KI Solutions Research Articles

Monophotonic ionization of poly[A,G] and DNA in alkaline aqueous solution by 248 nm laser light: Formation of guanyl radical

Photoionization of 2′-deoxyguanosine 5′-monophosphoric acid (dGMP), polyadenylic-guanylic acid (poly[A,G]) and single-stranded DNA (ssDNA) in alkaline aqueous solution by 248 nm laser pulses was investigated. Unlike the reactions in neutral solution, the ionization at pH > 9 was found to be monophotonic. The transition from mono- to biphotonic ionization with increasing pH was shown to be associated with deprotonation of guanine and the corresponding decrease of ionization potential. In the case of Poly[A,G] and ssDNA, photoionization occurs at deprotonated guanine moieties, thus giving guanyl radicals. The quantum yields of formation of hydrated electrons ( Φ e−) were determined at room temperature with KI solutions used as a reference.

A Channel-Forming Polyiodide Network in [Cu(dafone)3]I12. A Tris Chelate of Dafone and a New Planar Structure for the I122- Ion (Dafone = 4,5-Diazafluoren-9-one)

Treatment of an aqueous solution of copper(II) acetate, dafone, and KI with I2 in CH2Cl2 leads to the formation of Cu(dafone)3I12 (1). 1 crystallizes in the orthorhombic system, space group Pbcn, with a = 22.902(4) Å, b = 11.104(2) Å, c = 18.992(7) Å, and Z = 4. Cu(dafone)32+ is the first tris chelate of dafone and is stabilized by a channel-forming network of planar I122- ions. Temperature dependence of the EPR spectrum indicates fluxionality of the cation.

Effects of ultrasound on the electrolytic conductivity of simple halide salts

Ultrasound irradiation of aqueous solutions of KCl, LiCl and KI causes an increase in their conductivity (measured with AC at 1000 Hz), which disappear as soon as ultrasound irradiation is switched off. The phenomenon is explained in terms of collapse of cavitational bubbles created by ultrasound in the solution with release of energy under the form of shock waves and heat.

Cathodic Generation and Oxidation of Lead Zintl Ion Pb94- in Potassium Iodide Solutions in Liquid Ammonia

The electrochemical reduction of lead and oxidation reaction of the resulting Pb94- Zintl ions have been studied in 0.1 and 1.0 M KI solutions in liquid ammonia at −70 °C. The reduction process is a complicated multistep reaction. Under certain conditions the oxidation of Pb94- occurs as a simple, electrochemically irreversible reaction for which the limiting current is diffusion controlled. The diffusion coefficient of Pb94- was determined from a combination of chronoamperometry measurements on a 25 μm Pt ultramicroelectrode and chronocoulometry measurements on a 1 mm Pb disk electrode. The chronocoulometric method for the determination of Pb94- determination is presented and used to determine the actual Pb94- concentrations in the electrochemical cell. Side effects, which accompany the reduction and oxidation reactions, have also been studied and the ways to avoid them presented.

Continuous variation of iodine adlattices on Ag(111) electrodes: in situ STM and ex situ LEED studies

The structure of the iodine adlattice formed on Ag(111) in aqueous solutions containing iodide ions has been determined as a function of the electrode potential by in situ scanning tunneling microscopy (STM) and ex situ low energy electron diffraction (LEED). In KI solutions buffered with KF-KOH at pH 10, continuous compression of the iodine adlattice from square (√3 × √3R-30°), via (√3 qR β° × √3R-30°), to (√3 × √3)R30° was observed as the electrode potential was increased; this was then followed by an abrupt phase transition into a rotated hexagonal (√3 r × √3 r)R(30° + α°) phase. Coadsorption of K was observed by Auger electron spectroscopy (AES) at potentials negative of that for the phase transition. In acid solutions (0.1mM HI) the continuous compression from (√3 × √3)R30°, via c( p × √3R-30°), into (√3 r × √3 r)R(30° + α°) was observed. The Moiré pattern observed for the (√3 r × √3 r)R(30° + α°) adlattice, as well as the flatness of other adlattices observed in STM images, is explained in terms of lattice registry on the basis of a “hard ball contact model”.

Uptake of NO 3 on KI solutions: rate coefficient for the NO 3 + I − reaction and gas-phase diffusion coefficients for NO 3

Uptake of NO 3 by KI solutions was measured at 273 ± 1 K using a wetted-wall flow tube to determine the rate coefficient for the NO 3(aq) + I − reaction to be k = (4.6 ± 0.5) × 10 9M −1 s −1. It is suggested that the reaction of NO 3 with halide ions proceeds by electron transfer. Use of high concentration of KI enabled determination of the gas-phase diffusion coefficients of NO 3 in H 2O vapor, He, N 2 and O 2 to be, respectively, D NO 3 − H 2O = 120 ± 15, D NO 3 − He = 345 ± 25 D NO 3 − N 2 = 80 ± 15 and D NO 3 − O 2 = 80 ± 15 Torr cm 2s −1. These coefficients agree well with calculated values.

Raman Study of the Influence of KCl and KI on Polarization Contours of OH Stretching Band of Water

Changes in the isotropic and anisotropic contours of H2O stretching bands in solutions of KCl and KI were studied. The change of the isotropic contour of the OH stretching band in aqueous KCl solutions involves two parameters: the non-coincidence parameter, Δν and the Fermi resonance coupling constant, W. For KI solutions an additional change is caused by an increase in the distance between unperturbed ν1 and 2ν2. The non-coincidence parameter Δν decreases and changes its sign for the molar ratio of about 0.1 and the Fermi resonance constant W also decreases, when the electrolyte concentration increases.

Ordered Binary Ionic Adlayers on a Au(110) Electrode: Coadsorption of Alkali Metal Cations with Iodide Anions

Alkali metal cations are found, using X-ray diffraction, to coadsorb with iodide ions on a Au(110) electrode surface at potentials positive of the onset of the Au(110) reconstruction and negative of the formation of iodine monolayers. The adlayer exhibits a c(2 × p) in-plane diffraction pattern with p depending on the cation species and concentration. For the CsI adlayer, p = 4/3 independent of potential and the Cs+−I- spacing is close to that in bulk CsI. In KI, NaI, and LiI solutions, p increases with increasing potential. As a result, the coverages of both the cation and anion species decrease with increasing potential. For the anion, the slope of the potential-dependent coverage is opposite of its behavior in the absence of cation coadsorption. This unusual behavior is attributed to the net positive charge within the adlayer due to the partial discharge of chemisorbed iodides. Details of the diffraction features suggest the existence of antiphase domains and relaxation at domain walls.

Osmotic regulation of cytokine synthesis in vitro.

These studies were undertaken to investigate the therapeutic mechanism of saturated solutions of KI, used to treat infectious and inflammatory diseases. The addition of 12-50 mM KI to cultured human peripheral blood mononuclear cells resulted in 319-395 mosM final solute concentration and induced interleukin (IL)-8 synthesis. Maximal IL-8 production was seen when 40 mM salt was added (375 mosM) and was equal to IL-8 induced by endotoxin or IL-1 alpha. However, there was no induction of IL-1 alpha, IL-1 beta, or tumor necrosis factor to account for the synthesis of IL-8; the effect of KI was not due to contaminating endotoxins. Hyperosmolar NaCl also induced IL-8 and increased steady-state levels of IL-8 mRNA similar to those induced by IL-1 alpha. IL-8 gene expression was elevated for 96 hr in peripheral blood mononuclear cells incubated with hyperosmolar NaCl. In human THP-1 macrophagic cells, osmotic stimulation with KI, NaI, or NaCl also induced IL-8 production. IL-1 signal transduction includes the phosphorylation of the p38 mitogen-activated protein kinase that is observed following osmotic stress. Using specific blockade of this kinase, a dose-response inhibition of hyperosmolar NaCl-induced IL-8 synthesis was observed, similar to that in cells stimulated with IL-1. Thus, these studies suggest that IL-1 and osmotic shock utilize the same mitogen-activated protein kinase for signal transduction and IL-8 synthesis.

Mass spectrometric calibration of an atomizer/nebulizer for doping flames or discharge plasmas

An atomizer or nebulizer provides a very versatile means of doping a flame or discharge plasma with a small amount (typically < 10 −5 mole fraction) of an additive. A wide variety of substances (e.g. salts of metallic halides) can be introduced as an aerosol by spraying an aqueous solution into the system, but the additive concentration must be calibrated. Optical calibration methods are difficult, and measurements of the atomizer effluent or depletion are unreliable. A conceptually simple and general method has been developed for calibration of the atomizer concentration in situ when the system can be sampled by a mass spectrometer. A solution is sprayed with the atomizer, which produces a distinctive type of ions in the system, either positive or negative. The same type of ions is then produced by introducing the vapour of a volatile substance of known vapour pressure using a small flow of a carrier gas through a gas saturator. By varying the saturator flow rate, the ion signal from the saturator is then matched to the ion signal from the atomizer. As the concentration introduced by the saturator is known, the calibration factor for the atomizer can be determined. An example is worked out for a premixed H 2O 2Ar flame having essentially no natural ionization, which is doped with an atomizer spraying a 0.05 M aqueous solution of KI to produce K + and I −. Then, with the atomizer spraying a 0.05 M KNO 3 solution, the I − atomizer signal is matched by an I − signal produced when C 6H 5I vapour is introduced by a tiny flow rate of argon through the saturator. If the ion chemistry is straightforward, the mass spectrometer could be replaced by a total ion collector. The method should be applicable to a variety of flames and also to discharge plasmas.

Remediation of a soil polluted by mercury with acidic potassium iodide

A new chemical process has been studied to clean up a mercury-polluted soil by using acidic potassium iodide (KI) solution. A highly contaminated soil (max. 47.1 mg Hg/g) was used as a model sample. Evaluation was made on the effects of aqua regia, HCl, NaOH, Na-EDTA and KI solutions to extract mercury from polluted soil in a batch process. A mixture of 100 m M KI + 50 m M HCl (pH = 1.5) was found to be most effective. The acidic KI solution was passed through a column packed with 9.8 g polluted soil at a flow rate of 25 ml/h. After 15 fraction volumes, the mercury content decreased from 113.5 to 26.2 mg. The leachate from the column test containing HgI 2− 4 was treated with granular activated carbon.

Novel Anion Dependence of Induced Cation Transport in Malaria-infected Erythrocytes

Following invasion by the malaria parasite there appear in the parasitized erythrocyte new ("induced") permeation pathways that mediate the transport of a wide variety of small solutes. Although anion-selective, these pathways have a significant cation permeability and cause a substantial increase in the basal leak of cations into and out of the infected cell. In this study of human erythrocytes infected in vitro with Plasmodium falciparum it was shown that the transport of monovalent cations (Rb+ and choline), but not that of a nonelectrolyte (sorbitol) or a monovalent anion (lactate), via the malaria-induced pathways is strongly dependent on the nature of the anion in the suspending medium. Substitution of NO3- for Cl- resulted in a 4-6-fold increase in the unidirectional influx and efflux of Rb+, and a 2-3-fold increase in the influx of choline via the induced pathways. By contrast, replacement of Cl- with NO3- caused a slight (although not significant) decrease in the malaria-induced influx of sorbitol and lactate. Hemolysis experiments with a range of K+ salts revealed that the net influx of K+ into infected cells showed the same novel anion dependence as seen for the unidirectional flux of Rb+ and choline, with hemolysis occurring much faster in iso-osmotic KNO3 and KSCN solutions than in KCl, KBr, or KI solutions. Hemolysis in the corresponding Na+ salt solutions was very much slower, consistent with the induced pathways being selective for K+ over Na+, and raising the possibility that the efflux of cell K+ via these pathways may play a role in host cell volume regulation. A number of models that would account for the anion dependence of malaria-induced cation transport are considered.

Changes in Amylose and Total Starch Content in `Fuji' Apples during Maturation

Total starch and amylose (AM) concentration and a starch index (SI) were determined in `Fuji' apple (Malus domestica Borkh.) fruit from weekly harvests in 1990 and 1991. As apples matured, SI scores increased and total starch and amylose content decreased. The percentage of AM in the total starch decreased as the apples matured. Because KI solutions interact efficiently only with AM, the SI is less reliable in representing total starch during later stages of `Fuji' apple maturation.

Anomalous diffusion of iodine ions into polypropylene implanted with F+ and I+ ions

AbstractThe diffusion of K and I atoms from 5 M water solution of KI into polypropylene implanted with 150 keV F+ and I+ was studied at boiling temperature. Standard Rutherford back scattering (RSB) technique was used for the determination of concentration depth profiles of diffused atoms. It was found that the I and K atoms penetrate the polymer surface layer affected by ion implantation and they are captured by trapping centers produced by electronic energy losses of implanted ions. The uptake of K atoms is several times higher than that of I atoms, and the relative K concentration exceeds the KI stoichiometric value. © 1995 John Wiley &amp; Sons, Inc.

Electrospray mass spectrometry using potassium iodide in aprotic organic solvents for the ion formation by cation attachment

A solution of KI in DMF-THF (1:1) was used as aprotic solvent in electrospray ionization mass spectrometry (ESI-MS) of neutral organic compounds. The potassium ions brought about the ionization. The new method was tested with poly(ethylene glycol) and applied to compounds unusual for ESI-MS.

Thermal decomposition of caesium—potassium iodothiocyanatobismuthates(III)

New double complex bismuth salts of the general formula Cs 2K[Bi(SCN) x I 6- x ] where x = 1, 2 and Cs 2K[Bi 2(SCN) y I 9- y ] where y=5, 6, 7 have been obtained by dissolving Cs[Bi(SCN) 4] in KI solutions of various concentrations. The mechanism of the thermal decomposition of these compounds has been determined on the basis of thermal curves, chemical and diffractometric analyses of the solid pyrolysis products. The decomposition was found to proceed in three stages.

Modelling of a batch sonochemical reactor

Ultrasonication of aqueous KI solution is known to yield I 2 due to reaction of iodide ions with hydroxyl radicals, which in turn are generated due to cavitation. Based on this conceptual framework, a model has been developed to predict the rate of iodine formation for KI solutions of various concentrations under different gas atmospheres. The model follows the growth and collapse of a gas—vapour cavity using the Rayleigh—Plesset bubble dynamics equation. The bubble is assumed to behave isothermally during its growth phase and a part of the collapse phase. Thereafter it is assumed to collapse adiabatically, yielding high temperatures and pressures. Thermodynamic equilibrium is assumed in the bubble at the end of collapse phase. The contents of the bubble are assumed to mix with the liquid, and the reactor contents are assumed to be well stirred. The model has been verified by conducting experiments with KI solutions of different concentrations and using different gas atmospheres. The model not only explains these results but also the existence of a maximum when ArO 2 mixtures of different compositions are employed.

USE OF POTASSIUM IODIDE AS A CHEMICAL ACTINOMETER

Aqueous solutions of KI were examined for use as chemical actinometers to measure 254 nm (germicidal) radiation. Irradiation results in electron ejection from iodide such that aqueous electrons and iodine atoms are formed. In the presence of N2O, an electron scavenger, recombination of these two reactive species is eliminated and stoichiometric formation of triiodide occurs. The absorbance increase due to triiodide was followed and the quantum yield determined using either a radiometer or ferrioxalate actinometry to estimate the amount of energy absorbed by the KI solution. The quantum yield (phi) at 25 degrees C was determined to be 0.26 using radiometry, and 0.224-0.233 using actinometry, depending on the radiation conditions. The following expression was used to measure the incident fluence rate for 254 radiation at a given temperature T for irradiation over a time interval delta t (s) [formula: see text] At temperatures other than 25 degrees C, the temperature dependence of the quantum yield (0.004/degrees C) is taken into account by the term shown in the denominator. Because KI remains relatively blind to longer wavelengths such as those found in normal room light, measurements can be made in the presence of room light without having to work in a darkened room.

Effect of adsorbed salts on the conductivity of nylon 66

Films of nylon 66 were immersed in saturated solutions of LiCl, NaBr, NaI, KI, CuCl 2 , and ZnCl 2 until the weight no longer increased. After the films were dried, dielectric data were taken at frequencies from 10 2 to 10 5 Hz and temperatures up to 200°C. The high-temperature behavior is dominated by conductivity which is increased up to 150-fold by the presence of the absorbed salts. The largest effects were obtained with CuCl 2 even though the amount absorbed is less than in the case of ZnCl 2 . It is suggested that the strong Cu-N interaction facilitates the liberation of amide protons for conduction

Heat capacities and densities of electrolyte mixtures in aqueous solution — Application to the determination of apparent molar heat capacities and volumes for potassium triiodide and dioxoneptunium(V) perchlorate

Apparent molar heat capacities for KI 3(aq) were determined from flow-microcalorimetric measurements of KI(aq) solutions containing dissolved iodine. From these, the conventional partial molar heat capacity C ∞ p,2 ( I − 3, maq, 298.15 K) = 156±40 JK −1 mol −1 is estimated. Also, densities and heat capacities for NpO 2 ClO 4( aq) + HClO 4( aq) mixtures were measured. Preliminary values are reported for apparent molar heat capacities (at 298.15 K) and volumes (at 296.02 K) for NpO 2ClO 4(aq). From these, values for the ionic apparent molar volume and heat capacity of NpO + 2(aq) are calculated. Analysis of the data is done assuming deviations from Young's rule are small for the apparent molar heat capacities of simple electrolytes. This is shown to be true for aqueous solutions of NaCl( aq) + KBr( aq) (298.15 K and 348.15 K) and NaCl( aq) + MgCl 2( aq) (348.15 K).