The development of a new radionuclide generator, based on118Te/118Sb, has been studied. The 3.5 minute118Sb daughter activity decays principally by positron emission and has potential use as a flow tracer. The118Te parent is conveniently produced by proton bombardment of antimony targets. A simple and efficient scheme for the separation of radiotellurium from proton-irradiated antimony targets has been developed, and thin-target cross sections for121Sb(p, 4n)118Te and competing reactions have been determined. For antimony targets irradiated with 46 MeV protons, the yields (mCi/g Ah) of118Te,119mTe and119Te were measured to be 0.71, 0.33 and 1.9, respectively. The adsorption and elution characteristics of activated carbon for tellurium have been evaluated for use as a column chromatography adsorbent in a118Te/118Sb generator. The conditions for optimal118Sb elution and minimal118Te breakthrough for promising systems are presented.
Authors:L. Wang, S. Jiao, Y. Jiang, H. Yan, D. Su, G. Sun, X. Yan and L. Sun
Genetic structure of 142 parent lines of sorghum [Sorghum bicolor (L.) Moench] was analyzed using model-based approach based on SSR markers. Forty-one selected from 103 SSR markers were used to analyze the parent lines, which generated 189 alleles revealed by each marker ranging from 2 to 11 with an average of 4.6 per marker. The polymorphic information content (PIC) value was 0.543 with a range of 0.089 to 0.850. All the parent lines were assigned to 7 subgroups, named Kafir, Kaoliang, Feterita, Shallu, Hegari, Milo and Durra. Parent lines without clear pedigree record were clustered into their corresponding groups, and genetic components of each line were estimated by Q-values. Information of this study would be useful for breeders to conclude their genetic background and select appropriate parents for germplasm improvement and hybrid breeding, and thus improve the efficiency of breeding programs.
Triticum dicoccoides, wild emmer wheat, is the direct progenitor of cultivated wheats, has the same genome formula as durum wheat, and has contributed two genomes to bread wheat. It harbors many useful genes, more than can be used for wheat improvement. These genes are associated with many agronomic traits, abiotic stress tolerances, biotic stress resistances, grain protein content and micronutrient mineral concentrations. In this review, we summarized the achievements regarding gene discovery, i.e. gene identification, mapping and cloning in wild emmer wheat. These genes, controlling important agronomic traits, disease resistance, drought tolerance, high protein content and micronutrient mineral content, should be very useful for improvement of wheat production and food nutrition. However, the majority of genetic resources in wild emmer remain untapped, demonstrating the need for further exploration and utilization for wheat breeding programs. The large number of molecular markers, genomics tools and efficient cloning techniques available for wheat will greatly accelerate the application of wild emmer germplasm to wheat improvement and ensure sustainability of global wheat production.
Authors:J. Zeng, Z. Cao, D. Yang, L. Sun and L. Zhang
One of the greatest challenges in the application of organic phase change materials (PCMs) is to increase their thermal conductivity
while maintaining high phase change enthalpy. 1-Tetradecanol/Ag nanowires composite PCM containing 62.73 wt% (about 11.8 vol%)
of Ag nanowires showed remarkably high thermal conductivity (1.46 W m−1 K−1) and reasonably high phase change enthalpy (76.5 J g−1). This behavior was attributed to the high aspect ratio of Ag nanowires, few thermal conduct interfaces, and high interface
thermal conductivity of Ag nanowires in the composite PCM. These results indicated that Ag nanowires might be strong candidates
for thermal conductivity enhancement of organic PCMs.
The dilution enthalpies of D-mannitol and D-sorbitol in aqueous sodium chloride solution at various concentrations have been determined by isothermal microcalorimetry
at 298.15 K. The homogeneous enthalpic interaction coefficients over a quite large range of concentration of aqueous sodium
chloride solutions have been calculated according to the excess enthalpy concept. The results show that enthalpic pairwise
interaction coefficients (h2) of D-mannitol and D-sorbitol are positive in aqueous sodium chloride solution and become more positive with increase of the concentration of
sodium chloride. The results are interpreted in terms of the different conformations of the two polyols, solute-solute and
solute-solvent interactions involved by solvent effects.
AP/HTPB based composite
propellants with additives such as ammonium oxalate (AO), mixture of ammonium
oxalate and strontium carbonate (SC) was investigated by burning rate, TG-DTG
and FTIR experiments. The results show that the burning rates of these propellants
are decreased significantly. TG-DTG experiments indicate that decomposition
temperatures of AP with these additives are increased. Furthermore, the activation
energy of the decomposition reaction of AP is also increased in the presence
of AO or AO/SC. These results show that AO or AO/SC restrains the decomposition
of AP. The burning rates of these propellants are decreased. The burning rate
temperature sensitivity of AP/HTPB based propellants is reduced significantly
by the addition of AO or AO/SC. But the effect of AO is less than that of
AO/SC. AO/SC is better effect to reduce temperature sensitivity and at the
same time, to reduce pressure exponent. The reduced heat release at the burning
surface of AP/HTPB/AO is responsible for the reduced temperature sensitivity.
Synergetic action is probably produced between AO and SC within AP/HTPB based
propellants in the pressure range tested. This synergetic effect causes the
heat release to reduce and the burning surface temperature to increase. Moreover,
it makes the net exothermal reaction of condensed phase become little dependent
on T0. Thus, the
burning rate temperature sensitivity is reduced.
Authors:Z. Sun, C. Segebade, D. Wells and J. Green
Photon activation analysis (PAA) includes extensive data evaluation that is sensitive to error. In order to save time and
minimize human error, a new computer program—photon activation analysis system (PAAS)—was designed, built and implemented
using the SQL language and Asp.net technology to analyze PAA data. Given peak information from PAA spectra and aided by a
photonuclear data library, the program identifies the product isotopes, recognizes the possible nuclear reactions, and evaluates
the concentration of target elements. Uncertainties of concentrations are estimated using standard error propagation techniques.
The program can be accessed conveniently anywhere the internet is available and gives a fast and reliable determination of
the trace elemental content of samples. Furthermore, this program also allow one to search its database for the information
of general photonuclear reactions (e.g. energy lines, line intensities, target and product nuclides, photonuclear reactions,
cross sections, natural abundance, etc.) and estimating the activity even before the activation begins. By switching the nuclide
libraries, the program could also be expanded to neutron activation analysis and charged particle activation analysis (CPAA)
without any difficulty. This program can be a versatile tool for the daily use of the nuclear and radiochemistry laboratories
that conduct activation analysis.
The prompt k0,H factors for B, N, Si, P, S and Cl were determined relative to the 2223.25 keV gamma-line from the 1H(n,γ) reaction. The measurements were performed at the SNU-KAERI Prompt Gamma Activation Analysis facility, of which the background was greatly reduced recently by upgrading the detection system to a Compton suppressed g-ray spectrometer with a BGO/NaI(Tl) guard detector and by improving the shield geometry. From the measured prompt k0,H factors, the partial γ-ray production cross sections were determined using the latest cross section for H. The measured prompt k0,H factors were tabulated and compared with the other reported data.
Authors:R.D. Wang, Y.J. Deng, L.J. Sun, Y.L. Wang, Z.J. Fang, D.F. Sun, Q. Deng and R. Gooneratne
Growth and haemolytic activity of several pathogenic Vibrio species were compared in egg-fried-rice with different egg ratios. Egg-fried-rice preparations with rice-to-egg ratios of 4:1, 1:1, and 1:4 were inoculated with either Vibrio parahaemolyticus, V. cholerae, V. vulnificus, or V. alginolyticus and incubated for 24 h. Cell number, thermostable direct haemolysin (TDH) activity, and total haemolytic activity were determined. The cell number and total haemolytic activity increased in all Vibrio strains after 24 h, and these were most marked in egg-fried-rice with the highest egg content (1:4 (rice:egg) ratio; P<0.05). V. alginolyticus exhibited the maximal growth and V. parahaemolyticus the highest haemolytic activity, but only V. parahaemolyticus ATCC 33847, V. alginolyticus CAMT 21162, and V. alginolyticus HY 91101 showed TDH activity. Results suggest that lowering egg content in egg-fried-rice could reduce growth and virulence of Vibrio pathogens.