Depletion Phenomena Research Articles

The modality effect of ego depletion: Auditory task modality reduces egodepletion.

An initial act of self-control that impairs subsequent acts of self-control is called ego depletion. The ego depletion phenomenon has been observed consistently. The modality effect refers to the effect of the presentation modality on the processing of stimuli. The modality effect was also robustly found in a large body of research. However, no study to date has examined the modality effects of ego depletion. This issue was addressed in the current study. In Experiment 1, after all participants completed a handgrip task, one group's participants completed a visual attention regulation task and the other group's participants completed an auditory attention regulation task, and then all participants again completed a handgrip task. The ego depletion phenomenon was observed in both the visual and the auditory attention regulation task. Moreover, participants who completed the visual task performed worse on the handgrip task than participants who completed the auditory task, which indicated that there was high ego depletion in the visual task condition. In Experiment 2, participants completed an initial task that either did or did not deplete self-control resources, and then they completed a second visual or auditory attention control task. The results indicated that depleted participants performed better on the auditory attention control task than the visual attention control task. These findings suggest that altering task modality may reduce ego depletion.

Potential impact of an exceptional bloom of Karenia mikimotoi on dissolved oxygen levels in waters off western Ireland

In the summer of 2005 an exceptional bloom of the dinoflagellate Karenia mikimotoi occurred along Ireland's Atlantic seaboard and was associated with the mass mortality of both benthic and pelagic marine life. Oxygen depletion, cellular toxicity and physical smothering, are considered to be the main factors involved in mortality. In this paper we use a theoretical approach based on stoichiometry (the Anderson ratio) and an average K. mikimotoi cellular carbon content of 329pgCcell−1 (n=20) to calculate the carbonaceous and nitrogenous oxygen demand following bloom collapse. The method was validated against measurements of biochemical oxygen demand and K. mikimotoi cell concentration. The estimated potential oxygen utilisation (POU) was in good agreement with field observations across a range of cell concentrations. The magnitude of POU following bloom collapse, with the exception of three coastal areas, was considered insufficient to cause harm to most marine organisms. This indicates that the widespread occurrence of mortality was primarily due to other factors such as cellular toxicity and/or mucilage production, and not oxygen depletion or related phenomena. In Donegal Bay, Kilkieran Bay and inner Dingle Bay, where cell densities were in the order of 106cellsL−1, estimated POU was sufficient to cause hypoxia. Of the three areas, Donegal Bay is considered to be the most vulnerable due to its hydrographic characteristics (seasonally stratified, weak residual flow) and hypoxic conditions (2.2mgL−1 O2) were directly observed in the Bay post bloom collapse. Here, depending on the time of bloom collapse, depressed DO levels could persist for weeks and continue to have a potentially chronic impact on the Bay.

The influence of dopant concentration on temperature dependent emission spectra in LiLa1-x-yEuxTbyP4O12 nanocrystals: toward rational design of highly-sensitive luminescent nanothermometers.

Luminescence nanothermometry is gaining great interest, and different excitation and readout schemes have been sought to improve temperature sensitivity and sensing range, or to simplify the readout. Although many up-conversion based nanothermometers have been studied, Tb(3+) and Eu(3+) doped systems have not been widely considered, so far. Herein, we report the synthesis of new LiLa1-x-yEuxTbyP4O12 nanocrystals for luminescent thermal sensing; their spectroscopic properties have been investigated in a wide range of compositions and temperatures. In particular, the impact of dopant concentration on energy transfer processes (such as energy transfer, back energy transfer, energy diffusion and cross relaxation) is presented in a quantitative manner, both experimentally and theoretically, which enables the intentional optimization of the composition to find the finest balance between temperature sensitive excitation and depletion phenomena, and thus, enhance the luminescent thermometry properties. The studied thermometers can be applied in as wide a temperature range as 77-600 K, where they demonstrate sensitivity up to 1% K(-1), which is the highest among the Tb(3+) and Eu(3+) doped inorganic phosphor based materials, to date.

高粘度絶縁油中における絶縁紙の直流部分放電特性と電荷挙動

In long-distance DC submarine cables, insulating oil depletion phenomenon occurs due to limitations in pressure transmission distance. Therefore, the high viscosity insulating oil such as high viscosity oil is promising. However, if the unexpected bubbles are occurred in the high viscosity oil, partial discharge in bubbles may reduce insulation performance of the cable. In addition, the partial discharge promote the degradation of insulating oil and insulating performance may reduce. In this paper, it is investigated DC partial discharge inception voltage and repetition rate of DC partial discharge occurrence of the kraft paper impregnated with the high viscosity insulating oil. Furthermore, the charge behavior was discussed.

Comprehensive Study of Reactants Depletion in Catalytic Olefin Polymerization Industrial Loop Reactors

A multizone model is developed to analyze the reactants depletion phenomena in catalytic, slurry-phase olefin polymerization loop reactors. The modeling approach utilizes linking models at different length and time scales, namely, a kinetic model, a thermodynamic model and a reactor macroscopic model. In addition, a generalized population model equation is utilized to calculate the particle size distribution in the reactor. From the numerical solution of the proposed model, the spatial distribution of the reactants concentration, particle growth rate and particle size distribution in a catalytic polymerization loop reactor can be predicted. The model is further employed to assess the importance of using multifeed injection points along the reactor length for lessening the depletion phenomena and improving the product homogeneity. It is demonstrated that proper selection of the multifeed injection points of the reactants along the reactor length can significantly contribute in producing on-spec polymer gra...

Multi-scale entropic depletion phenomena in polymer liquids.

We apply numerical polymer integral equation theory to study the entropic depletion problem for hard spheres dissolved in flexible chain polymer melts and concentrated solutions over an exceptionally wide range of polymer radius of gyration to particle diameter ratios (Rg/D), particle-monomer diameter ratios (D/d), and chain lengths (N) including the monomer and oligomer regimes. Calculations are performed based on a calibration of the effective melt packing fraction that reproduces the isobaric dimensionless isothermal compressibility of real polymer liquids. Three regimes of the polymer-mediated interparticle potential of mean force (PMF) are identified and analyzed in depth. (i) The magnitude of the contact attraction that dominates thermodynamic stability scales linearly with D/d and exhibits a monotonic and nonperturbative logarithmic increase with N ultimately saturating in the long chain limit. (ii) A close to contact repulsive barrier emerges that grows linearly with D/d and can attain values far in excess of thermal energy for experimentally relevant particle sizes and chain lengths. This raises the possibility of kinetic stabilization of particles in nanocomposites. The barrier grows initially logarithmically with N, attains a maximum when 2Rg ∼ D/2, and then decreases towards its asymptotic long chain limit as 2Rg ≫ D. (iii) A long range (of order Rg) repulsive, exponentially decaying component of the depletion potential emerges when polymer coils are smaller than, or of order, the nanoparticle diameter. Its amplitude is effectively constant for 2Rg ≤ D. As the polymer becomes larger than the particle, the amplitude of this feature decreases extremely rapidly and becomes negligible. A weak long range and N-dependent component of the monomer-particle pair correlation function is found which is suggested to be the origin of the long range repulsive PMF. Implications of our results for thermodynamics and miscibility are discussed.

Evaluation of ion separation coefficients by foam flotation using a carboxylate surfactant

Separation of metal cations of different charges, Na+, Li+, Ca2+, Sr2+, Cu2+, Nd3+ and Eu3+ was investigated through ion foam flotation using a pH sensitive surfactant, nonaoxyethylene oleyl ether carboxylic acid. We propose here a method to evaluate ion selectivity coefficients using mass and volume balances. This method yields selectivity coefficients in agreement with those obtained with the classical slope method. The ion selectivity obtained by the flotation experiments was found to correlate well with the apparent charge of the surfactant micelles (zeta potential values) in the presence of different salts and is therefore not influenced by the surface curvature. Consequently the ion specificity order has been established according to the surfactant–ion affinity at the air–water and micelle–water interfaces as Na+ < Li+ < Sr2+ < Ca2+ < Cu2+ < Nd3+ < Eu3+. It has been noticed that the selectivity coefficients between the different metal ions, obtained by ion flotation, differ from the ones predicted by using metal ion complexation constants of acetate, which is considered here as the non-surface active complexing part of the surfactant. This discrepancy was attributed to the surface complexation effects at the air–water interface in flotation experiments and at the micelle–water interface. For the separation of lithium and neodymium, a depletion phenomenon of lithium ions from the interface, hence from the foam, has been observed, i.e. once the flotation experiment was finished, the lithium concentration in the remaining foaming solution was indeed higher compared to the initial one. This phenomenon was explained by the strong adsorption of Nd3+ that leads Li+ to be repelled from the foam.

Modelling compositional changes in nickel base alloy 602 CA during high temperature oxidation

The high chromium nickel base alloy 602 CA is used as construction material for high temperature components in aggressive environments such as gas burners or heat exchangers. The high temperature oxidation behaviour of this alloy is characterised by the formation of an external Cr2O3 scale and internal precipitation of alumina. The main goal of the present investigation was to elucidate the effect of aluminum on the subscale chromium depletion phenomena. The chromium concentration profiles were found to be flat and sometimes even increasing towards the oxide-alloy interface. The experimental observations were interpreted in terms of alloy thermodynamics, i.e. effect of oxidation induced compositional changes on chemical potentials of the alloy constituents. The concentration profiles in alloy 602 CA observed during high temperature exposure were modelled using the CALPHAD approach for thermodynamic and kinetic calculations. Thermodynamic calculations revealed that the Al depletion in the alloy subsurface due to internal alumina precipitation leads to enhanced Cr diffusion towards the alloy surface.

Effect of iron complexes with seawater extractable organic matter on oogenesis in gametophytes of a brown macroalga (Saccharina japonica)

The phenomenon of macroalgae depletion is a serious worldwide problem in terms of the destruction of ecosystems and reducing carbon fixation capacity in coastal areas. A lack of dissolved Fe is thought to be one of reasons for this phenomenon, and attempts have been made to develop Fe fertilization techniques. This study reports on the bioavailability of Fe species that are complexed with seawater extractable organic matter (SWEOM) derived from a compost and various chelators on oogenesis in a brown macroalga (Saccharina japonica). Oogenesis is induced by Fe uptake. Oogenesis assays indicate that Fe uptake can be explained by a ligand exchange reaction, suggesting that dissolved Fe in the form of a labile complex species could be used as a fertilizer. Fifty to eighty percent of gametophytes induced oogenesis in the presence of 0.16–0.27 μM Fe species complexed with SWEOM. However, no oogenesis was observed in the presence of 1 μM Fe species complexed with N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, an inert Fe-containing complex. These results show that SWEOM can serve as a chelator for Fe fertilization. Moreover, the concentration of SWEOM extracted from a bark compost was more than ten times higher than the corresponding values obtained from dredged soil and peat, suggesting this type of compost represents a suitable source of SWEOM. These findings extend our current knowledge of the use of Fe fertilization for the restoration of seaweed beds.

Super-resolution imaging of lateral distribution for the blue-light emission of an InGaN single-quantum-well structure utilizing the stimulated emission depletion effect.

We have observed a remarkable decrease in photoluminescence (PL) from a blue-light emitting InGaN single-quantum-well (SQW) structure under the radiation of a green laser due to the stimulated emission depletion (STED) phenomenon. By extending the observed STED effect, super-resolution imaging of the blue-light emission lateral distribution was demonstrated for the InGaN-SQW structure through co-irradiation using a doughnut-shaped green light beam and a Gaussian-shaped violet excitation light beam. We measured point-spread functions (PSFs) to evaluate the spatial resolution of the system by imaging a small emission area. A lateral PSF size of ~150 nm was confirmed, which was approximately 40% smaller than that without the STED beam. This demonstrates that the STED technique is applicable for PL imaging of semiconductor quantum structures. The present approach may make possible a new strategy for characterizing and investigating the spatial inhomogeneity of emission properties and carrier dynamics in InGaN-based quantum wells, as well as in other semiconductor materials exhibiting quantum confinement effects.

Study of crossover and depletion effects in laminar flow-based fuel cells using electrochemical impedance spectroscopy

Abstract The impedance characteristics of the laminar flow-based fuel cells (LFFCs), which are also called microfluidic fuel cells (MFFCs), are measured to study the crossover and depletion phenomena. To study the effect of the crossover and depletion separately, the impedances are measured at different flow rates simulating different crossover conditions; while the effect of depletion is controlled by keeping the current density constant through changing the fuel concentration at different flow rates. Then the depletion effect is studied by measuring the impedance characteristics of the cell at various fuel concentrations. It is shown that the crossover affects the moderate frequency ranges in the measured Nyquist plot; whereas depletion impacts the low frequency domain. Finally, the impedance measurements at various potentials suggest that increasing the current density increases the effect of crossover while decreases the effect of depletion. This could be the result of carbon dioxide production in the anode.

Lifting the off-state bandgap limit in InAs channel metal-oxide-semiconductor heterostructures of nanometer dimensions

One of the major challenges of high mobility complementary metal-oxide-semiconductor (CMOS) circuits is to meet off-current requirements of &amp;lt;100 pA/μm for low stand-by power (LSTP) operation due to the small bandgap (≤0.5 eV) of the channel material (bandgap limit). In this work, we present experimental proof that the bandgap limit can be overcome at nanometer dimensions leveraging the phenomenon of steady state deep depletion (SSDD). The occurrence of SSDD is investigated using high-k capacitors with 5 and 10 nm InAs channel on a n- or p-type doped lattice matched wide bandgap AlAsSb layer. Absence of charge carriers at the off-state band edge is observed for 5 nm InAs channel layers demonstrating occurrence of SSDD and lifting of the off-state bandgap limit providing a path to meet LSTP requirements for future high mobility CMOS.

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

Abstract. In this paper we provide an overview of new knowledge on oxygen depletion (hypoxia) and related phenomena in aquatic systems resulting from the EU-FP7 project HYPOX ("In situ monitoring of oxygen depletion in hypoxic ecosystems of coastal and open seas, and landlocked water bodies", http://www.hypox.net). In view of the anticipated oxygen loss in aquatic systems due to eutrophication and climate change, HYPOX was set up to improve capacities to monitor hypoxia as well as to understand its causes and consequences. Temporal dynamics and spatial patterns of hypoxia were analyzed in field studies in various aquatic environments, including the Baltic Sea, the Black Sea, Scottish and Scandinavian fjords, Ionian Sea lagoons and embayments, and Swiss lakes. Examples of episodic and rapid (hours) occurrences of hypoxia, as well as seasonal changes in bottom-water oxygenation in stratified systems, are discussed. Geologically driven hypoxia caused by gas seepage is demonstrated. Using novel technologies, temporal and spatial patterns of water-column oxygenation, from basin-scale seasonal patterns to meter-scale sub-micromolar oxygen distributions, were resolved. Existing multidecadal monitoring data were used to demonstrate the imprint of climate change and eutrophication on long-term oxygen distributions. Organic and inorganic proxies were used to extend investigations on past oxygen conditions to centennial and even longer timescales that cannot be resolved by monitoring. The effects of hypoxia on faunal communities and biogeochemical processes were also addressed in the project. An investigation of benthic fauna is presented as an example of hypoxia-devastated benthic communities that slowly recover upon a reduction in eutrophication in a system where naturally occurring hypoxia overlaps with anthropogenic hypoxia. Biogeochemical investigations reveal that oxygen intrusions have a strong effect on the microbially mediated redox cycling of elements. Observations and modeling studies of the sediments demonstrate the effect of seasonally changing oxygen conditions on benthic mineralization pathways and fluxes. Data quality and access are crucial in hypoxia research. Technical issues are therefore also addressed, including the availability of suitable sensor technology to resolve the gradual changes in bottom-water oxygen in marine systems that can be expected as a result of climate change. Using cabled observatories as examples, we show how the benefit of continuous oxygen monitoring can be maximized by adopting proper quality control. Finally, we discuss strategies for state-of-the-art data archiving and dissemination in compliance with global standards, and how ocean observations can contribute to global earth observation attempts.

On the signal depletion induced by stretching excitation of methane in the reaction with the F atom

Exciting a stretching mode of a chemical bond should help its breaking during a chemical reaction, according to conventional wisdom. In several recent studies of the reactions of stretch-excited methane (and isotopologues) with the F atom, counterintuitively, we found that the induced reactant vibrations instead inhibit the bond rupture and slow down the overall reaction rate. This intriguing observation has been qualitatively ascribed to the vibrationally induced steric effects of the reaction in previous reports. However, quantitative determination of the reactivity suppression in terms of reaction cross sections remains lacking. In this report, we scrutinize the physical meaning of this (product) signal depletion phenomenon and fill the gap. Through a systematic investigation we further elucidate the additional reaction dynamics information that can be retrieved from the depletion measurements. The resultant rotationally state-selected reaction cross sections for both the vibrational ground and excited states are presented, and the stereodynamical implications are delineated.

Towards an entropy-based detached-eddy simulation

A concept of entropy increment ratio (sI) is introduced for compressible turbulence simulation through a series of direct numerical simulations (DNS). sI represents the dissipation rate per unit mechanical energy with the benefit of independence of freestream Mach numbers. Based on this feature, we construct the shielding function f (s) to describe the boundary layer region and propose an entropy-based detached-eddy simulation method (SDES). This approach follows the spirit of delayed detached-eddy simulation (DDES) proposed by Spalart et al. in 2005, but it exhibits much better behavior after their performances are compared in the following flows, namely, pure attached flow with thick boundary layer (a supersonic flat-plate flow with high Reynolds number), fully separated flow (the supersonic base flow), and separated-reattached flow (the supersonic cavity-ramp flow). The Reynolds-averaged Navier-Stokes (RANS) resolved region is reliably preserved and the modeled stress depletion (MSD) phenomenon which is inherent in DES and DDES is partly alleviated. Moreover, this new hybrid strategy is simple and general, making it applicable to other models related to the boundary layer predictions.

Micro-chemical and micro-structural investigation of archaeological bronze weapons from the Ayanis fortress (lake Van, Eastern Anatolia, Turkey)

Bronze weapons (VII cen BC) found during the archaeological excavation of the Ayanis fortress (lake Van, eastern Anatolia, Turkey) are investigated in order to determine their chemical composition and metallurgical features as well as to identify the micro-chemical and micro-structural nature of the corrosion products grown during long-term burial. Small fragments were sampled from the artefacts and analysed by means of the combined use of optical microscopy (OM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show that the bronze artefacts have been manufactured by using alloys with a controlled and refined chemical composition demonstrating the high level metallurgical competence and skill of the Urartian craftsmen and artists. Furthermore, the micro-structural and metallurgical investigations evidence the presence of equiaxed grains in the matrix, indicating that the artefact were produced by repeated cycles of mechanical shaping and thermal annealing treatments to restore the alloy ductility. From the degradation point of view, the results show the structures and the chemical composition of the stratified corrosion layers (i.e. the patina) where the copper or tin depletion phenomenon is commonly observed with the surface enrichment of some elements coming from the burial soil, mainly Cl, which is related to the high concentration of chlorides in the Ayanis soil. The results reveal also that another source of degradation is the inter-granular corrosion phenomenon likely increased by the metallurgical features of the alloys caused by the high temperature manufacturing process that induces crystallisation and segregation phenomena along the grain boundaries.

Preferential localization of Lactococcus lactis cells entrapped in a caseinate/alginate phase separated system

This study aimed to entrap bioprotective lactic acid bacteria in a sodium caseinate/sodium alginate aqueous two-phase system. Phase diagram at pH=7 showed that sodium alginate and sodium caseinate were not miscible when their concentrations exceeded 1% (w/w) and 6% (w/w), respectively. The stability of the caseinate/alginate two-phase system was also checked at pH values of 6.0 and 5.5. Lactococcus lactis subsp. lactis LAB3 cells were added in a 4% (w/w) caseinate/1.5% (w/w) alginate two-phase system at pH=7. Fluorescence microscopy allowed to observe that the caseinate-rich phase formed droplets dispersed in a continuous alginate-rich phase. The distribution of bacteria in such a system was observed by epifluorescence microscopy: Lc. lactis LAB3 cells stained with Live/Dead® Baclight kit™ were located exclusively in the protein phase. Since zeta-potential measurements indicated that alginate, caseinate and bacterial cells all had an overall negative charge at pH 7, the preferential adhesion of LAB cells was assumed to be driven by hydrophobic effect or by depletion phenomena in such biopolymeric systems. Moreover, LAB cells viability was significantly higher in the ternary mixture obtained in the presence of both caseinate and alginate than in single alginate solution. Caseinate/alginate phase separated systems appeared thus well suited for Lc. lactis LAB3 cells entrapment.

Neutral Gas Expansion in a Cylindrical Helicon Discharge Chamber

The expansion of neutral gas in an open-ended cylindrical chamber into a large vacuum facility is investigated to understand neutral particle density distribution. The cylindrical chamber geometry with a single on-axis gas injection port is representative of a helicon plasma source discharge chamber. The neutral gas pressure profile along the cylinder wall is experimentally measured for argon and xenon mass flow rates of 0–200 sccm, at facility pressures up to and and torr Xe, respectively. The average relative error between the experimentally measured pressure profiles and the numerical results obtained with a direct simulation Monte Carlo code is less than 10%, with the maximum relative error below 30%. The single on-axis injection port into the cylindrical discharge chamber results in a nonuniform neutral particle density distribution in the source due to the recirculation zone generated in the rear of the discharge chamber. This highlights the potential impact of the propellant injection system design on the neutral particle depletion phenomenon in helicon plasma sources.

Micro‐structural and micro‐chemical composition of bronze artefacts from Tharros (Western Sardinia, Italy)

The present work reports the results of the SEM–energy dispersive spectrometry, X‐ray diffraction (XRD), XPS and optical microscopy (OM) investigations performed to identify the corrosion products nature, i.e. the patina, grown on bronze common use artefacts found during excavations carried out at Tharros (on the west coast of Sardinia, Italy). The micro‐chemical investigations of the patina revealed the structure and the chemical composition of the stratified corrosion layers, where tin depletion phenomenon has been observed within some cases of a surface enrichment of lead combined with elements coming from the soil such as Cl and P and mixed with other burial elements such as Ca, Si, Fe, Si and Al. The presence of soil elements was also confirmed by XPS investigations that evidence from the lineshape analysis and Binding Energy (BE) values of Cu 2p, Sn 3 d and Pb 4f photoemission signals that these elements are mainly present in their maximum oxidation states on the surface. The surface information is confirmed by OM and XRD results that evidence also the presence of copper trihydroxychlorides. In the inner layers, OM, SEM–energy dispersive spectrometry and XRD results disclose the presence of Cu (I) compounds such as cuprite (Cu2O) and nantokite (CuCl), the latter being the specie that induces the cyclic and self‐sustaining degradation process commonly defined ‘bronze disease’. The micro‐chemical and micro‐structural informations demonstrate the strict interaction between soil components and corrosion products that form different compounds as a function of the local characteristics of the soil and of the chemical composition and metallurgical features of the Cu‐based alloys. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Interpretation of ac dielectrophoretic behavior of tin oxide nanobelts using Maxwell stress tensor approach modeling

In order to explain the dielectrophoretic behavior of ethanol suspended tin oxide (SnO 2) nanobelts observed experimentally, modeling of the ac dielectrophoresis (DEP) phenomenon is carried out. Nanobelts are a type of ribbon like semiconducting oxide nanowire with rectangular cross-sections. To calculate the DEP induced forces and torques the Maxwell stress tensor (MST) approach is used. DEP experiments have indicated negative DEP (repulsion) in the low frequency range (<100 kHz) and positive DEP (attraction) in the high frequency range (∼1–10 MHz) of the applied ac electric field. The experimentally observed DEP characteristic is unusual if the nanobelt is treated as possessing uniform bulk material electrical properties of tin oxide. Several different nanobelt models are studied using simulations to explain the unusual behavior. The model providing the best explanation is the one where the nanobelt has an electrically conductive interior and a non-conductive outer layer, depleted of charge carriers. This is consistent with the surface depletion phenomenon commonly observed in SnO 2 and other semiconducting metal oxide materials. This work demonstrates the importance of surface dominant properties of nanostructures in DEP manipulation and assembly.