Clustering in ferronematics : The effect of magnetic collective ordering

Clustering of magnetic nanoparticles can dramatically change their collective magnetic properties, and it consequently may influence their performance in biomedical and technological applications. Owing to tailored surface modification of magnetic particles such composites represent stable systems. Here, we report ferronematic mixtures that contain anisotropic clusters of mesogen-hybridized cobalt ferrite nanoparticles dispersed in liquid crystal host studied by different experimental methods—magnetization measurements, small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), and capacitance measurements. These measurements reveal non-monotonic dependencies of magnetization curves and the Fréedericksz transition on the magnetic nanoparticles concentration. This can be explained by the formation of clusters, whose structures were determined by SAXS measurements. Complementary to the magnetization measurements, SANS measurements of the samples were performed for different magnetic field strengths to obtain information on the orientation of the liquid crystal molecules. We demonstrated that such hybrid materials offer new avenues for tunable materials

Exact results of the mixed-spin Ising model on a decorated square lattice with two different decorating spins of integer magnitudes

The mixed-spin Ising model on a decorated square lattice with two different decorating spins of the integer magnitudes S_B = 1 and S_C = 2 placed on horizontal and vertical bonds of the lattice, respectively, is examined within an exact analytical approach based on the generalized decoration-iteration mapping transformation. Besides the ground-state analysis, finite-temperature properties of the system are also investigated in detail. The most interesting numerical result to emerge from our study relates to a striking critical behaviour of the spontaneously ordered 'quasi-1D' spin system. It was found that this quite remarkable spontaneous order arises when one sub-lattice of the decorating spins (either S_B or S_C) tends towards their 'non-magnetic' spin state S = 0 and the system becomes disordered only upon further single-ion anisotropy strengthening. The effect of single-ion anisotropy upon the temperature dependence of the total and sub-lattice magnetization is also particularly investigated.Comment: 17 pages, 6 figure

Assessment of Antioxidants in Selected Plant Rootstocks

The service tree (Sorbus domestica) is a wild fruit tree with immense medicinal and industrial value. This study aimed at determining the four major groups of antioxidants (flavonoids, phenolic acids and aldehydes, catechin and procyanidin) in rootstocks of Crataegus laevigata (genotypes O-LE-14 and O-LE-21), Aronia melanocarpa (genotypes O-LE-14 and O-LE-21), Chaenomeles japonica (genotype O-LE-9) and Cydonia oblonga (BA 29) (genotypes O-LE-14 and O-LE-21). Hyperoside (Quercetin 3-D-galactoside) was the most abundant flavonoid compound, since its average content in the rootstocks of Crataegus laevigata (O-LE-21) was 180.68 +/- 0.04 mu g center dot g(-1). Dihydrokaempherol was the least frequently found flavonoid compound, with an average concentration of 0.43 +/- 0.01 mu g center dot g(-1) in all the rootstocks of plants considered in this study. Among the phenolic compounds, the most represented one was protocatechuic acid, with 955.92 +/- 10.25 mu g center dot g(-1) in the rootstocks of Aronia melanocarpa (O-LE-14). On the other hand, the least represented p-Coumaric acid exhibited the average concentration of 0.34 +/- 0.01 mu g center dot g(-1) in the plant rootstocks. Epicatechin was the most abundant catechin compound, with a content of 3196.37 +/- 50.10 mu g center dot g(-1) in the rootstocks of Aronia melanocarpa (O-LE-14). The lowest represented catechin compound was epigallocatechin, with the average concentration of 0.95 +/- 0.08 mu g center dot g(-1) in the screened plant rootstocks. From the procyanidin compounds, the most abundant one was procyanidin b2 in the rootstocks of Crataegus laevigata (O-LE-14), with a concentration of 5550.40 +/- 99.56 mu g center dot g(-1). On the contrary, procyanidin a2, with an average concentration of 40.35 +/- 1.61 mu g center dot g(-1), represented the least frequent procyanidin compound in all the plant rootstocks screened herein