Intercalation of porphyrin (TMPyP) and copper-porphyrin into γ-zirconium phosphate

Water-soluble ,,,-tetrakis(4-N-methylpyridyl)porphine(TMPyP) was directly intercalated into -zirconium phosphate (-ZrP) with expansion of the interlayer distance from 12.3 to a maximum of 17.2 Å, indicating parallel orientation of porphyrin to the layer of -ZrP. Diffuse reflectance spectra of the intercalate shows that the porphyrin is protonated in the interlayer space. Uptake of Cu²⁺ ions into the porphyrin intercalate takes place with further increase in the interlayer distance. It was observed that TMPyP metalated Cu²⁺ in -ZrP. Copper porphyrin can also be taken up quite easily and an interlayer spacing of 18.6 Å is attained.     

Fast non-destructive determination of silicon in coal by means of /n,n′ γ/ and /n, γ/ processes

The possibilities were evaluated of nondestructive determination of silicon content in large-scale samples of coal /about 20–50 kg/, based on the spectrometry of prompt -radiation from processes /n, n /, E=1779 keV and /n, /, E=3539 keV and 4935 keV. The neutron sources were either²⁴¹Am–Be or²⁵²Cf located additionally in D₂O moderator. A Ge/Li/ detector was used for -radiation detection. In exposure times of up to 2 h, the detection limits of 1.3% and 0.9% and accuracies of silicon determination of 0.66% and 0.40% have been achieved in case of /n, / and /n, n / processes, respectively.     

Comparison of the Complexation of Cosmetical and Pharmaceutical Compounds with γ-Cyclodextrin, 2-Hydroxypropyl-β-cyclodextrin and Water-Soluble β-Cyclodextrin-co-epichlorhydrin Polymers

The ability of different cyclodextrins (CDs): CD, 2-hydroxypropyl CD to complex drugs like 3--hydroxy-11-oxoolean- 12-en-30-oic acid, 2-ethylhexyl-3-(4-methoxyphenyl)-2-propanoate and menthol was compared to that of water-soluble polymers: CD-co-epichlorhydrin polymer (pCD/EP) and CD-co-epichlorhydrin polymer partially modified with trimethylammonium groups (pCD/EPN⁺). 3--Hydroxy-11-oxoolean-12-en-30-oic acid was poorly solubilized by CD compared with other CD derivatives, however the determination of the complexation constants was possible for pCD/EP, K₁₁ = 740, K₁₂ = 4, for pCD/EPN⁺, K₁₁ = 681, for CD, K₁₁ = 16 and for hydroxypropyl CD, K₁₁ = 114, K₁₂ = 3.4. A significant increase of the solubility was observed for 2-ethylhexyl-3-(4-methoxyphenyl)-2-propanoate with all host molecules, it was 916 times its solubility in pure water with pCD/EPN⁺, 1116 and 1300 times with 2-hydroxypropyl CD and pCD/EP respectively. The association constants are K₁₁ = 7970, K₁₁ = 4700, K₁₁ = 1470, K₁₁ = 230 and K₁₂ = 200 with pCD/EP, pCD/EPN⁺, CD, 2-hydroxypropyl CD respectively. An increase of the solubility of menthol was observed with all CD derivatives, up to 36–37 times, except for CD. The complexation constants are similar equal to about 200.     

Quadrupole polarizability and hyperpolarizability of carbon monoxide

Summary We report a study of the electric dipole-quadrupole (A _,,), quadrupole-quadrupole (C _,,), dipole-octopole (E _,) polarizability and the dipole-dipole-quadrupole (B _,,) hyperpolarizability of carbon monoxide. All values are obtained from finite-field self-consistent field (SCF) and fourth-order manybody perturbation theory (MP4) calculations. Our best values for the dipole-octopole polarizability areE _z,zzz=60.19 andE _x,xxx=–38.06e ² a ₀ ⁴ E _h ^–1 . For the dipole-dipole-quadrupole hyperpolarizability we reportB _zz,zz=–296,B _xz,xz=–170,B _xx,zz=88 andB _xx,xx=–178e ³ a ₀ ⁴ E _h ^–2 .     

Actinide uptake onto zeolite-L and SAPO-34

The characteristics of ion exchange of uranyl and americium, which are -emitting radioactive nuclides, were examined by batch and column methods. SAPO-34 showed good selectivity for uranyl ion at pH 2–3.5, and distribution coefficients of Am³⁺ and UO ₂ ²⁺ increased with equilibrium pH. -irradiation (2 MGy) did not show any significant effect on the uptake of both of actinide ions onto L and SAPO-34. Higher does of -irradiation (up to 10 MGy) created a change of equilibrium pH, and hence uptake, due to radiolysis of water and heat localization generated by -radiation and annealing processes.     

Solubility Study of Nimodipine Inclusion Complexation with α- and β-Cyclodextrin and some Substituted Cyclodextrins

The solubility of nimodipine was measured in aqueous solutions of the following cyclodextrins: -cyclodextrin (-CD), hydroxypropyl--CD (HP--CD), -cyclodextrin (-CD), random substituted methyl--CD (M--CD), three hydroxypropyl--CDs (HP--CD) with mutually different average degree of substitution, and hydroxypropyl--cyclodextrin (HP--CD). From the determined linear solubility diagrams the values of the binding constant K₁₁ of the inclusion complexes of nimodipine with the respective CDs were evaluated. The -CDs efficiently solubilized sparingly soluble nimodipine, the highest value of K₁₁ was found for M--CD (1680 M^-1), followed by -CD (550 M^-1) and HP--CDs, where the higher degree of substitution lowered K₁₁. Only slight solubilization of nimodipine was observed in the solutions of the -CDs and HP--CD.     

Infrared Spectroscopy Analysis of Oxyhydroxides as Intermediate Species in the Formation of Iron Oxides-Silica Xerogels

A detailed infrared spectroscopy analysis in the 2500 to 3800 cm^–1 region has been used to study the formation of species in samples of iron oxides embedded in silica xerogel matrix. We report the presence of , , and forms of iron oxyhydroxides as intermediate species in the formation of -Fe₂O₃, -Fe₂O₃ and -Fe₂O₃ starting from three different iron precursors: iron nitrate, iron chloride and nanometric Fe particles prepared by chemical reduction. Our results show that under thermal dehydration and forms of iron oxyhydroxides transform into hematite and maghemite, respectively, whereas the form transform to the -Fe₂O₃ without going through an intermediate iron oxide phase.     

Determination of solid solution limits based on the thermal behaviour of aluninium substituted iron hydroxides and oxides

The formation of substitutional solid solutions of the isostructural oxyhydroxides -FeOOH--AlOOH (goethite-diaspore and -FeOOH--AlOOH (lepidocrocite-boehmite) was investigated by X-ray powder diffraction technique and by thermal analysis.The unit cell parameters of both orthorhombic structures of -Fe_1–x-Al_xOOH (Pbnm) and -Fe_1–xAl_xOOH (Cmcm) decrease clearly with the increase of aluminium content up tox=0.10.Thermal analysis reveals the sensitivity of DTA and DTG effects to the composition of solid solutions. The temperatures of topotactic formation of rhombohedral -(Fe, Al)₂O₃ and of the defect-spinel -(Fe, Al)₂O₃ during the dehydroxylation of -(Fe, Al)OOH and -(Fe, Al)OOH respectively increase as the aluminium concentration rises up to 10 mol%. The dehydration curves of samples with greater aluminium content exhibits the same maximumm/T as for the 10 mol% Al-preparation, indicating indirectly the end-members of the solid solution ranges.

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Zusammenfassung Mittels Röntgendiffraktion und Thermoanalyse wurde die Bildung von Substitutions-Mischkristallen der isostrukturellen Oxyhydroxide -FeOOH--AlOOH (Goethit-Diaspor) und -FeOOH--AlOOH (Lepidokrokit-Böhmit) untersucht. Die Elementarzellenparameter beider rhombischer Strukturen von -Fe_1–xAl_xOOH (Pbnm) und -Fe_1–xAl_xOOH (Cmcm) werden mit zunehmenden Aluminiumgehalt bis zux=0.10 eindeutig kleiner.Thermoanalyse zeigt die Empfindlichkeit von DTA- und DTG-Effekten gegenüber der Zusammensetzung der Mischkristalle. Steigt die Aluminiumkonzentration bis 10 mol% an, so erhöhen sich auch die Temperaturen für die topotaktische Bildung von rhomboedrischem -(Fe,Al)₂O₃ und des Defekt-Spinells -(Fe,Al)₂O₃ bei der Dehydroxylierung von -(Fe,Al)OOH und -(Fe,Al)OOH. Die Dehydratationskurven von Proben mit einem größeren Aluminiumgehalt zeigen dasselbe m/T-Maximum wie für die Proben mit 10 mol%, was indirekt auf die Grenze des Mischkristallbereiches deutet.

     

The effect of Fe(II) ions on the 1,10-phenanthroline and neocuproine intercalates of γ-zirconium phosphate

1,10-Phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neocuproine), and 4,7-dimethyl-1,10-phenanthroline have been intercalated between layers of -zirconium phosphate (-ZrP). The observed interlayer distances are not a simple function of the size of guest molecules. Despite the fact that -ZrP takes up very few Fe²⁺ ions, the phen and neocuproine intercalates do take up some Fe²⁺ ions without further changes in the interlayer distances. The chemical environments around Fe²⁺ ions between layers of the intercalates were investigated by⁵⁷Fe Mössbauer spectroscopy. A fairly large fraction of the Fe²⁺ ions was found to be in a high-spin state. The low-spin [Fe(phen)₃]²⁺ ions are also ion exchanged on -ZrP, with the expansion of the interlayer up to 19.9 Å.     

Dissociative electron capture and level width of quasistationary molecular states

Perturbation theory is applied to give the cross section for dissociative capture e+A₂A+A^–. From the requirement of quantitative agreement with experiment, the level widths for the quasistationary states are estimated as ₁1.2 eV; ₂0.2 eV; ₃0.05 eV for the first three terms for H ₂ ^– .Visiting worker from the Boris Kidri Institute of Nuclear Sciences, Belgrade.     

Aqueous solubilities and octanol-water partition coefficients of binary liquid mixtures of organic compounds at 25°C

From thermodynamics and certain assumptions it is shown that, under the usual experimental conditions, the octanol-water partition coefficient (K_o/w) of a given organic liquid should be the same whether the substance is partitioned neat or as part of a mixture. Measurements of several mixtures of n-propylbenzene (log K_o/w=3.71±0.04)+ethylbenzene (log K_o/w=3.16±0.01) clearly confirm this. It is also shown that the aqueous solubility (S_w) of a neat organic liquid can be related to its aqueous solubility (S _w ), when it is present at volume fraction in an organic liquid mixture, by S _w =S_w, where is its activity coefficient in the organic mixture. The measured S _w values for n-propylbenzene + ethylbenzene (1), n-hexane + nitrobenzene (>1) and di-isopropyl ether + chloroform (<1) are found to be in good agreement with the predicted values (average differences of, respectively, <2%, 8% and 6%). In general, the bounds on S _w are expected to be 0w w.     

Effect of aminoacids on the surface free energy of nitrofurantoin

Changes in nitrofurantoin surface free energy components, Lifshitz-van der Waals, _s ^LW , electron donor, _s ^– , and electron acceptor, _s ⁺ , due to adsorption of the aminoacids: lysine, alanine and glutamic acid, were determined by means of the thin-layer wicking technique. It was found that the aminoacids slightly increase the _s ^– component already at 10^–4 M concentration. They reduce the _s ⁺ component practically to zero, and a very sharp increase of _s ^– was observed when the nitrofurantoin surface was precovered from the solutions at concentrations larger tan 10^–4 M. It is concluded that the adsorption of the aminoacids takes place via hydrogen bonding and electrostatic interactions between nitrofurantoin surface and aminoacid molecules. The increase in the _s ^– parameter is probably caused by the presence of carboxyl groups in the aminoacid molecules.     

Diffraction and XPS studies of Cu complexes of intercalated compounds of α-zirconium phosphate. I: Derivation of structural models from powder diffraction data

Reasonable structural models are proposed for the Cu complexes of two intercalated compounds of -Zr(HPO₄)₂·H₂O (-ZrP): one with 1,10-phenanthroline (A) and the other with 2,2-bipyridyl (B). The models are derived from considerations of the unit-cell geometry changes undergone by -ZrP upon insertion of, first, the organic molecules and then copper, in accordance with a set of general criteria of structural analysis called the comparison method.     

The predictive accuracy for estimating infinite dilution activity coefficients by γ∞-based UNIFAC

The predictive accuracy for estimating infinite dilution activity coefficients by a modification of the UNIFAC method wherein the group interaction parameters were based on only data (referred to as -based UNIFAC) has been studied. Estimates and measured values were compared for six prototypical solutes in a series of homologous n-alkanes, l-alcohols and alkanenitrile solvents. Despite the fact that the interaction parameters were derived using only data, this approach still gave serious errors due to several inherent problems in the original UNIFAC model. Its performance is sometimes even poorer than that of the original UNIFAC method. For example for nitromethane in alcohols and p-dioxane in nitriles values predicted by the -based UNIFAC are essentially zero. The large errors for these systems are most likely due to inaccurate interaction parameters in the -based UNIFAC method.     

Order and disorder in mixed metal linear chains: The homo and heterobimetallic EDTA (M(H2O)4OIOII)[M′(EDTA)] · 6H2O complexes (M = Mg,Mn, Co,Zn and Ni; M′ = Co,Ni, Cu and Zn)

Summary Polymetallic solid solutions of the ethylenediaminetetracetic acid (EDTA) and six divalent metal ions exist in the range: MgMnCoZnNiCu(EDTA) · 6H₂O where + + + + + =2, 01, 0,,2, 0, 1.This type of structure is characterized by the presence of two different octahedral carboxylate-bridged coordination sites forming infinite zig-zag chains. Visible and i.r. spectra and t.g.a. analysis show that there is occupational preference for the two coordination sites in the crystalline structure.Due to this preference, and also to the structural features, the heterobimetallic MM(EDTA) · 6H₂O compounds constitute a structurally new class of materials which can be described as ordered alternating-heterobimetallic polymeric coordination complexes.     

A new improved expression for gamma-ray detection efficiency of Ge(Li) detectors

In the present paper, a new improved expression for -ray detection efficiency of Ge(Li) detectors, ⁰ , is given. It is represented as a continuous function of x (viz. E ^–1) with a maximum and decreases very rapidly to a small positive value as -ray energy, E, drops to 40 keV or lower, but slowly as E rises to 1.7 MeV or higher. Since it can well represent the whole physical process of the -ray detection, this expression may be one of the simplest and most precise representations, for ⁰ at the present time.     

Measurement of103mRh produced by the103Rh/γ, γ′ /103mRh reaction with liquid scintillation counting

A liquid scintillation counting technique was applied to measure the isotope^103mRh /half life = 56.12 min/ which is difficult to detect because its -ray is of low energy and low emission probability. Tris-/2,4-pentanedionato/ rhodium /III/ /Rh/ acac/₃/ was irradiated with bremsstrahlung of accelerated 3.2 MeV electrons by LINAC. The method has given a reliable calibration curve for the determination of^103mRh radioactivity below Rh/acac/₃ concentrations of 2 mM. The integrated cross section of¹⁰³Rh/,/^103mRh determined by this method was found to be 6.8±3.4 b MeV at 3.2 MeV.     

Assay of uranium in crude diuranate cakes and MgF2 slag produced at the natural uranium conversion plants by γ-ray spectrometry

A transmission-corrected -ray counting method has been employed for the assay of uranium in crude Na₂U₂O₇ cakes produced at the Uranium Conversion Facilities. A 3×3 NaI(TI) detector was used in conjunction with a 400-channel analyzer. The observed count rate of the 1 MeV -ray emitted by the²³⁸U in the sample was corrected for sample self-attenuation, measured with a⁶⁵Zn (-energy 1115 keV) transmission source. A calibration factor determined by measuring a standard of known amount of radioactive material in the same form and geometry as the unknown sample was used to convert the transmission corrected count rate to the amount of uranium in the weighted sample. Another -spectrometric method is described for the assay of the U-content in the MgF₂ slag produced during the magnesiothermic reduction of UF₄ to U-metal ingots at the natural U-conversion plant.     

A new detection method of99Tc by nuclear excitation

A new nuclear excitation process,⁹⁹Tc (, )^99mTc reaction, was applied for the first time to radioactivation analysis of technetium. Bremsstrahlung irradiation of⁹⁹Tc samples gave the reaction product^99mTc which emits -ray measurable with ease by a semiconductor detector. The production rate of^99mTc per g⁹⁹Tc was linearly correlated with the flux of bremsstrahlung. The detection limit of⁹⁹Tc was estimated to be nanogram order (0.63 Bq⁹⁹Tc) under the optimum irradiation condition. Possible interference by¹⁰⁰Ru(, p)^99mTc reaction was also studied, which could be discriminated from the (, ) reaction by simultaneously occurring⁹⁸Ru (, p)⁹⁷Ru reaction.     

Quantitative extraction of uranium(VI) in aqueous solutions with n-alkylamine intercalates of γ-titanium phosphate

The intercalation compounds Ti(C₃H₇NH₂)(HPO₄)₂·H₂O (18.4 Å) (-TiP/n-Pr) and Ti(C₄H₉NH₂)(HPO₄)₂·H₂O (20.5 Å) (-TiP/n-Bu) have been prepared using -titanium phosphate, Ti(HPO₄)₂·2H₂O (11.6 Å), as precursor. The retention of UO ₂ ²⁺ , in aqueous solutions by -TiP is very low being only a superficial adsorption phenomenon. When the intercalated materials are used, the retention is quantitative until 95% of the cation exchange capacity in the -TiP/n-Pr case (c.e.c.=6.30 mequiv./g), and over 80% for the -TiP/n-Bu compound (c.e.c.=6.04 mequiv./g).