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Abstract  

A method of efficiency calibration for the measurement of 88Kr and 138Xe by HPGe γ-spectrometer is proposed in the present paper. The question for the efficient calibration is, how to achieve homogeneous sources of 88Kr-88Rb and 138Xe-138Cs. The fission product gases were obtained by irradiating a precisely measured amount of U3O8 (90% 235U) filled in a quartz glass ampoule. Source cell was first filled up with stearic acid, and then the fission product gases were charged into it. Xenon and krypton are not adsorbed on stearic acid, therefore, homogeneous sources of 88Kr-88Rb and 138Xe-138Cs can be prepared. The results of the experiment demonstrate that the method is feasible and successful.

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Abstract  

We studied the removal process of excessive free carbon in the nano-SiC powder by TG-DTA-MS, XRD and TEM three methods. The studies showed that the temperature of removing excessive free carbon in the nano-SiC powder should be about 750°C in air.

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Abstract  

In order to measure 182Hf by accelerator mass spectrometry (AMS), a chemical procedure for separation of hafnium from tungsten has been developed by extraction chromatography. The extraction chromatographic behavior of hafnium and tungsten has been studied using tri-n-octylamine (TOA) as the stationary phase, HCl–H2O2 mixture and NH3·H2O as the mobile phase. The effects of H2O2 concentration, column loading and column dimensions are investigated. Hf and W with microgram amounts are successfully separated on a chromatographic column (Ø5 × 196 mm), on which Hf is hardly retained after completely eluted with 6 M HCl–1% H2O2 and W strongly adsorbed is then eluted with 3 M NH3·H2O. The decontamination factor for tungsten is 3.0 × 105 and the recovery of hafnium is better than 99% using a single column separation.

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The neurotransmitter γ-aminobutyric acid (GABA) is a functional food ingredient of growing importance in the preparation of GABA-enriched germinated brown rice (GBR). Quantification of GABA levels during germination in a locally developed high yielding red rice variety (UKMRC-9) was carried out via high-performance liquid chromatography (HPLC) analysis using pre-column chemical derivatisation with 2-hydroxynaphthaldehyde (HN) using a UV detection system. Factors that influence rice germination such as soaking time and temperature were also studied. The results of this study showed that the UKMRC-9 rice variety soaked in water for 6 hours at 35 °C yielded the highest value for both germination percentage (95.4±1.2%) and GABA content (411 μg g-1). This suggests that long soaking times of 1-4 days can be substituted by short soaking times to produce high GABA levels in germinated brown rice.

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A new, sensitive, and selective high-performance liquid chromatography-tandem mass spectrometric method (HPLC-MS/MS) has been developed for the quantification of six flavonoids (sophoricoside, genistin, genistein, rutin, quercetin, and kaempferol) in rat bile and urine. The sample pretreatment was simple by liquid-liquid extraction. Sulfamethalazole was used as internal standard (IS). During method development, the effect of extraction volume, mobile phase composition, column temperature, and injection volume were varied to optimize sensitivity and achieve a run time as short as possible. Chromatographic separation was accomplished on a C18 column with a simple linear gradient elution within 9 min. Full validation of the assay was in accordance with the requirement of the validation of the method in vivo and implemented including specificity, linearity, accuracy, precision, recovery, and matrix effect. This is the first report on determination of the major flavones in rat bile and urine after oral administration of Fructus Sophorae extract. The method has been used successfully in excretion studies of six major flavonoids in rat bile and urine.

Open access
Acta Alimentaria
Authors:
J.J. Lin
,
Q.H. Meng
,
Z.F. Wu
,
S.Y. Pei
,
P. Tian
,
X. Huang
,
Z.Q. Qiu
,
H.J. Chang
,
C.Y. Ni
,
Y.Q. Huang
, and
Y. Li

Abstract

This paper explores the prediction of the soluble solid content (SSC) in the visible and near-infrared (400–1,000 nm) regions of Baise mango. Hyperspectral images of Baise mangoes with wavelengths of 400–1,000 nm were obtained using a hyperspectral imaging system. Multiple scatter correction (MSC) was chosen to remove the effect of noise on the accuracy of the partial least squares (PLS) regression model. On this basis, the characteristic wavelengths of mango SSC were selected using the competitive adaptive reweighted sampling (CARS), genetic algorithm (GA), uninformative variable elimination (UVE), and combined CARS + GA-SPA, CARS + UVE-SPA, and GA + UVE-SPA characteristic wavelength methods. The results show that the combined MSC-CARS + GA-SPA-PLS algorithm can reduce redundant information and improve the computational efficiency, so it is an effective method to predict the SSC of mangoes.

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As one of the world’s earliest domesticated crops, barley is a model species for the study of evolution and domestication. Domestication is an evolutionary process whereby a population adapts, through selection; to new environments created by human cultivation. We describe the genome-scanning of molecular diversity to assess the evolution of barley in the Tibetan Plateau. We used 667 Diversity Arrays Technology (DArT) markers to genotype 185 barley landraces and wild barley accessions from the Tibetan Plateau. Genetic diversity in wild barley was greater than in landraces at both genome and chromosome levels, except for chromosome 3H. Landraces and wild barley accessions were clearly differentiated genetically, but a limited degree of introgression was still evident. Significant differences in diversity between barley subspecies at the chromosome level were observed for genes known to be related to physiological and phenotypical traits, disease resistance, abiotic stress tolerance, malting quality and agronomic traits. Selection on the genome of six-rowed naked barley has shown clear multiple targets related to both its specific end-use and the extreme environment in Tibet. Our data provide a platform to identify the genes and genetic mechanisms that underlie phenotypic changes, and provide lists of candidate domestication genes for modified breeding strategies.

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