Search results for " shell"
showing 10 items of 307 documents
Highly fluorescent and photostable organic- and water-soluble CdSe/ZnS core-shell quantum dots capped with thiols
2012
Highly fluorescent organic- and water-soluble CdSe/ZnS core-shell quantum dots (QDs) with thiol ligands chemisorbed on the QD surface were synthesized by the replacement of amine ligands by alkyl thiols under very mild conditions. The QDs exhibited an even greater photostability than the initial core-shell amine capped QDs.
Core‐shell nanoparticles with hyperbranched poly(arylene‐oxindole) interiors
2009
Opracowano synteze wysoce rozgalezionego poli(aryleno-oksyndolu) na drodze reakcji polimeryzacji pochodnej 5-bromoizatyny, a nastepnie modyfikacji terminalnych jednostek izatynowych. Tak przygotowany polimerowy rdzen, charakteryzujący sie stopniem rozgalezienia 100 %, byl substratem do rodnikowej polimeryzacji z przeniesieniem atomu (z ang. ATRP) w reakcji z akrylanem tert-butylu. Otrzymane kopolimery zawierające hydrofobowy rdzen i alkilowe lancuchy zakonczone wolnymi grupami karboksylowymi tworzą sferyczne nanocząstki. Przedstawiono wstepne wyniki badan dotyczących ich wlaściwości fizykochemicznych oraz potencjalnych zastosowan.
Recycling mussel shells as secondary sources in green construction materials: a preliminary assessment
2023
This paper reports the development of novel green bio-composite mortars obtained by reusing mussel shells, a waste from the fish canning industry, as recycled aggregate, used for the first time in total substitution to the traditional sand. It suggests that this is a valid alternative to their usual disposal in landfills because the organic matter is potentially dangerous to humans and the environment. Different waste-based cementitious mixes were tested and compared to a traditional OPC mortar. The manufacturing process was performed at ambient conditions (20 °C, 65% RH) with highly sustainable results and consisted of simple operative steps reproducible in a real building site. The engine…
Ba/Ca ratios in shells of Arctica islandica —Potential environmental proxy and crossdating tool
2017
Abstract Ba/Ca shell time-series of marine bivalves typically show flat background levels which are interrupted by erratic sharp peaks. Evidence from the literature indicates that background Ba/Ca shell ratios broadly reflect salinity conditions. However, the causes for the Ba/Ca shell peaks are still controversial and widely debated although many researchers link these changes to primary productivity, freshwater input or spawning events. The most striking feature is that the Ba/Ca shell peaks are highly synchronous in contemporaneous specimens from the same population. For the first time, we studied Ba/Ca shell in mature and ontogenetically old (up to 251 year-old) specimens of the long-li…
The size and shape of shells used by hermit crabs: A multivariate analysis of Clibanarius erythropus
2009
Shell attributes such as weight and shape affect the reproduction, growth, predator avoidance and behaviour of several hermit crab species. Although the importance of these attributes has been extensively investigated, it is still difficult to assess the relative role of size and shape. Multivariate techniques allow concise and efficient quantitative analysis of these multidimensional properties, and this paper aims to understand their role in determining patterns of hermit crab shell use. To this end, a multivariate approach based on a combination of size-unconstrained (shape) PCA and RDA ordination was used to model the biometrics of southern Mediterranean Clibanarius erythropus populatio…
β Decay of 127Cd and Excited States in 127In
2019
A dedicated spectroscopic study of the β decay of 127Cd was conducted at the IGISOL facility at the University of Jyväskylä. Following high-resolution mass separation in a Penning trap, β−γ−γcoincidences were used to considerably extend the decay scheme of 127In. The β-decaying 3/2+ and 11/2− states in 127Cd have been identified with the 127Cd ground state and the 283-keV isomer. Their respective half-lives have been measured to 0.45(128)s and 0.36(4) s. The experimentally observed βfeeding to excited states of 127In and the decay scheme of 127In are discussed in conjunction with large-scale shell-model calculations. peerReviewed
The gallium anomaly revisited
2019
The gallium anomaly, i.e. the missing electron-neutrino flux from $^{37}$Ar and $^{51}$Cr electron-capture decays as measured by the GALLEX and SAGE solar-neutrino detectors, has been among us already for about two decades. We present here a new estimate of the significance of this anomaly based on cross-section calculations using nuclear shell-model wave functions obtained by exploiting recently developed two-nucleon interactions. The gallium anomaly of the GALLEX and SAGE experiments is found to be smaller than that obtained in previous evaluations, decreasing the significance from 3.0σ to 2.3σ. This result is compatible with the recent indication in favor of short-baseline ν¯e disappeara…
Quantum-state-selective decay spectroscopy of 213Ra
2017
An experimental scheme combining the mass resolving power of a Penning trap with contemporary decay spectroscopy has been established at GSI Darmstadt. The Universal Linear Accelerator (UNILAC) at GSI Darmstadt provided a 48Ca beam impinging on a thin 170Er target foil. Subsequent to velocity filtering of reaction products in the Separator for Heavy Ion reaction Products (SHIP), the nuclear ground state of the 5n evaporation channel 213Ra was mass-selected in SHIPTRAP, and the 213Ra ions were finally transferred into an array of silicon strip detectors surrounded by large composite germanium detectors. Based on comprehensive geant4 simulations and supported by theoretical calculations, the …
Searching for differences in Swift's intermediate GRBs
2010
Gamma-ray bursts are usually classified through their high-energy emission into short-duration and long-duration bursts, which presumably reflect two different types of progenitors. However, it has been shown on statistical grounds that a third, intermediate population is needed in this classification scheme, although an extensive study of the properties of this class has so far not been done. The large amount of follow-up studies generated during the Swift era allows us to have a suficient sample to attempt a study of this third population through the properties of their prompt emission and their afterglows. Our study is focused on a sample of GRBs observed by Swift during its first four y…
Optical illusions in scanning electron micrographs: the case of the eggshell of Acrosternum (Chinavia) marginatum (Hemiptera: Pentatomidae)
2003
Scanning electron microscopy revealed that-as is common in this family of the Hemiptera-the eggs of the green stink bug Acrosternum (Chinavia) marginatum are roughly barrel-shaped and possess at their apical pole a row of slender extensions, the aero-micropylar processes. The outer surface of the eggshell carries hexagonally arranged pits. The analysis of cross-fractured eggshells showed that the pits have slender basal extensions with transverse diaphragms. When scanning electron micrographs of the egg surface of A. marginatum are viewed upside down, the perception flips and the pits appear as elevations to all observers addressed. Thus, we are dealing with an optical illusion, which is kn…