Chemical engineering of molecular qubits.

We show that the electron spin phase memory time, the most important property of a molecular nanomagnet from the perspective of quantum information processing, can be improved dramatically by chemically engineering the molecular structure to optimize the environment of the spin. We vary systematically each structural component of the class of antiferromagnetic Cr(7)Ni rings to identify the sources of decoherence. The optimal structure exhibits a phase memory time exceeding 15 µs.

Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens.

The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.

Limits on intrinsic magnetism in graphene.

We have studied magnetization of graphene nanocrystals obtained by sonic exfoliation of graphite. No ferromagnetism is detected at any temperature down to 2 K. Neither do we find strong paramagnetism expected due to the massive amount of edge defects. Rather, graphene is strongly diamagnetic, similar to graphite. Our nanocrystals exhibit only a weak paramagnetic contribution noticeable below 50 K. The measurements yield a single species of defects responsible for the paramagnetism, with approximately one magnetic moment per typical graphene crystallite.

Entanglement in supramolecular spin systems of two weakly coupled antiferromagnetic rings (purple-Cr7Ni).

We characterize supramolecular magnetic structures, consisting of two weakly coupled antiferromagnetic rings, by low-temperature specific heat, susceptibility, magnetization and electron paramagnetic resonance measurements. Intra- and inter-ring interactions are modeled through a microscopic spin-Hamiltonian approach that reproduces all the experimental data quantitatively and legitimates the use of an effective two-qubit picture. Spin entanglement between the rings is experimentally demonstrated through magnetic susceptibility below 50 mK and theoretically quantified by the concurrence.

Size-induced effects in wet-chemically synthesized CoPt3 nanoparticles.

CoPt3 alloy spherical nanoparticles with sizes tuned between 3-7 nm were produced by the simultaneous thermal treatment of proper platinum and cobalt precursors in the presence of surfactants. The final size and composition of the particles are determined by the precursors' ratio, the chemical behavior of Co precursors and the stabilizing efficiency of the surfactants. By employing higher reaction temperatures (approximately 350 degrees C) better alloying is achieved leading to enhancement of macroscopic magnetic features and decrease of the superparamagnetic limit down to 7 nm.

Cluster glass properties and magnetic phase separation studies of Nd(x)Bi(0.5-x)Sr(0.5)MnO(3) (x = 0.1, 0.2, 0.3 and 0.4).

The crystal structure, dc and ac magnetic susceptibility, electron spin resonance and magnetoresistive behavior of Nd(x)Bi(0.5-x)Sr(0.5)MnO(3) (x = 0.1, 0.2, 0.3 and 0.4) compounds are studied. The Rietveld analysis of the XRD data shows that the samples crystallize in an orthorhombic perovskite structure, with Pbnm space group for x = 0.1 and 0.2 and Imma space group for x = 0.4 and 0.3. Magnetic studies reveal that substituting Bi with Nd collapses the robust charge ordered AFM state of Bi(0.5)Sr(0.5)MnO(3) to an inhomogeneous magnetic state. As Nd concentration increases there is a gradual appearance of cluster glass behavior. ESR studies reveal that the NBSMO system phase separates into ferromagnetic and antiferromagnetic regions below the transition temperature.

Rapid Geriatric Assessment, Physical Activity, and Sleep Quality in Adults Aged more than 65 Years: A Preliminary Study.

OBJECTIVE: (1) To evaluate geriatric syndromes using the Rapid Geriatric Assessment; (2) To investigate possible association of geriatric syndomes with physical activity and sleep quality in adults aged more than 65 years who applied to outpatients physical medicine and rehabilitation clinic. DESIGN: A cross-sectional study. SETTING: Outpatient physical medicine and rehabilitation clinic in Edirne, Turkey. PARTICIPANTS: A total of 56 adults (mean aged 69.7 ± 4.0 (range, 65-80) years, 33 women). MEASUREMENTS: The Rapid Geriatric Assessment, which includes the FRAIL Questionnaire Screening Tool for frailty, Simplified Nutritional Assessment Questionnaire (SNAQ), SARC-F Screen for Sarcopenia, and Rapid Cognitive Screen (RCS), was used to assess geriatric syndromes. The International Physical Activity Questionnaire (IPAQ) was used to obtain data regarding health-related physical activity. The Pittsburgh Sleep Quality Index (PSQI) was used to measure sleep quality during the past month. RESULTS: The mean age of the patients was 69.7 ± 4.0 years. Of the 56 patients, 12.5% were frail, 50.0% were pre-frail, 35.7% had sarcopenia, 44.6% had a risk of weight loss, 33.9% had dementia, 57.1% were physically inactive, and 53.6% had poor sleep quality. The total FRAIL and SARC-F scores were positively correlated with the global PSQI score (correlation coefficient (r) = 0.300, p < 0.05; r = 0,327, p < 0.05, respectively) and negatively correlated with the total RCS score (r= -0,267, p < 0.05; r = -0,314, p < 0.05, respectively)). The total FRAIL score was positively correlated with the SARC-F score (r = 0.695, p < 0.001), and the concurrence of frailty and sarcopenia in the same patients was 10.7%. The global PSQI score was negatively correlated with the SNAQ score (r = -0.273, p < 0.05). CONCLUSION: Frailty and sarcopenia were positively correlated with poor sleep quality and negatively correlated with cognition and physical activity. In clinical practice, the Rapid Geriatric Assessment and determination of physical activity level could assist in disability prevention.

High magnetic relaxivity in a fluorescent CdSe/CdS/ZnS quantum dot functionalized with MRI contrast molecules.

Light emitting semiconducting quantum dots show great promise as solar cells, optoelectronic devices and multimodal imaging probes. Here we demonstrate successful grafting of a thiol-functionalised GdIII MRI contrast agent onto the surface of core-multishell CdSe/CdS/ZnS quantum dots. The resulting nanoprobe exhibits intense photoluminescence and unprecedentedly large T1 relaxivity of 6800 mM-1 s-1 per nanoparticle due to secure implanting of ca. 620 magnetic centers per quantum dot unit.

An {Fe60} tetrahedral cage: building nanoscopic molecular assemblies through cyanometallate and alkoxo linkers.

A nanoscopic {Fe60} coordination cage (approximately 3 nm) was prepared by the self assembly of a partially blocked tricyanidoferrate(iii) complex and tris(alkoxo)-based iron(iii) coordination motifs. This cage is a rare example of a mixed cyanido/alkoxo-bridged high nuclearity complex and it exemplifies the great potential of this new synthetic route to generate uncommon molecular architectures using cyanometallates as metalloligands versus alkoxo-based polynuclear entities.

The presence of hyperostosis in Atlantic moonfish, Selene setapinnis (Mitchill, 1815) in the Brazilian Coast - case report / [A presença de hiperostoses no peixe-galo-sem-penacho, Selene setapinnis (Mitchill, 1815) na costa brasileira - relato de caso]

The occurrence of hyperostotic bones is common in marine fish, especially in the Carangidae family, despite few records of this condition in fishes from Brazilian waters. The present study describes the occurrence of hyperostosis in Atlantic moonfish (Selene setapinnis) in, Rio de Janeiro State, Brazil. Radiographs of the fish specimens were taken and all of them presented hyperostosis in at least three different regions: cleithrum, pterygiophores and pleural ribs. The observed pattern is different from previously described for other species of the same genus. It is the first record for the species and a valuable contribution to the study of bone diseases in fishes from the Brazilian coast.(AU)

A ocorrência de ossos hipertostóticos é comum em peixes marinhos, especialmente na família Carangidae, apesar de poucos relatos dessa condição em peixes de águas brasileiras. O presente estudo descreve a ocorrência de hiperostose no peixe-galo-sem-penacho (Selene setapinnis) no estado do Rio de Janeiro, Brasil. Radiografias dos espécimes de peixes foram feitas e todos os exemplares apresentaram hiperostoses em pelo menos três regiões diferentes: cleithrum, pterigióforos e costelas pleurais. O padrão observado é diferente do descrito previamente para outras espécies do mesmo gênero. Este é o primeiro relato para a espécie e é uma contribuição valiosa para o estudo de doenças ósseas em peixes da costa brasileira.(AU)