Enhancement of TbIII-CuII single-molecule magnet performance through structural modification

We report a series of 3d–4f complexes {Ln2Cu3(H3L)2Xn} (X=OAc−, Ln=Gd, Tb or X=NO3−, Ln=Gd, Tb, Dy, Ho, Er) using the 2,2′-(propane-1,3-diyldiimino)bis[2-(hydroxylmethyl)propane-1,3-diol] (H6L) pro-ligand. All complexes, except that in which Ln=Gd, show slow magnetic relaxation in zero applied dc field. A remarkable improvement of the energy barrier to reorientation of the magnetisation in the {Tb2Cu3(H3L)2Xn} complexes is seen by changing the auxiliary ligands (X=OAc− for NO3−). This leads to the largest reported relaxation barrier in zero applied dc field for a Tb/Cu-based single-molecule magnet. Ab initio CASSCF calculations performed on mononuclear TbIII models are employed to understand the increase in energy barrier and the calculations suggest that the difference stems from a change in the TbIII coordination environment (C4v versus Cs)

X-ray photoelectron spectroscopy and friction studies of nickel-zinc and manganese-zinc ferrites in contact with metals

X-ray photoelectron spectroscopy analysis and sliding friction experiments were conducted with hot-pressed, polycrystalline Ni-Zn and Mn-Zn ferrites in sliding contact with various transition metals at room temperature in a vacuum of 30 nPa. The results indicate that the coefficients of friction for Ni-Zn and Mn-Zn ferrites in contact with metals are related to the relative chemical activity in these metals: the more active the metal, the higher is the coefficient of friction. The coefficients of friction for the ferrites correlate with the free energy of formation of the lowest metal oxide. The interfacial bond can be regarded as a chemical bond between the metal atoms and the oxygen anions in the ferrite surfaces. The adsorption of oxygen on clean metal and ferrite surfaces increases the coefficients of friction for the Ni-Zn and Mn-Zn ferrite-metal interfaces

New Approaches for ab initio Calculations of Molecules with Strong Electron Correlation

Reliable quantum chemical methods for the description of molecules with dense-lying frontier orbitals are needed in the context of many chemical compounds and reactions. Here, we review developments that led to our newcomputational toolbo x which implements the quantum chemical density matrix renormalization group in a second-generation algorithm. We present an overview of the different components of this toolbox.Comment: 19 pages, 1 tabl

Influence of physical aspects and throwing velocity in opposition situation in top-elite and elite female handball players

The relationship between anthropometric and physical characteristics of female handball players and throwing velocity is considered an important factor in handball performance. The aim of this study was to examine key differences in anthropometric and fitness characteristics between top elite and elite female players competing in the first Spanish handball league. A total of 89 players from the first Spanish handball league were divided into two groups, top elite (38) and elite (51) players, and assessed for anthropometric and fitness characteristics (throwing velocity, vertical jump and hand grip strength). A Student’s t-test was used to determine whether a statistically significant difference between the two different levels of play occurred. Significant differences were found in age, body height, body mass, arm span, muscle mass, different girths (tensed and flexed arm, forearm, wrist, ankle), dominant hand width and length, different breadths (biacromial, bitrochanteric, bistyloid breadth and biepicondylar humerus) and fitness characteristics (hand grip strength and throwing velocity for different positions). Top elite players compared to elite players showed differences in anthropometric characteristics which were mainly located in the upper limbs and mostly were nonmodifiable aspects by training. Furthermore, the best players were able to maintain a high throwing velocity in different tactical situations

Los corpus diacrónicos como instrumento para el estudio del origen y distribución de la concordancia de objeto en español

Partimos de una investigación previa sobre la génesis y el desarrollo histórico de la concordancia de objeto en español que pone de relieve las ventajas de un enfoque basado en corpus frente a otras alternativas de análisis. Teniendo en cuenta los corpus diacrónicos de que dispone el español, discutiremos hasta qué punto resulta factible recuperar los datos precisos para un estudio de estas características y qué tipo de información (etiquetado, analizado, etc.) sería necesaria para facilitar tal tarea. Finalmente, se verá en qué medida se manifiesta la preferencia de ciertas funciones sintácticas por una codificación y un estatus informativo determinados en el corpus seleccionado y se planteará si los géneros discursivos documentados a lo largo de la historia del español son representativos en igual medida de dicha preferencia.The article is based on previous research on the genesis and diffusion of object agreement in Spanish, which highlights the advantages of a corpus-driven approach as contrasted with other lines of analysis. We take into account the Spanish historical corpora available and discuss the feasibility of retrieving the necessary data for this type of study. Furthermore, we put forward some proposals about what kind of information (tagging, parsing, etc.) could make the task easier. Lastly, in the light of corpus data, we can see to what extent certain syntactic functions favour particular coding devices and information status, and consider if the various discourse genres registered in the history of the Spanish language are equally representative of these preferences