Титульні сторінки та зміст

Sr and Nd isotopes were determined using new thermal ionisation mass spectrometry (TIMS) techniques for a suite of 21 olivine-hosted (85-92mol% Fo) melt inclusions selected from potassic and ultra-potassic lavas from the Italian peninsula. Sr isotopes were measured using default 1

Coupled trace element and Sr-Nd-(Pb) isotopes in olivine-hosted melt inclusions from the Mariana arc

The Mariana arc forms part of the 2500 km Izu–Bonin–Mariana arc system caused by westward subduction of the Pacific Plate beneath the Philippine Sea Plate over the last ~45 Myr. The magmatism produced in this comparatively simple arc setting records a moderate flux of fluids and sediments from the downgoing plate, however, the low MgO (<6 wt.%) of the lavas imply that magma mixing, crystal fractionation and crustal assimilation mask the primitive melt compositions. Olivine-hosted melt inclusions (MIs), in contrast, provide access to melt trapped deep in the magmatic plumbing system allowing more precise determination of the nature and quantity of recycled components. Here we analyse coupled trace element and Sr-Nd(-Pb) isotope compositions of olivine-hosted MIs in five samples from four islands within the Central Island province: Agrigan (AGR2, AGR6), Pagan (PAG3), Guguan (GUG6) and Sarigan (SAG1). Bulk rock MgO contents range from 4 to 5.7 wt.% [1]. We specifically target melt inclusions in olivine phenocrysts with the highest fortsterite content (Fo = Mg/(Mg+Fe)*100): AGR: 80-86; PAG: 76-81; GUG: 76-88; SAG: 84-88 mol%. Trace element contents and ratios of the selected MIs record marked differences between islands and show larger variability compared to published bulk rock and MI compositions [2]. Ba/La and Th/Nb or La/Sm ratios – indicators of slab fluids versus sediment melts, respectively – confirm that Guguan inclusions are dominated by a fluid component whereas Agrigan and Sarigan reflect a larger sediment contribution. Pagan inclusions show intermediate compositions and a restricted range indicating the influence of both fluids and sediments. Sr-Nd-(Pb) isotope compositions of individual and pooled melt inclusions will be determined by wet chemistry and TIMS techniques using 10^13 Ω amplifier technology [3] to further identify and quantify the recycled components. [1] Elliott et al. (1997). Journal of Geophysical Research, 102: 14991-15019. [2] Kent & Elliott (2002). Chemical Geology, 183: 263-286. [3] Koornneef et al. (2019). Nature Communications 10, 323

Эффективность комбинированных криоконсервантов, содержащих глицерин или 1,2-пропандиол, при замораживании эритроцитов

Исследовали осмотические свойства эритроцитов, замороженных в комбинированных криоконсервантах, содержащих полимерные непроникающие (декстран, полиэтиленгликоль) и проникающие (глицерин, 1,2-пропандиол) криопротекторы. Установлено, что в эритроцитах, замороженных-отогретых в среде с полимерами, отмечается повышение скорости потока ионов Н+ и осмотической хрупкости в среде, содержащей 0,45–0,9% NaCl. Для сохранения осмотических свойств замороженных- отогретых клеток достаточно включить в среду глицерин или 1,2-пропандиол (1,2-ПД) в концентрации 5%. Полученные результаты позволяют предположить, что криопротекторная эффективность комбинированных криоконсервантов, содержащих непроникающие и проникающие криопротекторы, определяется вкладом различных по механизму действия криозащитных компонентов в суммарную защитную эффективность при замораживании и ослаблением постгипертонического стресса на клетки при размораживании.Досліджували осмотичні властивості еритроцитів, заморожених-відігрітих у комбінованих кріоконсервантах, які містять полімерні непроникаючі (декстран, поліетиленгліколь) і проникаючі (гліцерин, 1,2-пропандіол) кріопротектори. Встановлено, що в еритроцитах, заморожених-відігрітих у середовищі з полімерами, визначається зростання швидкості потоку іонів Н+ і осмотичної крихкості в середовищі, яке містить 0,45–0,9% NaCl. Для збереження осмотичних властивостей заморожених- відігрітих клітин достатньо включити в середовище гліцерин або 1,2-пропандіол в концентрації 5%. Отримані результати дозволяють припустити, що кріопротекторна ефективність комбінованих кріоконсервантів, які містять непроникаючі і проникаючі кріопротектори, визначається внеском різноманітних за механізмом дії кріозахисних компонентів у сумарну захисну ефективність при заморожуванні та послабленням постгіпертонічного стресу на клітини при розморожуванні.The osmotic properties of erythrocytes frozen-thawed in combined cryopreservatives, containing polymeric non-penetrating (dextran, polyethylene glycol) and penetrating (glycerol, 1,2-propane diol) cryoprotectants were studied. It was established that in erythrocytes frozen-thawed in the presence of polymers the increasing of H+ ion flow rate and osmotic fragility in the environment with 0.45–0.9% NaCl was observed. It is sufficient to add 5% glycerol or 1,2-propane diol (1,2-PD) to the medium to preserve osmotic properties of frozen-thawed cells. The obtained results enable to suggest that cryoprotective efficiency of combined cryopreservatives, containing non-penetrating and penetrating cryoprotectants is determined both by the contribution of cryoprotective components differing by action mechanism into th

A holistic provenance and microwear study of pre-colonial jade objects from the Virgin Islands: unravelling mobility networks in the wider Caribbean

Pre-colonial Caribbean jade objects from the National Museum of Denmark Hatt Collection were subjected to a provenance and microwear analysis. Thirty-nine jade celts and bodily ornaments from the US Virgin Islands, i.e., St. Croix, St. Thomas, St. John, and five celts from the West Indies of unknown location, St. Vincent, Cuba and the Dominican Republic were analysed.A comprehensive in-depth examination of jade adornments from St. Croix, combining typo-technological and microwear analysis, is compared to other lithologies used for pre-colonial ornaments. A portable laser ablation system was used to sample jade celts and bodily ornaments on site in a quasi-non-destructive manner. Low-blank trace element and Sr-Nd isotope ratio data were evaluated with a multiclass regression provenance prediction model.This study demonstrates that the pan-Caribbean exchange of jade raw materials, pre-forms or finished objects during the Ceramic Age (400 BC to AD 1492) occurred on a more complex scale than previously thought involving jade sources in Guatemala, eastern Cuba and the northern Dominican Republic. In addition, the study of ornaments recovered from St. Croix reveals use of specific lithologies suggesting stronger ties to Indigenous communities on Puerto Rico than other Lesser Antillean Islands.Material Culture Studie

Extreme differences in 87Sr/86Sr between Samoan lavas and the magmatic olivines they host: Evidence for highly heterogeneous 87Sr/86Sr in the magmatic plumbing system sourcing a single lava

.Investigations of mantle heterogeneity in ocean island basalts (OIB) frequently compare heavy radiogenic isotopes (i.e. 87Sr/86Sr), often measured in whole rock powders, with 3He/4He and δ18O, commonly measured in olivines. However, the 87Sr/86Sr in the olivines, which is dominated by Sr in melt inclusions, may not be in equilibrium with the 87Sr/86Sr in the whole rock. Here we present new 87Sr/86Sr measurements made on Samoan magmatic olivines, where multiple olivine crystals are aggregated for a single isotopic measurement. The olivines host abundant melt inclusions, and yielded relatively large quantities of Sr (13.0 to 100.6 ng) in 19 to 185 mg aliquots of fresh olivine, yielding high Srsample/Srblank ratios (≥ 427). These new data on olivines show that samples can exhibit significant 87Sr/86Sr disequilibrium: in one extreme sample, where the basaltic whole rock 87Sr/86Sr (0.708901) is higher than several different aliquots of aggregate magmatic olivines (0.707385 to 0.707773), the whole rock-olivine 87Sr/86Sr disequilibrium is > 1590 ppm. The 87Sr/86Sr disequilibrium observed between whole rocks and bulk olivines relates to the isotopic disequilibrium between whole rocks and the average 87Sr/86Sr of the population of melt inclusions hosted in the olivines. Therefore, a population of olivines in a Samoan lava must have crystallized from (and trapped melts of) a different 87Sr/86Sr composition than the final erupted lava hosting the olivines. A primary question is how melts with different 87Sr/86Sr can exist in the same magmatic plumbing system and contribute heterogeneous 87Sr/86Sr to a lava and the magmatic olivines it hosts. We explore potential mechanisms for generating heterogeneous melts in magma chambers. The reliance, in part, of chemical geodynamic models of the relationships between isotopic systems measured in whole rocks (87Sr/86Sr) and systems measured in olivines (3He/4He and δ18O) means that whole rock-olivine Sr-isotopic disequilibrium will be important for evaluating relationship among these key isotopic tracer systems. Moving forward, it will be important to evaluate whether whole rock-olivine Sr-isotopic disequilibrium is a pervasive issue in OIB globally

Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

CO2 afvang en opslag is geen alles-in-1 oplossing

Afvang van CO2 bij kolencentrales kan leiden tot een uitwisseling van milieueffecten. Dat suggereert een recente wetenschappelijke studie uitgevoerd door medewerkers van de Universiteit Utrecht. De studie onderzocht het inruilen van CO2 vermindering voor andere milieueffecten, maar ook het ontstaan van win-win situaties voor het milieu. Hiertoe is de hele levenscyclus van het opwekken van elektriciteit in kolencentrales met en zonder CO2 afvang, transport en opslag (CCS) in kaart gebracht. In een zogenaamde levenscyclus analyse worden de ingrepen op het milieu van alle processen van de kolenmijn tot kilowattuur (kWh) ingedeeld naar milieuthema en bij elkaar opgeteld