New constraints on the genesis and long-term stability of Os-rich alloys in the Earth's mantle

A variety of seemingly unrelated processes, such as core-mantle interaction, desulfurization, and direct precipitation from a silicate melt have been proposed to explain the formation of Ru-Os-Ir alloys (here referred to as osmiridiums) found in terrestrial mantle rocks. However, no consensus has yet been reached on how these important micrometer-sized phases form. In this paper we report the results of an experimental study on the solubilities of Ru, Os and Ir in sulfide melts (or mattes) as a function of alloy composition at 1300 degrees C. Considering the low solubilities of Ru, Os, and Ir in silicate melts, coupled with their high matte/silicate-melt partition coefficients, our results indicate that these elements concentrate initially at the ppm level in a matte phase in the mantle source region. During partial melting, the extraction of sulfur into silicate melt leads to a decrease in fS(2) that triggers the exsolution of osmiridiums from the refractory matte in the residue. The newly formed osmiridiums may persist in the terrestrial mantle for periods exceeding billions of years. (C) 2012 Elsevier Ltd. All rights reserved.

Aquaporin-4 Antibodies Are Not Related to HTLV-1 Associated Myelopathy

Introduction: The seroprevalence of human T-cell leukemia virus type 1 (HTLV-1) is very high among Brazilians (,1:200). HTLV-1 associated myelopathy or tropical spastic paraparesis (HAM/TSP) is the most common neurological complication of HTLV-1 infection. HAM/TSP can present with an acute/subacute form of longitudinally extensive myelitis, which can be confused with lesions seen in aquaporin-4 antibody (AQP4-Ab) positive neuromyelitis optica spectrum disorders (NMOSD) on MRI. Moreover, clinical attacks in patients with NMOSD have been shown to be preceded by viral infections in around 30% of cases. Objective: To evaluate the frequency of AQP4-Ab in patients with HAM/TSP. To evaluate the frequency of HTLV-1 infection in patients with NMOSD. Patients and Methods: 23 Brazilian patients with HAM/TSP, 20 asymptomatic HTLV-1+ serostatus patients, and 34 with NMOSD were tested for AQP4-Ab using a standardized recombinant cell based assay. In addition, all patients were tested for HTLV-1 by ELISA and Western blotting. Results: 20/34 NMOSD patients were positive for AQP4-Ab but none of the HAM/TSP patients and none of the asymptomatic HTLV-1 infected individuals. Conversely, all AQP4-Ab-positive NMOSD patients were negative for HTLV-1 antibodies. One patient with HAM/TSP developed optic neuritis in addition to subacute LETM; this patient was AQP4-Ab negative as well. Patients were found to be predominantly female and of African descent both in the NMOSD and in the HAM/TSP group; Osame scale and expanded disability status scale scores did not differ significantly between the two groups. Conclusions: Our results argue both against a role of antibodies to AQP4 in the pathogenesis of HAM/TSP and against an association between HTLV-1 infection and the development of AQP4-Ab. Moreover, the absence of HTLV-1 in all patients with NMOSD suggests that HTLV-1 is not a common trigger of acute attacks in patients with AQP4-Ab positive NMOSD in populations with high HTLV-1 seroprevalence.

Direct Access to Oxidation-Resistant Nickel Catalysts through an Organometallic Precursor

The synthesis of nickel catalysts for industrial applications is relatively simple; however, nickel oxidation is usually difficult to avoid, which makes it challenging to optimize catalytic activities, metal loadings, and high-temperature activation steps. A robust, oxidation-resistant and very active nickel catalyst was prepared by controlled decomposition of the organometallic precursor [bis(1,5-cyclooctadiene)nickel(0)], Ni(COD)(2), over silica-coated magnetite (Fe3O4@SiO2). The sample is mostly Ni(0), and surface oxidized species formed after exposure to air are easily reduced in situ during hydrogenation of cyclohexene under mild conditions recovering the initial activity. This unique behavior may benefit several other reactions that are likely to proceed via Ni heterogeneous catalysis.

4-Organochalcogenoyl-1H-1,2,3-triazoles: synthesis and functionalization by a nickel-catalyzed Negishi cross-coupling reaction

A general method for the synthesis of triazoles containing selenium and tellurium was accomplished via a CuCAAC reaction between organic azides and a terminal triple bond, generated by in situ deprotection of the silyl group. The reaction tolerates alkyl and arylazides, with alkyl and aryl substituents directly bonded to the chalcogen atom. The products were readily functionalized by a nickel-catalyzed Negishi cross-coupling reaction, furnishing the aryl-heteroaryl products at the 4-position in good yields. (C) 2012 Elsevier Ltd. All rights reserved.

Coffee is highly tolerant to cadmium, nickel and zinc: Plant and soil nutritional status, metal distribution and bean yield

Sewage sludge has been used to fertilize coffee, increasing the risk of metal contamination in this crop. The aim of this work was to study the effects of Cd, Zn and Ni in adult coffee plants growing under field conditions. Seven-year-old coffee plants growing in the field received one of three;loses of Cd, Zn or Ni: 15,45 and 90 g Cd plant(-1); 35, 105 and 210 g Ni plant(-1); and 100, 300 and 600 g Zn plant(-1), with all three metals in the form of sulphate salts. After three months, we noticed good penetration of the three metals into the soil, especially in the first 50 cm, which is the region where most coffee plant roots are concentrated. Leaf concentrations of K, Ca, Mg, S, B, Cu, Fe and Mn were nor affected. N levels did not change with the application of Ni or Zn but were reduced with either 45 or 90 g Cd plant(-1). Foliar P concentrations decreased with the addition of 45 and 90 g Cd plant(-1) and 600 g Zn plant(-1). Zn levels in leaves were not affected by the application of Cd or Ni. The highest concentrations. of Zn were found in branches (30-230 mg kg(-1)), leaves (7-35 mg kg(-1)) and beam (4-6.5 mg kg(-1)); Ni was found in leaves (4-45 mg kg(-1)), branches (3-18 mg kg(-1)) and beans (1-5 mg kg(-1)); and Cd was found in branches (0-6.2 mg kg(-1)) and beans (0-1.5 mg kg(-1)) but was absent in leaves. The mean yield of two harvests was not affected by Ni, but it decreased at the highest dose of Zn (600 g plant(-1)) and the two higher doses of Cd (45 and 90 g plant(-1)). Plants died when treated with the highest dose of Cd and showed symptoms of toxicity with the highest dose of Zn. Nevertheless, based on the amounts of metal used and the results obtained, we conclude that coffee plants are highly tolerant to the three metals tested. Moreover, even at high doses, there was very little transport to the beans, which is the part consumed by humans. (C) 2011 Elsevier B.V. All rights reserved.

Magnetic Barkhausen Noise in Quenched Carburized Nickel-Steels

Two steel sheets, one with 5% Ni and another with 10% Ni, were submitted to carburization and quenching, obtaining a microstructure with martensite and retained austenite. These steels were characterized with magnetic Barkhausen noise (MBN). The Barkhausen signal is distinctively different for the carburized and quenched samples. The carburized and quenched samples present higher coercive field than the annealed samples. X-ray diffraction data indicated that the carburized and quenched samples have high density of dislocations, a consequence of the martensitic transformation.

Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC

We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.

Response of Saccharomyces cerevisiae to Cadmium and Nickel Stress: The Use of the Sugar Cane Vinasse as a Potential Mitigator

Most of the metals released from industrial activity, among them are cadmium (Cd) and nickel (Ni), inhibit the productivity of cultures and affect microbial metabolism. In this context, the aim of this work was to investigate the capacity of sugar cane vinasse to mitigate the adverse effects of Cd and Ni on cell growth, viability, budding rate and trehalose content of Saccharomyces cerevisiae, likely because of adsorption and chelating action. For this purpose, the yeast was grown batch-wise in YED medium supplemented with selected amounts of vinasse and Cd or Ni. The negative effects of Cd and Ni on S. cerevisiae growth and the mitigating one of sugar cane vinasse were quantified by an exponential model. Without vinasse, the addition of increasing levels of Cd and Ni reduced the specific growth rate, whereas in its presence no reduction was observed. Consistently with the well-proved toxicity of both metals, cell viability and budding rate progressively decreased with increasing their concentration, but in the presence of vinasse the situation was remarkably improved. The trehalose content of S. cerevisiae cells followed the same qualitative behavior as cell viability, even though the negative effect of both metals on this parameter was stronger. These results demonstrate the ability of sugar cane vinasse to mitigate the toxic effects of Cd and Ni.

VIBRATIONAL ANALYSIS OF COORDINATION COMPOUNDS OF NICKEL (II): AN APPROACH TO THE TEACHING OF POINT GROUPS

VIBRATIONAL ANALYSIS OF COORDINATION COMPOUNDS OF NICKEL (II): AN APPROACH TO THE TEACHING OF POINT GROUPS. This paper presents an IR and Raman experiment executed during the teaching of the course "Chemical Bonds" for undergraduated students of Science and Technology and Chemistry at the Federal University of ABC, in order to facilitate and encourage the teaching and learning of group theory. Some key aspects of this theory are also outlined. We believe that student learning was more significant with the introduction of this experiment, because there was an increase in the discussions level and in the performance during evaluations. This work also proposes a multidisciplinary approach to include the use of quantum chemistry tools.

Unraveling the Mysterious Role of Palladium in Feigl bis(dimethylglyoximate)nickel(II) Spot Tests by Means of Confocal Raman Microscopy

The add protection effect promoted by traces of PdCl2 in [Ni(dmgH)(2)] spot tests was elucidated from confocal Raman microscopy imaging, which revealed the formation of protecting layers of [Pd(dmgH)(2)] closing the extremities of the [Ni(dmgH)(2)] filaments.

Spectroscopic characterization and crystal structure of cis-Bis(N-(2-benzoyl)-N ',N '-diphenylthioureato-k O-2,S)nickel(II)

The title compound [Ni(C20H15N2OS)(2)] is prepared by the reaction of metal acetate with the corresponding acylthiourea derivative. The complex is characterized by elemental analysis, IR, H-1 and C-13 NMR, and its structure is determined by single crystal X-ray diffraction. The Ni(II) ion is coordinated by the S and O atoms of two N-benzoyl-N',N'-diphenylthiourea ligands in a slightly distorted square-planar coordination geometry. The two O and two S atoms are mutually cis to each other. The substance crystallizes triclinic (P-1 space group) with cell dimensions a = 10.7262(9) , b = 12.938(3) , c = 14.2085(12) , alpha = 74.650(4)A degrees, beta = 78.398(4)A degrees, gamma = 68.200(5)A degrees, and two formula units in the unit cell. The structure is very close to the related N-(2-furoyl) Ni complex reported previously.

Field dependent transition to the non-linear regime in magnetic hyperthermia experiments: Comparison between maghemite, copper, zinc, nickel and cobalt ferrite nanoparticles of similar sizes

Further advances in magnetic hyperthermia might be limited by biological constraints, such as using sufficiently low frequencies and low field amplitudes to inhibit harmful eddy currents inside the patient's body. These incite the need to optimize the heating efficiency of the nanoparticles, referred to as the specific absorption rate (SAR). Among the several properties currently under research, one of particular importance is the transition from the linear to the non-linear regime that takes place as the field amplitude is increased, an aspect where the magnetic anisotropy is expected to play a fundamental role. In this paper we investigate the heating properties of cobalt ferrite and maghemite nanoparticles under the influence of a 500 kHz sinusoidal magnetic field with varying amplitude, up to 134 Oe. The particles were characterized by TEM, XRD, FMR and VSM, from which most relevant morphological, structural and magnetic properties were inferred. Both materials have similar size distributions and saturation magnetization, but strikingly different magnetic anisotropies. From magnetic hyperthermia experiments we found that, while at low fields maghemite is the best nanomaterial for hyperthermia applications, above a critical field, close to the transition from the linear to the non-linear regime, cobalt ferrite becomes more efficient. The results were also analyzed with respect to the energy conversion efficiency and compared with dynamic hysteresis simulations. Additional analysis with nickel, zinc and copper-ferrite nanoparticles of similar sizes confirmed the importance of the magnetic anisotropy and the damping factor. Further, the analysis of the characterization parameters suggested core-shell nanostructures, probably due to a surface passivation process during the nanoparticle synthesis. Finally, we discussed the effect of particle-particle interactions and its consequences, in particular regarding discrepancies between estimated parameters and expected theoretical predictions. Copyright 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi. org/10.1063/1.4739533]

Effect of Nitrogen Ion Implantation on the Flexibility of Rotary Nickel-Titanium Instruments

Introduction: The aim of this study was to assess the effect of nitrogen ion implantation on the flexibility of rotary nickel-titanium (NiTi) instruments as measured by the load required to bend implanted and nonimplanted instruments at a 30 degrees angle. Methods: Thirty K3 files, size #40, 0.02 taper and 25-mm length, were allocated into 2 groups as follows: group A, 15 files exposed to nitrogen ion implantation at a dose of 2.5 x 10(17) ions/cm(2), voltage 200 KeV, current density 1 mu A/cm(2), temperature 130 degrees C, and vacuum conditions of 10 x 10(-6) mm Hg for 6 hours; and group B, 15 nonimplanted files. One extra file was used for process control. All instruments were subjected to bend testing on a modified troptometer, with measurement of the load required for flexure to an angle of 30 degrees. The Mann-Whitney U test was used for statistical analysis. Findings with P <.05 were considered significant. Results: The mean load required to bend instruments at a 30 degrees angle was 376.26 g for implanted instruments and 383.78 g for nonimplanted instruments. The difference was not statistically significant. Conclusions: Our findings show that nitrogen ion implantation has no appreciable effect on the flexibility of NiTi instruments. (J Endod 2012;38:673-675)

Bryozoan biodiversity in Saint Peter and Saint Paul Archipelago, Brazil

Among the marine invertebrate groups recorded from oceanic islands, bryozoans stand out because they can live and reproduce in suboptimal habitats, which may enhance their dispersal capabilities. This study aimed to update the checklist of bryozoans known from the Saint Peter and Saint Paul Archipelago (ASPSP) and discusses their distribution. During the five expeditions conducted between 2007 and 2009, 22 species were found, of which 16 were new occurrences for the archipelago. The bryozoans were collected from different biotic (algae and invertebrates) and abiotic (rocks, rubble and wrecks) substrata. The bryozoan community in ASPSP includes: eight new and probably endemic species, five species that belong to widespread species complexes, three species known only from the Brazilian coast, two species reported from the Western Atlantic and one species recorded from oceanic islets in the Atlantic. Additionally, three species are widespread in tropical to subtropical waters. Margaretta buski can be highlighted as the most conspicuous and abundant species between 1045 m deep and acts as an "ecosystem engineer".

An environmentally friendly analytical procedure for nickel determination by atomic and molecular spectrometry after cloud point extraction in different samples

Cloud point extraction (CPE) was employed for separation and preconcentration prior to the determination of nickel by graphite furnace atomic absorption spectrometry (GFAAS), flame atomic absorption spectrometry (FAAS) or UV-Vis spectrophotometry. Di-2-pyridyl ketone salicyloylhydrazone (DPKSH) was used for the first time as a complexing agent in CPE. The nickel complex was extracted from the aqueous phase using the Triton X-114 surfactant. Under optimized conditions, limits of detection obtained with GFAAS, FAAS and UV-Vis spectrophotometry were 0.14, 0.76 and 1.5 mu g L-1, respectively. The extraction was quantitative and the enrichment factor was estimated to be 27. The method was applied to natural waters, hemodialysis concentrates, urine and honey samples. Accuracy was evaluated by analysis of the NIST 1643e Water standard reference material.