Techmer, Kirsten S.

[["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.issue","1-4"],["dc.bibliographiccitation.journal","Marine Geology"],["dc.bibliographiccitation.lastpage","14"],["dc.bibliographiccitation.volume","244"],["dc.contributor.author","Bohrmann, Gerhard"],["dc.contributor.author","Kuhs, Werner F."],["dc.contributor.author","Klapp, Stephan A."],["dc.contributor.author","Techmer, Kirsten S."],["dc.contributor.author","Klein, Helmut"],["dc.contributor.author","Murshed, M. Mangir"],["dc.contributor.author","Abegg, Fritz"],["dc.date.accessioned","2018-11-07T10:57:49Z"],["dc.date.available","2018-11-07T10:57:49Z"],["dc.date.issued","2007"],["dc.description.abstract","The state of preservation of natural gas hydrate samples, recovered from 6 sites drilled during ODP Leg 204 at southern summit of Hydrate Ridge, Oregon Margin, has been investigated by X-ray diffraction (XRD) and cryo-scanning-electron-inicroscopy (cryo-SEM) techniques. A detailed characterization of the state of decomposition of gas hydrates is necessary since no pressurized autoclave tools were used for sampling and partial dissociation must have occurred during recovery prior to the quench and storage in liquid nitrogen. Samples from 16 distinct horizons have been investigated by synchrotron X-ray diffraction measurements at HASYLAB/ Hamburg. A full profile fitting analysis (\"Rietveld method\") of synchrotron XRD data provides quantitative phase determinations of the major sample constituents such as gas hydrate structure I (sI), hexagonal ice (Ih) and quartz. The ice content (Ih) in each sample is related to frozen water composed of both original existing pore water and the water from decomposed hydrates. Hydrate contents as measured by diffraction vary between 0 and 68 wt.% in the samples we measured. Samples with low hydrate content usually show micro-structural features in cryo-SEM ascribed to extensive decomposition. Comparing the appearance of hydrates at different scales, the grade of preservation seems to be primarily correlated with the contiguous volume of the original existing hydrate; the dissociation front appears to be indicated by micrometer-sized pores in a dense ice matrix. (c) 2007 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.margeo.2007.05.003"],["dc.identifier.isi","000250150800001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/50340"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","0025-3227"],["dc.title","Appearance and preservation of natural gas hydrate from Hydrate Ridge sampled during ODP Leg 204 drilling"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3899"],["dc.bibliographiccitation.issue","11"],["dc.bibliographiccitation.journal","Clinical Oral Investigations"],["dc.bibliographiccitation.lastpage","3909"],["dc.bibliographiccitation.volume","24"],["dc.contributor.author","Wassmann, Torsten"],["dc.contributor.author","Schubert, Andrea"],["dc.contributor.author","Malinski, Felix"],["dc.contributor.author","Rosentritt, Martin"],["dc.contributor.author","Krohn, Sebastian"],["dc.contributor.author","Techmer, Kirsten"],["dc.contributor.author","Bürgers, Ralf"],["dc.date.accessioned","2020-12-10T14:11:05Z"],["dc.date.available","2020-12-10T14:11:05Z"],["dc.date.issued","2020"],["dc.identifier.doi","10.1007/s00784-020-03257-w"],["dc.identifier.eissn","1436-3771"],["dc.identifier.issn","1432-6981"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/70959"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","The antimicrobial and cytotoxic effects of a copper-loaded zinc oxide phosphate cement"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","459"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","Canadian Journal of Physics"],["dc.bibliographiccitation.lastpage","468"],["dc.bibliographiccitation.volume","81"],["dc.contributor.author","Legagneux, L."],["dc.contributor.author","Lauzier, T."],["dc.contributor.author","Domine, F."],["dc.contributor.author","Kuhs, Werner F."],["dc.contributor.author","Heinrich, Steffen"],["dc.contributor.author","Techmer, Kirsten S."],["dc.date.accessioned","2018-11-07T10:42:07Z"],["dc.date.available","2018-11-07T10:42:07Z"],["dc.date.issued","2003"],["dc.description.abstract","The quantification of the specific surface area (SSA) of snow crystals and of its variation during metamorphism are essential to understand and model the exchange of reactive gases between the snowpack and the atmosphere. Therefore, the decay rate of SSA of five fresh snow samples was studied in the laboratory at -4, -10, and -15degreesC under isothermal conditions in closed systems. The time-evolution of the snow SSA can in all cases be very well described by an empirical law of the form, SSA = - A log(t + Deltat) + B, where A, B, and Deltat are adjustable parameters. B seems to be closely related to the initial SSA of the snow, and A describes the SSA decay rate. Our preliminary findings at -15degreesC suggest that a linear relationship exists between A and B, so that it may be possible to predict the decay rate of snow SSA from its initial value. For the first time, images obtained from scanning electron microscopy show that crystal rounding of snow is the main process taking place during isothermal metamorphism. New grain boundaries also form. More surprising, however, was the formation of new basal, prismatic, and pyramidal crystal faces, sometimes with very sharp angles, especially at -15degreesC. The growth of facets with sharp angles is not fully explained by current theories of snow metamorphism and has not been observed before."],["dc.identifier.doi","10.1139/P03-025"],["dc.identifier.isi","000183264100056"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/46710"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Canadian Science Publishing, Nrc Research Press"],["dc.relation.issn","1208-6045"],["dc.relation.issn","0008-4204"],["dc.title","Rate of decay of specific surface area of snow during isothermal experiments and morphological changes studied by scanning electron microscopy"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","305"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","International Journal of Offshore and Polar Engineering"],["dc.bibliographiccitation.lastpage","309"],["dc.bibliographiccitation.volume","14"],["dc.contributor.author","Kuhs, Werner F."],["dc.contributor.author","Genov, G."],["dc.contributor.author","Goreshnik, E."],["dc.contributor.author","Zeller, A."],["dc.contributor.author","Techmer, Kirsten S."],["dc.contributor.author","Bohrmann, Gerhard"],["dc.date.accessioned","2018-11-07T10:43:27Z"],["dc.date.available","2018-11-07T10:43:27Z"],["dc.date.issued","2004"],["dc.description.abstract","Methane hydrates front both sub-permafrost and seafloor occurrences show a very particular microstructure as evidenced by scanning electron microscopy. These hydrates are frequently porous. with typical pore sizes ranging front 100 not to 500 nor and occasionally reaching 1 mum. The pores are predominantly. closed with only occasional openings between them. and they are filled with methane gas. The gas-filling will affect the physical properties of gas hydrates. In particular. an increase in the attenuation of elastic waves can be expected. We suggest that the repeatedly observed combination of high seismic velocities and high attenuation in gas hydrate-bearing sediments may well be attributed to the presence of gas in the porous microstructures."],["dc.identifier.isi","000225741900009"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/47056"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Int Soc Offshore Polar Engineers"],["dc.publisher.place","Cupertino"],["dc.relation.conference","14th International Offshore and Polar Engineering Conference (ISOPE 2004)"],["dc.relation.eventlocation","Toulon, FRANCE"],["dc.relation.issn","1053-5381"],["dc.title","The impact of porous microstructures of gas hydrates on their macroscopic properties"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","116"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Marine and Petroleum Geology"],["dc.bibliographiccitation.lastpage","125"],["dc.bibliographiccitation.volume","27"],["dc.contributor.author","Klapp, Stephan A."],["dc.contributor.author","Bohrmann, Gerhard"],["dc.contributor.author","Kuhs, Werner F."],["dc.contributor.author","Murshed, M. Mangir"],["dc.contributor.author","Pape, Thomas"],["dc.contributor.author","Klein, Helmut"],["dc.contributor.author","Techmer, Kirsten S."],["dc.contributor.author","Heeschen, Katja U."],["dc.contributor.author","Abegg, Friedrich"],["dc.date.accessioned","2018-11-07T08:48:06Z"],["dc.date.available","2018-11-07T08:48:06Z"],["dc.date.issued","2010"],["dc.description.abstract","Gas hydrate samples from various locations in the Gulf of Mexico (GOM) differ considerably in their microstructure. Distinct microstructure characteristics coincide with discrete crystallographic structures, gas compositions and calculated thermodynamic stabilities. The crystallographic structures were established by X-ray diffraction, using both conventional X-ray sources and high-energy synchrotron radiation. The microstructures were examined by cryo-stage Field-Emission Scanning Electron Microscopy (FE-SEM). Good sample preservation was warranted by the low ice fractions shown from quantitative phase analyses. Gas hydrate structure II samples from the Green Canyon in the northern GOM had methane concentrations of 70-80% and up to 30% of C-2-C-5 of measured hydrocarbons. Hydrocarbons in the crystallographic structure I hydrate from the Chapopote asphalt volcano in the southern GOM was comprised of more than 98% methane. Fairly different microstructures were identified for those different hydrates: Pores measuring 200-400 nm in diameter were present in structure I gas hydrate samples; no such pores but dense crystal surfaces instead were discovered in structure II gas hydrate. The stability of the hydrate samples is discussed regarding gas composition, crystallographic structure and microstructure. Electron microscopic observations showed evidence of gas hydrate and liquid oil co-occurrence on a micrometer scale. That demonstrates that oil has direct contact to gas hydrates when it diffuses through a hydrate matrix. (C) 2009 Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.marpetgeo.2009.03.004"],["dc.identifier.isi","000272308200010"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21128"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Sci Ltd"],["dc.relation.issn","0264-8172"],["dc.title","Microstructures of structure I and II gas hydrates from the Gulf of Mexico"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","102376"],["dc.bibliographiccitation.journal","Journal of South American Earth Sciences"],["dc.bibliographiccitation.volume","96"],["dc.contributor.author","Oriolo, Sebastián"],["dc.contributor.author","Ozán, Ivana L."],["dc.contributor.author","Schmidt, Burkhard C."],["dc.contributor.author","Charlin, Judith E."],["dc.contributor.author","Manzi, Liliana M."],["dc.contributor.author","Techmer, Kirsten"],["dc.date.accessioned","2020-12-10T14:25:25Z"],["dc.date.available","2020-12-10T14:25:25Z"],["dc.date.issued","2019"],["dc.identifier.doi","10.1016/j.jsames.2019.102376"],["dc.identifier.issn","0895-9811"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/72548"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.title","Basalt weathering as the key to understand the past human use of hematite-based pigments in southernmost Patagonia"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","33"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Microscopy Research and Technique"],["dc.bibliographiccitation.lastpage","48"],["dc.bibliographiccitation.volume","62"],["dc.contributor.author","Domine, F."],["dc.contributor.author","Lauzier, T."],["dc.contributor.author","Cabanes, A."],["dc.contributor.author","Legagneux, L."],["dc.contributor.author","Kuhs, Werner F."],["dc.contributor.author","Techmer, Kirsten S."],["dc.contributor.author","Heinrich, Steffen"],["dc.date.accessioned","2018-11-07T10:36:40Z"],["dc.date.available","2018-11-07T10:36:40Z"],["dc.date.issued","2003"],["dc.description.abstract","Current theories of snow metamorphism indicate that sublimating snow crystals have rounded shapes, while growing crystals have shapes that depend on growth rates. At slow growth rates, crystals are rounded. At moderate rates, they have flat faces with rounded edges. At fast growth rates, crystals have flat faces with sharp edges, and they have hollow faces at very fast growth rates. The main growth/sublimation mechanism is thought to be by the homogeneous nucleation of new layers at or near crystal edges. It was also suggested that the equilibrium shape of snow crystals would be temperature dependent: rounded above - 10.5degreesC, and faceted below. To test these paradigms, we have performed SEM investigations of snow samples having undergone metamorphism under natural conditions, and of snow samples subjected to isothermal metamorphism at -4degrees and -15degreesC in the laboratory. In general, current theories predicting crystal shapes as a function of growth rates, and of whether crystals are growing or sublimating, are verified. However, the transition in equilibrium shapes from rounded to faceted at - 10.5degreesC is not observed in our isothermal experiments that reveal a predominance of rounded shapes after more than a month of metamorphism at - 4 and -15degreesC. Some small crystals with flat faces that also have sharp angles at - 15degreesC, are observed in our isothermal experiments. These faces are newly formed, and contradict current theory. Several hypotheses are proposed to explain their occurrence. One is that they are due to sublimation at emerging dislocations. (C) 2003 Wky-Liss. Inc."],["dc.identifier.doi","10.1002/jemt.10384"],["dc.identifier.isi","000184886300004"],["dc.identifier.pmid","12938116"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45381"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-liss"],["dc.relation.issn","1059-910X"],["dc.title","Snow metamorphism as revealed by scanning electron microscopy"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","62"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Environmental Chemistry"],["dc.bibliographiccitation.lastpage","73"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Ariya, P. A."],["dc.contributor.author","Domine, F."],["dc.contributor.author","Kos, G."],["dc.contributor.author","Amyot, M."],["dc.contributor.author","Cote, V."],["dc.contributor.author","Vali, H."],["dc.contributor.author","Lauzier, T."],["dc.contributor.author","Kuhs, Werner F."],["dc.contributor.author","Techmer, Kirsten S."],["dc.contributor.author","Heinrich, Steffen"],["dc.contributor.author","Mortazavi, R."],["dc.date.accessioned","2018-11-07T09:01:08Z"],["dc.date.available","2018-11-07T09:01:08Z"],["dc.date.issued","2011"],["dc.description.abstract","Field and laboratory studies of organic compounds in snow (12 species; concentrations <= 17 mu g L(-1)) were conducted and microorganisms in snow and aerosols at urban and Arctic sites were investigated (snow: total bacteria count <= 40000 colony forming units per millilitre (CFU mL(-1)), fungi <= 400 CFU mL(-1); air: bacteria <= 2.2 x 10(7) CFU m(-3), fungi <= 84 CFU m(-3)). Bio-organic material is transferred between snow and air and influence on snow-air exchange processes is demonstrated. Volatile organic compounds in snow are released into the air upon melting. In vitro photochemistry indicated an increase of <= 60 mu g L(-1) for 1,3- and 1,4-dimethylbenzenes. Bacillus cereus was identified and observed in snow and air with ice-nucleating being P. syringae absent. As a result snow photobiochemical reactions should be considered in describing organic matter air-snow exchanges, and the investigation of climate change."],["dc.description.sponsorship","NSERC; FQRNT; CFI"],["dc.identifier.doi","10.1071/EN10056"],["dc.identifier.isi","000287764800008"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/24342"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Csiro Publishing"],["dc.relation.issn","1448-2517"],["dc.title","Snow - a photobiochemical exchange platform for volatile and semi-volatile organic compounds with the atmosphere"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2929"],["dc.bibliographiccitation.issue","18"],["dc.bibliographiccitation.journal","Geophysical Research Letters"],["dc.bibliographiccitation.lastpage","2932"],["dc.bibliographiccitation.volume","27"],["dc.contributor.author","Kuhs, Werner F."],["dc.contributor.author","Klapproth, A."],["dc.contributor.author","Gotthardt, F."],["dc.contributor.author","Techmer, Kirsten S."],["dc.contributor.author","Heinrich, Steffen"],["dc.date.accessioned","2018-11-07T10:09:55Z"],["dc.date.available","2018-11-07T10:09:55Z"],["dc.date.issued","2000"],["dc.description.abstract","We present results of experimental studies on the formation of gas hydrates (clathrates) at conditions of geophysical interest. Clathrate hydrates formed by a reaction of gas at ice Ih surfaces are always found to be mesoporous to macroporous with pores sizes between 100 to 400 nm and pore volumes of approximately 25-40% for CH4, Ar and Nz hydrate, and smaller pores of 20 to 100 nm with a porosity of approximately 10-20% for CO2 hydrate. The three-dimensional sponge-like microstructure occurs in single crystalline grains of typically a few mu m size and was observed by field-emission scanning electron microscopy. It forms over a wide range of p-T conditions below the ice Ih melting. The porous microstructure is stable for at least several months, even close to the clathrate decomposition, and is proposed to be formed by local differences in the energy balance between hydrate formation and ice decompositon. The results presented are considered of potential major importance for the understanding of the behaviour of natural gas hydrates found e.g. in polar ice sheets and permafrost regions, and also in some celestial bodies."],["dc.identifier.doi","10.1029/2000GL006112"],["dc.identifier.isi","000089390400027"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/39748"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Geophysical Union"],["dc.relation.issn","0094-8276"],["dc.title","The formation of meso- and macroporous gas hydrates"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]