We apply the double‐beamforming tomography to a monthlong temporary dense seismic array to obtain high‐resolution images of the San Jacinto Fault's damage zone. We obtain Rayleigh waves between 0.3‐ ...and 0.8‐s periods via vertical‐vertical noise cross correlation, apply double beamforming to obtain phase velocities, and apply a piecewise 1‐D least squares inversion to obtain shear velocities in the top 300 m. We observe a ~200‐m‐wide low‐velocity zone that narrows with depth, which we interpret as the main damage zone in addition to two other ~100‐m‐wide subsidiary zones corresponding to secondary damaged structures, agreeing with the distribution of fault zone trapped waves produced by local earthquakes. The primary damage zone asymmetry indicates that materials on the northeast side of the fault are stiffer at seismogenic depth and suggests that large San Jacinto earthquakes tend to nucleate to the southeast and propagate to the northwest.
Key Points
We present shear wave velocities in the upper 300 m at the San Jacinto Fault, Clark segment
The damage zone is asymmetric, with more damage to the northeast of the fault trace
The damage zone geometry agrees with fault zone trapped waves generated by local earthquakes
Design of stable adsorbents for selective gold recovery with large capacity and fast adsorption kinetics is of great challenge, but significant for the economy and the environment. Herein, we show ...the design and preparation of an irreversible amide‐linked covalent organic framework (COF) JNU‐1 via a building block exchange strategy for efficient recovery of gold. JNU‐1 was synthesized through the exchange of 4,4′‐biphenyldicarboxaldehyde (BA) in mother COF TzBA consisting of 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)trianiline (Tz) and BA with terephthaloyl chloride. The irreversible amide linked JNU‐1 gave good stability, unprecedented fast kinetics, excellent selectivity and outstanding adsorption capacity for gold recovery. X‐ray photoelectron spectroscopy along with thermodynamic study and quantum mechanics calculation reveals that the excellent performance of JNU‐1 for gold recovery results from the formation of hydrogen bonds C(N)−H⋅⋅⋅Cl and coordinate interaction of O and Au. The rational design of irreversible bonds as both inherent linkage and functional groups in COFs is a promising way to prepare stable COFs for diverse applications.
Going for gold: A building‐block exchange strategy gave an irreversible amide‐linked covalent organic framework (COF). The irreversible‐amide linked COF gave good stability, unprecedented fast adsorption kinetics, excellent selectivity and outstanding adsorption capacity for gold recovery.
Mantle seismic structure beneath the United States spanning from the active western plate margin to the passive eastern margin was imaged with teleseismic P and S wave traveltime tomography including ...USArray data up to May 2014. To mitigate artifacts from crustal structure 5–40 s, Rayleigh wave phase velocities were used to create a 3‐D starting model. Major features of the final P and S models include two distinct low‐velocity anomalies at depths of ~60–300 km beneath the central and northern Appalachians and passive margin. The central Appalachian low‐velocity anomaly coincides with Eocene basaltic magmatism, and the northern anomaly is located along the Cretaceous track of the Great Meteor hot spot. At depths of ~300–700 km beneath the central and eastern U.S. large high‐velocity anomalies are inferred to be remnants of the Farallon slab that subducted prior to ~40 Ma during the Laramide orogeny.
Key Points
P wave and S wave mantle tomography spanning the contiguous U.S.Passive margin low‐velocity anomalies linked to Cenozoic and Mesozoic volcanismSome Laramide‐age slab fragments have yet to sink into the lower mantle
Seismic structure beneath the contiguous U.S. was imaged with multimode receiver function stacking and inversion of Rayleigh wave dispersion and ellipticity measurements. Crust thickness and ...elevation are weakly correlated across the contiguous U.S., but the correlation is ~3–4 times greater for separate areas east and west of the Rocky Mountain Front (RMF). Greater lower crustal shear velocities east of the RMF, particularly in low‐elevation areas with thick crust, are consistent with deep crustal density as the primary cause of the contrasting crust thickness versus elevation trends. Separate eastern and western trends are best fit by Airy isostasy models that assume lower crust to uppermost mantle density increases of 0.18 g/cm3 and 0.40 g/cm3, respectively. The former value is near the minimum that is plausible for felsic lower crust. Location of the transition at the RMF suggests that Laramide to post‐Laramide processes reduced western U.S. lower crustal density.
Key Points
Distinct crustal isostasy trends identified east and west of the Rocky Mountain Front
East of the RMF mean lower crust to mantle density contrast is about half that in the west
Laramide to post‐Laramide processes likely reduced the density of western U.S. lower crust
A novel and practical fluoroalkyl radical-initiated cascade reaction was developed to access diverse 2-fluoroalkylbenzothiazoles by reacting various fluoroalkyl radical sources, including ...perfluoroalkyl iodide (IC n F2n+1, n = 3–8, 10), ICF(CF3)2, ICF2COOEt, ICF2CF2Cl, or ICF2CF2Br, tetramethylethane-1,2-diamine (TMEDA), and 2-isocyanoaryl thioethers in tetrahydrofuran under nitrogen atmosphere and blue-light irradiation conditions. Furthermore, this one-pot protocol could well be expanded to access various 2-fluoroalkylbenzoselenazoles starting from (2-isocyanophenyl)(methyl)selane, perfluoroalkyl iodides (IC n F2n+1, n = 3–8) or ICF2COOEt and TMEDA.
To better inform efforts to treat and control the current outbreak with a comprehensive characterization of COVID-19.
We searched PubMed, EMBASE, Web of Science, and CNKI (Chinese Database) for ...studies published as of March 2, 2020, and we searched references of identified articles. Studies were reviewed for methodological quality. A random-effects model was used to pool results. Heterogeneity was assessed using I2. Publication bias was assessed using Egger's test.
43 studies involving 3600 patients were included. Among COVID-19 patients, fever (83.3% 95% CI 78.4–87.7), cough (60.3% 54.2–66.3), and fatigue (38.0% 29.8–46.5) were the most common clinical symptoms. The most common laboratory abnormalities were elevated C-reactive protein (68.6% 58.2–78.2), decreased lymphocyte count (57.4% 44.8–69.5) and increased lactate dehydrogenase (51.6% 31.4–71.6). Ground-glass opacities (80.0% 67.3–90.4) and bilateral pneumonia (73.2% 63.4–82.1) were the most frequently reported findings on computed tomography. The overall estimated proportion of severe cases and case-fatality rate (CFR) was 25.6% (17.4–34.9) and 3.6% (1.1–7.2), respectively. CFR and laboratory abnormalities were higher in severe cases, patients from Wuhan, and older patients, but CFR did not differ by gender.
The majority of COVID-19 cases are symptomatic with a moderate CFR. Patients living in Wuhan, older patients, and those with medical comorbidities tend to have more severe clinical symptoms and higher CFR.
Female-to-male (FTM) transgender men (affirmed males) can experience planned and unplanned pregnancy during and after testosterone therapy. We conducted an exploratory study to understand current ...contraceptive practices and fertility desires among transgender men during and after transitioning.
Self-identified transgender and transmasculine individuals assigned female at birth, ages 18–45, completed an anonymous online survey derived from standardized family planning surveys. We recruited participants from LGBT health centers, online listservs, and online groups for transgender men and used a mixed-methods analysis to evaluate quantitative and qualitative data.
Of the one hundred and ninety-seven participants included in the study, the median age was 30 years old, most respondents were white, and 86% were taking masculinizing hormones (testosterone). Of the 60 pregnancies reported, 10 (17%) pregnancies occurred after stopping testosterone, 1 (1.6%) while taking testosterone irregularly, and 5 of 7 abortions occurred in participants who had been using testosterone in the past. Over half of the respondents desired at least one child, and a quarter reported fears of not getting pregnant. The majority of participants reporting using contraception (n=110, 60.1%), with condoms and pills used most commonly (n=90, 49.2% and n=62, 33.9% respectively). Methods of contraception used did not differ between testosterone users and non-users, except for hormonal IUDs (20% testosterone versus 7% non-testosterone). Thirty participants (16.4%) believed that testosterone was a form of contraception, and 10 (5.5%) participants reported that their healthcare providers advised testosterone as contraception.
Transgender men use contraception and can experience pregnancy and abortion, even after transitioning socially and hormonally. Transgender men need counseling and care regarding reproductive health, including contraceptive and conception counseling.
Providers should be aware that transgender men may desire pregnancy and use contraception; this study highlights the need for further research regarding fertility, fertility desires, and optimal contraception among transgender men.
Driven by the persisting poor understanding of the sluggish kinetics of the hydrogen evolution reaction (HER) on Pt in alkaline media, a direct correlation of the interfacial water structure and ...activity is still yet to be established. Herein, using Pt and Pt–Ni nanoparticles we first demonstrate a strong dependence of the proton donor structure on the HER activity and pH. The structure of the first layer changes from the proton acceptors to the donors with increasing pH. In the base, the reactivity of the interfacial water varied its structure, and the activation energies of water dissociation increased in the sequence: the dangling O−H bonds < the trihedrally coordinated water < the tetrahedrally coordinated water. Moreover, optimizing the adsorption of H and OH intermediates can re‐orientate the interfacial water molecules with their H atoms pointing towards the electrode surface, thereby enhancing the kinetics of HER. Our results clarified the dynamic role of the water structure at the electrode–electrolyte interface during HER and the design of highly efficient HER catalysts.
On nickel–platinum alloy nanoparticles under alkaline conditions, the reactivity of interfacial water varies with its structure and the order of water dissociation. The inclusion of nickel re‐orientates interfacial water molecules with their hydrogen atoms pointing towards the electrode surface, thereby enhancing the kinetics of the hydrogen evolution reaction (HER).
Mantle shear velocity (Vs) structure beneath the Transportable Array (TA) in Alaska and northwestern Canada is imaged by joint inversion of Rayleigh wave dispersion and teleseismic S wave travel ...times. The study connects previously unsampled parts of northern and western Alaska with portions of southern Alaska imaged with earlier seismic arrays. The new Vs tomography shows contrasting lithospheric structure in the plate interior with lower Vs shallow upper mantle indicative of thinner thermal lithosphere south of the Brooks Range and along the transform margin. Higher Vs down to ~200 km beneath the Brooks Range and northern coast is consistent with the presence of a cold stable lithospheric root that may help guide intraplate deformation to the south. In the subduction‐to‐transform transition, a potential slab fragment is imaged beneath the Wrangell volcanic field where modern subduction has slowed due to the thick buoyant crust of the Yakutat terrane.
Plain Language Summary
We use a groundbreaking seismic data set from the EarthScope project to investigate the structure of the upper mantle beneath Alaska and northwestern Canada to better understand the effects of ongoing subduction and distinctive blocks within the continental lithosphere. Measurements of seismic body and surface waves are used to construct seismic images from the surface down to 800‐km depth. The images reveal cold thick blocks beneath northern Alaska and the Yukon Territory adjacent to warmer thinner blocks beneath younger geologic provinces to the south, suggesting that cold strong lithosphere in the north helps guide the extent of intraplate deformation driven by the southern plate boundary. The model also identifies a potential slab fragment beneath the Wrangell volcanic field, suggesting slab contributions to volcanic activity and a growing slab tear.
Key Points
Upper mantle Rayleigh and S wave tomography using the full Transportable Array in Alaska
Thick high Vs lithosphere is found beneath the western Brooks Range and Arctic coast
A high Vs potential slab fragment is identified beneath the Wrangell volcanic field
The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in the world. An understanding of its properties is key to enhancing our knowledge of volcanic mechanisms ...and corresponding risk. Using a joint local and teleseismic earthquake P-wave seismic inversion, we revealed a basaltic lower-crustal magma body that provides a magmatic link between the Yellowstone mantle plume and the previously imaged upper-crustal magma reservoir. This lower-crustal magma body has a volume of 46,000 cubic kilometers, ∼4.5 times that of the upper-crustal magma reservoir, and contains a melt fraction of ∼2%. These estimates are critical to understanding the evolution of bimodal basaltic-rhyolitic volcanism, explaining the magnitude of CO2 discharge, and constraining dynamic models of the magmatic system for volcanic hazard assessment.
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