Single Crystal Growth of Ga2(SexTe1-x)3 Semiconductors and Defect Studies via Positron Annihilation Spectroscopy

Small single crystals of Ga2(SexTe1-x)3 semiconductors, for x = 0.1, 0.2, 0.3, were obtained via modified Bridgman growth techniques. High-resolution powder x-ray diffractometry confirms a zincblende cubic structure, with additional satellite peaks observed near the (111) Bragg line. This suggests the presence of ordered vacancy planes along the [111] direction that have been previously observed in Ga2Te3. Defect studies via positron annihilation spectroscopy show an average positron lifetime of ~400 ps in bulk as-grown specimens. Such a large lifetime suggests that the positron annihilation sites in these materials are dominated by defects. Moreover, analyzing the electron momenta via coincidence Doppler broadening measurements suggests a strong presence of large open-volume defects, likely to be vacancy clusters or voids.Comment: 4 pages, 5 figure

A monotone multigrid solver for two body contact problems in biomechanics

The purpose of the paper is to apply monotone multigrid methods to static and dynamic biomechanical contact problems. In space, a finite element method involving a mortar discretization of the contact conditions is used. In time, a new contact-stabilized Newmark scheme is presented. Numerical experiments for a two body Hertzian contact problem and a biomechanical application are reported

Synergistic icephobic behaviour of swollen nitrile butadiene rubber graphene and/or carbon nanotube composites

Spontaneous change of adhesion of solidifying liquid on surfaces is of significant importance in materials technology where it finds applications such as anti-icing components operating in extreme environments like those of seals. In this work, nitrile butadiene rubber (NBR) composites reinforced with graphene, carbon nanotubes, and a mix of them after immersion in several fluids, experienced both a swelling and a reduction of the cross-link density that reduces ice adhesion, being this effect more evident for graphene containing samples. These results have been rationalized via a first principles atomistic modellization of interfaces formed by ice water of increasing thickness and graphene and scaling laws from fracture mechanics, revealing a clear synergy between swelling and nanocarbon phase in the icephobic nature of the composite, dictated by a competition between elastic modulus and adsorption energy. These findings could find an upscale in component validation readily applied to different areas where de-icing demands handling of large amount of environmental harmful agents.GG wants to thank CINECA [grant number HP10CN7DI0] and acknowledge PRACE for awarding us access to resource Marconi based in Italy at CINECA [Grant number Pra14_3664]. G.G. is similarly grateful to CARIT [grant number FCARITR17FR]” for supporting this research. MALM thanks the support from the MINECO [grant number MAT2016- 81138-R]. NMP is supported by the European Commission under the Graphene Flagship Core2 [WP14 “Composites” grant number 785219] and FET Proactive “Neurofibres” [grant number 732344]. NMP is supported by theItalian Ministry of Education, University and Research (MIUR) under the “Departments of Excellence” grant L.232/2016. LV is supported by the European Commission under the Graphene Flagship Core2 [WP14 “Composites” grant number 785219]. LV and GG rea supported by the Italian Ministry of Education, University and Research (MIUR) under the “Departments of Excellence” grant L.232/2016Peer Reviewe

The design, construction, and commissioning of the KATRIN experiment

The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [1] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [2]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns

Feint Lines: Notes on the Creation of a Skateboard Choreography

Magnetic fields on a range of scales play a large role in the ecosystems of galaxies, both in the galactic disk and in the extended layers of gas away from the plane. Observing magnetic field strength, structure and orientation is complex, and necessarily indirect. Observational data of magnetic fields in the halo of the Milky Way are scarce, and non-conclusive about the large-scale structure of the field. In external galaxies, various large-scale configurations of magnetic fields are measured, but many uncertainties about exact configurations and their origin remain. There is a strong interaction between magnetic fields and other components in the interstellar medium such as ionized and neutral gas and cosmic rays. The energy densities of these components are comparable on large scales, indicating that magnetic fields are not passive tracers but that magnetic field feedback on the other interstellar medium components needs to be taken into account.Comment: 13 pages, 7 figures. Accepted in Space Science Review

Production of low-calorie structured lipids from spent coffee grounds or olive pomace crude oils catalyzed by immobilized lipase in magnetic nanoparticles

In this study, crude oils extracted from spent coffee grounds (SCG) and olive pomace (OP) were used as raw-material to synthesize low-calorie triacylglycerols, either by acidolysis with capric acid, or by interesterification with ethyl caprate, in solvent-free media, catalyzed by sn-1,3 regioselective lipases. The Rhizopus oryzae lipase (ROL) was immobilized in magnetite nanoparticles (MNP\u2013ROL) and tested as novel biocatalyst. MNP-ROL performance was compared with that of the commercial immobilized Thermomyces lanuginosus lipase (Lipozyme TL IM). For both oils, Lipozyme TL IM preferred interesterification over acidolysis. MNP-ROL catalyzed reactions were faster and acidolysis was preferred with yields of c.a. 50% new triacylglycerols after 3 h acidolysis of OP or SCG oils. MNP-ROL was very stable following the Sadana deactivation model with half-lives of 163 h and 220 h when reused in batch acidolysis and interesterification of OP oil, respectively

Exploring Tracer Information and Model Framework Trade‐offs to Improve Estimation of Stream Transient Storage Processes

International audienceNovel observation techniques (e.g., smart tracers) for characterizing coupled hydrological and biogeochemical processes are improving understanding of stream network transport and transformation dynamics. In turn, these observations are thought to enable increasingly sophisticated representations within transient storage models (TSMs). However, TSM parameter estimation is prone to issues with insensitivity and equifinality, which grow as parameters are added to model formulations. Currently, it is unclear whether (or not) observations from different tracers may lead to greater process inference and reduced parameter uncertainty in the context of TSM. Herein, we aim to unravel the role of in‐stream processes alongside metabolically active (MATS) and inactive storage zones (MITS) using variable TSM formulations. Models with one (1SZ) and two storage zones (2SZ) and with and without reactivity were applied to simulate conservative and smart tracer observations obtained experimentally for two reaches with differing morphologies. As we show, smart tracers are unsurprisingly superior to conservative tracers when it comes to partitioning MITS and MATS. However, when transient storage is lumped within a 1SZ formulation, little improvement in parameter uncertainty is gained by using a smart tracer, suggesting the addition of observations should scale with model complexity. Importantly, our work identifies several inconsistencies and open questions related to reconciling time scales of tracer observation with conceptual processes (parameters) estimated within TSM. Approaching TSM with multiple models and tracer observations may be key to gaining improved insight into transient storage simulation as well as advancing feedback loops between models and observations within hydrologic science