Observation of Large Topologically Trivial Fermi-Arcs in the Candidate Type-II Weyl Semimetal WTe2

We report angle-resolved photoemission experiments resolving the distinct electronic structure of the inequivalent top and bottom (001) surfaces of WTe2. On both surfaces, we identify a surface state that forms a large Fermi-arc emerging out of the bulk electron pocket. Using surface electronic structure calculations, we show that these Fermi arcs are topologically trivial and that their existence is independent of the presence of type-II Weyl points in the bulk band structure. This implies that the observation of surface Fermi arcs alone does not allow the identification of WTe2 as a topological Weyl semimetal. We further use the identification of the two different surfaces to clarify the number of Fermi surface sheets in WTe2.Comment: Accepted in Physical Review B Rapid Communication on 16 Aug 201

Persistence of antiferromagnetic order upon La substitution in the 4d44d^4 Mott insulator Ca2_2RuO4_4

The chemical and magnetic structures of the series of compounds Ca$_{2-x}$La$_x$RuO$_4$ [$x = 0$, $0.05(1)$, $0.07(1)$, $0.12(1)$] have been investigated using neutron diffraction and resonant elastic x-ray scattering. Upon La doping, the low temperature S-Pbca space group of the parent compound is retained in all insulating samples [$x\leq0.07(1)$], but with significant changes to the atomic positions within the unit cell. These changes can be characterised in terms of the local RuO$_6$ octahedral coordination: with increasing doping the structure, crudely speaking, evolves from an orthorhombic unit cell with compressed octahedra to a quasi-tetragonal unit cell with elongated ones. The magnetic structure on the other hand, is found to be robust, with the basic $k=(0,0,0)$, $b$-axis antiferromagnetic order of the parent compound preserved below the critical La doping concentration of $x\approx0.11$. The only effects of La doping on the magnetic structure are to suppress the A-centred mode, favouring the B mode instead, and to reduce the N\'{e}el temperature somewhat. Our results are discussed with reference to previous experimental reports on the effects of cation substitution on the $d^4$ Mott insulator Ca$_2$RuO$_4$, as well as with regard to theoretical studies on the evolution of its electronic and magnetic structure. In particular, our results rule out the presence of a proposed ferromagnetic phase, and suggest that the structural effects associated with La substitution play an important role in the physics of the system.Comment: 10 pages, 9 figure

Self-assembly of oriented antibody-decorated metal–organic framework nanocrystals for active-targeting applications

Vol. 34(21) pp 2106607-1 - 2106607-7Antibody (Ab)-targeted nanoparticles are becoming increasingly important for precision medicine. By controlling the Ab orientation, targeting properties can be enhanced; however, to afford such an ordered configuration, cumbersome chemical functionalization protocols are usually required. This aspect limits the progress of Abs-nanoparticles toward nanomedicine translation. Herein, a novel one-step synthesis of oriented monoclonal Ab-decorated metal-organic framework (MOF) nanocrystals is presented. The crystallization of a zinc-based MOF, Zn₂(mIM₂(CO₃), from a solution of Zn²⁺ and 2-methylimidazole (mIM), is triggered by the fragment crystallizable (Fc) region of the Ab. This selective growth yields biocomposites with oriented Abs on the MOF nanocrystals (MOF*Ab): the Fc regions are partially inserted within the MOF surface and the antibody-binding regions protrude from the MOF surface toward the target. This ordered configuration imparts antibody-antigen recognition properties to the biocomposite and shows preserved target binding when compared to the parental antibodies. Next, the biosensing performance of the system is tested by loading MOF*Ab with luminescent quantum dots (QD). The targeting efficiency of the QD-containing MOF*Ab is again, fully preserved. The present work represents a simple self-assembly approach for the fabrication of antibody-decorated MOF nanocrystals with broad potential for sensing, diagnostic imaging, and targeted drug delivery.Karen Alt, Francesco Carraro, Edwina Jap, Mercedes Linares-Moreau, Raffaele Riccò, Marcello Righetto, Marco Bogar, Heinz Amenitsch, Rania A. Hashad, Christian Doonan, Christoph E. Hagemeyer, and Paolo Falcar

In situ strain tuning of the metal-insulator-transition of Ca2RuO4 in angle-resolved photoemission experiments

Pressure plays a key role in the study of quantum materials. Its application in angle resolved photoemission (ARPES) studies, however, has so far been limited. Here, we report the evolution of the k-space electronic structure of bulk Ca2RuO4, lightly doped with Pr, under uniaxial strain. Using ultrathin plate-like crystals, we achieve uniaxial strain levels up to -4.1%, sufficient to suppress the insulating Mott phase and access the previously unexplored electronic structure of the metallic state at low temperature. ARPES experiments performed while tuning the uniaxial strain reveal that metallicity emerges from a marked redistribution of charge within the Ru t2g shell, accompanied by a sudden collapse of the spectral weight in the lower Hubbard band and the emergence of a well-defined Fermi surface which is devoid of pseudogaps. Our results highlight the profound roles of lattice energetics and of the multiorbital nature of Ca2RuO4 in this archetypal Mott transition and open new perspectives for spectroscopic measurements

Predicting needlestick and sharps injuries in nursing students: Development of the SNNIP scale

Aim: To develop an instrument to investigate knowledge and predictive factors of needlestick and sharps injuries (NSIs) in nursing students during clinical placements. Design: Instrument development and cross-sectional study for psychometric testing. Methods: A self-administered instrument including demographic data, injury epidemiology and predictive factors of NSIs was developed between October 2018–January 2019. Content validity was assessed by a panel of experts. The instrument's factor structure and discriminant validity were explored using principal components analysis. The STROBE guidelines were followed. Results: Evidence of content validity was found (S-CVI 0.75; I-CVI 0.50–1.00). A three-factor structure was shown by exploratory factor analysis. Of the 238 participants, 39% had been injured at least once, of which 67.3% in the second year. Higher perceptions of “personal exposure” (4.06, SD 3.78) were reported by third-year students. Higher scores for “perceived benefits” of preventive behaviours (13.6, SD 1.46) were reported by second-year students

Epistemologie der Erziehungswissenschaft: Dilemmas, Fragen, mögliche Lösungen

U radu se polazi od tvrdnje da su epistemološke karakteristike temeljne odrednice znanstvenog digniteta znanosti. Na osnovi kritičke analize epistemoloških karakteristika pedagogije upozorava se na upitnost njezina znanstvenog digniteta. Navedena se tvrdnja obrazlaže odgovorima na nekoliko pitanja: Je li razina razvijenosti suvremenog društva nametnula potrebu redefiniranja semantičkog određenja osnovnih pojmova i pedagogije same? Može li se pedagogija koja desetljećima nije promijenila svoj osnovni teorijski, epistemološko-metodologijski koncept, smatrati suvremenom? Ima li Hrvatska suvremenu pedagogiju ili je riječ o tradicionalnoj (zastarjeloj) pedagogiji? Što je osnovna funkcija pedagogije? Je li pedagogija znanost o odgoju, znanost o odgoju i obrazovanju ili znanost o osposobljavanju ljudi? Jesu li cilj i zadaci pedagogijske znanosti jednoznačno određeni? Na kraju se navode moguća rješenja. Predlažu se nova suvremena jednoznačna semantička određenja temeljnih pojmova i s tog se aspekta utvrđuje osnovna funkcija pedagogije i kao znanstvene i kao praktične discipline, kao teorije osposobljavanja.The argumentation presented in the paper starts from the premise that epistemological characteristics are the elements that science builds its scientific dignity on. A critical analysis of the epistemological characteristics of pedagogy has led the author to question its scientific dignity. The doubts stated in the paper are raised by several questions. Is the level of development of the modern society forcing us to redefine the semantic components of basic pedagogical terms and pedagogy itself? Can pedagogy, which has not changed its basic theoretical, epistemological and methodological concept for decades, really be termed contemporary? Is pedagogy in Croatia contemporary or do we still practice the traditional (and outdated) form of pedagogy? What is the main function of pedagogy? Is pedagogy the science of education, the science of education and development, or the science of human resources development? Are the goals and tasks of pedagogy as a science unambiguously set? Finally, the author suggests possible answers, advocating new, modern and unambiguous semantic definitions of the basic terms, thus determining the primary function of pedagogy as both scientific and practical discipline – a human resources development theory.Den Ausgangspunkt dieser Arbeit bildet die These, dass epistemologische Charakteristiken die wissenschaftliche Dignität jeder Wissenschaft begründen. Anhand einer kritischen Analyse von epistemologischen Charakteristiken der Erziehungswissenschaft wird auf die Fragwürdigkeit ihrer wissenschaftlichen Dignität hingewiesen, Die angeführte Behauptung wird durch Antworten auf einige Fragen erklärt: Macht die Entwicklungsebene der modernen Gesellschaft eine Redefinition der semantischen Bestimmungen pädagogischer Grundbegriffe und der Pädagogik selbst erforderlichß Kann die Erziehungswissenschaft, die seit Jahrzehnten ihr theoretisches, epistemologisch – methodologisches Grundkonzept nicht geändert hat, als modern gelten? Hat Kroatien eine moderne Erziehungswissenschaft oder ob es um eine traditionelle (veraltete) Pädagogik handelt? Was ist die Grundaufgabe der Pädagogik? Ist die Pädagogik eine Wissenschaft über die Erziehung, Wissenschaft über die Erziehung und Bildung oder Wissenschaft über die Befähigung der Menschen? Lassen sich das Ziel und die Aufgaben der Erziehungswissenschaft eindeutig bestimmen? Am Ende werden mögliche Lösungen angeführt. Vorgeschlagen werden neue moderne eindeutige semantische Bestimmungen der pädagogischen Grundbegriffe und von diesem Standpunkt aus Grundaufgaben der Pädagogik sowohl als wissenschaftlicher als auch praktischer Disziplin sowie einer Befähigungstheorie festgelegt