CaI2 Research Articles

Scintillation characteristics of thin-film calcium iodide crystal x-ray detectors

A container design for fabricating low-energy x-ray scintillation detectors is proposed. CaI2 and CaI2:Eu crystal detectors are fabricated and their characteristics are investigated. It is shown that on account of their layered structure, perfect cleavage, and high light output, calcium iodide scintillators can be used to fabricate thin-film detectors for long-wavelength x rays.

Rapid down regulation of Ca 2+ signals induced by endothelin-1 in a human bronchial epithelial cell line

Ca 2+ transients evoked by endothelin-1 (ET-1) were measured in single cells of an immortalized human tracheal epithelial cell line using Fura-2. ET-induced Ca 2+ transients were compared to signals evoked via established phospholipase-C linked receptors (H 1 histamine; P 2y purinergic, ATP). Saturating concentrations of histamine (100 μM) and ATP (10 μM) caused Ca 2+ transients of identical amplitude, whereas a saturating concentration of ET-1 (10 nM) on average resulted in a slightly smaller change in fluorescence ratio (80 ± 27%). H 1 and PZY induced Ca 2+ signals caused by brief (10–30 s) application of the agonists were highly reproducible. No desensitization to these ligands was observed, if between two exposures cells were superfused with agonist-free solution for ≥ 200 s. A single exposure to ET-1 (10 nM) for ≥ 6 s reduced sensitivity of the cell to a second exposure to ET-1. On average, the signal upon a second application of 10 nM ET-1 had an amplitude of 30% of the first ET-1 induced signal in that cell. After two 10 s exposures to the peptide, less than 10% of the initial amplitude was measured. This desensitization did not affect responsiveness to histamine or ATP. No recovery from desensitization to ET-1 was observed for 12 h after a single brief treatment with the peptide. Thereafter, responsiveness to ET-1 re-appeared with a half time of about 5 h and was complete by about 20 h. Ca 2+ signals to all three agonists were absent in thapsigargin treated cells. Their amplitude was not affected by superfusion of the cells with Ca i2+-free solution. Under conditions of store-depletion either by ET-1 or by thapsigargin, a change from Ca 2+-free to Ca 2+-containing solution induced a slow rise in [Ca 2+ i, suggesting the existence of a capacitative Ca 2+ entry pathway. ET-receptors most likely of the ET A subtype are subject to a novel type of desensitization — at least with regard to Ca 2+ signalling — which might reflect a signal transduction mechanism specific to ET receptors.

Two distinct Na + currents control cytosolic Ca i2+ pulsing in Xenopus laevis pituitary melanotrophs

Studies with the Na + channel blocker tetrodotoxin (TTx) on Ca 2+-dependent hormone release by mammalian and amphibian pituitary melanotrophs have suggested that the Na+ spikes these cells generate are not responsible for triggering Ca 2+ influx and consequently secretion. In contrast, we found in Xenopus laevis melanotrophs that the spontaneously occurring elevations in cytosolic free Ca 2+ concentration (‘Ca 2+ pulses’) were dependent on the presence of extracellular Na + and sensitive to TTx and the Na + channel activator, veratridine. However, an inhibitory effect of TTx could only be demonstrated when the extracellular Na + concentration was lowered to near-threshold levels. In voltage-clamp experiments, two distinct Na + currents were recorded, one sensitive to TTx and the other insensitive to TTx but blocked by micromolar concentrations of Cd 2+. Together they appeared to control action potential activity and spontaneous Ca 2+ pulsing. These data strongly suggest that Na + action potentials do regulate cytosolic free Ca 2+ concentration in melanotrophs.

Effect of Hg 2+ on cytosolic Ca 2+ (Ca i2+) in hepatocytes isolated from the little sakte Raja erinacea: [formula omitted], Kavita Mariwalla, Nazzareno Ballatori and James L. Boyer. Mt. Desert Island Biol. Laboratory, Salsbury Cove, ME 04672, Dept. of Environ. Med., Univ. of Rochester School of Med., Rochester, NY 14642, and Liver Center, Yale Univ. School of Med., New

Effect of Hg 2+ on cytosolic Ca 2+ (Ca i2+) in hepatocytes isolated from the little sakte Raja erinacea: [formula omitted], Kavita Mariwalla, Nazzareno Ballatori and James L. Boyer. Mt. Desert Island Biol. Laboratory, Salsbury Cove, ME 04672, Dept. of Environ. Med., Univ. of Rochester School of Med., Rochester, NY 14642, and Liver Center, Yale Univ. School of Med., New

A mutant toxin of Vibrio parahaemolyticus thermostable direct hemolysin which has lost hemolytic activity but retains ability to bind to erythrocytes

A mutant toxin, R7, of thermostable direct hemolysin (TDH) with a single amino acid substitution at glycine 62 was analyzed. The hemolytic activity of R7 decreased to less than 1/1,000 of that of wild-type TDH, and its mouse lethality was undetectable. This mutant toxin, however, showed a marked inhibitory effect on hemolysis by wild-type TDH. Enzyme immunoassay and flow cytometric analysis demonstrated that R7 retained approximately 50% of the ability to bind to erythrocytes compared with that of wild-type TDH, suggesting that its inhibition of hemolysis by wild-type TDH might be due to blocking the binding sites on the erythrocyte membrane. Wild-type TDH affected the erythrocyte membrane by causing an influx of calcium and propidium iodide, while R7 showed no detectable effects of these kinds. These results suggest that hemolysis by TDH consists of at least two steps, binding and postbinding, and that R7 is likely to be a postbinding activity-deficient mutant toxin of TDH.

In squid axons the Ca i2+ regulatory site of the Na + /Ca 2+ exchanger is drastically modified by sulfhydryl blocking agents. Evidences that intracellular Ca i2+ regulatory and transport sites are different

We have explored the effect of the sulfhydryl group blocker p-chloromercuryphenylsulfonic acid (PCMBS) on Ca 2+ and Na + interactions with the Na − /Ca 2+ exchanger in squid giant nerve fibers. Steady-state Na o +-dependent Ca 2+ efflux (forward) and Na i +-dependent Ca 2+ influx (reverse) were measured in internally dialyzed, voltage clamped squid axons. External PCMBS (0.5 mM, for 25–35 min) has no effect on the activation of Ca 2+ efflux by Na o +, and Ca o 2+ or on the activatory external monovalent cation site. In contrast, when applied internally it drastically reduces the affinity of the Na + /Ca 2+ exchanger towards Ca i 2+ ions without affecting its maximal rate of transport; in the presence of MgATP the K 0.5 for Ca i 2+ activation of forward Na + /Ca 2+ exchange increases from 1.5 μM to 95 μM; likewise the apparent affinity of the Ca i 2+ stimulation of the reversal exchange decreases 100-fold. Interestingly, no effect of PCMBS was found on the interactions between Na i + and Ca i 2+ ions with the internal transport site(s) (inhibition of Na o + and Ca o 2+-dependent Ca 2+ efflux by Na i +). On the other hand, Na i + ions do not modify the interactions of Ca i 2+ with that site. Two important characteristics of the Ca i 2+ regulatory site are uncover in this work: (i) sulfhydryl groups are important in maintaining the integrity of the Ca 2+ binding domain of the Ca i 2+ regulatory site and (ii) Na i + and Ca i 2+ regulatory, or Na i + and Ca i 2+ transporting sites, are different entities.

Functionalization of halogenated polystyrene resins utilizing highly reactive calcium

Polymeric organocalcium reagents were prepared via the oxidative addition of highly reactive calcium, prepared from the lithium biphenylide reduction of calcium iodide, to cross-linkedp-bromopolystyrene,p-chloropolystyrene,p-fluoropolystyrene, and chloromethylated polystyrene. These organocalcium reagents react with a variety of electrophiles to yield functionalized polymers.

Infrared spectroscopic study of acetonitrile in aqueous inorganic salt solutions and comparison with related polyacrylonitrile solutions

The infrared spectra of acetonitrile (CH 3CN) have been obtained in the ν(CN) stretching region for the pure liquid, in water and in aqueous salt solutions of sodium thiocyanate, sodium iodide, lithium iodide calcium iodide and zinc chloride. The CN absorption bands of acetonitrile in aqueous inorganic salt solutions were very similar in character to those found in aqueous solutions of poly(acrylonitrile-co-vinyl acetate) containing inorganic salts. The effect of the salt solutions on the ν(CN) stretching absorptions can be divided into three types: (i) solutions containing NaSCN and NaI which cause a shift in the ν(CN) absorption band relative to that in pure CH 3CN with δν=+6 cm −1, (ii) solutions containing ZnCl 2 which give rise to two absorption bands with shifts of δν=+6 and +60cm −1, and (iii) those containing LiSCN and CaI 2, which also produce two absorption bands but with shifts of δν=+6 and +22cm −1. The spectral data are critically compared with those previously obtained for poly (acrylonitrile-co-vinyl acetate) under a similar range of conditions.

Relationship between intracellular pH (pH i) and calcium (Ca i2+) in avian heart fibroblasts

Measurements of pH i and Ca i 2+ were made in single isolated avian heart fibroblasts using the fluorescent dyes 2,3-dicyanohydroquinone (DCH) and Indo-1. The resting level of Ca i 2+ is in part maintained by an influx of Ca 2+ from the external medium. This flux was reduced in the absence of Ca 0 2+ or by adding 2 m M LaCl 3 or CoCl 2 to the bathing medium; however, it was insensitive to calcium channel blockers nifedipine and verapamil. BAPTA (25 μ M), a calcium chelator, also reduced Ca i 2+. Changes in Ca i 2+ brought about by any of these methods were found to be accompanied by an intracellular acidification. Experiments were carried out altering pH i using trimethylamine, propionate, and ammonium chloride to determine whether pH i could influence Ca i 2+. It was found that an intracellular acidification induced a fall in Ca i 2+ and any rise in pH i induced a rise in Ca i 2+. These results suggest a direct interaction between Ca i 2+ and pH i. Various models are described which may account for the experimental observations. The findings are discussed in terms of the possible roles for pH i and Ca i 2+ and their interactions to influence cell motility and adhesion.

In dialyzed squid axons Ca i2+ activates Ca o2+Na i+ and Na o+Na i+ exchanges in the absence of Ca chelating agents

We used internally dialyzed squid axons to explore whether the reported activatory effect of Ca i 2+ on the partial reactions of the Na +Ca 2+ exchange (essential activator) is secondary to the presence of Ca 2+ chelating agents in the internal medium. The effect of Ca i 2+ pulses on both the reverse (Ca o 2+-dependent Na + efflux) and Na +Na + exchange (Na o +-dependent Na + efflux) modes of the Na +Ca 2+ exchange was studied in axons dialyzed without EGTA. For these experiments a substantial inhibition of the Ca 2+ buffer capacity of the axoplasm was achieved by the use of Ruthenium red (10–20 μM), cyanide (1 mM) and vanadate (1 mM) in the dialysis solution. Our results indicate that the Ca i 2+ requirement of the reverse and Na +Na + exchange can not be explained by a direct inhibition of the Na +Ca 2+ exchanger by EGTA. In fact, both modes of operation of the exchanger can be activated by internal Ca 2+ ions in the complete absence of Ca 2+ chelating agents thus indicating that the ‘catalytic’ effect of Ca i 2+ on the Na +Ca 2+ exchanger is a real phenomenon.

Complexes of alkali metals, magnesium, and calcium with phosphoryl-containing pendant tetraazamacrocyclic ligands

1. The reaction of lithium, sodium, potassium, and cesium 2,4-dinitrophenoxides and magnesium and calcium iodides with a number of phosphoryl-containing pendant tetraazamacrocyclic ligands L in nonaqueous solvents was studied. 2. The stability constants of complexes of alkali metals with the composition [ML]+ and of magnesium and calcium with the composition [MLI]+ with the indicated ligands were determined. 3. Among the investigated macrocyclic compounds, the ligand that contains a 14-membered macroring and an ethylene bridge in the side chain is the most effective complexing agent.

In squid axons, ATP modulates Na +-CA 2+ exchange by a Ca i2+-dependent phosphorylation

In squid axons ATP stimulates both the forward and reverse modes of the Na 2+-Ca 2+ exchange by changing the affinity of the carrier towards Na 2+ and Ca 2+ ions. Whether ATP activates the Na 2+-Ca 2+ antiporter allosterically or is hydrolyzed during activation is still debated. The hypothesis that ATP modulates the Na 2+-Ca 2+ exchange through phosphorylation has been tested by means of [γ-S]ATP, an ATP analog that can act as a substrate for kinases but not for ATPases. Steady-state Ca 2+ efflux was measured in squid axons dialyzed without ATP and containing either 0.7 or 100 μM Ca i 2+. Addition of 1 mM [γ-S]ATP markedly increases the Na o +-dependent component of the Ca 2+ efflux. The activation by [γ-S]ATP: (1) requires the presence of Mg i 2+, (2) is partially reversible upon removing the analog, (3) is greater than that caused by ATP and (4) only operates on the exchange system since no activation of the ATP-dependent uncoupled Ca 2+ efflux (Ca 2+ pump) can be detected. 22Na 2+ experiments were used to monitor the Ca o-dependent Na + efflux (reverse Na +-Ca 2+ exchange). Without Ca i 2+ and ATP, Na + efflux is very small (‘leak’). [γ-S]ATP does not activate the efflux of Na + in the absence of Ca i 2+. In the presence of Ca i 2+ the ATP analog stimulates both the Ca o- and Na o-dependent Na + efflux components. Interestingly, neither the Na + pump, Ca i 2+-independent Na +-Na + exchange, Na i +-Mg i 2+ exchange or Na +/K +/Cl − cotransport are affected by [γ-S]ATP. The experiments indicate that a Ca i 2+-dependent phosphorylation occurs during the activation of the Na +-Ca 2+ exchange by ATP.

The He(I) photoelectron spectra of aqueous solutions of calcium salts

The He(I) photoelectron spectra of the surfaces of liquid aqueous solutions of calcium chloride, bromide, iodide and nitrate at −10 to 15°C are reported. Values of vertical ionisation energies (eV±0.3) are: water (lone pair) = 11.2, Cl −( 2P) = 10.0, Br −( 2P) = 9.0, I −( 2P 3 2 ) = 7.8, I −( 2P 1 2 ) = 8.6, NO − 3 = 10 (shoulder).

Infrared spectra of ammonia adsorbed on evaporated films of calcium fluoride and calcium iodide

The IR spectra of NH 3 absorbed on high surface areas of CaF 2 and CaI 2 were investigated. From the spectra it was concluded that NH 3 adsorbed on CaI 2 forms a complex of the type Ca(NH 3) n I 2, very similar to the complexes formed by ammonia on CaCl 2 and CaBr 2 films. In the NH 3 CaI 2 system a band at 310 cm −1 was found and was attributed to the CaN stretching vibration. The adsorption of NH 3 or CaF 2 was found to be a reversible physical adsorption and no evidence of complex formation was detected. The difference in the behavior of the adsorbents toward NH 3 adsorption was related, qualitatively, to the crystals' structures and to their lattice energies.

Determination of trace metals in biological materials by iodides extraction and atomic absorption spectrometry

Extraction of arsenic, mercury, gold, silver, antimony, indium, bismuth, tellurium, cadmium, zinc and copper iodides with methylisobutylketone was examined in the sulfuric acid of concentrations from 0 to 15 normalities. Although, arsenic and zinc iodides were extracted from 6 to 12 normalities, extraction of other metal-iodides were carried out in more wide range of sulfuric acid concentrations almost from 2 to 12 normalities. Iron, sodium, potassium, magnesium and calcium iodides, these, being chief biological elements of inorganic substances, were not extracted in the least into methylisobutylketone layer from sulfuric acid solution. Copper and zinc were normal elements of biological materials and were extracted into methylisobutylketone layer by this procedures. The flame interferences of copper and zinc were not recognized in determinations of gold, silver, antimony, indium, bismuth, tellurium and cadmium. To investigate the influences of biological elements, mock solutions of human blood and urine were prepared. The addition of mock blood does not excessively interfere with determinations of arsenic, mercury, indium, bismuth, tellurium, cadmium, silver and antimony with the exception of gold. However, with addition of mock urine negative interferences were strongly seen in antimony determination, while in mercury, indium and silver determinations only slight interferences were observed. To examine the influences of sample preparation techniques, gold, silver, indium, cadmium and copper were treated both by wet ashing (nitric acid and sulfuric acid) and dry ashing.(ABSTRACT TRUNCATED AT 250 WORDS)

Indirect, anodic oxidation of d-glucitol in aqueous calcium iodide

Indirect, anodic oxidation of d-glucitol in aqueous calcium iodide

Thermal Reactions of Oleic Acid Esters with Iodides of Alkali and Alkaline Earth Metals

As previously reported, thermal reaction of fatty acid methyl ester and magnesium iodide resulted in the formation of magnesium soap and methyl iodide. In this paper, thermal reactions of oleic acid esters having various chain length of alkoxyl group with iodides of alkali and alkaline earth metals under various reaction temperatures were carried out.The longer the chain length of alkoxyl group in the oleates, the lower the yield of alkyl iodide except the case of magnesium iodide resulted. The higher the temperature in the reaction of methyl oleate with the metal iodides, the higher the maximum yield of methyl iodide and the faster the velocity which reached the maximum yield gained. The reaction of methyl oleate with calcium iodide at 200°C gave the maximum yield of alkyl iodide, 89% of methyl iodide.

Thermal Reaction of Alkyl Acetates with Iodides of Alkali and Alkaline Earth Metals

Thermal reactions of alkyl acetates (methyl, ethyl, propyl, butyl, and heptyl) with iodides of alkali and alkaline earth metals at various reaction temperatures were carried out. The reactions resulted in the formation of alkyl iodides and metal salts of acetic acid.The formation of methyl iodide was easier than that in the case methyl oleate previously reported. The maximum yields of methyl iodide in the reactions with lithium, calcium, and strontium iodides were as follows : lithium iodide 95%, calcium iodide 91%, strontium iodide 91%. Moreover, the yields of alkyl iodides from alkyl acetates were poor except methyl iodide.

Glass transition temperature of hydrated mixtures of calcium chloride and nitrate, calcium bromide and nitrate, and calcium iodide and nitrate

The glass transition temperature depends linearly on the concentration and mole fraction of halide ions, yX, in the studied concentration range up to yX = 0.95. The behaviour of the three studied systems was compared.

ChemInform Abstract: STUDY OF THE VAPORIZATION THERMODYNAMICS OF SOLID AND LIQUID CALCIUM IODIDE USING A NOVEL KNUDSEN EFFUSION TECHNIQUE

Chemischer InformationsdienstVolume 9, Issue 25 Physical Inorganic Chemistry ChemInform Abstract: STUDY OF THE VAPORIZATION THERMODYNAMICS OF SOLID AND LIQUID CALCIUM IODIDE USING A NOVEL KNUDSEN EFFUSION TECHNIQUE T. PETZEL, Search for more papers by this authorJ. KOHLE, Search for more papers by this author T. PETZEL, Search for more papers by this authorJ. KOHLE, Search for more papers by this author First published: June 20, 1978 https://doi.org/10.1002/chin.197825014AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume9, Issue25June 20, 1978 RelatedInformation