Browsing by Subject "PRECURSOR"

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  • Mattinen, Miika; Hatanpää, Timo; King, Peter J.; Meinander, Kristoffer; Mizohata, Kenichiro; Jalkanen, Pasi; Räisänen, Jyrki; Ritala, Mikko; Leskelä, Markku (2019)
    Tungsten disulfide (WS2) is a semiconducting 2D material, which is gaining increasing attention in the wake of graphene and MoS2 owing to its exciting properties and promising performance in a multitude of applications. Herein, the authors deposited WSx thin films by atomic layer deposition using W-2(NMe2)(6) and H2S as precursors. The films deposited at 150 degrees C were amorphous and sulfur deficient. The amorphous films crystallized as WS2 by mild postdeposition annealing in H2S/N-2 atmosphere at 400 degrees C. Detailed structural characterization using Raman spectroscopy, x-ray diffraction, and transmission electron microscopy revealed that the annealed films consisted of small (
  • Tenhovirta, Salla Aino Maaria; Kohl, Lukas; Koskinen, Markku; Patama, Marjo Riitta; Lintunen, Anna; Zanetti, Alessandro; Lilja, Rauna Anniina Ilmatar; Pihlatie, Mari (2022)
    Plants are recognized as sources of aerobically produced methane (CH4), but the seasonality, environmental drivers and significance of CH4 emissions from the canopies of evergreen boreal trees remain poorly understood. We measured the CH4 fluxes from the shoots of Pinus sylvestris (Scots pine) and Picea abies (Norway spruce) saplings in a static, non-steady-state chamber setup to investigate if the shoots of boreal conifers are a source of CH4 during spring. We found that the shoots of Scots pine emitted CH4 and these emissions correlated with the photosynthetically active radiation. For Norway spruce, the evidence for CH4 emissions from the shoots was inconclusive. Our study shows that the canopies of evergreen boreal trees are a potential source of CH4 in the spring and that these emissions are driven by a temperature-by-light interaction effect of solar radiation either directly or indirectly through its effects on tree physiological processes.
  • Summanen, Milla; Back, Susanne; Voipio, Juha; Kaila, Kai (2018)
    Mammalian birth is accompanied by a period of obligatory asphyxia, which consists of hypoxia (drop in blood O-2 levels) and hypercapnia (elevation of blood CO2 levels). Prolonged, complicated birth can extend the asphyxic period, leading to a pathophysiological situation, and in humans, to the diagnosis of clinical birth asphyxia, the main cause of hypoxic-ischemic encephalopathy (HIE). The neuroendocrine component of birth asphyxia, in particular the increase in circulating levels of arginine vasopressin (AVP), has been extensively studied in humans. Here we show for the first time that normal rat birth is also accompanied by an AVP surge, and that the fetal AVP surge is further enhanced in a model of birth asphyxia, based on exposing 6-day old rat pups to a gas mixture containing 4% O-2 and 20% CO2 for 45 min. Instead of AVP, which is highly unstable with a short plasma half-life, we measured the levels of copeptin, the C-terminal part of prepro-AVP that is biochemically much more stable. In our animal model, the bulk of AVP/copeptin release occurred at the beginning of asphyxia (mean 7.8 nM after 15 min of asphyxia), but some release was still ongoing even 90 min after the end of the 45 min experimental asphyxia (mean 1.2 nM). Notably, the highest copeptin levels were measured after hypoxia alone (mean 14.1 nM at 45 min), whereas copeptin levels were low during hypercapnia alone (mean 2.7 nM at 45 min), indicating that the hypoxia component of asphyxia is responsible for the increase in AVP/copeptin release. Alternating the O-2 level between 5 and 9% (CO2 at 20%) with 5 min intervals to mimic intermittent asphyxia during prolonged labor resulted in a slower but quantitatively similar rise in copeptin (peak of 8.3 nM at 30 min). Finally, we demonstrate that our rat model satisfies the standard acid-base criteria for birth asphyxia diagnosis, namely a drop in blood pH below 7.0 and the formation of a negative base excess exceeding -11.2 mmol/l. The mechanistic insights from our work validate the use of the present rodent model in preclinical work on birth asphyxia.
  • Dunn, Cory D.; Paavilainen, Ville O. (2019)
    Many functions of eukaryotic cells are compartmentalized within membrane-bound organelles. One or more cis-encoded signals within a polypeptide sequence typically govern protein targeting to and within destination organelles. Perhaps unexpectedly, organelle targeting does not occur with high specificity, but instead is characterized by considerable degeneracy and inefficiency. Indeed, the same peptide signals can target proteins to more than one location, randomized sequences can easily direct proteins to organelles, and many enzymes appear to traverse different subcellular settings across eukaryotic phylogeny. We discuss the potential benefits provided by flexibility in organelle targeting, with a special emphasis on horizontally transferred and de novo proteins. Moreover, we consider how these new organelle residents can be protected and maintained before they contribute to the needs of the cell and promote fitness.