Detection sensitivity of time interval analysis for the determination of α-radionuclides with millisecond order lifetimes

A selective extraction of the correlated events due to three kinds of short-lived -decay events,²¹⁶Po (145 ms),²¹⁷At (32.3 ms) and²¹⁵Po (1.78 ms), from other random background events were examined by using a time interval analysis (TIA) from the viewpoint of detection sensitivity. In the theoretical treatment based on the probability and statistics, it was clarified that the detection sensitivity proportionally increased with shortening half-lives in the following order,²¹⁵Po>²¹⁷At>²¹⁶Po. In the experiments, pulses from a liquid scintillator owing to -decay events were analyzed using a multiple TIA technique and resulted in the highest sensitivity of²¹⁹Rn–²¹⁵Po pairs in the actinium series. Thus, the multiple TIA method was applied to the practical determination of²¹⁹Rn–²¹⁵Po pairs in natural samples.     

Determination of naturalα-radionuclides related to millisecond order lives in environmental samples using the time interval analysis (TIA) method

The time files due to radioactive decay events were analyzed for the selective extraction of successive alpha-decay pulse events in millisecond orders, such as²¹⁶Po (145 ms, thorium series),²¹⁷At (32.3 ms, neptunium series), and²¹⁵Po (1.78 ms, actinium series) after respective preceding parents decay, using a multiple time interval analysis (TIA-MTA) technique from both theoretical and experimental viewpoints. In the theoretical treatments, the detection sensitivities of each correlated event in natural decay series was compared with more generalized conditions. It was noteworthy that the evaluated detection sensitivity had increased proportionally with shorter half-lives in the following order:²¹⁴Po>²¹⁵Po>²¹⁷At>²¹⁶Po.Finally, the present TIA was applied to the clarification of thorium series disequilibrium states in Tamagawa (Akita, Japan) Hot Spring waters. Activities of²²⁴Ra were evaluated to be 3.41±0.38 and 0.60±0.08 Bq/l at the upper and lower stream, respectively. The results from activity ratios of radium to thorium isotopes showed a preferential precipitation of radium isotopes in comparison with thorium, reflecting the sensitivity to the lowering acidity of strongly acidic hot spring waters in the lower end of the stream.     

Simultaneous determination of radionuclides separable into natural decay series by use of time-interval analysis

A delayed coincidence method, time-interval analysis (TIA), has been applied to successive – decay events on the millisecond time-scale. Such decay events are part of the ²²⁰Rn²¹⁶Po (T_1/2 145 ms) (Th-series) and ²¹⁹Rn²¹⁵Po (T_1/2 1.78 ms) (Ac-series). By using TIA in addition to measurement of ²²⁶Ra (U-series) from -spectrometry by liquid scintillation counting (LSC), two natural decay series could be identified and separated. The TIA detection efficiency was improved by using the pulse-shape discrimination technique (PSD) to reject -pulses, by solvent extraction of Ra combined with simple chemical separation, and by purging the scintillation solution with dry N₂ gas. The U- and Th-series together with the Ac-series were determined, respectively, from alpha spectra and TIA carried out immediately after Ra-extraction. Using the ²²¹Fr²¹⁷At (T_1/2 32.3 ms) decay process as a tracer, overall yields were estimated from application of TIA to the ²²⁵Ra (Np-decay series) at the time of maximum growth. The present method has proven useful for simultaneous determination of three radioactive decay series in environmental samples.     

Mechanism of ring expansion in 1-ethylindane under dehydrogenation conditions

Studies of 1-ethyl-(-¹⁴C)-indane dehydroisomerization over a Pt/Al₂O₃ catalyst (AP-64) have revealed that 34.5% or 16.5% of the initial tracer label migrates into the -position of the expanded methylnaphthalene ring when the catalyst is pretreated at 763 K in Ar or H₂, respectively. The reaction mechanism is discussed.

---

1--(¹⁴C)- -64. , 763 - 34,5% , —16,5%. .

     

Radiochemical separation of thorium acetylacetonate from other thorium species

A solvent extraction technique to separate different chemical species of thorium is presented. The products formed by the chemical effects of the /n,/ reaction on the Th/acac/₄ were separated by this method and the retention value was measured.     

Liquid phase oxidation of acrolein to acrylic acid

The active catalytic system containing Co(acac)₃ and acetaldehyde in dioxane for the homogeneous oxidation of acrolein to acrylic acid at 40°C and 1–9 atm has been studied.

---

Co(acac)₃ 40°C 1–9 .

     

A rhodium-DIOP complex attached to an inorganic support as catalyst for enantioselective syntheses

A rhodium-DIOP complex attached to a macroporous silica gel has been tested as catalyst for the enantioselective hydrosilylation of acetophenone and hydrogenation of -acetamidocinnamic acid. The catalyst has been found to be comparable in asymmetric efficiency to homogeneous analogues. In both reactions, the activity of the heterogenized catalyst was by ca. one order of magnitude lower relative to the homogeneous system.

---

DIOP, , - . , . .

---

---

Parts XLIX and XLVIII, cf. Ref. /1/     

Neutron activation analysis of thorium after separation of233Th by isotopic ion exchange

The procedure for thorium determination in ammonium diuranate (ADU) and rocks, by neutron activation analysis after chemical separation of²³³Th, is presented. The separation of²³³Th from the interfering radioisotopes is based on the retention of²³³Th by a resin saturated with thorium (isotopic exchange) and on the elution of the interfering radioisotopes by a dilute solution of thorium in 0.5M HCl (ion exchange). The determination limit of thorium in rocks and ADU was found to be 0.56 and 9.3 g, respectively, when a 20% relative standard deviation was assumed as acceptable. The highest value obtained for the determination limit of thorium in uranium compounds, on account of the²³⁴Th activity present, is discussed.From a thesis submitted by C. S. Munita to the Instituto de Pesquisas Energéticas e Nucleares (CNEN/SP) University of São Paulo, in partial fulfillment for a Doctor of Science's Degree. Work supported by the Brazilian Atomic Energy Commission.     

A chemical investigation ofAchillea nobilis

From the flower heads and leaves ofAchillea nobilis collected in the flowering phase close to Balytkykol, Egindybulak region, Karaganda Province, Kazakh SSR, by extraction with chloroform and chromatography of the combined substances on a column of silica gel we have isolated a new sesquiterpene lactone anobin C₁₅H₂₀O₅, mp 175.5–177.5°C and have identified for the first time estafiatin, C₁₅H₁₈O₃, mp 102–104°C []²⁰ –10.3° (chloroform); hanphyllin, C₁₅H₂₀O₃, mp 189°C (decomp), [] _D ²⁰ + 58.6° (c 0.39; chloroform), and 3,5-dihydroxy-6,7,8-trimethoxyflavone, C₁₈H₁₆O₇, mp 148–150°C. On the basis of chemical and spectral characteristics it has been established that anobin has the structure of 4,10-dihydroxy-2,3-epoxy-5,7(H),6(H)-guai-11(13)-en-6,12-olide. It has been established that estafiatin possesses a pronounced growth regulating activity.Deceased.Chemical and Metallurgical Institute, Academy of Sciences of the Kazakh SSR, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 603–607, September–October, 1984.     

Simultaneous determination of environmental α-radionuclides using liquid scintillation counting combined with time interval analysis (TIA) and pulse shape discrimination (PSD)

Some improvements of the detection sensitivity in pulse time interval analysis (TIA) based on selective extraction of successively - correlated decay events within millisecond order from random or background events, were established by the utilization of PSD, to reject /-pulses from -ones and a simple chemical procedure of radium separation, together with the use of well resolved scintillator. By applying the PSD, the contribution of -decay events was completely eliminated in both the -spectra and the TIA distribution curves as well as the improvement into clear energy resolution and the enhancement of detection sensitivity for the TIA. As a result, the TIA and -spectrometric analysis of²²⁶Ra-extract showed the existence of²²³Ra (Ac-series) and /-correlated events with correlated life (due to 0.16 ms due to²¹⁴Bi()²¹⁴Po()) along with a singly well resolved -peak to be useful for the determination of²²⁶Ra (U-series). The difference of half-lives (145 and 1.78 ms) due to²¹⁶Po and²¹⁵Po (direct daughters of²²⁴Ra for Th-series and²²³Ra for Ac-series, respectively) was also proven for the possibility of the simultaneous determination of both correlated events by using the TIA/PSD combined with chemical separation and liquid scintillation counting method. Finally, the simultaneous determination of three natural decay series, which include U-, Th- and Ac-series nuclides, have been conveniently carried out for some environmental samples using the present method combined with²²⁵Ra yield tracer (Np-series).     

The kinetic energy components of LCAO-molecular orbitals: A comment on the “Electron-in-a-Box”-“LCAO-MO-Model” analogy

In many textbooks attention is drawn to the close analogy that seems to exist between the Electron-in-a-Box-wave functions _n and their LCAO-MO counterparts _J (J = n) for the movement of an electron in a -system. It is often implied that the wave lengths of _n and of _J (J = n) which satisfy to a high degree the relation =, have the same physical meaning. It is shown that this is not the case. for a linear system (e.g. a one-dimensional Electron-in-a-Box-model) is directly connected with the momentum of the electron and therefore with its kinetic energy according to the deBroglie relation. However, there is no such simple relationship between A and the corresponding kinetic energy component in LCAO-MO's _J . (The necessary two-center kinetic energy integrals have been computed for 1s-type atomic orbitals.)

---

Zusammenfassung In vielen elementaren Textbüchern wird die Aufmerksamkeit auf die scheinbar enge Verwandtschaft hingelenkt, die zwischen den Wellenfunktionen _n für ein Electron-in-a-Box-Modell und den entsprechenden LCAO-MOs _J (J=n) für die Bewegung eines Elektrons in einem -System besteht. Unter anderem wird oft implizit angenommen, daß die Wellenlängen der Funktion _n und von _J (J=n), die weitgehend der Bedingung = genügen, die gleiche physikalische Bedeutung haben. In dieser Arbeit wird gezeigt, daß dies nicht der Fall ist. Für ein lineares System (z. B. ein eindimensionales Electron-in-a-Box-Modell) ist über die deBroglie'sche Beziehung direkt mit dem Impuls und damit mit der kinetischen Energie des Elektrons verknüpft. Im Gegensatz dazu existiert keine einfache Beziehung zwischen und der entsprechenden Komponenten der kinetischen Energie in einem LCAO-MO _J . (Die notwendigen Zweizentrenintegrale der kinetischen Energie wurden für Atomorbitale vom 1s-Typus berechnet.)

---

Résumé Dans les textes élémentaires de chimie théorique on attire souvent l'attention sur l'analogie qui semble exister entre les fonctions d'onde _n pour un modèle «Electron-in-a-Box» et les fonctions correspondantes LCAO-MO _J (J=n) décrivant le mouvement d'un électron dans un système . En particulier cette comparaison implique que les «longueurs d'onde» de _n et de _J (J=n), qui satisfont pratiquement la relation =, ont la même signification physique. Dans ce travail on montre, que ceci n'est pas le cas. Pour un système linéaire (c.à.d. un modèle linéaire du type «Electron-in-a-Box») est reliée directement à la quantité de mouvement et par là à l'énergie cinétique, par la relation de deBroglie. Par contre on ne trouve pas une dépendance analogue entre et la composante correspondante de l'énergie cinétique dans une orbitale moléculaire LCAO _J. (Les intégrales bicentriques pour les composantes d'énergie cinétique nécessaires à ce calcul ont été déterminées pour des orbitales atomiques du type 1s.)

     

On-line coupling of packed column supercritical fluid chromatography with multiple wavelength detector and radioactivity flow-through detector

Summary The coupling of packed column supercritical fluid chromatography with a commercial Radioactivity Flow-Through Detector for the sensitive and highly selective detection of radioactive nuclides (e.g.¹⁴C is described. The radioactivity flow-through detector showed no baseline shift when pressure or modifier (methanol) gradients were applied. The detector cell was pressure resistant even at high flow rates, over a period of approx. 100 hours and showed no leakage problems even at 40°C, 340 bar, 4.0 ml/min and a modifier content up to 20%.     

Density functional calculations of the structures and bond energies of Cr(CO)6 and (η6-C6H6) Cr(CO)2(CX) (X=O,S) complexes

Summary Quantum chemical calculations based on density functional theory have been performed on Cr(CO)₆, (⁶-C₆H₆)Cr(CO)₃ and (⁶-C₆H₆)Cr(CO)₂(CS) at the local and nonlocal level of theory using different functionals. Good agreement is obtained with experiment for both optimized geometries and metal-ligand binding energies. In particular, a comparison of metal-arene bond energies calculated for the (⁶-C₆H₆)Cr(CO)₃ and (⁶-C₆H₆)Cr(CO)₂(CS) complexes correlates well with kinetic data demonstrating that substitution of one CO group by CS leads to an important labilizing effect of this bond, which may be primarily attributed to a larger -backbonding charge transfer to the CS ligand as compared with CO.     

Detection of sub-micro quantities of thorium by solocnrome azurine B. S.

Summary Solochrome Azurine B. S. has been introduced as a new colour reagent for the detection of thorium in sub-micro quantities. Thorium gives a bluish violet colour with the dye at p_H 4. The limit of identification is 0.22g of thorium.

---

Zusammenfassung Solochrom Azurin B. S. wird als neues Farbreagens für den Nachweis von Thorium in Mikrogrammengen vorgeschlagen. Thorium gibt mit dem Farbstoff bei p_H 4 eine blauviolette Farbe. Die Erfassungsgrenze beträgt 0,22g Thorium.

---

Résumé On a introduit la Solochrome Azurine B. S. comme nouveau réactif colorimétrique pour déceler les quantités submicro de thorium. Celui-ci donne une couleur violet bleuâtre avec le colorant à p_H 4. La limite de dilution est de 0,22g de thorium.

     

Binary and Ternary Complexes Between Lauryl Hexaoxyethylene, Benzoate and Cyclodextrin. Part II. β-CD

The characterization of binary and ternary complexes of benzoate, lauryl hexaoxyethylene (C₁₂E₆) and -CD is presented. The complexation equilibrium was characterized by UV-Vis spectrophotometry, titration microcalorimetry, capillary electrophoresis, and 2D ROESY ¹H-NMR. Results suggested that -CD forms one complex with C₁₂E₆in the stoichiometric ratio of -CD : C₁₂E₆1.5 : 1, with a stability constant 1.3 × 10⁵ M^-1.5. The 2-D ROESY ¹H-NMR spectrum indicated that C₁₂E₆is included inside the -CD cavity. The primary binding site of C₁₂E₆ is on the lauryl subunit of this molecule. Analogous to a previously reported study of -CD, the combination of -CD and C₁₂E₆precipitated from the solution. Addition of benzoate seemed to dissolve the precipitate and nearly doubled the apparent stability constant of the complex. Results from the various techniques supported formation of ternary complexes between -CD, C₁₂E₆, and benzoate.     

New triterpene glycosides fromThalictrum squarrosum St. ex Willd. The structure of squarrosides B3 and B4

From the above-ground part ofThalictrum squarrosum St. ex Willd. (Ranunculaccae), an equilibrium mixture of two triterpene glycosides, squarrosidc B3 (1), 3-O-[O-(-L-rhamno-pyranosyl)-(16)--D-glucopyranosyl]-21 (S),22(),23(R)-3,21,22,30-tctralmydroxy-21, 23-cpoxycycloartlt-24-ene, and squarrosidc B4 (2), its 21(R) epimer, was isolated. Their structures were established on the basis of IR and 2D NMR spectra and FAB mass spectra.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1547–1551, June, 1996.These signals coincide for 5 and 6.     

Electrostatic and structural similarity of classical and non-classical lactam compounds

Various electrostatic and structural parameters for a series of classical and non-classical -lactams were determined and compared in order to ascertain whether some specific -lactams possess antibacterial or -lactamase inhibitory properties. The electrostatic parameters obtained, based on the Distributed Multipole Analysis (DMA) of high-quality wavefunctions for the studied structures, suggest that some non-classical -lactams effectively inhibit the action of -lactamases. As shown in this work, such electrostatic parameters provide much more reliable information about the antibacterial and inhibitory properties of -lactams than do structural parameters.     

State of copper in massive Cu?V?Mo oxide systems

ESR data for X(CuO) V₂O₅·8.3 MoO₃ system heated at 400–550 °C indicate the occurrence of a copper state with d_Z ²-ground state. Copper ions are orbitally ordered apparently in –Cu²⁺–O–Cu¹⁺–O–Cu²⁺-chains.

---

B X(CuO) V₂O₅·8,3 MoO₃ , 400–550°C d_Z ²- . , , –Cu²⁺–O–Cu¹⁺–O–Cu²⁺-.

     

Exact spin-pairing energies at the crossovers in octahedral d 4, d 5, d 6, and d 7 transition metal complexes

Exact spin-pairing energies are calculated by direct diagonalization of the relevant ligand field plus interelectronic repulsion matrices for the configurations d ⁴, d ⁵, d ⁶, and d ⁷ of octahedral transition metal ions. The results are presented in terms of /B as function of = C/B for the range of values =3.0 to 8.0. Comparison with the quantity resulting from a simplified approach in which configuration interaction is neglected or considered on an approximate basis only reveals significant differences. Useful estimates of spin-pairing energies are provided, in addition, on the basis of empirical magnetic and electronic spectral data.

---

Zusammenfassung Exakte Spinpaarungsenergien für die Konfigurationen d ⁴, d ⁵, d ⁶ und d ⁷ oktaedrischer Übergangsmetallionen werden durch direkte Diagonalisierung der entsprechenden Matrizen des Ligandenfeldes sowie der Elektronenwechselwirkung berechnet. Die Ergebnisse für /B werden in Abhängigkeit von = C/B für den Wertebereich =3.0 bis 8.0 angegeben. Ein Vergleich mit der Größe , die bei einer vereinfachten Behandlung unter Vernachlässigung oder näherungsweiser Berücksichtigung der Konfigurationswechselwirkung erhalten wird, zeigt auffallende Unterschiede. Nützliche Abschätzungen der Spinpaarungsenergie werden außerdem unter Benutzung empirischer magnetischer und elektronenspektroskopischer Daten erhalten.

---

Résumé Les énergies exactes de couplage de spin sont calculées par diagonalisation directe du champ de ligand correspondant en plus des matrices de répulsion électronique pour les configurations d ⁴, d ⁵, d ⁶ et d ⁷ des ions octaédriques des métaux de transition. Les résultats sont présentés en termes de /B en fonction de = C/B dan l'intervalle =3,0 à 8,0. On trouve des différences significatives par comparaison de avec les valeurs résultant d'une approche simplifiée sans interaction de configuration ou avec interaction de configuration approchée. De plus, des estimations des énergies de couplage de spin sont obtenues à partir de données empiriques magnétiques et spectrales.

     

Über Verdazyliumsalze

Zusammenfassung Verdazyle reagieren mit FeCl₃ und anderen Metallhalogeniden in HCOOH unter Bildung von Doppelsalzen. Mit Tetranitromethan erhält man Verdazylium; C(NO₂)₃ ; und Verdazylium^;NO₃ ;. Verdazyliumsalze und Tetramethyl-p-phenylendiamin ergeben unter Elektronenübergang Verdazyle undWursters Blau. Dabei werden aus 2 diamagnetischen Verbindungen 2 paramagnetische Radikale gebildet. Die Absorptionsspektren verschiedenartig substituierter Verdazyliumsalze werden im Zusammenhang mit den Spektren der entsprechenden Verdazyle diskutiert.

---

Verdazyls react with FeCl₃ and other metal halides in formic acid to give double-salts. Verdazylium;·C(NO₂)₃ ; and Verdazylium;NO₃ ; were obtained with tetranitromethane. Verdazyliumsalts and tetramethyl-p-phenylenediamine yield, in an electron transfer reaction, the corresponding verdazyls andWurster's-blue; i. e. two diamagnetic compounds react to give two stable paramagnetic species. The absorption spectra of different substituted verdazylium salts are discussed in relation to the spectra of the corresponding verdazyls.

---

---

10. Mitt.:F. A. Neugebauer, Mh. Chem.97, 853 (1966).