Go toArchive
Browse byFacets
Bookbag ( 0 )
Facet   section ZfN Section A:Volume 043  [X]
Results  183 Items
Sorted by   
Publication Year
1988 (183)
161Author    Isao Okada, Teruo Haibara, Osamu Odawara, Masao Nomura, Makoto OkamotoRequires cookie*
 Title    Anomalous Distribution of K-lsotopes During Countercurrent Electromigration in Molten ( L i,K )N 0 3  
 Abstract    The previously presented theory that, in countercurrent electromigration of molten common anion binary mixtures, the lighter isotope of the less mobile cation should anoma­ lously enrich in a zone next to the anode, has been substan­ tiated for the K isotopes in molten (Li, K)N03. 
  Reference    Z. Naturforsch. 43a, 1005—1006 (1988); received August 28 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1005_n.pdf 
 Identifier    ZNA-1988-43a-1005_n 
 Volume    43 
162Author    B. Müller, Ch OttingerRequires cookie*
 Title    Über die spektroskopischen Konstanten des A2n -und JV2I-Z ustandes von A1H +  
 Abstract    The Spectroscopic Constants of the A2II and X2 Slates of AIH + Published experimental data on the spectroscopy of A1H * have been reanalyzed to obtain improved rotational con­ stants of the X2Z and A2I7 states. These allow a determina­ tion of vibrational constants in better agreement with experi­ ment. 
  Reference    Z. Naturforsch. 43a, 1007—1008 (1988); eingegangen am 29. September 1988 
  Published    1988 
  Keywords    A1H+, rotational constants, vibrational constants 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1007_n.pdf 
 Identifier    ZNA-1988-43a-1007_n 
 Volume    43 
163Author    D. LortzRequires cookie*
 Title      
 Abstract    Dedicated to Adrienne in memory of Pee-Pee-Islands The stability of axisymmetric ideal MHD equilibria which are symmetric with respect to the equatorial plane is considered. It is found that for external axisymmetric modes which are antisym­ metric with respect to the equatorial plane and for profiles such that the current density vanishes at the free plasma boundary the stability problem reduces to a classical interior-exterior scalar eigenvalue problem. Because of the separation property the resulting stability condition is necessary and sufficient and is thus more stringent than criteria derived by choosing special test functions, e.g. the vertical shift condition. O n th e S ta b ility o f A x is y m m e tr ic M H D M o d e s 
  Reference    Z. Naturforsch. 43a, 1009—1016 (1988); received October 12 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1009.pdf 
 Identifier    ZNA-1988-43a-1009 
 Volume    43 
164Author    J. Puszynski, S. Kumar, P. Dimitriou, V. HlavacekRequires cookie*
 Title     
 Abstract    N u m e ric a l a n d E x p e r im e n ta l S tu d y o f R e a c tio n F r o n t P r o p a g a tio n in C o n d e n s e d P h a s e S y s te m s Certain noncatalytic exothermic chemical reactions of the type solid-solid characterized by high values of activation energy and heat of reaction represent an example of strongly nonlinear chemi­ cally reacting systems. In these systems different types of propagating waves can be observed such as constant pattern, planar pulsating, and rotating waves. Numerical simulations in two and three spatial dimensions predict, qualitatively, the same behavior as experimentally observed. For geome­ trically large systems multihead spinning or erratic waves occur, which bifurcate from a planar pulsating front. In nonadiabatic systems the spinning wave is more resistant to extinction than the one-dimensional planar pulsating front. List of Symbols Subscripts C E Ko R R' concentration, kg m~3 heat capacity, Jkg-1 K_1 diameter, m activation energy, J mol-1 rate constant heat transfer coefficient, Jm "2s"' K universal gas constant, J mol"1 K-1 radius of sample, m radial coordinate, m reaction rate, mol m-3s-1 rate t time, s >C.)Rg T«?exp(E/Ä r* = Ek0(-AH)CSO temperature, K reference time, s u = z yJq CP\X f* dimensionless axial coordinate z axial coordinate, m. Greek Symbols öl = 4 KH/d dimensionless heat transfer coefficient ß = Rg TJE dimensionless activation energy _ —p—g * dimensionless heat of reaction C0 E(— AH) AH heat of reaction, Jkg 1 > 7 = 1— Cs/Cso conversion E ft = ----^{T— T*) dimensionless temperature R T ' heat conductivity, J m 1 s 1 K 1 v = At^/g Cpn2 d2 dimensionless circumference £ = r/R dimensionless radial coordinate g density, kg m"3 t dimensionless time (j) angular coordinate < Z > = <j>j2 n dimensionless angular coordinate Reprint requests to Prof. V. Hlavacek, 
  Reference    Z. Naturforsch. 43a, 1017—1025 (1988); received September 1 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1017.pdf 
 Identifier    ZNA-1988-43a-1017 
 Volume    43 
165Author    R. Blinc, J. Dolinšek, G. Lahajnar, A. I. Sepe, S. Zupančič, J. Žumer, Stefan, F. Milia, M. M. PintarRequires cookie*
 Title      
 Abstract    The time evolution of the magnetization relaxation recovery of exchangeable water in ordinary Portland cement and white cement have been studied as functions of the hydration time together with the temperature and Larmor frequency dependence of the proton spin-lattice relaxation rates. The water self-diffusion coefficient was also studied as a function of both the hydration time and the diffusion time. The results show that the exchangeable water relaxes via cross relaxation to the gel protons, which are in turn relaxed via spin diffusion to paramagnetic impurities. The roughness of the gel-water interface and the wide distribution of pore sizes result in a stretched exponential nuclear magnetization relaxation recovery with the exponent reflecting the fractal geometry of the hydrating cement gel. Key words: NMR. cement gels, hydration. S p in -L a ttic e R e la x a tio n o f W a te r in C e m e n t G e ls 
  Reference    Z. Naturforsch. 43a, 1026—1038 (1988); received July 31 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1026.pdf 
 Identifier    ZNA-1988-43a-1026 
 Volume    43 
166Author    Hans SallhoferRequires cookie*
 Title      
 Abstract    After a discussion of the one-component Schrödinger (1926) and the four-component Dirac (1928) representation of hydrogen it is shown that the six-component electrodynamic picture turns out to be considerably simpler and clearer. The computational effort is reduced to a fraction. 
  Reference    Z. Naturforsch. 43a, 1039—1043 (1988); received October 5 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1039.pdf 
 Identifier    ZNA-1988-43a-1039 
 Volume    43 
167Author    B.-E Mellander, J. R. StevensRequires cookie*
 Title    in  
 Abstract    th e p o l y (N N -d im e th y l a c r y la m id e) -L i C 1 0 4 s y s te m The poly(NN-dimethylacrylamide)-LiC104 system has been investigated regarding ionic conduc­ tivity and electric relaxation. This material may contain up to 29 mol% LiC104 while still being an amorphous and transparent ionic conductor. The conductivity for this composition is of the order of 10"9 (ohm cm)"1 at room temperature while it increases to 7 • 10~7 (ohm cm)"1 at 100°C. The activation energy according to the conductivity measurements is 1.1 eV. The system polymethyl­ methacrylate)-LiCF3S03 was also investigated but only very low ionic conductivities were detected. Key words: Ionic conductivity, electric relaxation dimethylacrylamide, lithium perclorate, poly­ mer electrolyte. Io n ic c o n d u c tiv ity a n d e le c tr ic r e la x a tio n 
  Reference    Z. Naturforsch. 43a, 1044—1046 (1988); received September 8 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1044.pdf 
 Identifier    ZNA-1988-43a-1044 
 Volume    43 
168Author    P. Kizler, P. Lamparter, S. SteebRequires cookie*
 Title     
 Abstract    h o r t R a n g e O r d e r in S tr u c tu r a l M o d e ls f o r th e A m o rp h o u s F e 80B 20-a n d N i 81B 19-A llo y s The short range order in several structural models for amorphous alloys is investigated with respect to pair correlation functions, bond angle distributions and other properties. Despite of the different principles of modelling, the topological short range order turned out to be almost identical. Therefore also the question for the triplet correlations to some extent is found solved. Remaining differences thus consist regarding more complex correlations among the atoms. 
  Reference    Z. Naturforsch. 43a, 1047—1054 (1988); received September 17 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1047.pdf 
 Identifier    ZNA-1988-43a-1047 
 Volume    43 
169Author    M. Schaal, P. Lamparter, S. SteebRequires cookie*
 Title     
 Abstract    a r ia tio n s o f th e P a r t i a l S h o r t R a n g e O r d e r S tr u c tu r e o f A m o rp h o u s N i3 2P d 52P i6 D u rin g R e la x a tio n U s in g N e u tr o n D if fr a c tio n a n d Is o to p ic S u b s titu tio n Melt spun amorphous Ni32Pd52P16 specimens were produced using natNi, the isotope 60Ni, and an isotopic mixture ^Ni with zero-scattering length. The specimens were heat treated for two hours at 496, 533, 570, and 607 K, respectively, and investigated by neutron diffraction. The Faber-Ziman structure factors as well as the total pair correlation functions show rather large effects caused by the relaxation procedure. By convenient combination of the total functions conclusions on the behaviour of the Ni-Ni, Ni-Pd, Ni-P, Pd-Ni, Pd-Pd, Pd-P, P-Ni, and P-Pd partial coordina­ tion numbers and atomic distances during the relaxation procedure are obtained. Relaxation has no detectable influence on the nearest neighbourhood but leads to variations in the region of the second Ni-Ni coordination sphere (3.7 Ä ^ R ^ 5.7 Ä) with the main effect that after heat treatment at 607 K, 2 h, the second Ni-Ni coordination sphere is subdivided into three distinct subspheres. It is suggested that the relaxation process mainly involves the redistribution of bond angles. 
  Reference    Z. Naturforsch. 43a, 1055—1060 (1988); received September 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1055.pdf 
 Identifier    ZNA-1988-43a-1055 
 Volume    43 
170Author    A. N., M. Schaal, P. Lamparter, S. SteebRequires cookie*
 Title     
 Abstract    o n c e n tra tio n -a n d D e n s ity -F lu c tu a tio n s w ith A m o rp h o u s N i63N b 37 by M e a n s o f N e u tro n S c a tte r in g a t S m a ll M o m e n tu m T r a n s f e r (S By means of small angle neutron scattering SANS using isotopic substitution the medium range structure of the amorphous Ni63Nb37-alloy was investigated. From the coherently scattered intensi­ ty in the region of small momentum transfer the total and partial Bhatia-Thornton structure factors were determined. For Q-values down to 0.03 Ä"1 no small angle scattering effect at all was observed. Compared to amorphous Ni80P20 this means that apparently no small regions exits in amorphous Ni63Nb37. For 0.008Ä"1 < Q < 0.03Ä-1, corresponding to correlation lengths between 800 and 200Ä, however, Scc and SN N increase with almost constant slope of about 3.6 in the log S(^) — log Q presentation. 
  Reference    Z. Naturforsch. 43a, 1061—1064 (1988); received September 17 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1061.pdf 
 Identifier    ZNA-1988-43a-1061 
 Volume    43 
171Author    Shipra Baluja, Akira Endoh, Isao OkadaRequires cookie*
 Title    S e lf  
 Abstract    E x c h a n g e V e lo c itie s in M o lte n E q u im o la r L i(C l, B r) P r e d ic tin g a n A n io n C h e m la E ffe c t A molecular dynamics simulation of an equimolar mixture of LiCl and LiBr melts has been performed at about 1000 K to evaluate the self-exchange velocities (SE V). The SEV of L i B r " pairs is greater than that of Li+-Cl~ pairs. Therefore in this mixture the mobility of Br ions may be greater than that of CP ions, that is, an "anion Chemla effect" may occur. For comparison, MD simulations of pure LiCl and LiBr melts have also been performed. 
  Reference    Z. Naturforsch. 43a, 1065—1071 (1988); received September 25 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1065.pdf 
 Identifier    ZNA-1988-43a-1065 
 Volume    43 
172Author    B. Vassilikou-Dova, G. LehmannRequires cookie*
 Title     
 Abstract    Chemical shift anisotropics of 205T1 and 207Pb in TlPbI3 from the literature are shown to be determined by the distortions of the MI" coordination polyhedra. Application of the superposition model results in very good agreement with the patterns calculated from crystal structure data with an exponent f = 24 for the dependence on bond distance and intrinsic shift parameters of —83.5 and — 600 ppm/distortion for 205T1 and 20"Pb resp., larger than the value for 29Si in Mg2Si04. The high value for the exponent suggests that mechanisms proportional to a higher power of overlap of electron density dominate whereas purely electrostatic mechanisms are of minor importance. S u p e r p o s itio n M o d e l A n a ly s is o f N M R D a t a f o r T l P b I 3 
  Reference    Z. Naturforsch. 43a, 1072—1074 (1988); received October 25 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1072.pdf 
 Identifier    ZNA-1988-43a-1072 
 Volume    43 
173Author    J. Herdlicka, M. D. Richter, ZeidlerRequires cookie*
 Title     
 Abstract    An NMR probe head for diffusion measurements in molten salts at temperatures up to 673 K is described. The spin echo technique using pulsed magnetic field gradients was employed. Resulting self-diffusion coefficients of Na+ in molten NaNOj in the temperature range 596-670 K are compa­ red with literature data obtained by other methods. S p in E c h o S e lf-D iffu s io n M e a s u r e m e n ts in M o lte n S a lts 
  Reference    Z. Naturforsch. 43a, 1075—1082 (1988); received August 29 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1075.pdf 
 Identifier    ZNA-1988-43a-1075 
 Volume    43 
174Author    R. C. Beavis, J. Lindner, J. Grotemeyer, E. W. SchlagRequires cookie*
 Title     
 Abstract    n f r a r e d D e s o r p tio n o f N e u t r a l M o le c u le s E m b e d d e d in T r a n s p a r e n t M a tr ic e s The desorption of intact molecules by pulsed IR irradiation is shown to depend on the IR absorption of the matrix. IR transparent matrices, such as NaCl or NH4N03, increase the total yield and the shot-to-shot stability of the sample. IR absorbing matrices decrease the yield of intact molecules and increase the amount of pyrolysis products. Using semi-transparent sugar matrices with dipeptide samples, the most intense fragment, i.e. the parent molecule having lost 18 u, is suppressed. This fragment is formed by pyrolysis during IR desorption. Three other prominent fragments are caused by the UV photoionization step. The experimental results suggest that a model involving bulk stresses and strain may be necessary to explain the observations. 
  Reference    Z. Naturforsch. 43a, 1083—1090 (1988); received July 25 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1083.pdf 
 Identifier    ZNA-1988-43a-1083 
 Volume    43 
175Author    Claus Kahlert, Michael KleinRequires cookie*
 Title      
 Abstract    Nonconformal transformations, which leave the qualitative behavior of discrete dynamical sy­ stems invariant but destroy or create analyticity for the equations of motion are investigated. For linear transformations, an explicit criterion is demonstrated, which allows to check whether a map is conjugate to a complex holomorphic dynamics. 
  Reference    Z. Naturforsch. 43a, 1091—1093 (1988); received September 24 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1091.pdf 
 Identifier    ZNA-1988-43a-1091 
 Volume    43 
176Author    K. Funke, J. Hermeling, J. KümpersRequires cookie*
 Title    P art I: 3K N O , * 2 C a (N 0 3)2 at Frequencies from 100M Hz to 4 0 GHz  
 Abstract    The dynamic ionic conductivity of the molten salt 3 KNOa • 2 Ca(N03)2 has been measured at frequencies from 100 MHz to 40 GHz, at temperatures between 422 K and 478 K. Coaxial and rectangular waveguide systems have been used at 0.1 to 18 GHz and at 18 to 40 GHz, respectively. The conductivity is found to display the dispersion that is characteristic of the so-called "universal dielectric response". A similar dispersion was observed earlier at lower temperatures and frequencies. The data form arcs in the complex conductivity plane, with centers below the real axis. The modulus representation turns out to be comparatively involved and indirect, M" featuring two maxima, while the conductivity data traverse a single arc in the complex plane. The present results are interpreted in terms of a non-Debye jump-relaxation model involving only one reorientational relaxation time. This time and its temperature dependence are close to those derived from other techniques. 
  Reference    Z. Naturforsch. 43a, 1094—1102 (1988); received September 13 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1094.pdf 
 Identifier    ZNA-1988-43a-1094 
 Volume    43 
177Author    Tamura, K. Tanaka, E. Spohr, K. HeinzingerRequires cookie*
 Title     
 Abstract    An MD simulation of an 18.5molal LiCl aqueous solution was performed with the flexible Bopp-Jancsö-Heinzinger model for water, ion-water pair potentials derived from ab initio calcula­ tions and the ion-ion interactions described by a potential of Born-Mayer-Huggins (BMH) type. The comparison with a simulation of the same system, where the ion-ion interactions were described by a (12-6) Lennard-Jones-(-Coulomb potential, demonstrates that such a change affects not only the ion-ion but also the ion-water radial distribution functions significantly, and that the results with the BMH potential conform better to X-ray results. The self-diffusion coefficients for water and the ions are found to be lower by almost one order of magnitude compared with dilute solutions, in good agreement with experimental results. The spectral densities of the hindered translational motions as well as those of the librations and the internal vibrations of the water molecules have been calculated from the simulations through the corresponding velocity autocorrelation functions. S tr u c tu r a l a n d D y n a m ic a l P r o p e r tie s o f a n L iC l • 3 H 20 S o lu tio n 
  Reference    Z. Naturforsch. 43a, 1103—1110 (1988); received September 23 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1103.pdf 
 Identifier    ZNA-1988-43a-1103 
 Volume    43 
178Author    J. Haekel, H. MäderRequires cookie*
 Title     
 Abstract    e n trif u g a l D is to r tio n A n a ly s is a n d P r e s s u r e B ro a d e n in g S tu d ie s fo r /-T y p e D o u b le t T r a n s itio n s o f C y a n o a c e ty le n e -l5 N in th e M ic ro w a v e R a n g e With the help of Fourier transform spectrometers in the range from 8 GHz to 26.5 GHz, /-type doublet transitions of HCCC15N in the first excited state of the degenerate bending vibration v7, with 36 < J< 65, have been investigated. The ./-dependence of the resonance frequencies was analy­ sed to yield the doubling constant q(0) together with the correction terms q{1) and q{2) due to first and second order contributions from centrifugal distortion. For the lines in X-and Ku-band (8 GHz to 18 GHz) the self-broadening linewidth parameters rp were determined from the pressure dependence of coherence decay rates 1/T2 of the observed transient emission signals, following pulsed microwave excitation. For the lines with J — 36 and 41, foreign gas broadening in mixtures of HCCC15N with H2, D2 and He has also been studied. The experimental results are compared with theoretical predictions, based on a perturbative treatment of binary collisions. 
  Reference    Z. Naturforsch. 43a, 1111—11 (1988); received September 17 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1111.pdf 
 Identifier    ZNA-1988-43a-1111 
 Volume    43 
179Author    V. Villa, F. Fischer3, J. ThiembRequires cookie*
 Title     
 Abstract    o le k u la r e s V e rd rillu n g s v e rm ö g e n von K o h le n h y d ra t-D e riv a te n Helical Twisting Power of Carbohydrate Derivatives For the first time carbohydrate derivatives were systematically studied as doping material for a liquid crystalline phase. These compounds can exhibit a large twisting power. It may be controlled by the configurations of single chiral centers. Thus, a series of phenomena are realized in the cholesteric phase such as helix inversion, large or small temperature dependencies of the pitch, as well as broad blue phases. Durch Zugabe einer chiralen, löslichen Substanz zu einer nematischen Phase läßt sich die cholesterische Phase erzeugen [1], Neben neu synthetisierten Ver­ bindungen wurden auch zahlreiche Naturstoffe, vor­ nehmlich Isoprenoide eingesetzt. Kohlenhydratderi-vate wurden dagegen vermutlich aufgrund ihrer er­ heblichen Polarität bisher nicht in Betracht gezogen. Diese chemisch robusten und leicht zugänglichen Ver­ bindungen erscheinen ideal geeignet zu sein, da sich mit ihnen in einmaliger Weise alle stereochemischen Möglichkeiten realisieren lassen. Zur Überprüfung der Eignung von Kohlenhydrat-Derivaten als chirale Zusätze zu nematischen Phasen wurden 22 Mischungen untersucht. Als Wirtssubstanz diente jeweils 4-n-Butyloxy-phenyl-4'-n-hexyloxybenzoat (1, ZLI 1792). Als chirale Zusätze wurden gewählt (s. Tab. 1): 
  Reference    Z. Naturforsch. 43a, 1119—1125 (1988); eingegangen am 30. September 1988 
  Published    1988 
  Keywords    Helical twisting power, carbohydrates, induced cholesteric phase, diastereomers, liquid crystals 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1119.pdf 
 Identifier    ZNA-1988-43a-1119 
 Volume    43 
180Author    Hyoung-Ryun Park, Guozheng Li, Nikola GetoffRequires cookie*
 Title     
 Abstract    h o to in d u c e d C O -R e d u c tio n in A q u e o u s S u s p e n s io n o f n -T iO z Ti02-suspension as well as Ti02-colloide in aqueous solutions are acting as catalyst for trans­ forming CO into formaldehyde under illumination with uv-light. The yield of formaldehyde was studied as a function of pH (range: 1-7) and of the n-Ti02 content in the suspension at pH 2. Probable reaction mechanisms are presented. 
  Reference    Z. Naturforsch. 43a, 1126—1130 (1988); received October 19 1988 
  Published    1988 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-1126.pdf 
 Identifier    ZNA-1988-43a-1126 
 Volume    43 
Prev
...
6
7
8
9
10
Next