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Sound generation by planar flame annihilation for methane/hydrogen/air premixed flames is investigated using one-dimensional (1D) fully-resolved simulations. The Foundational Fuel Chemistry Model (FFCM) is used to undertake the simulations for different initial pressures and temperatures, for volumetric mixtures of 0 to 100% hydrogen in the fuel mixture. For cases with 25% to 80% of hydrogen in the fuel mixture three stages of annihilation are observed. The first stage exhibits a gradual flame extinction coupled with the generation of a pressure wave with a long wavelength. The second stage features a more rapid extinction as the flame accelerates towards the symmetry axis, producing a sharp pressure drop. The final stage exhibits a gradual decrease in pressure due to slow reactions such as CO oxidation. The contribution of the first stage increases as more hydrogen is added to the fuel. These stages are not distinctive when the fuel is pure hydrogen. The time derivative of the heat release rate is verified to be the dominant source of sound for annihilation events. A correlation linking the sound amplitude from planar annihilation events to key flame parameters is demonstrated to work for the studied fuel blends. The FFCM is then reduced using a modified Directed Relation Graph with Error Propagation and Sensitivity Analysis (DRGEPSA) method with error bounds based on the laminar flame speed, sL. A good agreement between the sL predictions for the reduced and the detailed mechanisms are found. Furthermore, the developed reduced mechanisms in this work are shown to predict the generated sound by flame annihilation accurately.

This study investigates a laminar premixed flame interacting with cold gas jets, at different cooling jet mass flow fractions ( m ˙ j e t * ) and diluent types, namely air and N2. A novel burner and wall configuration is used to experimentally induce flame-cooling-air interaction (FCAI). Flame chemiluminescence imaging, exhaust temperature (Texh) and exhaust CO emissions ([CO]exh) measurements are conducted to characterise the flame shape and [CO]exh response to the cooling jets. Flame imaging reveals that the cooling jets greatly affect the flame shape. Measurements of [CO]exh demonstrate a direct correlation with Texh, as decreasing Texh is observed to occur with decreasing [CO]exh. Additionally, the air diluent case shows consistently lower [CO]exh values, relative to the N2 diluent case. Using a novel modelling approach, the cooling jets are simulated using one-dimensional (1D) fully resolved simulations (FRS). The effect of jet dilution, jet cooling and exhaust gas cooling are independently and jointly investigated in these simulations. The FRS results support the experimentally observed behaviour, and show that exhaust gas cooling and exhaust gas oxygenation produce decreased CO concentrations. Using a chemical reactor network (CRN), the jet mixing process is modelled by a perfectly stirred reactor (PSR), while the exhaust gas cooling process is modelled by a plug flow reactor (PFR). The CRN modelling shows that the jet mass flow rates dictated by m ˙ j e t * , the dilution time (tdil) assumed for cooling jet mixing, and the exhaust gas cooling residence time (tcool), play an important role in determining the [CO]exh. An equilibrium analysis illustrates that the relationship between [CO]exh, Texh and exhaust O2, is due to the thermodynamically favoured equilibrium states. Timescale analyses demonstrate that appropriate modelling of jet mixing, and accounting for the rate of exhaust gas cooling, are important for estimations of [CO]exh.

This study investigates the interaction of a two-dimensional (2D) laminar methane-air premixed flame with a constant temperature wall using Direct Numerical Simulation (DNS). The flame is excited using velocity perturbations at the inlet for a range of forcing frequencies. The GRI 3.0 chemical mechanism is used to perform the simulations. The flame behaviour is first analysed by comparing the results to those observed for a steady 2D laminar flame interacting with the wall and a one-dimensional head-on quenching (HOQ) flame under the same conditions as the 2D flame. This is followed by analysing the wall heat flux and CO emission due to the flame quenching at the wall for different forcing frequencies. At low forcing frequencies, the flame is observed to sweep against a large portion of the wall whereas at high frequencies, the flame has an insignificant response to the incoming velocity perturbations. In both these regimes, side-wall quenching (SWQ) is the dominant mechanism of flame–wall interaction. However, at an intermediate frequency, both HOQ and SWQ occur at different stages of flame–wall interaction. The analysis of the total integrated wall heat flux of forced flames shows a large variation of this quantity compared with a steady state flame, with the highest fluctuations occurring for the flame forced at the intermediate frequency. The radical recombination reactions are found to be significant in the vicinity of the wall, contributing to about 50% of the total HRR at the wall at the quenching instant. The analysis of the species transport budget for CO shows that CO transport near the wall close to the flame tip is dominated by convection and diffusion.

The growth rate of total-economy U.S. labor productivity during the eight-year period between 2010:Q3 and 2018:Q3 was only 0.53 percent, lower by a large margin than any other eight-year interval in U.S. postwar quarterly data. This paper divides the question of a possible revival in productivity growth into two questions. The first is the possibility of a procyclical response in the gap between actual and trend productivity growth, and the second is a revival in the productivity growth trend itself. An econometric study of the procyclical gap elasticity takes account of a smaller response in the data since the mid-1980s. Because there is no post-1985 procyclicality in the productivity gap, in simulations of our equation estimated through 2015 we find that projections of the coefficients accurately track the failure of productivity growth to exhibit any revival during the three quarters of 2018 during which output growth has accelerated. Lacking a procyclical revival of the productivity gap, the chance of a revival rests with the productivity growth trend itself. An equation that estimates the responsiveness of that trend to labor market tightness and to capital deepening yields our second conclusion that, based on forecasts of the future trajectory of the unemployment rate and the capital-labor ratio, a revival in trend productivity growth of 0.2 percentage points may occur during 2019-21.

Heating, ventilation and air-conditioning (HVAC) demand accounts for 40% of household energy use. While the impacts of local climates, building characteristics, and occupancy patterns on HVAC demand are all well-known, the interplay between these factors has not been systematically studied. This paper provides a quantitative analysis of the complex interplay between these parameters on the annual and peak HVAC demand of residential buildings. Australia is used as a case study because the building construction practices are similar to many other countries, particularly in Europe and the USA, and the Australian climates span the majority of climates found in the world. The wall types considered are cement render, timber clad, brick veneer, reverse brick veneer, and cavity brick. The climates range from tropical in the north of the country, to cold temperate in the south of the country. The occupancy patterns are modeled using six common Occupancy Scenarios. The results show the highest energy reductions are observed in the climates with high diurnal temperature variation, such as Melbourne (51%) and Hobart (54%). The effect of thermal inertia is less in the climates with low diurnal temperature variation such as Darwin (19%). Occupancy scenarios that include unoccupied periods result in lower annual HVAC demand, yet they increase the peak cooling and heating demand. Increasing the indoor thermal mass by using brick veneer internal walls is shown to reduce the demand by approximately 10–15%.

Understanding the association between precious metals and trace elements in ore minerals is integral to ore deposit research and exploration. In situ characterization of ore minerals is now at the forefront of this field. The power of in situ element mapping and characterization is the ability to combine geochemistry with mineralogical and broader geological context. Synchrotron radiation (SR) X-ray techniques such as X-ray Fluorescence (XRF) and X-ray Absorption Near Edge Spectroscopy (XANES) are incredibly powerful tools for studying ore systems with applications in exploration, geometallurgy, and remediation. We provide examples of these applications to gold-bearing samples from across the world-class Timmins gold camp in Canada. Analysis of thin sections, billet offcuts, as well as cut rock slabs highlights the versatility of SR-XRF and XANES analysis at multiple stages of deposit investigation and for multiple sample types. SR-XRF mapping of large areas at 20 μm resolution is very effective for quickly identifying and characterizing gold and trace element associations with gold, even in low grade and nuggety samples. Large area mapping is integral to quickly providing key geochemical information within the sample context as well as for improving efficiency and mitigating bias in grain selection for higher resolution analyses. High-resolution SR-XRF mapping and XANES analysis of individual mineral grains are compared to conventional EPMA mapping and reveals micrometer scale associations with trace metals, Au, and As. The characterization of trace element associations with different fluid events and gold mineralization styles is integral to understanding mineralizing systems and developing exploration vectors. Point XRF and XANES identified and characterized the presence and nature of refractory gold in pyrite as well as grain scale variability in As speciation. An early understanding of the distribution and redox state of gold, trace metals, and deleterious elements at the exploration stage has implications for mitigating future geometallurgy and remediation issues. The examples presented highlight the potential for the application of synchrotron studies early in the mine cycle for characterizing gold mineralization in orogenic systems.

Transient head-on quenching of laminar premixed methane flames diluted with hot combustion products is analyzed using full-chemistry 1D DNS. The impact of the dilution level, pressure and wall temperature on carbon monoxide (CO) emissions is investigated. Increasing dilution level and pressure reduce peak average near-wall CO concentrations, and reduce the near-wall CO reduction rate. However, the peak average near-wall CO and near-wall CO reduction rate increase with increasing wall temperature. Analysis of the species transport budget for CO near the wall before, during and after quenching indicates that there are conditions where diffusion is the dominant transport term. As a consequence, it may be possible to model the near-wall CO using only the integrated diffusion term within certain spatial regions. Dilution increases the size of these regions, whereas increasing pressure reduces this size.

The Dome mine is host to over 16 Moz of orogenic gold deposited during a period of up to 25 Ma through multi-stage enrichment. The earliest economic stage of veining is an extensive set of ankerite veins which were historically considered barren except where overprinted by subsequent veining events. Gold in these veins is intimately associated with pyrite mineralization, and three stages of pyrite growth have been identified (Py1,2,3). The trace element content of each stage of pyrite growth determined by dynamic-secondary ion mass spectrometry and synchrotron radiation x-ray fluorescence reveals that there were three auriferous fluid events, each with a unique gold and trace element fingerprint which can be related to deposits wide mineralization events. Early ankerite vein forming fluids were auriferous, lower temperature (200–250 °C) and deposited Py1 enriched in gold, metals and metalloids (As, Cu, Ni, Zn). Py2 growth is related to deposit wide quartz-tourmaline and quartz-fuchsite veining based on trace element geochemistry, Au:Ag, and associated mineral assemblages. This deposited Ni enriched pyrite, tellurides, galena, and gold with anomalously high Au:Ag ratios. There is also evidence for remobilization of early gold and trace elements from Py1 pyrite during the Py2 forming event. The final stage of gold endowment in the ankerite veins is related to a deposit (and camp) wide quartz veining event. Py3 growth is trace element (As, Ni, Cu) and Au poor with respect to Py1 and Py2, however, this veining event contributed the bulk of the ankerite vein gold endowment. The remobilization of gold and trace elements from sieve textured Py1 in addition to overprinting Py2 and Py3 and their associated gold endowments helps explain the difficulty in applying bulk rock trace element vectors to gold at the Dome mine. The work also provides conclusive evidence for the auriferous nature of early ankerite veining at the Dome mine, and reveals that the system was fertile for a period of over 7 to 25 Ma, a key component for the formation of a world-class deposit.

This paper presents a systematic experimental study of the relative contributions of various near-wall flame dynamics to exhaust CO emissions. Exhaust carbon monoxide (CO) emissions and quenching distance measurements are reported for a laminar forced premixed propane flame undergoing flame-wall interaction. A vehicle-certification grade emissions bench was used to measure exhaust CO emissions at two points in the exhaust, one close to the flame and one far downstream of the flame. Flame chemiluminescence images were analysed to determine the quenching distance at 16 points in the forcing cycle. Four frequencies ( f = 5 , 20 , 35 and 60 Hz), three amplitudes ( | u ′ / u ¯ | = 0.02 , 0.05 and 0.15), and two cooling rates ( Q ˙ c ≈ 160 and 240 W), are compared to the unforced case. Higher forcing frequencies are observed to significantly change the flame shape during the forcing cycle. Increasing frequency is found to have a non-monotonic effect on the quenching distance, while increasing amplitude is found to decrease the mean quenching distance. Increasing the cooling rate is found to further decrease the mean quenching distance, which is in agreement with the literature. Exhaust CO measurements close to the flame reveal a small decrease at the higher cooling rate, while amplitude and frequency both had an order of magnitude less impact. Far downstream of the flame, exhaust CO measurements show that all cases converge to low CO concentrations. It is shown that a simple reactor network simulation reasonably predicts the exhaust CO emissions, far downstream of the flame.

The behaviour of the flame in an annular combustor with multiple bluff-body injectors with swirl was investigated to provide insights into lean blow-off (LBO) mechanisms when flames interact. Two different configurations, with 12 and 18 burners, and various bulk velocities and equivalence ratios were tested. Flame shape and main features were studied by means of 5 kHz OH ∗ chemiluminescence imaging and the stability limits were identified and compiled into stability regime diagrams. As the equivalence ratio of the mixture was reduced the individual flames would first exhibit a transition from a stable “W-shape” state to a stable “V-shape” state before becoming unstable close to extinction. In the 18-burner configuration LBO was characterised by random detachment and re-stabilisation of the flames over multiple burners across the chamber, until complete lift-off. In the 12-burner configuration the flame anchors on a few burners in azimuthally symmetric locations, making the overall flame less prone to global extinction. Finally, the stability curves were computed using a correlation based on the Damkholer (Da) number and compared to single burner configurations. The beginning of the blow-off transient was found to be similar to the LBO condition for a single burner in the 12-burner setup, while the 18-burner configuration was less stable for all the conditions investigated. However, it was found that correlations based on single burner extinction data do not fully work for the extinction of interacting flames. The results provide insights into the blow-off of realistic gas turbine engines and can be used for validating models of such processes.

This paper presents an experimental and theoretical examination of directly injected (DI) propane at a wide range of conditions relevant to spark ignition engines. The investigated conditions comprise the injection of sub- and supercritical propane, with the latter representing a plausible, operational extreme during engine heat soak. Optical imaging is first used to study a wide range of observed spray behaviors, highlighting the sensitivity of DI propane to the engine operating condition. These varying behaviors then prompt further consideration of the thermodynamics involved. This extends thermodynamic arguments recently proposed by the authors in another work, and is able to explain when supercritical injection contains the liquid phase, when shock structures appear and when the spray collapses. Spray regime diagrams are then proposed in order to generalize the observed behaviors. These diagrams reveal several, often overlapping regimes that demarcate choked and unchoked injection, collapsed and multi-plume sprays, and the appearance or disappearance of the liquid phase immediately outside of the injector.

This paper presents an analysis of different pathways for synthesising methanol and dimethyl ether (DME) from natural gas. This work seeks to determine the conditions under which methanol and DME might simultaneously have lower lifecycle greenhouse gas emissions and lower price than gasoline and diesel. Lower lifecycle greenhouse gas emissions are found to be possible if the energy used to synthesise these fuels is from low emission sources. Both methanol and DME synthesis should also be economically competitive with these incumbent transport fuels given current clean energy prices, provided that the natural gas price is approximately at current US levels and gasoline and diesel prices are at least 0.6$US/l. This suggests that methanol and DME can be scalable, economic and environmentally preferable alternatives to gasoline and diesel, particularly in the United States.

This paper presents a three-dimensional (3D) direct numerical simulation (DNS) study of flame-wall interaction (FWI) and flame-cooling air interaction (FCAI). A preheated, methane/air mixture enters a channel with constant temperature walls, where the top wall is effusion cooled. An imposed vertical hot sheet near the inlet creates two flame branches interacting with the top and bottom walls. The flame is observed to be leaner in the region where it interacts with the effusion cooling jets. In this region, the flame is longer and features reduced CO mass fraction. The fluctuations in the heat release rate (HRR) and CO mass fraction are also relatively small near the top wall. Near the bottom wall, finger-like flame structures are formed due to the interaction of turbulent vortices with the flame surface. These flame structures initially move away from the wall as they propagate further downstream before eventually collapsing at the wall. This leads to the creation of regions of high wall heat flux and CO. While analysis of the CO thermochemical state shows a complex picture near the bottom wall, two-dimensional (2D) manifolds can be identified near the top wall. Therefore, a framework to estimate CO mass fraction due to FCAI based on 1D freely-propagating flame solutions is proposed showing a good agreement with the DNS results.

Flames diluted by combustion products can reduce emissions such as Carbon Monoxide (CO) and Nitrogen Oxides (NO x ) in industrial applications. In gas turbines, these flames are confined in a combustor and can interact with relatively cold walls. This interaction can quench the flame, producing incomplete combustion products. In this study, Flame-Wall Interaction (FWI) for methane/air flames diluted by hot combustion products is investigated using direct numerical simulation. A three-Dimensional (3D) turbulent V-flame in a channel with isothermal hot and cold walls is simulated. It is shown that a main reaction zone in the central region between two walls supported by periodic bulk ignition events changes the position of volumetric reaction zones where CO is formed. The cold wall leads to a longer flame, thereby having disproportionately large contribution to the exhaust CO. Near-wall turbulence-flame interaction creates wrinkled and streaky flame surfaces, and localises the near-wall CO distribution. High mean CO mass fraction develops in the free-stream while a high magnitude of the peak RMS CO mass fraction is present closer to the wall. It is also shown that one-dimensional flame solutions can reasonably describe the changes of CO mass fraction as a function of temperature in the free-stream region and some parts of the near-wall region but not close to the wall. Turbulent mixing and diffusion effects contribute to this deviation. The results highlight the complexities involved in CO modelling for diluted flames and set a benchmark for future work.

The unsteady, visible, chemiluminescence fields of two non-axisymmetric, forced, laminar, premixed, propane–air flames are tomographically reconstructed using between 3 and 36 equally-spaced views. Algorithms for measuring flame surface area, flame curvature, flame thickness, and the normal component of the flame propagation velocity (surface speed) are demonstrated. The sensitivity of each measurement to the number of views used in the reconstruction is then assessed. For both flames studied, the difference between flame surface area fluctuations measured using 36 views and those measured using as few as 9 views was less than 1%. For the other three quantities, a measurement sample is acquired over the entire flame surface at one phase of the forcing cycle for each flame. The sensitivity to the number of views is compared by assessing the similarity of measurement distributions obtained using the maximum number of views to those obtained using fewer views. The surface speed measurement distribution is found to converge fastest as the number of views was increased, though results for mean curvature are similar. However, the flame thickness measurement distribution was found to have significantly slower convergence and more than twice the number of views are required to measure flame thickness compared to curvature or surface speed. The demonstrated measurement algorithms are generally applicable to the chemiluminescence fields of wrinkled, premixed flames. The results suggest that for laboratory-scale, weakly turbulent, premixed, jet flames, statistical measurements of flame curvature and surface speed may be accurately obtained using as few as six views, while greater than 20 views are likely to be required to obtain useful measurements of flame thickness.

This paper presents an experimental and modeling study of direct fuel injection in a constant volume chamber (CVC). Iso-octane and propane are used as surrogates for gasoline and liquefied petroleum gas (LPG) respectively, and are injected over a wide range of conditions that are relevant to modern, spark ignition engines. Optical imaging of the liquid and vapor phases are first used to examine these sprays’ overall behavior. These experimental results and thermodynamic arguments are then used to demonstrate the limitations of some existing methods for identifying the onset of spray plume interaction and spray collapse in multi-hole injectors. Further modeling is then undertaken, leading to new criteria for both spray collapse and plume interaction due to flash-boiling. These criteria employ simple physical arguments, geometrical parameters and the fuel’s thermodynamic property data, and appear to be applicable to any fuel injector.

Understanding the mixing process of under-expanded gaseous-fuel jets from an outward opening injector is essential for developing Direct Injection (DI) internal combustion engines. This paper presents a Large-Eddy Simulation (LES) study of the DI of methane into a Constant Volume Chamber (CVC), considering the full, internal geometry of a prototype injector. Four cases at conditions relevant to Compressed Natural Gas (CNG) DI engines are investigated, with methane as a surrogate for CNG. A new post-processing method permits the 3D LES field to be projected into a 2D density gradient field that can be compared to a schlieren image. The LES results are then validated against high-speed, schlieren imaging experiments, demonstrating that the simulations are able to reproduce experimental trends. Three main regions of the external flow are observed: a recirculation zone just downstream of the injector tip, a stagnation zone and a far-mixing zone. The location of the stagnation zone increases as the CVC pressure decreases, consistent with a theory presented in the literature. The modelling of the full internal geometry of the injector leads to a determination of the injector pressure losses. Once the pressure loss within the injector is considered, a short version of the injector can reasonably represent the full injector for prediction of the external flow.

Objectives The purpose of this study was to determine the risk factors for ischemic in hemorrhage cerebrovascular events in patients supported by the HeartWare ventricular assist device (HVAD). Background Patients supported with left ventricular assist devices are at risk for both ischemic and hemorrhagic cerebrovascular events. Methods Patients undergoing implantation with a HVAD as part of the bridge-to-transplant trial and subsequent continued access protocol were included. Neurological events (ischemic cerebrovascular accidents [ICVAs] and hemorrhagic cerebrovascular accidents [HCVAs]) were assessed, and the risk factors for these events were evaluated in a multivariable model. Results A total of 382 patients were included: 140 bridge-to-transplant patients from the ADVANCE (Evaluation of the HeartWare Left Ventricular Assist Device for the Treatment of Advanced Heart Failure) clinical trial and 242 patients from the continued access protocol. Patients had a mean age of 53.2 years; 71.2% were male, and 68.1% were white. Thirty-eight percent had ischemic heart disease, and the mean duration of support was 422.7 days. The overall prevalence of ICVA was 6.8% (26 of 382); for HCVA, it was 8.4% (32 of 382). Pump design modifications and a protocol-driven change in the antiplatelet therapy reduced the prevalence of ICVA from 6.3% (17 of 272) to 2.7% (3 of 110; p = 0.21) but had a negligible effect on the prevalence of HVCA (8.8% [24 of 272] vs. 6.4% [7 of 110]; p = 0.69). Multivariable predictors of ICVA were aspirin ≤81 mg and atrial fibrillation; predictors of HCVA were mean arterial pressure >90 mm Hg, aspirin ≤81 mg, and an international normalized ratio >3.0. Eight of the 30 participating sites had established improved blood pressure management (IBPM) protocols. Although the prevalence of ICVA for those with and without IBPM protocols was similar (5.3% [6 of 114] vs. 5.2% [14 of 268]; p = 0.99), those with IBPM protocols had a significantly lower prevalence of HCVA (1.8% [2 of 114] vs. 10.8% [29 of 268]; p = 0.0078). Conclusions Anticoagulation, antiplatelet therapy, and blood pressure management affected the prevalence of cerebrovascular events after implantation of the HVAD. Attention to these clinical parameters can have a substantial impact on the occurrence of serious neurological events. (Evaluation of the HeartWare Left Ventricular Assist Device for the Treatment of Advanced Heart Failure [ADVANCE]; NCT00751972)

Objectives This study evaluated gastrointestinal bleeding (GIB) in patients receiving the HeartWare HVAD System (HeartWare Inc., Framingham, Massachusetts) in the pivotal BTT (Bridge to Transplant) trial and under the continued access protocol (CAP). Background GIB has become a significant problem for recipients of continuous flow device left ventricular assist devices (CF-LVAD). The need for anticoagulation and antiplatelet therapies complicates the management of GIB. Methods Bleeding events from 382 patients with advanced heart failure (140 patients enrolled in the BTT trial, and an additional 242 CAP patients) were analyzed. Post-implant anticoagulation consisted of heparin followed by warfarin at a target international normalized ratio of 2 to 3. Acetylsalicylic acid was recommended at 81 to 325 mg. Results Overall, 59 of 382 (15.4%) patients experienced 108 GIB events (0.27 events per patient year). Mean time to first bleed was 273.1 days and 86.1% of events occurred beyond 30 days. Freedom from GIB was 84.1% at 1 year. Median international normalized ratio at the time of first bleed was 2.4 ± 1.4. The most common etiology of bleeding identified was arteriovenous malformation and the most common site was the small intestine. Repeat bleeding was infrequent, though GIB patients required more readmissions and developed nondevice infections more frequently. No patients required surgical intervention and no deaths directly related to GIB occurred. Conclusions Recipients of the HeartWare Ventricular Assist Device System had an incidence of 0.27 GIB/patient year with a freedom from GIB of 84.1% at 1 year. All patients with GIB events were managed with medical and endoscopic therapies, although 31% of patients experienced a recurrence of GIB. No surgical intervention was required. GIB did not impact survival. (Evaluation of the HeartWare Left Ventricular Assist Device for the Treatment of Advanced Heart Failure [ADVANCE]; NCT00751972 )

Plants have the potential to accumulate toxic amounts of cadmium (Cd), and understanding how and where Cd is stored in plants is important for ensuring food safety. Previous experiments have determined that a greater amount of Cd is translocated into the leaves of lettuce (Lactuca sativa) as compared to barley leaves (Hordeum vulgare). Preferential retention of Cd in root of barley would explain this difference. Hence, the purpose of this study was to determine the localization and coordination environment of Cd (i.e., the ligands to which Cd was bound) in the different root tissues of lettuce and barley using histochemical staining, electron microscopy and micro X-ray spectroscopy. Retention of Cd in barley roots could be explained by accumulation of Cd at the endodermis, comparatively higher amounts of Cd sequestered in the symplast of cortical cells and binding to xylem cell walls. Increased translocation of Cd to lettuce shoots seemed to be due to a less effective barrier at the endodermis and less sequestration of Cd in the cortex. Regardless of the tissue type, most of the Cd2+ was bound to S ligands in the roots of barley, possibly reflecting accumulation of Cd–phytochelatin and Cd–S molecules in the vacuoles. In lettuce roots, Cd was more evenly distributed among ligands containing S, O and NO3 groups, which is indicative of proportionately more Cd binding to the cell walls, relative to barley. These results will be useful in uncovering the mechanisms of differential Cd-tolerance and sequestration in lettuce and barley.

This paper will discuss the transition from multidisciplinary to interdisciplinary and transdisciplinary team approaches to pain management at New York University Langone Medical Center - Rusk Institute of Rehabilitation Medicine. A transdisciplinary team approach to pain management emphasizes mutual learning, training, and education, and the flexible exchange of discipline-specific roles. Clinicians are enabled to implement a unified, holistic, and integrated treatment plan with all members of the team responsible for the same patient-centered goals. The model promotes and empowers patient and family/support system goals within a cultural context. Topics of exploration include the descriptions of three team approaches to patient care, including their practical, philosophical, and historical basis, strengths and challenges, research support, and cultural diversity. Case vignettes will highlight the strengths and limitations of the transdisciplinary team approach to pain management throughout a broad and diverse continuum of care, including acute medical, palliative, and perioperative care and acute inpatient rehabilitation services.

A new experimental configuration has been developed to examine the effects of flow on the autoignition of dilute diesel and biodiesel sprays, where the spray is injected in the form of monodisperse individual droplets at right angles to a hot air turbulent flow. The ignition location has been measured by monitoring the OH * chemiluminescence. A qualitative comparison of the flame behaviour between ethanol, acetone, heptane and biodiesel as fuels has also been carried out. With decreasing volatility of the fuel, the flame showed progressively a higher number of individual droplets burning, with the first autoignition spots appearing at random locations but in general earlier than the intense droplet-flame emission. The time-averaged autoignition length increased with increasing air velocity and with increasing intensity of the turbulence, while it decreased with the temperature and the droplet size. The data can be used for validating models for two-phase turbulent combustion. © 2012 Elsevier Inc.

article i nfo Polarization of the plasma luminescence produced by both nanosecond and femtosecond laser ablation of Si(111) was analyzed under different conditions of fluence and detection geometry. It is shown that the lu- minescence is partially polarized and is directed in the plane of the crystal. The time evolution of the plasma emission signal was also investigated with the use of a streak camera. The mechanism for polarization is pro- posed to be preferential reflection of s-polarized light (i.e., light polarized normal to the plane of laser inci- dence) by the melted surface, in agreement with the Fresnel equations. Earlier reports of much stronger polarization are shown to be erroneous.

Heavily corroded metal artifacts recovered from the site of an 18th-century steel cementation furnace in Trenton, New Jersey, are cast iron altered by internal oxidation. The progress of the internal oxidation process was followed by comparison with the microstructure of cast iron exposed to high temperature in a wood-burning fireplace. The graphite flake structure of the cast iron allows deep, rapid penetration of oxygen that reacts at the iron–carbon interfaces within the iron to form iron oxides that eventually replace the graphite flakes. Microprobe analyses show that the silicon in the cast iron is converted to knebelite that also serves as the host for phosphorus. Sulfur dispersed in the internal oxidation product and porosity appear to be responsible for rapid rusting of the artifacts. Internal nitriding accompanies the oxidation. The Trenton artifacts are interpreted as grate bars from the fire box of a cementation furnace.

The current study aimed to investigate the effects of scene context on rapid object recognition using both behavioral and electrophysiological measures. Participants performed an animal/non-animal go/no-go categorization task in which they had to decide whether or not a flashed scene contained an animal. Moreover, the influence of scene context was manipulated either by retaining, deleting, or phase-randomizing the original scene background. The results of Experiments 1 and 2 showed that participants responded more accurately and quickly to objects appearing with their original scene backgrounds. Moreover, the event-related potential (ERP) data obtained from Experiment 2 showed that the onset latency of the frontal go/no-go ERP difference was delayed for objects appearing with phase-randomized scene backgrounds compared to objects appearing with their original scene backgrounds, providing direct evidence that scene context facilitates object recognition. Additionally, an increased frontal negativity along with a decreased late positive potential for processing objects presented in meaningless scene backgrounds suggest that the categorization task becomes more demanding when scene context is eliminated. Together, the results of the current study are consistent with previous research showing that scene context modulates object processing.

The oxidation state and local geometry of the metal centers in amorphous thin films of Fe{sub 2}O{sub 3} (Fe{sup 3+} oxidation state), CoFe{sub 2}O{sub 4} (Co{sup 2+}/Fe{sup 3+} oxidation states), and Cr{sub 2}O{sub 3} (Cr{sup 3+} oxidation state) are determined using K edge X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. The metal oxide thin films were prepared by the solid-state photochemical decomposition of the relevant metal 2-ethylhexanoates, spin cast as thin films. No peaks are observed in the X-ray diffraction patterns, indicating the metal oxides are X-ray amorphous. The oxidation state of the metals is determined from the edge position of the K absorption edges, and in the case of iron-containing samples, an analysis of the pre-edge peaks. In all cases, the EXAFS analysis indicates the first coordination shell consists of oxygen atoms in an octahedral geometry, with a second shell consisting of metals. No higher shells are observed beyond 3.5 {angstrom} for all samples, indicating the metal oxides are truly amorphous, consistent with X-ray diffraction results.

Confined and unconfined turbulent methane-air lean premixed flames stabilized on an axisymmetric bluff-body of diameter d = 25 mm have been examined close to the blow-off limit and during the extinction transient, with OH∗ chemiluminescence, flame tomography and OH-PLIF operated at 5 kHz, allowing a quantification of the duration of the blow-off event. Blow-off was approached by increasing the bulk velocity U b or decreasing the equivalence ratio and the flame shape changed from conical to cylindrical with decreasing length. Close to blow-off, the flame closed on the axis and was about 2 d long, and just before the blow-off condition it took an “M” shape with reaction fronts inside the recirculation zone (RZ). During the blow-off event, fresh reactants entered the RZ from the forward stagnation region and significant fragmentation of the flame occurred, with branches of the flame remaining anchored on the bluff-body edge and separate flame pockets moving randomly inside the RZ. Overall blow-off occurred with the gradual elimination of these flame fragments. The integrated OH∗ emission decreased slowly to zero as the flame surface decreased over a period of about 15 d / U b . The results suggest that the blow-off event in recirculating flames lasts long compared to the residence time in the RZ and the structure of the flame close to extinction supports the underlying assumptions behind well-stirred reactor concepts of blow-off.

Currently used immunosuppressants exacerbate cardiovascular risk. However, attempts to limit the use of these agents increase the risk of allograft rejection. Immunosuppressants targeting signal 2 and signal 3 lymphocyte activation pathways are under clinical development. Clinical data from trials of the Janus family protein tyrosine kinase-3 inhibitor tasocitinib and the costimulation blocker belatacept are presented. Additional pipeline agents are described. Results from two phase III clinical trials of belatacept revealed efficacy that is not inferior to that provided by cyclosporine (CsA). In the Belatacept Evaluation of Nephroprotection and Efficacy as First-line Immunosuppression Trial enrolling recipients of standard criteria living or deceased donor organs, the risk of rejection was higher among patients treated with a more intensive treatment regimen. Increased risk of posttransplant lymphoproliferative disorder, particularly among Epstein-Barr virus-patients, was a notable adverse event. Data from a phase II trial of tasocitinib suggested good prophylaxis of rejection. Safety signals included increased risk of infection and potential myelosuppression, leading to anemia, neutropenia, and leukopenia. Both belatacept and tasocitinib were associated with a low cardiovascular risk profile and improved renal function compared with CsA. New immunosuppressive regimens should maintain the effectiveness provided by current agents while preserving renal function and cardiovascular health. Surveillance for new adverse events must be an integral part of the long-term management strategy.

Planar laser-induced fluorescence (PLIF) and stereoscopic particle image velocimetry (PIV) were simultaneously applied at 1.5 kHz repetition-rate to acquire time-resolved, cinematographic planar measurements of the flamebase stabilization region of a turbulent lifted jet flame. The current work focuses on the development and demonstration of the diagnostic system and presents key examples of the new capabilities it provides. OH-PLIF is used to identify and track the spatial position and shape of the flamefront near the flamebase, while the stereoscopic PIV is used to acquire three-component planar velocity measurements over the same region. Initial results indicate that the significant temporal histories and experimental access to the Vz-velocity component afforded by this system are frequently essential for accurate interpretation of planar measurements in the flow field of a lifted turbulent jet flame.

Accurate prediction of the response of aircraft skins to acoustic loading is important in the design of future air vehicles. Direct time integration of full-order, nonlinear, finite element models may be accurate, but is computationally expensive. Much work has been reported in recent years on prediction methods, which reduce a finite element model to a reduced-order system of nonlinear modal equations. The major difference among the methods is the means by which induced membrane displacements are modeled. One method is the implicit condensation method where the effects of membrane displacements are condensed into the nonlinear stiffness terms of the bending equations. Membrane displacements are not explicitly modeled, so membrane basis vectors are not needed. However, the lack of membrane displacements prohibits the recovery of membrane stresses and strains from the standard finite element strain–displacement relationships. Here, the implicit condensation method is improved by adding a step to recover membrane displacements using an estimated membrane basis. Examples are given that demonstrate the viability of the proposed method.

The present study examined influences of semantic characteristics of objects in real-world scenes on allocation of attention as reflected in eye movement measures. Stimuli consisted of full-color photographic scenes, and within each scene, the semantic salience of two target objects was manipulated while the objects’ perceptual salience was kept constant. One of the target objects was either inconsistent or consistent with the scene category. In addition, the second target object was either smoking-related or neutral. Two groups of college students, namely current cigarette smokers (N = 18) and non-smokers (N = 19), viewed each scene for ten seconds while their eye movements were recorded. While both groups showed preferential allocation of attention to inconsistent objects, smokers also selectively attended to smoking-related objects. Theoretical implications of the results are discussed.

This paper details a quantitative joint temperature, OH, and CH2O imaging experiment designed to investigate the stabilization of lifted turbulent methane flames issuing into a high temperature vitiated coflow. Temperature is determined through Rayleigh imaging, and the data are used to quantify OH-LIF excited at 283.011 nm, and to enable to semi-quantification of CH2O-LIF excited at 355 nm. A fuel with Rayleigh cross-section equal to that of the vitiated coflow was used to improve accuracy in the processing of the Rayleigh temperature. Results of the experiment have been presented, and compared to simulations of laminar transient autoignition flamelets. The images were classified in three main categories: (i) CH2O only, (ii) ignition kernels, and (iii) liftoff flames. Images of type (i) and (ii) were dominant in the early part of the jet, while images of type (iii) were dominant after the mean stabilization height. By examining OH and CH2O conditional on the size of the kernel, it was found that the sequence of conditional data was analogous to the evolution of autoignition, following the key stages of (1) build-up of a precursor pool, (2) initiation of reaction, and (3) formation of a steady flame. Viewed in such a sequence, CH2O peaks prior to the autoignition and then decays after ignition, and OH is found to peak at ignition and these peaks are maintained into the established steady flames. This is in qualitative agreement with the laminar transient flamelet calculations. The data are consistent with the view that autoignition is the main stabilization mechanism in this lifted flame.

Metallurgical examination of Korean bronze artifacts shows that a technical tradition based on casting and use of leaded high-tin alloys was established in Korea at the early stages of bronze use. After the subsequent discovery of quenching methods that suppress formation of the brittle δ phase, new thermo-mechanical techniques were introduced between the 7th and 10th centuries AD. Lead-free alloys were used, and tin contents near that of the peritectic point in the Cu–Sn phase diagram were chosen. Leaded high tin alloys continued in use, but only in cast objects, and with significant composition variation. The unique conditions during the time of innovation suggest that the transition to new metallurgical techniques was gradually achieved through domestic technical innovation inspired by external influences.

Autoignition of hydrocarbon fuels is an outstanding research problem of significant practical relevance in engines and gas turbine applications. This paper presents a numerical study of the autoignition of methane, the simplest in the hydrocarbon family. The model burner used here produces a simple, yet representative lifted jet flame issuing in a vitiated surrounding. The calculations employ a composition probability density function (PDF) approach coupled to the commercial CFD package, FLUENT. The in situ adaptive tabulation (ISAT) method is used to implement detailed chemical kinetics. An analysis of species concentrations and transport budgets of convection, turbulent diffusion, and chemical reaction terms is performed with respect to selected species at the base of the lifted turbulent flames. This analysis provides a clearer understanding of the mechanism and the dominant species that control autoignition. Calculations are also performed for test cases that clearly distinguish autoignition from premixed flame propagation, as these are the two most plausible mechanisms for flame stabilization for the turbulent lifted flames under investigation. It is revealed that a radical pool of precursors containing minor species such as CH3, CH2O, C2H2, C2H4, C2H6, HO2, and H2O2 builds up prior to autoignition. The transport budgets show a clear convective–reactive balance when autoignition occurs. This is in contrast to the reactive–diffusive balance that occurs in the reaction zone of premixed flames. The buildup of a pool of radical species and the convective–reactive balance of their transport budgets are deemed to be good indicators of the occurrence of autoignition.

Metallurgical study of seven cast iron artifacts recovered from sites of the former Xiongnu (BC 3rd to AD 1st), Turk (AD 6th to 8th), Khitan (AD 10th to 12th), and Mongolian empires (AD 12th to 15th) shows that the earlier Xiongnu and Turk artifacts were made of cast iron alloys of near eutectic composition. The later Khitan and Mongol objects had greatly reduced carbon content in the range of ultrahigh carbon steel rather than cast iron, and contained more than 0.5 mass % silicon as an alloying element. Inclusions high in sulfur, phosphorus or silicon are also present. These differences suggest that Mongolia experienced a technical transition a few centuries before the establishment of the Mongolian empire, which is in agreement with some written accounts. The microstructures of the cast iron artifacts are compared with the related archaeological and documentary evidence. The results suggest that the use of fossil coal in smelting and the state policy of controlling iron production were the major factors responsible for the transition.

Previous research has shown that trait anger is associated with biases in attention and interpretation, but the temporal relation between these two types of biases remains unresolved. Indeed, two very different models can be derived from the literature. One model proposes that interpretation biases emerge from earlier biases in attention, whereas the other model proposes that hostile interpretations occur quickly, even prior to the allocation of attention to specific cues. Within the context of integrated visual scenes of ambiguously intended harm, the two models make opposite predictions that can be examined using an eye-tracking methodology. The present study (N = 45) therefore tracked participants’ allocation of attention to hostile and non-hostile cues in ambiguous visual scenes, and found support for the idea that high anger individuals make early hostile interpretations prior to encoding hostile and non-hostiles cues. The data are important in understanding associations between trait anger and cognitive biases.

We have carried out an assessment of the in-use stock of nickel in New Haven, CT, by “bottom–up” methods. To our knowledge, this is only the second characterization of in-use nickel stock in any locale and at any epoch. We find that the City of New Haven contains about 321 Mg (1 Mg = 1 metric tonnes = 1000 kg) of nickel, primarily in the form of nickel-containing alloys. For every resident of New Haven, there is approximately 2.6 kg of nickel stock in use. The principal uses accounting for these totals are identified and quantified in this paper.

The sustainability of metal supplies can be discussed from a physical perspective, as done here, as well as from an economic one. The physical approach involves the concept of limits to virgin supplies, either absolute or arising from external constraints, as well as the sometimes-overlooked additional supply provided by recycling and reuse. At present, economic geology data are too sparse to accurately quantify many of these issues, but current trends imply increased emphasis on recycling and the use of alternative materials for some of the metals widely employed in modern technology.

A detailed inventory shows that an average resident of the City of New Haven depends on a per capita capital stock of 9200 kg/c of iron and 144 kg/c of copper in the city infrastructure, buildings, transportation systems, and equipment. Of the iron stock 28% is in items such as rail cars and ships in ocean trade not permanently within the city, and 22% is devoted to receiving and delivering oil fuel to the city and its surrounding communities. Copper is principally used in the distribution of electric power and in water piping within buildings. The city's 9200 kg/c of iron stock-in-use is less than the 13,000 kg/c national average due to New Haven's lack of heavy industry and relatively small number of large buildings. The 144 kg/c of copper stock-in-use is only 58% of the overall value for the United States, but is comparable to that in cities such as Stockholm, Sweden. Attainment of a level of iron and copper services with contemporary technology in less developed countries to the level enjoyed in New Haven would require consumption of the presently identified world copper resources.

Analyses of silver–copper alloy artifacts from Machu Picchu show silver contents ranging from 24 to 81%. The tin present, ranging up to 3%, originated with the copper, perhaps from admixture of recycled bronze. The presence of 0.4–0.9% lead in the silver-rich phase indicates use of silver prepared by cupellation. All the objects had been forged after casting, some extensively. All have surface enhancement of the silver arising from depletion of the copper-rich phase. Some of the tin found at the site contains inclusions of hardhead (FeSn 2 ) and of a nickel–arsenic–copper compound. Forming trials with duplicate silver–copper alloys show that intermediate anneals at temperatures between 500 and 600 °C facilitate making thin sheet artifacts. Mechanical tests show that the most commonly used alloys, containing 25–30% silver, are particularly well adapted to forging because of their uniform work hardening during plastic deformation. Annealing of the laboratory-made alloys in air followed by boiling in salty weak acid creates a silver-rich surface layer comparable to that found in the artifacts. Depletion forms a dense silver surface on the alloy containing more silver than the eutectic composition, but a porous surface layer on the 25% silver alloys.