bluuebunny/crossref_metadata_2025 huggingface dataset:
Auger Electron Spectroscopic and Electrochemical Analysis of the Effect of Alloying Elements on the Passivation Behavior of Stainless Steels
Authors: OGAWA HIROYUKI , OMATA HIROYASU , ITOH ISAO , OKADA HIDEYA
Published: February 2013

This investigation is concerned with the effect of chromium and molybdenum on the formation of the passive film of stainless steels, and its corrosion resistance to the chloride ion. The corrosion resistance to the chloride ion was estimated by the potential decay method and the measurement of the anodic polarization curve. The composition analysis of the passive film was performed by Auger Electron Spectroscopic Analysis. The following conclusions were obtained from the test results: (1) The passive film was more resistant in the environment containing chloride ions as the chromium content in the passive film increased, and (2) molybdenum was observed on AES analysis to have an effect on the increment of the chromium content in the passive film and to promote the passive film formation of stainless steels, probably adsorbing on the active metal surface in the form of molybdate.
The Structure of Iron-Carboxylic Acid Surface Films
Authors: Wood J. C.
Published: February 2013

XPS has been used to study the nature of the films formed on Fe surfaces by molecules containing the —COOH grouping. The corrosion inhibitive properties of these films in SO2 containing atmospheres is related both to the nature of the adsorption bond and to the orientation of the molecule on the surface.
Stress Corrosion Cracking of Low Strength, Low Alloy Nickel Steels in Sulfide Environments
Authors: DUNLOP A. K.
Published: February 2013

Factors governing stress corrosion cracking (SCC) of low strength, low alloy nickel steels (e.g., ASTM A203 Grade E) in sulfide environments were investigated using a three point loaded bent beam specimen. Cracking occurred in both weld and base metal at low H2S partial pressures (to 0.001 atmosphere) and stress levels, but could be inhibited by a neutralizing amine (morpholine) and methanol addition as used for control of ice and hydrate formation in cryogenic gas plants. Cathodic polarization experiments showed cracking was retarded under these conditions. This indicates the cracking phenomenon involved is not that of hydrogen embrittlement (i.e., sulfide stress cracking) as has been heretofore assumed, but involves localized anodic attack as does the cracking of other low strength alloys in environments such as nitrate, caustic, CO/CO2, etc. Sulfide corrosion stress cracking (SCSC) is suggested as a term for this type of localized anodic cracking attack in sulfide environments.
Continuous Cooling Sensitization of Type 304 Stainless Steel
Authors: SOLOMON H. D.
Published: February 2013

This study compares the sensitization of one heat of Type 304 stainless steel by isothermal heat treatments and by continuously cooling through the sensitization region. Predictions of the continuous cooling sensitization (CCS) based upon the isothermal data underestimate the severity of CCS but are within an order of magnitude in their accuracy. Furthermore, the isothermal tests failed to predict a strong influence of the peak temperature of a CCS cycle, when this peak temperature is above that required for isothermal sensitization. CCS is more severe (i.e., occurs at higher cooling rates) when the maximum temperature of the cycle is 800 or 900 C than when it is 1000 or 1100 C. It is also shown that the sensitization observed after the application of more than one thermal cycle cannot be predicted by simply adding the influence of the individual cycles.
Evaluation of Sulfide SCC Resistance of High Strength Steels by the Constant-Strain-Rate Method
Authors: LYLE F. F. , NORRIS E. B.
Published: February 2013

This paper presents a description of application of constant strain rate test to evaluation of stress corrosion cracking (SCC) resistance of engineering alloys, in general, and to oil field materials exposed to H2S environments, in particular. Tests to discriminate between susceptible and nonsusceptible low alloy steels exposed to an H2S-CO2 environment and to determine the temperature at which the alloy (in a specific heat treat condition) becomes immune to SCC are described.
Stress Corrosion Cracking of C-Mn Steel in Phosphate Solutions
Authors: PARKINS R. N. , HOLROYD N. J. H. , FESSLER R. R.
Published: February 2013

Annealed C-Mn steel has been shown to fail by transgranular stress corrosion cracking (SCC) in sodium phosphate solutions over a range of potentials and pH's at room temperature. The observed SCC domain is reasonably accurately predicted from fast and slow sweep rate polarization curves. Moreover, the cracking domain boundaries can be calculated with reasonable precision from the thermodynamic properties of the reactants and products involved in the reactions responsible for the various modes of failure at different potentials and pH's.
Hydride Phases in Austenitic Stainless Steels
Authors: SZUMMER A. , JANKO A.
Published: February 2013

Electrolytic charging of austenitic stainless steels with hydrogen induces formation of two distinct alloy hydride phases, both being unstable under normal atmospheric conditions. One of the new phases denoted Hγ, has the same Bravais lattice as austenite (fcc), whereas another, denoted Hε, exhibits an hcp structure. Compared with hydrogen-free austenite and ε-martensite, respectively, the lattice constants of hydride phases are larger by about 5%. During charging of austenitic stainless steels with hydrogen evolved electrolytically from promoter containing acid solutions, these hydrides form a hard and brittle surface layer, several μm thick with numerous microcracks, and it is probable that these hydride phases play an important role during stress corrosion cracking (SCC) of austenitic stainless steels.
Corrosion by Alternating Current: A Study of the Anodic Polarization of Mild Steel in Na2SO4 Solution
Authors: CHIN D-T. , FU T-W.
Published: February 2013

A study has been made of the anodic polarization of mild steel in Na2SO4 solutions (pH 3-9) in the presence of a sinusoidal electric current. The measurement was carried out over a range of alternating current (AC) densities from 0 to 200 mA/c2 and AC frequencies from 20 to 6000 Hz. It was found that the corrosion potential of mild steel shifted toward the active direction in the presence of AC. The magnitude of the potential shift increased with increasing AC densities, and decreased with AC frequencies. AC also increased the passivity current density in a way similar to the addition of chloride ions to the electrolyte. The phenomenon was explained with a time-averaging analysis of the mixed potential theory.
Effects of Cyclic Tensile Loading on Stress Corrosion Cracking Susceptibility for Sensitized Type 304 Stainless Steel in 290 C High Purity Water
Authors: TAKAKU HIROSHI , TOKIWAI MORIYASU , HIRANO HIDEO
Published: February 2013

The effects of load waveform on intergranular stress corrosion cracking (IGSCC) susceptibility have been examined for sensitized Type 304 stainless steels in a 290 C high purity water loop. Concerning the strain rate in the trapezoidal stress waveform, it was found that IGSCC susceptibility was higher for smaller values of the strain rate. It was also shown that IGSCC susceptibility became higher when the holding time at the upper stress was prolonged, and when the upper stress was high. The occurrence of IGSCC for sensitized Type 304 stainless steel became easy due to the application of cyclic tensile stress in 290 C high purity water.
An Apparatus for the Examination of Localized Corrosion Behavior
Authors: GAINER L J. , WALLWORK G. R.
Published: February 2013

A potential measuring device has been developed which allows the distribution of potential on a specimen surface to be determined and displayed and at the same time the levels of potential to be recorded. This equipment permits the study of corrosion on metallic surfaces under well defined environmental conditions and the direct study of the origin and propagation of pits in metals. The electrochemical data is related to the metallurgical features of the metallic surface.
Sulfide Induced Corrosion of Copper Nickel Alloys
Authors: GUDAS JOHN P. , HACK HARVEY P.
Published: February 2013

The susceptibility of Cu-Ni alloys to accelerated corrosion in sea water containing low sulfide concentrations has been investigated. Test alloys included wrought 90/10 Cu-Ni, 70/30 Cu-Ni and Ni-Cu, plus cast 70/30 Cu-Ni. Sheet type specimen exposures were performed in fresh flowing sea water at a test velocity of 2.4 m/s (8 ft/s), and simultaneous polarization resistance cell exposures were conducted at a test velocity of 1.2 m/s (4 ft/s). Sulfide concentrations included 0.01, 0.05, and 0.2 ppm from addition of Na2S to flowing sea water. The test sequence included continuous sulfide exposures ranging from 1 to 1 5 days, followed by 60 days exposure in natural sea water. Gravimetric corrosion rates, depth of attack, corrosion potentials, and instantaneous corrosion rate data were developed. Results showed that wrought 90/10 Cu-Ni was susceptible to accelerated attack in sea water containing 0.01 ppm sulfides and is attacked vigorously after exposure to 0.2 ppm sulfides in sea water. Wrought 70/30 Cu-Ni is similarly susceptible to sulfide induced pitting, but appears to require higher sulfide concentration to trigger attack. Cast 70/30 Cu-Ni and Ni-Cu are susceptible to accelerated corrosion in sulfide modified sea water, but modes of attack differ from wrought 90/10 and 70/30 Cu-Ni. Interaction of exposure (or system operating) variables is seen as a key factor in assessing susceptibility of Cu-Ni alloys to sulfide induced corrosion.
Hydrogen Induced Fracture of a High Strength Aluminum Alloy
Authors: KOCH G. H.
Published: February 2013

A fractographic study has been carried out on intergranular and transgranular cracks produced in the commercial aluminum alloy 7075 in a 3% NaCI aqueous solution and in ionized hydrogen gas. It has been demonstrated that fracture in both environments is similar, suggesting a common mechanism of crack growth. It is concluded that stress corrosion cracking (SCC) is mechanical and involves hydrogen generated by the aqueous solution.
The Kinetics and Mechanism of Formation of Calcium Sulfate Scale Minerals—The Influence of Inhibitors
Authors: NANCOLLAS GEORGE H. , WHITE WESLEY , TSAI FELIX , LOW LARRY MAS
Published: February 2013

A seeded growth method has been used to study the kinetics of crystallization of calcium sulfate dihydrate at various temperatures and at ionic strengths up to 0.6M. Under all conditions, the rate of reaction is proportional to the square of the relative supersaturation and is controlled by a surface process. The same kinetics are applicable for the growth of calcium sulfate hemihydrate at temperatures above 110 C. The organic phosphonates effectively retard scale formation, and diethylenetriaminepenta (methylenephosphonic acid), when present at a concentration as low as 10−7M, completely inhibits the growth of calicum sulfate hemihydrate at 120 C. By assuming that the inhibitor molecules are adsorbed on growth sites on the surface of the crystals, the inhibition can be interpreted in terms of a simple Langmuir adsorption isotherm.
High Temperature Scaling of Monophase Nickel-Titanium Alloys
Authors: GESMUNDO F. , NANNI P. , VIANI F.
Published: February 2013

The oxidation of Ni-rich nickel-titanium solid solutions has been studied in the 950 to 1250 C range. Titanium additions decrease the oxidation resistance of nickel to an extent depending on the Ti content and temperature. Essentially monophase NiO scales are formed on a dilute alloy (1.60 Wt% Ti), with a small concentration of dissolved titanium and few isolated particles of NiTiO3. At higher titanium concentrations (7.64 Wt% Ti), the scale contains NiO in the outer region and TiO2 or NiTiO3 in the inner part. After a long oxidation time, NiO begins to grow also at the scale surface beneath the Ti-rich layer, due to a strong Ti depletion of the alloy matrix. Extensive internal oxidation is also observed under any condition.
Stress Corrosion of Steam Turbine Disc and Rotor Steels
Authors: ROBERTS B. W. , GREENFIELD P.
Published: February 2013

A range of low alloy steels, commonly used in the construction of steam turbines, has been tested for susceptibility to stress corrosion cracking (SCC) in pure condensing steam and pure water. It has been shown that when tested for prolonged periods, the steels will initiate cracks in steam only at very high stresses. Initiation is promoted by stagnant conditions and retarded by residual compressive stresses. Propagation rates of cracks are low but increase as the strength level of the steel is raised. A low strength molybdenum free steel is much more resistant to stress corrosion than any of the other steels examined.
Corrosion of Copper-Nickel Alloys in Sea Water Polluted with Sulfide and Sulfide Oxidation Products
Authors: SYRETT B. C. , MACDONALD D. D. , WING S. S.
Published: February 2013

The corrosion rates of copper alloys 706 (90:10 Cu:Ni) and 715 (70:30 Cu:Ni) were measured, using rotating cylinder specimens in sea water that contained oxygen, sulfide, sulfur, and polysulfide, either singly or in combination. In addition a control test was performed using unpolluted deaerated sea water. Corrosion rates were monitored for over 24 hours, using linear polarization and potential step techniques. The work has shown that copper-nickel alloys can corrode quite rapidly in deaerated sea water if these normally “passive” alloys are made active by the presence of sulfide, or if sulfur is available as an oxidant.
Galvanic Corrosion of Aluminum
Authors: REBOUL M. C.
Published: February 2013

Laboratory tests were carried out to compare the electrochemical characteristics of galvanic couples made of aluminum alloys (1050, 5086, 2024, and 7075) with other metals (plain steel, Type 316 stainless steel, titanium) in tap water and in artificial sea water. It was found that: One must first choose materials which individually resist corrosion. Only when this requirement is fulfilled can the risk of galvanic corrosion be evaluated. In aluminum-steel assemblies, taking into account only the risk of galvanic corrosion leads to the following bad choices: (1) the choice of copper containing aluminum alloys which are less anodic than copper free alloys (poor choice except when justified by mechanical factors),and (2) the choice of plain steel which is less noble than stainless steel. Although they generate weaker galvanic currents, field tests show that those assemblies made of corrosive materials have shorter life than stainless steel assembled with a copper free aluminum alloy. The galvanic current produced by the couple decreases rapidly with time, then stabilizes within a few days. The comparison of these stabilized currents seems to be the best way to compare the risks of galvanic corrosion. For a given couple of different metals, the life span of the assembly depends upon the conductivity and the aggressiveness of the environment; in other words the complexity and the cost of the protection to be used, for a given couple increase with the aggressiveness of the environment.
Information Stickiness in General Equilibrium and Endogenous Cycles
Authors: Gomes Orlando
Published: February 2013

Traditionally, observed fluctuations in aggregate economic time series have been mainly modeled as being the result of exogenous disturbances. A better understanding of macroeconomic phenomena, however, surely requires looking directly at the relations between variables that may trigger endogenous nonlinearities. Several attempts to justify endogenous business cycles have appeared in the literature in the last few years, involving many types of different settings. This paper intends to contribute to such literature by investigating how we can modify the well-known information stickiness macro model, through the introduction of a couple of reasonable new assumptions, in order to trigger the emergence of endogenous fluctuations.
Towards better error statistics for atmospheric inversions of methane surface fluxes
Authors: Berchet A. , Pison I. , Chevallier F. , Bousquet P. , Conil S. , Geever M. , Laurila T. , Lavrič J. , Lopez M. , Moncrieff J. , Necki J. , Ramonet M. , Schmidt M. , Steinbacher M. , Tarniewicz J.
Published: February 2013

Abstract. In this study, we adapt general statistical methods to compute the optimal error covariance matrices in a regional inversion system inferring methane surface emissions from atmospheric concentrations. We optimally estimate the error statistics with a minimal set of physical hypotheses on the patterns of errors. With this very general approach applied within a real-data framework, we recover sources of errors in the observations and in the prior state of the system that are consistent with expert knowledge. By not assuming any specific error patterns, our results show the variability and the inter-dependency of errors induced by complex factors such as the mis-representation of the observations in the transport model or the inability of the model to reproduce well the situations of steep gradients of air mass composition in the atmosphere. By analyzing the sensitivity of the inversion to each observation, ways to improve data selection in regional inversions are also proposed. We applied our method to a recent significant accidental methane release from an offshore platform in the North Sea.
Modeling the present and future impact of aviation on climate: an AOGCM approach with online coupled chemistry
Authors: Huszar P. , Teyssèdre H. , Cariolle D. , Olivié D. J. L. , Michou M. , Saint-Martin D. , Senesi S. , Voldoire A. , Salas D. , Alias A. , Karcher F. , Ricaud P. , Halenka T.
Published: February 2013

Abstract. This work assesses the impact of emissions from global aviation on climate, while focus is given on the temperature response. Our work is among the first that use an Atmosphere Ocean General Circulation Model (AOGCM) online coupled with stratospheric chemistry and the chemistry of mid-troposphere relevant for aviation emissions. Compared to previous studies where either the chemical effects of aviation emissions were investigated using global chemistry transport models or the climate impact of aviation was under focus implementing prescribed perturbation fields or simplified chemistry schemes, our study uses emissions as inputs and provides the climate response as output. The model we use is the Météo-France CNRM-CM5.1 earth system model extended with the REPROBUS stratospheric scheme. The timehorizon of our interest is 1940–2100 assuming the A1B SRES scenario. We investigate the present and future impact of the most relevant aviation emissions (CO2, NOx, contrail and contrail induced cirrus – CIC) as well as the impact of the non-CO2 emissions and the "Total" aviation impact. Aviation produced aerosol is not considered in the study. The general conclusion is that the aviation emissions result in a less pronounced climate signal than previous studies suggest. Moreover this signal is more unique at higher altitudes (above the mid-troposphere) than near the surface. The global averaged near surface CO2 impact reaches around 0.1 °C by the end of the 21st century and can be even negative in the middle of the century. The non-CO2 impact remains positive during the whole 21st century reaching 0.2 °C in its second half. A similar warming is calculated for the CIC effect. The NOx emissions impact is almost negligible in our simulations, as the aviation induced ozone production was small in the model's chemical scheme. As a consequence the non-CO2 signal is very similar to the CIC signal. The seasonal analysis showed that the strongest warming due to aviation is modeled for the late summer and early autumn months. A much less significant warming is calculated for the winter months. In the stratosphere, significant cooling is attributed to aviation CO2 emissions which reaches −0.25 °C by the end of the 21st century. A −0.3 °C temperature decrease is modeled when considering all the aviation emissions as well, but no significant signal is coming with CIC and NOx emissions in the stratosphere.
Glacial-interglacial variability in ocean oxygen and phosphorus in a global biogeochemical model
Authors:   V Palastanga, Slomp C. P. , Heinze C.
Published: February 2013

Abstract. Increased transfer of particulate matter from continental shelves to the open ocean during glacials may have had a major impact on the biogeochemistry of the ocean. Here, we assess the response of the coupled oceanic cycles of oxygen, carbon, phosphorus, and iron to the input of particulate organic carbon and reactive phosphorus from shelves. We use a biogeochemical ocean model and specifically focus on the Last Glacial Maximum (LGM). When compared to an interglacial reference run, our glacial scenario with shelf input shows major increases in ocean productivity and phosphorus burial, while mean deep-water oxygen concentrations decline. There is a downward expansion of the oxygen minimum zones (OMZs) in the Atlantic and Indian Ocean, while the extension of the OMZ in the Pacific is slightly reduced. Oxygen concentrations below 2000 m also decline but bottom waters do not become anoxic. The model simulations show when shelf input of particulate organic matter and particulate reactive P is considered, low oxygen areas in the glacial ocean expand, but concentrations are not low enough to generate wide scale changes in sediment biogeochemistry and sedimentary phosphorus recycling. Increased reactive phosphorus burial in the open ocean during the LGM in the model is related to dust input, notably over the southwest Atlantic and northwest Pacific, whereas input of material from shelves explains higher burial fluxes in continental slope and rise regions. Our model results are in qualitative agreement with available data and reproduce the strong spatial differences in the response of phosphorus burial to glacial-interglacial change. Our model results also highlight the need for additional sediment core records from all ocean basins to allow further insight into changes in phosphorus, carbon and oxygen dynamics in the ocean on glacial-interglacial timescales.
Phytoplankton community structure in the Lena Delta (Siberia, Russia) in relation to hydrography
Authors: Kraberg A. C. , Druzhkova E. , Heim B. , Loeder M. J. G. , Wiltshire K. H.
Published: February 2013

Abstract. The Lena Delta in Northern Siberia is one of the largest river deltas in the world. During peak discharge, after the ice melt in spring, it delivers between 60–8000 m3s−1 of water and sediment into the Arctic Ocean. The Lena Delta and the Laptev Sea coast also constitute a~continuous permafrost region. Ongoing climate change, which is particularly pronounced in the Arctic, is leading to increased rates of permafrost thaw. This is likely to profoundly change the discharge rates of the Lena River and the chemistry of the river waters which are discharged into the coastal Laptev Sea, e.g. by increasing concentrations of inorganic nutrients, DOC and importantly methane. These physical and chemical changes will also affect the composition of and interactions between phytoplankton and zooplankton communities, forming the basis of the food web. However, before potential consequences of climate change for coastal arctic plankton communities can be judged, the inherent status of the diversity and linked foodweb interactions within the delta need to be established. As part of the AWI Lena Delta Programme in 2010 the phyto- and microzooplankton community in three river channels as well as four coastal transects were investigated to capture the typical river phytoplankton communities and the transitional zone of brackish/marine conditions. Most CTD profiles from 23 coastal stations showed very strong stratification. The only exception to this was a small a shallow and mixed area running from the outflow of Bykovskaya channel in a northerly direction parallel to the shore (transect 3). Of the five stations in this area three had a salinity of close to zero. Two further stations had salinities of around 2 and 5 throughout the water column. In the remaining transects on the other hand salinities varied between 5–30 with depth. Phytoplankton counts from the outflow from the Lena were dominated by diatoms (Aulacoseira species) cyanobacteria (Aphanizomenon, Pseudanabaena) and chlorophytes, in those stations characterized by river outflow (stations in the Lena itself and in coastal transect 3). In contrast in the stratified stations the plankton was mostly dominated by dinoflagellates, ciliates and nanoflagellates, with only an insignificant diatom component from the genera Chaetoceros and Thalassiosira (brackish as opposed to freshwater species). Ciliate abundance was significantly coupled with the abundance of total flagellates. A pronounced partitioning in the phytoplankton community was also discernible with depth, with a different community composition and abundance above and below the thermocline in the stratified sites. This work represents the first attempt at analyzing the phytoplankton structure of the region of freshwater influence at confluence Lena–Laptev sea.
Fukushima-derived radiocesium in western North Pacific sediment traps
Authors: Honda M. C. , Kawakami H. , Watanabe S. , Saino T.
Published: February 2013

Abstract. At two stations in the western North Pacific, K2 in the subarctic gyre and S1 in the subtropical gyre, time-series sediment traps were collecting sinking particles when the Fukushima Daiichi Nuclear Power Plant (FNPP1) accident occurred on 11 March 2011. Radiocesium (134Cs and 137Cs) derived from FNPP1 accident was detected in sinking particles collected at 500 m by late March 2011 and at 4810 m by early April 2011 at both stations. The sinking velocity of 134Cs and 137Cs was estimated to be 8 to 36 m day−1 between the surface and 500 m and > 180 m day−1 between 500 m and 4810 m. 137Cs specific activity varied from 0.14 to 0.25 Bq g−1 dry weight. These values are higher than those of surface seawater, suspended particles, and zooplankton collected in April 2011. Although the radiocesium may have been adsorbed onto or incorporated into clay minerals, correlations between 134Cs and lithogenic material were not always significant; therefore, the form of the cesium associated with the sinking particles is still an open question. The total 137Cs flux by late June at K2 and by late July at S1 was 0.5 to 1.7 Bq m−2 at both depths. Compared with 137Cs input to both stations by April 2011, estimated from the surface 137Cs activity and mixed layer depth and by assuming that the observed 137Cs flux was constant throughout the year, the estimated removal rate of 137Cs from the upper layer (residence time in the upper layer) was 0.3 to 1.5% (68 to 312 yr). The estimated removal rates and residence times are comparable to previously reported values.
The importance of glacier and forest change in hydrological climate-impact studies
Authors: Köplin N. , Schädler B. , Viviroli D. , Weingartner R.
Published: February 2013

Abstract. Changes in land cover alter the water balance components of a catchment, due to strong interactions between soils, vegetation and the atmosphere. Therefore, hydrological climate impact studies should also integrate scenarios of associated land cover change. To reflect two severe climate-induced changes in land cover, we applied scenarios of glacier retreat and forest cover increase that were derived from the temperature signals of the climate scenarios used in this study. The climate scenarios were derived from ten regional climate models from the ENSEMBLES project. Their respective temperature and precipitation changes between the scenario period (2074–2095) and the control period (1984–2005) were used to run a hydrological model. The relative importance of each of the three types of scenarios (climate, glacier, forest) was assessed through an analysis of variance (ANOVA). Altogether, 15 mountainous catchments in Switzerland were analysed, exhibiting different degrees of glaciation during the control period (0–51%) and different degrees of forest cover increase under scenarios of change (12–55% of the catchment area). The results show that even an extreme change in forest cover is negligible with respect to changes in runoff, but it is crucial as soon as changes in evaporation or soil moisture are concerned. For the latter two variables, the relative impact of forest change is proportional to the magnitude of its change. For changes that concern 35% of the catchment area or more, the effect of forest change on summer evapotranspiration is equally or even more important than the climate signal. For catchments with a glaciation of 10% or more in the control period, the glacier retreat significantly determines summer and annual runoff. The most important source of uncertainty in this study, though, is the climate scenario and it is highly recommended to apply an ensemble of climate scenarios in the impact studies. The results presented here are valid for the climatic region they were tested for, i.e., a humid, mid-latitude mountainous environment. They might be different for regions where the evaporation is a major component of the water balance, for example. Nevertheless, a hydrological climate-impact study that assesses the additional impacts of forest and glacier change is new so far and provides insight into the question whether or not it is necessary to account for land cover changes as part of climate change impacts on hydrological systems.
Natural vs. artificial groundwater recharge, quantification through inverse modeling
Authors: Hashemi H. , Berndtsson R. , Kompani-Zare M. , Persson M.
Published: February 2013

Abstract. Estimating the change in groundwater recharge from an introduced artificial recharge system is important in order to evaluate future water availability. This paper presents an inverse modeling approach to quantify the recharge contribution from both an ephemeral river channel and an introduced artificial recharge system based on floodwater spreading in arid Iran. The study used the MODFLOW-2000 to estimate recharge for both steady- and unsteady-state conditions. The model was calibrated and verified based on the observed hydraulic head in observation wells and model precision, uncertainty, and model sensitivity were analyzed in all modeling steps. The results showed that in a normal year without extreme events, the floodwater spreading system is the main contributor to recharge with 80% and the ephemeral river channel with 20% of total recharge in the studied area. Uncertainty analysis revealed that the river channel recharge estimation represents relatively more uncertainty in comparison to the artificial recharge zones. The model is also less sensitive to the river channel. The results show that by expanding the artificial recharge system, the recharge volume can be increased even for small flood events, while the recharge through the river channel increases only for major flood events.
Using a thermal-based two source energy balance model with time-differencing to estimate surface energy fluxes with day-night MODIS observations
Authors: Guzinski R. , Anderson M. C. , Kustas W. P. , Nieto H. , Sandholt I.
Published: February 2013

Abstract. The Dual Temperature Difference (DTD) model, introduced by Norman et al. (2000), uses a two source energy balance modelling scheme driven by remotely sensed observations of diurnal changes in land surface temperature (LST) to estimate surface energy fluxes. By using a time differential temperature measurement as input, the approach reduces model sensitivity to errors in absolute temperature retrieval. The original formulation of the DTD required an early morning LST observation (approximately 1 h after sunrise) when surface fluxes are minimal, limiting application to data provided by geostationary satellites at sub-hourly temporal resolution. The DTD model has been applied primarily during the active growth phase of agricultural crops and rangeland vegetation grasses, and has not been rigorously evaluated during senescence or in forested ecosystems. In this paper we present modifications to the DTD model that enable applications using thermal observation from polar orbiting satellites, such as Terra and Aqua, with day and night overpass times over the area of interest. This allows the application of the DTD model in high latitude regions where large viewing angles preclude the use of geostationary satellites, and also exploits the higher spatial resolution provided by polar orbiting satellites. A method for estimating nocturnal surface fluxes and a scheme for estimating the fraction of green vegetation are developed and evaluated. Modification for green vegetation fraction leads to significantly improved estimation of the heat fluxes from the vegetation canopy during senescence and in forests. Land-cover based modifications to the Priestley–Taylor scheme, used to estimate transpiration fluxes, are explored based on prior findings for conifer forests. When the modified DTD model is run with LST measurements acquired with the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra and Aqua satellites, generally satisfactory agreement with field measurements is obtained for a number of ecosystems in Denmark and the United States. Finally, regional maps of energy fluxes are produced for the Danish Hydrological ObsErvatory (HOBE) in western Denmark, indicating realistic patterns based on land use.
Sub-modeling approach for obtaining structural stress histories during dynamic analysis
Authors: Rantalainen T. T. , Mikkola A. M. , Björk T. J.
Published: February 2013

Abstract. Modern machine structures are often fabricated by welding. From a fatigue point of view, the structural details and especially, the welded details are the most prone to fatigue damage and failure. Design against fatigue requires information on the fatigue resistance of a structure's critical details and the stress loads that act on each detail. Even though, dynamic simulation of flexible bodies is already current method for analyzing structures, obtaining the stress history of a structural detail during dynamic simulation is a challenging task; especially when the detail has a complex geometry. In particular, analyzing the stress history of every structural detail within a single finite element model can be overwhelming since the amount of nodal degrees of freedom needed in the model may require an impractical amount of computational effort. The purpose of computer simulation is to reduce amount of prototypes and speed up the product development process. Also, to take operator influence into account, real time models, i.e. simplified and computationally efficient models are required. This in turn, requires stress computation to be efficient if it will be performed during dynamic simulation. The research looks back at the theoretical background of multibody simulation and finite element method to find suitable parts to form a new approach for efficient stress calculation. This study proposes that, the problem of stress calculation during dynamic simulation can be greatly simplified by using a combination of Floating Frame of Reference Formulation with modal superposition and a sub-modeling approach. In practice, the proposed approach can be used to efficiently generate the relevant fatigue assessment stress history for a structural detail during or after dynamic simulation. Proposed approach is demonstrated in practice using one numerical example. Even though, examples are simplified the results show that approach is applicable and can be used as proposed.
Combined Hip Arthroscopy and Limited Open Osteochondroplasty for Anterior Femoroacetabular Impingement: Early Patient Reported Outcomes
Authors: Srinivasan Sreebala C.M. , Hosny Hazem A.H. , Williams Mark R.
Published: February 2013

Many surgical techniques have been described for femoroacetabular impingement (FAI) surgery to help with improvement of pain and function in symptomatic patients. The aim of this study was to evaluate early patient reported outcomes and complications using combined hip arthroscopy and limited open osteochondroplasty technique. We retrospectively analysed 27 hips in 26 patients. Outcomes were assessed using the nonarthritic hip score (NAHS), UCLA score and Visual analogue scale (VAS) pain score. The average age of patients was 31.3 years and they were followed up for an average of 22.3 months. Average improvement of NAHS score was 39.55 points (p<.0001), 18 patients (72%) had at least 30 points increase in NAHS. There was 3 points average improvement in UCLA score (p<.0001). 17 patients (68%) had UCLA activity level of 6 and above. The average improvement of VAS pain score was 27.5 points (p<.0001). Minor complications included neuropraxia of the lateral femoral cutaneous nerve in three patients who recovered at three months with no sequelae, while one patient developed asymptomatic heterotopic ossification Brooker grade I. One patient had neuropraxia of the sciatic nerve which recovered completely within six months. One patient had a conversion to THR at 12 months.

This is an effective technique to treat FAI for reducing pain and improving function at short term follow-up and has a low complication rate without appearing to have a significant learning curve. The failure rate can be reduced if proper case selection is done.
Linac Based Radical Radioablation of Liver Tumors
Authors: Miszczyk L. , Tukiendorf A. , Jochymek B.
Published: February 2013

Due to the low percentage of resectable liver tumors, new alternative treatment modalities are used. Among them, radioablation, that is, by using a limited number of high dose radiation. The aim of this study was to evaluate the effectiveness of liver tumor radioablation at 36 Gy delivered in three fractions. The analyzed material comprised of 65 liver tumors. In 61 cases, we irradiated metastases (20 rectal cancers) and in 4 primary liver tumors. Radioablation, was done using 6 and 20 MV photons with a fraction dose of 12 Gy once a week up to a total dose of 36 Gy. During the follow-up we measured tumor diameters, and for our statistics we used a classical linear regression and the Bayesian approach. Mild and moderate late toxicity was observed. We found a significant absolute and relative decrease in tumor size during the first 6 months from the whole analyzed group. In subgroups with adenocarcinomas, metastases of gastrointestinal tract (GI) cancers, metastases of cancers other than GI cancers, and in the subgroup in which 2D-2D kV system (IGRT) and respiratory gating was used. The percentage of tumors with local control (lack of “in field” progression) after 6 months was 89%. The obtained results permit us to conclude that gated SBRT of liver tumors is an effective and safe treatment modality resulting in a significant regression of liver tumors and that the highest degree of tumor size reduction can be expected for metastases of non-gastro intestinal tract cancers.
Social Participation Restriction Among US Adults With Arthritis: A Population‐Based Study Using the International Classification of Functioning, Disability and Health
Authors: Theis K. A. , Murphy L. , Hootman J. M. , Wilkie R.
Published: February 2013

Objective

To examine arthritis impact among US adults with self‐reported doctor‐diagnosed arthritis using the International Classification of Functioning, Disability and Health (ICF) framework (including the impairments, activity limitations, environmental, and personal factors domains and social participation restriction [SPR] as the outcome) overall and among those with and without SPR, and to identify the correlates of SPR.

Methods

Cross‐sectional 2009 National Health Interview Survey data were analyzed to examine the distribution of the ICF domain components. Unadjusted and multivariable‐adjusted prevalence ratios (PRs) and 95% confidence intervals (95% CIs) were estimated to identify the correlates of SPR. Analyses using SAS, version 9.2 survey procedures accounted for the complex sample design.

Results

SPR prevalence was 11% of adults with arthritis (5.7 million). After initial multivariable adjustment by ICF domain, serious psychological distress (impairments domain; PR 2.5 [95% CI 2.0–3.2]), ≥5 medical office visits (environmental domain; PR 3.4 [95% CI 2.5–4.4]), and physical inactivity (personal domain; PR 4.8 [95% CI 3.6–6.4]) were most strongly associated with SPR. A combined measure (key limitations [walking, standing, or carrying]; PR 31.2 [95% CI 22.3–43.5]) represented the activity limitations domain. After final multivariable adjustment incorporating all ICF domains simultaneously, the strongest associations with SPR were key limitations (PR 24.3 [95% CI 16.8–35.1]), ≥9 hours of sleep (PR 1.6 [95% CI 1.3–2.0]), and income‐to‐poverty ratio <2.00 and severe joint pain (PR 1.4 [95% CI 1.2–1.6] for both).

Conclusion

SPR affects 1 of 9 adults with arthritis. This study is the first to use the ICF framework in a population‐based sample to identify specific functional activities, pain, sleep, and other areas as priorities for intervention to reduce negative arthritis impacts on disability, including SPR. Increased use of existing clinical and public health interventions is warranted.
Potential Classification Criteria for Rheumatoid Arthritis After Two Years: Results From a French Multicenter Cohort
Authors: Saraux Alain , Tobón Gabriel J. , Benhamou Mathilde , Devauchelle‐Pensec Valérie , Dougados Maxime , Mariette Xavier , Berenbaum Francis , Chiocchia Gilles , Rat Anne‐Christine , Schaeverbeke Thierry , Rincheval Nathalie , Meyer Olivier , Fautrel Bruno , Combe Bernard
Published: February 2013

Objective

To determine agreement among the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria, a diagnosis of rheumatoid arthritis (RA) by a rheumatologist, and other criteria previously used to classify arthritis.

Methods

We used a nationwide longitudinal prospective cohort of patients with recent‐onset arthritis. After 2 years, the patients were classified as receiving disease‐modifying antirheumatic drugs (DMARDs), having synovitis, having joint erosions typical of RA, having a rheumatologist diagnosis of RA with >50.0% certainty, having a no better alternative diagnosis with >50.0% certainty, and having a diagnosis of RA using the 1987 ACR criteria and the 2010 ACR/EULAR criteria. Agreement among these criteria was assessed based on Cohen's kappa coefficient, where ≥0.80 = excellent, 0.60–0.79 = good, 0.40–0.59 = moderate, and <0.40 = poor.

Results

Of the 692 evaluated patients, 544 (78.6%) had persistent arthritis (defined as synovitis, ongoing DMARD treatment, or both) after 2 years. Among these 544 patients, 496 (91.2%) were receiving DMARDs. Agreement among all criteria was poor (estimated κ = 0.09–0.43), except when including a rheumatologist diagnosis of RA with >50.0% certainty or a no better alternative diagnosis with >50.0% certainty (estimated κ = 0.69–0.81). The strongest associations with a rheumatologist diagnosis of RA with >50.0% certainty were the 2010 ACR/EULAR criteria and the combination of no better alternative diagnosis, persistent arthritis, 1987 ACR criteria, and positive anti–citrullinated protein antibody.

Conclusion

Rheumatologist diagnosis of RA with >50.0% certainty after 2 years agreed well with the 2010 ACR/EULAR criteria or a combination of items including no better alternative diagnosis, confirming high value as classification criteria after 2 years of followup.
Passivity analysis for nonlinear, nonstationary entry capsules
Authors: Mooij E.
Published: February 2013

Application of simple adaptive control theory to the design of guidance and control systems for winged re‐entry vehicles has been proven successful, despite the fact that the sufficient conditions of passivity are not fulfilled throughout the trajectory. This has been traced back to the hybrid control, that is, a combination of reaction and aerodynamic control for a single axis of motion, as well as a zero bank angle in the initial phase of the mission. The latter condition makes the vehicle nonminimum phase (positive transmission zeros of the open‐loop system). To further analyze the passivity of nonlinear, time‐varying systems, we study an entry capsule that enters the atmosphere in a lift‐down configuration to avoid skipping flight. The capsule is controlled by a reaction control system only. The transient effect (i.e., time‐varying aspects) is an important factor in the stability properties of the guidance system, and an analysis methodology has been set up to take both the nonlinearities and the time‐varying aspects due to the strongly changing flight regimes into account. Deriving the passivity conditions for translational motion, as well as evaluating these conditions along the trajectory, shows that the entry capsule is not almost strictly passive and the sufficient conditions are not met. The guidance‐system design should be augmented with parallel feedforward filters. For rotational motion, on the other hand, it is found the entry capsule is almost strictly passive, so the sufficient conditions to apply simple adaptive control are met.Copyright © 2013 John Wiley & Sons, Ltd.
Classification of Lattice Defects in the Kesterite Cu2ZnSnS4 and Cu2ZnSnSe4 Earth‐Abundant Solar Cell Absorbers
Authors: Chen Shiyou , Walsh Aron , Gong Xin‐Gao , Wei Su‐Huai
Published: February 2013

The kesterite‐structured semiconductors Cu2ZnSnS4 and Cu2ZnSnSe4 are drawing considerable attention recently as the active layers in earth‐abundant low‐cost thin‐film solar cells. The additional number of elements in these quaternary compounds, relative to binary and ternary semiconductors, results in increased flexibility in the material properties. Conversely, a large variety of intrinsic lattice defects can also be formed, which have important influence on their optical and electrical properties, and hence their photovoltaic performance. Experimental identification of these defects is currently limited due to poor sample quality. Here recent theoretical research on defect formation and ionization in kesterite materials is reviewed based on new systematic calculations, and compared with the better studied chalcopyrite materials CuGaSe2 and CuInSe2. Four features are revealed and highlighted: (i) the strong phase‐competition between the kesterites and the coexisting secondary compounds; (ii) the intrinsic p‐type conductivity determined by the high population of acceptor CuZn antisites and Cu vacancies, and their dependence on the Cu/(Zn+Sn) and Zn/Sn ratio; (iii) the role of charge‐compensated defect clusters such as [2CuZn+SnZn], [VCu+ZnCu] and [ZnSn+2ZnCu] and their contribution to non‐stoichiometry; (iv) the electron‐trapping effect of the abundant [2CuZn+SnZn] clusters, especially in Cu2ZnSnS4. The calculated properties explain the experimental observation that Cu poor and Zn rich conditions (Cu/(Zn+Sn) ≈ 0.8 and Zn/Sn ≈ 1.2) result in the highest solar cell efficiency, as well as suggesting an efficiency limitation in Cu2ZnSn(S,Se)4 cells when the S composition is high.
Molecular insights for the optimization of solvent‐based selective extraction of ethanol from fermentation broths
Authors: Keasler Samuel J. , Lewin John L. , Siepmann J. Ilja , Gryska Nicole M. , Ross Richard B. , Schultz Nathan E. , Nakamura Masayuki
Published: February 2013

Simulations and experiments were carried out to explore the solvent extraction of ethanol from aqueous solution using a series of seven 10‐carbon alcohols. It is shown that configurational‐bias Monte Carlo simulations in the Gibbs ensemble coupled with the TraPPE‐UA force field can be utilized for predictive screening of the different extraction abilities (in terms of capacity factor and selectivity) of these alcohols. Analysis of the simulation trajectories indicates that extraction capacity is connected to the stabilization of larger ethanol/water cluster in the organic solvent, whereas selectivity is improved when smaller ethanol/water clusters are more prevalent. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3065–3070, 2013