Geomicrobial processes in the subsurface: A tribute to Johannes Neher's work

For almost 50 years, Johannes Neher's research emphasized the significant role of microbes in geological processes. He has been searching for microbial evidence in the formation of silicates, such as cornelian, jasper, moss agate, chalcedony, and chrysocolla, as well as quartzites, itacolumnites, diamonds, dendrites on calcite, silicate horizons in limestone beds, and dolomite phenocrysts that formed in a biotite gneiss. Johannes Neher has never published his research and, thus, has caused opposition and disbelief amongst scientists. Two examples of his discoveries which are of fundamental significance in geology are briefly presented in this paper: (1) bacterially mediated precipitation of dolomite, and (2) microbial dissolution of quartz in an Alpine environmen

Perylene dye@SiO 2 core–shell nanoparticles with intense fluorescence

PD/CC@SiO2 core–shell nanoparticles (PD: perylene dye, CC: cholecalciferol/vitamin D3) were prepared using a water-based injection method. Specifically, a solution of the PD (fluorescent red (FR), fluorescent orange (FO), fluorescent yellow (FY)), CC, and octyltriethoxysilane (OTES) as a silica precursor in ethanol was injected in water at 70 °C and pH 5. The core–shell nanoparticles exhibited an outer particle diameter of 29 ± 11 nm and an inner core of 12 ± 4 nm. Suspensions (up to 10 mg mL−1) were colloidally highly stable due to the negative surface charging (−40 to −50 mV). CC efficiently allowed disturbing of the π-stacking of the PD, such that, e.g., FR/CC@SiO2 nanoparticles with 10 wt% FR showed intense emission with quantum yields near unity (98%) and without any concentration quenching. In contrast to the freely-dissolved dyes, PD in the nanoparticle core did not show any photobleaching even after 20 hours of continuous UV illumination (280 nm). As proof-of-the-concept, suspensions and thin films were realised showing intense emission from red to yellow. Exemplarily, FR/CC@SiO2 core–shell nanoparticles were examined in detail, including electron microscopy, element mapping, dynamic light scattering, infrared spectroscopy, elemental analysis, UV-Vis spectroscopy, and photoluminescence spectroscopy

A Multi-perspective Analysis of Carrier-Grade NAT Deployment

As ISPs face IPv4 address scarcity they increasingly turn to network address translation (NAT) to accommodate the address needs of their customers. Recently, ISPs have moved beyond employing NATs only directly at individual customers and instead begun deploying Carrier-Grade NATs (CGNs) to apply address translation to many independent and disparate endpoints spanning physical locations, a phenomenon that so far has received little in the way of empirical assessment. In this work we present a broad and systematic study of the deployment and behavior of these middleboxes. We develop a methodology to detect the existence of hosts behind CGNs by extracting non-routable IP addresses from peer lists we obtain by crawling the BitTorrent DHT. We complement this approach with improvements to our Netalyzr troubleshooting service, enabling us to determine a range of indicators of CGN presence as well as detailed insights into key properties of CGNs. Combining the two data sources we illustrate the scope of CGN deployment on today's Internet, and report on characteristics of commonly deployed CGNs and their effect on end users

Computational fluid dynamics modeling of symptomatic intracranial atherosclerosis may predict risk of stroke recurrence.

BackgroundPatients with symptomatic intracranial atherosclerosis (ICAS) of ≥ 70% luminal stenosis are at high risk of stroke recurrence. We aimed to evaluate the relationships between hemodynamics of ICAS revealed by computational fluid dynamics (CFD) models and risk of stroke recurrence in this patient subset.MethodsPatients with a symptomatic ICAS lesion of 70-99% luminal stenosis were screened and enrolled in this study. CFD models were reconstructed based on baseline computed tomographic angiography (CTA) source images, to reveal hemodynamics of the qualifying symptomatic ICAS lesions. Change of pressures across a lesion was represented by the ratio of post- and pre-stenotic pressures. Change of shear strain rates (SSR) across a lesion was represented by the ratio of SSRs at the stenotic throat and proximal normal vessel segment, similar for the change of flow velocities. Patients were followed up for 1 year.ResultsOverall, 32 patients (median age 65; 59.4% males) were recruited. The median pressure, SSR and velocity ratios for the ICAS lesions were 0.40 (-2.46-0.79), 4.5 (2.2-20.6), and 7.4 (5.2-12.5), respectively. SSR ratio (hazard ratio [HR] 1.027; 95% confidence interval [CI], 1.004-1.051; P = 0.023) and velocity ratio (HR 1.029; 95% CI, 1.002-1.056; P = 0.035) were significantly related to recurrent territorial ischemic stroke within 1 year by univariate Cox regression, respectively with the c-statistics of 0.776 (95% CI, 0.594-0.903; P = 0.014) and 0.776 (95% CI, 0.594-0.903; P = 0.002) in receiver operating characteristic analysis.ConclusionsHemodynamics of ICAS on CFD models reconstructed from routinely obtained CTA images may predict subsequent stroke recurrence in patients with a symptomatic ICAS lesion of 70-99% luminal stenosis

Identifying seaweed consumption by sheep using isotope analysis of their bones and teeth : Modern reference δ13C and δ15N values and their archaeological implications

This research was funded by the British Natural Environment Research Council (NERC; NER/B/S/2003/00223) and the European Social Fund and Scottish Funding Council as part of Developing Scotland’s Workforce in the Scotland 2014-2020 European Structural and Investment Fund Programme. Stable isotope values in tooth enamel were measured at the SSMIM (Paris, MNHN) with technical support of Joël Ughetto. Modern sheep mandibles and/or information on sheep herding practices on Orkney were kindly provided by Robert Mainland (Rousay), Linda Haganand Una Gordon (Holm of Aikerness), Billy Muir, Dr Kevin Woodbridge and the North Ronaldsay Sheep Court (North Ronaldsay). We would like to thank Anne Brundle, Tankerness House Museum, Orkney (Point of Cott), Dr Colleen Batey, University of Glasgow (Earl’s Bu) and ProfJane Downes and Nick Card, Orkney College, UHI (Mine Howe) for providing access to the archaeological mandibles. The authors would also like to thank Jane Outram and Mandy Jay for assistance in preparation and isotopic measurement of the vegetation samples, which were kindly collected by Robert Craigie, and Karen Chapman for preparing the mandibles. Lastly, the authors are also grateful for the constructive comments of the editors and anonymous reviewers.Peer reviewedPostprin

Phase Behavior and Substitution Limit of Mixed Cesium-Formamidinium Lead TriIodide Perovskites

The mixed cation lead iodide perovskite photovoltaics show improved stability following site substitution of cesium ions (Cs+) onto the formamidinium cation sites (FA+) of (CH(NH2)2PbI3 (FAPbI3) and increased resistance to formation of the undesirable ∂-phase. The structural phase behavior of Cs0.1FA0.9PbI3 has been investigated by neutron powder diffraction (NPD), complemented by single crystal and power X-ray diffraction and photoluminescence spectroscopy. The Cs-substitution limit has been determined to be less than 15%, and the cubic α-phase, Cs0.1FA0.9PbI3, is shown to be synthesizable in bulk and stable at 300 K. On cooling the cubic Cs0.1FA0.9PbI3, a slow, second-order cubic to tetragonal transition is observed close to 290 K, with variable temperature NPD indicating the presence of the tetragonal β-phase, adopting the space group P4/mbm between 290 and 180 K. An orthorhombic phase or twinned tetragonal phase is formed below 180 K, and the temperature for further transition to a disordered state is lowered to 125 K compared to that seen in phase pure α-FAPbI3 (140 K). These results demonstrate the importance of understanding the effect of cation site substitution on structure–property relationships in perovskite materials

Star Formation in Atomic Gas

Observations of nearby galaxies have firmly established, over a broad range of galactic environments and metallicities, that star formation occurs exclusively in the molecular phase of the interstellar medium (ISM). Theoretical models show that this association results from the correlation between chemical phase, shielding, and temperature. Interstellar gas converts from atomic to molecular only in regions that are well shielded from interstellar ultraviolet (UV) photons, and since UV photons are also the dominant source of interstellar heating, only in these shielded regions does the gas become cold enough to be subject to Jeans instability. However, while the equilibrium temperature and chemical state of interstellar gas are well-correlated, the time scale required to reach chemical equilibrium is much longer than that required to reach thermal equilibrium, and both timescales are metallicity-dependent. Here I show that the difference in time scales implies that, at metallicities below a few percent of the Solar value, well-shielded gas will reach low temperatures and proceed to star formation before the bulk of it is able to convert from atomic to molecular. As a result, at extremely low metallicities, star formation will occur in a cold atomic phase of the ISM rather than a molecular phase. I calculate the observable consequences of this result for star formation in low metallicity galaxies, and I discuss how some current numerical models for H2-regulated star-formation may need to be modified.Comment: 9 pages, 8 figures, ApJ in press; very minor changes from previous versio

A Future Tale of Two Winters? Sediment-water interface nitrogen dynamics in Lake Võrtsjärv (Estonia) during the ice-free winter 2019/2020 : [presentation]

The presentation took place at the Lahti Lakes 2021 Symposium.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 95196. Estonian University of Life Sciences ASTRA project “Value-chain based bio-economy”.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 95196. Estonian University of Life Sciences ASTRA project “Value-chain based bio-economy”