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1989 (196)
141Author    H.-P Werner, W. Grauf, J. U. Von Schütz, H. C. Wolf, H. W. Helberg, W. Kremer, A. Aumüller, S. HünigRequires cookie*
 Title     
 Abstract    o n d u c tiv ity a n d M a g n e tic P r o p e r tie s o f th e C h a r g e -T r a n s fe r C o m p le x fro m N ,N '-D ic y a n o n a p h th o q u in o n e d im im in e (D C N N I) a n d T e tra th ia fu lv a le n e (T T F) Conductivity (dc and ac), ESR-properties and proton relaxation rates of the charge transfer complex Tetrathiafulvalene N,N'-dicyanonaphthoquinonediimine in the temperature range be­ tween 300 K and 3.8 K are reported. This salt belongs to the unusual group of organic conductors, in which segregated donor and acceptor stacks are associated in a pairwise manner. The physical properties, which are compared with TTF-TCNQ, give evidence of non-stoichiometric charge transfer (g # 1). A metal like state can be identified for T> 70 K, as is seen from the weak temper­ ature dependence of the conductivity (an % 30 Scm-1) and the susceptibility (yrl ^ 7.5 ■ 10~4 emu/ mole) and from the Korringa like temperature dependence of the proton relaxation rates. The drop of the susceptibility at Tc ^ 70 K and the activated temperature dependence of the conductivity for T < 70 K are explained by a metal-to-semiconductor transition. 
  Reference    Z. Naturforsch. 44a, 825—832 (1989); received July 17 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0825 
 Volume    44 
142Author    -U Grabow, H. Ehrlichmann, H. DreizlerRequires cookie*
 Title      
 Abstract    We reinvestigated the rotational spectra of morpholine and N-deutero morpholine with the higher precision of microwave Fourier transform spectroscopy. The rotational, centrifugal, and nitrogen quadrupole coupling constants were improved and the deuterium quadrupole coupling constants determined. N itro g e n a n d D e u te riu m H y p e rfin e S tr u c tu r e in th e R o ta tio n a l S p e c tr u m o f M o rp h o lin e 
  Reference    Z. Naturforsch. 44a, 833 (1989); received July 18 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0833 
 Volume    44 
143Author    J.-U Ehrlichmann, H. Grabow, DreizlerRequires cookie*
 Title     
 Abstract    We present an analysis of the rotational spectra of the normal and the N-deuterated pyrrolidine measured by microwave Fourier transform spectroscopy. The quartic centrifugal distortion con­ stants and the 14N coupling constants have been determined with higher accuracy. In addition the D hyperfine structure could be analyzed. 14N -a n d D -H y p e r f in e S tr u c tu r e in th e R o ta tio n a l S p e c tru m o f P y r ro lid in e 
  Reference    Z. Naturforsch. 44a, 837—840 (1989); received July 18 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0837 
 Volume    44 
144Author    H. J. Ehrlichmann, -UH. Grabow, N. Dreizler, M. Heineking, AndolfattoRequires cookie*
 Title      
 Abstract    We reinvestigated by microwave Fourier transform spectroscopy the rotational spectra of the axial and equatorial isotopomers of piperidine and N-deutero piperidine. The rotational, centrifugal, and nitrogen quadrupole coupling constants were improved, the deuterium quadrupole coupling constants were determined. The principal coupling tensor elements for nitrogen were estimated. N itro g e n a n d D e u te riu m H y p e rfin e S tr u c tu r e in th e R o ta tio n a l S p e c tru m o f P ip e rid in e 
  Reference    Z. Naturforsch. 44a, 841 (1989); received July 18. 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0841 
 Volume    44 
145Author    N. Heineking, U. Andresen, H. DreizlerRequires cookie*
 Title      
 Abstract    The dipole moments of chloro-, bromo-, and iodoacetylene, and those of the respective deuterated species, have been accurately determined using microwave Fourier transform spectrometers equipped with Stark cells. In each case, deuteration resulted in a change of the value of the dipole moment of about 0.012 D. The results provide strong evidence that the orientation of the dipole moment vector of iodoacetylene is opposite to that of the other haloacetylenes. 
  Reference    Z. Naturforsch. 44a, 848 (1989); received July 18 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0848 
 Volume    44 
146Author    Gerhard KlagesRequires cookie*
 Title     
 Abstract    o le k ü lin te rn e D ip o lo rie n tie r u n g u n d d ie le k tr is c h e A b s o rp tio n in v e rd ü n n te r L ö s u n g bei M ik r o -u n d S u b m illim e te rw e lle n . V. A c e ty l-V e rb in d u n g e n Intramolecular Dipole Reorientation and Dielectric Loss of Microwaves and Submillimeter naves in Diluted Solution. V . Acetyle Compounds The dielectric loss of sixteen molecules, eleven with the acetyle group in aromatic bonds and five in aliphatic bonds, has been measured in very dilute solutions of cyclohexene at 20 °C. Five of these molecules are investigated in decalene solutions, too. The measurements have been made at wavenumbers in the range 0.08 to 140 cm -\ above 8 cm" 1 making use of a pumped molecular laser. They are supplemented by the data of a Fourier transform spectrometer up to 300 cm-1. All microwave spectra of loss factor e" are analysed in terms of three absorption areas using the two variable Mori formalism. On the other hand, Lorentz curves are fitted to the FIR absorption spectra of a(v). The fast relaxation process of the aliphatic compounds is suggested to be due to intramolecular reorientation of the acetyle group itself, since in acetyle cyclohexene the remaining part of the molecule is rigid. To the contrary, the acetyle group is not able to reorientate swiftly, if bounded to aromatic rings. Presumably, it is fixed by mesomeric interaction with the dipole in the plain of the ring. However, 2-methyl acetophenone and 1-acetyle naphthone show some quick dipole reorienta­ tion, which coincides with a steric hindrance of the group in entering the plain of the ring. 
  Reference    Z. Naturforsch. 44a, 853 (1989); eingegangen am 18. Juli 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0853 
 Volume    44 
147Author    HorstUwe KellerRequires cookie*
 Title      
 Abstract    Dedicated to Professor H. Wanke on the occasion of his 60th birthday Four lines of information on comets are discussed: their orbits, their relation to other bodies of the planetary system, their physical state and chemical composition, and implications of recent observations of the nucleus of comet Halley. The in situ measurements during the flybys of comet Halley strongly support the assumption that comets are members of the solar system and were created during its formation. The region (heliocentric distance) of their formation is, however, still difficult to assess. The size, shape, and topography of the cometary nucleus suggest that it was formed from relatively large subnuclei in a region of the primordial solar nebula where relative velocities were sufficiently small. There are indications that some of the interplanetary dust particles in the Earth atmosphre may originate from comets. 
  Reference    Z. Naturforsch. 44a, 867—876 (1989); received June 27 1989 
  Published    1989 
  Keywords    Comets, origin of comets, cometary nucleus, comet Halley, cometary composition, cometary dust 
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 Identifier    ZNA-1989-44a-0867 
 Volume    44 
148Author    H. FechtigRequires cookie*
 Title      
 Abstract    Dedicated to Heinrich Wanke on the occasion of his 60 th birthday Properties of cometary dust particles are better known since the space missions to Comet Halley. Their properties (densities, atomic composition) are compared with relevant observations from lunar microcraters and in-situ experiments. At 1 AU in the eliptic, 2/3 of the dust grains are normal density particles, presumably of asteroidal origin and irregularly shaped, while the remaining 1/3 are low density particles, presumably of cometary origin, but due to solar irradiation in a processed state (corresponding to "Brownlee"-particles). Beyond the asteroidal belt only black cometary dust grains are observed which have recently been released from comet nuclei orbiting on highly eccentric trajectories. 
  Reference    Z. Naturforsch. 44a, 877 (1989); received May 16 1989 
  Published    1989 
  Keywords    Cometary dust, Core-mantle particles, Porous aggregates, Eccentric orbits, Asteroidal dust 
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 Identifier    ZNA-1989-44a-0877 
 Volume    44 
149Author    MichaelJ. DrakeRequires cookie*
 Title      
 Abstract    Dedicated to Heinrich Wanke on the occasion of his 60th birthday Theories of the formation of the Earth strongly suggest that the Earth should have been substan­ tially molten during and immediately after accretion. Estimates of the composition of the upper mantle indicate that many elements are present in chondritic ratios. Experimental measurements of element partition coefficients show that segregation of perovskite, majorite garnet, or olivine would fractionate the ratios of these elements away from chondritic values. The implication of these geochemical observations is that the Earth did not undergo extensive fractionation during and immediately following accretion. One possibility is that the Earth did not become substantially molten. Alternatively, if the Earth was indeed substantially molten, then it is possible that minerals were entrained in magma and were unable to segregate. In the former case, the accretional process must have delivered gravitational potential energy more slowly than current theory predicts, and an origin of the Moon in a giant impact would be unlikely. In the latter case, the high Mg/Si ratio in the upper mantle of the Earth relative to most classes of chondrites would be intrinsic to the silicate portion of the Earth. Unless significant amounts of Si exist in the core, the high Mg/Si ratio is a bulk planetary property, implying that the accretional process did not mix material between 1 AU and 2-4 AU. 
  Reference    Z. Naturforsch. 44a, 883—890 (1989); received May 16 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0883 
 Volume    44 
150Author    A. E. RingwoodRequires cookie*
 Title      
 Abstract    Dedicated to Heinrich Wanke on the occasion of his 60th birthday The early thermal state of the Earth provides important constraints on hypotheses relating to its origin and its connection with the Moon. The currently popular giant impact hypothesis of lunar origin requires the Earth's mantle to have been completely melted during the impact. Differentiation of a molten mantle would have produced strong chemical and mineralogical stratification, causing the mantle to become gravitationally stable and resistant to convective rehomogenization. The resulting composition and mineralogy of the upper mantle and primitive crust would have been dramatically different from those which have existed during the past 3.8 b. y. It is concluded that the Earth's mantle was not extensively melted at the conclusion of accretion of the planet and therefore the hypothesis that the Moon was formed by the impact of a martian-sized planetesimal on the proto-Earth is probably incorrect. Nevertheless, a wide range of geochemical evidence demonstrates the existence of a close genetic relationship between the Moon and the Earth's mantle. The key evidence relates to the processes of core formation in planetary bodies and resultant abundance patterns of siderophile elements which remain in their silicate mantles. Because of the complexity of the core formation process within a given body and the multiplicity of chemical and physical processes involved, the mantle siderophile signature is expected to be a unique characteristic. Thus, the siderophile signatures of Mars and of the eucrite parent body are quite distinct from that of the Earth's mantle. Lunar siderophile geochemistry is reviewed in detail. It is demonstrated that a large group of siderophile elements display similar abundances in the terrestrial and lunar mantles. The similarity implies that a major proportion of the material now in the Moon was derived from the Earth's mantle after core formation. This implication, however, does not require that the bulk compositions of the lunar and terrestrial mantles should be essentially identical, as is often assumed. Factors which may contribute to significant compositional differences between the two bodies within the context of a close genetic relationship are reviewed. The most promising mechanism for remov­ ing terrestrial material from the Earth's mantle arises from the impacts of a number of large (0.001 to 0.01 MF) but not giant (> 0.1 ME) planetesimals after core formation and at the terminal stage of the Earth's accretion. These impacts evaporated several times their own masses of mantle material and shock-melted considerably more. However, they did not lead to complete or extensive (e.g. > 50%) melting of the entire mantle. Impact-generated clouds of shock-melted spray and vapours were accelerated to high velocities in the presence of a primitive terrestrial atmosphere that co-rotated with the Earth. This provided an effective means of transferring angular momentum from the Earth to the ejected material which condensed to form a ring of Earth-orbiting planetesimals and moonlets. The Moon was formed by coagulation from material derived from the outer regions of this ring. Accretion of the Earth in the presence of the gases of the solar nebula and the co-rotating primitive terrestrial atmosphere may also have provided a mechanism for generating the rapid prograde spin of the proto-Earth. 
  Reference    Z. Naturforsch. 44a, 891 (1989); received June 15 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0891 
 Volume    44 
151Author    EdwardR D Scott, HortonE. NewsomRequires cookie*
 Title      
 Abstract    We review the chemical and mineralogical properties of primitive meteorites and chemical data for the Sun, Comet Halley and interplanetary dust particles. Regardless of where meteorites formed, concentrations of rock-forming elements in solar nebular solids could not have varied simply with distance from the Sun. Thus compositional differences between neighboring planets and the chemical and mineralogical diversity of chondritic asteroids may have been caused by local variations in the compositions of planetesimals, rather than transport of planetesimals over large heliocentric dis­ tances. Chemical variations were partly caused by differential transport and preferential agglomer­ ation of various presolar and solar grains and aggregates, and the production from these aggregates of diverse types of chondrules, refractory inclusions and other chondritic components in brief, local high temperature events in the nebula. These processes were just as important in controlling solar system chemistry as effects due to changes in ambient nebular temperatures and pressures. Differ­ ences between the Fe/Si ratios of the Sun, CI chondrites, interplanetary dust particles and Comet Halley suggest that planetesimals in the outer solar system had diverse relative concentrations of rock-forming elements. P l a n e t a r y C o m p o s itio n s -C lu e s fro m M e te o r ite s a n d A s te ro id s 
  Reference    Z. Naturforsch. 44a, 924—934 (1989); received July 28 1989 
  Published    1989 
  Keywords    Meteorites, chondrites, asteroids, planets, comets 
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 Identifier    ZNA-1989-44a-0924 
 Volume    44 
152Author    Masako Shima, FumitakawakabayashiRequires cookie*
 Title      
 Abstract    Dedicated to Professor Heinrich Wänke on the occasion of his 60th birthday Concentrations and isotopic ratios of noble gases are reported for nineteen Japanese chondrites. Among those, Nio (H3-4) is a solar-gas-rich meteorite. U/Th -He ages are younger than K -Ar ages for all meteorites studied. Six of the nine L-chondrites give significantly young K-Ar ages, suggesting gas loss by impact shock heating. The remaining three L-chondrites and seven of the ten H-chondrites have K-Ar ages older than 4 Ga. The L-chon-drite Nogata and the H-chondrites Numakai, Ogi and Higashi-Koen have concordant ages. Cosmic-ray exposure ages for six of the H-chondrites show clustering around the 6-Myr peak in the distribution of exposure ages, while those for the L-chondrites, ranging from 8.2 to 64 Myr, do not show clustering. Fukutomi (L4) contains trapped 36Ar in excess, 3.5 times enriched compared to the highest value so far reported for type-4 ordinary chondrites except solar-gas-rich chondrites. The 36Ar/132Xe and 84Kr/132Xe ratios fit along a mixing line between a planetary and a sub-solar (or argon-rich) component found in separates of E-chondrites [43], The Xe isotopic composition is identical with that in Abee and Kenna. The isotopic signatures suggest that this meteorite may contain mineral fragments bearing the noble gas component found in E-chondrites or ureilites. Fukutomi also contains 80Kr, 82Kr and 128Xe produced by epithermal neutron captures on 9Kr, 81Kr and 127I, respectively. From the neutron-produced Kr, the preatmospheric minimum radius is estimated to be 20 cm with an assumption of a spherical meteoroid. N o b le G a s R e c o rd o f J a p a n e s e C h o n d r ite s 
  Reference    Z. Naturforsch. 44a, 935 (1989); received August 5 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0935 
 Volume    44 
153Author    K. Fredriksson, E. Jarosewich, F. WlotzkaRequires cookie*
 Title     
 Abstract    C h a o tic C h o n d r ite B re c c ia w ith N o r m a l H -G r o u p C h e m is try Dedicated to Professor Heinrich Wänke, on the occasion of his 60th birthday. The Study Butte (SB) H-group chondrite is an accretionary, well-indurated, multicomponent breccia of exceptional complexity. It contains practically all previously described types of chondrules (in two discrete populations according to Fe/Mg and Al/Ca distributions) and fragments (including CAFs and also some which were not observed before, e.g. an "andesite"); furthermore it is gas-rich. According to currently popular definitions, it can be ascribed to petrographic type 3 based on overall texture, presence of glass in chondrules and the wide spread of pyroxene and olivine composition (PMD30), although about 2/3 have nearly constant Fa 17 (PMD4) in the normal H-range. In addition, Al and Ca in individual chondrules with normal H-olivines, Fa 16-20, are negatively correlated, as usual in chondrules from H 4.5 chondrites [3], but are positively correlated in other chondrules. Thus SB has the properties of both "equilibrated" and "unequilibrated" chondrites. However, in spite of the multitude and complexity of components, the bulk composition is that of normal H-chondrites. A great variety of multi-stage accretion and chondrule formation, break-ups, heating and compaction processes in a quasi closed system are clearly indicated; no clues to preceding nebular processes have been recognized. After the descriptive and analytical data a "Model", based upon bulk composition, for the formation of chondrules and chondrites is presented. S tu d y B u tte : 
  Reference    Z. Naturforsch. 44a, 945—962 (1989); received August 11 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0945 
 Volume    44 
154Author    K. Marti, J. S. Kim, B. Lavielle, P. Pellas, C. PerronRequires cookie*
 Title      
 Abstract    Dedicated to Heinrich Wänke on the occasion of his 60th birthday. We report xenon isotopic abundances observed in the stepwise release of noble gases in a high-purity metal separate of the Forest Vale (H4) chondrite. We identify a 244Pu-derived fission compo­ nent, due to recoils into the metal, a cosmic-ray-produced spallation component and a new trapped component (FVM; 132Xe: 134Xe: 136Xe = 3.16:1.235:1.000) which is isotopically distinct from known solar system reservoirs. We discuss several processes which might account for observed isotopic shifts and conclude that the signature of FVM xenon may provide clues regarding the origin of chondritic metal. 
  Reference    Z. Naturforsch. 44a, 963—967 (1989); received May 16 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0963 
 Volume    44 
155Author    JohnW. Larimer, ErmannoR. RambaldiRequires cookie*
 Title      
 Abstract    Dedicated to Heinrich Wänke on the occasion of his 60th birthday Metal grains from a silicate inclusion in Landes, a group IAB iron-meteorite, were separated and analyzed via IN A A for 14 siderophile elements. The same 14 elements were determined in matrix metal from Landes, 5 other IAB meteorites and three anomalous iron meteorites. Compared to the other samples and to chondritic metal, the inclusion metal is enriched in siderophile elements. In chondritic metal, the siderophile element contents are higher when Fe° is oxidized to FeO. Silicates in IAB inclusions contain little FeO, yet the metal is as rich in siderophile elements as the most oxidized chondrites. Evidently the IAB body contained its full cosmic complement of S resulting in an FeS content ~ 5 x that of ordinary chondrites. This explains the composition of the metal since sulfurization, like oxidation, reduces the available Fe°. IAB meteorites contain their full cosmic complement of other moderately volatile elements, which implies an equally high S content. A high S content significantly affects the melting and freezing of FeNi-metal. About 85% of the metal melts at the Fe-FeS eutectic (~ 960 °C), and all of the metal is molten at ~1050°C. During cooling, ~85% of the metal crystallizes with a Ni content of 6±1% between 1050c and 960'C. Besides a small depletion in elements with low melting points or chalcophile tendencies this metal is little fractionated. Bellow 960 °C, the Ni content of the metal increases until the melt is exhausted. This Ni-rich metal also becomes progressively depleted in refractory elements and enriched in volatile elements. The crystal­ lization process thus yields products that mimic the abundance and composition of group IAB meteorites. 
  Reference    Z. Naturforsch. 44a, 968—978 (1989); received July 28 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0968 
 Volume    44 
156Author    RickL. Paul, MichaelE. LipschutzRequires cookie*
 Title      
 Abstract    S o m e A n ta r c tic C a r b o n a c e o u s C h o n d r ite s : A n ta r c tic a n d N o n -A n ta r c tic M e te o r ite C o m p a ris o n s U and Zn determined by radiochemical neutron activation analysis in consortium samples of Belgica (B) 7904, Yamato (Y) 82042, Yamato 82162 and Yamato 86720 carbonaceous chondrites. These trace elements cover a wide volatility/mobility range and give unique information on thermal histories of meteorites. The results indicate the unique nature of these carbonaceous chondrites. Y-82042 proves to have the volatile element pattern of a C2 (= CM) chondrite and the petrologic characteristics of a CI (sCI) chondrite. These must be primary nebular condensation/accretion features, unaffected by post-ac-cretionary processes. The other three meteorites were thermally metamorphosed in ^2 parent regions over the 600-700 C range, at relative temperatures B-7904 < Y-82162< Y-86720. Before heating, B-7904 and Y-86720 had C2-levels of volatile elements: Y-82162 had uniquely high volatile element concentrations, at about CI-levels. The data require a new classification scheme for such chondrites. Belgica 7904 and Y-82162 and -86720 seem to be derived from one or more thermally altered carbonaceous asteroids, and their spectral characteristics should be compared with those of B-, F-, G-or T-asteroids. These results indicate substantial differences in the thermal histories of Antarctic and non-Antarctic CI and C2 chondrite populations. In reviewing all that is known about the Antarctic and non-Antarctic meteorite populations, the overwhelming weight of evidence sup­ ports the view that these populations sample different extraterrestrial source materials, differing in thermal histories. It may be that over the extended collecting period of the Antarctic ice sheet, it has sampled a considerably greater proportion of near-Earth asteroids than do current falls. 
  Reference    Z. Naturforsch. 44a, 979—987 (1989); received May 16 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0979 
 Volume    44 
157Author    G. Kurat, H. Palme, F. Brandstätter, J. HuthRequires cookie*
 Title     
 Abstract    lle n d e X e n o lith A F : U n d is tu r b e d R e c o rd o f C o n d e n s a tio n a n d A g g re g a tio n o f M a t t e r in th e S o la r N e b u la In this paper an unusual, cm-sized xenolith from the Allende meteorite is described. Xenolith Allende-AF (All-AF) is chemically similar to bulk Allende, its texture is. however, completely different. It consists mainly of highly porous silicate-rich aggregates embedded in a largely opaque matrix. Occasionally olivine-sulfide-metal aggregates and large sulfide-andradite objects are found. Chondrules are absent and grain size in matrix and aggregates is the same, quite different from normal Allende. The main mineral in All-AF is olivine (22-41 wt% FeO). low Ca-pyroxene is absent, but a variety of clinopyroxenes were encountered. Rare phases found throughout All-AF are refractory metal nuggets (Ir, Os, Ru etc.), HgS, and Ca-phosphate. Associated with sulfide-andradite objects are native-Cu, Ti-magnetite, perovskite, barite, and calcite. Morphology, crystalline state and minor element contents of olivine strongly suggest an origin by condensation from a gas. Al20 3-contents, for example, range from 0.5 to 3% and Cr20 3-con-tents reach 2.5%. Texture of All-AF indicates that condensation of olivine continued during formation of aggre­ gates. Relictic low-Fe aluminous diopsides suggest that olivine was initially FeO-poor. Before final accretion into a solid rock exchange reactions between condensed phases and an (increasingly oxidized) vapor established the high FeO-content of olivine. A similar process led to sulfurization of most of the original metal. The exotic sulfide-andradite objects are probably alteration products of unusual, metal-rich calcium-aluminium-rich inclusions. It appears that All-AF has preserved a unique record of condensation, hierarchical aggregation, and metasomatic exchange reactions in the solar nebula. 
  Reference    Z. Naturforsch. 44a, 988—1004 (1989); received August 14 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-0988 
 Volume    44 
158Author    H. Palme, G. Kurat, B. Spettel, A. BurgheleRequires cookie*
 Title     
 Abstract    h e m ic a l C o m p o s itio n o f a n U n u s u a l X e n o lith o f th e A lle n d e M e te o r ite Dedicated to Prof. Heinrich Wänke on the occasion of his 60th birthday The chemical composition of an unusual xenolith (All-AF) from the Allende meteorite was determined by neutron activation and x-ray fluorescence analyses. The xenolith is similar in bulk composition to Allende, but has large excesses in some moderately volatile trace elements, such as Na, K, Au, Sb etc. Some of these elements show considerable variations in other components of Allende, suggesting inhomogeneous distribution in Allende. However, elements of higher volatility, such as Zn and Se have concentrations typical of bulk Allende and other type 3 carbonaceous chondrites. Therefore, All-AF must have formed from the same reservoir as bulk Allende. All-AF has uniform grain size and does not, and did never, contain chondrules. The low content of volatile elements, therefore cannot be ascribed to loss of volatiles during the chondrule forming process. It is a characteristic of the Allende reservoir. The chemical composition of related dark inclusions (DIs) in Allende is different from All-AF. Dark inclusions may have formed by separation of fine grained material in the early solar nebula while All-AF resembles bulk Allende material that was never subject to chondrule formation. Both, dark inclusions and All-AF have oxygen isotopic compositions which plot at the upper end of the ö lsO vs. (5170 correlation, suggesting extensive oxygen exchange with ambient gas. 
  Reference    Z. Naturforsch. 44a, 1005—1014 (1989); received August 5 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1005 
 Volume    44 
159Author    S. Jovanovic, G. W. ReedRequires cookie*
 Title     
 Abstract    h e r m a l E q u ilib ra tio n H is to r y a n d N o b le M e ta l (R e)d is tr ib u tio n s in M in e r a l P h a s e s * Dedicated to Heinrich Wänke on the occasion of his 60th birthday Ru, Os, and Ir in Allende whole rock and coarse grained CAIs are present in amounts up to 80% in phases other than inert Pt-metal alloys. Selective chemical dissolution was used to dissolve sulfides by ascorbic acid-H20 2 and metal (NiFe)-silicate-oxides by HF/HC1. Carbon-rich, spinel-chromite residues were left from the demineralization procedures and scavenged inert material such as Pt-metal alloy particles. The Pt-metal contents in sulfide phases from the Allende whole rock sample and the total Pt-metal contents of the CAI samples give near-cosmic to cosmic interelement ratios. Pt-metal ratios in all the other separated phases are fractionated. The Fe/Co ratio in the carbon-rich residue from the CAI and in the sulfide fractions from Allende whole rock and CAI-bulk samples is 230, the same as is reported for sulfides in the Zelda fremdlinge. A scheme for mixing aggregates from different regions of "Allende-space" in the solar nebula is proposed to account for the Pt-metal and Fe-Co distributions observed here. Chemical alteration processes in condensed material may have required moderate to high temper­ atures in the nebula to have caused the interelement relationships observed. We determined the final equilibration temperatures to which components of Allende were subjected. Temperatures are based on the distribution of Hg between labile (low T) and retentive (high T) sites in silicate rocks. Compositionally and texturally different CAI clasts and the matrix associated with one of the clasts were equilibrated at 778-975 C C. The averaged thermal equilibration temperature for seven bulk (matrix) Allende samples reported previously was 670 °C. The final thermal equilibrations of the clasts probably occurred before Allende was assembled. A lle n d e W h o le R o c k a n d C A I S tu d ie s : 
  Reference    Z. Naturforsch. 44a, 1015—1027 (1989); received June 30 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1015 
 Volume    44 
160Author    W. Kerner, D. Pfirsch, H. WeitznerRequires cookie*
 Title     
 Abstract    n th e V a lid ity o f M a c r o s c o p ic M o d e ls The validity of macroscopic models in the limit of large mean-free path is examined by solving a one-dimensional model equation, where the term v Vfx is retained in the kinetic equation. A standard thirteen-moments approximation yields accurate results in all collisionality regimes if the fluid velocity is sufficiently small. In contrast, the Chapman-Enskog scheme is only accurate in the collision-dominated regime. 
  Reference    Z. Naturforsch. 44a, 1029—1040 (1989); received July 7 1989 
  Published    1989 
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 Identifier    ZNA-1989-44a-1029 
 Volume    44 
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