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  • Wiley-Blackwell  (125,065)
  • 2020-2022  (1)
  • 2005-2009  (46)
  • 1990-1994  (66,038)
  • 1980-1984  (43,083)
  • 1940-1944  (5,314)
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  • 1
    Publication Date: 2021-06-22
    Description: In this work, we analyse continuous measurements of microseisms to assess the reliability of the fundamental resonance frequency estimated by means of the horizontal-to-vertical (H/V) spectral ratio within the 0.1–1 Hz frequency range, using short-period sensors (natural period of 1 s). We apply the H/V technique to recordings of stations installed in two alluvial basins with different sedimentary cover thicknesses—the Lower Rhine Embayment (Germany) and the Gubbio Plain (Central Italy). The spectral ratios are estimated over the time–frequency domain, and we discuss the reliability of the results considering both the variability of the microseism activity and the amplitude of the instrumental noise. We show that microseisms measured by short period sensors allow the retrieval of fundamental resonance frequencies greater than about 0.1–0.2 Hz, with this lower frequency bound depending on the relative amplitude of themicroseism signal and the self-noise of the instruments. In particular,we show an examplewhere the considered short-period sensor is connected to instruments characterized by an instrumental noise level which allows detecting only fundamental frequencies greater than about 0.4 Hz. Since the frequency at which the peak of the H/V spectral ratio is biased depends upon the seismic signal-to-instrument noise ratio, the power spectral amplitude of instrumental self-noise should be always considered when interpreting the frequency of the peak as the fundamental resonance frequency of the investigated site.
    Description: Published
    Description: 175-184
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: site effects ; fourier analysis ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
    Publication Date: 2020-09-21
    Description: Streams and rivers are important components of the carbon cycle as they transport and transform dissolved organic matter (DOM). Using high‐resolution Fourier‐transform ion cyclotron resonance mass spectrometry, we studied the spatial distribution of DOM at the molecular level at more than 100 sites across a stream network during summer and winter baseflow. We developed a model approximating the time DOM spent in the fluvial network, a key constraint on the biogeochemical processing of DOM. Discharge‐weighted travel time explained the compositional changes of DOM, which differed markedly in summer and winter. We attribute these seasonal differences to variation in source material, putatively reflecting the dynamics of freshly produced DOM in summer and DOM with an imprint of leaf litter in winter. Hydrological mixing was an important driver of the spatial dynamics of DOM. From the convergence rate of DOM compound intensities to the network‐wide average, we inferred the spatial distribution of sources within the catchment. Finally, we estimated network‐wide apparent mass transfer coefficients (vf app) of individual DOM compounds, which describe the vertical velocity at which DOM compounds are removed by biotic and abiotic processes. We identified the oxidative state of carbon as an important factor explaining vf app, which we consequently attribute to biological uptake of thermodynamically favorable DOM compounds. This work contributes to our understanding of the spatial processes, temporal constraints, and chemical properties of DOM that regulate the transformation and diagenesis of DOM at the fluvial network scale.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
    Publication Date: 2017-04-04
    Description: Geochemical investigations have shown that there is a considerable inflow of gas into both crater lakes of Monticchio, Southern Italy. These lakes are located in two maars that formed 140 000 years ago during Mt. Vulture volcano s last eruptive activity. Isotopic analyses suggest that CO2 and helium are of magmatic origin; the latter displays 3He ⁄ 4He isotope ratios similar to those measured in olivines of the maar ejecta. In spite of the fact that the amount of dissolved gases in the water is less than that found in Lake Nyos (Cameroon), both the results obtained and the historical reports studied indicate that these crater lakes could be highly hazardous sites, even though they are located in a region currently considered inactive. This could be of special significance in very popular tourist areas such as the Monticchio lakes, which are visited by about 30 000 people throughout the summer, for the most part on Sundays.
    Description: Published
    Description: 83-87
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic gases ; gas hazard ; crater lakes ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    Publication Date: 2017-04-04
    Description: On 2009 April 6, the Central Apennines were hit by an Mw = 6.3 earthquake. The region had been shaken since 2008 October by seismic activity that culminated in two foreshocks with Mw 〉 4, 1 week and a few hours before the main shock. We computed seismic moment tensors for 26 events with Mw between 3.9 and 6.3, using the Regional Centroid Moment Tensor (RCMT) scheme. Most of these source parameters have been computed within 1 hr after the earthquake and rapidly revised successively. The focal mechanisms are all extensional, with a variable and sometimes significant strike-slip component. This geometry agrees with the NE–SW extensional deformation of the Apennines, known from previous seismic and geodetic observations. Events group into three clusters. Those located in the southern area have larger centroid depths and a wider distribution of T-axis directions. These differences suggest that towards south a different fault systemwas activated with respect to the SW-dipping normal faults beneath L’Aquila and more to the north.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: moment tensor ; seismotectonics ; L'Aquila ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2017-04-04
    Description: The strong motion data of 2009 April 6 L’Aquila (Central Italy) earthquake (Mw = 6.3) and of 12 aftershocks (4.1 ≤ Mw ≤ 5.6) recorded by 56 stations of the Italian strong motion network are spectrally analysed to estimate the source parameters, the seismic attenuation, and the site amplification effects. The obtained source spectra for S wave have stress drop values ranging from 2.4 to 16.8 MPa, being the stress drop of the main shock equal to 9.2 MPa. The spectral curves describing the attenuation with distance show the presence of shoulders and bumps, mainly around 50 and 150 km, as consequence of significant reflected and refracted arrivals from crustal interfaces. The attenuation in the first 50 km is well described by a quality factor equal to Q( f ) = 59 f 0.56 obtained by fixing the geometrical spreading exponent to 1. Finally, the horizontal-to-vertical spectral ratio provides unreliable estimates of local site effects for those stations showing large amplifications over the vertical component of motion.
    Description: Published
    Description: 1573–1579
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: Generalized inversion ; strong-motion ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Wiley-Blackwell
    In:  Journal of Zoology, 179 (3). pp. 291-295.
    Publication Date: 2020-07-17
    Description: The cartilaginous tubercles of the mantle of the squid Cranchia scabra have been examined with the scanning electron microscope. Some tubercles are small, simple nodules whereas others are large with a complex Maltese cross form. The varying shapes and sizes probably represent a developmental sequence. The possible role of the tubercles is discussed.
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  • 7
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    Wiley-Blackwell
    In:  Journal of Zoology, 224 (3). pp. 431-477.
    Publication Date: 2020-07-17
    Description: Three specimens of the rare giant squid (genus Architeuthis, 18 nominal species) are described from the waters around southern Africa. Consideration of their internal and external morphology, including beaks, radula, statocyst and statolith give no reason to suppose that the three specimens do not pertain to the same species. A standardized data collection form and a summary of existing morphometric data are presented for the first time and the morphology and systematics of the genus are discussed. The value of various systematic characters is examined and certain guidelines are proposed, with an appeal for a more scientific approach to Architeuthis studies. Features of the internal anatomy, including the female reproductive tract, are described and illustrated and the beak dimensions are used to evaluate existing regression formulae for beak and body parameters. The statocyst and statolith are described and illustrated in full, the statolith for the first time, and are compared with those of other squids. The value of recent data from trawl-caught specimens, as well as indirect evidence, is cited to replace speculation in discussions on distribution and habitat. Our specimens suggest that the waters off the south-western coast of Africa may be one of the natural habitats of Architeurhis, during both feeding and spawning periods of the life cycle.
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  • 8
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    Wiley-Blackwell
    In:  Journal of Quaternary Science, 23 (1). pp. 3-20.
    Publication Date: 2017-04-06
    Description: Investigations indicate that the Iceland Ice Sheet was reduced in size during MIS 3 but readvanced to the shelf break at the LGM. Retreat occurred very rapidly around 15 k–16 k cal. yr BP. By contrast, the margin of the ice sheet on the East Greenland shelf, north of the Denmark Strait, was at or close to the shelf break during MIS 3 and 2 and retreat starting ∼17 k cal. yr BP. Quantitative X-ray diffraction analysis of the 〈2 mm sediment fraction was undertaken on 161 samples from Iceland and East Greenland diamictons, and from cores on the slopes and margins of the Denmark Strait. Weight% mineralogical data are used in a principal component analysis to differentiate sediments derived from the two margins. The first two PC axes explain 52% of the variance. These associations are used to characterise sediments as being affiliated with (a) Iceland, (b) East Greenland or (c) mixed. The contribution from Iceland becomes prominent during MIS 2. The extensive outcrop of early Tertiary basalts on East Greenland between 68° and 71° N is an alternative source for basaltic clasts and North Atlantic sediments with εNd(0) values close to ±0.
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  • 9
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    Wiley-Blackwell
    In:  Journal of Quaternary Science, 25 (5). pp. 633-650.
    Publication Date: 2017-12-19
    Description: Two cores were recovered in the southeastern part of Lake Shkodra (Montenegro and Albania) and sampled for identification of tephra layers. The first core (SK13, 7.8 m long) was recovered from a water depth of 7 m, while the second core (SK19, 5.8 m long) was recovered close to the present-day shoreline (water depth of 2 m). Magnetic susceptibility investigations show generally low values with some peaks that in some cases are related to tephra layers. Naked-eye inspection of the cores allowed the identification of four tephra layers in core SK13 and five tephra layers in core SK19. Major element analyses on glass shards and mineral phases allowed correlation of the tephra layers between the two cores, and their attribution to six different Holocene explosive eruptions of southern Italy volcanoes. Two tephra layers have under-saturated composition of glass shards (foiditic and phonolitic) and were correlated to the AD 472 and the Avellino (ca. 3.9 cal. ka BP) eruptions of Somma-Vesuvius. One tephra layer has benmoreitic composition and was correlated to the FL eruption of Mount Etna (ca. 3.4 cal. ka BP). The other three tephra layers have trachytic composition and were correlated to Astroni (ca. 4.2 cal. ka BP), Agnano Monte Spina (ca. 4.5 cal. ka BP) and Agnano Pomici Principali (ca. 12.3 cal. ka BP) eruptions of Campi Flegrei. The ages of tephra layers are in broad agreement with eight 14C accelerator mass spectrometric measurements carried out on plant remains and charcoal from the lake sediments at different depths along the two cores. The recognition of distal tephra layers from Italian volcanoes allowed the physical link of the Holocene archive of Lake Shkodra to other archives located in the central Mediterranean area and the Balkans (i.e. Lake Ohrid). Five of the recognised tephra layers were recognised for the first time in the Balkans area, and this has relevance for volcanic hazard assessment and for ash dispersal forecasting in case of renewed explosive activity from some of the southern Italy volcanoes. Copyright © 2009 John Wiley & Sons, Ltd.
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  • 10
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    Wiley-Blackwell
    In:  Journal of Quaternary Science, 24 (5). pp. 437-449.
    Publication Date: 2018-05-15
    Description: This paper presents a temperature reconstruction of the past 1000 years for Central Europe, based on chronological records. The advantages and limitations of this hermeneutic, text-based approach are discussed and the statistic methodology is introduced. Historical documents represent direct observation of weather and atmospheric conditions with highest temporal resolution available and precise dating. A major advantage of these extensive data is that they allow the reconstruction of large numbers of variables such as winter temperature, precipitation, pressure patterns or climate extremes as well as floods or storms. Within this hermeneutic climatological research approach, even human impacts and social dimensions of climate development can be examined. In order to quantify the historical information, statistical methods are applied, based on an index approach.
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  • 11
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    Wiley-Blackwell
    In:  Journal of Zoology, 170 (4). pp. 451-462.
    Publication Date: 2020-07-17
    Description: The dry weight and the crest length of the upper and lower beak, the length of the radula ribbon, the average width of the base of the six proximal and distal rachidian teeth as well as the total number of these teeth have all been related to the live body weight of octopuses between 1.1 and 4440 g. From any one of these parameters it is possible to estimate the size and approximate age of the animal.
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  • 12
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    Wiley-Blackwell
    In:  Journal of Zoology, 181 (4). pp. 527-559.
    Publication Date: 2020-07-17
    Description: Features of the brain of this oceanic squid have been investigated and related, as far as possible, to its habits and mode of life. The body and arms are much vacuolated for buoyancy and the animal probably lives with the head upwards. The very long whip-like tentacles are not vacuolated and perhaps hang downwards. They are covered by numerous minute pedunculated suckers, perhaps providing a sticky surface. A special nerve running outside the brain carries signals from the arms and tentacles to the magnocellular lobe, which is very large and of complex structure. However, there are no giant cells and the mantle is weak. Propulsion is mainly by the large fins, which are controlled from the magnocellular lobe, presumably using the information from the arms and tentacles.
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  • 13
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    Wiley-Blackwell
    In:  Journal of Zoology, 223 (3). pp. 499-500.
    Publication Date: 2020-07-17
    Description: Benthoctopus piscatorum appears to be a multiple spawner. In the ovary of one specimen about 50 eggs were found at various stages of development.
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  • 14
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    Wiley-Blackwell
    In:  Marine Ecology, 28 (1). pp. 152-159.
    Publication Date: 2020-07-14
    Description: Meiobenthos densities and higher taxon composition were studied in an active gas seepage area at depths from 182 to 252 m in the submarine Dnieper Canyon located in the northwestern part of the Black Sea. The meiobenthos was represented by Ciliata, Foraminifera, Nematoda, Polychaeta, Bivalvia, Gastropoda, Amphipoda, and Acarina. Also present in the sediment samples were juvenile stages of Copepoda and Cladocera which may be of planktonic origin. Nematoda and Foraminifera were the dominant groups. The abundance of the meiobenthos varied between 2397 and 52,593 ind.·m−2. Maximum densities of Nematoda and Foraminifera were recorded in the upper sediment layer of a permanent H2S zone at depths from 220 to 250 m. This dense concentration of meiobenthos was found in an area where intense methane seeps were covered by methane-oxidizing microbial mats. Results suggest that methane and its microbial oxidation products are the factors responsible for the presence of a highly sulfidic and biologically productive zone characterized by specially adapted benthic groups. At the same time, an inverse correlation was found between meiofauna densities and methane concentrations in the uppermost sediment layers. The hypothesis is that the concentration of Nematoda and Foraminifera within the areas enriched with methane is an ecological compromise between the food requirements of these organisms and their adaptations to the toxic H2S.
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  • 15
    Publication Date: 2020-07-29
    Description: The diet of King Penguins Aptenodytes patagonica at Possession Island was studied in February 1989 by analysis of 20 stomach contents collected from adult birds, just before they fed their single chicks. The mean mass of the samples was 1.84 kg, equivalent to 15% of the unladen adult body-mass. Fish accounted for 99.8% and squids for 0.2% by mass. The main prey were mesopelagic myctophid fish which live in dense shoals and perform a daily vertical migration. Subadults/adults of Electrona carlsbergi and juveniles and subadults/adults of Krefftichthys anderssoni represented 73.7 and 13.4% of the diet by mass, respectively. No difference was found in the diet of male and female King Penguins. Comparison of individual samples suggests that these birds catch a large quantity of fish from only a limited number of shoals. The mean caloric content of the food was 7 kJ/g wet mass. The total energy requirement of each chick during its initial period of growth was estimated to amount to 328,000 kJ, equivalent to 55 kg of food. The rate at which energy was delivered to the chick was calculated to be 50 W during this period.
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  • 16
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    Wiley-Blackwell
    In:  Journal of Zoology, 226 (3). pp. 469-490.
    Publication Date: 2020-07-17
    Description: In Loligo forbesi Steenstrup, the female reproductive system consists of the ovary and accessory reproductive organs which include the oviducal gland, the nidamental gland, the accessory nidamental gland and seminal receptacle. Histological studies were made on the accessory reproductive organs of female L. forbesi. The various changes observed during maturation are described and the functional significance discussed. The secretions produced by the oviducal gland and nidamental gland apparently form the egg coats. The seminal receptacle serves to store spermatozoa after mating. The function of the accessory nidamental gland is unknown.
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  • 17
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    Wiley-Blackwell
    In:  Journal of Zoology, 158 (4). pp. 475-483.
    Publication Date: 2020-07-17
    Description: An automatic food dispenser was designed for use with Octopus vulgaris Lamarck. One live crab was delivered each time the octopus pulled a white shape attached to the dispenser. The apparatus provided a continuous record of the time and frequency of feeding over periods of up to 15 days.
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  • 18
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    Wiley-Blackwell
    In:  Journal of Zoology, 232 (3). pp. 491-504.
    Publication Date: 2020-07-17
    Description: Whether the study of external morphology can increase our knowledge of shallow-water octopuses and their biology is tested by multivariate morphometric analyses. The extent of morphological variation among 20 species from the Atlantic and eastern tropical Pacific Oceans is explored, and four hypotheses are addressed: (1) that octopuses show secondary sexual dimorphism; (2) that remote, ostensibly conspecific populations are morphologically distinct; (3) that morphometric characters contribute to resource partitioning among sympatric species; and (4) that morphology is predictably associated with habitat. Results of principal components analysis show most species to be very similar in shape. Arm length contributes most shape variation; other characters contribute little. Principal components and size-free discriminant analyses refute each of the hypotheses considered. The morphological similarity of isolated Atlantic populations may be a symplesiomorphy, but information on the planktonic phase of the octopus lire cycle supports the possibility of dispersal across the Atlantic Ocean. Size, not directly treated here, may significantly affect some aspects of octopus biology. Increased female size may evolve due to selection for increased fecundity and intraspecific niche partitioning. Size may also indicate interaction within and among species. Characters of shape, deemed essential to species descriptions, do not appear to be able to identify most specimens, nor to increase our understanding of octopus biology.
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  • 19
    Publication Date: 2017-12-19
    Description: This paper presents an event stratigraphy based on data documenting the history of vegetation cover, lake-level changes and fire frequency, as well as volcanic eruptions, over the Last Glacial–early Holocene transition from a terrestrial sediment sequence recovered at Lake Accesa in Tuscany (north-central Italy). On the basis of an age–depth model inferred from 13 radiocarbon dates and six tephra horizons, the Oldest Dryas–Bølling warming event was dated to ca. 14 560 cal. yr BP and the Younger Dryas event to ca. 12 700–11 650 cal. yr BP. Four sub-millennial scale cooling phases were recognised from pollen data at ca. 14 300–14 200, 13 900–13 700, 13 400–13 100 and 11 350–11 150 cal. yr BP. The last three may be Mediterranean equivalents to the Older Dryas (GI-1d), Intra-Allerød (GI-1b) and Preboreal Oscillation (PBO) cooling events defined from the GRIP ice-core and indicate strong climatic linkages between the North Atlantic and Mediterranean areas during the last Termination. The first may correspond to Intra-Bølling cold oscillations registered by various palaeoclimatic records in the North Atlantic region. The lake-level record shows that the sub-millennial scale climatic oscillations which punctuated the last deglaciation were associated in central Italy with different successive patterns of hydrological changes from the Bølling warming to the 8.2 ka cold reversal. Copyright © 2006 John Wiley & Sons, Ltd.
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  • 20
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    Wiley-Blackwell
    In:  Journal of Zoology, 221 (3). pp. 359-374.
    Publication Date: 2020-07-17
    Description: The stomach contents of 1522 adult seals (Arctocephalus pusillus pusillus) and 673 pups, which were collected around the West and South Coasts of Southern Africa, were examined and cephalopod prey identified. About 20 cephalopod species (some identifications were uncertain) were found in the stomachs, of which only six were significant: Loligo vulgaris reynaudii. Sepia spp., Octopus sp., Todaropsis eblanae, Todarodes angolensis and Ocythoe tuberculata. This list suggests that A. pusillus feeds exclusively on the continental shelf, frequently on or near the bottom. Among adults, cephalopod prey varied in importance around the coast. It was most important on the South Coast of South Africa where it comprised 35.0% of the weight of all prey, of which L. v. veynaudii constituted about 88%. On the West Coast cephalopods comprised about 26.6% by weight of all prey, and Octopus sp. predominated, whereas in Namibian waters cephalopods were least important, constituting only 3.4% by weight of all prey, with Todarodes angolensis and Octopus sp. being most significant. Among pups (aged 8–10 months) in the Lüderitz (Namibia) area, cephalopods were about 16.9% of prey by weight, of which Ocythoe tuberculata, small Sepia spp. and Octopoda were most important.
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  • 21
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    Wiley-Blackwell
    In:  Journal of Zoology, 188 (1). pp. 53-67.
    Publication Date: 2020-07-17
    Description: The movements of the isolated buccal mass of Octopus vulgaris have been investigated. The beaks undergo rhythmic cycles of activity in the absence of applied stimulation and after electrical stimulation of the inter-buccal connective. Initial opening, closing, retraction and re-opening phases of movement are described. This cycle of movements is taken to resemble those in the intact animal. Anatomical and electrical evidence identifies the superior mandibular muscle as being partly responsible for the closing and retraction phases of movement. The inferior buccal ganglion determines the sequence of these buccal movements, but modification by sensory feed-back from the musculature is also implied. The preparation will allow a closer comparison of the control of movement in cephalopods and gastropods.
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  • 22
    Publication Date: 2020-07-17
    Description: The structure of the reproductive systems of mature males and females of the nektonic, oceanic squid Thysanoteuthis rhombus are described. The main peculiarities of the female system are relatively low capacity oviducts, set in a tight spiral, and hypertrophically developed oviducal glands with a very large second section. The male reproductive system is characterized by a long, narrow Needham's sac containing 10–15 large spermatophores 80–100 mm in length. The mesentery supporting the gonad, and protruding into it dorsally, is a characteristic feature in both sexes. The hectocotylus structure differs markedly from that in other squids and resembles that of sepiids. The reproductive system of T. rhombus possesses primitive features (pattern of gonad attachment and hectocotylus) but mostly secondary characters (small oviducts, very large oviducal glands and ovary). The complex morpho-ecological adaptations of T. rhombus are reflected in the distinctive features of the reproductive system.
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  • 23
    Publication Date: 2020-07-17
    Description: Seasonal variation in the diet of common seals (Phoca vitulina) in the Moray Firth, north-east Scotland, was determined from analysis of faecal samples collected at haul-out sites during each month of 1988. Data on diet of common seals in 1987 are also presented. Limitations of the methods available for quantification of diet are discussed. Although some of the observed variation in diet from month to month may reflect changes in the sampling regime, a clear seasonal pattern was apparent, with clupeids predominating in the winter and sandeels in the summer. The trends observed are consistent with opportunistic feeding on the most abundant Prey.
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  • 24
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    Wiley-Blackwell
    In:  Journal of Zoology, 224 (2). pp. 320-328.
    Publication Date: 2020-07-17
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  • 25
    Publication Date: 2020-07-17
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  • 26
    Publication Date: 2020-07-17
    Description: The cephalopod fauna collected during six surveys carried out in the bathyal basin of the north-western Mediterranean is discussed. Samples were taken at depths mainly between 1000 and 2000 m. Ten species were identified. Bathypolypus sponsalis and Neorossia caroli were the commonest species. Small individuals of both these species occurred at greater depths than did larger individuals, suggesting up-slope ontogenetic migration. The depth ranges recorded for all species collected are discussed and compared to the results of previous studies found in the literature.
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  • 27
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    Wiley-Blackwell
    In:  Journal of Zoology, 179 (1). pp. 19-83.
    Publication Date: 2020-07-17
    Description: Taonius megalops is a neutrally buoyant oceanic squid, very different in form when young and old. The young, has a round, sac-like mantle and relatively long tentacles, while the adult has an elongated cone-like mantle and relatively short tentacles. The transition in shape and form is gradual and has been followed in animals of between 3 and 180 mm dorsal mantle length. Statistical tests on various parameters investigated, both external and internal, revealed good correlation with the dorsal mantle length and confirmed the descriptions of the development of the chromatophores and subocular light organs with growth. It was concluded that these animals, captured in the Atlantic Ocean, all belonged to the species T. megalops Prosch 1849. This study has permitted us to suggest a tentative outline of the life cycle, although no adults were present in the material available.
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  • 28
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    In:  Journal of Zoology, 202 (3). pp. 441-447.
    Publication Date: 2020-07-17
    Description: A crab which has been captured and paralysed by an octopus but retrieved 1 1/2 min later cannot at first be pulled apart by the experimenter: 27 min later it can be dismembered easily. This demonstrates that there is external digestion when Octopus vulgaris feeds upon crabs. However, it is strictly limited at this stage to the arthrodial membrane and the musculo-skeletal attachment mechanisms as the exoskeleton separates at the joints allowing the muscles to be drawn out of the appendages. And yet, two hours after capture, pieces of crab meat are still recognizable in the octopus's stomach. The process of paralysing and cleaning a crab was noticeably slowed after the surgical removal of the radula, salivary papilla or the lateral buccal palps.
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  • 29
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    In:  Journal of Zoology, 150 (1). pp. 1-9.
    Publication Date: 2020-07-17
    Description: The changes in body weight of 12 octopuses, fed on fish or crabs, were followed under laboratory conditions for periods of 1 to 7 1/2 months. The food intake was estimated and compared with the changes in body weight of the octopuses; 25 to 55% of the total intake of food appeared to be incorporated. The range of the average increase in weight over the whole observation period of each of the animals was 1.9 to 7.7g per day (1 to 7 1/2 months); the mean value was 4.8g per day. The effect of changing the diet of small octopuses (fish or crab)was followed for four weeks but there was no evidence that alteration of the diet affected the rate of changes in body weight of animals of more than 47g initial body weight.
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  • 30
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    In:  Magnetic Resonance in Chemistry, 45 (12). pp. 1072-1075.
    Publication Date: 2020-07-15
    Description: Diosmetin, 5,7,3′-trihydroxy-4′-methoxyflavone shows chemopreventive, antimutagenic, and antiallergic effects. On the other hand, chrysoeriol, 5,7,4′-trihydroxy-3′-methoxyflavone induced nodABC-lacZ in Rhizobium meliloti. Both of them belong to hydroxymethoxy- flavones. One major difference between diosmetin and chrysoeriol is the substituted position of hydroxyl and methoxyl groups. In order to elucidate the relationships between their structures and activity, one of the first things to be done is the determination of their structures. However, most flavones occur widely in nature, and thus it is difficult to obtain in sufficient amounts from natural sources to identify their structures. Assignments of NMR data of several hydroxymethoxyflavones may help us to identify novel flavonoid compounds isolated from natural sources based on their NMR experiments. Therefore, we report here the complete assignments of 1H and 13C NMR data of 13 hydroxymethoxyflavones.
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  • 31
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    In:  Journal of Zoology, 186 (1). pp. 95-108.
    Publication Date: 2020-07-17
    Description: Reproductive mechanisms in the seven species of the thecosomatous pteropod genus Limacina are described and compared. All species are protandrous hermaphrodites. Five species–L. bulimoides, L. helicina, L. lesueuri, L. retroversa and L. trochiformis–have a similar reproductive anatomy in which the gonoduct leading from the gonad to the common genital pore functions as a seminal vesicle in the male and is elaborated into mucous and albumen glands in the female. The male system consists of a prostate gland and penis connected to the common genital pore by an external ciliary tract. All five species have a free-swimming veliger stage which hatches from free-floating egg masses. Limacina helicoides has the same reproductive anatomy but is ovoviviparous, with embryos retained in capsules in the mucous gland until they are juveniles of 50 mm in shell diameter. Limacina inflata lacks mucous and albumen glands and a penis; a spermatophore formed by the prostate gland is used in aphallic sperm transfer. This species exhibits brood protection with un-encapsulated embryos retained in the mantle cavity until they are released as veligers measuring 0067 mm in diameter. L. inflata is the most abundant of the seven species despite lowered fecundity; reasons for its ecological success are discussed.
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  • 32
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    In:  In: Biofouling. , ed. by Dürr, S. and Thomason, J. Wiley-Blackwell, Weinheim, pp. 73-86. ISBN 978-1-4051-6926-4
    Publication Date: 2012-02-23
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  • 33
    Publication Date: 2015-08-31
    Description: The Stilbonemutinue (marine free-living nematodes) arc remarkable for cctosymbiotic bacteria, which cover the greatest part of their body in a highly ordered and species specific pattern. Using SEM we describe the main types of symbiotic cover and give evidence for the role of the bacteria in the nutrition of their host on the basis of stable carbon isotope ratios. In experimental systems the worms migrated repeatedly across a sulfide gradient during 12 h when sulfide concentrations were low, but stayed above the sulfide maximum at high concentrations. The migration across the chemocline exposes the symbionts alternately to reduced sulfur compounds and oxygen; this constitutes an alternative strategy to the ventilation/circulation systems in symbiotic macrofauna from sulfidic habitats
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  • 34
    Publication Date: 2020-07-24
    Description: Myrionecta rubra, a ubiquitous planktonic ciliate, has received much attention due to its wide distribution, occurrence as a red tide organism, and unusual cryptophyte endosymbiont. Although well studied in coastal waters, M. rubra is poorly examined in the open ocean. In the Irminger Basin, North Atlantic, the abundance of M. rubra was 0–5 cells/ml, which is low compared with that found in coastal areas. Distinct patchiness (100 km) was revealed by geostatistical analysis. Multiple regression indicated there was little relationship between M. rubra abundance and a number of environmental factors, with the exception of temperature and phytoplankton biomass, which influenced abundance in the spring. We also improve on studies that indicate distinct size classes of M. rubra; we statistically recognise four significantly distinct width classes (5–16, 12–23, 18–27, 21–33 μm), which decrease in abundance with increasing size. A multinomial logistic regression revealed the main variable correlated with this size distribution was ambient nitrate concentration. Finally, we propose a hypothesis for the distribution of sizes, involving nutrients, feeding, and dividing of the endosymbiont.
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  • 35
    Publication Date: 2015-10-06
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  • 36
    Publication Date: 2020-07-27
    Description: Understanding the influence of growth temperature and carbon dioxide (CO2) on seed quality in terms of seed composition, subsequent seedling emergence and early seedling vigour is important under present and future climates. The objective of this study was to determine the combined effects of elevated temperature and CO2 during seed-filling of parent plants on seed composition, subsequent seedling emergence and seedling vigour of red kidney bean (Phaseolus vulgaris). Plants of cultivar ‘Montcalm’, were grown at daytime maximum/nighttime minimum sinusoidal temperature regimes of 28/18 and 34/24 °C at ambient CO2 (350 μmol mol−1) and at elevated CO2 (700 μmol mol−1) from emergence to maturity. Seed size and seed composition at maturity and subsequent per cent emergence, early seedling vigour (rate of development) and seedling dry matter production were measured. Elevated CO2 did not influence seed composition, emergence, or seedling vigour of seeds produced either at 28/18 or 34/24 °C. Seed produced at 34/24 °C had smaller seed size, decreased glucose concentration, but significantly increased concentrations of sucrose and raffinose compared to 28/18 °C. Elevated growth temperatures during seed production decreased the subsequent per cent emergence and seedling vigour of the seeds and seedling dry matter production of seed produced either at ambient or elevated CO2.
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  • 37
    Publication Date: 2015-09-01
    Description: Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a high spatial resolution analytical method which has been applied to the analysis of silicic tephras. With current instrumentation, around 30 trace elements can be determined from single glass shards as small as ∼ 40 µm, separated from tephra deposits. As a result of element fractionation during the ablation process using a 266 nm laser, a relatively complex calibration strategy is required. Nonetheless, such a strategy gives analyses which are accurate (typically within ±5%) and have an analytical precision which varies from ∼ ±2% at 100 ppm, to ∼ ±15% at 1 ppm. Detection limits for elements used in correlation and discrimination studies are well below 1 ppm. Examples of the application of trace element analysis by LA-ICP-MS in tephra studies are presented from the USA, New Zealand and the Mediterranean. Improvements in instrumental sensitivity in recent years have the potential to lower detection limits and improve analytical precision, thus allowing the analysis of smaller glass shards from more distal tephras. Laser systems operating at shorter wavelengths (e.g. 193 nm) are now more widely available, and produce a much more controllable ablation in glasses than 266 nm lasers. Crater sizes of 〈10 µm are easily achieved, and at 193 nm many of the elemental fractionation issues which mar longer wavelengths are overcome. By coupling a short wavelength laser to a modern ICP-MS it should be possible to determine the trace element composition of glass shards as small as 20 µm and, providing sample preparation issues can be overcome, the determination of the more abundant trace elements in glass shards as small as 10 µm is within instrumental capabilities. This will make it possible to chemically fingerprint tephra deposits which are far from their sources, and will greatly extend the range over which geochemical correlation of tephras can be undertaken.
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  • 38
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    In:  Journal of Fish Biology, 75 (5). pp. 960-996.
    Publication Date: 2015-09-14
    Description: Absolute barriers to dispersal are not common in marine systems, and the prevalence of planktonic larvae in marine taxa provides potential for gene flow across large geographic distances. These observations raise the fundamental question in marine evolutionary biology as to whether geographic and oceanographic barriers alone can account for the high levels of species diversity observed in marine environments such as coral reefs, or whether marine speciation also operates in the presence of gene flow between diverging populations. In this respect, the ecological hypothesis of speciation, in which reproductive isolation results from divergent or disruptive natural selection, is of particular interest because it may operate in the presence of gene flow. Although important insights into the process of ecological speciation in aquatic environments have been provided by the study of freshwater fishes, comparatively little is known about the possibility of ecological speciation in marine teleosts. In this study, the evidence consistent with different aspects of the ecological hypothesis of speciation is evaluated in marine fishes. Molecular approaches have played a critical role in the development of speciation hypotheses in marine fishes, with a role of ecology suggested by the occurrence of sister clades separated by ecological factors, rapid cladogenesis or the persistence of genetically and ecologically differentiated species in the presence of gene flow. Yet, ecological speciation research in marine fishes is still largely at an exploratory stage. Cases where the major ingredients of ecological speciation, namely a source of natural divergent or disruptive selection, a mechanism of reproductive isolation and a link between the two have been explicitly documented are few. Even in these cases, specific predictions of the ecological hypothesis of speciation remain largely untested. Recent developments in the study of freshwater fishes illustrate the potential for molecular approaches to address specific questions related to the ecological hypothesis of speciation such as the nature of the genes underlying key ecological traits, the magnitude of their effect on phenotype and the mechanisms underlying their differential expression in different ecological contexts. The potential provided by molecular studies is fully realized when they are complemented with alternative (e.g. ecological, theoretical) approaches.
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  • 39
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    In:  Marine Ecology, 14 (4). pp. 329-340.
    Publication Date: 2016-02-04
    Description: Growth of the shallow-water gorgonian Lophogorgia ceratophyta was investigated in an infralittoral station located in La Spezia Gulf, Ligurian Sea. Mean annual height growth rate was estimated to be 2.57 cm · a-1. The fractal dimension of the colonies was found to gradually evolve in complexity, exhibiting a simpler branching pattern in younger specimens. The maintenance of a low, invariable ramification complexity as an optimal choice in managing relationships between water and the colony's living tissues is also discussed.
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  • 40
    Publication Date: 2020-04-28
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  • 41
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    In:  Geofluids, 6 . pp. 241-250. Date online first: 2006
    Publication Date: 2017-08-02
    Description: Groundwater seeps are known to occur in Eckernförde Bay, Baltic Sea. Their discharge rate and dispersion were investigated with a new schlieren technique application, which is able to visualize heterogeneous water parcels with density anomalies down to Drt ¼ 0.049 on the scale of millimeters. With the use of an inverted funnel, discharged fluids can be captured and the outflow velocity can be determined. Overall, 46 stations could be categorized by three different cases: active vent sites, seep-influenced sites, and non-seep sites. New seep locations were discovered, even at shallow near-shore sites, lacking prominent sediment depression, which indicate submarine springs. The detection of numerous seeps was possible and the groundwater-influenced area was defined to be approximately 6.3 km2. Flow rates of between 0.05 and 0.71 l m)2 min)1 were measured. A single focused fluid plume, which was not disturbed by the funnel was recorded and revealed a flux of 59.6 ± 20 ml cm)2 min)1 and it was calculated that this single focused plume would be strong enough to produce a flow rate through the funnel of 1.32 ± 0.44 l m)2 min)1. The effect of different seep-meter funnel sizes is discussed.
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  • 42
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    In:  In: Biofouling. , ed. by Dürr, S. and Thomason, J. Wiley-Blackwell, Weinheim, pp. 100-108. ISBN 978-1-4051-6926-4
    Publication Date: 2012-02-23
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  • 43
    Publication Date: 2017-01-31
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  • 44
    Publication Date: 2016-06-29
    Description: Quantitative X-ray diffraction analysis of the 〈2mm sediment fraction was carried out on 1257 samples (from the seafloor and 16 cores) from the Iceland shelf west of 188 W. All but one core (B997-347PC) were from transects along troughs on theNW to N-central shelf, an area that in modern and historic times has been affected by drift ice. The paper focuses on the non-clay mineralogy of the sediments (excluding calcite and volcanic glass). Quartz and potassium feldspars occupy similar positions in an R-mode principal component analysis, and oligoclase feldspar tracks quartz; these minerals are used as a proxy for ice-rafted detritus (IRD). Accordingly, the sum of these largely foreign minerals (Q&K) (to Icelandic bedrock) is used as a proxy for drift ice. A stacked, equi-spaced 100 a record is developed which shows both low-frequency trends and higher-frequency events. The detrended stacked record compares well with the flux of quartz (mg cm-2 a-1) at MD99-2269 off N Iceland. The multi-taper method indicated that there are three significant frequencies at the 95% confidence level with periods of ca. 2500, 445 and 304 a. Regime shift analysis pinpoints intervals when there was a statistically significant shift in the average Q&K weight %, and identifies four IRDrich events separated by intervals with lower inputs. There is some association between peaks of IRD input, less dense surface waters (from d18O data on planktonic foraminifera) and intervals of moraine building.
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  • 45
    Publication Date: 2017-09-14
    Description: An experimental study was performed to disentangle parental and environmental effects on the growth of Atlantic cod Gadus morhua larvae and juveniles. Eggs were collected during the spawning season from spawning pairs (families) kept separately in specially designed spawning compartments. Newly hatched larvae were released simultaneously into two mesocosms of 2500 and 4400 m3. Larval growth was monitored by sampling over a 10 week period, after which juveniles were transferred to on-growing tanks, where they were tagged and kept for up to 2 years. Maternal origin was determined by individual microsatellite genotyping of the larvae (n = 3949, 24 families) and juveniles (n = 600). The results showed significant positive correlations between egg size and larval size during the whole mesocosm period. Correlations, however, weakened with time and were no longer significant at the first tank-rearing sampling at an age of 9 months. Significant family-specific differences in growth were observed. The coefficient of variation (c.v.) was calculated in order to examine variation in standard length of larvae during the mesocosm period. Inter-family c.v. was on average 69% of intra-family c.v. Differences in zooplankton densities between the two mesocosms were reflected in larval growth, condition factor and c.v. Low food abundance appeared to reduce c.v. and favour growth of larvae that showed relatively slow growth at high food abundance. It is suggested that genetically determined variation in growth potential is maintained by environmental variability.
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  • 46
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    In:  Marine Ecology, 14 . pp. 67-79.
    Publication Date: 2017-10-05
    Description: To study the impact of the gradient of primary production between the southern, central, and northern Red Sea, benthic metabolism and standing stocks were investigated in the axial trough between 17°N and 27°N. Data on sediment chloroplastic pigments, macrofauna and meiofauna abundance, particulate adenylate, protein and carbohydrate biomass, as well as electron transport activity of the sediment community give evidence for an enhanced benthic standing stock and activity in the southern Red Sea south of 18°N; this is related to the increased primary productivity in the area south 16°N. Despite a large primary production only small benthic standing stocks were found in all areas investigated; they are much smaller than in other parts of the world's deep oceans with comparable primary production. The low benthic biomass is caused by two factors: a large proportion of particulate organic carbon is remineralized in the water column, while only a relatively small amount sediments to the sea floor; nearly all sedimented particulate organic matter is respired by the benthic community of the deep Red Sea and only a minute proportion is used for the production of benthic biomass.
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  • 47
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    In:  International Journal of Climatology, 29 (12). pp. 1731-1744.
    Publication Date: 2020-03-19
    Description: The annual cycle of extreme 1-day precipitation events across the UK is investigated by developing a statistical model and fitting it to data from 689 rain gauges. A generalized extreme-value distribution (GEV) is fit to the time series of monthly maxima, across all months of the year simultaneously, by approximating the annual cycles of the location and scale parameters by harmonic functions, while keeping the shape parameter constant throughout the year. We average the shape parameter of neighbouring rain gauges to decrease parameter uncertainties, and also interpolate values of all model parameters to give complete coverage of the UK. The model reveals distinct spatial patterns for the estimated parameters. The annual mean of the location and scale parameter is highly correlated with orography. The annual cycle of the location parameter is strong in the northwest UK (peaking in late autumn or winter) and in East Anglia (where it peaks in late summer), and low in the Midlands. The annual cycle of the scale parameter exhibits a similar pattern with strongest amplitudes in East Anglia. The spatial patterns of the annual cycle phase suggest that they are linked to the dominance of frontal precipitation for generating extreme precipitation in the west and convective precipitation in the southeast of the UK. The shape parameter shows a gradient from positive values in the east to negative values in some areas of the west. We also estimate 10-year and 100-year return levels at each rain gauge, and interpolated across the UK.
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  • 48
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    In:  Lethaia, 24 (2). pp. 191-198.
    Publication Date: 2020-07-15
    Description: The presence of several typically northern hemisphere foraminiferal species in the upper Miocene and Recent deposits of the Río de la Plata, Paraná river and adjacent areas, and their absence along the Brazilian coast strongly suggests that in the late Miocene the Caribbean and the Southern Atlantic were linked by a marine connection. This connection was first envisioned by H. von Ihering, who called it the ‘Arm of the Tethys’. It was represented by a very broad strait which ran meridionally across the South American continent. In the Pliocene it shrank considerably and its salinity was lowered by Andean river runoff. At the end of the Pliocene - beginning of the Pleistocene it gave rise to the Paraná river, a series of brackish water lakes and lagoons, and the Río de la Plata. □Foraminifera, arm of the Tethys, South America.
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  • 49
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    In:  Journal of Zoology, 210 (1). pp. 137-147.
    Publication Date: 2020-07-17
    Description: Epipelagic pterotracheid heteropods and young cranchiid squids rely primarily on transparency for concealment; yet they have opaque structures, the eyes and visceral organs that compose the visceral nuclei, which can only be camouflaged in other ways. These two groups have achieved convergent solutions to this problem. The visceral nucleus has a narrow and conical shape and a covering layer of iridophores that lies parallel to the surface of the organ. The eyes also have iridophore layers and tapered shapes. A minimal ventral silhouette results when the long axes of the visceral nucleus and eyes are oriented vertically, with the narrowest ends directed downward. In pterotracheids, this is actively achieved by tilting the nucleus and eyes and flexing the body and proboscis. In cranchiids, tilting of the organs alone suffices and adjustments are accomplished much more rapidly than in the pterotracheids.
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  • 50
    Publication Date: 2016-07-28
    Description: Coccoliths were studied from the ODP Hole 1002C and core PL07-39PC in the Cariaco Basin. Increases in Emiliania huxleyi are synchronous with decreases of Gephyrocapsa oceanica and vice versa. A new index (GEX) based on the relative abundances of these two taxa is proposed, and correlates with various other proxies. It is shown that GEX can serve as upwelling proxy. This confirms that the Intertropical Convergence Zone shifted north during the Bølling/Allerød, south during the Younger Dryas and back north during the Preboreal. The upwelling proxy shows few discrepancies with the terrigenous record.
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  • 51
    Publication Date: 2016-05-27
    Description: A visible tephra horizon in the NGRIP ice core has been identified by geochemical analysis as the Fugloyarbanki Tephra, a widespread marker horizon in marine cores from the Faroe Islands area and the northern North Atlantic. An age of 26 740 ± 390 yr b2k (1s uncertainty) is derived for this tephra according to the new Greenland Ice Core Chronology (GICC05) based on multiparameter counting of annual layers. Detection of this tephra for the first time within the NGRIP ice core provides a key tie-point between marine and ice-core records during the transition between MIS 3 and 2. Identification of this volcanic event within the Greenland records demonstrates the future potential of using tephrochronology to precisely correlate palaeoarchives in widely separated localities that span the last glacial period, as well as providing a potential method for examining the extent of the radiocarbon marine reservoir effect at this time.
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  • 52
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    In:  Journal of Zoology, 207 (4). pp. 511-519.
    Publication Date: 2020-07-17
    Description: A study of the diet of Sepia officinalis and S. elegans in the Ria de Vigo has shown that crustaceans are the most abundant prey in both species, followed by fish. Changes in the food composition of both species occur with growth. The type of prey eaten by the two sexes of these species is very similar. The possibility of trophic competition between juveniles of S. qficinalis and S. elegans is discussed.
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  • 53
    Publication Date: 2017-10-05
    Description: Natural communities are constantly changing due to a variety of interacting external processes and the temporal occurrence and intensity of these processes can have important implications for the diversity and structure of marine sessile assemblages. In this study, we investigated the effects of temporal variation in a disturbance regime, as well as the specific timing of events within different regimes, on the composition and diversity of marine subtidal fouling assemblages. We did this in a multi-factorial experiment using artificial settlement tiles deployed at two sites on the North East coast of England. We found that although there were significant effects of disturbances on the composition of assemblages, there were no effects of either the variation in the disturbance regime or the specific timing of events on the diversity or assemblage composition at either site. In contrast to recent implications we conclude that in marine fouling assemblages, the variability in disturbance regimes (as a driving force) is unimportant, while disturbance itself is an important force for structuring robust ecosystems.
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  • 54
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    In:  In: Microbial Ecology of the Oceans. Wiley-Blackwell, Hoboken, NJ, pp. 383-441. 2. Edition ISBN 978-0-470-04344-8
    Publication Date: 2019-12-06
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  • 55
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    In:  Fish and Fisheries, 9 (4). pp. 450-461.
    Publication Date: 2016-12-13
    Description: Archived scales and otoliths constitute a unique source of DNA that potentially enables extension of the temporal scale of genetic studies of fish populations by decades and even centuries. We review recent insights into fish population and conservation genetics obtained using analysis of DNA from archived samples. This involves both new knowledge about demographic parameters and population structure in wild populations and insights into consequences of anthropogenic pressure resulting from over-harvesting, habitat degradation and stocking. We show that the latter category of studies have led to significant changes of management practices. Ongoing improvement of genetic methods will undoubtedly further expand the ability to utilize historical DNA samples. We envisage that temporal comparisons of large numbers of coding genes will lead to novel insights into selective responses of fish populations to anthropogenic challenges, particularly fisheries-induced selection and global warming. However, both acquisition and storage of historical DNA samples can be hurdles to temporal genetic analyses, while degradation and low copy number in historical DNA samples render genetic data from such sources prone to technical artefacts. We summarize recommendations for storage of samples and DNA extraction and provide checklists for validation of genotyping results. Finally, we stress that validation procedures also involve documentation of the time and population of origin of historical samples, and the inferences drawn should account for the technical and statistical uncertainties associated with historical DNA analysis.
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  • 56
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    In:  Journal of Quaternary Science, 21 (6). pp. 645-675.
    Publication Date: 2018-10-22
    Description: Intra‐plate volcanism in western Europe shows statistically significant episodicity during the Quaternary period. By comparing the known ages for eruptions in France and Germany, which are compiled here, with a composite oxygen isotope record, we have investigated the link between this episodic volcanism and the climate record over the last two million years. We show that increased volcanism between 415–400 ka and 17–5 ka correlates with warming phases at the end of the last Weichselian (Devensian) and earlier Elsterian (Anglian) glacial stages. The three significant caldera explosions in the eastern Eifel, Germany, are all associated with warming phases at the onset of interglacials. The growth and decay of nearby ice sheets suggest that surface changes in continental mass distribution during glacial Milankovich cycles could provide a mechanism for this correlation by means of the distal effects of flexural loading on the lithosphere.
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  • 57
    Publication Date: 2017-09-14
    Description: An analysis of mass (M) and standard length (LS) data for larval, juvenile and adult sprat (Sprattus sprattus; Clupeidae) revealed marked changes in the allometric scaling factor (b in inline image). For sprat 〈44 mm LS, b was 5·0, whereas in larger juveniles and adults, b was c. 3·4 indicating a relatively protracted metamorphic period for this species.
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  • 58
    Publication Date: 2019-09-11
    Description: To investigate and disentangle the role of major histocompatibility complex (MHC)‐based ‘good genes' and ‘compatible genes' in mate choice, three‐spined sticklebacks Gasterosteus aculeatus with specific MHC IIB genotypes were allowed to reproduce in an outdoor enclosure system. Here, fish were protected from predators but encountered their natural parasites. Mate choice for an intermediate genetic distance between parental MHC genotypes was observed, which would result in intermediate diversity in the offspring, but no mate choice based on good genes was found under the current semi‐natural conditions. Investigation of immunological variables revealed that the less‐specific innate immune system was more active in individuals with a genetically more divergent MHC allele repertoire. This suggests the need to compensate for an MHC‐diminished T‐cell repertoire and potentially explains the observed mate choice for intermediate MHC genetic distance. The present findings support a general pattern of mate choice for intermediate MHC diversity (i.e. compatible genes). In addition, the potentially dynamic role of MHC good genes in mate choice under different parasite pressures is discussed in the light of present and previous results.
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  • 59
    facet.materialart.
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    Wiley-Blackwell
    In:  Journal of Fish Biology, 75 . pp. 290-294.
    Publication Date: 2017-09-14
    Description: Individual behaviour of Atlantic cod Gadus morhua in the presence of hypoxic water was measured in situ in the vertically stratified Bornholm Basin of the Baltic Sea. Considering all recaptured individuals, the use of hypoxic habitat was comparable to data derived by traditional survey data, but some G. morhua had migrated towards the centre of the c.100 m deep basin and spent about a third of their time at oxygen saturation 〈50%, possibly to forage on zoobenthos. Maximal residence time per visit in such hypoxic water was limited to a few hours, allowing for the digestion of consumed prey items in waters with sufficient dissolved oxygen.
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  • 60
    facet.materialart.
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    Wiley-Blackwell
    In:  Journal of Fish Biology, 67 . pp. 1585-1602.
    Publication Date: 2017-09-14
    Description: The seasonal growth trajectories of wild Atlantic salmon Salmo salar juveniles by age group within the Margaree River, Canada, are described. Circuli counts from scales were used to infer growth rates at different ages and these were used to predict the proportions of age 2‐ and 3‐year old smolts from different portions of the watershed. In the wild Atlantic salmon juveniles from the Margaree River, there was no bimodality in fork length frequencies and no 1 year old smolts were produced. Water temperature differences during the growing season were insufficient to explain the differences in growth rates and size at age among the sites sampled. There was a positive association between the growth rate in the first year and the subsequent age at smoltification. In the Margaree River, differences in tributary specific growth rates and size at age were expected to produce important differences in the relative ages at smoltification.
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  • 61
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    Wiley-Blackwell
    In:  Oikos, 117 (5). pp. 754-762.
    Publication Date: 2019-09-23
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  • 62
    Publication Date: 2020-03-20
    Description: Speciation and the maintenance of recently diverged species has been subject of intense research in evolutionary biology for decades. Although the concept of ecological speciation has been accepted, its mechanisms and genetic bases are still under investigation. Here, we present a mechanism for speciation that is orchestrated and strengthened by parasite communities acting on polymorphic genes of the immune system. In vertebrates, these genes have a pleiotropic role with regard to parasite resistance and mate choice. In contrasting niches, parasite communities differ and thus the pools of alleles of the adapted major histocompatibility complex (MHC) also differ between niches. Mate choice for the best‐adapted MHC genotype will favour local adaptations and will accelerate separation of both populations: thus immune genes act as pleiotropic speciation genes –‘magic traits’. This mechanism should operate not only in sympatric populations but also under allopatry or parapatry. Each individual has a small subset of the many MHC alleles present in the population. If all individuals could have all MHC alleles from the pool, MHC‐based adaptation is neither necessary nor possible. However, the typically small optimal individual number of MHC loci thus enables MHC‐based speciation. Furthermore, we propose a new mechanism selecting against species hybrids. Hybrids are expected to have super‐optimal individual MHC diversity and should therefore suffer more from parasites in all habitats.
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  • 63
    Publication Date: 2017-01-31
    Description: Human activities have differentially altered biogeochemical cycling at local, regional and global scales. We propose that a stoichiometric approach, examining the fluxes of multiple elements and the ratio between them, may be a useful tool for better understanding human effects on ecosystem processes and services. The different scale of impacts of the elements carbon, nitrogen and phosphorus and the different nature of their biogeochemical cycles, imply a large variation of their stoichiometric ratios in space and time and thus divergent impacts on biota. In this paper, we examine the effects of anthropogenic perturbations on nutrient ratios in ecosystems in two examples and one case study. Altered stoichiometry in agricultural systems (example 1) can affect not only crop yield and quality but also the interactions between plants and their pollinators, pests and pathogens. Human activities have also altered stoichiometry in coastal ecosystems (example 2). Increased N loading has especially lead to increased N:P and reduced Si:N ratios, with detrimental effects on ecosystem services derived from coastal pelagic food webs, such as fish yield and water quality. The terrestrial–aquatic linkage in stoichiometric alterations is illustrated with a case study, the Mississippi River watershed, where anthropogenic activities have caused stoichiometric changes that have propagated through the watershed into the northern Gulf of Mexico. Coupled with altered stoichiometric nutrient inputs are the inherent differences in variation and sensitivity of different ecosystems to anthropogenic disturbance. Furthermore, the connections among the components of a watershed may result in downstream cascades of disrupted functioning. Applying a multiple element perspective to understanding and addressing societal needs is a new direction for both ecological stoichiometry and sustainability.
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  • 64
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    Wiley-Blackwell
    In:  Journal of Zoology , 234 . pp. 189-201.
    Publication Date: 2020-11-09
    Description: Maturation in the onychoteuthid squid Moroteuthis ingens was found to be irreversible, with death following shortly after sexual maturation and spawning. Both males and females were found with spent gonads. The ovary reaches very large sizes in mature females and probably prevends feeding by constricting the caecum. There was also a marked difference in the tissue with an inelastic, gelantinous appearence. Histological examination of the mantle wall revealed that the tissue breakdown was due to a drastic histolysis of muscle tissue and, to a lesser extent, collagen fibres. Mature males also showed some tissue breakdown and loss of muscle fibres but this was not as dramatic as in the females. These features are considered in relation to processes contributing to terminal maturation in M. ingens.
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  • 65
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 107-116 
    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: Zur Beschreibung der Polymerisationsgeschwindigkeit der radikalischen Fallungspolymerisation von Acrylsäure in Toluol wurde ein Modell entewickelt. Die experimentelle Überprüfung des Modells erfolgte durch Messungen in einem isotherm betriebenen Reaktionskalorimeter. Das Modell beschreibt die Polymerisationsgeschwindigkeit bis zum vollständigen Umsatz in einem Temperaturbereich von 40 bis 60°C.
    Notes: A kinetic model for the free-radical precipitation polymerization of acrylic acid in toluene was developed and verified experimentally by using an isothermal reaction calorimeter. The model predicts the rate of polymerization accurately up to complete conversion in the temperature range of 40 to 60°C.
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  • 66
    Electronic Resource
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    Angewandte Makromolekulare Chemie 175 (1990), S. 157-168 
    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 über Untersuchungen an Legierungen aus isotaktischem Polypropylen und EPDM-Elastomer berichtet, die mit hochenergetischen Elektronen bestrahlt worden waren. Die Mischungsverhältnisse in den Proben überstrichen sowohl den für elastomermodifizierte Thermoplaste typischen Bereich als auch den der thermoplasticschen Elastomeren. Eine Vernetzung der Komponenten über die Grenzfläche hinweg wurde nachgewiesen. Diese grenzflächenübergreifende Vernetzung bewirkte eine merkliche Verbesserung der mechanischen Eigenschaften insbesondere des thermoplastischen Elastomeren.
    Notes: Blends of isotactic polypropylene and EPDM rubber have been treated by electron irradiation in the composition range of rubber modification and in the thermoplastic rubber composition range as well. Mutual crosslinking of the components through the interface could be detected. This intercrosslinking caused a remarkable improvement of the mechanical properties particularly of the thermoplastic rubber.
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  • 67
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    Angewandte Makromolekulare Chemie 175 (1990), S. 205-205 
    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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  • 68
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanisms of photooxidation usually envisaged, are perfected by taking into account photoreactions of peroxy radicals. They involve interaction of a peroxy radical with the polymer to yield a hydroperoxy radical and a pair of macroradicals. After peroxidation, this pair will usually undergo bimolecular termination. The influence of such a reaction on photooxidation kinetics is particularly important for polyethylene. Then, chain termination occurs mainly by interaction of two hydroperoxy radicals or of a hydroperoxy radical with a macroperoxy radical. The reaction does not only affect kinetics of photooxidation but also the nature of the photooxidation products. The latter is more important for polypropylene than for polyethylene.
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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
    Notes: Isothermal Differential Thermal Analysis was used to test the thermooxidative stability of pipes of polybutene during internal pressure tests at 110°C. At low hoop stresses and long testing times pipe failure was exclusively caused by thermooxidative degradation of the polymer.The stabilizer distribution in the initial state and its alteration during the pressure tests could easily be measured by isothermal DTA. Leaching of antioxidants from pipe walls could be detected. The decrease of residual thermooxidative stability was degressive.Degradation of pipe material started from the exterior pipe wall. Molecular weight of polybutene decreased rapidly after stabilizer exhaustion which could be observed by isothermal DTA.
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  • 70
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A base of experimental data on the ageing of commerial grade plastics is created. In includes assorted physical and chemical properties of plastics and their changes at natural ageing. An automated system for storing and processing of the experimental data is designed. Processing involves mathematical modeling of the changes in properties that aids in empirical prediction. The possibilities of the system are verified with experimental results from a 5-year ageing period of PE-LD and PE-HD. The results show a good agreement between the predicted and real data for selected models.
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  • 71
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    Angewandte Makromolekulare Chemie 179 (1990), S. 35-56 
    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 Morphologie von Polypropylen-Spritzgußteilen mit Bindenaht wurde mit Röntgenweit-und Kleinwinkelstreuung, Lichtstreuung und Polarisationsmikroskopie untersucht. Die erhaltenen morphologischen Daten wurden mit mechanischen Werten aus Zugversuchen korreliert. Es wird gefunden, daß die mechanischen Eigenschaften der untersuchten Proben im wesentlichen von der sphärolithstruktur beeinflußt werden. Anhäufungen von Sphärolithen mit Kristallen der hexagonalen β-Modifikation und eine starke Inhomogenität der Sphärolithstruktur senkrecht zur Bindenaht sind der wesentliche Grund für die verschlechterten mechanischen Eigenschaften. Diese Sphärolithstruktur wird durch die Temperatur des Spritzgußwerkzeugs stark beeinflußt. Die Lamellen-Überstruktur hat dagegen einen vernachlässigbar kleinen Einfluß auf das mechanische Verhalten.
    Notes: The morphology of polypropylene plaques containing a weld line, has been investigated by x-ray wide and small angle scattering, light scattering and polarization microscopy. The results are correlated to mechanical values obtained from tensile tests. While the lamellar morphology is of neglectable influence, it is found, that the mechanical properties of the samples are strongly influenced by the spherulitic structure. Clustering of β-type spherulites and strong morphological inhomogeneities in the vicinity of the weld line are the primary reason for the mechanical weakening of the plaques. The temperature of the mould has a strong effect on the spherulitic structure and thus on the tensile properties of the samples.
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  • 72
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    Angewandte Makromolekulare Chemie 179 (1990), S. 77-85 
    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: Füllstoffe für PVC- und PP-Formmassen wurden mit Mikrowellenplasma behandelt. Photoakustische FT-IR-Spektren zeigen, daß die Plasma-Polymerhülle auf der Füllstoffoberfläche —C=C—, —CH2—, CH3— und andere Gruppen enthält. Aus Röntgenelektronenspektren geht hervor, daß zwischen Siliciumdioxid und der organischen Beschichtung chemische Bindungen existieren. Durch Compoundieren von plasmabehandelten Füllstoffen mit PVC und PP werden Materialien mit guten mechanischen Eigenschaften bei niedrigen Kosten erhalten.
    Notes: Fillers for PVC and PP compounds have been treated by microwave plasma. FT-IR photoacoustic spectroscopy studies show that the plasma polymer sheath on filler's surface contains —C=C—, —CH2—, —CH3 groups, etc. X-ray photoelectron spectroscopy studies reveal that interfacial chemical bondings exist between silica and the organic coating. Application of plasma-treated fillers in PVC and PP compounds gives rise to materials of good mechanical properties and low cost.
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  • 73
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    Angewandte Makromolekulare Chemie 179 (1990), S. 135-148 
    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: Poly-(alkylenadipat)-diole mit Molmassen von 1500, 2000 und 3000 wurden bei Temperaturen von 25 und 60°C in Gegenwart verschiedener Alkohole und unterschiedlicher PUR-Katalysatoren (1,4-Diazabicyclo[2.2.2]octan (DABCO), Dibutylzinndilaurat (DBTL),Dibutylzinndiethoxid (DBTEO) und Dibutylzinnoxid (DBTO)) in Ethylacetat bzw. Toluol gelagert und die Alkoholyse verfolgt. Die erhaltenen Ergebnisse werden mit dem Alkoholyseverhalten verschiedener Dialkyladipate sowie des Lösungsmittels Ethylacetat unter den selben Bedingungen verglichen. Die Alkoholyse verlauft in Gegenwart der zinnorganischen Verbindungen etwa mit gleicher Geschwindigkeit, ohne daß diese selbst signifikant zersetzt werden, wahrend DABCO praktisch inaktiv ist. Die Aktivitat der Alkohole ist starker von ihrer sterischen Struktur als von ihrer Basizitat abhangig. Die Stabilität der Polyalkylenadipate gegenüber einer Umesterung nimmt mit der Lange der Diolalkyleneinheiten des Polyols zu. Die Umesterung von Adipinsäuredialkylestern findet auch partiell in Anwesenheit eines großen Uberschusses an Ethylacetat statt.
    Notes: Poly(alkylene adipate)diols having molar masses of 1500, 2000 and 3000 were stored at temperatures of 25 and 60°C in the presence of low amounts of different alcohols and some polyurethane (PUR) catalysts, such as dibutyltindilaurate (DBTL), dibutyltindiethoxide (DBTEO), dibutyltinoxide (DBTO), and 1,4-diazabicyclo[2.2.2]octane (DABCO). Alcoholysis was studied using either ethyl acetate (EA) or toluene as solvent. The results were compared with those obtained by examining the behaviour of several dialkyl adipates and ethyl acetate under identical conditions. The alcoholysis in the presence of the tin catalysts proceeds at the same reaction rate without significant decomposition of the catalyst, whereas DABCO is practically inactive. The nucleophilic activity of the alcohols depends on their bulk size rather than their basicity. The resistance of polyalkylene adipates to transesterification increases with the increasing alkyl chain length of diol units in polyester. A partial transesterification of dialkyl adipates takes place too, in spite of ethyl acetate being present in excess.
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  • 74
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    Angewandte Makromolekulare Chemie 179 (1990), S. 157-171 
    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 wurde das Permeations- und Trennverhalten von Alkohol/Wasser-Systemen durch poröse PVA-Membranen untersucht. PVA-Membranen mit unterschiedlicher Anzahl und Große von Poren wurden über Mischungen in Lösung mit verschiedenen synthetisierten Polymeren und Copolymeren, wie Polyacrylsäure, Polyacrylnitril, Polyacrylamid, Poly(Methylmethacrylat-co-Maleinsäureanhydrid) etc., anschließendes Gießen von Filmen und Extraktion der Polymeren oder Copolymeren durch Lösungsmittel hergestellt. Die Abhängigkeit der Durchlässigkeit und Trennwirkung von der Größe und Form der permeierenden Moleköle wurde qualitativ diskutiert. Des weiteren wurde die Selektivität der Trennwirkung in Abhangigkeit von der Zusammensetzung von Alkohol/Wasser-Gemischen und von der Größe und Anzahl der Poren untersucht. Es wurde gefunden, daß die Selektivität von der Menge und dem Molekulargewicht der in die Membranen eingebrachten Polymeren abhängt. Wenn der Gewichtsanteil des verwendeten Polymeren größer als 0,1 war, permeierte bevorzugt der Alkoholanteil bei methanolischen Msungen, wobei der Trennfaktor mit steigender Methanolkonzentration anstieg. In Gemischen mit anderen Alkoholen zeigten die Membranen andererseits eine selektive Durchlässigkeit für Wasser. Der Einfluß der Versuchsbedingungen wurde ebenfalls untersucht.
    Notes: The permeation and separation characteristics of alcohol/water systems through porous PVA membranes were investigated. Porous PVA membranes with different pore size and number were prepared by solution blending of PVA with several synthesized polymers or copolymers, such as polyacrylic acid, polyacrylamide, polyacrylonitrile, and methylmethacrylate-co-maleic anhydride, etc. Then casting, and finally extracting the blended polymers or copolymers by solvent from the membranes. The dependency of both permeation and separation on the molecular size and shape of the permeating species was dicussed qualitatively. Moreover, the permselectivity was investigated with attention to the feed composition of alcohol/water mixture and the effect of pore size and number. The selectivity was found to depend on the weight ratio and the molecular weight of polymer introduced to the membrane. When the weight ratio of polymer introduced into the membrane was larger than 0.1, methanol was permeated through membrane preferentially in methanol/water system, and the separation factor increased with increasing the methanol feed concentration. On the other hand, membrane had a selective permeability for water in the other alcohol/water systems. The influence of operating conditions was also studied.
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  • 75
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    Angewandte Makromolekulare Chemie 175 (1990), S. 29-38 
    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: Die Temperatur des T1-Minimums für die Segmentbewegung in Polypropylen, das einen hohen ataktischen Anteil besitzt, ist niedriger als die in isotaktischem Polypropylen. Ein kurzes T1, T1s, tritt bei beiden Materialien auf. Bei Temperaturerhöhung nimmt T2a (T2 der beweglichen amorphen Bezirke) stark und T2m (T2 der dazwischen liegenden Bezirke) leicht zu, während sich T2c (T2 der steifen kristallinen Bezirke) kaum ändert. T2a in Polypropylen mit hohem ataktischem Anteil ist länger als in isotaktischem Polypropylen.Der Massenbruch der kristallinen Bezirke, Fc, nimmt bei Temperaturerhöhung ab und der der amorphen Bezirke, Fa, zu. Die Relaxationsgeschwindigkeit, 1/ (T1min), steigt linear mit Zunahme des amorphen Anteils an, außer bei der mit siedendem n-Heptan extrahierten Probe. Mit Zunahme der Peaktemperatur von tan δ fällt T2a nahezu linear ab, während die Temperatur des T1-Minimums zunimmt.
    Notes: The temperature of the T1 minimum for the segmental motion in polypropylene containing a lot of atactic fraction is lower than that in isotactic polypropylene. A short T1, T1s, appears for both materials. As the temperature is raised, there is a large increase in T2a (T2 of the mobile amorphous regions), and a mild increase in T2m (T2 of the intermediate regions), while there is no substantial change in T2c (T2 of the rigid crystalline regions). T2a in polypropylene containing a lot of atactic fraction is longer than that in isotactic polypropylene.The mass fraction of crystalline regions, Fc, decreases and that of the amorphous regions, Fa, increases as the temperature is raised. There is a linear increase in the relaxation rate, 1/(T1min), as the amorphous fraction is increased, except for the sample extracted with boiling n-heptane. With increase of the peak temperature of tanδ, T2a decreases nearly linearly, while the temperature of the T1 minimum increases.
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  • 76
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    Angewandte Makromolekulare Chemie 180 (1990), S. 191-198 
    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 Bestrahlung von PTFE mit Elektronen niedriger Energie führt zur Abspaltung von Fluor und zum Einbau von Sauerstoff in die Polymeroberfläche. Es wird gezeigt, daß das Ausmaß der Oberflächenveränderungen hauptsächlich von der Zahl und kaum von der Energie der Elektronen abhängt, die die Oberfläche erreichen. Änderungen in der Oberflächenenergie resultieren in unterschiedlichem Benetzungsverhalten. Kontaktwinkelmessungen und Kurvenanalysen der C-1s-Peaks aus Röntgenphotonenspektroskopiemessungen zeigen, daß der am wenigsten benetzbare Teil der bestrahlten Oberflächen in den meisten Fällen aus —CF2 —CF-Einheiten besteht. Werden bei der Bestrahlung nahezu alle Fluoratome abgespalten, bleiben nur isolierte —CF2-oder —CF-Gruppen zurück. Die „receding“-Winkel werden mit zunehmender Sauerstoffkonzentration in der Oberfläche kleiner, was auf die Bildung stark oxidierter Bereiche hinweist. Die Unabhängigkeit der Kontaktwinkel von der Alterungsdauer deutet auf eine sehr geringe Beweglichkeit der Makromoleküle hin, was mit einer starken Vernet-zung an der Oberfläche zusammenhängen könnte.
    Notes: Low energy electron irradiation of PTFE induced fluorine depletion and introduction of oxygen on the surface. The effect on surface chemistry was shown to be dependent mostly on the amount of electrons reaching the sample, rather than on their energy.Changes in surface energy resulted in different wetting behaviors. The measurement of advancing water contact angles and the analysis of XPS C-1s peak shapes showed that the least wettable portion of irradiated surfaces is made in most cases of —CF2—CF — units. When the treatment caused a nearly complete fluorine depletion, only isolated —CF2— or —CF— groups are present. Receding angle values decreased linearly depending on the amount of oxygen introduced on the sample during the treatment, suggesting the formation of strongly oxidized polymer islets. The invariance of contact angles with aging time indicated very low macromolecular mobility, probably related to extensive surface crosslinking.
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  • 77
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    Angewandte Makromolekulare Chemie 181 (1990), S. 41-52 
    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 aqueous dispersions of anionic polyurethanes containing the triethylammonium salt of 2,2-dimethylol propionic acid as chain extender, triethylamine can be largely replaced by ammonia. For electrostatic reasons, NH4+ is namely more tightly bound in the ion pairs located in the Stern layer than NH(C2H5)3+. Thermal treatment of films leads to a loss of base, whereby ammonia is more rapidly released than triethylamine. Therefore, crosslinking with partially methylated hexamethylolmelamine proceeds the faster the more triethylamine is replaced by ammonia.
    Notes: In Dispersionen aus anionischen Polyurethanen, die das Triethylammoniumsalz der 2,2-Dimethylolpropionsäure als Kettenverlängerungsmittel enthalten, läßt sich durch Zugabe von Ammoniak eine weitgehende Verdrängung des Triethylamins erreichen. Aus elektrostatischen Gründen ist nämlich in den in der Sternschen Schicht lokalisierten Ionenpaaren NH4+ fester gebunden als NH(C2H5)3+. Bei der thermischen Behandlung der Filme tritt Basenabspaltung ein, dabei erfolgt die Abgabe von Ammoniak deutlich schneller als die von Triethylamin. Die Spannungswerte der mit teilmethyliertem Hexamethylolmelamin vernetzten Proben sind daher um so höher, je mehr Triethylamin durch Ammoniak ersetzt wurde.
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  • 78
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    Angewandte Makromolekulare Chemie 181 (1990), S. 53-66 
    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 Viskoelastizitäts-Parameter von geschmolzenem Polystyrol (PS) wurden mit einem Instron-Kapillarrheometer gemessen.Die Drucknachgiebigkeit B(t) zeigt ein Plateau sowohl im Schmelze (B1)- als auch im Glaszustand (Bg); beide nehmen mit abnehmender Spannung ab. Durch Verschiebung der B(t)-Kurven werden Master-Kurven erhalten, mit denen das Gesamtdruckverhalten (überlagerte elastische und viskose Deformationen) analysiert werden kann. Die stationäre Nachgiebigkeit (Bs) erlaubt eine Beschreibung des elastischen Energieanteils und scheint mit der Extrusions-Strangaufweitung (Bcs/Bds) korreliert zu sein. Die Volumenviskosität (ηk) nimmt mit zunehmender Spannung (P), zunehmender Belastungsgeschwindigkeit (k) und abnehmender Temperatur ab.
    Notes: Viscoelastic parameters of polystyrene (PS) melt in compression creep have been measured in an lnstron capillary-rheometer.Bulk compression creep compliance B(t) shows plateau regions in the molten state (B1) and the glassy state (Bg), both decreasing with increasing stress. Shifting of B(t) curves provides master curves suitable to analysing the total (superposed elastic and viscous deformations) bulk compression behaviour. The steady-state creep compliance (Bs) allows to describe the recoverable elastic energy (Be) and seems to be related to the extrusion die swell (Bcs/Bds). Volume viscosity (ηk) decreases with decreasing stress (P), increasing compression rates (k) and decreasing temperature (T).
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  • 79
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    Angewandte Makromolekulare Chemie 181 (1990), S. 67-74 
    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 wurden Untersuchungen über Molekulargewichtsänderungen an physikalisch bei Raumtemperatur gealterten isotaktischen Polypropylenfilamenten (iPP) mit Hilfe der Hochtemperaturgelpermeationschromatographie (HTGPC) durchgeführt. Das Ergebnis der Untersuchungen weist auf eine sehr unbedeutende Änderung des Molekulargewichts des Materials während der Alterung hin.Das Materialgranulat wurde als Bezugsstandard gewählt. Basierend auf der Uneinheitlichkeit D = Mw/Mn des Granulats wurden Filamente der Handelsprodukte GYE 47 und PXC 31399 charakterisiert, deren Alterungsdauer zwischen 2 Wochen und 8 Monaten lag. Bei den Filamenten der Qpe GYE 47 verringerte sich die Breite der Molekulargewichtsverteilung D um durchschnittlich 12%. Andererseits zeigen die Filamente des PXC 31399-vps einen weniger eindeutigen Trend zur Änderung, jedoch im Mittel hat sich die Breite der Verteilung um etwa 20% erniedrigt. Bei letzterem ist die Verteilung iiber die Alterungsdauer stark gestreut. Der GYE 47-Typ zeigt eine nahezu asymptotische Abnahme. Es wird angenommen, daß die Ungleichartigkeit in der Ändenz der Anderung von D zwischen beiden Proben in ihrer unterschiedlichen thermodynamischen Stabilitat liegen ktinnte; PXC 31399 ist weniger stabil.
    Notes: Experiments on the molecular weight variations of physically, room temperature aged isotactic polypropylene (iPP) filaments were done using the High Temperature Gel Permeation Chromatography (HTGPC). Evidence emanating from the studies indicates a very marginal change in molecular weight of the materials during aging.The granules of the materials were chosen as the reference standard. Based on the polydispersity D = Mw/Mn of the granules, filaments of commercial grades GYE 47 and PXC 31399 were characterized between an aging period ranging from 2 weeks to 8 months. The filaments of the GYE 47 grade have their distributions D lowered on the average by about 12%. On the other hand, those of the PXC 31399 grade have a less definite trend in change, but on the average, D is lowered by about 20%. The distributions of this latter grade are highly scattered over the period of aging. The GYE 47 grade shows a reduction in the distribution of a near asymptotic nature. It is believed that the disparity in the trend of change of D between the two samples could be attributed to their relative thermodynamic stability with the PXC 31399 grade being less stable.
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  • 80
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The properties (squared dimensions, anisotropy, numbers of intra- and intermolecular contacts) of a single five-way cubic lattice chain embedded into an environment (matrix) of chains of the same length n = 50 were evaluated as a function of matrix volume fraction (matrix density) v and intermolecular interaction between the matrix polymer and the minority chain segments, characterized by a parameter φ. No convincing evidence was found for the occurrence of a coil-globule transition in the range of matrix densities (v ≤ 0.7) and repulsive interactions between matrix and minority chain (φ ≤ 0.2) investigated. For moderate attractive interaction (φ ≈ -0.17) a compensation of the chaincompressing action of the matrix and the chain-expanding interaction with the matrix was observed resulting in a zero-dependence of the size and shape of the minority chain on matrix density. It further turned out that there are fixed relations among the various size and shape data irrespective of the specific combination of matrix density and thermodynamic interaction by which a particular polymer dimension is produced. These interrelations are fairly the same as those evaluated for isolated chains the size of which is varied by an intramolecular energy parameter φi.
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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
    Notes: New three phases composite materials made of glassbeads as filler, water as liquid dispersed phase and polystyrene as matrix were obtained by polymerization of a water in oil emulsion formed by water dispersed in styrene in which glass beads are added. For this purpose glass beads have to be modified by silanization by a coupling agent 3-(Trimethoxysilyl)propylmethacrylate (TPM) or a silane Octadecyltrichlorosilane (ODMS), in order to prevent the wetting of the glass by water. Only low coverage of the glass surface by the coupling agent (0,05% of TPM) are convenient for the preparation cellular materials having good mechanical properties. At higher coverage ratio, strong hydrophobic glass beads are obtained which destabilize the water / styrene emulsion and lead to macroporous products. Study of the rheology of the filled emulsion appears to be the more simple and more sensitive method to determine the level of wettability of the glass bead by the emulsion which is the most significant parameter for the preparation of such three phases composite materials. Composite materials made of glass beads, air and polystyrene are simply obtained by evaporation of water under vacuum.
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  • 82
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To test the molecular parameters concerning gas sorption in polymers, the concentration of CO2, N2O, CO, N2, CH4 and the noble gases Ne, He in glassy poly(butylene terephthalate) films (PBTP) has been studied gravimetrically with a recording microbalance at 25°C. The sorption isotherms exhibit downward curvature to the pressure axis. As neither solubility nor adsorption can explain the experimental results, analysis was carried out based on the dual-sorption model: gas dissolution and microvoid filling are considered as independent sorption mechanisms. The parameters of the dual-sorption model for the mentioned penetrants are determined. The results indicate that for parameter correlation the Lennard-Jones potential parameters give a rough idea, but size exclusion of gases in small diameter microvoids is proposed and special chemical interactions must be considered.
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  • 83
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    Angewandte Makromolekulare Chemie 185 (1991), S. 283-292 
    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 ring opening metathesis polymerisation (ROMP) of 5-cyano-2-norbornene with tungsten hexachloride, tungesten oxytetrachloride, bis(dichloralkoxo)tungsten tetrachloride and bis(dichloralkoxo)tungsten oxydichloride as transition metal component was studied. Methylaluminoxan, diethylaluminium ethoxide, tetraisobutyldialuminoxan and tetrabutyltin served as cocatalyst. Toluene, Chlorobenzene and dichloromethane were used as solvents. The concentration of the tungsten components was in the range from 5 × 10-4 to 5 × 10-3 mol/l. Among the catalyst studied, tungsten hexachloride with diethylaluminium ethoxide proved to be the best. The polymerisation was highly selective with this system even at high monomer/tungsten ratios (e.q. 10200:1) and let to high conversions (≥82%).
    Notes: Die ringöffnende metathetische Polymerisation (ROMP) von 5-Cyano-2-norbornen wurde unter Einsatz von Wolframhexachlorid, Wolframoxidterachlorid, Bis(dichloralkoxo)wolframtetrachlorid und Bis(dichloralkoxo)wolframoxiddichlorid als Übergangsmetallkomponente untersucht. Als Cokatalysatoren dienten Methylaluminoxan, Diethylaluminiumethoxid, Tetraisobutyldialuminoxan und Tetrabutylzinn. Als Lösungsmittel wurden Toluol, Chlorbenzol und Dichlormethan verwendet. Die Konzentration der Wolframkomponente lag im Bereich 5 × 10-4 - 5 × 10-3 mol/l. Unter den geprüften Katalysatoren erwies sich Wolframhexachlorid in Verbindung mit Diethylalumiumethoxid als der geeignetste. Mit diesem System verlief die Polymerisation auch bei großen Monomer/Wolfram-Verhältnissen (10200 :1) hochselektiv und führte zu großen Umsätzen (≥82%).
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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
    Notes: The dependence of dilution on the chain propagation and termination rate constants was investigated in the polymerization of ethyl acrylate in benzene solution at 50°C, with the rotating sector method. The errors of the above rate constants were determined and, by our method applied to decrease these errors, the errors of the propagation rate constant was reduced to its half value. By the application of our earlier results in polymerization kinetics, we found that in this system the chain propagation step is exclusively responsible for the solvent effects observed. Our experimental results can be quantitatively described in terms of the hot redical theory.
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  • 85
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    Angewandte Makromolekulare Chemie 185 (1991), S. 329-334 
    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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  • 86
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    Angewandte Makromolekulare Chemie 174 (1990), S. 1-10 
    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 Photopolymerisation von Ethylenglykoldimethacrylat (EGDMA) mit Methylmethacrylat (MMA) wurde mit Benzoinmethylether (BME) als Initiator in einem Glasrohr durchgeführt, um einen lichtfokussierenden Plastikstab (Radius Rp) mit parabolischer Brechungsindex-Verteilung (Verteilungskonstante A) in der Nähe der Stabachse (bis zum Radius Rc) herzustellen. Die Abhängigkeit von A und Rc/Rp vom Monomerenverhältnis MMA/EGDMA der Ausgangsmischung, der Einfluß der BME-Konzentration auf die Brechungsindex-Verteilung und die Reproduzierbarkeit der Photopolymerisationen wurden untersucht. Das Rc/Rp-Verhältnis stieg mit dem Monomerenverhältnis MMA/EGDMA bei BME = 1,0 Gew.-% und der Geschwindigkeit der UV-Lampe von V = 0,58 mm/min an. Andererseits stieg Rc/Rp bei BME = 0,6 Gew.-% und V = 0,735 mm/min bis zum Monomerenverhältnis von 0,2 an und fiel dann deutlich zwischen 0,20 und 0,25 ab. Die Plastikstäbe, die hier durch Photopolymerisation hergestellt wurden, haben Linseneigenschaften und sind gut reproduzierbar.
    Notes: The photocopolymerization of ethyleneglycol dimethacrylate (EGDMA) with methylmethacrylate (MMA) containing benzoin methyl ether (BME) as initiator was carried out in a glass tube to fabricate a light-focusing plastic rod (radius Rp) with a parabolic refractive index distribution (distribution constant A) in the region near the center axis (radius Rc). The dependence of A and Rc/Rp on MMA/EGDMA feed ratio, influence of BME concentration on the refractive index distribution, and the reproducibilities of the photopolymerizations were investigated. The Rc/Rp increased with the feed ratio used under BME = 1.0 wt.-% at velocity of UV lamp V = 0.58 mm/min. On the other hand, Rc/Rp increased with the feed ratio to 0.2 and then decreased remarkably with the feed ratio in the range of 0.2-0.25 with BME = 0.6 wt.-% at V = 0.735 mm/min. Plastic rods fabricated in the investigation using photopolymerization have lens characteristics and good reproducibilities.
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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: Polystyrol- und Polymethylmethacrylateinzelfäden mit verschiedenen Graden von Doppelbrechung wurden durch die kontinuierliche Änderung der Ziehgeschwindigkeit, der Temperatur der Polymerschmelze und des Molekulargewichts von Polystyrol (PS) und Polymethylmethacrylat (PMMA) gewonnen. Der “brittle to ductile” Übergangspunkt (Übergang des Polymeren vom spröden zum ziehbaren Zustand) wurde für das optisch reine Polystyrol im Bereich der Doppelbrechungszahlen -0,6 · 10-3 bis -2,6 · 10-3 gefunden. Höhe und Lage dieses Punktes werden durch das Molekulargewicht, die Molekulargewichtsverteilung und die Temperatur der Polymerschmelze beeinflußt. Die Werte des Doppelbrechungsindexes von PS sind um zwei Zehnerpotenzen höher als von PMMA. Bei PMMA wurde der “brittle to ductile” Übergangspunkt nicht beobachtet. Die mechanischen und optischen Eigenschaften hängen nicht nur vom mittleren Wert des durch die Doppelbrechung charakteri-sierten Orientierungsgrades ab, sondern auch davon, welcher Teil des Relaxations-spektrums des Polymeren vorzugsweise orientiert ist. Beim Ziehen der PS- und PMMA-Einzelfäden bilden sich in der Mitte des Fadens Risse (crazes), die jedoch nicht an die Oberflache des Fadens treten.
    Notes: Monofilaments possessing various degrees of birefringence were obtained by changing the drawing rate, the molten polymer temperature, and the molecular weight of polystyrene (PS) and poly(methyl methacrylate) (PMMA). The “brittle-toductile” transition point of optically pure PS was found in the range of birefringences of -0.6 · 10-3 to -2.6 · 10-3. Both the height and position of this point are influenced by M̄w, molecular weight distribution, and polymer melt temperature. The birefringence of PS is higher by two orders of magnitude than that of PMMA in which this transition point has not been observed. The mechanical and optical properties depend not only on the average amount of orientation characterized by the birefringence but on what portion of the relaxation spectrum of the polymer is preferentially oriented. During the drawing of PS and PMMA monofilaments crazes are formed in the centre of the fibers and do not reach the surface.
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  • 88
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    Angewandte Makromolekulare Chemie 174 (1990), S. 105-117 
    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 possibility of the application of atactic polypropylene is investigated as graft base for the preparation of graft copolymers of vinyl acetate and vinyl chloride respectively graft copolymers from vinyl acetate onto polypropylene as graft base for the preparation of graft copolymers of vinyl chloride in relation to the composition of the original mixture.After compounding of the graft products with polyvinyl chloride or ABS/polyvinyl-chloride mixtures selected mechanical properties are presented in relation to the quantity and composition of the incorporated graft copolymers.
    Notes: Die Möglichkeiten des Einsatzes von ataktischem Polypropylen als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylacetates und Vinylchlorids bzw. von Polypropylen-Vinylacetat-Pfropfprodukten als Pfropfgrundlage zur Herstellung von Pfropfcopolymerisaten des Vinylchlorids werden in Abhängigkeit von der Ausgangsgemischzusammensetzung untersucht.Nach Abmischung der Pfropfprodukte mit Polyvinylchlorid bzw. ABS/Polyvinylchlorid-Mischungen werden ausgewählte mechanische Eigenschaften sowohl in Abhängigkeit von der Menge des enthaltenen Pfropfproduktes als auch von der Zusammensetzung der Pfropfpolymerisate dargestellt.
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  • 89
    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: A new spectroscopic method for determining the permeability of ammonia in transparent polymer layers is presented. It is based on the quantitative proof of the ammonia passing the test layer into a sensor layer, containing 4-nitrophenol as an NH3-sensitive probe, which is placed under the test film. The permeability (P) of the test layer is calculated from the slope of extinction with time in the sensor layer. The lag time (t1) gives the diffusion coefficient (D). The suitability of this method is confirmed by comparison with literature values. Diffusion coefficients obtained from t1 correspond well to those obtained by the sorption method.The temperature dependence of P and D in more than five different polymers (CDA, PVB, PVAc, PVC and different polyvinyl alcohols) demonstrates that peculiarities in the temperature dependence of the permeability result from the behaviour of the NH3-solubility (P/D) which is strongly dependent on the polymer structure.
    Notes: Es wird eine neuartige spektroskopische Methode zur Messung der Ammoniak-Permeabilität in transparenten Polymerfilmen vorgestellt. Sie beruht auf dem quantitativen Nachweis des den Testfilm durchdringenden Ammoniaks in einer darunter befindlichen Sensorschicht mit Hilfe der NH3-empfindlichen Sonde 4-Nitrophenol. Aus dem Anstieg der Extinktion mit der Zeit (ΔE/Δt) in der Sensorschicht wird die Permeabilität (P) und aus der Verzögerungszeit (lag time (t1)) der Diffusionskoeffizient (D) berechnet. Die Eignung der Methode wird durch Vergleich mit Literaturwerten belegt. Die aus t1 zugänglichen Diffusionskoeffizienten stimmen sehr gut mit denen überein, die mit der Sorptionsmethode gefunden werden.Die Temperaturabhängigkeiten von P und D in mehr als fünf verschiedenen Polymeren (CDA, PVB, PVAc, PVC und in verschiedenen Polyvinylalkoholen) zeigen, daß Besonderheiten im Temperaturgang der Permeabilität aus dem vom Aufbau des Polymeren stark abhängigen Verhalten der NH3-Löslichkeit (P/D) resultieren.
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  • 90
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    Angewandte Makromolekulare Chemie 179 (1990), S. 99-111 
    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: Es wurde die strahleninduzierte Pfropfung von 4-Vinylpyridin (VP) auf Styrol-Butadien-Styrol-Copolymere (SBS) in Gegenwart von gelöstem Sauerstoff untersucht. Pfropfcopolymer-Membranen mit unterschiedlichen Pfropfgraden wurden durch Gießen aus benzolischer Lösung hergestellt. Die mechanischen Eigenschaften, die Gaspermeabilität sowie der Einfluß der Temperatur auf die Gasdurchlässigkeit wurden untersucht. Der höchste Pfropfgrad von 8,4% wurde bei einer Bestrahlungszeit von 15,5 herreicht. Sowohl bei kürzeren als auch längeren Bestrahlungszeiten war der Pfropfgrad  -  bedingt durch Störung durch den vorhandenen Sauerstoff  -  niedriger. Reißfestigkeit und Reißdehnung von SBS-g-VP waren vergleichbar rnit SBS. Die Spannungsrelaxation von SBS-g-VP war langsamer als bei SBS, was auf der Bildung von starren Polyvinylpyridin(DVP)-Mikrophasen beruhen könnte, die als permanente Vernetzungspunkte wirken und die Spannungsrelaxation beeinträchtigen könnten.Da SBS eine hohe Gasdurchlässigkeit und PVP eine hohe O2/N2-Selektivität aufweisen, wurde die Gasdurchlässigkeit der Pfropfmembranen untersucht. Die Selektivitat der SBS-g-VP-Membranen stieg mit steigendem Pfropfgrad, allerdings auf Kosten der Permeabilität, Bei Erhöhung der Temperatur nahm die Durchlässigkeit zu, das Verhältnis O2/N2, aber ab. Die Aktivierungsenergie (Ep) der Gasdurchlässigkeit stieg mit dem Pfropfgrad. Für eine nichtgepfropfte SBS-Membran betrug Ep 5,5 kcal/mol für Sauerstoff und 7,2 kcal/mol für Stickstoff. Für eine SBS-g-VP-Membran mit einem Pfropfgrad von 8,4% waren die Ep-Werte für Sauerstoff und Stickstoff 6,5 bzw. 8,1 kcal/mol.
    Notes: The grafting of 4-vinyl pyridine (VP) onto styrene-butadiene-styrene triblock copolymers (SBS) by homografting irradiation with dissolved oxygen was studied. Homograft membranes of various degree of grafting were prepared from a casting solution of grafted copolymer in benzene. The mechanical properties of membranes, gas permeability, and the effect of operating temperature on gas permeation were investigated.The degree of grafting of 8.4% was the largest at an irradiation time of about 15.5 h. It was smaller at both shorter and longer duration because of the interference of dissolved oxygen. It was found that the tensile strength and elongation of SBS-g-VP were similar to those of SBS. The stress relaxation of SBS-g-VP was slower than that of SBS, and this might be due to the formation of rigid microphase separation domain of poly(4-vinyl pyridine), which acted as permanent crosslinking points to reduce the stress relaxation.Using the properties of high flux of SBS and high O2/N2 selectivity of poly(4-vinyl pyridine), the performance of gas permeation of 4-vinyl pyridine homografted SBS membrane was studied. The selectivity of SBS-g-VP membrane increased with increasing degree of grafting. However, it was done at the expense of a decrease in the gas permeability.When the operating temperature of gas permeation increased, the permeability of oxygen and nitrogen increased, and the O2/N2 permeability ratio decreased. The activation energy (Ep) for gas permeation through different degree of grafting of SBS-g-VP membrane (obtained by the Arrhenius law) increased with increasing degree of grafting. For ungrafted SBS membrane, Ep was 5.5 kcal/mol for oxygen and 7.2 kcal/mol for nitrogen. For 8.4% grafting degree SBS-g-VP membrane, Ep for oxygen and nitrogen, were 6.5 and 8.1 kcal/mol, respectively.
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  • 91
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    Angewandte Makromolekulare Chemie 175 (1990), S. 13-27 
    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 change of molecular mass and long-term strength of high and low density polyethylene under tensile load in surface-active medium was studied. It is shown that long-term strength of polyethylene depends on the molecular mass. The influence of polydispersity on strength was investigated.
    Notes: Es wird über die Untersuchungsergebnisse von Lebensdauer und Molmassenänderung an polydispersen Proben von HDPE und HDPE in einem breiten M̄v-Bereich im Zugversuch in einem oberflächenaktiven Medium berichtet.Die Arbeit enthält auch die Darstellung der quantitativen Änderung der Molmasse von Hochdruck- und Niederdruck-Polyethylen unter Dauerbeanspruchung und die Analyse der Lebensdauer in Abhängigkeit von den unterschiedlichen Molmassen (MM) (M̄w, M̄n, M̄v); die Unterschiede in Abhängigkeit von der Lebensdauer von M̄v für Proben und polydisperse Muster sowie die Vorstellungen über den dualen Einfluß der Polydispersität auf die Lebensdauer mit einer Interpretation der auftretenden Erscheinungen werden beschrieben.
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  • 92
    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: One constitutive property for the description of dyeing polyester-materials with disperse dyes is the particle size distribution in the dye bath. To measure particle sizes below one micrometer in situ, special techniques are required. One of these is the so called photon-correlation-spectroscopy, depending on the scattering of laser light by suspended small particles in a fluid. The mathematical and physical principles of the photon-correlation-technique are explained in this article.
    Notes: Eine zur Beschreibung des Färbevorganges von Polyestermaterialien mit Dispersionsfarbstoffen wesentliche Größe stellt die Partikelgrößenverteilung im Farbebad dar. Partikelgrößen unterhalb eines Mikrometers lassen sich in situ nur mit wenigen Meßtechniken bestimmen. Dazu zählt u. a. die Photonen-Korrelations-Spektroskopie, die auf Streuung von Laserlicht an kleinen, in einer Flüssigkeit suspendierten Teilchen basiert. Die mathematischen und physikalischen Grundlagen dieser Meßtechnik werden in diesem Artikel erläutert.
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  • 93
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    Angewandte Makromolekulare Chemie 175 (1990), S. 81-97 
    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 Kristallinität von Polyethylen, Polyethylenterephthalat und Polypropylen wurde mit Hilfe der Röntgenweitwinkel(WAXS)-und-kleinwinkel(SAXS)streuung gemessen. Die mittels der letzteren Methode erhaltenen Kristallinitätswerte sind deutlich größer als die durch WAXS. Es wird vermutet, daß die Unterschiede mit der Schicht zusammenhängen, die zwischen den amorphen und kristallinen Bereichen liegt. Daraus wurde geschlossen, daß die Röntgenkleinwinkelstreuung nicht als unabhängige Routinemethode zur Kristallinitätsbestimmung angewendet werden kann.
    Notes: The crystallinity of polyethylene, polyethyleneterephthalate, and polypropylene was measured with the aid of wide angle (WAXS) and small angle (SAXS) X-ray scattering methods. The values of crystallinity evaluated using the latter method are distinctly larger than those ones given by the WAXS method. The differences are supposed to be associated with the transition layer existing between the amorphous and crystalline regions. It was concluded that small angle X-ray scattering cannot be employed as an independent routine method of crystallinity determination.
    Additional Material: 11 Ill.
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  • 94
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 117-128 
    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: Für das System Cellulosenitrat-μ-Styragel-THF wurde die DP-Ve-Beziehung sowie die Ausarbeitung der betreffenden Eichparameter einer genaueren Betrachtung unterzogen. Die etwa dreißig Eichpräparate waren durch definierten säurekatalysierten Abbau von Baumwollcellulose und anschließende Nitrierung hergestellt worden und umfaßten einen DP-Bereich von 150 〈 DP 〈 8000. Es wird gezeigt, daß mit steigendem DP die DP-Ve-Beziehung drei verschiedene Phasen aufweist. Bei der Anwendung der SEC auf Cellulosenitrat müssen daher bezüglich der Eichung zwei Fehlerquellen in Betracht gezogen werden: eine bezieht sich auf die Methode der Ausarbeitung der Eichparameter als solche, und die andere auf die Nichtbeachtung des Vorhandenseins dreier Abschnitte in der DP-Ve-Beziehung. Die Auswirkung dieser Fehler auf die Genauigkeit der aus den Elutionsdiagrammen abgeleiteten Verteilungskurven und DP-Mittelwerte wird diskutiert.
    Notes: The calibration behaviour of the system cellulose nitrate-μ-Styragel-THF has been studied using about 30 different calibration samples prepared by defined acid catalyzed degradation of cotton cellulose. The samples covered a range of DP between 150 〈 DP 〈 8000. It is shown that the DP-Ve relationship is characterized by the existence of three subsequent stages. Consequently, two sources of errors in the DP-Ve calibration must be taken into consideration. One refers to the methods as such to elaborate the calibration parameters, and the other one arises by neglecting that the DP-Ve relationship involves 3 distinct stages. The extent of the two classes of errors in regard to the exactness of the determined molecular weight averages and molecular weight distributions is discussed.
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 175 (1990), S. 141-156 
    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: Bei der Polycondensation von d,l-Asparaginsäure mit Nδ-phthaloyl-L-ornithin in Phosphorsäure bei 185°C entstehen statisticsche Copolymere (Ausbeute 60  -  70%) aus Poly(d,l-succinimid-co-Nδ-phthaloyl-d,l-ornithin), Formel 6, mit inhärenten Viskositäten (DMF) von 5 bis 15 ml g-1. Copolyimide der selben Zusammensetzung 6 und vergleichbarer Kettenlänge werden aus Asparaginsäure und dem Kupferchelat des Phthaloylornithins erhalten. Die Behandlung des Copolymeren 6 mit Hydrazinhydrat fuhrt zur Öffnung der Succinimid-Kettenglieder unter Bildung von Hydrazid-Seitengruppen. Die resultierenden Polyamide sind Poly(α,β-d,l-asparaginsäurehydrazid-co-d,l-ornithin), Formel 7. Kürzere Reaktionszeiten bedingen unvollständige Ringöffnung, und die verbleibenden Succinimid-Gruppen werden bei der folgenden Aufarbeitung hydrolytisch gespalten unter Bildung von Asparaginsaüre-Gruppen; die sogebildeten Polyamide besitzen die Struktur 8. Beide Polymere, 7 und 8, sind in Wasser loslich und zeigen in Wasser inharente Viskositiiten von 5 bis 14 ml g-l. Die Fahigkeit dieser Polyamide zur Arzneimittelverankerung wird durch Ankoppeln von Carbonsau- ren als Modellsubstanzen gezeigt.
    Notes: The polycondensation of d,l-aspartic acid with Nδ-phthaloyl-l-ornithine in phosphoric acid at 185°C gives rise to the formation, in 60  -  75% yield, of random copolymers of the poly(d,l-succinimide-co-Nδ-phthaloyl-D,L-ornithine) type 6 possessing inherent viscosities (DMF) in the range of 5  -  15 ml g-1. Copolyimides of the same compositions 6 and comparable chain lengths are obtained from aspartic acid and the copper chelate of the phthaloylornithine. Treatment of copolymers 6 with hydrazine hydrate in DMF leads to N-deprotection and opening of the intrachain succinimide rings with formation of hydrazide side groups. The resultant polyamides are of the poly(α,β-d,l-asparthydrazide-co-d,l-ornithine) type 7. Shorter reaction periods give incomplete hydrazinolytic ring opening, and the remaining succinimide units are cleaved hydrolytically during the subsequent aqueous workup, thereby transforming into aspartic acid units. The polyamides so formed possess the general poly(α,β-d,l-asparthydrazide-co-α,β-d,l-aspartic acid-co-d,l-ornithine) structure 8 Both types 7 and 8 are soluble in water and, in this medium, give inherent viscosities of 5  -  14 ml g-1. The potential drug-anchoring capabilities of these amine-functionalized polyamides are demonstrated by coupling reactions with model carboxylic acids.
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  • 96
    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: Im Zusammenhang mit Arbeiten über den Wirkungsmechanismus von Antioxidantien in Kohlenwasserstoffpolymeren unter Sauerstoffmangel wurde die Abfangreaktion des Modellradikals 1-Cyano-1-methylethyl (R°) mit N-Isopropyl-N′-phenyl-1,4-phenylendiamin (Ia) und seinem Oxidationsprodukt IIa untersucht. Reines Ia und IIa reagieren kaum mit R′, eine Mischung aus beiden ist jedoch ein effektiver Fänger fur R′, wobei R′ entweder am Stickstoffatom zwischen den aromatischen Ringen unter Bildung von VIa gebunden wird, oder unter Substitution mit dem Phenylenring reagiert, wobei VIIIa entsteht. Verbindung VIa ist labil, bei Vulkanisationstemperatur spaltet sie im neutralen Medium Olefin unter Regenerierung von Ia ab. In Gegenwart von Säuren lauft diese Reaktion auch bei niedrigerer Temperatur ab. Im Produkt VIIIa ist R′ fest gebunden, durch die Nitrilgruppe tritt jedoch eine säurekatalysierte Cyclisierung zum Indolinderivat X ein. Die Bildung von VIIIa ist ein Modell für die Entstehung einer „nichtextrahierbaren Fraktion“ des Antioxidants Ia bei der Stabilisierung von Kohlenwasserstoffpolymeren.
    Notes: In connection with the investigation of the mechanism of antioxidant action of antidegradants in hydrocarbon polymers under the conditions of a relative deficiency of oxygen, scavenging of a model alkyl (1-cyano-1-methylethyl,R°) was studied with Nisopropyl-N′-phenyl-1,4-phenylenediamine (Ia)For abbreviations see p. 11. and its oxidation product, i.e. Nisopropyl-N′-phenyl-1,4-benzoquinonediimine (IIa). While pure Ia and IIa do not react with the radical R° almost at all, their mixture is able to scavenge R° effectively. The reaction is further accelerated with acids. The alkyl R° combines with the antidegradant molecule in two ways, one of which leads to the substitution at the nitrogen atom between the aromatic rings, giving rise to VIa, while the other consists in the substitution of phenylene, leading to VIIIa. The product VIa is labile, and at vulcanization temperatures it readily splits off olefin in a neutral medium, being regenerated to Ia. In the presence of acids this reaction proceeds even at lower temperatures. In the other product, i.e. in VIIIa, the alkyl R° is bound firmly, but due to the presence of the nitrile group, VIIIa is readily cyclized by the effect of acids, and an indoline derivative X is formed. The formation of VIIIa is a model of the formation of an “unextractable fraction” of antidegradant Ia in the stabilization of hydrocarbon polymers. Investigations based on the isolation of reaction products bear at the same time evidence of the possibility of regeneration of an effective antioxidant in the stabilized substrate.
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  • 97
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photochemical degradation of polymers (commonly known as UV degradation) takes place in two stages: First, there is the primary process comprising the rapid formation of radicals caused by quanta of visible light; this involves the dissociation of polymer chain molecules and/or the activation of polymer chain molecules respectively of additives, colorants and impurities contained in the polymer. The secondary process consists in oxidation reactions with singulett-oxygen generated by energy-transfer and/or between the polymer radicals thus formed and adsorbed oxygen, as a result of which gradual degradation of the polymer takes place.An investigation of these individual reactions using a combination of selected physical test methods leads to an unterstanding of the entire reaction sequence involved in photo-oxidative degradation. This knowledge provides a basis for systematically improving the weather-resistance of polymers by modifying their basic polymeric structure or through the controlled use of UV absorbers, quenchers, radical interceptors and antioxidants.The physical test methods themselves are divided into two categories: techniques used for investigating the primary processes (ultra short-time spectroscopy, ESR) and those used to investigate the secondary processes (XPS, FT-IR, UV/VIS et al.).With pigmented polymers, attention is focussed on borderline cases in the use of photoactive and photoinactive pigments: as a result of “photocatalytic oxidation”, photoactive pigments (e.g. TiO2 anatase) lead to additional degradation reactions which take place at the same time as the UV degradation reaction. Photoinactive pigments (e.g. high-grade TiO2-rutile and iron oxide pigments), on the other hand, exhibit negligible or no photocatalytic oxidation and, by absorbing UV radiation, provides better protection for the polymer against UV degradation.This paper gives an overview of the above-mentioned physical methods of investigating primary and secondary photochemical processes, taking a thermoplastic material (Polycarbonate) as an example. A description is also given of the photocatalytic oxidation reations which can take place if pigmented polymers are used, and there is a discussion of the degradation-inhibiting effects of inorganic pigments.
    Additional Material: 7 Ill.
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  • 98
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The aim of the present work is to predict the warehouse storage life of polyethylene low-density, polyethylene high-density and polystyrene impact-resistent, using the method of temperature-time superposition. The properties, most representative for thermal ageing, are the relative elongation at break for polyethylene and the impact resistance for polystyrene. The validity of the predicted shelf-life is verified by estimating the change of these properties under real conditions of warehouse storage.
    Additional Material: 3 Ill.
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  • 99
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A commercial type of impact-resistant polystyrene was investigated. Two types of antioxidants, Irganox 245 and Irganox PS-800 were added to polystyrene in ammounts of 0,05 to 0.20%. Films, dumbbells and straight test pieces were subjected to thermal and u.v. ageing. Films of 250 μ thickness were thermally treated at 100°C and separately u.v. irradiated at 360 nm for 24, 72, 120 and 168 hours. Dumbbells and straight test pieces were only thermally aged at 100°C for 7, 14, 21, 28 and 35 days. Mechanical properties were determined. The spectra of samples were recorded using Perkin-Elmer, model 1750 FTIR and Perkin-Elmer data station 7700. Colour changes of all dumbbells were measured using Elrepho apparatus in u.v.-visible region. (Changes of the content of carbonyl and hydroxyl groups, as well as of polybutadiene (PB) unsaturation in films were recorded on i.r. spektrophotometer Perkin-Elmer 257 between 4000 and 625 cm-1 and were published in the first part of this study1).
    Additional Material: 7 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 181 (1990), S. 85-91 
    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: Formstoffe aus aromatischen Polyepoxiden, aromatischen Polyaminen mit hochtemperaturbeständigen Strukturelementen sowie pulverförmigen Füllstoffen besitzen hervorragende Eigenschaften, wie hohe Glasübergangstemperatur, hohemechanische Festigkeit, kleinen thermischen Ausdehnungskoeffizienten und Schwerbrennbarkeit ohne Zugabe von Flammschutzmitteln. Über die Synthese dieser aromatischen Polyamine, die Herstellung und Verarbeitung der Niederdruckpreßmassen sowie die Eigenschaften der Formstoffe wird berichtet.
    Notes: Moulded materials produced from aromatic epoxide resins, aromatic polyamines with high-temperature-resistant structure units and powdered mineral fillers possess outstanding properties like high glass transition temperatures, high mechanical strength, low linear thermal expansion coefficient, and reduced flammability without the addition of flame retardants. An account is given of the synthesis of aromatic polyamines, the preparation and working of moulding materials and the properties of the finished products.
    Additional Material: 2 Ill.
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