Temporal trend studies on tetra- and pentabrominated diphenyl ethers and hexabromocyclododecane in guillemot egg from the Baltic Sea

Guillemot eggs from the Baltic Sea, sampled between 1969 and 2001, were analyzed for tetra- and pentabromodiphenyl ethers (2,2',4,4'-tetraBDE (BDE-47), 2,2',4,4',5-pentaBDE (BDE-99), and 2,2',4,4',6-pentaBDE (BDE-100)), and hexabromocyclododecane (HBCD). This temporal trend study indicates that the concentrations of the polybrominated diphenyl ether compounds increased from the 1970s to the 1980s, peaking around the mid- to the late-1980s. These peaks are then followed by a rapid decrease in concentrations during the rest of the study period, with the concentrations of the major BDE congener below 100 ng/g lipid weight at the end of the period. This corresponds to less than 10% of its peak values. The concentrations of HBCD show a different pattern over time. After a peak in the middle of the 1970s followed by a decrease, the concentrations increased during the latter part of the 1980s. During the recent 10-yr period no significant change has occurred, and the annual mean concentrations are more or less stable at a higher level as compared to the beginning of the study period.     

Modelling temperature-dependent heat production over decades in High Arctic coal waste rock piles

Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures as the release of AMD normally is limited by permafrost. Here we show that temperatures within a 20 year old heat-producing waste rock pile in Svalbard (78°N) can be modelled by the one-dimensional heat and water flow model (CoupModel) with a new temperature-dependent heat-production module that includes both biological and chemical oxidation processes and heat source depletion over time. Inputs to the model are meteorological measurements, physical properties of the waste rock material and measured subsurface heat-production rates. Measured mean annual subsurface temperatures within the waste rock pile are up to 10 °C higher than the mean annual air temperature of −5.8 °C. Subsurface temperatures are currently decreasing with 0.5 °C per year due to decreasing heat production, which can be modelled using an exponential decay function corresponding to a half-life period of pyrite oxidation of 7 years. Simulations further suggest that subsurface temperatures two years after construction of the pile may have been up to 34.0 °C higher than in 2009 and that the release of AMD may have been more than 20 times higher. Sensitivity simulations show that maximum temperatures in the pile would have been up to 30.5-32.5 °C lower and that the pile would have been frozen 12-27 years earlier if the pile had been initially saturated with water, constructed with a thickness half of the original or a combination of both. Simulation show that the pile thickness and waste rock pyrite content are important factors controlling the internal build up of heat leading to potential self-incineration. However, site specific measurements of temperature-dependent heat production as well as simulation results show that the heat produced from pyrite oxidation alone cannot cause such a temperature increase and that processes such as heat production from coal oxidation may be equally important.     

CD74 and CD44 Expression on CTCs in Cancer Patients with Brain Metastasis

Up to 40% of advance lung, melanoma and breast cancer patients suffer from brain metastases (BM) with increasing incidence. Here, we assessed whether circulating tumor cells (CTCs) in peripheral blood can serve as a disease surrogate, focusing on CD44 and CD74 expression as prognostic markers for BM. We show that a size-based microfluidic approach in combination with a semi-automated cell recognition system are well suited for CTC detection in BM patients and allow further characterization of tumor cells potentially derived from BM. CTCs were found in 50% (7/14) of breast cancer, 50% (9/18) of non-small cell lung cancer (NSCLC) and 36% (4/11) of melanoma patients. The next-generation sequencing (NGS) analysis of nine single CTCs from one breast cancer patient revealed three different CNV profile groups as well as a resistance causing ERS1 mutation. CD44 and CD74 were expressed on most CTCs and their expression was strongly correlated, whereas matched breast cancer BM tissues were much less frequently expressing CD44 and CD74 (negative in 46% and 54%, respectively). Thus, plasticity of CD44 and CD74 expression during trafficking of CTCs in the circulation might be the result of adaptation strategies.     

Anisotropic Curvature and Damage of Unbonded Post-tensioned Concrete Slabs During Fire Testing

Two furnace tests, using two different fire exposures, on unbonded post-tensioned concrete slabs (1700 × 1200 mm) are reported. Local curvature is measured along two lines approximately in the middle of the slabs both parallel (longitudinal) and orthogonal (transverse) to the prestressing direction. More pronounced curvature in the transverse direction is accompanied by the formation of cracks running predominantly in the longitudinal direction. While the transverse curvature relaxes back to the original state after the cooling phase the curvature in the longitudinal direction ultimately exhibits upward deflection due to the hogging moment caused by the prestress in the tendons acting on a cross section with temperature reduced mechanical properties at the fire exposed side. The effect on crack formation due to the prestressing can additionally be detected by ultrasonic pulse velocity measurements in the different directions through the depth of the slab, where a reduction of 5–25% is observed in the transverse direction compared to the longitudinal direction. The phenomenological mechanical behaviour of the slabs is captured in a finite element model which describes the evolution of stress in the prestressing tendons. This model additionally suggests that the curvature in the transverse direction is independent of the prestressing in the longitudinal direction.     

Self-diffusion of oil in lubricating greases by NMR

Self-diffusion of base oil in six model lubricating greases and in the base oils themselves was measured using pulsed-field gradient nucleic magnetic resonance (NMR) at 23, 40, 70, and 90°C. Three of the greases were based on naphthenic mineral oils, and three were based on synthetic polyalphaolefin oils. Soaps of 12-hydroxy stearic acid were used as thickener agents in all six greases. The purpose of the investigation using NMR was to see if structure varies with temperature, and if NMR is a viable method for structure determination. The ratio between the diffusion coefficient of the base oil in the grease and the neat base oil in itself was evaluated as a function of temperature. This ratio was taken as a direct indicator of the obstruction effect that the thickener has on the oil. The thickener showed a stronger obstruction effect on the base oil in the synthetic grease than in the mineral-based grease. This was related to the soap content, which, for these greases, is roughly twice as high in the synthetic greases as in the mineral ones. The obstruction effect was constant in the temperature range 40–90°C for mineral- as well as synthetic-based greases. NMR was judged to be a promising method for investigating how the gellant affects the diffusion coefficient of oil in a lubricating grease.     

Intramolecular H-transfer reactions during the Decomposition of Alkylhydroperoxides in hydrocarbons as the solvents

Eight defined primary and secondary alkylhydroperoxides were decomposed in n-alkanes as the solvent, mostly in the presence of manganese stearate. In all cases the corresponding alcohols and carbonyl compounds were formed as the main products with yields of 60–90%. Besides, difunctional products were formed by an intramolecular H-transfer in the alkoxy radicals corresponding to the starting hydroperoxides. Products possibly formed by an intramolecular H-transfer in the corresponding alkylperoxy radical could be found only in the case of 4-methyl-2-hydroperoxy pentane. The amount of products formed by intramolecular H-transfer depended on the nature of the C-H bond in δ-position to the original hydroperoxy group and lay between 4% (primary C-H in the case of 4-hydroperoxy heptane) and 13% (tertiary C-H in the case of 2-hydroperoxy-5-methyl hexane) with respect to the starting hydroperoxide. The amount of products formed by oxidative attack of the alkoxy and alkylperoxy radicals at the normal paraffins used as the solvents was unexpectedly low (always less than 10% with respect to the starting hydroperoxide). An increment system is proposed for the calculation of ¹³C-nmr shifts in alkyl hydroperoxides.