In the present study, we investigate the flow of a paramagnetic fluid in a two dimensional heated channel when an external magnetic gradient is imposed. In the fully developed regime, an analytical solution shows that a flow reversal may occur; the condition of this is given n terms of the Reynolds number. Numerical simulations are then carried out for more general situations. It is shown that the analytical model gives good qualitative predictions.

In the current paper application of magnetic abrasive polishing process, on paramagnetic workpieces is investigated. A magnetic disc which comprises of six magnetic coils and is electrified with three phase AC current is used to perform the experiments. In the experimental setup various parameters including; rotational speed of abrasive pins, quantity of abrasive pins, working gap, abrasive pins' dimensions and process's time can be changed. Changing this parameters surface quality is investigated. Two kinds of workpieces with different mechanical properties are examined. It is observed that both increasing the rotational speed and using smaller pins improve final surface quality but the rotational speed has a sharper effect. There are optimum abrasive pins quantity and working gap in which the best surface quality is obtained. The results are similar for the both selected materials.

Introduction: Use of an adhesive with a suitable composite resin is an important factor in tooth-colored restorations and increasing marginal sealing ability. The aim of this study was to evaluate the microleakage of various adhesives with composite resins using fluid filtration and dye extraction techniques and assessment of the correlation between these two techniques.Materials and Methods: In this in vitro study, class II cavities were prepared on the proximal surfaces of 48 extracted sound human premolar teeth, measuring 1.5±0.5 mm in gingival width, 4 mm in occluso-gingival height and 1.3 of the inter-cuspal distance in width. The samples were divided into four groups (n=12). Group 1; OptiBond Solo Plus adhesive/Herculite XRV composite resin; Group 2: OptiBond Solo Plus adhesive/Master Dent composite resin; Group 3: Prime & Bond NT adhesive/Herculite XRV composite resin; Group 4: Prime & Bond NT adhesive/Master Dent composite resin. Microleakage was assessed primarily by fluid filtration and then by dye extraction techniques. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests, with Bonferroni correction and Spearman's rho correlation test at 95% confidence interval.Results: The minimum and maximum mean microleakage values were recorded in fluid filtration and dye extraction techniques groups 1 and 4, respectively. There were significant differences between the experimental groups in microleakage with the two methods of leakage assessment (p value=0.001). Spearman's rho revealed a strongly direct correlation between the two methods (r=0.797, p value=0.000).Conclusion: In both methods of microleakage assessment, use of ethanol-based in comparison to acetone-based adhesive resulted in microleakage reduction. Application of light-cured composite resin contrary to self-cured composite resin with both types of adhesives increased marginal sealing ability.

Dust lattice modes are studied in a hexagonal two-dimensional lattice in plasma crystal, including paramagnetic dust particles. The gradients of magnetic fields, electric fields, and dust charge and also the interaction of dipole-dipole take into account. These gradients modify the levitation condition and affect the frequencies of dust lattice waves. The coupling between in-plane and out-of-plane modes gives rise to the hybrid mode, which is always an unstable mode. However, intersection of the in-plane mode with other modes does not result in mode-coupling instability.

In the article, first a trinuclear complex under formula [Mn (phen)2(H2O) (m-NCS) Cu (NCS)4(m-NCS) Mn (phen)2(H2O)] that (phen=1, 10- phenanthroline) has been synthesized. This complex characterized by FT-IR, UV-Vis spectroscopirs. The electrochemical behavior of the complex was investigated by cyclic voltammeteric method. Crystal of complex was placed in the furnace at 950oC for 5h to become oxide particle of CuMn2O4. Nano oxide particle was carried out using FT-IR, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Magnetic behavior of nanoparticle characterized using VSM. SEM images show that the particles have same morphology with less than 100 nm size. XRD show nanoparticles have single phase with cubic symmetry.The particle size of about 18 nm is formed. SEM images showed that the morphology of the particles obtained are almost identical with globular form.

The radiation effect on the thermo-magnetic convection which occurs in participating paramagnetic medium under microgravity (g = 0) condition is numerically investigated. Different from the electrically conducting fluid, the paramagnetic fluid is driven by Kelvin force which is proportional to the product of magnetic susceptibility and the gradient of the square of the magnetic induction and is introduced into the source term of the Navier-Stokes equation. In order to realize the fluid flow, an external magnetic field with uniform or non-uniform magnetic gradient is imposed. Further, the thermo-magnetic convection is carried out in high temperature field, in which the magnetic susceptibility varies greatly with absolute temperature according to Curie's law, and the radiation field is also modified by the absorbing-emitting paramagnetic medium. In the present study, the effects of magnetic Rayleigh number and optical thickness are investigated. The results show that radiative heat transfer plays a significant role in thermo-magnetic convection.

A novel magnetically immobilized polyethyleneimine (PEI) fabricated by covalently anchoring on silica coated Fe3O4 nanoparticles (PEI@Si-MNPs) was prepared. The synthesized catalyst was characterized by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The immobilized PEI was shown to be an efficient heterogeneous catalyst for the synthesis of spiro-oxindole, benzopyranes and chromene derivatives via multi-component reaction (MCR), in water as a green solvent. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.