37,540 research outputs found
Mixed d-f Block Single-Molecule Toroics
No full textSingle Molecule Toroics pp 15–66Cite as
Mixed d-f Block Single-Molecule Toroics
Keith S. Murray, Stuart K. Langley, Kuduva R. Vignesh, Gopalan Rajaraman, Kieran Hymas & Alessandro Soncini
Chapter
First Online: 24 November 2022
3 Accesses
Abstract
In this chapter, we focus on the single-molecule toroidal (SMT) behaviour of a family of “double dysprosium triangle” heptanuclear species which contain a bridging d-block M(III) or a p-block M(III) ion. They are of general formula [MIIIDyIII 6(OH)8(o-tol)12(NO3)(MeOH)5]∙3MeOH, labelled MDy 6, where o-tol = o-toluate. The parent compound has M = Cr, with subsequent family members having M = Mn, Fe, Co and Al, the latter two having diamagnetic M(III) centres. This heptanuclear family could also be made using chloride as counter-anion rather than nitrate, the molecular structures being similar to the nitrates though the unit cells are different. The LnIII ion could also be varied to include Tb, Ho and Er and, thus, allow exploration of SMT behaviour in non-Dy analogues. The syntheses, structures and magnetic and EPR properties are described, starting with the parent CrDy 6. Theoretical calculations are described in detail, with MOLCAS methods employed to determine anisotropy directions, blocking barriers and relaxation effects and a newly developed model used to calculate magnetically coupled toroidal states and the role of these states in spin dynamics. The direct simulation of the micro-Squid magnetic hysteresis loops of all family members is described as well as that of the original Dy 3 material. Toroido-structural correlations are presented with strategies developed to optimize the important ferrotoroidic coupling between Dy3 triangles in these heptanuclear toroidal species. Finally, we give a brief summary of SMT behaviour in ring-shaped 3d-4f toroidal species
Ferrotoroidic ground state in a heterometallic {CrIIIDyIII6} complex displaying slow magnetic relaxation
No full textToroidal quantum states are most promising for building quantum computing and information storage devices, as they are insensitive to homogeneous magnetic fields, but interact with charge and spin currents, allowing this moment to be manipulated purely by electrical means. Coupling molecular toroids into larger toroidal moments via ferrotoroidic interactions can be pivotal not only to enhance ground state toroidicity, but also to develop materials displaying ferrotoroidic ordered phases, which sustain linear magneto-electric coupling and multiferroic behavior. However, engineering ferrotoroidic coupling is known to be a challenging task. Here we have isolated a {CrIIIDyIII6} complex that exhibits the much sought-after ferrotoroidic ground state with an enhanced toroidal moment, solely arising from intramolecular dipolar interactions. Moreover, a theoretical analysis of the observed sub-Kelvin zero-field hysteretic spin dynamics of {CrIIIDyIII6} reveals the pivotal role played by ferrotoroidic states in slowing down the magnetic relaxation, in spite of large calculated single-ion quantum tunneling rates
Depolarization and decreased surface expression of K+ channels contribute to NSAID-inhibition of intestinal restitution
No full textNon-steroidal anti-inflammatory drugs (NSAIDs) contribute to gastrointestinal ulcer formation by inhibiting epithelial cell migration and mucosal restitution; however, the drug-affected signaling pathways are poorly defined. We investigated whether NSAID inhibition of intestinal epithelial migration is associated with depletion of intracellular polyamines, depolarization of membrane potential (Em) and altered surface expression of K+ channels. Epithelial cell migration in response to the wounding of confluent IEC-6 and IEC-Cdx2 monolayers was reduced by indomethacin (100μM), phenylbutazone (100μM) and NS-398 (100μM) but not by SC-560 (1μM). NSAID-inhibition of intestinal cell migration was not associated with depletion of intracellular polyamines. Treatment of IEC-6 and IEC-Cdx2 cells with indomethacin, phenylbutazone and NS-398 induced significant depolarization of Em, whereas treatment with SC-560 had no effect on Em. The Em of IEC-Cdx2 cells was: −38.5±1.8mV under control conditions; −35.9±1.6mV after treatment with SC-560; −18.8±1.2mV after treatment with indomethacin; and −23.7±1.4mV after treatment with NS-398. Whereas SC-560 had no significant effects on the total cellular expression of Kv1.4 channel protein, indomethacin and NS-398 decreased not only the total cellular expression of Kv1.4, but also the cell surface expression of both Kv1.4 and Kv1.6 channel subunits in IEC-Cdx2. Both Kv1.4 and Kv1.6 channel proteins were immunoprecipitated by Kv1.4 antibody from IEC-Cdx2 lysates, indicating that these subunits co-assemble to form heteromeric Kv channels. These results suggest that NSAID inhibition of epithelial cell migration is independent of polyamine-depletion, and is associated with depolarization of Em and decreased surface expression of heteromeric Kv1 channels.ID: S0006295207001931; M3: Article; Accession Number: S0006295207001931; Author: L.C. Freeman (b); Author: D.F. Narvaez (a); Author: A. McCoy (a); Author: F.B. von Stein (c); Author: S. Young (b); Author: K. Silver (a); Author: S. Ganta (b); Author: D. Koch (b); Author: R. Hunter (b); Author: R.F. Gilmour (c); Author: J.D. Lillich (a, ⁎); Affiliation: Department of Clinical Sciences, Kansas State University, Manhattan, KS 66506, United States; Affiliation: Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, United States; Affiliation: Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, United States; Keyword: Non-steroidal anti-inflammatory drugs; Keyword: Intestinal epithelial cells; Keyword: Membrane potential; Keyword: Potassium channels; Number of Pages: 12; Language: English;Source type: Electronic(1)http://search.ebscohost.com/login.aspx?direct=true&db=edselp&AN=S0006295207001931&site=eds-live&scope=sit
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
Correction to: Bican, R., Christensen, C., Fallieras, K., Sagester, G., O’Rourke, S., Byars, M., & Tanner, K. (2021). Rapid Implementation of Telerehabilitation for Pediatric Patients During COVID-19
No full textCorrection to: Bican, R., Christensen, C., Fallieras, K., Sagester, G., O’Rourke, S., Byars, M., & Tanner, K. (2021). Rapid Implementation of Telerehabilitation for Pediatric Patients During COVID-19. International Journal of Telerehabilitation, 13(1). https://doi.org/10.5195/ijt.2021.6371
The affiliation for each author was incorrectly stated as: Physical Medicine & Rehabilitation, Children’s Minnesota, Minneapolis, Minnesota, USA
The correct affiliation for each author is: Clinical Therapies, Nationwide Children’s Hospital, Columbus, Ohio, USA
The metadata for the original article has been corrected
The Reconciliation of the r-K, and C-S-R-Models for Life-History Strategies
No full textAbstract. The author attempts to accomplish a reconciliation of the r-K and C-S-R models to identify life-history strategies. He mapped the primary and secondary strategies of the latter model in the linear r-K continuum, using his algorithm COMPTO, for multi-attribute decision--making. He proposes a reinterpretation of the r-K model that accommodates the seven life--history strategies depicted by the C-S-R model. Key words: C-S-R model; epistemic reconciliation; life-history strategy; r-K model Uma Reconciliação dos Modelos r-K e C-S-R para as Estratégias Bionómicas Sumário. O autor propõe uma reconciliação dos modelos r-K e C-S-R, para as estratégias bionómicas. Faz o mapeamento das estratégias primárias e secundárias do segundo modelo no contínuo linear r-K, recorrendo ao seu algoritmo COMPTO, para tomada de decisão em situações de atributos múltiplos. Apresenta uma reinterpretação do contínuo r-K que acomoda as sete estratégias bionómicas do modelo C-S-R. Palavras-chave: estratégias bionómicas; modelo C-S-R; modelo r-K; reconciliação epistémica Une Réconciliation des Modèles r-K et C-S-R pour les Stratégies Biologiques Résumé. L'auteur propose une réconciliation des modèles r-K et C-S-R pour les stratégies biologiques. Il fait la transposition des stratégies primaires et secondaires du modèle C-S-R dans le continuum linéaire r-K, utilisant son algorithme COMPTO. Il présente une réinterpréta-tion du continuum r-K qui accommode les sept stratégies biologiques du modèle C-S-R
Intermittency in Weak Magnetohydrodynamic Turbulence
No full textThree-dimensional incompressible magnetohydrodynamic (MHD) turbulence with a strong uniform magnetic field b0 may be governed by the regime of weak turbulence. At leading order, it is known that the asymptotic regime of weak MHD turbulence is achieved via three-wave resonant interactions with the scattering of two of these waves on a third/2D mode for which k//=0. For zero cross-helicity, the expected exact solution is an energy spectrum in . Higher-order statistics has, however, never been reported in the literature. Therefore, we have recently investigated this question with high resolution direct numerical simulations (Meyrand et al., 2014). We found the presence of strong intermittency when the vector separation of structure functions is taken transverse to b0. This result may be explained by the influence of the 2D modes whose regime belongs to strong turbulence. In addition to shed light on the origin of this intermittency, we derived a log-Poisson law, , which fits perfectly the data and highlights the important role of parallel current sheets
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Discriminating ferrotoroidic from antiferrotoroidic ground states using a 3d quantum spin sensor
No full textMolecular toroidal states have come to the forefront as candidates for next-generation quantum information devices owing to their bistability and protection from weak, short-range magnetic interactions. The protection offered by these non-magnetic vortex spin states proves to be a double-edged sword as inferring their existence in a molecular system has yet to be achieved through experimental means alone. Here, we investigate the anomalous, sickle-shaped, single-crystal magnetisation profile arising in μ-SQUID measurements of a novel CrDy3 molecule. Theoretical modelling supported by ab initio calculations demonstrates that the weak field CrDy3 spin dynamics is resultant from quantum superposition of the CrIII spin states determined by three competing interactions: (i) the alignment of the CrIII magnetic moment to the external magnetic field, (ii) the zero-field splitting of the CrIII ground quartet, and (iii) coupling to the remnant magnetisation of the toroidal ground state in the Dy3 triangle. If zero-field splitting of the central transition metal ion is quenched, it operates as a quantum spin sensor, which can be exploited to experimentally discriminate between ferrotoroidic and antiferrotoroidic ground states in MDy6 double triangle complexes through electron paramagnetic resonance experiments and single-crystal magnetisation measurements with a restricted field sweeping domain
- …
