113 research outputs found
Modulating the Verwey Transition of Epitaxial Magnetite Thin Films by Ionic Gating
Understanding the Verwey transition in magnetite (Fe3O4), a strongly correlated magnetic oxide, is a one-century-old topic that recaptures great attention because of the recent spectroscopy studies revealing its orbital details. Here, the modulation of the Verwey transition by tuning the orbital configurations with ionic gating is reported. In epitaxial magnetite thin films, the insulating Verwey state can be tuned continuously to be metallic showing that the low-temperature trimeron states can be controllably metalized by both the gate-induced oxygen vacancies and proton doping. The ionic gating can also reverse the sign of the anomalous Hall coefficient, indicating that the metallization is associated with the presence of a new type of carrier with competing spin. The variable spin orientation associated with the sign reversal is originated from the structural distortions driven by the gate-induced oxygen vacancies
Current status and progress in research on dressing management for diabetic foot ulcer
Diabetic foot ulcer (DFU) is a major complication of diabetes and is associated with a high risk of lower limb amputation and mortality. During their lifetime, 19%–34% of patients with diabetes can develop DFU. It is estimated that 61% of DFU become infected and 15% of those with DFU require amputation. Furthermore, developing a DFU increases the risk of mortality by 50%–68% at 5 years, higher than some cancers. Current standard management of DFU includes surgical debridement, the use of topical dressings and wound decompression, vascular assessment, and glycemic control. Among these methods, local treatment with dressings builds a protective physical barrier, maintains a moist environment, and drains the exudate from DFU wounds. This review summarizes the development, pathophysiology, and healing mechanisms of DFU. The latest research progress and the main application of dressings in laboratory and clinical stage are also summarized. The dressings discussed in this review include traditional dressings (gauze, oil yarn, traditional Chinese medicine, and others), basic dressings (hydrogel, hydrocolloid, sponge, foam, film agents, and others), bacteriostatic dressings, composite dressings (collagen, nanomaterials, chitosan dressings, and others), bioactive dressings (scaffold dressings with stem cells, decellularized wound matrix, autologous platelet enrichment plasma, and others), and dressings that use modern technology (3D bioprinting, photothermal effects, bioelectric dressings, microneedle dressings, smart bandages, orthopedic prosthetics and regenerative medicine). The dressing management challenges and limitations are also summarized. The purpose of this review is to help readers understand the pathogenesis and healing mechanism of DFU, help physicians select dressings correctly, provide an updated overview of the potential of biomaterials and devices and their application in DFU management, and provide ideas for further exploration and development of dressings. Proper use of dressings can promote DFU healing, reduce the cost of treating DFU, and reduce patient pain
Epidemiological and genomic analyses of human isolates of Streptococcus suis between 2005 and 2021 in Shenzhen, China
Streptococcus suis (S. suis) is an important food-borne zoonotic pathogen that causes swine streptococcosis, which threatens human health and brings economic loss to the swine industry. Three-quarters of human S. suis infections are caused by serotype 2. A retrospective analysis of human S. suis cases in Shenzhen, a megacity in China, with high pork consumption, between 2005 and 2021 was conducted to understand its genomic epidemiology, pathogen virulence, and drug resistance characteristics. The epidemiological investigation showed that human cases of S. suis in Shenzhen were mainly associated with people who had been in close contact with raw pork or other swine products. Whole-genome sequence analysis showed that 33 human isolates in Shenzhen were dominated by serotype 2 (75.76%), followed by serotype 14 (24.24%), and the most prevalent sequence types (STs) were ST7 (48.48%) and ST1 (39.40%). ST242 (9.09%) and ST25 (3.03%), which were rarely reported, were also found. Phylogenetic analysis showed that the Shenzhen human isolates had close genetic relatedness to isolates from Guangxi (China), Sichuan (China), and Vietnam. We found a new 82 KB pathogenicity island (PAI) in the serotype 2 isolate that may play a role in sepsis. Similarly, a serotype 14 isolate, containing 78 KB PAI, was isolated from a patient presenting with streptococcal toxic shock syndrome (STSLS) who subsequently died. Multi-drug resistance (MDR) was high in human isolates of S. suis from Shenzhen. Most human isolates were resistant to tetracycline, streptomycin, erythromycin, and clindamycin, and 13 isolates had intermediate resistance to penicillin. In conclusion, swine importation from Guangxi, Sichuan, and Vietnam should be more closely monitored, and the use of antibiotics limited to reduce the potential for antimicrobial resistance (AMR)
Real-time Monitoring for the Next Core-Collapse Supernova in JUNO
Core-collapse supernova (CCSN) is one of the most energetic astrophysical
events in the Universe. The early and prompt detection of neutrinos before
(pre-SN) and during the SN burst is a unique opportunity to realize the
multi-messenger observation of the CCSN events. In this work, we describe the
monitoring concept and present the sensitivity of the system to the pre-SN and
SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is
a 20 kton liquid scintillator detector under construction in South China. The
real-time monitoring system is designed with both the prompt monitors on the
electronic board and online monitors at the data acquisition stage, in order to
ensure both the alert speed and alert coverage of progenitor stars. By assuming
a false alert rate of 1 per year, this monitoring system can be sensitive to
the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos
up to about 370 (360) kpc for a progenitor mass of 30 for the case
of normal (inverted) mass ordering. The pointing ability of the CCSN is
evaluated by using the accumulated event anisotropy of the inverse beta decay
interactions from pre-SN or SN neutrinos, which, along with the early alert,
can play important roles for the followup multi-messenger observations of the
next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure
Potential of Core-Collapse Supernova Neutrino Detection at JUNO
JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve
Detection of the Diffuse Supernova Neutrino Background with JUNO
As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO
Calculation of Radioactivity and Dose Rate of Activated Corrosion Products in Water-Cooled Fusion Reactor
In water-cooled reactor, the dominant radioactive source term under normal operation is activated corrosion products (ACPs), which have an important impact on reactor inspection and maintenance. A three-node transport model of ACPs was introduced into the new version of ACPs source term code CATE in this paper, which makes CATE capable of theoretically simulating the variation and the distribution of ACPs in a water-cooled reactor and suitable for more operating conditions. For code testing, MIT PWR coolant chemistry loop was simulated, and the calculation results from CATE are close to the experimental results from MIT, which means CATE is available and credible on ACPs analysis of water-cooled reactor. Then ACPs in the blanket cooling loop of water-cooled fusion reactor ITER under construction were analyzed using CATE and the results showed that the major contributors are the short-life nuclides, especially Mn-56. At last a point kernel integration code ARShield was coupled with CATE, and the dose rate around ITER blanket cooling loop was calculated. Results showed that after shutting down the reactor only for 8 days, the dose rate decreased nearly one order of magnitude, which was caused by the rapid decay of the short-life ACPs
Synthesis of reusable NH2-MIL-125(Ti)@polymer monolith as efficient adsorbents for dyes wastewater remediation
NH2-MIL-125(Ti) is a Ti-MOFs (MOFs: metal-organic frameworks) with high adsorption properties and is therefore widely used for wastewater purification. However, the powdered MOF material suffers from the disadvantages of being difficult to separate and being potentially wasted due to easy agglomeration, which limits its application in practical applications. Here, a mesoporous Ti-MOF/polymer (PEG, PVA, and PAM) monolithic material was prepared by freeze casting in liquid nitrogen (−196 °C) as an adsorbent for wastewater remediation. The composites could be easily picked up with tweezers and used for recovery tests. Characterization results such as XRD, BET, FT-IR, and SEM proved the successful synthesis of Ti-MOF/polymer. Adsorption tests using 100 mg/L methylene blue (MB) simulated wastewater showed that the Ti-MOF/PEG monolithic material had the best adsorption capacity. The order of adsorption was Ti-MOF@PEG10 (747.4 mg/g) > Ti-MOF@PVA10 (687.4 mg/g) > Ti-MOF@PAM10 (633.7 mg/g) > NH2-MIL-125(Ti) (571.4 mg/g). The effects of polymer dosage, different pollutants (methylene blue, methyl orange, indigo, actual textile wastewater), pH, anions, and cations on the adsorption effect of Ti-MOF/polymer were also investigated. It was demonstrated that all the above pollutants were well adsorbed by this Ti-MOF/polymer in the pH range 3–9. The adsorption isotherms and kinetic data are fully consistent with the Langmuir and pseudo-secondary models. This suggests that the adsorption between the pollutant and the adsorbent is a chemical interaction. Thermodynamic studies indicate that the adsorption process is exothermic and spontaneous. This work provides the potential methods to fabricate Ti-MOF/polymer monolith to avoid the pollution from powdery adsorbents that could be practical applications
Kinetic Modeling of the Extraction–Oxidation Coupling Process for the Removal of Dibenzothiophene
Extraction–oxidation
desulfurization (EODS) technology would be a potential industrial
application for achieving ultralow-sulfur fuel oils. A combined extraction–oxidation
system for dibenzothiophene removal from model fuel with H<sub>2</sub>O<sub>2</sub> as an oxidant, acetonitrile as an extractant, and Mo/γ-Al<sub>2</sub>O<sub>3</sub> as a catalyst was performed in a batch reactor.
To study this complex heterogeneous system, the chemical reaction
and mass transfer on each phase were individually assessed. Kinetics
of the EODS system for dibenzothiophene in model fuel was developed,
comprising the chemical kinetic mechanism and mass transfer effects.
The kinetic parameters of the kinetic model, such as the kinetic constants
and apparent activation energy, were determined. The EODS system in
the experimental condition is determined by both the extraction process
and catalytic oxidation reaction, because the terms involving the
intrinsic resistance of the chemical reaction are no more important
than mass transfer resistance
Combined Extraction–Oxidation System for Oxidative Desulfurization (ODS) of a Model Fuel
An
efficient extraction–oxidation catalytic system for deep
desulfurization of a model fuel was explored. First, Mo/γ-Al<sub>2</sub>O<sub>3</sub> catalysts were prepared using an impregnation
method and were characterized using X-ray diffraction, temperature-programmed
reduction, and N<sub>2</sub> physical adsorption isotherms. Acetonitrile,
methanol, <i>N</i>,<i>N</i>-dimethylformamide, <i>N</i>-methylpyrrolidone, and H<sub>2</sub>O were added to investigate
the influences of different extracting agents for extraction–oxidation
desulfurization. Acetonitrile showed synergistic action for dibenzothiophene
oxidation and a comparatively low dissolving capacity for aromatic
compounds. Under a <i>n</i>(H<sub>2</sub>O<sub>2</sub>)/<i>n</i>(S) molar ratio of 2.3 and <i>v</i>(oil)/<i>v</i>(acetonitrile) of 3:1, benzothiophene, dibenzothiophene,
and 4,6-dimethyldibenzothiophene were almost completely removed in
the presence of the 16 wt % Mo/γ-Al<sub>2</sub>O<sub>3</sub> catalyst over 40 min at 333 K. A reaction pathway based on extraction–oxidation
was proposed in which the sulfur compounds were transferred to the
extracting phase before oxidizing to form sulfones in the extracting
phase. The extraction process was rapid relative to the oxidation
process. The advantages of the extraction–oxidation catalytic
system are that a high sulfur removal can be achieved under a lower <i>n</i>(H<sub>2</sub>O<sub>2</sub>)/<i>n</i>(S) molar
ratio and that the stability of the catalyst is significantly improved
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