bluuebunny/crossref_metadata_2025_split huggingface dataset:
The study of the charge collection of the normal‐collector configuration
Authors: Tan Chee Chin , Ong Vincent K. S. , Radhakrishnan K. 
Published: March 2012

ABSTRACTCharge collection is one of the crucial processes to collect the induced current when a semiconductor sample is subjected to some external excitations such as the electron or photon beams. The charge collection probability is the basis in the study of this induced current particularly in the field of photonic devices, photovoltaic cells as well as in the characterization of semiconductor materials and devices. In this paper, the analytical expressions for the charge collection probability of the finite‐dimension normal‐collector configuration, with and without surface recombination at the free surfaces are presented. An excellent agreement has been found between the charge collection probability profiles computed using the presently derived analytical expressions and those obtained using a device simulator. The results have been used to study the effects of the various physical parameters on the charge collection probability. These analytical expressions are expected to enhance our understanding of the charge collection process. Copyright © 2012 John Wiley & Sons, Ltd.
Structural and enzymatic characterization of BacD, an L‐amino acid dipeptide ligase from Bacillus subtilis
Authors: Shomura Yasuhito , Hinokuchi Emi , Ikeda Hajime , Senoo Akihiro , Takahashi Yuichi , Saito Jun‐ichi , Komori Hirofumi , Shibata Naoki , Yonetani Yoshiyuki , Higuchi Yoshiki 
Published: March 2012

AbstractBacD is an ATP‐dependent dipeptide ligase responsible for the biosynthesis of L‐alanyl‐L‐anticapsin, a precursor of an antibiotic produced by Bacillus spp. In contrast to the well‐studied and phylogenetically related D‐alanine: D‐alanine ligase (Ddl), BacD synthesizes dipeptides using L‐amino acids as substrates and has a low substrate specificity in vitro. The enzyme is of great interest because of its potential application in industrial protein engineering for the environmentally friendly biological production of useful peptide compounds, such as physiologically active peptides, artificial sweeteners and antibiotics, but the determinants of its substrate specificity and its catalytic mechanism have not yet been established due to a lack of structural information. In this study, we report the crystal structure of BacD in complex with ADP and an intermediate analog, phosphorylated phosphinate L‐alanyl‐L‐phenylalanine, refined to 2.5‐Å resolution. The complex structure reveals that ADP and two magnesium ions bind in a manner similar to that of Ddl. However, the dipeptide orientation is reversed, and, concomitantly, the entrance to the amino acid binding cavity differs in position. Enzymatic characterization of two mutants, Y265F and S185A, demonstrates that these conserved residues are not catalytic residues at least in the reaction where L‐phenylalanine is used as a substrate. On the basis of the biochemical and the structural data, we propose a reaction scheme and a catalytic mechanism for BacD.
Toxicity of formic acid to red imported fire ants, Solenopsis invicta Buren
Authors: Chen Jian , Rashid Tahir , Feng Guolei 
Published: March 2012

AbstractBACKGROUND: Ants often compete with other ants for resources. Although formic acid is a common defensive chemical of formicine ants, it does not occur in any other subfamilies in Formicidae. No information on toxicity of formic acid to red imported fire ants, Solenopsis invicta, is available. This study examined its contact and fumigation toxicity to S. invicta in the laboratory.RESULTS: In a contact toxicity bioassay, 24 h LD50 values of formic acid for workers ranged from 124.54 to 197.71 µg ant−1. Female alates and queens were much less sensitive to formic acid than workers. At a concentration of 271.72 µg ant−1, which killed 81.09 ± 16.04% of workers, the 24 h mortality was up to 39.64% for female alates and 38.89% for queens. In fumigation bioassays, 24 h LC50 values ranged from 0.26 to 0.50 µg mL−1 for workers, 0.32 µg mL−1 for male alates and 0.70 µg mL−1 for female alates. Complete mortality (100%) in queens occurred 24 h after they had been exposed to 1.57 µg mL−1 of formic acid. At a concentration of 2.09 µg mL−1, KT50 values ranged from 23.03 to 43.85 min for workers, from 37.84 to 58.37 min for male alates, from 86.06 to 121.05 min for female alates and from 68.00 to 85.92 min for queens.CONCLUSION: When applied topically, formic acid was significantly less toxic than bifenthrin to red imported fire ants. Although its fumigation toxicity was lower than that of dichlorvos, formic acid had about an order of magnitude higher toxicity to S. invicta than to other insects studied so far. It may be worth investigating the use of formic acid for managing imported fire ants. Published 2012 by John Wiley & Sons, Ltd.
Effect of chelating agents in phytoremediation of heavy metals
Authors: Dipu S. , Kumar Anju A. , Thanga Salom Gnana 
Published: March 2012

AbstractChelate‐assisted metal uptake by plants has only recently been discovered in the remediation industry. The simultaneous accumulation of lead, arsenic, copper, and cadmium in plants after application of chelating agents to soil is a promising technology enhancement for phytoremediation. One of the most powerful and commonly used chelating agents is ethylene diamine tetra acetic acid (EDTA), which forms complexes with many of the metal contaminants within the natural environment. This study was conducted to determine the efficiency of an emergent wetland plant species Typha sp. and floating wetland macrophytes such as Pistia sp., Azolla sp., Lemna sp., Salvinia sp., and Eichhornia sp. in phytoremediation of various heavy metals with addition of a chelating agent such as EDTA. EDTA addition to the treatment systems increased the uptake of heavy metals by plants, which was much pronounced with lead and copper. However, the pattern of uptake by plants was similar as that of heavy metals without EDTA amendments. © 2012 Wiley Periodicals, Inc.
Enhanced dichloroethene biodegradation in fractured rock under biostimulated and bioaugmented conditions
Authors: Bradley Paul M. , Journey Celeste A. , Kirshtein Julie D. , Voytek Mary A. , Lacombe Pierre J. , Imbrigiotta Thomas E. , Chapelle Francis H. , Tiedeman Claire J. , Goode Daniel J. 
Published: March 2012

AbstractSignificant microbial reductive dechlorination of [1,2 14C] cis‐dichloroethene (DCE) was observed in anoxic microcosms prepared with unamended, fractured rock aquifer materials, which were colonized in situ at multiple depths in two boreholes at the Naval Air Warfare Center (NAWC) in West Trenton, New Jersey. The lack of significant reductive dechlorination in corresponding water‐only treatments indicated that chlororespiration activity in unamended, fractured rock treatments was primarily associated with colonized core material. In these unamended fractured rock microcosms, activity was highest in the shallow zones and generally decreased with increasing depth. Electron‐donor amendment (biostimulation) enhanced chlororespiration in some but not all treatments. In contrast, combining electron‐donor amendment with KB1 amendment (bioaugmentation) enhanced chlororespiration in all treatments and substantially reduced the variability in chlororespiration activity both within and between treatments. These results indicate (1) that a potential for chlororespiration‐based bioremediation exists at NAWC Trenton but is limited under nonengineered conditions, (2) that the limitation on chlororespiration activity is not entirely due to electron‐donor availability, and (3) that a bioaugmentation approach can substantially enhance in situ bioremediation if the requisite amendments can be adequately distributed throughout the fractured rock matrix. © 2012 Wiley Periodicals, Inc.*
Solar‐powered in situ soil washing with surfactant to collect LNAPL
Authors: Miller Charles , Ruffing Steven , Kline Robert 
Published: March 2012

AbstractThis article presents the findings of a sustainable, surfactant‐enhanced, product recovery pilot‐scale study (PSS) completed between January 2010 and May 2010 at the Hydrocarbon Burn Facility located at the John F. Kennedy Space Center in Florida. The goal of this study was to implement a unique, simple, and sustainable light nonaqueous‐phase liquid (LNAPL) recovery process and evaluate site‐specific volumes and rates of LNAPL that could be collected and the degree of soil and groundwater cleanup that could be achieved. The recovery process was a combination of groundwater recirculation at a rate of approximately 2.9 gallons per minute (11.0 liters per minute), soil washing via LNAPL mobilization, and collection of LNAPL via a hydrophobic LNAPL skimmer. A biodegradable surfactant, ECOSURFTM SA‐15, was added to the recirculation line to lower the interfacial tension and facilitate LNAPL recovery via mobilization. All equipment (submersible pump, LNAPL skimmer, surfactant feed pump, controls, and various other equipment) used was powered by a solar panel array. Approximately 60 gallons (227 liters) or 429 pounds (195 kilograms) of LNAPL were collected at the recirculation site over approximately three months during the PSS. The data suggest that surfactant amendments greatly enhanced free product collection. The maximum rate of free product collection was approximately 1 gallon (3.8 liters) per day. © 2012 Wiley Periodicals, Inc.
Sequestration of metals in active cap materials: A laboratory and numerical evaluation
Authors: Dixon Kenneth L. , Knox Anna S. 
Published: March 2012

AbstractActive capping involves the use of capping materials that react with sediment contaminants to reduce their toxicity or bioavailability. Although several amendments have been proposed for use in active capping systems, little is known about their long‐term ability to sequester metals. Recent research has shown that the active amendment apatite has potential application for metals‐contaminated sediments. The focus of this study was to evaluate the effectiveness of apatite in the sequestration of metal contaminants through the use of short‐term laboratory column studies in conjunction with predictive, numerical modeling. A breakthrough column study was conducted using North Carolina apatite as the active amendment. Under saturated conditions, a spike solution containing elemental As, Cd, Co, Se, Pb, Zn, and a nonreactive tracer was injected into the column. A sand column was tested under similar conditions as a control. Effluent water samples were periodically collected from each column for chemical analysis. Relative to the nonreactive tracer, the breakthrough of each metal was substantially delayed by the apatite. Furthermore, breakthrough of each metal was substantially delayed by the apatite compared to the sand column. Finally, a simple 1‐D, numerical model was created to qualitatively predict the long‐term performance of apatite based on the findings from the column study. The results of the modeling showed that apatite could delay the breakthrough of some metals for hundreds of years under typical groundwater flow velocities. © 2012 Wiley Periodicals, Inc.
Active capping technology—New approaches for in situ remediation of contaminated sediments
Authors: Knox Anna S. , Paller Michael H. , Roberts Jesse 
Published: March 2012

AbstractThis study evaluated pilot‐scale active caps composed of apatite, organoclay, biopolymers, and sand for the remediation of metal‐contaminated sediments. The active caps were constructed in Steel Creek, at the Savannah River Site near Aiken, South Carolina. Monitoring was conducted for 12 months. Effectiveness of the caps was based on an evaluation of contaminant bioavailability, resistance to erosion, and impacts on benthic organisms.Active caps lowered metal bioavailability in the sediment during the one‐year test period. Biopolymers reduced sediment suspension during cap construction, increased the pool of carbon, and lowered the release of metals. This field validation showed that active caps can effectively treat contaminants by changing their speciation, and that caps can be constructed to include more than one type of amendment to achieve multiple goals. © 2012 Wiley Periodicals, Inc.
Simulation of flow and mercury transport in Upper East Fork Poplar Creek, Oak Ridge, Tennessee
Authors: Malek‐Mohammadi Siamak , Tachiev Georgio , Cabrejo Elsa , Lawrence Angelique 
Published: March 2012

AbstractAs a result of nuclear processing activities started back in the 1950s, the environment in the vicinity of the Y‐12 National Security Complex (Y‐12 NSC) in Oak Ridge, Tennessee, and surrounding watersheds has been contaminated by nearly 1,000 tons of elementary mercury. To comply with the state and federal surface water quality standards, a significant reduction in mercury concentration to parts‐per‐trillion levels has been proposed. In order to analyze the mercury cycle in the environment and provide forecasting capabilities for the flow and transport of mercury within the Upper East Fork Poplar Creek (UEFPC) watershed, an integrated surface and subsurface flow and transport model has been developed using the hydrodynamic and transport numerical package, MIKE, developed by the Danish Hydraulic Institute. The model has been constructed and calibrated using an extensive collection of historical records (i.e., hydrological data, and mercury concentration measurements in groundwater, soil, and sediment) obtained from the Oak Ridge Environmental Information System database. Daily fluctuations in stream flow, as a result of scattered rainfall, flooding, and flow augmentation, resuspend the contaminated streambed sediments and/or erode the polluted streambank soil and provide a secondary source of mercury to the creek. In order to investigate the significance of sediment‐mercury interactions on the fate and transport of mercury within the UEFPC study domain, simulations were performed for two different cases (i.e., with and without consideration of sediment‐mercury interactions). Computed total suspended solids and mercury concentrations at the integration point of the creek are compared with the corresponding historical records in both cases. As confirmed by the numerical simulations, a substantial portion of the mercury detected in the river is likely in the form of sediment particle–bound mercury (i.e., mercury particulates). © 2012 Wiley Periodicals, Inc.
IMPORTANCE OF FLOODPLAIN CONNECTIVITY TO FISH POPULATIONS IN THE APALACHICOLA RIVER, FLORIDA
Authors: Burgess O. T. , Pine W. E. , Walsh S. J. 
Published: March 2012

ABSTRACTFloodplain habitats provide critical spawning and rearing habitats for many large‐river fishes. The paradigm that floodplains are essential habitats is often a key reason for restoring altered rivers to natural flow regimes. However, few studies have documented spatial and temporal utilization of floodplain habitats by adult fish of sport or commercial management interest or assessed obligatory access to floodplain habitats for species' persistence. In this study, we applied telemetry techniques to examine adult fish movements between floodplain and mainstem habitats, paired with intensive light trap sampling of larval fish in these same habitats, to assess the relationships between riverine flows and fish movement and spawning patterns in restored and unmodified floodplain distributaries of the Apalachicola River, Florida. Our intent is to inform resource managers on the relationships between the timing, magnitude and duration of flow events and fish spawning as part of river management actions. Our results demonstrate spawning by all study species in floodplain and mainstem river habitat types, apparent migratory movements of some species between these habitats, and distinct spawning events for each study species on the basis of fish movement patterns and light trap catches. Additionally,Micropterusspp.,Lepomisspp. and, to a lesser degree,Minytrema melanopsused floodplain channel habitat that was experimentally reconnected to the mainstem within a few weeks of completing the restoration. This result is of interest to managers assessing restoration activities to reconnect these habitats as part of riverine restoration programmes globally. Copyright © 2012 John Wiley & Sons, Ltd.
PATCH CHANGE AND THE SHIFTING MOSAIC OF AN ENDANGERED BIRD'S HABITAT ON A LARGE MEANDERING RIVER
Authors: Greco S. E. 
Published: March 2012

ABSTRACTThe yellow‐billed cuckoo is a state‐listed endangered bird in California. The largest population of cuckoos in California is on the meandering portion of the middle Sacramento River. I studied two time periods (1952 and 1987) of a 127‐km study reach of the Sacramento River to document regeneration and spatial shifts in yellow‐billed cuckoo habitat patches due to fluvial geomorphic processes, vegetation recruitment and succession over a 35‐year period. The spatial co‐occurrence of natural riparian vegetation and floodplain age <65 years were used to identify sub‐patches of cottonwood forest, a preferred habitat element, within larger patches of contiguous riparian forest. Only 247 ha (15%) of the 1664 ha of habitat sub‐patches identified in 1952 were coincident with those in 1987. Seventeen (27%) of the 62 sub‐patches delineated for 1987 emerged anew and independently of the 1952 patches; the remaining 83% formed by shifting adjacent to the patches from 1952. Comparing observation data (1987–1990) with modelled patches (1987) indicates that 79% of the modelled sub‐patches correctly predicted cuckoo presence or absence. The commission and omission errors were 7% and 14%, respectively. The goal of sustaining the yellow‐billed cuckoo population will require that river channel management encourage channel meander dynamics and channel cut‐off to maintain natural regeneration of cottonwood and willow pioneer plant communities. The active management of hydrodynamic (flow) and geomorphic processes, including the use of prescription flows and the removal of bank revetment (riprap), will be important tools towards achieving this goal. Copyright © 2012 John Wiley & Sons, Ltd.
A proposed meta‐model for formalizing systems engineering knowledge, based on functional architectural patterns
Authors: Pfister F. , Chapurlat V. , Huchard M. , Nebut C. , Wippler J.‐L. 
Published: March 2012

AbstractDesign patterns and architecture patterns have been considerably promoted by software engineering. The software oriented tools and methods have been adapted for systems engineering, conforming to the model driven engineering paradigm proposed by the Object Management Group. However, designers of complex sociotechnical systems have specific concerns, which differ from those of software designers. We propose a method of pattern implementation for systems engineering, based on a functional approach and relying on formal conceptual foundations in the form of a meta‐model, which can be used for the management, application, and cataloguing of patterns specific to the field of systems engineering. A pattern instance in the field of control systems is proposed as an example application: © 2012 Wiley Periodicals, Inc. Syst Eng
Development and application of endothelium‐targeted microparticles for molecular magnetic resonance imaging
Authors: Jefferson Andrew , Wijesurendra Rohan S. , McAteer Martina A. , Choudhury Robin P. 
Published: March 2012

AbstractMolecular imaging of disease states can enhance diagnosis allowing for accurate and more effective treatment. By specifically targeting molecules differentially expressed in disease states, researchers and clinicians have a means of disease characterization at a cellular or tissue level. Targeted micron‐sized particles of iron oxide (MPIO) have been used as molecule‐specific contrast agents for use with magnetic resonance imaging (MRI), and early evidence suggests they may be suitable for use with other imaging modalities. Targeting of MPIO to markers of disease is commonly achieved through the covalent attachment of antibodies to the surface of the particles, providing an imaging agent that is both highly specific and which binds with high affinity. When comparing micron‐sized particles with nanometre‐sized particles, the former provide substantial signal dropout in MRI and confer the sensitivity to detect low levels of target. Furthermore, larger particles appear to bind to targets more potently than smaller particles. Animal models have also demonstrated favorable blood clearance characteristics of MPIO, which are important in achieving favorable signal over background and to attain clearance and disposal. Although the current generation of commercially available MPIO are not suitable for administration into humans, future work may focus on the development of biodegradable and nonimmunogenic MPIO that may allow the use of these imaging agents in a clinical setting. WIREs Nanomed Nanobiotechnol 2012, 4:247–256. doi: 10.1002/wnan.1164This article is categorized under:

Diagnostic Tools > In Vivo Nanodiagnostics and Imaging
Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease
Using the magnetosome to model effective gene‐based contrast for magnetic resonance imaging
Authors: Goldhawk Donna E. , Rohani Roja , Sengupta Anindita , Gelman Neil , Prato Frank S. 
Published: March 2012

AbstractFormation of iron biominerals is a naturally occurring phenomenon, particularly among magnetotactic bacteria which produce magnetite (Fe3O4) in a subcellular compartment termed the magnetosome. Under the control of numerous genes, the magnetosome serves as a model upon which to (1) develop gene‐based contrast in mammalian cells and (2) provide a mechanism for reporter gene expression in magnetic resonance imaging (MRI). There are two main components to the magnetosome: the biomineral and the lipid bilayer that surrounds it. Both are essential for magnetotaxis in a variety of magnetotactic bacteria, but nonessential for cell survival. Through comparative genome analysis, a subset of genes characteristic of the magnetotactic phenotype has been found both within and outside a magnetosome genomic island. The functions of magnetosome‐associated proteins reflect the complex nature of this intracellular structure and include vesicle formation, cytoskeletal attachment, iron transport, and crystallization. Examination of magnetosome genes and structure indicates a protein‐directed and stepwise assembly of the magnetosome compartment. Attachment of magnetosomes along a cytoskeletal filament aligns the magnetic particles such that the cell may be propelled along an external magnetic field. Interest in this form of magnetotaxis has prompted research in several areas of medicine, including magnetotactic bacterial targeting of tumors, MR‐guided movement of magnetosome‐bearing cells through vessels and molecular imaging of mammalian cells using MRI, and its hybrid modalities. The potential adaptation of magnetosome genes for noninvasive medical imaging provides new opportunities for development of reporter gene expression for MRI. WIREs Nanomed Nanobiotechnol 2012, 4:378–388. doi: 10.1002/wnan.1165This article is categorized under:

Diagnostic Tools > Diagnostic Nanodevices
Diagnostic Tools > In Vivo Nanodiagnostics and Imaging