Untangling the Formation of Methoxymethanol (CH\u3csub\u3e3\u3c/sub\u3eOCH\u3csub\u3e2\u3c/sub\u3eOH) and Dimethyl Peroxide (CH\u3csub\u3e3\u3c/sub\u3eOOCH\u3csub\u3e3\u3c/sub\u3e) in Star-forming Regions

© 2019. The American Astronomical Society. All rights reserved.. Methoxymethanol (CH3OCH2OH) was recently detected toward the MM1 core in the high-mass star-forming region NGC 6334I. However, the underlying formation mechanisms of this complex organic molecule (COM) as well as its structural isomers ethylene glycol (HOCH2CH2OH) and the hitherto unobserved dimethyl peroxide (CH3OOCH3) are still elusive. Here, we report the very first confirmed synthesis of dimethyl peroxide - at various deuteration levels within interstellar analogous ices of D3-methanol (CD3OH) exposed to ionizing radiation at ultralow temperatures of 5 K. The discrimination of specific isomers is achieved by exploiting reflectron time-of-flight mass spectrometry coupled with isomer-selective photoionization of the subliming molecules in the temperature programmed desorption phase of the experiment. Based on the distribution of the identified species at distinct mass-to-charge ratios, we reveal primary and secondary reaction pathways to methoxymethanol, ethylene glycol, and dimethyl peroxide involving radical-radical recombination of methoxy (CH3O) and hydroxymethyl (CH2OH). Our findings help to constrain the formation mechanism of COMs detected within star-forming regions (methoxymethanol, ethylene glycol) and propose that the hitherto elusive dimethyl peroxide isomer represents an excellent candidate for future astronomical searches

The genetic epidemiology of joint shape and the development of osteoarthritis

Congruent, low-friction relative movement between the articulating elements of a synovial joint is an essential pre-requisite for sustained, efficient, function. Where disorders of joint formation or maintenance exist, mechanical overloading and osteoarthritis (OA) follow. The heritable component of OA accounts for ~ 50% of susceptible risk. Although almost 100 genetic risk loci for OA have now been identified, and the epidemiological relationship between joint development, joint shape and osteoarthritis is well established, we still have only a limited understanding of the contribution that genetic variation makes to joint shape and how this modulates OA risk. In this article, a brief overview of synovial joint development and its genetic regulation is followed by a review of current knowledge on the genetic epidemiology of established joint shape disorders and common shape variation. A summary of current genetic epidemiology of OA is also given, together with current evidence on the genetic overlap between shape variation and OA. Finally, the established genetic risk loci for both joint shape and osteoarthritis are discussed

Untersuchungen zur Multielement-Spurenanreicherung aus metallischen Mehrkomponentensystemen am Beispiel der Kupferlegierungen

Available from TIB Hannover: DW 8099 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Regenerative water sources on surfaces of airless bodies

© 2019, The Author(s), under exclusive licence to Springer Nature Limited. Spectroscopic signatures of water and hydroxyl radicals have been observed on the surfaces of asteroids1–3. As the lifetime of the exposed water ice is on the order of 104 to 106 yr in the inner asteroid belt4, there must be mechanisms to replenish the water in the absence of recent ice-exposing processes. However, such regenerative water-ice sources on asteroids are still elusive. Here we perform laboratory experiments by exposing the samples of the Murchison meteorite to energetic electrons and laser irradiation, simulating, respectively, the secondary electrons generated by the solar wind as well as galactic cosmic ray particles and the micrometeorites impacting on an asteroid. We find that a single simulated space-weathering component is insufficient and both are needed to regenerate water at low temperatures at the desired timescales. We propose that two main mechanisms can be the source of surface water on asteroids: low-temperature oxidation of organics and mineral dehydration