Distribution and uptake of 137Cs in relation to alkali metals in a perhumid montane forest ecosystem.

We determined the content of radiocesium ((137)Cs) and alkali metals in soils, plants (2 ferns, a shrub and moss) and rainwater collected in an undisturbed forest ecosystem. The (137)Cs activity and the isotopic ratio of (137)Cs/Cs in the samples were used to interpret the distribution and uptake of (137)Cs and the alkali metals in plants. As a whole, the (137)Cs in plants was assimilated together with K but was not dependent on Cs. Different adaptations of fern species collected in ecological niches cause them to have different (137)Cs/Cs ratios. Diplopterygium glaucum is distributed at the edges of the forest; it usually has shallow organic layers, and the root takes up more stable Cs from mineral layers, leading to lower (137)Cs/Cs ratios than that in the understory Plagiogyria formosana and Rhododendron formosanum species. The steady supply of stable Cs through the uptake by D. glaucum from deep soils may gradually dilute the (137)Cs concentration and thus explain the lower (137)Cs/Cs ratio in the fern samples. The (137)Cs is predicted to be proportional to the Cs content across plant species in the biological cycle once isotopic equilibrium is attained.

A potential dating technique using 228Th/228Ra ratio for tracing the chronosequence of elemental concentrations in plants.

We propose a radiometric method based on measurement of the radioactivity of the naturally occurring radionuclides (228)Ra and 228)Th and the derived (228)Th/(228)Ra ratios in plant samples to estimate plant age and the corresponding nutritional conditions in a field-growing fern, Dicranopteris linearis. Plant age (tissue age) was associated with the (228)Th/(228)Ra ratio in fronds, which implies the accumulation time of immobile elements in the plant tissue or the life span of the fronds. Results indicated that the accumulation of alkaline earth elements in D. linearis is relatively constant with increased age, while the K concentration is reversed with age because of translocation among plant tissues. Estimation of dating uncertainty based on measurement conditions revealed that the radiometric technique can be applied to trace chronosequential changes of elemental concentrations and environmental pollutants in plants with ages of less than 10-15 years.

Development of separation techniques for analysis of Nb-94 in radwaste samples.

A chemical separation technique for removing interfering gamma-ray radionuclides by combined precipitation of Nb pentoxide and anion exchange was proposed, thereby allowing detection of trace 94Nb in low-level radwastes. The detection limit for 94Nb was improved by a factor of 10-103, and the scaling factor (94Nb/60Co) of the radwastes was estimated to be less than 10-5. This technique can be used for low-level radwaste classification and power reactor decommissioning.

Comparison of the single dose pharmacokinetics, pharmacodynamics, and safety of two novel oral formulations of dimethandrolone undecanoate (DMAU): a potential oral, male contraceptive.

Dimethandrolone (DMA, 7α,11ß-dimethyl-19-nortestosterone) has both androgenic and progestational activities, ideal properties for a male hormonal contraceptive. In vivo, dimethandrolone undecanoate (DMAU) is hydrolyzed to DMA. We showed previously that single oral doses of DMAU powder in capsule taken with food are well tolerated and effective at suppressing both LH and testosterone (T), but absorption was low. We compared the pharmacokinetics and pharmacodynamics of two new formulations of DMAU, in castor oil and in self-emulsifying drug delivery systems (SEDDS), with the previously tested powder formulation. DMAU was dosed orally in healthy adult male volunteers at two academic medical centers. For each formulation tested in this double-blind, placebo-controlled study, 10 men received single, escalating, oral doses of DMAU (100, 200, and 400 mg) and two subjects received placebo. All doses were evaluated for both fasting and with a high fat meal. All three formulations were well tolerated without clinically significant changes in vital signs, blood counts, or serum chemistries. For all formulations, DMA and DMAU showed higher maximum (p < 0.007) and average concentrations (p < 0.002) at the 400 mg dose, compared with the 200 mg dose. The powder formulation resulted in a lower conversion of DMAU to DMA (p = 0.027) compared with both castor oil and SEDDS formulations. DMAU in SEDDS given fasting resulted in higher serum DMA and DMAU concentrations compared to the other two formulations. Serum LH and sex hormone concentrations were suppressed by all formulations of 200 and 400 mg DMAU when administered with food, but only the SEDDS formulation was effectively suppressed serum T when given fasting. We conclude that while all three formulations of oral DMAU are effective and well tolerated when administered with food, DMAU in oil and SEDDS increased conversion to DMA, and SEDDS may have some effectiveness when given fasting. These properties might be advantageous for the application of DMAU as a male contraceptive.

Measurement of 224Ra uptake in a fern actively accumulating radium.

A method is proposed for determining the level of 224Ra in plant samples by measuring its descendant nuclide 212Pb at 239 keV by gamma-ray spectrometry. Variations of 224Ra and 212Pb over time during sample preparation and counting were delineated prior to gamma-ray measurement. The 224Ra concentrations in plant samples were measured by their direct uptake from soil, which could be determined and distinguished from that resulting from decay of 228Th inside the plants. We propose that a field-growing Dicranopteris linearis, which actively accumulates radium, can be used as an indicator of the nutritional transportation and metabolic rate of radium and other alkaline earth elements. We investigated the influence of rainfall on 224Ra concentrations in fronds of D. linearis and the corresponding uptake rates. 224Ra could serve as a natural tracer of growth in plants over a several days. Its presence and content in plants implies a temporal mineral metabolic rate, which can provide useful information for plant physiological and environmental investigations.

Patient perceptions concerning clinical trials in oncology patients.

BACKGROUND: Clinical trials are critical to scientifically evaluate promising new therapies in oncology, but patient accrual to these studies is persistently low. Patient preference plays an important role in enrollment in these trials. We performed this survey to evaluate the perceptions of newly diagnosed oncology patients about clinical trials and the reasons why they wish to or not to participate in these trials. METHODS: Patients were given a ten question survey reflective of their attitudes regarding clinical trials as a treatment option at their initial visit. The self-directed questionnaire was scored on an ordinate scale from strongly agree [1] to strongly disagree [5]. RESULTS: Ninety three patients were surveyed in the cancer specific multispecialty clinics in an academic center. Our patients expected their providers to discuss all information relating to clinical trials and eligibility at the first visit (65.4% agree and 15.4% neutral, p < 0.0001). Patients felt their privacy and safety would be safeguarded in the University sponsored trials (56.8% agree, and 25.7% neutral, p < 0.0001). Over 80% patients showed their unwillingness to participate in randomized clinical trials (disagree 61%, neutral 19.5%, p < 0.001). Patients also showed less likelihood to participate in clinical trials as a first treatment option (48.7% disagree and 28.9% neutral, p0.0161), but were willing to consider participating in a clinical trial if the conventional treatment failed. Industry sponsored trials, phase 1 trials, investigator initiated trials with the involved tests and time commitment and altruistic reasons did not significantly deviate from the mean preference analyzed using Fisher's exact test analysis. CONCLUSIONS: Patients consider the option of clinical trials as important in their treatment, and expect to be informed by their oncologist about such trials. Newly diagnosed cancer patients perceive randomization and first line trials negatively. Since randomization data provides new standards of care and hope for improved treatment, patients and their families must be educated of their importance.

Determination of trace Al in silicon carbide by epithermal neutron activation.

An approach based on utilization of epithermal neutron activation analysis (ENAA) is proposed for determination of trace Al in silicon carbide (SiC) materials. The feasibility and restrictions of the ENAA were evaluated in terms of the associated uncertainties that resulted from counting and from propagation in calculations. Experimental measurements were carried out under the specified irradiation and measurement conditions, where the results of a set of SiC standards for accuracy testing were compared with the calculated uncertainties. It is shown that the epithermal neutron activation is a simple and reliable method practically useful for analysis of SiC containing Al in concentrations (f(Al)) higher than 10(-3) weight fraction by the use of a typical nuclear reactor; the associated uncertainties can be suppressed to less than 12%. The influences of neutron quality or the cadmium ratio in 27Al(n,gamma)28Al reaction on the applicable concentrations of Al in SiC are also predicted and discussed.

129I concentrations of mammalian thyroids in Taiwan.

The 129I and 129I/127I ratios in mammalian thyroids were determined by neutron activation analysis to estimate the 129I concentrations in the biosphere due to fallout accumulation during the past decades in this island. The average 129I/127I ratio in thyroids of grazing animals, bovine and ovine, is about 1 x 10(-9), three times higher than that of hogs. The 129I/127I ratio in twin water collected during the same period was found to be as high as 1.7 x 10(-8) and it is supposed to be the predominant source of 129I in the biosphere. The 129I concentrations in these mammalian thyroids are similar to those of non-direct contamination areas of the world, where the terrestrial 129I contents are influenced by the global fallout.

Measurement of high dose rates by photon activation of indium foils.

Photon activation of indium foils is proposed as a dosimetry technique for high dose rate measurements in a 60Co irradiation facility. The irradiated indium nuclei may be raised to its metastable isomers of 113mIn and 115mIn. The isomer 115mIn, with appreciable induced radioactivity, was selected for dose-rate measurements. Based on the photon flux distribution and the derived dose rates, which were simulated by the MCNP code, the dependence of dose rate measurement sensitivity of indium foils with respect to photon energy at various irradiation distances is described. For practical uses, the radioactivity of 115mIn was linearly related to the dose rate response at the specified irradiation positions. By comparing with a calibrated dosimetry system, the measurement deviation of the indium dosimeter, over dose rates ranging from 10 to 10(4) Gy/h, was evaluated and exhibited an uncertainty of +/- 7%. Other related characteristics including measurement sensitivity and range, linearity with respect to the variation of dose rate, and limitations of the indium dosimeter were evaluated to justify it as an alternative for monitoring dose rate in an irradiation field.

Dose estimation for repeated phosphorus-32 ingestion in human subjects.

Dose estimation was conducted for internal phosphorus-32 exposure in one young male subject from repeated oral mis-ingestion for > 1 year. Since disclosure for previous continuous contamination, a series of urine samples were collected from this individual weekly for a period of >2 months. P-32 radioactivity in urine samples were measured by the acid precipitation method. Estimation for retrospective total effective dose equivalent received by this subject was conducted for cumulative internal dose estimation. A minimum of 9.4 mSv was estimated for an assumed single ingestion. As this was a rare case in radiation protection and internal radiation dosimetry, its implications were of considerable significance.

Monitoring of (7)Be in surface air of varying PM(10) concentrations.

In this study, beryllium-7 ((7)Be) concentrations of surface air were monitored throughout a span of 23 years (1992-2012) in the Taiwanese cities Yilan, Taipei, Taichung, and Kaohsiung. During this period, particulate matter (PM) concentrations, in terms of PM10, were collected monthly from the nearest air-quality pollutant monitoring stations and compared against (7)Be concentrations. Seasonal monsoons influenced (7)Be concentrations in all cities, resulting in high winter and low summer concentrations. In addition, the meteorological conditions caused seasonal PM10 variations, yielding distinct patterns among the cities. There was no correlation between (7)Be and PM10 in the case cities. The average annual (7)Be concentrations varied little among the cities, ranging from 2.9 to 3.5 mBq/m(3), while the PM10 concentrations varied significantly from 38 µg/m(3) in Yilan to 92 µg/m(3) in Kaohsiung depending on the degree of air pollution and meteorological conditions. The correlation between the (7)Be concentration and gross-beta activities (Aß) in air implied that the (7)Be was mainly attached to crustal PM and its concentration varied little among the cities, regardless of the increase in anthropogenic PM in air-polluted areas.

Variation of atmospheric Be-7 in relation to PM concentrations.

In the present study, the influences of particulate matter (PM) and seasonal monsoons on (7)Be concentrations in surface air (CBe) are elucidated. The (7)Be and the corresponding PM concentrations in the air were monitored simultaneously throughout a 14-year period (1998-2011) in Hsinchu, Taiwan. During the autumn and winter seasons (Oct.-Feb.), both the PM and the (7)Be concentrations increased as a result of the northeasterly monsoon. In contrast, the lowest PM and (7)Be concentrations were observed in July and August. This timing is due to the occurrence of southwest monsoons, which carry air masses with low PM concentrations and are associated with depleted (7)Be from low latitudes. The activity concentration of (7)Be in the PM (APM) was used to explain the seasonal variations of (7)Be with respect to the PM concentrations. In contrast, APM is not sensitive enough to vary with the seasons. The air masses transported by the monsoons are believed to be partially mixed with the PM locally produced in Taiwan, which explains their seasonal variations. The (7)Be concentrations in surface air can be experimentally predicted from the PM concentrations based on CBe (mBq/m(3))=0.0767 PM (µg/m(3)) across seasons. The annual averages of the PM and (7)Be concentrations are 48.1 µg/m(3) and 3.7 mBq/m(3), respectively. The estimated CBe was either slightly overestimated or underestimated, depending on the season. The highest deviations occurred in July and August, when CBe was underestimated by 33%.

Deposition of beryllium-7 in Hsinchu, Taiwan.

In the present study, factors that influence the distribution and variation of (7)Be in Hsinchu, Taiwan were elucidated. The (7)Be activity including the deposition flux and air concentration was continuously monitored and recorded throughout a 15-year period (1996-2010). To explain the observed variability in the (7)Be activity over time, air concentration and deposition flux of (7)Be were correlated to rainfall and solar activity. The monthly average deposition flux and air concentration of (7)Be were inversely related to solar activity with the 11-year cycle and were not strongly correlated to rainfall. The highest seasonal deposition flux of (7)Be occurred in March, which is commonly referred to as the spring maximum, due to air-mass mixing processes in the troposphere. The air concentration of (7)Be was seasonally variable and was significantly affected by monsoons. The lowest deposition flux and air concentration of (7)Be were observed in July and August due to the occurrence of southwest monsoons from low latitudes, which carry air masses with low concentrations of (7)Be. The deposition flux was enhanced by precipitation, which increased the deposition velocity, transferring more (7)Be from the troposphere to the ground. The fraction of dry to total deposition varied seasonally and was equal to 9.86%, on average.

Determination of Au and Pt in titanate nanotube catalysts by photon activation analysis.

This study demonstrated the determination of Au and Pt concentrations in titanate nanotube-supported (abbreviated as TNT-supported) metal catalysts by photon activation and their catalytic activity with respect to metal concentration. An 18MV medical accelerator was used as photon source to activate the metals and generate radionuclides for gamma-ray spectroscopic analysis. Two TNT-supported metal catalysts, namely Au/NaTNT and Pt/MTNT (M=Na(+) and Cs(+)), were prepared and the Au and Pt concentrations and the respective loading efficiencies were determined. The detection sensitivities with respect to the photon activated radionuclides were estimated to select the most sensitive gamma rays for the determination of Au and Pt concentrations. The loading efficiency for Au/NaTNT decreased with increasing Au concentration prepared, while it was almost 100% for Pt loading in Pt/MTNT of various prepared Pt concentrations. The Au/NaTNT containing 2.53 wt% of Au effectively oxidized CO at a much lower reaction temperature than the lower concentration ones. For cinnamaldehyde hydrogenation reaction, the catalytic activity of Pt/TNT with different Pt loadings followed the order of 2.9>2.3>0.9>0.5 wt%. This photon activation technique, with minus interfering radionuclides in the gamma-ray spectra and induced radioactivities in the samples, is perfectly suited to the determination of metal concentrations in TNT-supported catalysts, that might contain considerable amounts of alkali metal ions.

Accumulation of radium in relation to some chemical analogues in Dicranopteris linearis.

This study elucidates the uptake and accumulation of radium in the field-growing fern Dicranopteris linearis by relating the radium concentration to some potential chemical analogues, including alkaline earth metals, rare earth elements, and some important heavy metals. Time-dependent accumulation of radium and these chemical analogues for D. linearis were described by the (228)Th/(228)Ra activity ratio, an index for inferring plant age. The correlation between radium and these elements was assessed by statistical analysis and used as a reference to elucidate the uptake and accumulation of radium in relation to the chemical analogues. Analytical and statistical results showed that the concentrations of alkaline earth metals (except for Mg) rare earth elements and some heavy metals in D. linearis increased linearly with plant age. These elements, exhibiting a similar accumulation pattern to radium and significant correlation coefficients with radium, were considered as the chemical analogues to radium. Additionally, the plant/soil concentration ratios (CRs) for radium and most of these analogues in D. linearis exceeded 1, consistent with the definition of hyper-accumulator plants.

Relationship between radioactivity of radium and concentrations of barium and lead in hokutolite.

Hokutolite consists of barite (BaSO(4)) and anglesite (PbSO(4)), and contains significant amounts of radium isotopes as a radioactive mineral. Photon activation and gamma-ray spectrometry were employed to determine Ba, Pb and (226)Ra contents in hokutolite samples and to investigate the correlation between (226)Ra activity and both Ba and Pb content. (226)Ra activity in 30 hokutolite samples were estimated in the range of 40-65Bq/g and was positively related to Ba content (r=0.859, p<0.001), but independent of Pb content (r=-0.236, p=0.217). Experimental results implied that (226)Ra preferably precipitated with Ba over Pb. The (226)Ra activity in hokutolite from the Peitou Hot Spring was experimentally estimated based on the Ba/Pb ratio and expressed as (226)Ra (Bq/g)=14.67 (Ba/Pb)(molar)+14.13.

Using medical accelerators and photon activation to determine Sr/Ca concentration ratios in teeth.

This paper describes a photon activation method, studied by using two medical accelerators (energies: 15 and 18 MeV) as photon sources, for determining Sr and Ca levels and Sr/Ca ratios in tooth samples. The radionuclides formed by various photonuclear reactions were measured and identified using a gamma-spectrometry with HPGe detection system. The yields of the corresponding photonuclear reactions and the detection sensitivities for the alkaline earth metals (e.g., Ca, Sr) were surveyed and estimated in relation to the radiation dose. The minimum detectable amount of Sr was estimated to be less than 1 microg g(-1), allowing the Sr/Ca ratios in teeth to be determined conveniently. The Sr/Ca ratios in deciduous and permanent tooth samples obtained from local dental clinics were 0.390 and 0.565 mg g(-1), respectively. This photon activation method of determining Sr/Ca ratio in bones and teeth using medical accelerators for cancer treatment is thought to be useful also in biological and archaeological studies.

Radionuclide monitoring in environmental water body using an in situ gamma probe.

An HPGe gamma probe designed to monitor radioactive nuclides in environmental water in situ is described. The probe is equipped with a 15% HPGe detector and an associated spectrum analyzer. Laboratory tests were performed to evaluate its operating depth, detecting sensitivity, detecting volume and the detection limits of radionuclides. A field operation was conducted to measure in situ radionuclide concentrations in a nuclear reactor pool, and the feasibility as well as the disadvantages of this rapid survey are discussed.