A highly enantioselective biocatalytic dynamic kinetic resolution (DKR) of configurationally labile N-arylindole aldehydes is described. The DKR proceeds by atroposelective bioreduction of the ...carbonyl group catalyzed by commercial ketoreductases (KREDs), thus affording the corresponding axially chiral N-arylindole aminoalcohols, with excellent conversions and optical purities. The strategy relies on the racemization of the stereogenic axis that takes place thanks to a transient Lewis pair interaction between the NMe2 and the aldehyde groups. This protocol features a broad substrate scope under very mild conditions.
Abstract
FU Orionis–type stars are young stellar objects showing large outbursts due to highly enhanced accretion from the circumstellar disk onto the protostar. FU Orionis–type object (FUor) ...outbursts happen in a wide variety of sources from the very embedded ones to those with almost no sign of extended emission beyond the disk. The subsequent eruptions might gradually clear up the obscuring envelope material and drive the protostar on its way to become a disk-only T Tauri star. We used the Very Large Telescope (VLT)/VLT spectrometer and imager for the mid-infrared (VISIR) to obtain the first spectra that cover the 8–13
μ
m mid-infrared wavelength range in low resolution of five recently discovered FUors. Four objects from our sample show the 10
μ
m silicate feature in emission. We study the shape and strength of the silicate feature in these objects and find that they mostly contain large amorphous grains, suggesting that large grains are typically not settled to the midplane in FUor disks. This is a general characteristic of FUors, as opposed to regular T Tauri–type stars whose disks display anything from pristine small grains to significant grain growth. We classify our targets by determining whether the silicate feature is in emission or in absorption, and confront them with the evolutionary scenarios on the dispersal of the envelopes around young stars. In our sample, all Class II objects exhibit silicate emission, while for Class I objects, the appearance of the feature in emission or absorption depends on the viewing angle with respect to the outflow cavity. This highlights the importance of geometric effects when interpreting the silicate feature.
This paper proposes a computational technique for the classification of electricity consumption profiles. The methodology is comprised of two steps. In the first one, a C-means-based fuzzy clustering ...is performed in order to find consumers with similar consumption profiles. Afterwards, a fuzzy classification is performed using a fuzzy membership matrix and the Euclidean distance to the cluster centers. Then, the distance measures are normalized and ordered, yielding a unitary index score, where the potential fraudsters or users with irregular patterns of consumption have the highest scores. The approach was tested and validated on a real database, showing good performance in tasks of fraud and measurement defect detection.
Summary
Alternative strategies are required to enhance the diagnosis of silent hepatitis C virus (HCV) infections in key populations at risk. Among them, HCV prevalence and bio‐behavioural data are ...scarce for HIV‐negative men who have sex with men (MSM) and men and trans‐women sex workers. We sought to describe and assess the potential benefits of a community‐based one‐step HCV screening and confirmatory strategy for these populations in Barcelona. The screening strategy based on a real‐time RT‐PCR assay for HCV‐RNA detection in dried‐blood spots (DBS) was validated and implemented in addition to an antibody point‐of‐care test in a community centre. HCV prevalence was assessed, and bio‐behavioural data were collected. The molecular assay was precise, reproducible, sensitive and specific. Four HIV‐negative MSM reported being currently infected (0.75% HCV self‐reported prevalence). Implementation of DBS testing was easy, and acceptability was >95%, but no silent HCV case was diagnosed (N = 580). High‐risk sexual practices and drug use for sex were reported frequently. HIV prevalence was 4.7% in MSM and 10% in sex workers. Self‐reported prevalence of other STIs ranged from 11.3% to 36.2%. In conclusion, HCV‐RNA testing in DBS showed a good performance, but the assessed one‐step strategy does not seem beneficial in this setting. Although no silent HCV infections were detected, the observed high‐risk behaviours and prevalence of other STIs suggest that HCV spread should be periodically monitored among these populations in Barcelona by means of behavioural surveillance, rapid antibody testing and molecular confirmation in DBS.
In this study, we report U–Pb Laser Ablation ICP-MS zircon and ID-TIMS monazite ages for peraluminous granitoid plutons (biotite ± muscovite ± cordierite ± sillimanite) in the Tormes Dome, one of the ...gneiss-cored domes located in the Central Iberian Zone of the Variscan belt of northern Spain. Textural domains in zircon, interpreted to represent the magmatic crystallization of the granitoids (and one monazite fraction in the Ledesma pluton) yielded ages around 320 Ma, in agreement with other geochronological studies in the region. This age is interpreted to date the timing of decompression crustal melting driven by the extensional collapse of the orogenic belt in this domain of the Variscan chain of western Europe. In addition, there are several populations of inherited (xenocrystic) zircon: (1) Carboniferous zircon crystals (ca. 345 Ma) as well as one of the monazite fractions in the coarse-grained facies of the Ledesma pluton that also yielded an age of ca. 343 Ma. (2) Devonian–Silurian zircon xenocrysts with scattered ages between ca. 390 and 432 Ma. (3) Middle Cambrian–Ordovician (ca. 450–511 Ma). (4) Ediacaran–Cryogenian zircon ages (ca. 540–840 Ma). (5) Mesoproterozoic to Archaean zircon (900–2700 Ma). The abundance of Carboniferous-inherited zircon shows that crustal recycling/cannibalization may often happen at a fast pace in orogenic scenarios with only short lapses of quiescence. In our case study, it seems plausible that a “crustal layer” of ca. 340 Ma granitoids/migmatites was recycled, partially or totally, only 15–20 My after its emplacement.
ABSTRACT
We report first results on a method aimed at simultaneously characterizing atmospheric parameters and magnetic properties of M dwarfs from high-resolution near-IR spectra recorded with ...SPIRou in the framework of the SPIRou Legacy Survey (SLS). Our analysis relies on fitting synthetic spectra computed from marcs model atmospheres to selected spectral lines, both sensitive and insensitive to magnetic fields. We introduce a new code, ZeeTurbo, obtained by including the Zeeman effect and polarized radiative transfer capabilities to Turbospectrum. We compute a grid of synthetic spectra with ZeeTurbo for different magnetic field strengths and develop a process to simultaneously constrain Teff, log g, $\rm {M/H}$, $\rm {\alpha /Fe}$, and the average surface magnetic flux. In this paper, we present our approach and assess its performance using simulations, before applying it to six targets observed in the context of the SLS, namely AU Mic, EV Lac, AD Leo, CN Leo, PM J18482+0741, and DS Leo. Our method allows us to retrieve atmospheric parameters in good agreement with the literature, and simultaneously yields surface magnetic fluxes in the range 2–4 kG with a typical precision of 0.05 kG, in agreement with literature estimates, and consistent with the saturated dynamo regime in which most of these stars are.
Background and aims
Immunoglobulin G4‐associated cholangitis (IAC) is characterized by distinctly elevated immunoglobulin G4 in serum (sIgG4) and responds well to corticosteroid therapy. Primary ...Sclerosing Cholangitis (PSC) is a progressive liver disease without causal treatment options usually not responding to immunosuppression. Increased serum levels of sIgG4 in patients with PSC, that do not meet criteria of IAC, have been reported in 10%‐25%. Therefore, we aimed to characterize this subgroup of patients in a retrospective, multicenter study.
Methods
sIgG4 values of 289 patients with PSC from three German university hospitals were analysed. Patients with elevated sIgG4 levels were identified and further characterized by clinical and biochemical parameters and by cholangiographic presentation. Clinical endpoints, death and liver transplantation were compared between groups. Parameters associated with outcome were identified with Cox regression analysis.
Results
14.5% of patients with PSC showed increased sIgG4 levels (PSC‐IgG4), presented with significantly higher (P < .02) albumin, aspartate‐aminotransferase, bilirubin and alkaline phosphatase and had a significant lower prevalence of a concomitant autoimmune hepatitis (P = .025). Cholangiogram obtained via ERC showed extrahepatic dominant strictures more often in the PSC‐IgG4 subgroup (P = .047). The disease severity models Amsterdam‐Oxford‐Score (P = .018) and Mayo‐Risk‐Score (P = .025) predicted lower survival rates for the PSC‐IgG4 subgroup. Transplant‐free survival after first diagnosis of PSC was shorter in patients with elevated sIgG4 (11.6 vs 15.1 years, P = .001).
Conclusion
Patients with PSC and elevated sIgG4 should be considered as a distinct subgroup, characterized by different clinical and cholangiographical features and are associated with an inferior outcome.
A highly enantioselective biocatalytic dynamic kinetic resolution (DKR) of 2‐(quinoline‐8‐yl) 3‐methylbenzaldehydes and 1‐naphthaldehydes is described. The reaction proceeds by atroposelective ...carbonyl reduction catalyzed by commercial ketoreductases (KREDs), generally reaching high conversions and excellent enantiomeric excesses. Both atropoisomers of the final alcohols can be obtained by a proper selection of the biocatalyst. The DKR strategy relies in the racemization of the stereogenic axis that takes place thanks to a transient Lewis acid‐base interaction (LABI) between the nitrogen in the quinoline and the carbonyl group.
Sporadic-E (Es) occurrence rates from Global Position Satellite radio occultation (GPS-RO) measurements have shown to vary by a factor of five between studies, motivating the need for a comparison ...with ground-based measurements. In an attempt to find accurate GPS-RO techniques for detecting Es formation, occurrence rates derived using five previously developed GPS-RO techniques are compared to ionosonde measurements over an eight-year period from 2010–2017. GPS-RO measurements within 170 km of a ionosonde site are used to calculate Es occurrence rates and compared to the ground-truth ionosonde measurements. The techniques are compared individually for each ionosonde site and then combined to determine the most accurate GPS-RO technique for two thresholds on sporadic-E intensity: no lower limit and fbEs ≥3 MHz. Overall, the YuS4 method shows the closest agreement with ionosonde measurements for total Es occurrence rates without a lower limit on intensity, while the phase-based Chu technique shows the closest agreement for fbEs ≥3 MHz. This analysis demonstrates that the variation in GPS-RO derived sporadic-E occurrence rates is due to varying thresholds on the sporadic-E intensities in terms of fbEs.
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