X-ray fluorescence in some rare earth and high Z elements excited by 661.6 keV γ-rays

The K-shell X-ray fluorescence cross sections are determined experimentally for 10 elements such as Pb, Hg, Ir, W, Lu, Tm, Dy, Tb, Gd and Nd at excitation energy of 661.6 keV associated with γ-rays of ¹³⁷Cs radioisotope. The technique employed involves the measurement of total intensity of fluorescent K X-rays that follow the photoeffect absorption of a known flux of γ-rays using a well type Nal(Tl) detector. The obtained results are compared with the available theoretical values and other measured values.     

MRI detection of tumor in mouse lung using partial liquid ventilation with a perfluorocarbon-in-water emulsion

Transverse relaxation time (T(2*))-weighted (1)H-MRI of mouse lungs has been performed using partial liquid ventilation (PLV) with a perfluorocarbon (PFC)-in-water emulsion as a contrast modality for lung MRI. Significant sensitivity enhancement in MRI of mouse lungs has been demonstrated with the protocol. The results show that the T(2*) value in lung is approximately proportional to the infusion dose up to a dose of 5 ml/kg body weight (BW) (4.5 g PFC/kg BW) and becomes essentially constant beyond this dosage. T(2*) maps of lungs have been calculated and T(2*) in lungs is in the range of 10-35 ms with this technique, which is an order of magnitude greater than the T(2*) value of mouse lungs without using a PFC-in-water emulsion. T(2*)-weighted (1)H-MR images of mouse lungs have been obtained with good quality under our experimental conditions. We have applied this technique to detect tumors in mouse lungs. Our technique can detect small lung tumors of B16 melanoma, about 1 mm in diameter, in mice. With its significant MR sensitivity enhancement and technical simplicity, T(2*)-weighted (1)H-MRI using PLV with PFC-in-water emulsion offers a promising approach to investigate lung cancers using rodent models.     

Pellet freezing of in vitro produced bovine embryos using dry ice

In vitro produced bovine embryos were frozen by pellet freezing or vitrification method. In the pellet freezing method, the embryos were cooled on the dry ice and then frozen as pellets. At warming, the pellets were immersed directly into 0.5 M sucrose. The survival rates of blastocysts frozen by the pellet freezing method were higher (P<0.01) in 40% ethylene glycol (EG) than those in the lower concentrations (20 and 30% EG). Higher survival rates of blastocysts frozen by the pellet freezing method were obtained but the development rates did not differ, as compared with those by the vitrification method. There were no significant differences between the pellet freezing and vitrification method in the frequencies of post-thaw survival of hatched blastocysts. These results demonstrate that the pellet freezing method using dry ice can be used successfully for the cryopreservation of blastocysts.