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1
Weber, S. L. "A timescale analysis of the NH temperature response to volcanic and solar forcing in the past millenium". Climate of the Past Discussions 1, n. 2 (8 settembre 2005): 137–53. http://dx.doi.org/10.5194/cpd-1-137-2005.
Testo completoAbstract (sommario):
Abstract. The Northern Hemisphere temperature response to volcanic and solar forcing is studied using first a set of simulations with an intermediate-complexity climate model, driven by reconstructed forcings. Results are than compared with those obtained from the seven high-resolution reconstructed temperature records for the last millenium that are at present available. Focus of the analysis is on the timescale dependence of the response. Results between the model and the proxy-based reconstructions are remarkably consistent. The response to solar forcing is found to equilibrate at interdecadal timescales, reaching an equilibrium value for the regression of 0.2-0.3°C per W/m2. The time interval between volcanic eruptions is typically shorter than the dissipation timescale of the climate system, so that the response to volcanic forcing never equilibrates. As a result, the regression on the volcanic forcing is always lower than the equilibrium value and goes to zero for the longest temporal scales. The trends over the pre-anthropogenic period are found to be relatively large in all reconstructed temperature records compared to their interdecadal-centennial variability. This is at variance with a recent claim that reconstructed temperature records underestimate climatic variations at multi-centennial scales.
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Weber, S. L. "A timescale analysis of the Northern Hemisphere temperature response to volcanic and solar forcing". Climate of the Past 1, n. 1 (5 dicembre 2005): 9–17. http://dx.doi.org/10.5194/cp-1-9-2005.
Testo completoAbstract (sommario):
Abstract. The Northern Hemisphere temperature response to volcanic and solar forcing in the time interval 1000–1850 AD is studied using first a set of simulations with an intermediate-complexity climate model, driven by reconstructed forcings. Results are then compared with those obtained from the seven high-resolution reconstructed temperature records for the last millenium that are at present available. Focus of the analysis is on the timescale dependence of the response. Results between the model and the proxy-based reconstructions are remarkably consistent. The response to solar forcing is found to equilibrate at interdecadal timescales, reaching an equilibrium value for the regression of 0.2–0.3°C per W/m2. The time interval between volcanic eruptions is typically shorter than the dissipation timescale of the climate system, so that the response to volcanic forcing never equilibrates. As a result, the regression on the volcanic forcing is always lower than the equilibrium value and goes to zero for the longest temporal scales. The trends over the pre-anthropogenic period are found to be relatively large in all reconstructed temperature records, given the trends in the reconstructed forcing and the equilibrium value for the regression. This is at variance with a recent claim that reconstructed temperature records underestimate climatic variations at multi-centennial timescales.
3
Yutkin, Maxim P., Himanshu Mishra, Tadeusz W. Patzek, John Lee e Clayton J. Radke. "Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs". SPE Journal 23, n. 01 (25 agosto 2017): 84–101. http://dx.doi.org/10.2118/182829-pa.
Testo completoAbstract (sommario):
Summary Low-salinity waterflooding (LSW) is ineffective when reservoir rock is strongly water-wet or when crude oil is not asphaltenic. Success of LSW relies heavily on the ability of injected brine to alter surface chemistry of reservoir crude-oil brine/rock (COBR) interfaces. Implementation of LSW in carbonate reservoirs is especially challenging because of high reservoir-brine salinity and, more importantly, because of high reactivity of the rock minerals. Both features complicate understanding of the COBR surface chemistries pertinent to successful LSW. Here, we tackle the complex physicochemical processes in chemically active carbonates flooded with diluted brine that is saturated with atmospheric carbon dioxide (CO2) and possibly supplemented with additional ionic species, such as sulfates or phosphates. When waterflooding carbonate reservoirs, rock equilibrates with the injected brine over short distances. Injected-brine ion speciation is shifted substantially in the presence of reactive carbonate rock. Our new calculations demonstrate that rock-equilibrated aqueous pH is slightly alkaline quite independent of injected-brine pH. We establish, for the first time, that CO2 content of a carbonate reservoir, originating from CO2-rich crude oil and gas, plays a dominant role in setting aqueous pH and rock-surface speciation. A simple ion-complexing model predicts the calcite-surface charge as a function of composition of reservoir brine. The surface charge of calcite may be positive or negative, depending on speciation of reservoir brine in contact with the calcite. There is no single point of zero charge; all dissolved aqueous species are charge determining. Rock-equilibrated aqueous composition controls the calcite-surface ion-exchange behavior, not the injected-brine composition. At high ionic strength, the electrical double layer collapses and is no longer diffuse. All surface charges are located directly in the inner and outer Helmholtz planes. Our evaluation of calcite bulk and surface equilibria draws several important inferences about the proposed LSW oil-recovery mechanisms. Diffuse double-layer expansion (DLE) is impossible for brine ionic strength greater than 0.1 molar. Because of rapid rock/brine equilibration, the dissolution mechanism for releasing adhered oil is eliminated. Also, fines mobilization and concomitant oil release cannot occur because there are few loose fines and clays in a majority of carbonates. LSW cannot be a low-interfacial-tension alkaline flood because carbonate dissolution exhausts all injected base near the wellbore and lowers pH to that set by the rock and by formation CO2. In spite of diffuse double-layer collapse in carbonate reservoirs, surface ion-exchange oil release remains feasible, but unproved.
4
D'Avanzo, Nazzareno, Hee Cheol Cho, Illya Tolokh, Roman Pekhletski, Igor Tolokh, Chris Gray, Saul Goldman e Peter H. Backx. "Conduction through the Inward Rectifier Potassium Channel, Kir2.1, Is Increased by Negatively Charged Extracellular Residues". Journal of General Physiology 125, n. 5 (11 aprile 2005): 493–503. http://dx.doi.org/10.1085/jgp.200409175.
Testo completoAbstract (sommario):
Ion channel conductance can be influenced by electrostatic effects originating from fixed “surface” charges that are remote from the selectivity filter. To explore whether surface charges contribute to the conductance properties of Kir2.1 channels, unitary conductance was measured in cell-attached recordings of Chinese hamster ovary (CHO) cells transfected with Kir2.1 channels over a range of K+ activities (4.6–293.5 mM) using single-channel measurements as well as nonstationary fluctuation analysis for low K+ activities. K+ ion concentrations were shown to equilibrate across the cell membrane in our studies using the voltage-sensitive dye DiBAC4(5). The dependence of γ on the K+ activity (aK) was fit well by a modified Langmuir binding isotherm, with a nonzero intercept as aK approaches 0 mM, suggesting electrostatic surface charge effects. Following the addition of 100 mM N-methyl-d-glucamine (NMG+), a nonpermeant, nonblocking cation or following pretreatment with 50 mM trimethyloxonium (TMO), a carboxylic acid esterifying agent, the γ–aK relationship did not show nonzero intercepts, suggesting the presence of surface charges formed by glutamate or aspartate residues. Consistent with surface charges in Kir2.1 channels, the rates of current decay induced by Ba2+ block were slowed with the addition of NMG or TMO. Using a molecular model of Kir2.1 channels, three candidate negatively charged residues were identified near the extracellular mouth of the pore and mutated to cysteine (E125C, D152C, and E153C). E153C channels, but not E125C or D152C channels, showed hyperbolic γ–aK relationships going through the origin. Moreover, the addition of MTSES to restore the negative charges in E53C channels reestablished wild-type conductance properties. Our results demonstrate that E153 contributes to the conductance properties of Kir2.1 channels by acting as a surface charge.
5
Munday, David R., Helen L. Johnson e David P. Marshall. "Eddy Saturation of Equilibrated Circumpolar Currents". Journal of Physical Oceanography 43, n. 3 (1 marzo 2013): 507–32. http://dx.doi.org/10.1175/jpo-d-12-095.1.
Testo completoAbstract (sommario):
Abstract This study uses a sector configuration of an ocean general circulation model to examine the sensitivity of circumpolar transport and meridional overturning to changes in Southern Ocean wind stress and global diapycnal mixing. At eddy-permitting, and finer, resolution, the sensitivity of circumpolar transport to forcing magnitude is drastically reduced. At sufficiently high resolution, there is little or no sensitivity of circumpolar transport to wind stress, even in the limit of no wind. In contrast, the meridional overturning circulation continues to vary with Southern Ocean wind stress, but with reduced sensitivity in the limit of high wind stress. Both the circumpolar transport and meridional overturning continue to vary with diapycnal diffusivity at all model resolutions. The circumpolar transport becomes less sensitive to changes in diapycnal diffusivity at higher resolution, although sensitivity always remains. In contrast, the overturning circulation is more sensitive to change in diapycnal diffusivity when the resolution is high enough to permit mesoscale eddies.
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Sentman, Lori T., Elena Shevliakova, Ronald J. Stouffer e Sergey Malyshev. "Time Scales of Terrestrial Carbon Response Related to Land-Use Application: Implications for Initializing an Earth System Model". Earth Interactions 15, n. 30 (1 ottobre 2011): 1–16. http://dx.doi.org/10.1175/2011ei401.1.
Testo completoAbstract (sommario):
Abstract The dynamic vegetation and carbon cycling component, LM3V, of the Geophysical Fluid Dynamics Laboratory (GFDL) prototype Earth system model (ESM2.1), has been designed to simulate the effects of land use on terrestrial carbon pools, including secondary vegetation regrowth. Because of the long time scales associated with the carbon adjustment, special consideration is required when initializing the ESM when historical simulations are conducted. Starting from an equilibrated, preindustrial climate and potential vegetation state in an offline land-only model (LM3V), estimates of historical land use are instantaneously applied in five experiments beginning in the following calendar years: 1500, 1600, 1700, 1750, and 1800. This application results in the land carbon pools experiencing an abrupt change—a carbon shock—and the secondary vegetation needs time to regrow into consistency with the harvesting history. The authors find that it takes approximately 100 years for the vegetation to recover from the carbon shock, whereas soils take at least 150 years to recover. The vegetation carbon response is driven primarily by land-use history, whereas the soil carbon response is affected by both land-use history and the geographic pattern of soil respiration rates. Based on these results, the authors recommend the application of historical land-use scenarios in 1700 to provide sufficient time for the land carbon in ESMs with secondary vegetation to equilibrate to adequately simulate carbon stores at the start of the historical integrations (i.e., 1860) in a computationally efficient manner.
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Messias, Andresa, Denys E. S. Santos, Frederico J. S. Pontes, Filipe S. Lima e Thereza A. Soares. "Out of Sight, Out of Mind: The Effect of the Equilibration Protocol on the Structural Ensembles of Charged Glycolipid Bilayers". Molecules 25, n. 21 (4 novembre 2020): 5120. http://dx.doi.org/10.3390/molecules25215120.
Testo completoAbstract (sommario):
Molecular dynamics (MD) simulations represent an essential tool in the toolbox of modern chemistry, enabling the prediction of experimental observables for a variety of chemical systems and processes and majorly impacting the study of biological membranes. However, the chemical diversity of complex lipids beyond phospholipids brings new challenges to well-established protocols used in MD simulations of soft matter and requires continuous assessment to ensure simulation reproducibility and minimize unphysical behavior. Lipopolysaccharides (LPS) are highly charged glycolipids whose aggregation in a lamellar arrangement requires the binding of numerous cations to oppositely charged groups deep inside the membrane. The delicate balance between the fully hydrated carbohydrate region and the smaller hydrophobic core makes LPS membranes very sensitive to the choice of equilibration protocol. In this work, we show that the protocol successfully used to equilibrate phospholipid bilayers when applied to complex lipopolysaccharide membranes occasionally leads to a small expansion of the simulation box very early in the equilibration phase. Although the use of a barostat algorithm controls the system dimension and particle distances according to the target pressure, fluctuation in the fleeting pressure occasionally enables a few water molecules to trickle into the hydrophobic region of the membrane, with spurious solvent buildup. We show that this effect stems from the initial steps of NPT equilibration, where initial pressure can be fairly high. This can be solved with the use of a stepwise-thermalization NVT/NPT protocol, as demonstrated for atomistic MD simulations of LPS/DPPE and lipid-A membranes in the presence of different salts using an extension of the GROMOS forcefield within the GROMACS software. This equilibration protocol should be standard procedure for the generation of consistent structural ensembles of charged glycolipids starting from atomic coordinates not previously pre-equilibrated. Although different ways to deal with this issue can be envisioned, we investigated one alternative that could be readily available in major MD engines with general users in mind.
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Roland, Steffen, Juliane Kniepert, John A. Love, Vikas Negi, Feilong Liu, Peter Bobbert, Armantas Melianas, Martijn Kemerink, Andreas Hofacker e Dieter Neher. "Equilibrated Charge Carrier Populations Govern Steady-State Nongeminate Recombination in Disordered Organic Solar Cells". Journal of Physical Chemistry Letters 10, n. 6 (4 marzo 2019): 1374–81. http://dx.doi.org/10.1021/acs.jpclett.9b00516.
Testo completo
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Van Breedam, Jonas, Heiko Goelzer e Philippe Huybrechts. "Semi-equilibrated global sea-level change projections for the next 10 000 years". Earth System Dynamics 11, n. 4 (6 novembre 2020): 953–76. http://dx.doi.org/10.5194/esd-11-953-2020.
Testo completoAbstract (sommario):
Abstract. The emphasis for informing policy makers on future sea-level rise has been on projections by the end of the 21st century. However, due to the long lifetime of atmospheric CO2, the thermal inertia of the climate system and the slow equilibration of the ice sheets, global sea level will continue to rise on a multi-millennial timescale even when anthropogenic CO2 emissions cease completely during the coming decades to centuries. Here we present global sea-level change projections due to the melting of land ice combined with steric sea effects during the next 10 000 years calculated in a fully interactive way with the Earth system model of intermediate complexity LOVECLIMv1.3. The greenhouse forcing is based on the Extended Concentration Pathways defined until 2300 CE with no carbon dioxide emissions thereafter, equivalent to a cumulative CO2 release of between 460 and 5300 GtC. We performed one additional experiment for the highest-forcing scenario with the inclusion of a methane emission feedback where methane is slowly released due to a strong increase in surface and oceanic temperatures. After 10 000 years, the sea-level change rate drops below 0.05 m per century and a semi-equilibrated state is reached. The Greenland ice sheet is found to nearly disappear for all forcing scenarios. The Antarctic ice sheet contributes only about 1.6 m to sea level for the lowest forcing scenario with a limited retreat of the grounding line in West Antarctica. For the higher-forcing scenarios, the marine basins of the East Antarctic Ice Sheet also become ice free, resulting in a sea-level rise of up to 27 m. The global mean sea-level change after 10 000 years ranges from 9.2 to more than 37 m. For the highest-forcing scenario, the model uncertainty does not exclude the complete melting of the Antarctic ice sheet during the next 10 000 years.
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Cardoso, Eveline Coelho, e Glayci Kelli Reis da S. Xavier. "Tempo e narrativa no gênero charge: condensar para potencializar". Veredas: Revista da Associação Internacional de Lusitanistas, n. 31 (5 maggio 2020): 155–74. http://dx.doi.org/10.24261/2183-816x0931.
Testo completoAbstract (sommario):
O rompimento da barragem construída pela mineradora brasileira Vale, que devastou a cidade de Brumadinho (MG) em janeiro de 2019, é o tema de seis charges que compõem o corpus do presente artigo. Sob a perspectiva de análise do discurso semiolinguística, as charges são gêneros discursivos oriundos de um contrato comunicativo midiático, equilibrado, como tal, entre duas intenções principais: informar e captar o leitor. Driblando, contudo, a objetividade e credibilidade típicas da mídia, as charges narram uma versão pessoal e crítica da realidade, expressa em uma verbo-visualidade “carregada” de opinião, humor e ironia. Veremos, pois, de que maneira tais textos manifestam a temporalidade por meio de mecanismos linguísticos e simbólicos das histórias em quadrinhos, que lhes permitem romper a aparente fixidez de sua estrutura.
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Morel, Christian, Noura Ziadi, Aimé Messiga, Gilles Bélanger, Pascal Denoroy, Bernard Jeangros, Claire Jouany et al. "Modeling of phosphorus dynamics in contrasting agroecosystems using long-term field experiments". Canadian Journal of Soil Science 94, n. 3 (agosto 2014): 377–87. http://dx.doi.org/10.4141/cjss2013-024.
Testo completoAbstract (sommario):
Morel, C., Ziadi, N., Messiga, A., Bélanger, G., Denoroy, P., Jeangros, B., Jouany, C., Fardeau, J. C., Mollier, A., Parent, L. E., Proix, N., Rabeharisoa, L. and Sinaj, S. 2014. Modeling of phosphorus dynamics in contrasting agroecosystems using long-term field experiments. Can. J. Soil Sci. 94: 377–387. Long-term field experiments on phosphorus (P) fertilization were originally designed to study crop needs in different soil types by analyzing the effects of several rates of P fertilization on yields, their P concentrations and dynamics of plant-available soil P. The objective of this study was to test a computer-based model to simulate the P dynamics at the field scale using plant database and analyzing for plant-available P by a hierarchical process-based approach. It predicts both the concentration (CP) of phosphate ions (Pi) in soil solution and the associated Pi amounts that in time equilibrate with Pi in solution. Five experiments, representative of contrasting soil types, land-use, and climates were selected. Our model equilibrates the change in plant-available P in the upper soil layer to the P budget between annual P inputs and outputs. Rates of P fertilization affected simulations following the same expected pattern across sites. Field-observed and simulated values are in good agreements in all sites. The field-observed variations of CP per unit of P budget ranged from 0.007 to 2.49 (µg P L−1) (kg P ha−1)−1. The predictions are of the same order of magnitude. Predictions were compared with empirical long-term data and mismatches were discussed. This investigation highlights the scientific interest of long-term field P experiments to test and validate models describing P dynamics at the scale of the agricultural fields under different agricultural management practices.
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Cui, Leyu, Kun Ma, Ahmed A. Abdala, Lucas J. Lu, Ivan Tanakov, Sibani L. Biswal e George J. Hirasaki. "Adsorption of a Switchable Cationic Surfactant on Natural Carbonate Minerals". SPE Journal 20, n. 01 (11 settembre 2014): 70–78. http://dx.doi.org/10.2118/169040-pa.
Testo completoAbstract (sommario):
Summary A switchable cationic surfactant (e.g., tertiary amine surfactant Ethomeen C12) was previously described as a surfactant that one can inject in high-pressure carbon dioxide (CO2) for foam-mobility control. C12 can dissolve in high-pressure CO2 as a nonionic surfactant and equilibrate with brine as a cationic surfactant. Here, we describe the adsorption characteristics of this surfactant in carbonate-formation materials. The adsorption of this surfactant is sensitive to the equilibrium pH, the electrolyte composition of the brine, and the minerals in carbonate-formation materials. Pure C12 is a nonionic surfactant. When it is mixed with brine, the solution has a high pH and limited solubility. However, when the surfactant solution in brine is equilibrated with high-pressure CO2, the pH is approximately 4; the surfactant switches to a cationic surfactant and becomes soluble. Thus, the adsorption is also a function of pH. The adsorption of C12 on calcite at low pH is low (e.g., 0.5 mg/m2). However, if the carbonate formation contains silica or clays, the adsorption is high, as is typical for cationic surfactants. The adsorption of C12 on silica decreases with an increase in divalent (Ca2+ and Mg2+) and trivalent (Al3+) cations. This is because of the competition for the negatively charged silica sites between the multivalent cations and the monovalent cationic surfactant. An additional effect of the presence of divalent cations in the brine is that it reduces the dissolution of calcite or dolomite in the presence of high-pressure CO2. The dissolution of calcite and dolomite is harmful because of formation damage and increased alkalinity. The latter raises the pH and thus increases the adsorption of C12 or even causes surfactant precipitation.
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Kirchberg, Henning, e Abraham Nitzan. "Energy transfer and thermoelectricity in molecular junctions in non-equilibrated solvents". Journal of Chemical Physics 156, n. 9 (7 marzo 2022): 094306. http://dx.doi.org/10.1063/5.0086319.
Testo completoAbstract (sommario):
We consider a molecular junction immersed in a solvent where the electron transfer is dominated by Marcus-type steps. However, the successive nature of the charge transfer through the junction does not imply that the solvent reaches thermal equilibrium throughout the transport. In our previous work [Kirchberg et al., J. Phys. Chem. Lett. 11, 1729 (2020)], we have determined the nonequilibrium distribution of the solvent where its dynamics, expressed by a friction, is considered in two limiting regimes of fast and slow solvent relaxation. In dependence of the nonequilibrium solvent dynamics, we investigate now the electrical, thermal, and thermoelectric properties of the molecular junction. We show that by suitable tuning of the friction, we can reduce the heat dissipation into the solvent and enhance the heat transfer between the electrodes. Interestingly, we find that the Seebeck coefficient grows significantly by adapting the solvent friction in both regimes.
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Perera, Lalith, Thomas Darden e Lee Pedersen. "Modeling Human Zymogen Factor IX". Thrombosis and Haemostasis 85, n. 04 (2001): 596–603. http://dx.doi.org/10.1055/s-0037-1615639.
Testo completoAbstract (sommario):
SummaryModern theoretical techniques are employed to provide complete three dimensional structure for the zymogen and activated forms of human coagulation factors IX and IXa. These structures are fully calcium bound and equilibrated in an electrically neutral aqueous environment. The relationship of structure to mutational data is examined. We find that a substantial relative orientational change of the catalytic domain occurs on activation. Also, we find that the electrostatistically dipolar nature of the catalytic domain is substantially modified upon activation, with cleavage of the negatively charged activation peptide leaving behind a largely hydrophobic face in factor IXa. While the backbone atoms of the catalytic residues have little relative movement, nearby loops are found that do move. The presence or absence of these changes likely defines specificity.
15
Schaeffer, Bernard. "Electric and Magnetic Coulomb Potentials in the Deuteron". Advanced Electromagnetics 2, n. 1 (27 settembre 2013): 69. http://dx.doi.org/10.7716/aem.v2i1.218.
Testo completoAbstract (sommario):
After one century of nuclear physics, the underlying fun- damental laws of nuclear physics are still missing. Bohr had found a formula for the H atom and another for the H2 molecule but no equivalent formula exists for the deuteron 2H. The only known Coulomb interaction in a nucleus by the mainstream nuclear physics is the long range repulsion between protons, forgetting that the neutron contains elec- tric charges with no net charge. The neutron is attracted by the proton in a way discovered two millenaries ago by the Greeks. This attraction is equilibrated by the repulsion between the opposite magnetic moments of the proton and of the neutron in the deuteron. The bare application of ge- ometry together with electric and magnetic Coulomb’s in- teractions accounts for the binding energy of the deuteron, without fitting, with only 4 per cent discrepancy, proving the electromagnetic nature of the nuclear energy.
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Koc, Julian, Lisa Schardt, Kim Nolte, Cindy Beyer, Till Eckhard, Philipp Schwiderowski, Jessica L. Clarke et al. "Effect of Dipole Orientation in Mixed, Charge-Equilibrated Self-assembled Monolayers on Protein Adsorption and Marine Biofouling". ACS Applied Materials & Interfaces 12, n. 45 (28 ottobre 2020): 50953–61. http://dx.doi.org/10.1021/acsami.0c11580.
Testo completo
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Liang, Mao-Chang, Li-Ching Lin, Ka-Kit Tung, Yuk L. Yung e Shan Sun. "Impact of Climate Drift on Twenty-First-Century Projection in a Coupled Atmospheric–Ocean General Circulation Model". Journal of the Atmospheric Sciences 70, n. 10 (1 ottobre 2013): 3321–27. http://dx.doi.org/10.1175/jas-d-13-0149.1.
Testo completoAbstract (sommario):
Abstract Reducing climate drift in coupled atmosphere–ocean general circulation models (AOGCMs) usually requires 1000–2000 years of spinup, which has not been practical for every modeling group to do. For the purpose of evaluating the impact of climate drift, the authors have performed a multimillennium-long control run of the Goddard Institute for Space Studies model (GISS-EH) AOGCM and produced different twentieth-century historical simulations and subsequent twenty-first-century projections by branching off the control run at various stages of equilibration. The control run for this model is considered at quasi equilibration after a 1200-yr spinup from a cold start. The simulations that branched off different points after 1200 years are robust, in the sense that their ensemble means all produce the same future projection of warming, both in the global mean and in spatial detail. These robust projections differ from the one that was originally submitted to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), which branched off a not-yet-equilibrated control run. The authors test various common postprocessing schemes in removing climate drift caused by a not-yet-equilibrated ocean initial state and find them to be ineffective, judging by the fact that they differ from each other and from the robust results that branched off an equilibrated control. The authors' results suggest that robust twenty-first-century projections of the forced response can be achieved by running climate simulations from an equilibrated ocean state, because memory of the different initial ocean state is lost in about 40 years if the forced run is started from a quasi-equilibrated state.
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Köhler, Stephan, Jakub Hruka e Kevin Bishop. "Influence of organic acid site density on pH modeling of Swedish lakes". Canadian Journal of Fisheries and Aquatic Sciences 56, n. 8 (1 agosto 1999): 1461–70. http://dx.doi.org/10.1139/f99-097.
Testo completoAbstract (sommario):
A semidirect titration method was used to determine individual site densities of carboxylic acids present in natural organic matter originating from 74 Swedish lakes. The average carboxylic acid site density of natural organic matter of the studied lakes was 8.6 ± 1.6 µequiv.·mg total organic carbon-1, which is more variable than the site densities observed earlier in a set of streams. These data were then used to assess the effect on modeling pH and organic anion charge contribution caused by the natural variability in site density. Air-equilibrated pH was modeled with a median error of 0.08 pH unit, equivalent to a mean error in the charge balance of 9 µmol·L-1, using measured Cb-Ca and individually determined site densities. A better prediction of pH, however, was made using this average site density and the CBALK approach, which is a different method for estimating total buffering capacity. The mean error in pH prediction was decreased to 0.05 pH unit, equivalent to a mean error in the charge balance of 5 µmol·L-1. These uncertainties in pH prediction are significantly smaller than reported in other studies. This implies that the existing natural variation in site density does not lead to significant effects on modeling pH or anion charge contribution in surface waters in the pH range of 4.5-8.5. Filtered samples (0.45 µm) did not show any significant change in pH, total organic carbon, or site density compared with unfiltered samples.
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Santofimia, M. J., Lie Zhao e Jilt Sietsma. "Volume Change Associated to Carbon Partitioning from Martensite to Austenite". Materials Science Forum 706-709 (gennaio 2012): 2290–95. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2290.
Testo completoAbstract (sommario):
Annealing of martensite/austenite microstructures leads to the partitioning of carbon from martensite to austenite until the chemical potential of carbon equilibrates in both phases. This work calculates the volume change associated with this phenomenon using theoretical models for the carbon partitioning from martensite to austenite. Calculations are compared with experimentally determined volume changes. This comparison reveals that in the case of steels with higher contents of austenite-stabilizing elements, reported volume changes are satisfactory predicted assuming a low mobilily martensite/austenite interface. In the case of a steel with lower additions of austenite-stabilizing elements, experimentally measured expansions are considerably larger than predicted ones. The large measured volume expansions probably reflect the decomposition of the austenite.
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Lieberman, Robert C. "Ideas, Institutions, and Political Order: Explaining Political Change". American Political Science Review 96, n. 4 (dicembre 2002): 697–712. http://dx.doi.org/10.1017/s0003055402000394.
Testo completoAbstract (sommario):
Institutional approaches to explaining political phenomena suffer from three common limitations: reductionism, reliance on exogenous factors, and excessive emphasis on order and structure. Ideational approaches to political explanation, while often more sensitive to change and agency, largely exhibit the same shortcomings. In particular, both perspectives share an emphasis on discerning and explaining patterns of ordered regularity in politics, making it hard to explain important episodes of political change. Relaxing this emphasis on order and viewing politics as situated in multiple and not necessarily equilibrated order suggests a way of synthesizing institutional and ideational approaches and developing more convincing accounts of political change. In this view, change arises out of “friction” among mismatched institutional and ideational patterns. An account of American civil rights policy in the 1960s and 1970s, which is not amenable to either straightforward institutional or ideational explanation, demonstrates the advantages of the approach.
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RAZEIRA, MOISÉS, BARDO E. J. BODMANN e CÉSAR A. ZEN VASCONCELLOS. "STRANGE MATTER AND STRANGE STARS WITH TSALLIS STATISTICS". International Journal of Modern Physics D 16, n. 02n03 (febbraio 2007): 365–72. http://dx.doi.org/10.1142/s0218271807010134.
Testo completoAbstract (sommario):
We investigate the properties of β-equilibrated electrically charged neutral strange matter and strange stars at finite temperature in the framework of Tsallis statistics [C. Tsallis, J. Stat. Phys.52 (1988) 479]. As the main result of our study we find out that a QHD description of nuclear matter combined with Tsallis statistics may open new possibilities for nuclear matter models.
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Kwon, Taekyung, Andrew L. Harris, Angelo Rossi e Thaddeus A. Bargiello. "Molecular dynamics simulations of the Cx26 hemichannel: Evaluation of structural models with Brownian dynamics". Journal of General Physiology 138, n. 5 (17 ottobre 2011): 475–93. http://dx.doi.org/10.1085/jgp.201110679.
Testo completoAbstract (sommario):
The recently published crystal structure of the Cx26 gap junction channel provides a unique opportunity for elucidation of the structure of the conductive connexin pore and the molecular determinants of its ion permeation properties (conductance, current–voltage [I-V] relations, and charge selectivity). However, the crystal structure was incomplete, most notably lacking the coordinates of the N-terminal methionine residue, which resides within the pore, and also lacking two cytosolic domains. To allow computational studies for comparison with the known channel properties, we completed the structure. Grand canonical Monte Carlo Brownian dynamics (GCMC/BD) simulations of the completed and the published Cx26 hemichannel crystal structure indicate that the pore is too narrow to permit significant ion flux. The GCMC/BD simulations predict marked inward current rectification and almost perfect anion selectivity, both inconsistent with known channel properties. The completed structure was refined by all-atom molecular dynamics (MD) simulations (220 ns total) in an explicit solvent and POPC membrane system. These MD simulations produced an equilibrated structure with a larger minimal pore diameter, which decreased the height of the permeation barrier formed by the N terminus. GCMC/BD simulations of the MD-equilibrated structure yielded more appropriate single-channel conductance and less anion/cation selectivity. However, the simulations much more closely matched experimentally determined I-V relations when the charge effects of specific co- and posttranslational modifications of Cx26 previously identified by mass spectrometry were incorporated. We conclude that the average equilibrated structure obtained after MD simulations more closely represents the open Cx26 hemichannel structure than does the crystal structure, and that co- and posttranslational modifications of Cx26 hemichannels are likely to play an important physiological role by defining the conductance and ion selectivity of Cx26 channels. Furthermore, the simulations and data suggest that experimentally observed heterogeneity in Cx26 I-V relations can be accounted for by variation in co- and posttranslational modifications.
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Duran, Randolph S., e Gregory B. McKenna. "A torsional dilatometer for volume change measurements on deformed glasses: Instrument description and measurements on equilibrated glasses". Journal of Rheology 34, n. 6 (agosto 1990): 813–39. http://dx.doi.org/10.1122/1.550150.
Testo completo
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Glazer, A. M., N. Zhang, A. Bartasyte, D. S. Keeble, S. Huband, P. A. Thomas, I. Gregora, F. Borodavka, S. Margueron e J. Hlinka. "LiTaO3crystals with near-zero birefringence". Journal of Applied Crystallography 45, n. 5 (13 settembre 2012): 1030–37. http://dx.doi.org/10.1107/s0021889812035121.
Testo completoAbstract (sommario):
A study of vapour transport equilibrated crystals of LiTaO3shows periodic fringes that change with temperature. The origin of these fringes and their behaviour is explained in terms of domains with slanted walls. Micro-Raman measurements have been used to determine the Li2O concentration through the crystals, and by comparison with the observed fringe pattern the variation of birefringence with Li2O content has been determined.
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Rentsch, Rüdiger, e Ekkard Brinksmeier. "Numerical Simulation of Residual Stresses at the Grain and Sub-Grain Length Scale Using Atomistic Modeling". Materials Science Forum 524-525 (settembre 2006): 517–22. http://dx.doi.org/10.4028/www.scientific.net/msf.524-525.517.
Testo completoAbstract (sommario):
For modeling the deformation and the heat treatment related change of micro structural material properties, a crystal structure with several grains is analyzed using the molecular dynamics simulation. The generated atom arrangement has been equilibrated, sheared and tempered, and the resulting microstructures and stresses as well as their changes are presented. The shearing of the multiple grain model into the region of plastic deformation caused a significant change in its microstructure and introduced additional stress. On applying the heat treatment simulation, it was possible to show thermally induced relaxation processes in a microstructure using MD.
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Wang, Shun-Chung, Chun-Yu Liu e Yi-Hua Liu. "A Non-Dissipative Equalizer with Fast Energy Transfer Based on Adaptive Balancing Current Control". Electronics 9, n. 12 (24 novembre 2020): 1990. http://dx.doi.org/10.3390/electronics9121990.
Testo completoAbstract (sommario):
In this study, an active inductive equalizer with fast energy transfer based on adaptive balancing current control is proposed to rapidly equilibrate lithium-ion battery packs. A multiphase structure of equalizer formed by many specific parallel converter legs (PCLs) with bidirectional energy conversion serves as the power transfer stage to make the charge shuttle back and forth between the cell and sub-pack or sub-pack and sub-pack more flexible and efficient. This article focuses on dealing with the problem of slow balancing rate, which inherently arises from the reduction of balancing current as the voltage difference between the cells or sub-packs decreases, especially in the later period of equalization. An adaptive varied-duty-cycle (AVDC) algorithm is put forward here to accelerate the balance process. The devised method has taken the battery nonlinear behavior and the nonideality of circuit component into consideration and can adaptively modulate the duty cycle with the change of voltage differences to maintain balancing current nearly constant in the whole equilibrating procedure. Test results derived from simulations and experiments are provided to demonstrate the validity and effectiveness of the equalizer prototype constructed. Comparing with the conventional fixed duty cycle (FDC) method, the improvements of 68.3% and 8.3% in terms of balance time and efficiency have been achieved.
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Cardoso, Eveline Coelho. "Um golpe de vista midiático: o discurso da charge entre imagens e imaginários". Gragoatá 24, n. 50 (27 gennaio 2020): 809–28. http://dx.doi.org/10.22409/gragoata.v24i50.34164.
Testo completoAbstract (sommario):
O presente trabalho apresenta uma descrição do gênero discursivo charge, tendo por base os pressupostos da Teoria Semiolinguística de Análise do Discurso (CHARAUDEAU, 2010). Sob tal perspectiva, esse texto multimodal se limita às cláusulas de um contrato comunicativo midiático, cujas restrições conduzem à elaboração de um acontecimento comentado, equilibrado entre um duplo desejo de informar e captar. Por outro lado, desfrutando das liberdades de um “traço texto” de natureza humorística e irônica e plenamente afastado da objetividade jornalística, o enunciador chargista explora estratégias específicas de apelo da emoção mais do que da razão, o que está ancorado em saberes diversos, que permeiam as trocas comunicativas e sustentam sistemas coletivos de representações. Com o apoio da Teoria das Representações Sociais (MOSCOVICI, 2013; JODELET, 2001), veremos de que maneira tais saberes são explorados no comentário verbo-visual chargístico, impregnando de sentidos sua estrutura altamente condensada – que não se deixa interpretar à primeira vista. A peça que aqui nos serve como objeto de estudo é do cartunista carioca Carlos Latuff e traduz um olhar intertextual sobre a educação no Rio de Janeiro.
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Ballarotta, M., L. Brodeau, J. Brandefelt, P. Lundberg e K. Döös. "A Last Glacial Maximum world-ocean simulation at eddy-permitting resolution – Part 1: Experimental design and basic evaluation". Climate of the Past Discussions 9, n. 1 (18 gennaio 2013): 297–328. http://dx.doi.org/10.5194/cpd-9-297-2013.
Testo completoAbstract (sommario):
Abstract. Most state-of-the-art climate models include a coarsely resolved oceanic component, which has difficulties in capturing detailed dynamics, and therefore eddy-permitting/eddy-resolving simulations have been developed to reproduce the observed World Ocean. In this study, an eddy-permitting numerical experiment is conducted to simulate the global ocean state for a period of the Last Glacial Maximum (LGM, ~ 26 500 to 19 000 yr ago) and to investigate the improvements due to taking into account these higher spatial scales. The ocean general circulation model is forced by a 49-yr sample of LGM atmospheric fields constructed from a quasi-equilibrated climate-model simulation. The initial state and the bottom boundary condition conform to the Paleoclimate Modelling Intercomparison Project (PMIP) recommendations. Before evaluating the model efficiency in representing the paleo-proxy reconstruction of the surface state, the LGM experiment is in this first part of the investigation, compared with a present-day eddy-permitting hindcast simulation as well as with the available PMIP results. It is shown that the LGM eddy-permitting simulation is consistent with the quasi-equilibrated climate-model simulation, but large discrepancies are found with the PMIP model analyses, probably due to the different equilibration states. The strongest meridional gradients of the sea-surface temperature are located near 40° N and S, this due to particularly large North-Atlantic and Southern-Ocean sea-ice covers. These also modify the locations of the convection sites (where deep-water forms) and most of the LGM Conveyor Belt circulation consequently takes place in a thinner layer than today. Despite some discrepancies with other LGM simulations, a glacial state is captured and the eddy-permitting simulation undertaken here yielded a useful set of data for comparisons with paleo-proxy reconstructions.
29
Simmons, G. L., e P. E. Pope. "Influence of soil water potential and mycorrhizal colonization on root growth of yellow-poplar and sweet gum seedlings grown in compacted soil". Canadian Journal of Forest Research 18, n. 11 (1 novembre 1988): 1392–96. http://dx.doi.org/10.1139/x88-217.
Testo completoAbstract (sommario):
A greenhouse study was conducted to determine the influence of soil water potential and endomycorrhizal fungi on root growth of yellow-poplar (Liriodendrontulipifera L.) and sweet gum (Liquidambarstyraciflua L.) seedlings grown at three soil bulk densities. Silt loam soil was compacted in PVC pots to bulk densities of 1.25 (low), 1.40 (medium), or 1.55 (high) Mg • m−3, and equilibrated at −10 kPa soil water potential. Newly germinated seedlings were transplanted into the pots, inoculated with fungal chlamydospores of Glomusmacrocarpum or Glomusfasciculaturn, or distilled water (control), and grown for 3 months at −10 or −300 kPa soil water potential. Total porosity, air-filled porosity, water content, and mechanical resistance of the soil were determined for samples compacted to the same bulk densities and equilibrated at the same soil water potentials as were used in the greenhouse study. Root growth was reduced by the high mechanical resistance caused by bulk densities of 1.40 and 1.55 Mg • m−3 at −300 kPa water potential. At both water potentials, total length of lateral roots and fibrosity of the root system of both tree species decreased significantly when bulk density increased from 1.40 to 1.55 Mg • m−3. Air-filled porosity less than 0.12 m3 • m−3 limited root growth when water potential was −10 kPa, and mechanical resistance greater than 3438 kPa restricted growth at −300 kPa. At −10 kPa, root length and fibrosity were greatest for inoculated sweet gum seedlings at each bulk density. At −300 kPa, sweet gum seedlings inoculated with G. fasciculatum had the greatest root length and fibrosity at the low and medium bulk densities. Mycorrhizal effects on root length of yellow-poplar were variable, and fibrosity was not significantly affected by mycorrhizal treatment.
30
Jay, Jenny Ayla, Karen J. Murray, Cynthia C. Gilmour, Robert P. Mason, François M. M. Morel, A. Lynn Roberts e Harold F. Hemond. "Mercury Methylation by Desulfovibrio desulfuricans ND132 in the Presence of Polysulfides". Applied and Environmental Microbiology 68, n. 11 (novembre 2002): 5741–45. http://dx.doi.org/10.1128/aem.68.11.5741-5745.2002.
Testo completoAbstract (sommario):
ABSTRACT The extracellular speciation of mercury may control bacterial uptake and methylation. Mercury-polysulfide complexes have recently been shown to be prevalent in sulfidic waters containing zero-valent sulfur. Despite substantial increases in total dissolved mercury concentration, methylation rates in cultures of Desulfovibrio desulfuricans ND132 equilibrated with cinnabar did not increase in the presence of polysulfides, as expected due to the large size and charged nature of most of the complexes. In natural waters not at saturation with cinnabar, mercury-polysulfide complexes would be expected to shift the speciation of mercury from HgS0 (aq) toward charged complexes, thereby decreasing methylation rates.
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Post, R. L., e I. Klodos. "Interpretation of extraordinary kinetics of Na(+)-K(+)-ATPase by a phase change". American Journal of Physiology-Cell Physiology 271, n. 5 (1 novembre 1996): C1415—C1423. http://dx.doi.org/10.1152/ajpcell.1996.271.5.c1415.
Testo completoAbstract (sommario):
We interpret at a molecular level an extraordinary response in the transient kinetics of the phosphointermediate of Na(+)-K(+)-ATPase (I. Klodos, R. L. Post, and B. Forbush III. J. Biol. Chem. 269: 1734-1743, 1994). The phosphointermediate comprises two principal states. The partition between these states varies with salt concentration. A jump in salt concentration changes the partition of some of the molecules more rapidly than they interconvert in a steady state at constant salt concentration. We propose that interconversion is limited by free volume in the lipid of the surrounding membrane. This lipid is partitioned into phases that vary with salt concentration. Free volume is larger at the interface between these phases than within the phases themselves. Na(+)-K(+)-ATPase molecules are distributed at random in the membrane. When the phase boundary moves in response to a jump in salt concentration, it crosses some Na+ -K+ -ATPase molecules, which transiently experience an increase in free volume of the surrounding lipid. Thus their phosphointermediate states equilibrate more rapidly than at a constant salt concentration. Functional and structural heterogeneity of Na(+)-K(+)-ATPase molecules is discussed.
32
Behnke, R. D., R. K. Wong, S. M. Huse, S. J. Reshkin e G. A. Ahearn. "Proline transport by brush-border membrane vesicles of lobster antennal glands". American Journal of Physiology-Renal Physiology 258, n. 2 (1 febbraio 1990): F311—F320. http://dx.doi.org/10.1152/ajprenal.1990.258.2.f311.
Testo completoAbstract (sommario):
Purified brush-border membrane vesicles (BBMV) of lobster antennal gland labyrinth and bladder were separately formed by a magnesium precipitation technique. L-[3H]proline uptake was stimulated by a transmembrane NaCl gradient [outside (o) greater than inside (i)] to a greater extent in BBMV from labyrinth than those from the bladder. Detailed study of the labyrinth proline-transport processes revealed a specific dependence on NaCl, with negligible stimulatory effects by NaSCN, Na-gluconate, or KCl. A transmembrane proton gradient (o greater than i) was without stimulatory effect on proline transport. A transmembrane potential difference alone, in the presence of equilibrated NaCl and L-[3H]proline, led to net influx of the labeled amino acid, suggesting that the uptake process was electrogenic and capable of bringing about the net transfer of positive charge to the vesicle interior. Although a transmembrane Na gradient alone, in the presence of equilibrated Cl and L-[3H]proline, was able to bring about the net influx of the amino acid, a transmembrane Cl gradient alone under Na- and L-[3H]proline-equilibrated conditions was not, suggesting that only the Na gradient could energize the carrier process through cotransport, while the anion served an essential activating role. Proline influx by these vesicles occurred by the combination of at least one saturable Michaelis-Menten carrier system (apparent Kt = 0.37 mM; apparent JM = 1.19 nmol.mg protein-1.10 s-1) and apparent diffusion (P = 0.33 nmol.mg protein-1.10 s-1.mM-1). Static head analysis of the transport process suggested a cotransport stoichiometry of 2 Na:1 proline with essential activation by Cl ion.
33
Zhong, Qin, Tao Luo, Zhengjuan Yan, Lin Yang, Zhiye Zhang e Xinlong Wang. "Purification of Wet-Process Phosphoric Acid via Donnan Dialysis with a Perfluorinated Sulfonic Acid Cation-Exchange Membrane". Membranes 11, n. 4 (20 aprile 2021): 298. http://dx.doi.org/10.3390/membranes11040298.
Testo completoAbstract (sommario):
This work reports the application of an electromembrane process, Donnan dialysis (DD), for the purification of so-called wet-process phosphoric acid (WPA). Nitric acid is used as the stripping solution to remove metallic cations (mostly Fe3+, Al3+, and Mg2+) that are harmful to the further processing of WPA. The paper first presents a set of experimental data on the measurements of the metallic cation fluxes through a perfluorinated sulfonic acid cation-exchange membrane. Not only WPA, but also synthetic phosphoric acid solutions with mixed metallic cations (MPA) and with a single metallic cation (SPA) were studied. This confrontation confirms (1) that the order of metallic cations fluxes is Mg2+ > Al3+ > Fe3+; (2) that, compared with MPA, the purification effect of WPA causes only negligible change; (3) that, by comparing the DD processes with SPA and MPA solutions, the reason for the low transmembrane fluxes of Fe3+ and Al3+ could be explained by the large ionic charge and large hydrated ion radius. Furthermore, by analyzing the ion composition of membranes equilibrated in SPA solutions, we conclude that the forms of cations in the membrane are most likely Fe3+, Al3+, and Mg2+.
34
Hoertz, Paul G., Aaron Staniszewski, Andras Marton, Gerard T. Higgins, Christopher D. Incarvito, Arnold L. Rheingold e Gerald J. Meyer. "Toward Exceeding the Shockley−Queisser Limit: Photoinduced Interfacial Charge Transfer Processes that Store Energy in Excess of the Equilibrated Excited State". Journal of the American Chemical Society 128, n. 25 (giugno 2006): 8234–45. http://dx.doi.org/10.1021/ja060470e.
Testo completo
35
Vrkoč, F., M. Vach, V. Veleta e J. Košner. "Influence of different organic mineral fertilization on the yield structure and on changes of soil properties". Plant, Soil and Environment 48, No. 5 (11 dicembre 2011): 212–16. http://dx.doi.org/10.17221/4228-pse.
Testo completoAbstract (sommario):
The monitoring was carried on in the years 1996–2000 in the international IOSDV (Internationale Ökologische Stickstoff Dauer Versuche) field trial running since 1983 in Lukavec, Pelhřimov district. In the given locality, there are low fertility sandy-loamy cambisoils, long-term average annual rainfall 653 mm, average annual temperature 7°C, altitude 620 m. In the field trials there were introduced different organic fertilizations and graduate N-doses. According to the complex diffusion analysis, statistically significant for the yields of winter wheat after potatoes was the impact of N fertilization, years, and double interactions, with the exception of different organic fertilization. The N doses up to 120 kg.ha<sup>–1</sup> after potatoes proved to be optimal from the viewpoint of winter wheat yields and quality. The situation was similar for winter barley. The results of diffusion analysis for individual years were analogical also in straw yields of both cereals. The highest N dose to potatoes (200 kg.ha<sup>–1</sup>) resulted in the highest tuber yields, but the starch content was significantly lower. Graduated N doses increased in cereals the numbers of ears per m2, but the mass of 1000 grains mostly decreased. In addition, N content in grain and straw increased with N doses, while pH annually decreased by 0.1 to 0.4. On plots without organic fertilization the N-balance was equilibrated with the annual application of 120 kg N.ha<sup>–1</sup> with straw embedding after cereals at 90 kg N.ha<sup>–1</sup> and on plots with stall dung to potatoes already at 70 kg N.ha<sup>–1</sup>. On plots without N fertilization, the balance was passive also in P and K on plots without organic fertilization. A balance surplus was obtained already with the annual application of 15 kg P.ha–1 and 83 kg K.ha<sup>–1</sup> and organic fertilization. With the annual fertilization with 22 kg P.ha<sup>–1</sup> and 83 kg K.ha<sup>–1</sup> and stall dung (30 t.ha<sup>–1</sup>) once every three years the P and K content increased annually by 1 to 3 mg.kg<sup>–1</sup> of soil. Maximum levels of crop growing profitability were obtained with those doses of fertilizers with which also an equilibrated balance of nutrients was obtained.
36
Hayes, Sally, Tomas White, Craig Boote, Christina S. Kamma-Lorger, James Bell, Thomas Sorenson, Nick Terrill, Olga Shebanova e Keith M. Meek. "The structural response of the cornea to changes in stromal hydration". Journal of The Royal Society Interface 14, n. 131 (giugno 2017): 20170062. http://dx.doi.org/10.1098/rsif.2017.0062.
Testo completoAbstract (sommario):
The primary aim of this study was to quantify the relationship between corneal structure and hydration in humans and pigs. X-ray scattering data were collected from human and porcine corneas equilibrated with polyethylene glycol (PEG) to varying levels of hydration, to obtain measurements of collagen fibril diameter, interfibrillar spacing (IFS) and intermolecular spacing. Both species showed a strong positive linear correlation between hydration and IFS 2 and a nonlinear, bi-phasic relationship between hydration and fibril diameter, whereby fibril diameter increased up to approximately physiological hydration, H = 3.0, with little change thereafter. Above H = 3.0, porcine corneas exhibited a larger fibril diameter than human corneas ( p < 0.001). Intermolecular spacing also varied with hydration in a bi-phasic manner but reached a maximum value at a lower hydration ( H = 1.5) than fibril diameter. Human corneas displayed a higher intermolecular spacing than porcine corneas at all hydrations ( p < 0.0001). Human and porcine corneas required a similar PEG concentration to reach physiological hydration, suggesting that the total fixed charge that gives rise to the swelling pressure is the same. The difference in their structural responses to hydration can be explained by variations in molecular cross-linking and intra/interfibrillar water partitioning.
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Kadam, Rahul S., e Kishor P. Gadkaree. "Thermodynamics of Lithium Intercalation in Randomly Oriented High Graphene Carbon". International Journal of Electrochemistry 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/5391794.
Testo completoAbstract (sommario):
This paper covers details of systematic investigation of the thermodynamics (entropy and enthalpy) of intercalation associated with lithium ion in a structurally novel carbon, called Randomly Oriented High Graphene (ROHG) carbon and graphite. Equilibrated OCV (Open Circuit Voltage) versus temperature relationship is investigated to determine the thermodynamic changes with the lithium intercalation. ROHG carbon shows entropy of 9.36 J·mol−1·K−1 and shows no dependency on the inserted lithium concentration. Graphite shows initial entropy of 84.27 J·mol−1·K−1 and shows a strong dependence on lithium concentration. ROHG carbon (from −90.85 kJ mol−1 to −2.88 kJ mol−1) shows gradual change in the slope of enthalpy versus lithium ion concentration plot compared to graphite (−48.98 kJ mol−1 to 1.84 kJ mol−1). The study clearly shows that a lower amount of energy is required for the lithium ion intercalation into the ROHG structure compared to graphite structure. Randomly oriented graphene platelet cluster structure of ROHG carbon makes it easier for the intercalation or deintercalation of lithium ion. The ease of intercalation and the small cluster structure of ROHG as opposed to the long linear platelet structure of graphite lead to higher rates of the charge-discharge process for ROHG, when used as an electrode material in electrochemical applications.
38
Lang, M. A. "Correlation between osmoregulation and cell volume regulation". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 252, n. 4 (1 aprile 1987): R768—R773. http://dx.doi.org/10.1152/ajpregu.1987.252.4.r768.
Testo completoAbstract (sommario):
The euryhaline crab, Callinectes sapidus, behaves both as an osmoregulator when equilibrated in salines in the range of 800 mosM and below and an osmoconformer when equilibrated in salines above 800 mosM. There exists a close correlation between osmoregulation seen in the whole animal in vivo and cell volume regulation studied in vitro. Hyperregulation of the hemolymph osmotic pressure and cell volume regulation both occurred in salines at approximately 800 mosM and below. During long-term equilibration of the crabs to a wide range of saline environments, the total concentration of hemolymph amino acids plus taurine remained below 3 mM. During the first 6 h after an acute osmotic stress to the whole animal, the hemolymph osmotic pressure and Na activity gradually decreased, whereas the free amino acids remained below 3 mM. As the hemolymph osmotic pressure decreased below approximately 850 mosM, the amino acid level began to increase to 17-25 mM. This change was primarily due to increases in glycine, proline, taurine, and alanine. The likely source of the increase in hemolymph free amino acids in vivo is the free amino acid loss from muscle cells observed during cell volume regulation in vitro.
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Exbrayat, J. F., A. J. Pitman, Q. Zhang, G. Abramowitz e Y. P. Wang. "Examining soil carbon uncertainty in a global model: response of microbial decomposition to temperature, moisture and nutrient limitation". Biogeosciences Discussions 10, n. 6 (24 giugno 2013): 10229–69. http://dx.doi.org/10.5194/bgd-10-10229-2013.
Testo completoAbstract (sommario):
Abstract. Reliable projections of future climate require land–atmosphere carbon (C) fluxes to be represented realistically in Earth System Models. There are several sources of uncertainty in how carbon is parameterized in these models. First, while interactions between the C, nitrogen (N) and phosphorus (P) cycles have been implemented in some models, these lead to diverse changes in land–atmosphere fluxes. Second, while the parameterization of soil organic matter decomposition is similar between models, formulations of the control of the soil physical state on microbial activity vary widely. We address these sources uncertainty by implementing three soil moisture (SMRF) and three soil temperature (STRF) respiration functions in an Earth System Model that can be run with three degrees of biogeochemical nutrient limitation (C-only, C and N, and C and N and P). All 27 possible combinations of a SMRF with a STRF and a biogeochemical mode are equilibrated before transient historical (1850–2005) simulations are performed. As expected, implementing N and P limitation reduces the land carbon sink, transforming some regions from net sinks to net sources over the historical period (1850–2005). Differences in the soil C balance implied by the various SMRFs and STRFs also change the sign of some regional sinks. Further, although the absolute uncertainty in global carbon uptake is reduced, the uncertainty due to the SMRFs and STRFs grows relative to the inter-annual variability in net uptake when N and P limitations are added. We also demonstrate that the equilibrated soil C also depend on the shape of the SMRF and STRF. Equilibration using different STRFs and SMRFs and nutrient limitation generates a six-fold range of global soil C that largely mirrors the range in available (17) CMIP5 models. Simulating the historical change in soil carbon therefore critically depends on the choice of STRF, SMRF and nutrient limitation, as it controls the equilibrated state to which transient conditions are applied. This direct effect of the representation of microbial decomposition in Earth System Models adds to recent concerns on the adequacy of these simple representations of very complex soil carbon processes.
40
KIM, Y. H., H. H. HSIEH, Z. WU e P. H. HOR. "FAR-INFRARED MEASUREMENTS OF OXYGEN-DOPED POLYCRYSTALLINE La2CuO4.0315 SUPERCONDUCTOR UNDER SLOW-COOLED AND FAST-COOLED CONDITIONS". Modern Physics Letters B 25, n. 05 (20 febbraio 2011): 315–24. http://dx.doi.org/10.1142/s0217984911025687.
Testo completoAbstract (sommario):
We have studied the far-infrared (far-IR) charge dynamics of an equilibrated pure oxygen doped La 2 CuO 4.0315 under slow-cooled and fast-cooled conditions. The superconducting transition temperature (Tc) for the slow-cooled and that for the fast-cooled processes were respectively found to be close to the two intrinsic Tc. One at 30 K and the other at 15 K. Direct comparison with our previous results and other far-IR and Raman studies on single crystalline La 2-x Sr x CuO 4, we conclude that the topology of the pristine electronic phases that are responsible for the two intrinsic Tc is holes arranged into two-dimensional (2D) square lattices.
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Möbus, G., T. Gemming, W. Nüchter, M. Exner, P. Gumbsch, A. Weickenmeier, M. Wilson e M. Rühle. "Are Common Atom Form Factors in HREM-Simulations Accurate Enough for Quantitative Image Matching?" Microscopy and Microanalysis 3, S2 (agosto 1997): 1159–60. http://dx.doi.org/10.1017/s143192760001268x.
Testo completoAbstract (sommario):
1.Introduction:If digital image matching between an experimental HREM-image and the simulated image fails, one of the suggested reasons is the “inaccuracy of the atomic form factors“ describing the electron scattering in common simulation packages using the free and neutral atom approximation from Hartree-Fock calculations [1]. In detail, three contributions within the usual form factor calculations are mainly missing: (i) the redistribution of charge in ionic crystals, (ii) the accumulation of charge away from atom sites in covalent crystals, (iii) the inclusion of thermal diffuse scattering (TDS) as well as the correlated vibration of atoms beyond the Einstein-approximation within the Debye-Waller factor (DWF) theory. Each of the three effects have been checked separately:2.Simulations of TDS by Coupling of Molecular Dynamics Time Series to HREM- Multislice Calculations:70 snap shots of a series of structures of NiAl (4.9 × 5.1 × l0nm) are stored from an equilibrated molecular dynamics simulation with vibration amplitudes corresponding to room temperature.
42
Temin, Peter. "The Labor Market of the Early Roman Empire". Journal of Interdisciplinary History 34, n. 4 (aprile 2004): 513–38. http://dx.doi.org/10.1162/002219504773512525.
Testo completoAbstract (sommario):
The available evidence on wages and labor contracts supports the existence of a functioning labor market in the early Roman empire, in which workers could change jobs in response to market-driven rewards. Slaves were included in the general labor market because Roman slavery, unlike that in the United States and in Brazil, permitted frequent manumission to citizen status. Slaves' ability to improve their status provided them with incentives to cooperate with their owners and act like free laborers. As a result, the supply and demand for labor were roughly equilibrated by wages and other payments to most workers, both slave and free.
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Fernández Barba, Ramón. "Scale and scale change in the Early Middle Ages: Exploring landscape, local Society and the world beyond". Arqueología y Territorio Medieval 18 (13 dicembre 2011): 167–69. http://dx.doi.org/10.17561/aytm.v18i0.1482.
Testo completoAbstract (sommario):
La editorial Brepols Publishers publica este volumen, dentro de su colección dedicada al mundo rural medieval (The Medieval Countryside), que tiene como objeto el uso de la escala y el cambio de escala como herramientas metodológicas e interpretativas de los procesos que operan en las sociedades altomedievales, especialmente en las transformaciones territoriales. Los once autores del volumen forman parte de un proyecto de investigación denominado “Los fundamentos del Espacio Europeo: Comunidad, Territorio y Sistemas Políticos en la Europa altomedieval” cuyo principales resultados se recogen en esta obra. Los investigadores participantes provienen de diferentes universidades nacionales e internacionales y son especialistas en las temáticas que abordan, con lo que podemos obtener una visión plural y compleja de las cuestiones de fondo tratadas en el libro. La edición es muy cuidada, los textos son, en general, claros, de lectura agradable y los acompaña un aparato grafico equilibrado, coherente y de gran utilidad.
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AUDITORE, L., R. BARNÁ, D. DE PASQUALE, A. ITALIANO, A. TRIFIRÓ, M. TRIMARCHI, V. RAUCH et al. "A SEMI-CLASSICAL ANALYSIS OF THE PROTON SEQUENTIAL EMISSION IN 16O+58Ni DEEP INELASTIC COLLISIONS". International Journal of Modern Physics E 14, n. 02 (marzo 2005): 239–54. http://dx.doi.org/10.1142/s021830130500293x.
Testo completoAbstract (sommario):
We study the 16 O +58 Ni deep inelastic reaction by using coincident charged techniques. Inclusive as well as exclusive data of the C , N , and O fully-damped fragments and their associated light charged particles ( p , d , t , and α-particles) have been collected at the IReS Strasbourg VIVITRON Tandem facility. The velocity distributions of the emitted protons and the associated multiplicity polar plots are analyzed by means of a model which describes simultaneously the nonequilibrium and the evaporative (equilibrated) components of a deep inelastic reaction mechanism. Estimates on polarization phenomena as well as the associated "decay times" of the reaction have been obtained. The hypothesis of a new "fan effect" is proposed for the proton sequential emission in the deep inelastic scattering of 16 O +58 Ni at 8.25 MeV/nucleon.
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Hecksher, Tina, Niels Boye Olsen e Jeppe C. Dyre. "Fast contribution to the activation energy of a glass-forming liquid". Proceedings of the National Academy of Sciences 116, n. 34 (7 agosto 2019): 16736–41. http://dx.doi.org/10.1073/pnas.1904809116.
Testo completoAbstract (sommario):
This paper presents physical-aging data for the silicone oil tetramethyl-tetraphenyl trisiloxane. The density and the high-frequency plateau shear modulus G∞ were monitored following temperature jumps starting from fully equilibrated conditions. Both quantities exhibit a fast change immediately after a temperature jump. Adopting the material-time formalism of Narayanaswamy, we determine from the dielectric loss at 0.178 Hz the time evolution of the aging-rate activation energy. The relative magnitude of the fast change of the activation energy differs from that of the density, but is identical to that of G∞. In fact, the activation energy is proportional to G∞ throughout the aging process, with minor deviations at the shortest times. This shows that for the silicone oil in question the dynamics are determined by G∞ in—as well as out of—equilibrium.
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Nicolis, N. G., G. S. Souliotis e A. Asimakopoulou. "Spallation of 56Fe by 1.0 GeV Protons". HNPS Proceedings 26 (1 aprile 2019): 25. http://dx.doi.org/10.12681/hnps.1791.
Testo completoAbstract (sommario):
Mass, charge and isotopic distributions observed in spallation reactions of 56Fe with 1 GeV protons are analysed in the framework of the intranuclear cascade code ISABEL coupled with the sequential binary decay code MECO. The code MECO provides a description of the equilibrated nuclear decay by the emission of gamma-rays, light-mass particles and clusters as well as intermediate mass fragments emitted in their ground, excited bound and excited unbound states (continuum) according to a generalized Weisskopf formalism. A good overall description of the experimental data is obtained with a global Fermi gas level density parameter and inverse cross sections based on the Christensen and Winther nuclear potential. Multifragmentation decay events are simulated with the code SMM and their influence on the above observables is discussed.
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Kozyra, K. A., J. R. Heldt, G. Gondek, P. Kwiek e J. Heldt. "Influence of DPPC Liposome Concentration on the Fluorescence Properties of PRODAN and LAURDAN". Zeitschrift für Naturforschung A 59, n. 11 (1 novembre 2004): 809–18. http://dx.doi.org/10.1515/zna-2004-1115.
Testo completoAbstract (sommario):
Fluorescence spectral features of PRODAN and LAURDAN in phospholipid vesicles of different phase states were investigated. The results indicate that in the liquid crystalline phase the dominant emission results from the charge transfer (CT) excited state, whereas in the gel state of the membrane the emission from the locally excited (LE) state dominates. The fluorescence time studies point out that there are two radiation modes, one starting from only vibrationally relaxed excited states S1(LE)ν ((S1(CT)ν) and the other from a totally thermally equilibrated state S1(LE)EQ (S1(CT)EQ). In accordance with the obtained decay time dependencies, the fluorescence emission from total nonequilibrated excited states consists of a dominant or minor radiation process in the LE or CT band emission
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Fitzgerald, R. S., S. Howell, M. M. Pike e W. E. Jacobus. "NMR study of rat diaphragm exposed to metabolic and compensated metabolic acidosis". Journal of Applied Physiology 65, n. 5 (1 novembre 1988): 2278–84. http://dx.doi.org/10.1152/jappl.1988.65.5.2278.
Testo completoAbstract (sommario):
When exposed to hypercapnia, several muscles deteriorate with respect to their mechanical performance. Exposure to metabolic acidosis and, perhaps surprisingly, to compensated metabolic acidosis has the same effect on the diaphragm. The mechanisms involved in these effects remain unclear. If the diaphragmatic intracellular pH (pHi) is assumed to decrease with hypercapnia, to remain unchanged during metabolic acidosis, and to increase during compensated metabolic acidosis, it would appear that different mechanisms must be responsible for the depreciation in the diaphragm's mechanical performance. The present experiments using 31P nuclear magnetic resonance (31P-NMR) spectroscopy were undertaken to determine the effect of metabolic acidosis and compensated metabolic acidosis on pHi and on high-energy phosphate metabolites in the resting rat diaphragm. A whole diaphragm was slightly stretched while being stitched onto a fiberglass mesh. The area approximated that at functional residual capacity. It was superfused in the NMR sample tube with a phosphate-free Krebs-Ringer bicarbonate solution [( HCO3-] = 6 meqO equilibrated with either 95% O2-5% CO2 or 98.75% O2-1.25% CO2). Spectra were acquired during 15-min intervals for control (30 min of normal Krebs-Ringer bicarbonate superfusate, equilibrated with 95% O2-5% CO2), for 120 min of exposure to either form of acidosis and for 60 min of recovery with normal superfusate. The pHi decreased rapidly during metabolic acidosis but did not change significantly during compensated metabolic acidosis. In both forms of acidosis, phosphocreatine declined gradually but not significantly, whereas ATP and inorganic phosphate did not change at all. The results suggest that HCO3- passes freely through the diaphragmatic sarcolemma, very much like the cardiac sarcolemma.(ABSTRACT TRUNCATED AT 250 WORDS)
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Sanderson, Benjamin. "Relating climate sensitivity indices to projection uncertainty". Earth System Dynamics 11, n. 3 (4 agosto 2020): 721–35. http://dx.doi.org/10.5194/esd-11-721-2020.
Testo completoAbstract (sommario):
Abstract. Can we summarize uncertainties in global response to greenhouse gas forcing with a single number? Here, we assess the degree to which traditional metrics are related to future warming indices using an ensemble of simple climate models together with results from the Coupled Model Intercomparison Project phases 5 and 6 (CMIP5 and CMIP6). We consider effective climate sensitivity (EffCS), transient climate response (TCR) at CO2 quadrupling (T140) and a proposed simple metric of temperature change 140 years after a quadrupling of carbon dioxide (A140). In a perfectly equilibrated model, future temperatures under RCP8.5 (Representative Concentration Pathway 8.5) are almost perfectly described by T140, whereas in a mitigation scenario such as RCP2.6, both EffCS and T140 are found to be poor predictors of 21st century warming, and future temperatures are better correlated with A140. We show further that T140 and EffCS calculated in full CMIP simulations are subject to errors arising from control model drift and internal variability, with greater relative errors in estimation for T140. As such, if starting from a non-equilibrated state, measured values of effective climate sensitivity can be better correlated with true TCR than measured values of TCR itself. We propose that this could be an explanatory factor in the previously noted surprising result that EffCS is a better predictor than TCR of future transient warming under RCP8.5.
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Wouters, E. F. "Impedance measurement during air and He-O2 breathing before and after salbutamol in normal subjects". Journal of Applied Physiology 69, n. 5 (1 novembre 1990): 1665–69. http://dx.doi.org/10.1152/jappl.1990.69.5.1665.
Testo completoAbstract (sommario):
Total respiratory resistance and reactance from 4 to 52 Hz were determined by the method of forced pseudorandom noise oscillation in 20 normal male subjects before and after inhalation of 0.200 mg salbutamol (albuterol) and before and after the subjects were equilibrated with 80% He-20% O2. During air breathing, there was a statistically significant decrease of resistance values at lower frequencies after inhalation of salbutamol. When the subject was equilibrated with 80% He-20% O2, total respiratory resistance markedly decreased at all frequencies, and a negative frequency dependence of resistance was observed between 8 and 20 Hz. Resistance values further decreased during He-O2 breathing after inhalation of salbutamol. After inhalation of salbutamol, reactance values increased during air and He-O2 breathing. The density-dependent decrease of the real part of impedance can be explained by a decrease of turbulence in the larger airways. The bronchodilating effect of salbutamol was not influenced by a change in the physical properties of the inhaled gas. During He-O2 breathing, reactance values significantly decreased, resulting in an increase of resonant frequency due to a decrease of inductive reactance. It is concluded that an increase in the capacitance of the respiratory system must be supposed to explain the increase in reactance values after inhalation of the beta-adrenergic agonist salbutamol.