Preparation and magnetic characteristics of Co1−δZnδFe2O4 ferrite nanopowders

In the present paper the Co1 Zn Fe2O4 (0 1) ferrite nanopowders with a spinel type structure were synthesized using a chemical co-precipitation technique with constant flow rate FR = 120 cm3/min at three different reaction temperatures i.e. Tr = 50 C, 70 C and 90 C. Magnetic and structural characteristics of the obtained materials were investigated by means of X-ray diffraction method, transmission electron microscopy and vibrating sample magnetometer. In the course of studies hysteresis loops M( 0H) and the relations of magnetization M7T (determined at 0H = 7 T), squareness ratio S and the Néel temperature TN versus Zn content were determined and discussed in detail. It was shown that for < 0:6 the increase in reaction temperature Tr results in a significant increase of the measured magnetic characteristics. In particular, in the case of Co0:8Zn0:2Fe2O4 ferrite nanopowder magnetization M7T reaches maximal value of about 80 emu/g

The Ionizing Radiation-Induced Bystander Effect: Evidence, Mechanism, and Significance

It has long been considered that the important biological effects of ionizing radiation are a direct consequence of unrepaired or misrepaired DNA damage occurring in the irradiated cells. It was presumed that no effect would occur in cells in the population that receive no direct radiation exposure. However, in vitro evidence generated over the past two decades has indicated that non-targeted cells in irradiated cell cultures also experience significant biochemical and phenotypic changes that are often similar to those observed in the targeted cells. Further, nontargeted tissues in partial body-irradiated rodents also experienced stressful effects, including oxidative and oncogenic effects. This phenomenon, termed the “bystander response,” has been postulated to impact both the estimation of health risks of exposure to low doses/low fluences of ionizing radiation and the induction of second primary cancers following radiotherapy. Several mechanisms involving secreted soluble factors, oxidative metabolism, gap-junction intercellular communication, and DNA repair, have been proposed to regulate radiation-induced bystander effects. The latter mechanisms are major mediators of the system responses to ionizing radiation exposure, and our knowledge of the biochemical and molecular events involved in these processes is reviewed in this chapter

Preparation and Magnetic Characteristics of Co 1-δ

In the present paper the Co1 Zn Fe2O4 (0 1) ferrite nanopowders with a spinel type structure were synthesized using a chemical co-precipitation technique with constant flow rate FR = 120 cm3/min at three different reaction temperatures i.e. Tr = 50 C, 70 C and 90 C. Magnetic and structural characteristics of the obtained materials were investigated by means of X-ray diffraction method, transmission electron microscopy and vibrating sample magnetometer. In the course of studies hysteresis loops M( 0H) and the relations of magnetization M7T (determined at 0H = 7 T), squareness ratio S and the Néel temperature TN versus Zn content were determined and discussed in detail. It was shown that for < 0:6 the increase in reaction temperature Tr results in a significant increase of the measured magnetic characteristics. In particular, in the case of Co0:8Zn0:2Fe2O4 ferrite nanopowder magnetization M7T reaches maximal value of about 80 emu/g

Development of membrane conductance improves coincidence detection in the nucleus laminaris of the chicken

Coincidence detection at the nucleus laminaris (NL) of a chicken was improved between embryos (embryonic days (E) 16 and 17) and chicks (post-hatch days (P) 2–7) in slice preparations. Electrical stimuli were applied bilaterally to the projection fibres to the NL at various intervals. The response window corresponding to the temporal separation of electrical stimuli that resulted in half-maximal firing probability was adopted as the measure of coincidence detection, and was narrower in chicks (1.4 ms) than in embryos (3.9 ms). Between these two ages, the membrane time constant of NL neurons was reduced from 18.4 to 3.2 ms and the membrane conductance was increased 5-fold, while no difference was measured in the input capacitance. Evoked EPSCs decayed slightly faster in chicks, while the size and the time course of miniature EPSCs were unchanged. Action potentials had lower thresholds and larger after-hyperpolarization in chicks than in embryos. Dendrotoxin-I depolarized cells and increased their input resistance significantly at both ages, eliminated the after-hyperpolarization, and delayed the decay phase of action potentials, indicative of the expression of low-threshold K+ channels. Cs+ hyperpolarized the cells, increased the input resistance and eliminated sags during hyperpolarization at both ages, while the hyperpolarization sag was affected by neither Ba2+ nor TEA. These data indicate the expression of hyperpolarization-activated cation channels. Between these two ages, the maximum conductance of low-threshold K+ channels increased 4-fold to about 16 nS, and hyperpolarization-activated channels increased 6-fold to about 10 nS. Improvement of coincidence detection correlated with the acceleration of the EPSP time course as a result of the increase of these conductances