Anderson transitions in Ln1-x Sr x CoO3 (Ln═Pr or Nd)

Electrical conductivity measurements show that Ln1-x Sr x CoO3, (Ln = Pr or Nd) undergoes a non-metal-metal transition when x≈0 3. The d.c. conductivity of compositions with 0

Anomalous magnetism of Pr in PrCoAsO

Detailed magnetization and magneto-transport measurements studies are carried out to unearth the anomalous magnetism of Pr in PrCoAsO compound. The studied PrCoAsO sample is single phase and crystallized in the tetragonal structure with space group P4/nmm in analogy of ZrCuSiAs type compounds. Detailed magnetization measurements showed that Co moments in PrCoAsO exhibit weakly itinerant ferromagnetic Co spins ordering at below 80 K with a small magnetic moments of similar to 0.12 mu B/f.u. High temperatures Curie-Weiss fit, resulted in effective paramagnetic moment mu(eff) (exp) of 5.91 mu(B)/f.u., which can be theoretically assigned to 3d Co (3.88 mu(B)) and 4f Pr (3.58 mu(B)). Further, a positive Curie-Weiss temperature (Theta) of 136 K is seen, indicating predominant ferromagnetic interactions in PrCoAsO. Detailed transport measurements showed that PrCoAsO exhibit metallic behavior and negative magneto-resistance below ferro-magnetically (FM) ordered state. Surprisingly, the situation of PrCoAsO is similar to non magnetic La containing LaCoAsO and strikingly different than that as reported for magnetic Nd, Sm and Gd i.e., (Nd/Sm/Gd)CoAsO. The magnetic behavior of PrCoAsO being closed to LaCoAsO and strikingly different to that of (Nd/Sm/Gd)CoAsO is unusual. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

Rare-earth carboxylates, Ln(2)(III)(mu(3)-OH)(C4H4O5)(2)(C4H2O4)]center dot 2H(2)O Ln = Ce, Pr and Nd]: synthesis, structure and properties

A new series of inorganic-organic hybrid framework compounds, Ln(2)(mu(3)-OH)(C4H4O5)(2)(C4H2O4)]center dot 2H(2)O, (Ln = Ce, Pr and Nd), have been prepared employing a hydrothermal method. Malic acid and fumaric acid form part of the structure. The malate units connect the lanthanide centers forming Ln-O-Ln two-dimensional layers, which are cross-linked by the fumarate units forming the three-dimensional structure. Extra framework water molecules form a dimer and occupy the channels. The water molecules can be reversibly adsorbed. The dehydrated structure did not show any differences in framework structure/ connectivity. The presence of lattice water provides a pathway for proton conductivity. Optical studies suggest an up-conversion behavior involving more than one photon for a neodymium compound.

Evaluation of TRMM PR Sampling Error Over a Subtropical Basin Using Bootstrap Technique

Quantitative use of satellite-derived rainfall products for various scientific applications often requires them to be accompanied with an error estimate. Rainfall estimates inferred from low earth orbiting satellites like the Tropical Rainfall Measuring Mission (TRMM) will be subjected to sampling errors of nonnegligible proportions owing to the narrow swath of satellite sensors coupled with a lack of continuous coverage due to infrequent satellite visits. The authors investigate sampling uncertainty of seasonal rainfall estimates from the active sensor of TRMM, namely, Precipitation Radar (PR), based on 11 years of PR 2A25 data product over the Indian subcontinent. In this paper, a statistical bootstrap technique is investigated to estimate the relative sampling errors using the PR data themselves. Results verify power law scaling characteristics of relative sampling errors with respect to space-time scale of measurement. Sampling uncertainty estimates for mean seasonal rainfall were found to exhibit seasonal variations. To give a practical example of the implications of the bootstrap technique, PR relative sampling errors over a subtropical river basin of Mahanadi, India, are examined. Results reveal that the bootstrap technique incurs relative sampling errors < 33% (for the 2 degrees grid), < 36% (for the 1 degrees grid), < 45% (for the 0.5 degrees grid), and < 57% (for the 0.25 degrees grid). With respect to rainfall type, overall sampling uncertainty was found to be dominated by sampling uncertainty due to stratiform rainfall over the basin. The study compares resulting error estimates to those obtained from latin hypercube sampling. Based on this study, the authors conclude that the bootstrap approach can be successfully used for ascertaining relative sampling errors offered by TRMM-like satellites over gauged or ungauged basins lacking in situ validation data. This technique has wider implications for decision making before incorporating microwave orbital data products in basin-scale hydrologic modeling.

Common effect of chemical and external pressures on the magnetic properties of RCoPO (R = La, Pr, Nd, Sm). II.

We investigate the direct correspondence between Co band ferromagnetism and structural parameters in the pnictide oxides RCoPO for different rare-earth ions (R = La, Pr, Nd, Sm) by means of muon-spin spectroscopy and ab initio calculations, complementing our results published previously G. Prando et al., Common effect of chemical and external pressures on the magnetic properties of RCoPO (R = La, Pr), Phys. Rev. B 87, 064401 (2013)]. We find that both the transition temperature to the ferromagnetic phase T-C and the volume of the crystallographic unit cell V are conveniently tuned by the R ionic radius and/or external pressure. We report a linear correlation between T-C and V and our ab initio calculations unambiguously demonstrate a full equivalence of chemical and external pressures. As such, we show that R ions influence the ferromagnetic phase only via the induced structural shrinkage without involving any active role from the electronic f degrees of freedom, which are only giving a sizable magnetic contribution at much lower temperatures.

Two bifurcation transitions of the floating half zone convection in a fat liquid bridge of larger Pr

The transient process of the thermocapillary convection was obtained for the large Pu floating half zone by using the method of three-dimensional and unsteady numerical simulation. The convection transits directly from steady and axisymmetric state to oscillatory flow for slender liquid bridge, and transits first from steady and axisymmetric convection to the steady and non-axisymmetric convection, then, secondly to the oscillatory convection for the fatter liquid bridge. This result implies that the volume of liquid bridge is not only a sensitive critical parameter for the onset of oscillation, but also relates to the new mechanism for the onset of instability in the floating half zone convection even in case of large Prandtl number fluid.

Proper orthogonal decomposition of oscillatory Marangoni flow in half-zone liquid bridges of low-Pr fluids

Proper orthogonal decomposition (POD) using method of snapshots was performed on three different types of oscillatory Marangoni flows in half-zone liquid bridges of low-Pr fluid (Pr = 0.01). For each oscillation type, a series of characteristic modes (eigenfunctions) have been extracted from the velocity and temperature disturbances, and the POD provided spatial structures of the eigenfunctions, their oscillation frequencies, amplitudes, and phase shifts between them. The present analyses revealed the common features of the characteristic modes for different oscillation modes: four major velocity eigenfunctions captured more than 99% of the velocity fluctuation energy form two pairs, one of which is the most energetic. Different from the velocity disturbance, one of the major temperature eigenfunctions makes the dominant contribution to the temperature fluctuation energy. On the other hand, within the most energetic velocity eigenfuction pair, the two eigenfunctions have similar spatial structures and were tightly coupled to oscillate with the same frequency, and it was determined that the spatial structures and phase shifts of the eigenfunctions produced the different oscillatory disturbances. The interaction of other major modes only enriches the secondary spatio-temporal structures of the oscillatory disturbances. Moreover, the present analyses imply that the oscillatory disturbance, which is hydrodynamic in nature, primarily originates from the interior of the liquid bridge. (C) 2007 Elsevier B.V. All rights reserved.

半浮区小Pr数液桥热毛细对流的实验探讨

研究了半浮区汞液桥实验装置，以探讨小Prandtl数流体的热毛细对流及其不稳定性。发展了非接触光学监测汞桥的表面流动及形变的方法。实验观察热毛细对流及其受表面膜的影响，证明表面膜的形成严重抑制了与热毛细对流有关的行为。实验给出发生振荡的条件及其特征。实验表明：所观察到的临界Marangoni数远比数值模拟值为高。讨论了表面膜的生成条件和过程，以及所观察到的有表面膜情况下的表面振荡现象。并给出了该振荡的特征和频率。

Os desafios, os impactos e a gestão da exploração do pré-sal

Consultoria Legislativa - Área XII - Recursos Minerais, Hídricos e Energéticos.

O pré-sal e o aquecimento global

Consultoria Legislativa - Área XII - Recursos Minerais, Hídricos e Energéticos.

A cessão onerosa de áreas do pré-sal e a capitalização da Petrobrás

Consultoria Legislativa - Área XII - Recursos Minerais, Hídricos e Energéticos.

A proposta do Poder Executivo para o marco legal do Pré-sal

Consultoria Legislativa - Área XII - Recursos Minerais, Hídrico e Energéticos.

Juventude em revolta : o Pró-Sinase e a realidade do Distrito Federal

Trata do Programa de Implementação do Sistema Nacional de Atendimento Socioeducativo (Pró-Sinase) e a realidade no Distrito Federal, assunto relevante para o contexto atual, objetivando analisar a realidade das Unidades Executoras das medidas socioeducativas de internação, internação provisória, e semiliberdade. Pretende verificar, à luz do Estatuto da Criança e do Adolescente, da Resolução nº 46 do Conselho Nacional dos Direitos da Criança e do Adolescente (Conanda) e das diretrizes do Pró-Sinase, qual o provável distanciamento das condições das Unidades de Atendimento Socioeducativo em relação ao que determinam os instrumentos legais, nos seguintes aspectos: gestão dos programas, parâmetros de gestão pedagógica no atendimento socioeducativo e os parâmetros arquitetônicos para Unidades de Atendimento Socioeducativo.

微重力条件下开口矩形容器的小Pr热毛细对流

采用数值方法研究了微重力条件下开口矩形容器内小Prandtl数镓(Ga)熔体生长过程中定常热毛细对流，讨论了Re数、几何纵横比A和侧壁外加温差的相对高度H对熔体内温度场和流场分布的影响。计算结果表明，热毛细对流对熔体温度分布有明显的影响，从而影响着晶体生长过程。自由面两侧温度差很小(如0.1K)时，熔体内温度场将发生变化；当温度差增加即Re数增加时，热毛细对流加强，对流和扩散相互作用导致温度场分布更加不均匀。无论多小的H值，若自由面存在温差，都会驱动热毛细对流；随着H值增加，热毛细对流会扩展到整个熔区。几何纵横比A对熔体内温度场和流场也有影响，当A比较大时，在固/液界面附近扩散起主导作用。

液池中大Pr数流体的热流体波

数值研究零重力条件下浅液池中大Pr数流体（Pr=105．6）的热流体波．液池的两侧有不同的温度，形成一定的温度差．当温度差增加并超过临界温度差时，在液池中会出现从冷端向热端传播的行波．扰动温度，扰动速度和扰动压强的相位关系表明这种行波为扰动温度所驱动，为热流体波．热流体波很弱，在热流体波出现时，在液池中几乎观测不到振荡的流场和温度分布．对热流体波的形成机理进行了分析和讨论．