A review of iron carbonate (FeCO₃) formation in the oil and gas industry

This paper reviews the information in the literature relating to FeCO₃ formation in the context of oil and gas production. Numerous factors which influence the kinetics, physical properties and protective nature of FeCO₃ are considered in addition to a review of semi-empirical models developed to predict precipitation/corrosion layer accumulation rate. The limitations of current models are discussed and the challenges of conducting deposition studies onto steel surfaces in a controlled environment using laboratory based techniques are also reviewed. Finally, more recently employed experimental techniques are considered in their potential to provide a further understanding of FeCO₃ and mixed carbonate kinetics

Blood circulating miR-28-5p and let-7d-5p associate with premature ageing in Down syndrome

Persons with Down syndrome (DS) undergo a premature ageing with early onset of age-related diseases. The main endpoint of this study was the identification of blood circulating microRNAs (c-miRs) signatures characterizing DS ageing process. A discovery phase based on array was performed in plasma samples obtained from 3 young (31 ± 2 years-old) and 3 elderly DS persons (66 ± 2 years-old). Then, a validation phase was carried out for relevant miRs by RT-qPCR in an enlarged cohort of 43 DS individuals (from 19 up to 68 years-old). A group of 30 non-trisomic subjects, as representative of physiological ageing, was compared. In particular miR-628-5p, miR-152-3p, miR-28-5p, and let-7d-5p showed a lower level in younger DS persons (age ≤ 50 years) respect to the age-matched controls. Among those, miR-28-5p and let-7d-5p were found significantly decreased in physiological ageing ( oldest group ), thus they emerged as possible biomarkers of premature ageing in DS. Moreover, measuring blood levels of beta amyloid peptides, Aβ-42 was assessed at the lowest levels in physiological ageing and correlated with miR-28-5p and let-7d-5p in DS, while Aβ-40 correlated with miR-628-5p in the same cohort. New perspectives in terms of biomarkers are discussed

Modeling of Surface Damage at the Si/SiO2_2-interface of Irradiated MOS-capacitors

Surface damage caused by ionizing radiation in SiO$_2$ passivated silicon particle detectors consists mainly of the accumulation of a positively charged layer along with trapped-oxide-charge and interface traps inside the oxide and close to the Si/SiO$_2$-interface. High density positive interface net charge can be detrimental to the operation of a multi-channel $n$-on-$p$ sensor since the inversion layer generated under the Si/SiO$_2$-interface can cause loss of position resolution by creating a conduction channel between the electrodes. In the investigation of the radiation-induced accumulation of oxide charge and interface traps, a capacitance-voltage characterization study of n/$\gamma$- and $\gamma$-irradiated Metal-Oxide-Semiconductor (MOS) capacitors showed that close agreement between measurement and simulation were possible when oxide charge density was complemented by both acceptor- and donor-type deep interface traps with densities comparable to the oxide charges. Corresponding inter-strip resistance simulations of a $n$-on-$p$ sensor with the tuned oxide charge density and interface traps show close agreement with experimental results. The beneficial impact of radiation-induced accumulation of deep interface traps on inter-electrode isolation may be considered in the optimization of the processing parameters of isolation implants on $n$-on-$p$ sensors for the extreme radiation environments.Comment: Corresponding author: T. Peltola. 24 pages, 17 figures, 6 table

Iron carbonate formation kinetics onto corroding and pre-filmed carbon steel surfaces in carbon dioxide corrosion environments

This work investigates the Corrosion Layer Accumulation Rate (CLAR) of iron carbonate (FeCO3) onto X65 carbon steel in carbon dioxide containing environments using the direct method of corrosion layer mass gain measurement. Glass cell experiments were performed at 80 °C and pH 6.3 or 6.8 over a range of bulk FeCO3 saturation ratios using both actively corroding carbon steel and steel pre-filmed with FeCO3. The CLARs obtained from experiments using actively corroding samples displayed strong agreement with the most recently developed precipitation model by Sun and Nesic at high supersaturation for pH 6.3 and 6.8, but a disparity at low supersaturation for the solution at pH 6.8. The observed discrepancy was attributed to the significant difference in surface saturation ratio between the two conditions when the steel is actively corroding. CLARs determined for pre-FeCO3 filmed carbon steel show that the kinetics of FeCO3 formation reduce significantly once the film establishes a protective barrier at lower values of bulk supersaturation. The results highlight the contrast between surface layer accumulation kinetics in the early stages of growth and those encountered in the long-term after the development of a protective film

Correction to: GloPL,a Global Data Base on Pollen Limitation of Plant Reproduction (Scientific Data, (2018), 5, (180249), 10.1038/sdata.2018.249)

J. H. Burns was omitted in error from the author list of the original version of this Data Descriptor. This omission has now been corrected in both the HTML and PDF versions

In situ SR-XRD study of FeCO₃ precipitation kinetics onto carbon steel in CO₂-containing environments: The influence of brine pH

The growth of iron carbonate (FeCO₃) on the internal walls of carbon steel pipelines used for oil and gas transportation can reduce internal corrosion significantly. Solution pH can be considered as one of the most influential factors with regards to the kinetics, morphology and protection afforded by FeCO₃ films. This paper presents results from a recently developed in situ Synchrotron Radiation-X-ray Diffraction (SR-XRD) flow cell integrated with electrochemistry for corrosion measurements. The cell was used to follow the nucleation and growth kinetics of corrosion products on X65 carbon steel surfaces in a carbon dioxide (CO₂)-saturated 3.5 wt.% NaCl brine at 80 °C and a flow rate of 0.1 m/s over a range of solution pH values (6.3, 6.8 and 7). In all conditions, FeCO₃ was identified as the only crystalline phase to form. Electrochemical results coupled with post-test surface analysis indicate that at higher pH, larger portions of the surface become covered faster with thinner, more protective films consisting of smaller, denser and more compact crystals. The comparison between XRD main peak area intensities and FeCO₃ surface coverage, mass and volume indicates a qualitative relationship between these parameters at each pH, providing valuable information on the kinetics of film growth

Charge Collection and Electrical Characterization of Neutron Irradiated Silicon Pad Detectors for the CMS High Granularity Calorimeter

The replacement of the existing endcap calorimeter in the Compact Muon Solenoid (CMS) detector for the high-luminosity LHC (HL-LHC), scheduled for 2027, will be a high granularity calorimeter. It will provide detailed position, energy, and timing information on electromagnetic and hadronic showers in the immense pileup of the HL-LHC. The High Granularity Calorimeter (HGCAL) will use 120-, 200-, and 300-$\mu\textrm{m}$ thick silicon (Si) pad sensors as the main active material and will sustain 1-MeV neutron equivalent fluences up to about $10^{16}~\textrm{n}_\textrm{eq}\textrm{cm}^{-2}$. In order to address the performance degradation of the Si detectors caused by the intense radiation environment, irradiation campaigns of test diode samples from 8-inch and 6-inch wafers were performed in two reactors. Characterization of the electrical and charge collection properties after irradiation involved both bulk polarities for the three sensor thicknesses. Since the Si sensors will be operated at -30 $^\circ$C to reduce increasing bulk leakage current with fluence, the charge collection investigation of 30 irradiated samples was carried out with the infrared-TCT setup at -30 $^\circ$C. TCAD simulation results at the lower fluences are in close agreement with the experimental results and provide predictions of sensor performance for the lower fluence regions not covered by the experimental study. All investigated sensors display 60$\%$ or higher charge collection efficiency at their respective highest lifetime fluences when operated at 800 V, and display above 90$\%$ at the lowest fluence, at 600 V. The collected charge close to the fluence of $10^{16}~\textrm{n}_\textrm{eq}\textrm{cm}^{-2}$ exceeds 1 fC at voltages beyond 800 V.Comment: 36 pages, 34 figure

Association between fat-soluble vitamins and self-reported health status: A cross-sectional analysis of the MARK-AGE cohort

Self-rated health (SRH) is associated with higher risk of death. Since low plasma levels of fat-soluble vitamins are related to mortality, we aimed to assess whether plasma concentrations of vitamins A, D and E were associated with SRH in the MARK-AGE study. We included 3158 participants (52% female) aged between 35-75 years. Cross-sectional data were collected via questionnaires. An enzyme immunoassay quantified 25-hydroxyvitamin D and HPLC determined α-tocopherol and retinol plasma concentrations. The median 25-hydroxyvitamin D and retinol concentrations differed significantly (P<0.001) between SRH categories, and were lower in the combined fair/poor category versus the excellent, very good, good categories (25-hydroxvitamin D: 40.8 vs. 51.9, 49.3, 46.7 nmol/l, respectively; retinol: 1.67 vs. 1.75, 1.74, 1.70 μmol/l, respectively). Both vitamin D and retinol status were independently associated with fair/poor SRH in multiple regression analyses: adjusted ORs (95% CI) for the vitamin D insufficiency, deficiency, severe deficiency categories were 1.33 (1.06-1.68), 1.50 (1.17-1.93), and 1.83 (1.34-2.50) respectively; P=0.015, P=0.001, P<0.001, and for the second/third/fourth retinol quartiles: 1.44 (1.18-1.75), 1.57 (1.28-1.93), 1.49 (1.20-1.84); all P<0.001. No significant associations were reported for α-tocopherol quartiles. Lower vitamin A and D status emerged as independent markers for fair/poor SRH. Further insights into the long-term implications of these modifiable nutrients on health status are warranted

Relative Stability of Core Groups in Pollination Networks in a Biodiversity Hotspot over Four Years

Plants and their pollinators form pollination networks integral to the evolution and persistence of species in communities. Previous studies suggest that pollination network structure remains nested while network composition is highly dynamic. However, little is known about temporal variation in the structure and function of plant-pollinator networks, especially in species-rich communities where the strength of pollinator competition is predicted to be high. Here we quantify temporal variation of pollination networks over four consecutive years in an alpine meadow in the Hengduan Mountains biodiversity hotspot in China. We found that ranked positions and idiosyncratic temperatures of both plants and pollinators were more conservative between consecutive years than in non-consecutive years. Although network compositions exhibited high turnover, generalized core groups – decomposed by a k-core algorithm – were much more stable than peripheral groups. Given the high rate of turnover observed, we suggest that identical plants and pollinators that persist for at least two successive years sustain pollination services at the community level. Our data do not support theoretical predictions of a high proportion of specialized links within species-rich communities. Plants were relatively specialized, exhibiting less variability in pollinator composition at pollinator functional group level than at the species level. Both specialized and generalized plants experienced narrow variation in functional pollinator groups. The dynamic nature of pollination networks in the alpine meadow demonstrates the potential for networks to mitigate the effects of fluctuations in species composition in a high biodiversity area