Thermal expansion of troilite and pyrrhotite determined by in situ cooling (873 to 373 K) neutron powder diffraction measurements

The thermal expansion coefficients for natural troilite, FeS, Ni-rich pyrrhotite, Fe0.84Ni0.11S, and Ni-poor pyrrhotite, Fe0.87Ni0.02S, were measured during cooling by in situ neutron powder diffraction over the temperature range 873–373 K. Between 873 and 573 K, the mean thermal expansion coefficients for the three compositions are 7.4(3) × 10-5 {FeS}, 8.0(4) × 10-5 {Fe0.84Ni0.11S} and 8.5(4) × 10-5 K–1 {Fe0.87Ni0.02S}. Below 573 down to 373 K, the first two increase considerably to 14.1(7) × 10-5 {FeS} and 9.3(5) × 10-5 {Fe0.84Ni0.11S} while the latter sample shows no significant variation, 8.4(5) × 10-5 K-1. Below 573 K, the thermal expansion is highly anisotropic, with Deltaa/100 K-1 ranging from 0.89(9)% {FeS} to 0.48(12)% {Fe0.87Ni0.02S} while Deltac/100 K-1 ranges from -0.39(11)% {FeS} to -0.13(2)% {Fe0.87Ni0.02S}. Upon cooling through 573 K, troilite and pyrrhotite undergo a transition where the FeS6 octahedra distort and in the case of pyrrhotite, cation-vacancy clustering occurs. The thermal expansion coefficients are bigger for low cation-vacancy concentrations and decrease as the pyrrhotites become less stoichiometric. This indicates that the thermal expansion in these minerals is damped by vacancy ordering or clustering. The thermal expansion coefficients for troilite and pyrrhotite are amongst the largest reported for sulphide minerals and their role in the formation of ore textures is discussed briefly

Individual Radiation Exposure Dose Due to Support Activities at Safe Shelters in Fukushima Prefecture

Immediately after the accidents in the nuclear power stations in Fukushima on March 11, the Japanese Government ordered the evacuation of the residents within a 20-km radius from the station on March 12, and asked various institutions to monitor the contamination levels of the residents. Hirosaki University, which is located 355 km north of Fukushima City, decided to send support staff to Fukushima. This report summarizes the results of the exposure of 13 individual teams from March 15 to June 20. The support teams surveyed more than 5,000 people during this period. Almost all subjects had external contamination levels of less than 13 kcpm on Geiger-Müller (GM) survey meter, which is categorized as “no contamination level.” The 1st team showed the highest external exposure dose, but the 4th team onward showed no significant change. Subsequently, the internal radiation exposure was measured using a whole body counter that indicated undetectable levels in all staff members. Although the measured external radiation exposure dose cannot have serious biological effects on the health of an individual, a follow-up study of the residents in Fukushima and other regions where the radioactive material has spread will be required for a long time

International standardisation work on the measurement of radon in air and water

Radon is considered to be the main source of human exposure to natural radiation. As stated by the World Health Organization, the exposure due to the inhalation of indoor radon is much greater than the one via the ingestion of water as radon degasses from water during handling. In response to these concerns about the universal presence of radon, environmental assessment studies are regularly commissioned to assess the radon exposure of public and workers. The credibility of such studies relies on the quality and reliability of radon analysis as well as on the sample representativeness of the radiological situation. The standard-setting approach, based on consensus, seemed to lend itself to a settlement of technical aspects of potential comparison. At present, two Working Groups of the International Standardization Organization are focussing on drafting standards on radon and its decay products measurement in air and water. These standards, which aim for a set of rigorous metrology practices, will be useful for persons in charge of the initial characterisation of a site with respect to natural radioactivity as well as to those performing the routine surveillance of specific site

Design, Analysis, and Fabrication of a Snake-Inspired Robot with a Rectilinear Gait

Snake-inspired robots display promise in areas such as search, rescue and reconnaissance due to their ability to locomote through tight spaces. However, several specific issues regarding the design and analysis must be addressed in order to better design them. This thesis develops kinematic and dynamic models for a class of snake-inspired gait known as a rectilinear gait, where mechanism topology changes over the course of the gait. A model using an Eulerian framework and Coulomb friction yields torque expressions for the joints of the robot. B-spline curves are then used to generate a parametric optimization formulation for joint trajectory generation. Exact gradient computation of the torque functions is presented. A parametric model is used to describe the performance effects of changing system parameters such as mass, length, and motor speed. Finally, a snake-inspired robot is designed and fabricated in order to demonstrate both the vertical rectilinear gait and a modular, molded design aimed at reducing the cost of fabrication

Environmental radiation at Izu-Oshima after the Fukushima Daiichi nuclear power plant accident

Environmental radiation at Izu-Oshima Island was observed six months after the accident at the Fukushima Daiichi Nuclear Power Plant (F1-NPP). A car-borne survey of the dose rate in air was conducted over the entire island and the results were compared with measurements performed in 2005 (i.e., before the accident). The activity concentrations of cesium-134 and cesium-137 were also measured using a germanium detector. The dose rate in air was found to be 2.9 ± 1.2 times higher than that in 2005 and cesium-134 was detected on Izu-Oshima Island. These results are attributed to the accident at the F1-NPP

Residential Radon and Brain Tumour Incidence in a Danish Cohort

BACKGROUND: Increased brain tumour incidence over recent decades may reflect improved diagnostic methods and clinical practice, but remain unexplained. Although estimated doses are low a relationship between radon and brain tumours may exist. OBJECTIVE: To investigate the long-term effect of exposure to residential radon on the risk of primary brain tumour in a prospective Danish cohort. METHODS: During 1993-1997 we recruited 57,053 persons. We followed each cohort member for cancer occurrence from enrolment until 31 December 2009, identifying 121 primary brain tumour cases. We traced residential addresses from 1 January 1971 until 31 December 2009 and calculated radon concentrations at each address using information from central databases regarding geology and house construction. Cox proportional hazards models were used to estimate incidence rate-ratios (IRR) and 95% confidence intervals (CI) for the risk of primary brain tumours associated with residential radon exposure with adjustment for age, sex, occupation, fruit and vegetable consumption and traffic-related air pollution. Effect modification by air pollution was assessed. RESULTS: Median estimated radon was 40.5 Bq/m(3). The adjusted IRR for primary brain tumour associated with each 100 Bq/m(3) increment in average residential radon levels was 1.96 (95% CI: 1.07; 3.58) and this was exposure-dependently higher over the four radon exposure quartiles. This association was not modified by air pollution. CONCLUSIONS: We found significant associations and exposure-response patterns between long-term residential radon exposure radon in a general population and risk of primary brain tumours, adding new knowledge to this field. This finding could be chance and needs to be challenged in future studies

BRAFV600E mutation is highly prevalent in thyroid carcinomas in the young population in Fukushima: a different oncogenic profile from Chernobyl

After the accident at the Fukushima Daiichi Nuclear Power Plant, the thyroid ultrasound screening program for children aged 0-18 at the time of the accident was started from October 2011. The prevalence of thyroid carcinomas in that population has appeared to be very high (84 cases per 296,253). To clarify the pathogenesis, we investigated the presence of driver mutations in these tumours. 61 classic papillary thyroid carcinomas (PTCs), two follicular variant PTCs, four cribriform-morular variant PTCs and one poorly-differentiated thyroid carcinoma were analysed. We detected BRAF V600E in 43 cases (63.2%), RET/PTC1 in six (8.8%), RET/PTC3 in one (1.5%) and ETV6/NTRK3 in four (5.9%). Among classic and follicular variant PTCs, BRAF V600E was significantly associated with the smaller size. The genetic pattern was completely different from post-Chernobyl PTCs, suggesting non-radiogenic etiology of these cancers. This is the first study demonstrating the oncogene profile in the thyroid cancers discovered by large mass screening, which probably reflects genetic status of all sporadic and latent tumours in the young Japanese population. It is assumed that BRAF V600E may not confer growth advantage on paediatric PTCs, and many of these cases grow slowly, suggesting that additional factors may be important for tumour progression in paediatric PTCs

L-2-hydroxyglutarate production arises from non-canonical enzyme function at acidic pH

The metabolite 2-hydroxyglutarate (2HG) can be produced as either a D(R)- or L(S)- enantiomer, each of which inhibits alpha-ketoglutarate (αKG)-dependent enzymes involved in diverse biologic processes. Oncogenic mutations in isocitrate dehydrogenase produce D-2HG, which causes a pathologic blockade in cell differentiation. On the other hand, oxygen limitation leads to accumulation of L-2HG, which can facilitate physiologic adaptation to hypoxic stress in both normal and malignant cells. Here we demonstrate that purified lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) catalyze stereospecific production of L-2HG via ‘promiscuous’ reduction of the alternative substrate αKG. Acidic pH enhances production of L-2HG by promoting a protonated form of αKG that binds to a key residue in the substrate-binding pocket of LDHA. Acid-enhanced production of L-2HG leads to stabilization of hypoxia-inducible factor 1 alpha (HIF-1α) in normoxia. These findings offer insights into mechanisms whereby microenvironmental factors influence production of metabolites that alter cell fate and function