Dual Separation of Krypton and Argon from Environmental Samples for Radioisotope Dating.

The noble gas radioisotopes 85Kr, 81Kr, and 39Ar are nearly ideal environmental tracers because of their chemical inertness and simple transport mechanisms. Recent advances in Atom Trap Trace Analysis have enabled measurements of 85Kr and 81Kr using 10-20 kg of water or ice, and 39Ar in only a few kilograms, making these tracers available to be applied in the earth sciences on a large-scale. To meet the resulting increase in demand, we have developed an automated process for the dual separation of krypton and argon from environmental samples based on titanium gettering and gas chromatography. 0.5-4 L STP air samples have been purified, demonstrating purities and recoveries of >90% for krypton and >99% for argon within 90-120 min of processing time. Samples of high methane admixtures, a challenge regularly encountered in groundwater applications, have been purified by exploiting the full potential of titanium gettering at high temperatures (>1000 °C). Samples with 0.4-48 L STP of methane admixture are processed in 2-5 h without compromising purity or recovery. The applicability of the purification system is further demonstrated using actual groundwater samples with carbon dioxide and methane content in the extracted gas up to 16 L STP and 42 L STP, respectively.

[The influence of miR-21 on HK-2 EMT cells induced by TGF-beta 1].

OBJECTIVE: To investigate the effect of the miR-21 and its target mRNA in renal tubular epithelial mesenchymal transformation (EMT) model induced by transformation growth factor-ß1(TGF-ß1) in human renal tubular epithelial (HK-2) cells. METHODS: HK-2 cells were divided into 6 groups:normal control group, TGF-ß1 group, miR-21 mimic negative group, miR-21 mimic group, miR-21 inhibitor negative group and miR-21 inhibitor group. EMT model was established in HK-2 cells induced by 4 ng/ml TGF-ß1. The level of miR-21, the mRNA and protein expression of EMT related factors were detected. MiR-21 mimic plasmid and miR-21 inhibitor plasmid were transfected into HK-2 cells that treated with TGF-ß1 respectively using liposome transfection technique. Observe the impact of overexpression or inhibition expression of miR-21 on the mRNA and protein expression of EMT related factors and PTEN. RESULTS: ①Compared with the normal group, the level of miR-21 was significantly increased in model group (P<0.05), the mRNA and protein expression levels of epithelial cells marker E-cadherin was significantly decreased (P<0.01), while the mRNA and protein levels of mesenchymal cells marker α-SMA was significantly increased (P<0.05,P<0.01). ②Compared with the miR-21 mimic negative group, the level of miR-21 in miR-21 mimic group increased significantly (P<0.01), the mRNA and protein expression levels of PTEN and E-cadherin decreased significantly (P<0.05,P<0.01), the mRNA and protein levels of α-SMA increased significantly (P<0.05,P<0.01). Compared with the miR-21 inhibitor negative control group, the level of miR-21 in miR-21 inhibitor group decreased significantly (P<0.01), the mRNA and protein expression levels of PTEN and E-cadherin increased significantly (P<0.05,P<0.01), the mRNA and protein levels of α-SMA decreased significantly (P<0.05,P<0.01). CONCLUSIONS: MiR-21 may play an important role in EMT induced by TGF-ß1 in HK-2 cells and regulate the expression of EMT related factors its target gene PTEN.