bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Mold Surface Roughness on the Interfacial Heat Transfer Coefficient During Solidification of Solder Alloys
Authors: Dias Antonio Carlos Pires , Meza Elisangela dos Santos , Bertelli F. , Goulart Pedro R. , Cheung Noé , Garcia Amauri
Published: November 2012

Solder joints are strongly dependent on how well the solder alloy can wet the substrate. One of the parameters which can be used to characterize the wettability of solder alloys on a substrate is the heat transfer coefficient at the interface alloy/substrate, hi. This study focus on the effect of the surface roughness of the substrate on the interfacial heat transfer coefficient during solidification of solder alloys. A comparative study is carried out with two lead-free solders alternatives and the traditional Sn-Pb solder (Sn 0.7wt%Cu, Sn 3.5 wt%Ag and Sn 38wt%Pb, respectively). These alloys were directionally solidified using a solidification apparatus having a water cooled bottom made of low carbon steel with two different surface finishing: machined and polished. The experimental thermal data collected by thermocouples positioned along the casting length were used as input information into an Inverse Heat Transfer Code implemented in this work in order to determine the hi variation in time. A power–law function given by (where a and m are constants which depend on the alloy composition, substrate and melt superheat and t is the time) which is based on both theoretical and experimental analyses is proposed. The transient hi profile has a typical drastic reduction from a high initial value due to the development of an air gap, followed by a recovery to an essentially constant value. The literature generally reports a decrease in hi with increasing surface roughness. However, in the present work an opposite behavior has been detected, which is explained based on contact interactions between alloy and substrate that are subjected to thermal contraction and thermal expansion during the soldering process, respectively.
Characterization of Bi6Fe2Ti3O18 Ceramics with Impedance Spectroscopy
Authors: Lisińska-Czekaj Agata , Czekaj Dionizy
Published: November 2012

In the present research the tool of impedance spectroscopy was utilized to characterize dielectric behavior of Aurivillius-type ceramics of Bi6Fe2Ti3O18 composition fabricated by hot pressing method from the stoichiometric mixture of oxides Bi2O3, TiO2 and Fe2O3. Impedance spectroscopy was applied to characterize dielectric response of bulk, grain boundary, and material/electrode interfaces of the fabricated polycrystalline ceramic material at both room and elevated temperature. The Kramers-Kronig data validation test was employed in the impedance data analysis. Experimental data were fitted using the CNLS fitting method. Agreement between experimental and simulated data was established.
Effect of the Acid Environment on the Electrochemical Behaviour of 1045 Steel Reinforced Cement
Authors: da Nóbrega Ana Cecilia Vieira , Rocha Luís Augusto Sousa Marques , Avila Edith Ariza , Martinelli Antonio Eduardo , de Araújo Melo Dulce Maria , de Sá Maria das Vitórias Vieira Almeida
Published: November 2012

External corrosion is one of the most common causes of oilwell casing failure. Hostile environments can be due to acidizing treatments. Although it is common to add corrosion inhibitors and oxygen scavengers in acidic solutions to control external casing corrosion, their real efficiency is unknown yet. Therefore, it is important to establish how aggressive to steel are the different hostile environments to help decide which acidic systems can be used. A comparative evaluation of the corrosion of steel immersed in hardened cement slurries submitted to commonly acidizing agents is suggested. The performance of Special Class Portland Cement Slurries reinforced with polished SAE 1045 steel was evaluated by electrochemical measurements as a function of time. Open circuit potential, polarization curves and electrochemical impedance spectroscopy were studied. 15.0 wt% HCl, 12.0 wt% HCl + 3.0 wt% HF (regular mud acid), 10.0 wt% HAc + 1.5 wt% HF and a simulated hardened cement slurry pore solution were used as electrolytes. The most aggressive acid solution to plain Portland hardened cement slurries was the regular mud acid. 10.0 wt% HAc + 1.5 wt% HF electrolytes were the least aggressive ones, showing open circuit potentials around +250 mV compared to -130 mV of the simulated hardened cement slurry pore solution after the first 24 hours of immersion. This behavior was observed during two months at least. Similar corrosion rates were shown between both electrolytes, around 0.01 μA.cm-2. Total impedance values, insipient arcs and large polarization resistance capacitive arcs on the Nyquist plots, indicating passivity process, confirmed the behaviour of the system in the 10.0 wt% HAc + 1.5 wt% HF electrolyte.
Experimental and First Principles Study of the Ni-Ti-W System
Authors: de Sá Maria H. , Isomäki Iikka , Ferreira Jorge A. , Hämäläinen Marko , Braga Maria H.
Published: November 2012

Nickel based superalloys are structural materials with a chemical composition and structure which has been developed to enable good high temperature performances leading to a wider range of applications. Their unique properties are due to their microstructure characterized by the coexistence of L12-ordered intermetallic precipitates like Ni3Al or Ni3Ti - g’ phase - in a face-centered cubic nickel based solid solution matrix, (Ni) - g phase. Solid solution strengthening at high temperatures can also be provided by the addition of refractory alloying elements, like tungsten, W. Therefore, the mechanical properties behaviour of the alloys is very strongly related to their composition and microstructures. The purpose of this work is to study the effect of composition and microstructures in a series of Ni-rich prototype alloys, Ni100-2x–Tix–Wx (in which x is in at.%), in order to understand and ultimately optimize the performance of these materials. The adopted strategy was to combine experimental studies using Neutron Diffraction, Electron Probe Micro Analysis – EPMA, Differential Scanning Calorimeter – DSC and micro-hardness measurements, with first principles calculations for structure optimization and Gibbs energies at different temperatures, for each phase, leading to thermodynamic assessment.
Colloidal Processing of Fine Spinel Powders
Authors: Zych Łukasz , Wajler Anna , Lach Radosław
Published: November 2012

Magnesium-aluminium spinel (MgAl2O4) in the form of transparent ceramics is applied in shields of infrared detectors or emitters, high-temperature widows and elements of military aircrafts and vehicles. Apart from high transparency for specific wave lengths, such materials should have good mechanical properties, especially hardness. It is the reason for production of the fine-grained materials. It seems that they can be produced from submicron powders consolidated by one of colloidal techniques. The work presents preliminary results of investigations on colloidal consolidation of two fine spinel powders with different particle size by pressure filtration and slip casting. The aim of the studies was consolidation of the fine powders leading to green samples with narrow pore size distribution. The samples were then sintered in isothermal conditions. Microstructure, Vickers hardness and transmission in infrared spectrum of the dense materials were examined.
Microalloying of the Zinc for Obtaining Masteralloys or Correction of the Chemical Composition for the Zn Baths in the Galvanizing Process
Authors: Alexa Alexandru , Ciocan Anisoara , Radu Tamara , Potecasu Florentina
Published: November 2012

The paper presents the research that has developed to clarify the zinc microalloying process with nickel, aluminum, bismuth and tin. We have analyzed the parameters and factors that influenced the dissolution process of alloying solid elements in the liquid phase (zinc bath) in respect to compositional controlling process. In accordance we analyzed the most important parameters that influenced this process. There have established the optimum making technology of the zinc alloys used into hot dip galvanized process and also the correction technology of the bath composition into continuous process.
Surface Improvement by Overlapping in Multipass FSP
Authors: Gandra João , Miranda Rosa M. , Vilaça Pedro
Published: November 2012

Friction stir processing (FSP) is an emerging metal-working technique based on the same fundaments as friction stir welding that allows local modification and control of microstructures, for the purpose of improving surface or in-volume mechanical properties. This paper aims to explore several applications of the FSP technology for surface improvement either by multipass FSP or surface reinforcement with silicon carbide particles. An AA5083-H111 alloy 8 mm thick was tested. Structural and mechanical differences were observed when overlapping by the advancing side (AS) direction or by the retreating side (RS) one. Hardness within the processed layer increased by 8.5 % and was seen to be approximately constant between passes. Toughness under bending was improved by 18 %. The production of particle-reinforced metal matrix composite materials (MMC) was investigated, as the severe plastic deformation inherent to the process promoted the dispersion of 12.5 μm median size SiC particles, resulting in a severe superficial hardness increase.
Analysis of CoCrMo Surface Oxide Removal by Alumina Blasting before Porcelain Firing in Dental Restorations
Authors: Henriques Bruno , Silva Filipe , Soares Delfim
Published: November 2012

The purpose of this work was to perform a chemical and mechanical characterization of a preoxidized CoCrMo alumina blasted surface. This is a commonly performed surface treatment used in metal-porcelain systems for dental restorations to remove oxides formed during preoxidation heat treatment from the metal’s surface. CoCrMo dental alloy’s specimens produced by lost wax process were examined in terms of chemical composition using X-Ray fluorescence spectroscopy (XRF), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS); in terms of mechanical characteristics through the means of a microhardness test and in terms of surface roughness using a profilometer. It was investigated the chemical composition of various surface conditions: non-preoxidized, preoxidized, ground oxidized surface and sandblasted oxidized surface. After alumina blasting, the oxides level on metal’s surface remained high. Alumina blasting treatment (Ø110 µm) produced an 84% increase of CoCrMo surface hardening and an increase in surface roughness (Ra=0.58 µm). It was found alumina contaminants on the metal’s surface. Therefore, it was concluded that alumina blasting do not entirely removes the oxide layer formed during preoxidation heat treatment. It produced a chemical and mechanical surface modification that can influence the metal-ceramic bond strength.
Multiscale Copper-µDiamond Nanostructured Composites
Authors: Nunes Daniela , Livramento Vanessa , Fernandes Horácio , Silva Carlos , Shohoji Nobumitsu , Correia José B. , Carvalho Patricia A.
Published: November 2012

Nanostructured copper-diamond composites can be tailored for thermal management applications at high temperature. A novel approach based on multiscale diamond dispersions is proposed for the production of this type of materials: a Cu-nDiamond composite produced by high-energy milling is used as a nanostructured matrix for further dispersion of micrometer sized diamond. The former offers strength and microstructural thermal stability while the latter provides high thermal conductivity. A series of Cu-nDiamond mixtures have been milled to define the minimum nanodiamond fraction suitable for matrix refinement and thermal stabilization. A refined matrix with homogenously dispersed nanoparticles could be obtained with 4 at.% nanodiamond for posterior mixture with mDiamond and subsequent consolidation. In order to define optimal processing parameters, consolidation by hot extrusion has been carried out for a Cu-nDiamond composite and, in parallel, for a mixture of pure copper and mDiamond. The materials produced were characterized by X-ray diffraction, scanning and transmission electron microscopy and microhardness measurements.
Effect of Phosphogypsum on the Clinkerization Temperature of Portland Cement Clincker
Authors: Lima Maria Margarida Rolim Augusto , Braz L.F.C. , Monteiro Regina da Conceição Corredeira , Veiga J.P.
Published: November 2012

Phosphogypsum (PG) is a pollutant residue resulting from the production of phosphoric acid in the phosphated fertilizers industry. About 180 millions of tons of PG are generated worldwide per year, which originates storage problems because of the environmental restrictions and the high costs of storage spaces. Taking into account the mineralizer properties of PG it has been studied a way to valorize this residue as an alternative material in the production of Portland cement clinker. The PG and the raw-materials (limestone, marl, sand and iron oxide) were chemical, mineralogical and thermally characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and differential thermal analysis and termogravimetric analysis (DTA/TGA). After milling, the phosphogypsum was mixed with the raw-materials in different amounts up to 10% weight. The raw mixtures were submitted to two types of firing schedules, heating up to 1500°C without any holding time or heating up to 1350°C and holding for 20 minutes. After firing, the clinkers were analyzed by optical microscopy, milled and characterized in terms of chemical and mineralogical compositions. The clinkers were used to produce cement mortar according to NP EN 196-1 standard. The resultant test specimens were mechanically tested at 2 and 28 days according to the same standard. The obtained results show a reduction of about 140°C in the clinkerization temperature, when a raw mixture with 5% phosphogypsum was used. Standard clinkers, without phosphogypsum addition, which were fired at 1500°C, originated test specimens with a compressive strength of 48.1MPa at 28 days. Test specimens produced with clinker containing 5% phosphogypsum present higher compressive strength values at 28 days, being 55.1MPa for clinkers produced at 1500°C, and 49.4 MPa for clinkers produced at 1350°C.
God in de economie
Authors: Van den Hoogen Toine
Published: November 2012

God in economics? During the 20th century, in Christian churches and amongst Christian theologians a new interest was found in economics as an object of theological reflection. This article researches the nature of such theological reflection, amongst others from the critical question of how a connection can be made between a constructivist approach of theology and the analysis by today’s economic sciences of the market as an important horizon of human culture and of human communities.
Spotlights and shadows: Preliminary findings about the experiences of women in family business leadership roles
Authors: Barrett Mary , Moores Ken
Published: November 2012

In an earlier study (Moores & Barrett 2002) we found successful CEOs had learned leadership of family controlled businesses (FCBs) in a series of distinct learning phases. Because that study's sample did not include many women, our present study focuses on women in FCBs to better understand how they exercise leadership and entrepreneurship in the family firm context. Case study analysis of an international sample of women FCB leaders, using frameworks which avoid essentialist assumptions about women's and men's approach to leadership, suggests there are some characteristic ways women leaders learn FCB leadership and entrepreneurship roles. We have tentatively labelled them stumbling into the spotlight, building your own stage, directing the spotlight elsewhere, and coping with shadows. Some interviewees had failed to attain leadership; we labelled their journey becoming invisible. This paper uses Eisenhardt's (1989) framework to elaborate on the stumbling into the spotlight and coping with shadows journeys and what can be learned from them.
Dust emission size distribution impact on aerosol budget and radiative forcing over the Mediterranean region: a regional climate model approach
Authors: Nabat P. , Solmon F. , Mallet M. , Kok J. F. , Somot S.
Published: November 2012

Abstract. The present study investigates the dust emission and load over the Mediterranean basin using the coupled chemistry–aerosol–regional climate model RegCM-4. The first step of this work focuses on dust particle emission size distribution modeling. We compare a parameterization in which the emission is based on the individual kinetic energy of the aggregates striking the surface to a recent parameterization based on an analogy with the fragmentation of brittle materials. The main difference between the two dust schemes concerns the mass proportion of fine aerosol that is reduced in the case of the new dust parameterization, with consequences for optical properties. At the episodic scale, comparisons between RegCM-4 simulations, satellite and ground-based data show a clear improvement using the new dust distribution in terms of aerosol optical depth (AOD) values and geographic gradients. These results are confirmed at the seasonal scale for the investigated year 2008. This change of dust distribution has sensitive impacts on the simulated regional dust budget, notably dry dust deposition and the regional direct aerosol radiative forcing over the Mediterranean basin. In particular, we find that the new size distribution produces a higher dust deposition flux, and smaller top of atmosphere (TOA) dust radiative cooling. A multi-annual simulation is finally carried out using the new dust distribution over the period 2000–2009. The average SW radiative forcing over the Mediterranean Sea reaches −13.6 W m−2 at the surface, and −5.5 W m−2 at TOA. The LW radiative forcing is positive over the basin: 1.7 W m−2 on average over the Mediterranean Sea at the surface, and 0.6 W m−2 at TOA.
Characterization of photochemical pollution at different elevations in mountainous areas in Hong Kong
Authors: Guo H. , Ling Z. H. , Cheung K. , Jiang F. , Wang D. W. , Simpson I. J. , Wang T. J. , Wang X. M. , Saunders S. M. , Blake D. R.
Published: November 2012

Abstract. To advance our understanding on the factors that affect photochemical pollution at different elevations in mountainous areas, concurrent systematic field measurements (September to November 2010) were conducted at a mountain site and at an urban site at the foot of the mountain in Hong Kong. The mixing ratios of air pollutants were greater at the foot of the mountain (i.e. Tsuen Wan urban site, TW) than near the summit (i.e. Tai Mao Shan mountain site, TMS), except for ozone. In total, only 1 O3 episode day was observed at TW, whereas 21 O3 episode days were observed at TMS. The discrepancy of O3 at the two sites was attributed to the mixed effects of NO titration, vertical meteorological conditions, regional transport and mesoscale circulations. The lower NO levels at TMS and the smaller differences of "oxidant" Ox (O3 + NO2) than O3 between the two sites suggested that variations of O3 at the two sites were partly attributed to different degree of NO titration. In addition, analysis of vertical structure of meteorological variables revealed that the inversion layer at the range of altitudes of 500–1000 m might be another factor that caused the high O3 levels at TMS. Furthermore, analyses of the wind fields and the levels of air pollutants in different air flows indicated that high O3 concentrations at TMS were somewhat influenced by regional air masses from the highly polluted Pearl River Delta (PRD) region. In particular, the analysis of diurnal profiles and correlations of gaseous pollutants suggested influence of mesoscale circulations which was further confirmed using the Master Chemical Mechanism moving box model (Mbox) and the Weather Research and Forecasting (WRF) model. By investigating the correlations of observed O3 and NOx*, as well as the ratios of VOC/NOx, it was concluded that photochemical O3 formation was VOC-sensitive or both NOx and VOC-sensitive at TMS, while it was VOC-sensitive at TW.
The benthic foraminiferal community in a naturally CO2-rich coastal habitat of the southwestern Baltic Sea
Authors: Haynert K. , Schönfeld J. , Polovodova-Asteman I. , Thomsen J.
Published: November 2012

Abstract. It is expected that the calcification of foraminifera will be negatively affected by the ongoing acidification of the oceans. Compared to the open oceans, these organisms are subjected to much more adverse carbonate system conditions in coastal and estuarine environments such as the southwestern Baltic Sea, where benthic foraminifera are abundant. This study documents the seasonal changes of carbonate chemistry and the ensuing response of the foraminiferal community with bi-monthly resolution in Flensburg Fjord. In comparison to the surface pCO2, which is close to equilibrium with the atmosphere, we observed large seasonal fluctuations of pCO2 in the bottom and sediment pore waters. The sediment pore water pCO2 was constantly high during the entire year ranging from 1244 to 3324 μatm. Nevertheless, in contrast to the bottom water, sediment pore water was slightly supersaturated with respect to calcite as a consequence of higher alkalinity (AT) for most of the year. Foraminiferal assemblages were dominated by two calcareous species, Ammonia aomoriensis and Elphidium incertum, and the agglutinated Ammotium cassis. The one-year cycle was characterised by seasonal community shifts. Our results revealed that there is no dynamic response of foraminiferal population density and diversity to elevated sediment pore water pCO2. Surprisingly, the fluctuations of sediment pore water undersaturation (Ωcalc) co-vary with the population densities of living Ammonia aomoriensis. Further, we observed that most of the tests of living calcifying foraminifera were intact. Only Ammonia aomorienis showed dissolution and recalcification structures on the tests, especially at undersaturated conditions. Therefore, the benthic community is subjected to high pCO2 and tolerates elevated levels as long as sediment pore water remains supersaturated. Model calculations inferred that increasing atmospheric CO2 concentrations will finally lead to a perennial undersaturation in sediment pore waters. Whereas benthic foraminifera indeed may cope with a high sediment pore water pCO2, the steady undersaturation of sediment pore waters would likely cause a significant higher mortality of the dominating Ammonia aomoriensis. This shift may eventually lead to changes in the benthic foraminiferal communities in Flensburg Fjord, as well as in other regions experiencing naturally undersaturated Ωcalc levels.
Impact of CO2 and climate on Last Glacial Maximum vegetation – a factor separation
Authors: Claussen M. , Selent K. , Brovkin V. , Raddatz T. , Gayler V.
Published: November 2012

Abstract. Differences between glacial and pre-industrial potential vegetation patterns can conceptually be attributed to two factors: firstly to differences in the climate, caused by a strong increase in ice masses and the radiative effect of lower greenhouse gas concentrations, and secondly to differences in the ecophysiological effect of lower glacial atmospheric CO2 concentrations. The synergy emerging from these effects when operating simultaneously can be interpreted as sensitivity of the effect of enhancing physiologically available CO2 on shifting vegetation to climate warming. Alternatively and equally valid, it can be viewed as sensitivity of climatically induced vegetation changes to differences in physiologically available CO2. A first complete factor separation based on simulations with the MPI Earth System Model indicates that the pure climate effect mainly leads to a contraction or a shift in vegetation patterns when comparing glacial with pre-industrial simulation vegetation patterns. Globally, a reduction in fractional coverage of most plant functional types is seen – except for raingreen shrubs which strongly benefit from the colder and drier climate. The ecophysiological effect of CO2 appears to be stronger than the pure climate contribution for many plant functional types – in line with previous simulations. The ecophysiological effect of lower CO2 mainly yields a reduction in fractional coverage, a thinning of vegetation and a strong reduction in net primary production. The synergy appears to be as strong as each of the pure contributions locally. For tropical evergreen trees, the synergy appears strong also on global average. Hence this modelling study suggests that for tropical forests, an increase in CO2 has, on average, a stronger ecophysiological effect in warmer climate than in glacial climate. Alternatively, areal differences in tropical forests induced by climate warming can, on average, be expected to be larger with increasing concentration of physiologically effective CO2.
On the importance of appropriate precipitation gauge catch correction for hydrological modelling at mid to high latitudes
Authors: Stisen S. , Højberg A. L. , Troldborg L. , Refsgaard J. C. , Christensen B. S. B. , Olsen M. , Henriksen H. J.
Published: November 2012

Abstract. Precipitation gauge catch correction is often given very little attention in hydrological modelling compared to model parameter calibration. This is critical because significant precipitation biases often make the calibration exercise pointless, especially when supposedly physically-based models are in play. This study addresses the general importance of appropriate precipitation catch correction through a detailed modelling exercise. An existing precipitation gauge catch correction method addressing solid and liquid precipitation is applied, both as national mean monthly correction factors based on a historic 30 yr record and as gridded daily correction factors based on local daily observations of wind speed and temperature. The two methods, named the historic mean monthly (HMM) and the time–space variable (TSV) correction, resulted in different winter precipitation rates for the period 1990–2010. The resulting precipitation datasets were evaluated through the comprehensive Danish National Water Resources model (DK-Model), revealing major differences in both model performance and optimised model parameter sets. Simulated stream discharge is improved significantly when introducing the TSV correction, whereas the simulated hydraulic heads and multi-annual water balances performed similarly due to recalibration adjusting model parameters to compensate for input biases. The resulting optimised model parameters are much more physically plausible for the model based on the TSV correction of precipitation. A proxy-basin test where calibrated DK-Model parameters were transferred to another region without site specific calibration showed better performance for parameter values based on the TSV correction. Similarly, the performances of the TSV correction method were superior when considering two single years with a much dryer and a much wetter winter, respectively, as compared to the winters in the calibration period (differential split-sample tests). We conclude that TSV precipitation correction should be carried out for studies requiring a sound dynamic description of hydrological processes, and it is of particular importance when using hydrological models to make predictions for future climates when the snow/rain composition will differ from the past climate. This conclusion is expected to be applicable for mid to high latitudes, especially in coastal climates where winter precipitation types (solid/liquid) fluctuate significantly, causing climatological mean correction factors to be inadequate.
Is bias correction of Regional Climate Model (RCM) simulations possible for non-stationary conditions?
Authors: Teutschbein C. , Seibert J.
Published: November 2012

Abstract. In hydrological climate-change impact studies, Regional Climate Models (RCMs) are commonly used to transfer large-scale Global Climate Model (GCM) data to smaller scales and to provide more detailed regional information. However, there are often considerable biases in RCM simulations, which have led to the development of a number of bias correction approaches to provide more realistic climate simulations for impact studies. Bias correction procedures rely on the assumption that RCM biases do not change over time, because correction algorithms and their parameterizations are derived for current climate conditions and assumed to apply also for future climate conditions. This underlying assumption of bias stationarity is the main concern when using bias correction procedures. It is in principle not possible to test whether this assumption is actually fulfilled for future climate conditions. In this study, however, we demonstrate that it is possible to evaluate how well bias correction methods perform for conditions different from those used for calibration. For five Swedish catchments, several time series of RCM simulated precipitation and temperature were obtained from the ENSEMBLES data base and different commonly-used bias correction methods were applied. We then performed a differential split-sample test by dividing the data series into cold and warm respective dry and wet years. This enabled us to evaluate the performance of different bias correction procedures under systematically varying climate conditions. The differential split-sample test resulted in a large spread and a clear bias for some of the correction methods during validation years. More advanced correction methods such as distribution mapping performed relatively well even in the validation period, whereas simpler approaches resulted in the largest deviations and least reliable corrections for changed conditions. Therefore, we question the use of simple bias correction methods such as the widely used delta-change approach and linear scaling for RCM-based climate-change impact studies and recommend using higher-skill bias correction methods.
Past and future sea-level change from the surface mass balance of glaciers
Authors: Marzeion B. , Jarosch A. H. , Hofer M.
Published: November 2012

Abstract. We present estimates of sea-level change caused by the global surface mass balance of glaciers, based on the reconstruction and projection of the surface mass balance of all the individual glaciers of the world, excluding the ice sheets in Greenland and Antarctica. The model is validated using a leave-one-glacier-out cross-validation scheme against 3997 observed surface mass balances of 255 glaciers, and against 756 geodetically observed, temporally integrated volume and surface area changes of 341 glaciers. When forced with observed monthly precipitation and temperature data, the glaciers of the world are reconstructed to have lost mass corresponding to 114 ± 5 mm sea-level equivalent (SLE) between 1902 and 2009. Using projected temperature and precipitation anomalies from 15 coupled general circulation models from the Coupled Model Intercomparison Project phase 5 (CMIP5) ensemble, they are projected to lose an additional 148 ± 35 mm SLE (scenario RCP26), 166 ± 42 mm SLE (scenario RCP45), 175 ± 40 mm SLE (scenario RCP60), or 217 ± 47 mm SLE (scenario RCP85) during the 21st century. Based on the extended RCP scenarios, glaciers are projected to approach a new equilibrium towards the end of the 23rd century, after having lost either 248 ± 66 mm SLE (scenario RCP26), 313 ± 50 mm SLE (scenario RCP45), or 424 ± 46 mm SLE (scenario RCP85). Up until approximately 2100, ensemble uncertainty within each scenario is the biggest source of uncertainty for the future glacier mass loss; after that, the difference between the scenarios takes over as the biggest source of uncertainty. Ice mass loss rates are projected to peak 2040 ∼ 2050 (RCP26), 2050 ∼ 2060 (RCP45), 2070 ∼ 2090 (RCP60), or 2070 ∼ 2100 (RCP85).
Caracterização micorrízica de "Oeceoclades maculata" (LINDL.) LINDL. e utilização de seus simbiontes fúngicos na germinação e produção de mudas de orquídeas nativas da região do Alto Paranaíba – MG. DOI: 10.7902/ecb.v3i1.6
Authors: Pessoa Herika Paula , Teixeira Anita Fernanda dos Santos , Miranda Letícia , Pereira Marlon Correa
Published: November 2012

Oeceoclades maculata (Lindl.) Lindl. pertence à família Orchidaceae e, como as demais plantas dessa família, necessita da interação com fungos micorrízicos para que a germinação de suas sementes ocorra na natureza. Várias populações de O. maculata foram encontradas no município de Rio Paranaíba, o qual está inserido no bioma do Cerrado. Não há relatos de estudos da associação micorrízica para plantas deste bioma. Este trabalho teve como objetivo caracterizar a associação micorrízica de O. maculata a partir do isolamento, caracterização morfológica e identificação dos fungos micorrízicos associados a seu sistema radicular e testar a compatibilidade dos isolados na germinação de Cattleya walkeriana Gardner, Dendrobium nobile Lindl., O. maculatta e Sophronitis cernua Lindl., orquídeas encontradas no Cerrado. Isolou-se 44 fungos, que foram organizados em nove morfotipos e identificados como Fusarium sp., Rhizoctonia-like e Basideomicetes. Alguns destes fungos se mostraram eficientes na germinação, podendo ser utilizados na produção de mudas destas plantas.
Effect of the Substituents of the Neighboring Ring in the Conformational Equilibrium of Iduronate in Heparin‐like Trisaccharides
Authors: Muñoz‐García Juan Carlos , López‐Prados Javier , Angulo Jesús , Díaz‐Contreras Irene , Reichardt Niels , de Paz José L. , Martín‐Lomas Manuel , Nieto Pedro M.
Published: November 2012

Based on the structure of the regular heparin, we have prepared a smart library of heparin‐like trisaccharides by incorporating some sulfate groups in the sequence α‐D‐GlcNS‐ (1‐4)‐α‐L‐Ido2S‐(1‐4)‐α‐D‐GlcN. According to the 3D structure of heparin, which features one helix turn every four residues, this fragment corresponds to the minimum binding motif. We have performed a complete NMR study and found that the trisaccharides have a similar 3D structure to regular heparin itself, but their spectral properties are such that allow to extract very detailed information about distances and coupling constants as they are isotropic molecules. The characteristic conformational equilibrium of the central iduronate ring has been analyzed combining NMR and molecular dynamics and the populations of the conformers of the central iduronate ring have been calculated. We have found that in those compounds lacking the sulfate group at position 6 of the reducing end glucosamine, the population of 2S0 of the central iduronate residue is sensitive to the temperature decreasing to 19 % at 278 K. On the contrary, the trisaccharides with 6‐O‐sulfate in the reducing end glucosamine keep the level of population constant with temperature circa 40 % of 2S0 similar to that observed at room temperature. Another structural feature that has been revealed through this analysis is the larger flexibility of the L‐IdoAS‐ D‐GlcN glycosidic linkage, compared with the D‐GlcNS‐L‐IdoA. We propose that this is the point where the heparin chain is bended to form structures far from the regular helix known as kink that have been proposed to play an important role in the specificity of the heparin–protein interaction.
Phytoremediation of Pyrene Contaminated Soils by Different Plant Species
Authors: D'Orazio Valeria , Ghanem Alaà , Senesi Nicola
Published: November 2012

Polycyclic aromatic hydrocarbons (PAHs) present serious problems in the environment because they may affect negatively human health and alter native ecological communities. Phytoremediation has long been recognized as an efficient method of eliminating PAH pollutants from soil. A pot experiment was conducted in greenhouse conditions to investigate the capability of three plant species, Medicago sativa, Brassica napus, and Lolium perenne, to promote the degradation of pyrene by measuring their growth on pyrene‐contaminated soils. After 90 days, pyrene concentration in soils declined by 32, 30, and 28%, respectively, with M. sativa, B. napus, and L. perenne, whereas it decreased only by 18% in the control soil without plants. These results indicated that pyrene was successfully removed by plants used. In particular, M. sativa showed the highest capacity for pyrene dissipation in soil, whereas L. perenne was more efficient in limiting adverse effects of pyrene contamination. In addition, the contaminant pyrene was undetectable in shoots and roots of the three species, likely because plant roots can stimulate soil microbial biomass and oxygen transport to the rhizosphere, thus facilitating indirectly the degradation process of pyrene. Further studies are in progress to evaluate the possible adsorption of pyrene to soil organic matter.
Control of ZnO Nanostructures via Vapor Transport
Authors: Modeshia Deena R. , Dunnill Charles W. , Suzuki Yuji , Al‐Ghamdi Ahmed A. , El‐Mossalamy Elsayed H. , Obaid Abdullah Y. , Basahel Sulaiman N. , Alyoubi Abdulrahman O. , Parkin Ivan. P.
Published: November 2012

An adapted form of vapor transport is used for the preparation of zinc oxide (ZnO) nanostructures. Control of substrate, partial pressure, temperature, and deposition time enable the synthesis of seven ZnO samples, each with different morphology. Characterization by X‐ray diffraction (XRD), photoluminescence spectroscopy (PLS), and scanning electron microscopy (SEM) shows ZnO forms with a wide range of microstructures such as “nano‐stars”, “nano‐caterpillars”, urchin‐like structures, and vertically aligned forests of hexagonal nanorods. Adopting a systematic approach of varying a single parameter from the standard experimental method, enables an understanding of why the resultant morphologies are obtained. In particular, a growth mechanism is proposed whereby hexagonal crystals grow from the catalytic substrate consisting of gold droplets, close to, or at, the melting temperature, supersaturated with zinc and oxygen, allowing propagation of hexagonal “parent” pillars. Parent pillars then form “daughter” rods which propagate sideways from the faces with angles tending towards 60° from each other.
Label‐free aptamer‐based partial filling technique for enantioseparation and determination of dl‐tryptophan with micellar electrokinetic chromatography
Authors: Huang Rong , Xiong Wenming , Wang Daifang , Guo Longhua , Lin Zhenyu , Yu Lishuang , Chu Kedan , Qiu Bin , Chen Guonan
Published: November 2012

In this study, a simple and reproducible method for enantioseparation and determination of dl‐tryptophan (dl‐Trp) was developed by using a partial filling technique in combination with MEKC. The corresponding l‐Trp specific DNA aptamer was used as a chiral selector. Sodium cholate was used to form the chiral micelles and to enhance the enantioseparation of the enantiomers. Effects of aptamer concentration, filling time, buffer composition, and separation voltage on the enantioseparation were evaluated. The Mg2+ and Na+ concentration in separation buffer was found to effectively affect the separation efficiency and reproducibility. Under the optimal conditions, d‐ and l‐Trp were completely enantioseparated in less than 9 min. This aptamer‐based partial‐filling approach has the potential to be extended to the separation of other enantiomers after the replacement of corresponding specific aptamers.
Reconstructing 2 x 2 contingency tables from odds ratios using the Di Pietrantonj method: difficulties, constraints and impact in meta‐analysis results
Authors: Veroniki Areti Angeliki , Pavlides Marios , Patsopoulos Nikolaos A , Salanti Georgia
Published: November 2012

A problem that is frequently encountered during the systematic review process is when studies that meet the inclusion criteria do not provide the appropriate numerical estimates to include in a meta‐analysis. For dichotomous outcomes, a method has been suggested by Di Pietrantonj for reconstructing the 2 × 2 table when the Odds Ratio (OR), the Standard Error (SE(lnOR)) and the sample sizes are provided. The method produces two possible 2 × 2 tables; and to select the correct one, the Control Group Risk (CGR) is used. As CGR is typically unknown and only rounded figures of the OR and SE(lnOR) are provided, the accuracy of the reconstruction method varies. In this paper, we evaluate the performance of the method using simulated and empirical data. Small studies with large OR and CGR away from 50% are reconstructed satisfactorily, and the use of SE(lnOR) rounded to the third decimal rather than the second one improves the performance of the method. However, when CGR is unknown, its estimation from other studies is problematic as it exhibits high heterogeneity. Inclusion of an incorrectly reconstructed table in the meta‐analysis may result in different summary effects. Reviewers that consider applying the method should be cautious about its impact in the meta‐analysis. Copyright © 2012 John Wiley & Sons, Ltd.
Rate constants for the reactions of Cl atoms with a series of C6–C10 cycloalkanes and cycloketones at 297 ± 2 K
Authors: Aschmann Sara M. , Atkinson Roger
Published: November 2012

Rate constants for the reactions of Cl atoms with cycloheptane, cyclooctane, cyclodecane, cyclohexanone, cycloheptanone, cyclooctanone, and cyclodecanone have been measured at 297 ± 2 K and atmospheric pressure of air using a relative rate method. n‐Butane, with a rate constant of 2.05 × 10−10 cm3 molecule−1 s−1, was used as the reference compound, and the rate constants obtained (in units of 10−10 cm3 molecule−1 s−1) were cycloheptane, 4.22 ± 0.15; cyclooctane, 4.57 ± 0.15; cyclodecane, 5.13 ± 0.15; cyclohexanone, 1.79 ± 0.06; cycloheptanone, 2.46 ± 0.07; cyclooctanone, 2.97 ± 0.09; and cyclodecanone, 3.65 ± 0.15, where the indicated errors are two least‐squares standard deviations and do not include uncertainties in the rate constant for the reference compound n‐butane. Room temperature rate constants for the C5–C10 cycloketones indicate that the CH2 groups adjacent to the carbonyl group are almost totally deactivated toward H‐atom abstraction by Cl atoms, and this also applies to acyclic ketones. A previous structure–reactivity relationship for Cl + alkanes has been extended to include acyclic and cyclic ketones. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 52–58, 2013
Combination with genistein enhances the efficacy of photodynamic therapy against human anaplastic thyroid cancer cells
Authors: Ahn Jin‐Chul , Biswas Raktim , Chung Phil‐Sang
Published: November 2012

Background and Objective

Photodynamic therapy (PDT) has become one of the emerging options in management of cancer and other diseases. The major goal of PDT is to kill cancer cell without causing any adverse effect to the normal cells. PDT in combination of different therapeutic agents is being evaluated to improve the efficacy of treatment. Genistein, a soy ingredient, has widely been studied against different types of cancer. In the present study, combination of these two therapeutic methods has been studied to evaluate the enhanced effectiveness and find out the mechanism of action.

Materials and Methods

Combination of PDT and genistein has been studied against human thyroid cancer cells SNU 80. Cells were treated with genistein and different concentration of photofrin in PDT singly and conjointly. Viability of SNU 80 cells was analyzed using MTT assay. The cells were stained with Hoechst 33342 and propidium iodide (PI) for morphological observations. Changes in mitochondrial membrane potential and generation of reactive oxygen species (ROS) were also studied by confocal microscopy. Western blot analysis were also performed to find out the expressions of different pro‐ and anti‐apoptotic proteins.

Results

From the result, the combination of genistein and photofrin mediated PDT enhanced the apoptotic effect against SNU 80 cells. Proliferation of the cells was inhibited and the mitochondrial membrane depolarisation was observed. ROS level were also increased in combination treatment. The expressions of Caspase 3, Caspase 9, cytochrome c, Caspase 8, Caspae 12 and other apoptosis related proteins were also modified.

Conclusion

Thus PDT can induce apoptosis in thyroid cancer cells singly or in combination with genistein. But in combination treatment, the efficacy of inducing apoptosis in SNU 80 cells is much higher than that of individual treatment with genistein or PDT. Lasers Surg. Med. 44: 840–849, 2012. © 2012 Wiley Periodicals, Inc.
The effects of monetary and social rewards on task performance in children and adolescents: Liking is not enough
Authors: Demurie Ellen , Roeyers Herbert , Baeyens Dieter , Sonuga‐Barke Edmund
Published: November 2012

The current study compared the effects of reward anticipation on task performance in children and adolescents (8–16 years old) using monetary and various social rewards. Eighty‐five typically developing children undertook the Monetary Incentive Delay (MID) task. Of these 44 also undertook the Social Incentive Delay (SID‐basic) task where social reward was operationalized as a smiling face and spoken compliments. Forty‐one children participated in the SID‐plus where points were added to a pictogram with written compliments. In a preparatory validation study participants were asked howmuch they liked the SID‐basic rewards.Results showed that there was an effect of reward size on accuracy and RT in both the MID task and SID‐plus, but not SID‐basic. Subjective value of the SID‐basic rewards was rated higher with hypothesized increasing reward intensity. In conclusion, although the social rewards in SID‐basic were liked by children andadolescents in the validation study, they had no effect on the behaviour. Only when points were added (SID‐plus), anticipated social reward affected task performance. Thus our results highlight (i) the difference between likeability andreinforcing quality and (ii) the need for a quantifiable element to rewards for themto be reinforcing for children. Copyright © 2012 John Wiley & Sons, Ltd.
Laser‐doped solar cells exceeding 18% efficiency on large‐area commercial‐grade multicrystalline silicon substrates
Authors: Li Tao , Wang Wenjing , Zhou Chunlan , Song Yang , Duan Ye , Li Youzhong
Published: November 2012

Large‐area multicrystalline silicon solar cells fabrication by laser doping is studied in this paper. The liquid dopant solution is sprayed onto the SiNx:H film to act as dopant source. Laser doping is performed to locally melt silicon substrates, and phosphorus dopant atoms are incorporated into the liquid silicon by liquid‐phase diffusion to form a selective emitter. Light‐induced plating is carried out for front side metallization. The influences of laser energy density and pulse overlap on electrical performance of large‐area multicrystalline silicon solar cells are obtained. The laser energy density and pulse overlap are optimized in consideration of sufficient built‐in voltage and small‐scale laser‐induced damage. The typical spectral response for large‐area multicrystalline silicon solar cells by laser doping is presented. The typical efficiency distribution for 1‐day production of the 10 MW production line shows the overall average efficiency above 18% on large‐area commercial‐grade multicrystalline silicon substrates for the 4 months of operation, confirming the potential for transferring high‐efficiency selective emitter silicon solar cells by laser doping into a production line. Copyright © 2012 John Wiley & Sons, Ltd.
Fast and reliable calculation of the two‐diode model without simplifications
Authors: Suckow Stephan , Pletzer Tobias M. , Kurz Heinrich
Published: November 2012

An algorithm to calculate the current in the two‐diode equivalent circuit of a solar cell is described and characterized in detail. It enables fitting measured current–voltage characteristics with hundreds of voltage points and six fit parameters at practically instantaneous speeds and can handle thousands of voltage points within a few seconds, without simplifications of the two‐diode model. This performance enables routine two‐diode model parameter extraction at in‐line speeds, which may help to enhance cell characterization for module integration. The source code is publicly available. Copyright © 2012 John Wiley & Sons, Ltd.