The International journal of applied radiation and isotopes最新文献

The preparation of the ^99mTcN-complexes of gluconate, EHDP, HIDA and PIPIDA by substitution reactions of ^99mTcNCl₄⁻ is described. Studies of the distribution of these complexes in mice indicate that the presence of the Tc-nitrido group significantly alters the biological properties of the ^99mTc-complexes formed using these ligands. Results suggest that the ^99mTcN-complexes of these ligands are labile and undergo some ligand exchange in vivo.

In this paper we report the successful labelling of cryptolepine with ¹³¹I using the chloramine T method. Quality control by ITLC of the labelled product showed 80% labelling but when the mixture was equilibrated with some amberlite (Cl⁻) anion resin to exchange the excess free iodide, the radiochemical purity was raised to >90%. Preliminary biodistribution in a rat did not show specific localisation of the tracer; rather, rapid clearance from the blood was indicated. It appears that its main excretory pathway is the hepatobiliary tract despite its relatively small molecular weight of 365. Also, despite i.v. administration, an appreciable 8% uptake was found in the stomach at 1 h post injection, indicating the process of enterohepatic reflux. These findings may have some bearings on the antimicrobial property of the plant.

CaF₂ thermoluminescence dosimeters (TDL) were used to measure the apparent absorbed dose due to ¹⁶N-decay radiation, such as is found in nuclear reactor coolant or in air due to the ¹⁶O(n,p)¹⁶N activation by fast neurons. By comparison with an ionization chamber calibrated with a ⁶⁰Co source, it was found that the TLD underestimated the dose for about 7-MeV γ-rays by a factor 1.8, while the ionization chamber reading was low by a factor 2.6 when compared with the calculated dose.

The production and use of radioactive standard sources suitable for the efficiency calibration of Si(Li) and germanium detectors in the energy range from 5 to 40 keV is described. Special attention was given to self absorption which could be reduced to about 1% or less by applying appropriate source preparation procedures.

A number of metal selenides were investigated as target material for the production of ⁷⁵Br by the ⁷⁶Se(p,2n)⁷⁵Br reaction. Ag₂Se, CuAgSe, and Cu₂Se met the rqquirements for an economical and fast production procedure. These selenides were found to be stable during bombardment with 1–4 μA 28 MeV protons (beam dimension 0.4 cm²) and at the dry distillation temperature of 1473 K. A target system was developed for radiobromine production with a 7 μA 28−22 MeV proton beam on Cu₂Se. At EOB the calculated thick target yield is 1.59 GBq/μAh (43 mCi/μAh) and the radionuclidic purity is 98.6%. The radiobromine was separated from Cu₂Se by dry distillation at 1473 K and collected for 80–95% on platinum wool pretreated with CaCl₂. Radiochemical analysis showed the radiobromine to be Br⁻ for 95% and BrO₃⁻ for 5%. The total loss of selenide after irradiation and distillation was found to be less than 0.1%.

An instrument and a method for investigation of root bioactivity in plants injected with ⁷⁵Se are presented. The design of the detection probe is described and its response in soil is surveyed. The scanning of radioactivity in the root system is performed automatically by means of a digital depth control, the function of which is also described. The method has been used for several years at this department and the results of a laboratory test are presented.

The δ¹³C values of 20 breath samples and 10 tank-CO₂ samples (δ¹³C values ranged from −31.3 to +148.9% vs PDB) and the CO₂ concentrations of three breath samples and 10 tank-CO₂ samples were measured with a commercial prototype of a diode-laser i.r. spectrophotometer, MAT I. The results were compared with those obtained by gas-isotope-ratio mass spectrometry and by gas chromatography. Precisions (s_x, n = 10) of 0.2% and 0.6% were calculated for ¹³C/¹²C ratios and CO₂ concentrations, respectively, using the MAT I system.