Assessment of a compton-suppressed spectrometer for measurement of radioactive xenon isotopes.

Airborne radionuclide monitoring is considered to be the most certain way to detect a clandestine nuclear weapon test. The activity concentration of radioxenon samples collected by the radionuclide stations of the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) is generally performed at the low-level, hence it is necessary to improve the detection sensitivity of the radioactivity measuring apparatus for radionuclide monitoring. The Compton-suppressed spectrometer (CSS) has the advantage of reducing the background and improving the sensitivity in the environmental level measurement. Therefore, the measurement of the relevant radioxenon sample at the environmental level is feasible by using CSS. To assess the performance of CSS for radioxenon measurements, the Compton-suppressed and unsuppressed spectra of the 133Xe and 127Xe samples have been acquired, and subsequently, the information of the full energy peaks (FEP) in the spectra were compared. The assessment indicates that CSS can provide high sensitivity, simple operation, and straightforward activity determination, and it can be regarded as an appropriate apparatus in the radioxenon measurement.

Measurement of the gamma-ray emission probability of 131mXe.

131mXe has been standardized by means of an internal gas proportional counting system, employing a length-compensated method. The activity concentration of 131mXe was measured with a relative standard uncertainty of 0.6%. The gamma-ray emission probability of 131mXe was then determined as 0.0196(4) by measuring a standard sample of 131mXe using a high-purity germanium (HPGe) spectrometer.

Effect of vacuum sealing drainage in dermatoplasty of large area of cutaneous defects.

OBJECTIVES: To investigate the clinical effect of vacuum sealing drainage in dermatoplasty of large area of cutaneous defects in comparison to conventional treatment. METHODS: 80 patients with large area of cutaneous defects were enrolled in this study, and they had received superficial thickness dermatoplasty. Then these patients were randomly divided into two groups based on follow-up treatments: vacuum sealing drainage (defined as group A, 40 cases) and conventional treatment (defined as group B, 40 cases). After operation, all the patients received similar hospital stay, antibiotics administration, swelling elimination and wound closure in these two groups. RESULTS: No significant difference was observed in terms of the baseline characteristics between the two groups, including areas of cutaneous defects. Compared with conventional treatment group, the healing time of dermatoplasty was reduced significantly in vacuum sealing drainage group. Meanwhile, the rate of survival of dermatoplasty was better, and the rate of wound infection was lower in vacuum sealing drainage group than conventional treatment group. CONCLUSION: Vacuum sealing drainage is effective in treatment with large area of cutaneous defects combined with dermatoplasty, which had better clinical outcomes than conventional therapy.

Determination of 226Ra Activity Using Gamma Spectrometry with 226Ra-222Rn Disequilibrium.

Radium-226 (Ra) activity is normally determined indirectly by gamma spectrometry, in particular by measuring the characteristic γ-ray emitted from its progeny (Pb and Bi) when Ra-Rn secular equilibrium is reached. This article describes a measurement method involving the measurement of Pb ingrowth. The activity of Ra determined by this method agrees with that measured after Ra-Rn equilibrium. The method of Pb ingrowth allows rapid and sufficiently accurate determination of Ra activity without the need to wait for Ra-Rn equilibrium.

Direct immobilization of glucose oxidase in magnetic mesoporous bioactive glasses.

Direct immobilization of enzymes on the bioactive glasses is conceptually a completely new strategy. We find that the Fe2O3-CaO-SiO2-P2O5 magnetic mesoporous bioactive glass (MMBG) is an ideal immobilization matrix for glucose oxidase (GOD). Its unique chemical surface properties and open mesopores enhance the catalytic activity of directly immobilized GOD. In this paper, MMBG was synthesized using the sol-gel approach and polyethylene glycol (PEG) as template at 700 °C. GOD molecules were spontaneously entrapped inside the open mesoporous structure and onto the surface of MMBG via iron ion binding, their activity was not impaired. The substrates and products can access and diffuse freely through the open mesoporous structure in MMBG. This study is focused on understanding the formation mechanism of MMBG, the immobilized mechanism of GOD and the magnetic separation mechanism of MMBG from the reaction medium. The MMBG can be utilized in the design of a solid support for any enzyme for bioconversion, bioremediation, and biosensors.