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  • Elsevier  (308,943)
  • American Physical Society  (46,634)
  • Wiley-Blackwell  (24,590)
  • 2020-2022
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  • 2010-2014  (144,142)
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  • 1
    Publication Date: 2020-12-21
    Description: We detail the Kamil crater (Egypt) structure and refine the impact scenario, based on the geological and geophysical data collected during our first expedition in February 2010. Kamil Crater is a model for terrestrial small-scale hypervelocity impact craters. It is an exceptionally well-preserved, simple crater with a diameter of 45 m, depth of 10 m, and rayed pattern of bright ejecta. It occurs in a simple geological context: flat, rocky desert surface, and target rocks comprising subhorizontally layered sandstones. The high depth-to-diameter ratio of the transient crater, its concave, yet asymmetric, bottom, and the fact that Kamil Crater is not part of a crater field confirm that it formed by the impact of a single iron mass (or a tight cluster of fragments) that fragmented upon hypervelocity impact with the ground. The circular crater shape and asymmetries in ejecta and shrapnel distributions coherently indicate a direction of incidence from the NW and an impact angle of approximately 30 to 45 . Newly identified asymmetries, including the off-center bottom of the transient crater floor downrange, maximum overturning of target rocks along the impact direction, and lower crater rim elevation downrange, may be diagnostic of oblique impacts in well-preserved craters. Geomagnetic data reveal no buried individual impactor masses 〉100 kg and suggest that the total mass of the buried shrapnel 〉100 g is approximately 1050–1700 kg. Based on this mass value plus that of shrapnel 〉10 g identified earlier on the surface during systematic search, the new estimate of the minimum projectile mass is approximately 5 t.
    Description: Published
    Description: 1842–1868
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: Impact craters ; geophysical survey ; iron meteorite ; impact scenario ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2020-12-07
    Description: We present new stratigraphic, palaeomagnetic, 87Sr/86Sr and 40Ar/39Ar data from a lacustrine succession of the Sulmona basin, central Italy, which, according to an early study, included six unconformitybounded lacustrine units (from SUL6, oldest, to SUL1, youngest) spanning the interval 〉600 to 2 ka. The results of the present study, on the one hand confirm some of the previous conclusions, but by contrast reveal that units SUL2 and SUL1, previously attributed to the Holocene, are actually equivalent to the older SUL6 and SUL5 units – here dated to 814–〉530 ka and 530–〈457 ka, respectively – and that the U-series dates previously published for both former SUL2 and SUL1 units yielded abnormally young ages. In light of the present results, a reassessment of the chronology of the Sulmona basin succession and a revision of the tephrostratigraphy of the SUL2/SUL6 and SUL1/SUL5 units is in order.
    Description: Published
    Description: 545–551
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: 40Ar/39Ar dating; central Italy ; Sr isotope composition ; Sulmona lacustrine succession ; Brunhes–Matuyama geomagnetic reversal ; tephrostratigraphy ; U-series dating ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Publication Date: 2020-12-15
    Description: Seismogram envelopes recorded at Campi Flegrei caldera show diffusive characteristics as well as steep amplitude increases in the intermediate and late coda, which can be related to the presence of a non-uniformly scattering medium. In this paper, we first show the results of a simulation with a statistical model considering anisotropic scattering interactions, in order to match coda-envelope duration and shape.We consider as realistic parameters for a volcanic caldera the presence of large square root velocity fluctuations (10 per cent) and two typical correlation lengths for such an heterogeneous crust, a = 0.1 and 1 km. Then, we propose the inclusion of a diffusive boundary condition in the stochastic description of multiple scattering, in order to model intermediate and late coda intensities, and particularly the sharp intensity peaks at some stations in the caldera. Finally, we show that a reliable 2-D synthetic model of the envelopes produced by earthquakes vertically sampling a small region can be obtained including a single drastic change of the scattering properties of the volcano, that is, a caldera rim of radius 3 km, and sections varying between 2 and 3 km. These boundary conditions are diffusive, which signifies that the rim must have more scattering potential than the rest of the medium, with its diffusivity 2–3 orders of magnitude lower than the one of the background medium, so that the secondary sources on its interface(s) could enhance coda intensities. We achieve a good first-order model of high-frequency (18 Hz) envelope broadening adding to the Monte Carlo solution for the incident flux the secondary source effects produced by a closed annular boundary, designed on the caldera rim signature at 1.5 km depth. At lower frequencies (3 Hz) the annular boundary controls the intermediate and late coda envelope behaviour, in a way similar to an extended diffusive source. In our interpretation, the anomalous intensities observed at several stations and predicted by the final Monte Carlo solutions are mainly due to the diffusive transmission reflection from a scattering object of increased scattering power, and are controlled by its varying thickness.
    Description: This work was carried out under the HPC-Europa2 project (project number: 228398) with the support of the European Commission Capacities Area-Research Infrastructures Initiative. We thank the whole staff at EPCC (Edinburgh Parallel Computing Centre) in Edinburgh and particularly Dr. Adam Carter for their help in both developing and parallelizing the code. The challenging comments and suggestions of the editor and two anonymous reviewers helped both in focusing the aim and in overcoming the strong limits of a previous version of the paper.
    Description: Published
    Description: 1102–1119
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: Numerical solutions; ; Seismic anisotropy; ; Seismic attenuation ; Seismic tomography ; Wave scattering and diffraction ; Calderas ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Elsevier
    In:  EPIC3Earth and Planetary Science Letters, Elsevier, 375, pp. 408-417, ISSN: 0012-821X
    Publication Date: 2014-06-25
    Description: The Miocene expansion of C4 plants (mainly tropical grasses) between 8 and 4 million years (Ma) remains an enigma since regional differences in the timing of the expansion rules out decreased CO2 (pCO2) as a dominant forcing [e.g. Tipple and Pagani, 2007. The early origins of terrestrial C4 photosynthesis. Annu. Rev. Earth Planet. Sci. 35, 435–461]. Other environmental factors, such as low-latitude aridity and seasonality have been proposed to explain the low tree versus grass ratio found in savannahs and tropical grasslands of the world, but conclusive evidence is missing. Here we use pollen and stable carbon (δ13C) and hydrogen (δD) isotope ratios of terrestrial plant wax from a South Atlantic sediment core (ODP Site 1085) to reconstruct Miocene to Pliocene changes of vegetation and rainfall regime of western southern Africa. Our results reveal changes in the relative amount of precipitation and indicate a shift of the main moisture source from the Atlantic to the Indian Ocean during the onset of a major aridification 8 Ma ago. We emphasize the importance of declining precipitation during the expansion of C4 and CAM (mainly succulent) vegetation in South Africa. We suggest that the C4 plant expansion resulted from an increased equator-pole temperature gradient caused by the initiation of strong Atlantic Meridional Overturning Circulation following the shoaling of the Central American Seaway during the Late Miocene.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
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  • 6
    Publication Date: 2017-06-14
    Description: Linear Pottery Culture (LBK) are investigated. These are interpreted as resulting from a combination of internal socio-economic processes as well as external environmental parameters. Resilience theory is helpful in understanding periods of increased vulnerability and inherent trends to social complexity. Cycles and threshold levels also help to understand why societies experience periods of increasing fragility and subsequent decline. Results are based on the correlation of a typology and dendrochronology-based archaeological chronology for western LBK and various palaeoclimatic proxy-data. The 14C-production curve is taken as an indicator for solar activity fluctuations, and an age model for laminated sediments as an indicator for rainfall fluctuations. We currently consider this correlation as agreeably robust; however future finedating may result in slight shifts within the archaeological chronology. According to the applied age model, the simple farming societies of the LBK (5600e4900 cal BC) in west-central Europe were not immediately and devastatingly affected by most climate fluctuations. Yet, they might have been one destabilising component within broader processes. However, periods of decreased or irregularly spaced rainfall are contemporaneous to periods of population decline, while periods of increased rainfall may have favoured population growth. Towards the end of the 6th millennium cal BC, the final years of LBK in western Central Europe are contemporaneous to a general trend to less rainfall punctuated by short-term increases in precipitation. During this climatically highly volatile period LBK reaches its highest population rates and at the same time experiences a period of warfare. Thereafter population rates decline and LBK gradually vanishes from the archaeological record, being replaced by Middle Neolithic societies.
    Repository Name: EPIC Alfred Wegener Institut
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  • 7
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    Elsevier
    In:  EPIC3Quaternary Science Reviews, Elsevier, 80, pp. 1-28, ISSN: 02773791
    Publication Date: 2016-11-06
    Repository Name: EPIC Alfred Wegener Institut
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  • 8
    Publication Date: 2017-04-04
    Description: Local and regional seismicity jointly recorded by two dense small aperture arrays, one installed at surface and one at 1.3 km depth, constitutes an interesting data set useful for coda observations. Applying array techniques to earthquakes recorded at the two arrays we measure slowness, backazimuth and correlation coefficient of the coherent coda wave signals in five frequency bands in the range 1–10 Hz. Slowness distributions show marked differences between surface and underground, with slow signals at surface (slowness greater than 1.0 s km−1) that are not observed underground. We interpret these coherent signals as surface waves produced by the interaction of body waves with the free surface characterized by rough topography. The backazimuth values measured in the frequency bands centred at 1.5 and 3 Hz are almost uniformly distributed between 0 and 360◦, while those measured at higher frequencies show different distributions between surface and underground. On the contrary, the earthquake envelopes show very similar coda shapes between surface and underground recordings, with an almost constant coda-amplitude ratio (between 4 and 8) in a wide frequency range.
    Description: Published
    Description: 367-371
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: restricted
    Keywords: Coda waves ; Wave scattering and diffraction ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-04
    Description: In this work, we present regional maps of the inverse intrinsic quality factor (Qi −1), the inverse scattering quality factor (Qs −1) and total inverse quality factor (Qt −1) for the volcanic environment of Deception Island (Antarctica). Our attenuation study is based on diffusion approximation, which permits us to obtain the attenuation coefficients for every single couple source-receiver separately. The data set used in this research is derived from an active seismic experiment using more than 5200 offshore shots (air guns) recorded at 32 onshore seismic stations and four ocean bottom seismometers. To arrive at a regional distribution of these values, we used a new mapping technique based on a Gaussian space probability function. This approach led us to create ‘2-D probabilistic maps’ of values of intrinsic and scattering seismic attenuation. The 2-D tomographic images confirm the existence of a high attenuation body below an inner bay of Deception Island. This structure, previously observed in 2-D and 3-D velocity tomography of the region, is associated with a massive magma reservoir. Magnetotelluric studies reach a similar interpretation of this strong anomaly. Additionally, we observed areas with lower attenuation effects that bear correlation with consolidated structures described in other studies and associated with the crystalline basement of the area. Our calculations of the transport mean-free path and absorption length for intrinsic attenuation gave respective values of ≈950 m and 5 km, which are lower than the values obtained in tectonic regions or volcanic areas such as Tenerife Island. However, as observed in other volcanic regions, our results indicate that scattering effects dominate strongly over the intrinsic attenuation.
    Description: This work has been partially supported by the Spanish project Ephestos, CGL2011–29499-C02–01, by the EU project EC-FP7 MEDiterranean SUpersite Volcanoes (MED-SUV), by the Basque Government researcher training program BFI09.277 and by the Regional project ‘Grupo de Investigaci´on en Geof´ısica y Sismolog´ıa de la Junta de Andaluc´ıa, RNM104.’ Edoardo del Pezzo was partly supported by DPC-INGV projects UNREST SPEED and V2 (Precursori).
    Description: Published
    Description: 1957-1969
    Description: 3.1. Fisica dei terremoti
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation; ; Seismic tomography ; Volcano seismology ; Wave scattering and diffraction ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: This article has been accepted for publication in Geophysical Journal International ©: The Authors 2003. Published by Oxford University Press on behalf of The Royal Astronomical Society. All rights reserved.
    Description: In this study, we modify and extend a data analysis technique to determine the stress orientations between data clusters by adding an additional constraint governing the probability algorithm. We apply this technique to produce a map of the maximum horizontal compressive stress (S_Hmax) orientations in the greater European region (including Europe, Turkey and Mediterranean Africa). Using the World Stress Map dataset release 2008, we obtain analytical probability distributions of the directional differences as a function of the angular distance, θ. We then multiply the probability distributions that are based on pre-averaged data within θ〈3° of the interpolation point and determine the maximum likelihood estimate of the S_Hmax orientation. At a given distance, the probability of obtaining a particular discrepancy decreases exponentially with discrepancy. By exploiting this feature observed in the World Stress Map release 2008 dataset, we increase the robustness of our S_Hmax determinations. For a reliable determination of the most likely S_Hmax orientation, we require that 90% confidence limits be less than ±60° and a minimum of three clusters, which is achieved for 57% of the study area, with small uncertainties of less than ±10° for 7% of the area. When the data density exceeds 0.8×10^-3 data/km2, our method provides a means of reproducing significant local patterns in the stress field. Several mountain ranges in the Mediterranean display 90° changes in the S_Hmax orientation from their crests (which often experience normal faulting) and their foothills (which often experience thrust faulting). This pattern constrains the tectonic stresses to a magnitude similar to that of the topographic stresses.
    Description: This work was supported by the DPC-INGV 2008-2010 S1 project, the EU-FP7 project “Seismic Hazard Harmonization in Europe” (SHARE; Grant agreement no. 226967), and project MIUR-FIRB "Abruzzo" (code: RBAP10ZC8K_003).
    Description: Published
    Description: 3.1. Fisica dei terremoti
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: partially_open
    Keywords: Neotectonics ; Seismicity and tectonics ; Fractures and faults ; Intra-plate processes ; Plate motions ; Dynamics: gravity and tectonics ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous
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  • 11
    Publication Date: 2017-04-04
    Description: macroseismic intensity data. A set of 2373 intensity observations from 15 earthquakes is analysed to calibrate non-parametric models for the source and attenuation with distance, the distance being computed from the instrumental epicentres located according to the International Seismological Centre (ISC) catalogue. In a second step, the non-parametric source model is regressed against different magnitude values (e.g. MLH, mb, MS, Mw) as listed in various instrumental catalogues. The reliability of the calibrated model is then assessed by applying the methodology to macroseismic intensity data from 29 validation earthquakes for which bothMLH and mb are available from the Central Asian Seismic Risk Initiative (CASRI) project and the ISC catalogue. An overall agreement is found for both the location and magnitude of these events, with the distribution of the differences between instrumental and intensity-based magnitudes having almost a zero mean, and standard deviations equal to 0.30 and 0.44 for mb and MLH, respectively. The largest discrepancies are observed for the location of the 1985, MLH = 7.0 southern Xinjiang earthquake, whose location is outside the area covered by the intensity assignments, and for the magnitude of the 1974, mb = 6.2 Markansu earthquake, which shows a difference in magnitude greater than one unit in terms of MLH. Finally, the relationships calibrated for the non-parametric source model are applied to assign different magnitude-scale values to earthquakes that lack instrumental information. In particular, an intensity-based moment magnitude is assigned to all of the validation earthquakes.
    Description: Published
    Description: 710-724
    Description: 5.1. TTC - Banche dati e metodi macrosismici
    Description: JCR Journal
    Description: restricted
    Keywords: seismicity and tectonics: seismic attenuarion; Asia ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2017-04-04
    Description: We find that geodetic strain rate (SR) integrated with the knowledge of active faults points out that hazardous seismic areas are those with lower SR, where active faults are possibly approaching the end of seismic cycle. SR values estimated from GPS velocities at epicentral areas of large historical earthquakes in Italy decrease with increasing elapsed time, thus highlighting faults more prone to reactivation. We have modelled an exponential decrease relationship between SR and the time elapsed since the last largest earthquake, differencing historical earthquakes according to their fault rupture style. Then, we have estimated the characteristic times of relaxation by a non-linear inversion, showing that events with thrust mechanism exhibit a characteristic time (∼ 990 yr) about three times larger than those with normal mechanism. Assuming standard rigidity and viscosity values we can infer an average recurrence time of about 600 yr for normal faults and about 2000 yr for thrust faults.
    Description: Published
    Description: 815-820
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic cycle ; Seismicity and tectonics ; Transient deformation ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 13
    Publication Date: 2017-04-04
    Description: Until a decade ago, regression analyses for conversions between different types of magnitude were using only the ordinary least squares method,which assumes that the independent variable is error free, or the simple orthogonal regression method,which assumes equal uncertainties for the two variables. The recent literature became aware of the inadequacy of such approaches and proposes the use of general orthogonal regression methods that account for different uncertainties of the two regression variables. Under the common assumption that only the variance ratio η between the dependent and independent variables is known, we compared three of such general orthogonal regression methods that have been applied to magnitude conversions: the chi-square regression, the general orthogonal regression, and the weighted total least squares. Although their formulations might appear quite different, we show that, under appropriate conditions, they all compute almost exactly the same regression coefficients and very similar (albeit slightly different) formal uncertainties. The latter are in most cases smaller than those estimated by bootstrap simulation but the amount of the deviation depends on the data set and on the assumed variance ratio.
    Description: European Union project SHARE (Seismic Hazard Harmonization in Europe) within the ambit of Task 3.1‘European Earthquake Database’.
    Description: Published
    Description: 1135-1151
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source observations; Statistical seismology ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-04
    Description: Co-injection of a conservative tracer during the geological sequestration of CO2 can imprint a marker to the injected gas that can be easily recognized during soil gas surveys in case of CO2 leakage from the reservoir toward the surface. In this work, an ultra-trace detection method, based on gas chromatography with electron capture detection for analyzing perfluorocarbon tracers (PFTs) in soil gas samples was optimized. Three totally fluorinated cycloalcane compounds consisting of five and six atom carbon rings were selected for this purpose. We evaluated the feasibility of collecting PFTs on adsorbent tube packed with a commercial graphitized carbon black (Carbotrap™ 100) sampling 2 L of soil gas. The sorbent tubes were then analyzed by using a two-stage thermal desorption process. The developed method allows to quickly determine these compounds at very low fL/L level, method identification limits ranged from 1.3 to 5.8 fL/L. Moreover, it shows good precision, evaluated by within-day and between-day studies. A preliminary survey of the PFT soil gas background concentrations, conducted by analyzing some soil gas samples collected in two different areas in Central Italy and in the Po Plain, ascertained the PFT background concentration lower than MIL.
    Description: Published
    Description: 60-64
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: partially_open
    Keywords: Perfluorocarbon tracers; Soil gas; Carbon dioxide storage; Leakage monitoring; GC–ECD ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
    Publication Date: 2017-04-04
    Description: We used the SBAS DInSAR analysis technique to estimate the interseismic deformation along the western part of the Doruneh fault system (DFS), northeastern Iran. We processed 90 ENVISAT images from four different frames from ascending and descending orbits. Three of the ground velocity maps show a significant interseismic signal. Using a simple dislocation approach we model 2-D velocity profiles concerning three InSAR data set relative to the western part of the DFS, obtaining a good fit to the observations. The resulting model indicates that a slip rate of ∼5mmyr−1 accumulates on the fault below 10 km depth, and that in its western sector the Doruneh fault is not purely strike-slip (left-lateral) as in its central part, but shows a significant thrust component. Based on published geological observations, and assuming that all interseismic deformation is recovered with a single event, we can estimate a characteristic recurrence interval between 630 and 1400 yr.
    Description: Published
    Description: 622-628
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Image processing; Satellite geodesy; Seismic cycle; Radar interferometry; Seismicity and tectonics; Continental tectonics: strike-slip and transform. ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 16
    Publication Date: 2017-04-04
    Description: In this study, we revisit the mechanism of the 1976 Friuli (NE Italy) earthquake sequence (main shocks M w 6.4, 5.9 and 6.0). We present a new source model that simultaneously fits all the available geodetic measurements of the observed deformation. We integrate triangulation measurements, which have never been previously used in the source modelling of this sequence, with high-precision levelling that covers the epicentral area. We adopt a mixed linear/non-linear optimization scheme, in which we iteratively search for the best-fitting solution by performing several linear slip inversions while varying fault location using a grid search method. Our preferred solution consists of a shallow north-dipping fault plane with assumed azimuth of 282◦ and accommodating a reverse dextral slip of about 1 m. The estimated geodetic moment is 6.6 × 1018 Nm (M w 6.5), in agreement with seismological estimates. Yet, our preferred model shows that the geodetic solution is consistent with the activation of a single fault system during the entire sequence, the surface expression of which could be associated with the Buia blind thrust, supporting the hypothesis that the main activity of the Eastern Alps occurs close to the relief margin, as observed in other mountain belts. The retrieved slip pattern consists of a main coseismic patch located 3–5 km depth, in good agreement with the distribution of the main shocks. Additional slip is required in the shallower portions of the fault to reproduce the local uplift observed in the region characterized by Quaternary active folding. We tentatively interpret this patch as postseismic deformation (afterslip) occurring at the edge of the main coseismic patch. Finally, our rupture plane spatially correlates with the area of the locked fault determined from interseismic measurements, supporting the hypothesis that interseismic slip on the creeping dislocation causes strain to accumulate on the shallow (above ∼10 km depth) locked section. Assuming that all the long-term accommodation between Adria and Eurasia is seismically released, a time span of 500–700 years of strain-accumulating plate motion would result in a 1976-like earthquake.
    Description: Published
    Description: 1279-1294
    Description: 3.1. Fisica dei terremoti
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: seismic cycle; earthquake source observations ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
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  • 17
    Publication Date: 2017-04-04
    Description: The peculiar source characteristics of long-period seismic events (time persistency of the source, low-frequency peaks in the source spectrum, absence of high-frequency radiation) prevent the formation of a definite high-frequency coda in the seismograms. In contrast, this is well formed in volcano–tectonic quakes. For this reason, the widely used duration magnitude scale that is based on the proportionality between the energy and the coda duration cannot be used for long-period estimation. In observatory practice, the long-period magnitude is sometimes estimated using the same duration magnitude scale, leading to confusing results. In this report, we show a new method to estimate the magnitude of long-period events that generally occur for volcanoes, with some application examples from data for Mt Etna (Italy), Colima Volcano (Mexico) and Campi Flegrei (Italy).
    Description: Published
    Description: 911-919
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source observations; ; Volcano monitoring ; Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 18
    Publication Date: 2017-04-04
    Description: Repeating volcano-tectonic (VT) earthquakes, taking place at Mt. Etna during 1999–2009,were detected and analyzed to investigate their behavior. We found 735 families amounting to 2479 VT earthquakes, representing ~38% of all the analyzed VT earthquakes. The number of VT earthquakes making up the families ranges from 2 to 23. Over 70% of the families comprise 2 or 3 VT earthquakes and only 20 families by more than 10 events. The occurrence lifetime is also highly variable ranging from some minutes to ten years. In particular, more than half of the families have a lifetime shorter than 0.5 day and only ~10% longer than 1 year. On the basis of these results, most of the detected families were considered “burst-type”, i.e., show swarm-like occurrence, and hence their origin cannot be explained by a temporally constant tectonic loading. Indeed, since the analyzed earthquakes take place in a volcanic area, the rocks are affected not only by tectonic stresses related to the fairly steady regional stress field but also by local stresses, caused by the volcano, such as magma batch intrusions/ movements and gravitational loading.We focused on the five groups of families characterized by the longest repeatability over time, namely high number of events and long lifetime, located in the north-eastern, eastern and southern flanks of the volcano. Unlike the first four groups, which similarly to most of the detected families show swarm-like VT occurrences, group “v”, located in the north-eastern sector, exhibits a more “tectonic” behavior with the events making up such a group spread over almost the entire analyzed period. It is clear how both occurrence and slip rates do not remain constant but vary over time, and such changes are time-related to the occurrence of the 2002–2003 eruption. Finally, by FPFIT algorithm a good agreement between directions identified by nodal planes and the earthquake epicentral distribution was generally found.
    Description: Published
    Description: 1223 – 1236
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: repeating earthquakes ; Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-04
    Description: The coda normalization method is one of the most used methods in the inference of attenuation parameters Qα and Qβ . Since, in this method, the geometrical spreading exponent γ is an unknown model parameter, the most part of studies assumes a fixed γ , generally equal to 1. However γ and Q could be also jointly inferred from the non-linear inversion of codanormalized logarithms of amplitudes, but the trade-off between γ and Q could give rise to unreasonable values of these parameters. To minimize the trade-off between γ and Q, an inversion method based on a parabolic expression of the coda-normalization equation has been developed. The method has been applied to the waveforms recorded during the 1997 Umbria-Marche seismic crisis. The Akaike criterion has been used to compare results of the parabolic model with those of the linear model, corresponding to γ = 1. A small deviation from the spherical geometrical spreading has been inferred, but this is accompanied by a significant variation of Qα and Qβ values. For almost all the considered stations, Qα smaller than Qβ has been inferred, confirming that seismic attenuation, in the Umbria-Marche region, is controlled by crustal pore fluids.
    Description: Published
    Description: 1726-1731
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; coda normalization method ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 20
    Publication Date: 2017-04-04
    Description: For decades, many authors have attempted to define the location, geometry and kinematics of the causative fault for the 1908 December 28, M 7.1 earthquake that struck the Messina Straits between Sicily and Calabria (southern Italy). The coseismic displacement caused a predominant downwarping of the Straits and small land uplift away from it, which were documented by levelling surveys performed 1 yr before and immediately after the earthquake. Most of the source models based on inversion of levelling data suggested that the earthquake was caused by a low angle, east-dipping blind normal fault, whose upper projection intersects the Earth surface on the Sicilian (west) side of the Messina Straits.An alternative interpretation holds that the causative fault is one of the high-angle, west-dipping faults located in southern Calabria, on the eastern side of the Straits, and may in large part coincide with the mapped Armo Fault. Here, we critically review the levelling data with the aim of defining both their usefulness and limits in modelling the seismogenic fault. We demonstrate that the levelling data alone are not capable of discriminating between the two oppositely dipping fault models, and thus their role as a keystone for modellers is untenable. However, new morphotectonic and geodetic data indicate that the Armo Fault has very recent activity and is accumulating strain. The surface observations, together with appraisal ofmacroseismic intensity distribution, available seismic tomography and marine geophysical evidence, lends credit to the hypothesis that the Armo and possibly the S. Eufemia faults are part of a major crustal structure that slipped during the 1908 earthquake.
    Description: Published
    Description: 1025-1041
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source ; Messina Straits ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
    Publication Date: 2017-04-04
    Description: With the goal of constructing a homogeneous data set of moment magnitudes (Mw) to be used for seismic hazard assessment, we compared Mw estimates from moment tensor catalogues available online. We found an apparent scaling disagreement between Mw estimates from the National Earthquake Information Center (NEIC) of the US Geological Survey and from the Global Centroid Moment Tensor (GCMT) project. We suspect that this is the effect of an underestimation ofMw 〉 7.0 (M0 〉 4.0 × 1019 Nm) computed by NEIC owing to the limitations of their computational approach. We also found an apparent scaling disagreement between GCMT and two regional moment tensor catalogues provided by the ‘Eidgen¨ossische Technische Hochschule Z¨urich’ (ETHZ) and by the European–Mediterranean Regional Centroid Moment Tensor (RCMT) project of the Italian ‘Istituto Nazionale di Geofisica e Vulcanologia’ (INGV). This is probably the effect of the overestimation of Mw 〈 5.5 (M0 〈 2.2 × 1017 Nm), up to year 2002, and of Mw 〈 5.0 (M0 〈 4.0 × 1016 Nm), since year 2003, owing to the physical limitations of the standard CMT inversion method used by GCMT for the earthquakes of relatively low magnitude. If the discrepant data are excluded from the comparisons, the scaling disagreements become insignificant in all cases. We observed instead small absolute offsets (≤0.1 units) for NEIC and ETHZ catalogues with respect to GCMT whereas there is an almost perfect correspondence between RCMT and GCMT. Finally, we found a clear underestimation of about 0.2 units of Mw magnitudes computed at the INGV using the time-domain moment tensor (TDMT) method with respect to those reported by GCMT and RCMT. According to our results, we suggest appropriate offset corrections to be applied to Mw estimates from NEIC, ETHZ and TDMT catalogues before merging their data with GCMT and RCMT catalogues. We suggest as well to discard the probably discrepant data from NEIC and GCMT if other Mw estimates from different sources are available for the same earthquakes. We also estimate approximately the average uncertainty of individual Mw estimates to be about 0.07 magnitude units for the GCMT, NEIC, RCMT and ETHZ catalogues and about 0.13 for the TDMT catalogue.
    Description: European Union research project SHARE (Seismic Hazard Harmonization in Europe), within the ambit of Task 3.1 ‘European Earthquake Database’
    Description: Published
    Description: 1733-1745
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source observations; Statistical seismology ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 22
    Publication Date: 2017-04-04
    Description: The complex volcanic system of Tenerife Island is known to have a highly heterogeneous character, as recently confirmed by velocity tomography.We present new information derived from intrinsic quality factor inverse maps (Qi −1), scattering quality factor inverse maps (Qs −1) and total quality factor inverse maps (Qt −1) obtained for the same region. The data set used in this work is the result of the analysis of an active seismic experiment carried out, using offshore shots (air guns) recorded at over 85 onshore seismic stations. The estimates of the attenuation parameters are based on the assumption that the seismogram energy envelopes are determined by seismic energy diffusion processes occurring inside the island. Diffusion model parameters, proportional to Qi −1 and to Qs −1, are estimated from the inversion of the energy envelopes for any source–receiver couple. They are then weighted with a new graphical approach based on a Gaussian space probability function, which allowed us to create ‘2-D probabilistic maps’ representing the space distribution of the attenuation parameters. The 2-D images obtained reveal the existence of a zone in the centre of the island characterized by the lowest attenuation effects. This effect is interpreted as highly rigid and cooled rocks. This low-attenuation region is bordered by zones of high attenuation, associated with the recent historical volcanic activity. We calculate the transport mean free path obtaining a value of around 4 km for the frequency range 6–12 Hz. This result is two orders of magnitude smaller than values calculated for the crust of the Earth. An absorption length between 10 and 14 km is associated with the average intrinsic attenuation parameter. These values, while small in the context of tectonic regions, are greater than those obtained in volcanic regions such as Vesuvius or Merapi. Such differences may be explained by the magnitude of the region of study, over three times larger than the aforementioned study areas. This also implies deeper sampling of the crust, which is evidenced by a change in the values of seismic attenuation. One important observation is that scattering attenuation dominates over the intrinsic effects, Qi being at least twice the value of Qs.
    Description: This work has been partially supported by the Spanish project Ephestos, CGL2011-29499-C02-01, by the EU project EC-FP7 MEDiterranean SUpersite Volcanoes (MED-SUV), by the Basque Government researcher training program BFI09.277 and by the Regional project ‘Grupo de Investigaci´on en Geof´ısica y Sismolog´ıa de la Junta de Andaluc´ıa, RNM104’. EdP has been partly supported by DPC-INGV projects UNREST SPEED and V2 (Precursori).
    Description: Published
    Description: 1942-1956
    Description: 3.1. Fisica dei terremoti
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; ; Seismic tomography; ; Volcano seismology ; Wave propagation. ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
    Publication Date: 2017-04-04
    Description: The central United States is a region for which observational studies have indicated an increase in heavy rainfall. This study uses projections of daily rainfall from 20 state-of-the-art global climate models and one scenario (RCP 8.5) to examine projected changes in extreme rainfall. Analyses are performed focusing on trends in the 90th and 99th percentiles of the daily rainfall distributions for two periods (2006-2045 and 2046-2085). The results of this study indicate a large increase in extreme rainfall in particular over the northern part of the study region, with a much less clear signal over the Great Plains and the states along the Gulf of Mexico.
    Description: Published
    Description: 200-205
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: embargoed_20160624
    Keywords: precipitation ; extreme events ; cmip5 ; climate change ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 24
    Publication Date: 2017-04-04
    Description: The Geochemical Monitoring System II (GMSII)prototype was designed, assembled, tested and installed at the Acqua Difesa test site, near Belpasso (Catania).
    Description: Published
    Description: 273-306
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: restricted
    Keywords: Geochemical Monitoring System ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects
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  • 25
    Publication Date: 2017-04-04
    Description: The study of the health of a building connects humanistic and scientific research, and a complete characterization can be achieved by integrating all the available historical documentation, architectural and metrological studies, as well as laboratory and in situ analyses of the materials. A contactless, non-invasive surveying technique such as terrestrial laser scanning (TLS) allows the acquisition of dense and accurate geometric and radiometric (electromagnetic measurements such as signal intensity) information about the observed surface of the building, which can be easily integrated with data provided by high-resolution digital imaging. The early Christian Cantalovo church was surveyed for the first time in April 2011, by means of the ILRIS-3D ER very long range scanner. The second and last survey was performed in June 2012, after the main shocks of the Emilia earthquake seismic sequence. A very long range instrument is suitable for fast, simple and independent measurements, due to its technical characteristics and, for this reason, is easily usable for accurate surveying in emergency conditions. The main results are obtained by applying a data analysis strategy based on the creation of TLS-based morphological maps computed as point-to-primitive differences, which allow the creation of a deformation map and its evolution in time.
    Description: Published
    Description: 703-716
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: JCR Journal
    Description: restricted
    Keywords: Terrestrial Laser Scanning ; Deformation ; Earthquake ; Ancient Building ; Procedure Standardization ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring
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  • 26
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    Elsevier
    In:  EPIC3Encyclopedia of Quaternary Science. 2nd edition, Amsterdam, Elsevier, 11 p., pp. 542-552, ISBN: 978-0-444-53643-3
    Publication Date: 2020-09-25
    Description: Syngenetically frozen deposits that are fine-grained and ice-rich are widely distributed in lowlands of northeastern Siberia, Alaska and northwestern Canada. These late Pleistocene sediments are specific to this region summarized as Beringia, and have been termed 'Ice Complex' or 'Yedoma' in Siberia, and 'muck' in North America. Silt is their dominant material, but they also include abundant organic matter preserved in permafrost since the time of deposition. Vegetation and faunal reconstructions indicate that the sediments aggraded largely under a cryoxeric environment characterized by graminoid and forb-rich vegetation that supported a grazing megafauna population during the Pleistocene.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 27
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    Wiley-Blackwell
    In:  EPIC3Methods for the study of marine benthos, Methods for the study of marine benthos, West Sussex, Wiley-Blackwell, 78 p., pp. 329-407, ISBN: 978-0-470-67086-6
    Publication Date: 2014-04-15
    Description: Traditionally, the rationale for energy flow studies was found in the elucidation of energy transfers within ecosystems or within the practical context of the rational management of resources, but it is now widely recognised that its scope embodies almost all biology, including the field of population dynamics and evolutionary studies. Here, we first describe conceptual models of energy and mass budgets at the level of the individual, the population and the community. However, the emphasis is on the next part in which the practicalities of measuring the various components of these budgets in the marine zoobenthic community are described in detail. The measurement of, among other things, ingestion, absorption, defaecation, excretion, growth, reproduction and respiration is discussed. Finally, attention is paid to the estimation of secondary production of benthic populations and to community-level modelling methods.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 28
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    Elsevier
    In:  EPIC3Comparative Biochemistry and Physiology Part D: Genomics and Proteomics, Elsevier, 8(4), pp. 344 - 351, ISSN: 1744-117X
    Publication Date: 2016-08-17
    Description: Abstract Research investigating the genetic basis of physiological responses has significantly broadened our understanding of the mechanisms underlying organismic response to environmental change. However, genomic data are currently available for few taxa only, thus excluding physiological model species from this approach. In this study we report the transcriptome of the model organism Hyas araneus from Spitsbergen (Arctic). We generated 20,479 transcripts, using the 454 {GS} {FLX} sequencing technology in combination with an Illumina HiSeq sequencing approach. Annotation by Blastx revealed 7159 blast hits in the {NCBI} non-redundant protein database. The comparison between the spider crab H. araneus transcriptome and {EST} libraries of the European lobster Homarus americanus and the porcelain crab Petrolisthes cinctipes yielded 3229/2581 sequences with a significant hit, respectively. The clustering by the Markov Clustering Algorithm (MCL) revealed a common core of 1710 clusters present in all three species and 5903 unique clusters for H. araneus. The combined sequencing approaches generated transcripts that will greatly expand the limited genomic data available for crustaceans. We introduce the {MCL} clustering for transcriptome comparisons as a simple approach to estimate similarities between transcriptomic libraries of different size and quality and to analyze homologies within the selected group of species. In particular, we identified a large variety of reverse transcriptase (RT) sequences not only in the H. araneus transcriptome and other decapod crustaceans, but also sea urchin, supporting the hypothesis of a heritable, anti-viral immunity and the proposed viral fragment integration by host-derived {RTs} in marine invertebrates.
    Repository Name: EPIC Alfred Wegener Institut
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  • 29
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    Elsevier
    In:  EPIC3Progress in Oceanography, Elsevier, 112-11, pp. 38-48
    Publication Date: 2019-07-16
    Description: Coastal upwelling ecosystems are areas of high productivity and strong outgassing, where most gases, such as N2O and CH4, are produced in subsurface waters by anaerobic metabolisms. We describe seasonal CH4 variation as well as potential mechanisms producing CH4 in surface waters of the central Chile upwelling ecosystem (36°S). Surface waters were always supersaturated in CH4 (from 125% up to 550%), showing a clear seasonal signal triggered by wind driven upwelling processes (austral spring– summer period), that matched with the periods of high chlorophyll-a and dimethylsulfoniopropionate (DMSP) levels. Methane cycling experiments, with/without the addition of dimethylsulfide (including 13C-DMS) and acetylene (a nonspecific inhibitor of CH4 oxidation) along with monthly measurements of CH4, DMSP and other oceanographic variables revealed that DMS can be a CH4 precursor. Net CH4 cycling rates (control) fluctuated between -0.64 and 1.44 nmol L-1 d-1. After the addition of acetylene, CH4 cycling rates almost duplicated relative to the control, suggesting a strong methanotrophic activity. With a spike of DMS, the net CH4 cycling rate significantly increased relative to the acetylene and control treatment. Additionally, the d13C values of CH4 at the end of the incubations (after addition of 13C enriched-DMS) were changed, reaching -32‰ PDB compared to natural values between -44‰ and -46‰ PDB. These findings indicate that, in spite of the strong CH4 consumption by methanotrophs, this upwelling area is an important source of CH4 to the atmosphere. The effluxes are derived partially from in situ surface production and seem to be related to DMSP/DMS metabolism.
    Repository Name: EPIC Alfred Wegener Institut
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  • 30
    Publication Date: 2018-08-10
    Description: Abstract Radiocarbon and uranium-thorium dating results are presented from a genus of calcitic Antarctic cold-water octocorals (family Coralliidae), which were collected from the Marie Byrd Seamounts in the Amundsen Sea (Pacific sector of the Southern Ocean) and which to date have not been investigated geochemically. The geochronological results are set in context with solution and laser ablation-based element/Ca ratios (Li, B, Mg, Mn, Sr, Ba, U, Th). Octocoral radiocarbon ages on living corals are in excellent agreement with modern ambient deep-water �14C, while multiple samples of individual fossil coral specimens yielded reproducible radiocarbon ages. Provided that local radiocarbon reservoir ages can be derived for a given time, fossil Amundsen Sea octocorals should be reliably dateable by means of radiocarbon. In contrast to the encouraging radiocarbon findings, the uranium-series data are more difficult to interpret. The uranium concentration of these calcitic octocorals is an order of magnitude lower than in the aragonitic hexacorals that are conventionally used for geochronological investigations. While modern and Late Holocene octocorals yield initial δ234U in good agreement with modern seawater, our results reveal preferential inward diffusion of dissolved alpha-recoiled 234U and its impact on fossil coral δ234U. Besides alpha-recoil related 234U diffusion, high-resolution sampling of two fossil octocorals further demonstrates that diagenetic uranium mobility has offset apparent coral U-series ages. Combined with the preferential alpha-recoil 234U diffusion, this process has prevented fossil octocorals from preserving a closed system U-series calendar age for longer than a few thousand years. Moreover, several corals investigated contain significant initial thorium, which cannot be adequately corrected for because of an apparently variable initial 232Th/230Th. Our results demonstrate that calcitic cold-water corals are unsuitable for reliable U-series dating. Mg/Ca ratios within single octocoral specimens are internally strikingly homogeneous, and appear promising in terms of their response to ambient temperature. Magnesium/lithium ratios are significantly higher than usually observed in other deep marine calcifiers and for many of our studied corals are remarkably close to seawater compositions. Although this family of octocorals is unsuitable for glacial deep-water �14C reconstructions, our findings highlight some important differences between hexacoral (aragonitic) and octocoral (calcitic) biomineralisation. Calcitic octocorals could still be useful for trace element and some isotopic studies, such as reconstruction of ambient deep water neodymium isotope composition or pH, via boron isotopic measurements.
    Repository Name: EPIC Alfred Wegener Institut
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  • 31
    Publication Date: 2018-08-10
    Description: The AND-1B drill core (1285 m-long) was recovered, inside the ANDRILL (ANtarctic geological DRILLing) Program, during the austral summer of 2006/07 from beneath the floating McMurdo Ice Shelf. Drilling recovered a stratigraphic succession of alternating diamictites, diatomites and volcaniclastic sediments spanning about the last 14 Ma. A core portion between 350 and 480 mbsf, including a 80 m-thick diatomite interval recording the early Pliocene warming event, was investigated in term of opal biogenic content and element geochemistry. Across the diatomite interval, in spite of the lithological uniformity, a fluctuating biogenic opal profile mirrors the δ18O record, testifying a decrease in productivity when temperature drops as a consequence of small glacial fluctuations. The comparison of biogenic opal data with Chaetoceros spp. abundances from Konfirst et al. (2012) documents alternations between periods of high primary productivity in stratified surface waters and of enhanced terrigenous input in ice-free conditions. Cluster analysis discriminates elements associated to terrigenous input from those subject to biogenic control. Further separation in sub-cluster was interpreted in term of different element response to changes in provenance but also to depositional/early diagenetic conditions at the seafloor. Whilst K and Ti are related to different sediment sources confirming previous studies from the same interval, V, Zn and, to a lesser extent, Fe, document reducing/anoxic conditions during the diatomites deposition (in particular in 400–460 mbsf interval). Mg, Sr and Mn contents are related to authigenic carbonate precipitation whilst Ba is interested by nonsteady-state processes leading to local peaks of barium below the sulphate-rich/sulphate-poor pore water boundary where generally the low degree of barite saturation is responsible for Ba remobilization. Such alteration in depositional dynamics, responsible of the precipitation of an oxygen-depleted barium phase, was probably induced by change in sedimentation rate and/or in palaeoenvironmental conditions.
    Repository Name: EPIC Alfred Wegener Institut
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  • 32
    Publication Date: 2019-07-17
    Description: In recent years, a novel proxy for the past occurrence of Arctic sea ice has been proposed that is based on the variable marine sedimentary abundance of an organic geochemical lipid derived from sea ice diatoms in the spring. This lipid, termed IP25 (Ice Proxy with 25 carbon atoms), is a highly branched isoprenoid mono-unsaturated alkene that appears to be sufficiently stable in sediments to permit meaningful palaeo sea ice reconstructions to be carried out over short- to long-term timescales. Since the first proposed use of IP25 as a proxy for palaeo sea ice by Belt et al. (2007), a number of laboratories have measured this biomarker in Arctic sediments and it is anticipated that research activity in this area will increase further in the future. The content of this review is divided into a number of sections. Firstly, we describe the scientific basis for the IP25 proxy and its initial discovery in Arctic sea ice, sedimenting particles and sediments. Secondly, we summarise the relatively few studies that have, to date, concentrated on examining the factors that influence the production and fate of IP25 and we identify some areas of future research that need to be addressed in order to improve our understanding of IP25 data obtained from sedimentary analyses. What is clear at this stage, however, it that the presence of IP25 in Arctic marine sediments appears to represent a proxy measure of past seasonal sea ice rather than permanent or multi-year ice conditions. Thirdly, we highlight the importance of rigorous analytical identification and quantification of IP25, especially if measurements of this biomarker are going to be used for quantitative sea ice reconstructions, rather than qualitative analyses alone (presence/absence). Fourthly, we review some recent attempts to make the interpretations of IP25 biomarker data more detailed and quantitative by combining sedimentary abundances with those of phytoplankton- and other sea ice-derived biomarkers. Thus, the bases for the so-called PIP25 and DIP25 indices are described, together with an overview of potential limitations, concluding that investigations into the use of these indices needs further research before their full potential can be realised. In the final section, we provide a summary of IP25-based palaeo sea ice reconstruction case studies performed to date. These case studies cover different Arctic regions and timescales spanning decades to tens of thousands of years.
    Repository Name: EPIC Alfred Wegener Institut
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  • 33
    Publication Date: 2019-07-17
    Description: Cratons with their thick lithospheric roots can influence the thermal structure, and thus the convective flow, in the surrounding mantle. As mantle temperatures are hard to measure directly, depth variations in the mantle transition zone (MTZ) discontinuities are often employed as a proxy. Here, we use a large new data set of P-receiver functions to map the 410 km and 660 km discontinuities beneath the western edge of the East European Craton and adjacent Phanerozoic Europe across the most fundamental lithospheric boundary in Europe, the Trans-European Suture Zone (TESZ). We observe significantly shorter travel times for conversions from both MTZ discontinuities within the craton, caused by the high velocities of the cratonic root. By contrast, the differential travel time across the MTZ is normal to only slightly raised. This implies that any insulating effect of the cratonic keel does not reach the MTZ. In contrast to earlier observations in Siberia, we do not find any trace of a discontinuity at 520 km depth, which indicates a rather dry MTZ beneath the western edge of the craton. Within most of covered Phanerozoic Europe, the MTZ differential travel time is remarkably uniform and in agreement with standard Earth models. No widespread thermal effects of the various episodes of Caledonian and Variscan subduction that took place during the amalgamation of the continent remain. Only more recent tectonic events, related to Alpine subduction and Quarternary volcanism in the Eifel area, can be traced. While the East European craton shows no distinct imprint into the MTZ, we discover the signature of the TESZ in the MTZ in the form of a linear region of about 350 km width with a 1.5 s increase in differential travel time, which could either be caused by high water content or decreased temperature. Taking into account results of recent S-wave tomographies, raised water content in the MTZ cannot be the main cause for this observation. Accordingly, we explain the increase, equivalent to a 15 km thicker MTZ, by a temperature decrease of about 80 K. We discuss two alternative models for this temperature reduction, either a remnant of subduction or an indication of downwelling due to small-scale, edge-driven convection caused by the contrast in lithospheric thickness across the TESZ. Any subducted lithosphere found in the MTZ at this location is unlikely to be related to Variscan subduction along the TESZ, though, as Eurasia has moved significantly northward since the Variscan orogeny.
    Repository Name: EPIC Alfred Wegener Institut
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  • 34
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
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  • 35
    Publication Date: 2018-02-15
    Repository Name: EPIC Alfred Wegener Institut
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  • 36
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    Elsevier
    In:  EPIC3The Encyclopedia of Quaternary Science, The Encyclopedia of Quaternary Science, Amsterdam, Elsevier, pp. 755-764
    Publication Date: 2014-04-15
    Repository Name: EPIC Alfred Wegener Institut
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  • 37
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    Unknown
    Elsevier
    In:  EPIC3The Encyclopedia of Quaternary Science, The Encyclopedia of Quaternary Science, Elsevier, pp. 73-85
    Publication Date: 2014-04-15
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 38
    facet.materialart.
    Unknown
    Elsevier
    In:  EPIC3Deep Sea Research Part I: Oceanographic Research Papers, Elsevier, 76, pp. 66-84, ISSN: 09670637
    Publication Date: 2019-07-17
    Description: We use a 27 year long time series of repeated transient tracer observations to investigate the evolution of the ventilation timescales and the related content of anthropogenic carbon(Cant) in deep and bottom water in the Weddell Sea. This time series consists of chlorofluorocarbon (CFC) observations from 1984 to 2008 together with first combined CFC and sulphurhexafluoride (SF6) measurements from 2010/2011 along the Prime Meridian in the Antarctic Ocean and across the Weddell Sea. Applying the Transit Time Distribution (TTD) method we find that all deep water masses in the Weddell Sea have been continually growing older and getting less ventilated during the last 27years. The decline of the ventilation rate of Weddell Sea Bottom Water (WSBW) and Weddell Sea Deep Water (WSDW) along the Prime Meridian is in the order of 15–21%; the Warm Deep Water (WDW) ventilation rate declined much faster by 33%. About 88–94% of the age increase in WSBW near its source regions (1.8–2.4 years per year) is explained by the age increase of WDW (4.5 years per year). As a consequence of the aging, the Cant increase in the deep and bottom water formed in the Weddell Sea slowed down by 14–21% over the period of observations.
    Repository Name: EPIC Alfred Wegener Institut
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  • 39
    Publication Date: 2014-04-17
    Description: A high input of lithogenic sediment from glaciers was assumed to be responsible for high Fe and Mn contents in the Antarctic soft shell clam Laternula elliptica at King George Island. Indeed, withdrawal experiments indicated a strong influence of environmental Fe concentrations on Fe contents in bivalve hemolymph, but no significant differences in hemolymph and tissue concentrations were found among two sites of high and lower input of lithogenic debris. Comparing Fe and Mn concentrations of porewater, bottom water, and hemolymph from sampling sites, Mn appears to be assimilated as dissolved species, whereas Fe apparently precipitates as ferrihydrite within the oxic sediment or bottom water layer prior to assimilation by the bivalve. Hence, we attribute the high variability of Fe and Mn accumulation in tissues of L. elliptica around Antarctica to differences in the geochemical environment of the sediment and the resulting Fe and Mn flux across the benthic boundary.
    Repository Name: EPIC Alfred Wegener Institut
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  • 40
    Publication Date: 2019-07-17
    Description: Coral recruitment was assessed in highly diverse and economically important Spermonde Archipelago, a reef system subjected to land-based sources of siltation/pollution and destructive fishing, over a period of 2 years. Recruitment on settlement tiles reached up to 705 spat m�2 yr�1 and was strongest in the dry season (July–October), except off-shore, where larvae settled earlier. Pocilloporidae dominated nearshore, while a more diverse community of Acroporidae, Poritidae and others settled in the less polluted mid-shelf and off-shore reefs. Non-coral fouling community appeared to hardly influence initial coral settlement on the tiles, although, this does not necessarily infer low coral post-settlement mortality, which may be enhanced at the near- and off-shore reefs as indicated by increased abundances of potential space competitors on natural substrate. Blast fishing showed no local reduction in coral recruitment and live hard coral cover increased in oligotrophic reefs, indicating potential for coral recovery, if managed effectively.
    Repository Name: EPIC Alfred Wegener Institut
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  • 41
    facet.materialart.
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    American Physical Society
    In:  EPIC3Physical Review E, American Physical Society, 88(6), ISSN: 1539-3755
    Publication Date: 2018-02-16
    Description: In this study we model population dynamics in a three-species food web with heterogeneous resources and intraguild predation by using a nonspatial Lotka-Volterra system with a density-dependent interaction of resource items. The model consists of two predators with an intraguild predation (IGP) relation competing for a common resource. The resource is subdivided into subpopulations of different quality that are distinguished by grazing rates of the two predators, contact rates between subpopulations and mortality rates. The proposed system describes an exchange of traits between species from distinct subpopulations by using a species interaction term. In particular, we examine the percentage of stable coexistence solutions versus resource carrying capacity and contact rates between distinct resource pools. We also present a numerical comparison of the percentage of stable food webs found for different numbers of subpopulations. While at high enrichment no stable coexistence was found in the IGP system with a single resource, our model predicts a stable coexistence of two IGP-related predators and resources at high and intermediate enrichment already at a low contact rate between subpopulations.
    Repository Name: EPIC Alfred Wegener Institut
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  • 42
    Publication Date: 2022-05-25
    Description: © The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Geochimica et Cosmochimica Acta 123 (2013): 322–337, doi:10.1016/j.gca.2013.06.011.
    Description: Despite the importance of diatoms in regulating climate and the existence of large opal-containing sediments in key air-ocean exchange areas, most geochemical proxy records are based on carbonates. Among them, Boron (B) content and isotopic composition have been widely used to reconstruct pH from foraminifera and coral fossils. We assessed the possibility of a pH/CO2 seawater concentration control on B content in diatom opal to determine whether or not frustule B concentrations could be used as a pH proxy or to clarify algae physiological responses to acidifying pH. We cultured two well-studied diatom species, Thalassiosira pseudonana and Thalassiosira weissflogii at varying pH conditions and determined Si and C quotas. Frustule B content was measured by both laser-ablation inductively coupled mass spectrometry (LA-ICPMS) and secondary ion mass spectrometry (SIMS/ion probe). For both species, frustules grown at higher pH have higher B contents and higher Si requirements per fixed C. If this trend is representative of diatom silicification in a future more acidic ocean, it could contribute to changes in the efficiency of diatom ballasting and C export, as well as changes in the contribution of diatoms relative to other phytoplankton groups in Si-limited regions. If B enters the cell through the same transporter employed for HCO3− uptake, an increased HCO3− requirement with decreasing CO2 concentrations (higher pH), and higher B(OH)4/HCO3− ratios would explain the observed increase in frustule B content with increasing pH. The mechanism of B transport from the site of uptake to the site of silica deposition is unknown, but may occur via silicon transport vesicles, in which B(OH)4− may be imported for B detoxification and/or as part of a pH regulation strategy either though Na-dependent B(OH)4−/Cl− antiport or B(OH)4−/H+ antiport. B deposition in the silica matrix may occur via substitution of a B(OH)4− for a negatively charged SiO− formed during silicification. With the current analytical precision, B content of frustules is unlikely to resolve ocean pH with a precision of paleoceanographic interest. However, if frustule B content was controlled mainly by HCO3− uptake for photosynthesis, which appears to show a threshold behavior, then measurements of B content might reveal the varying importance of active HCO3− acquisition mechanisms of diatoms in the past.
    Description: This work was funded by the European Community under the project ERC-STG-240222-PACE.
    Repository Name: Woods Hole Open Access Server
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  • 43
    Publication Date: 2015-01-22
    Description: Climatic hazards, such as severe droughts and floods, affect extensive areas across monsoon Asia and can have profound impacts on the populations of that region. The area surrounding Indonesia, including large portions of the eastern Indian Ocean and Java Sea, plays a key role in the global climate system because of the enormous heat and moisture exchange that occurs between the ocean and atmosphere there. Here, we evaluate the influence of rainfall variability on multiple tree-ring parameters of teak (Tectona grandis) trees growing in a lowland rain forest in Central Java (Indonesia). We assess the potential of, annually resolved, tree-ring width, stable carbon (δ13C) and oxygen (δ18O) isotope records to improve our understanding of the Asian monsoon variability. Climate response analysis with regional, monthly rainfall data reveals that all three tree-ring parameters are significantly correlated to rainfall, albeit during different monsoon seasons. Precipitation in the beginning of the rainy season (Sep–Nov) is important for tree-ring width, confirming previous studies. Compared to ring width, the stable isotope records possess a higher degree of common signal, especially during portions of the peak rainy season (δ13C: Dec–May; δ18O: Nov–Feb) and are negatively correlated to rainfall. In addition, tree-ring δ18O also responds positively to peak dry season rainfall, although the δ18O rainy season signal is stronger and more time-stable. The correlations of opposite sign reflect the distinct seasonal contrast of the δ18O signatures in rainfall (18OPre) during the dry (18O-enriched rain) and rainy (18O-depleted rain) seasons. This difference in 18OPre signal reflects the combination of two signals in the annual tree-ring δ18O record. Highly resolved intra-annual δ18O isotope analyses suggest that the signals of dry and rainy season can be distinguished clearly. Thereby reconstructions can improve our understanding of variations and trends of the hydrological cycle over the Indonesian archipelago.
    Repository Name: EPIC Alfred Wegener Institut
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  • 44
    Publication Date: 2019-07-16
    Description: This study presents a reconstruction of the Late Holocene climate in Kamchatka based on chironomid remains from a 332 cm long composite sediment core recovered from Dvuyurtochnoe Lake (Two-Yurts Lake, TYL) in central Kamchatka. The oldest recovered sediments date to about 4500 cal years BP. Chironomid head capsules from TYL reflect a rich and diverse fauna. An unknown morphotype of Tanytarsini, Tanytarsus type klein, was found in the lake sediments. Our analysis reveals four chironomid assemblage zones reflecting four different climatic periods in the Late Holocene. Between 4500 and 4000 cal years BP, the chironomid composition indicates a high lake level, well-oxygenated lake water conditions and close to modern temperatures (w13 �C). From 4000 to 1000 cal years BP, two consecutive warm intervals were recorded, with the highest reconstructed temperature reaching 16.8 �C between 3700 and 2800 cal years BP. Cooling trend, started around 1100 cal years BP led to low temperatures during the last stage of the Holocene. Comparison with other regional studies has shown that termination of cooling at the beginning of late Holocene is relatively synchronous in central Kamchatka, South Kurile, Bering and Japanese Islands and take place around 3700 cal years BP. From ca 3700 cal years BP to the last millennium, a newly strengthened climate continentality accompanied by general warming trend with minor cool excursions led to apparent spatial heterogeneity of climatic patterns in the region. Some timing differences in climatic changes reconstructed from chironomid record of TYL sediments and late Holocene events reconstructed from other sites and other proxies might be linked to differences in local forcing mechanisms or caused by the different degree of dating precision, the different temporal resolution, and the different sensitive responses of climate proxies to the climate variations. Further high-resolution stratigraphic studies in this region are needed to understand the spatially complex pattern of climate change in Holocene in Kamchatka and the surrounding region. �
    Repository Name: EPIC Alfred Wegener Institut
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  • 45
    Publication Date: 2022-05-24
    Description: This article focuses on the Montello thrust system in the Eastern Southern Alps as a potential seismogenic source. This system is of particular interest because of its lack of historical seismicity. Nevertheless, the system is undergoing active deformation. We developed a finite-element model using visco-elasto-plastic rheology. The free parameters of the model (essentially, the locking status of the three thrusts included in the study), were constrained by matching the observed horizontal GPS and vertical levelling data. We show that the amount of interseismic fault locking, and thus the seismic potential, is not necessarily associated with the fastest-slipping faults. More specifically, the locked Bassano thrust has a greater seismic potential than the freely slipping Montello thrust. The findings suggest that faults with subtle evidence of Quaternary activity should be carefully considered when creating seismic hazard maps.
    Description: Published
    Description: 221-227
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: open
    Keywords: interseismic deformation ; Montello thrust ; Southern Alps ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
    Publication Date: 2022-05-24
    Description: The broad availability of geodetic measurements for the Mw 6.3 April 6th 2009 L’Aquila earthquake allowed an unprecedented description of the co- and post-seismic ground deformations, leading to the definition of the Paganica fault geometry and kinematics. Through DInSAR, we found, in a wide area of 20 kilometres on the Paganica hangingwall, a further displacement up to 7 cm, which might have occurred in the earthquake proximity. In this study, we explore the possibility of the co-, post- and pre-seismic alternative scenarios. Although our data are not sufficient to undoubtedly prove that this signal occurred before the main event, this seems to be the most likely hypothesis based on tectonics constraints and image acquisition times. The nature of this deformation remains unclear, but we speculate that deep fluids played a role. These results can drive ad hoc requirements for future space-based missions and design of the GPS network.
    Description: Published
    Description: 343–351
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: restricted
    Keywords: InSAR ; L'Aquila earthquake ; GPS ; Anomalous signature ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Nuclear Physics, Section B 373 (1992), S. 3-34 
    ISSN: 0550-3213
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
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  • 48
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Nuclear Physics, Section B 386 (1992), S. 471-492 
    ISSN: 0550-3213
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
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  • 49
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 294 (1992), S. 466-478 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
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  • 50
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 289 (1992), S. 199-210 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
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  • 51
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 274 (1992), S. 230-238 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
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  • 52
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 317 (1993), S. 474-484 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
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  • 53
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 139-150 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe makroporöser Glycidylmethacrylat-Ethylendimethacrylat-Copolymerer (GMA-co-EDMA) wurde durch Suspensionspolymerisation hergestellt; dabei wurden nach einer statistisch geplanten experimentellen Durchführung die Ethylendimethacrylatkonzentration und die Heizrate der Polymerisationstemperatur von 20 auf 70°C variiert. Die Porositätseigenschaften der hydrolysierten Copolymeren wurden mit Hilfe der Größenausschlußchromatographie unter Verwendung von Polystyrolstandards in Tetrahydrofuran charakterisiert. Das Porenvolumen, die spezifische Oberfläche und die Porengröße werden dabei durch die Konzentration des Vernetzungsmittels stärker beEinflußt als durch die Heizrate während der Polymerisation.
    Notes: A series of macroporous glycidyl methacrylate-ethylene dimethacrylate copolymers have been prepared by the suspension polymerization according to a statistical design of experimental approach in which concentration of ethylene dimethacrylate and time needed for raising the polymerization temperature from 20 to 70°C have been varied. The porous properties of hydrolyzed copolymers have been characterized by means of size exclusion chromatography using polystyrene standards in tetrahydrofuran. Pore volume, specific surface area, and pore size are affected by the crosslinking agent concentration rather than by the rate of temperature increase during the polymerization reaction.
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  • 54
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 171-190 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Copolymers of AN were prepared with variable molecular masses and with variable contents of methylacrylate (ASME) and sodiumallylsulfonate (NaAS), acrylamide (AA), itaconic acid (IS), polyethyleneglycol acrylate (600) (PEGA), vinylacetate (VA), 2-hydroxyethyl acrylate, (HEE) or sodium acrylamido-2-methylpropanesulfonate (NaAMPS), respectively, by using a mathematical model for the calculation of the polymerization conditions needed. Precipitation studies by light scattering showed the predominant influence of NaAS and NaAMPS on the precipitation properties. Acrylonitrile homopolymers show a hard precipitation behaviour. The originating particles have a density of between 0.2 and 0.4 g/cm3. An increasing content of NaAS or NaAMPS leads for example beginning from 0.8 wt.-% NaAS in the monomer composition to a soft precipitation behaviour and to highly swollen particles possessing a density of less than 1 · 10-2 g/cm3. The molar mass and the ASME-content show no significant influence. For the acrylonitrile/acrylamide system already 0.5 wt.-% allylsulfonate is sufficient to get a soft precipitation behaviour with formation of highly swollen particles. All samples with the other cocomponents and without NaAS- or NaAMPS-comonomer show a hard precipitation behaviour with little swollen particles.
    Notes: Copolymere des Acrylnitrils (AN) mit variabler Molmasse bzw. mit variablem Anteil von Acrylsäuremethylester (ASME) und Natriumallylsulfonat (NaAS), Acrylamid (AA), Itaconsäure (IS), Polyethylenglykolacrylat (600) (PEGA), Vinylacetat (VA), Acrylsäure-2-hydroxyethylester (HEE) oder Natrium-2-acrylamido-2-methylpropansulfonat (NaAMPS) wurden hergestellt, wobei die erforderlichen Polymerisations-bedingungen mit Hilfe eines mathematischen Polymerisationsmodells ermittelt wurden.Die Fällungsuntersuchungen mit der Methode der Lichtstreuung zeigten, daß NaAS und NaAMPS einen dominierenden Einfluß haben. Bei Acrylnitril-Homopolymeren tritt eine harte Fällung auf, und die entstehenden Partikel haben eine Dichte zwischen 0,2 und 0,4 g/cm3. Zunehmender NaAS-bzw. NaAMPS-Gehalt führt ab einem Gehalt von beispielsweise ca. 0,8 Gew.-% NaAS im Monomergemisch zu einer weichen Fällung, bei der hochgequollene Partikel mit einer Dichte in der Größenordnung von 〈 1.10-2 g/cm3 entstehen. Ein Einfluß der Molmassen und des ASME-Gehaltes Konnte nicht nachgewiesen werden. Beim Acrylnitril/Acrylamid-System genügen offensichtlich 0,5 Gew.-% Allylsulfonat im Monomeransatz, um eine stabile, weiche Fällung unter Bildung hochgequollener Strukturen zu gewährleisten. Alle Proben mit den übrigen hydrophilen Cokomponenten zeigen ohne NaAS bzw. NaAMPS-Comonomer ein hartes Fäungsverhalten mit wenig gequollenen Partikeln.
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  • 55
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 213-213 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 56
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 191-204 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Photovernetzung von Poly(p-hydroxystyrol) (PPHS) wird durch O2 beachtlich beschleunigt. Dies ergab sich aus der Bestimmung der Molmasse (mit Hilfe der Lichtstreumethode) und des Gelanteils nach kontinuierlicher Bestrahlung bei λinc = 254 nm. Aufgrund von Ergebnissen aus Blitzphotolyseversuchen wird der folgende Reaktionsmechanismus aufgestellt: Die Vernetzung sowohl in An-als auch Abwesenheit von O2 kommt im wesentlichen durch Kombination von Radikalen des Phenoxyltyps zustande. In Abwesenheit von O2 werden Phenoxylradikale ausschließlich durch Spaltung von O—H-Bindungen phenolischer Gruppen, die sich im angeregten Singulettzustand befinden, erzeugt. Triplett-angeregte phenolische Gruppen, die sich auch bilden, desaktivieren nicht durch Spaltung der O—H-Bindungen. Sie reagieren allerdings sehr effektiv, sofern vorhanden, mit O2. Bei dieser Reaktion entstehen HO·2- und zusätzliche Phenoxylradikale. Alle handelsüblichen und die meisten im Labor synthetisierten PPHS-Proben enthalten chemisch gebundene, chinoidartige Verunreinigungen. Durch Versuche mit niedermolekularen Modellverbindungen wurde nachgewiesen, daß triplett-angeregte chinoide Gruppen einerseits mit phenolischen Gruppen unter Bildung von Phenoxylradikalen reagieren und daß sie andererseits unreaktiv sind bezüglich der Abstraktion aliphatischer Wasserstoffatome. Die Bestrahlung von PPHS bei λinc = 254 nm bewirkt die Bildung chinoider Gruppen, die bei dieser Wellenlänge auch stark absorbieren. Die Lichtabsorption dieser Gruppen wird im Laufe der weiteren Bestrahlung zum bestimmenden Faktor hinsichtlich der photochemischen Veränderung des Polymeren.
    Notes: Light-induced crosslinking of poly(p-hydroxystyrene) (PPHS) is significantly enhanced by O2. This was evidenced by molar mass (light scattering measurements) and by gel content determinations which were performed on various polymer samples before and after continuous irradiation at λinc = 254 nm. The following mechanism was elucidated with the aid of flash photolysis studies: Crosslinking in the absence or presence of O2 is mainly due to the combination of phenoxyl type radicals. In the absence of O2 the latter are exclusively formed by O—H bond cleavage of singlet excited phenolic groups. Triplet excited phenolic groups which are also formed do not deactivate via O—H bond cleavage but react very effectively with O2. This reaction leads to the formation of HO2· and additional phenoxyl type radicals. All Commercial and most laboratory-prepared PPHS samples contain chemically bound impurities of quinoid nature. On the basis of results performed with model compounds of low molar mass, it is concluded that triplet excited quinoid groups react effectively with phenolic groups forming phenoxyl type radicals and that they are quite unreactive with respect to the abstraction of alphatic hydrogen atoms. Irradiation of PPHS at λinc = 254 nm causes the formation of quinoid groups which absorb strongly at this wavelength. Light absorption by these groups becomes a determining factor with respect to photochemical alteration in the course of further irradiation.
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  • 57
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 21-35 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die verschiedenartigen Eigenschaften von Polymerlegierungen aus Polyoxymethylen (POM) und bis zu 20 Gew.-% chemische oberf;ächenbehandeltem Poly(tetrafluorethylen) (CPTFE) wurden untersucht und denen unbahandelter POM/PTFE- Blends gegenübergestellt. PTFE iwrd POM zugesetzt, um dessen Oberflächenabriebseigenschaften Anteil zunehmend verschlechtert. Durch die bessere Phasenanbindung in den oberflächenbehandelten POM/CPTFE- Blends konnten die doppelten Zugfestigkeiten und EModuli wie bei unbehandelten POM/PTEF- Blends erreicht werden. Mit Hilfe der Elektronenmikroskopie (SEM) konnte gezeigt werden, daß die PTEF-Agglomerate in der POM-Matrix eine Größe von 30 bis 100 μm haben, während die CPTFE-Teilchengrößbe unter 1 μum liegt.
    Notes: The various properties of the blends of polyacetal (POM) with up to 20 wt.-% chemically surface-treated poly(tetrafluoroethylene) (CPTFE) were investigated and compared with those of POM/PTFE blends. The PTFE is added to POM to improve the wear properties, however, the mechanical properties of POM/PTFE blends decrease with increasing PTFE content, but tensile strength and Young's modulus of POM/CPTFE blends are more than 2 times higher than that of the POM/PTFE blends. SEM shows that the size of inherent agglomerative PTFE is in the range of 30 to 100 μm. The particle size of major CPTFE dispersed in POM is smaller than 1 μm.
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  • 58
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 49-61 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Hydrogele wurden aus methylmethacrylat (MMA) and N-Vinyl-2-pyrrolidon (NVP) mit 1,2,2-Trimethylolpropantrimethacrylat (TPTA) als Vernetzungsmittel hergestellt. Die Terplymerisation wurden mittels UV-strahlung (365 nm) initiiert, wobei kleine Mengen an Diethoxycetophenon (DEAP) als Photosensibilisator sowie Triethanolamin(TEA)als Beschleuniger und Verdünner verwendet wurden. Die Hydrogele wurden durch Messung des Wasserrückhaltevermögens, der Sauerstodiffusions- und permitionskoeffizienten, der mechanischen Eigenschaften und der Lichtdurchlässigkeit charakterisiert. Dabei zeigte sich, daß die Hydrogele bis zu 80 Gew.-% Wasser aufnehmen können, wobei mit steigendem Wassergtehalt deren mechanische Festigkeit drastisch sinkt. Der Ssuerstoffdiffusionskoeffizient der gequollenen Hydrogele beträgt 10-6 cm2s-1, der Sauerstoffpermeationskoeffizient 1013 cm2s-1Pa-1, und die Lichtdurchlässigkeit liegt im Bereich von 500 bis 700 nm bei über 90%.
    Notes: Hydrogels are synthesized from methyl methacrylate (MMA) and N-vinyl-2-pyrrolidone (NVP) with 1,1,1-trimethylol propane trimethacrylate (TPTA) as a crosslinking agent. It was polymerized under UV radiation (365nm) with a small amount of photosensitizer, diethoxy acetophenone (DEAP), acclerator and diluent, triethanol amine (TEA). The hydrogels were characterized by measuring the water retention, dissolved oxygen diffusivity and permeability, mechanical strength, and light transparency. The hydrogels can retain water up to 80 wt.-% and the mechanical strenght is weakened as the water content is increased in the gel. The dissolved oxygen diffusivity and permeability in the swelling hydrogels are determined to be 10-6 cm2/sec and 1013 cm2s-1 Pa-1, respectively. The light transparency is over 90% in the wave lenght ranging from 500 to 700 nm.
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  • 59
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Bisphenol-A-Epoxidharz wurde zunächst mit Toluylendiisocyanat, dessen eine Isocyanatgruppe mit 2-Ethylhexanol blockiert war, und dann mit unterschiedlichen Mischungen on Diethanolamin und Bis(2-methyl-isobutylketiminoethyl)amin (DKI)umgesetzt. Aus diesen Harzen mit Triethanolamin- und DKI-Endgruppen wurden durch Hydrolyse und Neutralisieren mit Essigsäure kationische Harze mit primären Amin-Endgruppen erhalten, aus denen mit geeigneten Lösungsmitteln und deionisiertem Wasser Emulsionen hergestellt wurden. Deren Eigenschaften und die Elektroabscheidung der Harze aus den Emulsionen wurden untrsucht. Der Effekt der Zugabe von hydrophoben Lösungsmitteln wie Toluol oder Hexylcellosolv (HCS) auf die Abscheidungseigenschaften wird diskutiert.
    Notes: A diglycidylether of bisphenol A epoxy resin (DGEBA) was first reacted with 2,4-toluene diisocyanate partially blocked with 2-ethylhexanol (2-EH P. B. TDI) to form modified epoxy resins, and subsequently reacted with different molar ratios of diethanolamine and bis(2-methylisobutylketiminoethyl)amine (DKI) (used as ring opening agents) to give diethanolamine/diketimine terminated resins. These resins were hydrolyzed and neutralized with acetic acid to give cationic resins containing various contents of primary amine groups in the terminal polymeric chain. These cationic resins can be dissolved in a suitable solvent and mixed with deionized water to obtain emulsions. The electrodeposition properties and characteristics of the resulting cationic resins were investigated in detail. The effects of hydrophobic solvents, such as hexyl cellosolve (HCS) and toluene, on the deposition properties of the emulsions are discussed.
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  • 60
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    Angewandte Makromolekulare Chemie 196 (1992), S. 107-111 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die radikalische Polymerisation von Acrylnitril in Gegonwart verschiedener ungesättigter optischer Aufheller (FB) (Derivate des 1,3,5-Triazins) wurde untersucht. Kolorimetrische Messungen ergaben, daß mehr als 80% des optischen Aufhellers in die Polymerkette eingebaut werden. Zur Erzielung eines intensiven optischen Effektes genügt eine FB-Anfangskonzentration von 0,1 Gew.-%, bezogen auf Acrylnitril.
    Notes: The polymerization of acrylonitrile in the presence of some unsaturated, triazinebased fluorescent brighteners (FB) has been investigated. It was found colourimetrically that more than 80% of the FB is incorporated in the polymer. The initial concentration of 0.1 wt.-% is sufficient to obtain a good bleaching effect without significant decrease of the molecular weight.
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  • 61
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Les polyesters thermoplastiques (PBT et PET) sont des polymères fragiles avec une résistance au choc entaillée faible. Leur renforcement peut être obtenu par extrusion réactive avec dirrérents types de copolymères élastomères de l'éthylène, contenant des fonctons à réactivité potentielle avec extrémités de chaîne acide et hydroxyle des polyesters.Deux types de copolymères ont été étudiés: Ethylène(acrylate d'éthyle/méthacrylate de glycidyle (E/EA/GMA), et éthylène/acrylate d'éthyle/anhydride maléique (E/EA/MAH). Les alliages ont été obtenu par malaxage de 10 à 25% de coppolymères avec du PBT.Le PBT présente une transition fragile, ductile lorsqu'on passe de 10 à 20% de particules dispersées de copolymère au GMA. Les gains les plus importants en résistance au choc sont obtenus en réticulant partiellement la phase dispersée, par association de copolymères en GMA et de copolymères avec MAH et catalyseur de réaction.
    Notes: Poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET) are brittle polymers with poor notched impact strength. Their toughening can be achieved by melt blending with different types of rubbery ethylene copolymers containing functions having potential reactivity with the hydroxy and carboxy end groups in polyesters.Two types of ethylene copolymers were investigated: ethylene/ethyle acrylate/glycidyl methacrylate (E/EA/GMA) and ethylene/ethyl acrylate/maleic anhydride (E/EA/MAH) copolymers. The blends were obtained by reactive extrusion of PBT with 10 to 25% of copolymers.PBT blends undergo a brittle to ductile transition by toughening with GMA copolymer between 10 and 20% of rubbery phase. The most effective toughening could be achieved by a partial crosslinking of the rubbery particles obtained by associating GMA and MAH copolymers and a reaction catalyst.
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  • 62
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    Angewandte Makromolekulare Chemie 196 (1992), S. 101-106 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Orientierung (Neigungswinkel ϕ) von thermotropen Flüssigkristallen (LC) an der Grenzfläche zu polymerbeschichteten Substraten wird nicht nur durch den numerischen Wert der Oberflächenspannung \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm \gamma }_{\rm S} {\rm = \gamma }_{\rm S}^{\rm d} {\rm + \gamma }_{\rm S}^{\rm p} } \right)$\end{document} bestimmt. Das Verhältnis zwischenden dispersiven und polaren Anteilen an \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm \gamma }_{\rm S}^{\rm d} {\rm : \gamma }_{\rm S}^{\rm p} } \right)$\end{document} beeinflußt ebenfalls die Orientierung der LC-Moleküle an der Substratoberfläche. Als Polymere wurden ein Polyimid und ein Midgruppenhaltiges Styrol/Maleinsäureanhydrid-Copolymeres verwendet.
    Notes: The orientation (tilt angle ϕ) of thermotropic liquid crystals (LC) on the interface to a polymer-coated surface is not only determined by the numerical value \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm \gamma }_{\rm S} {\rm = \gamma }_{\rm S}^{\rm d} {\rm + \gamma }_{\rm S}^{\rm p} } \right)$\end{document} of the substrate surface tension. However, the ratio between the dispersive and the polar part of \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm\gamma }_{\rm S}^{\rm d} {\rm : \gamma }_{\rm S}^{\rm p} } \right)$\end{document} also influences the LC orientation on the substrate surface. A polyimide and an amide-modified styrene/maleic anhydride copolymer were used as polymers.
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  • 63
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    Angewandte Makromolekulare Chemie 195 (1992), S. 129-137 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Epoxidharze aus Bisphenol A wurden mit neuen Diphenolen, die Imidgruppen enthalten, modifiziert, um die thermischen Eigenschaften zu verbessern. Die verwendeten Diimiddiphenole wurden aus Dianhydriden und Aminophenolen durch Kondensation hergestellt. Die Diimiddiphenole und die modifizierten Harze wurden durch IR- und NMR-spektroskopische Messungen charakterisiert. Das thermische Verhalten wurde anhand von DSC- und TGA-Messungen untersucht.
    Notes: Epoxy resins derived from Bisphenol A have been modified with new diphenols containing imide moieties in order to improve their thermal properties. The diphenols have been synthesized from dianhydrides and aminophenols by condensation reactions. Diphenols as well as modified resins have been characterized by IR and NMR spectroscopy. The thermal characteristics were evaluated by DSC and TGA.
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  • 64
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    Angewandte Makromolekulare Chemie 195 (1992), S. 165-170 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The structural transformation of a molecular complex (MC) of polyoxyethylene and urea on cooling from the molten state has been investigated by DSC and X-ray analysis. A high-temperature polymorphic from of the MC was found to be formed, which transforms into the known crystal form of the MC with a hexagonal crystal modification on cooling.
    Notes: Die Strukturveränderungen eines Molekülkomplexes (MK) aus Polyoxyethylen und Harnstoff beim Abkühlen aus dem geschmolzenen Zustand werden kalorimetrisch und röntgenographisch untersucht. Es wird festgestellt, daß eine polymorphe Hochtemperaturform des MK entsteht, die beim Abkühlen in die bekannte Kristallform des MK mit hexagonaler Kristallmodifikation übergeht.
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  • 65
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    Angewandte Makromolekulare Chemie 196 (1992), S. 143-154 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Anfangsstadium der Oxidation von Lactamen wurden im Temperaturbereich 70-120°C Cuntersucht. Es wurde festgestellt, daß Pyrrolidon und Piperidon bedeutend schneller oxidiert werden als die sieben-, acht- und dreizehngliedrigen Lactame sowie lineare N-Alkylamide. Die hohe Oxidierbarkeit der fünf- und sechsgliedrigen Lactame kann der leichteren homolytischen Spaltung der N- vicinalen C—H Bindung und der unterschiedlichen Reaktivität der Lactamradikale im Wachstuschritt der Kettenoxidation zugeschrieben werden.
    Notes: The initial stage of oxidation of lactams was studied in the temperature range 70-120°C. It was found that pyrrolidone and piperidone are oxidized essentially more easily than the seven-, eight-, nine- and thirteen-membered lactams as well as linear N-alkylamides. The high oxidizability of the five- and six-membered lactams may be attributed to the easier homolytic splitting of the N-vicinal C—H bond and to the different reactivity of lactam radicals in the propagation step of the chain oxidation.
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  • 66
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    Angewandte Makromolekulare Chemie 196 (1992), S. 127-141 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The relative chain transfer constant for sodium allylsulfonate (NaAS) in the copolymer system acrylonitrile (AN)/methylacrylate (MA) in dimethylformamide (DMF) was determined to be Cx = 0,04 ± 0.01, independent of the initiator used (azoisobutyronitrile, ammoniumperoxodisulfate).The chain transfer reaction explains the influence of NaAS on the polymerization degree, but not the concentration dependence of the copolymerization reactivity ratio r1 · r1 depends on the transfer reaction only in a range of 1 - 5%.The extended Debye-Hückel theory for dilute electrolytes has been successfully tested for a quantitative dependence of r1 from NaAS concentration. The resultant r10-value for infinite dilution of NaAS obviously depends on the acrylonitrile concentration, but only to a small extent (e.g. r10 = 0.32 for [AN] =- 4.26 mol/l). This theory provides comfortable access to resolve the nonideal AN/NaAS copolymerization. This approach may be generally applicable to copolymerizations of monomers with dissociated groups.
    Notes: Im Copolymerisationssystem Acrylnitril (AN)/Methylacrylat(MA) mit Natriumallylsulfonat (NaAS) in Dimethylformamid wurde die relative Übertragunskonstante zum NaAS Cx = 0,04 ± 0,01 unabhängig vom verwendeten Initiator (Azoisobuttyronitril, Ammoniumperoxodisulfat) ermittelt. Die Übertragunsreaktion beschreibt den Einfluß des NaAS auf den Polymerisationsgrad, sie beeinflußt jedoch den Copolymerisationsparameter r1 nur in der Größenordung von 1 bis 5% und kann damit die Konzentrationsabhängigkeit von r1 nicht erklären.Mit Hilfe der erweiterten Debye-Hückel-Theorie für verdünnte Elektrolyte wird die Abhängigkiet des r1-Wertes von der NaAS- Konzentration beschrieben. Der sich daraus für unendliche Verünnung des NaAS ergebende r10-Wert ist offensichtlich noch gerinfügig von der Acrylnitrilkonzentration abhägig. Er liegt beispielsweise für [AN] = 4, 26 mol/1 bei r10 = 0, 32. Damit wurde zum ersten Mal das nichtideale Copolymerisationsverhalten im untersuchten System erkärl. Das Vorgehen sollte verallemeinerungsfähig sein und generell auf das Copolymerisationsverhalten von Monomeren mitdissoziierten Gruppen angewendet werden können.
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  • 67
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    Angewandte Makromolekulare Chemie 196 (1992), S. 169-177 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Katalase wurde durch photoinduzeirte Propfpolymerisation auf mikroporöse polymere Trägermembranen immobilisiert. Die katalytische Aktivität für Zersetzung von Wasserstoffperoxid unter Ultrafitrationsbedingungen wurde mittels eines Rezirkulationsapparates untersucht. Die Membranen zeigten ein sehr gutes katalytisches Verhalten; die Enzymreaktion fand ausschließlich in der Membranstruktur statt. Anfangsreaktionsgeschwindigkeiten, gemessen in einem Temperaturbereich von 5-35°C als Funkation der Substratkonzentration und der Menge des immobilisierten Enzyms pro Einheit Membranoberfäche zeigten, daß sich der Reaktionsmechanismus der Katalase durch die Immobilisierung nicht verädert.
    Notes: Catalase has been immobilized in membranes prepared by photoinduced grafting onto microporous polymeric supports and its catalytic activity on hydrogen peroxide decomposition has been studied under ultrafiltration conditions by means of a recirculation apparatus. The membranes showed a very good catalytic performance and the enzyme reaction took place exclusively within the membrane structure. Initial reaction rates measured in the temperature range 5 - 35°C as a function of both substrate concentration and enzyme amount immobilized per unit membrane surface indicate that the mechanism of action of catalase is not altered after immobilization.
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  • 68
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The network formation process of bisphenol A-diglycidylether and 4,4′-diaminodiphenylmethane was investigated by measuring the torque, the conductivity and the soluble part of the crosslinking system. The activation energy for the curing process was estimated from gel time. The volume shrinkage during network formation was measured. The influence of N,N-dimethylbenzylamine as accelerator was discussed.
    Notes: Der Aufbau von Netwerken aus Bisphenol A-Diglycidylether und 4,4′-Diaminodiphenylmethan wurde durch Messung des Drehmomentes, der Leitfähigkeit und durch Bestimmung der löslichen Anteile des vernetzenden System untersucht. Aus den Gelzeiten wurden die Aktivierungsenergie für den Vernetzungsprozeß bestimmt. Außerdem wurde die während der Vernetzung aufretende Volumenschwindung gemessen. Der Einfluß von N, N-Dimethylbenzylamin als Beschleuniger auf den Vernetzungsprozeß wird diskutiert.
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  • 69
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The UV-laser induced surface modification of various types of high-performance fibers is investigated. Due to the high UV-absorption coefficients, the well-known effect of UV-laser induced etching (ablation) is observed with all fiber types. Furthermore, the relaxation of orientated macromolecules leads to a characteristic structuring of the fiber surface. For a possible controlled use of this physical surface modification, exact conditions for the treatment in view of textile applications are determined. Useful constants like threshold of ablation, etching rate and structuring constants are measured for all fiber types.
    Notes: Die Oberflächenbehandlung von unterschiedlichen Hochleistungsfasertypen mit gepulstem UV- Laserlicht wird untersucht. Bedingt durch die hohen UV-Absorptionskoeffizienten dieser Materialien wird der bekannte Effekt des UV-laserinduzierten Abtrags (Ablation) bei allen Fasern beobachtet. Zusätzlich werden durch die Relaxation der orientierten Makromoleküle charakteristische Strukturierungen auf der Faseroberfläche ausgebildet. Für einen möglichen kontrollierten und gezielten Einsatz dieser physikalischen Oberflächenmodifizierung in textilen Anwendungen werden die gnaunen Bedingungen der Laserbestrahlung ermittelt und beschieben. Darüber hinaus werden geeignete Konstanten der Laserbearbeitung wie Ablationsschwellenenergie, Ätzraten und Strukturierungskonstanten für verschiedene Fasertypen bestimmt.
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  • 70
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    Angewandte Makromolekulare Chemie 198 (1992), S. 165-178 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Dimethyl-diallyl-ammoniumchlorid in konzentrierter wäßriger Lösung mit Persulfat als Initiator kann bis zu hohen Umsätzen mit einem Modell beschrieben werden, in dem folgende Teilreaktionen berücksichtigt werden: a)Primärradikalbildung durch aktivierten Initiatorzerfall sowie Redoxreaktion von S2O2-8 und Cl-b)Kettenwachstum über Monomerkationassoziate undc)Kettenabbruch durch Kombination von cyclisierten Polymerradikalen untereinan der und mit Chloratomen.Für die Polymerisationsgeschwindigkeit wird ein Zeitgesetz hergeleitet, für dessen Konstanten und Parameter numerische Werte ermittelt wurden.
    Notes: The polymerization of dimethyl diallyl ammonium chloride in concentrated aqueous solution with persulfate as an initiator can be described up to high conversion by a kinetic model including a)formation of primary radicals by activated initiator decomposition as well as by redox reaction of S2O82- and Cl-,b)chain propagation via monomer cation associates andc)termination by combination of cyclized polymer radicals between each other or with chlorine atoms.A kinetic expression for the rate of polymerization is presented; rate constants and model parameters have been determined.
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  • 71
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    Angewandte Makromolekulare Chemie 198 (1992), S. 199-199 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 72
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    Angewandte Makromolekulare Chemie 198 (1992), S. 179-190 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polymere mit über eine C—C-Verknüpfung an hochvernetztem Polystyrol kovalent gebundenen, makrocyclischen Amiden wurden durch die Reaktion polymergebundener Malonsäureester-Gruppen mit offenkettigen Diaminen dargestellt. Die Reaktion von vernetztem, chlormethyliertem Polystyrol mit makrocyclischen und offenkettigen Aminen führt zu Polymeren mit kovalenter Bindung über eine C—N-Verknüpfung. Die erhaltenen funktionalisierten Polymeren wurden hinsichtlich der Adsorption von Cu(II)-, Ni(II)- und Co(II)-Ionen aus wäßriger Lösung untersucht.
    Notes: Polymers containing moieties of amides covalently bound to highly crosslinked polystyrene by C—C connections were prepared via a polymer-bound malonic ester group in the reaction with open-chain diamines. The reaction of crosslinked, chloromethylated polystyrene with macrocyclic and open-chain amines results in covalent binding by C—N-connection. The synthesized functionalized polymers were investigated for uptake of Cu(II), Ni(II) and Co(II) ions from aqueous solutions.
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  • 73
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    Angewandte Makromolekulare Chemie 199 (1992), S. 1-6 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(phenylphosphindiylterephthaloyl), ein neues phosphorhaltiges Polymeres, wurde durch Lösungspolykondensation von Dilithium(phenyl)phosphin mit Terephthaloylchlorid bei niedriger Temperatur hergestellt. Es ist in polaren aprotischen Lösungsmitteln löslich; die inhärente Viskosität in DMF bei 30°C beträgt 19 ml/g. Das Polymere wurde mittels Elementaranalyse sowie IR- und 1H-NMR-Spektroskopie charakterisiert. TGA-Messungen ergeben, daß das Polymere in Luft bis 250°C stabil ist; es ist selbstverlöschend.
    Notes: Poly(phenylphosphinediylterephthaloyl), a novel phosphorus-containing polymer, was synthesized by low-temperature solution polycondensation of dilithio(phenyl)-phosphine with terephthaloyl chloride. The resulting polymer is soluble in polar aprotic solvents, having inherent viscosity of 19 ml/g in DMF at 30°C. The polymer was characterized by elemental analysis, IR and 1H-NMR spectroscopy. TGA data show that the polymer is stable up to 250°C in air. The polymer was found to be self-extinguishing.
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  • 74
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird eine neue Methode für die Erweiterung des Meßbereiches der Ausschlußchromatographie, gekoppelt mit Lichtstreuung (SEC/LALLS), zu höherer molarer Masse, vorgestellt. Diese Methode nützt den Effekt, daß das Lichtstreusignal oft schon bei wesentlich kleineren Werten des Elutionsvolumens, also hoheren Werten der molaren Masse erfaßbar ist als das Konzentrationssignal und berücksichtigt dabei die Peakverbreiterung in der SEC. Das betreffende Rechenverfahren wird für den Fall einer logarithmischen Normalverteiung und einer wahrscheinlichsten Verteilung getestet. Im Falle von Polypropylen mit logarithmischer Normalverteilung (M̄W = 420 000 und M̄n = 99 000) kann der durch SEC/LALLS erfaßte Bereich der molaren Masse um einen Faktor von ca. 10 erweitert werden; bei einer wahrscheinlichsten Verteilung (M̄n = 100 000) liegt die erreichbare Erweiterung des Meßbereiches der molaren Masse beieinem Faktor von ca. 2.
    Notes: A new method for the extension of the measuring range of size exclusion chromatography coupled with light scattering (SEC/LALLS) to higher molar mass is presented. This method uses the fact that the light scattering signal can often be detected already at considerable smaller values of the elution volume (i. e. higher values of molar mass) than the concentration signal; furthermore, it takes into account the peak broadening effect in SEC. This procedure is tested for the case of a logarithmic normal distribution and a most probable distribution of molar mass. In the case of polypropylene with a logarithmic normal distribution (M̄w = 420 000, M̄n = 99 000), the range of molar mass covered by SEC/LALLS can be extended by a factor of about 10; with a most probable distribution (M̄n = 100 000), the attainable extension in molar mass assumes a factor of about 2.
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  • 75
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    Angewandte Makromolekulare Chemie 199 (1992), S. 45-63 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Because of the interest in their possible application as biologically degradable polymers, the isotherms of sorption of water vapour by native and thermoplastic starch were measured. The thermomechanical treatment of starch and the insertion of glycerol as softener lead to the disappearance of the hysteresis and to the transition from a Type II to Type III isotherm. A theory, describing the sorption behaviour of swellable sorbents, is introduced and its statements are discussed by means of experimental results. The theory allows to draw conclusions on the molecular behaviour during sorption.
    Notes: Es wurden Wasserdampf-Sorptionsisothermen von nativer und thermoplastischer Stärke gemessen. Die thermisch-mechanische Behandlung der Stärke und das Einfähren von Glyzerin als Weichmacher fährt zum Verschwinden der Hysterese und zum Übergang von der Typ II in eine Typ III Isotherme. Eine Theorie, welche das Sorptionsverhalten von quellbaren Sorbentien gut beschreibt, wird kurz eingeführt und anhand der experimentellen Daten ihre Aussagen diskutiert. Die vorgestellte Theorie erlaubt wegen der physikalischen Bedeutung der Parameter Rückschlüsse auf die molekularen Vorgänge während der Sorption. Die Motivation zur Untersuchung des Sorptionsverhaltens von thermoplastischer Stärke ist deren möglicher Einsatz als biologisch abbaubarer Kunststoff.
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  • 76
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In order to solve the problem of polymer swelling which limits the resolution of negative resists, we have developed new resists where the swelling does not appear. For our study, we developed resists including polymers containing the tetrathiafulvalenylcarbonyloxymethyl radical and dibromotetrachloroethane. In order to study the influence of the nature of the radical bearing the tetrathiafulvalene unit in the polymers on the microlithographic properties of these resists, we also studied polymers containing the tetrathiafulvalenylphenoxymethyl radical. The resists have been tested under UV irradiation. The dependence of resist sensitivity on molecular weight is reported.
    Notes: Pour résoudre le phéomène de gonflement qui limite la résolution des résines microlithographiques classiques, nous nous sommes intéressés à de nouvelles résines avec lesquelles ce phénomène n'apparait pas. Nous avons retenu pour notre étude les résines R qui renferment en mélange un polymère porteur de radicaux tétrathiafulvalénylcarbonyloxyméthyles et le dibromotétrachloroéthane. Afin de voir l'influence de la nature du radical porteur de l'unité tétrathiafulvalène dans le polymtrè sur les propriétés microlithographiques des résines R, nous nous sommes également intéressés aux polymères renfermant des radicaux tétrathiafulvalénylphénoxymethyles. Les résines R ont été testées sous irradiation UV. Leurs sensibilités dépendent en outre de la valeur de la masse molaire du polymèr.
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  • 77
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 33-44 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Hochfeste Polyethylen- (HSPE), Polypropylen- (PP), Polyethylenterephthalat-(PET) und Polyvinylalkohol-(PVA) Textilgarne wurden unter Anwendung des entwickelten kontinuierlichen Einweichprozesses mit verschiedenen funktionellen Monomeren, wie beispielsweise Acrylsäure (AA), Acrylamid (AM), Glycidylacrylat (GA) und 4-Vinylpyridin (VP) oberflächenfotogepfropft. Die Einfärbbarkeit der oberflächenmodifizierten Garne mit verschiedenen Textilfarbstoffen wurde untersucht. Im allgemeinen wurde eine erhebliche Verbesserung der Einfärbbarkeit beobachtet. Die Farbstoffaufnahme der oberflächenfotogepfropften Fasern wird von vielen Faktoren beeinflußt, beispielsweise von der Art der Faser, der Menge und den Eigenschaften des auf die Oberfläche der Fasern gepfropften funktionellen Monomeren, der Art des Textilfarbstoffs usw. Die Faseroberflächen, auf die ein Monomeres mit basischen Gruppen wie Acrylamid und 4-Vinylpyridin gepfropft wurde, lassen sich mit einem sauren Farbstoff wirkungsvoll einfärben. Dagegen läßt sich eine Faseroberfläche, auf die ein saures funktionelles Monomeres gepfropft wurde, leicht mit basischen Farbstoffen in tiefen Farbtönen einfärben. Die Farbstoffaufnahme steigt stetig mit zunehmender Pfropfung, in ESCA-Spectren als relative Intensitaten relevanter Linien gemessen. Die nicht gepfropften HSPE-, PP-, und PET-Fasern können mit bestimmten Farbstoffen in gewissem Maße eingefärbt werden. Bei der vorliegenden Arbeit erhöhte sich die Farbstoffaufnahme bei HSPE-Fasern, die mit GA gepfropft und mit dem Metallkomplexfarbstoff IO eingefärbt wurden, um das 3,4fache, bei PP-Fasern, die mit AA gepfropft und mit dem basischen Farbstoff MB eingefärbt wurden, um das 7,9fache, bei PET mit AM und dem Direktfarbstoff SL um das 6,1fache, bei PVA mit VP und dem sauren Farbstoff TE um das 15,3fache.
    Notes: High-strength polyethylene (HSPE), polypropylene (PP), poly(ethylene terephthalate) (PET), and poly(vinyl alcohol) (PVA) textile yarns have been surface-photografted with various functional monomers, such as acrylic acid (AA), acrylamide (AM), glycidyl acrylate (GA) and 4-vinyl pyridine (VP), by means of the continuous presoaking process developed. The dyeing of these surface-modified yarns with various textile dyes has been investigated. In general, considerable improvements of dyeability have been observed. The dye adsorption of the surface-photografted fibers is influenced by many factors, such as type of fiber, amount and properties of the functional monomer grafted on the surface of the fibers, type of textile dye, etc. The fibers surface-grafted with a monomer containing basic groups, such as acrylamide and 4-vinyl pyridine, are efficiently dyed with an acid dye. Conversely, a fiber surface-grafted with acidic functional monomer is easily dyed to deep shades with basic dyes. The dye adsorption increases monotonically with increasing grafting measured in ESCA spectra as relative intensities of relevant lines. The ungrafted HSPE, PP and PET fibers can be dyed to some extent with certain dyes. In the present work, the dye adsorption increased by 3.4 times for HSPE fiber grafted with GA and dyed with the metal complex dye IO, by 7.9 times for PP fiber grafted with AA and dyed with the basic dye MB, by 6.1 times for PET with AM and with the direct dye SL, and by about 15.3 times for PVA with VP and with the acid dye TE.
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  • 78
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 65-74 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die thermische Stabilität von Acrylnitril-Copolymeren wurde mittels DSC untersucht, um den Einfluß von halogenierten Comonomeren mit Carboxygruppen auf die Stabilisierung von PAN zu präfen. Es wird gezeigt, daß die Aktivierungsenergie fär die Cyclisierung des AN/Bromacrylsäure(BrAA)-Copolymeren (86,2 kJ/mol) deutlich niedriger als die der Copolymeren mit Chloracrylsäure (ClAA, 158 kJ/mol), Acrylsäure (AA, 128 kJ/mol) und Itaconsäure (IA, 102 kJ/mol) ist. Das erlaubt eine Stabilisierung bei häherer Temperatur und eine Verkürzung der Stabilisierungszeit. ClAA ist BrAA bezäglich der Stabilisierungseffektivität nicht überlegen. Der Mechanismus der Cyclisierung von AN-Copolymeren mit halogenierten, carboxygruppenhaltigen Comonomeren wird diskutiert.
    Notes: The thermal stability of AN copolymers was studied by DSC technique in order to get information on the influence of comonomers containing halogenated carboxylic acid on the stabilization of PAN. It is shown that the activation energy of cyclization is reduced in the case of the copolymer with bromoacrylic acid (BrAA, 86.2 kJ/mol) compared with chloroacrylic acid (ClAA, 158 kJ/mol), acrylic acid (AA, 128 kJ/mol) and itaconic acid (IA, 102 kJ/mol). Copolymer AN/BrAA permits the stabilization at higher temperature than AN/IA and AN/AA, helping to shorten the stabilization time. It is proved that comonomer ClAA is not superior to BrAA in the effectiveness of thermal stabilization. The mechanism of the cyclization reaction of AN copolymer containing halogenated carboxylic acid is discussed.
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  • 79
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 75-85 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden neue unsymmetrische cycloaliphatische Bisepoxyderivative hergestellt. Die unterschiedliche Reaktionsfahigkeit der zwei Oxiranringe (cycloaliphatisch und glycidylisch) gegenüber Carbonsäure wurde untersucht, wobei eine normale und anomale Ringöffnung der Glycidylgruppen beobachtet wurde. Eine Homopolymerisation des Oxirans wurde ebenfalls beobachtet. Mit Hilfe der 13C-NMR-Spektroskopie wurde die Struktur der Polymeren ermittelt. Die neuen Epoxidharze zeigen gute thermische Eigenschaften.
    Notes: New bisepoxy unsymmetrical cycloaliphatic derivatives have been synthesized. The different reactivity of both oxirane rings (cycloaliphatic and glycidylic) has been tested against carboxylic acids giving rise to normal and abnormal opening to the glycidyl group. Homopolymerization reaction was also observed. Polymer structures were identified by 13C-NMR spectroscopy. Thermal analysis carried out allowed to confirm their good thermal properties.
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  • 80
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 119-131 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: N,N′-4,4′-Diphenylmethane-bismaleimide (BMI) was oligomerized in semisolid phenolnovolak epoxide-resin (EP) up to P̄n = 10. The morphology of the novolakcured EP-BMI solid resins is a two-phase structure. It consists in a homogeneous EP-BMI phase of an interpenetrating polymer network (IPN) and a BMI phase. The dynamic-mechanical properties depend on the overall weight fraction w2 of BMI and on the degree of oligomerization (P̄)n of BMI. The relative shear modulus of the EP-EMI resin in the rubber state shows that both phases can be coherent. The glass transition temperature (Tg) can be correlated with the degree of oligomerization of the BMI, for instance Δ P̄n ≡ 10 corresponds to Δ Tg ≡ 35 K and Δ wx2 ≡ 0,25 (weight fraction of BMI in the homogeneous EP-BMI phase). Surprisingly, the breaking strength remains constant.
    Notes: N,N′-4,4′-Diphenylmethan-bismaleimid (BMI) wurde in halbfesten Phenolnovolak-Epoxidharzen (EP) bis P̄, = 10 oligomerisiert. Die novolakgehärteten EP-BMI-Festharze bilden eine Zweiphasenstruktur, bestehend aus einer EP-BMI-Mischphase der beiden sich durchdringenden Netzwerke (interpenetrating polymer network, IPN) und einer BMI-Phase. Die dynamisch-mechanischen Eigenschaften hängen vom Gesamt-BMI-Anteil w2 und vom Oligomerisierungsgrad P̄n des BMI ab. Der relative Schubmodul des EP-BMI-Harzes im kautschukelastischen Zustand zeigt, daß beide Phasen kohärent sein können. Die Glastemperatur Tg korreliert mit dem Oligomerisierungsgrad, z. B. entspricht ΔPn ≡ 10 einem ΔTg ≡ 35 K und einem BMI-Anteil Δ wx2 ≡ 0,25 in der Mischphase. Die Bruchzahigkeit bleibt unerwartet konstant.
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  • 81
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Handelsübliche Araldit™-Polymere wurden mit Zimtsäure- bzw. Furanacrylsäurechlorid modifiziert und über [2 + 2]-Cycloaddition photochemisch vernetzt. Die Glasübergangstemperaturen der entstandenen Polymeren betragen bis zu 130°C bei Dielektrizitätskonstanten von ∊r = 3.0. Daher können diese Polymeren in Mehrlagenmikroverdrahtungen verwendet werden. Zahlreiche wohldefinierte, multifunktionelle Modifikatoren wurden synthetisiert und deren Einfluß auf die Polymerisation und die Eigenschaften der Araldit™-Polymeren eingehend untersucht.
    Notes: Commercially available Araldite™-type polymers have been modified with cinnamic and furan acrylic acid chlorides. The polymers were photochemically crosslinked via a [2 + 2] cycloaddition. The resulting polymers show glass transition temperatures up to 130°C and dielectrical constants of ∊r = 3.0. Therefore, these polymers can be applied as permanent resists in multi-layered wiring structures. Numerous well-defined multifunctional modifiers have been synthesized. The effect of those modifiers on the polymerization and properties of the araldite-type polymers has been studied in some detail.
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  • 82
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 200 (1992), S. 61-76 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The photoinduced free radical crosslinking of silicone containing pendent acrylate or methacrylate groups was investigated by swelling measurements. A modified swelling test was applied to observe the network formation as a function of several parameters. The results show that the network density of the crosslinked polymers is a function of the light intensity, the exposure time, the acrylate content, the molecular weight of the uncrosslinked silicone acrylate and also of the length of the spacer group between the acrylate unit and the silicone backbone. Oxygen has only an influence on the polymerization kinetics, but it does not influence the network density.From the δB, -values of crosslinked silicone acrylates and silicone containing vinyl groups it is possible to analyze the structure of the network as a function of the olefinic group. The χ-parameters of both silicone types are of the same magnitude in the same concentration range.Kinetics investigations demonstrate that the order of the network formation is nearly unity. This result agrees with the polymerization kinetics.By means of swelling measurements it is also possible to study the influence of hydrogen siloxane additives as hydrogen transfer reagents.
    Notes: Die photoinduzierte radikalische Vernetzung von Siliconacrylaten bzw. -methacrylaten wurde mit Hilfe von Quellungsmessungen untersucht, wobei ein modifizierter Quellungstest erlaubt, die Netzwerkbildung als Funktion verschiedener Parameter zu betrachten. Die Ergebnisse zeigen, daß die Netzwerkdichte eine Funktion der Lichtintensität, der Bestrahlungszeit, des Acrylatgehalts, der Molmasse des unvernetzten Silicons und auch der Länge der Spacergruppe zwischen Acrylateinheit und dem Siliconrückgrat ist. Sauerstoff besitzt dagegen nur einen Einfluß auf die Polymerisationskinetik, nicht aber auf die Netzwerkdichte.Aus dem Vergleich der δB, -Werte der vernetzten Siliconacrylate und der vernetzten Vinylsilicone kann geschlossen werden, daß die Netzwerkstruktur auch vom Typ der olefinischen Gruppen abhängt. Die χ-Parameter besitzen jedoch im gleichen Konzentrationsbereich die gleiche Größe.Kinetische Untersuchungen zeigen, daß die Netzwerkbildung nach einem Zeitgesetz erster Ordnung verläuft. Dieses Ergebnis steht im Einklang mit der Polymerisationskinetik.Mit Hilfe der Quellexperimente ist es auch moglich, den Einfluß von H-Siloxanzusätzen als Wasserstoffüberträger zu untersuchen.
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  • 83
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 133-148 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The copolymerization of butadiene with a technical divinylbenzene fraction was investigated to study the modification of cis-1,4 polybutadiene. Beside the Ziegler-Natta-catalyst nickeloctanoate/bortrifluoride/aluminiumtriethyl, another catalytic system consisting of nickeloctanoate/titaniumtetrachloride/aluminiumtriethyl was used, which allows to polymerize more divinylbenzene because of its higher activity toward vinylaromates. With the help of spectroscopical, pyrolysis-gaschromatographical and thermoanalytical methods one can obtain relations between glass-, crystallization- and melting temperature and the microstructure of the polymer. It can be shown that not only the divinylbenzene but also the trans-1,4- and the 1,2-vinyl units are statistically distributed in the polymer. By this, beside the pyrolysis-gaschromatography, particularly the differential scanning calorimetry is a useful tool to characterize the structure of partially crosslinked polymers obtained from polymerization of technical fractions.
    Notes: Im Rahmen von Arbeiten zur Modifizierung des cis-1,6Polybutadiens wurde die Copolymerisation von Butadien und einer Divinylbenzolfraktion, insbesondere der Bereich mit kleinen Divinylbenzolgehalten, untersucht. Neben dem Ziegler-Natta-Katalysator Nickeloctanoat/Bortrifluoridetherat/Aluminiumtriethyl kam auch ein Nickeloctanoat/Titantetrachlorid/Aluminiumtriethyl-System zur Anwendung, welches es durch seine höhere Aktivität gegenüber Vinylaromaten ermöglicht, großere Mengen der Divinylbenzolfraktion zu polymerisieren. Durch die Anwendung von spektroskopischen, pyrolysegaschromatographischen und thermoanalytischen Charakterisierungsmethoden können Beziehungen zwischen den erhaltenen Glas-, Kristallisations- und Schmelztemperaturen und der Mikrostruktur des Polymeren hergestellt werden. Es zeigt sich, daß sowohl das Divinylbenzol als auch die trans-1,4 bzw. die 1,2-Vinyl-Einheiten statistisch in das Polymere eingebaut werden. Damit eignet sich neben der Pyrolysegaschromatographie besonders die Differential Scanning Calorimetry als eine einfache Methode zur Charakterisierung der Struktur von aus technischen Fraktionen erhaltenen und teilweise vernetzten Polymerproben.
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  • 84
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Optisch hochreine Gläser wurden aus Polystyrol (PS), Polymethylmethacrylat (PMMA) und statistischen Styrol-Methylmethacrylat-Copolymeren (S-MMA) hergestellt. Die an diesen Gläsern gemessene Lichtstreuung hängt von der chemischen Zusammensetzung des Polymeren und dem Brechungsindex des zugesetzten Weichmachers ab. Ein isorefraktiver Weichmacher verringert die Streuwerte der S-MMA-Copolymeren, hat aber keinen signifikanten Einfluß auf das Streuverhalten von PMMA. Ein Weichmacher mit einem vom Polymeren verschiedenen Brechungsindex verschlechtert die Streuwerte in allen untersuchten Fällen. Es wird gezeigt, daß ein isorefraktiver Weichmacher die Dämpfungseigenschaften von aus dem Copolymeren S-MMA 2/1 gezogenen polymeren Lichtleitern verbessert.
    Notes: High optical purity polystyrene (PS), poly(methyl methacrylate) (PMMA) and styrene-methyl methacrylate statistical copolymers (S-MMA) were prepared. Light scattering measured on polymeric glasses depends on the chemical composition of the polymer and on the refractive index of the plastifier added. An isorefractive plastifier reduces considerably the scattering values for the copolymers S-MMA, while having no significant effect on the scattering of PMMA. A plastifier with a refractive index different from that of the polymer raises distinctly the light scattering values in all cases. It has been shown that the isorefractive plastifier has a favourable effect on attenuation loss of polymeric optical fibers (POF) obtained from the copolymer S-MMA 2/1.
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  • 85
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: ABS/TPU- und SAN/TPU-blends were investigated on the basis of the analysis of viscoelastic behaviour of the components for characterization of the formation of morphology in melt mixing processes. Blends mixed in a laboratory kneeder and extruded from a high pressure capillary viscosimeter under definite conditions were characterized concerning their phase morphology by transmission electron microscopy. The types of morphology predicted by the help of rheological analysis could be confirmed by electron micrographs and quantitative analysis of morphology. It becomes evident, that the ratio of viscosity of the components has the primary influence on the formation of morphology in the blends. But also thermomechanically induced molecular destruction processes and thermodynamic interactions as well as connecting crystallisation conditions for the TPU-phase are not negligible with regard to resulting phase morphology.
    Notes: An ABS/TPU- bzw. SAN/TPU-Blends wurden Untersuchungen zur Morphologiebildung beim Schmelzemischen auf der Basis der Analyse des viskoelastischen Verhaltens der Komponenten angestellt. Unter definierten Bedingungen im Laborkneter gemischte und unter definierten Bedingungen mittels Hochdruckkapillarviskosimeter extrudierte Blendproben wurden hinsichtlich ihrer Phasenmorphologie elektronenmikroskopisch charakterisiert. Die mittels der rheologischen Analyse prognostizierten Morphologietypen und Morphologiebildungsmechanismen konnten anhand der elektronenmikroskopischen Aufnahmen und der quantitativen Morphologieanalyse bestätigt werden. Es zeigte sich, daß das Viskositätsverhältnis der Komponenten primären Einfluß auf die Morphologiebildung ausübt. Darüber hinaus sind auch thermomechanisch induzierte molekulare Abbauvorgänge und thermodynamische Wechselwirkungen sowie damit im Zusammenhang stehende Kristallisationsbedingungen für die TPU-Phase hinsichtlich der resultierenden Phasenmorphologie nicht zu vernachlässigen.
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  • 86
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    Angewandte Makromolekulare Chemie 194 (1992), S. 189-200 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Stabilität von Verbindungen von Polypropylen (PP) und Polycarbonat (PC) mit einem Acryl-Kleber wurde mit einer thermodynamischen, auf der Messung von Oberflächenspannungen beruhenden Methode bestimmt.Die Charakterisierung der Oberflächen zeigte, daß eine Plasmabehandlung die Bildung einer sauerstoffreichen Oberflächenschicht bewirkt. Eine Lagerung in Wasser führt bei PP zu keiner Veränderung dieser Schicht, während bei PC niedermolekulare, oxidierte Verbindungen ausgewaschen werden.Sowohl unbehandelte als auch mit Plasma behandelte PP-Verbindungen wiesen bei Lagerung in Wasser eine annehmbare Stabilität auf. Zwar wurde eine geringe Abnahme der Scherfestigkeit gemessen, aber unbehandeltes und plasmabehandeltes PP zeigten weiterhin adhäsives bzw. kohäsives Bruchverhalten.Im Falle von PC blieben nur die aus unbehandeltem PC hergestellten Verbindungen ausreichend stabil, während die aus plasmabehandeltem PC hergestellten Verbindungen stark abgebaut wurden. Bei den letzteren wanderte der Versagensort an die Polymer/Kleber-Grenzfläche, was auf die Ausbildung einer sehr hydrophilen, niedermolekularen Schicht zurückgeführt wird.
    Notes: The stability of PP and PC/acrylic adhesive joints has been assessed using a thermodynamic method based on surface tension components.Surface characterization showed that plasma treatment induces the formation of an oxygen-rich layer on treated surfaces. In the case of PP this layer does not change its composition upon immersion in water, while for PC leaching of oxidized species with low molecular weight was observed.Both untreated and plasma treated PP joints showed reasonable stability against immersion in water. A small reduction of shear strength was observed, but the fracture remained adhesive for untreated PP and cohesive for plasma treated PP.In the case of PC, only joints made from untreated PC showed fair sensitivity against immersion in water, while those made from plasma treated specimens degraded dramatically. In the latter case the locus of failure moved to the adhesive/adherend interface, the presence of a very hydrophilic, low molecular weight layer being suggested as responsible for this behavior.
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  • 87
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The chloromethylated polystyrenes bearing tetrathiafulvalenylcarbonyloxymethyl groups can be oxidized. We have shown that ion radical salts are obtained from these polymers and carbon tetrabromide after irradiation with UV light. Charge transfer complexes were prepared by mixing these polymers and 2,3-dichloro-5,6-dicyanobenzoquinone. The possible presence of sulfoxides as a result of oxidation of some tetrathiafulvalene units could explain the difficulties we have observed to filter solutions of these polymers.
    Notes: Les polystyrènes chlorométhylés renfermant des radicaux tétrathiafulvalénylcarbonyloxyméthyles peuvent être oxydés. Ainsi la formation de sels d'ions radicaux obtenus à partir de ces polymères et de tétrabromure de carbone, irradiés sous UV, a été mise en évidence. Des complexes de transfert de charge ont été préparés en mettant en présence ces polymères et de la 2,3-dichloro-5,6-dicyanobenzoquinone. La présence de sulfoxydes non décelés et résultant de l'oxydation de certaines unités de tetrathiafulvalène contenus dans ces polymères pourrait expliquer les problèmes rencontrés lors de la filtration de leurs solutions.
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  • 88
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Metallkomplexierung von wasserloslichem Poly[1-(2-hydroxyethyl)aziridin-co-2-methyl-2-oxazolin] mit Co(II), Zn(II), Ni(II), Cu(II), Cr(III), Fe(III), Cd(II), Pb(II) und Sr(II)-Ionen wurde in wäßriger Phase mit der Methode der Liquid-Phase Polymer-Based Retention (LPR) untersucht. Die Studie zeigt, daß alle Metallionen, außer Co(II) und Zn(II), bei pH 5 komplexiert wurden. Im Gegensatz zu Sr(II), das nur eine schwache Wechselwirkung in einem pH-Bereich von 3 bis 7 zeigte, wurden bei pH 7 94% Co(II) und 88% Zn(II) retentiert. Bei pH 3 zeigten nur Cu(II) und Cr(III) eine Wechselwirkung mit dem Polymeren, wobei die Retentionswerte 76% für Cu(II) und 52% für Cr(III) betrugen. Viskositätsmessungen des Copolymeren in Gegenwart von Metallionen wurden bei verschiedenen pH-Werten durchgeführt.
    Notes: The metal complexation of water-soluble poly[1-(2-hydroxyethyl)aziridine-co-2-methyl-2-oxazoline] with Co(II), Zn(II), Ni(II), Cu(II), Cr(III), Fe(III), Cd(II), Pb(II), and Sr(II) ions was investigated in aqueous phase using Liquid-Phase Polymer-Based Retention (LPR). The study shows that all metal ions are complexed at pH 5, except Co(II) and Zn(II). In contrast to Sr(II), which showed only a slight interaction over a pH range of 3 to 7, 94% of Co(II) and 88% of Zn(II) were retained at pH 7. At pH 3, only Cu(II) and Cr(III) ions interacted with the copolymer with retention values of 76% for Cu(II) and 52% for Cr(III). Viscosimetric measurements of the copolymer were performed in the presence of metal ions at different pH values.
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  • 89
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    Angewandte Makromolekulare Chemie 197 (1992), S. 117-129 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Makroretikulare Copolymerperlen wurden durch Suspensionspolymerisation von Styrol, Bis(2-chlorethyl)vinylphosphonat (CEVP) und Divinylbenzol (DVB) in Gegenwart von Toluol als Verdünnungsmittel hergestellt. Die auf der Perlenoberfläche vorhandenen 2-Chlorethylphosphonat-Gruppen wurden durch Hydrolyse mit verdünnter Salpetersäure in Phosphon-Gruppen transformiert. Für die Einführung zusätzlicher Phosphon-Gruppen wurden die Copolymeren in Gegenwart von Aluminiumchlorid-Katalysator mit Phosphortrichlorid phosphoryliert, und die dabei entstandenen Dichlorphosphingruppen wurden mit verdünnter Salpetersäure verseift und oxidiert. Die Untersuchungen zur Chelatbildung der Copolymeren mit Metallionen zeigten, daß sie ein hohes Adsorptionsvermögen für Uranylionen und gute Stabilität gegen Chemikalien wie Säuren und Alkalien aufweisen. Es wurde auch gefunden, daß die Phosphongruppen enthaltenden Copolymeren recht effektive Adsorbentien für eine Vielzahl von Schwermetalionen wie Pb2+, Hg2+, Cd2+ und Cu2+ sind.
    Notes: Macroreticular copolymer beads were prepared by suspension polymerization of styrene, bis(2-chloroethyl) vinyl phosphonate (CEVP) and divinylbenzene (DVB) in the presence of toluene as diluent. The bis(2-chloroethyl) phosphonate groups on the bead surface were converted into phosphono groups by hydrolysis with dilute nitric acid. For the additional enrichment of phosphono groups, the copolymers were phosphorylated at the phenyl rings with phosphorus trichloride in the presence of aluminum chloride and hydrolyzed and oxidized with dilute nitrics acid. The investigations on metal ion chelation characteristics of the bead-type copolymers revealed that they have very high adsorptivity toward uranyl ions and good chemical resistance under acidic and alkaline media. It was also found that the phosphono group-containing copolymer beads are effective adsorbents for other heavy metal ions such as Pb2+, Hg2+, Cd2+, and Cu2+.
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  • 90
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    Angewandte Makromolekulare Chemie 197 (1992), S. 131-139 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Lösungen von Phenylisocyanat (I) in DMF wurden sowohl bei verschiedenen Temperaturen als auch in Gegenwart von Polyurethankatalysatoren und/oder 1,3-Diphenylharnstoff (II) gelagert. Die Reaktionsprodukte wurden mit Hilfe der HPLC quantifiziert. Neben der Hydrolyse von I zu II wird bei 20°C eine signifikante Reaktion von I mit II zu 1,3,5-Triphenylbiuret (III) beobachtet.Oberhalb 60°C reagiert I mit dem Lösungsmittel zu N,N-Dimethyl-N′-phenylformamidin (V). In DMF dissoziiert III bereits bei Temperaturen 〉 40°C zu I und II.
    Notes: Solutions of phenylisocyanate (I) in DMF were stored at different temperatures in the presence of both polyurethane catalysts and 1,3-diphenylurea (II). The reaction products were determined by HPLC. Beside the hydrolysis of I to II, a significant reaction of I with II to 1,3,5-triphenylbiuret (III) was observed at 20°C. Above 60°C, I reacted with the solvent to form N,N-dimethyl-N′-phenylformamidine (V). In DMF, III dissociated to I and II already at temperatures 〉40°C.
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  • 91
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    Angewandte Makromolekulare Chemie 197 (1992), S. 141-147 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Glasfaserverstärkte Epoxidlaminate wurden aus den Matrixharzen Tetraglycidyldiaminodiphenylmethan (TGDDM) und Tetraglycidylbis(o-toluidino)methan (TGMBT) unter Verwendung von Härtern wie 4,4′-Diaminodiphenylmethan (DDM), 4,4′-Diaminodiphenylsulfon (DDS) und Diethylentriamin (DETA) hergestellt. Die mechanischen und dielektrischen Eigenschaften sowie die Chemikalienresistenz der Laminate wurden untersucht. Die Zugabe eines Epoxyverstärkers (20 Gew.-%, bezogen auf das Matrixharz) ergab eine Verbesserung der mechanischen Eigenschaften.
    Notes: Glass fiber-reinforced epoxy composites were prepared from the matrix resins tetraglycidyl diaminodiphenylmethaneSystematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-diaminodiphenylmethane. (TGDDM) and tetraglycidyl bis(o-toluidino)-methaneSystematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-bis(o-toluidino)methane. (TGMBT) using various amines like 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenylsulfone (DDS) and diethylene triamine (DETA) as curing agents. The fabricated laminates were evaluated for their mechanical and dielectrical properties and chemical resistance. The composites prepared using an epoxy fortifier (20 phr) showed significant improvement in the mechanical properties.
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  • 92
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    Angewandte Makromolekulare Chemie 197 (1992), S. 149-157 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In 1 μm layers of different polymers containing 10 wt.-% 4,4′-diazidobiphenyl, the network formation under the influence of UV-irradiation was estimated by solvent treatment. The high activity of poly(glycidyl methacrylate) against the nitrenes formed is caused by its 1,2-epoxypropyl groups. As confirmed by IR-spectroscopy, the oxirane ring itself is not affected; NMR spectroscopic results indicate reactions between nitrenes and exocyclic CH2-groups.
    Notes: Die UV-Vernetzung in 1 μm-Schichten aus Polymeren verschiedener Konstitution, die 10 Gew.-% 4,4′-Diazidobiphenyl (DABP) enthalten, wird zeitabhängig anhand der reduzierten Schichtdicke nach Lösungsmittelbehandlung verglichen. Für die hohe Vernetzungsgeschwindigkeit von Polyglycidylmethacrylat mit den photolytisch gebildeten Bisnitrenen sind die 1,2-Epoxypropylgruppen verantwortlich. Der Oxiranring bleibt erhalten (IR-Spektroskopie). Wahrscheinlicher Reaktionsort ist die exocyclische CH2-Gruppe (13C-Festkörper-NMR-Spektroskopie).
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  • 93
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    Angewandte Makromolekulare Chemie 197 (1992), S. 159-173 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ausgehend von 10 unterschiedlich 4′-substituierten 4-[N,N-dihydroxyethyl]aminoazobenzolen wurden durch Umsetzung mit Hexamethylendiisocyanat polymere Azofarbstoffe (M̄n 4200-10200) synthetisiert und die Substituentenabhängigkeit der spektralen Eigenschaften, der Redoxpotentiale und des Ausbleichverhaltens mit entsprechenden monomeren und dimeren Modellverbindungen verglichen. Die Ausbleichung erfolgt durch einen photooxidativen Prozeß. In der Reihenfolge monomerer 〉 dimerer 〉 polymerer Azofarbstoff sinkt die Lichtstabilität durch die Verringerung thermischer Desaktivierungsprozesse sowie durch einen möglichen intramolekularen Energietransfer.
    Notes: Starting from 10 different 4′-substituted 4-[N,N-dihydroxyethyl]aminoazobenzenes, polymeric urethane-azo dyes (M̄n 42000-10200) were prepared by reacting those with hexamethylene diisocyanate. The dependence of spectral properties, redox potentials and photofading behaviour on the kind of substitutents was determined and then compared with corresponding monomer and dimer model compounds. Photofading is caused by a photooxidative process. In the sequence of monomeric 〉 dimeric 〉 polymeric azo dyes, light stability decreases due to a diminution in thermal disactivation processes and in a possible intramolecular energy transfer.
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  • 94
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    Angewandte Makromolekulare Chemie 197 (1992), S. 207-208 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 95
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    Angewandte Makromolekulare Chemie 197 (1992), S. 201-206 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bead cellulose, particle diameter 0.1 - 2.7 mm, was prepared from dispersions of viscose in chlorobenzene by applying the thermal sol-gel transition. Technical viscose containing modifiers Berol Visco 32, Berol Glyco 1540 and Kordamin V was used. The size of cellulose beads can be controlled by means of the amount of oleic acid in the dispersion medium. The optimal result was reached at 5 - 6 mg oleic acid in 90 ml chlorobenzene.
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  • 96
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    Angewandte Makromolekulare Chemie 197 (1992), S. 185-199 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: PET- und PA 66-Textilien wurden unter normalen Bedingungen mit verschiedenen Dispersionsfarbstoffen gefärbt. Die gefärbten Textilien wurden mit 180 kV Elektronenstrahlung bestrahlt. Es wurde beobachtet, daß, verglichen mit den unbestrahlten Materialien, zunehmende Strahlungsdosen zu einer Zunahme des Gesamtfarbabstandes dE führten. Diese Farbunterschiede werden hauptsächlich von zwei Reaktionen verursacht: Erstens von der reversiblen Bildung von Farbstoffradikalen, die (an Luft) wieder zu den Ausgangsfarbstoffen reoxidiert werden können und zweitens durch die irreversible Reaktion von Farbstoffmolekülen mit dem Faserpolymeren. Die zweite Reaktion ruft eine permanente Farbänderung des Textils hervor, die bei entsprechenden Bestrahlungsbedingungen klein gehalten werden kann. Die Entscheidung, ob diese Veränderung toleriert werden kann, hängt von der weiteren Verwendung des Textils ab.
    Notes: PET and PA 66 fabrics were dyed with different disperse dyes under regular conditions. The dyed fabrics were irradiated with 180 kV electron radiation. It was observed that increasing radiation doses led to increasing total color differences dE if compared to the unirradiated materials.These color differences are mainly caused by two types of reactions. First by the reversible formation of dye radicals, which can be reoxidized (in air) to the original dye molecules, and second by the irreversible reaction of dye molecules with the fiber polymer. The latter reaction causes a permanent change of the color of the fabric, which can be kept low with the proper irradiation conditions. The decision whether or not this change can be tolerated depends on the further use of the textile.
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  • 97
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    Angewandte Makromolekulare Chemie 197 (1992), S. 175-184 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Unterschiedlich 4′-substituierte 4-[N-Ethyl-N-(2-acryloyloxy)ethyl]aminoazobenzole dienten als Ausgangsmonomere für Homopolymerisationen und Copolymerisationen mit Styrol und Methylmethacrylat. Die Photobleichung der erhaltenen polymeren Azofarbstoffe (M̄ 4200-9000) wurde mittels einer Xenotest-Apparatur untersucht und mit den entsprechenden Monomeren verglichen. Es wird angenommen, daß die in der Reihenfolge monomerer  -  copolymerisierter  -  homopolymerisierter Azofarbstoff sinkende Photostabilität durch zunehmenden Energietransfer in der Matrix verursacht wird.
    Notes: Different 4′-substituted 4-[N-ethyl-N-(2-acryloyloxy)ethyl]aminoazobenzenes were used as starting monomers for homopolymerization and copolymerization reactions with styrene and methyl methacrylate. The photofading behaviour of the obtained polymeric azo dyes (M̄n 4200 - 9000) was investigated by means of a Xenotest device and compared with that of the corresponding monomers. The decreased photostability in the order monomer  -  copolymer  -  homopolymer was assumed to be caused by an increasing energy transfer in the matrix.
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  • 98
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    Angewandte Makromolekulare Chemie 198 (1992), S. 31-38 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: N-Methacryloyloxyphthalimid und N-Methacryloyloxytetrabromphthalimid wurden durch Reaktion von Methacrylsäure bzw. Methacryloylchlorid mit N-Hydroxyphthalimid bzw. N-Hydroxytetrabromphthalimid hergestellt und homopolymerisiert. Die Austauschreaktionen der Polymeren mit Hydroxy- und Amin-Verbindungen wurden untersucht.
    Notes: N-Methacryloyloxyphthalimide (NMPI) and N-methacryloyloxytetrabromophthalimide (NMTPI) were prepared by the reaction of methacrylic acid with N-hydroxy-phthalimide and N-hydroxytetrabromophthalimide, respectively. The resulting monomers were polymerized. The reactions of the resulting polymers with hydroxy and amine compounds have been studied.
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  • 99
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    Angewandte Makromolekulare Chemie 198 (1992), S. 15-29 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Tempern von Poly(etheretherketonketon) zwischen Glasübergangs- und Schmelztemperatur erzeugt normalerweise einen ausgeprägten Doppelschmelzpeak in der DSC-Kurve dieses Polymeren. Die eingehende Untersuchung dieses Doppelschmelzverhaltens in Abhängigkeit von Temperbedingungen und experimentellen Parametern zeigt, daß die Kristallisation als ein in zwei Stufen mit unterschiedlichen Zeitskalen ablaufender Prozeß beschrieben werden kann. Eine Rekristallisation als Ursache des Doppelpeaks kann widerlegt werden.
    Notes: Annealing poly(ether ether ketone ketone) (PEEKK) between glass transition and melting temperature generally results in a pronounced double peak melting behavior as obtained by DSC. Detailed investigations of the dependence of this double peak melting behavior on annealing conditions and experimental parameters clearly reveal that the crystallization can be described by a two-stage process occurring on different time scales. A recrystallization model as origin for the double peak melting curves can be disproved.
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  • 100
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    Angewandte Makromolekulare Chemie 198 (1992), S. 1-14 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Nitrilkautschuk (NBR) wurde mit trans-Chlorcarbonylbis(tripheny1phosphin)rhodium(1) [trans-RhCI(CO)(PPh3)2] und Hydridocarbonyltris(triphenylphosphin)rhodium(1) [RhH (CO)(PPh3)3] als Katalysatoren in homogener Lösung selektiv hydroformyliert. Bei der Hydroformylierung von NBR mit 40 mol-% Acrylnitril bei 363 K, 5,6 MPa Gasdruck (CO:H2 = 1:1) und mit 0,43 mmol Katalysator werden mit trans-RhCl(CO)(PPh3)2 25% und mit RhH (CO)(PPh3)3 30% Umsatz erreicht. Beide Reaktionen sind bezüglich der Olefin- und Katalysatorkonzentration pseudo-erster Ordnung. Mit RhH (CO)(PPh3)3 wird eine höhere Reaktionsgeschwindigkeit erhalten. Die IR- und NMR-spektroskopische Charakterisierung der Produkte zeigt, daß sowohl die 1,4- als auch die 1,2-Butadieneinheiten hydroformyliert werden. Mit steigendem Aldehydgruppengehalt sinkt die Grenzviskositatszahl [q] und steigt die Glastemperatur. Bei hoheren Hydroformylierungsgraden wird Gelbildung beobachtet.
    Notes: Selective homogeneous catalytic hydroformylation of nitrile rubber (NBR) has been carried out in presence of trans-chlorocarbonylbis(triphenylphosphine)rhodium(I) [trans-RhCl(CO)(PPh3)3] and hydridocarbonyltris(triphenylphosphine)rhodium(I) [RhH(CO)(PPh3)3] as catalysts. At 363 K, under 5.6 MPa pressure (CO:H2 = 1:1) in presence of 0.43 mmol/l catalyst, the amount of hydroformylation is 25% in the case of trans-RhCl(CO)(PPh3)2 and 30% in the case of RhH (CO)(PPh3)3 for NBR with 40 mol-% acrylonitrile. Reaction kinetics suggest that both the reactions are pseudo-first order with respect to olefinic substrate and catalyst concentration. The rate of the reaction is higher in the case of RhH(CO)(PPh3)3. The characterization of the products by IR and NMR spectroscopy shows the formation of internal aldehyde groups from 1,4-units and terminal branched aldehyde groups from 1,2-units of the copolymer. Measurements on intrinsic viscosity [η] and glass transition temperature (Tg) suggest a decrease in [η] and an increase in Tg with the degree of formyl functionalization. Gel formation has been observed at higher degree of hydroformylation.
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