Modified Mode1 of Initial Magnetic Permeability of Polycrystalline Ferrites

A modified model of the initial magnetic permeability (IMP) is offered for a wide class of polycrystalline ferrites (PF) : Ni and NiZn ferrites, YIG. Within the scope of this model, IMP and other structure-dependent properties of normally sintered ferrites are explained by two pinning mechanisms of the displacing flat domain walls (DW). The main mechanism is due to the interaction between DW and the inhomogeneous microstresses in the immediate vicinity of the grain boundaries (GB). The second mecchanism occurs due to the closure domains

Analysis of Grains Distribution Effects on the Magnetic Spectra of Polycrystalline Ferrites

The effects of grain size distribution of soft polycrystalline ferrites on its domain wall initial susceptibility magnetic spectra are analyzed. It is shown that absorption component of spectrum may be inhomogeneously broadened, and that it formally reproduces the grain size distribution density function. Explicit relations for the absorption component and some characteristic parameters of spectrum are presented

Embryonic Stem Cell Marker Expression Pattern in Human Mesenchymal Stem Cells Derived from Bone Marrow, Adipose Tissue, Heart and Dermis

Mesenchymal stem cells (MSCs) have been isolated from a variety of human tissues, e.g., bone marrow, adipose tissue, dermis, hair follicles, heart, liver, spleen, dental pulp. Due to their immunomodulatory and regenerative potential MSCs have shown promising results in preclinical and clinical studies for a variety of conditions, such as graft versus host disease (GvHD), Crohn's disease, osteogenesis imperfecta, cartilage damage and myocardial infarction. MSC cultures are composed of heterogeneous cell populations. Complications in defining MSC arise from the fact that different laboratories have employed different tissue sources, extraction, and cultivation methods. Although cell-surface antigens of MSCs have been extensively explored, there is no conclusive evidence that unique stem cells markers are associated with these adult cells. Therefore the aim of this study was to examine expression of embryonic stem cell markers Oct4, Nanog, SOX2, alkaline phosphatase and SSEA-4 in adult mesenchymal stem cell populations derived from bone marrow, adipose tissue, dermis and heart. Furthermore, we tested whether human mesenchymal stem cells preserve tissue-specific differences under in vitro culture conditions. We found that bone marrow MSCs express embryonic stem cell markers Oct4, Nanog, alkaline phosphatase and SSEA-4, adipose tissue and dermis MSCs express Oct4, Nanog, SOX2, alkaline phosphatase and SSEA-4, whereas heart MSCs express Oct4, Nanog, SOX2 and SSEA-4. Our results also indicate that human adult mesenchymal stem cells preserve tissue-specific differences under in vitro culture conditions during early passages, as shown by distinct germ layer and embryonic stem cell marker expression patterns. Studies are now needed to determine the functional role of embryonic stem cell markers Oct4, Nanog and SOX2 in adult human MSCs