Mononuclear lanthanide complexes with 18-crown-6 ether: synthesis, characterization, magnetic properties, and theoretical studies

A family of lanthanide metal complexes with general formula [Ln(H2O)3(18-crown-6)](ClO4)3 (Ln: TbIII, DyIII, ErIII and YbIII) has been synthesized. Their magnetic properties have been characterized by DC and AC SQUID measurements and analyzed with the help of CASSCF-type calculations. The DyIII and YbIII compounds show slow relaxation of the magnetization under an external magnetic field. The analysis of the dependence of the relaxation time with the temperature and external magnetic field reveals that the main contributions are respectively the quantum tunneling and the Raman term, respectively. The analysis of the beta electron density and electrostatic potentials indicate that the axial ligands (three water molecules) generate a relatively small repulsion with the lanthanide electron density being the reason of the moderate magnetic anisotropy found in these systems

Spin-phonon coupling and slow-magnetic relaxation in pristine ferrocenium

We report the spin dynamic properties of non-substituted ferrocenium complexes. Ferrocenium shows a field-induced single-molecule magnet behaviour in DMF solution while cobaltocene lacks slow spin relaxation neither in powder nor in solution. Multireference quantum mechanical calculations give a non-Aufbau orbital occupation for ferrocenium with small first excitation energy that agrees with the relatively large measured magnetic anisotropy for a transition metal S=1/2 system. The analysis of the spin relaxation shows an important participation of quantum tunnelling, Raman, direct and local-mode mechanisms which depend on temperature and the external field conditions. The calculation of spin-phonon coupling constants for the vibrational modes shows that the first vibrational mode, despite having a low spin-phonon constant, is the most efficient process for the spin relaxation at low temperatures. In such conditions, vibrational modes with higher spin-phonon coupling constants are not populated. Additionally, the vibrational energy of this first mode is in excellent agreement with the experimental fitted value obtained from the local-mode mechanism

Metal-Organic Nanocapsules with Functionalized s-Heptazine Ligands

A metalloorganic capsule was synthesized where the ligand is a derivative of heptazine with three carboxylic groups that are coordinated to CuII cations, forming paddle-wheel motifs. Each nanocapsule is neutral, with 12 CuII centers and 8 ligands adopting a rhombicuboctahedron shape. It has almost 3 nm diameter, and the main intermolecular interactions in the solid are π··· π stacking between the C6N7 heptazine moieties. The nanocapsules can form monolayers deposited on graphite as observed by atomic force microscopy, which confirms their stability in solution

Determination of the motor unit behavior of lumbar erector spinae muscles through surface EMG decomposition technology in healthy female subjects

Introduction: The aims of this study were to determine the motor unit behavior of the erector spinae muscles and to assess whether differences exist between the dominant/non-dominant sides of the back muscles. Methods: Nine healthy women, aged 21.7 years (±0.7), performed a back extension test. Surface electromyographic decomposition data were collected from both sides of the erector spinae and decomposed into individual motor unit action potential trains. The mean firing rate for each motor unit was calculated, and a regression analysis was performed against the corresponding recruitment thresholds. Results: The mean firing rate ranged from 15.9 to 23.9 pulses per second (pps) and 15.8 to 20.6 pps on the dominant and non-dominant sides, respectively. However, the early motor unit potential s of the non-dominant lumbar erector spinae muscles were recruited at a lower firing rate. Conclusions: This technique may further our understanding of individuals with back pain and other underlying neuromuscular diseases

Different topologies in three manganese-μ-azido 1D compounds: magnetic behavior and DFT-quantum Monte Carlo calculations

The syntheses and structural characterization of three new monodimensional azido-bridged manganese(II) complexes with empirical formulae [Mn(N3)2(aminopyz)2]n (1), [Mn(N3)2(4-azpy)2]n (2) and [Mn(N3)2(4-Bzpy)2]n (3) (pyz = pyrazine (1,4-diazine)), 4-azpy = 4-azidopyridine and 4-Bzpy = 4-benzoylpyridine) are reported. 1 is a monodimensional compound with double EO azido bridges, 2 is an alternating monodimensional compound with double end-on and double end-to-end azido bridges in the sequence di-EO-di-EE and 3 is a monodimensional compound with double end-on and double end-to-end azido bridges in the sequence di-EO-di-EO-diEO-di-EO-di-EE. The magnetic properties of 1-3 are reported. Periodic DFT calculations were performed to estimate the J values and quantum Monte Carlo simulations were carried out using the calculated J values to check their accuracy in comparison with the experimental magnetic measurements. From this theoretical analysis, two appealing features of the di-EO Mn(II) compounds can be extracted: first, the exchange coupling becomes more ferromagnetic when the Mn-N-Mn bridging angle becomes larger and the spin density of the bridging nitrogen atoms has an opposite sign to that of the Mn(II) centers

Slow-spin relaxation of a low-spin S = 1/2 FeIII carborane complex

In this communication, we report the first evidence of slow-spin relaxation of a low-spin FeIII carborane complex. Iron S=1/2 complexes showing such behaviour are specially appealing as qubits candidates because they fulfil some of the main requirements to reach long decoherence times: moderate magnetic anisotropy, small spin, metal element mainly with zero-nuclear spin and furthermore, large versatility to introduce chemical modifications

Spirit, mind and body: the archaeology of monastic healing

Archaeology and material culture are used in this chapter to consider how monastic experience responded to illness, ageing and disability. The approach taken is influenced by the material study of religion, which interrogates how bodies and things engage to construct the sensory experience of religion, and by practice-based approaches in archaeology, which examine the active role of space and material culture in shaping religious agency and embodiment. The archaeology of monastic healing focuses on the full spectrum of healing technologies, from managing the body in order to prevent illness, through to the treatment of the sick and preparation of the corpse for burial

NADPH oxidases in cardiovascular disease: insights from in vivo models and clinical studies

NADPH oxidase family enzymes (or NOXs) are the major sources of reactive oxygen species (ROS) that are implicated in the pathophysiology of many cardiovascular diseases. These enzymes appear to be especially important in the modulation of redox-sensitive signalling pathways that underlie key cellular functions such as growth, differentiation, migration and proliferation. Seven distinct members of the family have been identified of which four (namely NOX1, 2, 4 and 5) may have cardiovascular functions. In this article, we review our current understanding of the roles of NOX enzymes in several common cardiovascular disease states, with a focus on data from genetic studies and clinical data where available

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Ligandos Supramoleculares en Complejos Metálicos con Propiedades Físicas Relevantes

[spa] En la primera parte de esta tesis, se basó en la síntesis de ligandos basados en la heptazina y los complejos formados con CuII. Utilizando 2-dipiridilamina para funcionalizar el núcleo de heptazina, (ligando que presenta propiedades fotoquímicas remarkables) se logró crear una caja molecular con tres CuII que se coordinaba a dos ligandos tris(2-dipirilamina)1,5,9-heptazina. Siguiendo en esta línea, se funcionalizó el núcleo de heptazina con piperidina-4-acido carboxílico para formar el ligando tris(piperidina-4-ácido carboxílico)-1,5,9-heptazina, que mediante la coordinación con átomos metálicos CuII se puedo generar un compuesto bastante grande, con un diámetro de 24 Å. Esta caja molecular, se encuentra formada por 8 ligandos y 12 átomos metálicos que forman el compuesto [Cu12(tpach)8(H2O)12]. En la segunda parte de este trabajo, se estudió compuestos magnéticos, que presentan propiedades de imán. Este tipo de moléculas se conocen como imanes unimoleculares, generalmente se denominan SMM por sus siglas en inglés Single Molecule Magnets. El segundo objetivo principal a raíz del descubrimiento realizado por los Profesores Dante Gatteschi y Roberta Sessoli en 1993 en qué una sola molécula presenta una lenta relajación de su magnetización por debajo de una temperatura conocida como temperatura de bloqueo (Tb). En un trabajo realizado por los profesores Jeffrey Long y Jeffrey Rinehard, se reportaron un método en el cual de manera sistemática y cualitativa, se pueden sintetizar imanes unimoleculares basados en lantánidos. Dependiendo de la densidad electrónica del ion lantánido la cual fue definida como forma de achatada (oblato) o alargada (prolato) la anisotropía magnética podría ser máxima, propiedad de la cual depende principalmente la relajación de la magnetización. Parte de esta tesis, se enfocó en esa propuesta publicada por Long y para eso se utilizó compuestos basados en éteres coronas (18-corona-6) y lantánidos (Nd, Tb, Dy, Er y Yb), con la idea de generar compuestos en el que la densidad electrónica del ion lantánido se acomode en el plano ecuatorial del éter corona y posicionar ligandos axiales cargados, para ejercer la mayor repulsión posible, con la idea de obtener una densidad electrónica tipo oblato y maximizar la anisotropía. Siguiendo con la línea de los imanes unimoleculares, se estudió los sistemas con espín ½ sistemas que presentan propiedades para ser usados en computación cuántica como qbits. Se estudió principalmente metalocenos basados en ferricinio y cobaltoceno. De entrada el cobaltoceno debería presentar una relajación lenta de la magnetización, ya que su electrón desapareado se encuentra en un orbital degenerado, que por distorsión de Jahn Teller esa degeneración se rompe obteniéndose un estado excitado de con una diferencia de energía baja, que en el caso de los metales de transición es la fuente de la anisotropía magnética. En el caso del ferricinio, esa energía de excitación era alta, por lo cual no presentaría anisotropía. Los resultados experimentales en solución congelada (separación de centros metálicos) mostraron que el ferricinio poseía relajación de la magnetización y el cobaltoceno no, esto debido a un cambio en la configuración de los orbitales, donde los dos compuestos poseían su electrón desapareado en orbitales degenerados, pero en el caso del cobaltoceno, la distorcion de Jahn Teller, se produce en orbitales antienlazantes (separación de energía mayor, menor anisotropía) en contraparte del ferricionio, en el cual su electron desapareado se encuentra en orbitales de no-enlace (menor distorsión) . Para mejorar las propiedades, se decidió encapsular esta molécula, con dos polisacáridos y ciclodextrina, con la misión de aislar la molécula aún más, para suprimir la interacción con moléculas vecinas, las cuales generan que la relajación lenta sea acelere. Los resultados obtenidos indicaron que las propiedades mejoraron sustancialmente, el mecanismo de relajación por efecto túnel, se suprimió en gran medida debido al aislamiento del ferricinio.[eng] The first part of this thesis focuses on the synthesis of heptazine-based ligands and the formation of its coordination compounds with CuII. The functionalization of this ligand with 2-dipiridilamine leads to the synthesis of a CuII trinuclear molecular cage. On the other hand, by using piperidin-4-carboxylic acid the supramolecular compound [Cu12(tpach)8(H2O)12] can be obtained, which possesses a cavity diameter of 24 Å. The second part of this thesis focuses on the synthesis, characterization and study of the single molecule magnet (SMMs) properties for different systems containing lanthanide ions. SMMs exhibit a slow relaxation of the magnetization below the blocking temperature (Tb). Using previously published work that describes systematic ways of synthetizing lanthanide-based SMMs based on the shape of the electron density (oblate or prolate), we used crown ethers (18-crown-6) and several lanthanides (Nd, Tb, Dy, Er and Yb) to build up molecules in which the electron density will be in the equatorial plane. By later addition of anionic axial ligands, it should be possible to generate molecules with an electronic density such as the anisotropy of the system maximizes, which will lead to SMMs behavior. Finally, for SMMs with total spin S=1/2 exists the possibility of using them as qbits for Quantum Computing. The last part of the thesis centered on the study of the cobaltocene and ferrocenium SMM behavior applied to Quantum Computing. One should expect, based on their electronic structure, that cobaltocene will be a much better candidate when it comes to SMM behavior, however, experimental data shows that it is the ferrocenium the one that displays better properties. This fact can be rationalized on basis of the Single-occupied Molecular Orbital (SOMO) for both complexes, and its antibonding or non-bonding character. To improve the properties of the ferrocenium, we encapsulated the molecule using polysaccharids (a and b cyclodextrin). This process does increase the SMM properties of ferrocenium, due to the isolation of the magnetic centers, which block the tunnel-effect relaxation mechanism