TESTING THE COBALT ION EMISSION ON THE STAND FOR DIFFERENT ANGLES OF POSITIONING THE COMPONENTS OF THE METAL–METAL HIP JOINT ENDOPROSTHESIS

The paper deals with the subject related to the assessment of the influence of the axis angle of the metal components of the hip joint on the emission of cobalt ions. The tribological tests were carried out with the use of a simulator for the examination of hip joint endoprostheses, the structure of which enables the fixation of endoprosthesis components in accordance with the anatomical structure of the human hip joint. During the tests, the simulator performs flexion and extension movements as well as loads occurring in the human hip joint while walking. Loss-wear tests were carried out for nine variants of the “head–cup” system settings. These settings were determined on the basis of CT images obtained from patients after arthroplasty. After the tribological tests were completed, samples of the lubricating fluid with the wear products suspended in it were collected in order to determine the concentration of cobalt ions, which was carried out using the atomic absorption spectrometry method. As a result, the influence of the head antetorsion angle (α) and the acetabular anteversion angle (β) on the concentration of cobalt ions was analysed.

Cobalt-doped Ti surface promotes immunomodulation

Here, cobalt-doped plasma electrolytic oxidation (PEO) coatings with different cobalt contents were prepared on Ti implants. The cobalt ions in the PEO coating exhibited a slow and sustainable release and thus showed excellent biocompatibility and enhanced cell adhesion. In vitro ELISA and RT-PCR assays demonstrated that the cobalt-loaded Ti showed immunomodulatory functions to macrophages and upregulated the expression of anti-inflammatory (M1 type) genes and downregulated expression levels of pro-inflammatory (M2 type) genes compared with that of pure Ti sample. High cobalt content induced increased macrophage polarization into the M2 type. Furthermore, the findings from the in vivo air pouch model suggested that cobalt-loaded Ti could mitigate inflammatory reactions. The present work provides a novel strategy to exploit the immunomodulatory functions of implant materials.

Mössbauer investigation of Co-doped Bismuth Ferrite prepared by the solution method

In this work, [Formula: see text] ([Formula: see text] = 0, 0.08) nanoparticles were synthesized by the solution method and their structural differences were studied. X-ray diffraction results show that the rhombohedral R3c space group and perovskite structures are detected in both samples, accompanied by an impurity phase. The (104) and (110) peaks merge when cobalt ions are doped. The decrease in lattice parameters indicates that the microstructure of the nanoparticles becomes gradually distorted. Mössbauer spectroscopy analysis at room temperature reveals an additional doublet due to the oxygen vacancies in [Formula: see text]. Hyperfine interactions, spatial spin-modulated structures and oxygen deficiencies around iron ions are also reflected in the observed spectra and variations in hyperfine parameters.

Influence of the structure of titenium phosphate on sorption properties

The process of sorption of lead, zinc, cadmium and cobalt ions from aqueous solutions on titanium-containing sorbents of various compositions is studied. Langmuir, Freundlich and Temkin models were used to determine sorption equilibrium. It was found that the process of sorption of metal ions on sorbents is described with the maximum probability by the Langmuir equation. The data obtained made it possible to determine the affinity of the metal to the sorbent and to compose a selectivity series.

Water in the Alluaudite Type-Compounds: Synthesis, Crystal Structure and Magnetic Properties of Co3(AsO4)0.5+x(HAsO4)2−x(H2AsO4)0.5+x[(H,□)0.5(H2O,H3O)0.5]2x+

In this study, a new cobalt arsenate belonging to the alluaudite supergroup compounds with the general formula of Co3(AsO4)0.5+x(HAsO4)2−x(H2AsO4)0.5+x[(H,□)0.5(H2O,H3O)0.5]2x+ (denoted as CoAsAllu) was synthesized under hydrothermal conditions. Its crystal structure was determined by a room-temperature single-crystal X-ray diffraction analysis: space group C2/c, a = 11.6978(8), b = 12.5713(7), c = 6.7705(5) Å, β = 113.255(5)°, V = 914.76(11) Å3, Z = 2 for As6H8Co6O25. It represents a new member of alluaudite-like protonated arsenates and the first alluaudite-like phase showing both protonation of the tetrahedral site and presence of the H2O molecules in the channels. In the asymmetric unit of CoAsAllu, one of the two Co, one of the two As and one of the seven O atoms lie at 4e special positions (site symmetry 2). The crystal structure consists of the infinite edge-shared CoO6 octahedra chains, running parallel to the [101¯] direction. The curved chains are interconnected by [(As1O4)0.5(H2As1O4)0.5]2− and [HAs2O4]2− tetrahedra forming a heteropolyhedral 3D open framework with two types of parallel channels. Both channels run along the c-axis and are located at the positions (1/2, 0, z) and (0, 0, z), respectively. The H2 and H4 hydrogen atoms of O2H2 and O4H4 hydroxyl groups are situated in channel 1, while the uncoordinated water molecule H2O7 at half-occupied 4e special positions and hydrogen atoms of O6H6 hydroxyl group were found in channel 2. The results of the magnetic investigations confirm the quasi one-dimensional structure of divalent cobalt ions. They are antiferromagnetically coupled with the intrachain interaction parameter of J ≈ −8 cm−1 and interchain parameter of J’ ≈ −2 cm−1 that become effective below the Néel temperature of 3.4 K.

Conductive bimetal organic framework nanorods decorated with highly dispersed Co3O4 nanoparticles as bi-functional electrocatalyst

The poor electronic conductivity and low intrinsic electrocatalytic activity of metal organic frameworks (MOFs) greatly limit their direct application in electrocatalytic reactions. Herein, we report a conductive two-dimensional π–d conjugated Ni and Co bimetal organic framework (MOF)——NiCo-(2,3,6,7,10,11-hexaiminotriphenylene) (NiCo-HITP) nanorods decorated with highly dispersed Co3O4 nanoparticles (NPs) as a promising bi-functional electrocatalyst towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through an effective and facile strategy by modifying the rod-shaped Ni3(HITP)2 crystals using cobalt ions. The triggered electrocatalytic activity of the resulting MOF-based materials was achieved by increasing the electrical conductivity (7.23 S cm-1) originated from Ni3(HITP)2 substrate and also by creating the cooperative catalysis sites of Co-Nx and Co3O4 NPs. Optimized syntheses show a promising ORR activity with a high half-wave potential (0.77 V) and also a significantly improved OER activity compared with pure Ni3(HITP)2 in alkaline electrolyte. Furthermore, a rechargeable Zn–air battery using the as-prepared material as air-cathode also shows a high power density (143.1 mW cm-2) –even comparable to a commercial Pt/C-RuO2-based battery. This methodology offers a new prospect in the design and synthesis of non-carbonized MOF bi-functional electrocatalysts for efficient catalysis towards ORR and OER.

Examination of the Catalytic Role of the Axial Cystine Ligand in the Co-Type Nitrile Hydratase from Pseudonocardia thermophila JCM 3095

The strictly conserved αSer162 residue in the Co-type nitrile hydratase from Pseudonocardia thermophila JCM 3095 (PtNHase), which forms a hydrogen bond to the axial αCys108-S atom, was mutated into an Ala residue. The αSer162Ala yielded two different protein species: one was the apoform (αSerA) that exhibited no observable activity, and the second (αSerB) contained its full complement of cobalt ions and was active with a kcat value of 63 ± 3 s−1 towards acrylonitrile at pH 7.5. The X-ray crystal structure of αSerA was determined at 1.85 Å resolution and contained no detectable cobalt per α2β2 heterotetramer. The axial αCys108 ligand itself was also mutated into Ser, Met, and His ligands. All three of these αCys108 mutant enzymes contained only half of the cobalt complement of wild-type PtNHase, but were able to hydrate acrylonitrile with kcat values of 120 ± 6, 29 ± 3, and 14 ± 1 s−1 for the αCys108His, Ser, and Met mutant enzymes, respectively. As all three of these mutant enzymes are catalytically competent, these data provide the first experimental evidence that transient disulfide bond formation is not catalytically essential for NHases.