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1
Pyasetska, Svitlana. "Duration of the phase of preservation and destruction in cases of deposits of iced categories of SHP (spontaneous) in the territory of Ukraine in the month of the cold period of the year during 1991–2016." Physical Geography and Geomorphology 99, no. 1-2 (2020): 62–72. http://dx.doi.org/10.17721/phgg.2020.1-2.07.
Повний текст джерелаАнотація:
The article deals with the question of the duration of the preservation and destruction phase which were calculated for ice-free periods of the category of SHP and were observed on the territory of Ukraine in the month of the cold period of the year during certain periods 1991–2000, 2001-2010 and 2011-2016. It was established that the duration of the preservation phase and the destruction of ice-oily deposits in the category of SHP is very volatile and ranges from near-instant destruction after reaching a maximum diameter of several hours or several dozen hours. However, there are cases where the duration of this phase can be 4 days in a row and more than several hundred hours. The study found that for the most part during the investigated period, the glacial deposits of the SHP category were dominated by non-prolonged conservation and degradation phases, regardless of the region where the sediment was formed, and regardless of the overall duration of the sediment itself, which could be significant. In 2001–2010 and 2011–2016, unlike in the period of 1991-2000, in January and December, the number of cases of ice-ousted categories of SHP increased. Moreover, in January, especially in 2011–2016, the number of cases with a significant duration of the phase of preservation and destruction of ice deposits of the category of SHP was increased. From the above we can draw a number of conclusions, namely: – During 1991–2000, the phases of preservation and destruction of ice-clay deposits in the category of HPAs were mostly non-prolonged and ranging from several hours to several dozen hours. The most prolonged phases of preservation and destruction of deposits of iced ice of category SHHA were in cases of sediments in Lower Zirgozakh in January 1996, in March 1998 in Kropivnitsky and most often in November 1999 in Gadyach, Dolynska, Komissarivka, Mariupol, Prisheby, and also in 2000 It is in Novodnistrovsk, Separate, Lyubashevtsi, Serbs, Voznesensk, December 1997 in Loshkarivka, Kryvy Rih, Nikopol, Lyubashevtsi, Prisheb and especially in Donetsk. – In 2001–2010, the amount of ice-cream deposits in the category of SHP increased slightly. In addition, the duration of the preservation and destruction phase compared to the previous period changed slightly, taking into account the individual months. So, in January, along with the relatively long phases of preservation and destruction of ice-clay deposits of the category of SHP (up to several dozen hours), in 2010 deposits with very long phases of conservation and destruction in Debaltsevo and especially in Mysovoye were observed. In December of this period, the long phases of preservation and destruction of deposits of iced ice of category SHP were observed in 2004 in Dar’yivka, and in 2008 in Vinnitsa and Ovruch. In the remaining months, the duration of the conservation and destruction phase was overwhelmingly within a few hours, at least to several dozen golds (11–25 hours) – Unlike in the years 1991-2000 and 2001-2010, in January the number of cases of ice deposits of the category of SHP increased in the five-year period of 2011–2016. They met practically in most regions. Significantly increased cases with them, where the duration of the preservation and destruction phase was significant and exceeded the duration of 4 consecutive days. Such cases were observed in January 2013 in Rava-Ruska, Kamianets Buzka and Poltava, in January 2014 – in Rava-Ruska, Ternopil, Amvrosiyivka, Rosdilna, Mykolayiv, Ochakov, and Simferopol. In December 2012, a similar accident happened in Evpatoria.
2
Bachler, Johannes, Johannes Giebelmann, and Thomas Loerting. "Experimental evidence for glass polymorphism in vitrified water droplets." Proceedings of the National Academy of Sciences 118, no. 30 (July 23, 2021): e2108194118. http://dx.doi.org/10.1073/pnas.2108194118.
Повний текст джерелаАнотація:
The nature of amorphous ices has been debated for more than 35 years. In essence, the question is whether they are related to ice polymorphs or to liquids. The fact that amorphous ices are traditionally prepared from crystalline ice via pressure-induced amorphization has made a clear distinction tricky. In this work, we vitrify liquid droplets through cooling at ≥106 K ⋅ s−1 and pressurize the glassy deposit. We observe a first order–like densification upon pressurization and recover a high-density glass. The two glasses resemble low- and high-density amorphous ice in terms of both structure and thermal properties. Vitrified water shows all features that have been reported for amorphous ices made from crystalline ice. The only difference is that the hyperquenched and pressurized deposit shows slightly different crystallization kinetics to ice I upon heating at ambient pressure. This implies a thermodynamically continuous connection of amorphous ices with liquids, not crystals.
3
Blake, D. F., L. Allamandola, S. Sandford, D. Hudgins, and F. Freund. "Type II Clathrate Hydrate Formation in Cometary Ice Analogs in Vacuo." Symposium - International Astronomical Union 150 (1992): 437–38. http://dx.doi.org/10.1017/s0074180900090616.
Повний текст джерелаАнотація:
Clathrate Hydrates can be formed under high vacuum conditions by annealing vapor-deposited amorphous ices of the appropriate composition. When astrophysically significant H2O:CH3OH ices are deposited and annealed, Type II Clathrate Hydrates are formed which can hold up to 6 mole % large guest molecules such as methanol and 12 mole % small guest molecules such as CO2 and CO. The solid state transformation of amorphous mixed molecular ice into crystalline clathrate hydrate and its sublimation at higher temperatures may serve to explain heretofore anomalous mechanical and gas release properties observed in cometary ices and laboratory ice analog experiments.
4
Hu, Yuyao, Sihua Guo, Richang Xian, Xingbo Han, Zhongyi Yang, and Ying Wu. "Flashover Performance and Process of Suspension Insulator Strings Artificially Covered with Snow." Energies 11, no. 11 (October 26, 2018): 2916. http://dx.doi.org/10.3390/en11112916.
Повний текст джерелаАнотація:
Snow accumulates on the surface of insulator string, causing a decrease in its electrical performance, seriously threatening the reliable operation of the power grid. Most previous studies have focused on iced insulators; however, there is a lack of research on snow-covered insulators. In this paper, to reveal the influencing mechanism that snow has on the electrical characteristics of insulator string, based on an artificial snowing test in a chamber, the effects of equivalent salt deposit density, applied voltage type, and snow thickness on the flashover performance of snow-covered insulators are analyzed, and the flashover process is investigated. The results show that the relationship between the arc flashover gradient and the equivalent salt deposit density is a power function with a negative exponent, which is similar to that of polluted and ice-covered insulator strings. For the insulator strings with the same snow accretion, the direct current (DC) arc flashover gradient is lower than the alternating current (AC) arc flashover gradient. The relationship between arc flashover gradient and snow thickness is also a power function. The formation of a dry band during the flashover of snow-covered insulator string is similar to the flashover of the polluted insulator, and the arc propagation along the surface of the snow-covered insulator is similar to the flashover of the iced insulator.
5
Leu, Ming-Taun, and Leon F. Keyser. "Vapor-deposited water and nitric acid ices: Physical and chemical properties." International Reviews in Physical Chemistry 28, no. 1 (January 2009): 53–109. http://dx.doi.org/10.1080/01442350802617129.
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6
McNeill, V. F., A. M. Grannas, J. P. D. Abbatt, M. Ammann, P. Ariya, T. Bartels-Rausch, F. Domine, et al. "Organics in environmental ices: sources, chemistry, and impacts." Atmospheric Chemistry and Physics Discussions 12, no. 4 (April 10, 2012): 8857–920. http://dx.doi.org/10.5194/acpd-12-8857-2012.
Повний текст джерелаАнотація:
Abstract. The physical, chemical, and biological processes involving organics in ice in the environment impact a number of atmospheric and biogeochemical cycles. Organic material in snow or ice may be biological in origin, deposited from aerosols or atmospheric gases, or formed chemically in situ. In this manuscript, we review the current state of knowledge regarding the sources, properties, and chemistry of organic materials in environmental ices. Several outstanding questions remain to be resolved and fundamental data gathered before a comprehensive, accurate model of organic species in the cryosphere will be possible. For example, more information is needed regarding the quantitative impacts of chemical and biological processes, ice morphology, and snow formation on the fate of organic material in cold regions. Interdisciplinary work at the interfaces of chemistry, physics and biology is needed in order to fully characterize the nature and evolution of organics in the cryosphere and predict the effects of climate change on the Earth's carbon cycle.
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McNeill, V. F., A. M. Grannas, J. P. D. Abbatt, M. Ammann, P. Ariya, T. Bartels-Rausch, F. Domine, et al. "Organics in environmental ices: sources, chemistry, and impacts." Atmospheric Chemistry and Physics 12, no. 20 (October 24, 2012): 9653–78. http://dx.doi.org/10.5194/acp-12-9653-2012.
Повний текст джерелаАнотація:
Abstract. The physical, chemical, and biological processes involving organics in ice in the environment impact a number of atmospheric and biogeochemical cycles. Organic material in snow or ice may be biological in origin, deposited from aerosols or atmospheric gases, or formed chemically in situ. In this manuscript, we review the current state of knowledge regarding the sources, properties, and chemistry of organic materials in environmental ices. Several outstanding questions remain to be resolved and fundamental data gathered before an accurate model of transformations and transport of organic species in the cryosphere will be possible. For example, more information is needed regarding the quantitative impacts of chemical and biological processes, ice morphology, and snow formation on the fate of organic material in cold regions. Interdisciplinary work at the interfaces of chemistry, physics and biology is needed in order to fully characterize the nature and evolution of organics in the cryosphere and predict the effects of climate change on the Earth's carbon cycle.
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Wynhoff, Irma, Raldi B. Bakker, Bas Oteman, Paula Seixas Arnaldo, and Frank van Langevelde. "Phengaris (Maculinea) alconbutterflies deposit their eggs on tall plants with many large buds in the vicinity ofMyrmicaants." Insect Conservation and Diversity 8, no. 2 (November 7, 2014): 177–88. http://dx.doi.org/10.1111/icad.12100.
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Ouyed, Rachid. "Can D-D fusion contribute to Jupiter's excess heat?" Symposium - International Astronomical Union 202 (2004): 280–82. http://dx.doi.org/10.1017/s0074180900218068.
Повний текст джерелаАнотація:
We explore the highly speculative idea of Deuterium - Deuterium (D-D) fusion inside Jupiter as an internal heating source. We suggest that D could have been brought deep inside the planet by planetesimals (during the process of planet formation) and deposited through planetesimal/ices vaporization. Here, the general aspects of the model are presented.
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Foti, Francesco, and Luca Martinelli. "Finite element modeling of cable galloping vibrations. Part II: Application to an iced cable in 1:2 multiple internal resonance." Journal of Vibration and Control 24, no. 7 (July 20, 2016): 1322–40. http://dx.doi.org/10.1177/1077546316660017.
Повний текст джерелаАнотація:
The aim of this paper is to validate the finite element formulations proposed in a companion paper for the study of the nonlinear dynamic behavior of cable structures. A well-known suspended cable in multiple 1:2 “internal resonance” conditions is herein considered. A uniform ice deposit, along the length of the cable, makes it prone to galloping vibrations under a steady wind flow. Different modeling strategies, relying on different assumptions regarding both the mechanical model as well as the aerodynamic response, are investigated and compared with results coming from analytical, semi-analytical and numerical models from the literature. The role of torsional and flexural stiffness terms, and of the initial undeformed configuration, is critically assessed. The results obtained show the significant effect coming from the adoption of a beam finite element formulation that includes the effect of torsional rotation in the evaluation of the aerodynamic loads.
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Salzmann, Christoph, Jacob Shephard, and John Evans. "The structural relaxation properties of the amorphous ices." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1337. http://dx.doi.org/10.1107/s2053273314086628.
Повний текст джерелаАнотація:
Despite the importance of low-density amorphous ice (LDA) in critical cosmological processes and its prominence as one of the polyamorphs of water there is still an incomplete picture of the processes that take place upon thermal annealing. We show that a gradual structural relaxation process takes place upon heating vapor-deposited LDA, also called amorphous solid water, and LDAs obtained from several different states of high-density amorphous ice. The structural relaxation leads to an increase in structural order on local and more extended length scales as the average O-O distance shortens and the O-O distance distribution narrows. The relaxation process is separate from crystallization and it does not seem to reach completion before crystallization sets in. Our findings are therefore difficult to reconcile with the postulated glass transition of LDA to the supercooled and highly viscous liquid prior to crystallization. On the basis of a comparison of the calorimetric data of LDA with those of some of the crystalline phases of ice we propose that the calorimetric feature of LDA prior to crystallization may in fact be connected to the kinetic unfreezing of defect-migration mediated reorientation dynamics. We finally discuss the relaxation properties of the various kinds of high-density amorphous ice in the context of these new findings.
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Dupuy, R., M. Bertin, G. Féraud, X. Michaut, P. Jeseck, M. Doronin, L. Philippe, C. Romanzin, and J. H. Fillion. "Spectrally-resolved UV photodesorption of CH4 in pure and layered ices." Astronomy & Astrophysics 603 (July 2017): A61. http://dx.doi.org/10.1051/0004-6361/201730772.
Повний текст джерелаАнотація:
Context. Methane is among the main components of the ice mantles of interstellar dust grains, where it is at the start of a rich solid-phase chemical network. Quantification of the photon-induced desorption yield of these frozen molecules and understanding of the underlying processes is necessary to accurately model the observations and the chemical evolution of various regions of the interstellar medium. Aims. This study aims at experimentally determining absolute photodesorption yields for the CH4 molecule as a function of photon energy. The influence of the ice composition is also investigated. By studying the methane desorption from layered CH4:CO ice, indirect desorption processes triggered by the excitation of the CO molecules are monitored and quantified. Methods. Tunable monochromatic vacuum ultraviolet light (VUV) light from the DESIRS beamline of the SOLEIL synchrotron is used in the 7–13.6 eV (177–91 nm) range to irradiate pure CH4 or layers of CH4 deposited on top of CO ice samples. The release of species in the gas phase is monitored by quadrupole mass spectrometry, and absolute photodesorption yields of intact CH4 are deduced. Results. CH4 photodesorbs for photon energies higher than ~9.1 eV (~136 nm). The photodesorption spectrum follows the absorption spectrum of CH4, which confirms a desorption mechanism mediated by electronic transitions in the ice. When it is deposited on top of CO, CH4 desorbs between 8 and 9 eV with a pattern characteristic of CO absorption, indicating desorption induced by energy transfer from CO molecules. Conclusions. The photodesorption of CH4 from pure ice in various interstellar environments is around 2.0 ± 1.0 × 10-3 molecules per incident photon. Results on CO-induced indirect desorption of CH4 provide useful insights for the generalization of this process to other molecules co-existing with CO in ice mantles.
13
Shi, Y., X. J. Fan, H. X. Guo, and Q. Fu. "Raman scattering studies on the C60 films deposited by ionized cluster beam deposition (ICBD) technique." Solid State Communications 99, no. 6 (August 1996): 445–49. http://dx.doi.org/10.1016/0038-1098(96)00281-5.
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Givan, A., A. Loewenschuss, and C. J. Nielsen. "The stretching mode of deposited CO as a probe for the morphology of 5 K ices." Chemical Physics Letters 275, no. 1-2 (August 1997): 98–102. http://dx.doi.org/10.1016/s0009-2614(97)00723-9.
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15
McFall, Alexander S., and Cort Anastasio. "Photon flux dependence on solute environment in water ices." Environmental Chemistry 13, no. 4 (2016): 682. http://dx.doi.org/10.1071/en15199.
Повний текст джерелаАнотація:
Environmental context Anthropogenic pollutants deposited in and on snowpacks can undergo many sunlight-driven reactions. These processes have been studied, but typically without measuring the photon flux, the amount of light seen by the reactants, which is needed for comparing results across studies. This work investigates the effects of container albedo, solute location and mechanical ice crushing on the photon flux in laboratory ice samples to understand how these factors might affect photochemical rates. Abstract The photon flux directly affects the rates of both direct and indirect photodegradation reactions in water and ice. This flux might vary in the different solute reservoirs of water ice (e.g. between the bulk ice and air–ice interface), which might help explain reported differences in measured reaction rates. To address this possibility, here we use 2-nitrobenzaldehyde chemical actinometry to measure photon fluxes in ice samples prepared using different freezing techniques in order to put 2-nitrobenzaldehyde into different regions in the ice samples. Overall, the solute location has little effect on photon flux in water ice (purified frozen water) samples, with a maximum observed enhancement of 42±9% relative to aqueous values. However, the albedo (reflectivity) of the sample container strongly influences the photon flux in water and ice samples: for the same incident irradiance, 2-nitrobenzaldehyde loss is four times higher in a white beaker compared with in a dark-brown beaker. In addition, crushing an ice sample to a 2-mm grain size increases the photon flux in the resulting ice granules by 50% compared with in an intact ice disc (and by 80% compared with the corresponding solution). Although photon fluxes are similar in different solute reservoirs in and on ice, our results show that photon fluxes within a frozen (or aqueous) sample cannot be simply determined from incident fluxes, but instead need to be measured using the same sample geometry and container type.
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Inoue, Shozo, Takahiro Namazu, T. Fujimoto, Keiji Koterazawa, and Kanryu Inoue. "Mechanical Properties of Fe-Pd Ferromagnetic Shape Memory Alloy Thin Films Prepared by Dual Source DC Sputtering." Materials Science Forum 539-543 (March 2007): 3173–78. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3173.
Повний текст джерелаАнотація:
The purpose of this work is to quantitatively clarify the shape memory behavior of Fe-Pd films containing ~30at%Pd by thermal cycling testing under various constant stresses. Fe-Pd films (4 $m thick) were deposited onto Si wafers with thermally formed 1$m-thick SiO2 layer using a dual-source dc magnetron sputtering apparatus. The deposited films were all annealed at 900°C for 60 min followed by iced water quenching. Perfect shape recovery was observed for Fe-30.0at%Pd film when the applied stress was lower than 300 MPa. The maximum recoverable strain was ~0.6%. Fe-29.2at%Pd film, on the other hand, showed unrecovered strain after thermal cycling even if the applied stress was 40 MPa. XRD measurements of the Fe-29.2at% Pd film before and after thermal cycling revealed irreversible fcc-bct martensitic transformation that occurred during cooling process at a temperature around -80°C. The critical stress of Fe-Pd films, at which plastic deformation commences to occur, is higher for films with 30 at% Pd than for films with 29.2 at% Pd, which is practically advantageous. The Ms temperature of these films is lower than room temperature when no bias stress is applied, while it becomes higher than room temperature when appropriate bias stress is applied, obeying Clapeyron-Clausius law.
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Agop, Maricel, Nicanor Cimpoesu, Silviu Gurlui, and Stefan Andrei Irimiciuc. "Investigations of Transient Plasma Generated by Laser Ablation of Hydroxyapatite during the Pulsed Laser Deposition Process." Symmetry 12, no. 1 (January 9, 2020): 132. http://dx.doi.org/10.3390/sym12010132.
Повний текст джерелаАнотація:
The optimization of the pulsed laser deposition process was attempted here for the generation of hydroxyapatite thin films. The deposition process was monitored with an ICCD (Intensified Coupled Charged Device) fast gated camera and a high-resolution spectrometer. The global dynamics of the laser produced plasma showed a self-structuring into three components with different composition and kinetics. The optical emission spectroscopy revealed the formation of a stoichiometric plasma and proved that the segregation in the kinetic energy of the plasma structure is also reflected by the individual energies of the ejected particles. Atomic Force Microscopy was also implemented to investigate the properties and the quality of the deposited film. The presence of micrometric clusters was seen at a high laser fluence deposition with in-situ ICCD imaging. We developed a fractal model based on Schrödinger type functionalities. The model can cover the distribution of the excited states in the laser produced plasma. Moreover, we proved that SL(2R) invariance can facilitate plasma substructures synchronization through a self-modulation in amplitude.
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Schenk, Paul, Chloe Beddingfield, Tanguy Bertrand, Carver Bierson, Ross Beyer, Veronica Bray, Dale Cruikshank, et al. "Triton: Topography and Geology of a Probable Ocean World with Comparison to Pluto and Charon." Remote Sensing 13, no. 17 (September 1, 2021): 3476. http://dx.doi.org/10.3390/rs13173476.
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The topography of Neptune’s large icy moon Triton could reveal important clues to its internal evolution, but has been difficult to determine. New global digital color maps for Triton have been produced as well as topographic data for <40% of the surface using stereogrammetry and photoclinometry. Triton is most likely a captured Kuiper Belt dwarf planet, similar though slightly larger in size and density to Pluto, and a likely ocean moon that exhibited plume activity during Voyager 2′s visit in 1989. No surface features or regional deviations of greater than ±1 km amplitude are found. Volatile ices in the southern terrains may take the form of extended lobate deposits 300–500 km across as well as dispersed bright materials that appear to embay local topography. Limb hazes may correlate with these deposits, indicating possible surface–atmosphere exchange. Triton’s topography contrasts with high relief up to 6 km observed by New Horizons on Pluto. Low relief of (cryo)volcanic features on Triton contrasts with high-standing massifs on Pluto, implying different viscosity materials. Solid-state convection occurs on both and at similar horizontal scales but in very different materials. Triton’s low relief is consistent with evolution of an ice shell subjected to high heat flow levels and may strengthen the case of an internal ocean on this active body.
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Boxe, C. S., B. R. Bodsgard, W. Smythe, and M. T. Leu. "Grain sizes, surface areas, and porosities of vapor-deposited H2O ices used to simulate planetary icy surfaces." Journal of Colloid and Interface Science 309, no. 2 (May 2007): 412–18. http://dx.doi.org/10.1016/j.jcis.2007.01.008.
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Yamamuro, O., T. Matsuo, I. Tsukushi, and N. Onoda-Yamamuro. "Inelastic neutron scattering and low-energy excitation of amorphous SF6 hydrate prepared by vapor-deposition technique." Canadian Journal of Physics 81, no. 1-2 (January 1, 2003): 107–14. http://dx.doi.org/10.1139/p02-140.
Повний текст джерелаАнотація:
Amorphous SF6 hydrate (SF6·17H2O) was prepared by depositing the mixed vapor onto a substrate kept at about 8 K. The inelastic neutron-scattering spectra of the as-deposited sample and those annealed at about 120 and 150 K were measured at 50 K in the energy range below 100 meV. The first two samples were considered to be in amorphous states while the third one was in a crystalline state. The librational frequency of the water molecule (at around 60 meV) is smaller in the order of (as-deposited sample) < (annealed sample) < (crystalline sample). This indicates that the strength of the intermolecular hydrogen bonds is (crystalline sample) > (annealed sample) > (as-deposited sample). The spectra below 10 meV were compared with our previous data of pure vapor-deposited amorphous ices and those doped with methanol (CD3OH). The low-energy excitation (E < 6 meV) differed drastically depending on the dopants, i.e., the scattering intensity was enhanced by methanol doping but reduced by SF6 doping. This may be because the hydrogen-bond formation was hindered by methanol doping but promoted rather more by SF6 doping because of the hydrophobic interaction as in clathrate hydrates. PACS Nos.: 61.12Ex, 63.50tx
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Desprez, M., B. Pearce, and S. Le Bot. "The biological impact of overflowing sands around a marine aggregate extraction site: Dieppe (eastern English Channel)." ICES Journal of Marine Science 67, no. 2 (November 3, 2009): 270–77. http://dx.doi.org/10.1093/icesjms/fsp245.
Повний текст джерелаАнотація:
Abstract Desprez, M., Pearce, B., and Le Bot, S. 2010. The biological impact of overflowing sands around a marine aggregate extraction site: Dieppe (eastern English Channel). – ICES Journal of Marine Science, 67: 270–277. The study investigates the physical impact of sediment deposition associated with aggregate dredging at a site off Dieppe, and the consequences for benthic fauna. Sampling stations were sited across potential zones of impact classified as high, moderate, and low deposition, depending on their proximity to dredging activities and their position relative to the net sediment transport route. Samples were also taken west of the dredge site outside the zone of likely impact (no deposition). A strong gradient was observed from the sediments dominated by fine sands in the high and moderate deposition zones, through to coarse sands and gravels in the low and no deposition zones. The benthic fauna sampled from the deposits of fine sand in the high and moderate deposition zones were sparse compared with the coarser deposits sampled from the low and no deposition zones. There was a strong correspondence between the distribution of different sediment fractions and the associated benthic fauna, with a weighted Spearman rank correlation of 0.638, higher than reported in related studies. This suggests that in deposition areas such as this, biological interactions play a less important role in shaping communities than the changes in the physical environment, which may have a greater impact on the biological communities.
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Tikhonravova, Ya V., A. V. Lupachev, E. A. Slagoda, V. V. Rogov, A. O. Kuznetsova, V. I. Butakov, G. V. Simonova, N. A. Taratunina, and D. R. Mullanurov. "Structure and formation of ice-ground veins of the second lake-alluvial terrace in the North of Gydan in the late Neopleistocene–Holocene." Ice and Snow 59, no. 4 (December 1, 2019): 557–70. http://dx.doi.org/10.15356/2076-6734-2019-4-367.
Повний текст джерелаАнотація:
The syngenetic ice and ice-ground composite veins in khasyrey (alas) and interalas plateaus were studied on the second lake-alluvial terrace located in the North of the Gydan Peninsula near the village of Gyda. On the basis of the radiocarbon dating, the time of formation of deposits containing veins from was established – from 16 640 to 854 BP. The peat deposits are mainly represented by the following species: Carex sp., Eriophorum sp., Betula nana, Equisetum sp., Calamagrostis sp., Vaccinium vitis-idaea, Drepanocladus sp., Empetrum sp., Vaccinium uliginosum, Rubus arcticus, Petasites sp. It is established that the polygonal-veined ice of khasyrey and interalas plateaus, except for vertical-striped «clean» ice, contain areas with vertical wavy streaks of ice-ground. Ice of elementary veins and segregation ice were revealed in the composition of veins according to structural and textural features in polarized light. Elementary ice veins compose «clean» ice sections of veins and segregation ice which are their ice-ground sections. Elementary veins are indicative of the predominance of the process of frost cracking during the formation of polygonal-vein ices. The presence of inclusions of ice-ground in the structure of veins points is evidence of a manifestation of local thermokarst processes under the growth of polygonal-vein ice. Ice-ground veins were formed by repeated thawing of the initial ice veins. The formation of ice-ground veins during syngenetic freezing of sediments of the second lake-alluvial terrace is related to uneven manifestation of thermokarst in different facies situations and and climate changes at the Early Pleistocene and Holocene.
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Müller, B., B. M. Giuliano, M. Goto, and P. Caselli. "Spectroscopic measurements of CH3OH in layered and mixed interstellar ice analogues." Astronomy & Astrophysics 652 (August 2021): A126. http://dx.doi.org/10.1051/0004-6361/202039139.
Повний текст джерелаАнотація:
Context. The molecular composition of interstellar ice mantles is defined by gas-grain processes in molecular clouds, with the main components being H2O, CO, and CO2. Methanol (CH3OH) ice is detected towards the denser pre-stellar cores and star-forming regions, where large amounts of CO molecules freeze out and get hydrogenated on top of the icy grains. The thermal heating from nearby protostars can further change the ice structure and composition. Despite the several observations of icy features carried out towards molecular clouds and along the line of site of protostars, it is not yet clear if interstellar ices are mixed or if they have a layered structure. Aims. We aim to examine the effect of mixed and layered ice growth in dust grain mantle analogues, with specific focus on the position and shape of methanol infrared bands, so dedicated future observations could shed light on the structure of interstellar ices in different environments. Methods. Mixed and layered ice samples were deposited on a cold substrate kept at a temperature of 10 K using a closed-cycle cryostat placed in a vacuum chamber. The spectroscopic features were analysed by Fourier transform infrared spectroscopy. Different proportions of the most abundant four molecular species in ice mantles, namely H2O, CO, CO2, and CH3OH, were investigated, with a special attention placed on the analysis of the CH3OH bands. Results. We measure changes in the position and shape of the CH and CO stretching bands of CH3OH depending on the mixed or layered nature of the ice sample. Spectroscopic features of methanol are also found to change due to heating. Conclusions. A layered ice structure best reproduces the CH3OH band position recently observed towards a pre-stellar core and in star-forming regions. Based on our experimental results, we conclude that observations of CH3OH ice features in space can provide information about the structure of interstellar ices, and we expect the James Webb Space Telescope to put stringent constraints on the layered or mixed nature of ices in different interstellar environments, from molecular clouds to pre-stellar cores to protostars and protoplanetary discs.
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De Bonis, Angela, Agostino Galasso, Antonio Santagata, and Roberto Teghil. "Ultrashort Pulsed Laser Ablation of Magnesium Diboride: Plasma Characterization and Thin Films Deposition." Journal of Nanomaterials 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/596328.
Повний текст джерелаАнотація:
A MgB2target has been ablated by Nd:glass laser with a pulse duration of 250 fs. The plasma produced by the laser-target interaction, showing two temporal separated emissions, has been characterized by time and space resolved optical emission spectroscopy and ICCD fast imaging. The films, deposited on silicon substrates and formed by the coalescence of particles with nanometric size, have been analyzed by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction. The first steps of the films growth have been studied by Transmission Electron Microscopy. The films deposition has been studied by varying the substrate temperature from 25 to 500°C and the best results have been obtained at room temperature.
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Zaporozhchenko, E. V. "Ice-rock avalanche of 2002 in Genaldon River valley, North Caucasus, Russia: consequences and problems." Journal of Nepal Geological Society 34 (October 9, 2006): 99–108. http://dx.doi.org/10.3126/jngs.v34i0.31884.
Повний текст джерелаАнотація:
The biggest glacial disaster in the Russian history occurred in September 2002. A huge ice- rock-water flow from the Kolka Glacier went down the Genaldon River valley with a speed of 320 km/h. Having travelled a distance of 18.5 km, it was stopped by the 2 km long narrows of the Rocky Mountain Range and it filled the hollow with 120 ml of deposits. The ice rock-water mass pressed through the narrows forming a debris flow which went down the valley for 10 km devastating all the settlements on the riverbed. As a result, 125 people lost their lives. In 2002, two months before the disaster, a series of collapses from an elevation of about 1000 m at the backside of the glacier had activated the avalanche. The last ice- mass collapse had a volume of 10 million ml. The material accumulated in the glacier hollow was knocked off and went down the valley. The 100-150 m high ice- rock- water mass (with air also) was moving down the 400- 500 m wide valley. The flow on its way down the valley trough was fed by the frontal masses of three huge ancient landslides situated on the left bank. The hazards and risks after 2002 can be attributed mainly to the filling up of the hollow by the ice-rock material, the formation of a dammed lake, and the filling up of the narrows by debris flow and mudflow deposits. Presently the dammed lake is discharging naturally and there is about 0.5 million ml of water in it. The future behaviour of the ice-rock dam is not clear and it is difficult to make any forecast due to its melting on the one hand and the formation of underground outflows with sporadic floods on the other hand. In 2002-2004 the debris flow deposits on the riverbed were still unstable and loose. A surge with a discharge of more than 20 m3/sec and (or) a storm flood of such a magnitude can adversely affect the riverbed processes in the overpopulated foothill areas requiring mitigation and protective measures.
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Bass, A. D., L. Parenteau, F. Weik, and L. Sanche. "Effects of morphology on the low-energy electron stimulated desorption of O− from O2 deposited on benzene and water ices." Journal of Chemical Physics 115, no. 10 (September 8, 2001): 4811–18. http://dx.doi.org/10.1063/1.1394733.
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Sousa, Arturo, Pablo García-Murillo, Julia Morales, and Leoncio García-Barrón. "Anthropogenic and natural effects on the coastal lagoons in the southwest of Spain (Doñana National Park)." ICES Journal of Marine Science 66, no. 7 (April 23, 2009): 1508–14. http://dx.doi.org/10.1093/icesjms/fsp106.
Повний текст джерелаАнотація:
Abstract Sousa, A., García-Murillo, P., Morales, J., and García-Barrón, L. 2009. Anthropogenic and natural effects on the coastal lagoons in the southwest of Spain (Doñana National Park). – ICES Journal of Marine Science, 66: 1508–1514. The Doñana peridunal lagoons, located in the southwest of Spain, have been well studied, because their conservation is of great interest. Since 1965, they have also been affected by the extraction of underground water for local coastal tourist resorts. A reconstruction of the evolution of this series of coastal lagoons reveals that, along with the anthropogenic effect, there was a natural effect resulting from the reactivation of mobile dune fronts that have blocked and filled the original lagoon complex—in the period 1920–1987, the lagoons were reduced by 70.7%. These fronts might have been fed by deposits of marine sand during the climatically driest phases of the Little Ice Age in Andalusia, Spain. Therefore, if the frequency and duration of dry periods increase, as well as droughts as a whole, because of global warming, the desiccation and disappearance of the lagoons could become more widespread, not only at this site in southwestern Europe, but in other Mediterranean coastal ecosystems as well.
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Van Dover, Cindy Lee. "Mining seafloor massive sulphides and biodiversity: what is at risk?" ICES Journal of Marine Science 68, no. 2 (June 30, 2010): 341–48. http://dx.doi.org/10.1093/icesjms/fsq086.
Повний текст джерелаАнотація:
Abstract Van Dover, C. L. 2011. Mining seafloor massive sulphides and biodiversity: what is at risk? – ICES Journal of Marine Science, 68: 341–348. Scientific exploration of the deep sea in the late 1970s led to the discovery of seafloor massive sulphides at hydrothermal vents. More recently, sulphide deposits containing high grades of ore have been discovered in the southwest Pacific. In addition to metal-rich ores, hydrothermal vents host ecosystems based on microbial chemoautotrophic primary production, with endemic invertebrate species adapted in special ways to the vent environment. Although there has been considerable effort to study the biology and ecology of vent systems in the decades since these systems were first discovered, there has been limited attention paid to conservation issues. Three priority recommendations for conservation science at hydrothermal vent settings are identified here: (i) determine the natural conservation units for key species with differing life histories; (ii) identify a set of first principles for the design of preservation reference areas and conservation areas; (iii) develop and test methods for effective mitigation and restoration to enhance the recovery of biodiversity in sulphide systems that may be subject to open-cut mining.
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He, Jiao, Sharon J. M. Diamant, Siyu Wang, Haochuan Yu, Will R. M. Rocha, Marina Rachid, and Harold Linnartz. "Refractive Index and Extinction Coefficient of Vapor-deposited Water Ice in the UV–vis Range." Astrophysical Journal 925, no. 2 (February 1, 2022): 179. http://dx.doi.org/10.3847/1538-4357/ac3fbb.
Повний текст джерелаАнотація:
Abstract Laboratory results of the optical properties of vapor-deposited water ice, specifically the refractive index and extinction coefficient, are available mainly for a selective set of wavelengths and a limited number of deposition temperatures. Experimental limitations are the main reason for the lack of broadband data, which is unfortunate as these quantities are needed to interpret and predict astronomical and planetary observations. The goal of this work is to address these lacking data, using an experimental broadband method that is capable of rapidly providing reliable water ice data across the entire UV–visible range. This approach combines the simultaneous use of a monochromatic HeNe laser and a broadband Xe-arc lamp to record interference fringes of water ice during deposition at astronomically relevant ice temperatures. The ice thickness is typically more than 20 μm. Analyzing the period and intensity patterns combining both the monochromatic and broadband interference patterns allows the determination of the wavelength-dependent refractive index and extinction coefficient. We present accurate refractive index and extinction coefficient graphs for wavelengths between 250 and 750 nm and ices deposited between 30 and 160 K. From our data, we find a possible structural change in the ice in the 110–130 K region that has not been reported before. We also discuss that the data presented in this paper can be used to interpret astronomical observations of icy surfaces.
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Podolak, Morris, and Nader Haghighipour. "Planetesimal Capture by an Evolving Giant Gaseous Protoplanet." Proceedings of the International Astronomical Union 8, S293 (August 2012): 263–69. http://dx.doi.org/10.1017/s1743921313012957.
Повний текст джерелаАнотація:
AbstractBoth the core-accretion and disk-instability models suggest that at the last stage of the formation of a gas-giant, the core of this object is surrounded by an extended gaseous envelope. At this stage, while the envelope is contracting, planetesimals from the protoplanetary disk may be scattered into the protoplanets atmosphere and deposit some or all of their materials as they interact with the gas. We have carried out extensive simulations of approximately 104 planetesimals interacting with a envelope of a Jupiter-mass protoplanet including effects of gas drag, heating, and the effect of the protoplanets extended mass distribution. Simulations have been carried out for different radii and compositions of planetesimals so that all three processes occur to different degrees. We present the results of our simulations and discuss their implications for the enrichment of ices in giant planets. We also present statistics for the probability of capture (i.e. total mass-deposition) of planetesimals as a function of their size, composition, and closest approach to the center of the protoplanetary body.
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Chaabouni, Henda, Saoud Baouche, Stephan Diana, and Marco Minissale. "Reactivity of formic acid (HCOOH) with H atoms on cold surfaces of interstellar interest." Astronomy & Astrophysics 636 (April 2020): A4. http://dx.doi.org/10.1051/0004-6361/201936411.
Повний текст джерелаАнотація:
Context. Formic acid (HCOOH) is the simplest organic carboxylic acid in chemical synthesis and the significant species in interstellar chemistry. HCOOH has been abundantly detected in interstellar ices, dense molecular clouds and star-forming regions. Aims. Laboratory hydrogenation experiments of HCOOH molecules with H atoms were performed with two cryogenic ultra-high vacuum devices on amorphous solid water ices, and highly oriented pyrolytic graphite surfaces. The aim of this work is to study the reactivity of HCOOH molecules with H atoms at low surface temperature 10 K, low surface coverage of one monolayer to three layers, and low H-atom flux of about 3.0 × 1012 molecule cm−2 s−1. Methods. HCOOH and H beams were deposited on cold surfaces held at 10 K, and the condensed films were analyzed by in-situ Reflection Absorption InfraRed Spectroscopy and temperature programmed desorption (TPD) mass spectrometry technique by heating the sample from 10 to 200 K. Results. Using the temperature programmed during exposure desorption technique, we highlight the possible dimerization of HCOOH molecules at low surface temperatures between 10 and 100 K. In our HCOOH+H experiments, we evaluated a consumption of 20–30% of formic acid by comparing the TPD curves at m/z 46 of pure and H-exposed HCOOH ice. Conclusions. The hydrogenation HCOOH+H reaction is efficient at low surface temperatures. The main products identified experimentally are carbon dioxide (CO2) and water (H2O) molecules. CO bearing species CH3OH, and H2CO are also detected mainly on graphite surfaces. A chemical surface reaction route for the HCOOH+H system is proposed to explain the product formation.
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Bouquety, A., L. Jorda, O. Groussin, A. Sejourné, S. Bouley, and F. Costard. "Ancient and present surface evolution processes in the Ash region of comet 67P/Churyumov-Gerasimenko." Astronomy & Astrophysics 649 (May 2021): A82. http://dx.doi.org/10.1051/0004-6361/202140516.
Повний текст джерелаАнотація:
Aims. The Rosetta mission provided us with detailed data of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko. In order to better understand the physical processes associated with the comet activity and the surface evolution of its nucleus, we performed a detailed comparative morphometrical analysis of two depressions located in the Ash region. Methods. To detect morphological temporal changes, we compared pre- and post-perihelion high-resolution (pixel scale of 0.07–1.75 m) OSIRIS images of the two depressions. We quantified the changes using the dynamic heights and the gravitational slopes calculated from the digital terrain model of the studied area. In particular, we measured seven geometric parameters associated with the two depressions (length, three width values, height, area, and volume) using the ArcGIS software before and after perihelion. Results. Our comparative morphometrical analysis allowed us to detect and quantify the temporal changes that occurred in two depressions of the Ash region during the last perihelion passage. We find that the two depressions grew by several meters. The area of the smallest depression (structure I) increased by 90 ± 20%, with two preferential growths: one close to the cliff associated with the apparition of new boulders at its foot, and a second one on the opposite side of the cliff. The largest depression (structure II) grew in all directions, increasing in area by 20 ± 5%, and no new deposits have been detected. We interpreted these two depression changes as being driven by the sublimation of ices, which explains their global growth and which can also trigger landslides. The deposits associated with depression II reveal a stair-like topography, indicating that they have accumulated during several successive landslides from different perihelion passages. Overall, these observations bring additional evidence of complex active processes and reshaping events occurring on short timescales (months to years), such as depression growth and landslides, and on longer timescales (decades to millenniums), such as cliff retreat.
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Cimpoesu, Nicanor, Silviu Gurlui, Georgiana Bulai, Ramona Cimpoesu, Viorel-Puiu Paun, Stefan Andrei Irimiciuc, and Maricel Agop. "In-Situ Plasma Monitoring during the Pulsed Laser Deposition of Ni60Ti40 Thin Films." Symmetry 12, no. 1 (January 6, 2020): 109. http://dx.doi.org/10.3390/sym12010109.
Повний текст джерелаАнотація:
The properties of pulsed laser deposited of Ni60Ti40 shape memory thin films generated in various deposition conditions were investigated. In-situ plasma monitoring was implemented by means of space- and time-resolved optical emission spectroscopy, and ICCD fast camera imaging. Structural and chemical analyses were performed on the thin films using SEM, AFM, EDS, and XRD equipment. The deposition parameters influence on the chemical composition of the thin films was investigated. The peeled layer presented on DSC a solid-state transformation in a different transformation domain compared to the target properties. A fractal model was used to describe the dynamics of laser produced plasma through various non-differentiable functionalities. Through hydrodynamic type regimes, space-time homographic transformations were correlated with the global dynamics of the ablation plasmas. Spatial simultaneity of homographic transformation through a special SL(2R) invariance implies the description of plasma dynamics through Riccati type equations, establishing correlations with the optical emission spectroscopy measurements.
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Nachbar, Mario, Denis Duft, and Thomas Leisner. "The vapor pressure over nano-crystalline ice." Atmospheric Chemistry and Physics 18, no. 5 (March 8, 2018): 3419–31. http://dx.doi.org/10.5194/acp-18-3419-2018.
Повний текст джерелаАнотація:
Abstract. The crystallization of amorphous solid water (ASW) is known to form nano-crystalline ice. The influence of the nanoscale crystallite size on physical properties like the vapor pressure is relevant for processes in which the crystallization of amorphous ices occurs, e.g., in interstellar ices or cold ice cloud formation in planetary atmospheres, but up to now is not well understood. Here, we present laboratory measurements on the saturation vapor pressure over ice crystallized from ASW between 135 and 190 K. Below 160 K, where the crystallization of ASW is known to form nano-crystalline ice, we obtain a saturation vapor pressure that is 100 to 200 % higher compared to stable hexagonal ice. This elevated vapor pressure is in striking contrast to the vapor pressure of stacking disordered ice which is expected to be the prevailing ice polymorph at these temperatures with a vapor pressure at most 18 % higher than that of hexagonal ice. This apparent discrepancy can be reconciled by assuming that nanoscale crystallites form in the crystallization process of ASW. The high curvature of the nano-crystallites results in a vapor pressure increase that can be described by the Kelvin equation. Our measurements are consistent with the assumption that ASW is the first solid form of ice deposited from the vapor phase at temperatures up to 160 K. Nano-crystalline ice with a mean diameter between 7 and 19 nm forms thereafter by crystallization within the ASW matrix. The estimated crystal sizes are in agreement with reported crystal size measurements and remain stable for hours below 160 K. Thus, this ice polymorph may be regarded as an independent phase for many atmospheric processes below 160 K and we parameterize its vapor pressure using a constant Gibbs free energy difference of (982 ± 182) J mol−1 relative to hexagonal ice.
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Chuang, K. J., G. Fedoseev, D. Qasim, S. Ioppolo, E. F. van Dishoeck, and H. Linnartz. "H2 chemistry in interstellar ices: the case of CO ice hydrogenation in UV irradiated CO:H2 ice mixtures." Astronomy & Astrophysics 617 (September 2018): A87. http://dx.doi.org/10.1051/0004-6361/201833439.
Повний текст джерелаАнотація:
Context. In dense clouds, hydrogenation reactions on icy dust grains are key in the formation of molecules, like formaldehyde, methanol, and complex organic molecules (COMs). These species form through the sequential hydrogenation of CO ice. Although molecular hydrogen (H2) abundances can be four orders of magnitude higher than those of free H-atoms in dense clouds, H2 surface chemistry has been largely ignored; several laboratory studies show that H2 does not actively participate in “non-energetic” ice chemistry because of the high activation energies required. Aims. For the example of CO ice hydrogenation, we experimentally investigated the potential role of H2 molecules on the surface chemistry when energetic processing (i.e., UV photolysis) is involved. We test whether additional hydrogenation pathways become available upon UV irradiation of a CO:H2 ice mixture and whether this reaction mechanism also applies to other chemical systems. Methods. Ultra-high vacuum (UHV) experiments were performed at 8–20 K. A pre-deposited solid mixture of CO:H2 was irradiated with UV-photons. Reflection absorption infrared spectroscopy (RAIRS) was used as an in situ diagnostic tool. Single reaction steps and possible isotopic effects were studied by comparing results from CO:H2 and CO:D2 ice mixtures. Results. After UV-irradiation of a CO:H2 ice mixture, two photon-induced products, HCO and H2CO, are unambiguously detected. The proposed reaction mechanism involves electronically excited CO in the following reaction steps: CO + hν→CO*, CO* + H2→HCO + H where newly formed H-atoms are then available for further hydrogenation reactions. The HCO formation yields have a strong temperature dependence for the investigated regime, which is most likely linked to the H2 sticking coefficient. Moreover, the derived formation cross section reflects a cumulative reaction rate that mainly determined by both the H-atom diffusion rate and initial concentration of H2 at 8–20 K and that is largely determined by the H2 sticking coefficient. Finally, the astronomical relevance of this photo-induced reaction channel is discussed.
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Zischke, Mitchell T., Shane P. Griffiths, and Ian R. Tibbetts. "Rapid growth of wahoo (Acanthocybium solandri) in the Coral Sea, based on length-at-age estimates using annual and daily increments on sagittal otoliths." ICES Journal of Marine Science 70, no. 6 (May 22, 2013): 1128–39. http://dx.doi.org/10.1093/icesjms/fst039.
Повний текст джерелаАнотація:
Abstract Zischke, M. T., Griffiths, S. P., and Tibbetts, I. R. 2013. Rapid growth of wahoo (Acanthocybium solandri) in the Coral Sea, based on length-at-age estimates using annual and daily increments on sagittal otoliths. – ICES Journal of Marine Science, 70: 1128–1139. The wahoo (Acanthocybium solandri) is an economically important species incidentally caught in oceanic fisheries targeting tuna and coastal fisheries targeting mackerels. The age and growth of wahoo was examined using whole and sectioned otoliths from 395 fish (790–1770 mm LF) sampled from the Coral Sea. Growth increments were more reliably assigned on whole otoliths than sectioned otoliths. Edge analyses revealed that growth increments were deposited annually, primarily between October and February. Furthermore, analysis of presumed daily microincrements showed that ∼90% of fish had deposited the first “annual” growth increment by the 365th day, thereby indirectly validating annual increment formation. Wahoo were aged at between 108 d and 7 years, with 76% of fish being <2-year old. The specialized von Bertalanffy growth function provided the best fit to length-at-age data, with parameter estimates (sexes combined) of L∞ = 1499 mm LF, K = 1.58 year−1, and t0 = −0.17 years. The growth performance index for wahoo in the Coral Sea (φ′ = 4.55) was one of the highest of all pelagic fish, with their growth and maximum size most similar to dolphinfish. This study suggests that wahoo are one of the fastest growing teleosts and provides growth parameter estimates that may facilitate future stock assessments and guide fisheries management.
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Gladstone, G. Randall, and Leslie A. Young. "New Horizons Observations of the Atmosphere of Pluto." Annual Review of Earth and Planetary Sciences 47, no. 1 (May 30, 2019): 119–40. http://dx.doi.org/10.1146/annurev-earth-053018-060128.
Повний текст джерелаАнотація:
New Horizons data provide a snapshot of the current state of Pluto's atmosphere. Winds are slow and mostly controlled by sublimation of surface ices. Molecular nitrogen is the primary constituent below 1,800 km, while methane and carbon monoxide are important minor species. Photolysis of these gases leads to a thin haze that encompasses Pluto from the surface up to >500-km altitude and is important in heating and cooling the atmosphere. A cold (∼70 K) upper atmosphere curtails the escape of Pluto's molecular nitrogen to space, although there is substantial escape of methane (∼5 × 1025 molecules s−1), coincidentally about equal to its loss by photochemistry. It is unknown if the current atmosphere is representative of its long-term average state. From the inferred rapid rate of haze settling, it seems that Pluto's atmosphere must occasionally undergo collapse to allow time for radiation processing of the colorless haze material into the dark deposits found on the surface. ▪ This article outlines what has been gleaned about Pluto's atmosphere in the years since the New Horizons flyby. ▪ Pluto's atmosphere is most similar to Titan's—with the photochemistry of supervolatile nitrogen and hydrocarbons resulting in a kind of factory for cold haze production. ▪ Much has been learned about Pluto's atmosphere, but many new questions have arisen, and these will likely remain unanswered until there is a follow-up mission—no doubt a long time from now.
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Cruikshank, Dale P., Yvonne J. Pendleton, and William M. Grundy. "Organic Components of Small Bodies in the Outer Solar System: Some Results of the New Horizons Mission." Life 10, no. 8 (July 28, 2020): 126. http://dx.doi.org/10.3390/life10080126.
Повний текст джерелаАнотація:
The close encounters of the Pluto–Charon system and the Kuiper Belt object Arrokoth (formerly 2014 MU69) by NASA’s New Horizons spacecraft in 2015 and 2019, respectively, have given new perspectives on the most distant planetary bodies yet explored. These bodies are key indicators of the composition, chemistry, and dynamics of the outer regions of the Solar System’s nascent environment. Pluto and Charon reveal characteristics of the largest Kuiper Belt objects formed in the dynamically evolving solar nebula inward of ~30 AU, while the much smaller Arrokoth is a largely undisturbed relic of accretion at ~45 AU. The surfaces of Pluto and Charon are covered with volatile and refractory ices and organic components, and have been shaped by geological activity. On Pluto, N2, CO and CH4 are exchanged between the atmosphere and surface as gaseous and condensed phases on diurnal, seasonal and longer timescales, while Charon’s surface is primarily inert H2O ice with an ammoniated component and a polar region colored with a macromolecular organic deposit. Arrokoth is revealed as a fused binary body in a relatively benign space environment where it originated and has remained for the age of the Solar System. Its surface is a mix of CH3OH ice, a red-orange pigment of presumed complex organic material, and possibly other undetected components.
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Fulle, Marco, J. Blum, A. Rotundi, B. Gundlach, C. Güttler, and V. Zakharov. "How comets work: nucleus erosion versus dehydration." Monthly Notices of the Royal Astronomical Society 493, no. 3 (February 20, 2020): 4039–44. http://dx.doi.org/10.1093/mnras/staa508.
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ABSTRACT We develop an activity model based on ice sublimation and gas diffusion inside cm-sized pebbles making-up a cometary nucleus. Our model explains cometary activity assuming no free parameters and fixing the nucleus surface temperature Ts, its gradient below the nucleus surface at thermal equilibrium, the pressure inside the porous pebbles, and the gas flux from them. We find that (i) the nucleus erosion rate and water vapour flux are independent of the nucleus refractory-to-ice ratio, which affects the dehydration rate only; (ii) water-driven dust ejection occurs in thermal quasi-equilibrium at Ts > 205 K; (iii) the smallest and largest ejected dust sizes depend on the nucleus surface temperature and its gradient at depths of few cm; and (iv) the water-driven nucleus erosion rate is independent of the water vapour flux. Regarding comet 67P/Churyumov–Gerasimenko, we find that (i) during the northern and southern polar summers, the nucleus active areas are ≈5 km2; (ii) >95 per cent of the southern pristine nucleus has a refractory-to-water-ice mass ratio >5; and (iii) the different temperature dependences of the dehydration and erosion rates explain the seasonal cycle: at perihelion, dm-sized chunks ejected by the sublimation of CO2 ices are rapidly enveloped by an insulating crust, preserving most water ice up to their fallout on the northern dust deposits; the inbound water-driven activity at low temperatures triggers a complete erosion of the fallout if its water-ice mass fraction is >0.1 per cent.
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Iovanas, Radu, Cosmin Toma, Daniela Maria Iovanas, Ionut Claudiu Roata, and Viorel Anton. "Research on the Use of the MIG/MAG-Tandem Procedure in Welding X52MS Plates for the Manufacture of Pipelines." Advanced Materials Research 1128 (October 2015): 236–41. http://dx.doi.org/10.4028/www.scientific.net/amr.1128.236.
Повний текст джерелаАнотація:
The pipelines used for carrying fluids and gas, made of specially designed steels in keeping with their intended uses, are obtained by welding on generator or by spiral welding, in a wide range of diameters (from 350 to 1800 mm) and pipe wall widths (between 6 and 40 mm). At present, the following welding procedures are used: automatic submerged arc welding (with 1 and 2 wires), combined with the unilateral or bilateral MIG/MAG welding procedure, according to plate thickness and edge working method. Ongoing researches focus on improving the end product [1, 2, 3, 4, 5, 6] by replacing the submerged arc welding procedure with other welding procedures which use less energy and have high deposit rates. This paper presents the results obtained by using tandem MAG welding, with two wires (2 x ø1.2 mm), in welding Y joint X52MS steel plates. The welds were carried out using a QUIROX 315 welding robot, with a 2-wire tandem MIG/MAG welding head, supplied by 2 QUINTO-GLC 603 welding sources, equipment found at Research Centre C12, Advanced Welding Eco-Technologies, owned by ICDD - UTBV. The results of the tests (carried out as per the enforceable regulations) concerning the characterisation of the executed welds proved that it is possible to obtain welds with lower energy use and lower material-relates costs and high productivity and quality.
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Koroleva, Ekaterina Sergeevna, Elena Adol'fovna Slagoda, Elena Alekseevna Babkina, Evgenij Mikhailovich Babkin, Yana Vital'evna Tikhonravova, and Nikita Yur'evich Fakashuk. "Structural and textural features of genetic types of the massive and ice wedges, and the conditions of their formation in the lower reaches of the Gyda River." Арктика и Антарктика, no. 4 (April 2020): 15–31. http://dx.doi.org/10.7256/2453-8922.2020.4.33717.
Повний текст джерелаАнотація:
In the structure of the frozen thickness of the 2nd lake-alluvial terrace of the Gyda River were detected polygonal-wedge, lens massive and lensoid ice were. A detailed analysis of structural and textural peculiarities in the layers was carried out for the first time for these morphological types of underground ice. Based on the cryolithological structure of host rocks and structural-textural features of ice, the main mechanisms of deposit formation – polygonal-wedge, infiltration-segregational, and congelation were determined. The development of polygonal-wedge ice occurred in an alluvial floodplain setting of sedimentation accompanied by the climate fluctuations in the end of the Late Pleistocene and Holocene. The growth of ice wedge in the second half of the Sartan Period was interrupted under the reservoirs with shallow talik waters, after freezing of which there formed infiltration-segregational lensoid formation ices. The structure of frozen thickness was complicated by the lenses of congelation ice formed in thermoerosive niches in the Holocene optimum of about 6.5 thousand years ago. At the present time is possible the formation of similar types of ice on various sections of the relief. The established peculiarities of cryogenic structure are important for the creation of paleogeographic reconstructions and forecasting the dynamics of permafrost-facies environments accompanied by the modern changes in the depth of the seasonal thaw layer and the development of thermokarst.
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Strazzulla, G., and R. E. Johnson. "Irradiation Effects on Comets and Cometary Debris." International Astronomical Union Colloquium 116, no. 1 (1989): 243–75. http://dx.doi.org/10.1017/s0252921100109716.
Повний текст джерелаАнотація:
AbstractFor the last 10 years, many experimental results have been obtained on the chemical and physical changes induced by ion and electron irradiation of materials relevant to comets. Those results are reviewed here, together with their physical interpretation and their relevance for cometary astrophysics. Cometary material is, from the time of its origin, altered by the large amount of energy deposited by energetic ions. Four phases of the irradiation history are considered: the pre-cometary phase, during which interstellar dust is bombarded by cosmic-ray ions; the accretion phase, during which comets are built up, possibly in an environment rich in fast ions (T-Tau phase); the cometary phase, during which the outer layers of the comets are irradiated by galactic ions in the Oort cloud; and the post-cometary phase, during which dust, lost from the comet, is bombarded by solar ions.The relevant applications of laboratory results are reviewed. In particular, the ability of ion irradiation of simple carbon-containing ices to produce complex refractory organic materials is discussed. In the Oort cloud, this process can occur several meters into the surface, so that the buildup of a stable organic crust may occur. A comparison of ion irradiation at various stages is also made with other models for the production of organics.
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Duarte, Eduardo Seperuelo, Alicja Domaracka, Philippe Boduch, Hermann Rothard, Emmanuel Balanzat, Emmanuel Dartois, Sergio Pilling, Lucio Farenzena, and Enio Frota da Silveira. "Heavy ion irradiation of astrophysical ice analogs." Proceedings of the International Astronomical Union 5, S263 (August 2009): 29–32. http://dx.doi.org/10.1017/s1743921310001444.
Повний текст джерелаАнотація:
AbstractIcy grain mantles consist of small molecules containing hydrogen, carbon, oxygen and nitrogen atoms (e.g. H2O, CO, CO2, NH3). Such ices, present in different astrophysical environments (giant planets satellites, comets, dense clouds, and protoplanetary disks), are subjected to irradiation of different energetic particles: UV radiation, ion bombardment (solar and stellar wind as well as galactic cosmic rays), and secondary electrons due to cosmic ray ionization of H2. The interaction of these particles with astrophysical ice analogs has been the object of research over the last decades. However, there is a lack of information on the effects induced by the heavy ion component of cosmic rays in the electronic energy loss regime. The aim of the present work is to simulate of the astrophysical environment where ice mantles are exposed to the heavy ion cosmic ray irradiation.Sample ice films at 13K were irradiated by nickel ions with energies in the 1-10 MeV/u range and analyzed by means of FTIR spectrometry. Nickel ions were used because their energy deposition is similar to that deposited by iron ions, which are particularly abundant cosmic rays amongst the heaviest ones.In this work the effects caused by nickel ions on condensed gases are studied (destruction and production of molecules as well as associated cross sections, sputtering yields) and compared with respective values for light ions and UV photons.
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Qasim, D., K. J. Chuang, G. Fedoseev, S. Ioppolo, A. C. A. Boogert, and H. Linnartz. "Formation of interstellar methanol ice prior to the heavy CO freeze-out stage." Astronomy & Astrophysics 612 (April 2018): A83. http://dx.doi.org/10.1051/0004-6361/201732355.
Повний текст джерелаАнотація:
Context. The formation of methanol (CH3OH) on icy grain mantles during the star formation cycle is mainly associated with the CO freeze-out stage. Yet there are reasons to believe that CH3OH also can form at an earlier period of interstellar ice evolution in CO-poor and H2O-rich ices. Aims. This work focuses on CH3OH formation in a H2O-rich interstellar ice environment following the OH-mediated H-abstraction in the reaction, CH4 + OH. Experimental conditions are systematically varied to constrain the CH3OH formation yield at astronomically relevant temperatures. Methods. CH4, O2, and hydrogen atoms are co–deposited in an ultrahigh vacuum chamber at 10–20 K. OH radicals are generated by the H + O2 surface reaction. Temperature programmed desorption – quadrupole mass spectrometry (TPD–QMS) is used to characterize CH3OH formation, and is complemented with reflection absorption infrared spectroscopy (RAIRS) for CH3OH characterization and quantitation. Results. CH3OH formation is shown to be possible by the sequential surface reaction chain, CH4 + OH → CH3 + H2O and CH3 + OH → CH3OH at 10–20 K. This reaction is enhanced by tunneling, as noted in a recent theoretical investigation Lamberts et al. (2017, A&A, 599, A132). The CH3OH formation yield via the CH4 + OH route versus the CO + H route is approximately 20 times smaller for the laboratory settings studied. The astronomical relevance of the new formation channel investigated here is discussed.
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Kilada, Raouf W., Steven E. Campana, and Dale Roddick. "Validated age, growth, and mortality estimates of the ocean quahog (Arctica islandica) in the western Atlantic." ICES Journal of Marine Science 64, no. 1 (October 24, 2006): 31–38. http://dx.doi.org/10.1093/icesjms/fsl001.
Повний текст джерелаАнотація:
Abstract Kilada, R. W., Campana S. E., and Roddick, D. 2007. Validated age, growth, and mortality estimates of the ocean quahog (Arctica islandica) in the western Atlantic. ICES Journal of Marine Science, 64: 31–38. The age structure of offshore (Sable Bank) and inshore (St Mary's Bay) populations of eastern Canadian ocean quahogs (Arctica islandica), and of a northwestern Iceland population, is investigated. Age estimates for eastern Canadian ocean quahogs were validated through analysis of bomb-produced 14C in quahog shell growth increments deposited before, during, and after the atmospheric atomic bomb testing periods of the 1950s and 1960s. Delta 14C from shells with presumed birthdates between the late 1950s and 1970s clearly reflects the sharp increase in oceanic radiocarbon attributable to nuclear testing. The results validate our age interpretations of Sable Bank quahogs to an age of 45 y, and support longevity estimates of more than 200 y for the same population. Longevity calculations for the other populations exceeded 60 y. Von Bertalanffy growth parameters were estimated for the three populations; the growth rate of all three was relatively rapid for the first 20–30 y of life, but thereafter was very slow. The instantaneous rate of natural mortality (M), calculated using the age–frequency distribution of the unexploited populations, was estimated to be 0.03 and 0.10 for the Sable Bank and St Mary's Bay populations, respectively.
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de Barros, A. L. F., C. Mejía, E. Seperuelo Duarte, A. Domaracka, P. Boduch, H. Rothard, and E. F. da Silveira. "Chemical reactions in H2O:CO interstellar ice analogues promoted by energetic heavy-ion irradiation." Monthly Notices of the Royal Astronomical Society 511, no. 2 (January 27, 2022): 2491–504. http://dx.doi.org/10.1093/mnras/stac171.
Повний текст джерелаАнотація:
ABSTRACT H2O:CO, at concentrations of (3:2) and (10:1), was condensed on CsI substrate at 15 K and irradiated with 46-MeV 58Ni11 + ion beam. Radiolysis induced by fast heavy ions was analyzed by infrared spectroscopy (FTIR). The formation of nine molecular species: CO2, H2O2, HCOOH, HCO, H2CO, 13CO2, CH3OH, O3, and C3O2 was observed. For both concentrations, carbon dioxide (CO2), formaldehyde (H2CO), formic acid (HCOOH), and hydrogen peroxide (H2O2) are the most abundant products species, and tricarbon dioxide (C3O2) is much less abundant. Precursor destruction cross-sections and formation cross-sections of products are determined. The CO destruction cross-section for the (3:2) concentration is almost five times higher than that of water, while those for the (10:1) concentration are practically the same. Atomic sputtering yields are estimated for the two ice films, the total mass sputtered is approximately 2.5 × 106 u per impact. These results contribute to figure out the chemical pathways of compounds synthesized from the two most abundant organic species (H2O and CO) observed in the ices of grain mantles of the circumstellar envelopes and interstellar medium. In additional, the finding results reveal that molecular astronomical percentages are comparable to those obtained after 15 eV molec−1 of deposited dose in current experiments compared with the relative concentration of molecules in solid phase observed in MYSO, LYSO, BG Stars, and Comets.
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Nopiardo, Widi. "STRATEGI FUNDRAISING DANA ZAKAT PADA BAZNAS KABUPATEN TANAH DATAR." Imara: JURNAL RISET EKONOMI ISLAM 1, no. 1 (March 30, 2018): 57. http://dx.doi.org/10.31958/imara.v1i1.991.
Повний текст джерелаАнотація:
Fundraising activities are essential for the operation of zakat management programs and its operations. In BAZNAS, Tanah Datarregency, it is found that in 2013, the total of zakat fundraising is Rp.8.418.272.757, -, 2014 the total of zakat fundraising is Rp. 8.754.155.665,-, 2015 the total is Rp. 9.179.036.735,-, 2016 the total is Rp. 11.148.298.358,-. While for the following years, it increases signiicantly. In 2014, Zakat fundraising was enhanced 3.99% with Rp. 335.882.908. It was from Rp.8.418.272.757 to Rp.8.754.155.665. It also increased 4.85% with Rp. 424.881.070 in 2015. It was from Rp.8.754.155.665to Rp.9.179.036.735. It also significantly boosted in 2016 for 21.45% with Rp. 1.969.261.623. It was from Rp.9.179.036.735 to Rp. 11.148.298.358. These facts indicate a precise strategy used by BAZNAS, Tanah Datarregency in doing zakat fundraising. This type of research was field research with qualitative descriptive approach. Data were collected through interviews, documentation, and literature study. The results showed that BAZNAS, Tanah Datar regency used strategy direct and indirect fundraising. If the muzakki have expressed their willingness to pay zakat through media campaigns and direct fundraising, BAZNAS, Tanah Datar regencyused three ways to ease the muzakki to pay their zakat. First, do direct cutting through UPZ which has been formed to be deposited into the account of BAZNAS Tanah Datar. Second, do "pick up theball", the oficer of BAZNAS Tanah Datar will collect zakat directly to muzakki’s place. Third, invite muzakki to distribute his zakat through the account of BAZNAS Tanah Datar.
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Dartois, E., and F. Langlet. "Carbon dioxide clathrate hydrate formation at low temperature." Astronomy & Astrophysics 652 (August 2021): A74. http://dx.doi.org/10.1051/0004-6361/202140858.
Повний текст джерелаАнотація:
Context. The formation and presence of clathrate hydrates could influence the composition and stability of planetary ices and comets; they are at the heart of the development of numerous complex planetary models, all of which include the necessary condition imposed by their stability curves, some of which include the cage occupancy or host–guest content and the hydration number, but fewer take into account the kinetics aspects. Aims. We measure the temperature-dependent-diffusion-controlled formation of the carbon dioxide clathrate hydrate in the 155–210 K range in order to establish the clathrate formation kinetics at low temperature. Methods. We exposed thin water ice films of a few microns in thickness deposited in a dedicated infrared transmitting closed cell to gaseous carbon dioxide maintained at a pressure of a few times the pressure at which carbon dioxide clathrate hydrate is thermodynamically stable. The time dependence of the clathrate formation was monitored with the recording of specific infrared vibrational modes of CO2 with a Fourier Transform InfraRed spectrometer. Results. These experiments clearly show a two-step clathrate formation, particularly at low temperature, within a relatively simple geometric configuration. We satisfactorily applied a model combining surface clathration followed by a bulk diffusion–relaxation growth process to the experiments and derived the temperature-dependent-diffusion coefficient for the bulk spreading of clathrate. The derived apparent activation energy corresponding to this temperature-dependent-diffusion coefficient in the considered temperature range is Ea = 24.7 ± 9.7 kJ mol−1. The kinetics parameters favour a possible carbon dioxide clathrate hydrate nucleation mainly in planets or satellites.
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Griffiths, Shane P., Gary C. Fry, Fiona J. Manson, and Dong C. Lou. "Age and growth of longtail tuna (Thunnus tonggol) in tropical and temperate waters of the central Indo-Pacific." ICES Journal of Marine Science 67, no. 1 (August 30, 2009): 125–34. http://dx.doi.org/10.1093/icesjms/fsp223.
Повний текст джерелаАнотація:
Abstract Griffiths, S. P., Fry, G. C., Manson, F. J., and Lou, D. C. 2010. Age and growth of longtail tuna (Thunnus tonggol) in tropical and temperate waters of the central Indo-Pacific. – ICES Journal of Marine Science, 67: 125–134. Age and growth of longtail tuna (Thunnus tonggol) were assessed by examination of annual growth increments in sectioned sagittal otoliths from 461 fish (238–1250 mm fork length, LF) sampled from tropical and temperate waters in the central Indo-Pacific between February 2003 and April 2005. Edge and microincrement analyses (presumed daily increments) suggest that longtail tuna deposit a single annual growth increment mainly between August and October. Age was, therefore, estimated for all fish by counting assumed annual growth increments. Ages ranged from 154 d to 18.7 years, with most fish being 3–9 years. Five growth models were fitted to length-at-age data, all of which indicated that the species is relatively slow-growing and long-lived. Recaptures of two tagged fish at liberty for 6.2 and 10.5 years support this notion. A bias-corrected form of Akaike's Information Criterion determined that the Schnute–Richards model provided the best fit to length-at-age data, with model parameter estimates (sexes combined) of L∞ = 135.4 cm LF, K = 22.3 year−1, t0 = 0.120 years, δ = 150.0, v = 0.019, and γ = 2.7 × 10−8. There was no significant difference in growth between sexes. The results suggest that longtail tuna grow more slowly and live longer than other tuna species of similar size. Coupled with their restricted neritic distribution, longtail tuna may be vulnerable to overexploitation by fisheries, and caution needs to be exercised in managing the species until more reliable biological and catch data are collected to assess the status of the population.
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Kirik, S. D., L. A. Solovyov, A. I. Blokhin, and I. S. Yakimov. "Structures of [Pd(NH3)2 X 2] and its chemical transformation in the solid state." Acta Crystallographica Section B Structural Science 56, no. 3 (June 1, 2000): 419–25. http://dx.doi.org/10.1107/s0108768100000252.
Повний текст джерелаАнотація:
Crystal structures of [Pd(NH3)2 X 2] complexes, where X = Br or I, diamminediiodo-/-dibromopalladium(II), have been studied by X-ray powder diffraction. The series consists of five complexes: cis-[Pd(NH3)2Br2] (I) [a = 13.3202 (7), b = 12.7223 (6), c = 7.05854 (3) Å, Z = 8, space group Pbca], trans-[Pd(NH3)2Br2] (II) [a = 6.7854 (3), b = 7.1057 (3), c = 6.6241 (2) Å, α = 103.221 (3), β = 102.514 (2), γ = 100.386 (3)°, Z = 2, space group P\overline 1], β-trans-[Pd(NH3)2Br2] (III) [a = 8.4315 (3), b = 8.4206 (3), c = 8.0916 (2) Å, Z = 4, space group Pbca], cis-[Pd(NH3)2I2] (IV) [a = 13.9060 (8), b = 13.5035 (8), c = 7.5050 (4) Å, Z = 8, space group Pbca], and β-trans-[Pd(NH3)2I2] (V) [a = 8.8347 (5), b = 8.8410 (5), c = 8.6081 (2) Å, Z = 4, space group Pbca]. Patterson synthesis and Rietveld refinement have been used for structural determination. Molecular structures with column- or parquet-type packing of flat complexes are characteristic of these substances. Corresponding cis- and β-trans compounds are isostructural. The thermal transformations cis→trans→β-trans (cis→β-trans in the case of iodine) are considered. Cl derivatives are also discussed. The transformations proceed irreversibly and are accompanied by decreasing specific volume. Owing to these features, they can be classified as chemical reactions. High-temperature X-ray powder diffraction was used to study the transformations in air. The set of data is consistent with a solid state transformation from cis to trans. According to this model, the columns of molecules remain intact during the process, and the transformation proceeds via the breaking of Pd...X and Pd...N intermolecular bonds. The powder diffraction data have been deposited in ICDD-JCPDS (45-0596, 46-0876, 46-0879, 47-1690, 48-1185).