Lead-free ceramics of composition Bi(Mg₁/₂Ti₁/₂)O₃-(Bi₁/₂K₁/₂)TiO₃-(Bi₁/₂Na₁/₂)TiO₃ were prepared
using solid state synthesis techniques. The dielectric spectra showed a Tmax of more than 320 °C
for all compositions, and the transitions became increasingly diffuse as the Bi(Mg₁/₂Ti₁/₂)O₃
content increased. A lower temperature transition, indicating a transformation from an ergodic to a
non-ergodic...
The piezoelectric fatigue behavior of Pb-free ceramics based on solid solutions of Bi(Zn₀.₅Ti₀.₅)O₃-(Bi₀.5K₀.₅)TiO₃-(Bi₀.₅Na₀.₅)TiO₃ was characterized at 50 kV/cm after 10⁶ bipolar cycles. Ferroelectric compositions containing 2.5% Bi(Zn₀.₅Ti₀.₅)O₃ exhibited only minor losses in maximum strain (~10%). In compositions with 5% Bi(Zn₀.₅Ti₀.₅)O₃ that exhibit large electric field-induced strains, the electromechanical strain actually...
Polycrystalline ferroelectric lead-free 85 mol% (Bi₀.₅Na₀.₅)TiO₃–10 mol% (Bi₀.₅K₀.₅)TiO₃–5 mol% BaTiO₃ (85BNT–10BKT–5BT) thin films were fabricated via chemical solution deposition on platinized silicon substrates. The permittivity and dielectric loss at 1 kHz were 610 and ∼3.5%, respectively. The ferroelectric properties at room temperature and as a function of the temperature up...
Solid solutions ceramics of the Bi(Zn0.5Ti0.5)O-3-(Bi0.5K0.5)TiO3-(Bi0.5Na0.5)TiO3 ternary system for <20 mol. % BZT were created and confirmed to be single phase using x-ray diffraction. The dielectric dispersion showed decreasing T-max of the dielectric spectrum with a broadening of the transition with increasing BZT content. At 2.5BZT-40BKT-57.5BNT, a secondary transition commonly...
Lead-free Bi(Mg₁/₂Ti₁/₂)O₃-(Bi₁/₂K₁/₂)TiO₃-(Bi₁/₂Na₁/₂)TiO₃ (BMT-BKT-BNT) ceramics have
been shown to exhibit large electromechanical strains under high electric fields along with
negligible fatigue under strong electric fields. To investigate the role of point defects on the
fatigue characteristics, the composition 5BMT-40BKT-55BNT was doped to incorporate acceptor and
donor defects on the A and...
In order to develop dielectric ceramics with temperature-stable permittivity characteristics, perovskite BaTiO[subscript 3]-Bi(Zn[subscript 1/2]Ti[subscript 1/2])O-[subscript 3]-NaNbO[subscript 3] ceramic solid solutions were investigated with a particular focus on effects of BaTiO[subscript 3] and NaNbO[subscript 3] contents on the dielectric properties of ternary compounds. Keeping the ratios of the other two constituents...
The dielectric spectra of CaCu₃Ti₄O₁₂ is characterized by a large permittivity (εᵣ>10 000) with only a weak dependence on temperature over the temperature range 200–400 K. In this work, doping with 0.1–1.0 wt % ZrO₂ has been shown to dramatically reduce the dielectric loss. At 0.5 wt % ZrO₂, tan...
The crystal structure and multiferroic properties of single-phase (Bi₀.₉La₀.₁)FeO₃–Ba(Fe₀.₅Nb₀.₅)O₃ ceramics were investigated. The rhombohedral-type structure of 1.0(Bi₀.₉La₀.₁)FeO₃) was transformed to a monoclinic-type structure for the 0.5(Bi₀.₉La₀.₁)FeO₃–0.5Ba(Fe₀.₅Nb₀.₅)O₃) composition. It shows the coexistence of ferroelectricity and magnetism at room temperature, represented by a high dielectric constant with ferroelectric hysteresis and clear magnetic...
The defect mechanisms that underpin the high energy density dielectric 0.8BaTiO₃–0.2Bi(Zn₁/₂Ti₁/₂) O₃ were investigated. Characterization of the nominally stoichiometric composition revealed the presence of a Ti³⁺-related defect center, which is correlated with lower resistivities and an electrically heterogeneous microstructure. In compositions with 2 mol. % Ba-deficiency, a barium vacancy-oxygen vacancy...
Materials based on BiMO₃-modified BaTiO₃ have been shown to exhibit a number of attractive electrical and electromechanical properties. In addition, many of the materials in this broad family exhibit reduced sintering temperatures for densification as compared to pure BaTiO₃. We report here a study of the phase evolution and sintering...
A new composite system, Ba(Zr[subscript 0.07]Ti[subscript 0.93])O₃ (BZT93) ceramic/NiO nanoparticles, was fabricated to investigate the effect of NiO nanoparticles on the properties of these composites. M-H hysteresis loops showed an improvement in the magnetic behavior for higher NiO content samples plus modified ferroelectric properties. However, the 1 vol. % samples...
The need for miniaturization without compromising cost and performance continues to motivate research in advanced capacitor devices. In this report, multilayer ceramic capacitors based on relaxor BaTiO₃-Bi(Zn₁/₂Ti₁/₂)O₃ (BT-BZT) were fabricated and characterized. In bulk ceramic embodiments, BT-BZT has been shown to exhibit relative permittivities greater than 1000, high resistivities (ρ > 1...
The concept of sustainable resource management can be applied at multiple scales.
Monitoring is an essential component of sustainable natural resource management
schemes, and as we begin to confront the need to manage natural resources at the
global scale, the importance of monitoring at the global scale is also growing....
Real-time PCR assays using locked nucleic acid (LNA) probes and high resolution melt (HRM) analysis were developed for molecular differentiation of Pseudoperonospora cubensis and P. humuli, causal agents of cucurbit and hop downy mildew, respectively. The assays were based on a previously identified single nucleotide polymorphism (SNP) in the cytochrome...
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants generated as byproducts of natural and anthropogenic combustion processes. Despite significant public health concern, physiologically based pharmacokinetic (PBPK) modeling efforts for PAHs have so far been limited to naphthalene, plus simpler PK models for pyrene, nitropyrene, and benzo[a]pyrene (B[a]P). The dearth of...
Structure-property relationships in ferroelectrics extend over several length scales from the individual unit cell to the macroscopic device, and with dynamics spanning a broad temporal domain. Characterizing the multi-scale structural origin of electric field-induced polarization reversal and strain in ferroelectrics is an ongoing challenge that so far has obscured its...
Dibenzo[def,p]chrysene (DBC) is a transplacental carcinogen in mice (15 mg/kg; gestation day (GD) 17). To mimic residual exposure throughout pregnancy, dams received 4 smaller doses of DBC (3.75 mg/kg) on GD 5, 9, 13 and 17. This regimen alleviated the previously established carcinogenic responses in the thymus, lung, and liver....
RNA sequencing (RNA-seq) and genotyping-by-sequencing (GBS) were used for single nucleotide polymorphism (SNP) identification from two economically important obligate plant pathogens, Pseudoperonospora cubensis and P. humuli. Twenty isolates of P. cubensis and 19 isolates of P. humuli were genotyped using RNA-seq and GBS. Principle components analysis (PCA) of each data...
Dibenzo(def,p)chrysene (DBC), (also known as dibenzo[a,l]pyrene), is a high molecular weight polycyclic aromatic hydrocarbon (PAH) found in the environment, including food, produced by the incomplete combustion of hydrocarbons. DBC, classified by IARC as a 2A probable human carcinogen, has a relative potency factor (RPF) in animal cancer models 30-fold higher...
BaCuQF (Q=S,Se) materials, candidate transparent p-type conductors, were prepared by solid-state reaction, and their bulk electrical and optical properties were evaluated. The room-temperature Seebeck coefficient and electrical conductivity of undoped BaCuQF pellets were +56 μV/K and 0.088 S/cm, respectively, for the sulfide fluoride, and +32 μV/K and 0.061 S/cm, respectively,...
Native point defects, defect complexes, and oxygen impurities in BaCuChF were studied using density
functional theory calculations, self-consistent thermodynamic simulations, and various experimental techniques.
Unintentional p-type conductivity in BaCuChF is explained by the presence of copper vacancies with
transition levels in the valence band. These acceptor-like defects are partially compensated...
The polycyclic aromatic hydrocarbon (PAH), benzo[a]pyrene (BaP), was compared to dibenzo[def,p]chrysene (DBC) and combinations of three environmental PAH mixtures (coal tar, diesel particulate and cigarette smoke condensate) using a two stage, FVB/N mouse skin tumor model. DBC (4 nmol) was most potent, reaching 100% tumor incidence with a shorter latency...
Continental precipitation not routed to the oceans as runoff returns to the atmosphere as evapotranspiration. Partitioning this evapotranspiration flux into interception, transpiration, soil evaporation, and surface water evaporation is difficult using traditional hydrological methods yet critical for understanding the water cycle and linked ecological processes. We combined two large-scale flux-partitioning...
Seamounts are ubiquitous features of the seafloor that form part of the fabric of oceanic crust. When a seamount enters a subduction zone, it has a major affect on forearc morphology, the uplift history of the island arc, and the structure of the downgoing slab. It is not known, however,...
Crown profile equations were developed for stand-grown western hemlock (Tsuga heterophylla (Raf.) Sarg.) in northwest Oregon. The profile model uses a segmented approach, dividing the crown into an upper and lower portion at the point of the largest crown width (LCW). The model explains about 86% of the variation in...
In their recent Canadian Journal of Forest Research Comment 368 article, Wilson and Oliver (2000) developed an equation for predicting the average ratio of height to diameter at breast height for the largest 250 trees/ha (H/DL250) in unthinned stands as a function of initial density and dominant height of the...
Sustaining forest resources requires a better understanding of forest ecosystem processes, and how management decisions and climate change may affect these processes in the future. While plot and inventory data provide our most detailed information on forest carbon, energy, and water cycling, applying this understanding to broader spatial and temporal...
As the Galápagos hot spot is approached from the west along the Galápagos Spreading Center there are systematic increases in crustal thickness and in the K/Ti, Nb/Zr, ³He/⁴He, H₂O, and Na₂O content of lavas recovered from the spreading axis. These increases correlate with progressive transitions from rift valley to axial...
The Pacific lamprey (Entosphenus tridentatus) is in decline in the Columbia River Basin, and translocating adult lamprey to bypass difficult migration corridors has been implemented since 2000. We describe and report results from two current translocation programs, provide context for use of translocation, and discuss potential benefits, risks, and uncertainties....
Many wind-power facilities in the United States have established effective monitoring programs to determine turbine-caused fatality rates of birds and bats, but estimating the number of fatalities of rare species poses special difficulties. The loss of even small numbers of individuals may adversely affect fragile populations, but typically, few (if...
This work advances a unified approach to process-based hydrologic modeling to enable controlled and systematic evaluation of multiple model representations (hypotheses) of hydrologic processes and scaling behavior. Our approach, which we term the Structure for Unifying Multiple Modeling Alternatives (SUMMA), formulates a general set of conservation equations, providing the flexibility...
The relationships of the unusual salticid spider Depreissia from central Africa and Borneo have been difficult to resolve, obscured by its highly modified ant-like body. Phylogenetic analysis of the gene 28S strongly supports its placement outside the major clade Salticinae and within the clade of cocalodines, spartaeines and lapsiines, with...
Computer models are used to simulate the nonlinear formation of images of obscurations in laser beams. The predictions of the model are found to be in good agreement with measurements conducted in the nonlinear regime corresponding to a typical solid-state laser operation. In this regime, peak-to-mean fluence ratios large enough...
A near-large-eddy simulation approach with size-revolving (bin) microphysics is employed to evaluate the relative sensitivity of southeast Pacific marine boundary layer cloud properties to thermodynamic and aerosol parameters. Simulations are based on a heavily drizzling cloud system observed by the NOAA ship Ronald H. Brown during the Variability of the...
Wildlife crossing structures and accompanying barrier fencing can prevent large mammals from accessing road surfaces and can significantly reduce wildlife-vehicle collisions while allowing animals to move from one side of the road to the other. Little research has been conducted on the behavioral responses of wildlife when encountering these novel...
A depth-dependent boundary layer lapse rate was empirically deduced from 156 radiosondes released during six month-long research cruises to the southeast Pacific sampling a variety of stratocumulus conditions. The lapse-rate dependence on boundary layer height is weak, decreasing from a best fit of 7.6 to 7.2 K km⁻¹ as the...
The sustainability of the food system is at the forefront of academic and policy discussions as we face the challenge of providing food security to a growing population amidst environmental uncertainty and depletion, social disruptions, and structural economic shocks and stresses. Crafting a sustainable and resilient food system requires us...
Core-top benthic foraminifera (Cibicidoides wuellerstorfi) from a depth transect of Soutar box cores from the Ontong-Java Plateau (1.6 – 4.4 km) were analyzed for cadmium, barium, and strontium (Cd/Ca, Ba/Ca, and Sr/Ca) and for their stable isotopic composition (δ¹³C and δ¹⁸O). We also measure bottom water δ¹³C, Cd, and Ba...
Volcanic eruptions are important events in Earth’s cycle of magma generation and crustal construction. Over durations of hours to years, eruptions produce new deposits of lava and/or fragmentary ejecta, transfer heat and magmatic volatiles from Earth’s interior to the overlying air or seawater, and significantly modify the landscape and perturb...
Thoreau's experiment at Walden Pond reveals two potentially contradictory desires, one of which can be linked to agrarian reform, and the other to ecological knowledge. Thoreau conceived his Walden project in a cultural milieu in which agrarian reform was receiving incrasing attention, and the Walden experiments was, in important ways,...
Phylogenetic relationships of the Antiperyphanes Complex of the genus Bembidion are inferred using DNA
sequences from seven genes (two nuclear ribosomal, four nuclear protein coding, and one mitochondrial
protein coding). Redefined subgenera within the complex are each well-supported as monophyletic. Most
striking was the discovery that a small set of...
Black Brant (Branta bernicla nigricans) distribution was monitored and eelgrass beds (Zostera marina) were mapped during the spring migration of 1976. Brant used eelgrass areas significantly, and human disturbance and tide height were important factors influencing Brant distribution and activity.
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David J. Wetzel (current address unknown)
CITATION: Wetzel, D. J. 1996. Brant use of Yaquina Estuary
Continuous records of upper water column (0–150 m) temperature profiles, spectral distribution of downwelling irradiance, and phytoplankton solar-induced fluorescence at 25 m depth were obtained during the inaugural deployment of the Hawaii Air-sea Logging Experiment, A Long-term Oligotrophic Habitat Assessment (HALE ALOHA) mooring, near the Hawaii Ocean Time-series (HOT) Station...
We analyzed the sedimentological characteristics and magnetic properties of cores from the three basins of Clear Lake, California, USA, to assess the depositional response to a series of land use changes that occurred in the watershed over the 20th century. Results indicate that distinct and abrupt shifts in particle size,...
Density estimation for marine mammal species is performed primarily using
visual distance sampling or capture-recapture. Minke whales in Hawaiian waters
are very difficult to sight; however, they produce a distinctive “boing” call, making
them ideal candidates for passive acoustic density estimation. We used an array of
14 bottom-mounted hydrophones, distributed...
There is a great deal of evidence that altered sphingolipid metabolism is associated with fumonisin-induced
animal diseases including increased apoptotic and oncotic necrosis, and carcinogenesis in
rodent liver and kidney. The biochemical consequences of fumonisin disruption of sphingolipid
metabolism most likely to alter cell regulation are increased free sphingoid bases...
Tides in the Delaware Bay (USA) have been modeled from 7000 years before present (7 ka) to the present day and for selected future sea-level rise scenarios (100 years, 300 years). Historic bathymetries were constructed through use of glacial isostatic adjustment models and a very high spatial resolution (< 100...
Acoustic methods are frequently used to monitor endangered marine mammal species. Advantages of acoustic methods over visual ones include the ability to detect submerged animals, to work at night, and to work in any weather conditions. A relatively inexpensive and easy-to-use acoustic float, the QUEphone, was developed by converting a...
Humpback whales produce a wide range of low-to mid-frequency vocalizations throughout their migratory range. Non-song "calls" dominate this species' vocal repertoire while on high-latitude foraging grounds. The source levels of 426 humpback whale calls in four vocal classes were estimated using a four-element planar array deployed in Glacier Bay National...