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Aberration corrected scanning transmission electron microscopy (STEM) and electron diffraction have been used to disclose local structure and nano-chemistry in a Ca modified BaTiO3-Bi(Mg0.5Ti0.5)O3 relaxor dielectric ceramic which exhibits high and near-invariant relative permittivity over a wide temperature range. High resolution, synchrotron X-ray diffraction indicated a globally cubic structure (Pm3m), but direct atomic-scale imaging by STEM revealed local tetragonal distortions. Nanopolar clusters were identified from B-site atomic displacement vectors measured relative to oxygen ion positions along < 100 > and < 110 > zone axes of integrated differential phase contrast (iDPC) STEM images, highlighting cluster sizes of 2–5 nm. Chemical analysis by STEM-energy dispersive X-ray spectroscopy and full pattern refinements of X-ray powder diffraction data each implied high levels of Bi vacancies within the matrix. The possibility that these A-site vacancies modulate the nanopolar structure and promote flattening of the permittivity-temperature response in this class of dielectric is discussed.

The substitution of Re into Bi2O3 allows stabilization of the δ-Bi2O3 structure by additional substitution of any lanthanide ion to give, for example, phases of composition Bi12.5La1.5ReO24.5. Some of these phases have been found to show exceptionally high oxide ion conductivity at low temperatures, ca 10-3 S cm-1 at 300 °C. The phases show a significant structural difference from other δ-Bi2O3 phases previously reported, with interstitial anion sites displaced further from the ideal fluorite position, (1/4,1/4,1/4).

The dielectric properties of dense ceramics of (6H)Ba(Ti0.90Mn0.10)O3 are reported. Single-phase powders were obtained by the mixed oxide route at 1250 degC and ceramics (~ 87% of the theoretical X-ray density) by sintering in air and flowing O2 at 1400 degC. The hexagonal phase was detected by angle XRD analysis. The lattice parameter was calculated from the XRD data. The phase purity of the powders and ceramics was determined using the index scheme for undoped 6H-BaTiO3, reported in the ICDD file number 82-1175 as space group P63/mmc with lattice parameters of a = 5.72380(70) Aring, c = 13.96490(70) Aring, V = 396.2 Aring3 and refinement data of XRD for BaTi0.90Mn0.10O3. After calcining at 1250 degC it had lattice parameters of a = 5.7235(6) Aring, c = 13.9771(15) Aring and V = 396.53 Aring3, showing very little difference in lattice parameters from the reported values. BaTi0.90Mn0.10O3 ceramics, after sintering at 1400 degC for 4 hours in air and flowing oxygen, showed lattice parameters of a = 5.7277(4) Aring, c = 13.9750(17) Aring, V = 396.73 Aring3 and a = 5.7176(6) Aring, c = 13.9607(5) Aring, V = 395.25 Aring3, respectively. SEM micrograph of the ceramics microstructure revealed the presence of open porosity with an average grain size between 1 and 3 mum. The conductivity through the grain and grain boundary was analyzed using impedance analysis. The impedance response of the ceramics showed single parallel RC elements with total resistance of 8.124 times 105 Omegacm at 384 degC, capacitance of ~4.79 pFcm-1 and permittivity of ~40-50, quality factor, Q times fr ~ 13,000-19,000 GHz at ~6.3GHz. The bulk resistivity and ceramics microstructure influence the loss in the microwave frequency range.

It is argued that the key to increasing the deployment of fiber in the local loop has long been the economics of fiber versus copper. One major contributor of cost to the network is the requirement for power for the optical network unit (ONU), which will decline as the power needed for the ONU electronics is reduced by improved designs and by system suppliers. The history of loop powering is reviewed, and several innovations that will reduce the initial cost and long-term total system cost, including service and upgrade of loop systems, are described. It is shown that improvements in battery life expectancy will provide greater reliability of POTS service. >

Many DC power systems installed around the world today utilize low voltage disconnects as the primary means of protecting batteries from being over discharged and becoming damaged through such phenomenon as cell voltage reversal. There are two different arrangements that are utilized extensively, one being to isolate the battery string(s) from the DC power system and the other to disconnect the electronic loads. This paper is designed to discuss the use of each of these topologies and the issues that need to be understood by a systems engineer before making his selection.

The substitution of Re into Bi2O3 allows stabilization of the delta-Bi2O3 structure by additional substitution of any lanthanide ion to give, for example, phases of composition Bi12.5La1.5ReO24.5. Some of these phases have been found to show exceptionally high oxide ion conductivity at low temperatures, ca 10-3 S cm-1 at 300 degrees C. The phases show a significant structural difference from other delta-Bi2O3 phases previously reported, with interstitial anion sites displaced further from the ideal fluorite position, (1/4,1/4,1/4).

Pain is one of the symptoms which most quickly drive the patient to consult a doctor, and its relief is a major aim of treatment, whether by drugs, by operation, or by physiotherapy. It is therefore of immense importance to investigate the mechanisms which cause the patient to experience the sensation of pain, and it is a reproach to modern medicine that We still know so little of such a fundamental matter. The study of pain is a meeting place of many fields of inquiry; the biochemist may interest himself in the nature of the painful stimulus, the physiologist in the character of the nervous impulses which lead to the sensation of pain. The pharmacologist may study the events which occur in local or general anaesthesia, and the clinician can observe in his patients the varieties and anomalies of painful experience. But perhaps the most basic type of research on pain is done by the anatomist, whose object is to investigate the structure and disposition of the nerve-endings, nerve fibres and nervous pathways involved in the events which result in the patient feeling pain.