Surface roughness effects on squeeze film behavior in porous circular disks with couple stress fluid

The effect of surface roughness on squeeze film behavior between two circular disks with couple stress lubricant is analyzed when the upper disk has porous facing which approaches the lower disk with uniform velocity. The modified Stochastic Reynolds equation is derived on the basis of Stokes micro-continuum theory for couple stress fluid and Christensen Stochastic theory for the rough surface. Closed form solution of the Stochastic Reynolds equation is obtained in terms of Fourier–Bessel series. The importance of roughness and couple stress on bearing characteristics are presented in terms of load carrying capacity, squeeze time, and relative percentage of the load. It is observed that, effect of couple stress fluid, and surface roughness is more pronounced compared to classical case. These predictions enable design engineers to choose suitable parameters.     

Catechol derivatives-coated Fe3O4 and γ-Fe2O3 nanoparticles as potential MRI contrast agents

Superparamagnetic iron oxide nanoparticles, Fe₃O₄ and γ-Fe₂O₃, were produced by the so-called polyol process. In order to stabilize the particles in a physiological environment as potential contrast agents for Magnetic Resonance Imaging (MRI), the as-prepared particles were successfully transferred to an aqueous medium through ligand exchange chemistry of the adsorbed polyol species with the dopamine or the catechaldehyde. The ligands were able to participate in bidentate binding to the nanoparticles surface and to improve the stability of aqueous suspensions of the nanoparticles. Analysis was performed by various techniques including X-ray diffraction, transmission electron microscopy, infrared spectroscopy and thermal analysis. The results of magnetic measurements and initial in vitro magnetic resonance imaging essays are presented for the pre- and post-surface modified nanoparticles, respectively and discussed in relation with their structure and microstructure.     

The thermal analysis of lipids isolated from various tissues of deers and does

TG analysis of lipids is a suitable analytical method that offers the possibility to correlate kinetic parameters of thermal degradation (activation energy) and lipid composition. For this purpose, an inert (nitrogen) or oxidising atmosphere (oxygen) was applied during the thermal treatment (30–220°C) of lipids isolated from intramuscular and fatty tissues (L-IMT and L-FT) of deers and does. Prior to investigation, the extracted samples of lipids were kept at –24°C or +4°C for nine months, thus enabling detection of the influence of storage temperature on the thermal behaviour of the lipids.     

Cation Co-intercalation in Potassium Copper(II) Hexacyanoferrates

The cation-insertion solid state electrochemistry of a potassium copper(II) hexacyanoferrate in contact with LiClO₄/DMSO, NaPF₆/DMSO, and KPF₆/DMSO electrolytes has been theoretically and experimentally studied using the voltammetry of immobilized particles methodology. Voltammetric data, combined with SEM/EDS analysis permit to determine a K_0.876Cu^II_1.328Fe^III_0.049[Fe^III_0.318Fe^II_0.682(CN)₆] stoichiometry for the synthesized solid. Separation of electronic and ionic contributions to Gibbs energy changes can be made based on cyclic voltammetric and open circuit potential measurements. These parameters can be combined to measure values of the Gibbs energy of cation-independent electron transfer of 7.2±0.4 (K⁺), 7.1±0.5 (Na⁺) kJ mol⁻¹, in close agreement with the expected independence of this parameter on the electrolyte cation. The reduction Fe(III) centers bound to cyano groups exhibit a cation-dependent, essentially Nernstian character which can be described in terms of Na⁺ and K⁺ insertion/deinsertion while in the case of Li⁺ electrolytes there is significant co-cation diffusion. Chronoamperometric data provide estimates of the diffusion coefficients of Na⁺, and K⁺ ions through the solid around 10⁻⁹ cm² s⁻¹.