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Type: Article × Subject: recovery ×

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Now showing 1 - 3 of 3
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    Recovery of release cloud from laser shock-loaded graphite and hydrocarbon targets: in search of diamonds
    (Bristol : IOP Publ., 2022) Schuster, A.K.; Voigt, K.; Klemmed, B.; Hartley, N.J.; Lütgert, J.; Zhang, M.; Bähtz, C.; Benad, A.; Brabetz, C.; Cowan, T.; Döppner, T.; Erb, D.J.; Eychmüller, A.; Facsko, S.; Falcone, R.W.; Fletcher, L.B.; Frydrych, S.; Ganzenmüller, G.C.; Gericke, D.O.; Glenzer, S.H.; Grenzer, J.; Helbig, U.; Hiermaier, S.; Hübner, R.; Laso Garcia, A.; Lee, H.J.; MacDonald, M.J.; McBride, E.E.; Neumayer, P.; Pak, A.; Pelka, A.; Prencipe, I.; Prosvetov, A.; Rack, A.; Ravasio, A.; Redmer, R.; Reemts, D.; Rödel, M.; Schoelmerich, M.; Schumacher, D.; Tomut, M.; Turner, S.J.; Saunders, A.M.; Sun, P.; Vorberger, J.; Zettl, A.; Kraus, D.
    This work presents first insights into the dynamics of free-surface release clouds from dynamically compressed polystyrene and pyrolytic graphite at pressures up to 200 GPa, where they transform into diamond or lonsdaleite, respectively. These ejecta clouds are released into either vacuum or various types of catcher systems, and are monitored with high-speed recordings (frame rates up to 10 MHz). Molecular dynamics simulations are used to give insights to the rate of diamond preservation throughout the free expansion and the catcher impact process, highlighting the challenges of diamond retrieval. Raman spectroscopy data show graphitic signatures on a catcher plate confirming that the shock-compressed PS is transformed. First electron microscopy analyses of solid catcher plates yield an outstanding number of different spherical-like objects in the size range between ten(s) up to hundreds of nanometres, which are one type of two potential diamond candidates identified. The origin of some objects can unambiguously be assigned, while the history of others remains speculative.
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    Seasonal changes in dendrometer-derived stem variation in apple trees grown in temperate climate
    (Lublin : IA PAS, 2022) Rezaei, Yousef; Zude-Sasse, Manuela; Herppich, Werner
    Studies of daily changes in tree trunk diameter provide valuable information concerning growth patterns and their relationships with varying environmental conditions. To date, very few experiments with fruit trees evaluated the effects of climate variation on trunk shrinkage and the duration of the contraction and recovery phases and of growth. In this study, electronic dendrometers continuously monitored trunk diameter and trunk water storage dynamics of drip-irrigated ‘Gala’ apple trees (Malus x domestica Borkh.) during three growing seasons, which differed significantly in temperature, precipitation, air humidity and solar irradiation. It was found that trunk diameter and meteorological variables were closely related, even when excluding the effects of soil water limitations. During each growing season, the durations of the daily contraction phase began to increase with increasing water vapour partial pressure deficit, and decreased again in autumn, when vapour partial pressure decreased. Throughout the season, the duration of the growth phase tended to change inversely to that of both contraction and recovery phase. The relationship between maximum trunk shrinkage and vapour partial pressure was higher post than pre harvest for all years studied. The duration of contraction, recovery, and growth phases may provide valuable information concerning seasonal changes and environmental drivers of water storage dynamics in apple trees.
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    Waste Recycling in Thermoelectric Materials
    (Weinheim : Wiley-VCH, 2020) Bahrami, Amin; Schierning, Gabi; Nielsch, Kornelius
    Thermoelectric (TE) technology enables the efficient conversion of waste heat generated in homes, transport, and industry into promptly accessible electrical energy. Such technology is thus finding increasing applications given the focus on alternative sources of energy. However, the synthesis of TE materials relies on costly and scarce elements, which are also environmentally damaging to extract. Moreover, spent TE modules lead to a waste of resources and cause severe pollution. To address these issues, many laboratory studies have explored the synthesis of TE materials using wastes and the recovery of scarce elements from spent modules, e.g., utilization of Si slurry as starting materials, development of biodegradable TE papers, and bacterial recovery and recycling of tellurium from spent TE modules. Yet, the outcomes of such work have not triggered sustainable industrial practices to the extent needed. This paper provides a systematic overview of the state of the art with a view to uncovering the opportunities and challenges for expanded application. Based on this overview, it explores a framework for synthesizing TE materials from waste sources with efficiencies comparable to those made from raw materials.