2,184 research outputs found
Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin
Thermochemical oxidation of methane (TOM) by high-valence metal oxides in geological systems and its potential role as a methane sink remain poorly understood. Here we present evidence of TOM induced by high-valence metal oxides in the Junggar Basin, located in northwestern China. During diagenesis, methane from deeper source strata is abiotically oxidized by high-valence Mn(Fe) oxides at 90 to 135 °C, releasing 13C-depleted CO2, soluble Mn2+ and Fe2+. Mn generally plays the dominant role compared to Fe, due to its lower Gibbs free energy increment during oxidation. Both CO2 and metal ions are then incorporated into authigenic calcites, which are characterized by extremely negative δ13C values (−70 to −22.5‰) and high Mn content (average MnO = 5 wt.%). We estimate that as much as 1224 Tg of methane could be oxidized in the study area. TOM is unfavorable for gas accumulation but may act as a major methane sink in the deep crustal carbon cycle.This study was supported by funds from the Natural Science Foundation of China to W.-X.H. (41830425, 41230312) and X.-L.W. (41573054), the Fundamental Research Funds for the Central Universities to X.-L.W. (020614380056), and the Outstanding PhD Candidate Program of Nanjing University to X.K
Core Collapse Supernova Explosions in Active Galactic Nucleus Accretion Disks
Astrophysical events that occur in active galactic nucleus (AGN) disks are
believed to differ significantly from the ordinary in the interstellar medium.
We show that stars located in the outer region of the AGN disk would explode
near the original migration starting points instead of being accreted by the
central supermassive black hole due to the effect of viscosity. AGN disks
provide a dense environment for supernova (SN) explosions, which inevitably
involve ejecta-disk interactions. In this paper, we investigate the light
curves (LCs) of core-collapse SN exploded in AGN disks. In addition to the
fundamental energy source of ---- decay reaction powering the SN LCs, the forward-reverse shock
produced during interactions may contribute significantly to the observed flux.
If the stellar winds manage to create a cavity surrounded by a shell near the
star before the SN explosion, the ejecta-winds-disk configurations are
expected. We present various SN LCs from different types of progenitors and
find that the SN LCs are dominated by the radiation of ejecta-disk
interaction-induced shocks. The resulting SNe in the AGN disk is a promising
transient source for UV and optical band detection by the Neil Gehrels Swift
Observatory (Swift), the Ultraviolet Explorer (UVEX) and wide field survey
telescopes such as Ultraviolet Transient Astronomy Satellite (ULTRASAT), Wide
Field Survey Telescope (WFST) and Legacy Survey of Space and Time (LSST) at the
Vera C. Rubin Observatory. These detections could aid in the investigation of
AGN discs and the associated high-energy transient occurrences.Comment: 16 pages, 6 figures, 2 tables, matches the published version in Ap
Design of Chiral Supramolecular Polymers Exhibiting a Negative Nonlinear Response.
Many synthetic and supramolecular chiral polymeric systems are known to exhibit the "majority rules effect" (MRE), a positive nonlinear response in which a small enantiomeric excess ( ee ) of the chiral building blocks leads to unproportionally large chiroptical signals near zero ee . In contrast, the opposite "racemate rules effect" (RRE), a negative nonlinear response in which the chiroptical signals are flat near zero ee , while giving large nonlinear chiroptical responses to ee at high values, has only been occasionally observed. The origin of this unusual ee dependence remains elusive largely because few systems have been established that exhibit this effect. Herein, we present a design approach that enables the development of chiral supramolecular polymers with a pronounced negative nonlinear response akin to RRE. This is achieved by in situ generating a bidentate inducer for supramolecular polymerization that exists in both meso - and homochiral forms upon reacting with chiral guests. The presence of the meso -inducer creates an aggregate structure that has a little response in the circular dichroism (CD) spectra as a function of ee at a particular wavelength, but a homochiral inducer gives large changes in response to ee at this wavelength. This allowed for an RRE-like response to be observed when the CD intensity of the supramolecular polymers was plotted against the ee of the chiral guests that generate the meso - and homochiral inducers without the necessity of the racemic guest preferentially being incorporated into the polymer
Atrial Natriuretic Peptide Regulates Ca2+ Channel in Early Developmental Cardiomyocytes
currents has not been investigated in developmental cardiomyocytes. by ANP was entirely abolished by erythro-9-(2-Hydroxy-3-nonyl) adenine (EHNA), a selective inhibitor of type 2 phosphodiesterase(PDE2) in most cells tested. is due to activation of particulate guanylyl cyclase (GC), cGMP production and cGMP-activation of PDE2 mediated depression of adenosine 3′, 5′–cyclic monophophate (cAMP)–cAMP-dependent protein kinase (PKA) in early cardiomyogenesis
Short-term prognostic analysis of patients with systemic lupus erythematosus co-infection and comparison of mNGS and conventional microbiological test results
ObjectivesInfection is one of the major causes of morbidity and mortality in patients with systemic lupus erythematosus (SLE), and as a new diagnostic technique, metagenomic next-generation sequencing (mNGS) is increasingly used for the pathogenetic detection of co-infected SLE patients. However, conventional microbiological testing (CMT) is still the gold standard for pathogenic diagnosis, and the specific diagnostic efficacy of mNGS versus CMT in such patients is not known. In addition, there are few studies on the short-term prognosis of co-infected SLE patients.MethodsThis study retrospectively included 58 SLE patients with co-infection admitted to the First Affiliated Hospital of Zhengzhou University from October 2020 to August 2022. Patients were divided into a survivors (n=27) and a non-survivors (n=31) according to their discharge status. Baseline characteristics and etiological data were collected and statistically analyzed for all patients during their hospitalization. The sequential organ failure assessment (SOFA) score, acute physiology and chronic health evaluation (APACHE) II and systemic lupus erythematosus disease activity index (SLEDAI) were calculated for each patient to assess the predictive ability of the 3 scores on the short-term prognosis of SLE patients. The mNGS and CMT culture results were also compared to clarify the flora characteristics of patients with SLE infection.ResultsMore patients in the non-survivors had renal impairment, neurological manifestations, multiplasmatic cavity effusion and gastrointestinal manifestations compared to the survivors (p < 0.05). The SOFA score, APACHE II and SLEDAI were significantly higher in the non-survivors than in the survivors (p < 0.01). There were also significant differences between the two groups in several tests such as hemoglobin, platelets, albumin, total bilirubin, C-reactive protein (CRP), procalcitonin (PCT), and complement C3 (p < 0.05). In addition, the absolute values of T lymphocytes, CD4+ T cells and CD8+ T cells were smaller in the non-survivors than in the survivors (p < 0.05). The most common type of infection in this study was pulmonary infection, followed by bloodstream infection. mNGS and CMT positivity rates were not significantly different among patients in the non-survivors, but were significantly different among patients in the survivors (p=0.029). In-hospital survival of patients with SLE infection could be predicted based on the SOFA score in relation to 6. For patients with SOFA <6, we recommend earlier mNGS testing to identify the pathogen and improve patient prognosis.ConclusionsFor SLE patients with co-infection, in-hospital survival can be predicted based on SOFA score. For patients with SOFA <6, advising them to complete mNGS testing as early as possible may improve the prognosis to some extent
Maskless Generation of Single Silicon Vacancy Arrays in Silicon Carbide by a Focused He+ Ion Beam
Precise generation of spin defects in solid-state systems is essential for
nanostructure fluorescence enhancement. We investigated a method for creating
single silicon vacancy defect arrays in silicon carbide using a helium-ion
microscope. Maskless and targeted generation can be realized by precisely
controlling the focused He+ ion beam with an implantation uncertainty of 60 nm.
The generated silicon vacancies were identified by measuring the optically
detected magnetic resonance spectrum and room temperature photoluminescence
spectrum. We systematically studied the effects of the implantation ion dose on
the generated silicon vacancies. After optimization, a conversion yield of ~
6.95 % and a generation rate for a single silicon vacancy of ~ 35 % were
realized. This work paves the way for the integration and engineering of color
centers to photonic structures and the application of quantum sensing based on
spin defects in silicon carbide
Soil heterogeneity in the horizontal distribution of microplastics influences productivity and species composition of plant communities
Contamination of soils by microplastics can have profound ecological impacts on terrestrial ecosystems and has received increasing attention. However, few studies have considered the impacts of soil microplastics on plant communities and none has tested the impacts of spatial heterogeneity in the horizontal distribution of microplastics in the soil on plant communities. We grew experimental plant communities in soils with either a homogeneous or a heterogeneous distribution of each of six common microplastics, i.e., polystyrene foam (EPS), polyethylene fiber (PET), polyethylene bead (HDPE), polypropylene fiber (PP), polylactic bead (PLA) and polyamide bead (PA6). The heterogeneous treatment consisted of two soil patches without microplastics and two with a higher (0.2%) concentration of microplastics, and the homogeneous treatment consisted of four patches all with a lower (0.1%) concentration of microplastics. Thus, the total amounts of microplastics in the soils were exactly the same in the two treatments. Total and root biomass of the plant communities were significantly higher in the homogeneous than in the heterogeneous treatment when the microplastic was PET and PP, smaller when it was PLA, but not different when it was EPS, HDPE or PA6. In the heterogeneous treatment, total and root biomass were significantly smaller in the patches with than without microplastics when the microplastic was EPS, but greater when the microplastic was PET or PP. Additionally, in the heterogeneous treatment, root biomass was significantly smaller in the patches with than without microplastics when the microplastic was HDPE, and shoot biomass was also significantly smaller when the microplastic was EPS or PET. The heterogeneous distribution of EPS in the soil significantly decreased community evenness, but the heterogeneous distribution of PET increased it. We conclude that soil heterogeneity in the horizontal distribution of microplastics can influence productivity and species composition of plant communities, but such an effect varies depending on microplastic chemical composition (types) and morphology (shapes)
Small Angle X-Ray and Neutron Scattering - Its Application to Supramolecular Solutions
Contains reports on seven research projects.Argonne National LaboratoryU.S. Department of Energy DE-FG01-90ER45429National Science FoundationUniversity of Florence, ItalyExxon FellowshipNational Science Foundation Grant INT 87-508
Survey and Visual Detection of Zaire ebolavirus in Clinical Samples Targeting the Nucleoprotein Gene in Sierra Leone
Ebola virus (EBOV) can lead to severe hemorrhagic fever with a high risk of death in humans and other primates. To guide treatment and prevent spread of the viral infection, a rapid and sensitive detection method is required for clinical samples. Here, we described and evaluated a reverse transcription loop-mediated isothermal amplification (RT-LAMP) method to detect Zaire ebolavirus using the nucleoprotein gene (NP) as a target sequence. Two different techniques were used, a calcein/Mn2+ complex chromogenic method and real-time turbidity monitoring. The RT-LAMP assay detected the NP target sequence with a limit of 4.56 copies/μL within 45 min under 61°C, a similar even or increase in sensitivity than that of real-time reverse transcription-polymerase chain reaction (RT-PCR). Additionally, all pseudoviral particles or non- Zaire EBOV genomes were negative for LAMP detection, indicating that the assay was highly specific for EBOV. To appraise the availability of the RT-LAMP method for use in clinical diagnosis of EBOV, of 417 blood or swab samples collected from patients with clinically suspected infections in Sierra Leone, 307 were identified for RT-LAMP-based surveillance of EBOV. Therefore, the highly specific and sensitive RT-LAMP method allows the rapid detection of EBOV, and is a suitable tool for clinical screening, diagnosis, and primary quarantine purposes
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