The stress shadow induced by the 1975-1984 Krafla rifting episode

It has been posited that the 1975\u20131984 Krafla rifting episode in northern Iceland was responsible for a significant drop in the rate of earthquakes along the H\ufasav\uedk\u2010Flatey Fault (HFF), a transform fault that had previously been the source of several magnitude 6\u20137 earthquakes. This compelling case of the existence of a stress shadow has never been studied in detail, and the implications of such a stress shadow remain an open question. According to rate\u2010state models, intense stress shadows cause tens of years of low seismicity rate followed by a faster recovery phase of rate increase. Here, we compare the long\u2010term predictions from a Coulomb stress model of the rifting episode with seismological observations from the SIL catalog (1995\u20132011) in northern Iceland. In the analyzed time frame, we find that the rift\u2010induced stress shadow coincides with the eastern half of the fault where the observed seismicity rates are found to be significantly lower than expected, given the historical earthquake activity there. We also find that the seismicity rates on the central part of the HFF increased significantly in the last 17 years, with the seismicity progressively recovering from west to east. Our observations confirm that rate\u2010state theory successfully describes the long\u2010term seismic rate variation during the reloading phase of a fault invested by a negative Coulomb stress. Coincident with this recovery, we find that the b\u2010value of the frequency\u2010magnitude distribution changed significantly over time. We conclude that the rift\u2010induced stress shadow not only decreased the seismic rate on the eastern part of the HFF but also temporarily modified how the system releases seismic energy, with more large magnitude events in proportion to small ones. This behavior is currently being overturned, as rift\u2010induced locking is now being compensated by tectonic forcing

Experiments of convective evaporation of refrigerant R513A in a horizontal stainless-steel tube

Refrigerant R513A represents an interesting solution for the retrofit of conventional high-GWP fluorinated gases, such as R134a, R401A, R401B and R409A for low and medium temperature applications. R513A is an azeotropic mixture (almost zero-temperature glide at any operating pressure) made up of R134a and R1234yf (44% and 56% in mass, respectively), allowing at the same time a very low GWP of 580 and favourable safety characteristics such as no flammability and no toxicity (A1 ASHRAE class). The boiling performance of this blend is scarcely explored and studied in scientific literature, especially in case of commercial tubes typically adopted for refrigeration purposes. For this reason, this paper presents two-phase flow boiling experiments of refrigerant R513A in a 6.00 mm horizontal stainless-steel tube. Heat is provided by means of Joule effect directly on the tube surface, and the peripheral average heat transfer coefficients are obtained by measuring the temperatures at four sides (top, bottom, left and right) of the channel. The effect of the operating conditions is experimented and discussed, by varying the mass flux between 150 and 300 kg/m2 s, saturation temperature between 20 and 50°C and imposed heat flux between 5 and 20 kW/m2. Also, a comparison with the boiling performance of refrigerant R134a is proposed within the same operating conditions. Finally, the assessment of well-known flow boiling prediction methods is presented and discussed

Stress inversions to forecast magma pathways and eruptive vent location

When a batch of magma reaches Earth\u2019s surface, it forms a vent from which volcanic products are erupted. At many volcanoes, successive batches may open vents far away from previous ones, resulting in scattered, sometimes seemingly random spatial distributions. This exposes vast areas to volcanic hazards and makes forecasting difficult. Here, we show that magma pathways and thus future vent locations may be forecast by combining the physics of magma transport with a Monte Carlo inversion scheme for the volcano stress history. We validate our approach on a densely populated active volcanic field, Campi Flegrei (Italy), where we forecast future vents on an onshore semi-annular belt located between 2.3 and 4.2 km from the caldera center. Our approach offers a mechanical explanation for the vent migration over time at Campi Flegrei and at many calderas worldwide and may be applicable to volcanoes of any type

Synthesis, variable temperature NMR investigations and solid state characterisation of novel octafluorofluorene compounds

The preparation of a number of new 9-substituted octafluorofluorene derivatives, solution NMR studies, and the first examples of solid state structures of octafluorofluorenes [1,2,3,4,5,6,7,8-octafluorofluorene, C13H2F8, 1; 1,2,3,4,5,6,7,8-octafluoro-9-(pentafluoro)phenylfluorene, C19HF13, 8; 1,1′,2,2′,3,3′,4,4′,5,5′,6,6′,7,7′,8,8′-hexadecafluoro-9,9′-bifluorenyl, C26H2F16, 11] are reported. Variable temperature 19F NMR investigations have been performed on the 9-aryl substituted compounds 1,2,3,4,5,6,7,8-octafluoro-9-(pentafluoro)phenyl-9-hydroxyfluorene, C19HF13O, 4, 1,2,3,4,5,6,7,8-octafluoro-9-(nonafluoro-4′-biphenylyl)-9-hydroxyfluorene, C25HF17O, 5, and 8, and the energetic barriers to rotation of the aryl have been determined. A lower rotational barrier is observed for compound 4 with respect to compound 8, while 5 does not show fluxional behaviour below 338 K. The results of the variable temperature experiments performed on 8 have been rationalized by 2D NMR studies, and compared to the solid state data resulting from the X-ray structural analysis

Pseudoangiomatous stromal hyperplasia: an unsuspected cause of anisomasty

Breast asymmetry can be congenital or developmental, however a tumorous growth may be the cause of this condition after puberty. A 19-year-old female presented with a slowly developing breast asymmetry pre-operatively diagnosed as Pseudoangiomatous Stromal Hyperplasia (PASH). The patient underwent tumour excision with breast gland remodelling. Postoperative course was uneventful

Impedance measurements and simulations on the TCT and TDI LHC collimators

The LHC collimation system is a critical element for the safe operation of the LHC machine and it is subject to continuous performance monitoring, hardware upgrade and optimization. In this work we will address the impact on impedance of the upgrades performed on the injection protection target dump (TDI), where the absorber material has been changed to mitigate the device heating observed in machine operation, and on selected secondary (TCS) and tertiary (TCT) collimators, where beam position monitors (BPM) have been embedded for faster jaw alignment. Con- cerning the TDI, we will present the RF measurements per- formed before and after the upgrade, comparing the result to heating and tune shift beam measurements. For the TCTs, we will study how the higher order modes (HOM) intro- duced by the BPM addition have been cured by means of ferrite placement in the device. The impedance mitigation campaign has been supported by RF measurements whose results are in good agreement with GdfidL and CST simula- tions. The presence of undamped low frequency modes is proved not to be detrimental to the safe LHC operation

A case study on the application of the MSFD to Mediterranean coastal systems: the Po plume, as a transitional water system in the Northern Adriatic basin.

1 - In the frame of the Marine Strategy Framework Directive (MSFD) of the European Community, in order to assess the Good Environmental Status (GES) of the marine coastal and estuarine waters, the eutrophication descriptors include several aspects of the phytoplankton communities (such as composition, abundance and biomass). 2 - Two oceanographic campaigns were carried out in the area off the Po River plume, where a highly dynamic frontal zone separates an inshore and an offshore system. The coupling of size structure and diagnostic pigments of phytoplankton communities in relation to different environmental contexts are tested as an expedite and informative tool to assess water quality sensu MSFD. 3 - The Po plume creates a very dynamic frontal zone, resulting in strong trophic gradients within a relatively small area. 4 - The spatio-temporal variability of salinity in coastal waters and in transitional waters plays a pivotal role in structuring phytoplankton communities. 5 - The dynamics of forcing factors drive changes in cell-size structure, in the functional group composition as well as a shift in size within the same functional group. 6 - The combination of phytoplankton size-structure and chemotaxonomic compositions is proposed as an expedite tool for investigating, at the appropriate scales, the ecology of transitional water systems

N-Methylation of Amines with Methanol Catalyzed by Iridium(I) Complexes Bearing an N, O-Functionalized NHC Ligand

A set of neutral IrBr(L-2)-(kappa C-(t)BuImCH(2)PyCH(2)OMe)] and cationic Ir(L-2)-(kappa C, N-tBuImCH(2)PyCH(2)OMe)]PF6 (L-2 = cod, (CO)(2)) Ir(I) compounds featuring a flexible lutidine-derived polydentate ligand having NHC and - OMe as donor functions have been evaluated as catalyst precursors for the N-methylation of aniline using methanol both as a reducing agent and a C1 source. The carbonyl complexes are somewhat more active than the related diene compounds with the neutral compound IrBr(CO)(2)(kappa C-(t)BuImCH(2)PyCH(2)OMe)] being the more active. A range of aromatic primary amines, including heterocyclic amines, have been selectively transformed into the corresponding N-methylamino derivatives using this catalyst at a low catalyst loading (0.1 mol %) and substoichiometric amounts of Cs2CO3 (half equiv) as a base, in methanol at 423 K. For aliphatic primary amines, selective N, N-dimethylation was achieved under the same catalytic conditions. The unselective deprotonation of the methylene linkers in IrBr(CO)(2)(kappa C-(t)BuImCH(2)PyCH(2)OMe)] affords two isomeric neutral complexes featuring a coordinated dearomatized pyridine core, which were converted into Ir(OMe)(CO)(2)(kappa C-(t)BuImCH(2)PyCH(2)OMe)] upon addition of methanol. This compound undergoes thermal activation of a C-H bond of the tert-butyl group to give the cyclometalated iridium(I) complex Ir(CO)(2){kappa C-2, C-(-CH2Me2C-ImCH(2)PyCH(2)OMe)}] featuring a bidentate C, C-coordinated NHC ligand. Mechanistic investigations support a borrowing hydrogen mechanism proceeding through iridium(I) intermediates with the methoxo complex as the catalytic active species and the cyclometalated complex as the catalyst resting state. Deuterium labeling experiments have demonstrated that both species are in equilibrium under catalytic conditions, which is consistent with the exhibited catalytic activity of the cyclometalated complex

Activation of H-H, HO-H, C(sp2)-H, C(sp3)-H, and RO-H bonds by transition-metal frustrated lewis pairs based onon M/N (M = Rh, Ir) couples

Reaction of the dimers (Cp*MCl)2(µ-Cl)2] (Cp* = 5-C5Me5) with Ph2PCH2CH2NC(NH(p-Tolyl))2 (H2L) in the presence of NaSbF6 affords the chlorido complexes Cp*MCl(¿2N, P-H2L)]SbF6] (M = Rh, 1; Ir, 2). Upon treatment with aqueous NaOH, solutions of 1 and 2 yield the corresponding complexes Cp*M(¿3N, N', P-HL)]SbF6] (M = Rh, 3; Ir, 4) in which the ligand HL presents a fac ¿3N, N', P coordination mode. Treatment of THF solutions of complexes 3 and 4 with hydrogen gas, at room temperature, results in the formation of the metal hydrido-complexes Cp*MH(¿2N, P-H2L)]SbF6] (M = Rh, 5; Ir, 6) in which the N(p-Tolyl) group has been protonated. Complexes 3 and 4 react with deuterated water in a reversible fashion resulting in the gradual deuteration of the Cp* group. Heating at 383 K THF/H2O solutions of the complexes 3 and 4 affords the orthometalated complexes Cp*M(¿3C, N, P-H2L-H)]SbF6] M = Rh, 7; Ir, 8, H2L-H = Ph2PCH2CH2NC(NH(p-Tolyl))(NH(4-C6H3Me))], respectively. At 333 K, complexes 3 and 4 react in THF with methanol, primary alcohols, or 2-propanol giving the metal-hydrido complexes 5 and 6, respectively. The reaction involves the acceptorless dehydrogenation of the alcohols at a relatively low temperature, without the assistance of an external base. The new complexes have been characterized by the usual analytical and spectroscopic methods including the X-ray diffraction determination of the crystal structures of complexes 1-5, 7, and 8. Notably, the chlorido complexes 1 and 2 crystallize both as enantiopure conglomerates and as racemates. Reaction mechanisms are proposed based on stoichiometric reactions, nuclear magnetic resonance studies, and X-ray crystallography as well as density functional theory calculations. © 2022 The Authors. Published by American Chemical Society