Long-range ferromagnetic dipolar ordering of high-spin molecular clusters

We report the first example of a transition to long-range magnetic order in a purely dipolarly interacting molecular magnet. For the magnetic cluster compound Mn6O4Br4(Et2dbm)6, the anisotropy experienced by the total spin S=12 of each cluster is so small that spin-lattice relaxation remains fast down to the lowest temperatures, thus enabling dipolar order to occur within experimental times at Tc=0.16 K. In high magnetic fields, the relaxation rate becomes drastically reduced and the interplay between nuclear- and electron-spin lattice relaxation is revealed.

Salience and consumer choice

We present a theory of context-dependent choice in which a consumer's attention is drawnto salient attributes of goods, such as quality or price. An attribute is salient for a good when itstands out among the good's attributes, relative to that attribute's average level in the choice set (orgenerally, the evoked set). Consumers attach disproportionately high weight to salient attributesand their choices are tilted toward goods with higher quality/price ratios. The model accounts fora variety of disparate evidence, including decoy effects, context-dependent willingness to pay, andlarge shifts in demand in response to price shocks.

Distribution, Abundance and Molecular Analysis of Genus Barbadocladius Cranston & Krosch (Diptera, Chironomidae) in Tropical, High Altitude Andean Streams and Rivers

The distribution of the genus Barbadocladius Cranston & Krosch (Diptera: Chironomidae), previously reported from Chile to Bolivia, has extended northwards. Larvae, pupae and pupal exuviae of this genus have been found in the high mountain tropical streams of Peru to 9°22′56″, but are restricted to very high altitude streams (altitudes over 3,278 m asl) compared to the lower altitude streams (below 1,100 m asl) in which the genus is reported in Chile and Argentina. Based on morphological studies, both described species in the genus, Barbadocladius andinus Cranston & Krosch and Barbadocladius limay Cranston & Krosch, have been found in Peru as pupae or pupal exuviae. Morphological analysis of the larvae and pupae revealed no differences between the two described species from Patagonia and Peru, which are of similar size and with a similar armament of hooklets and spines in pupal tergites and sternites. However, molecular analysis of larvae and pupae revealed that in Peru, there are at least two different evolutionary lines, one distributed widely and another restricted to one site. Phylogenetic analysis (using cox1 mitochondrial sequences) of all available sequences of Barbadocladius shows that the Chilean and Argentinean material differs from that of Peru. Therefore, a total of four molecular segregates are identified, although morphologically, neither larvae nor the pupae may be differentiated.

Identificación de variedades de vitis vinifera procedentes de diferentes regiones del mundo mediante tècnica de biologia molecular de los microsatéllites

El objetivo de este estudio se centró en analizar una colección privada de germoplasma de Vitis vinifera L., de 338 cultivares procedentes de 24 países, para caracterizarlas creando una base de datos, utilizando 11 marcadores microsatélites o SSR (Simple Sequence Repeat). Como resultado se encontraron que algunas de las muestras analizadas presentaron un perfil idéntico de SSR, indicando que se trata de una sinonimia (la misma variedad pero con diferente nombre). Se detectaron 293 perfiles únicos. Adicionalmente, 15 pares de variedades presentaron diferencias en un solo locus y otros 7 grupos difieren en 2 loci, lo cual indicaría la alta proximidad genética entre esas variedades, sin llegar a ser la misma. El germoplasma analizado cuenta con una compleja biodiversidad varietal que se debe preservar. El estudio se realizó programando para el primer año la revisión bibliográfica detallada, recolección de las hojas y el inicio de la puesta a punto de la metodología, en el segundo año se completa la puesta a punto de la metodología, se trituran las hojas y se realiza la extraccinón del ADN. El tercer año se emplea para amplificar los fragmentos de ADN por medio de la PCR (reacción en cadena de la polimerasa), obtener la longitud de los fragmentos con un secuenciador ABI PRISM 310, valorar resultados y realizar repeticiones. El último año se analizan los resultados obtenidos, se realizan repeticiones pertinentes y se comienza la redacción de artículos científicos.

Characterization of alkaline lignins for use in penol-formaldehyde and epoxy resins

Besides polyurethanes and polyesters, phenolic and epoxy resins are the most prominent applications for technical lignins in thermosetting materials. To evaluate the potential application of lignin raw materials in phenol formaldehyde and epoxy resins, three types of alkaline lignins were characterized in terms of their structures and thermal properties. The lignin samples analyzed were kraft lignin (LIG-1), soda–rice straw lignin (LIG-2), and soda-wheat straw lignin (LIG-3). FTIR and 1H-NMR methods were used to determine their structure. Gel permeation chromatography (GPC) was used to determine the molecular weight distribution (MWD). Differential scanning calorimetry (DSC) was used to measure the glass transition temperature (Tg), and thermogravimetric analysis (TGA) to determine the thermal stability of lignin samples. Results showed that kraft lignin (LIG-1) has moderate hydroxyl-group content, is rich in G-type units, and has good thermal stability. These properties make it more suitable for direct use in phenol formaldehyde resins, and it is therefore a good raw material for this purpose. The alkaline soda-rice straw lignin (LIG-2) with a high hydroxyl-group content and excellent thermal stability is most suited to preparing lignin-based epoxy resin

Conformations of poly{G}-poly{C} π stacks with high hole mobility

Charge transfer properties of DNA depend strongly on the π stack conformation. In the present paper, we identify conformations of homogeneous poly-{G}-poly-{C} stacks that should exhibit high charge mobility. Two different computational approaches were applied. First, we calculated the electronic coupling squared, V2, between adjacent base pairs for all 1 ps snapshots extracted from 15 ns molecular dynamics trajectory of the duplex G15. The average value of the coupling squared 〈 V2 〉 is found to be 0.0065 eV2. Then we analyze the base-pair and step parameters of the configurations in which V2 is at least an order of magnitude larger than 〈 V2 〉. To obtain more consistent data, ∼65 000 configurations of the (G:C)2 stack were built using systematic screening of the step parameters shift, slide, and twist. We show that undertwisted structures (twist<20°) are of special interest, because the π stack conformations with strong electronic couplings are found for a wide range of slide and shift. Although effective hole transfer can also occur in configurations with twist=30° and 35°, large mutual displacements of neighboring base pairs are required for that. Overtwisted conformation (twist38°) seems to be of limited interest in the context of effective hole transfer. The results may be helpful in the search for DNA based elements for nanoelectronics

Multifunctional ligands for application in Alzheimer’s Disease: molecular modelling and biological evaluation

Projecte de recerca elaborat a partir d’una estada a la University of British Columbia, Canadà, entre 2010 i 2012 La malaltia d'Alzheimer (MA) representa avui la forma més comuna de demència en la població envellida. Malgrat fa 100 anys que va ser descoberta, encara avui no existeix cap tractament preventiu i/o curatiu ni cap agent de diagnòstic que permeti valorar quantitativament l'evolució d'aquesta malaltia. L'objectiu en el que s'emmarca aquest treball és contribuir a aportar solucions al problema de la manca d'agents terapèutics i de diagnosi, unívocs i rigorosos, per a la MA. Des del camp de la química bioinorgànica és fàcil fixar-se en l'excessiva concentració d'ions Zn(II) i Cu(II) en els cervells de malalts de MA, plantejar-se la seva utilització com a dianes terapèutica i, en conseqüència, cercar agents quelants que evitin la formació de plaques senils o contribueixin a la seva dissolució. Si bé aquest va ser el punt de partida d’aquest projecte, els múltiples factors implicats en la patogènesi de la MA fan que el clàssic paradigma d’ ¨una molècula, una diana¨ limiti la capacitat de la molècula de combatre aquesta malaltia tan complexa. Per tant, un esforç considerable s’ha dedicat al disseny d’agentsmultifuncionals que combatin els múltiples factors que caracteritzen el desenvolupament de la MA. En el present treball s’han dissenyat agents multifuncionals inspirats en dos esquelets moleculars ben establers i coneguts en el camp de la química medicinal: la tioflavina-T (ThT) i la deferiprona (DFP). La utilització de tècniques in silico que inclouen càlculs farmacocinètics i modelatge molecular ha estat un procés cabdal per a l’avaluació dels millors candidats en base als següents requeriments: (a) compliment de determinades propietats farmacocinètiques que estableixin el seu possible ús com a fàrmac (b) hidrofobicitat adequada per travessar la BBB i (c) interacció amb el pèptid Aen solució.

Desarrollo y validación de ensayos rápidos para la detección de aeroalérgenos ocupacionales/ambientales: soja i proteinas séricas de paloma

Tanto el asma ocupacional como la neumonitis por hipersensibilidad, como es el pulmón del cuidador de aves, son patologías respiratorias que se pueden prevenir o disminuir su aparición mediante la evitación de la fuente antigénica. Para poder actuar de forma preventiva es de utilidad el disponer de ensayos rápidos que sean capaces de estimar la presencia de alérgeno de forma inmediata. En el marco de este proyecto de dos años de duración tenemos por objeto el desarrollar y estandarizar dos métodos rápidos, inmunocromatográficos, para la determinación de alérgenos de soja y de proteínas séricas de paloma. Alérgenos que han sido seleccionados por su importancia en el medio como agentes causales de asma y neumonitis por hipersensibilidad, respectivamente. También tenemos por objeto determinar la carga de alérgeno de soja en la fracción de partículas menores de 10 micrómetros (PM10) en los alrededores del puerto de Barcelona y comprarla con los niveles en los filtros de partículas suspendidas totales (TSP). Como pasos previos al desarrollo de los ensayos rápidos se han producido anticuerpos específicos frente al extracto de cáscara de soja de bajo peso molecular y frente al suero de paloma, se ha desarrollado un ELISA tipo sándwich para cada alérgeno y parte de los anticuerpos se ha conjugado con oro coloidal. El ensayo inmunocromatográfico para la soja presenta un límite de detección de 6.25ng/ml y ha sido validado mediante el análisis de 119 muestras ambientales, presentando una elevada especificidad y sensibilidad. El ensayo inmunocromatográfico para la determinación de antígenos séricos de paloma requiere ser validado. Mediante un métodos de ELISA de inhibición se han determinado los niveles de alérgeno de soja en filtros PM10 y TSP. A pesar de la buena correlación entre los niveles de alérgeno en ambos filtros, se observó una amplia variación en la proporción PM10/TSP entre días.

Synthesis, binding affinity, and molecular docking analysis of new benzofuranone derivative as pontential antipsychotics

The complex etiology of schizophrenia has prompted researchers to develop clozapine-related multitargetstrategies to combat its symptoms. Here we describe a series of new 6-aminomethylbenzofuranones in aneffort to find new chemical structures with balanced affinities for 5-HT2 and dopamine receptors. Throughbiological and computational studies of 5-HT2A and D2 receptors, we identified the receptor serine residuesS3.36 and S5.46 as the molecular keys to explaining the differences in affinity and selectivity betweenthese new compounds for this group of receptors. Specifically, the ability of these compounds to establishone or two H-bonds with these key residues appears to explain their difference in affinity. In addition, wedescribe compound 2 (QF1004B) as a tool to elucidate the role of 5-HT2C receptors in mediating antipsychoticeffects and metabolic adverse events. The compound 16a (QF1018B) showed moderate to high affinitiesfor D2 and 5-HT2A receptors, and a 5-HT2A/D2 ratio was predictive of an atypical antipsychotic profile.

The Coordinated Radio and Infrared Survey for High-Mass Star Formation (The CORNISH Survey). I. Survey Design

We describe the motivation, design, and implementation of the CORNISH survey, an arcsecondresolution radio continuum survey of the inner galactic plane at 5 GHz using the Very Large Array (VLA). It is a blind survey coordinated with the northern SpitzerGLIMPSE I region covering 10° molecular phases to build up a complete picture of the interstellar medium in the Galaxy.

Nucleation and growth of GaN nanorods on Si (111) surfaces by plasma-assisted molecular beam epitaxy - The influence of Si- and Mg-doping

The self-assembled growth of GaN nanorods on Si (111) substrates by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions is investigated. An amorphous silicon nitride layer is formed in the initial stage of growth that prevents the formation of a GaN wetting layer. The nucleation time was found to be strongly influenced by the substrate temperature and was more than 30 min for the applied growth conditions. The observed tapering and reduced length of silicon-doped nanorods is explained by enhanced nucleation on nonpolar facets and proves Ga-adatom diffusion on nanorod sidewalls as one contribution to the axial growth. The presence of Mg leads to an increased radial growth rate with a simultaneous decrease of the nanorod length and reduces the nucleation time for high Mg concentrations.

Structural and optical properties of dilute InAsN grown by molecular beam epitaxy

We perform a structural and optical characterization of InAs1¿xNx epilayers grown by molecular beam epitaxy on InAs substrates x 2.2% . High-resolution x-ray diffraction HRXRD is used to obtain information about the crystal quality and the strain state of the samples and to determine the N content of the films. The composition of two of the samples investigated is also obtained with time-of-flight secondary ion mass spectroscopy ToF-SIMS measurements. The combined analysis of the HRXRD and ToF-SIMS data suggests that the lattice parameter of InAsN might significantly deviate from Vegard"s law. Raman scattering and far-infrared reflectivity measurements have been carried out to investigate the incorporation of N into the InAsN alloy. N-related local vibrational modes are detected in the samples with higher N content. The origin of the observed features is discussed. We study the compositional dependence of the room-temperature band gap energy of the InAsN alloy. For this purpose, photoluminescence and optical absorption measurements are presented. The results are analyzed in terms of the band-anticrossing BAC model. We find that the room-temperature coupling parameter for InAsN within the BAC model is CNM=2.0 0.1 eV.

Steps in the hysteresis of a high spin molecule

We report the first observation of steps in the hysteresis loop of a high¿spin molecular magnet. We propose that the steps, which occur every 0.46 T, are due to thermally assisted resonant tunneling between different quantum spin states. Magnetic relaxation increases dramatically when the field is in the neighborhood of a step. A simple model accounts for the observations and predicts a value for the anisotropy barrier consistent with that inferred from the superparamagnetic blocking temperature

Effect of a transverse magnetic field on resonant magnetization tunneling in high-spin molecules

The recent observation of steps at regular intervals of magnetic field in the hysteresis loops of oriented crystals of the spin-10 molecular magnet Mn12O12(CH3COO)16(H2O)4 has been attributed to resonant tunneling between spin states. Here, we investigate the effect on the relaxation rate of applying the magnetic field at an angle with respect to the easy axis of magnetization. We find that the position of the resonances is independent of the transverse component of the field, and is determined solely by the longitudinal component. On the other hand, a transverse field significantly increases the relaxation rate, both on and off resonance. We discuss classical and quantum mechanical interpretations of this effect