Search Results

You are looking at 1 - 10 of 13 items for

  • Author or Editor: C. Chai x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

A simple method for simultaneous determination of inorganic and total mercury contents in human hair by neutron activation analysis (NAA) has been developed. The method is based on the selective extraction of methylmercury from hair by hydrochloric acid. Thus, the residual phase containing inorganic mercury can be determined by NAA. Further, the methylmercury contents in hair samples are easily calculated by subtracting the inorganic mercury contribution from the total Hg simultaneously given by INAA. Several reference materials of human hair, including IAEA hair RM 085 and 086, Chinese hair RMs GBW 09101 and 07601, were analyzed by this method. Our results show that the method is reliable.

Restricted access

Abstract  

Contamination and adsorption of trace elements during storage of natural water samples in polyethylene containers have been studied. Variations of concentrations of 29 elements in pH=1.5 natural water samples stored in polyethylene bottles for 15 and 30 days respectively were determined by the method of freeze-drying preconcentration and NAA. The percentage adsorption loss of radioactive indicators60Co,124Sb,65Zn,75Se,134Cs and46Sc in the pH=1.5–8.0 reservoir water, tap water and distilled water stored for 1–2 months were also determined. The optimized storage condition for natural water is obtained.

Restricted access

Abstract  

Molecular activation analysis (MAA) of iridium in geological samples, based on a combination of a newly-developed chemical sequential dissolution method and radiochemical and instrumental NAA, was described to study the distribution pattern and chemical species of iridium in various fractions (soluble carbonate, metal, sulfide, oxide, silicate and acid-insoluble residue) of geological boundary samples, meteorites, ultrabasic rock and volcanic lava. The correlations of Ir with Au, Os, siderophile, chalcophile and lithophile elements were discussed. In addition, the role of kerogen and noble-nugget in the Ir enrichment was scrutinized. The MAA results of Ir favors a mixed effect of asteroid impact, volcanic eruption and post-depositional redistribution to interpret the extant Ir anomaly at Cretaceous-Tertiary boundary layer.

Restricted access

Abstract  

Twenty-seven pairs of head hair from mothers and their new-born infants were collected at the time of delivery in a hospital in Beijing. The total mercury content in the hair samples was determined by INAA. The correlation between mercury content in hair of mothers and their new-born infants has been investigated. In addition, the change of Hg content in pregnant women's hair during their pregnancy was also studied by INAA and SRXRF. The results indicate a significant positive correlation between the mercury content in maternal and infant head hairs (r=+0.862, p<0.001). The average content of Hg in infant and maternal hairs was 0.66±0.31 g/g and 0.59±0.25 g/g, respectively. The infant level exceeded the maternal by 12%. The Hg content in maternal head hair gradually reduced during pregnancy. Further, the methylmercury (Me–Hg) content in 3 maternal hair samples was analyzed by GC(EC). The Me–Hg was in accordance with the total mercury content. Thus a conclusion can be drawn that damage to the infant from Hg occurred in the early stages of pregnancy.

Restricted access

Enteritis is a serious problem for patients having received abdominal radiation. This study was to investigate whether zinc affected intestinal injury induced by the radiation. ICR mice were divided randomly into three groups and treated with one of three different compounds. Two of the compounds contained zinc (gluconate and amino acid chelated with bovin prostate extract) and one was water. One week after receiving the treatment, they were irradiated with 6 or 10 Gy at the abdominal region. One, 2, and 4 weeks after the irradiation the animals were sacrificed to examine the histological changes in the intestinal mucosa. The apoptotic cell numbers were found to be significantly higher after irradiation. The number of the apoptotic cells increased with increasing radiation doses. In this study we found that zinc appears to have the capability to lower the occurrence of apoptosis in the intestinal mucosa, thus protecting intestinal mucosa from injuries. Based on this finding, it would be reasonable to suggest that zinc could be used as food supplements in patients with cancer receiving radiotherapy in a hope to reduce radiation induced toxicity.

Restricted access

Abstract  

Two different radiochemical procedures were developed: chelate ion resin exchange and amine solvent extraction. Two kinds of new Chinese chelate resins (NANKAI-3926 and BEI-5) and a new longchain primary amine N1923 were compared with the Srafion NMRR and the tertiary amine N235 in absorption performance of noble metals, respectively. Influences of various experimental conditions, e. g. sample digestion, acidity, equilibrium time, as well as elution of noble metals, on analytical sensitivity and chemical yield were discussed. Combining with neutron activation, the radiochemical separation procedures developed were used to determine the noble metal contents in the geological samples from Permian/Triassic boundary in South China.

Restricted access

Abstract  

Ca-47 radioactive tracer was used to determine the phamocodynamics, distribution pattern, absorption and bioavailability of a new type calcium supplement in rabbit prepared by plasma technology. Our results indicate that calcium from the new nutrient is mainly deposited in bone 6 or 7 days after oral administration. The absorption rate of this new calcium preparation is estimated to be 30–40 %.

Restricted access

Abstract  

Although Ir anomaly has been discovered in a number of C/T boundaries in the world, no positive results of this anomaly in Permian/Triassic (P/Tr) boundary were given. There are many well-developed P/T sections in South China. One of representative sections is located at the Baoqing quarry, Meishan Town, Changxin County, Zhejiang Province. Ir, Os, Re, Au, Pt, Cu and Mo were determined by the radiochemical procedure developed in our laboratory. (1) Besides those accessible by INAA. The results reveal that the refractory siderophile and other chalcophile elements have certain enrichment near and at the boundary layer. However, the Ir/Au and other element abundance ratios fail to accord with the extraterrestrial values. The nature of the boundary event was discussed in terms of elemental geochemistry.

Restricted access

Abstract  

The concentrations of 14 elements, including Ir, Au, Co, Cr, Fe, Sr, Rb, K, Ta, Zn, Sb, Ba, Sc and Se, in the Wuxi fallen ice were determined by neutron activation analysis. The experimental results show that the relative concentration ratios of Ir/Co, Ir/Cr and Ir/Sc etc. in the ice water (0.0069, 0.00024 and 0.11, respectively) are quite close to those of Type C1 chondrite (0.0102, 0.00021 and 0.092, respectively), which implies that the fallen ice might be a piece of extraterrestrial substance.

Restricted access

Abstract  

Chemical elemental compositions of some silicate, magnetic and glass spherules were investigated with INAA. The elements determined include Os, Ir, Ni, Co, Fe, Cr, Au, La, Ce, Sm, Eu, Yb, Lu and Sc etc. The elemental correlation, as well as their enrichment (or depletion) factors relative to Cl chondrite were examined. The high concentrations of the refractory siderophile elements contained in these spherules support the proposal that they originate from extraterrestrial substances. Some useful chemical criteria for identifying the sources of silicate, magnetic and glass spherules are put forward.

Restricted access