The viscosity and density of the methanol + n-nonane, ethanol + n-nonane, and ethanol + n-decane systems

This work presents the results obtained in measurements of the kinematic viscosity and density of the methanol-n-nonane, ethanol-n-nonane, and ethanol-n-decane systems at various temperatures and low n-alkane concentrations (within the concentration range of miscibility). The dynamic viscosities of these systems at 298.15 K were calculated according to free volume theory. The results substantiated the existence of an anomaly in the behavior of viscosity of the methanol-n-nonane system (positive Δlnη values) and its absence for the ethanol-n-alkane systems.     

Radiolysis in H2O/D2O mixtures. Hydrogen production under LOCA simulation

The hydrogen isotope radiolytic yields, G(H₂), G(HD) and G(D₂) were determined in H₂O/D₂O mixtures under chemical conditions close to a LOCA in a PHWR like Atucha I Nuclear Station, that is 2·10^–3 MH₃BO₃ and p(H+D)=8.5±0.2. The total hydrogen radiolytic yield G(H₂+HD+D₂) as a function of the deuterium atom fraction goes through a flat maximum at about 0.58. This result in dicates that the 4% flammability limit for hydrogen in the reactor's containment with be reached sooner than what is expected assuming a linear combination of pure H₂ and D₂ radiolytic yields. Hydrogen radiolytic production in 10^–3 M KBr in H₂O/D₂O mixtures gives the same results as in the boric solutions suggesting a bimolecular B(OH) ₄ ^– +OH reaction. Identical isotope concentration factors were calculated for both solutions.     

Retaining60Co2+ ions from residual water on zeolites

The ion exchange between⁶⁰Co²⁺ ions contained in residual radioactive water and zeolites of the NaA, NaX and CaA types was studied. The more advanced retaining of⁶⁰Co²⁺ ions occurs for the NaA zeolite with the higher exchange capacity, as compared to NaX. With the CaA zeolite, a very weak ion exchange with⁶⁰Co²⁺ ions was observed.     

2-[3-(Trifluoromethyl)phenyl]furo[3,2-b]pyrroles: synthesis and reactions

The synthesis and reactions of methyl 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole-5-carboxylate (1a) are described. Upon reaction with methyl iodide, benzyl chloride, or acetic anhydride, this compound gave N-substituted products 1b-d. By hydrolysis of compounds 1a-c, the corresponding acids 2a-c were formed, or by reaction with hydrazine-hydrate, the corresponding carbohydrazides 3a-c were formed. By heating 2-[3-(trifluoromethyl)phenly]-4H-furo[3,2-b]pyrrole-5-carboxylic acid (2a) in acetic anhydride, 4-acetyl-2-[3-(trifluoromethyl)phenyl]furo[3,2-b]pyrrole (4) was formed. By hydrolysis of 4, 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole (5a) was formed, and reactions with methyl iodide or benzyl chloride gave N-substituted products 5b-c. The reaction of 4 with dimethyl butynedioate gave substituted benzo[b]furan 6. Compound 3a reacted with triethyl orthoesters giving 7a-c, which afforded with phosphorus (V) sulphide the corresponding thiones 8a-c. The thiones 8a-c reacted with hydrazine hydrate to form hydrazine derivatives 9a-c. The reaction of triethyl orthoformiate with compounds 9a-c led to furo[2′,3′: 4,5]pyrrolo[1,2-d][1,2,4]triazolo[3,4-f][1,2,4]triazines 10a-c. Hydrazones 11a-c were formed from 3a-c and 5-[3-(trifluoromethyl)phenyl]furan-2-carboxaldehyde. The effect of microwave irradiation on some condensation reactions was compared with “classical” conditions. The results showed that microwave irradiation shortens the reaction time while affording comparable yields.     

Syntheses of Some 3—[1′（1′H）—Substituent—pyrazol—5′—yl] benzo [5,6] coumarins

3-[1′(1′H)-Substituent-pyrazol-5′-yl]benzo[5,6]coumarins and 3-(1′,2′-oxazol-5′-yl)benzo[5,6]coumarin were prepared via condensation of 3-(2′-formyl-1′-chlorovinyl)benzo[5,6] coumarin with hydrazine derivatives or hydroxylamine.Reaction of 3-[1′(1′H)-pyrazol-5′-yl]benzo[5,6]coumarin with alkyl halides,olefinic compunds or acid chlorides are described.     

Extensive generalization of renormalized coupled-cluster methods

The recently developed completely renormalized (CR) coupled-cluster (CC) methods with singles, doubles, and noniterative triples or triples and quadruples [CR-CCSD(T) or CR-CCSD(TQ), respectively], which are based on the method of moments of CC equations (MMCC) [K. Kowalski and P. Piecuch, J. Chem. Phys. 113, 18 (2000)], eliminate the failures of the standard CCSD(T) and CCSD(TQ) methods at larger internuclear separations, but they are not rigorously size extensive. Although the departure from strict size extensivity of the CR-CCSD(T) and CR-CCSD(TQ) methods is small, it is important to examine the possibility of formulating the improved CR-CC methods, which are as effective in breaking chemical bonds as the existing CR-CCSD(T) and CR-CCSD(TQ) approaches, which are as easy to use as the CR-CCSD(T) and CR-CCSD(TQ) methods, and which can be made rigorously size extensive. This may be particularly useful for the applications of CR-CC methods and other MMCC approaches in calculations of potential energy surfaces of large many-electron systems and van der Waals molecules, where the additive separability of energies in the noninteracting limit is very important. In this paper, we propose different types of CR-CC approximations, termed the locally renormalized (LR) CCSD(T) and CCSD(TQ) methods, which become rigorously size extensive if the orbitals are localized on nointeracting fragments. The LR-CCSD(T) and LR-CCSD(TQ) methods rely on the form of the energy expression in terms of the generalized moments of CC equations, derived in this work, termed the numerator-denominator-connected MMCC expansion. The size extensivity and excellent performance of the LR-CCSD(T) and LR-CCSD(TQ) methods are illustrated numerically by showing the results for the dimers of stretched HF and LiH molecules and bond breaking in HF and H2O.     

Comparison of low-order multireference many-body perturbation theories

Tests have been made to benchmark and assess the relative accuracies of low-order multireference perturbation theories as compared to coupled cluster (CC) and full configuration interaction (FCI) methods. Test calculations include the ground and some excited states of the Be, H(2), BeH(2), CH(2), and SiH(2) systems. Comparisons with FCI and CC calculations show that in most cases the effective valence shell Hamiltonian (H(v)) method is more accurate than other low-order multireference perturbation theories, although none of the perturbative methods is as accurate as the CC approximations. We also briefly discuss some of the basic differences among the multireference perturbation theories considered in this work.     

Biodistribution of the bone imaging agents99mTc-DHPE and99mTc-MDP in rats

The self life of the freeze-dried formulation kits utilized for the preparation of the new bone imaging radiopharmaceutical^99mTc-1,2-dihydroxy-1,2-bis/dihydroxyphosphinyl/ethane /^99mTc-DHPE/ has been investigated as well as the toxicity of the DHPE. In a biodistribution investigation of^99mTc-DHPE in rats, in comparison to^99mTc-methylenediphosphanate /^99mTc-MDP/,^99mTc-DHPE exhibited a certain extent higher skeleton uptake, a higher blood clearance rate, a very low concentration in other organs, a satisfactory biological stability and excretion primarily through the kidneys. These properties demonstrate that^99mTc-DHPE is a new promising skeleton imaging radio-pharmaceutical.     

Level-spacing distributions beyond the Wigner surmise

We introduce a dynamical system, for which it is possible to get such a large number of eigenvalues that deviations from Wigner's surmise are visible. The obtained level-spacing distribution agrees much better with the distribution derived from random matrix theory.     

Mercury Speciation in Fish by High-Performance Liquid Chromatography (HPLC) and Post-Column Ultraviolet (UV)-Photochemical Vapor Generation (PVG): Comparison of Conventional Line-Source and High-Resolution Continuum Source (HR-CS) Atomic Absorption Spectrometry (AAS)

An ultraviolet-photochemical generator (UV-PVG) capable of post-column on-line transformation of both organic and inorganic mercury species to cold vapor (Hg⁰) with subsequent detection by quartz tube-atomic absorption spectrometry (QT-AAS) was developed. Mercury(II), methylmercury(I), ethylmercury(I), and phenylmercury(I) were successfully detected after separation by reversed-phase high-performance liquid chromatography (RP-HPLC). Two types of AAS detectors were compared. The first was a commonly used line-source instrument while the second was a high-resolution continuum source (HR-CS) AAS. The latter provided better limits of detection: 0.47?µg?L^?1 for Hg(II), 0.84?µg?L^?1 for methylmercury(I), 0.80?µg?L^?1 for ethylmercury(I), and 2.0?µg?L^?1 for phenylmercury(I). The repeatability at 30?μg?L^?1 was 3.6%, 4.1%, 6.2%, and 4.5% for these species (n?=?10). These figures of merit were comparable with those reported for more sensitive atomic fluorescence spectrometry. Nine sample extraction procedures were investigated. Extraction by tetramethylammonium hydroxide and HCl at 75?°C was selected as the only method compatible with the proposed separation and detection steps providing high extraction efficiency and no changes in mercury speciation. The applicability of the proposed high-performance liquid chromatography–ultraviolet-photochemical vapor generation–quartz tube-atomic absorption spectrometry method was demonstrated using fish samples and certified reference materials (CRM) DOLT-4 (dogfish liver) and ERM-CE464 (tuna fish). The results were comparable to those obtained by a reference method based on L-cysteine extraction and high-performance liquid chromatography–inductively coupled plasma-mass spectrometry (HPLC–ICP-MS) determination.