Ground state of small mixed helium and spin-polarized tritium clusters: a quantum Monte Carlo study

We report results for the ground-state energy and structural properties of small (4)He-T↓ clusters consisting of up to four T↓ and eight (4)He atoms. These results have been obtained using very well-known (4)He-(4)He and T↓- T↓ interaction potentials and several models for the (4)He- T↓ interatomic potential. All the calculations have been performed with variational and diffusion Monte Carlo methods. It takes at least three atoms to form a mixed bound state. In particular, for small clusters the binding energies are significantly affected by the precise form of the (4)He- T↓ interatomic potential but the stability limits remain unchanged. The only exception is the (4)He(2)T↓ trimer whose stability in the case of the weakest (4)He- T↓ interaction potential is uncertain while it seems stable for other potentials. The mixed trimer (4)He(T↓)(2), a candidate for the Borromean state, is not bound. All other studied clusters are stable. Some of the weakest bound clusters can be classified as quantum halo as a consequence of having high probability of being in a classically forbidden region.     

Raman Analysis of Polymerization of APST Molecule

In this work we investigated the solidification of aminopropylsilanetriol dissolved in water (∼25%) under different conditions by Raman spectroscopy. The solidification was carried out at three different temperatures 8 °C, 23 °C and 60 °C. The influence of electromagnetic radiation on the polymerization process was also studied. Samples were held to solidify in dark and at UV (254 nm and 356nm) spectral range. In order to investigate the influence of the substrate on the resulting polymer structure, teflon, PVC, glass, brass and silica were used. Best ordered polymerized structure was achieved for samples deposited on plastics and solidified in dark, at room temperature.     

The infrared spectra and normal coordinate analysis of syn and anti acetaldoxime

The infrared spectra of mixtures of syn and anti acetaldoxime and its deuterated analogues CH₃CHNOD, CD₃CHNOH, CD₃CDNOH and CH₃CDNOH have been recorded. The syn and anti isomers of CH₃CHNOH, CD₃CHNOH, CD₃CDNOH and CH₃CDNOH have been separated by gas chromatography [1]. The infrared spectra of separated isomers in CS₂ solution have been recorded and the assignment of ten in-plane vibrations made. From a normal coordinate analysis the Urey-Bradley force field, the potential energy distribution and additional information about assignments have been obtained.For the anti isomer the simple Urey-Bradley force field gives satisfactory agreement between the calculated and measured frequencies. For the syn isomer it is necessary to take into account the interactions between atoms separated by three bonds.     

Flow injection analysis : Part II. Ultrafast determination of phosphorus in plant material by continuous flow spectrophotometry

The effect of sample volume, tube length, tube diameter, peak height and sampling rate on the determination of phosphorus in acidic plant digests was investigated, and optimal conditions for the flow injection method are described. Sampling rates of 420 samples per hour were achieved without incurring problems from carryover of samples, and evidence was obtained that rates as high as 700 samples per hour are possible. The flow injection method was proved to be suitable for routine analyses and has obvious advantages over other automated or manual methods in sampling rate, simplicity of design and cost.     

Coulometrische Wismutometrie

Zusammenfassung Durch elektrolytische Oxydation einer Bi-Anode in gesättigter NaCl-Lösung können Bi³⁺-Ionen in Lösung gebracht werden. Dieser Prozeß ermöglicht die coulometrische Bestimmung anwesender Anionen, die schwerlösliche Bi-Verbindungen bilden.Es wurden Semimikro- und Mikrobestimmungen von Phosphationen durch elektrolytisch erzeugte Bi³⁺-Ionen bei konstanter Stromstärke ausgeführt. Die Endpunktbestimmung erfolgte amperometrisch bei konstantem Potential mit einer Indikatorelektrode — tropfende Quecksilberelektrode — und mit einer gesättigten Kalomelelektrode als Bezugselektrode. Die coulometrische Wismutometrie bietet eine weitere Möglichkeit der coulometrischen Eichung volumetrischer Lösungen im Sinne des seinerzeitigen Vorschlags vonTutundi.

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Summary Bi³⁺ ions can be brought into solution through electrolytic oxidation of a Bi-anode in saturated NaCl solution. This process makes possible the coulometric determination of the anions present that yield difficulty soluble bismuth compounds.Semimicro- and micro-determinations of phosphate ions were made via Bi³⁺-ions produced electrolytically at constant current strength. The endpoint was determined amperometrically at constant potential with an indicator electrode-dropping mercury electrode-and with a saturated calomel electrode as reference electrode. The coulometric bismuthometry affords a further possibility of the coulometric standardization of volumetric solutions in the sense of the proposal previously advanced byTutundi.

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Résumé On peut utiliser les ions Bi³⁺ en solution par oxydation électrolytique d'une anode en bismuth, en solution de chlorure de sodium saturée. Ce procédé permet le dosage coulométrique des anions présents qui forment des composés peu solubles avec le bismuth.On a mis au point le dosage semimicro et micro des ions phosphates par les ions Bi³⁺ formés électrolytiquement sous intensité constante. On détermine par ampérométrie le point équivalent à potentiel constant à l'aide d'une électrode indicatrice — électrode de mercure à goutte pendante —et avec une électrode au calomel saturée comme électrode de référence. La «bismuthométrie» coulométrique offre de grandes possibilités pour l'étalonnage coulométrique de solutions volumétriques, suivant l'idée queTutundi a émise en son temps.

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Vorgetragen beim Symposium für analytische Chemie in Graz, 29. September bis 1. Oktober 1965.

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Wir danken Herrn Dipl.-Ing.Vladimir Pantovi für seine Hilfe bei unserer experimentellen Arbeit.     

Toxic metal complexes of macrocyclic cyclen molecule – synthesis,structure and complexing properties

Toxic metal (Cd²⁺, Hg²⁺, Pb²⁺, and Ag⁺) complexes with the tetradentate macrocyclic ligand - cyclen (1,4,7,10-tetraazacyclododecane, [12]aneN₄, L) were prepared and studied in the solid state by IR, X-ray diffraction, elemental and thermal analysis. Diffraction results have yielded three molecular structures, [Cd([12]ane-κ⁴N^1,4,7,10)(NO₃)₂)] (1), [Hg([12]ane-κ⁴N^1,4,7,10)(NO₃-κ²O,O`)]NO₃ (2), [Pb₂([12]ane-κ⁴N^1,4,7,10)₂][Pb(NO₃)₆] (3) and one polymeric structure {[Ag₂([12]ane-κ³N^1,4,7)(μ₂-[12]aneN¹⁰)](NO₃)₂?2H₂O)}_n (4) featuring a unique coordination mode not observed before with cyclen as a ligand. The monodentate (1) and chelate (with small bite angle 50.3(3)°, (2) coordination modes of nitrate ligands were confirmed. Stereochemically active 6s² lone pair was suggested in 3 and DFT results confirmed no significant metal–metal covalent bond. The stability constants of the complexes with Cd²⁺ and Pb²⁺ ions were determined by potentiometric methods in aqueous solutions. Additionally, the structures of complexes in solution were observed by ¹H NMR. Both methods confirm similar cyclen complexing properties toward Zn²⁺ biometal and Cd²⁺, Pb²⁺ toxic metals.     

Radionuclides in steel slag intended for road construction

The objective of this study was to describe the radiochemical characteristics of electric arc furnace (EAF) slag from Croatian EAF black steel slags, generated from carbon steel production process in CMC Sisak d.o.o., and steel mill in Split in order to enhance the understanding of possibilities for their use in road construction. This article presents the results of radionuclide in electric arc furnace steel slag. The presence of natural isotopes ⁴⁰K, ²³²Th (²²⁸Ra), ²²⁶Ra and ²³⁸U was established. The measured activity in slag natural isotopes lies within the Croatian legally permitted limits.     

Vapor pressure of selected aliphatic alcohols by ebulliometry. Part 2

Vapor pressures of six pentanols, 2-methyl-1-butanol (CAS Registry Number 137-32-6), 2-methyl-2-butanol (CAS Registry Number 75-85-4), 3-methyl-1-butanol (CAS Registry Number 123-51-3), 3-methyl-2-butanol (CAS Registry Number 598-75-4), 2-pentanol (CAS Registry Number 6032-29-7) and 3-pentanol (CAS Registry Number 584-02-1), were measured by the precision ebulliometry over an approximate pressure range from 9 to 99 kPa. The absolute uncertainties in pressure and temperature are estimated to be less than or equal to 7 Pa and 0.02 K, respectively. The results are represented by the Antoine equation and compared with available literature data.