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Flavin compounds are of great interest in biochemistry because of their diverse functions in catalytic and photochemical processes. The intrinsic optical properties of flavins depend sensitively on their environment such as complexation with metal ions. Herein, we characterize the interaction of alkali metal ions (M

Antiperovskites exhibit promising potential in the application of all-solid-state batteries due to their high ionic conductivity. A comprehensive understanding of the diffusion mechanism of alkali ions in antiperovskites is significant to explore novel antiperovskite electrolyte materials. In this work, we report the migration mechanism of alkali ions in Ruddlesden–Popper (RP) antiperovskites A4OX2 (A = Li, Na; X = Cl, Br, I) through first-principles calculations. Migration mechanisms of different vacancies and interstitials are simulated for these RP antiperovskites. The alkali interstitials are predicted to have lower migration barriers than vacancies, and play a significant role in the ionic conduction of RP antiperovskites. Therefore, the increase of the content of alkali interstitials is a reasonable approach to further improve the ionic conductivity of RP antiperovskites. Our results can serve as a useful guide for developing novel antiperovskite electrolytes of all-solid-state batteries.

Herein, we demonstrate a supramolecular nanochannel formed by intermolecular π stacking of pyridine-pyridazine helical oligomers, wherein alkali ions could be easily recognized and transported. Importantly, this nanochannel also revealed reversible collection and triggered-release behaviors via modulating the folded and unfolded states of helical pyridine-pyridazine oligomers.

CaZrO3:5%molEu3+ and CaZrO3:5%molEu3+/5mol%A+ (A = Li, Na, K) phosphors were synthesized by a solid state reaction. Effects of codoped alkali ions on luminescent properties of CaZrO3:5%molEu3+ was investigated. The XRD and FTIR measurements show that the all of synthesized phosphors have the same phase with pure CaZrO3. The excitation and emission spectra indicate that the codoped alkali ions enhance the Eu3+ emission intensity significantly. Moreover, the decay lifetime is also prolonged by the addition of alkali ions. The enhancements of luminescent properties for CaZrO3:5%molEu3+ can be attributed to the charge compensation and decrease of Ca2+ vacancies induced by the addition of alkali ions.

The specific adsorption of alkali ions, Li + , Na + , K + , and Cs + , in electrolyte solutions on Prussian blue (PB) is investigated by using the three-dimensional (3D) reference interaction site-model (RISM) theory. The results from 3D-RISM show dramatically different adsorption sites between large ions (K + and Cs + ) and small ions (Li + and Na + ). The small ions are adsorbed at the channel entrance sites without the water–ion exchange mechanism. In contrast, the large ions are adsorbed in PB by the water–ion exchange mechanism, and the adsorption site of large ions is located at the center of the cage or at the interstitial site.

A transition between two isomeric clusters involving the change of the main skeleton structure of a well-defined, rigid molecular cluster [(UO2 )24 (O2 )24 (P2 O7 )12 ]48- , {U24 Pp12 }, is achieved by simply introducing proper alkali cations into its dilute aqueous solution. While the unique structural transition can be triggered by introducing any of the Na+ /K+ /Rb+ /Cs+ alkali ions, the two isomers, Li/Na-{U24 Pp12 } and Na/K-{U24 Pp12 }, as typical macroions, can accurately choose among different alkali counter-cations based on their hydrated sizes, and the ion selectivity process clearly showed endothermic features. The preferred K+ and Rb+ ions have suitable sizes to be incorporated into the proper windows on {U24 Pp12 } nanocapsules, as supported by the transition points in both ITC studies and IR measurements.

International audience; Alkali cations are required for the colloidal synthesis of Ln$_2$O$_2$S nanoplates in organic solvent. Based on a thorough experimental analysis using various lanthanides and three alkali ions, we challenge the commonly accepted scenario of partial lanthanide substitution by the alkali, which is supposed to favor the sulfide insertion over the oxide one. Using SAXS-WAXS on aliquots taken from the synthesis medium, we demonstrate the formation of an alkali-stabilized oleate mesophase acting as a template for nanoparticles nucleation and growth. As a consequence, the alkali is not incorporated into the crystalline structure; nanoparticle growth requires only a low alkali concentration that can be readily washed away from the final nanoparticles powder. We expect that similar mesophases may form in other colloidal synthesis using oleates and small cations.

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.

In the present study, using density functional calculations we have investigated a possible mechanism for the structural phase transition of the semiconducting bilayer 2H-MoS2 via lithiation. The results indicate that the addition of lithium to the bilayer 2H-MoS2 transforms the bilayer to a heterostructure of the 2H and 1T structures instead of a complete conversion to the 1T bilayer structure. Therefore, we propose that the desired synthesis of the 1T-MoS2 from the bulk 2H-MoS2 takes place through the hybrid 2H–1T structure. Our finding gives physical insight into the experimentally described microscopic mechanism of the phase transition in MoS2 and enriches the atomic scale understanding of the interaction of MoS2 with the alkali ions and other transition-metal dichalcogenides manifesting a similar phase transition.

International audience; The coloration mechanism of tungsten trioxide (WO3) upon insertion of alkali ions is still under debate after several decades of research. This Letter provides new insights into the reversible insertion and coloration mechanisms of Na+ ions in WO3 thin films sputter-deposited on ITO/glass substrates. A unique model based on a constrained spline approach was developed and applied to draw out ε1+iε2 from spectroscopic ellipsometry data from 0.6 to 4.8 eV whatever the state of the electrochromic active layer, i.e. as-deposited, colored or bleached. It is shown that electrochemically intercalated sodium-tungsten trioxide, NaxWO3 (x=0.1, 0.2, 0.35), exhibits an absorption band centered at ca.1.14 eV in 2 governing the coloration mechanism.

The insertion of alkali metal ions into a prevalent lanthanide-carboxylate coordination motif in heterometallic 3d–4f metal–organic frameworks (MOFs) leads to new MOFs whose structures are sensitively dependent on the size of the alkali ions used and with significantly enhanced effective free crystallographic volume.

A supramolecularly tunable chiral bisphosphine ligand bearing two pyridyl-containing crown ethers, (−) or (+)-Xyl-P16C6-Phos, was fabricated and utilized in the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid esters and Ir-catalyzed asymmetric hydrogenation of quinolines in high yields with excellent enantioselectivities (90–99% ee). Up to a 22% enhancement in enantioselectivity was achieved by the addition of certain amounts of alkali ions (Li+, Na+ or K+), which could be selectively recognized and effectively complexed by the crown ethers on the chiral Xyl-P16C6-Phos.

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.

The neutralization of low energy Na$^+$ and Li$^+$ ions scattered from Au nanoclusters formed by deposition onto oxide surfaces decreases as the cluster size increases. An explanation for this behavior is provided here, which is based on the notion that the atoms in the clusters are not uniformly charged, but that the edge atoms are positively charged while the center atoms are nearly neutral. This leads to upward pointing dipoles at the edge atoms that increase the neutralization probability of alkali ions scattered from those atoms. As the clusters increase in size, the number of edge atoms relative to the number of center atoms decreases, so that that the average neutralization also decreases. Calculations employing this model are compared to experimental data and indicate good agreement if the strengths of the dipoles at the edge atoms are assumed to decrease with cluster size. This model also explains differences in the neutralization probabilities of scattered Na$^+$ and Li$^+$., Comment: 36 pages, 5 figures

We report on an abnormal migration phenomenon of alkali ions in calcium silicate glasses, induced by 250 kHz, 800 nm femtosecond laser irradiation. The diameter of the laser-affected zone is not dependent on the glass-transition temperature of glass samples. Elemental analysis by Electro-Probe Microanalyzer demonstrates that K ions migrate to the periphery of the laser-affected zone, while Cs ions show an opposite tendency in the two alkali ions coexisting glass. The possible mechanism on the observed abnormal phenomenon is discussed.

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.

We examine the insertion of alkali ions into narrow nanotubes of graphite and gold by density functional theory. The surrounding tubes screen the ionic charge very effectively; the resulting image energy compensates well for the loss of solvation. In addition, ion–ion interactions are strongly reduced. These effects are stronger for gold than for graphite tubes. Our results explain at an atomic level, why narrow tubes store charge so effectively Fil: Goduljan, Aleksej. Universitat Ulm; Alemania Fil: Juarez, Maria Fernanda. Universitat Ulm; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Mohammadzadeh, Leila. Universitat Ulm; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Quaino, Paola Monica. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Electroquímica Aplicada e Ingeniería Electroquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina Fil: Santos, Elizabeth del Carmen. Universitat Ulm; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina Fil: Schmickler, Wolfgang. Universitat Ulm; Alemania

Tm 2 O 3 -doped multi-component silicate glasses without alkali ions are prepared using a conventional melt quenching method. The Judd–Ofelt theory is applied to calculate the intensity parameters of the resultant glass. The intensity parameters of silicate glasses without alkali ions are larger than those of silicate glasses with alkali ions. The spontaneous radiation probability of the transition from 3 F 4 to 3 H 6 of glasses without alkali ions is 191.89 s −1 , which is larger than that of glasses with alkali ions. Moreover, the measured lifetime of the 3 F 4 energy level of glasses is larger too. Emission cross section results show a maximum value 3.89×10 −21 cm 2 at 1882 nm. These findings indicate that the glass in this study can be used to realize ~2 μm lasers. The effect of variations in Tm 2 O 2 concentration on the emission properties is also studied. Cross-relaxation and emission intensity enhance with increasing Tm 2 O 3 content. However, the lifetime of the 3 F 4 level decreases because of concentration quenching. The influence of OH groups on the emission properties is also investigated.

This paper presents molecular simulation and experimental investigation for water adsorption on aluminium fumarate (Al-fum) MOFs, alkali ions doped Al-fum MOF and Al-fum + CHA/AFI zeolite composites. The grand canonical Monte Carlo (GCMC) simulations have been carried out to calculate water-adsorption isotherms. Based on simulation results, the Al-fum MOFs are post-synthesized with (i) 5% Li-ions dopants and (ii) 10%, 30% and 50% CHA/AFI zeolites. The pore structure characteristics are performed by N 2 adsorption analysis. The water adsorption isotherms are conducted from 30 °C to 60 °C. The newly synthesized adsorbents show faster kinetics with higher water transfer (Δq) under adsorption-desorption conditions of an adsorption chiller. It is found that (i) 5% Li-ions doped Al-fum-MOF shows the Δq of 0.26 kg/kg, (ii). CHA-zeolite and Al-fum-MOF composite show the Δq of 0.25 kg/kg with 1.6 times faster kinetics, and (iii) AFI-zeolite and Al-fum-MOF composite show the Δq of 0.24 kg/kg with 1.2 times faster kinetics as compared to the original Al-fum-MOF adsorbent.

Author(s): Kim, H; Ishado, Y; Tian, Y; Ceder, G | Abstract: This work compares the intercalation of K, Na, and Li in KxVPO4F (x ∼ 0). The KxVPO4F (x ∼ 0) cathode delivers reversible capacities of ≈90–100 mAh g−1 in K, Na, and Li cells, at an average voltage of ≈4.33 V for K, ≈3.98 V for Na, and ≈3.96 V for Li. This is so far the highest average voltage known for a K-intercalation cathode. The lower voltage of Li insertion compared to Na is attributable to undercoordinated Li ions in the KxVPO4F (x ∼ 0) framework. While the material shows high rate capability for all the alkali ions, Li migration in KxVPO4F (x ∼ 0) is more difficult than with Na and K. This work suggests that a large cavity is not always good for insertion of alkali ions and cathode materials need to be suitably tailored to each intercalating ion species.

The present study concerns the leachability of alkali ions from hardened cement paste in terms of an increase in the pH together with the rate of alkali leaching. To evaluate the influence of mix design on the leaching capacity and rate of alkali, different water-cement ratios (W/C) and binders were used to manufacture paste specimens. The cement paste was made in the form of rectangular bucket where deionised water was subsequently supplied as solvent media. Then the specimen was wrapped in polythene film to avoid contact to atmospheric conditions, which may affect the water chemistry in the bucket. The pH of media was monitored until no further change in the pH value was observed, of which value then used to calculate the leaching capacity and rate. The influence of binder on the pH of solvent is more dominant than that of water to cement ratio: OPC paste produced the highest level of alkali leaching, whilst 30% PFA and 60% GGBS pastes imposed lower level of alkali leaching. After the monitoring of the pH, the inner bucket was ground with an increment of 1.0 mm to measure the leaching influence using the suspension consisting of paste powder and deionised water. It was found that the impact zone for OPC was about 7-8 mm, whilst 30% PFA and 60% GGBS had deeper impact depth of the alkali leaching.

Lanthanide based materials are preferred over other luminescent materials for various applications. Current focus in this area is to exploit the unique luminescence features of lanthanide-based materials for multidisciplinary research and novel applications. Furthermore, efforts are going on to enhance the luminescence of lanthanide ions for better performance. In a broader sense, there are two ways to enhance the luminescence of lanthanide ions. The first is to use a suitable sensitizer, which can absorb excitation energy efficiently, and can transfer it to the lanthanide ions. This method has been known for a long time and is well documented in the literature. The second way is to modify host matrices in such a way that it favors radiative transitions. It is widely reported in the literature that the presence of alkali ions, particularly Li+ ions, in a matrix enhances the luminescence of lanthanide ions significantly. But there are no comprehensive reports available in the literature that summarize how alkali ions help in the luminescence enhancement of lanthanide ions in various host matrices. The prime objective of this review is to highlight various contributing factors that help in the luminescence enhancement of lanthanide ions in the presence of alkali ions.

Eu 3+ -activated double tungstates phosphors MLa(WO 4 ) 2 (M=Li, Na, K) and NaRE(WO 4 ) 2 (RE=Gd, Y, Lu) have been successfully prepared via the conventional solid-state reaction method. The effects of alkali ions and rare earth ions on the luminescence of MLa(WO 4 ) 2 :Eu 3+ and NaRE(WO 4 ) 2 :Eu 3+ were investigated. In MLa(WO 4 ) 2 :Eu 3+ system the emission intensity was found to decrease with increasing the size of alkali ions, and in NaRE(WO 4 ) 2 :Eu 3+ system the emission intensity can be ordered as follows: Lu>Y>Gd. Moreover, under 393 nm light excitation all compounds exhibited strong luminescence of 5 D 0 → 7 F 2 at 615 nm. The excitation spectra implied that these phosphors can absorb not only the emission of near UV-LED chips but also that of blue LED chips. All the results indicate that these phosphors are promising red-emitting phosphors pumped by near-UV or blue light.

A supramolecularly tunable chiral bisphosphine ligand bearing two pyridyl-containing crown ethers, (−) or (+)-Xyl-P16C6-Phos, was fabricated and utilized in the Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid esters and Ir-catalyzed asymmetric hydrogenation of quinolines in high yields with excellent enantioselectivities (90–99% ee). Up to a 22% enhancement in enantioselectivity was achieved by the addition of certain amounts of alkali ions (Li+, Na+ or K+), which could be selectively recognized and effectively complexed by the crown ethers on the chiral Xyl-P16C6-Phos.

Glasses with compositions of 34.5SiO 2 –25AlPO 4 –12.5Al 2 O 3 –12.5B 2 O 3 –15R 2 O–0.5Bi 2 O 3 ( R = Li, Na, K) were synthesized. Characteristic absorption bands of bismuth centered at 500, 700, and 800 nm and broadband near infrared (NIR) emissions peaked at 1100 and 1300 nm were observed. With the change of alkali ion (Li + → Na + → K + ), the intensity of absorption bands at 500 and 800 nm increase, while the intensity of two NIR emissions decrease. The dependence of NIR emission peaked at 1300 nm on the radius of the alkali ion is found to be opposite to that in previous reports, being ascribed to the abnormal reduction of Bi ion in the glasses investigated herein. The results of this work is helpful for understanding the nature of Bi-NIR-emission, and the NIR emission peaked at 1300 nm was proposed to originate from Bi + according to the influence of the alkali ions sizes.

Encapsulated platinum in the form of core–shell Pt@SiO 2 prepared by reverse microemulsion, can be rendered catalytically active for the low-temperature water-gas shift (WGS) reaction by the addition of alkali ions during the synthesis steps or by impregnation of the dried (uncalcined) core–shell materials. We report that positively charged platinum species, embedded throughout the silica shell and stabilized by the alkali ions are the active sites for the WGS reaction. Water dissociation and hydroxyl regeneration take place on the Na-promoted Pt–O x sites. It is shown by cyclic CO-TPR experiments with intermittent ambient rehydration that the activity remains constant, and the onset temperature of the reaction is the same, ∼150 °C, with cycling. The apparent activation energies for the WGS reaction in realistic fuel gas mixtures over the various encapsulated Pt-based catalysts evaluated here and those on other supports are all in the same range, 70 ± 5 kJ/mol. Hence any difference in the reaction rates between the open- and encapsulated-Pt catalysts is attributed to their different number of active sites accessible to the reactants. The Pt-Na@SiO 2 catalyst structures show remarkable stability with time-on-stream at 350 °C.

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+).

This Account provides perspective on the evolution of the rechargeable battery and summarizes innovations in the development of these devices. Initially, I describe the components of a conventional rechargeable battery along with the engineering parameters that define the figures of merit for a single cell. In 1967, researchers discovered fast Na(+) conduction at 300 K in Na β,β''-alumina. Since then battery technology has evolved from a strongly acidic or alkaline aqueous electrolyte with protons as the working ion to an organic liquid-carbonate electrolyte with Li(+) as the working ion in a Li-ion battery. The invention of the sodium-sulfur and Zebra batteries stimulated consideration of framework structures as crystalline hosts for mobile guest alkali ions, and the jump in oil prices in the early 1970s prompted researchers to consider alternative room-temperature batteries with aprotic liquid electrolytes. With the existence of Li primary cells and ongoing research on the chemistry of reversible Li intercalation into layered chalcogenides, industry invested in the production of a Li/TiS2 rechargeable cell. However, on repeated recharge, dendrites grew across the electrolyte from the anode to the cathode, leading to dangerous short-circuits in the cell in the presence of the flammable organic liquid electrolyte. Because lowering the voltage of the anode would prevent cells with layered-chalcogenide cathodes from competing with cells that had an aqueous electrolyte, researchers quickly abandoned this effort. However, once it was realized that an oxide cathode could offer a larger voltage versus lithium, researchers considered the extraction of Li from the layered LiMO2 oxides with M = Co or Ni. These oxide cathodes were fabricated in a discharged state, and battery manufacturers could not conceive of assembling a cell with a discharged cathode. Meanwhile, exploration of Li intercalation into graphite showed that reversible Li insertion into carbon occurred without dendrite formation. The SONY corporation used the LiCoO2/carbon battery to power their initial cellular telephone and launched the wireless revolution. As researchers developed 3D transition-metal hosts, manufacturers introduced spinel and olivine hosts in the Lix[Mn2]O4 and LiFe(PO4) cathodes. However, current Li-ion batteries fall short of the desired specifications for electric-powered automobiles and the storage of electrical energy generated by wind and solar power. These demands are stimulating new strategies for electrochemical cells that can safely and affordably meet those challenges.

The target of this investigation is to characterize by a recently developed methodology, the main features of the first solvation shells of alkaline ions in nonpolar environments due to aromatic rings, which is of crucial relevance to understand the selectivity of several biochemical phenomena. We employ an evolutionary algorithm to obtain putative global minima of clusters formed with alkali-ions (M(+)) solvated with n benzene (Bz) molecules, i.e., M(+)-(Bz)(n). The global intermolecular interaction has been decomposed in Bz-Bz and in M(+)-Bz contributions, using a potential model based on different decompositions of the molecular polarizability of benzene. Specifically, we have studied the microsolvation of Na(+), K(+), and Cs(+) with benzene molecules. Microsolvation clusters up to n = 21 benzene molecules are involved in this work and the achieved global minimum structures are reported and discussed in detail. We observe that the number of benzene molecules allocated in the first solvation shell increases with the size of the cation, showing three molecules for Na(+) and four for both K(+) and Cs(+). The structure of this solvation shell keeps approximately unchanged as more benzene molecules are added to the cluster, which is independent of the ion. Particularly stable structures, so-called "magic numbers", arise for various nuclearities of the three alkali-ions. Strong "magic numbers" appear at n = 2, 3, and 4 for Na(+), K(+), and Cs(+), respectively. In addition, another set of weaker "magic numbers" (three per alkali-ion) are reported for larger nuclearities.

The ion-exchanger Mg0.5Ti0.5PO4 of spinel type was prepared by means of the solid state reaction crystallization method, and was acid-modified. This inorganic ion-exchanger(Mg0.5Ti0.5PO4) has the saturation capacity of exchange for Li+ higher than those for other alkali ions, the saturation capacity of exchange for Li+ reaches to 5.4mmol/g, MgTi-750(H) has a higher selectivity of ion exchange for Li+ than for other alkali ions.

It was found that destabilization of the low, medium and high concentrations of К + in seminal fluid, spermatozoa and sperm is related to the hypo- and hyperfunctions of genitals’ generative tissues. The unmatched К + concentrations and constant ratios of Са 2 + , К + and Na + under presence of normofunction and destabilization of their contents and ratios in seminal plasma and spermatozoa under hypo- and hyperfunction indicate that the features of ion homeostasis in sperm are programmed at the genetic level.

Chemically strengthened glasses are of increasing technological importance for personal electronic devices, tablet computers, and a variety of other applications. However, there are many unexplained phenomena associated with the physics of the ion exchange process used for strengthening. One of the most puzzling of these is the anomalous behavior of the network dilation coefficient, i.e., the parameter governing the amount of linear strain of the glass per unit of alkali ions exchanged, which is inevitably a factor of 2–4 higher for as-melted glasses as compared to chemically strengthened versions of the same glass compositions prepared via ion exchange. In this paper, we investigate the atomistic origin of this discrepancy between as-melted and ion-exchanged glasses based on molecular dynamics simulations of a series of alkali tetrasilicate glasses, viz., x Na 2 O·(20 − x )K 2 O·80SiO 2 (mol%). The network dilation coefficient of the ion-exchanged glasses is dependent on composition and ranges from 30% to 54% of the ideal value obtained from the as-melted glasses. This anomalous behavior of the network dilation coefficient is explained in terms of different local environments between sodium and potassium sites in the glass network and a two-stage relaxation process of the local potassium environment after ion exchange.

The ion-exchanger Li0.8Zn1.1PO4of spinel type was prepared by means of the solid state reaction crystallization method, and was acid-modified. This inorganic ion-exchanger(Li0.8Zn1.1PO4) has the saturation capacity of exchange for Li+higher than those for other alkali ions, the saturation capacity of exchange for Li+reaches to 3.0mmol/g.

The polarizabilities of the alkali and halogen ions are calculated by means of a new method. It is proved that the polarizabilities of the mononuclear ions are constant and not (as Fajans and Joos had to assume) dependent on the surroundings. The values obtained for the alkali ions are in good agreement with those calculated by other writers; the values for the halogen ions are lower than those given by Fajans and Joos, but it is shown that the method they adopted in calculating them was incorrect.

Two novel 3D extended polyoxotantalates/niobates solid complexes: [Na 6 (H 2 O) 13 )][Li(H 2 O)(H 3 O)][(Ta 6 O 19 )] ( 1 ) and [Na 6 (H 2 O) 13 ][Li(H 2 O) 2 ][H(Nb 6 O 19 )] ( 2 ) have been assembled successfully based on double alkali metal ions (Li + and Na + ) and Lindqvist clusters ([Ta 6 O 19 ] 8− /[Nb 6 O 19 ] 8− ) under aqueous solution. Both compounds have been characterized by IR, TG analysis and single-crystal X-ray diffraction. It is worth noting that Li and Na ions, different kinds of alkali ions, are first observed coexisting in two resultant solid crystal structures of polyoxotantalates/niobates. Further photocatalytic investigations show that methylene blue (MB) dye solution can be degraded by UV irradiation effectively in the presence of [Nb 6 O 19 ] 8− /[Ta 6 O 19 ] 8− . The experiments indicate that the degradation efficiency depends on pH value, irradiation time, initial MB concentration and different types of POM anions etc.

Diffusion of alkaline-earth ions in mixed cation glasses of the composition xA2O•(3-x)MO•4SiO2 (x = 0.0, 0.1, 0.3, 0.4 and 1.0; A = Na, K; M = Ca, Ba) was investigated by means of the radiotracer diffusion technique below the respective glass transition temperatures. The mobility of alkaline-earth ions increases with the alkali content in all analyzed glass systems with no decrease in the diffusion activation energy, but a raise in the pre-exponential factor. A distinct dependency of the activation energy of the alkaline-earth ions on the type and content of the alkali ions in the glass is observed. Additional experiments with thin glass films derived by the sol-gel technique reveal an analogous diffusion behaviour. This demonstrates that the dynamic of alkaline-earth ions in mixed cation glasses does not depend on the way of glass preparation.

Alkali ions were co-precipitated with titanium hydroxide gels. When Ti(SO4)2 solution was added to KOH solution with K:Ti=10:1 (in molar ratio), the potassium remains in the precipitated gel, in spite of several times of washing. Excess amount of alkali and pH>9 were the essential conditions for the co-precipitation. Similar results were obtained for the other alkali elements; Li and Na. Nano-sized particles of K2O-6TiO2, Li2O-TiO2 and Na2O-3TiO2 with 20-30 nm in size were respectively obtained by heating the precipitates at 500 or 600°C.In addition, the thin films of alkali titanates were obtained on Si substrate by dripping Ti(SO4)2 solution and MOH solution for 30-60 min.

Atomic scale molecular dynamics simulation is used to investigate how alkali concentrations in glass adjacent to interfaces with crystal surfaces, might differ from those within the interior of a bulk glass. A sodium, lithium alkali-borosilicate glass and its interfaces with the (1 0 0) and (1 1 0) surfaces of MgO, CaO, and SrO are considered. These six interfaces were formed by melt-quenching the glass in the presence of the crystal surface, providing glass alkali ions with the opportunity to either migrate towards or away from the crystal surface. The resulting alkali contents adjacent to the interface are found to differ depending on crystal composition and surface orientation.

An overview of the common methods for the determination of the alkali metals is given. These are drawn from all of the three principle branches of quantitative analysis and consist mainly of optical atomic spectrometric methods, ion-selective electrodes, and the separation methods of ion-chromatography and capillary electrophoresis. Their main characteristics and performance parameters are discussed. Important specific applications are also examined, namely clinical analysis, single cell analysis, the analysis of soil samples and hydroponic nutrient solutions, as well as the detection of the radioactive 137Cs isotope.

A series of 5-dialkyl(aryl)aminomethyl-8-hydroxyquinoline dansylates were synthesized and their fluoroionophoric properties toward representative alkali ions, alkaline earth ions and transition metal ions were investigated. Among the selected ions, Fe3+ caused considerable quenching of the fluorescence, while Cr3+ caused quenching to some extent. The absence of any significant fluorescence quenching effects of the other ions examined, especially Fe2+, renders these compounds highly useful Fe3+-selective fluorescent sensors.

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.

To improve battery technology, cathodes based on intercalated Na${}^{+}$ rather than Li${}^{+}$ are closely studied, as sodium is much cheaper, and sodium-ion batteries can be fully drained yet still remain viable. Unfortunately, during cycling Na cathode materials present reversible vacancy-ordering phase transformations that can reduce performance. The authors use high-throughput calculations to study the nature of these transformations in all known Na${}_{x}$$M$O${}_{2}$ layered compounds, and their findings may also apply to systems with other alkali ions.