Joint Assessment of ETRR-2 Research Reactor Operations Program, Capabilities, and Facilities

A joint assessment meeting was conducted at the Egyptian Atomic Energy Agency (EAEA) followed by a tour of Egyptian Second Research Reactor (ETRR-2) on March 22 and 23, 2006. The purpose of the visit was to evaluate the capabilities of the new research reactor and its operations under Action Sheet 4 between the U.S. DOE and the EAEA, ''Research Reactor Operation'', and Action Sheet 6, ''Technical assistance in The Production of Radioisotopes''. Preliminary Recommendations of the joint assessment are as follows: (1) ETRR-2 utilization should be increased by encouraging frequent and sustained operations. This can be accomplished in part by (a) Improving the supply-chain management for fresh reactor fuel and alleviating the perception that the existing fuel inventory should be conserved due to unreliable fuel supply; and (b) Promulgating a policy for sample irradiation priority that encourages the use of the reactor and does not leave the decision of when to operate entirely at the discretion of reactor operations staff. (2) Each experimental facility in operation or built for a single purpose should be reevaluated to focus on those that most meet the goals of the EAEA strategic business plan. Temporary or long-term elimination of some experimental programs might be necessary to provide more focused utilization. There may be instances of emerging reactor applications for which no experimental facility is yet designed or envisioned. In some cases, an experimental facility may have a more beneficial use than the purpose for which it was originally designed. For example, (a) An effective Boron Neutron Capture Therapy (BNCT) program requires nearby high quality medical facilities. These facilities are not available and are unlikely to be constructed near the Inshas site. Further, the BNCT facility is not correctly designed for advanced research and therapy programs using epithermal neutrons. (b) The ETRR-2 is frequently operated to provide color-enhanced gemstones but is operated infrequently for radioisotope production. Because the two irradiation programs compete by utilizing the same core locations, the issues should be resolved at a high level. (c) Cobalt-60 production uses the most valuable irradiation location in the ETRR-2 (the high neutron density flux-trap), but there seems to be no potential customer for the Co-60. Further, the low number of hours the reactor is operated per week precludes ever producing a marketable specific activity of Co-60. Accordingly, Co-60 production should be reevaluated. (d) ETRR-2 staff would benefit from additional training to successfully design new experiment facilities and utilize existing facilities more effectively. This training can include IAEA Fellowships, as well as topical DOE Sister Laboratory visits to gain experience using equipment and research tools at other research reactor facilities

Glutamate cycling may drive organic anion transport on the basal membrane of human placental syncytiotrophoblast

The organic anion transporter OAT4 (SLC22A11) and organic anion transporting polypeptide OATP2B1 (SLCO2B1) are expressed in the basal membrane of the placental syncytiotrophoblast. These transporters mediate exchange whereby uptake of one organic anion is coupled to efflux of a counter-ion. In placenta, these exchangers mediate placental uptake of substrates for oestrogen synthesis as well as clearing waste products and xenobiotics from the fetal circulation. However, the identity of the counter-ion driving this transport in the placenta, and in other tissues, is unclear. While glutamate is not a known OAT4 or OATP2B1 substrate, we propose that its high intracellular concentration has the potential to drive accumulation of substrates from the fetal circulation. In the isolated perfused placenta, glutamate exchange was observed between the placenta and the fetal circulation. This exchange could not be explained by known glutamate exchangers. However, glutamate efflux was trans-stimulated by an OAT4 and OATP2B1 substrate (bromosulphothalein). Exchange of glutamate for bromosulphothalein was only observed when glutamate reuptake was inhibited (by addition of aspartate). To determine if OAT4 and/or OATP2B1 mediate glutamate exchange, uptake and efflux of glutamate were investigated in Xenopus laevis oocytes. Our data demonstrate that in Xenopus oocytes expressing either OAT4 or OATP2B1 efflux of intracellular [14C]glutamate could be stimulated by conditions including extracellular glutamate (OAT4), estrone-sulphate and bromosulphothalein (both OAT4 and OATP2B1) or pravastatin (OATP2B1). Cycling of glutamate across the placenta involving efflux via OAT4 and OATP2B1 and subsequent reuptake will drive placental uptake of organic anions from the fetal circulation.<br/

Experimental estimation of snare detectability for robust threat monitoring

Hunting with wire snares is rife within many tropical forest systems, and constitutes one of the severest threats to a wide range of vertebrate taxa. As for all threats, reliable monitoring of snaring levels is critical for assessing the relative effectiveness of management interventions. However, snares pose a particular challenge in terms of tracking spatial or temporal trends in their prevalence because they are extremely difficult to detect, and are typically spread across large, inaccessible areas. As with cryptic animal targets, any approach used to monitor snaring levels must address the issue of imperfect detection, but no standard method exists to do so. We carried out a field experiment in Keo Seima Wildlife Reserve in eastern Cambodia with the following objectives: (1) To estimate the detection probably of wire snares within a tropical forest context, and to investigate how detectability might be affected by habitat type, snare type, or observer. (2) To trial two sets of sampling protocols feasible to implement in a range of challenging field conditions. (3) To conduct a preliminary assessment of two potential analytical approaches to dealing with the resulting snare encounter data. We found that although different observers had no discernible effect on detection probability, detectability did vary between habitat type and snare type. We contend that simple repeated counts carried out at multiple sites and analyzed using binomial mixture models could represent a practical yet robust solution to the problem of monitoring snaring levels both inside and outside of protected areas. This experiment represents an important first step in developing improved methods of threat monitoring, and such methods are greatly needed in southeast Asia, as well as in as many other regions

Measurement of electron attachment in oxygen-methane and oxygen-carbon dioxide mixtures

The formation of heavy negative ions by the attachment of low-energy electrons to oxygen molecules was studied for small amounts of oxygen mixed with methane or carbon dioxide. The rate of attachment in both cases was found to depend on the electron energy, the pressure of the oxygen and the non-attaching gas, and on the kind of non-attaching gas. In general, the attachment increases as electron enprgy decreases or as either oxygen or total pressure increases. The value of the attachment coefficient in oxygencarbon dioxide mixtures is about 100 times its value in oxygen-methane mixtures. This large difference is probably due in part to differences in electron energy and partly to differences in the stabilizing qualities of the two molecules. Dissociative attachment, which should be pressure independent, does not occur at the low energies that were used in this work. Both methane and carbon dioxide are to differences in the stabilizing qualities of the two molecules. Dissociative attachment, which should be pressure independent, does not occur at the low energies that were used in this work. Both methane and carbon dioxide are sometimes used as filling gases for Geiger and proportional counters. The high sensitivity of carbon dioxide to oxygen contamination indicates that very pure gas should be used if the best operation is to be obtained. The low sensitivity of methane recommends it for counters where careful purification of the gas is difficult and particularly for flow counters where the possibility of contamination by atmospheric oxygen exists. (auth