bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical Performance of Calcium doped Lanthanum Ferrite for use in Single-Step Co-fired Solid Oxide Fuel Cells (SOFCs)
Authors: Zink Peter A. , Yoon Kyung Joong , Pal Uday B. , Gopalan Srikanth
Published: February 2009

In the single-step SOFC co-firing process YSZ electrolytes with sintering aid densify at a temperature of ˜1300°C. Electrodes employed in the single-step co-fired SOFC must therefore sinter with the right microstructure at ˜1300°C. Calcium-doped lanthanum ferrite, La0.8Ca0.2FeO3±δ (LCF-20) was identified in earlier studies as a possible stable cathode material for the single-step co-fired SOFC. LCF-20 is also expected to be a more stable cathode material than LSCF (strontium and cobalt doped lanthanum ferrite).
Four-probe conductivity tests yielded ˜93 S/cm at 800°C and showed an increase in conductivity as pO2 increases, characteristic of p-type conduction. LCF has a higher electrical conductivity compared to LSCF and LCM+YSZ cathode materials. Oxygen ion conductivity of LCF-20 obtained from permeability measurements is higher than that of YSZ and LSF-20. Therefore LCF has excellent mixed conducting properties to serve as a catalytically active cathode material for co-fired solid oxide fuel cells operating at intermediate temperatures.
Electrochemical Impedance Spectroscopy (EIS) measurements were made on symmetrical cells fabricated with YSZ electrolyte and the electrode materials. A gadolium doped ceria (GDC) barrier layer was employed to prevent LCF/YSZ reaction. Comparison of LCF/GDC/YSZ/GDC/LCF EIS data to LCM+YSZ/YSZ/LCM+YSZ EIS data gathered using identical test conditions and electrode microstructures shows that LCF has a measured polarization resistance (Rp) of approximately half that seen in LCM+YSZ. Variations in cathode thickness and porosity show the best performance with a cathode of a critical thickness and finer porosity.
Slight stoichiometric deviations in LCF result in the formation of a Ca-Fe-O liquid phase during electrode sintering at around 1220 C. The liquid phase migrates into and through the GDC layer. EDX line scans show the second phase to be rich in Ca and Fe. Thicker GDC layers seem to prevent the liquid phase from reaching the electrolyte/GDC interface. Structural analysis with TEM will be performed.
The properties and the effect of the Ca-Fe-O phase on the cathodic performance of the cell are being investigated; however, preliminary results indicate that minor amounts of the Ca-Fe-O phase will not interfere with the electrochemical performance of the LCF cathode. The high temperature instability in LCF has been observed in other studies, but has not been studied specifically in the literature.
Experimental Studies and Thermodynamic Simulations of Phase Transformations in Ti-(41-45)Al-4Nb-1Mo-0.1B Alloys
Authors: Clemens Helmut , Boeck Barbara , Wallgram Wilfried , Schmoelzer Thomas , Droessler Laura M. , Zickler Gerald A. , Leitner Harald , Otto Andreas
Published: February 2009

TNM™ alloys are novel γ-TiAl based alloys which exhibit a high concentration of β-stabilizing elements such as Nb and Mo. Due to the high volume fraction of disordered β-phase these alloys can be hot-die forged under near conventional conditions. In this study, solid-state phase transformations and phase transition temperatures in Ti-(41-45)Al-4Nb-1Mo-0.1B (in at%) alloys were analyzed experimentally and compared to thermodynamic calculations. Results from scanning electron microscopy, conventional and high-energy X-ray diffraction as well as differential scanning calorimetry were used for the characterization of the prevailing phases and phase transformations. For the prediction of phase stabilities and phase transition temperatures thermodynamic calculations were conducted. ThermoCalc® was applied using a commercially available TiAl database. Combining all results a stable as well as a metastable phase diagram for Ti-(41-45)Al-4Nb-1Mo-0.1B alloys is proposed.
Microscale Fracture Toughness Testing of TiAl PST Crystals
Authors: Miyaguchi Daisuke , Otsu Masaaki , Takashima Kazuki , Takeyama Masao
Published: February 2009

A microscale fracture testing technique has been applied to examine the fracture properties of lamellar in TiAl PST crystals. Micro-sized cantilever specimens with a size ˜ 10×20×50 μm3 were prepared from Ti-48Al two-phase single crystals (PST) lamellar by focused ion beam (FIB) machining. Notches with a width of 0.5 μm and a depth of 5 μm were also introduced into the specimens by FIB. Two types of notch directions (interlamellar and translamellar) were selected when introducing the notches. Fracture tests were successfully completed using a mechanical testing machine for micro-sized specimens at room temperature. The fracture toughness (KQ) values of the interlamellar type specimens were obtained in the range 1.5–3.6 MPam1/2, while those of the translamellar specimens were 5.0–8.1 MPam1/2. These fracture toughness values are lower than those having been previously reported in conventional TiAl PST samples. For macro-sized specimens, extrinsic toughening mechanisms, including shear ligament bridging, act in the crack wake, and the crack growth resistance increases rapidly with increasing length of crack wake for lamellar structured TiAl alloys. In contrast, the crack length in microsized specimens is only 2–3 μm. This indicates that extrinsic toughening mechanisms are not activated in micro-sized specimens. This also indicates that intrinsic fracture toughness can be evaluated using microscale fracture toughness testing.
Microstructures and Mechanical Properties of Co3(Al,W) with the L12 Structure
Authors: Oohashi Takashi , Okamoto Norihiko L. , Kishida Kyosuke , Tanaka Katsushi , Inui Haruyuki
Published: February 2009

Since the ternary intermetallic compound Co3(Al,W) with the L12 structure was discovered, two-phase Co-base alloys composed of the γ-Co solid-solution phase and the γ'-Co3(Al,W) phase as a strengthening phase have been investigated as promising high-temperature materials. Some Co-base alloys have been reported to exhibit high-temperature strength greater than those of conventional Ni-base superalloys. Although the excellent high-temperature physical properties of the Co-based alloys are considered to result from the phase stability and strength of Co3(Al,W), the pristine physical properties of Co3(Al,W) have not been fully understood, supposedly due to the difficulties in obtaining single-phase Co3(Al,W). In the present study, we examine the effect of heat treatment on the microstructure of alloys with compositions close to single-phase Co3(Al,W) as well as their mechanical properties, e.g. elastic modulus, thermal expansion, etc., in hope of deriving the pristine properties of the Co3(Al,W) phase. A single crystal with the composition of Co-10Al-11W grown by floating-zone melting exhibits a thermal expansion coefficient of 10×10-6 K-1 at room temperature, which is virtually identical to those of the commercial Ni-base superalloys. However, it increases with increasing temperature followed by a discontinuity at around 1000°C, inferring the phase transformation from γ' to γ. The investigated thermal expansion behavior indicates that the lattice mismatch between the γ' and γ phases is reversed from positive at room temperature to negative at high temperatures above around 500°C. The results of elastic property measurement and environmental embrittlement investigation of polycrystalline Co3(Al,W) will also be presented.
Plastic Deformation Behavior of Ti5Si3 Single Crystals
Authors: Kishida Kyosuke , Fujiwara Masakazu , Okamoto Norihiko L. , Tanaka Katsushi , Inui Haruyuki
Published: February 2009

Deformation behavior of binary stoichiometric Ti5Si3 single crystals was examined as a function of the loading axis orientation and temperature. Two different types of deformation modes, namely {1100}[0001] prism slip, {2112}1/3<2113> pyramidal slip were newly identified to be activated above 1300 °C depending on the loading axis orientation. Critical resolved shear stresses (CRSS) for the {1100}[0001] prism slip and {2112}1/3<2113> pyramidal slip were estimated to be about 130 MPa and 330 MPa at 1400 °C, respectively. The values of the CRSS for these two slip systems decrease monotonously with increasing the temperature.
Magnetostrictive Fe-Ga Wires with <100> Fiber Texture
Authors: Farrell Shannon Patrick , Quigley Patti E. , Avery Kyle J. , Hatchard Tim D. , Flynn Stephanie E , Dunlap Richard A.
Published: February 2009

Recently, low-cost processing approaches that produce textured thin bodies have engendered interest as cost-effective approaches for fabrication of magnetostrictive Fe-Ga alloys. In particular, wire-forming methods that strictly control the solidification direction could lead to some measure of crystallographic texture control. This is critical for development of large magnetostriction in polycrystals and for use of the alloys in actuators, sensors, energy harvesters and other systems. Magnetostrictive Fe-Ga wires have been prepared using an innovative cost-effective approach – based on the Taylor wire method – that combines rapid solidification and deformation processes. The procedure for making magnetostrictive wires is discussed and the wires are evaluated in terms of microstructure, crystallographic texture and magnetostriction. Results show that the Taylor-based approach is an effective and versatile means to draw 1-3 mm diameter textured Fe-Ga wire. Experimentation on the influence of drawing technique and quench conditions on texture development resulted with production of a strong <100> fiber texture in the Fe-Ga wire. Magnetostriction measurements, in the absence of prestress, indicated a maximum magnetostriction of ˜165 ppm in a saturation field of less than 200 mTesla. This is considered a significant strain for bulk polycrystalline Fe-Ga alloys without a pre-stress or a stress-annealing treatment. The unique properties of wires made with the Taylor-based approach coupled with the low intrinsic cost make this an attractive approach for production of textured magnetostrictive wire for a variety of applications.
Magnetoelastic Material as a Biosensor for the Detection of Salmonella Typhimurium
Authors: Lakshmanan Ramji S , Guntupalli Rajesh , Huang S. , Johnson M. L. , Mathison Leslie C , Chen I-Husan , Petrenko V. A. , Cheng Zhong-Yang , Chin B. A.
Published: February 2009

ABSTRACT
Magnetoelastic materials are amorphous, ferromagnetic alloys that usually include a combination of iron, nickel, molybdenum and boron. Magnetoelastic biosensors are mass sensitive devices comprised of a magnetoelastic material that serves as the transducer and bacteriophage as the bio-recognition element. By applying a time varying magnetic field, the magnetoelastic sensor thin films can be made to oscillate, with the fundamental resonant frequency of oscillations depends on the physical dimensions and properties of the material. The change in the resonance frequency of these mass based sensors can be used to evaluate the amount of analyte attached on the sensor surface. Filamentous bacteriophage specific to S. typhimurium was used as a bio-recognition element in order to ensure specific and selective binding of bacteria onto the sensor surface. The sensitivity of magnetoelastic materials is known to be dependent on the physical dimensions of the material. An increase in sensitivity from 159Hz/decade for a 2mm sensor to 770Hz/decade for a 1mm sensor and 1100Hz/decade for a 500micron sensor was observed. The sensors were characterized by scanning electron microscopy (SEM) analysis assayed biosensors to provide visual verification of frequency responses and an insight into the characteristics of the distribution of phage on the sensor surface. The magnetoelastic sensors immobilized with filamentous phage are suitable for specific and selective detection of target analyte in different media. Certain modifications to the measurement circuit resulted in better signal to noise ratios for sensors with smaller dimensions (L<1mm). This was achieved by tuning the circuit resonance close to that of the sensor. According to models and preliminary tests, this method was anticipated in about a 5 times increase in signals for a 200×40×6microns. This technique and further studies into the design and modification of the measurement circuits could yield better, sensitive responses for sensors with smaller dimensions. The magnetoelastic materials offer further advantages of potential miniaturization, contact-less nature and ease of operation.
Bending Behavior of Polymer Films in Strongly Interacting Solvents
Authors: Zhang Jianxia , Wiley John
Published: February 2009

Several polymers show bending behavior on exposure to selected solvent systems. Either on emersion or evaporation of particular solvents, films can bend or curl within seconds. The response depends on the interaction between polymer chains and solvent molecules as well as the film geometry and surrounding temperature.
Optical Detection of Polyacrylamide Swelling Behavior in a Porous Silicon Sensor
Authors: Bonanno Lisa M. , DeLouise Lisa A.
Published: February 2009

This work proves that a 1-D porous silicon (PSi) sensor is capable of monitoring the optical changes in a polyacrylamide (PAAm) hydrogel that correlate with swelling capacity. The PSi device was impregnated with PAAm hydrogel with varying crosslinking density and total solids. The optical response of the PSi sensor was utilized to distinguish the changes in refractive index of hydrogels with varying cross-linking densities. Refractive index values calculated by the composite hydrogel-PSi sensor response agree well (≤1% difference) with values measured using a bench-top refractometer. This work serves to build a foundation for creating a composite biochemical-responsive hydrogel-PSi sensor in which competitive binding of a target analyte would cause a reduction in hydrogel cross-linking density. Long-term goals of this work are to exploit the volume sensitivity of a PSi sensor and leverage the added optical response of the responsive hydrogel to increase target detection sensitivity in an affinity based biosensor.
Label-free Optical Detection of Molecular Interactions by Molecular Interferometric Imaging
Authors: Zhao Ming , Wang Xuefeng , Nolte David. D.
Published: February 2009

Molecular interferometric imaging (MI2) is a label-free optical biosensor that combines common-path interferometry with shot-noise limited characteristics of a CCD array detector to detect protein binding to surfaces. In the metrology limit, it has achieved roughness-limited surface height resolution of 15 pm per 0.4 micron pixel, corresponding to a scaling mass sensitivity of 7 fg/mm, and a molecular resolution of about 15 IgG molecules per pixel. We have applied MI2 to detect cytokine interleukin-5 at a concentration detection limit of 50 pg/mL with a sandwich immunoassay. Real-time binding assays with MI2 enable the study of reaction kinetics, with a scaling mass sensitivity of 2 pg/mm under 7x magnification. Real-time MI2 measurements of anti-rabbit IgG against rabbit IgG were compared with results from surface plasmon resonance, with identical association rate constants at 5x103 M-1sec-1.
Elastic Aerogels and Xerogels Synthesized from Methyltrimethoxysilane (MTMS)
Authors: Kanamori Kazuyoshi , Nakanishi Kazuki , Hanada Teiichi
Published: February 2009

Transparent organic-inorganic hybrid aerogels and aerogel-like xerogels have been prepared from methyltrimethoxysilane (MTMS) respectively by supercritical drying (SCD) and ambient pressure drying (APD). The new aerogels and xerogels significantly deform without collapsing on uniaxial compression and almost fully relax when unloaded. This elastic behavior, termed as “gspring-back”, allows APD without noticeable shrinkage and cracking. The flexible network composed of lower cross-linking density (up to three bonds per every silicon atom) compared to silica gels (up to four bonds) and repulsion between hydrophobic methyl groups bonded to every silicon atom largely contributes to the pronounced deformability and relaxing, respectively. Lower surface silanol group density also plays a crucial role for the “gspring-back” behavior.
Crystalinity Properties of Carbon Nanotube-Polyvinylidene Fluoride Composites
Authors: Shan Xiaobing , Wu Pei-xuan , Zhang Lin , Cheng Zhong-Yang
Published: February 2009

Single-wall and multi-wall carbon nanotube blends (0 to 0.5 vol% ) with polyvinylidene fluoride (PVDF) have been prepared using solution cast method and characterized. By acid treatment, it has been observed that nanotube has been well functionalized and uniformly dispersed into the polymer. X-ray diffraction analysis coupled with differential scanning calorimetry (DSC) has revealed that carbon nanotube alters the crystallinity of PVDF and thereby enhances the β-phase in PVDF. Experimental results have demonstrated that enhancement of β-phase is a function of carbon nanotube concentration.
Effect of Process Variables on Glass Frit Wafer Bonding in MEMS Wafer Level Packaging
Authors: Sridharan Sid , Henry Jim , Maloney John , Gardner Bob , Mason Keith , Dragoi Viorel , Burggraf Jurgen , Pabo Eric , Cakmak Erkan
Published: February 2009

Among different MEMS wafer level bonding processes glass frit bonding provides reliable vacuum tight seals in volume production. The quality of the seal is a function of both seal glass materials and the processing parameters used in glass frit bonding. Therefore, in this study Taguchi L18 screening Design of Experiment (DOE) was used to study the effect of materials and process variables on the quality of the glass seal in 6” silicon wafers bonded in EVG520IS bonder. Six bonding process variables at three levels and two types of sealing glass pastes were considered. The seals were characterized by Scanning Acoustic Microscopy (SAM), cross sectional Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX). The results were quantified into four responses for DOE analysis. Key results are a) peak temperature has the strongest influence on seal properties, b) hot melt paste has significantly lower defects compared to liquid paste, and c) peak firing temperatures can be as low as 400°C under certain conditions.
Using New Porous Nanocomposites for Photocatalytic Water Decontamination
Authors: Chaleshtori Maryam Zarei , Masud S. M. Sarif , Saupe Geoffrey B.
Published: February 2009

Heterogeneous catalysts that accelerate the photolytic destruction of organic contaminants in water are a potentially inexpensive and highly effective way to remove both trace-level and saturated harmful compounds from industrial waste streams and drinking water. Porous photocatalytic materials can have the combined qualities of high surface area and relatively large particle sizes, as compared with nanoparticulate catalyst powders like titanium dioxide . The larger particle sizes of the porous materials facilitate catalyst removal from a solution, after purification has taken place.

We have synthesized new kinds of photocatalytic porous oxide materials that can be used to purify contaminated water by accelerating the photodegradation of any kind of organic pollutant. The new materials have very large open pore structures that facilitate the diffusion, the surface contact of contaminants, and solvent flow through the catalyst. These qualities enhance surface reactions important to the process. The new catalysts have shown robust physical and chemical properties that make them candidates for real applications in polluted water decontamination.
Noncentrosymmetry in Mixed Metal Oxide-Fluorides, Can We Control It?
Authors: Pinlac Rachelle Ann F. , Marvel Michael R. , Lesage Julien J.-M. , Poeppelmeier Kenneth R.
Published: February 2009

The rational design of crystal structures, in particular noncentrosymmetric materials, and how to differentiate polar, polar-chiral, and chiral structures, is an ongoing theme in crystal engineering. In KNaNbOF5, the combination of a second-order Jahn Teller active d0 transition metal oxyfluoride anionic unit and mixed K/Na cation coordination environments are shown to result in a polar structure (space group Pna21). The crystal structure analysis of the Na/K-O/F interactions reveals that the potassium cations form one of the two contacts to the under-bonded oxide ions. These interactions satisfy the expected bond valence sums and Pauling's second crystal rule (PSCR), leading to O/F ordering and acentric packing of the [NbOF5]2− anionic unit.
Porosity through reduction in metal oxides
Authors: Shoemaker Daniel P , Corr Serena Ann , Seshadri Ram
Published: February 2009

Routes to porous materials with nanoscale dimensions have been investigated. In the first example presented, porous manganese oxide has been prepared by leaching Ni metal from a nickel-manganese oxide precursor via reduction. Electron microscopy studies have revealed the presence of Ni nanoparticles on the surface, and also embedded within the porous MnO matrix. Magnetic measurements have shown exchange bias between the ferromagnetic Ni nanoparticles and the antiferromagnetic MnO phase. In the second system studied, porous nanostructures of rutile VO2 and corundum V2O3 have been prepared by reduction of amine-templated V2O5−δ nanoscrolls. The porosity of these materials has been probed by electron microscopy, N2 sorption measurements and thermogravimetric analysis.
Highly Transparent, Tough and Dimensionally Stable Polymer Nanocomposite
Authors: Kai Yasuaki , Morohoshi Katsumi , Muramatsu Hironobu , Unno Haruo , Oda Takashi , Itou Tomohiro , Fujita Naoko , Kawa Manabu
Published: February 2009

This report describes a novel polymer nanocomposite that shows high transparency, toughness and dimension stability at the same time. Polymer nanocomposites are attracting industrial interest for a wide range of application. One advantage of polymer nanocomposites is the possibility to obtain visually transparent polymer materials owing to nano-size particles that are smaller than visible wavelengths. Transparent polymer nanocomposites are suitable for light, clear, tough and dimensionally stable applications such as the windows and sunroofs of vehicles or houses and other buildings. However, most of the research on transparent polymer nanocomposites has remained at the stage of showing their potential or future expectations because of the complexity of various nanoparticle-polymer matrix combinations. One of the most difficult challenges for the fabrication of transparent nanocomposites is to keep the dispersion of particles in the polymer uniform at the nano-level until the final composite is obtained. Some successful examples have been reported with polyacrylate-based polymer nanocomposites. For example, silica/PMMA nanocomposites show good transparency even with a high filler content. In fact, most of their transparency depends on refractive index matching. While a nanocomposite may appear transparent to the human eye, TEM observation shows that there are many aggregations inside, preventing the material from ever becoming tough and making it extremely brittle. Some other cases are based on a tough polymer like polycarbonate, but with a very restrained filler content of only several weight percent. Because of such a small amount of filler, dimensional stability cannot be improved. Thus, there have been no reports of highly transparent, tough and dimensionally stable polymer nanocomposites with a filler content of more than 10wt%. We overcame this contradictory challenge and succeeded in dispersing more than 15wt% of filler into polycarbonate. We chose needle-shaped alumina boehmite nanoparticles as the filler, and employed an appropriate amount of organic acid as a surface modifier to aid in uniform particle dispersion in the polymer matrix. Polycarbonate is well-known as a tough polymer, but its main chain easily hydrolyses, either in the presence of an acid or base. The hydrolysis reaction makes the polymer chain shorter, leading rapidly to a brittle composite. We carefully defined the surface modification condition to avoid this hydrolysis reaction. This completely novel composite shows excellent properties without any trade-off, including high transparency (Haze<1%), toughness (Izod>60 J/m) and dimensional stability (CLTE<40 ppm) at the same time.
In-Plane Texturing of Buffer Layers by Alternating Beam Assisted Deposition: Large Area and Small Area Applications
Authors: Usoskin Alexander , Kirchhoff Lutz
Published: February 2009

In standard ion beam assisted deposition (IBAD), the growing film is exposed to inclined ion etching in order to achieve a preferable in-plane orientation of the crystalline structure. Recently, we suggested exposing the film periodically to deposition pulses and to etching pulses, i.e. to assisted beam pulses. As a long sequence of alternations of these two pulses is needed, we named this method “alternating beam assisted deposition” (ABAD). In real application, the substrates exposed to the molecular/atomic flow originating from the sputter source acquire a few nanometer thick layer of yttria-stabilized zirconia (YSZ). In the next step, this layer undergoes ion etching with an Ar ion beam emitted from the source with a particle energy between 200 and 300 eV. Simultaneously with ion-beam exposition, an additional electron beam provides neutralizing of the electrical change in the substrate plane. The ion beam guided 55° at a 55° angle of incidence provides selective etching of the YSZ layer, leading finally after numerous deposition-etching cycles to a sufficiently high quality of in-plane texture in the YSZ layer with the best FWHM values of 8°-9°.
Bone Regeneration Using B-Tricalcium Phosphate in a Calcium Sulfate Matrix
Authors: Podaropoulos Leonidas , Veis Alexander A. , Papadimitriou Serafim , Alexandridis Constantinos , Kalyvas Demos
Published: February 2009

The aim of the study was the histomorphometric comparison of the osteogenic potential of β-tricalcium phosphate (β-TCP) alone or in a calcium sulfate matrix. Three round defects, 10 mm (diameter) × 5 mm (depth), were created on each iliac crest of 4 dogs. The defects were divided into 3 groups. Ten defects were filled with β-TCP in a calcium sulfate (CS) matrix (Fortoss Vital; group A), 10 defects were filled with β-TCP alone (Fortoss Resorb; group B), and 4 defects were left ungrafted to heal spontaneously (group C). All defects were left to heal for 4 months without the use of a barrier membrane. Histologic evaluation and morphometric analysis of undecalcified slides was performed using the areas of regenerated bone and graft remnants. All sites exhibited uneventful healing. In group A sites (β-TCP/CS), complete bone formation was observed in all specimens, graft granules dominated the area, and a thin bridge of cortical bone was covering the defect. Group B (β-TCP) defects were partially filled with new bone, the graft particles still dominated the area, while the outer cortex was not restored. In the ungrafted sites (group C), incomplete new bone formation was observed. The outer dense cortical layer was restored in a lower level, near the base of the defect. The statistical analysis revealed that the mean percentage of new bone regeneration in group A was higher than in group B (49.38% and 40.31%, respectively). A statistically significant difference existed between the 2 groups. The beta-TCP/CS group exhibited significantly higher new bone regeneration according to a marginal probability value (P = .004 < .05). The use of β-TCP in a CS matrix produced significantly more vital new bone fill and preserved bone dimensions compared with the use of β-TCP alone.
Hierarchical drivers of reef‐fish metacommunity structure
Authors: MacNeil M. Aaron , Graham Nicholas A. J. , Polunin Nicholas V. C. , Kulbicki Michel , Galzin René , Harmelin-Vivien Mireille , Rushton Steven P.
Published: February 2009

Coral reefs are highly complex ecological systems, where multiple processes interact across scales in space and time to create assemblages of exceptionally high biodiversity. Despite the increasing frequency of hierarchically structured sampling programs used in coral‐reef science, little progress has been made in quantifying the relative importance of processes operating across multiple scales. The vast majority of reef studies are conducted, or at least analyzed, at a single spatial scale, ignoring the implicitly hierarchical structure of the overall system in favor of small‐scale experiments or large‐scale observations. Here we demonstrate how α (mean local number of species), β diversity (degree of species dissimilarity among local sites), and γ diversity (overall species richness) vary with spatial scale, and using a hierarchical, information‐theoretic approach, we evaluate the relative importance of site‐, reef‐, and atoll‐level processes driving the fish metacommunity structure among 10 atolls in French Polynesia. Process‐based models, representing well‐established hypotheses about drivers of reef‐fish community structure, were assembled into a candidate set of 12 hierarchical linear models. Variation in fish abundance, biomass, and species richness were unevenly distributed among transect, reef, and atoll levels, establishing the relative contribution of variation at these spatial scales to the structure of the metacommunity. Reef‐fish biomass, species richness, and the abundance of most functional‐groups corresponded primarily with transect‐level habitat diversity and atoll‐lagoon size, whereas detritivore and grazer abundances were largely correlated with potential covariates of larval dispersal. Our findings show that (1) within‐transect and among‐atoll factors primarily drive the relationship between α and γ diversity in this reef‐fish metacommunity; (2) habitat is the primary correlate with reef‐fish metacommunity structure at multiple spatial scales; and (3) inter‐atoll connectedness was poorly correlated with the nonrandom clustering of reef‐fish species. These results demonstrate the importance of modeling hierarchical data and processes in understanding reef‐fish metacommunity structure.
Multiscale control of flooding and riparian‐forest composition in Lower Michigan, USA
Authors: Baker Matthew E. , Wiley Michael J.
Published: February 2009

Despite general agreement that river‐valley hydrology shapes riparian ecosystems, relevant processes are difficult to distinguish and often inadequately specified in riparian studies. We hypothesize that physical constraints imposed by broad‐scale watershed characteristics and river valleys modify local site conditions in a predictable and probabilistic fashion. To test this hypothesis, we employ a series of structural equations that decompose occurrence of riparian ecotypes into regional temperature, catchment storm response, valley hydraulics, and local site wetness via a priori specification of factor structure and ask (1) Is there evidence for multiscale hydrologic control of riparian diversity across Lower Michigan? (2) Do representations of key constraints on flood dynamics distinguish regional patterns of riparian vegetation? (3) How important are these effects? Cross‐correlation among geospatial predictors initially obscured much of the variation revealed through analysis of semipartial variance. Causal relationships implied by our model fit with observed variation in riparian conditions (chi‐square P = 0.43) and accounted for between 84% and 99% of the occurrence probability of five riparian ecotypes at 94 locations. Results suggest strong variation in the effects of regional climate, and both the relative importance and spatial scale of hydrologic factors influencing riparian vegetation through explicit quantification of relative flood frequency, duration, intensity, and relative overall inundation. Although climate and hydrology are not the only determinants of riparian conditions, interactions of hydrologic sourcing and flood dynamics described by our spatial models drive a significant portion of the variation in riparian ecosystem character throughout Lower Michigan, USA.
Temperature oscillation coupled with fungal community shifts can modulate warming effects on litter decomposition
Authors: Dang Christian K. , Schindler Markus , Chauvet Eric , Gessner Mark O.
Published: February 2009

Diel temperature oscillations are a nearly ubiquitous phenomenon, with amplitudes predicted to change along with mean temperatures under global‐warming scenarios. Impact assessments of global warming have largely disregarded diel temperature oscillations, even though key processes in ecosystems, such as decomposition, may be affected. We tested the effect of a 5°C temperature increase with and without diel oscillations on litter decomposition by fungal communities in stream microcosms. Five temperature regimes with identical thermal sums (degree days) were applied: constant 3° and 8°C; diel temperature oscillations of 5°C around each mean; and oscillations of 9°C around 8°C. Temperature oscillations around 8°C (warming scenario), but not 3°C (ambient scenario), accelerated decomposition by 18% (5°C oscillations) and 31% (9°C oscillations), respectively, compared to the constant temperature regime at 8°C. Community structure was not affected by oscillating temperatures, although the rise in mean temperature from 3° to 8°C consistently shifted the relative abundance of species. A simple model using temperature–growth responses of the dominant fungal decomposers accurately described the experimentally observed pattern, indicating that the effect of temperature oscillations on decomposition in our warming scenario was caused by strong curvilinear responses of species to warming at low temperature, particularly of the species becoming most abundant at 8°C (Tetracladium marchalianum). These findings underscore the need to consider species‐specific temperature characteristics in concert with changes in communities when assessing consequences of global warming on ecosystem processes.
Beyond description: the active and effective way to infer processes from spatial patterns
Authors: McIntire Eliot J. B. , Fajardo Alex
Published: February 2009

The ecological processes that create spatial patterns have been examined by direct measurement and through measurement of patterns resulting from experimental manipulations. But in many situations, creating experiments and direct measurement of spatial processes can be difficult or impossible. Here, we identify and define a rapidly emerging alternative approach, which we formalize as “space as a surrogate” for unmeasured processes, that is used to maximize inference about ecological processes through the analysis of spatial patterns or spatial residuals alone. This approach requires three elements to be successful: a priori hypotheses, ecological theory and/or knowledge, and precise spatial analysis. We offer new insights into a long‐standing debate about process–pattern links in ecology and highlight six recent studies that have successfully examined spatial patterns to understand a diverse array of processes: competition in forest‐stand dynamics, dispersal of freshwater fish, movement of American marten, invasion mechanisms of exotic trees, dynamics of natural disturbances, and tropical‐plant diversity. Key benefits of using space as a surrogate can be found where experimental manipulation or direct measurements are difficult or expensive to obtain or not possible. We note that, even where experiments can be performed, this procedure may aid in measuring the in situ importance of the processes uncovered through experiments.
A derivative approach to endangered species conservation
Authors: Mandel James T , Donlan C Josh , Armstrong Jonathan
Published: February 2009

Two major shortcomings of the US Endangered Species Act have led to inefficient use of conservation dollars: (1) it only provides conservation protection to distressed or rapidly declining species, and (2) it does not take full advantage of the market to reduce costs in conservation. New, derivative‐based insurance products (financial instruments designed to allow the commoditization and sale of risk) have been developed that allow investors to insure risk in exchange for fixed payments. Modifications to these financial derivatives, which are used to distribute risk and stabilize forecasts across many corporate and social scenarios, could allow purchasers to take preventative action to simultaneously protect their investment and decrease the likelihood of the insured event. We propose that governments issue modified derivative contracts to sell species' extinction risk to market investors and stakeholders. Using the endangered red‐cockaded woodpecker (Picoides borealis) in the US as an example, we show how a biodiversity derivatives program could proactively generate new funding, result in more cost‐effective conservation, align stakeholders' interests, and create incentives for private conservation efforts.
Simultaneous positive and negative density‐dependent dispersal in a colonial bird species
Authors: Kim Sin-Yeon , Torres Roxana , Drummond Hugh
Published: February 2009

Contradictory patterns of density‐dependent animal dispersal can potentially be reconciled by integrating the conspecific attraction hypothesis with the traditional competition hypothesis. We propose a hypothesis that predicts a U‐shaped relationship between density and both natal and breeding dispersal distance. Using 10 years of observations on a breeding colony of the Blue‐footed Booby (Sula nebouxii), the hypothesis was confirmed by documenting simultaneous positive and negative density‐dependent dispersal distances in natal and breeding dispersal of males and breeding dispersal of females within the colony. Point‐pattern analyses demonstrated that the breeding sites of Blue‐footed Boobies were highly aggregated in all years within a large study area, and aggregation presumably resulted in heterogeneity in patch density throughout the colony. As predicted, at moderate to high densities, dispersal distances showed positive density dependence, with individuals moving to lower density patches. In contrast, at low to moderate densities, dispersal distances showed negative density dependence, with individuals moving to higher density patches. In both sexes of the 1994 cohort, the higher the mean density in patches used by an individual over the long term (up to age 11 years), the fewer fledglings it produced. A positive effect of density on long‐term reproductive success was not detected, possibly because birds that failed during pair formation or incubation were not sampled. Density of conspecifics may be an important influence on habitat selection of breeders, and dispersal may tend to carry individuals to patches where pair formation opportunities are better and negative effects of competition on reproductive success are reduced.
Behavioral adjustments of African herbivores to predation risk by lions: Spatiotemporal variations influence habitat use
Authors: Valeix M. , Loveridge A. J. , Chamaillé-Jammes S. , Davidson Z. , Murindagomo F. , Fritz H. , Macdonald D. W.
Published: February 2009

Predators may influence their prey populations not only through direct lethal effects, but also through indirect behavioral changes. Here, we combined spatiotemporal fine‐scale data from GPS radio collars on lions with habitat use information on 11 African herbivores in Hwange National Park (Zimbabwe) to test whether the risk of predation by lions influenced the distribution of herbivores in the landscape. Effects of long‐term risk of predation (likelihood of lion presence calculated over four months) and short‐term risk of predation (actual presence of lions in the vicinity in the preceding 24 hours) were contrasted. The long‐term risk of predation by lions appeared to influence the distributions of all browsers across the landscape, but not of grazers. This result strongly suggests that browsers and grazers, which face different ecological constraints, are influenced at different spatial and temporal scales in the variation of the risk of predation by lions. The results also show that all herbivores tend to use more open habitats preferentially when lions are in their vicinity, probably an effective anti‐predator behavior against such an ambush predator. Behaviorally induced effects of lions may therefore contribute significantly to structuring African herbivore communities, and hence possibly their effects on savanna ecosystems.
Speciation and endemism under the model of island biogeography
Authors: Chen Xiao-Yong , He Fangliang
Published: February 2009

Speciation has been considered as a primary process contributing to species diversity, but its contribution to the diversity of local communities has not been fully appreciated. Based on the theory of classic island biogeography, we derived a model for the number of endemic species as a function of the processes of immigration, speciation, and extinction. The model shows that species endemism on an island is proportional to speciation rate but decreases with the sum of immigration and extinction rates (i.e., the species turnover rate). The model predicts that the contribution of immigration to species richness in local communities decreases with time, while the contribution of speciation to local richness increases with time. It further shows that only when the speciation rate is larger than half of the extinction rate can new species added from speciation eventually surpass those added from immigration. We conclude that, although the model leads to an apparent positive relationship between percentage endemism and species diversity on an island, this positive endemics–diversity relationship is not necessarily driven by speciation.
Time of Day and Length of Antidepressant Drug Administration Influence Brain-Derived Neurotrophic Factor and TrkB Levels in Rat Brain
Authors: E. Kozisek Megan , M. Qutna Nidal , B. Bylund David
Published: February 2009

The expression of brain-derived neurotrophic factor (BDNF) mRNA and protein and its primary receptor, TrkB
mRNA shows circadian oscillations in adult rats; however it has been unclear if juvenile rats also display a similar pattern
in circadian oscillations. We determined the levels of BDNF and TrkB mRNA and of BDNF protein at four separate time
points during a 24 hperiod in the hippocampus and frontal cortex. The expression of BDNF and TrkB undergoes diurnal
oscillation in adult and postnatal day 21 rats, but no significant variation is present in postnatal day 13 rats. Antidepressant
drug treatment also is known to influence BDNF and TrkB levels. However, the reported effects of antidepressant drug
treatment on BDNF and TrkB are highly variable and may be influenced by multiple factors, including detection method,
class of antidepressant drug, and length of administration. BDNF mRNA levels were decreased significantly in the hippocampus
after acute desipramine (a tricyclic antidepressant) treatment compared to control. BDNF mRNA and protein levels,
as well as TrkB mRNA levels, were unchanged in adult rats after subchronic and chronic treatment with either desipramine
or escitalopram (a selective serotonin reuptake inhibitor) and treatment consistent with several reports in the literature.
This study defines several important factors that must be taken into account when comparing BDNF and TrkB
levels both within and among studies.
Sources of Rationalized Governance: Cross-National Longitudinal Analyses, 1985–2002
Authors: Drori Gili S. , Yong Jang Suk , Meyer John W.
Published: February 2009

We assess the factors affecting national administrative rationalization in the context of the current worldwide movement for governance reforms, focusing on national linkages to world society rather than internal socioeconomic development. We conduct cross-national longitudinal analyses of a multiple-indicator measure of rationalized governance for the period 1985–2002. Overall, there is only a very modest growth in the measure worldwide, with the most substantial changes occurring in developing countries. Change is mostly on an indicator of investment openness. National change tends to reflect links with global society: expanded trade, the penetration of science, and embeddedness in world organizations play prominent roles. The rationalization of national governance, like other dimensions of modernization, is not simply or principally a consequence of endogenous national development or social complexity. Rather, it directly reflects trade and institutional linkages with wider rationalizing movements in the context of a neoliberal world society.
Positioning among Organizations in a Population: Moves between Market Segments and the Evolution of Industry Structure
Authors: Dobrev Stanislav D. , Kim Tai-Young
Published: February 2009

We develop a framework for defining the boundaries of within-population market segments, differentiated based on type and level of resources. Using this framework, we propose a theory of the moves between market segments of all firms in an organizational population across its evolution. Focusing on commensalistic interdependence within a segment, we adapt density dependence theory to predict that processes of mutualism and competition operate concurrently, even across high counts of density, and affect firms' propensity to desert their segment. Analyses of moves between market segments by firms in the U.S. auto industry between 1895 and 1981 confirm our predictions and suggest the operation of a basic ecological process that shapes the evolution of population structure.
Use of an Enzymatic Process for Extracting and Hydrolyzing Rice Proteins Aiming at Phenylalanine Removal
Authors: Silvestre Marialice P. C. , Vieira Claudia R , Silva Mauro R , Silva Maitê C , Lopes Carlos O , Silva Viviane D. M.
Published: February 2009

The free use of rice in the phenylketonurics diet needs the reduction of phenylalanine (Phe) content from its proteins. This procedure involves protein extraction and hydrolysis followed by Phe removal. Enzymatic processes were then used for extracting and hydrolyzing rice proteins. In the former, a protease from Bacillus licheniformis was used while for the second case, six different enzymes were tested (pancreatin, papain, proteases from Aspergillus sojae, Bacillus stearothermophilus and two from Bacillus subtilis). Also, the activated carbon (AC) was employed as the adsorptive medium for removing Phe. The efficiency of Phe removal was evaluated by second derivative spectrophotometry. The hydrolysate prepared with papain showed the highest Phe removal (94.1%), using an E:S ratio of 4:100, a protein:AC ratio of 1:88 and three different meshes of AC simultaneously.
Regulating Modesty-Related Practices
Authors: Harel Alon
Published: February 2009

This Paper explores the justifications for regulating modesty-related practices in liberal societies and uses two examples of modesty-related practices the practice of wearing the hijab and the practice of separating men and women in busesin order to demonstrate that modesty-related practices often rest on different rationales. Some of these rationales are oppressive and discriminatory while other are benign or even autonomy-enhancing. The multiplicity of meanings associated with modesty-related practices is a challenge to the policy maker. The Paper proposes that sometimes it is possible to transform the social meaning of modesty-related practices without transforming the practices themselves.