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The Hamburg meteorite fell on January 16, 2018, near Hamburg, Michigan, after a fireball event widely observed in the U.S. Midwest and in Ontario, Canada. Several fragments fell onto frozen surfaces of lakes and, thanks to weather radar data, were recovered days after the fall. The studied rock fragments show no or little signs of terrestrial weathering. Here, we present the initial results from an international consortium study to describe the fall, characterize the meteorite, and probe the collision history of Hamburg. About 1 kg of recovered meteorites was initially reported. Petrology, mineral chemistry, trace element and organic chemistry, and O and Cr isotopic compositions are characteristic of H4 chondrites. Cosmic ray exposure ages based on cosmogenic 3He, 21Ne, and 38Ar are ~12 Ma, and roughly agree with each other. Noble gas data as well as the cosmogenic 10Be concentration point to a small 40-60 cm diameter meteoroid. An 40Ar-39Ar age of 4532 ± 24 Ma indicates no major impact event occurring later in its evolutionary history, consistent with data of other H4 chondrites. Microanalyses of phosphates with LA-ICPMS give an average Pb-Pb age of 4549 ± 36 Ma. This is in good agreement with the average SIMS Pb-Pb phosphate age of 4535.3 ± 9.5 Ma and U-Pb Concordia age of 4535 ± 10 Ma. The weighted average age of 4541.6 ± 9.5 Ma reflects the metamorphic phosphate crystallization age after parent body formation in the early solar system.

The 187Re-187Os isotopic systematics of many bulk chondrites plot well beyond analytical uncertainties of a primordial isochron. Limited variations in 187Os/188Os, coupled with large variations in Re/Os ratios among chondrites, suggest that this apparently open-system behavior is a result of the comparatively recent gain or loss of Re and/or Os. In order to assess whether or not rapid alteration in the terrestrial environment could be responsible for open-system behavior in chondrites, four pieces of the Sutter's Mill meteorite were examined for Os isotopic systematics and abundances of highly siderophile elements. Pieces SM1 and SM2 were collected prior to a rain event, within 2 days of the fall. Pieces SM51 and SM53 were collected after a rain event. There are significant but minor relative and absolute variations in the abundances of the highly siderophile elements, as well as 187Os/188Os among the four pieces. Rhenium-Os isotopic data for SM1 and SM2 plot within analytical uncertainties of a primordial isochron, while powders made from SM51 and SM53 do not. These results suggest that interactions with rain caused some redistribution of Re, and to a lesser extent Os, within small pieces of the meteorite. Thus, Re-Os isotopic systematics of

The long‐term health of pollinators is a critical issue for the functioning of natural habitats and for agricultural production. In response to widespread public concern about the future of these ecologically and economically important animals, in 2015 the US Government released a national strategy to support pollinators, including research priorities, directives for funding, and timelines for achieving three overarching goals. Five years after this strategic plan was released, we evaluate progress toward the national targets for improved honey bee (Apis mellifera) overwintering survival, expanded pollinator habitat, and larger monarch butterfly (Danaus plexippus) populations, and find that the three goals of the plan have not yet been reached. Our research and extension programs to improve the health of honey bees, wild bees, and monarch butterflies in the US state of Michigan are described, providing opportunities to contribute to the national pollinator goals. [ABSTRACT FROM AUTHOR]

Williams and Bargh (2008) reported that holding a hot cup of coffee caused participants to judge a person's personality as warmer and that holding a therapeutic heat pad caused participants to choose rewards for other people rather than for themselves. These experiments featured large effects (r = .28 and .31), small sample sizes (41 and 53 participants), and barely statistically significant results. We attempted to replicate both experiments in field settings with more than triple the sample sizes (128 and 177) and double-blind procedures, but found nearzero effects (r = -.0 3 and .02). In both cases, Bayesian analyses suggest there is substantially more evidence for the null hypothesis of no effect than for the original physical warmth priming hypothesis. [ABSTRACT FROM AUTHOR]

In a volunteer's dilemma (VoD), one person must make a material sacrifice so that others benefit. If no one makes a sacrifice, everyone is worse off than a volunteer. How do people make the decision to volunteer? We explore 4 a priori strategies in a 2-person 1-shot VoD. Two strategies focus a person's attention on either his or her own (egocentrism) or the other's (allocentrism) highest potential payoff. The third strategy (collectivism) directs attention to both players' payoffs and thereby maximizes joint outcomes. The fourth strategy (classic rationality) also directs attention to the other's payoffs to enable a mixed-motive Nash equilibrium. The results of 2 experiments with a set of asymmetric games show a pattern consistent with egocentrism, yet all 4 strategies yield similar degrees of volunteering overall. Also consistent with egocentrism, respondents project their own preferred decisions onto others. We discuss the contributions of egocentric reasoning to the provision of public goods. [ABSTRACT FROM AUTHOR]

How do social observers perceive and judge individuals who self-enhance (vs. not)? Using a decision-theoretic framework, we distinguish between self-enhancement bias and error, where the former comprises both correct and incorrect self-perceptions of being better than average. The latter occurs when a claim to be better than others is found to be false. In two studies, we find that when judging people's competence, observers are sensitive to the accuracy of self-perception. When judging their morality, however, they tend to respond negatively to any claims of being better than average. These findings are further modulated by the domain of performance (intelligence vs. moral aptitude). Implications for the strategic use of self-enhancement claims are discussed. [ABSTRACT FROM AUTHOR]

Introduction: The Martian meteorite NWA 7034 is a unique polymict breccia (e.g., [1-6]) characterized by a finegrained matrix that hosts diverse clast types that record a diversity of ages, indicating that this meteorite had a complex history punctuated by major thermal disturbances (e.g., [1, 7-9]). The clast types include differentiated igneous clasts, impact ejecta melt clasts, and breccia recycled from more ancient breccia. Here we describe a previously uncharacterized clast type, a large, olivine-rich clast (named Valentine due to its resemblance to a heart). Methods: A 2.5 cm2 sawn fragment of Black Beauty specimen FMNH ME 6118.1 was mounted in epoxy and polished by hand to reveal a cross section (polished section FMNH ME 6118.2). The petrology and mineral chemistry of the specimen was determined using X-ray microtomography (µCT), scanning electron microscopy, and quantitative energy dispersive X-ray spectroscopy (SEM/EDS): µCT. Specimen FMNH ME 6118.1 was scanned at 27.5 µm voxel resolution using the General Electric Phoenix v|tome|x S240 µCT scanner in the Department of Organismal Biology and Anatomy at the University of Chicago. Data were acquired with a transmission 240 kV microfocus X-ray tube using a diamond anode. SEM/EDS. To evaluate petrologic textures of the cross sectioned sample, high-resolution, backstattered electron (BSE) images were obtained from ME 6118.2 using a TESCAN LYRA3 field emission SEM equipped with an incolumn BSE detector in the Department of the Geophysical Sciences at the University of Chicago. To generate quantitative chemical maps (TruMaps), the SEM is also equipped with two Oxford Instruments XMax 80 silicon drift energy dispersive X-ray spectroscopy (EDS) detectors; these, coupled with Oxford Instruments AZTec software, were used for simultaneous determination of C, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, and Zr compositions. The system was calibrated with mineral and metal standards; the current stability and intensity was monitored using a Co standard and the beginning and end of each analysis session. Quantitative compositional analyses of the entire surface and of individual clasts larger than 0.1 mm2 (as in [5]) were made. Petrographic description: Euhedral phenocrysts and phenocryst fragments of dominant low-Ca pyroxene, pigeonite, and augite are set in a very fine-grained matrix which is composed of pyroxene, plagioclase, phosphate, and Fe-Ti oxide phases. As observed in previous studies, igneous clasts, proto-breccia clasts, and spherical melt clasts with accreted dust rims are present. Valentine is a large (~1 cm) clast that is composed primarily of porphyritic subhedral to anhedral grains of magnesian (Fo60-73) olivine and which represents, to our knowledge, the first documentation of an olivine-rich clast in a study of Black Beauty. Some of Valenitne's olivine grains contain accessory euhedral chrome-spinel inclusions 0.1-0.2 mm in size. The clast also contains several 0.5-2 mm subhedral to anhedral feldspar microphenocrysts, much more calcic and uniform (An51-62, Ab37-46, Or1-3) than the variable and primarily alkali (An9-33, Ab9-63, Or12-74) feldspar clasts in the matrix surrounding Valentine. Apatite is also present as 0.5-1 mm anhedral inclusions within Valentine's silicate phases. Calcium carbonate veins cut through Valentine and other clasts and extend to sample's exterior surfaces. Acknowledgements: We thank J. Piatek for donating the specimen, A. I. Neander for µCT scanning, G. Olack for maintaining the SEM lab, the TAWANI Foundation for support of the Robert A. Pritzker Center, and the Field Museum for funding MCV through the John Caldwell Meeker Postdoctoral Fellowship. [ABSTRACT FROM AUTHOR]

Introduction: Due to their small sizes, analytical challenges have impeded fine-grained, extraterrestrial materials and their nanoscale components from being fully characterized. Presolar oxides can range in size from a few micrometers down to <30 nm and have been found to be the carriers of 54Cr isotopic anomalies, with the smallest grains carrying the largest anomalies [1-3]. Unfortunately, even with the spatial resolution afforded by NanoSIMS, measurements of the isotopic compositions of grains <100 nm across can suffer from significant dilution effects from nearby material and are, therefore, only lower limits and the amount of dilution must be modelled to obtain better estimates [3]. Although frequently used in materials science, atom probe tomography (APT) has only recently begun to be applied in planetary science and cosmochemistry (e.g., [4, 5]). While NanoSIMS has a much higher mass resolving power, APT generates quantitative atom-by-atom elemental and isotopic distributions in 3D with a high sensitivity (~80% detection efficiency) at near-atomic spatial resolution. APT also detects all mass/charge-state ratios <600 Da, allowing for the possibility of additional correlated anomalies to be discovered within a grain, which may have been previously missed. APT is therefore a powerful technique for studying fine-grained materials, such as presolar oxides by providing undiluted local elemental and isotopic compositions of each grain with nm-scale spatial resolution, so that subgrains, inclusions, and other compositional heterogeneities (e.g., gradients) can be detected. Samples and Methods: APT analyses require laborious sample preparation, particularly for site-specific sub-µm grains. For this study, we have developed protocols adapted from traditional APT sample preparation methods [6] for lifting out and preparing nano-tips that target sub-µm grains for APT analyses. Samples were prepared with the TESCAN LYRA3 FIB-SEM at the University of Chicago. The nano-tips were analyzed with the LEAP5000XS tomograph at Northwestern University. Prior to analyzing bona fide presolar oxides, we have analyzed a ~1.5 µm meteoritic chromite from the CI chondrite Orgueil. This grain was also analyzed by energy dispersive spectroscopy (EDS) prior to APT. Presolar oxides were previously identified in this residue by NanoSIMS [2]. We also analyzed three nanotips prepared from a natural chromite reference material, UWCr-3, from a South African chromitite [7]. Results and Discussion: APT confirms that the UWCr-3 chromite standard is homogenous in all elements at the nm-scale as confirmed by a nearest-neighbor statistical analysis. Cr2+, CrO+,2+, CrO2+,2+, and CrO3+ molecular ions were detected, but no peaks associated with Cr3O+ or Cr2O5+ were observed as seen in synthetic chromite [8]. In NanoSIMS, Cr isotopic ratios must be corrected for isobaric overlaps from Fe, where 54Fe+ overlaps with 54Cr+ can be corrected by assuming a fixed 54Fe/56Fe ratio. This can be mitigated in APT, where the formation of molecular ion species is element-dependent. While ion species with different isotopes of the same element will have the same field evaporation behavior (e.g., 53CrO vs 54CrO), ion species of the same mass but from different elements may not (e.g., 54CrO vs 54FeO). Notably, we found that the peaks due to CrO2+ ions in the 82-86 Da mass region of UWCr-3 correspond to the terrestrial abundances in all isotopes, allowing for measurements of 54Cr/52Cr ratios. Peaks due to CrO2+ ions in the 33-35 Da mass region also correspond to natural abundances in all peaks when areas with Ga ion implantation are removed from the mass spectrum. Some mass regions have isobaric overlaps in only one or two Cr peaks, so the remaining peak ratios can be used for verification. The meteoritic chromite from Orgueil is also homogenous in all elements at the nm-scale and has a nearly identical mass spectrum to the UWCr-3 chromite, sharing all peaks with only minor differences in relative peak intensities and peak shapes, likely due to their small differences in elemental abundances (UWCr-3 is more Cr- and Mg-rich and more Fe-, Al-, and Ti-poor) and different operating conditions, respectively. As with UWCr-3, the peaks due to CrO2+ and CrO2+ ions correspond to natural abundances in all peaks. We were also able to confirm the Orgueil chromite is isotopically normal in Mg, Ti, and Fe. This is not unexpected for a meteoritic chromite of this size. Preparations of meteoritic chromites <200 nm in size are currently underway. [ABSTRACT FROM AUTHOR]

Introduction: Micrometeorites (MMs) are extraterrestrial particles 10 µm-2 mm in size, which represent in terms of mass the largest proportion of the flux of extraterrestrial material to fall on the Earth's surface (e.g. [1]). One of the most important objectives of MM studies is to identify their parent bodies. Here we identify six MM candidates in material dredged from the bottom of Lake Michigan during the Aquarius Project [2], a collaborative effort between the Adler Planetarium, the Shedd Aquarium, the Field Museum, and NASA to search, robotically, for fragments of a 600-pound meteorite that fell into the lake on Monday, February 6, 2017, 10 miles off the coast of Sheboygan, Wisconsin. Textural and chemical analyses were performed to confirm the grains' characterization as MMs and classify them. Methods: Six candidate MMs were mounted in 1-inch epoxy rounds and polished by hand to reveal cross sections. The petrology of polished MM sections were evaluated quantitatively using Raman spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS): Raman spectroscopy. The Field Museum's WITec alpha300R Raman spectroscopy system, equipped with a 532 nm green laser, was used to identify mineral phases in the MM candidates. At least two different spots were analyzed for each MM candidate sample. The averaged spectrum of the two spots was used for phase analysis. Identification of the mineralogical phases was done using RRUFF reference spectra and a calibration of olivine spectra for foresterite/fayalite molar compositions [3]. SEM/EDS. To evaluate petrological textures of cross sectioned MMs, high-resolution, backstattered electron (BSE) images were obtained using a TESCAN LYRA3 field emission SEM equipped with an in-column BSE detector in the Department of the Geophysical Sciences at the University of Chicago. To generate quantitative chemical maps (TruMaps), the SEM is also equipped with two Oxford Instruments XMax 80 silicon drift energy dispersive X-ray spectroscopy (EDS) detectors; these, coupled with Oxford Instruments AZTec software, were used for simultaneous determination of O, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Ni compositions. The system was calibrated with mineral and metal standards; the current stability and intensity is monitored using a Co standard and the beginning and end of each analysis session. Compositional analyses of the entire surface and of regions of interests (ROI) with individual phases (between 15-30 per grain) were made. For ROI analyses, freehand borders were drawn around regions of contiguous pixels as established by the overlayed Si and Mg maps. A quantitative chemical analysis was generated for each region. Results and Discussion: Five of the six grains were observed to have Raman spectra with peak positions consistent with either olivine, pyroxene, or both. One grain was organic in nature. MMs are dominantly composed of olivine and pyroxene (e.g. [4]); therefore, the five grains containing these minerals were considered MM candidates. SEM-BSE analyses supported the characterization of these grains as MMs, as all five grains appeared to be melted, silicate-(S-) type cosmic spherules, which are the most common cosmic spherule sub-type (e.g., [4, 5]). Four of the five had cryptocrystalline (Cc) to barred olivine (BO) textures, which may indicate that they derived from a chondritic parent body [6]. Quantitative EDS analyses were used to calculate fayalite (Fa) numbers for olivines (31.7±2.37, 26.6±2.68, 27.3±2.17; errors are 1SD) and ferrosilite (Fs) numbers of pyroxenes (21.8±2.27, 31.8±3.03, 26.4±2.18, 27.2±2.81, 22.8±5.85). Based on these calculations, all five MMs likely derived from equilibrated ordinary chondrite parent bodies, four of them specifically from the L or LL groups. The fifth MM, which has an irregular, granular pyroxene texture, is an unequilibrated ordinary chondrite because its Fs compositions are not uniform and span the range of all three ordinary chondrite groups. [ABSTRACT FROM AUTHOR]

Introduction: Remote sensing observations [1,2], laboratory experiments [3,4], and computational simulations [5] each predict that OH/H2O (hereafter water) can form in nominally anhydrous minerals on airless bodies due to space weathering. Space weathering is driven by solar wind irradiation and micrometeoroid bombardment and both mechanisms can change the optical, chemical, and microstructural properties of grains on airless surfaces [6]. Microstructural space weathering features include amorphous rims (upper ~100 nm), reduced and/or oxidized nanophase iron (npFe) particles, and vesicles that may form from the coalescence of solar wind implanted H and He [7]. Solar wind H+ ions can combine with O to form water species in surface minerals. Electron energy loss spectroscopy (EELS) has previously been used to identify such hydrogen and water species in the rims and vesicles of space weathered interplanetary dust particles and lunar regolith grains [8,9]. Atom probe tomography (APT) has also been used to identify hydrogen and water in the rims and vesicles of space weathered olivine from Itokawa [10] and lunar regolith grains [11,12,9]. However, understanding the abundance of hydrogen and water species in space weathered lunar grains and their relationship with microstructural space weathering features and mineralogy is still at an early stage. Here, we present results of coordinated EELS and APT analyses to understand the distribution of hydrogen and water in relation to microstructural space weathering features and mineralogy. Methods: In this work we analyzed grains from mature lunar mare soil 79221. Individual grains were transferred to an aluminum stub coated in carbon tape and subsequently sputter coated with Pt. We used scanning electron microscopy (SEM) to identify grains 100-200 µm in diameter that displayed vesicles or bubbles on their surface as evidence of solar wind irradiation. An agglutinate particle, clinopyroxene, olivine, plagioclase, and ilmenite grains were identified using energy dispersive x-ray spectroscopy (EDS). We then prepared electron transparent focused ion beam (FIB) cross sections of each grain with the Helios G4 UX Dual Beam FIB-SEM at Purdue University for analysis in the transmission electron microscope (TEM). Adjacent FIB sections were also collected from each grain to produce nanotips sharpened to have an apex radius of ~30 nm for APT analyses. High-resolution TEM (HRTEM) and high-angle annular dark field (HAADF) images were collected to characterize the microstructural space weathering features for FIB sections from each grain using the Thermo Scientific Themis Z monochromated and aberration-corrected TEM equipped with a Gatan Quantum 965 EELS detector at Purdue. Low-loss EELS spectra were collected as linescans across individual vesicles and within the amorphous rims of these grains to identify the presence of hydrogen and water via the hydrogen core scattering edge (H-K), energy gap of water (EG), and ionizing threshold of water (IT) features in the low-loss energy region. APT analyses were performed on tips made from each sample using the CAMECA LEAP 5000XS tomograph at Northwestern University. 3-D reconstructions of elemental information of each tip were analyzed and the presence of H, OH, and H2O were identified based on their mass-to-charge ratios. We then created depth profiles of each of these species to identify their change in concentration with depth. Results and Discussion: EELS analyses of an agglutinate grain revealed the presence of the H-K, IT, and EG features in both the space weathered rim and vesicles indicating the presence of hydrogen and water. APT analyses also identified the presence of H, OH, and H2O in the agglutinate grain and an olivine grain. Depth profiles in both grains reveal an enrichment in all three species in the space weathered rims which exhibit a steady decrease in concentration with depth into the grain. These profiles are similar in shape to the space weathered Itokawa olivine from [11] but differ from the observed shape in immature lunar ilmenite from [12]. The presence of H, OH, and H2O in vesicles and in space weathered rims provides evidence that solar wind implantation is a viable mechanism to form water on the lunar surface. Further EELS and APT measurements to characterize the relationship between water and microstructural features and comparisons in concentration profiles and abundance across mineralogy are ongoing. [ABSTRACT FROM AUTHOR]

Introduction and Methods: The alteration of the outer surfaces of grains on airless bodies by space weathering processes results in the production of new nanoscale features. Samples that have been exposed to this environment for a long time are termed mature. Apollo 17 sample Soil 79221 is classified as mature and has previously been used to study space weathering on the Moon, e.g. [1], and herein we present atom-probe tomography (APT) analyses of this soil to compare with our previously published data on submature soil 71501 [2]. In APT, atoms on a sample nanotip are field evaporated using a pulsed picosecond laser and their mass-to-charge-state ratio is measured via a positionsensitive detector, permitting a 3D reconstruction of the outermost ~100s of nanometers of space weathered material, e.g., [2,3]. Lift-outs were performed with a TESCAN LYRA3 FIB-SEM the University of Chicago close to the location of lamellae extracted for TEM for correlative analyses [4]. Prepared nanotips were analyzed with the CAMECA LEAP 5000XS tomograph at Northwestern University. Results: A total of 16 nanotips from agglutinate, plagioclase, olivine, and ilmenite were analyzed for their space weathering features, with nine providing useful data. Of particular interest are the olivine (Fig. 1) and ilmenite nanotips, as they exhibit zones of decreased atomic density which we interpret as vesicles and irregularly shaped defects. These features are prominent in our samples, and are also observed in TEM analyses [5]. The agglutinate nanotips are instead dominated by Fe-rich structures, including whisps of increased oxidation and a microphase Fe particle which are depleted in H relative to the rest of the sample [4]. The ilmenite nanotips contained some nanophase Fe particles, but heterogeneous Fe structures were not observed in the (Mg-rich) olivine nanotips. None of the analyzed samples preserved or included redeposition rims. Discussion: The olivine displays evidence of a complex structure of voids (Fig. 1). There is a fine-scale network of spaces that are much smaller than that of the round vesicles detected in the ilmenite nanotips. Like the vesicles, these void spaces are are filled with H species. Our previous APT study [2] identified a vesicle in submature lunar ilmenite with a small amount of 4He detected. This previously analyzed vesicle was similar in size to one of the vesicles we found in the mature lunar ilmenite, which also included a small 4He signal (5±2 atoms, 1s). Both analyses are missing at least three orders of magnitude of He atoms when compared to data from bulk analyses [6]. A burst of H detections at the top of vesicles indicates the opening and degassing of vesicles as the top of the nanotip field-evaporated during analysis. This suggests that the volatiles in the vesicle largely escaped into the vacuum without being analyzed, with only a small fraction ionized and detected. The number density of vesicles is much greater in the nanotips from the mature soils than the submature soil sample. Where the vesicle comprised a significant volume of the nanotip, the nanotips fractured before an analysis reached the lower half of the vesicle. Vesiculated textures present challenges to APT analysis. Interior voids cannot be filled with coating methods. The resulting non-hemispherical topography from vesicles alters the local electric field-evaporation dynamics in ways that can lead to instabilities and nanotip failure. Mature space-weathered samples are more challenging for APT than submature ones. [ABSTRACT FROM AUTHOR]

Introduction: We have measured Mo, Ru, and Ba isotopes in 49 presolar SiC and 21 graphite grains from the Murchison CM2 meteorite with the Chicago Instrument for Laser Ionization (CHILI) [1]. Each of these elements has seven stable isotopes, which allow study of the s-, r-, and p-processes. Correlated nucleosynthetic effects observed for several elements in single grains can provide tighter constraints for modeling of their parent stars. Furthermore, analyzing more than one element can help to decipher the role of contamination for these grains. Surface-related C and N contamination has been reported for SiC grains. It can often be identified by high-resolution imaging techniques and, at least, partially be removed by presputtering [2]. However, the removal of surface contamination by sputtering depends on particle and instrument geometry and might not be complete [3]. Samples and Analytical Procedures: All SiC grains were classified using C, N, and Si isotopic measurements with the NanoSIMS at the Max Planck Institute for Chemistry. Of the 49 grains, 40 were mainstream (MS), three Y, one Z, one X1, and four AB (one AB1 and three AB2). Only six of the graphite grains had NanoSIMS C and N data available. CHILI uses resonance ionization mass spectrometry (RIMS) to measure isotopic abundances from a cloud of atoms liberated from a sample via laser desorption, which are then selectively ionized with lasers tuned to elementspecific electronic transitions. CHILI's six tunable Ti:sapphire lasers allow simultaneous analysis of three elements, each with independent two-photon resonance ionization schemes. Mo and Ru isobars were separated by firing respective ionization lasers on alternate desorption laser shots. Ba ionization lasers were fired together with the Ru lasers. Mo and Ru data for 25 of the SiC grains and 11 of the graphite grains have been reported previously [4, 5]. Results and Discussion: Mo was detected in all 49 SiC grains, confirming previously observed trends for SiC grain types [6, 7], except for the AB1 grain, which showed a slight depletion in s-process isotopes. Ru was detected in 38 SiC grains (30 MS, three Y, one Z, and four AB) and showed s-process-dominated isotope patterns for all grains except for the AB1 grain, which also showed s-process depletions for Ru. The Ru and Mo s-process isotope enrichments for all other grains are strongly correlated. At least some Ba isotopes were detected in 23 of the SiC grains (20 MS, one X1, and two AB2), also confirming previously observed trends [7]. The X1 grain showed a neutron burst isotopic signature for Mo and a strong enrichment of 138Ba, as has been observed in X grains before [7, 8]. The graphite grains suffered from strong contamination with terrestrial or solar Mo, and the majority had no detectable Ru and Ba. We suspect the Mo contamination is related to the reagents used during separation of the grains from the host meteorite. However, four graphite grains showed clear s-process signatures in Mo and Ru, and three of them also in Ba. Depth profiles taken while ablating the grains revealed that s-process-enriched Mo is concentrated together with Ru and Ba in inner portions of the grains, while their surfaces predominately showed Mo contamination. Comparing Mo and Ru results for the grains revealed that some Mo contamination was still present even in the most s-process-enriched steps of the depth profiles, exemplifying the difficulty to completely remove contamination. For the SiC grains, however, Mo contamination is much less severe than for the graphite grains, which suggests that it is specific to the chemical separation of the graphite grains. Deviations from otherwise strongly correlated sprocess enrichments in Mo and Ru show that only a few SiC grains had been contaminated with Mo. Conversely, the observation that for SiC grains coming from asymptotic giant branch (AGB) stars, three isotope plots for Mo and Ru show data lying along straight lines going through the origin (solar), confirms that the initial composition of the grains' parent stars had fixed ratios of p- and r-process Mo and Ru isotope contributions and that these ratios are identical to those of the Solar System. Furthermore, the strong correlation between Mo and Ru isotope anomalies in M, Y, Z, and AB SiC grains indicates that s-process nucleosynthesis for these two elements happens simultaneously in AGB stars. [ABSTRACT FROM AUTHOR]