulaymanRequires cookie*
 Title    Presparking Effect in Spark Source Mass Spectrometry  
 Abstract    The Relative Sensitivity Factor (RSF) in Spark Source Mass Spectrometry analysis was found to be dependent on the number and duration of previous sparking periods. This dependency becomes very strong when dealing with volatile elements. By statistical analysis of experimental RSF values it was found that there is a linear correlation between In (RSF) of some trace elements and their boiling temperature. This correlation fails when dealing with volatile elements and carbon. It was found that elements with a large diffusion coefficient have a large RSF. 
  Reference    Z. Naturforsch. 47a, 748—752 (1992); received September 12 1989 
  Published    1992 
  Keywords    Relative Sensitivity Factor, Spark Source Mass Spectrometry, Presparking effect, Boiling temperature, Diffusion 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0748.pdf 
 Identifier    ZNA-1992-47a-0748 
 Volume    47 
9Author    Wolfram Hartung, Barbara DierichRequires cookie*
 Title    Uptake and Release of Abscisic Acid by Runner Bean Root Tip Segments  
 Abstract    Uptake o f abscisic acid by 5 mm long decapped root tips is a linear function o f the external ABA concentration in the range o f 2.9 x 10-8 m to 10~4 m and decreases dramatically with in­ creasing pH. At pH 8.0 uptake rate is extremely low, even at high ABA concentrations. This indicated that nearly all o f the ABA is taken up as the undissociated m olecule ABAH. Uptake o f ABA is influenced by agents m odifying the pH gradients between the m edium and the tissue such as salts o f weak acids incubated at low external pH (inhibition o f uptake and stim ulation o f ABA release by abolishing the pH gradients), protonophores such as CCCP (inhibition o f uptake) and fusicoccin (stim ulation o f uptake by increasing the pH between m edium and cytoplasm). It is concluded that ABA distributes between the compartments o f the root cells according to the pH gradients with the undissociated m olecule as the only penetrating species. Uptake and release occur without participation o f a saturable com ponent by diffusion. In contrast IAA permeates the plasm alem m a as both IAAH and IAA-. 
  Reference    Z. Naturforsch. 38c, 719 (1983); received March 31 1983 
  Published    1983 
  Keywords    Abscisic Acid, Diffusion, Indole Acetic Acid, Phaseolus coccineus, Plasm alem m a, Transport 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0719.pdf 
 Identifier    ZNC-1983-38c-0719 
 Volume    38