CO2 Conductance Research Articles

An Electrical Conductimetric Study of Association Phenomena of 4- Aminoantipyrine (4-AAp) Complexes in Mixtures of Methanol-Water at Different Temperatures

The aim of this work is to measure the electrical conductivity of Co (II) and Ni (II) complexes with 4-amino antipyrine in mixtures of different percentages of methanol and water at different temperatures. The data were analyzed using the Lee-Wheaton equation for unsymmetrical electrolytes, the conductivity parameters: ionic equivalent conductivity λM+2, association constant KA, and the distance parameter R are calculated. The ionic equivalent conductivity λM+2, increases with increasing temperature, which may attributed to the breaking of hydrogen bonds between solvated ion. Association constant KA increase with increasing temperature, which assumed the presences of simple coloumbic interactions between hard sphere ions in continuous medium. The distance parameter R are calculated at the bist fit values of standard deviation σΛ. Thermodynamic parameters from the relation between LnKA and 1T were calculated to examine the nature of interaction. Walden product were calculated which show the variation depending on electrochemical equilibrium between ions and the solvent molecules with the composition of the mixed polar solvents.

Molecular Modeling of Diffusion Coefficient and Ionic Conductivity of CO2 in Aqueous Ionic Solutions

Mass diffusion coefficients of CO(2)/brine mixtures under thermodynamic conditions of deep saline aquifers have been investigated by molecular simulation. The objective of this work is to provide estimates of the diffusion coefficient of CO(2) in salty water to compensate the lack of experimental data on this property. We analyzed the influence of temperature, CO(2) concentration,and salinity on the diffusion coefficient, the rotational diffusion, as well as the electrical conductivity. We observe an increase of the mass diffusion coefficient with the temperature, but no clear dependence is identified with the salinity or with the CO(2) mole fraction, if the system is overall dilute. In this case, we notice an important dispersion on the values of the diffusion coefficient which impairs any conclusive statement about the effect of the gas concentration on the mobility of CO(2) molecules. Rotational relaxation times for water and CO(2) increase by decreasing temperature or increasing the salt concentration. We propose a correlation for the self-diffusion coefficient of CO(2) in terms of the rotational relaxation time which can ultimately be used to estimate the mutual diffusion coefficient of CO(2) in brine. The electrical conductivity of the CO(2)-brine mixtures was also calculated under different thermodynamic conditions. Electrical conductivity tends to increase with the temperature and salt concentration. However, we do not observe any influence of this property with the CO(2) concentration at the studied regimes. Our results give a first evaluation of the variation of the CO(2)-brine mass diffusion coefficient, rotational relaxation times, and electrical conductivity under the thermodynamic conditions typically encountered in deep saline aquifers.

Detection of Interstitial Lung Disease in Systemic Sclerosis through Partitioning of Lung Transfer for Carbon Monoxide

Background: Interstitial lung disease (ILD) is a leading cause of death in systemic sclerosis (SSc). Sensitivities and specificities of the current pulmonary function tests (PFTs) for the detection of ILD in SSc are poor. Objective: To determine whether diffusion capacity of the lungs for carbon monoxide (DLCO) partitioned into membrane conductance for CO (DmCO) and alveolar capillary blood volume (Vcap) could provide more sensitive clues to ILD than current PFTs. Methods: DmCO and Vcap were determined in 35 consecutive SSc patients in whom a cardiac and/or pulmonary vascular abnormality had been rejected according to the recommended screening algorithm. ILD was diagnosed with high-resolution computed tomography. Results: Among 35 patients [6 men; median age (first–third quartile) 61.9 years (49.5–67.7)], 22 had no ILD and 13 did. Total lung capacity (TLC), vital capacity and DLCO [percentage of predicted value (%pred)] were lower in patients with ILD [86 (82–103) vs. 106 (98–112), p = 0.01, 96 (88–112) vs. 114 (104–121), p = 0.04, and 67 (59–81) vs. 80 (71–94), p = 0.02, respectively]. DmCO (%pred) and the ratio of DmCO to Vcap were much lower in patients with ILD [54 (48–72) vs. 83 (66–92), p < 0.001, and 0.22 (0.21–0.27) vs. 0.40 (0.35–0.53), p < 0.0001, respectively]. According to receiver operating characteristic analysis, the DmCO:Vcap ratio displayed higher sensitivity and specificity than TLC, vital capacity and DLCO in identifying ILD in our study group (p < 0.01). Conclusions: These results suggest that the partitioning of DLCO might be of interest for identifying ILD in SSc patients.

The Péclet effect on leaf water enrichment correlates with leaf hydraulic conductance and mesophyll conductance for CO2

Leaf water gets isotopically enriched through transpiration, and diffusion of enriched water through the leaf depends on transpiration flow and the effective path length (L). The aim of this work was to relate L with physiological variables likely to respond to similar processes. We studied the response to drought and vein severing of leaf lamina hydraulic conductance (K(lamina) ), mesophyll conductance for CO(2) (g(m) ) and leaf water isotope enrichment in Vitis vinifera L cv. Grenache. We hypothesized that restrictions in water pathways would reduce K(lamina) and increase L. As a secondary hypothesis, we proposed that, given the common pathways for water and CO(2) involved, a similar response should be found in g(m) . Our results showed that L was strongly related to mesophyll variables, such as K(lamina) or g(m) across experimental drought and vein-cutting treatments, showing stronger relationships than with variables included as input parameters for the models, such as transpiration. Our findings were further supported by a literature survey showing a close link between L and leaf hydraulic conductance (K(leaf) = 31.5 × L(-0.43) , r(2) = 0.60, n = 24). The strong correlation found between L, K(lamina) and g(m) supports the idea that water and CO(2) share an important part of their diffusion pathways through the mesophyll.

Temperature response of mesophyll conductance in cultivated and wild Oryza species with contrasting mesophyll cell wall thickness

A critical component of photosynthetic capacity is the conductance of CO(2) from intercellular airspaces to the sites of CO(2) fixation in the stroma of chloroplasts, termed mesophyll conductance (g(m)). Leaf anatomy has been identified as an important determinant of g(m). There are few studies of the temperature response of g(m) and none has examined the implications of leaf anatomy. Hence, we compared a cultivar of Oryza sativa with two wild Oryza relatives endemic to the hot northern savannah of Australia, namely Oryza meridionalis and Oryza australiensis. All three species had similar leaf anatomical properties, except that the wild relatives had significantly thicker mesophyll cell walls than O. sativa. Thicker mesophyll cell walls in the wild rice species are likely to have contributed to the reduction in g(m) , which was associated with a greater drawdown of CO(2) into chloroplasts (C(i) -C(c) ) compared with O. sativa. Mesophyll conductance increased at higher temperatures, whereas the rate of CO(2) assimilation was relatively stable between 20 and 40 °C. Consequently, C(i) -C(c) decreased for all three species as temperature increased.

Eliashberg analysis of optical spectra reveals a strong coupling of charge carriers to spin fluctuations in doped iron-pnictideBaFe2As2superconductors

The temperature and frequency dependences of the optical conductivity of Co and Ni-doped BaFe2As2 are analyzed and the electron-boson spectral density a2F(w) extracted using Eliashberg's formalism. The characteristic energy of a large peak in the spectrum around 10 meV coincide with the resonance peak in the spin excitation spectra, giving compelling evidence that in iron-based superconductors spin fluctuations strongly couple to the charge carriers and mediate superconductivity. In addition the spectrum is found to evolve with temperature towards a less structured background at higher energies as in the spin susceptibility.

Relationship between stable carbon isotope discrimination and water use efficiency under regulated deficit irrigation of pear-jujube tree

To investigate the relationship between stable carbon isotope discrimination ( Δ) of different organs and water use efficiency (WUE) under different water deficit levels, severe, moderate and low water deficit levels were treated at bud burst to leafing, flowering to fruit set, fruit growth and fruit maturation stages of field grown pear-jujube tree, and leaf stable carbon isotope discrimination ( Δ L) at different growth stages and fruit stable carbon isotope discrimination ( Δ F) at fruit maturation stage were measured. The results indicated that water deficit had significant effect on Δ L at different growth stages and Δ F at fruit maturation stage. As compared with full irrigation, the average Δ L at different growth stages and Δ F at fruit maturation stage were decreased by 1.23% and 2.67% for different water deficit levels, respectively. Δ L and Δ F among different water deficit treatments had significant difference at the same growth stage ( P < 0.05). Under different water deficit conditions, significant relationships between the Δ L and WUE i (photosynthesis rate/transpiration rate, P n/ T r), WUE n (photosynthesis rate/stomatal conductance of CO 2, P n/ g s), WUE y (yield/crop water consumption, Y/ET c) and yield, or between the Δ F and WUE y and yield were found, respectively. There were significantly negative correlations of Δ L with WUE i, WUE n, WUE y and yield ( P < 0.01) at the fruit maturation stage, or Δ L with WUE i and WUE n ( P < 0.01) over whole growth stage, respectively. Δ F was negatively correlated with WUE y, WUE n and yield ( P < 0.05), but positively correlated with ET c ( P < 0.01) over the whole growth stage. Thus Δ L or Δ F can compare WUE n and WUE y, so the stable carbon isotope discrimination method can be applied to evaluate the water use efficiency of pear-jujube tree under the regulated deficit irrigation.

High‐frequency field measurements of diurnal carbon isotope discrimination and internal conductance in a semi‐arid species, Juniperus monosperma

We present field observations of carbon isotope discrimination (Delta) and internal conductance of CO(2) (g(i)) collected using tunable diode laser spectroscopy (TDL). Delta ranged from 12.0 to 27.4 per thousand over diurnal periods with daily means from 16.3 +/- 0.2 per thousand during drought to 19.0 +/- 0.5 per thousand during monsoon conditions. We observed a large range in g(i), with most estimates between 0.04 and 4.0 micromol m(-2) s(-1) Pa(-1). We tested the comprehensive Farquhar, O'Leary and Berry model of Delta (Delta(comp)), a simplified form of Delta(comp) (Delta(simple)) and a recently suggested amendment (Delta(revised)). Sensitivity analyses demonstrated that varying g(i) had a substantial effect on Delta(comp), resulting in mean differences between observed Delta (Delta(obs)) and Delta(comp) ranging from 0.04 to 9.6 per thousand. First-order regressions adequately described the relationship between Delta and the ratio of substomatal to atmospheric CO(2) partial pressure (p(i)/p(a)) on all 3 d, but second-order models better described the relationship in July and August. The three tested models each best predicted Delta(obs) on different days. In June, Delta(simple) outperformed Delta(comp) and Delta(revised), but incorporating g(i) and all non-photosynthetic fractionations improved model predictions in July and August.

Detection of a quantitative trait locus controlling carbon isotope discrimination and its contribution to stomatal conductance in japonica rice

Increasing leaf photosynthesis offers a possible way to improve yield potential in rice (Oryza sativa L.). Carbon isotope discrimination (Delta(13)C) has potential as an indirect selection criterion. In this study, we searched for quantitative trait loci (QTLs) controlling Delta(13)C, and assessed their association with leaf photosynthesis. Substitution mapping by using chromosome segment substitution lines (CSSLs), that carry segments from the indica cultivar Kasalath in the genetic background of the japonica cultivar Koshihikari, identified genomic regions affecting Delta(13)C on chromosomes (Chr.) 2, 3, 6, 7, and 12. One of the CSSLs, SL208, in which most regions on Chr. 3 were substituted with Kasalath segments, showed higher leaf stomatal conductance for CO(2) (g (s)) and Delta(13)C than Koshihikari during the vegetative stage although leaf photosynthetic rate did not differ between them. These results suggest an association between Delta(13)C and g (s). To test this association, we performed a QTL analysis for Delta(13)C at vegetative and heading stages in an F(2) population derived from a cross between SL208 and Koshihikari. The results confirmed a QTL controlling Delta(13)C on the long arm of Chr. 3. By using a near-isogenic line specific to Hd6, we ruled out the possibility that variation in Delta(13)C was generated through the pleiotropic effect of heading date.

δ 13C and δD compositions of n-alkanes from modern angiosperms and conifers: An experimental set up in central Washington State, USA

This study investigates stable carbon and hydrogen isotope compositions of leaf wax n-alkanes from 3 angiosperm and 2 conifer species from a semi-desert natural environment. The δ 13C and δD n-C 27 alkane data show a clear distinction between Populus tremuloides/Syringa vulgaris (−31.9 to −32.7‰ and −168 to −186‰, respectively) and Pinus sylvestris/Picea pungens (−28.8 to −30.6‰ and −190 to −212‰) throughout the 2005 growing season. Like the other angiosperm species, Betula pendula was D-enriched (−162 to −178‰) relative to the conifer species. However, its δ 13C values were more similar to those of Pinus sylvestris and Picea pungens in May, but had a ∼4‰ positive shift later in the season. We suggest that the observed isotopic variations derive mainly from lower stomatal conductance for CO 2 and H 2O vapor in conifers relative to angiosperms. Betula pendula experienced severe environmental stress that affected its carbon metabolism for most of the season. Our results suggest that shifts in δD and δ 13C values of sedimentary leaf waxes may result not only from shifts in the paleoclimatic variables but also from temporal shifts in the distribution of angiosperms and conifers as well as from changes in the isotopic signatures of higher plants undergoing metabolic changes.

European reference equations for CO and NO lung transfer

The aim of the present study was to calculate reference equations for carbon monoxide and nitric oxide transfer, measured in two distinct populations. The transfer factor of the lung for nitric oxide (T(L,NO)) and carbon monoxide (T(L,CO)) were measured in 303 people aged 18-94 yrs. Measurements were similarly made in two distant cities, using the single-breath technique. Capillary lung volume (V(c)) and membrane conductance, the diffusing capacity of the membrane (D(m)), for carbon monoxide (D(m,CO)) were derived. The transfer of both gases appeared to depend upon age, height, sex and localisation. The rate of decrease in both transfers increased after the age of 59 yrs. T(L,NO)/alveolar volume (V(A)) and T(L,CO)/V(A) were only age-dependent. The mean T(L,NO)/T(L,CO) was 4.75 and the mean D(m)/V(c) was 6.17 min(-1) x kPa(-1); these parameters were independent of any covariate. V(c) and D(m,CO) calculations depend upon the choice of coefficients included in the Roughton-Forster equation. Values of 1.97 for D(m,NO)/D(m,CO) ratio and 12.86 min x kPa(-1) for 1/red cell CO conductance are recommended. The scatter of transfer reference values in the literature, including the current study, is wide. The present results suggest that differences might be due to the populations themselves and not the methods alone.

Drastic effects of fast neutrons and γ-irradiation on the DC conductivity of Co-, Ni-, Mn- and Ag-gelatin doped films

Abstract The effect of fast neutron fluencies and γ-rays on the DC conductivity, ln( σ ), for pure gelatin and that doped with 5, 10, and 15 wt% of CoCl 2 · 6H 2 O, and 5 wt% of NiCl 2 · 6H 2 O, MnCl 2 · 2H 2 O and AgNO 3 has been respectively investigated at different temperatures. Fast neutron fluencies and γ-rays doses are set from 7.60 × 10 5 to 0.50 × 10 9 N/cm 2 , and 0.25 up to 1.50 Gy, respectively. The calculated values of activation energies ( E a ) are found to be dependent on the radiation doses. The conductivity of gelatin samples shows an interesting behavior, which depends on the dopant Co concentration and the exposure dose. DC conductivity of the investigated samples reveals that the ionic conduction has been established at higher temperatures and fast neutron fluencies and γ-rays doses, while the electronic one plays an important role at lower temperatures. This has been related to the crosslinking formations as a result of the interaction between the exposure dose and gelatin sample. The attained results suggest strongly the applicability of these materials in dosimetry.

Electrical Conductivity of Co—Zr Substituted Hexagonal Barium Ferrites

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Effect of Root Feeding by &lt;I&gt;Diaprepes abbreviatus&lt;/I&gt; (Coleoptera: Curculionidae) Larvae on Leaf Gas Exchange and Growth of Three Ornamental Tree Species

Diaprepes abbreviatus L. (Coleoptera: Curculionidae), feeds on a variety of ornamental plants grown in southern Florida. Studies were conducted to evaluate the effects of root feeding by D. abbreviatus larvae on leaf gas exchange and growth of three ornamental tree species commonly grown in southern Florida that are known hosts of this weevil: green buttonwood, Conocarpus erectus L.; live oak, Quercus virginiana Mill.; and pygmy date palm, Phoenix roebelenii O'Brien. These hosts were grown in containers and infested with weevil larvae. Net CO2 assimilation, transpiration, and stomatal conductance of CO, were measured monthly. Leaf, stem, and root fresh and dry weights of each species also were determined. In one of two tests, larval root feeding significantly reduced net CO2 assimilation, transpiration, and stomatal conductance of CO2 of infested green buttonwood trees. Leaf gas exchange of live oak was not affected by larval infestation. In addition to testing cumulative effects of multiple infestations of larvae, the effects of incremental infestations on leaf gas exchange and fresh and dry weights also were tested for each plant species. Net CO2 assimilation, transpiration, stomatal conductance of CO2, and dry weights of green buttonwood were reduced as a result of larval root feeding, whereas there was no effect of incremental larval infestations on leaf gas exchange of live oak or pygmy date palm within the experimental time frame. There was no effect of incremental larval infestations on dry weights of live oak, but leaf, stem, and dry root weight of pygmy date palm were lower for infested plants than for noninfested plants. Overall, green buttonwood was more susceptible to larval root feeding damage than either live oak or pygmy date palm.

High-resolution measurements of middle ear gas volume changes in the rabbit enables estimation of its mucosal CO(2) conductance.

Transmucosal CO(2) exchange in the middle ear (ME) of the New Zealand White rabbit (Oryctolagus cuniculus) was studied using an accurate novel detecting and recording system for measuring gas volume changes at constant pressure, based on a principle that was previously used by Kania et al. (Acta Otolaryngol 124:408-410, 2004). After the ME cavity was washed with ambient air, the initial diffusion rate of CO(2) (V(.-)(i)CO(2)) from the blood perfusing the ME mucosa was calculated from gas volume change measurements. In nine cases, the (V(.-)(i)CO(2))calculated after normalization due to shifts in baseline was 314+/-112 microL x h(-1) (mean +/- SD). In two cases where normalization was not needed, (V(.-)(i)CO(2)) was 409 microL x h(-1) (276 and 543 microL x h(-1)). Normalization of (V(.-)(i)CO(2)) data was also made in five additional cases where secretion of fluids from the lining of the ear canal was observed. In these cases (V(.-)(i)CO(2)) was 245 +/- 142 microL x h(-1). No differences were found between results obtained in the three groups. Thus, an overall mean value of (V(.-)(i)CO(2)) of 305 +/- 131 microL x h(-1) (n = 16) was calculated. An effective coefficient of conductance of CO(2) (G(CO(2))) between the mucosal circulation and the ME gas cavity of the New Zealand White rabbit was estimated to be approximately 0.05 microL (h x Pa)(-1) and compared to the G(CO(2)) estimated for humans in a different study.

Electrical conductivity of Co–Zr substituted hexagonal barium ferrites

The electrical conductivity of Co–Zr substituted barium hexagonal ferrites of different compositions has been investigated as a function of composition and temperature. The values of log( σT) plotted versus 10 3/ T increase with increasing temperature. An attempt is made to explain the conduction mechanism in Ba–Co–Zr ferrites.

Interspecific difference in the photosynthesis?nitrogen relationship: patterns, physiological causes, and ecological importance

The photosynthesis-nitrogen relationship is significantly different among species. Photosynthetic capacity per unit leaf nitrogen, termed as photosynthetic nitrogen-use efficiency (PNUE), has been considered an important leaf trait to characterise species in relation to their leaf economics, physiology, and strategy. In this review, I discuss (1) relations between PNUE and species ecology, (2) physiological causes and (3) ecological implications of the interspecific difference in PNUE. Species with a high PNUE tend to have high growth rates and occur in disturbed or high productivity habitats, while those with a low PNUE occur in stressful or low productivity habitats. PNUE is an important leaf trait that correlates with other leaf traits, such as leaf mass per area (LMA) and leaf life span, irrespective of life form, phylogeny, and biomes. Various factors are involved in the interspecific difference. In particular, nitrogen allocation within leaves and the mesophyll conductance for CO(2) diffusion are important. To produce tough leaves, plants need to allocate more biomass and nitrogen to make thick cell walls, leading to a reduction in the mesophyll conductance and in nitrogen allocation to the photosynthetic apparatus. Allocation of biomass and nitrogen to cell walls may cause the negative relationship between PNUE and LMA. Since plants cannot maximise both PNUE and leaf toughness, there is a trade-off between photosynthesis and persistence, which enables the existence of species with various leaf characteristics on the earth.

PO2 dependence of valence number of Co in LaGaO 3 and its influence on partial electronic and oxide ionic conductivity

Partial electronic and oxide ionic conductivity in Co doped LaGaO 3 was investigated with a polarization method and it was seen that the partial electronic conductivity became significant with increasing temperature. P O 2 dependences of the partial electron and hole conductivities at 1173 K are almost proportional to P O 2 −1/4 and P O 2 1/4, respectively, in accordance to Wagner's theory. On the other hand, P O 2 dependences of electron and hole conductivities deviate from those of Wagner's theory and became much smaller as temperature decrease. The small P O 2 dependence of the partial electronic conductivity could be explained by extrinsic electrons or holes originating from oxidation or reduction of cobalt. In order to explain the small P O 2 dependence, average valence numbers of Co were measured by redox titration. It was seen that the P O 2 dependence of the Co valence number is similar to those of partial electron and hole conduction. Consequently, the small P O 2 dependence of partial electronic conduction could be assigned to the small P O 2 dependence of the valence number of Co.

Overexpression of the barley aquaporin HvPIP2;1 increases internal CO(2) conductance and CO(2) assimilation in the leaves of transgenic rice plants.

The internal conductance for CO(2) diffusion (g(i)) and CO(2) assimilation rate were measured and the related anatomical characteristics were investigated in transgenic rice leaves that overexpressed barley aquaporin HvPIP2;1. This study was performed to test the hypothesis that aquaporin facilitates CO(2) diffusion within leaves. The g(i) value was estimated for intact leaves by concurrent measurements of gas exchange and carbon isotope ratio. The leaves of the transgenic rice plants that expressed the highest levels of Aq-anti-HvPIP2;1 showed a 40% increase in g(i) as compared to g(i) in the leaves of wild-type rice plants. The increase in g(i) was accompanied by a 14% increase in CO(2) assimilation rate and a 27% increase in stomatal conductance (g(s)). The transgenic plants that had low levels of Aq-anti-HvPIP2;1 showed decreases in g(i) and CO(2) assimilation rate. In the plants with high levels of Aq-anti-HvPIP2;1, mesophyll cell size decreased and the cell walls of the epidermis and mesophyll cells thickened, indicating that the leaves had become xeromorphic. Although such anatomical changes could partially offset the increase in g(i) by the aquaporin, the increase in aquaporin content overcame such adverse effects.

Use of light and inorganic carbon acquisition by two morphotypes of Zostera noltii Hornem

The affinity for dissolved inorganic carbon (DIC) and the mechanisms to use HCO 3 − as a source of DIC for photosynthesis were investigated in two morphotypes of Zostera noltii Hornem. Both morphotypes were collected at Ria Formosa lagoon (Southern Portugal) at two different levels in the intertidal. Affinity for DIC at saturating photon fluence rate (PFR), estimated as photosynthetic conductance for CO 2 ( g p(CO 2) ), was reduced by 75% in the Z. noltii plants adapted to shade conditions (lower intertidal) in comparison to the sun morphotype (45×10 −6 and 182×10 −6 m s −1, respectively), indicating that the plants acclimated to sun conditions (higher intertidal) had a higher capacity to use HCO 3 − as DIC source for photosynthesis. Since external carbonic anhydrase activity was negligible and a large inhibitory effect was produced by Tris buffer addition, this HCO 3 − use was attributed to the operation of H + ATPases creating low pH zones in periplasmic space. The photosynthetic CO 2-flux supported for this mechanism was calculated to be 53 μmol O 2 m −2 s −1 in sun morphotype, about 80% out of maximum photosynthesis rate. In order to determine the possible photosynthetic energy cost of the HCO 3 − use, the effect of decreasing light on photosynthetic rates and g p(CO 2) was estimated. Photosynthetic conductance decreased in both morphotypes at non-saturating PFR. This dependence of g p(CO 2) on PFR indicated the existence of a positive interactive effect between DIC and PFR which was more pronounced in the shade morphotype since the ascending slope of O 2 evolution vs. PFR curves at limiting PFRs was reduced from 7.2 to 2.3 mmol O 2 mol photon −1 at 4 and 0.5 mol m −3 of DIC, respectively.