This site started in October 2013 as an experiment. Although never advertised except for an announcement on the MetSoc and the German Mineralogical Society mailing lists, the site is successful, but judge for yourself. The average stats are as follows:

Number of weekly abstracts posted: ~15-25  (total until today: 700 – congratulations to all who read all of them!)
Number of journals currently covered: 21

Monthly unique users: >300
Monthly views: ~2000

Weekly unique users: ~90
Weekly views: ~400

Daily unique users (weekdays): ~25
Daily views (weekdays): ~70-100

Users from Different countries per day: 8-10
Users from >50 countries visited the webpage at least once.

Weeks don’t add up to months and days don’t add up to weeks, as unique users are reported. Users visiting the webpage more than once a week are counted as one per week. In addition, 13 followers don’t visit the site, but get the posts via email. So these need to be added to the stats above.

I started this site as I wished for such a site myself. After almost 10 months, the site still is an experiment and its continuation is unclear. In any case, I just wanted to start it. For the moment, I will continue to update it for a couple more weeks. I will keep this post on top over the next week and would like to ask whether anyone else likes this page and would be interested in continuing it. I am happy to provide any further information to anyone who is interested in taking over. Please also indicate your interest, if you could imagine participating in this part time, in case a number of people would want to share the updating process. And please also keep in mind that this should be a longer time commitment.

However this turns out, it’s been a nice an interesting experiment in all its facets for about a year, and I enjoyed updating it during this time.

best,  Dominik

Stuart Ross Taylor

Research School of Earth Sciences, Australian National University. Canberra, Australia

Recent geochemical and geophysical data from the Moon enable a revision of earlier interpretations regarding lunar origin, structure and bulk composition. Earth and Moon show many similarities among their isotopic compositions, but they have evolved in totally dissimilar ways, probably related to the deficiency of water in the Moon as well as the vast differences in size and internal pressure. Although some global geochemical trends such as volatile depletion based on K/U ratios have been established, current lunar samples come from differentiated regions, making the establishment of a bulk composition more reliant on bulk geophysical properties or isotopic similarities although it remains unclear how the latter relate to whole Moon composition. The lack of fractionation effects among the refractory and super-refractory elements indicates that the proto-lunar material seems unlikely to have been vaporized while the depletion of volatile elements may place lower limits on proto-lunar temperatures. The apparent lack of geochemical evidence of an impacting body enables other possible impactors, such as comets, to be considered.

Reference
Taylor SR (in press) The Moon re-examined. Geochimica et Cosmochimica Acta
[doi:10.1016/j.gca.2014.06.031]
Copyright Elsevier

Link to Article

José C. Aponte^a,b, Jason P. Dworkin^b, Jamie E. Elsila^b

^aNASA Postdoctoral Program at NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
^bNASA Goddard Space Flight Center and Goddard Center for Astrobiology, Greenbelt, Maryland 20771, USA

The study of meteoritic organic compounds provides a unique window into the chemical inventory of the early Solar System and prebiotic chemistry that may have been important for the origin of life on Earth. Multiple families of organic compounds have been extracted from the Murchison meteorite, which is one of the most thoroughly studied carbonaceous chondrites. The amino acids extracted from Murchison have been extensively analyzed, including measurements of non-terrestrial stable isotopic ratios and discoveries of L-enantiomeric excesses for α-dialkyl amino acids, notably isovaline. However, although the isotopic signatures of bulk amine-containing fractions have been measured, the isotopic ratios and enantiomeric composition of individual aliphatic amines, compounds that are chemically related to amino acids, remain unknown. Here, we report a novel method for the extraction, separation, identification and quantitation of aliphatic monoamines extracted from the Murchison meteorite. Our results show a complete suite of structural isomers, with a larger concentration of methylamine and ethylamine and decreasing amine concentrations with increasing carbon number. The carbon isotopic compositions of fourteen meteoritic aliphatic monoamines were measured, with δ¹³C values ranging from +21 to +129‰, showing a decrease in ¹³C with increasing carbon number, a relationship that may be consistent with the chain elongation mechanism under kinetic control previously proposed for meteoritic amino acids. We also found the enantiomeric composition ofsec-butylamine, a structural analog to isovaline, was racemic within error, while the isovaline extracted from the same Murchison piece showed an L-enantiomeric excess of 9.7%; this result suggested that processes leading to enantiomeric excess in the amino acid did not affect the amine. We used these collective data to assess the primordial synthetic origins of these meteoritic aliphatic amines and their potential linkage to meteoritic amino acids.

Reference
Aponte JC, Dworkin JP and Elsila JE (in press) Assessing the origins of aliphatic amines in the murchison meteorite from their compound-specific carbon isotopic ratios and enantiomeric composition. Geochimica et Cosmochimica Acta
[doi:10.1016/j.gca.2014.06.035]
Copyright Elsevier

Link to Article

Kenji Furuya^1,2 and Yuri Aikawa¹

¹Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501, Japan
²Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands

We study the influence of the turbulent transport on ice chemistry in protoplanetary disks, focusing on carbon- and nitrogen-bearing molecules. Chemical rate equations are solved with the diffusion term, mimicking the turbulent mixing in the vertical direction. Turbulence can bring ice-coated dust grains from the midplane to the warm irradiated disk surface, and the ice mantles are reprocessed by photoreactions, thermal desorption, and surface reactions. The upward transport decreases the abundance of methanol and ammonia ices at r  30 AU because warm dust temperature prohibits their reformation on grain surfaces. This reprocessing could explain the smaller abundances of carbon and nitrogen bearing molecules in cometary coma than those in low-mass protostellar envelopes. We also show the effect of mixing on the synthesis of complex organic molecules (COMs) in two ways: (1) transport of ices from the midplane to the disk surface and (2) transport of atomic hydrogen from the surface to the midplane. The former enhances the COMs formation in the disk surface, while the latter suppresses it in the midplane. Then, when mixing is strong, COMs are predominantly formed in the disk surface, while their parent molecules are (re)formed in the midplane. This cycle expands the COMs distribution both vertically and radially outward compared with that in the non-turbulent model. We derive the timescale of the sink mechanism by which CO and N2 are converted to less volatile molecules to be depleted from the gas phase and find that the vertical mixing suppresses this mechanism in the inner disks.

Reference
Furuya K and Aikawa Y (2014) Reprocessing of Ices in Turbulent Protoplanetary Disks: Carbon and Nitrogen Chemistry. The Astrophysical Journal 790:97.
[doi:10.1088/0004-637X/790/2/97]

Link to Article