Substoichiometric extraction in conjunction with a double tracer technique is employed to simultaneous determination of extraction constants of simple metal pyrrolidinedithiocarbamates and chloride-mixed metal pyrrolidinedithiocarbamates. The metals involved include Hg(II), Bi(III), In(III), As(III), Cd(II) and Fe(II). The extraction constants for Bi(III) and Cd(II) obtained are compared with the values available in the literature. The extraction constants for all the other metals are reported for the first time.
The gold content of placer gold flakes and gold bearing ores has been determined by instrumental neutron activation analysis /INAA/ and radiochemical neutron activation analysis /RNAA/. It was discovered that significant errors result in the instrumental method for gold flakes as small as 10 mg due to sample self-absorption of neutrons during irradiation. Reliable results were obtained, for both ore samples and gold flakes, by dissolving the samples in aqua regia prior to irradiation.
Authors:L. Li, X. Wang, J. Shen, L. Zhou and T. Zhang
Adsorption microcalorimetry has been employed to study the interaction of ethylene with the reduced and oxidized Pt-Ag/SiO2catalysts with different Ag contents to elucidate the modified effect of Ag towards the hydrocarbon processing on platinum
catalysts. In addition, microcalorimetric adsorption of H2, O2, CO and FTIR of CO adsorption were conducted to investigate the influence of Ag on the surface structure of Pt catalyst.
It is found from the microcalorimetric results of H2and O2adsorption that the addition of Ag to Pt/SiO2leads to the enrichment of Ag on the catalyst surface which decreases the size of Pt surface ensembles of Pt-Ag/SiO2catalysts. The microcalorimetry and FTIR of CO adsorption indicates that there still exist sites for linear and bridged CO
adsorption on the surface of platinum catalysts simultaneously although Ag was incorporated into Pt/SiO2. The ethylene microcalorimetric results show that the decrease of ensemble size of Pt surface sites suppresses the formation
of dissociative species (ethylidyne) upon the chemisorption of C2H4on Pt-Ag/SiO2. The differential heat vs. uptake plots for C2H4adsorption on the oxygen-preadsorbed Pt/SiO2and Pt-Ag/SiO2catalysts suggest that the incorporation of Ag to Pt/SiO2could decrease the ability for the oxidation of C2H4.
Authors:D. Li, O. Sihamala, S. Bhulaidok and L. Shen
Edible black ant (
Roger) is a traditional edible insect species in China. It has long been used as an important ingredient of health foods. The aim of the present study was to investigate the changes of organic compounds following sun drying of edible black ant. The results showed that fresh and sun dried edible black ant samples have 28 organic components. Nine of them found in the present study have not been reported previously such as 8-heptadecene and (E,E)-6,10,14-trimethyl-5,9,13-pentadecatrien-2-one. Five constituents disappeared and 4 components formed while the ant was sun dried. The major organic compounds of fresh and sun dried edible black ant belong to fatty acids and hydrocarbons. Some compounds such as fatty acids, aldehyde and alkanes appeared during the procedure indicating that sun drying speeds up lipid oxidation and hydrolytic rancidity.
Rice straw represents a significant energy source for ruminant animals, and fibers and lignin contents of rice straw are negatively related to intake potential of forages. For improvement of the digestibility of rice straw, it is necessary to understand the genetic basis of the related traits. In present study, mapping of quantitative trait loci (QTL) for acid detergent fiber (ADF), neutral detergent fiber (NDF), and acid detergent lignin (ADL) was carried out using a doubled haploid (DH) population derived from a cross between
variety Zai-Ye-Qing 8 (ZYQ8) and
variety Jing-Xi 17 (JX17). The results indicated that all three parameters were continuously distributed among the DH lines, but many DH lines showed transgressive segregation for all the three traits. A total of three main-effect QTLs were identified for ADF and ADL, two of which, qADF-9 and qADL-9, shared the same region on chromosome 9. These two main-effect QTLs explained more than 20% of the total phenotypic variations, whereas the other QTL, qADF-5, explained 12.8% of the total phenotypic variation for ADF. In addition, another two epistatic QTLs, qADF-2 and qADF-3 could explain 17.6% of the total variations. Thus, we concluded that both main-effects and epistatic QTLs were important in controlling the genetic basis of ADF.
Authors:Z. Dang, L. Fan, Y. Shen, C. Nan and S. Zhao
Different scanning calorimetry and dynamic mechanical analysis are used to study the thermal behavior of composites by melt-mixing
low-density polyethylene (LDPE) matrix and zinc oxide whisker (ZnOw) fillers. Micrographs of the composites illustrate that needle or wedge shaped ZnOw are distributed uniformly in the LDPE matrix. Dielectric properties of the composites are measured in a frequency range of
1-10 MHZ. The results show that the addition of ZnOw does not affect the melting behavior of LDPE, but has an important effect on the heat of fusion, dynamic mechanical behavior,
and dielectric behavior of the composites.
Authors:L. Ruan, Y. Liu, Z. Gao, P. Shen and Q. Sheng
The thermogenic curves of the aerobic metabolism of the three strains of Bacillus thuringiensisB.t. A, B.t. B and B.t. C have been determined by using an LKB-2277 BioActivity Monitor. B.t. A was the host bacterium without foreign gene. B.t. B and B.t. C were constructed by transforming different foreign genes into the host B.t. A, respectively. B.t. B expressed erythromycin resistant gene, while B.t. C expressed both erythromycin resistant gene and tyrosinase gene. The heat flow rate of these strains is B.t. A> B.t. B >B.t. C. These results indicated that there is obvious interrelation between expression of foreign genes and heat flow rate of
Carburization and coke deposition of unsupported and carbon-supported Fe, Mo and Fe−Mo catalysts in syngas have been studied
using thermogravimetry. Compositions of the carbides formed are evaluated on the basis of the amount of metals in the catalysts
and amount of carbon deposited during carburization. It is shown that carburization temperature and the nature of the carbides
formed (Fe5C2 and Fe2C for iron and Mo2C for molybdenum) depend on the metals but are influenced by the support and metal loading. Coke deposition on these catalysts
takes place as soon as carburization is complete.
The catalytic performance of unsupported and carbon-supported Fe, Mo and Fe−Mo catalysts for Fischer-Tropsch synthesis is
greatly influenced by the final reduction states of the catalysts. In this investigation, the reduction process of the catalysts
by H2 was studied by using TG-DTG. The reduction process depends not only on the reducibility of metals but also on the nature
of the support. Methanation of the support occurred as soon as the supported metals were completely reduced for the carbon-supported
catalysts. For these, the reduction temperature should by carefully selected so that the metal oxides are reduced as completely
as possible, whilst the methanation of the support must be avoided to obtain optimum reduced catalysts.
Authors:F. Padoani, L. Cella, X. Shen and R. Werzi
A worldwide radionuclide network of 80 stations, including 40 with noble-gas-detection capability forming part of the International
Monitoring System, has been designed to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty. Pending entry into
force of the Treaty, the certified stations are operating provisionally and so far an experience of over 100 station-years
has been acquired for particulate stations. Noble gas systems are still under testing, though the operational experience is
fast growing. A maintenance strategy is being developed on the basis of the experience acquired so far and the analysis of