Measurements of Argon-39 from locations near historic underground nuclear explosions.

Measurement of radioactive gas seepage from an underground nuclear explosion is one of the primary methods to confirm whether an event was nuclear in nature. Radioactive noble gas indicators that are commonly targeted by such measurements (e.g. 133Xe, 37Ar) have half-lives of 35 days or less. Argon-39, an activation product similar to 37Ar, is produced by the interaction between neutrons and potassium in the surrounding geology and has a half-life of 269 years. Measurements taken at three sites near three historic underground nuclear test locations at the Nevada National Security Site have all shown highly elevated levels of 39Ar in soil gas decades after the test events. Elevated levels of 39Ar were also detected in atmospheric air collected near two of these sites, and outside the entrance of the one tunnel site. These measurements demonstrate that 39Ar has the potential to be a long-term signature of an underground nuclear event which can be reliably detected at the surface or in the shallow subsurface. This radionuclide detection of an underground nuclear event decades after the event takes place is in contrast to the commonly held assumption that detecting underground nuclear events via radionuclides at the surface needs to be done in a matter of months. Depending upon what further studies show about the robustness of this signature in a variety of geological settings, it may in fact be easy to detect underground nuclear events at the surface for a very long time post-detonation.

Migration of noble gas tracers at the site of an underground nuclear explosion at the Nevada National Security Site.

As part of an underground gas migration study, two radioactive noble gases (37Ar and 127Xe) and two stable tracer gases (SF6 and PFDMCH) were injected into a historic nuclear explosion test chimney and allowed to migrate naturally. The purpose of this experiment was to provide a bounding case (natural transport) for the flow of radioactive noble gases following an underground nuclear explosion. To accomplish this, soil gas samples were collected from a series of boreholes and a range of depths from the shallow subsurface (3 m) to deeper levels (~160 m) over a period of eleven months. These samples have provided insights into the development and evolution of the subsurface plume and constrained the relative migration rates of the radioactive and stable gas species in the case when the driving pressure from the cavity is low. Analysis of the samples concluded that the stable tracer SF6 was consistently enriched in the subsurface samples relative to the radiotracer 127Xe, but the ratios of SF6 and 37Ar remained similar throughout the samples.

Comparison of measured and simulated concentrations of 133Xe in the shallow subsurface.

Radioactive isotopes of the noble gases xenon and argon are considered primary indicators of an underground nuclear explosion. However, high atmospheric concentrations from other anthropogenic sources may lead to an elevation in the underground levels of these gases, particularly in times of increasing atmospheric pressure. In 2014, a week long sampling campaign near Canadian Nuclear Laboratories in the Ottawa River Valley resulted in first of their kind measurements of atmospheric 133Xe that had been pressed into the subsurface. In an effort to better understand this imprinting process, a second follow-up sampling campaign was conducted in the same location in 2016. The results of the second sampling campaign, where samples were collected at depths of 1 m and 2 m over a 14 day period and measured for their 133Xe concentration, are presented here. Gas transport and sample concentrations were predicted using the Subsurface Transport over Multiple Phases (STOMP) simulator. These results are examined and compared to the corresponding experimental results.

Xenon adsorption on geological media and implications for radionuclide signatures.

The detection of radioactive noble gases is a primary technology for verifying compliance with the pending Comprehensive Nuclear-Test-Ban Treaty. A fundamental challenge in applying this technology for detecting underground nuclear explosions is estimating the timing and magnitude of the radionuclide signatures. While the primary mechanism for transport is advective transport, either through barometric pumping or thermally driven advection, diffusive transport in the surrounding matrix also plays a secondary role. From the study of primordial noble gas signatures, it is known that xenon has a strong physical adsorption affinity in shale formations. Given the unselective nature of physical adsorption, isotherm measurements reported here show that non-trivial amounts of xenon adsorb on a variety of media, in addition to shale. A dual-porosity model is then discussed demonstrating that sorption amplifies the diffusive uptake of an adsorbing matrix from a fracture. This effect may reduce the radioxenon signature down to approximately one-tenth, similar to primordial xenon isotopic signatures.

Measurements of Argon-39 at the U20az underground nuclear explosion site.

Pacific Northwest National Laboratory reports on the detection of 39Ar at the location of an underground nuclear explosion on the Nevada Nuclear Security Site. The presence of 39Ar was not anticipated at the outset of the experimental campaign but results from this work demonstrated that it is present, along with 37Ar and 85Kr in the subsurface at the site of an underground nuclear explosion. Our analysis showed that by using state-of-the-art technology optimized for radioargon measurements, it was difficult to distinguish 39Ar from the fission product 85Kr. Proportional counters are currently used for high-sensitivity measurement of 37Ar and 39Ar. Physical and chemical separation processes are used to separate argon from air or soil gas, yielding pure argon with contaminant gases reduced to the parts-per-million level or below. However, even with purification at these levels, the beta decay signature of 85Kr can be mistaken for that of 39Ar, and the presence of either isotope increases the measurement background level for the measurement of 37Ar. Measured values for the 39Ar measured at the site ranged from 36,000 milli- Becquerel/standard-cubic-meter-of-air (mBq/SCM) for shallow bore holes to 997,000 mBq/SCM from the rubble chimney from the underground nuclear explosion.

The potential detection of low-level aerosol isotopes from new civilian nuclear processes.

As the world faces a challenging future in maintaining the commercial availability of radioactive isotopes for medical use, new methods of medical isotope production are being pursued. Many of these are small in size and could effectively operate continuously. With the potential for much shorter retention times, a new suite of isotopes may soon be found in the environment. The authors estimate that many more aerosols containing low-level isotopes of gas/volatile origin could be detectable at short range and times, and a few at longer ranges and times as compared to those released in more common nuclear reactor operations.

Signature-based radiation scanning using radiation interrogation to detect explosives.

Improvised explosive devices (IEDs) pose a serious threat to society. The signature-based radiation scanning technology has been developed to counter this threat. This technology can be automated, requires minimal operator involvement, and in principle can rapidly identify IEDs from standoff distances. Preliminary research using neutron interrogation indicates that explosive samples of about 7 kg or greater hidden in various targets can be detected from standoff distances of more than a meter, with high sensitivity and high specificity.

Induction of tolerance via the respiratory mucosa.

Immunological tolerance is defined as a state of specific non-responsiveness to a particular antigen induced by previous exposure to that same antigen. The mucosal surfaces comprise the upper and lower respiratory tracts, the gastrointestinal tract and the urogenitary tract, and are a major site of antigenic challenge. The immune system associated with the mucosa has the extraordinary potential to discriminate between antigens that are harmless (e.g. inhaled and dietary antigens) and those that are associated with pathogens. Normally soluble proteins delivered through the mucosal surfaces do not elicit a strong systemic immune response but instead induce a transient local immune response that is replaced by long-term peripheral unresponsiveness this is termed mucosal tolerance. The phenomenon of oral tolerance is well established and considerable attention has focussed on defining the underlying mechanisms. However, only comparatively recently was the induction of tolerance via the respiratory mucosa described, and it is this form of mucosal tolerance which forms the basis of this review.

CD40 expression in Hodgkin's disease.

CD40 is a transmembrane protein that belongs to a superfamily of proteins related to nerve growth factor receptor. CD40 is expressed on B cells and some B cell malignancies. It appears to be involved in B cell proliferation and the prevention of apoptosis in germinal center cells, which is accompanied by expression of bcl-2. Its expression is up-regulated by the EBV protein latent membrane protein-1 and cytokines interleukin-4 and interferon-gamma. The expression of CD40 in 37 cases of Hodgkin's disease and 23 cases of non-Hodgkin's lymphoma (11 T cell lymphomas and 12 B cell lymphomas) was examined by paraffin section immunohistochemistry using the BB-20 monoclonal antibody. In 26 of 37 cases of Hodgkin's disease the Reed-Sternberg cells showed strong membrane or cytoplasmic expression of CD40. Only 3 of 23 non-Hodgkin's lymphomas showed any expression of CD40 and then only weakly. There was no correlation between expression of bcl-2 or latent membrane protein-1 with CD40 expression. These results show that there is probable hyperexpression of CD40 in Hodgkin's disease and suggest that dysregulation of CD40 expression may play a role in the pathogenesis of Hodgkin's disease.

Effect of anesthetic agents on lavage fluid parameters used as indicators of pulmonary injury.

The effect of the anesthetic agent used in killing animals in an in vivo pulmonary toxicity screening test was examined in Fischer-344 rats and in Syrian hamsters. Using animals killed by cervical dislocation with no anesthesia as a baseline, two types of anesthetic agents (halothane, sodium pentobarbital) and carbon dioxide were tested. Carbon dioxide caused the greatest perturbance of baseline lavage fluid and tissue parameters normally used in the screening test. Halothane anesthesia caused the least perturbance in the screening test parameters and was selected as the anesthetic of choice for use in future pulmonary toxicity tests.

Effect of cis- and trans-dichlorodiammineplatinum(II) on human tumor cell proliferation in diffusion chambers in vivo.

The cis and trans isomers of dichlorodiammineplatinum(II) (DDP) were tested for their ability to inhibit human tumor cell proliferation in vivo. Cell-impermeable diffusion chambers containing KB target cells were surgically implanted in the peritoneal cavities of Fischer rats, which were, 1 day later, given i.p. injections of cis-DDP (0.25 to 8.0 mg/kg), trans-DDP (8.0 mg/kg), or 0.9% NaCl solution. Radiolabeled cis- and trans-[195mPt]DDPs were used to monitor the diffusion of DDP within the chamber fluid and the binding or uptake of DDP by the target cells. Cell counts following injection showed that cis-DDP induced a progressive, dose-dependent loss in cell number so that, by the second day, the chambers of animals receiving cis-DDP (8 mg/kg) contained less than 10% of the cell number found in the control or trans-DDP-treated chambers. Despite the relative lack of biological activity of the transisomer, between 2- and 3-fold greater levels of 195mPt activity were detected in the fluid and target cells in chambers of animals receiving trans-[195mPt[DDP compared to cis-[195mPt]-DDP injected animals. Scanning electron micrographs of target cells from cis-DDP treated rats showed certain morphological features (cell surface blebs and the appearance of giant cells) that were not found in control target cell populations. The diffusion chamber system was shown to be a reproducible, sensitive assay system which differentiated between cis-DDP, a potent antitumor drug, and trans-DDP, a biologically ineffective isomer. In addition, it was possible using 195mPt-labeled DDP in this assay system to quantitate the relative concentrations of the two isomers both surrounding and within the target cells.

Effects of diphenylhydantoin on mental abilities in the elderly.

An assessment was made of the effects of diphenylhydantoin (DPH) on the mental functions of clinically normal elderly persons. Their basic intelligence levels ranged between normal and bright-normal and they represented middle and lower-upper socio-economic group. The 10 subjects, 4 male and 6 female volunteers (average age, 69.3 years), were given pretrial intelligence tests, repeated twice during a double-blind, cross-over study of drug and placebo effects. Each cross-over period lasted three weeks. The dosage of DPH (Dilantin) was 100 mg twice daily, and placebo capsuales of identical appearance were given on the same schedule. The Wechsler Intelligence Scale series in three alternate forms was used to measure specific mental functions. The weighted scores of the altervate forms were directly compared to measure the difference between drug and placebo conditions. Significant increases in favor of DPH were observed in the Information, Comprehension, and Digit Symbol subtests, and in the Verbal Scale and Full Scale Intelligence Quotients. The first two measures indicated significant improvement in long-term memory and social comprehension. The third reflected an increase in the ability to learn new material and increased speed in visual-motor coordination. The fourth and fifth showed the effectiveness of DPH in improving general mental functioning. Apparently the underlying factor synthesizing these general DPH-associated improvements is mental concentration.