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The reduction process of silica supported cobalt catalyst was studied by thermal analysis technique. The reduction of the catalyst proceeds in two steps:

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$Co_3 O_4 + H_2 \to 3CoO + H_2 O, 3CoO + 3H_2 \to 3Co + 3H_2 O$$ \end{document}
which was validated by the TPR and in-situ XRD experiments. The kinetic parameters of the reduction process were obtained with a comparative method. For the first step, the activation energy, E a, and the pre-exponential factor, A, were found to be 104.35 kJ mol−1 and 1.18�106∼2.45�109 s−1 respectively. The kinetic model was random nucleation and growth and the most probable mechanism function was found to be f(α)=3/2(1−α)[−ln(1−α)]1/3 or in the integral form: g(α)=[−ln(1−α)]2/3. For the second step, the activation energy, E a, and the pre-exponential factor, A, were found to be 118.20 kJ mol−1 and 1.75�107∼2.45 � 109s−1 respectively. The kinetic model was a second order reaction and the probable mechanism function was f(α)=(1−α)2 or in the integral form: g(α)=[1−α]−1−1.

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Abstract  

Radioiodination of tri-n-butylstannyl-3-quinuclidinyl benzilate (TQNB) and N-succinimidyl-3-(tri-n-butylstannyl) benzoate (STB) was studied. STB was radiolabeled efficiently using iodogen to prepare radioactive N-succinimidyl-3- iodobenzoate (S125IB). TQNB was radioiodinated using Chloramine-T to obtain radioactive iodo-3-quinuclidinyl benzilate (125IQNB). Both S125IB and 125IQNB showed good stability at room temperature in the dark.

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Abstract  

Poly(AN—co—St) (PAS) and poly(AN—St—MMA)(PASM) were synthetized by emulsion polymerisation. The glass transition temperatures (T g) of the copolymers and the relationship between T g and the components of the copolymers were investigated by differential scanning calorimetry. The results show that T g for the AN—St bipolymers has apeak value in the range 115–118°C at a content of 50 mass% St. When methyl methacrylate was added, the T g of the terpolymer was decreased by about 2–6°C.The thermostability and the activation energy E of degradation were determined by thermogravimetric analysis.

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Abstract

This paper provides a rapid method coupled with chemometrics to visualise PEL quality of eight regions. The contents of mineral elements, Vitamin C (Vc), and colour parameters were measured using spectrophotometric methods. The volatile substances were determined by electronic nose (E-nose) and headspace solid phase micro-extraction with gas chromatography-mass spectrometry (HS-SPME/GC-MS). Chemometric analyses were employed to visualise the sample distribution according to the geographical origin. The colour parameters, Vc, and mineral contents of PEL from diverse origins were significantly different (P < 0.05). A total of 25 volatile organic compounds (VOCs) were identified from PELs, with the highest percentage of components being ethyl acetate. The combination of HS-SPME/GC-MS and E-nose can properly characterise PEL samples. Therefore, the results of this exploratory work highlight the possibility of discriminating PEL from different regions.

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Acta Alimentaria
Authors:
X. Bai
,
H.F. Gao
,
X. Li
,
Y.L. Li
,
M.Z. Lan
,
L. Li
,
Z.D. Zhao
,
Z.B. Li
, and
J. Wang

Abstract

As research advances, it is generally acknowledged that non-Saccharomyces yeast contribute to the addition of aromatic compounds during mead fermentation. In this experiment, eight different non-Saccharomyces strains and Saccharomyces cerevisiae co-fermentation, their aroma composition, and basic physicochemical parameters were investigated. More than 30 compounds with favourable impact were discovered using solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Co-fermentation of non-Saccharomyces spp. and S. cerevisiae can affect the concentration of volatile compounds, so that the mead presents different aroma characteristics. Co-fermented meads of Wickerhamomyces anomalus strains and S. cerevisiae (Wa 27-Sc and Wa 5-Sc) had higher alcohol, acids, aldehyde, and ester concentrations than those fermented with S. cerevisiae alone. In terms of taste, Wa 27-Sc was superior to Wa 5-Sc. Overall, the Wa 27-Sc received the highest score for its strong secondary aroma and good mouthfeel. The results show that the W. anomalus Wa 27 strain has a good potential to produce high quality mead.

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Abstract  

Three kinds of marine bivalves (wild Saccostrea cucullata, aquacultured Perna viridis and aquacultured Pinctada martens), collected from Daya Bay, the South China Sea, were used to investigate the bio-accumulation of radioruthenium in the glass aquarium with natural seawater (pH 8.20, 35‰ salinity, filtered by 0.45 μm) at ambient temperature under laboratory feeding conditions. The experimental results show that the stead-state of biology concentration factor (BCF, ml/g) of radioruthenium was approached around 6 days for most species of bivalves. The values of BCF in shells are the highest in organs all the three bivalves. The orders of BCF values (ml·g−1) are as: Perna viridis (33.2) < Saccostrea cucullata (47.0) < Pinctada martensi (208.4) for shells and Saccostrea cucullata (1.5) < Pinctada martensi (2.2) ≈ Perma viridis (2.4) for soft tissues, respectively, after exposed for 14 days. The rate constants of uptake and elimination of radioruthenium on marine bivalves were also discussed by first-order kinetics model. The Pinctada martensi may be applicable to be an indicator for monitoring radioruthenium among the three bivalves.

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Abstract  

The sorption/desorption of radioruthenium was investigated by the batch method in sea water system at ambient temperature on the surface sediments obtained around the Daya Bay of Guangdong Province, where the first nuclear power station of China has been running from 1994. It was found that the sorption percentage was obtained to be around 40% for all the surface sediments in 60 minutes. Then, the sorption percentage goes up slowly. The sorption percentage of radioruthenium reached around 80% in 113 days (2713 hours). The distribution coefficients decreased from 3.16·104 to 1.35·103 ml/g with the increasing of sediment concentration in the range of 4–10000 mg/l. The results of the desorption experiments suggest that the sorption of radioruthenium is irreversible with 81.5% relative hysteresis coefficient.

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Abstract  

The inclusion complex of benzaldehyde (BA) with β-cyclodextrin (β-CD) was prepared and was studied by thermal analysis and X-ray diffractometry. The composition of the complex was identified by TG and elemental analysis as β-CDBA9H2O. TG and DSC studies showed that the thermal dissociation of β-CDBA9H2O took place in three stages: dehydration in the range 70-120C; dissociation of β-CDBA in the range 235-270C; and decomposition of β-CD above 280C. The kinetics of dissociation of β-CDBA in flowing dry nitrogen was studied by means of TG both at constant temperature and at linearly increasing temperature. The results showed that the dissociation of β-CDBA was dominated by a one-dimensional random nucleation and subsequent growth process (A2). The activation energy E was 124. 8 kJ mol-1, and the pre-exponential factor A 5.041011 min-1.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
O. Manuel
,
J. Lee
,
D. Ragland
,
J. Macelroy
,
Bin Li
, and
W. Brown

Abstract  

Formation of the Solar System from heterogeneous debris of a supernova (SN) that exploded 5 billion years ago was recorded as (1) inter-linked chemical and isotopic heterogeneities in meteorites, (2) higher levels of extinct nuclides in grains that trapped larger isotopic anomalies, (3) the physical properties of grains mentioned in part (2), and (4) patterns of isotopic anomalies in meteorites, in the solar-wind, and in solar flare particles. The Sun formed on the SN core, and planets formed in a rotationally-supported, equatorial disk of SN debris. Interiors of the Sun and the inner planets accreted first in a central, Fe-rich region surrounding the SN core. These were layered as condensate from other parts of the SN fell toward the condensing Sun. Elements in outer SN layers formed low-density, giant Jovian planets. Intra-solar diffusion enriches hydrogen and lighter isotopes of individual elements at the Sun's surface.

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Summary  

The comprehension of the behavior of radioactive nuclides in aquifer requires the study of the sorption processes of nuclides in various geochemical conditions. The sorption/desorption of 65Zn(II) on surface sediments (0-2 cm) was investigated by batch method in sea water (pH 8.20, 35‰ salinity, filtered by 0.45mm) at ambient temperature. The surface sediments were obtained from four stations around the Daya Bay of Guangdong Province (China), where the first nuclear power station of China has been running from 1994. The sorption process is fast initially and around 39% average of sorption percentage (SP%) can be quickly obtained in 15 minutes for all the surface sediments. Then, the sorption percentage becomes constant. In 30 days of contact time 79.6% sorption percentage and K d=3.9. 103ml/g distribution coefficient was obtained. The value of K dbecame constant, 4.0. 103ml/g, in contact time more than 120 hours. The distribution coefficient K ddecreases with increasing sediment concentration from 4.0 to 250 mg/l from 1.31. 104to 1.68. 103ml/g, respectively. Then the value of K dgoes up to 5.38. 103ml/g with sediment concentration of 3000 mg/l. The desorption experiments suggest that the sorption of Zn(II) is irreversible with a hyteresis coefficient of 66%.

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