Advances in the management of radioactive wastes and radionuclide contamination in environmental compartments: a review.

Several anthropogenic activities produce radioactive materials into the environment. According to reports, exposure to high concentrations of radioactive elements such as potassium (40K), uranium (238U and 235U), and thorium (232Th) poses serious health concerns. The scarcity of reviews addressing the occurrence/sources, distribution, and remedial solutions of radioactive contamination in the ecosystems has fueled data collection for this bibliometric survey. In rivers and potable water, reports show that several parts of Europe and Asia have recorded radionuclide concentrations much higher than the permissible level of 1 Bq/L. According to various investigations, activity concentrations of gamma-emitting radioactive elements discovered in soils are higher than the global average crustal values, especially around mining activities. Adsorption technique is the most prevalent remedial method for decontaminating radiochemically polluted sites. However, there is a need to investigate integrated approaches/combination techniques. Although complete radionuclide decontamination utilizing the various technologies is feasible, future research should focus on cost-effectiveness, waste minimization, sustainability, and rapid radionuclide decontamination. Radioactive materials can be harnessed as fuel for nuclear power generation to meet worldwide energy demand. However, proper infrastructure must be put in place to prevent catastrophic disasters.

Development of a computer assisted gantry system for gaining rapid and accurate calyceal access during percutaneous nephrolithotomy.

PURPOSE: To design a simple, cost-effective system for gaining rapid and accurate calyceal access during percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: The design consists of a low-cost, light-weight, portable mechanical gantry with a needle guiding device. Using C-arm fluoroscopy, two images of the contrast-filled renal collecting system are obtained: at 0-degrees (perpendicular to the kidney) and 20-degrees. These images are relayed to a laptop computer containing the software and graphic user interface for selecting the targeted calyx. The software provides numerical settings for the 3 axes of the gantry, which are used to position the needle guiding device. The needle is advanced through the guide to the depth calculated by the software, thus puncturing the targeted calyx. Testing of the system was performed on 2 target types: 1) radiolucent plastic tubes the approximate size of a renal calyx (5 or 10 mm in diameter, 30 mm in length); and 2) foam-occluded, contrast-filled porcine kidneys. RESULTS: Tests using target type 1 with 10 mm diameter (n=14) and 5 mm diameter (n=7) tubes resulted in a 100% targeting success rate, with a mean procedure duration of 10 minutes. Tests using target type 2 (n=2) were both successful, with accurate puncturing of the selected renal calyx, and a mean procedure duration of 15 minutes. CONCLUSIONS: The mechanical gantry system described in this paper is low-cost, portable, light-weight, and simple to set up and operate. C-arm fluoroscopy is limited to two images, thus reducing radiation exposure significantly. Testing of the system showed an extremely high degree of accuracy in gaining precise access to a targeted renal calyx.

DFT and CV data of 4-phenyl-substituted dichloro(bis{2-[1-(phenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})iron(II) coordination compounds.

The data presented in this paper are related to the research article entitled "Synthesis, characterisation and electrochemistry of eight Fe coordination compounds containing substituted 2-(1-(4-R-phenyl-1H-1,2,3-triazol-4-yl)pyridine ligands, R=CH3, OCH3, COOH, F, Cl, CN, H and CF3." (Conradie et al., 2019) [1]. This paper presents electrochemical and density functional theory data of 4-phenyl-substituted dichloro(bis{2-[1-(4-R-phenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})iron(II) compounds, containing differently substituted 2-(1-(4-R-phenyl)-1H-1,2,3-triazol-1-yl)pyridine ligands (L2 - L9) (Tawfiq et al., 2014) [2]. Density functional theory calculated data of five different structural isomers for each compound, consistently show that the title compounds are octahedral and that the isomer with the chloride atoms, the pyridine nitrogens and the triazol nitrogens trans to each other, has the lowest energy. Natural bonding orbital (NBO) data and quantum theory of atoms in molecules (QTAIM) data of dichloro(bis{2-[1-(phenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})iron(II) show origin for the preference of the trans isomer.

Chemical and structural data of (1,2,3-triazol-4-yl)pyridine-containing coordination compounds.

The data presented in this paper are related to the research article entitled "Novel dichloro(bis{2-[1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) coordination compounds of seven transition metals (Mn, Fe, Co, Ni, Cu, Zn and Cd)" (Conradie et al., 2018) [1]. This paper presents characterization and structural data of the 2-(1-(4-methyl-phenyl)-1H-1,2,3-triazol-1-yl)pyridine ligand (L2) (Tawfiq et al., 2014) [2] as well as seven dichloro(bis{2-[1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl-κN3]pyridine-κN})metal(II) coordination compounds, [M(L2)2Cl2], all containing the same ligand but coordinated to different metal ions. The data illustrate the shift in IR, UV/VIS, and NMR (for diamagnetic complexes) peaks when L is coordinated to the metals, as well as the influence of the different metals on the peak positions. Solid state structural data is presented for M = Ni and Zn, while density functional theory calculated energies, structures and optimized coordinates are provided for the lowest energy cis and trans conformations for L2 as well as [M(L2)2Cl2] with M = Mn, Fe, Co, Ni, Cu, Zn and Cd.

Beam experiments with the Grenoble test electron cyclotron resonance ion source at iThemba LABS.

At iThemba Laboratory for Accelerator Based Sciences (iThemba LABS) an electron cyclotron ion source was installed and commissioned. This source is a copy of the Grenoble Test Source (GTS) for the production of highly charged ions. The source is similar to the GTS-LHC at CERN and named GTS2. A collaboration between the Accelerators and Beam Physics Group of CERN and the Accelerator and Engineering Department of iThemba LABS was proposed in which the development of high intensity argon and xenon beams is envisaged. In this paper, we present beam experiments with the GTS2 at iThemba LABS, in which the results of continuous wave and afterglow operation of xenon ion beams with oxygen as supporting gases are presented.

Density functional theory calculations of Rh-ß-diketonato complexes.

Density functional theory (DFT) results on the geometry, energies and charges of selected Rh-ß-diketonato reactants, products and transition states are discussed. Various DFT techniques are used to increase our understanding of the orientation of ligands coordinated to Rh, to identify the lowest energy geometry of possible geometrical isomers and to get a molecular orbital understanding of ground and transition states. Trends and relationships obtained between DFT calculated energies and charges, experimentally measured values and electronic parameters describing the electron donating power of groups and ligands, enable the design of ligands and complexes of specific reactivity.

Observed hydrolysis of fluorine substituted bis(ß-diketonato)-dichlorotitanium(IV) complexes.

Novel fluorine substituted mononuclear Ti(ß-diketonato)2Cl2 complexes have been synthesised and shown to be involved in a partial hydrolysis reaction in solution, in which the hydrolyzed dinuclear {Ti(ß-diketonato)2Cl}2(µ-O) is in equilibrium with the monomer. This is in contrast to the solution behaviour of the non CF3-containing Ti(CH3COCHCOCH3)2Cl2, Ti(PhCOCHCOCH3)2Cl2 and Ti(PhCOCHCOPh)2Cl2 complexes, under the same conditions. Variable temperature ((1)H and (19)F) NMR spectra and X-ray structure analyses reveal that the partially hydrolyzed dinuclear complex exists both in solution and in solid state, bridging through a single µ-oxo bridge and having one labile chloro-ligand per titanium center. Inclusion of electron-withdrawing CF3 groups into the already electron-deficient Ti complexes, led to the formation of {Ti(CF3COCHCOCF3)2Cl}2(µ-O) (dinuclear) and [Ti(CF3COCHCOCF3)2(µ-O)]4 (tetranuclear) complexes in CDCl3 containing trace amounts of water. DFT calculated free energies of hydrolysis support the existence of Ti(CH3COCHCOCH3)2Cl2 as a monomer and Ti(CF3COCHCOCF3)2Cl2 as a equilibrium mixture of the monomer and partially hydrolyzed dinuclear {Ti(ß-diketonato)2Cl}2(µ-O) in CDCl3 solution.

ELISA solid phase: partial denaturation of coating antibody yields a more efficient solid phase.

We have examined conditions which will improve the solid phase in ELISAs for HBsAg and ferritin in human serum. Sheep and rabbit antibodies were used. It was found that pre-exposure of antibody to low pH, 3 M urea and temperatures as high as 82 degrees C will enhance ELISA colour in these assays. Further experiments indicate that these conditions perturb the structure of the antibody molecules and results in the exposure of new hydrophobic regions. It is speculated that these more hydrophobic molecules can bind to regions on the plastic surface normally not coated by non-perturbed molecules.

The interpretation of ELISA results by means of the standard deviation ratio.

An improved sensitivity to low levels of hepatitis B surface antigen (HBsAg) was demonstrated when ELISA results were interpreted by a statistical method. The absorbance of each test well was compared with the mean absorbance of all low-colour test samples. Those wells with an absorbance of more than two standard deviations above the mean were referred for confirmatory tests. Samples containing 1.0 ng/ml of HBsAg were reliably detected by a rapid assay technique (1.5 h). Predictive value analysis showed greater sensitivity than was possible from a direct comparison of test samples with controls.

Natural antibodies to avidin in human serum.

Human serum was found to contain natural antibodies to the egg-white glycoprotein avidin. Of 270 samples tested, all contained antibodies to different extents, mainly of the IgG and IgM classes. Anti-avidin antibodies could be isolated by affinity chromatography.

Rapid purification of HBsAg from human plasma.

A method is described for the rapid isolation of purified HBsAg from infected donor plasma. This method uses polyethylene glycol precipitation and a single isopycnic ultracentrifugation step in which the gradient is formed in situ. It works equally well using a small swingout rotor or a zonal rotor.

Detection of Maedi-Visna virus antibodies using a single fusion transmembrane-core p25 recombinant protein ELISA and a modified receiver-operating characteristic analysis to determine cut-off values.

The core p25 and transmembrane (TM) genes of Maedi-Visna virus (MVV) were cloned individually into the pGEX-2T expression vector. Both proteins were expressed as a combined fusion protein in frame with glutathione S-transferase (GST). The purified recombinant antigens (GST-TM and GST-TM-p25) were used to develop a MVV ELISA. A preliminary assessment of the diagnostic potential of the recombinant antigens (GST-TM and GST-TM-p25) was made by testing the antigens against 46 seropositive and 46 seronegative sheep and comparing the results with a commercial p25 ELISA kit. A two-graph receiver operating characteristic (TG-ROC) analysis program was used to interpret the data. The GST-TM-p25 ELISA was more sensitive than the commercial assay which is based on the p25 antigen alone and more specific than the GST-TM ELISA.

An ELISA procedure for detecting human anti-endotoxin antibodies in serum.

We report an ELISA method suitable for the large-scale screening of blood bank stores to identify those blood units containing high concentrations of antiendotoxin antibodies. In Natal, 8.3% of total units collected had antiendotoxin antibodies at concentrations greater than 40 micrograms/ml, values that may be therapeutically useful. We found that one technician could screen enough samples per year to produce 800 litres of such high-titre plasma.

Radioiodination of murine anti-alpha-foetoprotein E.9 monoclonal antibody and its F(ab')2 fragment for the diagnosis of hepatocellular carcinoma.

The high incidence of hepatocellular carcinoma amongst certain population groups of Southern Africa made feasible the investigation of a radiolabelled monoclonal anti-alpha-foetoprotein as a radioimmunodiagnostic agent for this disease. This paper reports the preclinical trials with monoclonal anti-alpha-foetoprotein E.9 (anti-AFP) and its F(ab')2 fragment after radiolabelling with 131I. Various radioiodinations were tried. The best results were obtained with the lodogen and Bolton-Hunter methods. 131I from only one of the sources tested gave an 131I-labelled anti-AFP with meaningful immunoreactivity. It was shown by means of gamma-camera scans and monitoring of radioactivity in individual organs that 131I-anti-AFP and the 131I-anti-AFP F(ab')2 fragments did not accumulate abnormally in any organ(s) in healthy animals. The correlation in healthy mice of the biodistribution of 125I human IgG to 131I-anti-AFP, and 125I human IgG to 131I-F(ab')2 was good. Human hepatoma xenografts in athymic mice showed uptake of 131I-anti-AFP and the 131I-F(ab')2 fragment. The uptake of 131I-F(ab')2 was improved by liver background subtraction. There was correlation between circulatory alpha-foetoprotein concentrations and tumour uptake of 131I-F(ab')2 in tumour-bearing athymic mice and a definite relationship was found between tumour size and radiolabelled antibody and the F(ab')2 fragment. After the biological action of the 131I-anti-AFP and the 131I-F(ab')2 fragment was known, sterile pyrogen-free consignments were supplied for clinical trials in humans on a regular basis.

First commissioning results with the Grenoble test electron cyclotron resonance ion source at iThemba LABS.

iThemba Laboratory for Accelerator Based Science (iThemba LABS) is a multi-disciplinary accelerator facility. One of its main activities is the operation of a separated-sector cyclotron with a K-value of 200, which provides beams of various ion species. These beams are used for fundamental nuclear physics research in the intermediate energy region, radioisotope production, and medical physics applications. Due to the requirements of nuclear physics for new ion species and higher energies, the decision was made to install a copy of the so-called Grenoble test source (GTS) at iThemba LABS. In this paper, we will report on the experimental setup and the first results obtained with the GTS2 at iThemba LABS.

Development of a computer assisted gantry system for gaining rapid and accurate calyceal access during percutaneous nephrolithotomy

PURPOSE: To design a simple, cost-effective system for gaining rapid and accurate calyceal access during percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: The design consists of a low-cost, light-weight, portable mechanical gantry with a needle guiding device. Using C-arm fluoroscopy, two images of the contrast-filled renal collecting system are obtained: at 0-degrees (perpendicular to the kidney) and 20-degrees. These images are relayed to a laptop computer containing the software and graphic user interface for selecting the targeted calyx. The software provides numerical settings for the 3 axes of the gantry, which are used to position the needle guiding device. The needle is advanced through the guide to the depth calculated by the software, thus puncturing the targeted calyx. Testing of the system was performed on 2 target types: 1) radiolucent plastic tubes the approximate size of a renal calyx (5 or 10 mm in diameter, 30 mm in length); and 2) foam-occluded, contrast-filled porcine kidneys. RESULTS: Tests using target type 1 with 10 mm diameter (n = 14) and 5 mm diameter (n = 7) tubes resulted in a 100 percent targeting success rate, with a mean procedure duration of 10 minutes. Tests using target type 2 (n = 2) were both successful, with accurate puncturing of the selected renal calyx, and a mean procedure duration of 15 minutes. CONCLUSIONS: The mechanical gantry system described in this paper is low-cost, portable, light-weight, and simple to set up and operate. C-arm fluoroscopy is limited to two images, thus reducing radiation exposure significantly. Testing of the system showed an extremely high degree of accuracy in gaining precise access to a targeted renal calyx.

Quantitation of serum ferritin by enzyme-linked immunosorbent assay (ELISA).

We have developed an enzyme-linked immunosorbent assay (ELISA) for determining ferritin in serum. In this assay the solid phase consists of rabbit antiferritin IgG adsorbed onto PVC microtitre plates. Ferritin from standards or samples binds to the solid phase and is then detected by a conjugate consisting of rabbit antiferritin-IgG and horseradish peroxidase. The entire assay can be performed in 5 hours, with good precision. The assay has a useful range of 1 to 64 microgram/l and serum samples therefore have to be diluted 10-fold. The coefficient of variation for 6 samples (1,5-40,1 microgram/l) assayed 12 times on the same plate varied from 4% to 9% (intra-assay). When these 6 samples were assayed on different plates and on different days by two technicians the coefficients of variation varied from 4% to 11% (inter-assay). The lowest detectable level of ferritin was 1 microgram/l. Forty-six serum samples from blood donors were assayed by the method described here (gamma) and compared with results obtained by RIA (alpha). The resulting regression equation was gamma = 1,073 alpha -- 4,33; r = 0,984.

The importance of quaternary structure in the expression of the C1-binding site of IgM.

The ability of C1 to bind to the Fc5mu-fragment of a monoclonal IgM was determined by means of a haemolytic C1-inhibition assay. Fc5mu fragments were produced by trypsin digestion at five different temperatures ranging from 54-62 degrees (2 degrees increments) and were purified by immunoadsorption through a column of monospecific anti-Fabmu and by molecular exclusion chromatography. Analytical ultracentrifugation showed the final preparations to be free of aggregates. A plot of mug Fc5mu required to inhibit 50% of available C1 versus temperatures of production of the fragment yielded a curve with a minimum at 58-60 degrees. Upon mild reduction and alkylation of these Fc5mu fragments their C1-fixing capacity became approximately the same irrespective of temperature of production. Fc5mu was also prepared at 25 degrees in the presence of 5 M urea, purified by immunoadsorption as before and aliquots then exposed to temperatures ranging from 40-70 degrees (5 degrees increments) for 15 min. After aggregates had been removed by chromatography a similar minimum in C1-fixation was again observed at 60 degrees. Reduction and alkylation once more abolished these differences. Fc5mu and its reduced and alkylated subunits, produced at 60 degrees and then exposed to various concentrations of urea (0-7 M) for 24 hd did not yield a minimum in C1 fixation. Reduced and alkylated Fcmu incubated at various temperatures (40-70 degrees) also did not fix C1 differentially. Examination in the near and far u.v. region of the circular dichroism spectra of different Fc5mu preparations showed a gradual loss of structure associated with restricted aromatic chromophores and secondary (beta) structure with increased temperature. Urea denaturation had a more pronounced and irreversible effect on Fc5 mu conformation. These changes could not be correlated with the CU-fixation patterns observed. It would therefore appear that elevated temperatures induce a static change in the pentameric FC-part of IgM which in turn directly influences or modulates the availability of the C1-binding site. The importance of disulphide bonds in maintaining these temperature-induced changes in Fc5mu was also indicated.