Structural single crystal, thermal analysis and vibrational studies of the new rubidium phosphate tellurate Rb2HPO4RbH2PO4·Te(OH)6

AbstractThe determination of the crystalline structure of rubidium phosphate tellurate Rb2HPO4RbH2PO4·Te(OH)6 [RbPTe] is performed from single crystal X-ray diffraction data. The title compound crystallizes in the monoclinic system P2. The unit cell parameters are as follows: a=7.9500(7)Å, b=6.3085(6)Å, c=9.5008(9)Å, β=109.783(4)°, Z=2 and V=448.37(7)Å3.The crystal structure is constituted from isolated (PO43-) tetrahedra and (TeO66-) octahedra and two nonequivalent Rb+ cations. Material cohesion is built of O–H⋯O bondings and ionic interactions.The new synthesized material has been characterized using the differential scanning calorimetry (DSC), thermal analysis [differential thermogravimetric analysis (TG), thermodifference analysis (DTA) and the mass spectrometric analysis], FT-IR and Raman techniques.Thermal analysis, in the temperature range of 300–900K, confirms that the decomposition of this material took place in two steps. The differential scanning calorimetry analysis shows three endothermic peaks at 451, 463 and 481K.The existence of anionic groups in the structure has been confirmed by IR and Raman spectroscopy in the frequency ranges 3000–600cm−1 and 1300–50cm−1, respectively

Phase Transition and Electrical Properties in Cs2SeO4.Te(OH)6

Dielectric investigations in the temperature and frequency 300- 600 K and 0,1KHz–13MHz, respectively, show that cesium selenate tellurate Cs2SeO4.Te(OH)6 (CsSeTe) exhibits two phase transitions at 490 and 525 K. The a.c. complex impedance measurements performed on CsSeTe material show an important level of conductivity at high temperature, attributed to the motion of H+ proton. This behavior is in agreement with the presence of the super- protonic phase transition in CsSeTe compound at 525K. This assignment was confirmed by the analysis of the M"/M"max spectra. The temperature dependences of ε΄r and tanδ indicate that the anomaly at 490K is attributed to a ferroelectric-paraelectric phase transition. Thermal analysis at high temperature, DSC, DTA, TG,  Ms/z= 18 and Ms/z= 32 confirm the presence of the two transitions already cited, the temperature and the nature of the decomposition. Â

Thermal analysis, X-ray diffraction, spectroscopy studies and magnetic properties of the new compound Tl2HAsO4.Te(OH)6

The Tl2HAsO4.Te(OH)6 (TlAsTe) compound crystallizes in the triclinic system P1 with unit cell parameters: a= 7.100(10) Å, b= 7.281(13) Å, c= 8.383(11) Å, α= 76.91(1)°, β= 87.16(1)°, γ= 66.96(2)°, Z= 2 and V= 388.19(1) Å3. This new structure can be described as a lamellar one with the atomic arrangement being built by planes of Te(OH)6 octahedra alterning with planes of arsenate tetrahedra. Raman and infrared spectra recorded at room temperature confirm the presence of As  and Te  groups and characterize the hydrogen bonds present in the crystal lattice. Differential scanning calorimerty shows the presence of three-phase transitions at 396 K, 408 K and 430 K present in the title compound. Typical thermal analyses, such as differential thermal analysis and thermogravimetry show that the decomposition of this material starts at about T= 445 K. Magnetization curve of Tl2HAsO4·Te(OH)6 substance have revealed a diamagnetic response overall temperature range studied

Scalar wormholes with nonminimal derivative coupling

We consider static spherically symmetric wormhole configurations in a gravitational theory of a scalar field with a potential $V(\phi)$ and nonminimal derivative coupling to the curvature describing by the term $(\epsilon g_{\mu\nu} + \kappa G_{\mu\nu}) \phi^{,\mu}\phi^{,\nu}$ in the action. We show that the flare-out conditions providing the geometry of a wormhole throat could fulfilled both if $\epsilon=-1$ (phantom scalar) and $\epsilon=+1$ (ordinary scalar). Supposing additionally a traversability, we construct numerical solutions describing traversable wormholes in the model with arbitrary $\kappa$, $\epsilon=-1$ and $V(\phi)=0$ (no potential). The traversability assumes that the wormhole possesses two asymptotically flat regions with corresponding Schwarzschild masses. We find that asymptotical masses of a wormhole with nonminimal derivative coupling could be positive and/or negative depending on $\kappa$. In particular, both masses are positive only provided $\kappa<\kappa_1\le0$, otherwise one or both wormhole masses are negative. In conclusion, we give qualitative arguments that a wormhole configuration with positive masses could be stable.Comment: 17 pages, 8 figure

A new hybrid iron fluoride bipyridine with mixed valence: Fe2F5(2,2'-bipyridine)2H2O

Hydrothermal synthesis of iron fluoride compound, Fe2F5(2,2'-bipyridine)2H2O, and its characterization by single crystal X-ray diffraction is reported. The compound is found to crystallize in the triclinic space group . The monohydrate fluoroferrate of bipyridine is built up from Fe4F10N8 tetrahedron connected by eight nitrogen atoms of four 2,2'-bipyridine molecules and separated by H2O molecules. The main feature of this atomic arrangement is the coexistence of two oxidation states of iron cations and hybrid class II with 0-D dimensionality. Thermal and IR spectral analysis have been carried out for the title compound to confirm the hematite compound as residual and the presence of organic molecule , respectively. Magnetic characterization does not reveal any ferromagnetic component in the range of magnetic field from -20 kOe to 20 kOe at room temperature

Medidas preventivas para evitar afecciones a la salud por exposición al contaminante polvo en una planta chancadora de agregados para la construcción

El objetivo de la presente investigación es proponer medidas de prevención para evitar afecciones a la salud por exposición al contaminante polvo en una planta chancadora de agregados para la construcciónde la región Lambayeque. Para ello se evaluó indicadores comolas fuentes de emisión, cantidad de partículas respirables de polvo, número y tamaño de partículas, controles de polvo fugitivo, programas de vigilancia, entre otros. La propuesta permitirá que en el lugar de trabajo donde se dé cumplimiento alas normas legales vigentesde seguridad y salud en el trabajo.La metodología utilizada es cuantitativa, de diseño descriptivo, de tipo no experimental y correlacional. En una primera fasese identificó que el proceso de chancado de piedra y el tránsito de vehículos generan emisiones excesivas de polvo en el ambiente de trabajo. Estas emisiones fueron monitoreadas utilizando el muestreador de aire de alto volumen Thermo Scientific, VFC-PM10, donde se observó que el valor de la concentración (659.68 μg/m3)supera más de 6 veces la norma ambiental ECA del aire, y más de 12 veces el nivel de la OMS.En el estrato donde está ubicada la cantera de la que se extrae la materia prima para el proceso de chancado, INGEMMET realizó un análisis geoquímicoen la composición de las rocas ymineralesencontrando una concentración de SiO2entre 95.67-98.05 %. Así mismo a través de una encuesta aplicada a los trabajadores se evaluó la susceptibilidad personal que incrementa el riesgo de desarrollar afecciones a la salud por inhalación de polvo.Como resultado de lo aplicado, se propuso medidas de controlpara evitar la emisión y dispersión del contaminante polvo en el ambiente de trabajo y acciones de tipo administrativo para reducir la tasa de enfermedades ocupacionales. Finalmente se recomienda una posterior investigación para medir el impacto de la aplicación de las medidas preventivas propuestas.The present research aims to propose prevention measures to avoid health problems due to exposure to the dust pollutant in an aggregatescrushing plant for the construction of the Lambayeque region. For this, indicators such as emission sources, quantity of respirable dust particles, number and size of particles, fugitive dust controls, surveillance programs, among others, were evaluated. The proposal will allow the workplace to comply with the current legal regulations on safety and health at work.The methodology used is quantitative, descriptive in design, non-experimental and correlational. In a first phase, it was identified that the stone crushing process and the traffic of vehicles generate excessive dust emissions in the work environment. These emissions were monitored using the Thermo Scientific high volume air sampler, VFC-PM10, where it was observed that the concentration value (659.68 μg / m3) exceeds more than 6 times the ECA environmental standard of air, and more than 12 times the WHO level. In the stratum where the quarry from which the raw material is extracted for the crushing process is located, INGEMMET carried out a geochemical analysis on the composition of the rocks and minerals, finding a SiO2 concentration between 95.67-98.05%. Likewise, through a survey applied to the workers, the personal susceptibility that increases the risk of developing health conditions due to inhalation of dust was evaluated.As a result of what was applied, control measures were proposed to avoid the emission and dispersion of the pollutant dust in the work environment and administrative actions to reduce the rate of occupational diseases. Finally, a subsequent investigation is recommended to measure the impact of the application of the proposed preventive measures.Campus Chiclay

Green and blue materials for the ceramic industry from pink MgCoxNi1-xSiO4 (0 ≤ x ≤ 1) solid solutions

In this study, MgCoxNi1-xSiO4 (0.0 ≤ x ≤ 1.0) solid solutions with an olivine structure were synthetized via the chemical coprecipitation method and materials with a smaller M(II) (M = Co, Ni) amount than Co2SiO4 and Ni2SiO4 compounds were obtained. At 1200 °C, the Co(II) and Ni(II) were randomly distributed in the MgCoxNi1-xSiO4 (0.0 ≤ x ≤ 1.0) solid solutions with the olivine structure, but the occupation of Co(II) and Ni(II) ions in M1 (4a) octahedral sites was obtained at a higher level than in M2 (4c) octahedral sites. The Mg(II) ions prefer the M2 sites. This preference explains the main contribution of the M1 sites in spectra of octahedral Co(II) ions and the M1-O and M2-O distances jointly explain the pink colour of the MgCoxNi1-xSiO4 (0.0 ≤ x ≤ 1.0) solid solutions, while the colour of Co2SiO4 is blue. Spectra can be interpreted as the sum of Ni(II) and Co(II) ions in octahedral sites. When these solid solutions are enamelled, the pink colouring changes to green or blue because of the presence of tetrahedral Co(II).Funding for open access charge: CRUE-Universitat Jaume

Plasmonic nanodevice with magnetic funcionalities: fabrication and characterization

We have designed and fabricated a nanodevice exhibiting simultaneously ferromagnetic properties of nanostructures with plasmonic properties of continuous films. Our device consists of an array of nanomagnets on top of a continuous plasmonic film. The patterned nanomagnets magnetic state is single domain and well-defined shape anisotropy. Despite the presence of the patterned media on top of the Au film, the system exhibits surface plasmon resonance characteristics of a continuous film, i.e., propagating surface plasmon-polaritons