Prematurely condensed chromosome fragments in human lymphocytes induced by high doses of high-linear-energy-transfer irradiation

This study provides a useful biodosimetry protocol for radiation accidents that involve high doses of heavy particle radiation. Human peripheral blood lymphocytes (PBLs) were irradiated in vitro with high doses (5–50 Gy) of charged heavy-ion particles (carbon ions, at an effective linear-energy-transfer (LET) of 34.6 keV/ m), and were then stimulated to obtain dividing cells. PBLs were treated with 100nMcalyculin A to force chromosomes to condense prematurely, and chromosome spreads were obtained and stained with Giemsa. The G2 prematurely condensed chromosome (G2-PCC) index and the number of G2-PCC including fragments (G2-PCC-Fs) per cell for each radiation dose point were scored. Dose-effect relationships were obtained by plotting the G2-PCC indices or G2-PCC-Fs numbers against radiation doses. The G2-PCC index was greater than 5% up to doses of 15 Gy; even after a 30Gy radiation dose, the index was 1 to 2%. At doses higher than 30 Gy, however, the G2-PCC indices were close to zero. The number of G2-PCC-Fs increased steeply for radiation doses up to 30 Gy at a rate of 1.07 Gy−1. At doses higher than 30 Gy, the numbers of G2-PCC-Fs could not be accurately indexed because of the limited numbers of cells for analysis. Therefore, the number of G2-PCC-Fs could be used to estimate radiation doses up to 30 Gy. In addition, a G2-PCC index close to zero could be used as an indicator for radiation doses greater than 40 Gy.

Cross-correlation of excitation functions for different fragments and different scattering angles in Al-27(F-19, x)y reactions

Excitation functions have been measured for different projectile-like fragments produced in Al-27(F-19,x)y reactions at incident energies from 110.25 to 118.75 MeV in 250 keV steps. Strong cross section fluctuations of the excitation functions are observed. The cross- correlation coefficients of the excitation functions for different atomic number Z and for different scattering angle theta(cm) have been deduced. These coefficients are much larger than the statistical theoretical calculated ones. This indicates that there are strong correlations between different exit channels in the dissipative heavy ion Collision of Al-27(F-19,x)y.

Highly efficient separation of dsDNA fragments on glass chips by using an ultralow viscosity sieving matrix

A novel protocol has been established to separate dsDNA fragments with high efficiency on glass chips by using an ultralow viscosity sieving matrix with added glucose. Low-molecular-weight hydroxypropylmethylcellulose (HPMC), with a viscosity nearly equivalent to that of water, was used to electrophoretically separate fluorescent inter-calator-labeled double-stranded DNA (dsDNA) fragments on microfluidic glass chips. In comparison with conventional sieving protocols, low-molecular-weight HPMC as sieving matrix could result in reduced running cost and analysis time, in addition to a comparable separation efficiency of dsDNA fragments. In this paper, the addition of glucose was investigated to enhance the separation of DNA in the lowest viscosity polymer evaluated. The effect of staining dye and field strength were also evaluated. At an applied electric field strength of 200 V/cm, satisfactory resolution of the PBR322/HaeIII DNA marker could be achieved within 4 min by using 2% HPMC-5 with 6% glucose added. Coelectrophoresing PCR product along with phiX174/HaeIII DNA sizing marker was also demonstrated by using the ultralow viscosity HPMC-5 solution on a glass chip.

Relationships between precipitation, soil water and groundwater at Chongling catchment with the typical vegetation cover in the Taihang mountainous region, China

Vegetation cover plays an important role in the process of evaporation and infiltration. To explore the relationships between precipitation, soil water and groundwater in Taihang mountainous region, China, precipitation, soil water and water table were observed from 2004 to 2006, and precipitation, soil water and groundwater were sampled in 2004 and 2005 for oxygen-18 and deuterium analysis at Chongling catchment. The soil water was sampled at three sites covered by grass (Carex humilis and Carex lanceolata), acacia and arborvitae respectively. Precipitation is mainly concentrated in rainy seasons and has no significant spatial variance in study area. The stable isotopic compositions are enriched in precipitation and soil water due to the evaporation. The analysis of soil water potential and isotopic profiles shows that evaporation of soil water under arborvitae cover is weaker than under grass and acacia, while soil water evaporation under grass and acacia showed no significant difference. Both delta O-18 profiles and soil water potential dynamics reveal that the soil under acacia allows the most rapid infiltration rate, which may be related to preferential flow. In the process of infiltration after a rainstorm, antecedent water still takes up over 30% of water in the topsoil. The soil water between depths of 0-115 cm under grass has a residence time of about 20 days in the rainy season. Groundwater recharge from precipitation mainly occurs in the rainy season, especially when rainstorms or successive heavy rain events happen.

Hole-transporting polymers containing carbazol-3,9-diyl and 1,4-phenylene fragments in the main chain

New carbazole-based polymers, which contain various content of electro-active fragments in the main chain connected via alkylene spacers, have been synthesized by Ni(0)-catalyzed Yamamoto-type aryl-aryl coupling reactions. These compounds represent amorphous materials of high thermal stability with glass-transition temperatures of 139-151 degrees C and thermal decomposition starting at temperatures above 400 degrees C. UV-vis absorption and photoluminescence emission spectra of the materials confirmed that the conjugated segments in the macromolecules are rather short.