bluuebunny/crossref_metadata_2025 huggingface dataset:
Traces of historical infinitive in English dialects and their Celtic connections
Authors: KLEMOLA JUHANI
Published: July 2009

A number of nineteenth-century and early twentieth-century dialect descriptions refer to an unusual adverb + infinitive construction in southwestern and west Midlands dialects of English. The construction is most often reported in the form of a formulaic phrase away to go, meaning ‘away he went’, though it is also found with a range of other adverbs. In addition, the same dialects also make use of a possibly related imperative construction, consisting of a preposition or adverb and a to-infinitive, as in out to come! ‘Come out!’ and a negative imperative construction consisting of the negator not and the base form of the verb, as in Not put no sugar in!. These construction types appear to be marginal at best in earlier varieties of English, whereas comparable constructions with the verbal noun are a well-established feature of especially British Celtic languages (i.e. Welsh, Breton, and Cornish). In this article I argue that transfer from the British Celtic languages offers a possible explanation for the use of these constructions in the traditional southwestern and west Midlands dialects of English.
The Sun, geomagnetic polarity transitions, and possible biospheric effects: review and illustrating model
Authors: Glassmeier Karl-Heinz , Richter Otto , Vogt Joachim , Möbus Petra , Schwalb Antje
Published: July 2009

The Earth is embedded in the solar wind, this ever-streaming extremely tenuous ionized gas emanating from the Sun. It is the geomagnetic field which inhibits the solar wind plasma to directly impinge upon the terrestrial atmosphere. It is also the geomagnetic field which moderates and controls the entry of energetic particles of cosmic and solar origin into the atmosphere. During geomagnetic polarity transitions the terrestrial magnetic field decays down to about 10% of its current value. Also, the magnetic field topology changes from a dipole dominated structure to a multipole dominated topology. What happens to the Earth system during such a polarity transition, that is, during episodes of a weak transition field? Which modifications of the configuration of the terrestrial magnetosphere can be expected? Is there any influence on the atmosphere from the intensified particle bombardment? What are the possible effects on the biosphere? Is a polarity transition another example of a cosmic cataclysm? A review is provided on the current understanding of the problem. A first, illustrating model is also discussed to outline the complexity of any biospheric reaction on polarity transitions.
Late-stage stellar evolution: impact on planets
Authors: Silvotti Roberto
Published: July 2009

Among the many cosmic cataclysms that can influence life, we focus on the impact that the most critical phases of the late-stage stellar evolution may have on planets. To give an example, the red giant expansion of the Sun will probably engulf the inner planets, including perhaps the Earth. Although these studies are far from being able to predict anything concerning life, they are starting to make preliminary predictions about what can happen to planets within a few AU of the star. We present a short review of this field, in particular regarding the first detections of old evolved planets orbiting post-red giant branch stars.
Consensus and majority voting in the WTO
Authors: TIJMES-LHL JAIME
Published: July 2009

This article's subject is the implications that consensus/unanimity and majority voting might have for the World Trade Organization's (WTO) decision-making system. First it looks at some consequences that replacing the consensus rule with majority voting might have for the WTO, including justice concerns, legitimacy, homogeneity of WTO membership, and international enforcement. Second, it summarizes some solutions found in the European Union (EU) for coping with unanimity and majority rule, including constructive abstention, reallocation of contractual responsibilities, and the Luxembourg compromise. Finally, it considers some reform options for the WTO and offers some conclusions, namely expanding majority voting on certain areas only, redefining competences, multi-speed proposals (rethinking the single undertaking, constructive abstention, and the scheduling approach), redefining consensus, combining consensus and majority voting, and issuing interpretations.
Why trade facilitation matters to Africa
Authors: PORTUGAL-PEREZ ALBERTO , WILSON JOHN S.
Published: July 2009

Mitigating the impact of the economic crisis will require using all the tools necessary to regain a sustainable path to growth. This includes measures to support trade expansion, including in developing countries, such as those in Africa. This paper provides context for understanding why trade facilitation and lowering trade costs matter to Africa both today and over the long term. Trade costs are higher in Africa than in other regions. Using gravity-model estimates, the authors compute ad-valorem equivalents of improvements in trade indicators for a sample of African countries. The evidence suggests that the gains for African exporters from cutting trade costs half-way to the level of Mauritius has a greater effect on trade flows than a substantial cut in tariff barriers. As an example, improving logistics so that Ethiopia cuts its costs of trading a standardized container of goods half-way to the level in Mauritius would be roughly equivalent to a 7.6% cut in tariffs faced by Ethiopian exporters across all importers.
Legal Aspects of Church–State Relations in New Zealand
Authors: Cox Noel
Published: July 2009

Even though the church law of the Anglican Church in New Zealand is based upon the consensus of the members of the Church, the laws of the State also have an important part to play. In particular, not only is the Church, as a juridical body, subject to the law of the land, it has also relied upon the State for the enactment of certain laws. This has been necessitated by the evolution of the Church in New Zealand, and is also a legacy of the pre-colonial Church of England. This is also affected by the lack of an indigenous method or style of approach in the exposition of ecclesiastical law.
Exploring the range of climate biome projections for tropical South America: The role of CO2 fertilization and seasonality
Authors: Lapola David M. , Oyama Marcos D. , Nobre Carlos A.
Published: July 2009

Tropical South America vegetation cover projections for the end of the century differ considerably depending on climate scenario and also on how physiological processes are considered in vegetation models. In this paper we use a potential vegetation model (CPTEC‐PVM2) to analyze biome distribution in tropical South America under a range of climate projections and a range of estimates about the effects of increased atmospheric CO2. We show that if the CO2 “fertilization effect” indeed takes place and is maintained in the long term in tropical forests, then it will avoid biome shifts in Amazonia in most of the climate scenarios, even if the effect of CO2 fertilization is halved. However, if CO2 fertilization does not play any important role on tropical forests in the future or if dry season is longer than 4 months (projected by 2/14 GCMs), then there is replacement of large portions of Amazonia by tropical savanna.
Tidal sand wave formation: Influence of graded suspended sediment transport
Authors: Van Oyen T. , Blondeaux P.
Published: July 2009

The influence of graded suspended sediment transport on the formation of tidal sand waves is investigated. Hereto, in the framework of a linear stability analysis, we examine the time development of small‐amplitude perturbations superimposed to a flat heterogeneous seabed in a shallow tidal sea dominated by one tidal constituent. The heterogeneous bottom material is modeled by a bimodal sediment mixture and the transport of sediment close to the bottom, as well as in suspension, is considered. The active layer concept is employed and hiding/exposure effects are taken into account. The mechanisms giving rise to the sediment‐sorting process along the bed forms are found to be unaffected by the fractional transport of sediment in suspension. On the other hand, the formation of sand waves is quantitatively, substantially affected by the graded suspended sediment transport and the wavelength of the most amplified mode is found to depend strongly on the characteristics of the sediment mixture. In particular, the graded suspended sediment transport largely affects the contribution to the amplification rate related to the sorting process. This leads to the growth of bed forms characterized by a smaller wavelength compared with that predicted for a uniform sediment, when the mean grain size of the sediment mixture is relatively coarse. On the other hand, longer bed forms appear when the sediment mixture is characterized by a relatively fine mean grain size. Moreover, a destabilizing effect is identified in the former case while the flat bed configuration is stabilized in the latter case. A comparison of the theoretical predictions with field observations seems to support the model, even though it cannot be considered conclusive.
Flow and travel time statistics in highly heterogeneous porous media
Authors: Gotovac Hrvoje , Cvetkovic Vladimir , Andricevic Roko
Published: July 2009

In this paper we present flow and travel time ensemble statistics based on a new simulation methodology, the adaptive Fup Monte Carlo method (AFMCM). As a benchmark case, we considered two‐dimensional steady flow in a rectangular domain characterized by multi‐Gaussian heterogeneity structure with an isotropic exponential correlation and lnK variance σY2 up to 8. Advective transport is investigated using the travel time framework where Lagrangian variables (e.g., velocity, transverse displacement, or travel time) depend on space rather than on time. We find that Eulerian and Lagrangian velocity distributions diverge for increasing lnK variance due to enhanced channeling. Transverse displacement is a nonnormal for all σY2 and control planes close to the injection area, but after xIY = 20 was found to be nearly normal even for high σY2. Travel time distribution deviates from the Fickian model for large lnK variance and exhibits increasing skewness and a power law tail for large lnK variance, the slope of which decreases for increasing distance from the source; no anomalous features are found. Second moment of advective transport is analyzed with respect to the covariance of two Lagrangian velocity variables: slowness and slope which are directly related to the travel time and transverse displacement variance, which are subsequently related to the longitudinal and transverse dispersion. We provide simple estimators for the Eulerian velocity variance, travel time variance, slowness, and longitudinal dispersivity as a practical contribution of this analysis. Both two‐parameter models considered (the advection‐dispersion equation and the lognormal model) provide relatively poor representations of the initial part of the travel time probability density function in highly heterogeneous porous media. We identify the need for further theoretical and experimental scrutiny of early arrival times, and the need for computing higher‐order moments for a more accurate characterization of the travel time probability density function. A brief discussion is presented on the challenges and extensions for which AFMCM is suggested as a suitable approach.
Looking to the Future: AGU Council Takes Important Action
Authors: Grove Timothy L.
Published: July 2009

At the Joint Assembly in Toronto, the AGU Council passed three measures important to the Union's future: (1) a recommendation for a change in governance structure, (2) the schedule for the search for a new executive director, and (3) the announcement of a new strategic planning initiative.

Last month, I updated you on important data gathering and deliberations completed by the Future Focus Task Force (FFTF), a 15‐member committee established to advise the Council of changes needed for AGU's future, and I promised to share the results with you.
Geomagnetic Research From Space
Authors: Friis‐Christensen Eigil , Lühr Hermann , Hulot Gauthier , Haagmans Roger , Purucker Michael
Published: July 2009

The Decade of Geopotential Field Research, inaugurated in 1999 with the launch of the Danish satellite Ørsted on 23 February, was designed as an international effort to promote and coordinate continuous monitoring of geopotential field variability in the near‐Earth environment. Since 1999, the Challenging Minisatellite Payload (CHAMP), the Gravity Recovery and Climate Experiment (GRACE), the Satélite de Aplicaciones Científicas‐C (SAC‐C), and most recently, the Gravity field and steady‐state Ocean Circulation Explorer (GOCE) satellites have combined with Ørsted to generate an unprecedented wealth of data on Earth's magnetic and gravity fields.
Unique Meteorological Data During Hurricane Ike's Passage Over Houston
Authors: Schade Gunnar , Rappenglück Bernhard
Published: July 2009

Hurricane Ike passed over the Houston, Tex., metropolitan area during the early morning of 13 September 2008. Although Ike had been rated only a category 2 on the Saffir‐Simpson scale at landfall near Galveston, Tex., the storm's widespread damage to urban trees, many lacking proper trimming, knocked out the area's power distribution system; for some customers, power was only restored a month later.

The hurricane's path after landfall (Figure 1a) went north through Galveston Bay and Baytown. The city of Houston–with its economically important ship channel–experienced the less severe western eye wall, the tight circulation with maximum wind speeds around the hurricane's center. The eye's passage was recorded between 3:00 and 4:30 A.M. Central Standard Time (CST; Figures 1a and 1c). It had maintained its unusually large diameter of 35–40 kilometers in its first hours after landfall.
Science academies' statement on climate change
Authors: Showstack Randy
Published: July 2009

“It is essential that world leaders agree on emissions reductions needed to combat negative consequences of anthropogenic climate change,” national science academies from 13 countries declared in a joint statement issued on 11 June. The statement, issued by the academies of the G8 countries—including England, France, Russia, and the United States—and five other countries (Brazil, China, India, Mexico, and South Africa), came in advance of a G8 meeting in Italy in July and prior to United Nations Framework Convention on Climate Change (UNFCCC) negotiations in Denmark in December.
Web site for human spaceflight review committee
Authors: Showstack Randy
Published: July 2009

As part of an independent review of human spaceflight plans and programs, NASA has established a Web site for the Review of U.S. Human Space Flight Plans Committee (http://hsf.nasa.gov).

The Web site provides the committee's charter, relevant documents, information about meetings and members, and ways to contact the committee. “The human spaceflight program belongs to everyone. Our committee would hope to benefit from the views of all who would care to contact us,” noted committee chairman Norman Augustine, retired chair and CEO of Lockheed Martin Corporation.
Adapting to Climate Change: Research Challenges: Climate Change Impacts, Adaptation, and Vulnerability Community Coordination; Boulder, Colorado, 8–9 January 2009
Authors: Palutikof Jean , Romero‐Lankao Patricia
Published: July 2009

In 2007, the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) reaffirmed that anthropogenic climate change is under way, that future climate change is unavoidable, and that observed impacts can be attributed, at least in part, to anthropogenic warming. In addition, a growing number of climate change adaptation strategies are being developed around the world, indicating that policy makers are waking up to the reality of climate change. While mitigation efforts remain vital for avoiding the most dangerous impacts, adapting to unavoidable climate change is also essential. The climate change impacts, adaptation, and vulnerability (IAV) research community is now being called upon to demonstrate the likely impacts and vulnerabilities associated with future climate changes and to provide scientific advice on the most effective adaptation strategies.
High‐sensitivity measurement of diverse vascular plant‐derived biomarkers in high‐altitude ice cores
Authors: Makou Matthew C. , Thompson Lonnie G. , Montluçon Daniel B. , Eglinton Timothy I.
Published: July 2009

Semi‐volatile organic compounds derived from burned and fresh vascular plant sources and preserved in high‐altitude ice fields were detected and identified through use of recently developed analytical tools. Specifically, stir bar sorptive extraction and thermal desorption coupled with gas chromatography/time‐of‐flight mass spectrometry allowed measurement of multiple biomarkers in small sample volumes (≤30 ml). Among other compounds of interest, several diterpenoids, which suggest inputs from conifers and conifer burning, were identified in post‐industrial era and older Holocene ice from the Sajama site in the Bolivian Andes, but not in a glacial period sample, consistent with aridity changes. Differences in biomarker assemblages between sites support the use of these compounds as regionally constrained recorders of vegetation and climate change. This study represents the first application of these analytical techniques to ice core research and the first indication that records of vegetation fires may be reconstructed from diterpenoids in ice.
Bottom pressure changes around Antarctica and wind‐driven meridional flows
Authors: Ponte Rui M. , Quinn Katherine J.
Published: July 2009

Spatially‐averaged bottom pressure anomalies near Antarctica (south of 60°S) calculated from GRACE data are well correlated with those produced by the ECCO project using least‐squares optimization methods to fit an ocean model to most available data. Both GRACE and ECCO results indicate mass exchange primarily between the Southern Ocean and the Pacific and the importance of zonal wind stress to this exchange. The ECCO flow fields show that the near‐surface meridional Ekman transport, directly driven by the zonal wind stress, is nearly balanced by return flows below the shallowest topography at 60°S (∼1300 m at this Drake Passage latitude), with the return transport being slightly lagged in time relative to the Ekman transport. Such time lags, which may result from geostrophic adjustment at depth, cause the small associated net transport across 60°S to be ∼90° out of phase with the wind. This in turn can explain why zonal wind stress and bottom pressure anomalies around Antarctica tend to be anticorrelated in both GRACE and ECCO results.
ClassII peroxidase-encoding genes are present in a phylogenetically wide range of ectomycorrhizal fungi
Authors: Bödeker Inga T M , Nygren Cajsa M R , Taylor Andy F S , Olson Åke , Lindahl Björn D
Published: July 2009

Fungal peroxidases (ClassII) have a key role in degrading recalcitrant polyphenolic compounds in boreal forest wood, litter and humus. To date, their occurrence and activity have mainly been studied in a small number of white-rot wood decomposers. However, peroxidase activity is commonly measured in boreal forest humus and mineral soils, in which ectomycorrhizal fungi predominate. Here, we used degenerate PCR primers to investigate whether peroxidase-encoding genes are present in the genomes of a wide phylogenetic range of ectomycorrhizal taxa. Cloning and sequencing of PCR products showed that ectomycorrhizal fungi from several different genera possess peroxidase genes. The new sequences represent four major homobasidiomycete lineages, but the majority is derived from Cortinarius, Russula and Lactarius. These genera are ecologically important, but consist mainly of non-culturable species from which little ecophysiological information is available. The amplified sequences contain conserved active sites, both for folding and substrate oxidation. In some Cortinarius spp., there is evidence for gene duplications during the evolution of the genus. ClassII peroxidases seem to be an ancient and a common feature of most homobasidiomycetes, including ectomycorrhizal fungi. Production of extracellular peroxidases may provide ectomycorrhizal fungi with access to nitrogen sequestered in complex polyphenolic sources.
Abundant transposases encoded by the metagenome of a hydrothermal chimney biofilm
Authors: Brazelton William J , Baross John A
Published: July 2009

The carbonate chimneys of the Lost City Hydrothermal Field on the Mid-Atlantic Ridge are coated in thick microbial biofilms consisting of just a few dominant species. We report a preliminary analysis of a biofilm metagenome that revealed a remarkable abundance and diversity of genes potentially involved in lateral gene transfer (LGT). More than 8% of all metagenomic reads showed significant sequence similarity to transposases; all available metagenomic data sets from other environments contained at least an order of magnitude fewer transposases. Furthermore, the sequence diversity of transposase genes in the biofilm was much greater than that of 16S rRNA genes. The small size and high sequencing coverage of contigs containing transposases indicate that they are located on small but abundant extragenomic molecules. These results suggest that rampant LGT among members of the Lost City biofilm may serve as a generator of phenotypic diversity in a community with very low organismal diversity.
Metabolic rate links density to demography in Tetrahymena pyriformis
Authors: DeLong John P , Hanson David T
Published: July 2009

Many populations show density-dependent growth rates. We suggest that population growth rate may be connected to density through the density dependence of metabolic rate. If metabolic rate is an index of the total biochemical work being done by an organism, then as populations grow and density suppresses metabolic rate, the rate of reproduction should slow and the ability to avoid death should diminish. To test this idea, we grew axenic populations of a single-celled protist, Tetrahymena pyriformis, in laboratory microcosms, and measured metabolic rate and density. We also estimated division (birth) and death rates. The proposed connection was supported by two observations. First, increasing population density suppressed per-capita metabolic rate in accordance with the predictions of a resource-division model. The same pattern was shown with experimentally altered densities. Second, per-capita metabolic rate was positively related to per-capita division rate and negatively related to per-capita death rate. Thus, the particular pattern of population growth and regulation depends on exactly how individuals respond energetically to the density of conspecifics, and how they allocate metabolism to maintenance and production. The physiological basis of population regulation in this system is based on the constraints imposed on the total metabolic work that individual cells can perform.
The effects of cross‐link density and chemistry on the calcification potential of diamine‐extended glutaraldehyde‐fixed bioprosthetic heart‐valve materials
Authors: Bezuidenhout Deon , Oosthuysen Anel , Human Paul , Weissenstein Christoph , Zilla Peter
Published: July 2009

Despite indications that GA (glutaraldehyde)‐cross‐linked tissues remain prone to long‐term degradation and calcification, it is still the reagent of choice in the fixation of bioprosthetic heart valves. We have shown previously that increased GA concentrations and diamine extension of cross‐links with lysine incorporation lead to mitigated in vivo calcification, mainly of porcine aortic‐wall tissue. The present study was performed to assess the correlation between the cross‐link density of all three commonly used tissue types [PW (porcine aortic wall), PL (porcine aortic leaflet) and BP (bovine pericardium)] and tissue calcification in the subcutaneous rat model after GA treatment with or without lysine. The effect of lysine enhancement, and increased GA concentration in the presence of lysine, resulted in significant increases in tissue cross‐linking in all three tissue types. Although increased GA concentration on its own resulted in decreased calcification without an increase in cross‐link density, overall positive correlations were found between denaturation temperature and RPD (resistance towards protease degradation) [correlation coefficient (ρ) values: ρPW=0.922, ρPL=0.783 and ρBP=0.955], whereas negative correlations existed between RPD and calcification (ρPW=−0.836, ρPL=−0.929 and ρBP=−0.579). The combination of lysine enhancement and an increase in GA concentration from 0.2 to 3% resulted in 79, 44 and 56% decreases in calcification in PW, PL and BP. In the case of BP, a decrease in calcification of 81% could be achieved merely by adding lysine extension to low‐concentration (0.2%) GA cross‐linking. Thus it is concluded that the increase in cross‐link density achieved by lysine incorporation, and by increased GA concentration in the presence of lysine, results in significant and marked decreases in calcification of all three types of tissues commonly used in bioprosthetic heart valves.
Signal transducer and activator of transcription 3 (STAT3) regulates adipocyte differentiation via peroxisome‐proliferator‐activated receptor γ (PPARγ)
Authors: Wang Dongmei , Zhou Yiran , Lei Weiwei , Zhang Kehua , Shi Jian , Hu Ying , Shu Guangwen , Song Jianguo
Published: July 2009

Background information. STAT3 (signal transducer and activator of transcription 3) is an important transcription factor involved in many biological events, including apoptosis, tumorigenesis, angiogenesis and epithelial‐to‐mesenchymal transition. However, no direct evidence for a role of STAT3 in 3T3‐L1 adipocyte differentiation has been reported.

Results. In the present study, we found that rapid activation of STAT3, lasting for more than 48 h, was elicited upon induction of adipogenesis. Both the STAT3‐selective inhibitor stattic and the JAK2 (Janus kinase 2)/STAT3‐selective inhibitors AG490 and Gö6976 inhibited STAT3 activation, leading to the suppression of adipocyte differentiation. Adipocyte differentiation was also suppressed by STAT3 siRNA (small interfering RNA) or dominant‐negative STAT3. Interestingly, the PPARγ (peroxisome‐proliferator‐activated receptor γ) agonist TAZ (troglitazone) abolished the STAT3‐inhibitor‐ and RNAi (RNA interference)‐mediated suppression of adipogenesis. However, TAZ treatment had no effect on the stattic‐ and AG490‐mediated down‐regulation of STAT3 activation, suggesting that STAT3 regulates adipocyte differentiation through signalling that occurs upstream of PPARγ.

Conclusion. These data indicate that STAT3 functions as a critical factor for adipogenesis via a mechanism involving the PPARγ activation pathway.
Prostaglandin EP2 and EP4 receptors modulate expression of the chemokine CCL2 (MCP-1) in response to LPS-induced renal glomerular inflammation
Authors: Zahner Gunther , Schaper Melanie , Panzer Ulf , Kluger Malte , Stahl Rolf A. K. , Thaiss Friedrich , Schneider André
Published: July 2009

The pro-inflammatory chemokine CCL2 [chemokine (Cys-Cys motif) ligand 2; also known as MCP-1 (monocyte chemotactic protein-1)] is up-regulated in the glomerular compartment during the early phase of LPS (lipopolysaccharide)-induced nephritis. This up-regulation also occurs in cultured MCs (mesangial cells) and is more pronounced in MCs lacking the PGE2 (prostaglandin E2) receptor EP2 or in MCs treated with a prostaglandin EP4 receptor antagonist. To examine a possible feedback mechanism of EP receptor stimulation on CCL2 expression, we used an in vitro model of MCs with down-regulated EP receptor expression. Selectively overexpressing the various EP receptors in these cells then allows the effects on the LPS-induced CCL2 expression to be examined. Cells were stimulated with LPS and CCL2 gene expression was examined and compared with LPS-stimulated, mock-transfected PTGS2 [prostaglandin-endoperoxide synthase 2, also known as COX-2 (cyclo-oxygenase-2)]-positive cells. Overexpression of EP1, as well as EP3, had no effect on LPS-induced Ccl2 mRNA expression. In contrast, overexpression of EP2, as well as EP4, significantly decreased LPS-induced CCL2 expression. These results support the hypothesis that PTGS2-derived prostaglandins, when strongly induced, counter-balance inflammatory processes through the EP2 and EP4 receptors in MCs.
On the lateral crystal growth of laser irradiated NiTi thin films
Authors: Birnbaum A. J. , Yao Y. Lawrence , Chung U.-J. , Im James. S. , Huang X. , Ramirez A. G.
Published: July 2009

This letter demonstrates the ability to induce laterally grown, large-aspect crystals via pulsed, melt-mediated laser crystallization in NiTi thin films. Sputter-deposited 200 nm NiTi films were pulse irradiated utilizing a homogenized 308 nm excimer beam over a series of varying incident laser energy densities. Solidification occurred via two distinct pathways: nucleation and growth occurred away from the boundary of irradiation, while lateral growth of unmelted seeds into the undercooled melt developed at the boundary of irradiation. The potential for exploiting this technique to produce rolling direction texture for anisotropic properties is also discussed.
Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project
Authors: Hummelshøj J. S. , Landis D. D. , Voss J. , Jiang T. , Tekin A. , Bork N. , Dułak M. , Mortensen J. J. , Adamska L. , Andersin J. , Baran J. D. , Barmparis G. D. , Bell F. , Bezanilla A. L. , Bjork J. , Björketun M. E. , Bleken F. , Buchter F. , Bürkle M. , Burton P. D. , Buus B. B. , Calborean A. , Calle-Vallejo F. , Casolo S. , Chandler B. D. , Chi D. H. , Czekaj I , Datta S. , Datye A. , DeLaRiva A. , Despoja V , Dobrin S. , Engelund M. , Ferrighi L. , Frondelius P. , Fu Q. , Fuentes A. , Fürst J. , García-Fuente A. , Gavnholt J. , Goeke R. , Gudmundsdottir S. , Hammond K. D. , Hansen H. A. , Hibbitts D. , Hobi E. , Howalt J. G. , Hruby S. L. , Huth A. , Isaeva L. , Jelic J. , Jensen I. J. T. , Kacprzak K. A. , Kelkkanen A. , Kelsey D. , Kesanakurthi D. S. , Kleis J. , Klüpfel P. J. , Konstantinov I , Korytar R. , Koskinen P. , Krishna C. , Kunkes E. , Larsen A. H. , Lastra J. M. G. , Lin H. , Lopez-Acevedo O. , Mantega M. , Martínez J. I. , Mesa I. N. , Mowbray D. J. , Mýrdal J. S. G. , Natanzon Y. , Nistor A. , Olsen T. , Park H. , Pedroza L. S. , Petzold V , Plaisance C. , Rasmussen J. A. , Ren H. , Rizzi M. , Ronco A. S. , Rostgaard C. , Saadi S. , Salguero L. A. , Santos E. J. G. , Schoenhalz A. L. , Shen J. , Smedemand M. , Stausholm-Møller O. J. , Stibius M. , Strange M. , Su H. B. , Temel B. , Toftelund A. , Tripkovic V , Vanin M. , Viswanathan V , Vojvodic A. , Wang S. , Wellendorff J. , Thygesen K. S. , Rossmeisl J. , Bligaard T. , Jacobsen K. W. , Nørskov J. K. , Vegge T.
Published: July 2009

We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition metal atom (M2) plus two to five (BH4)− groups, i.e., M1M2(BH4)2–5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M1(Al/Mn/Fe)(BH4)4, (Li/Na)Zn(BH4)3, and (Na/K)(Ni/Co)(BH4)3 alloys are found to be the most promising, followed by selected M1(Nb/Rh)(BH4)4 alloys.
Near-infrared photoabsorption by C60 dianions in a storage ring
Authors: Kadhane U. , Andersen J. U. , Bonderup E. , Concina B. , Hvelplund P. , Kirketerp M.-B. Suhr , Liu B. , Nielsen S. Brøndsted , Panja S. , Rangama J. , Støchkel K. , Tomita S. , Zettergren H. , Hansen K. , Sundén A. E. K. , Canton S. E. , Echt O. , Forster J. S.
Published: July 2009

We present a detailed study of the electronic structure and the stability of C60 dianions in the gas phase. Monoanions were extracted from a plasma source and converted to dianions by electron transfer in a Na vapor cell. The dianions were then stored in an electrostatic ring, and their near-infrared absorption spectrum was measured by observation of laser induced electron detachment. From the time dependence of the detachment after photon absorption, we conclude that the reaction has contributions from both direct electron tunneling to the continuum and vibrationally assisted tunneling after internal conversion. This implies that the height of the Coulomb barrier confining the attached electrons is at least ∼1.5 eV. For C602− ions in solution electron spin resonance measurements have indicated a singlet ground state, and from the similarity of the absorption spectra we conclude that also the ground state of isolated C602− ions is singlet. The observed spectrum corresponds to an electronic transition from a t1u lowest unoccupied molecular orbital (LUMO) of C60 to the t1g LUMO+1 level. The electronic levels of the dianion are split due to Jahn–Teller coupling to quadrupole deformations of the molecule, and a main absorption band at 10723 cm−1 corresponds to a transition between the Jahn–Teller ground states. Also transitions from pseudorotational states with 200 cm−1 and (probably) 420 cm−1 excitation are observed. We argue that a very broad absorption band from about 11 500 cm−1 to 13 500 cm−1 consists of transitions to so-called cone states, which are Jahn–Teller states on a higher potential-energy surface, stabilized by a pseudorotational angular momentum barrier. A previously observed, high-lying absorption band for C60− may also be a transition to a cone state.
Structural, magnetic, and transport properties of laser-annealed GaAs:Mn–H
Authors: Farshchi R. , Hwang D. J. , Misra N. , Julaton C. C. , Yu K. M. , Grigoropoulos C. P. , Dubon O. D.
Published: July 2009

We have investigated the effect of laser annealing on the structural, magnetic, and transport properties of hydrogenated Ga0.96Mn0.04As films. Irradiation with nanosecond laser pulses leads to significant recovery of hole-mediated ferromagnetism in these films. By tuning processing parameters such as laser fluence and number of pulses, one can control the electrical and magnetic properties—namely, resistivity, magnetic coercivity, and remnant magnetization—in the laser-activated region. Ion-beam analysis indicates that the structural integrity of the film is maintained upon hydrogenation and laser annealing with evidence for displacement of substitutional Mn ions toward interstitial sites due to hydrogen-complex formation. Laser annealing results in the relaxation of up to 50% of Mn atoms back to substitutional sites while the Curie temperature recovers to ∼60% of the TC prior to hydrogenation. Subsequent thermal annealing results in full relocation of Mn atoms to substitutional sites, yet the TC remains pinned at ∼60% of its original value, suggesting the formation of a defect complex involving substitutional Mn. Our numerical simulations elucidate the strong interplay between laser processing parameters and Mn–H dissociation.
When group-III nitrides go infrared: New properties and perspectives
Authors: Wu Junqiao
Published: July 2009

Wide-band-gap GaN and Ga-rich InGaN alloys, with energy gaps covering the blue and near-ultraviolet parts of the electromagnetic spectrum, are one group of the dominant materials for solid state lighting and lasing technologies and consequently, have been studied very well. Much less effort has been devoted to InN and In-rich InGaN alloys. A major breakthrough in 2002, stemming from much improved quality of InN films grown using molecular beam epitaxy, resulted in the bandgap of InN being revised from 1.9 eV to a much narrower value of 0.64 eV. This finding triggered a worldwide research thrust into the area of narrow-band-gap group-III nitrides. The low value of the InN bandgap provides a basis for a consistent description of the electronic structure of InGaN and InAlN alloys with all compositions. It extends the fundamental bandgap of the group III-nitride alloy system over a wider spectral region, ranging from the near infrared at ∼1.9 μm (0.64 eV for InN) to the ultraviolet at ∼0.36 μm (3.4 eV for GaN) or 0.2 μm (6.2 eV for AlN). The continuous range of bandgap energies now spans the near infrared, raising the possibility of new applications for group-III nitrides. In this article we present a detailed review of the physical properties of InN and related group III-nitride semiconductors. The electronic structure, carrier dynamics, optical transitions, defect physics, doping disparity, surface effects, and phonon structure will be discussed in the context of the InN bandgap re-evaluation. We will then describe the progress, perspectives, and challenges in the developments of new electronic and optoelectronic devices based on InGaN alloys. Advances in characterization and understanding of InN and InGaN nanostructures will also be reviewed in comparison to their thin film counterparts.
Resonance frequencies of cavities in three-dimensional electromagnetic band gap structures
Authors: Khromova Irina , Gonzalo Ramón , Ederra Iñigo , de Maagt Peter
Published: July 2009

This paper is devoted to the phenomenon of resonant transmission in three-dimensional electromagnetic band gap structures (EBGs), achieved by introducing a defect into an EBG structure with the corresponding resonance frequency of the defect lying within the initial EBG region. It is shown that the resonance frequency of an EBG air cavity (acceptor defect) can either increase or decrease with increasing cavity dimensions. In particular, this paper demonstrates both experimentally and theoretically that the resonance frequency of a woodpile air cavity, formed by the partial removal of a woodpile bar, increases with increasing cavity size; it increases continuously or saturates depending on the field polarization with respect to the cavity orientation. The results obtained in this paper can be used for designing EBG devices based on resonant transmission.
Three-dimensional stability of a thin film between two approaching drops
Authors: Kaur Sukhvinder , Leal L. Gary
Published: July 2009

In most simulations of the coalescence process, the rupture of the thin film between two drops is assumed to be axisymmetric. In this paper, we examine the possibility of a nonaxisymmetric rupture by carrying out a three-dimensional linear stability analysis of an axisymmetric thin film region. First, the effect of tangential interfacial velocity on the stability of a flat film is analyzed and a scaling analysis is provided to predict the dependence of the critical film thickness on the dimensionless parameters of the problem: the capillary number Ca, the dimensionless Hamaker constant A∗, and the viscosity ratio λ. Multigrid integration and implicit eigensystem solution techniques are used to simultaneously solve the boundary integral and film evolution equations for the disturbance shape and growth rate. The calculations show that a fixed-end disturbance, which decays to zero at the edge of the film, exhibits maximum instability in the axisymmetric mode. On the other hand, the first nonaxisymmetric mode is the most unstable for the class of free-end disturbances that approach the edge of the film with zero slope. Next, the stability calculation is interfaced with the full axisymmetric simulation of two drops approaching in a biaxial extensional flow in order to obtain the correct base-state film shape at each time interval. In this case, the thin film first becomes unstable to a nonaxisymmetric disturbance for both kinds of boundary conditions. The critical thickness from the stability calculation is compared with the critical film thickness obtained earlier from numerical calculations of the collision and interaction of a pair of fully axisymmetric drops and the effect of base-state curvature on film stability is investigated.
Novel device for simultaneous volumetric and x-ray diffraction measurements on metal-hydrogen systems
Authors: Talagañis B. A. , Castro F. J. , Baruj A. , Meyer G.
Published: July 2009

Hydrogen storage materials can form more than one hydride phase. These different phases, in turn, display different hydrogen absorption/desorption capacities, kinetics, and stabilities. Studies aimed at characterizing and improving these materials usually need to correlate hydrogen intake with the precise determination of the hydride phase involved in the process. Here, we present a device designed to perform measurements of well known volumetric techniques with simultaneous x-ray diffraction on the material under study. The compact design can stand up to 6000 kPa of internal pressure while the sample can be heated up to 450 °C. The design process was assisted by finite element modeling and by the use of mock-up prototypes in order to optimize the thermal and under load behaviors. We provide two examples of use for this new device: (1) hydride decomposition in LaNi5 at 115 °C and (2) formation of MgCo during the programmed thermal desorption of the Mg2CoH5 hydride.
Magnetic properties of Fe-rich Fe–V alloy films
Authors: Jen S. U. , Tsai T. L. , Liu C. C.
Published: July 2009

Polycrystalline Fe100−xVx with x=0 to 14 at.% V films on a glass substrate were made by the dc magnetron sputtering method. The deposition temperature was 250 °C. The magnetic properties, i.e., saturation magnetization 4πMs, bulk-pinning field for a domain wall Hcw, coercive force Hc, initial permeability μi, maximum permeability μm, saturation magnetostriction λs, and electrical property, such as the electrical resistivity ρ of the Fe–V films, were measured. We find that 4πMs is a decreasing function of x, Hc, and/or Hcw has a minimum at x≈x0=8 at. % V, μi, μm, and/or μc has a maximum at x=x0, λs≈0 at x=x0, and ρ is an increasing function of x. These new magnetic results are consistent with earlier magnetostriction measurements [Jen and Chen, J. Magn. Magn. Mater. 204, 165 (1999)] and theoretical calculations [Ostanin, Staunton, and Razee, Phys. Rev. B 69, 064425 (2004)]. Moreover, all the magnetic features in the x dependence of Hc, Hcw, μi, μm, μc, and λs, respectively, can be explained within the framework of the bulk-pinning (or surface-pinning) and the end-pinning (or nucleation) models. Briefly, the pinning model analysis of the magnetic hysteresis data confirms the inference that near zero λs implies maximal permeabilities and smallest Hc and Hcw. Among all the Fe–V films, the Fe92V8 film has the optimal magnetic and electrical properties for application.
The screening effect on field enhancement factor of the finite-length small radius single-walled carbon nanotubes
Authors: Su W. S. , Chuang F. C. , Cho T. H. , Leung T. C.
Published: July 2009

The screening effects on the field enhancement factors of (3,3) and (5,0) finite length single-walled carbon nanotubes (SWCNTs) with respect to different kinds of tube terminations, either capped or H-terminated, are examined using first-principles calculations. Results show that for capped SWCNTs, the field enhancement factors of the (3,3) tube are slightly greater than those of (5,0) ones, while for H-terminated tubes exhibit the opposite effect. The effects of different endings on the SWCNT work functions are also investigated. Calculations show that for the capped SWCNTs, the work functions of (3,3) tubes are larger than those of (5,0) tubes, whereas for the H-terminated cases, the work functions of (3,3) tubes are smaller than those of the (5,0) tubes. Moreover, a saturated behavior of enhancement factors β versus the length of tubes is observed. Finally, the field enhancement factors of fixed length tubes can be enhanced to eventually achieve a convergent tendency as their tube-tube distance increases.
The dependence of the electrochemical properties of perfluorosulfonic acid membrane/water systems on repeat unit structure
Authors: Kim Young Gyun , Bae Young Chan
Published: July 2009

We developed a molecular thermodynamic framework to describe the dependence of the electrochemical properties of a perfluorosulfonic acid (PFSA) membrane/water system on the polymer structure. To better understand the behavior of the polymer membrane/water system, we developed a lattice model based on lattice cluster theory. We performed hypothetical calculations for a variety of repeat unit structures. We also investigated the correlation between the interaction energy and extending or reducing the chain length of the polymer repeat unit using COMPASS force fields. Our results indicate that the ionic conductivity of the nonpolar CF2CF2 group in the main chain varies with the length of the chain. In addition, the ionic conductivity of different CF2CF2 group chain lengths fluctuates according to hydration level. When OCF2CF3CF groups are substituted at 0 and 1, the predictions of the PFSA membrane agreed well with the experimental data from a Dow membrane. To obtain good ionic conductivity at a high vapor equilibrated hydration level, the nonpolar group in the polymer repeat unit and the substituted group chain connecting the nonpolar group length should both be short, and the substituted group chain connected with the sulfonic group should be long.
Vertical electronic excitation with a dielectric continuum model of solvation including volume polarization. I. Theory
Authors: Chipman Daniel M.
Published: July 2009

A dielectric continuum model of solvation is developed for use in conjunction with electronic structure calculation on vertical electronic excitation of a solute. Particular attention is paid to volume polarization arising from quantum mechanical penetration of solute charge density outside the cavity that nominally encloses it, which affects both the fast and slow components of the dielectric response. An approximation that closely simulates volume polarization while being easier to implement in practice is also described. These approaches are compared to other related formulations found in the literature.
Ultrasonic friction power during Al wire wedge-wedge bonding
Authors: Shah A. , Gaul H. , Schneider-Ramelow M. , Reichl H. , Mayer M. , Zhou Y.
Published: July 2009

Al wire bonding, also called ultrasonic wedge-wedge bonding, is a microwelding process used extensively in the microelectronics industry for interconnections to integrated circuits. The bonding wire used is a 25μm diameter AlSi1 wire. A friction power model is used to derive the ultrasonic friction power during Al wire bonding. Auxiliary measurements include the current delivered to the ultrasonic transducer, the vibration amplitude of the bonding tool tip in free air, and the ultrasonic force acting on the bonding pad during the bond process. The ultrasonic force measurement is like a signature of the bond as it allows for a detailed insight into mechanisms during various phases of the process. It is measured using piezoresistive force microsensors integrated close to the Al bonding pad (Al–Al process) on a custom made test chip. A clear break-off in the force signal is observed, which is followed by a relatively constant force for a short duration. A large second harmonic content is observed, describing a nonsymmetric deviation of the signal wave form from the sinusoidal shape. This deviation might be due to the reduced geometrical symmetry of the wedge tool. For bonds made with typical process parameters, several characteristic values used in the friction power model are determined. The ultrasonic compliance of the bonding system is 2.66μm∕N. A typical maximum value of the relative interfacial amplitude of ultrasonic friction is at least 222nm. The maximum interfacial friction power is at least 11.5mW, which is only about 4.8% of the total electrical power delivered to the ultrasonic generator.