Concentrations Of Ionic Species Research Articles

Site characteristics impacting the survival of historic waterlogged wood: A review

Survival of waterlogged wood from hundreds and in rare cases millions of years presents scientists with a unique opportunity to examine wood specimens which, due to select properties of the wood itself and/or the depositional environment, have not been completely degraded. Although degradation patterns of various types of microbial wood decay have been studied in detail, the site parameters of the zone from which the wood was removed has not been systematically characterized and correlated to the specific types and cause of degradation. Studies have been conducted attempting to relate factors such as hydrogen-ion concentration (pH), redox potential (Eh), oxygen (O 2) concentration, and ion species concentrations to specific environments, but there has been no unification of testing methodology. This paper proposes to review the literature concerning site characteristics that impact the biodegradation of historic submerged wood, and discuss the current research on archeological wood removed from waterlogged environments.

Propagation Characteristics of Ion Acoustic Waves in an Ar/SF6Plasma

There has been a great interest in wave phenomena in a negative ion plasma. Usually sulfur hexafluoride (SF6) gas is used to produce a negative ion plasma, because SF6 gas has a large electron attachment cross-section for electron energies less than 1 eV. Furthermore, the negative ion concentration, r, can be controlled by partial pressure of the gas. However, the introduction of SF6 gas produces several ion species in discharge plasmas. In fact, there are many discussions on ion species in discharge plasmas. In the most of the experiment on the ion acoustic wave in a negative ion plasma, only F− or only SF6 was assumed as the negative ion species. 1, 2) On the other hand, in many experimental studies on the ion acoustic soliton in Ar/SF6 plasmas it was assumed that the light components, that is, F− contributes more effectively to the ion acoustic wave, 4) and the results of these experiments were consistent with this assumption. Cooney et al., however, obtained the soliton velocity that shifted gradually from the theoretical value for Ar and F− to that for Ar and SF6 as r increased. 5) Although they mentioned that this was perhaps due to an increase in the relative concentration of SF6 to F − as r increased, there was no evidence for the phenomenon. On the other hand, it was recently observed by the mass spectrometry that the relative concentration of SF6 to F− increases with increasing r in the double plasma (DP) device. Thus, in order to confirm whether the variations in the relative concentrations of ion species affect the propagation characteristics of the ion acoustic wave or not, we detected dominant ion species in an Ar/SF6 plasma with a quadrupole mass spectrometer (QMS) and measured the phase velocity of the ion acoustic wave for different values of r. While much work on the ion acoustic wave in two-positive ion plasmas have been done, 8) the study on the ion acoustic wave in two-negative ion plasmas hardly has been carried out. The purpose of this paper is to observe the dependence of the ion acoustic wave on ion species, especially negative ion species. The experiments were carried out using a multidipole DP device. The diameter and the length of the device

Migration of methane sulphonate in Antarctic firn and ice

We investigate the seasonal relationship of the sulphur‐bearing anions methane sulphonate (MSA−) and non‐sea‐salt sulphate (nssSO42−) in sections of firn and ice cores from the Antarctic Peninsula and Weddell Sea region of Antarctica. In cores from Dolleman Island and Berkner Island, MSA− has clearly migrated from the summer snow layer, where it is initially deposited, to become concentrated in the winter layer. A similar behavior is evident in a core from the Dyer Plateau, though in deeper layers. Cores from Gomez Nunatak and Beethoven Peninsula show little evidence of relocation of MSA−, though migration at greater depth in the ice sheet cannot be ruled out. In contrast, in all these cores, non‐sea‐salt sulphate remains in the summer layer. From comparisons between the ice core characteristics and the migration behavior at these sites, we conclude that the movement of MSA− does not occur via percolation and refreezing of meltwater. Simple concentration‐driven diffusion is also not a factor, as the MSA− peaks are sharp in the winter layer. The data presented indicate that the movement of MSA− in firn is likely to be linked to the concentration of other ionic species in the snowpack and to the snow accumulation rate. A possible mechanism for the migration of MSA− in the snowpack is via an initial diffusion in the liquid or vapor phase, which is halted by trapping in the winter layer when the MSA− forms a salt with a cation.

冷却水系での軟鋼の腐食に対するアクリル酸／カフェ酸アミド系二元共重合体およびその類縁体の効果

To develop a highly efficient polymer inhibitor on corrosion of mild steel in cooling water. poly (acrylate-co-caffeylamide) [P(AA/CAm)n, n=1-7], poly (acrylate-co-caffeic acid) [P(AA/CA)], and poly (acrylate-co-cinnamamide) [P(AA/CiAm)] were synthesized under adsorption control by a polymer carboxyl group and deoxygenation by polyphenol. Inhibition of corrosion and scale deposition were studeid. In a solution with a low ionic species concentration, P(AA/CAm)2 and P(AA/CiAm) showed a high corrosion inhibition over a wide range of additive concentrations due to polymer adsorption on the steel surface. In a solution with a high ionic species concentration, P(AA/CAm)4 and P(AA/CA) had improved corrosion inhibition at the addition of low inhibitor concentration and decreased inhibition of scale deposition due to scale retention and steel surface adsorption by polymers.

A study of strontium binding to albumins, by a chromatographic method involving atomic emission spectrometric detection

A chromatographic method involving ICP-AES (inductively coupled plasma atomic emission spectrometry) detection has been successfully applied for the study of strontium-protein complexes. The chromatographic step involves the use of gel filtration—a large-zone Hummel and Dreyer method—which allows to dissociate the bound metallic ions and the free ones. This step is followed by an ICP-AES analysis of fractions collected throughout the chromatographic experiment: the concentration of ionic metallic species in solution can therefore be calculated. Two proteins have been tested: bovine serum albumin, which showed only weak interactions with Sr 2+ ions, and bovine α-lactalbumin: this protein, well-known for its calcium binding capacity, proved to interact strongly with strontium. The influence of various parameters on the formation of strontium-lactalbumin complexes were determined, namely temperature, pH. Competition experiments between Sr 2+ ions and, respectively Na + and Ca 2+ ions were also performed, by varying ionic strength of the medium, and by using both apo and native forms of bovine α-lactalbumin.

Biomimetic Method for Obtaining Hydroxyapatite

Coating of bioinerts or biotolerable materials with a bioactive layer, generally composed of hydroxyapatite (HA), has been currently used when one wishes to combine bioactivity and material properties. Coating methods include: plasma and flame spray, sputtering, electrophoresis and electrolysis. Except the electrolytic one, all other methods involve high working temperatures. Therefore, the physical and chemical characteristics of hydroxyapatite can be affected, with possible consequences on the behavior of the implanted material. A recently proposed method named biomimetic, can be employed to coat several types of substrates through precipitation of a hydroxyapatite layer. This approach imitates the biological natural conditions of hydroxyapatite formation, through control of temperature, pH and concentration of ionic species. In this work, barium titanate substracts were coated with hydroxyapatite and characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy.

Wet scavenging of black carbon: black carbon and ionic species concentrations in Mt. Sonnblick cloud water

Wet scavenging of black carbon: black carbon and ionic species concentrations in Mt. Sonnblick cloud water

Effects of acidic deposition on soil ecosystems under forest in the Chongqing region of China

The effects of acidic deposition on soil ecosystems under temperate coniferous forest in the Chongqing region of China were investigated from 1993 to 1994. Precipitation, throughfall, stemflow, soil solutions, and soil samples were collected to estimate the acidification of soil ecosystems through the changes of their chemical components. The concentrations of ion species in the throughfall and stemflow under masson pine forest in Mt. Zhenwu were higher than those under mixed coniferous forest in Mt. Jinyun and under camphor tree forest in Laojundong, suggesting that Mt. Zhenwu is located in the vicinity of the Chongqing center and that it allowed the canopy of masson pine to intercept air pollutants. However, the level of aluminum dissolution into soil solutions was relatively low under masson pine forest in Mt. Zhenwu in spite of the low pH in the stemflow.

Modeling of H 2 and H 2 /CH 4 Moderate-Pressure Microwave Plasma Used for Diamond Deposition

One-dimensional transport models of moderate-pressure H 2 and H 2 /CH 4 plasmas obtained in a diamond deposition microwave reactor are presented. These models describe the plasma as a thermochemically nonequilibrium flow with three different energy modes. The solution of the one-dimensional plasma transport equations enabled the estimation of plasma species concentrations and temperatures on the axis of the reactor. As far as pure H 2 plasmas are concerned, results showed that the model predictions of gas and vibration temperatures are in good agreement with experimental measurements. The model also yields a relatively good qualitative prediction of the variations of H-atom mole fraction with the power density absorbed by the plasma. The results obtained for H 2 /CH 4 discharges showed that the model prediction on the variations of H-atom mole fraction with methane percentage in the discharge is in good qualitative agreement with experimental results. They also showed that methane is rapidly converted to acetylene before reaching the discharge zone. The concentrations of neutral hydrocarbon species in the reactor are mainly governed by thermal chemistry. The addition of methane strongly affects the ionization kinetics of the plasma. Three major ions are generally obtained in H 2 /CH 4 plasmas: C 2 H 2 + , C 2 H 3 + , and C 2 H 5 + . The relative predominance of these ions depends on the considered plasma region and on the discharge conditions. The ionic species concentrations are also mainly governed by chemistry, except very near the substrate surface. Finally the use of this transport model along with the surface chemistry model of Goodwin (1) enabled us to estimate the diamond growth rate for several discharge conditions.

Distributions of beryllium 7 and lead 2109, and soluble aerosol‐associated ionic species over the western Pacific: PEM West B, February‐March 1994

Aerosol sampling for the determination of the concentrations of soluble ionic species and the natural radionuclides 7Be and 210Pb was conducted from the NASA DC‐8 over the western Pacific as part of GTE/PEM‐West B during February‐March 1994. Concentrations of most soluble ionic species in the free troposphere were higher in samples collected on flights originating from Hong Kong and Japan than those collected further east over the open ocean. In both regions the measured concentrations were higher than those found during PEM‐West A (fall 1991). Activities of 210Pb, a tracer of air masses influenced by sources on the Asian continent, showed the same patterns. These data indicate the effect of stronger continental outflow from Asia over the western Pacific during the spring compared to fall season. For readily scavenged aerosol‐associated species and soluble acidic gases the strongest indications of Asian outflow were restricted to altitudes below 6 km. The distribution of the continental tracer 210Pb was also compared to those of a large number of gas phase species measured on the DC‐8. Relatively strong correlations were found with O3 and peroxyacetylnitrate (PAN), but only during the flights over the remote Pacific. During PEM‐West A, similar correlations were seen, but they were stronger near Asia. We believe that these correlations are a signature of continental air that has been processed by deep wet convection over land before being advected over the ocean. One flight over the Sea of Japan provided the opportunity to sample upper troposphere/lower stratosphere air in and around a tropopause fold. Concentrations of 7Be reached 7 pCi m−3 STP, and peak O3 mixing ratios of 480 ppb were encountered at 10.7 km. The 7Be data are used to estimate the fraction of stratospheric air mixed down into the troposphere by circulation in the fold.

Assessing the Role of Interfacial Electrostatics in Oriented Mineral Nucleation at Charged Organic Monolayers

Charged organic−aqueous interface electrostatics are assessed in order to clarify potential electrostatic contributions to oriented mineral nucleation at planar organic surfaces. Fatty acid and acidic phospholipid monolayers contacting aqueous solutions of sparingly soluble salts serve as model systems. Monolayer electrostatic parameters and ion distributions in the interfacial aqueous solution are calculated using a Gouy−Chapman−Stern electric double-layer model that incorporates the multiple, multivalent cations and anions found in mineralizing solutions. The calculations provide insight into the relationship between surface-directed crystallization and factors such as ion binding, surface charge density, and interfacial ion concentrations. Variations in crystal nucleation, phase, and morphology observed at charged monolayers are interpreted in terms of calculated departures from lattice ion stoichiometry and pH lowering within the interfacial aqueous solution. Lattice matching is addressed in terms of Stern layer calculations of Ca2+ ion binding at carboxylic acid monolayers. Arguments are presented suggesting that near negatively charged surfaces, soluble ionic species concentrations are enhanced relative to free anion concentrations, and a link between interfacial anion speciation and oriented mineral nucleation is proposed. Implications for biomineralization and template-directed crystallization at planar surfaces are discussed.

Chromatographic method involving inductively coupled plasma atomic emission spectrometric detection for the study of metal–protein complexes

A chromatographic method has been used to study metal ion–protein complexes. It involves successively a gel filtration technique to separate and distinguish the complexed from the free metallic ions, and a spectrometric technique, inductively coupled plasma atomic emission spectrometry (ICP-AES), which allows us to calculate accurately the concentration of ionic metallic species in solution. In the chromatographic step, we applied a large-zone Hummel and Dreyer method. Thus, fractions can be collected throughout the chromatographic experiment and their metal concentration measured by ICP-AES, at constant and known protein concentration. This method has been tested on the copper complex of bovine serum albumin. Results of our study are in good agreement with previous studies on this complex.

Ionic and trace element composition of cloud water collected on the Olympic Peninsula of Washington State

Field measurements of the chemical composition of boundary-layer clouds that formed in clean, marine air are presented as a background reference point for comparison to cloud water composition in more polluted regions. An impaction-based sampler was used to simultaneously collect cloud water on two stages, where the ratio of droplet diameter was ∼1.1 for the two droplet size fractions. Analysis revealed that large droplets were more concentrated than smaller cloud droplets by a factor of 1.5 for sea-salt-derived species. Cloud water concentrations of ionic species were generally five times greater the concentrations of the same ions in rain water. Aqueous-phase solute concentrations in cloud varied over two orders of magnitude but generally were quite low, correlated to each other and to aerosol (CN) concentration, but negatively correlated to LWC. Air-equivalent solute concentrations were calculated, allowing the detection of the influence of air-mass trajectory on cloud-water composition. A multivariate statistical analysis of the cloud water data suggested sea salt, biogenic, crustal, and anthropogenic emission source contributions; the last two sources existed only for continental air-mass trajectories. Coastal and oceanic trajectories were selected for the purpose of estimating a northern hemisphere, mid-latitude, marine, background cloud water composition of 8 neq m −3 non-sea salt SO 4 2− and 4 neq m −3 NO 3 −.

Electric Potential and Concentration of Ion Species in the Proximity of a Cell Membrane:ab initioCalculations

The mathematical model of ion transport in the field of electric forces and diffusion gradients is based on particle conservation equations and the Poisson equation which governs the distribution of the electric potential. Designed for evaluating the currents through passive ion channels in cellular membranes, the model is formulated in a two-dimensional approximation assuming rotational symmetry. Three ionic species are considered in the present study: sodium, calcium and chlorine. The program developed for the numerical solution is based on a semi-analytical approximation suggested by Gummel & Scharfetter. The present contribution reports calculations of the steady-state distributions of ionic species induced by an electric field due to a negative potential drop across the cellular membrane, which represent initial conditions for future calculations of the time development of the ion flux through the calcium channel. The numerical calculations were performed from the moment of potential application up to the time 6.2 μs, when a new steady state is established. At this stage, the maximum values of the sodium and calcium concentrations at the membrane surface are about 22% and 47% above the initial values of 145 mM and 1 mM, respectively, while the chlorine concentration is approximately 18% below. The electric field at the membrane surface is about 6.7×104and decreases exponentially with distance. The length of the boundary layer is about 40 Å.Since the model is based on fundamental principles, it can be used for the quantitative solution of any problem possessing rotational symmetry where a continuum approach is applicable and some elementary conditions are fulfilled, such as equilibrium (or at least quasi-equilibrium) of the particle energy distributions with respect to time and electric field, and the assumption that the transport coefficients are defined as functions of the field and their numerical values are known.

Determination of Ionic Strength and Equilibrium Concentrations of Heavy Metals by the Electrical Conductivity Method

Abstract A laboratory investigation of several types of heavy metal-soil solutions was conducted to evaluate the possibility of determining ionic strength and equilibrium concentrations of heavy metals and exchangeable cations by means of the electrical conductivity method. The characteristics of the heavy metal-soil interactions including retention of metals and release of exchangeable cations by the illitic soil were examined, and electrical conductivity and pH measurements of the heavy metal-soil solutions were performed. Test results revealed that direct determination of equilibrium concentrations of certain ionic species could be realized by means of electrical conductivity measurements of soil suspensions. This laboratory technique is based on determining the relationship between the ionic strengths of the heavy metal-soil solutions and their electrical conductivity in order to derive the necessary correlations to estimate the equilibrium concentrations. The proposed technique is expected to aid in the direct calculation of equilibrium concentrations of metal ions and heavy metals from data collected during site investigation for remedial activity via electric conductivity or soil resistivity techniques.

Plasma doping dosimetry

Plasma immersion ion implantation (PIII) is a large-area doping technique that can provide very high implant current at very low implant energy. Multiple ion species, plasma conditions, and implanter current-voltage waveforms in PIII lead to an exponential implant profile which is different from conventional implant profiles. A methodology is developed for using in situ measurements of the implanter current (I) and implant voltage (V) to derive an energy spectrum for a single implant pulse. The advantage of this technique is that a per-pulse profile may be determined experimentally, even in the presence of substrate etching, without any need for an implant model. If the ion species concentrations in the plasma are known, the energy spectrum found from the ion current and voltage waveforms can be used to construct a per-pulse implant profile. If the ion species distribution is not known a priori for a multispecies plasma, secondary ion mass spectroscopy (SIMS) data from an implanted sample can be used to estimate the ion species distribution and calibrate the IV-generated profile within a factor of two. Data from 1-5 kV, 2.5-5 kHz BF/sub 3/ PIII implants are used to demonstrate the concept. The implant profile for a single pulse can then be used to project the final implant profile and total implanted dose as a function of implant time, Pm pulse frequency, and substrate etching. In this work, an estimated secondary electron yield function is used to separate the total implant current into ion and secondary electron current components. The 25% dose variation error introduced by this effective secondary electron yield function could be avoided in a system which can measure ion current directly.

Voltammetric investigation of the complexation equilibria in the presence of a low level of supporting electrolyte part 1: Steady-state current-potential curves for inert complexes

The use of microelectrodes for voltammetric investigations of the complexation equilibria at very low concentrations of supporting electrolyte allows the risk of competitive complexation or contamination to be avoided, makes the activities of the species involved closer to their concentrations (which facilitates comparisons with the spectroscopic results) and finally, allows the concentrations of the species to be varied over a broader range. This paper presents the calculations of the steady-state currents for a wide range of complexes that are inert on the experimental time scale, and reports the influence of the concentration of the electroinactive ionic species on the limiting currents. Also, for a number of cases the variation of halfwave potential with the ligand concentration, resulting from changes in the ohmic drop, is given. It is assumed that only one species (the complex or the uncomplexed form) is electroactive; if this is the complex, it may or may not change the number of ligands. The theoretical results were obtained either employing the Myland-Oldham theory extended in this paper or by digital simulation. The results of calculations show that the magnitude of the changes in the steady-state limiting current on complexation depends on the type of complexation equilibrium, the type of the change in the reactant charge number in the electrode process, and the complex formation constant. In a number of situations migrational effects are negligibly small and no special treatment is necessary, despite the lack of supporting electrolyte. In other cases, where migration is significant, the relations between the measured steady-state limiting current and the complex formation constant β are given in the form of fitted equations that can be used to obtain β from appropriate experimental data.

Kinetic Studies of the Oxygen Exchange of Chromate and Arsenate Ions with Water. Catalysis by Tellurate and Tellurite Ions

Abstract The oxygen exchange reaction of the chromate ions with water is catalyzed by the tellurate and tellurite ions. The catalytic reaction rate (RC), which is defined as the increase in the rate of the chromate-oxygen exchange upon the addition of Te(VI) or Te(IV), was studied by an 18O tracer method. The catalytic process has been interpreted in terms of the rapid reversible condensation of the Cr(VI) with Te(VI) or Te(IV) species to form hetero-poly anions. As exemplified for the Cr(VI)–Te(VI) reaction system, the rate law is given as the sum of kinetic terms: RC = ∑kij[Cr(VI)]i × [Te(VI)]j where [Cr(VI)]i and [Te(VI)]j denote the concentration of the various ionic species of the chromate and tellurate ions, respectively, and kij is the rate constant of the elementary reaction between (Cr(VI))i and (Te(VI))j. The catalytic rates were analyzed according to the rate law in order to obtain the rate constants kij. The catalytic reaction system As(V)–Te(IV) was also studied. The values of kij obtained for various catalytic systems were compared with each other.

Recent climate anomalies and their impact on snow chemistry at South Pole, 1987‐1994

Three 2‐m deep snowpits sampled at South Pole in 1994 provide detailed (2‐cm resolution) profiles of the concentrations of soluble ionic species for the period 1987–1994. The most prominent feature is a large concentration spike of SO4= in snow deposited in 1992 reflecting fallout from the eruptions of Pinatubo and Hudson in 1991. Concentrations of MSA and values of the MSA/(non‐sea‐salt SO4=) ratio are elevated for about three years centered on the prominent volcanic signal. These changes appear to be due to the extended 1991–1993 El Nino. The overlapping effects of the volcanic eruptions and El Nino circulation preclude partitioning the enhanced deposition of SO4= into volcanic and biogenic fractions. Nitrate concentration profiles show no relation to the severity of O3 depletion in the Antarctic stratosphere during the period of record. Rather, the profiles show a progressive decline of the annual peak concentrations over the top 0.5–1.0 m of each pit. This behavior is attributed to post‐deposition loss of NO3−, presumably by reemission of HNO3 into the atmosphere.

Surface characterization of hemodialysis membranes based on electrokinetic measurements

AbstractHemodialysis membranes were characterized by means of streaming potential measurements. By variation of the concentrations of different ionic species in the measuring solutions surface potential determining processes can be distinguished: The investigated materials (cellulose derivates) yield surface charges mainly from preferred adsorption of ions. A thermodynamic model of the electrochemical double layer according to STERN (1) was applied to quantify that processes; the resulting set of parameters provide a conjunction between chemical surface properties and the observed interfacial charging processes.Streaming potential measurements can be used for the in situ characterization of the adsorption of biologically relevant molecules like proteins and polysaccharides onto membrane materials. The results given here show the alteration of interfacial properties of different cellulosic membranes through adsorption of human serum albumin and fibrinogen in single, sequential and competitive adsorption.