bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement of Photoelectrochemical Reaction for Hydrogen Generation from Water using N-face GaN
Authors: Fujii Katsushi , Sato Keiichi , Kato Takashi , Minegishi Tsutomu , Yao Takafumi
Published: March 2010

Photoelectrochemical properties of Ga- and N-face GaN grown by hydride vapor phase epitaxy (HVPE) were investigated. The properties were also compared with Ga-face GaN grown by metal-organic vapor phase epitaxy (MOVPE). The flatband potentials were in order of Ga-face GaN grown by MOVPE < N-face GaN < Ga-face GaN. The highest photocurrent density at zero bias was obtained from the N-face GaN. The photocurrent density was over 3 times larger than that of Ga-face GaN.
Electron Emission from Diamond (111) p+-i-n+ Junction Diode
Authors: Takeuchi Daisuke , Makino Toshiharu , Kato Hiromitsu , Ogura Masahiko , Tokuda Norio , Oyama Kazuhiro , Matsumoto Tsubasa , Hirabayashi Izumi , Okushi Hideyo , Yamasaki Satoshi
Published: March 2010

We successfully observed electron emission from hydrogenated diamond (111) p+-i-n+ junction diodes. Here, p+- and n+-layers mean that the boron and phosphorous impurity concentrations in these layers are around 1020 cm-3. Then the p+-layer on top of the diode suppresses electron emission from the top-surface area. The heavily doped layers also play an important role to obtain high diode and emission currents. The emission started when the applying bias voltage was equal to the built-in potential, and the emission current reached to over 1 μA at room temperature operation. With taking into account our previous photoemission yield spectroscopy results and with the very high binding energy of free excitons of 80 meV in diamond, we suggested that the electron emission was derived from free excitons generated in the i-layer of the diodes.
Comparison Between Chemical and Plasmatic Treatment of Seeding Layer for Patterned Diamond Growth
Authors: Kromka Alexander , Babchenko Oleg , Rezek Bohuslav , Hruska Karel , Purkrt Adam , Remes Zdenek
Published: March 2010

We employ UV photolithographic and electron beam lithographic patterning of diamond seeding layer on SiO2/Si substrates for the selective growth of micrometer and sub-micrometer diamond patterns. Using bottom-up strategy, thin diamond channels (470 nm in width) are directly grown. Differences between wet chemical and plasma treatment on the patterned diamond growth are studied. We find that the density of parasitic diamond crystals (outside predefined patterns) is lowered for gas mixture CF4/O2 plasma than for rich O2 plasma. After CF4/O2 plasma treatment, the density of parasitic crystals is 106 cm-2 which is comparable to the wet chemical treatment. Introducing sandwich-like structure, i.e. photoresist-seeding layer-photoresist, and its treatment (lift-off and CF4/O2 plasma) further reduces the density of parasitic crystals down to 105 cm-2. The advantage of this novel treatment is short processing time, simplicity, and minimal damage of the substrate surface.
Growth of Carbon Nanotubes on Copper Substrates Using a Nickel Thin Film Catalyst
Authors: Atthipalli Gowtam , Kumta Prashant , Wang Wei , Epur Rigved , Jampani Prashanth H , Allen Brett L. , Tang Yifan , Star Alexander , Gray Jennifer
Published: March 2010

Carbon nanotubes with their attractive properties, one-dimensional character, and their large aspect ratio are ideal candidates for a variety of applications including energy storage, sensing, nanoelectronics, among others. We have studied the growth of carbon nanotubes on copper substrates using a nickel thin film as a catalyst. The catalyst was sputtered in a chamber having a base pressure in the ultra-high-vacuum regime. By adjusting the sputtering parameters, the effects of the morphology and the thickness of the nickel catalyst on the growth of carbon nanotubes have also been investigated. Multiple hydrocarbon sources as carbon feedstock (methane, acetylene and xylene) and corresponding catalyst precursors and varying temperature conditions were used during the Chemical Vapor Deposition (CVD) process to understand and best determine the ideal conditions for carbon nanotube growth on copper. Correlation between the thickness of the thin film nickel catalyst and the carbon nanotube diameter is also presented in the study. Characterization techniques used to study the morphology of the CNTs grown on copper include SEM, TEM and HRTEM, Raman Spectroscopy
Carbon Onion Films-Molecular Interactions of Multi-Layer Fullerenes
Authors: Alduhaileb Raed A. , Ayres Virginia M. , Jacobs Benjamin W. , Fan Xudong , McElroy Kaylee , Crimp Martin , Hirata Atsushi , Horikoshi Mutsumi
Published: March 2010

The evolution of carbon onion structure from spherical to polyhedral is correlated with changes in the sp3/sp2 ratio as a function of increasing synthesis temperature using electron energy loss spectroscopy, scanning electron microscopy, and high resolution electron microscopy. Results that are obtained using asymmetric f-variance versus symmetric Gaussian deconvolution of electron energy loss spectra are compared. The possibility of a separate peak at 287 eV is discussed.
Photoelectrochemical Properties of Carbon Nanotube/SnO2 Nanostructures Prepared by Three Different Methods
Authors: Muchharla Baleeswaraiah , Dong Lifeng
Published: March 2010

In this work, we employed three different methods to fabricate solar cell structures on indium tin oxide (ITO) substrates. For the first method, multi-layered structures were prepared by using single walled carbon nanotubes (SWCNTs) and tin oxide (SnO2). First, a SWCNT layer was deposited on the ITO substrate; and photoactive material was then coated on the top of the SWCNT layer. For the second method, photoactive particles were added to a solution of SWCNTs. The SWCNT/SnO2 solution was mechanically stirred and then deposited on the ITO substrate. For the third method, we synthesized photoactive particles on SWCNTs through a chemical-solution routine using SnCl4 as a precursor. We characterized the morphology and structure of the SWCNTs coated with SnO2 nanoparticles prepared with the three different methods by using a field emission scanning electron microscope equipped with an X-ray energy dispersive spectrometer. We characterized the photoelectrochemical properties of all electrodes by using an electrochemical station; mainly, we examined the photocurrent generated under periodic illumination. Our results indicate that there are significant differences in the photocurrent in the presence of SWCNTs. We propose the following hypothetical mechanism: without carbon nanotubes, generated electrons (when light is absorbed by SnO2 particles) must cross the particle network to reach an electrode. Many electrons never escape this network to generate an electrical current. The carbon nanotubes “collect” the electrons and provide, therefore, a more direct route to the electrode, thus improving the efficiency of the solar cells.
Dynamic Mechanical Analysis of Bulk Carbon Nanotube Materials
Authors: Moses Brian T. , Jarosz Paul R. , Schauerman Christopher M. , Alvarenga Jack , Landi Brian J. , Raffaelle Ryne
Published: March 2010

Several purification and processing techniques for laser-produced single wall carbon nanotube (SWCNT) soot were investigated and the resulting changes in the mechanical properties were characterized. SWCNT ribbons had non-nanotube carbonaceous content modified via thermal oxidation and the relationship between oxidation parameters and mechanical strength studied. SWCNT/Polyamide composites were developed and exhibited improved toughness, tensile strength and elongation before break. The composite material is observed to have a greater tensile strength than either the baseline paper or the added nylon.
Autoreduction of Metallic Species on the Surface of Silica Nanoparticles by Surface Functionalization
Authors: Samuel Jorice , Raccurt Olivier , Ling Wai Li , Poncelet Olivier J.C.
Published: March 2010

Silica nanoparticles with metallic nanoclusters are of great interest in many applications from bio imaging to optical devices. The nanometric size of metallic particles induces specific absorption properties due to surface plasmon resonance. This absorption mainly depends on the morphology of the nanoparticles. If the encapsulation of metallic nanoparticles into a silica shell is now well developed, there is a great interest on the synthesis of either silica nanoparticles covered by metallic nanoparticles or silica cores with metallic shells. Two main ways are described in the literature to bind metallic nanoparticles onto the silica nanoparticles. The first way consists on the mixing of a metallic colloidal sol with another sol containing silica nanoparticles bringing at their surface the suitable chemical functions, able to properly interact with the metal nanoparticles. The second way consists on the use of a reducing agent to reduce the metallic ions introduced successively into a suspension of silica nanoparticles. Herein is proposed an original third method based on a double surface functionalization of the silica nanoparticles. This method is actually based on an in-situ reduction of metallic ions by two chemical function (amino and thiol) previously grafted onto the surface of the silica nanoparticles. The silica nanoparticles are synthesized by a reverse micro-emulsion sol-gel process. This synthesis gives monodispersed silica nanoparticles of 40 nm diameter. The surface functionalization of the silica nanoparticles is performed by sol-gel reactions within the micro-emulsion, using two silane-coupling agents owning either a thiol function or a diamino function.The functionalized silica shell increases the chemical activity of the surface of the nanoparticles. But the capability of this functionalized surface to reduce metallic ions depends mainly on the chemical function used. Two examples are given in this study: the diamino functions, which reduce the copper ions, and the combination of the diamino and the thiol functions in a silver nitrate solutionwhich induces the growth of small silver nanoparticles (4-5 nm) on the silica nanoparticles’ surface.
Si/SiO2 Quantum Dots: Electronic Properties
Authors: Filikhin Igor N , Matinyan Sergei G , Vlahovic Branislav
Published: March 2010

Spherical shaped Si quantum dots (QDs) embedded into the SiO2 substrate are considered in the single sub-band effective mass approach. The electron and heavy hole sub-bands are taken into account. The energy dependence of electron effective mass is applied especially for small size QD. Calculations of low-lying single electron and hole energy levels are performed.
For QD of small sizes (diameter D≤6 nm) there is a strong confinement regime when the number of energy levels is restricted to several levels. The first order of the perturbation theory is used to calculate neutral exciton recombination energy taking into account the Coulomb force between electron and heavy hole. The PL exciton data are reproduced well by our model calculations. We also compare the results with those obtained within model [1].
For weak confinement regime (size D≥10 nm), when the number of confinement levels is limited by several hundred, we considered the statistical properties of the electron confinement. Distribution function for the electron levels is calculated and results are discussed.
Superfluorescent Pulsed Emission from Biexcitons in an Ensemble of CuCl Quantum Dots
Authors: Miyajima Kensuke , Saito Shingo , Ashida Masaaki , Itoh Tadashi
Published: March 2010

Time-resolved photoluminescence spectra of an ensemble of CuCl quantum dots have been measured by an optical Kerr gate method. The excitation photon energy was tuned to resonant energy for two-photon excitation of biexcitons. We observed that the time profiles of biexciton bands were changed from an exponential fast decay to a pulsed shape. This result indicates a transition from amplified spontaneous emission to superfluorescence. These results will introduce a new field of coherent phenomena originating an ensemble of quantum dots.
Enhancement of Photovoltaic Device Performance in Close-Packed Nanowire Excitonic Solar Cells by Förster Resonance Energy Transfer (FRET)
Authors: Shankar Karthik , Kim Sanghoon , Feng Xinjian , Mohammadpour Arash , Grimes Craig Alan
Published: March 2010

Our ability to fabricate close-packed single crystal rutile TiO2 nanowire arrays with average inter-wire distances of 5-10 nm allows us to create and control FRET-induced coupling effects, which can occur in this distance regime, in this architecture. We explored the use of such coupling to boost the performance of nanowire excitonic solar cells. Using Ru complex triplet dye N719 as the energy acceptor and fluorescent tetra tert-butyl substituted zinc phthalocyanine as the energy donor (see Fig. 1 for molecular structures), we obtained up to a four fold improvement in the quantum yield for red photons in the 660-690 nm spectral range. Similarly, by using a carboxylated unsymmetrical squaraine dye as the energy acceptor and highly fluorescent Nile Red dye as the donor (see Fig. 1 for molecular structures), we obtained 60% increased external quantum yields for photons in the 480-580 nm spectral range. For both systems, the use of FRET broadened spectral coverage and improved light harvesting. In this report, we also develop fundamental design principles in choosing donor-acceptor combinations for high efficiency FRET-enhanced solar cells in nanowire array architectures.
A Novel and Low-Cost Disposable Device for Phototherapy of Neonatal Jaundice
Authors: Ferreira Giovana R , Vasconcelos Cláudia K. B. de , Silva Mariana M , Santos Fabrício A dos , Pires Jorge G. , Duarte André S , Bianchi Andrea Gomes Campos , Bianchi Rodrigo Fernando
Published: March 2010

The present work details, to our knowledge, the first examination of the influence of blue-light radiation on the optical properties of organic luminescent films in attempting to develop an indicator dosimeter for phototherapy of neonatal jaundice. Jaundice is the most common problem encountered in newborns due to immature functioning in the liver. The operating principle of the device is based on the optical response of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene (MEH-PPV) and tris(8-hydroxyquinolinato) aluminum (Alq3) materials dispersed in polystyrene (PS) matrix (denoted as PS/MEH-PPV/Alq3). It is observed a blue-shift on the photoluminescence of PS/MEH-PPV/Alq3 system from red to orange-yellow, and then to green as function of the blue-light radiation exposure time. The result is attributed to the spectral overlap between emission of Alq3 and absorption of MEH-PPV. The optical response of PS/MEH-PPV/Alq3 to radiation was investigated to design a low-cost (< US$ 0.05) “smart” sensor to represent easily the radiation dosage normally used in blue-light phototherapy. The basic idea behind this concept considers the sensor as a traffic light device, where red represents underdose and green the prescription dose or overdose, while orange-yellow suggests that radiation therapy is an ongoing process. This personal real-time radiation dosimeter appears here as a key requirement for successful development of innovations in effective management of the radiation dose planning before treatment of neonatal where control of dose absorption of infants is extremely important.
Advanced Sciences Convergence for Defense and Security
Authors: Vaseashta Ashok , Braman E.W. , Alvelo J. , Susmann P.
Published: March 2010

The process of Advanced Science Convergence is to understand how different disciplines, focusing on discrete problems and applications, can be coalesced into a system to solve an intractable problem. It requires understanding of far-reaching end goal that is not yet defined but can be described in terms of desired actions or qualities. Institute of Advanced Sciences Convergence (IASC) provides an early monitoring and identification of emerging scientific advances across multiple disciplines that create revolutionary, integrated and cross-cutting technologies to break through existing solution paradigms. The objective of IASC is to support federal agencies by providing cutting-edge, functional, and advanced technological solutions in support of national security by employing emerging areas in nanotechnology, biotechnology, information processing, and cognitive sciences. Our team is supported by professionals with extensive background in academia, military, federal agencies and international organizations. The IASC value proposition is based on assessment derived from data collected from various resources. The IASC business model provides invaluable information in support of national security based on staff experience without the expense of laboratory infrastructure. Due to rapid developments in nanotechnology, IASC seeks to reach out to identify partners through research collaboration as SMEs to support objectives through identifying advances in NBIC areas and develop strategic investments for technology/science roadmap.
Length and Time Scales of Entanglement and Confinement Effects Constraining Polymer Chain Dynamics
Authors: Kimmich Rainer , Fatkullin Nail
Published: March 2010

With characteristic time constants for polymer dynamics, namely τs (the segment fluctuation time), τe (the entanglement time), and τR (the longest Rouse relaxation time), the time scales of particular interest (i) t<τs, (ii) τs<t<τe, and (iii) τe<t<τR will be discussed and compared with experimental data. These ranges correspond to the chain-mode length scales (i) l<b, (ii) b<l<d2/b, and (iii) d2/b<l<L, where b is the statistical segment length, d is the dimension of constraints by entanglements and/or confinement, and L is the chain contour length. Based on Langevin-type equations-of-motion coarse-grained predictions for the mean-squared segment displacement and the spin-lattice relaxation dispersion will be outlined for the scenarios “freely-draining”, “entangled”, and “confined”. In the discussion we will juxtapose “local” versus “global” dynamics on the one hand, and “bulk” versus “confined” systems on the other.
The Effect of Temperature on the Efficiency of Nitride-based Multi-quantum well Light-emitting Diodes
Authors: Heikkilä Oskari , Oksanen Jani , Tulkki Jukka
Published: March 2010

We have recently developed a self consistent light-emitting diode (LED) model that accounts for the current transport and internal heating in AlGaAs-GaAs LEDs. In this paper we extend the model to describe multi-quantum well (MQW) active regions and III-N materials, within the limits of the currently known values and temperature dependencies of the recombination parameters in these materials. The MQW description accounts for the effect of the reduced wave function overlap to the recombination. We present simulation results obtained for an InGaN MQW LED with 4 wells at selected temperatures and discuss the factors limiting the efficiency and luminescent output of LEDs.
Nanomonitor Technology for Glycosylation Analysis
Authors: Chatterjee Gaurav , Bothara Manish , Aithal Srivatsa , Nagraj Vinay J , Wiktor Peter , Eaton Seron , Prasad Shalini
Published: March 2010

Changes in protein glycosylation have great potential as markers for the early diagnosis of cancer and other diseases. The current analytical tools for the analysis of glycan structures need expensive instrumentation, advanced expertise, is time consuming and therefore not practical for routine screening of glycan biomarkers from human samples in a clinical setting.

We are developing a novel ultrasensitive diagnostic platform called ‘NanoMonitor’ to enable rapid label-free glycosylation analysis. The technology is based on electrochemical impedance spectroscopy where capacitance changes are measured at the electrical double layer interface as a result of interaction of two molecules.

The NanoMonitor platform consists of a printed circuit board with array of electrodes forming multiple sensor spots. Each sensor spot is overlaid with a nanoporous alumina membrane that forms a high density of nanowells. Lectins, proteins that bind to and recognize specific glycan structures, are conjugated to the surface of nanowells. When specific glycoproteins from a test sample bind to lectins in the nanowells, it produces a perturbation to the electrical double layer at the solid/liquid interface at the base of each nanowell. This perturbation results in a change in the impedance of the double layer which is dominated by the capacitance changes within the electrical double layer.

The nanoscale confinement or crowding of biological macromolecules within the nanowells is likely to enhance signals from the interaction of glycoproteins with the lectins leading to a high sensitivity of detection with the NanoMonitor as compared to other electrochemical techniques.

Using a panel of lectins, we were able to detect subtle changes in the glycosylation of fetuin protein as well as differentiate glycoproteins from normal versus cancerous cells. Our results indicate that NanoMonitor can be used as a cost-effective miniature electronic biosensor for the detection of glycan biomarkers.
Increased serum level of early prostate cancer antigen is associated with subsequent cancer risk in men with high-grade prostatic intraepithelial neoplasia
Authors: Zhao Zhigang , Zeng Guohua
Published: March 2010

Early prostate cancer antigen (EPCA) has been recently suggested as a novel biomarker in malignant and premalignant lesions of the prostate. This study was to examine serum expression of EPCA and to further clarify the relationship between initial serum EPCA levels and the presence of subsequent cancer in the individuals with isolated high-grade prostatic intraepithelial neoplasia (HGPIN). An indirect ELISA was used for initial serum EPCA measurement in 112 men with isolated HGPIN, who were enrolled and completed a follow-up of ≥5 years. All patients had a detectable concentration of EPCA in the initial serum, with a mean of 0.64±0.13 absorbance at 450 nm. Thirty-three patients had an initial serum EPCA level of ≥1.10, in which 31 cases were subsequently identified as having prostate cancer on follow-up. However, in the remaining 79 cases, serum EPCA levels were all <1.10, and none was diagnosed with cancer later. Statistical analysis showed a significantly higher serum ECPA level in isolated HGPIN patients with subsequent cancer than those without cancer (P<0.001). The area under the receiver operating characteristic curves showed that serum EPCA level had better predictive accuracy of cancer onset on follow-up than prostate specific antigen velocity and abnormal digital rectal examination findings. Furthermore, univariate and multivariate Cox regression analyses demonstrated the predictive performance independently by initial serum EPCA≥1.10 absorbance (relative risk, 3.32; 95% confidence intervals, 2.62–5.03, P<0.001). These preliminary findings first show the potential of serum EPCA to serve as a significant predictor for subsequent cancer in isolated HGPIN.
Tuning stochastic matrix models with hydrologic data to predict the population dynamics of a riverine fish
Authors: Sakaris Peter C. , Irwin Elise R.
Published: March 2010

We developed stochastic matrix models to evaluate the effects of hydrologic alteration and variable mortality on the population dynamics of a lotic fish in a regulated river system. Models were applied to a representative lotic fish species, the flathead catfish (Pylodictis olivaris), for which two populations were examined: a native population from a regulated reach of the Coosa River (Alabama, USA) and an introduced population from an unregulated section of the Ocmulgee River (Georgia, USA). Size‐classified matrix models were constructed for both populations, and residuals from catch‐curve regressions were used as indices of year class strength (i.e., recruitment). A multiple regression model indicated that recruitment of flathead catfish in the Coosa River was positively related to the frequency of spring pulses between 283 and 566 m3/s. For the Ocmulgee River population, multiple regression models indicated that year class strength was negatively related to mean March discharge and positively related to June low flow. When the Coosa population was modeled to experience five consecutive years of favorable hydrologic conditions during a 50‐year projection period, it exhibited a substantial spike in size and increased at an overall 0.2% annual rate. When modeled to experience five years of unfavorable hydrologic conditions, the Coosa population initially exhibited a decrease in size but later stabilized and increased at a 0.4% annual rate following the decline. When the Ocmulgee River population was modeled to experience five years of favorable conditions, it exhibited a substantial spike in size and increased at an overall 0.4% annual rate. After the Ocmulgee population experienced five years of unfavorable conditions, a sharp decline in population size was predicted. However, the population quickly recovered, with population size increasing at a 0.3% annual rate following the decline. In general, stochastic population growth in the Ocmulgee River was more erratic and variable than population growth in the Coosa River. We encourage ecologists to develop similar models for other lotic species, particularly in regulated river systems. Successful management of fish populations in regulated systems requires that we are able to predict how hydrology affects recruitment and will ultimately influence the population dynamics of fishes.
Modeling landscape‐scale pathogen spillover between domesticated and wild hosts: Asian soybean rust and kudzu
Authors: Fabiszewski Anna M. , Umbanhowar James , Mitchell Charles E.
Published: March 2010

Many emerging pathogens infect both domesticated and wild host species, creating the potential for pathogen transmission between domesticated and wild populations. This common situation raises the question of whether managing negative impacts of disease on a focal host population (whether domesticated, endangered, or pest) requires management of only the domesticated host, only the wild host, or both. To evaluate the roles of domesticated and wild hosts in the dynamics of shared pathogens, we developed a spatially implicit model of a pathogen transmitted by airborne spores between two host species restricted to two different landscape patch types. As well as exploring the general dynamics and implications of the model, we fully parameterized our model for Asian soybean rust, a multihost infectious disease that emerged in the United States in 2004. The rust fungus Phakopsora pachyrhizi infects many legume species, including soybeans (Glycine max) and the nonnative invasive species kudzu (Pueraria montana var. lobata). Our model predicts that epidemics are driven by the host species that is more abundant in the landscape. In managed landscapes, this will generally be the domesticated host. However, many pathogens overwinter on a wild host, which acts as the source of initial inoculum at the start of the growing season. Our model predicts that very low local densities of infected wild hosts, surviving in landscape patches separate from the domesticated host, are sufficient to initiate epidemics in the domesticated host, such that managing epidemics by reducing wild host local density may not be feasible. In contrast, managing to reduce pathogen infection of a domesticated host can reduce disease impacts on wild host populations.
Trends in agricultural impact and recovery of wetlands in prairie Canada
Authors: Bartzen Blake A. , Dufour Kevin W. , Clark Robert G. , Caswell F. Dale
Published: March 2010

Despite widespread recognition that they provide valuable ecosystem services and contribute significantly to global biodiversity, over half of the world's wetlands have been lost, primarily to agriculture. Wetland loss is evident in prairie Canada, but comprehensive information about causes of ongoing impact for existing wetlands is lacking. Habitat data collected for ∼10 500 wetlands during annual waterfowl surveys (1985–2005) were analyzed using multistate models to estimate rates of wetland impact and recovery from agricultural activities in the Canadian prairies. An impact was defined as an agricultural activity that visibly altered a wetland margin (natural vegetation surrounding wetland interiors) or basin (interior depression capable of holding water), whereas recovery was deemed to have occurred if agricultural activities had ceased and effects were no longer visibly apparent. We estimated separate impact and recovery rates for wetland basins and wetland margins and considered covariates such as location, time, wetness indices, land use, and wetland permanence. Results indicate that impact rates for wetland margins have declined over time, likely due to a decreasing percentage of unaffected wetlands on the landscape. Recovery rates for margins were always lower than impact rates, suggesting progressive incidence of impacts to wetlands over time. Unlike margins, impact and recovery rates for basins fluctuated with May pond densities, which we used as a wetness index. Shallow ephemeral wetlands located in agricultural fields had the highest impact and lowest recovery rates relative to wetlands with higher water permanence or situated in areas of lower agricultural intensity. High rates and incidence of wetland impact in conjunction with low recovery rates clearly demonstrate the need for stronger wetland protection in prairie Canada.
Forest restoration in a mixed‐ownership landscape under climate change
Authors: Ravenscroft Catherine , Scheller Robert M. , Mladenoff David J. , White Mark A.
Published: March 2010

The extent to which current landscapes deviate from the historical range of natural variability (RNV) is a common means of defining and ranking regional conservation targets. However, climate‐induced shifts in forest composition may render obsolete restoration strategies and conservation targets based on historic climate conditions and disturbance regimes. We used a spatially explicit forest ecosystem model, LANDIS‐II, to simulate the interaction of climate change and forest management in northeastern Minnesota, USA. We assessed the relevance of restoration strategies and conservation targets based on the RNV in the context of future climate change. Three climate scenarios (no climate change, low emissions, and high emissions) were simulated with three forest management scenarios: no harvest, current management, and a restoration‐based approach where harvest activity mimicked the frequency, severity, and size distribution of historic natural disturbance regimes. Under climate change there was a trend toward homogenization of forest conditions due to the widespread expansion of systems dominated by maple (Acerspp.). White spruce (Picea glauca), balsam fir (Abies balsamea), and paper birch (Betula papyrifera) were extirpated from the landscape irrespective of management activity; additional losses of black spruce (P. mariana), red pine (Pinus resinosa), and jack pine (P. banksiana) were projected in the high‐emissions scenario. In the restoration management scenario, retention and conversion to white pine (P. strobus) restricted maple expansion. But, widespread forest loss in the restoration scenario under high‐emissions projections illustrates the potential pitfalls of implementing an RNV management approach in a system that is not compositionally similar to the historic reference condition. Given the uncertainty associated with climate change, ensuring a diversity of species and conditions within forested landscapes may be the most effective means of ensuring the future resistance of ecosystems to climate‐induced declines in productivity.
Combining local‐ and large‐scale models to predict the distributions of invasive plant species
Authors: Jones Chad C. , Acker Steven A. , Halpern Charles B.
Published: March 2010

Habitat distribution models are increasingly used to predict the potential distributions of invasive species and to inform monitoring. However, these models assume that species are in equilibrium with the environment, which is clearly not true for most invasive species. Although this assumption is frequently acknowledged, solutions have not been adequately addressed. There are several potential methods for improving habitat distribution models. Models that require only presence data may be more effective for invasive species, but this assumption has rarely been tested. In addition, combining modeling types to form “ensemble” models may improve the accuracy of predictions. However, even with these improvements, models developed for recently invaded areas are greatly influenced by the current distributions of species and thus reflect near‐ rather than long‐term potential for invasion. Larger scale models from species' native and invaded ranges may better reflect long‐term invasion potential, but they lack finer scale resolution. We compared logistic regression (which uses presence/absence data) and two presence‐only methods for modeling the potential distributions of three invasive plant species on the Olympic Peninsula in Washington, USA. We then combined the three methods to create ensemble models. We also developed climate envelope models for the same species based on larger scale distributions and combined models from multiple scales to create an index of near‐ and long‐term invasion risk to inform monitoring in Olympic National Park (ONP). Neither presence‐only nor ensemble models were more accurate than logistic regression for any of the species. Larger scale models predicted much greater areas at risk of invasion. Our index of near‐ and long‐term invasion risk indicates that <4% of ONP is at high near‐term risk of invasion while 67–99% of the Park is at moderate or high long‐term risk of invasion. We demonstrate how modeling results can be used to guide the design of monitoring protocols and monitoring results can in turn be used to refine models. We propose that, by using models from multiple scales to predict invasion risk and by explicitly linking model development to monitoring, it may be possible to overcome some of the limitations of habitat distribution models.
Quantifying avian nest survival along an urbanization gradient using citizen‐ and scientist‐generated data
Authors: Ryder Thomas B. , Reitsma Robert , Evans Brian , Marra Peter P.
Published: March 2010

Despite the increasing pace of urbanization little is known about the factors that limit bird populations (i.e., population‐level processes) within the urban/suburban land‐use matrix. Here, we report rates of nest survival within the matrix of an urban land‐use gradient in the greater Washington, D.C., USA, area for five common songbirds using data collected by scientists and citizens as part of a project called Neighborhood Nestwatch. Using program MARK, we modeled the effects of species, urbanization at multiple spatial scales (canopy cover and impervious surface), and observer (citizen vs. scientist) on nest survival of four open‐cup and one cavity‐nesting species. In addition, artificial nests were used to determine the relative impacts of specific predators along the land‐use gradient. Our results suggest that predation on nests within the land‐use matrix declines with urbanization but that there are species‐specific differences. Moreover, variation in nest survival among species was best explained by urbanization metrics measured at larger “neighborhood” spatial scales (e.g., 1000 m). Trends were supported by data from artificial nests and suggest that variable predator communities (avian vs. mammalian) are one possible mechanism to explain differential nest survival. In addition, we assessed the quality of citizen science data and show that citizens had no negative effect on nest survival and provided estimates of nest survival comparable to Smithsonian biologists. Although birds nesting within the urban matrix experienced higher nest survival, individuals also faced a multitude of other challenges such as contaminants and invasive species, all of which could reduce adult survival.
Combining a dispersal model with network theory to assess habitat connectivity
Authors: Lookingbill Todd R. , Gardner Robert H. , Ferrari Joseph R. , Keller Cherry E.
Published: March 2010

Assessing the potential for threatened species to persist and spread within fragmented landscapes requires the identification of core areas that can sustain resident populations and dispersal corridors that can link these core areas with isolated patches of remnant habitat. We developed a set of GIS tools, simulation methods, and network analysis procedures to assess potential landscape connectivity for the Delmarva fox squirrel (DFS; Sciurus niger cinereus), an endangered species inhabiting forested areas on the Delmarva Peninsula, USA. Information on the DFS's life history and dispersal characteristics, together with data on the composition and configuration of land cover on the peninsula, were used as input data for an individual‐based model to simulate dispersal patterns of millions of squirrels. Simulation results were then assessed using methods from graph theory, which quantifies habitat attributes associated with local and global connectivity. Several bottlenecks to dispersal were identified that were not apparent from simple distance‐based metrics, highlighting specific locations for landscape conservation, restoration, and/or squirrel translocations. Our approach links simulation models, network analysis, and available field data in an efficient and general manner, making these methods useful and appropriate for assessing the movement dynamics of threatened species within landscapes being altered by human and natural disturbances.
Mental Illness Beliefs Inventory: A Preliminary Validation of a Measure of the Level of Belief in the Medical Model of Mental Illness
Authors: Lewis Steve J. , Lacasse Jeffrey R. , Spaulding-Givens Jennifer
Published: March 2010

The Mental Illness Beliefs Inventory (MIBI) measures the extent to which an individual subscribes to the medical model of mental illness. This article reports the results of two preliminary validation studies. The first study establishes the initial psychometric properties for the MIBI, based on a sample of 222 students in the helping professions; the second study tests the model established in the first study with an additional 270 students. The MIBI performs well as a composite instrument measuring belief in the medical model of mental illness. This instrument shows promise for examining the extent to which individual beliefs affect mental health practice.
Metals Removal from Stormwater by Commercial and Non‐Commercial Granular Activated Carbons
Authors: van Lienden Christopher , Shan Lin , Rao Shweta , Ranieri Ezio , Young Thomas M.
Published: March 2010

Removing dissolved metals from urban stormwater may be required to protect aquatic species in particular watersheds. This research examined the adsorption of zinc and copper on 12 granular activated carbons, of which six were obtained commercially and six were produced by thermal activation of agricultural byproducts in the laboratory. Batch studies were used to obtain single solute distribution coefficients at pH 7. Copper distribution coefficients were higher than those for zinc on each of the 12 adsorbents. Granular activated carbon (GAC) produced from nutshells was less effective than that produced from rice materials (straw and hulls). The rice‐derived GACs had the highest zinc distribution coefficients, and the commercial GACs typically exhibited higher copper distribution coefficients. Distribution coefficients for zinc and copper typically were higher for the materials tested in this study than in previous research, possibly because of the lower dissolved metal concentrations used, which were chosen to represent highway stormwater. Adsorption isotherms were obtained for zinc and copper adsorption on one commercial GAC and on activated rice hulls in buffered laboratory water and in highway stormwater. The constituents in stormwater caused a reduction in sorption of zinc and copper of up to 80%. The results suggest that 1 kg of activated rice hulls could treat up to 7 m3 of stormwater for zinc or 46 m3 of copper before exhaustion at the 90th percentile dissolved concentrations in California highway stormwater. The higher stormwater concentration and lower GAC affinity of zinc means that this constituent typically will limit adsorption system design for removal of multiple metals from stormwater.
Decolorization of Dye‐Containing Textile Industry Effluents Using Ganoderma Lucidum IBL‐05 in Still Cultures
Authors: Asgher Muhammad , Noreen Sadia , Bhatti Haq Nawaz
Published: March 2010

A locally isolated white rot fungus Ganoderma Lucidum IBL‐05 was used for development of a bioremediation process for original textile industry effluents. Dye‐containing effluents of different colors were collected from the Arzoo (maroon), Ayesha (yellow), Ittemad (green), Crescent (navy blue) and Magna (yellowish) textile industries of Faisalabad, Pakistan. G. lucidum IBL‐05 was screened for its decolorization potential on all the effluents. Maximum decolorization (49.5 %) was observed in the case of the Arzoo textile industry (ART) effluent (λmax = 515 nm) on the 10th day of incubation. Therefore, the ART effluent was selected for optimization of its decolorization process. Process optimization could improve color removal efficiency of the fungus to 95% within only 2 days, catalyzed by manganese peroxidase (1295 U/mL) as the main enzyme activity at pH 3 and 35°C using 1% starch supplemented Kirk's basal medium. Nitrogen addition inhibited enzyme formation and effluent decolorization. The economics and effectiveness of the process can be improved by further process optimization.
Phosphate Removal from Aqueous Solution by Adsorption on Modified Giant Reed
Authors: Yue Qin‐Yan , Wang Wen‐Yi , Gao Bao‐Yu , Xu Xing , Zhang Jian , Li Qian
Published: March 2010

The use of modified giant reed (MGR) as an adsorbent to remove phosphate from an aqueous solution was investigated. The dosage of MGR, pH of the phosphate solution, thermodynamics, and the effects of several factors on kinetics (concentration of phosphate solution, solution temperature, and shaking speed) were studied in batch experiments. The results showed that MGR was particularly effective to remove phosphate and that the effective pH range for the phosphate removal was between 4 and 9. The adsorption process could reach equilibrium in 25 minutes. Three kinetic models have been evaluated to fit the experimental data. It was shown that the pseudo‐second‐order model best described the adsorption kinetics of phosphate on MGR. The low activation energy of the adsorption suggested a physisorption process for phosphate adsorption. The equilibrium isotherm showed that the adsorption system was consistent with the Langmuir equation. The negative values of standard free energy (ΔG) and enthalpy (ΔH) indicated that the adsorption of phosphate onto MGR was a spontaneous and exothermic process.
Dispersal Characteristics of Juvenile Bobcats in South‐Central Indiana
Authors: JOHNSON SCOTT A. , WALKER HEATHER D. , HUDSON CASSIE M.
Published: March 2010

ABSTRACT  Bobcat (Lynx rufus) populations in the Midwestern United States experienced historic declines due to habitat loss and exploitation but have rebounded in recent decades. We investigated natal dispersal of juvenile bobcats from a population in south‐central Indiana, USA, from 1999 to 2006. We radiocollared 16 juvenile bobcats (11 M, 5 F) and monitored them for 237–1,014 days (x̄ = 506). One female (20%) and 11 males (100%) dispersed from natal home ranges that averaged 14.6 km2 in size. Most juveniles (70%) initiated dispersal from mid‐February through March, late in their first year. Only 5 bobcats (42%) ultimately established a final home range 63 ± 35 km2 in size 13–92 km (x̄ = 44) from their natal range 140 ± 45 days after initiating dispersal. Survival did not differ (P = 0.93) between dispersing (S = 0.73) and philopatric (S = 0.75) individuals, although 4 bobcats (3 M, 1 F) were killed in collisions with vehicles. We found dispersal of bobcats in fragmented landscapes is prolonged and often unsuccessful; the ability of dispersers to locate suitable vacant habitat patches may be vital to the continued growth of bobcat populations recolonizing the agricultural Midwest.
Using Bobcat Habitat Suitability to Prioritize Habitat Preservation on a Suburbanizing Barrier Island
Authors: ROBERTS SHANE B. , JORDAN JAMES D. , BETTINGER PETE , WARREN ROBERT J.
Published: March 2010

ABSTRACT  Many land‐trust organizations attempt to preserve habitat that will benefit specific wildlife species or suites of species. With limited resources available, these organizations need tools to prioritize preservation efforts. One such organization, the Kiawah Island Natural Habitat Conservancy (KINHC), is attempting to preserve wildlife habitat in the face of ever‐increasing property values and development pressure on Kiawah Island, South Carolina, USA. We modified an existing bobcat (Lynx rufus) habitat suitability index model, which focuses on suitability of habitats for food, by including components for concealment cover and den habitat. We developed a windows‐based computer program that calculates modified habitat suitability index (MHSI) values that can easily be imported into a Geographic Information System for display in map form, allowing for frequent reevaluation of site‐specific habitat suitability as land‐cover patterns change. We used locations collected from radiocollared bobcats to assess validity of the food and cover components of the MHSI. Bobcats used areas identified as highly suitable for food more than expected during nocturnal time periods (G52 = 640.9, P < 0.001) and areas identified as highly suitable for cover more than expected during diurnal time periods (G37 = 1,194.0, P < 0.001). Our approach for evaluating bobcat habitat suitability will allow KINHC to identify parcels that likely provide the greatest ecological benefit to bobcats and their associated wildlife community. Our approach could be altered to consider habitat requirements of other species, or multiple species, at virtually any location for which fine‐scale land‐cover data are available.
An Evaluation of Diazacon as a Potential Contraceptive in Non‐Native Rose‐Ringed Parakeets
Authors: LAMBERT MARK S. , MASSEI GIOVANNA , YODER CHRISTI A. , COWAN DAVID P.
Published: March 2010

ABSTRACT  Rose‐ringed parakeets (Psittacula krameri) have become widely established outside their native range through accidental or deliberate release. Potential economic impacts on agriculture, conservation concerns, and mixed public opinion regarding the species have highlighted the need to develop effective but humane management options. Fertility control might provide such a solution if a safe and environmentally benign contraceptive was available. The chemical 20,25‐diazacholesterol dihydrochloride (diazacon) has previously been used to reduce reproductive output in avian species through reduction of blood cholesterol and cholesterol‐dependent reproductive hormones. We orally dosed captive rose‐ringed parakeets with a solution of either 9 mg/kg or 18 mg/kg of diazacon for up to 10 days and found that a dose of 18 mg/kg for 10 days temporarily reduced blood cholesterol levels with no adverse side effects. We evaluated this dose level in a captive population in semi‐natural conditions during the 2008 breeding season and found a significant decrease in fertility. We concluded that diazacon has potential for fertility control in this species if a suitable formulation and delivery system is developed for free‐living populations.