Coupled magnetic and elastic properties in LaPr(CaSr)MnO manganites

We investigate a series of manganese oxides, the La0.225Pr0.4(Ca1-xSrx)0.375MnO3 system. The x = 0 sample is a prototype compound for the study of phase separation in manganites, where ferromagnetic and charge ordered antiferromagnetic phases coexist. Replacing Ca2+ by Sr2+ gradually turns the system into a homogeneous ferromagnet. Our results show that the material structure plays a major role in the observed magnetic properties. On cooling, at temperatures below 100 K, a strong contraction of the lattice is followed by an increase in the magnetization. This is observed both through thermal expansion and magnetostriction measurements, providing distinct evidence of magneto-elastic coupling in these phase separated compounds

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Creative destruction over the business cycle: a stochastic frontier analysis

[[abstract]]This paper examines the within-industry distributions of jobs created and destructed across plants in terms of technical efficiency, technical efficiency change, scale effect, and technical change. It further investigates how these distributions vary with economic activity. By applying the stochastic frontier analysis to plant-level longitudinal data on Taiwan’s 23 two-digit manufacturing industries spanning the period 1992–2003, we find that jobs created (destructed) are disproportionately clustered at plants with lower technical efficiency but higher rate of technical change. A fall in economic activities is associated with a statistically significant decrease (increase) in the fraction of newly created (destructed) jobs accounted for by plants with a higher rate of technical change, indicating that creative destruction is more pronounced during economic contractions.[[journaltype]]國外[[incitationindex]]SSCI[[ispeerreviewed]]Y[[countrycodes]]US

Mesozoic rock suites along western Philippines: Exposed proto-South China Sea fragments?

An ancient oceanic crustal leading edge east of mainland Asia, the proto-South China Sea crust, must have existed during the Mesozoic based on tectonic reconstructions that accounted for the presence of subducted slabs in the lower mantle and the exposed oceanic lithospheric fragments strewn in the Philippine and Bornean regions. Along the western seaboard of the Philippine archipelago, numerous Mesozoic ophiolites and associated lithologies do not appear to be genetically associated with the younger Paleogene-Neogene ocean basins that currently surround the islands. New sedimentological, paleomagnetic, paleontological, and isotopic age data that we generated are presented here, in combination with our previous results and those of others, to reassess the geological make-up of the western Philippine island arc system. We believe that the oceanic lithospheric fragments, associated melanges, and sedimentary rocks in this region are exhumed slivers of the proto-South China Sea ocean plate

Costos por dolor lumbar en una EPS en Cali, Colombia

Objective: To identify the costs for treatment and disability, in workers with low back pain affiliated to an EPS. Methodology: Descriptive study carried out on a database of 402 members of an EPS in the city of Cali (Colombia), between 2008 and 2011, occupationally active and diagnosed with low back pain with sciatica, radiculopathy and non-specific low back pain. Data on costs, type of treatment and days of disability were collected. Results: 52% of the patients were men with an average age of 42 years (SD ± 12). 11% of the patients had physical therapy and 27% medical treatment. The total costs generated for the years 2008 and 2011 averaged $14.8 billion Colombian pesos per year. Conclusions: It can be seen that as the chronological year increases, both the number of people with low back pain, as well as disabilities, the number of treatments and therefore the costs for its management are also increasing.Objetivo: Identificar los costos por tratamiento e incapacidad, en trabajadores con dolor lumbar afiliados a una EPS. Metodología: Estudio descriptivo realizado sobre una base de datos de 402 afiliados a una EPS en la ciudad de Cali (Colombia), entre los años 2008 y 2011, laboralmente activos y con diagnóstico de lumbalgia con ciática, radiculopatía y lumbalgia no específica. Se recolectaron datos de costos, tipo de tratamiento y días de incapacidad. Resultados: El 52$14.800.000 millones de pesos colombianos por año. Conclusiones: Se puede evidenciar que a medida que aumenta el ano cronológico, tanto el número de personas con lumbalgia, como las incapacidades, el número de tratamientos y por lo tanto los costos para su manejo también van aumentando

Giant magnetic-field-induced strain in Ni2MnGa-based polycrystal

Ferromagnetic Ni2MnGa-based alloys play an important role in technological fields, such as smart actuators, magnetic refrigeration and robotics. The possibility of obtaining large non-contact deformation induced by an external perturbation is one of its key strengths for applications. However, the search for materials with low cost, practical fabrication procedures and large signal output under small perturbing fields still poses challenges. In the present study we demonstrate that by judicial choice of substitution on the Mn site, an abrupt magnetostructural transition from a paramagnetic austenite phase to a ferromagnetic martensite one can be tuned to close to room temperature achieving large and reproducible strains. The required magnetic field to induce the strain varies from small values, as low as 0.25 T for 297.4 K and 1.6% of strain, to 8 T for 305 K and 2.6% of strain. Our findings point to encouraging possibilities for application of shape memory alloys in relatively inexpensive, scalable polycrystalline materials

Synergistic effect of simultaneous doping of ceria nanorods with Cu and Cr on CO oxidation and NO reduction

Ceria particles play a key role in catalytic applications such as automotive three-way catalytic systems in which toxic CO and NO are oxidized and reduced to safe CO2 and N2, respectively. In this work, we explore the incorporation of Cu and Cr metals as dopants in the crystal structure of ceria nanorods prepared by a single-step hydrothermal synthesis. XRD, Raman and XPS confirm the incorporation of Cu and Cr in the ceria crystal lattices, offering ceria nanorods with a higher concentration of oxygen vacancies. XPS also confirms the presence of Cr and Cu surface species. H2-TPR and XPS analysis show that the simultaneous Cu and Cr co-doping results in a catalyst with a higher surface Cu concentration and a much-enhanced surface reducibility, in comparison with either undoped or singly doped (Cu or Cr) ceria nanorods. While single Cu doping enhances catalytic CO oxidation and Cr doping improves catalytic NO reduction, co-doping with both Cu and Cr enhances the benefits of both dopants in a synergistic manner employing roughly a quarter of dopant weight