Experimental study of tritium activity concentration in cooling water of heavy ion research facility in Lanzhou

Cooling water of Heavy Ion Research Facility in Lanzhou is the media of choice for absorbing heat generated by a multitude of accelerator components. During the operation, tritium is produced by the secondary neutrons in the accelerator loop of accelerator cooling water, which is uniformly distributed in the water system in the form of hydrogen tritium oxide. The purpose of this study is to establish a rigorous method to measure the low levels of tritium in the accelerator cooling water system. The cooling water samples of Sector Focusing Cyclotron and Separated Sector Cyclotron of Heavy Ion Research Facility in Lanzhou, as well as the natural levels of tritium, were measured successfully, using Quantulus1220 ultra-low-level background liquid scintillation spectrometer. The electrolytic enrichment method was employed to measure the tritium activity concentrations of the cooling water samples. Moreover, the minimum detectable activity concentration and the counting rate efficiency curve of the liquid scintillation spectrometer were obtained to ensure reliability. In this work, we provide a reference to establish the related standards and specifications for monitoring the tritium levels in heavy-ion accelerator cooling water system.

Preparation of Carbon-14 Labeled 2-(2-mercaptoacetamido)-3-phenylpropanoic Acid as Metallo-beta-lactamases Inhibitor (MBLI), for Coadministration with Beta-lactam Antibiotics

Aim and Objective: Bacteria could become resistant to β-lactam antibiotics through production of β- lactamase enzymes like metallo-β-lactamase. 2-(2-mercaptoacetamido)-3-phenylpropanoic acid was reported as a model inhibitor for this enzyme. In order to elucidate the mechanism of action in the body’s internal environment, preparation of a labeled version of 2-(2-mercaptoacetamido)-3-phenylpropanoic acid finds importance. In this regard, we report a convenient synthetic pathway for preparation of carbon-14 labeled 2-(2- mercaptoacetamido)-3-phenylpropanoic acid. Materials and Methods: This study was initiated by using non-radioactive materials. Then, necessary characterization was performed after each of the reactions. Finally, the synthesis steps were continued to produce the target labeled product. For labeled products, the process was started from benzoic acid-[carboxyl- 14C] which has been prepared from barium 14C-carbonate. Chromatography column and NMR spectroscopy were used for purifications and identification of desired products, respectively. Barium [14C]carbonate was purchased from Amersham Pharmacia Biotech and was converted to [14C]benzyl bromide. Radioactivity was determined using liquid scintillation spectrometer. Results: We used [14C]PhCH2Br which was previously prepared from [14C]BaCO3, H2SO4, PhMgI, LAH and HBr, respectively. To neutralize the [14C]phenylalanine in acidic condition and to reach an isoelectric point of phenylalanine (pH = 5.48), Pb(OH)2 was used. Next, thioacetic acid and bromo acetic acid were used to prepare (acetylthio) acetic acid. A peptide coupling reagent was used in this stage to facilitating amide bond formation reaction between [14C]methyl-2-amino-3-phenyl propanoate hydrochloride and (acetylthio) acetic acid. Conclusion: Carbon-14 labeled 2-(2-mercaptoacetamido)-3-phenylpropanoic acid via radioactive phenylalanine was obtained with overall chemical yield 73% and radioactivity 65.3 nCi. The labeled target product will be used for in vivo pharmacological studies.

Gross alpha and beta activities in drinking water from Goiás state, Brazil

Detection of gross alpha and beta radioactivity is important for a quick surveying of both natural and anthropogenic radioactivity in water. Furthermore, gross alpha and gross beta parameters are included in Brazilian legislation on quality of drinking water. In this work, a low background liquid scintillation spectrometer was used to simultaneously determine gross alpha and gross beta in samples of the public water supplies in the state of Goiás, Brazil, during 2010-2015. Sample preparation involved evaporation to concentrate the sample ten-fold. The results indicate that the water meets the radioactivity standards required by the regulations MS 2914/2011 of the Brazilian Department of Health. Concerning the high level of censored observations, a statistical treatment of data was conducted by using analysis methods of censored data to provide a reference value of the gross alpha and beta radioactivity in drinking water from the state of Goiás. The estimated typical activities are very low, 0.030 Bq.L-1 and 0.058 Bq.L-1, for gross alpha and gross beta, respectively.

Translocation and Root Exudation of Glyphosate by Urochloa brizantha and its Transport on Sugarcane and Citrus Seedlings

ABSTRACT: Glyphosate is easily exuded by the roots of plants. However, there is still some lack of information in the scientific literature as to whether Urochloa brizantha is capable of exuding glyphosate to influence the growth of crops such as sugarcane and citrus. Thus, the objective of this research was to evaluate the translocation and root exudation of 14C-glyphosate by U. brizantha and its transport in sugarcane and citrus. Sugarcane seedlings, varieties SP80-1842, and citrus ‘Limão Rosa’ (Citrus limonia L. Osbeck) were cultivated with U. brizantha around the seedlings. Using a microsphere, 14C-glyphosate was applied on the leaves of U. brizantha. The plants were cultured for 12 days after treatment (DAT). The radioactivity of the herbicide was evaluated by liquid scintillation spectrometer, after oxidizing the soil and parts of the plants (leaves, culms and roots) of U. brizantha, sugarcane and citrus. The highest amount of glyphosate was detected in the U. brizantha leaves, where the applications were carried out, regardless of the culture studied. Only traces of glyphosate (0.001%) were detected in soil cultivated with sugarcane. On the other hand, in citrus, U. brizantha exuded 9.46% of the glyphosate by the root system in the soil. The total amount of herbicide found in sugarcane and citrus seedlings was only 0.006 and 0.095%, respectively, in all parts of the plant. These concentrations are lower than those required to cause intoxication in those crops. Considering the results, it is possible to state that the translocation of glyphosate in young plants of U. brizantha associated with citrus was higher in relation to sugarcane, and it was not exuded by the root system of the weed with sugarcane, but presented root exudation with citrus, however, the amount did not reach what is necessary to affect the dry mass of the agricultural crops.

The applicability of C-14 measurements in the soil gas for the assessment of leakage out of underground carbon dioxide reservoirs

Poland, due to the ratification of the Kioto Protocol, is obliged to diminish the emission of greenhouse gases. One of the possible solutions of this problem is CO2 sequestration (CCS - carbon capture and storage). Such an option is a priority in the European Union. On the other hand, CO2 sequestration may be potentially risky in the case of gas leakage from underground reservoirs. The most dangerous event may be a sudden release of the gas onto the surface. Therefore, it is very important to know if there is any escape of CO2 from underground gas reservoirs, created as a result of sequestration. Such information is crucial to ensure safety of the population in areas located above geological reservoirs. It is possible to assess the origin of carbon dioxide, if the measurement of radiocarbon 14C concentration in this gas is done. If CO2 contains no 14C, it means, that the origin of the gas is either geological or the gas has been produced as a result of combustion of fossil fuels, like coal. A lot of efforts are focused on the development of monitoring methods to ensure safety of CO2 sequestration in geological formations. A radiometric method has been tested for such a purpose. The main goal of the investigations was to check the application possibility of such a method. The technique is based on the liquid scintillation counting of samples. The gas sample is at first bubbled through the carbon dioxide adsorbent, afterwards the adsorbent is mixed with a dedicated cocktail and measured in a low-background liquid scintillation spectrometer Quantulus. The described method enables measurements of 14C in mine and soil gas samples.

Glyphosate translocation in hairy fleabane (Conyza bonariensis) biotypes

The objective of this work was to evaluate the translocation of glyphosate in C. bonariensis plants resistant and susceptible to that herbicide. The 14C-glyphosate was mixed with commercial gyhphosate (800 g ha-1) and applied on the center of the adaxial face of a third node leaf, using a micro syringe, and adding 10 µL of a solution with specific activity of 1,400 Bq, 45 days after plant emergence. The concentration of the glyphosate translocated in the plant was evaluated at time intervals of 6, 12, 36 and 72 hours after being applied on the application leaf, stem, roots and leaves. Ten hours after treatment application, the distribution of the product in the application leaf, divided into base, center and apex, was also evaluated by measuring the radiation emitted by 14C-glyphosate in a liquid scintillation spectrometer. Greater glyphosate retention was observed in the resistant biotype leaf, approximately 90% of the total absorbed up to 72 hours. In the susceptible biotype, this value was close to 70% in the same period. Susceptible biotype leaves, stem and roots showed greater concentration of glyphosate, indicating greater translocation efficiency in this biotype. In the resistant biotype, the herbicide accumulated in greater quantity at the apex and center of the application leaf, while in the susceptible biotype greater accumulation was observed at the base and center leaf. Thus, it can be stated that the resistance mechanism is related to the differential translocation of this herbicide in the biotypes.

Rehabilitation of the Laboratoire De Carbone 14-Dakar (Senegal) with a Super Low-Level Liquid Scintillation Counting System

Following the passing of Prof Cheikh Anta Diop in 1986, the radiocarbon laboratory (LC14) he created 20 yr earlier at the Institut Francophone d'Afrique Noire (IFAN), Dakar, Senegal, fell into a long hibernation. It took nearly 3 yr to renovate the laboratory and reinstall new equipment in order to return LC14 to full functionality and resume its activity. A new dating system has been implemented around a super low-level liquid scintillation spectrometer from Packard, the Tri-Carb 3170TR/LS, located in an underground room.In this paper, we assess the performance of the dating setup (background level and figure of merit) using known samples from Paris 6 and international standards from the International Atomic Energy Agency (IAEA). After the calibration, the setup was used to study bolé seashells from the Khant area in the northern part of Senegal (West Africa). The aim is to present evidence of the correlation between the transgression of the Nouakchottan (5500 BP) and a few industries in the Khant area. The corresponding ages are difficult to assess and the dates available for this cultural site are randomly distributed, ranging from 4500 to 1500 BP, i.e., a chronological period spanning from the Neolithic to the Iron Age.

Surface and Underground Ultra Low-Level Liquid Scintillation Spectrometry

Cosmic background and its variation have been removed in the Gran Sasso National Laboratory (National Institute of Nuclear Physics) by its 1400-m rock overburden. Stable, high-performance liquid scintillation counting conditions are obtained when any remaining variable components of the environmental background, such as radon, are eliminated. The ultra low-level liquid scintillation spectrometer Quantulus™ has an anti-Compton guard detector (guard for short) that allows monitoring of gamma radiation in the background. The guard detector efficiency in radiocarbon background reduction is 8% in the Gran Sasso National Laboratory, while 80% is observed in surface laboratories. Thus, atmospheric pressure variations in surface laboratories cause variation in cosmic radiation flux. The Quantulus anti-Compton detector is highly efficient in detecting cosmic radiation, and the sample count rate remains stable in long-term counting. Also, correlation of sample backgrounds with environmental gamma radiation in various laboratories is examined.