An extended guided crowd dynamics model is proposed to investigate the guide optimization during emergency evacuation. The initial assignment scheme for guides based on clustering algorithm, taking ...the numbers of both informed and uninformed pedestrians into consideration, is studied. The guide choice method for informed followers based on an exponent model, considering the distance to the guide and the follower quantity, is further investigated. On the basis of the modeling method of this paper, evacuation behavior dynamics under guides is explored, from which the leading role of guides can be clearly observed. The effects of guide quantity, parameter in the guide choice method and the size of visual field on evacuations are analyzed. Simulation results indicate that the evacuation efficiency gradually increases with the increase of guide quantity until it reaches a certain level, and the optimal number of guides is closely related to the initial distribution of pedestrians. The combination of density factor and distance factor with a reasonable proportion when determining which guide is very necessary. Pedestrians have stronger evacuation ability within a certain period of time when continuously increasing their visual radii. The study can provide theoretical suggestions for guiding pedestrian evacuation under emergencies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Graphene oxide/chitosan/silica fibers were prepared by a wet spinning technique.•Porous fibers were produced through wet-chemical etching off silica nanoparticles.•The maximum adsorption capacity of ...the porous fibers can reach 294.12mg/g.•The adsorption process was characterized by kinetics and isotherm analysis.
Graphene oxide/chitosan/silica fibers were prepared by a wet spinning technique. Silica nanoparticles were etched off from the graphene oxide/chitosan/silica fibers to produce graphene oxide/chitosan fibers with porous structure. The morphology and functional groups of the porous graphene oxide/chitosan fibers were characterized using scanning electron microscopy and Fourier-transform infrared spectroscopy, respectively. Adsorption experiments with the porous graphene oxide/chitosan fibers were performed based on various parameters, such as initial congo red concentration, solution pH, adsorbent dose and contact time. The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models were employed to discuss the adsorption behavior. The results indicated that the equilibrium data were perfectly represented by the Langmuir isotherm. The maximum adsorption capacity reached 294.12mg/g. The kinetics data were analyzed using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models and the pseudo-first-order model best described the adsorption of congo red onto the porous graphene oxide/chitosan fibers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Infrared spectroscopy, especially for molecular vibrations in the fingerprint region between 600 and 1,500 cm(-1), is a powerful characterization method for bulk materials. However, molecular ...fingerprinting at the nanoscale level still remains a significant challenge, due to weak light-matter interaction between micron-wavelengthed infrared light and nano-sized molecules. Here we demonstrate molecular fingerprinting at the nanoscale level using our specially designed graphene plasmonic structure on CaF2 nanofilm. This structure not only avoids the plasmon-phonon hybridization, but also provides in situ electrically-tunable graphene plasmon covering the entire molecular fingerprint region, which was previously unattainable. In addition, undisturbed and highly confined graphene plasmon offers simultaneous detection of in-plane and out-of-plane vibrational modes with ultrahigh detection sensitivity down to the sub-monolayer level, significantly pushing the current detection limit of far-field mid-infrared spectroscopies. Our results provide a platform, fulfilling the long-awaited expectation of high sensitivity and selectivity far-field fingerprint detection of nano-scale molecules for numerous applications.
BACKGROUND AND PURPOSE—Intracerebral hemorrhage (ICH) is a devastating disease without effective treatment. As a key component of the innate immune system, the NOD-like receptor (NLR) family, NLRP3 ...(pyrin domain–containing protein 3) inflammasome, when activated after ICH, promotes neuroinflammation and brain edema. MCC950 is a potent, selective, small-molecule NLRP3 inhibitor that blocks NLRP3 activation at nanomolar concentrations. Here, we examined the effect of MCC950 on brain injury and inflammation in 2 models of ICH in mice.
METHODS—In mice with ICH induced by injection of autologous blood or bacterial collagenase, we determined the therapeutic potential of MCC950 and its mechanisms of neuroprotection.
RESULTS—MCC950 reduced IL-1β (interleukin-1β) production and attenuated neurodeficits and perihematomal brain edema after ICH induction by injection of either autologous blood or collagenase. In mice with autologous blood-induced ICH, the protection of MCC950 was associated with reduced leukocyte infiltration into the brain and microglial production of IL-6. MCC950 improved blood–brain barrier integrity and diminished cell death. Notably, the protective effect of MCC950 was abolished in mice depleted of either microglia or Gr-1 myeloid cells.
CONCLUSIONS—These results indicate that the NLRP3 inflammasome inhibitor, MCC950, attenuates brain injury and inflammation after ICH. Hence, NLRP3 inflammasome inhibition is a potential therapy for ICH that warrants further investigation.Stroke is published on behalf of the American Heart Association, Inc., by Wolters Kluwer Health, Inc. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial-NoDerivs License, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited, the use is noncommercial, and no modifications or adaptations are made.
A novel direct Z-scheme Bi2O3/Bi2MoO6 nanocomposite was successfully obtained via simple alkali treatment of Bi2MoO6 succeeded by air calcination approach, which exhibited excellent ...visible-light-driven photocatalytic degradation of phenol and hydrogen evolution reaction due to the direct Z-scheme charge transfer mechanism. This Z-scheme system not only greatly promoting the efficient separation of photogenerated electron-hole pairs, but also preserves strong and continuous redox ability, resulting in the very high photocatalytic performance.
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•Novel direct Z-scheme Bi2O3/Bi2MoO6 composites was successfully obtained.•The composites exhibited excellent photocatalytic degradation of phenol and hydrogen evolution reaction.•Direct Z-scheme photocatalytic mechanism used to explain activity enhancement.•O2−, h+ and OH as the major reactive species in the forming Z-scheme system.•Oxygen vacancy serves as electron mediator to promote the separation of photogenerated electron-hole pairs.
Semiconductor based photocatalytic technology has attracted substantial research attention based on its potential to overcome environmental and energy crisis. The conventional photocatalysts with their issues such as rapid charge recombination are considered unfavorable candidates for practical applications. Herein, a novel direct Z-scheme based photocatalyst composed of Bi2O3/Bi2MoO6 hetrojunction is proposed for efficient photo-degradation of phenol and hydrogen (H2) production reaction. The hetrojunction comprises of ultra-thin (2D) Bi2O3 nanosheets, in-situ grown over 3D Bi2MoO6 microspheres via simple alkali treatment of Bi2MoO6 succeeded by air calcination step. The relative mass ratio of Bi2O3 and Bi2MoO6 could be fine-tuned by controlling the alkali dosage (i.e. NaOH or KOH). Unlike the conventional Bi2O3/Bi2MoO6 hetrojunction, the proposed catalyst follow a direct Z-scheme charge transfer mechanism which permits superior photocatalytic activity with 96.4% phenol degradation efficiency and high hydrogen evolution rate of 52 μmol·g−1 under visible light irradiation. The exuberant performance is accredited to the spatially separated redox charge carriers, excellent light harvesting capability and fast-charge transportation characteristics of the proposed photocatalyst. The present work serves as a primary pathway to design and develop efficient Bi2MoO6-based direct Z-scheme photocatalysts with promising applications in environmental remediation and solar fuel production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
An optimal single-photon source should deterministically deliver one, and only one, photon at a time, with no trade-off between the source’s efficiency and the photon indistinguishability. However, ...all reported solid-state sources of indistinguishable single photons had to rely on polarization filtering, which reduced the efficiency by 50%, fundamentally limiting the scaling of photonic quantum technologies. Here, we overcome this long-standing challenge by coherently driving quantum dots deterministically coupled to polarization-selective Purcell microcavities. We present two examples: narrowband, elliptical micropillars and broadband, elliptical Bragg gratings. A polarization-orthogonal excitation–collection scheme is designed to minimize the polarization filtering loss under resonant excitation. We demonstrate a polarized single-photon efficiency of 0.60 ± 0.02 (0.56 ± 0.02), a single-photon purity of 0.975 ± 0.005 (0.991 ± 0.003) and an indistinguishability of 0.975 ± 0.006 (0.951 ± 0.005) for the micropillar (Bragg grating) device. Our work provides promising solutions for truly optimal single-photon sources combining near-unity indistinguishability and near-unity system efficiency simultaneously.
Identification of gas molecules plays a key role a wide range of applications extending from healthcare to security. However, the most widely used gas nano-sensors are based on electrical approaches ...or refractive index sensing, which typically are unable to identify molecular species. Here, we report label-free identification of gas molecules SO
, NO
, N
O, and NO by detecting their rotational-vibrational modes using graphene plasmon. The detected signal corresponds to a gas molecule layer adsorbed on the graphene surface with a concentration of 800 zeptomole per μm
, which is made possible by the strong field confinement of graphene plasmons and high physisorption of gas molecules on the graphene nanoribbons. We further demonstrate a fast response time (<1 min) of our devices, which enables real-time monitoring of gaseous chemical reactions. The demonstration and understanding of gas molecule identification using graphene plasmonic nanostructures open the door to various emerging applications, including in-breath diagnostics and monitoring of volatile organic compounds.
An outstanding goal in quantum optics and scalable photonic quantum technology is to develop a source that each time emits one and only one entangled photon pair with simultaneously high entanglement ...fidelity, extraction efficiency, and photon indistinguishability. By coherent two-photon excitation of a single InGaAs quantum dot coupled to a circular Bragg grating bull's-eye cavity with a broadband high Purcell factor of up to 11.3, we generate entangled photon pairs with a state fidelity of 0.90(1), pair generation rate of 0.59(1), pair extraction efficiency of 0.62(6), and photon indistinguishability of 0.90(1) simultaneously. Our work will open up many applications in high-efficiency multiphoton experiments and solid-state quantum repeaters.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
Plasmonic Fano metamaterials provide a unique platform for optical sensing applications due to their sharp spectral response and the ability to confine light to nanoscale regions that make them a ...strong prospect for refractive-index sensing. Higher order Fano resonance modes in noble metal plasmonic structures can further improve the sensitivity, but their applications are heavily limited by crosstalk between different modes due to the large damping rates and broadband spectral responses of the metal plasmon modes. Here, we create pure higher order Fano modes by designing asymmetric metamaterials comprised of a split-ring resonator and disk with a low-loss graphene plasmon. These higher order modes are highly sensitive to the nanoscale analyte (8 nm thick) both in refractive-index and in infrared vibrational fingerprint sensing, as demonstrated by the numerical calculation. The frequency sensitivity and figure-of-merit of the hexacontatetrapolar mode can reach 289 cm
per RIU and 29, respectively, and it can probe the weak infrared vibrational modes of the analyte with more than 400 times enhancement. The enhanced sensitivity and tunability of higher order Fano graphene metamaterials promise a high-performance nanoscale optical sensor.
Despite being a major cyanide species in the process water, it is unclear how iron cyanide influences pyritic gold ore flotation as well as how lead ions influence pyritic gold ore flotation in the ...presence of iron cyanide. This study aims at revealing the interaction of Fe(CN)63− and lead ions in pyrite flotation to investigate the strong depressing effect of Fe(CN)63− on pyritic gold ore flotation and the significant activating effect of lead ions on pyritic gold ore flotation in the presence of Fe(CN)63− using flotation, zeta potential measurement and surface analysis methods. The flotation results showed that upon 5 × 10−5 mol/L Fe(CN)63− addition, pyrite recovery drastically decreased from about 51.3% to 8.6%, while the subsequent addition of 9.5 × 10−4 mol/L lead ions significantly activated pyrite with the recovery increasing from 8.6% to 91%, which demonstrated that Fe(CN)63− strongly depressed pyrite flotation, while lead ions completely activated pyrite in the presence of Fe(CN)63−. Zeta potential measurement, surface analysis using Cryogenic X-ray photoelectron spectroscopy (Cryo-XPS) and electrochemical impedance spectroscopy (EIS) revealed that Fe(CN)63− depression was attributed to the chemical adsorption of Fe(CN)63− on iron sites of pyrite as Prussian Blue (FeFe(CN)6); however, this hydrophilic layer could be covered totally by lead ions which adsorbed on as lead hydroxide/oxide through electrostatic interactions, which resulted in the significant activation effect of lead ions. The results from this study will lead to improved flotation of gold associated with pyrite in gold flotation plants.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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