bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solar wind noble gases and nitrogen in metal from lunar soil 68501
Authors: Becker Richard H. , Pepin Robert O. 
Published: June 2012

Abstract Noble gases and N were analyzed in handpicked metal separates from lunar soil 68501 by a combination of step‐wise combustions and pyrolyses. Helium and Ne were found to be unfractionated with respect to one another when normalized to solar abundances, for both the bulk sample and for all but the highest temperature steps. However, they are depleted relative to Ar, Kr and Xe by at least a factor of 5. The heavier gases exhibit mass‐dependent fractionation relative to solar system abundance ratios but appear unfractionated, both in the bulk metal and in early temperature steps, when compared to relative abundances derived from lunar ilmenite 71501 by chemical etching, recently put forward as representing the abundance ratios in solar wind. Estimates of the contribution of solar energetic particles (SEP) to the originally implanted solar gases, derived from a basic interpretation of He and Ne isotopes, yield values of about 10%. Analysis of the Ar isotopes requires a minimum of 20% SEP, and Kr isotopes, using our preferred composition for solar wind Kr, yield a result that overlaps both of these values. It is possible to reconcile the data from these gases if significant loss of solar wind Ar, Kr and presumably Xe has occurred relative to the SEP component, most likely by erosive processes that are mass independent, although mass‐dependent losses (Ar > Kr > Xe) cannot be excluded. If such losses did occur, the SEP contribution to the solar implanted gases must have been no more than a few percent.Nitrogen is a mixture of indigenous meteoritic N, whose isotopic composition is inferred to be relatively light, and implanted solar N, which has probably undergone diffusive redistribution and fractionation. If the heavy noble gases have not undergone diffusive loss, then N/Ar in the solar wind can be inferred to be at least several times the accepted solar ratio. The solar wind N appears, even after correction for fractionation effects, to have a minimum δ15N value ≥+150‰ and a more probable value ≥+200‰.
Noble gases in presolar diamonds II: Component abundances reflect thermal processing
Authors: Huss Gary R. , Lewis Roy S. 
Published: June 2012

Abstract— Using the isotopic compositions derived in Huss and Lewis, 1994a (Paper I), abundances of the P3, HL, and P6 noble‐gas components were determined for 15 diamond separates from primitive chondrites of 8 chondrite classes. Within a meteorite class, the relative abundances of these components correlate with the petrologic subtype of the host meteorite, indicating that metamorphism is primarily responsible for the variations. Relative abundances of P3, HL, and P6 among diamond samples can be understood in terms of thermal processing of a single mixture of diamonds like those now found in CI and CM2 chondrites. With relatively gentle heating, primitive diamonds first lose their low‐temperature P3 gases and a “labile” fraction of the HL component. Mass loss associated with release of these components produces an increase in the HL and P6 content of the remaining diamond relative to unprocessed diamond. Higher temperatures initiate destruction of the main HL carrier, while the HL content of the surviving diamonds remains essentially constant. At the same time, the P6 carrier begins to preferentially lose light noble gases. Meteorites that have experienced metamorphic temperatures ≳650 °C have lost essentially all of their presolar diamond through chemical reactions with surrounding minerals.The P3 abundance seems to be a function only of the maximum temperature experienced by the diamonds and thus is independent of the nature of the surrounding environment. If all classes inherited the same mixture of primitive diamonds, then P3 abundances would tie together the metamorphic scales in different meteorite classes. However, if the P3 abundance indicates a higher temperature than do other thermometers applicable to the host meteorite, then the P3 abundance may contain information about heating prior to accretion. Diamonds in the least metamorphosed EH, CV, and CO chondrites seem to carry a record of pre‐accretionary thermal processing.
Origin and diagenesis of K/T impact spherules—From Haiti to Wyoming and beyond
Authors: Bohor Bruce F. , Glass Billy P. 
Published: June 2012

Abstract— Impact spherules in Cretaceous/Tertiary (K/T) boundary clays and claystones consist of two types; each type is confined to its own separate layer of the boundary couplet in the Western Hemisphere. The form and composition of each of the spherule types result from its own unique mode of origin during the K/T event. Type 1 splash‐form spherules occur only in the melt‐ejecta (basal) layer of the K/T couplet. This layer was deposited from a ballistic ejecta curtain composed of melt‐glass droplets transported mostly within the atmosphere. In contrast, Type 2 spherules are accreted, partially crystalline, spheroidal bodies that formed by condensation of vaporized bolide and target‐rock materials in an expanding fireball cloud, from which they settled out of buoyant suspension to form the fireball layer. Dendritic and skeletal Ni‐rich spinel crystals are unique to these Type 2 spherules in the fireball layer.Compositions of relict glasses found in Type 1 K/T spherules from Haiti indicate that they were derived from intermediate silicic target rocks. These melt‐glass droplets were deposited into an aqueous environment at both continental and marine sites. We propose that the surfaces of the hot melt droplets hydrated rapidly in water and that these hydrated glass rims then altered to palagonite. Subsequent alteration of the palagonite rims to smectite, glauconite, chlorite, kaolinite, or goyazite occurred later during various modes of progressive diagenesis, accompanied by dissolution of some of the glass cores in spherules from continental sections and from marine sections that were subsequently raised above sea level. In many of the nonmarine sections in the Western Interior, the glass cores altered to kaolinite instead of dissolving.Directly comparable spherule morphologies (splash forms), textural features of the altered shells, and scalloping and grooving of relict glass cores or secondary casts demonstrate that the Haitian and Wyoming spherules are equivalent altered Type 1 melt‐droplet bodies. The spherules at both locations were deposited in a melt‐ejecta layer as part of the K/T impact event.Previously, two types of relict impact glasses had been identified in the Haitian spherule beds: black glass of andesitic composition and high‐Ca yellow glass with an unusually high S content. Most workers agree that the latter probably formed by impact melting and mixing of surficial carbonate (and minor anhydrite) rocks with the more deeply‐buried crystalline parent rocks of the black glasses. However, some workers have suggested that an intermediate compositional gap exists between the two groups of glasses, implying a different origin than simple mixing of end members during impact. We report glass compositional analyses with values extending throughout this intermediate range, lending support to the impact‐mixing model. Inclusions of CaSO4 found by us in relict yellow glasses further support this model.
Lunar behaviour of boron contrasted with the terrestrial boron cycle
Authors: Shaw Denis M. 
Published: June 2012

Abstract— Fifty‐eight lunar rocks have been analysed by prompt gamma neutron activation for B, Gd and Sm. The data were interpreted together with published analyses for Li and other elements.The behaviour of B in lunar rocks is virtually identical to that of Sm, Gd, Li and the other incompatible LIL (Large Ion Lithophile) and HFS (High Field Strength) elements, collectively known as the KREEP component. To a first approximation, the distribution of B concentrations in all lunar rocks can be described as a two‐component mixture of KREEP, with ∼32 ppm, and B‐free mare basalts and anorthositic rocks.The lunar B abundance, estimated from correlations with other KREEP elements, is ∼0.14 ppm.Alpha‐track images of the analysed lunar rocks were made from thin sections specially prepared to avoid contamination from terrestrial B. They provided surprising evidence that the distributions of B and Li within individual rocks fall into four categories: (1) substitution in mineral structures; (2) in irregular minute particles, disseminated through the rock with no apparent connection with mineralogy; (3) as aggregate properties of rock fragments, acquired prior to assembly in a breccia; and, (4) as aggregate properties of a breccia matrix, distinct from unaffected clasts.Only category (1) is encountered in terrestrial rocks. Categories (2), (3) and (4) become progressively more important as the abundance of KREEP components increases, and it is concluded that the alpha‐track images probably show the localisation of not only B and Li but all the KREEP elements. In terrestrial rocks, such textures could be understood in terms of successive episodes of permeation by solutions followed by brecciation, then cementation. It is difficult to adapt such a mechanism to a dry Moon, with brecciation imposed by impact melting.The linear correlation of lunar B and Gd contrasts strongly with the relationship seen in terrestrial rocks, where the presence of water creates a terrestrial B cycle quite different from that of Gd and other lunar incompatible elements.
40Ar/39Ar dating of the Araguainha impact structure, Mato Grosso, Brazil
Authors: Hammerschmidt Konrad , VON Engelhardt WOLF 
Published: June 2012

Abstract— Pursuing the exploration of the Araguainha impact structure (Engelhardt et al., 1992), we present 40Ar/39Ar ages (1) of biotite samples from the granite, which forms the central uplift of the structure, and (2) of a melt rock, formed by the impact.Total degassing ages of biotites from granite samples range from 326 to 481 Ma. The variation is explained by Ar losses due to the oxidation of divalent Fe and by removal of K. The K loss depends on the time that the granite was exposed to weathering at particular outcrops. The oldest age of the least oxidized biotite from a granite sample, collected at a site most recently exposed, signifies that the ascending granite passed the 300° isotherm earlier than 481 Ma ago. Early Devonian Furnas sandstones, the oldest sediments exposed by the impact, were deposited on this granite basement 410–396 Ma ago.The 40Ar/39Ar analyses of two size fractions of an impact melt rock, resulting in plateau ages of 245.5 ± 3.5 Ma and 243.3 ± 3.0 Ma, respectively, indicate that the Araguainha impact occurred close to the Permian‐Triassic boundary.
Stable nickel isotopes and cosmogenic beryllium‐10 and aluminum‐26 in metallic spheroids from Meteor Crater, Arizona
Authors: Xue S. , Herzog G. F. , Hall G. S. , Klein J. , Middleton R. , Juenemann D. 
Published: June 2012

Abstract— The isotopic abundances of Ni in 17 metallic spheroids from Meteor Crater, Arizona, were determined by inductively coupled plasma mass spectrometry (ICP‐MS). Sixteen spheroids have normal isotopic abundances. A 17th shows a marginally detectable mass fractionation of 0.40 ± 0.14 %/AMU in favor of the heavier isotopes. The general absence of mass fractionation indicates that open system evaporation caused little loss of Ni.Variable activities of the cosmogenic radionuclides 10Be and 26Al were measured by accelerator mass spectrometry in separate suites of spheroids. Activities of 26Al in most samples and of 10Be in metal cores separated from spheroids indicate that they either (1) come from greater depths in the parent meteoroid than do hand specimens, or (2) lost Al and Be during the process of spheroid formation. One individual spheroid has 10Be and 26Al activities comparable to those of bulk specimens. This result suggests that spheroid formation may occasionally include material from the outermost meter or so of the impactor. Relatively high activities of 10Be, ∼3 dpm/kg, in the siliceous shells of Canyon Diablo spheroids very likely have a meteoric origin.
Isotope source table for a 25 M⊙ supernova
Authors: Meyer Bradley S. , Weaver Thomas A. , Woosley Stanford E. 
Published: June 2012

Abstract— We present a table giving the yields of 103 isotopes in eight distinct zones in the ejecta from the explosion of a 25 M star. Each zone in the ejecta is distinct isotopically due to the evolution and explosion of the star. Thus the table not only gives the yields of isotopes in the different zones of the ejecta but also provides information about the chemical environments in which each isotope is injected into the interstellar medium.The table is a summary of the nuclear yields from a single numerical model of the explosion of a massive star. The yields from a real supernova will vary from those in this table because of uncertainties in the input physics to the numerical model and because the real star may differ in mass, mass‐loss rate, or metallicity from the modeled star. We argue that these uncertainties and variations, for the most part, will not change the direction of the largest isotopic effects in the different zones of the ejecta. This means that the table is quite generally applicable as a guide to understanding the ejecta of supernovae and as a characterization of possible chemical environments in which isotopes are injected into the interstellar medium.
Nierite (Si3N4), a new mineral from ordinary and enstatite chondrites
Authors: Lee Martin R. , Russell Sara S. , Arden John W. , Pillinger C. T. 
Published: June 2012

Abstract— Nierite (Si3N4) is a new mineral that has been found in perchloric acid‐resistant residues of three ordinary chondrites (Adrar 003 [LL3.2], Inman [L3.4] and Tieschitz [H3.6]) and one enstatite chondrite (Indarch [EH4]). This mineral occurs as very small (∼2 × 0.4 μm) lath‐shaped grains, which have been characterised by transmission electron microscopy. The d‐spacings of nierite are, within errors, comparable to those of synthetic α‐Si3N4, which has trigonal symmetry (P31c, a = 0.7758 nm, c = 0.5623 nm, V = 0.2931 nm3 Z = 4). Energy‐dispersive x‐ray analyses confirm that nierite is a Si‐ and N‐rich mineral. A few nierite crystals in the Indarch, Inman and Tieschitz residues are intergrown with whiskers of another nitride. Only two crystals of this additional nitride were found that were of sufficient size to give electron diffraction patterns uncontaminated by nierite reflections. The d‐spacings of this second nitride are comparable to those of β‐Si3N4, the hexagonal polymorph of synthetic Si3N4.The majority of nierite crystals in Indarch are interpreted to have formed by exsolution of Si and N from kamacite, perryite and schreibersite during parent‐body metamorphism. Some grains have evidence for two discrete episodes of nierite crystallization. The origin of nierite in Adrar 003, Inman and Tieschitz is not known, but formation during exsolution is again possible. The petrographic relationships between nierite and β‐Si3N4 in Indarch, Inman and Tieschitz suggests that the β‐Si3N4 whiskers predated nierite and acted as a seed on which nierite crystals later nucleated. The nierite/β‐Si3N4 ratio in ordinary chondrites is controlled by their metamorphic grade and possibly also their oxidation state.
Sulfur and selenium in chondritic meteorites
Authors: Dreibus G. , Palme H. , Spettel B. , Zipfel J. , Wänke H. 
Published: June 2012

Abstract— We report here new analyses of S and Se in carbonaceous chondrites (2 CIs, 11 CMs, 6 CO3s, 7 CV3s, 2 C4s, 4 CRs, and 1 CH), 2 rumurutiites, ordinary chondrites (2 Hs, 2 Ls, and 1 LL), 3 anomalous chondrites, 3 acapulcoites, 3 lodranites, and in silicate inclusions of the Landes IAB iron meteorite. To avoid problems from inhomogeneous distribution of sulfides, the same samples that had been analysed for Se by INAA were analysed for S using a Leybold Heraeus Carbon and Sulfur Analyser (CSA 2002).With the measured CI contents of 5.41% S and 21.4 ppm Se a CI S/Se ratio of 2540 is obtained. A nearly identical S/Se ratio of 2560 ± 150 is found for carbonaceous chondrites (average of falls). The average ratio of all meteorite falls analysed in this study was 2500 ± 270. These data suggest that the new S content of Orgueil with 5.41% provides a reliable estimate for the average Solar System. The new solar system abundance of S of 4.62 × 105 (atoms/106 Si) is in good agreement with the solar photospheric abundance of 7.21 (log (a(H)) = E12) (Anders and Grevesse, 1989).Among the 50 analysed meteorites, 24 were finds from hot (Australia, Africa) and cold (Antarctica) deserts. Weathering effects in the carbonaceous chondrites and in one lodranite from the hot deserts resulted in losses of S, Se, Na and occasionally Ni. Sulfur is apparently more affected by weathering than Se. No losses were observed in ordinary chondrite finds and in meteorites collected in the Antarctica, except for the obvious loss of Na in the CM‐chondrite Y 74662.The low S‐content of 0.096% in Gibson, a lodranite, is probably not representative of this group of meteorites. Gibson is a find from the Australian desert and has lost S and also Se by weathering. Two other lodranites, finds from Antarctica, have about 2% S.
Noble gases and strontium isotopes in the unique meteorite Divnoe
Authors: Shukolyukov Yu. A. , Assonov S. S. , Smoliar M. I. , Kolesnikov E. M. 
Published: June 2012

Abstract— We present an isotope study of noble gases in Divnoe, an anomalous meteorite, and also Rb‐Sr and K‐Ar dating of this meteorite. The relatively young Rb‐Sr age obtained (3.39 Ga) seems doubtful and, most probably, results from weathering or contamination. The ancient K‐Ar age (4.67+0.20–0.40), together with clear excess of 129Xe, allows the suggestion of very early formation of the Divnoe meteorite.Concentrations and isotope ratios of noble gases in Divnoe are: 17.9 ≤ 3He ≤ 29.0 × 10−8; 20Ne = 6.22 × 10−8; 2.44 ≤ 36Ar ≤ 5.10 × 10−8; 130Xe = 41.3 × 10−12 cm3/g; 0.079 ≤ 3He/4He ≤ 0.193; 20Ne/22Ne = 0.860; 21Ne/22Ne = 0.927; 3.47 ≤ 40Ar/36Ar ≤ 9.47; 2.22 ≤ 36Ar/38Ar ≤ 3.27; 129Xe/132Xe = 1.09. The exposure age calculated from cosmogenic 3He, 21Ne, and 38Ar is 17.9 ± 0.9 Ma.On the basis of the isotope data for the noble gases and O, and abundances of K, Rb, and Sr, an attempt was made to estimate the relationship of Divnoe to other meteorite types. The O‐isotope characteristics of Divnoe are clearly distinct from those of ordinary chondrites, acapulcoites/lodranites, and SNC meteorites (Petaev et al., 1994, Clayton, 1993). In plots of 136Xe vs. 129Xe/130Xe, the Divnoe data fall outside of the data fields for carbonaceous and enstatite chondrites. The light noble gas data, especially the 40Ar/38Ar ratio, and the 40Ar, 38Ar, 3He, and 4He contents of Divnoe differ significantly from those of all meteorite types except diogenites. The K, Rb, and Sr abundances in Divnoe are substantially lower than in most other meteorites. In the concentrations of these elements, as well as in the REE pattern, the Divnoe meteorite is similar only to diogenites. Divnoe probably should be treated as a restite remaining after partial melting of the chondritic mantle of a parent asteroid body.
Carbon, nitrogen and hydrogen in Saharan chondrites: The importance of weathering
Authors: Ash R. D. , Pillinger C. T. 
Published: June 2012

Abstract— The Sahara Desert is a region of high diurnal temperature variation and sporadic rainfall that has recently yielded over 450 meteorites. Eighteen of these Saharan samples are carbonaceous chondrites, of which we have analysed 17 for C content and isotopic composition. Ten of the 18 are paired CR chondrites, of which four have also had N and H contents and compositions determined. A primitive ordinary chondrite (L/LL3.2) found in the region has also been analysed for C, N and H contents and isotopic composition.Saharan samples contain between 21% and 45% of the light elements of their non‐Saharan counterparts. Paired Saharan samples show a greater heterogeneity in both C content and isotopic composition than multiple analyses of non‐Saharan samples.The cause of the observed isotopic and abundance effects is due to the hot desert weathering processes experienced by these samples. Peak temperatures of meteorites on the desert floor may be in excess of 100 °C, leading to low‐temperature hydrous pyrolysis and oxidation reactions, liberating volatile organics and CO2. This may also cause the remaining material to become partially solubilised and ultimately lost during rainfall. The low δD of the CR and ordinary chondrites can be attributed to the destruction and loss of organic material through dehydrogenation and exchange reactions on the desert surface. The increased 13C abundance suggests that the less tightly bound C from the macromolecular organic material is isotopically lighter than the remaining C. Carbon contents and isotopic compositions are also affected by the addition of terrestrial calcitic evaporite deposits, up to 10,000 ppm carbonate has been measured, with a δ13C of between 0 and −10%0.
Closure of non-healing chronic ulcer in Klippel–Trenaunay syndrome using low-level laser therapy
Authors: Dixit Snehil , Maiya Arun G , Umakanth Shashikiran , Shastry Barkur A 
Published: June 2012

A 69-year-old man diagnosed with Klippel–Trenaunay syndrome (KTS) reported to the physiotherapy outpatient clinic with the complaint of a non-healing ulcer over the right medial malleolus, for a 6-month duration, that was non-granulating and had moderate pus discharge with foul odour at initial assessment. There was a decrease in scores of the Pressure Ulcer Scale of Healing, a significant increase in granulation tissue, a decrease in the amount of discharge and foul odour along with complete closure of the chronic wound after irradiation with a light-emitting diode (LED). This is a novel case study analysing the possible effect of a helium–neon laser and LEDs on non-healing chronic ulcers associated with KTS, where the complete closure of the chronic ulcer that was initially not responsive to standard medical care was observed.
TRANSPORTATION NETWORK STABILITY: A CASE STUDY OF CITY TRANSIT
Authors: BERCHE BERTRAND , FERBER CHRISTIAN VON , HOLOVATCH TARAS , HOLOVATCH YURIJ 
Published: June 2012

The goals of this paper are to present criteria, that allow to a priori quantify the attack stability of real world correlated networks of finite size and to check how these criteria correspond to analytic results available for infinite uncorrelated networks. As a case study, we consider public transportation networks (PTN) of several major cities of the world. To analyze their resilience against attacks, either the network nodes or edges are removed in specific sequences (attack scenarios). During each scenario the size S(c) of the largest remaining network component is observed as function of the removed share c of nodes or edges. To quantify the PTN stability with respect to different attack scenarios we use the area below the curve described by S(c) for c ∈ [0, 1] recently introduced (Schneider, C. M. et al. [PNAS 108 (2011) 3838]) as a numerical measure of network robustness. This measure captures the network reaction over the whole attack sequence. We present results of the analysis of PTN stability against node and link-targeted attacks.