An Update on Eukaryotic Viruses Revived from Ancient Permafrost.

One quarter of the Northern hemisphere is underlain by permanently frozen ground, referred to as permafrost. Due to climate warming, irreversibly thawing permafrost is releasing organic matter frozen for up to a million years, most of which decomposes into carbon dioxide and methane, further enhancing the greenhouse effect. Part of this organic matter also consists of revived cellular microbes (prokaryotes, unicellular eukaryotes) as well as viruses that have remained dormant since prehistorical times.

Metagenomic survey of the microbiome of ancient Siberian permafrost and modern Kamchatkan cryosols.

In the context of global warming, the melting of Arctic permafrost raises the threat of a reemergence of microorganisms some of which were shown to remain viable in ancient frozen soils for up to half a million years. In order to evaluate this risk, it is of interest to acquire a better knowledge of the composition of the microbial communities found in this understudied environment. Here, we present a metagenomic analysis of 12 soil samples from Russian Arctic and subarctic pristine areas: Chukotka, Yakutia and Kamchatka, including nine permafrost samples collected at various depths.

Greenhouse gas production and lipid biomarker distribution in Yedoma and Alas thermokarst lake sediments in Eastern Siberia.

Permafrost thaw leads to thermokarst lake formation and talik growth tens of meters deep, enabling microbial decomposition of formerly frozen organic matter (OM). We analyzed two 17-m-long thermokarst lake sediment cores taken in Central Yakutia, Russia. One core was from an Alas lake in a Holocene thermokarst basin that underwent multiple lake generations, and the second core from a young Yedoma upland lake (formed ~70 years ago) whose sediments have thawed for the first time since deposition.

In situ elemental analysis and failures detection during additive manufacturing process utilizing laser induced breakdown spectroscopy.

The feasibility of in situ quantitative multielemental analysis and production failures detection by laser induced breakdown spectroscopy (LIBS) has been demonstrated during direct energy deposition process in additive manufacturing. Compact LIBS probe was developed and equipped with the laser cladding head installed at industrial robot for real-time chemical quantitative analysis of key components (Ni, W) during the synthesis of high wear resistant coatings of nickel alloy reinforced with tungsten carbide particles. Owing to non-uniform distribution of tungsten carbide grains in the upper surface layer the only acceptable choice for LIBS sampling was made to the melt pool at growing clad.

Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

A new approach combining Raman spectrometry and laser induced breakdown spectrometry (LIBS) within a single laser event was suggested. A pulsed solid state Nd:YAG laser running in double pulse mode (two frequency-doubled sequential nanosecond laser pulses with dozens microseconds delay) was used to combine two spectrometry methods within a single instrument (Raman/LIBS spectrometer). First, a low-energy laser pulse (power density far below ablation threshold) was used for Raman measurements while a second powerful laser pulse created the plasma suitable for LIBS analysis.