Electrical properties of BaTiO3 based ferroelectric capacitors grown on oxide sacrificial layers for micro-cantilevers applications

An investigation of all oxides ferroelectric capacitors based on $SrRuO_3/BaTiO_3/SrRuO_3$ multi-layers grown on sacrificial oxide layers of $YBa_2Cu_3O_7$\ud and MgO for Micro-Electo-Mechanical systems applications is reported. By insertion of additional MgO or $SrTiO_3$ buffer layers the orientation of the $BaTiO_3$ film can be controlled allowing the fabrication of suspended cantilevers using the 31 and the 33 piezoelectric modes. The electrical properties of $SrRuO_3/BaTiO_3/SrRuO_3$ capacitors are changed compared with those grown directly on a single crystal substrate by the introduction of sacrificial layers. Circuit modeling of the electrical characteristics of these devices shows that a reduction of the deposition pressure for $BaTiO_3$ produces a decrease of the parasitic shunting conductance (modeled with a resistor in parallel to the capacitance of the device) which reduces the resistive loss present in the $BaTiO_3$ film. However for extremely low deposition pressure the quality of the polarization hysteresis loops is compromised.\ud Particulates present on the surface of the $YBa_2Cu_3O_7$increases the parasitic conductance at low frequency in the capacitive structure grown on this sacrificial layer. Good electrical properties are obtained for the capacitive structures grown on top of the MgO sacrificial layers at pressures equal or lower than 8 Pa.\u

SOUTHERNMOST OCCURRENCE OF THE SUWANNEE COOTER, PSEUDEMYS CONCINNA SUWANNIENSIS (TESTUDINES: EMYDIDAE)

The Suwannee Cooter, Pseudemys concinna suwanniensis, the largest member of the speciose turtle family Emydidae, inhabits a small number of rivers that drain into the northeastern Gulf of Mexico along the northwest coast of Florida from just west of Tallahassee to just south of Tampa. The status of this state-protected subspecies in the southernmost of these rivers, the Alafia, is unknown and hence of conservation concern. We provide recent evidence confirming that a reproducing population still exists in this river, and review available specimens and both published and unpublished records documenting the southern limit of distribution. At least within the eastern United States, our observations also extend confirmed knowledge of the geographic occurrence of hatchling turtles overwintering in the nest southward by 285 km

Examples and Comments Related to Relativity Controversies

Recently Mansuripur has called into question the validity of the Lorentz force in connection with relativistic electromagnetic theory. Here we present some very simple point-charge systems treated through order v^{2}/c^{2} in order to clarify some aspects of relativistic controversies both old and new. In connection with the examples, we confirm the validity of the relativistic conservation laws. The relativistic examples make clear that external forces may produce a vanishing torque in one inertial frame and yet produce a non-zero torque in another inertial frame, and that the conservation of angular momentum will hold in both frames. We also discuss a relativistic point-charge model for a magnetic moment and comment on the interaction of a point charge and a magnetic moment. Mansuripur's claims of incompatibiltiy between the Lorentz force and relativity are seen to be invalid.Comment: 23 page

Scaling Symmetries of Scatterers of Classical Zero-Point Radiation

Classical radiation equilibrium (the blackbody problem) is investigated by the use of an analogy. Scaling symmetries are noted for systems of classical charged particles moving in circular orbits in central potentials V(r)=-k/r^n when the particles are held in uniform circular motion against radiative collapse by a circularly polarized incident plane wave. Only in the case of a Coulomb potential n=1 with fixed charge e is there a unique scale-invariant spectrum of radiation versus frequency (analogous to zero-point radiation) obtained from the stable scattering arrangement. These results suggest that non-electromagnetic potentials are not appropriate for discussions of classical radiation equilibrium.Comment: 13 page

In vitro susceptibility of thioredoxins and glutathione to redox modification and aging-related changes in skeletal muscle

AbstractThioredoxins (Trx's) regulate redox signaling and are localized to various cellular compartments. Specific redox-regulated pathways for adaptation of skeletal muscle to contractions are attenuated during aging, but little is known about the roles of Trx's in regulating these pathways. This study investigated the susceptibility of Trx1 and Trx2 in skeletal muscle to oxidation and reduction in vitro and the effects of aging and contractions on Trx1, Trx2, and thioredoxin reductase (TrxR) 1 and 2 contents and nuclear and cytosolic Trx1 and mitochondrial Trx2 redox potentials in vivo. The proportions of cytosolic and nuclear Trx1 and mitochondrial Trx2 in the oxidized or reduced forms were analyzed using redox Western blotting. In myotubes, the mean redox potentials were nuclear Trx1, −251mV; cytosolic Trx1, −242mV; mitochondrial Trx2, −346mV, data supporting the occurrence of differing redox potentials between cell compartments. Exogenous treatment of myoblasts and myotubes with hydrogen peroxide or dithiothreitol modified glutathione redox status and nuclear and cytosolic Trx1, but mitochondrial Trx2 was unchanged. Tibialis anterior muscles from young and old mice were exposed to isometric muscle contractions in vivo. Aging increased muscle contents of Trx1, Trx2, and TrxR2, but neither aging nor endogenous ROS generated during contractions modified Trx redox potentials, although oxidation of glutathione and other thiols occurred. We conclude that glutathione redox couples in skeletal muscle are more susceptible to oxidation than Trx and that Trx proteins are upregulated during aging, but do not appear to modulate redox-regulated adaptations to contractions that fail during aging

DISTRIBUTION AND STATUS OF THE SUWANNEE COOTER, PSEUDEMYS CONCINNA SUWANNIENSIS, IN THE ALAFIA RIVER (HILLSBOROUGH COUNTY, FLORIDA, USA)

The Suwannee Cooter, Pseudemys concinna suwanniensis, is a geographically limited turtle of conservation concern that inhabits Florida rivers draining into the northeastern Gulf of Mexico. Threats impacting its conservation status include take for human consumption, predation of turtles and nests, loss or degradation of nesting and basking habitat, water quality degradation, and boat strikes. Our surveys revealed that the Alafia River, which drains into Hillsborough Bay (northeastern Tampa Bay), is likely the stronghold of the southern distribution of P. c. suwanniensis. Multiple survey methods during 2015-2020 revealed that a substantial population of Suwannee Cooters inhabits much of this blackwater river system, including the main channel and at least one of its two primary tributaries. GIS analysis showed that more than half of the shoreline within the occupied extent is currently protected by conservation lands, although additional protection of private lands and improved habitat management protocols are needed to assure the population’s conservation

Field testing an acoustic lighthouse : Combined acoustic and visual cues provide a multimodal solution that reduces avian collision risk with tall human-made structures

Billions of birds fatally collide with human-made structures each year. These mortalities have consequences for population viability and conservation of endangered species. This source of human-wildlife conflict also places constraints on various industries. Furthermore, with continued increases in urbanization, the incidence of collisions continues to increase. Efforts to reduce collisions have largely focused on making structures more visible to birds through visual stimuli but have shown limited success. We investigated the efficacy of a multimodal combination of acoustic signals with visual cues to reduce avian collisions with tall structures in open airspace. Previous work has demonstrated that a combination of acoustic and visual cues can decrease collision risk of birds in captive flight trials. Extending to field tests, we predicted that novel acoustic signals would combine with the visual cues of tall communication towers to reduce collision risk for birds. We broadcast two audible frequency ranges (4 to 6 and 6 to 8 kHz) in front of tall communication towers at locations in the Atlantic migratory flyway of Virginia during annual migration and observed birds’ flight trajectories around the towers. We recorded an overall 12–16% lower rate of general bird activity surrounding towers during sound treatment conditions, compared with control (no broadcast sound) conditions. Furthermore, in 145 tracked “at-risk” flights, birds reduced flight velocity and deflected flight trajectories to a greater extent when exposed to the acoustic stimuli near the towers. In particular, the 4 to 6 kHz stimulus produced the greater effect sizes, with birds altering flight direction earlier in their trajectories and at larger distances from the towers, perhaps indicating that frequency range is more clearly audible to flying birds. This “acoustic lighthouse” concept reduces the risk of collision for birds in the field and could be applied to reduce collision risk associated with many human-made structures, such as wind turbines and tall buildings

Giant magnetoresistance in granular cobalt copper thin films prepared by pulsed laser ablation deposition

Giant magnetoresistance of up to 9.5% in 1.5 T at 14 K has been observed in Co19Cu81, thin films prepared by pulsed laser ablation deposition from rotated, split targets. The as-grown films show a small GMR effect but this may be enhanced by a factor of 4 by appropriate annealing. The volume ratio of material in the target is found to be reproduced in the film. Measurements of the remanence and initial susceptibility of the films indicate a distribution of energy barriers to the rotation of the magnetic moments of the cobalt particles and also the presence of inter-particle interactions. The choice of operating parameters to control these effects and thus optimise the GMR is discussed

Hydrogeology and Hydrochemistry of the Falls City Uranium Mine Tailings Remedial Action Project, Karnes County, Texas

Oxidized uranium ore deposits were discovered in the Deweesville sandstone (also referred to as the Stones Switch; Bunker and MacKallor [1973]) in the Falls City region in the 1950s. Uranium was mined and milled in the small community of Deweesville by Susquehanna-Western, Inc. (SWI) from April 1961 to August 1973. Tailings composed of sediment residue from the sulfuric acid milling process and residual sulfuric acid solutions were disposed of in six ponds on the outcrop of the Deweesville, within the mined-out uranium pits in the Deweesville, and on the outcrop of the Conquista, creating a set of large tailings impoundments (figs. 1.1 and 1.2). From 1978 to 1982 Solution Engineering, Inc. (SEI) conducted a secondary recovery of the remaining uranium in the tailings piles by in situ leaching. In 1984, the ponds on top of two of the tailings piles were spray evaporated and a clay cap was placed over the piles to prevent additional percolation of water through the piles and into the underlying aquifers. Acidic tailings solutions have been recharging the underlying aquifers since initial tailings disposal and may still be leaking into these aquifers. Several hydrogeologic investigations have been conducted to assess whether there has been groundwater contamination from the tailings. Early studies were conducted by Turk, Kehle and Associates (1976), and Ford, Bacon & Davis Utah (1978, 1981). Each of these studies included only minor investigations of the hydrogeology and hydrochemistry of the site and, in general, underestimated the extent of contamination from the site. Investigations conducted by the U.S. Department of Energy (DOE) from 1985 to 1991 have since revealed the true extent of contamination (U.S. Department of Energy, 1991).Bureau of Economic Geolog