Lowering the Number of False Positive Responses to Electric Pulp Tests by Qualifying Patient Response

The electric pulp test (EPT) has been shown to be a valuable tool in assessing pulp vitality. One of its drawbacks, however, is its high number of false positives. The purpose of this study was to determine if qualifying the type of sensation elicited by the test could lower the percentage of false positive responses. A retrospective chart review of an eleven-month period was conducted, examining all patients with necrotic teeth tested with the EPT. Of 189 teeth, when the patient responded to EPT at first sensation 23.3% of teeth were incorrectly identified as vital. When the patient was asked to respond only if they felt an uncomfortable sensation, the false positive rate was lowered to 8.5%, a statistically significant difference. No association was found between the teeth reclassified as necrotic and age, gender, type of tooth, or number of canals

Precise control of phase transformation process in lead zirconate titanate thin films by focused line-beam scanning

Phase transformation and grain growth processes of lead zirconate titanate (PZT) thin films have been precisely controlled by using focused line-beam scanning. The authors promoted the lateral crystallization of PZT grains by controlling a nucleation process and increasing the size of single grains to be as large as 40 μm in length. Focused line-beam scanning allows for the selective growth and crystallization of large PZT grains on predetermined nucleation sites. The high growth rate of the selected PZT grains was attributed to successive suppression of undesirable nucleation except at predetermined positions when pretreated PZT films were exposed to the focused line beam. © 2007 American Institute of Physics

Reliable current changes with selectivity ratio above 10(9) observed in lightly doped zinc oxide films

Low-power operation of semiconductor devices is crucial for energy conservation. In particular, energy-efficient devices are essential in portable electronic devices to allow for extended use with a limited power supply. However, unnecessary currents always exist in semiconductor devices, even when the device is in its off state. To solve this problem, it is necessary to use switch devices that can turn active devices on and off effectively. For this purpose, high on/off current selectivity with ultra-low off-current and high on-current is required. Here, we report a novel switch behavior with over 10(9) selectivity, a high on-current density of 1 MA cm(-2), an ultra-low off-current density of 1 mA cm(-2), excellent thermal stability up to 250 degrees C and abrupt turn-on with 5 mV per decade in solution-processed silver-doped zinc oxide thin films. The selection behavior is attributed to light doping of silver ions in zinc oxide films during electrochemical deposition to generate atomic-scale narrow conduction paths, which can be formed and ruptured at low voltages. Device simulation showed that the new selector devices may be used in ultra-high-density memory devices to provide excellent operation margins and extremely low power consumption.1110Ysciescopu

Hybrid Organic-Inorganic Perovskite Memory with Long-Term Stability in Air

11142Ysciescopu

Effect of halide-mixing on the switching behaviors of organic-inorganic hybrid perovskite memory

Mixed halide perovskite materials are actively researched for solar cells with high efficiency. Their hysteresis which originates from the movement of defects make perovskite a candidate for resistive switching memory devices. We demonstrate the resistive switching device based on mixed-halide organic-inorganic hybrid perovskite CH3NH3PbI3−xBrx (x = 0, 1, 2, 3). Solvent engineering is used to deposit the homogeneous CH3NH3PbI3−xBrx layer on the indium-tin oxide-coated glass substrates. The memory device based on CH3NH3PbI3−xBrx exhibits write endurance and long retention, which indicate reproducible and reliable memory properties. According to the increase in Br contents in CH3NH3PbI3−xBrx the set electric field required to make the device from low resistance state to high resistance state decreases. This result is in accord with the theoretical calculation of migration barriers, that is the barrier to ionic migration in perovskites is found to be lower for Br− (0.23 eV) than for I− (0.29–0.30 eV). The resistive switching may be the result of halide vacancy defects and formation of conductive filaments under electric field in the mixed perovskite layer. It is observed that enhancement in operating voltage can be achieved by controlling the halide contents in the film.1119Ysciescopu

Structural change in polar nanoregion in alkali niobate added Pb(Zn <inf>1/3</inf>Nb <inf>2/3</inf>) <inf>0.95</inf>Ti <inf>0.05</inf>O <inf>3</inf> single crystal and its effect on ferroelectric properties

Pb(Zn 1/3Nb 2/3) 0.95Ti 0.05O 3 (PZNT) single crystals with 5 mol.% alkali niobate such as LiNbO 3 (LN), NaNbO 3 (NN), and KNbO 3 (KN) were fabricated by using a flux method to investigate the effect of A-site cation radius on the structure and ferroelectric properties of PZNT under electric field (E-field). Their structure and properties showed different electric field dependence. Polarization versus electric field and strain versus electric field curves of PZNT-0.05LN showed E-field induced phase transition from a relaxor state to a normal ferroelectric state. However, only relaxor behavior was observed in PZNT-0.05NN and PZNT-0.05KN. The effect of A-site ion doping is attributed to the change in local lattice distortion and polar nano-region. When smaller cation such as Li ion substitutes Pb ion, the off-center displacement of Nb ion stabilizes rhombohedral lattice distortion. They, in turn, facilitate the development of macro-domains under electric field (E-field) in PZNT-0.05LN. In contrast, the substitution of Pb with larger cations such as Ni and K decreases the rhombohedral distortion of PZNT, which leads to the disappearance of unique E-field induced phase transition from rhombohedral to tetragonal phase in PZNT. Therefore, non-linear electrostrictive behavior of relaxor ferroelectrics is found in PZNT-0.05NN and PZNT-0.05KN. © 2012 American Institute of Physics

Fabrication and electrical characteristics of high-performance ZnO nanorod field-effect transistors

We report on fabrication and electrical characteristics of high-mobility field-effect transistors (FETs) using ZnO nanorods. For FET fabrications, single-crystal ZnO nanorods were prepared using catalyst-free metalorganic vapor phase epitaxy. Although typical ZnO nanorod FETs exhibited good electrical characteristics, with a transconductance of similar to140 nS and a mobility of 75 cm(2)/V s, the device characteristics were significantly improved by coating a polyimide thin layer on the nanorod surface, exhibiting a large turn-ON/OFF ratio of 10(4)-10(5), a high transconductance of 1.9 muS, and high electron mobility above 1000 cm(2)/V s. The role of the polymer coating in the enhancement of the devices is also discussed. (C) 2004 American Institute of Physics.X11333sciescopu

The effect of alkali niobate addition on the phase stability and dielectric properties of Pb (Zn13 Nb23) O3 based ceramic

While Pb (Zn13 Nb23) O3 -PbTi O3 (PZN-PT) single crystals have shown superior ferroelectric properties, less scientific and technical interests have been placed on PZN-PT polycrystalline ceramics due to their poor thermodynamic stability and the difficult processing conditions. Here, we stabilized the PZN-PT based ceramics by adding alkali niobates such as NaNb O3 (NN) and KNb O3 (KN) and investigated their structure and dielectric properties. Two stabilization mechanisms are suggested in alkali niobate added PZN-PT ceramics, increased tolerance factor and enhanced electronegativity difference. KN stabilized the perovskite structure of PZN-PT based ceramics more effectively than NN. Both PZN-PT-KN and PZN-PT-NN ceramics showed the typical behavior of relaxor ferroelectrics. The temperature of maximum dielectric constant of PZN-PT-NN was slightly higher than that of the PZN-PT-KN, which was explained by the difference in ionic size and B -site ordering. © 2007 American Institute of Physics

Integration scheme of nanoscale resistive switching memory using bottom-up processes at room temperature for high-density memory applications

A facile and versatile scheme is demonstrated to fabricate nanoscale resistive switching memory devices that exhibit reliable bipolar switching behavior. A solution process is used to synthesize the copper oxide layer into 250-nm via-holes that had been patterned in Si wafers. Direct bottom-up filling of copper oxide can facilitate fabrication of nanoscale memory devices without using vacuum deposition and etching processes. In addition, all materials and processes are CMOS compatible, and especially, the devices can be fabricated at room temperature. Nanoscale memory devices synthesized on wafers having 250-nm via-holes showed reproducible resistive switching programmable memory characteristics with reasonable endurance and data retention properties. This integration strategy provides a solution to overcome the scaling limit of current memory device fabrication methods.1165Ysciescopu

Bacterial Infection Elicits Heat Shock Protein 72 Release from Pleural Mesothelial Cells

Heat shock protein 70 (HSP70) has been implicated in infection-related processes and has been found in body fluids during infection. This study aimed to determine whether pleural mesothelial cells release HSP70 in response to bacterial infection in vitro and in mouse models of serosal infection. In addition, the in vitro cytokine effects of the HSP70 isoform, Hsp72, on mesothelial cells were examined. Further, Hsp72 was measured in human pleural effusions and levels compared between non-infectious and infectious patients to determine the diagnostic accuracy of pleural fluid Hsp72 compared to traditional pleural fluid parameters. We showed that mesothelial release of Hsp72 was significantly raised when cells were treated with live and heat-killed Streptococcus pneumoniae. In mice, intraperitoneal injection of S. pneumoniae stimulated a 2-fold increase in Hsp72 levels in peritoneal lavage (p<0.01). Extracellular Hsp72 did not induce or inhibit mediator release from cultured mesothelial cells. Hsp72 levels were significantly higher in effusions of infectious origin compared to non-infectious effusions (p<0.05). The data establish that pleural mesothelial cells can release Hsp72 in response to bacterial infection and levels are raised in infectious pleural effusions. The biological role of HSP70 in pleural infection warrants exploration