In-situ activated hydrogen evolution by molybdate addition to neutral and alkaline electrolytes

Activation of the hydrogen evolution reaction (HER) by in-situ addition of Mo(VI) to the electrolyte has been studied in alkaline and pH neutral electrolytes, the latter with the chlorate process in focus. Catalytic molybdenum containing films formed on the cathodes during polarization were investigated using scanning electron microscopy (SEM), energy-dispersive X ray analysis (EDS), X-ray photoelectron spectroscopy (XPS), and X ray fluorescence (XRF). In-situ addition of Mo(VI) activates the HER on titanium in both alkaline and neutral electrolytes and makes the reaction kinetics independent of the substrate material. Films formed in neutral electrolyte consisted of molybdenum oxides and contained more molybdenum than those formed in alkaline solution. Films formed in neutral electrolyte in the presence of phosphate buffer activated the HER, but were too thin to be detected by EDS. Since molybdenum oxides are generally not stable in strongly alkaline electrolyte, films formed in alkaline electrolyte were thinner and probably co-deposited with iron. A cast iron molybdenum alloy was also investigated with respect to activity for HER. When polished in the same way as iron, the alloy displayed a similar activity for HER as pure iron

Highly dense and chemically stable proton conducting electrolyte sintered at 1200 \ub0C

The BaCe 0.7 Zr 0.1 Y 0.2−x Zn x O 3−δ (x = 0.05, 0.10, 0.15, 0.20) has been synthesized by the conventional solid state reaction method for application in protonic solid oxide fuel cell. The phase purity and lattice parameters of the materials have been studied by the room temperature X-ray diffraction (XRD). Scanning electron microscopy (SEM) has been done for check the morphology and grain growth of the samples. The chemical and mechanical stabilities have been done using thermogravimetric analysis (TGA) in pure CO 2 environment and thermomechanical analysis (TMA) in Argon atmosphere. The XRD of the materials show the orthorhombic crystal symmetry with Pbnm space group. The SEM images of the pellets show that the samples sintered at 1200 \ub0C are highly dense. The XRD after TGA in CO 2 and thermal expansion measurements confirm the stability. The particles of the samples are in micrometer ranges and increasing Zn content decreases the size. The conductivity measurements have been done in 5% H 2 with Ar in dry and wet atmospheres. All the materials show high proton conductivity in the intermediate temperature range (400–700 \ub0C). The maximum proton conductivity was found to be 1.0 7 10 −2 S cm −1 at 700 \ub0C in wet atmosphere for x = 0.10. From our study, 10 wt % of Zn seems to be optimum at the B-site of the perovskite structure. All the properties studied here suggest it can be a promising candidate of electrolyte for IT-SOFCs

The Fluorite-Like Phase Nd₅Mo₃O_16±δ in the MoO₃–Nd₂O₃ System: Synthesis, Crystal Structure, and Conducting Properties

This paper describes a study of the system MoO₃–Nd₂O₃ using a combination of X-ray powder diffraction (XRD), neutron powder diffraction (NPD), thermogravimetric analysis (TGA), and ac impedance spectroscopy (IS). A phase-pure material is observed at a composition of 45.5 mol % Nd₂O₃, which corresponds to an ideal stoichiometry of Nd₅Mo₃O_16.5. XRD and NPD show that the crystal structure is a superstructure of the fluorite arrangement, with long-range ordering of the two cation species leading to a doubled unit cell parameter. The sample is found to be significantly oxygen deficient, i.e. Nd₅Mo₃O_15.63(4), when it is prepared by a solid-state reaction at 1473 K in air. TGA measurements indicate that the sample loses only minimal mass on heating to 1273 K in O₂. IS studies of the mean conductivity under different atmospheres show that the sample is a mixed conductor between ambient temperature and 873 K, with a dominant electronic component at higher temperatures, as demonstrated by measurements under inert atmosphere. NPD measurements indicate that the anion vacancies are preferentially located on the O2 sites, while studies of the temperature dependence performed under an O₂ atmosphere to 1273 K show significantly anisotropic thermal parameters of the anions. Together with analysis of the total neutron scattering data, this supports a model of oxygen ions hopping between O2 positions, with a vacancy, rather than interstitial, mechanism for the anion diffusion

Sr2GaScO5, Sr10Ga6Sc4O25, and SrGa0.75Sc0.25O2.5 : a Play in the Octahedra to Tetrahedra Ratio in Oxygen-Deficient Perovskites

Three different perovskite-related phases were isolated in the SrGa1-xScxO2.5 system: Sr2GaScO5, Sr10Ga6Sc4O25, and SrGa0.75Sc0.25O2.5, Sr2GaScO5 (x = 0.5) crystallizes in a brownrnillerite-type structure [space group (S.G.) Icmm, a = 5.91048(5) angstrom, b = 15.1594(1) angstrom, and c = 5.70926(4) angstrom] with complete ordering of Sc3+ and Ga3+ over octahedral and tetrahedral positions, respectively. The crystal structure of Sr10Ga6Sc4O25 (x = 0.4) was determined by the Monte Carlo method and refined using a combination of X-ray, neutron, and electron diffraction data [S.G. I4(1)/a, a = 17.517(1) angstrom, c = 32.830(3) angstrom]. It represents a novel type of ordering of the B cations and oxygen vacancies in perovskites. The crystal structure of Sr10Ga6Sc4O25 can be described as a stacking of eight perovskite layers along the c axis ...[-(Sc/Ga)O-1.6-SrO0.8-(Sc/Ga)O-1.8-SrO0.8-](2 center dot center dot center dot) Similar to Sr2GaScO5, this structure features a complete ordering of the Sc3+ and Ga3+ cations over octahedral and tetrahedral positions, respectively, within each layer. A specific feature of the crystal structure of Sr10Ga6Sc4O25 is that one-third of the tetrahedra have one vertex not connected with other Sc/Ga cations. Further partial replacement of Sc3+ by Ga3+ leads to the formation of the cubic perovskite phase SrGa0.75Sc0.25O2.5 (x = 0.25) with a = 3.9817(4) angstrom. This compound incorporates water molecules in the structure forming SrGa0.75Sc0.25O2.5 center dot xH(2)O hydrate, which exhibits a proton conductivity of similar to 2.0 x 10(-6) S/cm at 673 K

Prevalence and molecular detection of the causal agents of sub-clinical mastitis in dairy cows in Sirajganj and Pabna districts, Bangladesh

Objective: The present research work was undertaken with the objectives to investigate the prevalence and molecular detection of the causal agents of sub-clinical mastitis (SCM) in cows at milk shed areas in Sirajganj and Pabna districts, Bangladesh. Materials and methods: A total of 300 milk samples were randomly collected from Baghabari milk shed areas of Sirajganj and Pabna districts. The milk samples were subjected for California Mastitis Test (CMT) for identifying SCM. Total 81 positive samples were then used for the isolation and identification of associated bacteria and fungi using conventional microbiological examination and biochemical tests, followed by confirmation by polymerase chain reaction (PCR) using specific primers. Besides, universal primers were used for amplification and sequencing of PCR products where specific primers were not used. Results: The overall prevalence of SCM was 51% (n=153/300). Based on bacteriological examination and biochemical tests, several bacteria were identified in this study; the orgnaisms included Staphylococcus sp. (45.68%), Streptococcus uberis (14.81%), Escherichia coli (9.88%), Proteus sp. (19.75%), Salmonella sp. (1.23%), Acinetobacter sp. (7.41%), and fungus (1.23%). PCR technique confirmed the bacteria as Staphylococcus aureus (279-bp), Streptococcus uberis (884-bp), E. coli (16SrRNA 585-bp, stx1 606-bp, rfbO157 497-bp) and Salmonella sp. (Inv-A gene796-bp). Conclusion: This study reveals that SCM in dairy cattle is persisting in Sirajganj and Pabna districts of Bangladesh. Hygienic practices should be improved, and providing technical intereventions may reduce the rate of SCM in the study areas. [J Adv Vet Anim Res 2017; 4(4.000): 378-384

Sr₂GaScO₅, Sr₁₀Ga₆Sc₄O₂₅, and SrGa_0.75Sc_0.25O_2.5: a Play in the Octahedra to Tetrahedra Ratio in Oxygen-Deficient Perovskites

Three different perovskite-related phases were isolated in the SrGa_1–<i>x</i>Sc_<i>x</i>O_2.5 system: Sr₂GaScO₅, Sr₁₀Ga₆Sc₄O₂₅, and SrGa_0.75Sc_0.25O_2.5. Sr₂GaScO₅ (<i>x</i> = 0.5) crystallizes in a brownmillerite-type structure [space group (S.G.) <i>Icmm</i>, <i>a</i> = 5.91048(5) Å, <i>b</i> = 15.1594(1) Å, and <i>c</i> = 5.70926(4) Å] with complete ordering of Sc³⁺ and Ga³⁺ over octahedral and tetrahedral positions, respectively. The crystal structure of Sr₁₀Ga₆Sc₄O₂₅ (<i>x</i> = 0.4) was determined by the Monte Carlo method and refined using a combination of X-ray, neutron, and electron diffraction data [S.G. <i>I</i>4₁/<i>a</i>, <i>a</i> = 17.517(1) Å, <i>c</i> = 32.830(3) Å]. It represents a novel type of ordering of the B cations and oxygen vacancies in perovskites. The crystal structure of Sr₁₀Ga₆Sc₄O₂₅ can be described as a stacking of eight perovskite layers along the <i>c</i> axis ...[−(Sc/Ga)­O_1.6–SrO_0.8–(Sc/Ga)­O_1.8–SrO_0.8−]₂.... Similar to Sr₂GaScO₅, this structure features a complete ordering of the Sc³⁺ and Ga³⁺ cations over octahedral and tetrahedral positions, respectively, within each layer. A specific feature of the crystal structure of Sr₁₀Ga₆Sc₄O₂₅ is that one-third of the tetrahedra have one vertex not connected with other Sc/Ga cations. Further partial replacement of Sc³⁺ by Ga³⁺ leads to the formation of the cubic perovskite phase SrGa_0.75Sc_0.25O_2.5 (<i>x</i> = 0.25) with <i>a</i> = 3.9817(4) Å. This compound incorporates water molecules in the structure forming SrGa_0.75Sc_0.25O_2.5·<i>x</i>H₂O hydrate, which exhibits a proton conductivity of ∼2.0 × 10^–6 S/cm at 673 K