bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Silicon-Based Coating for High Temperature Protection of Metallic Alloys
Authors: Xu J. , Favergeon Jérôme , Mazeran P.E. , Moulin Gérard , Vu C.
Published: September 2011

This contribution presents results which show the possibility to develop protective coatings from perhydropolysilazane (PHPS) on low carbon steel. In order to have an effective protection, the pyrolysis conditions should be carefully controlled. Nanoindentation tests allow characterizing the mechanical resistance of the coating after different pyrolysis conditions. The pyrolysis of coated samples has also been monitored by acoustic emission; the results show that the structural conversion of the coating from polymer to ceramics can be detected by acoustic emission.
Cross-Sectional TEM Characterization of Re-Based Diffusion Barrier on Nb Substrate
Authors: Eni S. , Wang Y. , Hashimoto N. , Ohnuki Somei , Narita Toshio
Published: September 2011

Cross-sectional structures of a Re-based diffusion barrier coating on Nb as ultra high temperature material were investigated in order to verify the crystalline structure and composition of the coated layer. Three types coating specimens were prepared by electroplating Re from an aqueous solution on an Nb substrate, followed by Cr-pack cementation in vacuum. The coating process produced three distinct layers; an outer Cr(Re) layer, an intermediate Re-Cr-Nb layer, and an inner Nb(Re) layer. A crystal structure of Cr(Re) and Nb(Re) layers possess similar single crystal bcc structure. The Re-Cr-Nb layer expected to act as a diffusion barrier between the substrate and the outer reservoir layer was comprised of cubic c phase and hexagonal Laves C14 phase. Moreover, several crystal defects such as dislocations and stacking faults as well as voids and cracks are observed in the coating specimen.
Fabrication of Oxide Nano-Rod Array Structures via Internal Oxidation of Alloys
Authors: Nanko Makoto
Published: September 2011

A simple metallurgical process for fabricating oxide nano-rod array structures via internal oxidation is described. Some dilute alloys such as Ni(Al) and Fe(Al) solid solutions develop rod-like oxide precipitates after their internal oxidation at high-temperatures and under low oxygen partial pressures. The oxide nano-rod array structure can be developed on the metal substrate by removing the metallic matrix of the internal oxidation zone. Al2O3orMAl2O4(M=Ni or Fe) spinel nano-rod array structures were prepared by usingM(Al) solid solutions. Pack cementation process to develop M(Al) solid solution surface layers was used for the fabrication of nano-rod array structures on substrates with desired shape. Near-net shape Ni substrates with oxide nano-rod array structures on their surfaces can be prepared by using pack cementation and internal oxidation.
Oxidation Protection of Titanium Aluminides and Ni-Base Superalloys at High Temperatures by the Halogen Effect – Principles and Applications
Authors: Zschau Hans Eberhard , Schütze Michael
Published: September 2011

The oxidation protection of TiAl-alloys at temperatures above 750°C can be improved by the fluorine effect. The results of thermodynamical calculations predict a corridor for a positive fluorine effect. Ion implantation of F was performed because of giving the best results. After a high F-loss during heating a thin protective alumina scale acts as a diffusion barrier. The F-depth profiles show a distinct maximum at the metal/oxide interface. The diffusion coefficient of F in TiAl for 900°C was determined. The stability of the F-effect after long oxidation time at 900°C and 1000°C can be explained by the existence of a constant F-amount at the metal/oxide interface ensuring a slow growth of the alumina scale. The fluorine effect was also applied to Ni-base superalloys to improve their high temperature oxidation resistance by forming a dense continuous protective alumina scale.
Formation of Ni Aluminide Coating Containing Reactive Elements by Simultaneous Electrodeposition and Cyclic Oxidation Resistance
Authors: Fukumoto Michihisa , Yokota Tsuyoshi , Hara Motoi , Narita Toshio
Published: September 2011

A Ni aluminide layer containing Zr or Hf was formed on a Ni specimen by the simultaneous electrodeposition of Al and Zr or Al and Hf using a molten-salt bath. When the simultaneous electrodeposition of Al and Zr was carried out using molten NaCl-KCl containing 3.5 mol%AlF3 and 0.05 mol%ZrF4, the electrodeposited layers were formed in the order of Ni2Al3, NiAl3 and Al from the Ni substrate side. The ZrAl3 particles were uniformly formed in the surface region of the NiAl3 and Al layers. On the other hand, when the simultaneous electrodeposition of Al and Hf was carried out using molten NaCl-KCl containing 3.5 mol%AlF3 and 0.05 mol%HfF4, the electrodeposited layer consisted of Ni2Al3 as the inner layer and NiAl3 as the outer layer were formed with HfAl3 particles uniformly formed in the surface region of the NiAl3 layer. For the sample treated with the simultaneous electrodeposition of Al and Zr, no significant change in the mass gain was observed during the cyclic-oxidation test at 1423 K, suggesting that the sample had a high cyclic-oxidation resistance. Similarly, the sample treated by the simultaneous electrodeposition of Al and Hf had a high cyclic-oxidation resistance. An adhesive scale, having localized inward penetrations consisting of Al2O3 containing ZrO2 or HfO2, was formed on the samples having the high cyclic-oxidation resistance.
High Temperature Oxidation of TiAl and TiAl8Nb Alloys in Air
Authors: Prazuchi Janusz , Przybylski Kazimierz , Chevalier Sébastien , Brylewski Tomasz
Published: September 2011

Isothermal oxidation of two g-TiAl-based intermetallic alloys: Ti48Al and Ti46Al8Nb alloys was studied in synthetic air at 1073-1223 K for up to 240 hrs. Mass change per unit area for the oxidized samples followed approximately the parabolic rate law. The kp values for the studied temperature interval were in the range from 7.2×10-13 to 1.8×10-11 g2cm-4s-1. The activation energy for oxidation of Ti48Al alloy in air at 1073-1223 K was Ea = 165±12 kJ/mol. Niobium addition to Ti48Al alloy in the amount of 8% increased its oxidation resistance. Structure and chemical composition of the oxidation products, and morphology of the oxidized samples were investigated using XRD, SEM-EDS, and TEM. The oxide scales formed on Ti48Al and Ti46Al8Nb alloys were well adherent to the metallic substrates and exhibited a multilayer structure. Depending on the oxidation temperature and the alloy composition, the scale consisted of variable amounts of TiO2 and Al2O3. Additionally TiN, and niobium rich particles were also identified in the appropriate oxide scale. To understand the growth mechanism of oxide scale formed on Ti46Al8Nb alloy, two stage oxidation experiment was performed using 16O2/18O2, followed by SNMS and TEM-EDS. Particular attention was paid to the use of TEM in order to precisely characterize the reaction products on the Ti46Al8Nb alloy.
The Reactive Element Effect – Past, Present and Future
Authors: Hou Peggy Y.
Published: September 2011

The “reactive element effect”, modified from its earlier representation of the “rare earth effect”, is a well known term within the oxidation community. It describes several beneficial outcomes on the oxidation behavior of alumina and chromia forming alloys. Any element can be considered “reactive” if it is more oxygen active than the scale forming element, namely that of Al or Cr. However, the relative effectiveness of each element can be quite different. Numerous scientific studies have been carried out on this topic since its discovery more than 70 years ago to gain understanding of the manifestations of and reasons for these effects. This paper gives an overview that summarizes current understandings on this effect and points to issues that warrant further studies.
Oxidation Behavior of β-SiAlON in H2O-Containing Atmosphere
Authors: Yamauchi Akira , Yi Xue Mei , Akiyama Tomohiro , Kurokawa Kazuya
Published: September 2011

The oxidation behavior of β-SiAlONs (Si6-zAlzOzN8-z, z = 1, 3, and 4) was investigated at temperature ranging from 1473 to 1673 K in a (N2-3%O2)-20%H2O atmosphere. Oxidation kinetics was followed on the basis of the mass gains, and the oxidized specimens were characterized by FE-SEM, XRD, and EPMA. The mass gain was found to clearly increase with temperature and the z value. For oxidation at 1473 and 1573 K, the gain in mass was observed to be small. During oxidation at 1573 K, mass loss occurred. This loss may be because of the formation of volatile SiO(OH)2. The changes in mass depended on the z value. On the other hand, the oxidation rates at 1673 K were found to be higher than those at and below 1573 K by more than one order of magnitude. The oxidation kinetics at 1673 K followed an almost linear rate law. The XRD and EPMA results showed that the oxide formed on β-SiAlON (z = 1) was composed of a mixture of amorphous aluminosilicate and mullite, whereas that on β-SiAlONs (z = 3 and 4) was composed only of mullite.
Oxidation Properties of Metal/Ceramic Interconnectors for SOFC’s in Air, Ar-H2-H2O and Ar-CH4-H2O Atmospheres
Authors: Przybylski Kazimierz
Published: September 2011

The present paper is a review on the oxidation kinetics, electrical properties, chromium vaporization rate and microstructure investigations of oxide products formed on an uncoated Crofer 22 APU alloy and 1.4762 steel and coated by means of pulsed laser deposition and screen-printing methods with films of (La,Sr)CoO3, (La,Ca)CrO3, (La,Sr)CrO3, (La,Sr)(Co,Fe)O3 and MnCo2O4 in air and Ar-H2-H2O and Ar-CH4-H2O gas mixtures at 1023-1173 K for up to 1200 hrs. Microstructure investigations using SEM-EDS showed the influence of the reaction products formed in different atmospheres at the steel/coating interface on the electrical properties and Cr vaporization rate of these composite materials, which are used for construction of SOFC interconnects.
Manganese-Cobalt Spinel Coating on Alloy Interconnects for SOFCs
Authors: Baba Yoshitaka , Kameda Harukuni , Matsuzaki Yoshio , Yamashita Satoshi , Yasuda Nobutaka , Uehara Toshihiro , Horita Teruhisa , Yamaji Katsuhiko , Yokokawa Harumi
Published: September 2011

Manganese-cobaltite spinel coatings were produced on Fe-Cr alloys for the improvement of the chemical and mechanical stability of solid oxide fuel cell (SOFC) interconnects. It was found by thermal investigation, i.e., the microscopy of various samples that were heat-treated in air at 800 °C, that the screen-printed coating more effectively inhibited oxide scale growth than the sputtered coating. The reason why the manufacturing method of the spinel coating affected the oxide scale growth rate was investigated. It was demonstrated that the oxide scale in both the samples after annealing in air at 800 °C for 5000 h comprised MnCr2O4 and Cr2O3 with no difference in composition. However, the interface between the alloy and the oxide scale was deeper and rougher and had a larger grain size because of the high oxygen diffusivity in the sputtered coating. In contrast, in the screen-printed sample, the dense spinel layer above the oxide scale blocked oxygen diffusion into the alloy, so the oxide scale growth rate was lower and the interface between the alloy and oxide scale remained flat even after thermal treatment. Introducing a reduction treatment in the manufacturing process made the Mn-Co spinel layer denser and further inhibited the oxide scale growth. Moreover, the addition of Li as a sintering aid into the Mn-Co spinel was found to even more effectively inhibit the oxide scale growth.
The Future of Alumina-Forming Alloys: Challenges and Applications for Power Generation
Authors: Pint Bruce A.
Published: September 2011

Alumina-forming alloys have been studied for over 50 years and are now needed for high efficiency power generation applications operating at higher temperatures. Especially in the presence of water vapor, alumina-forming alloys outperform conventional chromia-forming alloys above 1000°C. However, alloy mechanical behavior is a significant issue and alumina-forming alloy development has been limited. The opportunity for alloy development is discussed as well as thefactors that limit oxidation resistance, including alloy thermal expansion and optimizing reactive element additions. Finally, lifetime modeling is discussed for thick section components together with the need to address performance in more complex environments.
The early Stages of the Scale Growth on FeCrAl(+RE)-Type Alumina Formers
Authors: Jedlinski Jerzy , Grosseau-Poussard Jean Luc , Nocuń Marek , Smoła G. , Kowalski Kazimierz , Dąbek J. , Rakowska A. , Bonnet G.
Published: September 2011

The early stages of the scale growth process were studied of two FeCrAl alloys: one synthetic (Fe23Cr5Al) and one commercial (Kanthal APM alloy). In addition, Yttrium was implanted to the Fe23Cr5Al alloy. Oxidation exposures were carried out at 1000°C using two-stage-oxidation exposures in atmospheres containing significantly different amounts of18O2-tracer. The scales were analyzed in terms of SIMS, PLS and SEM. The distribution of oxygen isotopes which corresponded to the location of new oxide formation, the scale phase composition, scale morphology and microstructure were determined which enabled description of the scale evolution on all studied alloys. Similar evolution stages were observed, but minor differences were related to the rate of disappearing of the transient aluminium oxides.
Immunotherapy with Costimulatory Dendritic Cells To Control Autoimmune Inflammation
Authors: O’Sullivan Brendan J. , Pai Saparna , Street Shayna , An Xiayou , MacDonald Kelli P. A. , Wong Michele , Strutton Geoffrey , Gerondakis Steve , Steptoe Raymond J. , Fazekas de St. Groth Barbara , Hill Geoffrey R. , Thomas Ranjeny
Published: September 2011

Costimulation-deficient dendritic cells (DCs) prevent autoimmune disease in mouse models. However, autoimmune-prone mice and humans fail to control expansion of peripheral autoreactive effector memory T cells (TEMs), which resist immunoregulation by costimulation-deficient DCs. In contrast, activation of DC costimulation may be coupled with regulatory capacity. To test whether costimulatory DCs control TEMs and attenuate established autoimmune disease, we used RelB-deficient mice, which have multiorgan inflammation, expanded peripheral autoreactive TEMs, and dysfunctional Foxp3+ regulatory T cells (Tregs) cells and conventional DCs. TEMs were regulated by Foxp3+ Tregs when costimulated by CD3/CD28-coated beads or wild-type DCs but not DCs deficient in RelB or CD80/CD86. After transfer, RelB and CD80/CD86-sufficient DCs restored tolerance and achieved a long-term cure of autoimmune disease through costimulation of TEM and Foxp3+ Treg IFN-γ production, as well as induction of IDO by host APCs. IDO was required for regulation of TEMs and suppression of organ inflammation. Our data challenge the paradigm that costimulation-deficient DCs are required to regulate established autoimmune disease to avoid TEM activation and demonstrate cooperative cross-talk between costimulatory DCs, IFN-γ, and IDO-dependent immune regulation. IFN-γ and IDO activity may be good surrogate biomarkers measured against clinical efficacy in trials of autoimmune disease immunoregulation.
A Comparative Study of Five Mouse Models of Alzheimer′s Disease: Cell Cycle Events Reveal New Insights into Neurons at Risk for Death
Authors: Li Luming , Cheung Timmy , Chen Jianmin , Herrup Karl
Published: September 2011

Ectopic cell cycle events (CCEs) in postmitotic neurons link the neurodegenerative process in human Alzheimer′s disease (AD) with the brain phenotype of transgenic mouse models with known familial AD genes. Most reports on the mouse models use the appearance of brain amyloid pathology as a key outcome measure. In the current paper, we focus on the induction of neurodegeneration using CCEs as markers for impending neuronal loss. We compare 5 mouse models of familial AD for the appearance of CCEs in subcortical regions—deep cerebellar nuclei, amygdala, locus coeruleus, hippocampus, and dorsal raphe. We find that the models differ in their CCE involvement as well as in the appearance of phosphorylated tau and amyloid deposition, suggesting that each model represents a different disease phenotype. Comparison with the pattern of neuron death in human AD suggests that each may represent a distinctly different disease model when used in preclinical trials.
Analysis of Chloramphenicol and Its Related Compound 2-Amino-1-(4-nitrophenyl)propane-1,3-diol by Reversed-Phase High-Performance Liquid Chromatography with UV Detection
Authors: Al-Rimawi Fuad , Kharoaf Maher
Published: September 2011

A simple and stability-indicating liquid chromatographic method is developed for the analysis of chloramphenicol and its related compound 2-amino-1-(4-nitrophenyl)propane-1,3-diol in two pharmaceutical forms. Liquid chromatography with a UV detector at a wavelength of 278 nm using a reversed phase C18 stationary phase has been employed in this study. Isocratic elution is employed using a mixture of sodium pentanesulfonate solution (0.012 M), acetonitrile, and glacial acetic acid (85 : 15 : 1, v/v). This new method is validated in accordance with USP requirements for new methods for assay determination, which include accuracy, precision, specificity, linearity and range. This method shows enough selectivity, sensitivity, accuracy, precision, and linearity range to satisfy Federal Drug Administration/International Conference on Harmonization regulatory requirements. The current method demonstrates good linearity over the range of 0.04–0.16 mg/mL of chloramphenicol. The accuracy of the method is 100.0% with a relative standard deviation of 0.1%. The precision of this method reflected by relative standard deviation of replicates is 0.1%. The method is sensitive with a detection limit of 0.005% for chloramphenicol. The related substance of chloramphenicol (2-amino-1-(4-nitrophenyl)propane-1,3-diol) can be selectively determined with a good resolution in two pharmaceutical forms: eye ointment and eye drops.
Determinants of soil respiration in a semi-arid savanna ecosystem, Kruger National Park, South Africa
Authors: Makhado Rudzani A. , Scholes Robert J.
Published: September 2011

Soil respiration, which is a combination of root respiration and microbial respiration, represents one of the main carbon fluxes in savannas. However, it is remarkable how little is known about these components – regarding either process-level mechanisms or quantitative estimates, especially in savanna ecosystems. Given the extensive area of savannas worldwide, this limits our ability to understand and predict the critical changes in the global carbon budget that underlie the phenomenon of global climate change. From May 2000 to April 2001, bi-weekly soil respiration measurements from two savanna types were made in 14 sampling collars (diameter = 100 mm), using a PP Systems EGM-2 respirometer. Results indicated that there was a difference in the rate of respiration between the more clayey Acacia and sandier Combretum savanna soils (p = 0.028). The mean (± s.d.) soil respiration in the Acacia savanna was 0.540 g/m2/h ± 0.419 g/m2/h, whilst it was 0.484 g/m2/h ± 0.383 g/m2/h in the Combretum savanna. We also found that soil respiration was sensitive to soil moisture and soil temperature. The rate of soil respiration at both sites rose to a maximum when soil temperature was at 28 °C and declined at higher temperatures, despite different temperature sensitivities. Soil respiration increased approximately linearly with an increase of soil moisture. In both savanna sites soil is subject to a combination of high temperature and water stress, which controls the fluxes of soil carbon dioxide. We found that the two sites differed significantly in their soil moisture characteristics (p < 0.0001) but not with regard to temperature (p = 0.141), which implies that soil moisture is the main factor responsible for the differences in respiration between Acacia and Combretum savannas.Conservation implications: It is argued for many protected areas that they perform a climate change buffering function. Knowing the soil respiration rate and determining its controlling factors contribute to improved understanding of whether protected areas will be net sources or sinks of carbon in the future.
Horseshoes, angels and other UFOs: Rethinking faith in light of present-day superstitions
Authors: Du Toit Cornel W.
Published: September 2011

The monotheistic religions see God as the author of human faith. Faith comes �from above� and as such is unnatural or supernatural. The faith of pagans, by contrast, is regarded as superstition and hence natural (Rm 1). One can make a case for the �natural� universal incidence of both religion and superstition and their fulfilment of similar needs. In addition both are characterised by the pattern-finding operation of the human brain. The (causal) connections we make and the patterns we impose on reality have always helped people to comprehend and manipulate the world. Historical circumstances led to the development of �official� religions as institutions wielding political power, whereas superstition has remained a para-religious phenomenon to this day.But how should religion and superstition be viewed in a postmetaphysical, technoscientific environment? How can the supernatural aspects of religion and superstition be accommodated in such an environment? The role of affect and belief (placebo effect) in religion and superstition is also scrutinised. Viewed differently, both religion and superstition are considered natural and are proposed as a form of immanent transcendence, in which the �supernatural� is not posited as a metaphysical model but is worked out �from below� in terms of the human constitution.
The concept of wisdom in the Hebrew Bible � A comparative-philosophical analysis
Authors: Gericke Jacobus W.
Published: September 2011

This article provides a brief comparative philosophical clarification of the concept of wisdom in the Hebrew Bible. Utilising the format of a presentation presented by Ryan (2008), four philosophical definitions of wisdom were compared with similar sentiments in ancient Israelite religion: (1) wisdom as epistemic humility, (2) wisdom as factual knowledge, (3) wisdom as useful knowledge, and (4) wisdom as successful living. Cumulatively the four criteria might approximate a functional list of individually necessary and jointly sufficient conditions for instantiating the property of being wise.
NASA A-Train and Terra observations of the 2010 Russian wildfires
Authors: Witte J. C. , Douglass A. R. , da Silva A. , Torres O. , Levy R. , Duncan B. N.
Published: September 2011

Abstract. Wildfires raged throughout western Russia and parts of Eastern Europe during a persistent heat wave in the summer of 2010. Anomalously high surface temperatures (35–41 °C) and low relative humidity (9–25 %) from mid-June to mid-August 2010 shown by analysis of radiosonde data from multiple sites in western Russia were ideal conditions for the wildfires to thrive. Measurements of outgoing longwave radiation (OLR) from the Atmospheric Infrared Sounder (AIRS) over western Russian indicate persistent subsidence during the heat wave. Daily three-day back-trajectories initiated over Moscow reveal a persistent anti-cyclonic circulation for 18 days in August, coincident with the most intense period of fire activity observed by Moderate Resolution Imaging Spectroradiometer (MODIS). This unfortunate meteorological coincidence allowed transport of polluted air from the region of intense fires to Moscow and the surrounding area. We demonstrate that the 2010 Russian wildfires are unique in the record of observations obtained by remote-sensing instruments on-board NASA satellites: Aura and Aqua (part of the A-Train Constellation) and Terra. Analysis of the distribution of MODIS fire products and aerosol optical thickness (AOT), UV aerosol index (AI) and single-scattering albedo (SSA) from Aura's Ozone Monitoring Instrument (OMI), and total column carbon monoxide (CO) from Aqua's Atmospheric Infrared Sounder (AIRS) show that the region in the center of western Russia surrounding Moscow (52°–58° N, 33°–43° E) is most severely impacted by wildfire emissions. Over this area, AIRS CO, OMI AI, and MODIS AOT are significantly enhanced relative to the historical satellite record during the first 18 days in August when the anti-cyclonic circulation persisted. By mid-August, the anti-cyclonic circulation was replaced with westerly transport over Moscow and vicinity. The heat wave ended as anomalies of surface temperature and relative humidity, and OLR disappeared. After 18 August the fire activity greatly diminished over western Russia and levels of the satellite smoke tracers returned to values typical of previous years.
Correlation among cirrus ice content, water vapor and temperature in the TTL as observed by CALIPSO and Aura/MLS
Authors: Flury T. , Wu D. L. , Read W. G.
Published: September 2011

Abstract. Water vapor in the tropical tropopause layer (TTL) has a significant radiative cooling effect on the Earth's climate system. As a source for cirrus clouds, however, it can also indirectly produce infrared heating. The amount of water vapor in the TTL is strongly controlled by temperature (correlation r=0.94) with a seasonal cycle of ~1–2 ppm vmr in amplitude at 100 hPa and minimum values in Northern Hemisphere winter (December–January-February, DJF). Studying the A-Train CALIPSO cirrus and MLS water vapor measurements, we find that the cirrus seasonal cycle is highly (r=−0.9) anticorrelated with the water vapor variation in the TTL, showing higher cloud occurrence during DJF. We further investigate the anticorrelation on a regional scale and find that the high anticorrelation occurs generally in the ITCZ (Intertropical Convergence Zone). The seasonal cycle of the cirrus ice water content is also highly anticorrelated to water vapor (r=−0.91) and our results support the hypothesis that the total water is roughly constant in the TTL at 100 hPa. Temperature acts as a main regulator for balancing the partition between water vapor and cirrus clouds. Thus, to a large extent, the depleting water vapor in the TTL during DJF is a manifestation of cirrus formation.
The influence of boreal biomass burning emissions on the distribution of tropospheric ozone over North America and the North Atlantic during 2010
Authors: Parrington M. , Palmer P. I. , Henze D. K. , Tarasick D. W. , Hyer E. J. , Owen R. C. , Helmig D. , Clerbaux C. , Bowman K. W. , Deeter M. N. , Barratt E. M. , Coheur P.-F. , Hurtmans D. , George M. , Worden J. R.
Published: September 2011

Abstract. We analyse the tropospheric ozone distribution over North America and the North Atlantic to boreal biomass burning emissions during the summer of 2010 using the GEOS-Chem 3-D global tropospheric chemical transport model, and observations from in situ and satellite instruments. In comparison to observations from the PICO-NARE observatory in the Azores, ozonesondes across Canada, and the Tropospheric Emission Spectrometer (TES) and Infrared Atmospheric Sounding Instrument (IASI) satellite instruments, the model ozone distribution is shown to be in reasonable agreement with mean biases less than 10 ppbv. We use the adjoint of GEOS-Chem to show the model ozone distribution in the free troposphere over Maritime Canada is largely sensitive to NOx emissions from biomass burning sources in Central Canada, lightning sources in the central US, and anthropogenic sources in eastern US and south-eastern Canada. We also use the adjoint of GEOS-Chem to evaluate the Fire Locating And Monitoring of Burning Emissions (FLAMBE) inventory through assimilation of CO observations from the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument. The CO inversion showed that, on average the FLAMBE emissions needed to be reduced to 89 % of their original values, with scaling factors ranging from 12 % to 102 %, to fit the MOPITT observations in the boreal regions. Applying the CO scaling factors to all species emitted from boreal biomass burning sources led to a decrease of the model tropospheric distributions of CO, PAN, and NOx by as much as −20 ppbv, −50 ppbv, and −20 ppbv respectively. The impact of optimizing the biomass burning emissions was to reduce the model ozone distribution by approximately −3 ppbv (−8 %) and on average improved the agreement of the model ozone distribution compared to the observations throughout the free troposphere reducing the mean model bias from 5.5 to 4.0 ppbv for the PICO-NARE observatory, 3.0 to 0.9 ppbv for ozonesondes, 2.0 to 0.9 ppbv for TES, and 2.8 to 1.4 ppbv for IASI.
Aerosol optical depth and fine-mode fraction retrieval over East Asia using multi-angular total and polarized remote sensing
Authors: Cheng T. , Gu X. , Xie D. , Li Z. , Yu T. , Chen H.
Published: September 2011

Abstract. A new aerosol retrieval algorithm using multi-angular total and polarized measurements is presented. The algorithm retrieves aerosol optical depth (AOD), fine-mode fraction (FMF) for studying the impact of aerosol on climate change. The retrieval algorithm is based on a lookup table (LUT) method, which assumes that one fine and one coarse lognormal aerosol modes can be combined with proper weightings to represent the ambient aerosol properties. To reduce the ambiguity in retrieval algorithm, the key characteristics of aerosol model over East Asia are constrained using the cluster analysis technique based on the AERONET sun-photometer observation over East Asia. A mixing model of bare soil and green vegetation spectra and the Nadal and Breon model for the bidirectional polarized reflectance factor (BPDF) were used to simulate total and polarized surface reflectance of East Asia. By applying the present algorithm to POLDER measurements, three different aerosol cases of clear, polluted and dust are analyzed to test the algorithm. The comparison of retrieved aerosol optical depth (AOD) and fine-mode fraction (FMF) with those of AERONET sun-photometer observations show reliable results. Preliminary validation is encouraging. Using the new aerosol retrieval algorithm for multi-angular total and polarized measurements, the spatial and temporal variability of anthropogenic aerosol optical properties over East Asia, which were observed during a heavy polluted event, were analyzed. Exceptionally high values of aerosol optical depth contributed by fine mode of up to 0.5 (at 0.865 μm), and high values of fine-mode fraction of up to 0.9, were observed in this case study.
Land use change and the impact on greenhouse gas exchange in north Australian savanna soils
Authors: Grover S. P. P. , Livesley S. J. , Hutley L. B. , Jamali H. , Fest B. , Beringer J. , Butterbach-Bahl K. , Arndt S. K.
Published: September 2011

Abstract. Savanna ecosystems are subject to accelerating land use change as human demand for food and forest products increases. Land use change has been shown to both increase and decrease greenhouse gas fluxes from savannas and considerable uncertainty exists about the non-CO2 fluxes from the soil. We measured methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) over a complete wet-dry seasonal cycle at three replicated sites of each of three land uses: savanna, young pasture and old pasture (converted from savanna 5–7 and 25–30 yr ago, respectively) in the Douglas Daly region of northern Australia. The effect of break of season rains at the end of the dry season was investigated with two irrigation experiments. Land use change from savanna to pasture increased net greenhouse gas fluxes from the soil. Pasture sites were a weaker sink for CH4 than savanna sites and, under wet conditions, old pastures turned from being sinks to a significant source of CH4. Nitrous oxide emissions were generally very low, in the range of 0 to 5 μg N2O-N m−2 h−1, and under dry conditions soil uptake of N2O was apparent. Break of season rains produced a small, short lived pulse of N2O up to 20 μg N2O-N m−2 h−1, most evident in pasture soil. Annual cumulative soil CO2 fluxes increased after clearing, with savanna (14.6 t CO2-C ha−1 yr−1) having the lowest fluxes compared to old pasture (18.5 t CO2-C ha−1 yr−1) and young pasture (20.0 t CO2-C ha−1 yr−1). Clearing savanna increased soil-based greenhouse gas emissions from 53 to ~70 t CO2-equivalents, a 30% increase dominated by an increase in soil CO2 emissions and shift from soil CH4 sink to source. Seasonal variation was clearly driven by soil water content, supporting the emerging view that soil water content is a more important driver of soil gas fluxes than soil temperature in tropical ecosystems where temperature varies little among seasons.
Climate change impacts on snow water availability in the Euphrates-Tigris basin
Authors: Özdoğan M.
Published: September 2011

Abstract. This study investigates the effects of projected climate change on snow water availability in the Euphrates-Tigris basin using the Variable Infiltration Capacity (VIC) macro scale hydrologic model and a set of regional climate-change outputs from 13 global circulation models (GCMs) forced with two greenhouse gas emission scenarios for two time periods in the 21st century (2050 and 2090). The hydrologic model produces a reasonable simulation of seasonal and spatial variation in snow cover and associated snow water equivalent (SWE) in the mountainous areas of the basin, although its performance is poorer at marginal snow cover sites. While there is great variation across GCM outputs influencing snow water availability, the majority of models and scenarios suggest a significant decline (between 10 and 60 percent) in available snow water, particularly under the high-impact A2 climate change scenario and later in the 21st century. The changes in SWE are more stable when multi-model ensemble GCM outputs are used to minimize inter-model variability, suggesting a consistent and significant decrease in snow-covered areas and associated water availability in the headwaters of the Euphrates-Tigris basin. Detailed analysis of future climatic conditions point to the combined effects of reduced precipitation and increased temperatures as primary drivers of reduced snowpack. Results also indicate a more rapid decline in snow cover in the lower elevation zones than the higher areas in a changing climate but these findings also contain a larger uncertainty. The simulated changes in snow water availability have important implications for the future of water resources and associated hydropower generation and land-use management and planning in a region already ripe for interstate water conflict. While the changes in the frequency and intensity of snow-bearing circulation systems or the interannual variability related to climate were not considered, the simulated changes in snow water availability presented here are likely to be indicative of climate change impacts on the water resources of the Euphrates-Tigris basin.
The water footprint of electricity from hydropower
Authors: Mekonnen M. M. , Hoekstra A. Y.
Published: September 2011

Abstract. Hydropower accounts for about 16% of the world's electricity supply. It has been debated whether hydroelectric generation is merely an in-stream water user or whether it also consumes water. In this paper we provide scientific support for the argument that hydroelectric generation is in most cases a significant water consumer. The study assesses the blue water footprint of hydroelectricity – the water evaporated from manmade reservoirs to produce electric energy – for 35 selected sites. The aggregated blue water footprint of the selected hydropower plants is 90 Gm3 yr−1, which is equivalent to 10% of the blue water footprint of global crop production in the year 2000. The total blue water footprint of hydroelectric generation in the world must be considerably larger if one considers the fact that this study covers only 8% of the global installed hydroelectric capacity. Hydroelectric generation is thus a significant water consumer. The average water footprint of the selected hydropower plants is 68 m3 GJ−1. Great differences in water footprint among hydropower plants exist, due to differences in climate in the places where the plants are situated, but more importantly as a result of large differences in the area flooded per unit of installed hydroelectric capacity. We recommend that water footprint assessment is added as a component in evaluations of newly proposed hydropower plants as well as in the evaluation of existing hydroelectric dams, so that the consequences of the water footprint of hydroelectric generation on downstream environmental flows and other water users can be evaluated.
Phanerozoic black shales and the Wilson Cycle
Authors: Trabucho-Alexandre J. , Hay W. W. , de Boer P. L.
Published: September 2011

Abstract. The spatial and temporal distribution of black shales is related to the development of the environments in which they accumulate and to a propitious combination of environmental variables. Whereas much has been done in recent years to improve our understanding of the mechanisms behind the temporal distribution of black shales in the Phanerozoic, the interpretation of the palaeogeographical distribution of black shales is still dominated by an oversimplistic set of three uniformitarian depositional models that do not capture the complexity and dynamics of environments of black shale accumulation. These three models, the restricted circulation, the (open) ocean oxygen minimum and the continental shelf models, are in fact a uniformitarian simplification of the variety of depositional environments that arise and coexist throughout the course of a basin's Wilson Cycle, i.e. the dynamic sequence of events and stages that characterise the evolution of an ocean basin, from the opening continental rift to the closing orogeny. We examine the spatial distribution of black shales in the context of the Wilson Cycle using examples from the Phanerozoic. It is shown that the geographical distribution of black shales, their position in the basin infill sequence and their nature (e.g. type of organic matter, lithology) depend on basin evolution because the latter controls the development of sedimentary environments where black shales may be deposited.
How reversible is sea ice loss?
Authors: Ridley J. K. , Lowe J. A. , Hewitt H. T.
Published: September 2011

Abstract. It is well accepted that increasing atmospheric CO2 results in global warming, leading to a decline in polar sea ice area. Here, the specific question of whether there is a tipping point in the sea ice cover is investigated. The global climate model HadCM3, is used to map the trajectory of sea ice area under idealised scenarios. The atmospheric CO2 is first ramped up to four times pre-industrial levels (4 × CO2) then ramped down back to pre-industrial levels. We also examine the impact of stabilising climate at 4 × CO2 prior to ramping CO2 down to pre-industrial levels. Against global mean temperature Arctic sea ice area has little hysteresis while the Antarctic sea ice shows significant hysteresis – its rate of change slower, with falling temperatures, than its rate of change with rising temperatures. However, we show that the driver of the hysteresis is the hemispherical differences in temperature change between transient and stabilisation periods. We find no irreversible behaviour in the sea ice cover.
Combined Central Retinal Vein and Central Retinal Artery Occlusions and Neovascular Glaucoma Associated with Interferon Treatment
Authors: Rachitskaya Aleksandra V. , Lee Richard K. , Dubovy Sander R. , Schiff Eugene R.
Published: September 2011

Purpose

Interferon (IFN) is a mainstay medication used for treatment of chronic hepatitis C, as well as for treatment of certain neoplastic and autoimmune conditions. We present a case of a 50-year-old man who, while on IFN treatment, developed central retinal vein and artery occlusions complicated by the development of neovascular glaucoma secondary to severe retinal ischemia. Interferon retinopathy is associated with ischemic retinal cotton-wool spots. This case illustrates how IFN can lead to severe and sight-threatening retinal ischemia.

Methods

Case report.

Results

A 50-year-old man with previously good vision presented with decreased vision in the right eye while being treated with IFN therapy for chronic hepatitis C. He was diagnosed with central retinal vein occlusion and 2 weeks later also developed a central retinal artery occlusion. His course was complicated by the development of neovascular glaucoma. The final visual acuity was ultimately light perception.

Conclusions

Interferon therapy is commonly utilized for chronic hepatitis C, neoplastic conditions, and multiple sclerosis. Clinicians should be aware of the sight-threatening complications of IFN therapy, especially with regard to ocular vaso-occlusive disease and severe retinal ischemia.
Violent and nonviolent video games differentially affect physical aggression for individuals high vs. low in dispositional anger
Authors: Engelhardt Christopher R. , Bartholow Bruce D. , Saults J. Scott
Published: September 2011

Although numerous experiments have shown that exposure to violent video games (VVG) causes increases in aggression, relatively few studies have investigated the extent to which this effect differs as a function of theoretically relevant individual difference factors. This study investigated whether video game content differentially influences aggression as a function of individual differences in trait anger. Participants were randomly assigned to play a violent or nonviolent video game before completing a task in which they could behave aggressively. Results showed that participants high in trait anger were the most aggressive, but only if they first played a VVG. This relationship held while statistically controlling for dimensions other than violent content on which game conditions differed (e.g. frustration, arousal). Implications of these findings for models explaining the effects of video games on behavior are discussed. Aggr. Behav. 37:539–546, 2011. © 2011 Wiley Periodicals, Inc.
Nanostructures from Single Amino Acid‐Based Molecules: Stability, Fibrillation, Encapsulation, and Fabrication of Silver Nanoparticles
Authors: Koley Pradyot , Pramanik Animesh
Published: September 2011

The small‐sized molecules that have been developed from single hydrophobic amino acids (Phe, Trp, Tyr and Leu) by suitably protecting the –NH2 and –CO2H groups generate diverse nanoscopic structures – such as nanorods, nanofibrils, nanotubes, and nanovesicles – depending upon the protection parameters and solvent polarity. The vesicular structures get disrupted in the presence of various salts, such as KCl, CaCl2, (NH4)2SO4 and N(n‐Bu)4Br. Insertion of unnatural (o/m/p)‐aminobenzoic acids as a protecting group and the lack of conventional peptide bonds in the molecules give the nanostructures proteolytic stability. The nanostructures also show significant thermal stability along with a morphological transformation upon heat treatment. Our in vitro studies reveal that the addition of micromolar concentration “curcumin” significantly reduces the formation of amyloid‐like fibrils. These diverse nanostructures are used as a template for fabricating silver nanoparticles on their outer surfaces as well as in the inner part, followed by calcination in air which helps to obtain a 1D silver nanostructure. Furthermore, the nanovesicles are observed to encapsulate a potent drug (curcumin) and other biologically important molecules, which could be released through salt‐triggered disruption of vesicles.
Towards Ultrastrong Glasses
Authors: Wondraczek Lothar , Mauro John C. , Eckert Jürgen , Kühn Uta , Horbach Jürgen , Deubener Joachim , Rouxel Tanguy
Published: September 2011

The development of new glassy materials is key for addressing major global challenges in energy, medicine, and advanced communications systems. For example, thin, flexible, and large‐area glass substrates will play an enabling role in the development of flexible displays, roll‐to‐roll processing of solar cells, next‐generation touch‐screen devices, and encapsulation of organic semiconductors. The main drawback of glass and its limitation for these applications is its brittle fracture behavior, especially in the presence of surface flaws, which can significantly reduce the practical strength of a glass product. Hence, the design of new ultrastrong glassy materials and strengthening techniques is of crucial importance. The main issues regarding glass strength are discussed, with an emphasis on the underlying microscopic mechanisms that are responsible for mechanical properties. The relationship among elastic properties and fracture behavior is also addressed, focusing on both oxide and metallic glasses. From a theoretical perspective, atomistic modeling of mechanical properties of glassy materials is considered. The topological origin of these properties is also discussed, including its relation to structural and chemical heterogeneities. Finally, comments are given on several toughening strategies for increasing the damage resistance of glass products.
A New Model Describing Solid Oxide Fuel Cell Cathode Kinetics: Model Thin Film SrTi1‐xFexO3‐δ Mixed Conducting Oxides–a Case Study
Authors: Jung WooChul , Tuller Harry L.
Published: September 2011

Identifying the important factors governing the oxygen reduction kinetics at solid oxide fuel cell cathodes is critical for enhanced performance, particularly at reduced temperatures. In this work, a model mixed conducting perovskite materials system, SrTi1–xFexO3–δ, is selected, offering the ability to systematically control both the levels of ionic and electronic conductivity as well as the energy band structure. This, in combination with considerably simplified electrode geometry, serves to demonstrate that the rate of oxygen exchange at the surface of SrTi1–xFexO3–δ is only weakly correlated with either high electronic or ionic conductivity, in apparent contradiction with common expectations. Based on the correlation found between the position of the Fermi energy relative to the conduction band edge and the activation energy exhibited by the exchange rate constant, it is possible to confirm experimentally, for the first time, the key role that the minority electronic species play in determining the overall reaction kinetics. These observations lead to a new conceptual model describing cathode kinetics and provide guidelines for identifying cathodes with improved performance.
In‐situ Crosslinking and n‐Doping of Semiconducting Polymers and Their Application as Efficient Electron‐Transporting Materials in Inverted Polymer Solar Cells
Authors: Cho Namchul , Yip Hin‐Lap , Davies Joshua A. , Kazarinoff Peter D. , Zeigler David F. , Durban Matthew M. , Segawa Yukari , O'Malley Kevin M. , Luscombe Christine K. , Jen Alex K.‐Y.
Published: September 2011

In this study, we demonstrate in‐situ n‐doping and crosslinking of semiconducting polymers as efficient electron‐transporting materials for inverted configuration polymer solar cells. The semiconducting polymers were crosslinked with bis(perfluorophenyl) azide (bis‐PFPA) to form a robust solvent‐resistant film, thereby preventing solvent‐induced erosion during subsequent solution‐based device processing. In addition, chemical n‐doping of semiconducting polymers with (4‐(1,3‐dimethyl‐2,3‐dihydro‐1H‐benzoimidazol‐2‐yl)phenyl)dimethylamine (N‐DMBI) substantially improved the power conversion efficiency of solar cells from 0.69% to 3.42%. These results open the way for progress on generally applicable polymeric interface materials, providing not only high device performance but also an effective fabrication method for solution‐processed multilayer solar cell devices.