Геохимическая зональность скарново-золоторудных месторождений Западной Сибири

Исследована геохимическая зональность золото-скарновых месторождений Западной Сибири. Выявлено концентрически зональное строение аномальных структур геохимических полей, сопровождающих изученные месторождения. Определены группы концентрирующихся и деконцентрирующихся (по отношению к золоторудным телам) элементов. Установлена тесная пространственная связь золота с комплексом халькофильных элементов-спутников, набор которых может изменяться в ходе эволюции гидротермальной системы. Набор деконцентрирующихся элементов, накапливающихся по периферии рудных тел, в целом стандартный и включает в себя Ni, Co, Cr, V, Ba, Mn. Проведено обсуждение генетических аспектов выявленной геохимической зональности

New Insights into Cosmic Ray induced Biosignature Chemistry in Earth-like Atmospheres

With the recent discoveries of terrestrial planets around active M-dwarfs, destruction processes masking the possible presence of life are receiving increased attention in the exoplanet community. We investigate potential biosignatures of planets having Earth-like (N$_2$-O$_2$) atmospheres orbiting in the habitable zone of the M-dwarf star AD Leo. These are bombarded by high energetic particles which can create showers of secondary particles at the surface. We apply our cloud-free 1D climate-chemistry model to study the influence of key particle shower parameters and chemical efficiencies of NOx and HOx production from cosmic rays. We determine the effect of stellar radiation and cosmic rays upon atmospheric composition, temperature, and spectral appearance. Despite strong stratospheric O$_3$ destruction by cosmic rays, smog O$_3$ can significantly build up in the lower atmosphere of our modeled planet around AD Leo related to low stellar UVB. N$_2$O abundances decrease with increasing flaring energies but a sink reaction for N$_2$O with excited oxygen becomes weaker, stabilizing its abundance. CH$_4$ is removed mainly by Cl in the upper atmosphere for strong flaring cases and not via hydroxyl as is otherwise usually the case. Cosmic rays weaken the role of CH$_4$ in heating the middle atmosphere so that H$_2$O absorption becomes more important. We additionally underline the importance of HNO$_3$ as a possible marker for strong stellar particle showers. In a nutshell, uncertainty in NOx and HOx production from cosmic rays significantly influences biosignature abundances and spectral appearance.Comment: Manuscript version after addressing all referee comments. Published in Ap

Unconventional Magnetization below 25 K in Nitrogen-doped Diamond provides hints for the existence of Superconductivity and Superparamagnetism

The magnetization of nitrogen-doped single crystalline diamond bulk samples shows unconventional field and temperature hysteresis loops at T ≲ 25 K. The results suggest the existence of superparamagnetic and superconducting regions in samples with nitrogen concentration <200 ppm. Both phases vanish at temperatures above 25 K where the samples show diamagnetic behavior similar to undoped diamond. The observation of superparamagnetism and superconductivity is attributed to the nitrogen doping and to the existence of defective regions. From particle-induced X-ray emission with ppm resolution we rule out that the main observations below 25 K are due to magnetic impurities. We investigated also the magnetic properties of ferromagnetic/high-temperature superconducting oxide bilayers. The magnetization results obtained from those bilayers show remarkable similarities to the ones in nitrogen-doped diamond

Verbesserung der Vergleichbarkeit der Öko-Landessortenversuche mit der BSL

In den Jahren 2010 bis 2012 wurden auf 25 langjährig ökologisch bewirtschafteten Flächen bundesweit Winterweizen Sortenversuche in Exaktanlage durchgeführt. Darin enthalten war ein auf allen Standorten identisches Sortiment bestehend aus vier Ökozüchtungen. Von insgesamt 23 Sorten wurden detailiertere Auswertungen vorgenommen. Das Vorhaben gliedert sich in mehrere Schritte. Das bestehende Datentransfer- und Datenbanksystem PIAF (Planung, Information und Auswertung im Feldversuchswesen) wurde um speziell für den ökologischen Landbau bedeutsame zusätzliche Merkmale, die auf die besonderen Bedürfnisse des ökologischen Landbaus zugeschnitten wurden, ergänzt. Zusätzlich wurden Bonituren wie Bodendeckungsgrad (in %) oder Blattstellung sowie die Bestimmung des Feuchtklebergehaltes vorgenommen. Die Auswertung erfolgte mit Hilfe der Hohenheim-Gülzower-Methode. Dazu wurden Anbaugebiete, bestehend aus bis zu sechs Versuchsstandorten gebildet. Diese Vorgehensweise wird Grundlage einer speziellen, nunmehr beschlossenen Ökowertprüfung sein. Es zeigt sich, dass die Ökozüchtungen sich in Ertrag wie Qualität erheblich von den konventionell gezüchteten Sorten unterscheiden. In einem zweiten Teil des Vorhabens wurde an 14 Standorten die Lichttransmission in den Beständen gemessen und mit den geschätzten Werten des Bodendeckungsgrades verglichen. NIRS-Untersuchungen zeigten, dass neben dem Gehalt an Rohprotein auch der Feuchtkleber hinreichend gut geschätzt werden kann

Factors influencing the honeydew production of Ultracoelostoma scale insects in New Zealand beech forests

In New Zealand Nothofagus forests Ultracoelostoma spp. scale insects produce abundant honeydew which is an important food for native birds, invertebrates, sooty mould, and invasive wasps. Previous models have underestimated honeydew production, potentially because they do not allow for the flow rate of honeydew to vary between insects based on characteristics such as insect size. This research focused on honeydew production rates at the level of the individual insect, how insect characteristics influence production, and whether the strongest predictor of production, ambient air temperature, acts directly on insects or indirectly via effects on trees. Finding out how temperature acts to increase honeydew production will better reveal the physiological processes involved. The study site was Mt. Richardson, Canterbury. In the first part of this study, during March-April 2012, daily mean ambient temperature (range 7.2 – 15.1 °C) had a positive relationship with honeydew production. Insect size positively influenced production at high temperatures, with the largest insects producing 0.296 µg insect⁻¹ h⁻¹ and the smallest insects 0.115 µg insect⁻¹ h⁻¹ at the highest temperature, 15.1 °C. In the second part of this study, during October 2012-January 2013, I manipulated temperature on areas of tree trunk using reflective or clear plastic covers, creating a mean temperature difference of 1.1 °C. However, the effects of tree and insect temperature could not be separated as there was no relationship between either manipulated or ambient temperature and honeydew production. These results show that honeydew production is influenced by individual insect characteristics. This will be important for future models of production. The results also show contradictory effects of temperature on honeydew production, perhaps because of interactions with other unknown factors, which bears further investigation

Detectability of biosignatures on LHS 1140 b

Terrestrial extrasolar planets around low-mass stars are prime targets when searching for atmospheric biosignatures with current and near-future telescopes. The habitable-zone Super-Earth LHS 1140 b could hold a hydrogen-dominated atmosphere and is an excellent candidate for detecting atmospheric features. In this study, we investigate how the instellation and planetary parameters influence the atmospheric climate, chemistry, and spectral appearance of LHS 1140 b. We study the detectability of selected molecules, in particular potential biosignatures, with the upcoming James Webb Space Telescope (JWST) and Extremely Large Telescope (ELT). In a first step we use the coupled climate-chemistry model, 1D-TERRA, to simulate a range of assumed atmospheric chemical compositions dominated by H$_2$ and CO$_2$. Further, we vary the concentrations of CH$_4$ by several orders of magnitude. In a second step we calculate transmission spectra of the simulated atmospheres and compare them to recent transit observations. Finally, we determine the observation time required to detect spectral bands with low resolution spectroscopy using JWST and the cross-correlation technique using ELT. In H$_2$-dominated and CH$_4$-rich atmospheres O$_2$ has strong chemical sinks, leading to low concentrations of O$_2$ and O$_3$. The potential biosignatures NH$_3$, PH$_3$, CH$_3$Cl and N$_2$O are less sensitive to the concentration of H$_2$, CO$_2$ and CH$_4$ in the atmosphere. In the simulated H$_2$-dominated atmosphere the detection of these gases might be feasible within 20 to 100 observation hours with ELT or JWST, when assuming weak extinction by hazes. If further observations of LHS 1140 b suggest a thin, clear, hydrogen-dominated atmosphere, the planet would be one of the best known targets to detect biosignature gases in the atmosphere of a habitable-zone rocky exoplanet with upcoming telescopes.Comment: 18 pages, 11 figure

ИССЛЕДОВАНИЕ УСЛОВИЙ ЗАЛЕГАНИЯ, СОСТАВА И СВОЙСТВ УРАНОВЫХ МЕСТОРОЖДЕНИЙ МОНГОЛИИ

Представлены результаты промышленных и лабораторных исследований условий залегания, состава и свойств урановых месторождений Монголии. Выполнены механические, геофизические и геохимические исследования вещественных и радиологических свойств урановых ру