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Many studies have been conducted to improve the strength and damage resistance of phosphosilicate glasses via the introduction of Li2O through an appropriate ion-exchange process. However, very limited investigations can unveil the effect of the comprehensive mechanism of two-step ion-exchange process on the mechanical properties of glass. Increasing the amount of Li2O in phosphosilicate glasses increases the hardness and decreases the depth of ion-exchange layers of other alkali ions. With a two-step ion-exchange treatment, the hardness of glass has been enhanced by 28.3% on average. Moreover, the phosphosilicate glass system was found to achieve the maximum compression stress on optimizing the Li2O content for a glass surface after the two-step ion-exchange treatment. The mechanism of strengthening the mechanical properties was then described using atomic packing theory. This investigation will pave the way for efficient composition design for phosphosilicate glasses to meet mechanical performance requirements of various display-related and engineering applications.

Biomembranes assemble and operate at the interface with electrolyte solutions. Interactions between ions in solutions and the lipid affect the membrane structure, dynamics and electrostatic potential. In this article, I review some of the experimental and computational methods that are used to study membrane–ions interactions. Experimental methods that account for membrane–ion interactions directly and indirectly are presented first. Then, studies in which molecular dynamics simulations were used to gain an understanding of membrane–ion interactions are surveyed. Finally, the current view on membrane–ion interactions and their significance is briefly discussed.

Many modern energy storage technologies operate via the nominally reversible shuttling of alkali ions between an anode and a cathode capable of hosting them. The degradation process that occurs with normal usage is not yet fully understood, but emerging progress in analytical tools may help address this knowledge gap. By interrogating ionic fluxes over electrified surfaces, scanning probe methods may identify features that impact the local cyclability of a material and subsequently help inform rational electrode design for future generations of batteries. Methods developed for identifying ion fluxes for batteries show great promise for broader applications, including biological interfaces, corrosion, and catalysis.

It is demonstrated that a femtosecond laser beam forms in alkali-silicon glass with different Na2O concentration microregions that possess birefringence associated with the formation of nanolattices. The phase shift of such regions is determined as a function of the number and energy of the laser pulses. The minimum number of pulses required for birefringence to appear increases with increasing Na2O concentration. At 107 pulses the phase shift reaches approximately the same maximum value for all glass compositions, which indicates that the diffusion of alkali ions in the process of formation of nanolattices plays a leading role in such glasses.

A test procedure for alkali-free Cu–Co-based catalysts synthesized by co-precipitation was established allowing the fast assessment and screening of their catalytic properties in the synthesis of higher alcohols by online GC analysis. Due to precisely controlled initial deactivation of the catalysts at 280 °C long-term measurements were avoided and steady-state conditions at 260 °C were reached within a short period of time. Temperatures up to 300 °C were found to favor the formation of methanol, whereas the product distribution was not affected at lower space velocities. Even traces of alkali ions present due to insufficient washing were found to strongly affect the catalytic properties.

Chemical promotion obtained with the addition of alkalis to a metal supported catalyst induces effects on the catalytic activity very similar to those of electrochemically supplied alkali ions trough the concept of electrochemical promotion of catalysis. Despite of the functional identity and the origin between two ways of promotion analyzed here (chemical and electrochemical), which follow the same general rules, the usefulness of the latter is clear. In this review the most important and recent contributions of Electrochemical Promotion with alkaline ionic conductors (Na+ and K+ conductors) in heterogeneous catalysis have been analyzed. The possibility of in situ controlling the alkali promoter coverage on the catalyst under working conditions lead to new opportunities from both: fundamental and more applied point of view. The optimization of catalytic activity and selectivity, the activation of a catalyst at lower reaction temperatures, the permanent electro-promotional effect or the regeneration of a catalyst at fixed reaction conditions are some of the novel contributions discussed here. Due to the wide use of alkali ions as electronic promoters in heterogeneous catalysis the aim of this review is to bring closer this fascinating and novel phenomenon to the catalysis scientific community.

A chemosensor, 2,2'-(1,4-phenylenedivinylene)bis-8-acetoxyquinoline (1), its fluorescent sensing behavior toward representative alkali ions (Na(+), K(+)), alkaline earth ions (Mg(2+), Ca(2+)), and transition-metal ions (Ni(2+), Cu(2+), Zn(2+), Hg(2+), Pb(2+), Cd(2+)) was intensively investigated. The compound (1) exhibited pronounced Hg(2+) selective on-off-type fluoroionophoric properties among the representative ions in DMF/ethanol (1:9, v/v) solution. Moreover, the highly Hg(2+)-selective fluorescence quenching property in conjunction with a visible colorimetric change from colorless to light yellow can be observed, leading to potential fabrication of both "naked-eye" and fluorescent detection of Hg(2+).

A detailed characterization of the site is crucial to designing an efficient method of managing the risks associated with tailings from abandoned mines. Therefore, samples collected from various depths within tailings in Guryong mine, Korea, were analyzed for their chemical, physical and mineralogical characteristics. All samples of the Guryong tailings had acid-generating potential. However, in the oxidation zone, the net acid generation (NAG) was low (30 kg H2SO4 t−1) although the acid neutralization potential (ANP) was less than zero. The ANP values in the unoxidation zone were higher (> −56.0 kg CaCO3 t−1) than in the other zones. As a result, the amount of alkali ions that are needed to neutralize the acid needs to be considered. In this experiment G3, G4 and G6 drill cores containing fine tailings particles near the unoxidation zone were observed to contain calcite (CaCO3) with acid-neutralizing capacity. A low pH (2−4) in the oxidation zone of the tailings changed to a neutral pH in the unoxidation zone of the tailings. These results suggest that the acid-neutralizing capacity of the tailings was controlled by particle and mineral composition of tailings.

Structures of NASICON glasses of the general formula AB(2)(PO4)(3), Where A = Li, Na or K and B = Fe, Ga, Ti, V or Nb, have been investigated using vibrational (IR and Raman) spectroscopies. Phosphate species appear to establish an equilibrium via a disproportionation reaction involving a dynamical bond-switching mechanism where both charge and bonds are conserved. B ions in the system acquire different coordinations to oxygens. Alkali ions cause absorptions due to cage vibrations. All the observed spectroscopic features are consistent with speciation involving disproportionation reactions.

The spectral properties of amorphous media synthesized on the basis of glasses of the system SiO2-CaO-R2O (R=Na, K, Li), the ternary compounds CuInSe2, and CuInTe2, and solid solutions based on them have been investigated. It is shown that the absorption limit of the media investigated lies within 1.4–1.6 µm. It is noted that the three alkali ions constituting the system exert a favorable influence on the state and optical properties of the amorphous media activated with the compound CuInTe2 and with the solid solutions CuInSe2xTe(1−x), where x≤0.5. The influence of the concentration of the solid solution CuInSeTe (x=0.5) on the optical properties of the amorphous media is investigated.

XRD shows that doping BaBiO3 with alkali ions transforms the larger monoclinic parent lattice into a more compact cubic or nearly cubic lattice. This lattice contraction favors the transition from semiconductor to metal. It leads also to superconductivity. Doping BaBiO3 with both K and Rb raises the onset resistivity Tc above those obtained by doping with either K or Rb.

The first excited states of the rare gas alkali ions have been calculated using Hellmanntype model potentials. The predicted decay energies agree with the results of a recent measurement within 2%.

The properties of vanadium oxide xerogels are reviewed with respect to guest-host chemistry, redox chemistry and electrical charge transport. The insertion chemistry of several conductive and insulating polymers and alkali ions. The physical properties of the resulting materials is discussed.

Alkali and alkaline earth ions in rain water can be determined by ion chromatography (IC) without preconcentration. The detection limits for alkali ions are between about 0.05 and 0.15 μmol/l and those for alkaline earth ions between about 0.2 and 0.6 μmol/l. The main advantages of IC are: very small sample volumes are sufficient; the simultaneous determination of the alkali ions or the alkaline earth ions requires less than 30 min; NH 4 + ions can also be determined. The results are compared with those obtained by flame AAS and AES-ICP.

Electrical conductivity studies have been reported on Rb2Ti4O9, Rb2Ti5O11 and RbKTi4O9 in the temperature range 373 K to 750 K. Three distinct regions have been identified in the log(σT) versus 1000/T plots, the lowest temperature region being attributed to extrinsic defects, the intermediate one to exchange of alkali ions and the highest temperature region to thermally created defects. A phase transition is indicated for each of the three compounds. The plot of resistivity with temperature further indicates the occurrence of a positive temperature coefficient of resistivity in RbKTi4O9.

The distribution coefficient of sulphide, sulphite, sulphate and thiosulphate anions between different concentrations of aqueous alkali metal chloride solutions and the anion exchanger Dowex 1X8 is studied. The obtained distribution deportment of these anions is explained in the light of water-water, anion-cation and ion-ion interactions as well as the different tendencies of the alkali ions to hydration. Based on the separation factors encountered between adjacent anions, a chromatographic method is adopted for isolation of the sulphur anions by gradient elution. This method is further compared with the chromatographic procedures so far reported for separation of the investigated anions.

Raman spectra of K2O-Nb2O5-SiO2 glasses are measured in order to compare the coordination state of Nb5+ ions in gallate glasses with that in silicate glasses. It is found that less-distorted NbO6 octahedra with no non-bridging oxygens as well as NbO6 octahedra with non-bridging oxygens and/or with much distortion are present in the K2O-Nb2O5-SiO2 glasses. The Raman band in the 800 to 900 cm−1 region is attributed to the NbO6 octahedra with non-bridging oxygens and/or with much distortion. The broad bands in the 600 to 800 cm−1 region are attributed to less-distorted NbO6 octahedra with no non-bridging oxygens. An increase in the molar ratio Nb2O5/K2O leads to an increase in the oxygens shared by more than two polyhedra and/or a decrease in non-bridging oxygens for the NbO6 octahedra which possess non-bridging oxygens, or to an increase of distortion for much-distorted NbO6 octahedra. At the same time, an increase in the molar ratio Nb2O5/K2O increases the less-distorted NbO6 octahedra with no non-bridging oxygens. In short, GaO4 tetrahedra and NbO6 octahedra compete to attract alkali ions in gallate glasses but such competition is not found in silicate glasses.

The clinker raw mixture (84 wt % limestone + 12 wt % clay +4 wt% pyrite ash) was divided into five portions. Each portion was mixed with an alkali carbonate and fired at a certain temperature along half an hour then quenched in air. A portion was left without alkali and fired at 1450°C to investigate the effect of alkali addition. Each portion was ground and refired at a temperature less than the first firing by about 100°C for ten hours to ensure that the cliniker had been fully formed, then quenched in air. Each clinker was measured by Mossbauer spectrometer and x-ray diffractometer. Each clinker was mixed with 5 wt% natural gypsum then with 25 wt% water. The compressive stength test was performed at three days of hydration. The results were compared with the results of ordinary Portland cement.

AC conductivity and dielectric properties of sulphate glasses have been studied as a function of temperature, frequency and variation in interalkali concentration. AC conductivity at frequencies well beyond the dielectric loss peaks seems to arise from local motion of alkali ions within the neighbouring potential wells. Activation energies for AC conductivity were found to be very much lower than those for DC conductivity. Further, AC conductivity seems to be independent of interalkali variation, whereas e′ and tan δ show a mild degree of mixed alkali effect. The observations made here have been explained on the basis of a structural model earlier proposed by us for these glasses.

1. Nach einem kurzen Uberblick uber die Muskelpharmakologie der Ionen Natrium, Kalium, Lithium, Magnesium und Calcium werden die Ergebnisse folgender Versuche mitgeteilt: a) Weisen Musen wurde jeweils 1,5 ml einer wasrigen blutisotonischen Losung eines Chlorides der genannten Kationen intraperitoneal injiziert. Uberlebenszeiten zwischen 10 und 100 min. b) Ein ganzes herausgeschnittenes Musezwerchfell wurde 30 min in eine blutisotonische KCl- bzw. CaCl2- Losung eingelegt. Nach den Versuchen wurde die Muskulatur des Zwerchfells elektronenmikroskopisch untersucht. 2. NaCl hat keinen Einflus auf die normalen Strukturen. 3. KCl fuhrt zur Schwellung der ganzen Muskelfasern und der Kapillarendothelien. Die Ursache wird in der Storung eines Donnan-Systems mit nachfolgendem Wassereinstrom gesehen. Die Schwellung der Mitochondrien und des sarkoplasmatischen Retikulums wird als sekundarer Effekt betrachtet. 4. Nach LiCl treten vermehrt Granula in Mitochondrien und im Sarkoplasma auf. Eine Deutung wird durch die dem Lithium eigene Neigung zu Polymerisation und Komplexbildung versucht. 5. MgCl2 erhalt die Membranstrukturen sehr gut. Dieser Effekt konnte durch die Stimulierung der ATPasen von Sarkolemm, Retikulum und Mitochondrien bedingt sein. 6. Nach CaCl2 sind am herausgeschnittenen Zwerchfell die Muskelfasern sehr gut erhalten, wahrend die ubrigen Gewebsbestandteile stark destruiert erscheinen. Wahrscheinlich dichtet Calcium in hoher Konzentration das Sarkolemm ab. 7. Nach intravitaler Calciumresorption sind die Schadigungen der Muskelfasern starker. Auffallig sind die geschwollenen Rume des sarkoplasmatischen Retikulums im Bereich der gefasnah liegenden grosen Mitochondriengruppen. Da das Retikulum die Fahigkeit hat, Calcium unter ATP-Verbrauch zu binden, wird hierin ein Zeichen fur die unter Calciumuberschus auftretende Insuffizienz dieses Bindungssystems gesehen. Durch vermehrt in den Rumen vorliegendes ungebundenes Calcium konnte es zur Erhohung des osmotischen Druckes kommen. 8. Es wird versucht, eine Beziehung zwischen der Calciumwirkung auf das Treppenphanomen und den morphologischen Befunden herzustellen. 9. Eine Synapse zeigt nach Calciumresorption vermehrt sich entleerende prasynaptische Blaschen. Vielleicht ist dieses der Ausdruck fur die vermehrte Freisetzung von Acetylcholin an der nicht erregten Synapse unter der Einwirkung von Ca2+. 10. Bei den Versuchen mit KCl fiel auf, das der mediale Teil der Triaden, das T-System, von der Schwellung des Retikulums ausgenommen bleibt. In einem Serienschnitt konnten zwei offene Verbindungen zwischen T-System und Interstitium gezeigt werden. Die Ausbreitung der Erregung vom Sarkolemm entlang der Tubuli des T-Systems ins Innere der Faser, und die Uberleitung auf das sarkoplasmatische Retikulum werden diskutiert.

Les additifs utilises sont: Li 2 CO 3 ; Na 2 Co 3 ; K 2 CO 3 et MgCO 3 . L'etude spectroscopique porte sur le ciment et sur le clinker

The lack of general applicability of the many theoretical models for the mixed alkali effect (MAE) in glasses is briefly reviewed. Although the MAE appears to be related to the bonding affinity of alkali ions to charge compensating centers in the glass network, experimental scatter and the difficulty of comparing different glass networks have prevented systematic tests of this relationship. The present paper discusses why the mixed alkali germanate glasses should provide a glass system where the concentration and strength of charge-compensating centers can be systematically varied and the relationship to the MAE tested. Such tests are only possible if the ionic conductivity of a series of mixed alkali germanate glasses can be measured in a reproducible manner. The measurements of the ionic conductivity of two series of X(Na,Rb)2O:(1-X)GeO2glasses, with X = 0.19 and X = 0.29, respectively, suggest the necessary reproducibility can be attained.

Alkali ions, which compensate for substitional Al3+, play an important role in the frequency stability of α-quartz crystals. In this work, low temperature dielectricloss measurements (between 2.9 and 300 K) are carried out on crystals that have been “swept” so as to introduce either Li+ or Na+. High quality synthetic crystals as well as natural crystals are employed. The well known loss peaks due to Al-Na pairs are further explored and similar peaks due to Al-Li are sought after but not found. It is concluded that the Al-Li pair is oriented along the C2 -axis of the A104 distorted tetrahedron. After irradiation, large peaks are observed at very low temperatures both in Li+- and Na+-containing crystals. These peaks, which are distorted below ∼6 K due to the onset of quantum effects, may originate in alkali centers produced when alkali ions are liberated by the irradiation.

THE first structural determination of a β-alumina compound containing two different alkali ions, lithium and sodium, in crystallographically distinct sites in the conducting plane is reported here. The lithium ions are displaced by about 1 A from the mirror planes. Although such a displacement has been suspected it has not hitherto been confirmed.

NITROGEN is one of the most abundant elements in the cosmos; in the Sun, only H, He, O and C exceed it1. In the Earth's crust it ranks only as the thirty-first element in magmatic rocks2, at a level of about 20 p.p.m. Because of the analytic difficulties in determining the nitrogen content of rocks little work has been done in this direction since Lord Rayleigh's determinations3, which gave nitrogen contents in the range of 28 to 68 p.p.m. for a variety of magmatic rocks. These values are confirmed by recent determinations4. Most workers assume, without further proof, that most or all nitrogen is present as the ammonium ion3,5, substituting to a small extent for alkali ions in the minerals.

THE Lawrence Smith method, which is well known as a procedure for the chemical analysis of alkali ions, has not been considered in the light of structural chemistry. Here we are considering the chemical reaction from the structural chemistry point of view and show that hydrogarnet is frequently formed, which suggests that the reaction should await further studies in relation to the natural skarnization.

INTEREST in the chemistry of gaseous ion clusters has increased sharply since the discovery1 of water-cluster ions in the D-region of the ionosphere. Furthermore, the fact that the electrical properties of the atmosphere are partly governed by the presence of small ions, which may undergo clustering reactions with trace constituents of the air, has also stimulated research into the properties and structure of the clusters. But knowledge of the structure of ion clusters is still rudimentary. Kebarle and colleagues2 have measured the gas-phase hydration enthalpies of alkali ions and compared the experimental results with calculated potential energies of the corresponding water-cluster ions. These calculations, made on the basis of an electrostatic model adopted from the classical theory of complex ions in solution, showed good agreement with the experimental results only for relative values, but not for absolute energies. Other investigators3 have employed molecular-orbital theory to calculate the energies of hydrated protons and shown that, in the case of H9O4, a chain structure is as feasible as a symmetrically branched structure proposed by Eigen4.

IN a communication under the above title, published in Nature of May 31, 1947, p. 746, J. L. Mongar and A. Wassermann report some experiments on the de-swelling of calcium alginate fibres in salt solutions. They noted that water-swollen alginate fibres when placed in various alkali-salt solutions first contract and then increase in length. The authors suggest that the contraction results from destruction of calcium ion cross-links between alginate chains as the calcium is replaced by alkali ions. They propose also that plastic flow is mainly responsible for the final swelling effect.