bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinematics of the ribbon fin in hovering and swimming of the electric ghost knifefish
Authors: Ruiz-Torres Ricardo , Curet Oscar M. , Lauder George V. , MacIver Malcolm A.
Published: November 2012

Weakly electric knifefish are exceptionally maneuverable swimmers. In prior work, we have shown that they are able to move their entire body omnidirectionally so that they can rapidly reach prey up to several centimeters away. Consequently, in addition to being a focus of efforts to understand the neural basis of sensory signal processing in vertebrates, knifefish are increasingly the subject of biomechanical analysis to understand the coupling of signal acquisition and biomechanics. Here, we focus on a key subset of the knifefish's omnidirectional mechanical abilities: hovering in place, and swimming forward at variable speed. Using high speed video and a markerless motion capture system to capture fin position, we show that hovering is achieved by generating two traveling waves, one from the caudal edge of the fin, and one from the rostral edge, moving toward each other. These two traveling waves overlap at a nodal point near the center of the fin, cancelling fore-aft propulsion. During forward swimming at low velocities, the caudal region of the fin continues to have counter-propagating waves, directly retarding forward movement. The gait transition from hovering to forward swimming is accompanied by a shift in the nodal point toward the caudal end of the fin. While frequency varies significantly to increase speed at low velocities, beyond about one body length per second, the frequency stays near 10~Hz, and amplitude modulation becomes more prominent despite its higher energetic costs. A coupled central pattern generator model is able to reproduce qualitative features of fin motion and suggest hypotheses regarding the fin's neural control.
Photo-orientation regulates seasonal habitat selection in the two-spotted spider miteTetranychus urticae
Authors: Suzuki Takeshi , Kojima Takeshi , Takeda Makio , Sakuma Masayuki
Published: November 2012

Non-diapausing spider mites (Tetranychus urticae) live on the undersurface of host leaves during summer, but diapausing mites overwinter in dark hibernacula. The light environments of these habitats would differ: visible radiation (VIS) but not ultraviolet radiation (UV) would reach the undersurface, but neither would enter dark hibernacula. Thus, mites of either seasonal form could locate their preferred habitat by photo-orientation responses to UV and VIS. To investigate this possibility, we analysed the mites’ locomotion behaviour on a virtual field with a programmed chequered pattern of light and dark patches in a micro-locomotion compensator. Both non-diapausing and diapausing mites moved away from UV-illuminated patches into dark patches. Non-diapausing mites moved towards VIS-illuminated patches, whereas diapausing mites did not show a preference. Our results show that non-diapausing mites avoid UV and are attracted to VIS, suggesting that this can guide them beneath a leaf. Diapausing mites simply avoid UV. The lack of preference for VIS during diapause could be due to changes in carotenoid metabolism, which also involve orange pigmentation of diapausing mites. We consider that a diapause-mediated switch of the response to VIS, together with regular avoidance of UV, plays a key role in the seasonal change of habitat selection in this species. This seasonal polyphenism involves alterations not only in reproductive state and pigmentation, but also in photo-spectral responses.
Nitric oxide signaling differentially affects habitat choice by two larval morphs of the sea slugAlderia willowi: mechanistic insight into evolutionary transitions in dispersal strategies.
Authors: Romero Melissa R. , Phuong Mark A. , Bishop Cory D. , Krug Patrick J.
Published: November 2012

In many marine animals, adult habitat is selected by lecithotrophic (non-feeding) larvae with a limited lifespan. In generalist species, larvae may increasingly accept sub-optimal habitat over time as energy stores are depleted (‘desperate larva’ hypothesis). If the fitness cost of suboptimal habitat is too high, larvae of specialists may prolong the searching phase until encountering a high-quality patch or dying (‘death before dishonor’ hypothesis). In generalists, starvation is hypothesized to lead to a decline in inhibitory nitric oxide (NO) signaling, thereby triggering metamorphosis. Here, we document alternative functions for identified signaling pathways in larvae having ‘desperate’ versus ‘death before dishonor’ strategies in lecithotrophic clutches of a habitat specialist, the sea slug Alderia willowi. In an unusual dimorphism, each clutch of A. willowi hatches both non-selective larvae that settle soon after hatching, and siblings that delay settlement in the absence of cues from the alga Vaucheria, the sole adult food. Phamacological manipulation of NO signaling induced metamorphosis in non-selective but not selective stages. However, decreased NO signaling in selective larvae lowered the threshold for response to habitat cues, mimicking the effect of declining energy levels. Manipulation of cGMP or dopamine production induced metamorphosis in selective and non-selective larvae alike, highlighting a distinct role for the NO pathway in the two larval morphs. We propose a model in which NO production (i) links nitrogen metabolism with sensory receptor signaling, and (ii) shifts from a regulatory role in ‘desperate larva’ strategies to a modulatory role in ‘death-before-dishonor’ strategies. This study provides new mechanistic insight into how the function of conserved signaling pathways may change in response to selection on larval habitat choice behaviors.
Utilization of Carboxylated 1,3-Indandione as an Electron Acceptor in Dye-Sensitized Solar Cells
Authors: Matsumoto Shoji , Aoki Tatsuro , Suzuki Tasutaka , Akazome Motohiro , Betto Atsushi , Suda Yasumasa
Published: November 2012

The performance of dyes containing carboxylated 1,3-indandiones as electron acceptors was examined. The compounds that included a monocarboxylic group on the 1,3-indandione moiety showed good overall power conversion efficiencies (ca. 2.38%), the values of which were comparable to those of cyanoacrylate derivatives with the same donor–π-linker structure.
Synthesis and Characterization of 2,3,9,10-Tetradendronized Pentacene
Authors: Tajima Tomoyuki , Yamakawa Akio , Fukuda Keitaro , Hayashi Yuuki , Nakano Masahiko , Takaguchi Yutaka
Published: November 2012

A new pentacene dendrimer was synthesized in 81% yield through the aromatization of a dihydropentacene derivative having benzyl ether dendrons at the C2, C3, C9, and C10 positions. The dendrimer is very soluble in various organic solvents such as toluene, benzene, chloroform, dichloromethane, acetone, and ethyl acetate. The half-life of the dendrimer reaches 22.4 min upon photoirradiation in air. Interestingly, regiospecific [4 + 2] cycloaddition reactions proceeded at the central ring of the pentacene.
Carbon Dioxide-promoted Selective Reductive Amination of Aliphatic Ketones with Aniline and Hydrogen Using a Pt/C Catalyst
Authors: Ichikawa Shinichiro , Seki Tsunetake , Ikariya Takao
Published: November 2012

Product selectivity in the reductive amination of aliphatic ketones with aniline and H2 using a 5% Pt/C catalyst was improved remarkably in the presence of CO2. The CO formed in situ by the reverse water–gas shift reaction selectively poisoned the Pt sites active for undesired side reactions.
3D-ordered Nanoporous LiMPO4 (M = Fe, Mn)–Carbon Composites with Excellent Charging–Discharging Rate-capability
Authors: Moriguchi Isamu , Nabeyoshi Shohei , Izumi Mayato , Yamada Hirotoshi
Published: November 2012

Highly ordered and three-dimensionally interconnected nanoporous materials, constructed with a nanothick wall of LiMPO4 (M = Fe, Mn) and a carbon (C) nanocomposite, were successfully synthesized by a colloidal crystal-template process. It was demonstrated for the first time that the ordered nanoporous composites show excellent rate capability not only for LiFePO4 but also for LiMnPO4.
Synthesis and Characterization of Reduction-responsive Cyclophane Dimer Based on Disulfide Linkage
Authors: Hayashida Osamu , Ichimura Kazuaki
Published: November 2012

Reduction-responsive cyclophane dimer having a disulfide linkage was synthesized. The host showed enhanced guest binding affinity relative to that by monocyclic cyclophane, as confirmed by fluorescence spectroscopy. Reduction of the disulfide bond of the host by dithiothreitol gave monocyclic cyclophanes having less guest-binding affinity.
Revenue Sharing in Airline Alliances
Authors: Hu Xing , Caldentey René , Vulcano Gustavo
Published: November 2012

We propose a two-stage game-theoretic approach to study the operations of an airline alliance in which independent carriers, managing different reservation and information systems, can collaboratively market and operate codeshare and interline itineraries. In the first-stage game, airlines negotiate fixed proration rates to share the revenues generated by such itineraries. In the second-stage game, airlines operate independent inventory control systems to maximize their own expected revenues. We derive a revenue-sharing rule that is (i) an admissible outcome of the first-stage negotiation, in the sense that no airline coalition has enough incentives to secede from the grand alliance, and (ii) efficient for the second-stage game, in the sense that the decentralized system can achieve the same revenues as a central planner managing the global alliance network. Our numerical study shows that the proposed proration rates can lead to a significant increase in revenues with respect to other rules commonly used in practice. Finally, because our proposal requires the disclosure of private demand information, we introduce a simple alternative rule that is based on public information. This heuristic performs remarkably well, becoming an interesting candidate to be pursued in practice.

This paper was accepted by Martin Lariviere, operations management.
On Boundedness of Q-Learning Iterates for Stochastic Shortest Path Problems
Authors: Yu Huizhen , Bertsekas Dimitri P.
Published: November 2012

We consider a totally asynchronous stochastic approximation algorithm, Q-learning, for solving finite space stochastic shortest path (SSP) problems, which are undiscounted, total cost Markov decision processes with an absorbing and cost-free state. For the most commonly used SSP models, existing convergence proofs assume that the sequence of Q-learning iterates is bounded with probability one, or some other condition that guarantees boundedness. We prove that the sequence of iterates is naturally bounded with probability one, thus furnishing the boundedness condition in the convergence proof by Tsitsiklis [Tsitsiklis JN (1994) Asynchronous stochastic approximation and Q-learning. Machine Learn. 16:185–202] and establishing completely the convergence of Q-learning for these SSP models.
Long-term skeletal consequences of childhood acute lymphoblastic leukemia in adult males: a cohort study
Authors: Mäkitie O , Heikkinen R , Toiviainen-Salo S , Henriksson M , Puukko-Viertomies L-R , Jahnukainen K
Published: November 2012

Objective

Long-term health sequelae of childhood-onset acute lymphoblastic leukemia (ALL) remain largely unknown. Low bone mineral content (BMC) and bone mineral density (BMD) are recognized complications, but it is unknown whether these persist until adulthood. We evaluated skeletal characteristics and their association with ALL therapy in long-term male ALL survivors.

Design

This cross-sectional cohort study included 49 long-term male ALL survivors and 55 age-matched healthy males.

Methods

BMD and compression fractures were assessed by dual-energy X-ray absorptiometry; blood biochemistry was obtained for parameters of calcium homeostasis.

Results

The ALL survivors (median age 29 years, range 25–38 years), assessed 10–38 years after ALL diagnosis, had lower lumbar spine (P<0.001), femoral neck (P<0.001), and whole-body (P=0.017) BMD than expected based on normative values. When compared with the controls (median age 30 years, range 24–36 years), the ALL survivors had lower lumbar spine BMC (P=0.014), lower whole-body BMC (P<0.001), and lower whole-body BMD (P<0.001), but the differences were partly explained by differences in height. Altogether, 20% of the ALL survivors had spinal compression fractures, but these were equally prevalent in the controls. Males diagnosed with ALL before age 5 years had significantly lower BMD values. Other recognized risk factors included untreated hypogonadism, vitamin D deficiency, hypophosphatemia, low IGF-binding protein-3, and low physical activity.

Conclusions

At young adulthood, long-term male ALL survivors have significantly reduced BMC and BMD and a high prevalence of spinal compression fractures. Careful follow-up and active treatment of the recognized risk factors are warranted.
Pathology of Congenital Heart Disease
Authors: Balakrishnan Preetha L. , Juraszek Amy L.
Published: November 2012

Tremendous gains have been made in recent years in the diagnosis and management of congenital heart malformations. Recognition of cardiac pathology is an imperative first step in the treatment of the newborn infant with critical congenital heart disease. This review will focus on the following: (1) a description of the forms of critical neonatal heart disease, including left heart obstructive lesions and pulmonary blood flow obstructive lesions and (2) a review of the clinical symptoms of ductal-dependent left heart obstructive lesions. This summary is limited to those conditions that present early in the neonatal period and require prompt intervention. Identification of affected infants before discharge and prompt initiation of prostaglandin therapy is life-saving in this population.
Isolation of lipase producing thermophilic bacteria: Optimization of production and reaction conditions for lipase from Geobacillus sp.
Authors: Mehta Akshita , Kumar Rakesh , Gupta Reena
Published: November 2012

Lipases catalyze the hydrolysis and the synthesis of esters formed from glycerol and long chain fatty acids. Lipases occur widely in nature, but only microbial lipases are commercially significant. In the present study, thirty-two bacterial strains, isolated from soil sample of a hot spring were screened for lipase production. The strain TS-4, which gave maximum activity, was identified as Geobacillus sp. at MTCC, IMTECH, Chandigarh. The isolated lipase producing bacteria were grown on minimal salt medium containing olive oil. Maximal quantities of lipase were produced when 30 h old inoculum was used at 10% (v/v) in production medium and incubated in shaking conditions (150 rpm) for 72 h. The optimal temperature and pH for the bacterial growth and lipase production were found to be 60°C and 9.5, respectively. Maximal enzyme production resulted when mustard oil was used as carbon source and yeast extract as sole nitrogen source at a concentration of 1% (v/v) and 0.15% (w/v), respectively. The different optimized reaction parameters were temperature 65°C, pH 8.5, incubation time 10 min and substrate p-nitrophenyl palmitate. The Km and Vmax values of enzyme were found to be 14 mM and 17.86 μmol ml−1min−1, respectively, with p-nitrophenyl palmitate as substrate. All metal ions studied (1 mM) increased the lipase activity.
Immune responses against chimeric DNA and protein vaccines composed of plpEN-OmpH and PlpEC-OmpH from Pasteurella multocida A:3 in mice
Authors: Okay Sezer , Özcengiz Erkan , Özcengiz Gülay
Published: November 2012

Pasteurella multocida is a pathogenic bacterium causing many diseases that are of significant economic importance to livestock industries. Outer membrane protein H (ompH) gene and two fragments of Pasteurella lipoprotein E (plpE) gene, namely plpEN and plpEC, were cloned from P. multocida A:3. Three DNA vaccine formulations, namely pCMV-ompH, pCMV-plpEN-ompH and pCMV-plpEC-ompH and two protein-based prototype vaccines, alum adjuvanted PlpEN-OmpH and PlpEC-OmpH, were generated. Antibody levels were induced in mice vaccinated with chimeric DNA or protein vaccines. A significant (p < 0.05) increase in serum IFN-g titer was obtained by vaccination with 100 μg of pCMV-ompH, pCMV-plpEC-ompH and PlpEC-OmpH. DNA vaccines did not provide protection upon intraperitoneal challenge with 10 LD50 of live P. multocida A:3. However, 40% protection was conferred by 100 μg of PlpEC-OmpH which was not statistically significant. These results showed that plpEN-ompH and plpEC-ompH chimeric DNA vaccines and alum adjuvanted PlpEN-OmpH or PlpEC-OmpH protein vaccines were immunogenic but not protective against P. multocida A:3 in mice. Prime-boost strategies, i.e. priming with DNA vaccines and boost with protein formulations or different adjuvants can be utilized to obtain significant protection.
Hardening Mechanism through Phase Separation of Beta Ti-35Nb-7Zr-5Ta and Ti-35Nb-7Ta Alloys
Authors: Afonso C. R. M. , Ferrandini P. L. , Caram R.
Published: November 2012

The β titanium alloys are highly attractive metallic materials for biomedical applications due to their high specific strength, high corrosion resistance and excellent biocompatibility, including low elastic modulus. The aim of this work is the evaluation of hardening mechanism through phase separation in β Ti-35Nb-7Zr-5Ta (TNZT) and Ti-35Nb-7Ta (TNT) alloys. Ingots (50 g) of TNZT and TNT alloys were arc-furnace melted in Ar(g)atmosphere. XRD using synchrotron radiation together with TEM and HRTEM analysis showed the coexistence of two separated phases (β and β’) with similar crystalline structures and slightly different lattice parameters in TNZT and TNT alloys. It was detected a heterogeneous microstructure alternating nanosized dark and bright regions (∼10 nm) with different compositions (Nb-rich β and Ta-Zr-rich β’).In aged condition (400ºC/4h), TNZT and TNT alloys undergoes coherent spinodal decomposition of β phase into two solid solution phases with coherent interface, different compositions and elastic strain associated with nanometric domains of Nb-rich β and Ta-(Zr)-rich β’ phases.
Arabinoxylans Gels as Lycopene Carriers: in vitro Degradation by Colonic Bacteria
Authors: Rascón-Chu A. , Martínez-López A. L. , Berlanga-Reyes C. , Carvajal-Millan E. , Campa-Mada A. C. , Gardea A. A. , Orozco-Avitia A.
Published: November 2012

Arabinoxylans are polysaccharides constituted of a linear backbone of xylose in which arabinose substituents are attached, some ferulic acid esterifies arabinose. Arabinoxylan can form covalent gels by oxidative coupling of ferulic acid. Arabinoxylan gels could have potential applications for colon-specific biomolecules delivery due to their macroporous structure, and their aqueous environment and their dietary fiber nature. Lycopene has received increasing attention for its possible role in the prevention of colon cancer. It has been previously reported that arabinoxylan gels could be formed in presence of lycopene with no detriment on the lycopene antioxidant activity. The objective of this research was to investigate the in vitro degradation of arabinoxylan gels (AX gels) by two human colon bacterial species (Bacteroides ovatus and Bifidobacterium longum). Bacterial counts (CFU ml-1) and metabolic heat production (p) followed a similar pattern with a high response during the first 24 h at 37 °C. A regression model related CFU ml-1 and p (r2= 0.98). These results show that AX gels could be carriers for lycopene delivery in colon due structure degradation by gut microbiota.
Scaffolds of Collagen from Nukbone ®
Authors: León Benjamín H. , Araiza Miguel A. , Piña M. Cristina
Published: November 2012

The scaffold is obtained from acellular bovine bone: Nukbone® (produced by Biocriss SAPI de CV). This acellular bone was subjected to a demineralization process after which the composition was found to be 10% water, 65% of collagen and 25% of hydroxyapatite. The techniques used to characterize these natural scaffolds were: optical microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, thermo gravimetric analysis, differential scanning calorimetry and determination of pore size using nitrogen adsorption, and physical adsorption of N2. The pore size is between 100 and 500 microns. These scaffolds have been tested in several biological tissues as urethra, trachea, blood vessels, bone and heart successfully.
Lubricin as a Surface Treatment to Reduce Post-operative Biofouling and Infection
Authors: Aninwene George E. , Hall Doug , Mei Amy , Jay Gregory D. , Webster Thomas J.
Published: November 2012

The goal of this research was to investigate the ability of lubricin to prevent bio-fouling of intraocular lenses after surgery, through surface coating trials with lubricin and analogues of the two major sub-units of the lubricin molecule (mucin and vitronectin). Yearly, there are over 6 million surgeries worldwide that involve intraocular lenses (IOLs) 1. However, preventing post-operative biofouling and bacterial infection of these implants remains a challenge 2. Surface modification of IOLs may provide a solution. This study proposes the use of the anti-adhesive protein lubricin (LUB), a glycoprotein found in the synovial fluid, as a means to make polymer surfaces less prone to bacterial adhesion and proliferation; thus, reducing the opportunity for post-operative infection 3. This study used extended bacteria growth trials on tissue cultures polystyrene coated with either lubricin, vitronectin, or mucin to investigate how lubricin and protein sub-regions of lubricin may reduce bacterial adhesion and proliferation.
The Pozzolanic Reaction of Silica Fume
Authors: Jensen Ole M.
Published: November 2012

Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy of activation of the pozzolanic reaction of silica fume is estimated. The results show that the pozzolanic reaction of silica fume has notable differences from Portland cement hydration.
The Importance of Portland cement Composition to Mitigate Sewage Collection Systems Damage
Authors: Rendon Luis Emilio , Lara Maria Eugenia , Rendon Montserrat
Published: November 2012

The damage that the products of microorganism metabolism, in particular biogenic sulfuric acid, do to hardened concrete is known as concrete biodeterioration. These microorganisms, Acidithiobacillus thiooxidans, Acidithiobacillus ferrooxidans and sulfate-reducing bacteria (SRB) are ubiquitous in the environment and they produce either hydrogen sulfide or sulfuric acid that can dissolve and disintegrate the concrete matrix. Their activity plays a very important function in the whole spectrum of degradation processes such as corrosion of reinforced metals and concrete.

In Canada and in the northern part of the United States, concrete structure failures from concrete biodeterioration are less common than in the southern part of the United States and in Mexico, nevertheless, it is a serious and expensive problem in hydraulic structures and sewage collection systems, which rapidly deteriorate. Also, leaking sewage systems result in the loss of groundwater resources particularly important in this arid region. Almost every city in the Mexican-American border region, who’s combined population is more than 15 million people, faces this problem. The U.S. cities have made some provision to face these concrete structure problems, but the Mexican cities have made less effort. Additives and admixtures are used to improve the properties of the concrete; nonetheless, we have exposed here the importance of the factual composition of the Portland cement and concrete to mitigate concrete biodeterioration in the hydraulic structures and sewage collection systems.
The Effect of Slag and Limestone Filler on Resistivity, Sorptivity, and Permeability of Concrete with Low Paste Content
Authors: Villagrán Zaccardi Yury A. , Di Maio Ángel A. , Romagnoli Roberto
Published: November 2012

This paper deals with several concrete properties and to what extent they are influenced by slag and limestone filler, either one or both of them are included. Concrete was designed for low paste content, this is, a water reducing admixture (WR) was used to limit mixing water content. The results are compared with concrete made with commercial composite cement, blended during milling. Concrete was tested for compressive strength, sorptivity, resistivity, and water penetration under pressure. The volume of paste in all concrete mixes was the same.

Results showed the effect of slag on concrete transport properties. The effect of limestone filler was minimal either admixed solely or in conjunction with slag. On the other hand, blended cement appeared to be less effective on improving concrete transport properties. Compressive strength was less affected than transport properties by slag inclusion.
Polycrystalline Silicon Thin Film Formed By Multiple Pulsed Rapid Thermal Annealing – Intrinsic a-Si Film Thickness Effect
Authors: Kuo Yue , Lin Chi-Chou
Published: November 2012

The polycrystalline n+/intrinsic silicon thin film stacks with various original intrinsic amorphous silicon layer thicknesses were formed using the multiple pulsed rapid thermal annealing process with the Ni-induced crystallization mechanism. The thick polycrystalline silicon stack was prepared by repeated steps of 1) amorphous silicon thin film deposition, 2) solution oxidation, 3) dehydrogenation, 4) pulsed rapid thermal annealing, and 5) oxide stripping. The poly-Si film properties, such as the grain size, orientation, and volume fraction of the crystalline phase, were related to the original intrinsic silicon film thickness and the total thermal budget. This process is effective in preparing the high volume fraction polycrystalline silicon thin film, which is important for low-cost thin-film solar cells, electronic and optoelectronic devices.
Modeling and Experimental Study of SiH4/GeH4/H2 Gas Discharge for Hydrogenated Silicon Germanium Deposition by RF PECVD
Authors: Zhao Lai , Hunsperger Robert , Hegedus Steven
Published: November 2012

A one-dimensional model has been developed for radio frequency (RF) glow discharge of SiH4/GeH4/H2 3-gases mixture at a high pressure regime based on the fluid model. The behavior of electrons, neutrals, radicals and ions with corresponding rate constants is described by driftdiffusion equations that are coupled with the Poisson’s equation and solved with an explicit central-difference discretization scheme. The germanium (Ge) content in the deposited film and germane (GeH4) radical fraction in the gas phase are found to decrease as total gas pressure increases in contrast to the increased deposition rate, which are explained by the fact that GeHx-group species are more thoroughly depleted and less promoted by the denser plasma at high pressure compared to SiHx-group species. The multiplied population of electrons and hydrogen atoms in the quadratically denser plasma also boosts secondary reactions which are favorable for SiH3 and GeH3 and consume SiH2 and GeH2for high order radicals.
Diffuse Reflectance and Absorption Characteriation of a Plasmonic Back Reflector for Application in Thin Film Si Solar Cells
Authors: Sesuraj R.S.A. , Temple T. L. , Bagnall D.M.
Published: November 2012

A plasmonic back reflector has been fabricated for light-trapping application in thin film Si photovoltaic devices. The back reflector comprises of a 2D array of self-organized Ag NPs separated from a planar Ag mirror by a ZnO layer deposited by atomic-layer deposition. The diffuse reflectance and parasitic absorption losses can be modulated by varying the ZnO thickness. A maximum diffuse reflectance peak value of 30% at 950 nm, with a bandwidth of 400nm, is observed for ∼100 nm diameter NPs at a distance of 50 nm from the Ag mirror. Finite-difference time-domain simulations of a 100nm Ag sphere near a mirror were used to understand the experimentally observed trends in diffuse reflectance and parasitic absorption, with distance from the mirror. Particles very close to the mirror can couple to delocalized surface plasmons or exhibit Fano resonance effects, thereby increasing parasitic absorption. Particles situated away from the mirror are influenced by driving-field effects due to the interaction of incident and reflected photons, which modulate the scattering cross-section.
Light Induced Changes in PIN Solar Cells: Beyond the Staebler-Wronski Effect
Authors: Kim Ka-Hyun , Johnson Erik V. , Kasouit Samir , Roca i Cabarrocas Pere
Published: November 2012

Hydrogenated polymorphous silicon (pm-Si:H) is one of the most promising candidates for a stable top cell material in multi-junction thin film solar cells. Solar cells using pm-Si:H as their absorbing layer show very interesting degradation kinetics when compared to hydrogenated amorphous silicon (a-Si:H), summarized by macroscopic structural changes and irreversible changes in solar cell characteristics, while nevertheless preserving a higher stabilized efficiency. Notably, pm-Si:H solar cells, once degraded, respond to neither annealing nor further light-soaking. Such results suggest a device degradation mechanism including structural changes, active hydrogen motion, and interface delamination mediated by fast hydrogen diffusion and accumulation at the interface. Interestingly, a similar behavior was reported for a-Si:H solar cells under severe light soaking conditions (at 350 °C or under 50 suns) while pm-Si:H solar cells show such behavior under 1 sun at 40 °C.
Artificial Photosynthesis - Use of a Ferroelectric Photocatalyst
Authors: Dunn Steve , Stock Matt
Published: November 2012

The solid-gas phase photoassisted reduction of carbon dioxide (artificial photosynthesis) was performed using ferroelectric lithium niobate and titanium dioxide as photocatalysts. Illumination with a high pressure mercury lamp and visible sunlight showed lithium niobate achieved unexpectedly high conversion of CO2 to products despite the low levels of band gap light available and outperformed titanium dioxide under the conditions used. The high reaction efficiency of lithium niobate is explained due to its strong remnant polarization (70 μC/cm2) thought to allow longer lifetime of photo induced carriers as well as an alternative reaction pathway.
Stimulating living cells with air DBD plasma
Authors: Favia P. , Pignatelli D. , Dilecce G. , Pistillo B. R. , Nardulli M. , Gristina R.
Published: November 2012

Cells positioned at the bottom of a Petri dish were exposed, in a home-made plasma source, to pulsed Dielectric Barrier Discharges operated in air in order to investigate the effect of the plasma species on their viability and growth. Processes with different number of pulse, respectively 1,3,9 and 27 pulse, were performed to study the influence on viability and cell growth of two different cell lines, Saos 2 and NHDF. Atmospheric air discharges applied on the two selected cell lines have shown an effect strongly dependent on cell type. At certain doses we have measured increased activity of the NHDF fibroblasts cell line. On the other side, an inhibition of cell adhesion and growth on the Saos 2 osteoblastoma cell line, directly dependent on the plasma doses, was clear. This study shows that by properly tuning the dose of exposure of cells to air plasma it is possible to induce both positive and negative effects on cell growth, that would be useful in several branches of Medicine.
Degradation of Influenza Virus Nucleoprotein by N2 Gas Plasma
Authors: Sakudo A , Hayashi N , Shimizu N , Imanishi Y , Shintani H
Published: November 2012

Using a N2 gas plasma apparatus (BLP-TES, NGK Insulators, Ltd), we showed that N2 gas plasma treatment of influenza A virus caused degradation of viral nucleoproteins. These findings suggest that N2 gas plasma treatment may contribute to infection prevention control for influenza.
An Algorithm for Finding Optimized Interface Morphologies in Thin Film Silicon Solar Cells
Authors: Jäger K. , Fischer M. , van Swaaij R.A.C.M.M. , Zeman M.
Published: November 2012

We recently developed a scattering model based on the scalar scattering theory. In this contribution we present how we used the scattering model to investigate interface textures with optimized scattering properties. We used the simulated annealing algorithm to find optimized surface textures and applied the ASA device simulator to evaluate the influence of these optimized textures on the performance of thin film silicon solar cells. We found that the lateral feature size of the textures is crucial for efficient scattering of the incident light.
The Optical Analysis and Application of Size-controllable Si Quantum Dots Fabricated by Multi-hollow Discharge Plasma Chemical Vapor Deposition
Authors: Seo Hyunwoong , Wang Yuting , Uchida Giichiro , Kamataki Kunihiro , Itagaki Naho , Koga Kazunori , Shiratani Masaharu
Published: November 2012

Quantum dot-sensitized solar cells (QDSCs) based on the multiple exciton generation (MEG) of QD are attractive in the field of photochemical cells because the improvement of conventional sensitized solar cells has been stagnant recently. The distinctive characteristics of QDs are their strong photo-response in the visible region and quantum confinement effects. Its theoretical efficiency is much higher than that of solar cell based on the single exciton generation (SEG). Moreover, QDs have tunable optical properties and band-gaps depending on the particle size. But QD materials widely used for QDSC have some disadvantages of toxicity and scarcity. On the other hand, Si as one of good QD materials is abundant and not toxic. Also, Si QD has high stability against light soaking and a high optical absorption coefficient due to quantum size effects. However, the research on Si QD is rare although the quantum effect of Si was already verified. It is one of reasons that the fabrication and collection of Si nano-particles are too difficult. Therefore, this work proposed multi-hollow plasma discharge chemical vapor deposition (CVD). It is possible to collect Si particles unlike conventional CVD and solve the problems of the wet process. The optical properties of Si particles were controlled by varying experimental conditions. In this work, Si particles were fabricated with various sizes and their characteristics were analyzed. Based on the results, Si QD was applied to Si QDSC.
Electron Spin Resonance (ESR) Observation of Radicals on Biological Organism Interacted with Plasmas
Authors: Ishikawa Kenji , Moriyama Hiroko , Tamiya Kazuhiro , Hashizume Hiroshi , Ohta Takayuki , Ito Masafumi , Iseki Sachiko , Tanaka Hiromasa , Takeda Keigo , Kondo Hiroki , Sekine Makoto , Hori Masaru
Published: November 2012

We report the kinetic analysis of radicals on fungal spores of Penicillium digitatum interacted with charged-neutral oxygen species (O*) generated plasma discharge using real time in situ electron spin resonance (ESR) measurements. The ESR signal from the spores was observed at a g-value of around 2.004 with a line width of approximately 5G. We have successfully obtained information regarding the reaction mechanism with free radicals and realtime in situ ESR has proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens
A multi-institution collaborative approach to a productive undergraduate research program in material science
Authors: Silversmith A.J. , Boye D.M. , Hoffman K.R.
Published: November 2012

We describe our approach to a student-centered interdisciplinary research program in material science. Our work in the synthesis and optical characterization of sol-gel materials provides an ideal research setting for undergraduates interested in physics and chemistry. Students fabricate all samples and perform laser spectroscopic measurements. The work is accessible to undergraduates but also of current interest to a wide community of scientists interested in new rare earth based optical materials. Students make meaningful contributions to publishable work, and many go on to do graduate work in physics or chemistry. Two recent students have been recognized with national awards for their research, and many have presented work at international meetings.
Preparation and Characterization of Platinum/Ceria-based Catalysts for Methanol Electro-oxidation in Alkaline Medium
Authors: Menéndez Christian L. , Mayol Ana-Rita , Cabrera Carlos R.
Published: November 2012

Platinum/Cerium oxide-based catalysts for methanol electro oxidation were prepared by the occlusion deposition technique. Composite glassy carbon (GC) electrodes were modified and then tested towards the methanol electro oxidation half reaction in acid and alkaline medium. Cyclic voltammetry and chronoamperometry techniques were used to test the catalytic response of the composite electrodes. AFM studies were carried out in order to have a measurement of the particle size and distribution of the platinum/ceria catalyst on HOPG.
An Improved In-line Inkjet Printing Process for 3D Multilayer Passive Devices
Authors: Yakoub A. , Saadaoui M. , Cauchois R. , Li J-M. , Benaben P.
Published: November 2012

This paper describes an in-line process for the realization of 3D electronic components on A4 format substrate by piezo inkjet printing. This process is developed within a semi-industrial prototype system named “JETPAC”. JETPAC includes an oxygen plasma torch for surface preparation and post-process modules as a variable frequency microwave oven and an UV lamp for metal selective sintering and dielectric ink curing, respectively. JETPAC is used to achieve passive components by chaining conductor and dielectric layers on kapton® substrate: silver nanoparticles based ink is used to print conductors. For multilayer component elaboration, the metal ink is deposited both on kapton® and on printed dielectric materials. Due to a low surface energy (S.E) of the printed dielectric, the realization of efficient silver tracks is compromised. A special process combines O2 plasma treatment and UV exposure before printing, allowing the reaching of S.E. value on dielectric near the optimum one (55mN/m). This pre-process allows printing of well-defined conductive structures on top of the dielectric. In-line sintering of printed structures is then performed using variable frequency microwave source. The process allows the elaboration of multilayer structures including stacked resistors and capacitors. These results make the developed process very promising for the realization by inkjet printing of passive devices for smart tag applications.
Fecundity of Japanese Barberry (Berberis thunbergii) Cultivars and Their Ability to Invade a Deciduous Woodland
Authors: Brand Mark H. , Lehrer Jonathan M. , Lubell Jessica D.
Published: November 2012

Japanese barberry is an important landscape shrub that has a demonstrated potential to be invasive in ∼30 states across the central and northern United States. Forty-six cultivars were evaluated for their potential to produce fruits and seeds in a randomized, replicated field planting. Seeds from a subset of cultivars were evaluated for their ability to germinate and survive as seedlings in a deciduous woodland. Seed production for cultivars varied from no seeds to more than 12,000 seeds plant−1and the number of seeds per fruit ranged from 0.1 to 1.8. Five cultivars produced fewer than 100 seeds plant−1, and two cultivars failed to produce fruit. When plants were allowed to mature for 4 to 5 yr beyond the first evaluation time, cultivars exhibited significant increases in fruits per plant, producing as much as 35,000 fruits plant−1(‘Sparkle’). ‘Golden Devine’ and ‘Red Chief’, fruitless cultivars at the first evaluation, produced 165 and 20 fruit plant−1, respectively, at the follow-up evaluation, demonstrating that long-term evaluation of cultivars is necessary to accurately assess sterility. Between 12.5 and 31% cultivar seed sown in a deciduous woodland germinated, and seedlings survived at rates between 5.6 and 29.3%. Coupling cultivar seed-production data with germination and survival data in a deciduous woodland suggests that even cultivars producing as few as 100 seeds annually have the potential to contribute a few seedlings each year to a natural area.
Briefing: Potential of energy saving partnerships in the UK: an example of Berlin
Authors: Chmutina Ksenia , Goodier Chris I. , Berger Susanne
Published: November 2012

There is significant potential for improving the energy efficiency of the UK's public building stock. This will require, however, significant financial investment by local and national government, which in the current economic climate is very difficult. One way to reduce the energy consumption of public buildings without direct up-front financing is by way of an energy saving partnership (ESP), two examples of which are outlined and compared here: the Berlin Energy Saving Partnership and the London Re:fit programme. Based on these examples and on discussions with UK building retrofit specialists, this paper analyses drivers and barriers for the potential of ESPs in the UK. It emphasises that in order to minimise or prevent potential financial obstacles, strong support, and not just financial support, from local government is required.
Internal imaging of saturated granular free-surface flows
Authors: Sanvitale Nicoletta , Bowman Elisabeth T.
Published: November 2012

This paper presents a novel method to investigate the internal behaviour of saturated granular free-surface flows in the context of high-speed movement. Such an approach aims to study the motion of the solids and fluid within the flow in small-scale model flume tests with a view to better understanding debris flows mechanics. Through the employment of a particular solid, liquid and fluorescent dye and the application of an optical technique that relies on precise matching of refractive indices, the arrangement and re-arrangement of the grains within the fluid can be determined by way of planar laser-induced fluorescence. The adopted methodologies, together with the physical and optical properties of the selected fluid and solid phases, are described. The results of a series of experiments performed in a small laboratory flume are presented. The results show the effectiveness of this technique and the reliability of an artificial glass–oil mixture in reproducing the key features of flows composed of natural materials.
A spatial mark–resight model augmented with telemetry data
Authors: Sollmann Rahel , Gardner Beth , Parsons Arielle W. , Stocking Jessica J. , McClintock Brett T. , Simons Theodore R. , Pollock Kenneth H. , O'Connell Allan F.
Published: November 2012

Abundance and population density are fundamental pieces of information for population ecology and species conservation, but they are difficult to estimate for rare and elusive species. Mark–resight models are popular for estimating population abundance because they are less invasive and expensive than traditional mark–recapture. However, density estimation using mark–resight is difficult because the area sampled must be explicitly defined, historically using ad hoc approaches. We developed a spatial mark–resight model for estimating population density that combines spatial resighting data and telemetry data. Incorporating telemetry data allows us to inform model parameters related to movement and individual location. Our model also allows <100% individual identification of marked individuals. We implemented the model in a Bayesian framework, using a custom‐made Metropolis‐within‐Gibbs Markov chain Monte Carlo algorithm. As an example, we applied this model to a mark–resight study of raccoons (Procyon lotor) on South Core Banks, a barrier island in Cape Lookout National Seashore, North Carolina, USA. We estimated a population of 186.71 ± 14.81 individuals, which translated to a density of 8.29 ± 0.66 individuals/km2 (mean ± SD). The model presented here will have widespread utility in future applications, especially for species that are not naturally marked.
US agricultural nitrous oxide emissions: context, status, and trends
Authors: Cavigelli Michel A , Grosso Stephen J Del , Liebig Mark A , Snyder Clifford S , Fixen Paul E , Venterea Rodney T , Leytem April B , McLain Jean E , Watts Dexter B
Published: November 2012

The use of commercial nitrogen (N) fertilizers has led to enormous increases in US agricultural productivity. However, N losses from agricultural systems have resulted in numerous deleterious environmental impacts, including a continuing increase in atmospheric nitrous oxide (N2O), a greenhouse gas (GHG) and an important catalyst of stratospheric ozone depletion. Although associated with about 7% of total US GHG emissions, agricultural systems account for 75% of total US N2O emissions. Increased productivity in the crop and livestock sectors during the past 30 to 70 years has resulted in decreased N2O emissions per unit of production, but N2O emissions from US agriculture continue to increase at a rate of approximately 0.46 teragrams of carbon dioxide equivalents per year (2002–2009). This rate is lower than that during the late 20th century. Improvements in agricultural productivity alone may be insufficient to lead to reduced emissions; implementing strategies specifically targeted at reducing N2O emissions may therefore be necessary.
Effects of elevated carbon dioxide and increased temperature on methane and nitrous oxide fluxes: evidence from field experiments
Authors: Dijkstra Feike A , Prior Stephen A , Runion G Brett , Torbert H Allen , Tian Hanqin , Lu Chaoqun , Venterea Rodney T
Published: November 2012

Climate change could alter terrestrial ecosystems, which are important sources and sinks of the potent green‐house gases (GHGs) nitrous oxide (N2O) and methane (CH4), in ways that either stimulate or decrease the magnitude and duration of global warming. Using manipulative field experiments, we assessed how N2O and CH4 soil fluxes responded to a rise in atmospheric carbon dioxide (CO2) concentration and to increased air temperature. Nitrous oxide and CH4 responses varied greatly among studied ecosystems. Elevated CO2 often stimulated N2O emissions in fertilized systems and CH4 emissions in wetlands, peatlands, and rice paddy fields; both effects were stronger in clayey soils than in sandy upland soils. Elevated temperature, however, impacted N2O and CH4 emissions inconsistently. Thus, the effects of elevated CO2 concentrations on N2O and CH4 emissions may further enhance global warming, but it remains unclear whether increased temperature generates positive or negative feedbacks on these GHGs in terrestrial ecosystems.