Determination of trace alkaline earth metals in brines using chelation ion chromatography with an iminodiacetic acid bonded silica column

The chromatographic behaviour of alkaline earth metals on iminodiacetic acid bonded silica was studied. It was found that the ionic strength of the eluent greatly affected both retention time and selectivity by controlling the extent to which either simple ion exchange or surface complexation was responsible for retention. With a 0.1 M KNO3 eluent, the retention order was Mg(II), Sr(II), Ca(II) and Ba(II), indicating a strong contribution to retention from ion exchange. However, when using a 1.5 M KNO3 eluent, Ba(II) was found to elute first, indicating complexation to be more dominant under these conditions (pH 4.2). The effect of the ionic strength of the sample was also studied and it was found that by matching the eluent cation with that of the sample matrix, efficient separations of alkaline earth metals in 1.0 M NaCl and KCl brines could be obtained without matrix system peaks. Using post-column reaction with o-cresolphthalein complexone, trace levels of Ca(II) and Mg(II) were determined in medicinal NaCl saline solution and laboratory-grade KCl.     

Parameterising matrix-assisted laser desorption/ionization (MALDI): effect of solvents and co-additives on analyte peak intensities

The peak intensities obtained when 2,5-dihydroxybenzoic acid (DHB) was used as a 'classic' matrix were measured using substance P (SP) and betacyclodextrin (BCD) as analytes. Enhancements in peak intensities were observed going from 1:1 MeOH/H2O to dimethylforamide (DMF) as matrix solvents. Also non-covalent interactions between SP and solvent and DHB were observed suggesting close interactions between matrix, solvent and analyte in the gas-phase. Peak enhancements were previously reported with 'superDHB' (DHB and 2-hydroxy-5-methoxybenzoic acid at 10% v/v). Co-addition of structural analogues and their respective absorption coefficients were determined. It was found that other analogues used as co-matrices could give analyte peak enhancement similar to reported for sDHB with the additional benefit that some analogues could act as matrices with DHB addition. No direct correlation was observed between absorption coefficient and the ability of the molecule to act as a 'good' UV MALDI matrix.     

Extraction and quantitation of furanic compounds dissolved in oils

There is often a need to calculate isotopic uranium activities from total uranium mass or gamma spectrometry measurement data. This calculation is based on a model of the relationship of the²³⁴U activity to that of²³⁵U since both are enriched together in the normal gaseous diffusion enrichment process. This paper presents equations for calculating these activities that have been developed from several sources of data. These equations have been used for several characterization studies and have produced very good results when compared to results from actual isotopic uranium analyses. However, because the variability in the model causes significant uncertainty in the calculated results, alpha-spectrometry is recommended for critical applications.     

Titrimetric and spectrophotometric methods for the determination of cerium(IV) in aqueous solution

A titrimetric and spectrophotometric methods for cerium(IV) determination have worked out. The first method relies upon the treatment of cerium(IV) solution with an excessive amount of iodide; the liberated iodine is extracted into chloroform, then reduced to iodide. The latter is iodometrically determined after 6- or 36-fold amplification. The spectropho-tometric finish is based upon the reaction of the titled ion with iron(II), in the presence of hexacyanoferrate(II), to form an intense prussian blue color suitable for the trace determination of cerium(IV) ion.     

Growth promotion of HepG2 hepatoma cells by antisense-mediated knockdown of glypican-3 is independent of insulin-like growth factor 2 signaling

Glypican-3 (GPC3) encodes a cell-surface heparan- sulfate proteoglycan and its expression is frequently silenced in ovarian cancer, mesotheliomas, and breast cancer cell lines and ectopic expression of GPC3 inhibited the growth of these cells, suggesting that GPC3 plays a negative role in cell proliferation. In contrast, up-regulation of GPC3 is often observed in hepatoma, neuroblastoma, and Wilms' tumor. Whether GPC3 plays the same growth inhibitory role in these tumors remains to be studied. Here we report that antisense-mediated knockdown of GPC3 in the HepG2 hepatoma cells significantly promotes the growth of hepatoma cells. In addition, we show that this growth promotion is independent of insulin-like growth factor 2 (IGF2) signaling. Our data suggest that GPC3 plays a growth-suppressing role in hepatoma and provide cell biological evidence inconsistent with the hypothesis that GPC3 acts as a growth suppressor by downregulating IGF2.     

Pseudoguaiane-type sesquiterpenes and inhibitors on nitric oxide production from Dichrocephala integrifolia

Three new pseudoguaiane-type sesquiterpenes, dichrocepholides A-C, and two new pseudoguaiane-type sesquiterpene dimers, dichrocepholides D and E, were isolated from the aerial part of Dichrocephala integrifolia. Their stereostructures were determined on the basis of chemical and physicochemical evidence. In addition, the extract and its principal sesquiterpene constituent, parthenin, showed an inhibitory activity on nitric oxide (NO) production and on induction of inducible NO synthase.     

Hall effects and entropy generation applications for peristaltic flow of modified hybrid nanofluid with electroosmosis phenomenon

The electroosmotic peristaltic flow of modified hybrid nanofluid in presence of entropy generation has been presented in this thermal model. The Hall impact and thermal radiation with help of nonlinear relations has also been used to modify the analysis. The assumed flow is considered due to a non-uniform trapped channel. The properties of modified hybrid nanofluid model are focused with interaction of three distinct types of nanoparticles namely copper ($Cu)$, silver ($Ag$) and aluminum oxide ($A{l}_2{O}_3).$ The mathematical modeling and significances of entropy generation and Bejan number are identified. With certain flow assumptions, the governing equations are attained for optimized peristaltic electroosmotic problem. Widely used assumptions of long wave length and low Reynolds number reduced the governing equations in ordinary differential equations. The ND solver is flowed for the solution process. The physical significant of results is observed by assigning the numerical values to parameters.     

Spectrophotometric determination of isonicotinic acid hydrazide

Summary Isonicotinic acid hydrazide reacts with 2,3,5-triphenyltetrazolium chloride in acidic medium in presence of excess of thallium(III) to give a pink-coloured formazan having maximum absorption at 480 nm. This colour reaction is used to determine isonicotinic acid hydrazide in urine and blood. The reaction is specific for isonicotinic acid hydrazide, and the visual limit of identification is1 g per ml.

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Zusammenfassung Isonikotinsäurehydrazid reagiert mit 2,3,5-Triphenyltetrazoliumchlorid in saurem Milieu bei Gegenwart von überschüssigem Thallium(III) unter Bildung eines rosa gefärbten Formazans mit dem Absorptionsmaximum bei 480 nm. Diese Farbreaktion wird zur Bestimmung von Isonikotinsäurehydrazid in Harn und Blut verwendet. Sie ist spezifisch. Ihre Erfassungsgrenze beträgt 1g/ml.

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Résumé L'hydrazide de l'acide isonicotinique réagit avec le chlorure de triphényl-2,3,5 tétrazolium, en milieu acide en présence d'un excès de thallium-III, en donnant un formazan coloré en rose dont le maximum d'absorption se situe à 480 nm. On utilise cette réaction colorée pour doser l'hydrazide de l'acide isonicotinique dans l'urine et dans le sang. La réaction est spécifique et la limite d'identification visuelle est de 1g par ml.

     

Retention of alkali,alkaline earth and transition metals on an itaconic acid cation-exchange column. Eluent pH,ionic strength and temperature effects upon selectivity

The unusual selectivity of a methylene succinic (itaconic) acid modified polymeric column was investigated for the separation of alkali, alkaline earth, transition and heavy metals employing non-chelating inorganic eluents. The retention of selected metal ions on the column was investigated with simple HNO3 eluents and eluents prepared from KNO3 and KCl salts of varying pH (adjusted using HNO3). From these studies both the effect of eluent ionic strength and pH upon retention was evaluated for the itaconic acid stationary phase. The results obtained showed that despite slow exchange kinetics causing poor efficiencies, acceptable baseline separations of selected alkaline earth and transitions could be obtained under optimum conditions (the baseline separation of Mg(II), Ca(II), Mn(II), Cd(II), Zn(II) and Co(II) was possible using a 15 mM KNO3-5 mM KCl eluent at pH 3.50 in under 25 min). The use of an simple ionic strength step gradient was shown that facilitated the addition of Pb(II) to the above group of metal ions. An investigation into the effect of temperature upon peak efficiency and retention showed increased column temperature could be used to improve the resolution of closely eluting metal ions such as Ca(II) and Sr(II) and Ca(II) and Mn(II).     

Phosphodiesterase‐Inhibiting Glycosides from Symplocos racemosa

Phytochemical investigation of Symplocos racemosa resulted in the isolation of two new glycosides, symploracemoside ( 1 ) and symplomoside ( 2 ), which are structurally related to the reported benzoylsalireposide ( 3 ) and salireposide ( 4 ). The structure elucidation of the isolated compounds was based primarily on 1D‐ and 2D‐NMR analysis, including COSY, NOESY, HMQC, and HMBC correlations. These glycosides showed inhibitory activity against snake‐venom phosphodiesterase I.