Concentration Of Alkali Ions Research Articles

Cytotoxicity of municipal solid waste incinerator ash wastes toward mammalian kidney cell lines

In this study, three municipal solid waste incinerator (MSWI) ash wastes—bottom ash, scrubber residue, and baghouse ash—were extracted using a toxicity characteristic leaching procedure (TCLP) extractant. These so-called final TCLP extracts were applied to African green monkey kidney cells (Vero), baby hamster kidney cells (BHK-21), and pig kidney cells (PK-15), multi-well absorption reader analysis was performed to test how the cytotoxicity of the incineration ashes would affect the digestive systems of animals. Ion-coupled plasma analyses indicated that the baghouse ash extract possessed the highest pH and heavy metal concentration, its cytotoxicity was also the highest. In contrast, the bottom ash and the scrubber residue exhibited very low cytotoxicities. The cytotoxicities of mixtures of baghouse ash and scrubber residue toward the three tested cell lines increased as the relative ratio of the baghouse ash increased, especially for the Vero cells. The slight cytotoxicity of the scrubber residue arose mainly from the presence of Cr species, whereas the high cytotoxicity of the baghouse ash resulted from its high content of heavy metals and alkali ions. In addition, it appears that the dissolved total organic carbon content of these ash wastes can reduce the cytotoxicity of ash wastes that collect in animal cells.

Anodic Bonding of Ag-Impregnated Glass and Reaction of Derived Joints to Reverse Voltage

When a voltage in the direction opposite to that for anodic bonding is applied to an anodically-bonded joint of glass whose alkali ion content is substituted by silver, silver precipitates of peculiar morphology form in the glass adjacent to the joint interface. In order to acquire knowledge about factors that control the configuration of the precipitates, effects of bonding time of the joints and application temperature of the reverse voltage on morphology of the precipitates were investigated. Shortening of the bonding time and increase of the application temperature of the reverse voltage cause decrease of the size of precipitates, and these effects were explained from formation frequency of current paths in the Ag+ depletion layer with penetration of Ag+ ions into the layer.

Ionic mechanisms in the optically stimulated luminescence of quartz

AbstractAmong the many centres found in crystalline quartz it is well known that Al, substitutional for Si, is always present in different concentrations giving rise at Room Temperature to ionic migration of the associated alkali ions. Many authors evidenced that these alkali ions are involved in trapping and recombination at the basis of Thermally and Optically Stimulated Luminescence, TL and OSL respectively. We have focused our attention on the OSL of quartz that is now widely used in sediment dating, although the trapping‐detrapping mechanisms have not yet been clarified. Bulk synthetic crystalline quartz, with known concentrations of Al and alkali ions has been used. There is evidence that an ionic migration is at the basis of the OSL phenomenon, linking OSL emission with the TL peaks known as “110 °C” and “325 °C”. This result is also supported by Radioluminescence (RL) measurements performed on swept and unswept quartzes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Compact Layer of Alkali Ions at the Surface of Colloidal Silica

The forces of electrical imaging strongly polarize the surface of colloidal silica. I used X-ray scattering to study the adsorbed 2-nm-thick compact layer of alkali ions at the surface of concentrated solutions of 5-nm, 7-nm, and 22-nm particles, stabilized either by NaOH or a mixture of NaOH and CsOH, with the total bulk concentration of alkali ions ranging from 0.1- to 0.7-mol/L. The observed structure of the compact layer is almost independent of the size of the particles and concentration of alkali base in the sol; it can be described by a two-layer model, i.e., an ~ 8 Angstrom thick layer of directly adsorbed hydrated alkali ions with a surface concentration 3x10(18) m(-2), and a ~ 13 Angstrom thick layer with a surface concentration of sodium ions 8x10(18) m(-2). In cesium-enriched sols, Cs+ ions preferentially adsorb in the first layer replacing Na+; their density in the second layer does not depend on the presence of cesium in the sol. The difference in the adsorption of Cs+ and Na+ ions can be explained by the ion-size-dependent term in the electrostatic Gibbs energy equation derived earlier by others. I also discuss the surface charge density and the value of surface tension at the sol's surface.

Electrical behaviour of materials based on monoclinic celsian derived from cation-exchanged commercial zeolites

Monoclinic celsian has been obtained by a non-conventional way, i.e. the thermal treatment of 4A-type commercial zeolite: a stoichiometric amount of barium ions was included in the zeolite by means of a cation-exchange treatment. A small concentration of alkali ions (either sodium or lithium) was also present in the exchanged zeolite, since previous studies had underlined the positive effect of these ions on the formation of monoclinic celsian. This particular synthesis proves to be economic, due to the low-cost precursors, the low temperatures and the short times required. However, the presence of even a small content of alkali ions and a residual amorphous phase can negatively affect the insulating properties of the material, thus hindering its use in electrical insulating systems. The results so far obtained show that the material keeps good insulating properties at low temperature, but its conductivity and dielectric losses strongly increase above 200 °C.

Electronic and ionic relaxations in oxide glasses

A survey of relaxation processes in glasses exhibiting electronic and electronic–ionic conductivity mechanisms is presented. Electrical conductivity data on a range of transition metal oxide (TMO) glasses shows that a polaronic model of conductivity is generally applicable. It is shown that in TMO glasses both ac and dc conductivity processes are due to the same mechanism, which is hopping of small polarons between transition metal ions in different valence states. By applying scaling using the BNN relation it is possible to obtain universal conductivity curve and to find the relation between ac and dc activation energy. Complex plot of electric modulus gives a simple method of scaling analysis. An attempt of classification of mixed electronic–ionic behaviour in TMO containing alkali ions was performed on the basis of impedance spectroscopy. A deep minimum of conductivity at certain content of alkali ions is observed in glasses where TMO is a glass former. Two different behaviours can be distinguished in glasses where TMO is a glass network modifier. In glasses containing iron oxide electrical properties are only slightly influenced by alkali ions. A mixed electronic–ionic conduction is observed in glasses containing copper oxides. It is shown that the internal friction method is a powerful tool for the study of relaxation processes in glasses. In electronic and ionic conducting glasses internal friction spectra reveal a peak which activation energy is identical as for the dc conductivity. In mixed electronic–ionic conducting glasses the internal friction spectra reveal two peaks, which are attributed to the electronic hopping and the alkali ion migration. A comparison of internal friction and impedance spectroscopy investigations indicates that the internal friction is a more sensitive method for detecting local movement of ions or polarons in the glass network.

Water quality assessment of different reservoir types in relation to nutrient solution use in hydroponics

Hydroponics requires good quality water. For this purpose, water quality is based on concentrations of specific ions and phytotoxic substances as well as the presence of organisms and substances that can clog irrigation systems. Here, four irrigation reservoirs, i.e. two rainwater ponds, a peat ditch, and a natural lake, were analyzed to determine whether or not they conform to water quality guidelines. Based on our data, the four reservoirs could be divided into two categories in respect to their water quality. The two rainwater ponds belong to the category characterized by low input of ionic strength (480 μmol m −1), low concentration of unwanted ions, such as SO 4 2− (63 μmol l −1) and Zn 2+ (3.9 μmol l −1), a moderate bacterial population (lg 4.9 CFU m −1), and moderate algae density (lg 6.0 cells ml −1). The rainwater ponds were found to contain a good diversity in bacteria (45 species from 25 genera), and a poor diversity of algae (15 species from 4 groups). The other category, to which the peat ditch and natural lake belong, is characterized by a high ionic strength (12,200 μmol l −1), high concentrations of alkali ions (Mg 2+: 890 μmol l −1; Ca 2+: 3.260 μmol l −1; K +: 470 μmol l −1), a moderate bacterial (lg 4.7 CFU ml −1), but low algae density (lg 5.0 cells ml −1). In comparison to the first category, the diversity of the bacteria was poor (seven species from three genera). However, in sharp contrast was the rich algal community detected in the peat ditch, for which 32 species from six groups were found, whereas in the natural lake, only one group with seven species was identified. In all reservoirs, species of the genera Paenibacillus and Bacillus were detected, and small green algae, e.g. Scenedesmus spp., also dominated in each case. Overall, the bacterial and algal densities showed wide fluctuations between water sources, and neither caused filter clogging as observed in investigations of others. The quality of the rainwater investigated was assessed to be well suited for use in hydroponics due to appropriate nutrient concentration (except Zn 2+ in one pond), and lack of potential bacterial and algal development. However, we recommend water from the natural lake and the peat ditch to be used with care because of the high nutrient concentration.

Interfacial reaction in anodically bonded joints during receiving reverse voltage

A voltage in the opposite direction to that of anodic bonding was applied to anodically bonded joints of Fe and Kovar alloys to borosilicate glass at a temperature at which thermal diffusion of the alkali ions in the glass was activated. Disjunction of the bond interfaces occurred in the Kovar/glass joints. On the other hand, the Fe/glass joints retained cohesion of their bond interface after a long application of the reverse voltage. In an as-bonded Kovar alloy/glass joint, a reaction layer of a crystalline Fe oxide was found at the bond interface. The content of Fe in Kovar alloy adjacent to the bond interface decreased. The oxide layer was formed by the reaction between Fe from the Kovar alloy and O from the alkali ion depletion layer in the glass. The reaction layer in an Fe/glass joint was of amorphous Fe–Si oxide. This layer was much thicker than the reaction layer in the Kovar/glass joint. After application of the reverse voltage, Fe in the amorphous oxide layer in Fe/glass was substituted by alkali ions. It was suggested that this process mitigated concentration of alkali ions at the bond interface and prevented disjunction of Fe/glass joints by the reverse voltage.

Effect of hydrolyzed surface layer on the cytotoxicity and chemical resistance of a low fusing porcelain

Objectives. The objectives of this study were to verify the formation of a hydrolyzed surface layer on Duceram LFC and to determine its effect on the cytotoxicity of the porcelain as measured by cellular activity and concentrations of leached ionic species. Methods. Specimens were fabricated from dentin porcelain by a vibration blotting technique. Half of the specimens underwent accelerated aging by subjecting them to the standard test for hydrolytic resistance (ISO 6872). Fibroblast cell cultures were placed in direct contact with specimens. Cell viability was assessed using succinic dehydrogenase activity. Chemical resistance was determined by leaching specimens with a continuous flow of deionized water and measuring the concentrations of soluble ions in the leachates. Porcelain surface topography was examined using atomic force microscopy, and Fourier transform infrared spectroscopy was used to detect the composition of the surface layer. Results. Hydrolyzation treatment created a smooth texture on the porcelain surfaces but did not result in a hydrolyzed surface layer with increased hydroxyl content. There was a decreased alkali ion content in the surface layer of hydrolyzed specimens. Mean cellular SDH activities for non-hydrolyzed and hydrolyzed porcelain were 75±7 and 80±5% of Teflon ® controls, respectively. Only sodium ions were present in significant concentrations in collected leachates. The sodium concentration decreased over the initial 4.5 h of leaching. Significance. The changes in surface layer texture and composition as the result of the aging treatment had little effect on the cytotoxicity and chemical resistance of Duceram LFC. The results suggest that Duceram LFC would pose no biocompatibility risk even after extended exposure to the oral environment. These data also provide baseline material properties to be used in future studies of the effects of porcelain additives.

Alkali and halogen dependence of optical absorption bands of alkali-borate glasses

We examined the alkali and halogen ion concentration dependence of the optical absorption in alkali borate glasses. When potassium iodide was added to alkali borate glasses, I 3 − molecules were formed and induced two bands with peaks at 287 and 354 nm. These bands increased with K 2O concentrations until 10 mol%, and decreased with K 2O from 20 to 25 mol%. In glasses with additions of KBr and KCl, the bands were observed at 266 and 259 nm, respectively. These positions were negligibly influenced by the kind of alkali ions. It is confirmed that all of these bands are attributed to the X 3 − ions (X: halogen), by the comparison with absorption spectra of thin films prepared by simultaneous evaporation of alkali halide and a small amount of halogen. Molecular orbital (MO) calculations were also carried out to examine the charge distribution and structures. From the experimental results and MO calculations, we suggest that the X 3 − ion binds to a boroxol ring that is coupled with a triborate group through an alkali ion.

Long-term effectiveness of supplementary cementing materials against alkali–silica reaction

The long-term effectiveness of six supplementary cementing materials (SCM) were tested according to the CSA-A23.2-14A Concrete Prism Method in the presence of two very alkali–silica reactive aggregates from Canada. Three fly ashes, two silica fumes, and one ground granulated blast furnace slag (GGBFS) were selected based on their elemental composition in order to represent a wide range of composition. The performance of SCMs in suppressing expansion due to alkali–silica reaction was compared with that obtained by a low-alkali cement. Pore solution composition of the mixtures was also determined. Results show that expansion curves flatten out after 2 years of curing. This phenomenon was due to alkali leaching from the concrete prisms and alkali binding by the alkali aggregate reaction products in the presence of the very reactive aggregates used, which was supported by very low alkali ion concentrations measured on concrete samples at the end of the experiment. A 2-year expansion limit is then suggested when using the CAN/CSA-A23.2-14A method to evaluate mixtures containing SCM. The proportion of SCM and total alkali content of the concrete are very significant factors controlling concrete expansion.

Viscosity and Speed of Sound of Potassium Nitrate and Lithium Nitrate in Poly(ethylene glycol)

Densities, viscosities, and speeds of sound of 0.15[xKNO3 + (1 − x)LiNO3] + 0.85[poly(ethylene glycol)] and 0.20[xKNO3 + (1 − x)LiNO3] + 0.80[poly(ethylene glycol)] systems (molecular weight of poly(ethylene glycol) = 300) were measured as functions of composition (x = 0.0 to 1.0 mole fraction) and temperature (273.15 ≤ T/K ≤ 343.15). The viscosity and the structural relaxation time were found to be non-Arrhenius temperature dependent and were analyzed by using the Vogel−Tamman−Fulcher equation. The normalized viscosity isotherm exhibits a significant mixed alkali effect for the 0.20[xKNO3 + (1 − x)LiNO3] + 0.80[poly(ethylene glycol)] system at 273.15 K. The onset of the mixed alkali effect in this system has been explained by the competitive polarization model. The absence of the mixed alkali effect in the 0.15[xKNO3 + (1 − x)LiNO3] + 0.85[poly(ethylene glycol)] system is attributed to the lesser amount of total alkali ion content in the system.

Extended stability ranges of β-aluminas with increasing ionic radii of metal alkali ions

Alkali (M)-β-aluminas were prepared by the soft chemistry method of gel-to-crystalline conversion (G–C) technique. The β-aluminas showed an extended compositional field of stability with respect to the alumina-content with increasing ionic radius of the alkali metal ions. Thus, the compositional stability of β-alumina is extended from M 2O/Al 2O 3 of 1:11 for Na + to 1:17 for K + and 1:22 for Rb +. High resolution electron microscopy (HREM) reveals that the decreasing concentration of alkali ions in the conducting planes is balanced by the changing widths of spinel blocks arising from the shift of tetrahedral Al 3+ to octahedral sites and the accompanying increase in stacking defects.

Electron paramagnetic resonance spectra of VO 2+ ions in NaI–Na 2O–K 2O–B 2O 3 mixed alkali glasses

The electron paramagnetic resonance (EPR) spectra of VO 2+ ions in the 15 NaI–(15 − x)Na 2O– xK 2O–B 2O 3 mixed alkali glass system were analysed at X-band frequencies at 310 K. The spin-Hamiltonian parameters and covalency rates were evaluated. It was found that the V 4+ ions exist as vanadyl (VO 2+) ions and are in an octahedral coordination with a tetragonal compression. The covalency rates (1 − α 2) and (1 − υ 2) indicate moderate covalency for the σ- and the π-bonds. It was observed that the spin-Hamiltonian parameters depend slightly on the relative alkali ion concentrations of K and Na.

Structure and morphology changes caused by wash treatment of tungstic acid precipitates

Crystalline H 2WO 4.H 2O, (WO 3.2H 2O) powder samples have been prepared by acidification of alkali tungstate aqueous solution. In order to decrease the alkali ion content of the precipitate from about 6×10 5 to 10–10 2 ppm, wash treatments have been applied. The influence of the wash treatment on the structure and hydration state of the solid product has been investigated by X-ray powder diffraction (XRD) and infrared absorption spectroscopy (IR). Morphology of the precipitate and the time development of the morphology during washing steps have been studied by scanning electron microscopy (SEM). The formation and transformation of an intermediate, the so-called tungstic acid C phase have been observed in the sequence of the washing steps. Reversible changes in the hydration state: WO 3.2H 2O↔WO 3.H 2O have also been observed at washing with long time interaction between crystallites and washing liquid with pH≥4.6.

Structural evolution during Cu +/Na + ion-exchange in the system Na 2O–Al 2O 3–SiO 2

Structural evolution during Cu +/Na + ion-exchange treatment and resultant electrical properties in sodium aluminosilicate glass were investigated by using 29Si, 27Al nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy and measurement of electrical conductivity. Ion-exchange treatments were performed on 20Na 2O–10Al 2O 3–70SiO 2 glass at a temperature well below the glass transition temperature, T g, of the initial glass. Glass specimens with various Cu +/Na + ratios were obtained by ion-exchange and concentration equalizing treatment. The foreign Cu + ions induced a large structural redistribution in the glass network causing a large reduction in T g of about 300 K, and leading to a change in the coordination of the Al 3+ ion from four-fold to six-fold in the ion-exchanged specimens. The electrical conductivity was increased up to the order of 10 −4 S cm −1 at 200°C and the activation energy decreased drastically in ion-exchanged specimens containing Cu + ion concentration of 75% the total alkali ion concentration.

Low-temperature anodic bonding of silicon to silicon wafers by means of intermediate glass layers

Silicon wafers have been anodically bonded to sputtered lithium borosilicate glass layers (Itb 1060) at temperatures as low as 150–180 °C and to sputtered Corning 7740 glass layers at 400 °C. Dependent on the thickness of the glass layer and the sputtering rate, the sputtered glass layers incorporate compressive stresses which cause the wafer to bow. As a result of this bowing, no anodic bond can be established especially along the edges of the silicon wafer. Successful anodic bonding not only requires plane surfaces, but also is determined very much by the alkali concentration in the glass layer. The concentration of alkali ions as measured by EDX and SNMS depends on both the sputtering rate and the oxygen fraction in the argon process gas. In Itb 1060 layers produced at a sputtering rate of 0.2 nm/s, and in Corning 7740 layers produced at sputtering rates of 0.03 and 0.5 nm/s, respectively, the concentration of alkali ions in the glass layers was sufficiently high, at oxygen partial pressures below 10-4 Pa, to achieve anodic bonding. High-frequency ultrasonic microanalysis allowed the bonding area to be examined non-destructively. Tensile strengths between 4 and 14 MPa were measured in subsequent destructive tensile tests of single-bonded specimens.

Valinomycin-mediated transport of alkali cations through solid supported membranes

Highly flexible lipid bilayers were immobilized on gold surfaces via self-assembly of thiolipids on gold in order to obtain an appropriate matrix for the carrier valinomycin. The bilayers were created by chemisorption of thiolipids to form the first hydrophobic monolayer on the gold substrate and subsequent fusion of unilamellar 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphocholine vesicles resulted in the second physisorbed monolayer. The synthesis of the thiolipid is based on the functionalization of phosphatidylethanolamine with a linker consisting of succinic acid hooked on a thiolated tetraethyleneglycol serving as the hydrophilic linker responsible for the flexibility of the monolayer and the anchor group. The solid supported membranes were characterized by X-ray photoelectron spectroscopy and impedance spectroscopy. The latter technique revealed that the bilayers form a considerable barrier against ions in solution. The capacitance and resistivity of the prepared bilayers amount to C m=1.0±0.2 μF/cm 2 and R m=11 000±1000 Ω cm 2 in 10 mM Tris, 50 mM N(CH 3) 4Cl, pH 7.0. Ion transport of sodium and potassium ions through the bilayers in the absence and presence of valinomycin was investigated by impedance spectroscopy in the frequency range of 10 −1–10 6 s −1. Valinomycin was dissolved in dimethyl sulfoxide and added to the bilayer. Data evaluation was performed using a modified model established by de Levie for carrier-mediated ion transport through free-standing lipid bilayers making use of the continuum equation. The membrane resistance showed the expected linear relation to the reciprocal of the valinomycin concentration in solution. The conductivity of the membrane in the presence of valinomycin corrected for the conductivity in the absence of the carrier vs. the concentration of alkali ions in solution showed a tenfold larger slope for potassium than for sodium ions.

The effect of Al 3+, Na + and Li + impurities on the charging ability of single-crystalline quartz under electron beam irradiation

Quartz crystals which are either natural or synthetic, always contain some impurities in the ppm range. Of the possible impurities that may be present, most notable is the trivalent substitutional cation Al 3+ for Si 4+ and interstitial alkali ions (M +) such as Na + and Li +. In the present paper, the charging ability of the quartz samples with impurities under electron beam irradiation was investigated by a time-resolved current method and a mirror image method employing a scanning electron microscope (SEM). The experimental results obtained by both methods are consistent and reveal that the quartz sample with least concentration of free-interstitial alkali ions (M +) has highest charging ability. An analysis reveals that the defects due to electron beam irradiation play an important role in electron trapping, while the free-interstitial alkali ions contribute to the sample conductivity and release the trapped charge.

Spatial distributions and chemical environments of cations in single- and mixed alkali borate glasses: Evidence from solid state NMR

The structural environments and the spatial distributions of the alkali ions in single- and mixed-alkali borate glasses are studied by complementary solid state NMR techniques. Specifically, spin echo decay spectroscopy is used to extract homodipolar second moments for 23 Na and 133 Cs in binary sodium and cesium borate glasses. These values are found to be quantitatively most consistent with spatially homogeneous cation distributions, except in sodium borate glasses with cation contents ≤16 mole %. Complementary isotropic chemical shifts extracted from field-dependent magic-angle spinning (MAS)-NMR depend linearly on alkali ion content, revealing a continuous concomitant change in the oxygen environment of the alkali ions. This effect can be related to structural changes in the network, where trigonal BO 3/2 units are progressively converted to tetrahedral BO 4/2 − sites as the alkali oxide content is increased. Taken together these data argue strongly against cation clustering models previously proposed for other types of glass systems. Isotropic 7 Li and 23 Na chemical shift data measured for mixed-alkali Li,Na and K,Na-borate glasses containing 30 mole % alkali oxide indicate universal compositional trends that can be understood in terms of the site-mismatch concept of Bunde's dynamic structure model: Consistent with current semi-empirical predictions, mismatching the cation of interest, e.g. Na + to a smaller Li site produces a low-frequency shift, while mismatching to a larger K site produces high-frequency 23 Na isotropic chemical shifts.