bluuebunny/crossref_metadata_2025 huggingface dataset:
Noble gases in metal and schreibersite of the Acuña (IIIAB) iron meteorite
Authors: Matsuda Jun‐ichi , Nagao Keisuke , Kurat Gero
Published: August 2012

Abstract— We measured abundances and isotopic compositions of noble gases in metal and schreibersite of the Acuña (IIIAB) iron meteorite. The concentrations of noble gases in Acuña metal are very low compared to those reported so far for other iron meteorites. The isotopic ratios of He, Ne and Ar indicate that they are mostly of cosmogenic origin. Cosmogenic components are even present in Kr and Xe, which could not have been produced from Fe, Ni and P and are probably due to the spallation of trace elements of higher masses. The high 4He/21Ne ratio of 420 in Acuña metal indicates that the samples were at a deep position within a very large meteoroid. The exposure ages of Acuña were estimated to be 50–200 Ma from 3He, 21Ne and 38Ar abundances and by utilizing the diagrams of production rates vs. the 4He/21Ne ratio based on the Signer‐Nier model. The low exposure age of Acuña may indicate a history different from that of other IIIAB irons whose exposure ages cluster at ∼670 Ma. Otherwise, Acuña may be one of the samples with the low production rate, which can not be estimated from the diagrams of the Signer‐Nier model.
Exposure history of the Torino meteorite
Authors: Wieler R. , Graf Th. , Signer P. , Vogt S. , Herzog G. F. , Tuniz C. , Fink D. , Fifield L. K. , Klein J. , Middleton R. , Jull A. J. T. , Pellas P. , Masarik J. , Dreibus G.
Published: August 2012

Abstract— We determined He, Ne, Ar, 10Be, 26Al, 36Cl, and 14C concentrations, as well as cosmic‐ray track densities and halogen concentrations in different specimens of the H6 chondrite Torino, in order to constrain its exposure history to cosmic radiation. The Torino meteoroid had a radius of ∼20 cm and travelled in interplanetary space for 2.5–10 Ma. Earlier, Torino was part of a larger body. The smallest possible precursor had a radius of 55 cm and a journey through space longer than ∼65 Ma. If the first‐stage exposure took place in a body with a radius of >3 m or in the parent asteroid, then it lasted nearly 300 Ma. The example of Torino shows that it is easy to underestimate first‐stage exposure ages when constructing two‐stage histories.
The Kaidun meteorite: Composition and origin of inclusions in the metal of an enstatite chondrite clast
Authors: IVANOV Andrei V. , MACPHERSON Glenn J. , ZOLENSKY Michael E. , KONONKOVA Nataliya N. , MIGDISOVA Lyudmila F.
Published: August 2012

Abstract— Metal nodules are one of the major textural components of Kaidun sample #01.3.06 EH3‐4. In terms of structure, the nodules are of three types: (1) globular, (2) zoned with a massive core and globular mantle, and (3) nodules with no internal structure. The size and composition of the globules in the nodules and grains of metal of the matrix are almost identical: no greater than 20 μm and Ni, 5.95; Si, 3.33 wt%. The nodules contain small (usually <5 μm) inclusions of SiO2; albitic glass; enstatite; roedderite; and a mixture of SiO2 and Na2S2. This is the first reported occurrence of a simple sulfide of an alkaline metal in nature. The formation of the inclusions appears to be related to condensation of material onto the surfaces of metal grains. The nodules appear to have formed by aggregation of separate grains (globules) of metal, with conservation of condensates on the grain surfaces as inclusions. The inclusions probably condensed over a significant temperature range from 1400 to 600 K. The aggregation of metal grains and formation of the nodules probably occurred simultaneously with condensation.
Mbosi: An anomalous iron with unique silicate inclusions
Authors: OLSEN Edward J. , CLAYTON Robert N. , MAYEDA Toshiko K. , DAVIS Andrew M. , CLARKE Roy S. , WASSON John T.
Published: August 2012

Abstract— The Mbosi iron meteorite contains millimeter size silicate inclusions. Mbosi is an ungrouped iron meteorite with a Ge/Ga ratio >10, which is an anomalous property shared with the five‐member IIF iron group, the Eagle Station pallasites and four other ungrouped irons. Neither the IIF group nor the four other ungrouped irons are known to have silicate inclusions. Chips from three Mbosi inclusions were studied, but most of the work concentrated on a whole 3.1 mm circular inclusion. This inclusion consists of a mantle and a central core of different mineralogies. The mantle is partially devitrified quartz‐normative glass, consisting of microscopic crystallites of two pyroxenes and plagioclase, which are crystalline enough to give an x‐ray powder diffraction pattern but not coarse enough to permit analyses of individual minerals. The core consists of silica. The bulk composition does not match any known meteorite type, although there is a similarity in mode of occurrence to quartz‐normative silicate inclusions in some HE irons. Mbosi silicate appears to be unique. The bulk rare earth element (REE) pattern of the mantle is flat at ≅ 7×C1; the core is depleted in REE but shows a small positive Eu anomaly. The O‐isotope composition of bulk silicate lies on a unit slope mixing line (parallel and close to the C3 mixing line) that includes the Eagle Station pallasites and the iron Bocaiuva (related to the IIF irons); all of these share the property of having Ge/Ga ratios >10. It is concluded that Mbosi silicate represents a silica‐bearing source rock that was melted and injected into metal. Melting occurred early in the history of the parent body because the metal now shows a normal Widmanstätten structure with only minor distortion that was caused when the parent body broke up and released meteorites into interplanetary space. The cause of Ge/Ga ratios being >10 in these irons is unknown. The fact that silicates in Mbosi, Bocaiuva (related to IIF irons) and the Eagle Station trio of pallasites, all characterized by a Ge/Ga ratio >10, lie on a unit slope mixing line in the O‐isotope diagram suggests that their origins are closely related. The C3 chondrites appear to be likely precursors for silicates in Mbosi, Bocaiuva and the Eagle Station pallasites.
The nuclear track record of core samples from the H5 chondrite Jilin
Authors: THIEL K. , Rui‐Ying HU
Published: August 2012

Abstract— Based on 43 documented drill core samples of the H5 chondrite Jilin, the depth profile of track densities was investigated. The study of olivine and pyroxene crystals extracted from the two drill cores A and B of the main fragment no. 1 yields a track background for the Jilin interior of 150 ± 90 cm−2. To estimate the contribution of different track origins, the U microdistribution of sample sections and single grain sections was mapped by neutron‐induced 235U‐fission using high‐purity quartz glass detectors. The average U content of 0.59 ± 0.22 ppb for pyroxenes and 0.12 ± 0.06 ppb for olivines is consistent with the observed fission track background in these minerals. There are no indications of spontaneous fission of 244Pu, secondary mobilisation of U in the bulk sample, or substantial track annealing. As deduced from the calculated fission track density, the track contribution from galactic cosmic rays is negligible in the core samples investigated.
Excavation and analysis of layered tektites from northeast Thailand: Results of 1994 field expedition
Authors: Fiske Peter S. , Putthapiban Prinya , Wasson John T.
Published: August 2012

Abstract— We have analyzed the size, shape, composition, and spatial distribution of 6 kg of layered tektite fragments excavated from a 3 m × 3 m area near the town of Ban Huai Sai in northeast Thailand. Our analysis suggests that these fragments represent a single homogeneous mass that underwent fragmentation far in the past and has undergone little disturbance since its deposition. We have also studied the stratigraphic occurrence of layered tektites exposed in situ near the town of Ban Huai Om. Tektites were found along a disconformable paleo‐erosion surface covered by recent aeolian sand, similar to other occurrences throughout Southeast Asia. This stratigraphic relationship provides little chronostratigraphic information and, thus, does not support a stratigraphic “age paradox” for the Australasian tektites. The present‐day surface density of layered tektites in this area is 2 to 20 g/m2.
An Apollo 15 mare basalt fragment and lunar mare provinces
Authors: Ryder Graham , Burling Trina Cox
Published: August 2012

Abstract— Lunar sample 15474,4 is a tiny fragment of olivine‐augite vitrophyre that is a mare basalt. Although petrographically distinct from all other Apollo 15 samples, it has been ignored since its first brief description. Our new petrographic and mineral chemical data show that the olivines and pyroxenes are distinct from those in other basalts. The basalt cooled and solidified extremely rapidly; some of the olivine might be cumulate or crystallized prior to extrusion. Bulk‐chemical data show that the sample is probably similar to an evolved Apollo 15 olivine‐normative basalt in major elements but is distinct in its rare earth element pattern. Its chemical composition and petrography both show that 15474,4 cannot be derived from other Apollo 15 mare basalts by shallow‐level crystal fractionation. It represents a distinct extrusion of magma.

Nonetheless, the chemical features that 15474,4 has in common with other Apollo 15 mare basalts, including the high FeO/Sc, the general similarity of the rare earth element pattern, and the common (and chondritic) TiO2/Sm ratio, emphasize the concept of a geochemical province at the Apollo 15 site that is distinct from basalts and provinces elsewhere. In making a consistent picture for the derivation of all of the Apollo 15 basalts, both the commonalities and the differences among the basalts must be explained. The Apollo 15 commonalities and differences suggest that the sources must have consisted of major silicate phases with the same composition but with varied amounts of a magma trapped from a contemporary magma ocean. They probably had a high olivine/pyroxene ratio and underwent small and reasonably consistent degrees of partial melting to produce the basalts. These inferences may be inconsistent with models that suggest greatly different depths of melting among basalts, primitive sources for the green glasses, or extensive olivine fractionation during ascent. An integrated approach to lunar mare provinces, of which the Apollo 15 mare basalts constitute only one, offers advances in our understanding of the physical and chemical processes of source formation and mare production but has so far not been utilized.
Cosmogenic and fissiogenic noble gases and 81Kr‐Kr exposure age clusters of eucrites
Authors: Shukolyukov A. , Begemann F.
Published: August 2012

Abstract— The isotopic composition and concentrations of noble gases were measured in the eucrites Bereba, Cachari, Caldera, Camel Donga, Chervony Kut, Ibitira, Jonzac, Juvinas, Millbillillie, Moore County, Padvarninkai, Pasamonte, Pomozdino, Serra de Magé, Sioux County, and Vetluga. The distribution of 81Kr‐Kr exposure ages shows “clusters” at (7 ± 1) Ma, (10 ± 1) Ma, (14 ± 1) Ma, (22 ± 2) Ma, and (37 ± 1) Ma that agree with those for howardites, eucrites, and diogenites (HED) at (6 ± 1) Ma, (12 ± 2) Ma, (21 ± 4) Ma, and (38 ± 8) Ma. This most likely indicates a common origin of HED meteorites. Correlation equations for the shielding‐sensitive cosmogenic ratios 78Kr/83Kr, 80Kr/83Kr, 82Kr/83Kr, and 124Xe/131Xe were obtained.

Comparison with data from simulation experiments suggests that most eucrites were exposed to the cosmic radiation as somewhat large meteoroids with diameters of ∼1 m or more. The shielding‐dependence of the 78Kr and 126Xe production rates was found to be small, with a few exceptions the variations aren <10%–15%. Concentrations of spallogenic 3He indicate diffusive losses of up to 70% that can be, in first approximation, described by a model of quasi‐continuous losses during the exposure to the cosmic radiation with a loss rate of the order of ∼3 × 10−8 a−1. Radiogenic 4He shows additional substantial losses that occurred at the time of, or prior to, the separation of the meteoroids from their parent body. Typical 40Ar retention in eucrites is 50%–60% which corresponds to a 40Ar‐K retention age of 3.4–3.6 Ga. In all analyzed unbrecciated eucrites, the retention is distinctly larger (70%–100%). The 244Pu fission ratio (86Kr/136Xe)Pu, was evaluated from the data on Pomozdino samples to be 0.039 ± 0.014.
Magnetic spherules in coastal plain sediments, Sullivan's Island, South Carolina, USA
Authors: Taylor Pamela L. , Nusbaum Robert L. , Fronabarger A. Kem , Katuna Michael P. , Summer Neil
Published: August 2012

Abstract— We extracted black, magnetic spherules from well cuttings of Oligocene sediments in the coastal plain of South Carolina, USA. Three possible origins were considered: industrial, volcanic, and extraterrestrial. An extraterrestrial origin by ablation of parent meteoroid material is proposed, based on the spherule morphologies, the presence of metallic Fe cores in many of the spherules, and the detection of wüstite in some of the oxide rims. Low Ni contents are problematic but may be attributed to the ablation of a low‐Ni parental body, such as hexahedrite.

The presence of spherules in somewhat clay‐like, sandy sediments is unusual, as most magnetic spherules are found in abyssal muds. Based on benthic foraminiferal assemblages and sediment distribution above, within, and below the beds containing spherules, it is unlikely that the spherules were transported from a deep‐sea environment.
Rapid changes in the nature of the H chondrites falling to Earth
Authors: Benoit P. H. , Sears D. W. G.
Published: August 2012

Abstract— We have previously identified a subgroup of Antarctic H chondrites that are significantly different from H chondrites among the modern falls in terms of induced thermoluminescence (TL), metallographic cooling rate, and cosmogenic inert gas contents. Here we examine their terrestrial and thermal history as apparent in their natural TL and radioactive cosmogenic isotope abundances. These meteorites have a tendency towards high 26Al activities and fairly short 14C and 36Cl terrestrial ages (generally <100 ka). They also sometimes exhibit unusually high natural TL levels, which we have previously interpreted as indicating orbital evolution from perihelia >1.2 AU to ∼1 AU within the last <105 years. We suggest that the nature of the meteorites falling to Earth is not independent of time but depends on stochastic events, such as the breakup of parent bodies and recent variations in orbit.
Dark clasts in the Khor Temiki aubrite: Not basalts
Authors: Newsom Horton E. , Ntaflos Theo , Keil Klaus
Published: August 2012

Abstract— The enstatite achondrite meteorites (aubrites) are ultramafic assemblages with highly variable bulk rare earth element (REE) compositions. An enrichment of REE in a dark clast from the Khor Temiki aubrite led Wolf et al. (1983) to suggest that such dark clasts could be the basaltic (i.e., enstatite‐plagioclase) complements to the ultramafic aubrites, with the relatively high REE contents resulting from the presence of plagioclase, which is a common carrier of the REEs. We have studied several dark clasts from the Khor Temiki aubrite and find no evidence for a basaltic character for such material. The microscopic character of the dark clasts is not significantly different from the main portions of Khor Temiki and consists either of highly brecciated material, containing a fine‐grained matrix, or of enstatite grains with abundant inclusions. We suggest that the dark clasts are shock‐darkened, heterogeneous Khor Temiki material that, by chance, contained variable trace contents of oldhamite (CaS), which has been shown to be a major carrier of REE in aubrites. We find that the REE contents of the clasts range from 0.1 to ∼20× CI. Most have negative Eu anomalies, but one has a small positive anomaly. Extensive searches have failed to identify basaltic material in Khor Temiki and other aubrites. The absence of basaltic material is consistent with, but does not prove, the model of Wilson and Keil (1991). They calculate that, on an asteroidal parent body < ∼100 km in radius, a volatile‐rich basaltic partial melt erupted with a velocity greater than the escape velocity of the asteroid and, thus, was lost into space ∼ 4.55 Ga ago.
Meteorites from Mongolia
Authors: Bischoff A. , Gerel O. , Buchwald V. F. , Spettel B. , Loeken T. , Schultz L. , Weber H. W. , Schlüter J. , Bauinnyam L. , Borchuluun D. , Byambaa C. , Garamjav D.
Published: August 2012

Abstract— The mineralogy and composition of six Mongolian meteorites were studied in some detail. Previously, only limited information existed about these rocks, and some were still unclassified. The six meteorites include three ordinary chondrites and three irons. The ordinary chondrite Adzhi‐Bogdo (stone) is a regolith breccia (LL3–6) containing various types of clasts (some of foreign origin) embedded within a fine‐grained clastic matrix. Tugalin Bulen (H6) and Noyan Bogdo (L6) meteorites are typical, well‐metamorphosed ordinary chondrites. Adzhi‐Bogdo (iron) has to be regarded as an IA iron meteorite like Campo del Cielo or Canyon Diablo; although the sample studied had been heated to about 900 °C–950 °C some time in the past, thus eradicating all original structural elements. Manlai is structurally closely related to the IIC iron meteorites; but based on its chemistry, which does not fit into this group, it is suggested that Manlai is an anomalous iron meteorite. The third iron, Sargiin Gobi, is certainly a normal member of the IA iron meteorites. The concentrations and isotopic compositions of He, Ne, and Ar were measured for all meteorites and their gas retention ages and exposure ages are discussed.
X‐ray digital‐imaging petrography: Technique development for lunar mare soils
Authors: Higgins S. J. , Taylor L. A. , Chambers J. G. , Patchen A. , McKay D. S.
Published: August 2012

Abstract Remote sensing studies are the primary means of solar system exploration. In particular, spectral reflectance measurements involve determinations of the nature and compositions of other worlds through analysis of absorption features characteristic of the surface chemistry and mineralogy. These studies are particularly applicable to “airless” solar system bodies (e.g., the Moon), because atmospheres, such as on Earth, tend to interfere with the reflectance spectrum. The precision of the spectral measurements is greatly increased by calibration with actual lunar soils. In the past, these calibrations were done using particle‐counting data collected for the study of soil formation processes, soil classification, and provenance determination. These particle counting data, while valuable in those areas of study, neither identify the true volume percentages of soil particles, nor give the true modal values for the various phases (i.e., minerals and glasses) which make up the soil grains. These data are paramount for accurate spectral reflectance calibrations. Therefore, in this paper, a new technique is presented that involves x‐ray digital‐imaging of lunar soils using an energy dispersive spectrometer (EDS) on an electron microprobe. In contrast to particle counting with an optical microscope, the digital‐imaging method allows precise volume percentages of soil grains to be determined, including absolute modal abundances of the various phases locked within the particles as well as their chemistry. In order to validate this method for characterization of lunar soils, the technique was applied to four Apollo 17 soils that were previously described by Heiken and McKay (1974) via particle counts with an optical microscope, and similar results were obtained. In addition to verifying the x‐ray digital‐imaging technique, the obtained data were applied in order to better understand the lunar‐soil formational process, specifically the variation of particle types with maturity.
Search for fullerenes in lunar fines 10084 and 79261
Authors: Heymann D.
Published: August 2012

Abstract Radicati di Brozolo et al. (1994) found the fullerenes C60 and C70 in and around a micrometeorite impact pit on the skin of the LDEF (Long Duration Exposure Facility) spacecraft and concluded that the fullerenes had formed from C of the micrometeorite. Becker et al. (1994) concluded that C60 and C70 in C‐bearing rocks from the large Sudbury impact structure had come mostly from C of the impacting bolide. These observations suggested that fullerenes had formed by analogous impacts on the Moon. One sample from the Apollo 11 site and one from the Apollo 17 site were treated with toluene for the extraction of C60 and C70. The extracts were analyzed by High Performance Liquid Chromatography (HPLC) for the presence of C60 and C70 fullerenes. No fullerenes were detected. Either the formation of fullerenes from extra lunar C on the Moon had very low yields, or fullerenes were formed with detectable yields but were quantitatively removed from the surface of the Moon in a short time.
Aqueous alteration in the matrix of the Vigarano (CV3) carbonaceous chondrite
Authors: LEE Martin R. , HUTCHISON Robert , GRAHAM Andrew L.
Published: August 2012

Abstract The matrix of Vigarano, a meteorite which belongs to the reduced subgroup of the CV3 chondrites, contains small amounts (<10%) of ferrihydrite and smectite. These hydrous minerals occur together as fine fibrous intergrowths between anhydrous silicate and oxide grains. Coarser crystals of ferrihydrite fill fractures that cut matrix minerals, and smectite also lines narrow channels within olivine grains. These channels may have formed by preferential alteration of olivines along (100)‐parallel defects.

Formation of ferrihydrite and smectite in the matrix of Vigarano was the result of mild aqueous alteration in a low‐temperature (<150 °C), oxidising parent body environment. Partial equilibration of matrix olivines indicates that alteration was followed by thermal metamorphism with a peak temperature of 400–500 °C. Mineralogically similar alteration products, which also were formed by parent body processes, have previously been described from the matrices of four CV meteorites: Bali, Grosnaja, Kaba and Mokoia, all of which belong to the oxidised subgroup. This discovery of the products of oxidative aqueous alteration in Vigarano has important consequences for understanding the chemical and thermal history of the CV class of meteorites.
The Kaidun meteorite: Mineralogy of an unusual CM1 lithology
Authors: ZOLENSKY Michael E. , IVANOV Andrei V. , YANG S. Vincent , MITTLEFEHLDT David W. , OHSUMI Kazumasa
Published: August 2012

Abstract Kaidun is a breccia of disparate enstatite and carbonaceous chondrite clasts that continues to provide real surprises. Many Kaidun clasts have been intensely altered by aqueous fluids, as evidenced by the widespread occurrence of ferromagnesian phyllosilicates and by the presence of carbonate‐ and phyllo‐silicate‐filled veins. In this report, we describe an unusual CM lithology containing many mineralogical features not previously reported from any meteorite, including pyrrhotite, with exclusive needlelike morphologies and thick mantles of phyllosilicate, and complex aggregates of phyllosilicate, melanite garnet, crosscut by pentlandite veins. The latter features appear to be due in large part to extensive hydrothermal alteration at temperatures on the order of 450 °C, which is significantly higher than that attained during secondary processing from other known CM material.
The meteorite collection of “Giorgio Abetti”* Astronomical Observatory and Museum, San Giovanni in Persiceto, Bologna, Italy: An update of the catalog
Authors: LEVI‐DONATI G. R.
Published: August 2012

Abstract— A catalogue of a collection of meteorites is presented. The catalogue is complete through 1995 December. It includes 206 stony meteorites, 47 iron meteorites, 18 stony‐iron meteorites, and 30 tektites, natural glasses, etc.
The role of meteoritics in spaceflight missions and vice versa
Authors: McSWEEN Harry Y.
Published: August 2012

Abstract— Research on extraterrestrial materials plays a critical role in formulating the science rationale and design for spacecraft missions, and, conversely, spaceflight holds great promise for solving perplexing problems in meteoritics. The connections between meteoritics and sample‐return missions are obvious: Meteorite research can define sampling strategies, the capabilities of sampling devices, acceptable levels of chemical contamination and physical alteration of samples, and the conditions under which samples are stored prior to and during recovery. For their part, sample‐return missions can provide geologic context for meteorites, increased sampling diversity (including materials not sampled as meteorites, such as unconsolidated regolith, ices, and atmosphere), calibration for crater‐counting chronology, and ground truth for remote sensing measurements of meteorite parent bodies. Meteoritics also relates to spacecraft flyby, rendezvous, and lander missions that do not necessarily return samples. Specific illustrations of this mutual relationship, based on a selection of recent or planned spacecraft missions include: Identifying source asteroid classes for ordinary and carbonaceous chondrites and reconstructing their thermal and collisional histories (Galileo, NEAR, Clementine II, and Muses‐C); determining the extent to which cometary dust and interstellar grains are found as interplanetary dust particles and assessing volatile abundances, isotopic compositions, and molecular species in cometary nuclei (Stardust and Rosetta); understanding the compositions of ancient Martian crust and the mantle sources for SNC meteorites, as well as inventorying the planet's volatile reservoirs and interactions (Mars Pathfinder, Mars Global Surveyor, and Mars Volatiles and Climate Surveyor); assessing whether lunar meteorites provide a more representative chemical sampling of the highlands crust and of mare volcanism than do Apollo samples (Galileo, Clementine, and Lunar Prospector). Spaceflight is the first priority of the space agencies that fund most research on extraterrestrial materials, and the continued level of support for such research may be linked, in part, to its use in exploration by spacecraft.
An analytical electron microscopy (AEM) investigation of opaque inclusions in some type 6 ordinary chondrites
Authors: LEROUX Hugues , DOUKHAN Jean‐Claude , GUYOT François
Published: August 2012

Abstract— A large number of ordinary chondrites contains micron‐sized particles of metal and/or troilite dispersed in their silicate grains. Such metallic phases are responsible for the so‐called darkening of the silicate grains and might be either precipitates, which formed during reduction of the silicates, or inclusions injected as a melt during a shock event. We have investigated these tiny foreign phases by analytical transmission electron microscopy in three unweathered, metamorphosed ordinary chondrites (Saint Séverin, LL6, Tsarev, L6 and Kernouvé, H6). We also looked for remnant shock indices.

Our TEM observations suggest the following sequence of events in the three meteorites. First, a number of relatively strong shock events occurred on the parent body/bodies producing an Fe‐FeS melt that was injected into silicate grains along a dense network of open fractures. Most of these shock defects were subsequently erased by high‐temperature (700–900 °C) thermal metamorphism. Some remnants of the shock events are the observed trails of tiny metal and/or sulfide inclusions that formed as a result of fracture healing. Chemical homogenization of the silicates and limited oxidation of the metallic blebs also occurred during this high‐temperature annealing event, resulting in Ni‐rich inclusions. This effect was especially pronounced in the L and LL‐chondrites studied. During subsequent cooling of the body/bodies, inclusions of chromite and phosphate precipitated, nucleating preferentially on lattice defects (dislocations, subgrain boundaries) and on the metal and sulfide inclusions. A later shock event of moderate intensity, probably corresponding to the separation of the meteorite from its parent body, produced new shock features in the silicate grains of the Saint Séverin meteorite, including mechanical twins in diopside and straight free screw dislocations in olivine.
Anatomy of individual agglutinates from a lunar highland soil
Authors: BASU Abhijit , McKAY David S. , MORRIS Richard V. , WENTWORTH Susan J.
Published: August 2012

Abstract— We report results of our investigation of the relationship between values of Is/FeO (relative concentration of nanophase Fe0 divided by total FeO content), glass abundance, total Fe content, and degree of digestion of <20 μm clasts for 22 individual agglutinates (250–1000 μm) from the mature Apollo 16 soil 61181 (Is/FeO = 82 units in the <250 μm fraction). Agglutinates are important products of space weathering on the Moon, and they influence spectral observations at visible and near‐IR wavelengths. Values of Is/FeO for individual agglutinates (250–1000 μm) within this single soil span a range from 3 to 262 units which is larger than the range observed for all Apollo 16 bulk soils (∼0 to 110 units). No correlation was observed between Is/FeO and glass abundance and FeO concentrations for either agglutinitic glass or whole agglutinate particles under investigation. Our results suggest that the variation in Is/FeO for agglutinates from a single soil may be in part a consequence of natural mixing processes on the Moon that produce highly‐variable environments (with respect to surface exposure) for agglutinate formation and in part to variable kinetics of reactions in an agglutinate melt, which are influenced by a variety of factors including melt composition, temperature, impactor velocity, and quench rate. We cannot exclude but do not see evidence for other processes including addition of exotic agglutinates, micrometeoritic bombardment into compositionally‐diverse microtargets, recycling of agglutinates, preferential melting of very fine soil particles, and production of nanophase Fe0 in amorphous rims of very fine irradiated lunar grains contributing to the observed variation of Is/FeO.
Lunar meteorite Queen Alexandra Range 93069: A lunar highland regolith breccia with very low abundances of mafic components
Authors: BISCHOFF A.
Published: August 2012

Abstract— Lunar meteorite QUE 93069 found in Antarctica is a mature, anorthitic regolith breccia with highland affinities that was ejected from the Moon <0.3 Ma ago. The frequency distribution of mineral and lithic clasts gives information about the nature of the regolith and subregolith basement near the ejection site as well as about the abundances of rock types shocked to different degrees prior to the breccia formation.

Thin section QUE 93069,37 consists of 67.5 vol% fine‐grained (<∼130 μm) constituents and 32.5 vol% mineral and lithic clasts and an impact melt vein. The most abundant types of these clasts are intragranularly recrystallized anorthosites and plagioclases (together 26.3 vol%) and feldspathic fine‐grained to microporphyritic crystalline melt breccias (21.9 vol%). Mafic crystalline melt breccias are extremely rare (1.3 vol%). Granulitic lithologies are 10.4 vol%, recrystallized feldspathic melt breccias are 15.0 vol%, and glasses are 3.5 vol%. The impact melt vein cutting across the entire thin section was probably formed subsequent to the lithification process of the bulk rock at pressures below 20 GPa, because the bulk rock never experienced a higher peak shock pressure.

Lunar meteorite QUE 93069 has a higher abundance of clear glass, occurring within melt spherules, glassy fragments, and an impact melt vein than lunar meteorites ALHA81005, Y‐791197, Y‐82192/3, Y‐86032, or MAC 88104/5. The high abundance of melt spherules indicates that this lunar meteorite contains the highest content of typical regolith components. Mafic crystalline melt breccias are much rarer in QUE 93069 than in all other lunar highland regolith breccias. The extremely low abundance of mafic components may constrain possible areas of the Moon, from which the breccia was derived. The source area of QUE 93069 must be a highland terrain lacking significant mafic impact melts or mare components.
History of lunar meteorites Queen Alexandra Range 93069, Asuka 881757, and Yamato 793169 based on noble gas isotopic abundances, radionuclide concentrations, and chemical composition
Authors: THALMANN Christoph , EUGSTER Otto , HERZOG Gregory F. , XUE Suizhou , KLEIN Jeffrey , KRÄHENBÜHL Urs , VOGT Stephan
Published: August 2012

Abstract— We investigated the characteristics and history of lunar meteorites Queen Alexandra Range 93069, Yamato 793169 and Asuka 881757 based on the abundances of all stable noble gas isotopes, the concentrations of the radionuclides 10Be, 26Al, 36Cl, and 81Kr, and the abundances of Mg, Al, K, Ca, Fe, Cl, Sr, Y, Zr, Ba, and La. Based on the solar wind and cosmic‐ray irradiations, QUE 93069 is the most mature lunar meteorite studied up to now. The 40Ar/36Ar ratio of the trapped component is 1.87 ± 0.16. This ratio corresponds to a time when the material was exposed to solar and lunar atmospheric volatiles ∼400 Ma ago. On the other hand, Yamato 793169 and Asuka 881757 contain very little or no solar noble gases, which indicates that these materials resided in the top layer of the lunar regolith only briefly or not at all. For all lunar meteorites, we observe a positive correlation of the concentrations of cosmic‐ray produced with trapped solar noble gases. The duration of lunar regolith residence for the lunar meteorites was calculated based on cosmic‐ray produced 21Ne, 38Ar, 78Kr, 83Kr, and 126Xe and appropriate production rates that were derived based on the target element abundances and the shielding indicator 131Xe/126Xe. For QUE 93069, Yamato 793169, and Asuka 881757, we obtained 1000 ± 400 Ma, 50 ± 10 Ma, and <1 Ma, respectively. Both Asuka 881757 and Yamato 793169 show losses of radiogenic 4He from U and Th decay and Yamato 793169 also 40Ar loss from K‐decay. For Asuka 881757, we calculate a K‐Ar gas retention age of 3100 ± 600 Ma and a 244Pu‐136Xe fission age of 4240 ± 170 Ma. This age is one of the oldest formation ages ever observed for a lunar basalt. The exposure history of QUE 93069 after ejection from the Moon was derived from the radionuclide concentrations: ejection 0.16 ± 0.03 Ma ago, duration of Moon‐Earth transit 0.15 ± 0.02 Ma and fall on Earth <0.015 Ma ago. This ejection event is distinguished temporally from those which produced the other lunar meteorites. We conclude that six to eight events are necessary to eject all the known lunar meteorites.
Equine corneal stromal abscesses: An evolution in the understanding of pathogenesis and treatment during the past 30 years
Authors: Henriksen M. D. L. , Andersen P. H. , Plummer C. E. , Mangan B. , Brooks D. E.
Published: August 2012

The last 30 years have seen many changes in the understanding of the pathogenesis and treatment of equine corneal stromal abscesses (SAs). Stromal abscesses were previously considered an eye problem related to corneal bacterial infection, equine recurrent uveitis, corneal microtrauma and corneal foreign bodies in horses. They were more commonly diagnosed in horses living in subtropical climatic areas of the world. Therapeutic recommendations to treat equine SAs were historically nearly always a medical approach directed at bacteria and the often associated severe iridocyclitis. Today the pathogenesis of most equine SAs appears to be more often related to fungal inoculation of the anterior corneal stroma followed by posterior migration of the fungi deeper into the corneal stroma. There is also now an increased incidence of diagnosis of corneal SAs in horses living in more temperate climates. Medical and surgical treatments are now directed towards elimination of fungal and bacterial infections, reduction and replacement of diseased corneal stroma, and suppression of iridocyclitis. If the abscess and anterior uveitis do not respond satisfactorily to medical therapy, full thickness or split thickness lamellar keratectomy to remove the fungal hyphae and diseased stroma, followed by transplantation of healthy corneal allografts has a high rate of success in speeding healing and preserving sight. This paradigm shift in the ability to diagnose and institute therapy for corneal SAs in horses has evolved over the last 30 years, and is the focus of this paper.
Factors influencing foaling rate following colic surgery in pregnantThoroughbred mares inCentralKentucky
Authors: Drumm N. J. , Embertson R. M. , Woodie J. B. , Ruggles A. J. , Hopper S. A. , Fimmers R. , Handler J.
Published: August 2012

Reasons for performing study

Clinical experience has suggested that foaling rates following colic surgery in the pregnant mare are influenced by days of gestation. This premise has not been supported in previous studies. We also aimed to determine the effects of other potential influencing factors.

Objective

To determine the influence of age of gestation on foaling rates in pregnant mares following colic surgery and evaluate the relationships between other factors and foaling rates.

Methods

Medical records ofThoroughbred mares, which had colic surgery performed from 1993 to 2007 at theRood andRiddleEquineHospital, were reviewed. Mares identified in the record as pregnant or bred within the previous 15 days were included in this study. Age of the mare, date of surgery, gestational age, duration of colic at admission, packed cell volume at admission, surgical diagnosis, duration of general anaesthesia, intraoperative hypotension, intraoperative hypoxaemia and post operative signs of endotoxaemia were recorded. A mare was considered to have a live foal if that foal was registered with theNorthAmericanJockeyClub.

Results

Of the 228 mares, where pregnancy had been confirmed, 152 (66.7%) had a live foal registered after surgery. Mares bred <40 days before surgery had a lower foaling rate compared with mares undergoing surgery ≥40 days after breeding: 48.7% vs. 69.8% (odds ratio [OR] = 0.41 [95% confidence interval (CI) 0.20–0.83],P= 0.012). Foaling rate was also influenced by mare's age (P= 0.008) and duration of colic signs before surgery (P= 0.03).

Conclusions

The prognosis for a live foal after colic surgery in the pregnant Thoroughbred mare is significantly better if the mare is ≤15 years of age and ≥40 days of gestation.

Potential relevance

The results of this study are useful for clinicians offering a prognosis for a live foal following colic surgery in pregnant mares.
Adjunctive clinical effect of a water‐cooled Nd:YAGlaser in a periodontal maintenance care programme: a randomized controlled trial
Authors: Slot Dagmar E. , Timmerman Mark F. , Versteeg Paula A. , van der Velden Ubele , van der Weijden Fridus A.
Published: August 2012

Background

Various laser systems are currently available for intra‐oral use. Neodymium:Yttrium–Aluminium Garnet lasers(Nd:YAG) have been approved by theUSFood and Drug Administration for soft tissue treatment in the oral cavity.

Objectives

The aim of this study was to test whether the use of a water‐cooled Nd:YAGlaser during a maintenance care programme as an adjunct to supragingival and subgingival debridement (scaling and root planing,SRP) with hand and ultrasonic instruments results in clinical improvement compared withSRPalone.

Material and Methods

This study was an examiner‐blind, randomized and controlled clinical trial using a split‐mouth design. Thirty subjects were selected, originally diagnosed with moderate to severe generalized periodontitis, following a periodontal maintenance care programme (PMC). Immediately afterSRPin two randomly assigned contra‐lateral quadrants, all pockets ≥5 mm were additionally treated with a Nd:YAGlaser (1064 nm, 4W, 250‐μsec pulse). Clinical assessments [probing pocket depthPPD, bleeding on pocket probing (BOPP)] were performed pre‐treatment and at 6 months. Based on these assessments, the periodontal inflamed surface area (PISA) was calculated.

Results

At 6 months, the clinical parameters had significantly improved for both regimens. No statistically significant differences between treatment modalities were observed forPPDandBOPPscores at any time.PISAscores supported these findings.

Conclusions

In residual pockets ≥5 mm, treated in aPMC, the adjunctive use of an Nd:YAGlaser does not provide a clinically significant additional advantage.
Mesenchymal stem cells derived from inflamed periodontal ligaments exhibit impaired immunomodulation
Authors: Liu Dayong , Xu Junji , Liu Ousheng , Fan Zhipeng , Liu Yi , Wang Fu , Ding Gang , Wei Fulan , Zhang Chunmei , Wang Songlin
Published: August 2012

Aim

The purpose of this study was to investigate the immunomodulatory properties of periodontal ligament stem cells derived from inflamed periodontal ligament tissues.

Material and Methods

Periodontal ligament stem cells were identified and isolated from healthy or inflamed periodontal ligament tissues. Peripheral blood mononuclear cells were cocultured with inflamed or healthy periodontal ligament stem cells, and T‐lymphocyte proliferation was determined by incubation with carboxyfluorescein succinimidyl ester. T‐helper cells (Th1/Th2, Th17) and regulatory T cells were analysed by flow cytometry. Cytokine profiles in supernatants were tested with a cytometric bead array.

Results

Compared to healthy cells, inflamed periodontal ligament stem cells showed significantly diminished inhibition of T‐cell proliferation. In cocultures, stimulated peripheral blood mononuclear cells showed significantly less induction of CD4+CD25+FOXP3+ regulatory T cells and IL‐10 secretion in the presence of inflamed compared with healthy periodontal ligament stem cells. Furthermore, suppression of Th17 differentiation and IL‐17 production by inflamed periodontal ligament stem cells was significantly lesser than by healthy cells.

Conclusion

This study demonstrated that inflamed periodontal ligament stem cells had markedly dysfunctional immunomodulatory properties; this may contribute to an imbalanced immune response, acceleration of osteoclastogenesis and inflammatory alveolar bone loss in periodontitis.
Callose Synthase in Pinus sylvestris Response during Infection by Species of Heterobasidion annosum sensu lato with Varied Host Preferences
Authors: Zadworny Marcin , Smoliński Dariusz J. , Świdzinski Michał , Guzicka Marzenna , Łakomy Piotr , Mucha Joanna
Published: August 2012

Strengthening of plant cell walls at the site of fungal entry is one of the earliest plant responses to fungal pathogens. The aim of our study was to characterize the pattern of callose synthase localization and callose deposition in roots of Pinus sylvestris after infection by species of the Heterobasidion annosum s.l. complex with different host specificity: H. annosum s.s., H. parviporum and H. abietinum. To address this, sense‐labelled probes and ribonuclease‐treated samples were used to determine in situ hybridizations of callose synthase by FISH method. Furthermore, determination of callose accumulation within P. sylvestris cells was carried out using aniline blue. The different species of H. annosum s.l. had distinct impacts on the callose synthase staining within plant tissues. Moreover, while inoculation with strains of H. abietinum resulted in callose synthase accumulation at the point of hyphae contact with the host cell, this was not observed with the other species. A significant difference in callose synthesis localization was observed after inoculation with varied species of H. annosum s.l. as a result of the specific interactions with the host.
Gene silencing by H‐NS from distal DNA site
Authors: Shin Minsang , Lagda Arvin Cesar , Lee Jae Woong , Bhat Abhay , Rhee Joon Haeng , Kim Jeong‐Sun , Takeyasu Kunio , Choy Hyon E.
Published: August 2012

In the modern concept of gene regulation, ‘DNA looping’ is the most common underlying mechanism in the interaction between RNA polymerase (RNAP) and transcription factors acting at a distance. This study demonstrates an additional mechanism by which DNA‐bound proteins communicate with each other, by analysing the bacterial histone‐like nucleoid‐structuring protein (H‐NS), a general transcriptional silencer. The LEE5 promoter (LEE5p) of enteropathogenic Escherichia coli was used as a model system to investigate the mechanism of H‐NS‐mediated transcription repression. We found that H‐NS represses LEE5p by binding to a cluster of A tracks upstream of −114, followed by spreading to a site at the promoter through the oligomerization of H‐NS molecules. At the promoter, the H‐NS makes a specific contact with the carboxy terminal domain of the α subunit of RNAP, which prevents the processing of RNAP–promoter complexes into initiation‐competent open promoter complexes, thereby regulating LEE5p from distance.
An Internal State Variable Constitutive Model for Deformation of Austenitic Stainless Steels
Authors: Follansbee Paul S.
Published: August 2012

Austenitic stainless steels—particularly the 304 and 316 families of alloys—exhibit similar trends in the dependence of yield stress on temperature. Analysis of temperature and strain-rate dependent yield stress literature data in alloys with varying nitrogen content and grain size has enabled the definition of two internal state variables characterizing defect populations. The analysis is based on an internal state variable constitutive law termed the mechanical threshold stress model. One of the state variables varies solely with nitrogen content and is characterized with a larger activation volume. The other state variable is characterized by a much smaller activation volume and may represent interaction of dislocations with solute and interstitial atoms. Analysis of the entire stress–strain curve requires addition of a third internal state variable characterizing the evolving stored dislocation density. Predictions of the model are compared to measurements in 304, 304L, 316, and 316L stainless steels deformed over a wide range of temperatures (up to one-half the melting temperature) and strain rates. Model predictions and experimental measurements deviate at temperatures above ∼600 K where dynamic strain aging has been observed. Application of the model is demonstrated in irradiated 316LN where the defect population induced by irradiation damage is analyzed. This defect population has similarities with the stored dislocation density. The proposed model offers a framework for modeling deformation in stable austenitic stainless steels (i.e., those not prone to a martensitic phase transformation).
Simulation of Material Flow and Heat Evolution in Friction Stir Processing Incorporating Melting
Authors: Nassar H. W. , Khraisheh M. K.
Published: August 2012

Friction stir processing (FSP) is a relatively new technology for microstructure refinement of metallic alloys. At high processing speeds, excessive heating due to severe plastic deformation and friction may result in local melting at the interface between the FSP tool and the workpiece. In this work, a computational fluid dynamics (CFD) approach is applied to model material flow and heat evolution during friction stir processing of AZ31B magnesium alloy, taking into consideration the possibility of local melting in the stirring region. This is achieved by introducing the latent heat of fusion into an expression for heat capacity and accounting for possible effects of liquid formation on viscosity and friction. Results show that the temperature in the stirring region increases with the increase in rotational speed and drops slightly with the increase in translational speed. As liquid phase begins to form, the slope of temperature rise with rotational speed decreases and the maximum temperature in the stirring region stabilizes below the liquidus temperature at high rotational speeds. It is also shown that the formation of a semi-molten layer around the tool may result in a reduction in the shearing required for microstructure refinement.