Imidazolium motif containing molecules are known to be of significant interest in diverse research areas, but there is a lack of functionalization protocols of these molecules. In a program to ...overcome this challenge, recently we developed a unique dual role of a latent imidazolium C–H bond which not only generated a metal–CNHC bond upon activation but also directed further aryl/heteroaryl C–H activation to furnish a library of potentially valuable products. Mechanistic investigation of any newly discovered catalytic reaction is at the heart of its future development for potential application in diverse fields. Motivated by this philosophy, we delineate in the present work the key mechanistic insights of this annulation reaction which unravel the crucial competition of two C–H bonds (imidazolium and aryl C–H) and two M–C bonds (M–CNHC and M–Caryl) in establishing the rate-limiting step and the alkyne-insertion regioselectivity in the reaction. Through careful isolation and X-ray structural characterization of the key seven-membered inserted intermediate along with a DFT rationale, the exclusive regioselectivity of the alkyne insertion to the M–CNHC bond was established. Kinetics studies were used to evaluate the rate-determining step of the reaction, which was found to be the initial nondirected imidazolium C–H activation step. These mechanistic insights should be useful in understanding similar C–H activation processes in general which are topical in the area of catalysis.
A new class of bi‐luminophoric dyad has been designed, consisting of an oxygen‐sensitive phosphorescent NHC–IrIII center with a remotely integrated oxygen‐insensitive fluorescent terpyridine unit. ...The new terpyridine flurophore‐integrated NHC–IrIII molecule was demonstrated as a potential ratiometric O2 probe with built‐in internal reference, exhibiting tunable dual‐emissive features, as well as highly linear and reversible O2‐response behavior.
Dyad hard with a vengeance: A new class of bi‐luminophoric dyad has been demonstrated as a potential ratiometric O2 probe with built‐in internal reference, exhibiting tunable dual‐emissive features as well as highly linear and reversible O2‐response behavior.
Deriving inspiration from the salinity of ice VII inclusions in excavated diamonds, we explore the phase behavior of quasi-two-dimensional salt water in diamond nanoconfinement via molecular dynamics ...simulations. We construct the compression-limit phase diagram for several slit widths over a wide range of gigapascal-high lateral pressures. We observe the assembly of solid-like amorphous monolayer, bilayer, and trilayer phases, distinct from the ordered structures found in both pure bulk water and quasi-two-dimensional confined water. The underlying mechanism of dehydration, caused by the disruptive presence of ions, and the concomitant destruction of the long-range order of the encapsulating water hydrogen-bond network are critically analyzed. Orientational analyses of the constrained salt-water system reveal ties to interlayer water hydrogen bonding and the preferential arrangement of ion and water layers. Our results offer fresh insight into the formation and structural characteristics of the phases exhibited by nanoconfined salt water.
The disruption of the intestinal epithelial barrier function occurs commonly in various pathologies, but the exact mechanisms responsible are unclear. The H19 long noncoding RNA (lncRNA) regulates ...the expression of different genes and has been implicated in human genetic disorders and cancer. Here, we report that H19 plays an important role in controlling the intestinal epithelial barrier function by serving as a precursor for microRNA 675 (miR-675). H19 overexpression increased the cellular abundance of miR-675, which in turn destabilized and repressed the translation of mRNAs encoding tight junction protein ZO-1 and adherens junction E-cadherin, resulting in the dysfunction of the epithelial barrier. Increasing the level of the RNA-binding protein HuR in cells overexpressing H19 prevented the stimulation of miR-675 processing from H19, promoted ZO-1 and E-cadherin expression, and restored the epithelial barrier function to a nearly normal level. In contrast, the targeted deletion of HuR in intestinal epithelial cells enhanced miR-675 production in the mucosa and delayed the recovery of the gut barrier function after exposure to mesenteric ischemia/reperfusion. These results indicate that H19 interacts with HuR and regulates the intestinal epithelial barrier function via the H19-encoded miR-675 by altering ZO-1 and E-cadherin expression posttranscriptionally.
YNi5 is an enhanced Pauli paramagnetic material, and this work is devoted to the effect of Co doping at the Ni site of YNi5. It is found that at 10% Co doping, the sample turns ferromagnetic, with a ...weak itinerant character. The critical behaviours of the 10% Co‐doped sample (i.e., YNi4.5CO0.5) in its polycrystalline form are examined through bulk magnetization measurements. The second‐order phase transition from the paramagnetic to the ferromagnetic state is confirmed by the positive slope of the Arrott plots. To obtain the most reliable values of the critical exponents, an extensive analysis of the magnetization data is performed, which includes a modified Arrott plot, Kouvel–Fisher plot, and critical isotherm analysis. The best values of the exponent obtained are β = 0.179 (±0.002), γ = 1.429 (±0.002), and TC = 9.1 K. These values are close to a 2D Ising model along with the long‐range exchange decaying as J(r) ≈ r−(3.6). It is found that this extended exchange is a typical characteristic of many itinerant ferromagnets, whereas the 2D nature is likely to be connected with the layered crystal structure.
A doping of 10% Co at the Ni site of the Pauli paramagnetic material YNi5 induces a ferromagnetic ordered state with a novel weak itinerant character. The critical point analysis on this 10% Co doped sample indicates that a 2D Ising model with extended exchange interaction over lattice spacing can characterize this fascinating weak ferromagnetic state.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the associated Coronavirus Disease 2019 (COVID-19) is a public health emergency. Acute kidney injury (AKI) is a common complication in ...hospitalized patients with COVID-19 although mechanisms underlying AKI are yet unclear. There may be a direct effect of SARS-CoV-2 virus on the kidney; however, there is currently no data linking SARS-CoV-2 viral load (VL) to AKI. We explored the association of SARS-CoV-2 VL at admission to AKI in a large diverse cohort of hospitalized patients with COVID-19.
We included patients hospitalized between March 13th and May 19th, 2020 with SARS-CoV-2 in a large academic healthcare system in New York City (N = 1,049) with available VL at admission quantified by real-time RT-PCR. We extracted clinical and outcome data from our institutional electronic health records (EHRs). AKI was defined by KDIGO guidelines. We fit a Fine-Gray competing risks model (with death as a competing risk) using demographics, comorbidities, admission severity scores, and log10 transformed VL as covariates and generated adjusted hazard ratios (aHR) and 95% Confidence Intervals (CIs). VL was associated with an increased risk of AKI (aHR = 1.04, 95% CI: 1.01-1.08, p = 0.02) with a 4% increased hazard for each log10 VL change. Patients with a viral load in the top 50th percentile had an increased adjusted hazard of 1.27 (95% CI: 1.02-1.58, p = 0.03) for AKI as compared to those in the bottom 50th percentile.
VL is weakly but significantly associated with in-hospital AKI after adjusting for confounders. This may indicate the role of VL in COVID-19 associated AKI. This data may inform future studies to discover the mechanistic basis of COVID-19 associated AKI.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The urgency to understand the long-term neuropsychiatric sequala of COVID-19, a part of the Post-Acute COVID-19 Syndrome (PACS), is expanding as millions of infected individuals experience new ...unexplained symptoms related to mood, anxiety, insomnia, headache, pain, and more. Much research on PACS involves cross sectional surveys which limits ability to understand the dynamic trajectory of this emerging phenomenon. In this secondary analysis, we analyzed data from a 4-week observational digital phenotyping study using the mindLAMP app for 695 college students with elevated stress who specified if they were exposed to COVID-19. Students also completed a biweekly survey of clinical assessments to obtain active data. Additionally, passive data streams like GPS, accelerometer, and screen state were extracted from phone sensors and through features the group built. Three hundred and eighty-second number participants successfully specified their COVID-19 exposure and completed the biweekly survey. From active smartphone data, we found significantly higher scores for the Prodromal Questionnaire (PQ) and the Pittsburgh Sleep Quality Index (PSQI) for students reporting exposure to COVID-19 compared to those who were not (
s < 0.05). Additionally, we found significantly decreased sleep duration as captured from the smartphone via passive data for the COVID-19 exposed group (
< 0.05). No significant differences were detected for other surveys or passive sensors. Smartphones can capture both self-reported symptoms and behavioral changes related to PACS. Our results around changes in sleep highlight how digital phenotyping methods can be used in a scalable and accessible manner toward better capturing the evolving phenomena of PACS. The present study further provides a foundation for future research to implement improving digital phenotyping methods.
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Water contamination by multidrug resistant (MDR) enteric bacteria can be considered as the foremost cause of gastrointestinal infections and poses a threat to global public health. ...Therefore, there is an urgent need to pursue unorthodox techniques with potential of community scale applications for purging of water borne pathogenic bacteria. We communicate visible-light assisted photocatalytic disinfection (PCD) of an enteric MDR bacterium; Enterobacter sp. using Fe-doped ZnO nanoparticles impregnated on Kaolinite (Clay) (ZnO/K). ZnO/K was synthesized by co-precipitation technique and was found to be more effective than Fe-doped ZnO (ZnO) and Kaolinite for PCD process. Analysis from fluorescence microscopy and electron microscopy (FESEM) proposed complete bacterial cell death via PCD due to damage of bacterial cell membrane. Experimental evidences indicated that O2− could be acting as the most significant component in disinfection of MDR Enterobacter sp. in visible-light assisted PCD process in presence of ZnO/K. Considering the experimental data of Resazurin assay, it is proposed that reactive oxygen species (ROS) generated during PCD might have impeded the oxido-reductase enzyme system of the bacteria and hence trammeling its metabolic activity. Crystal structure and particle size of ZnO/K was found to be unaltered during the photocatalytic process indicating its potential for reusability. When ZnO/K was exposed to HCT-116 Human Colorectal Carcinoma cell lines, about 79% cell survivability was noticed. The synthesized material was successful in completely disinfecting the target microorganism in Zebra Fish model, without producing any adverse effects on the Fish itself, further reinforcing its biocompatibility factor. High effectiveness of PCD process using ZnO/K under visible light in disinfecting enteric MDR bacteria, might have promising outcome as an alternative water disinfection technology to prevent the spread of infectious and resistant bacteria without producing any adverse effect on non-specific flora and fauna.
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•Ag@ZnO nanocomposites are synthesized via precipitation technique.•Solar-photocatalytic disinfection of V. cholerae by using Ag@ZnO is reported.•Disinfection efficiency of Ag@ZnO is ...compared with that of ZnO and TiO2.
Disinfection of Gram-negative bacterium Vibrio cholerae 569B in aqueous matrix by solar-photocatalysis mediated by Ag@ZnO core–shell structure nanocomposite particles was investigated. Silver nanoparticles are synthesized by the reduction of silver perchlorate followed by precipitation of zinc oxide shell and are employed in the photocatalytic disinfection of the model pathogen. Effect of photocatalyst loading and reaction temperature on the disinfection kinetics was studied. Disinfection efficiency in laboratory as well as real water samples was compared with that of pure-ZnO and TiO2 (Degussa P25). Nanocomposite system has shown optimum disinfection (≈98%) at 40–60min of sun-light exposure with a catalyst loading of 0.5mg/L of the reaction solution. The reduction of aquatic bacterial densities by photocatalytically active Ag@ZnO core–shell nanocomposite in presence of natural sun-light may have potential ex situ application in water decontamination at ambient conditions.
Site-selective functionalization of unactivated C(sp3)–H centers is challenging because of the ubiquity and strength of alkyl C–H bonds. Herein, we disclose a position-selective C(sp3)–C(sp2) ...cross-coupling reaction. This process engages C(sp3)–H bonds and aryl bromides, utilizing catalytic quantities of a photoredox-capable molecule and a nickel precatalyst. Using this technology, selective C–H functionalization arises owing to a 1,6-hydrogen atom transfer (HAT) process that is guided by a pendant alcohol-anchored sulfamate ester. These transformations proceed directly from N–H bonds, in contrast to previous directed, radical-mediated, C–H arylation processes, which have relied on prior oxidation of the reactive nitrogen center in reactions with nucleophilic arenes. Moreover, these conditions promote arylation at secondary centers in good yields with excellent selectivity.
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