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Absence of ferroelectricity in BiMnO3 ceramics J. Appl. Phys. 112, 074112 (2012) Improved performances of polymer-based dielectric by using inorganic/organic core-shell nanoparticles Appl. Phys. Lett. 101, 142901 (2012) Spatial power combination within fan-shaped region using anisotropic zero-index metamaterials Appl. Phys. Lett. 101, 141902 (2012) The Thomas-Fermi model in the theory of systems of charged particles above the surface of liquid dielectricsThe dielectric properties of Mn x Ni 0.5Ϫx Zn 0.5 Fe 2 O 4 ferrites with x varying from 0.05 to 0.4 synthesized by the citrate precursor method have been investigated as a function of frequency, temperature, composition, and sintering temperature. An increase in the dielectric constant is observed with the increase in Mn concentration except for xϭ0.3. Dispersion in the dielectric constant with frequency in the range of 100 Hz-1 MHz is observed. Resonance peaks were observed in tan ␦ versus frequency curves for all samples. A shift in the resonance frequency towards higher frequency is observed with increase in temperature. The peak height also increases with increase in temperature. Possible mechanisms contributing to these processes have been discussed. From the temperature variation of the dielectric relaxation, activation energies for various samples have been calculated and compared with those obtained from dc resistivity.

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Part I Cell loss in rats with a normal mucosaThe concept of continuous epithelial renewal in the gastrointestinal tract was introduced at the end of the nineteenth century (Patzelt, 1882;Bizzozero, 1888;Schaffer, 1891), and since then labelling experiments with tritium-labelled thymidine have established that epithelial cells are produced in the crypts of the small intestinal mucosa, migrate up onto the villi and are lost at the tips, both in experimental animals (Leblond and Messier, 1958;Quastler and Sherman, 1959;Creamer, Shorter, and Bamforth, 1961) and in man (Shorter, Moertel, Titus, and Reitemeier, 1964;MacDonald, Trier, and Everett, 1964). It has been previously considered that epithelial cells migrate up from the mouth of the crypts directly onto villi on all sides, and it has therefore been assumed that there is an orderly one-to-one relationship of crypts to villi, with one crypt orifice between adjacent villi. In another communication (Loehry and Creamer, 1968) we have established that the crypt-villus relationship in the small intestinal mucosa is more complex than has been assumed, that overall there are many more crypts than villi, that very few of the crypts open out onto villi on all sides, and that, in most cases, much of each crypt opening is adjacent not to villi but to other crypts. The migration therefore of epithelial cells from crypts to villi cannot be a simple direct progression as might be expected from two-dimensional sections. Two possibilities exist: those cells emerging at sites where two crypts are adjacent must either be desquamated here at the crypt mouth or else be channelled round in some way onto villi. Because of this complex crypt-villus relationship it was thought necessary to undertake a reappraisal of cell migration, and, in order to establish whether cells were desquamated at the crypt mouth or channelled onto villi, to study the problem by a consideration of cell loss. METHODS AND TECHNIQUESDesquamated epithelial cells were collected from male 13 albino rats by total small intestinal perfusion. The animals were anaesthetized with intraperitoneal nembutal and the abdomen was opened by a midline incision. A length of 1 mm diameter PVC tubing was passed through the mouth into the rat's stomach, and guided through the pylorus into the fourth part of the duodenum where it was tied by a silk ligature. Another piece of PVC tubing, 4 mm in diameter, was passed through a small incision in the caecum and tied in place in the distal ileum. This cannula passed directly into a collecting bottle. It was found that this method of cannulating the small intestine prevented any significant bleeding into the lumen, and when the tubes were in position the small bowel could be perfused without contamination from the stomach, gallbladder, or pancreas. The small intestine with the cannulae was returned to the peritoneal cavity and normal saline infused via a constant flow pump at a temperature of 37°C. Perfusions were performed at a rate of 250 ml per hour after an initial washout, and hourl...

Temperature and frequency characteristics of low-loss MnZn ferrite in a wide temperature range J. Appl. Phys. 109, 106103 (2011); 10.1063/1.3583551Frequency dispersion of complex permeability in Mn-Zn and Ni-Zn spinel ferrites and their composite materials Mn x Ni 0.5Ϫx Zn 0.5 Fe 2 O 4 ferrites with xϭ0.05, 0.1, 0.2, 0.3, and 0.4, have been synthesized by the citrate precursor method and investigated for their magnetic properties. The initial relative permeability is observed to increase with increase in manganese concentration up to xϭ0.2 followed by a decrease, the maximum value being 632. An initial increase followed by a subsequent decrease of saturation magnetization with increase in x is observed. Curie temperature is observed to decrease continuously from 488 to 418°C when x increases from 0.05 to 0.4. Frequency variation of complex initial permeability indicates that resonance peak due to domain wall oscillations is at a frequency above 13 MHz. Saturation magnetization is observed to increase by about 22% when the sintering temperature is increased from 1200 to 1400°C. Initial permeability and B -H loops are observed to increase and constrict, respectively, with increase in sintering temperature.