Atomic-scale visualization of the interlayer Rydberg exciton complex in moiré heterostructures.

Excitonic systems, facilitated by optical pumping, electrostatic gating or magnetic field, sustain composite particles with fascinating physics. Although various intriguing excitonic phases have been revealed via global measurements, the atomic-scale accessibility towards excitons has yet to be established. Here, we realize the ground-state interlayer exciton complexes through the intrinsic charge transfer in monolayer YbCl3/graphite heterostructure. Combining scanning tunneling microscope and theoretical calculations, the excitonic in-gap states are directly profiled. The out-of-plane excitonic charge clouds exhibit oscillating Rydberg nodal structure, while their in-plane arrangements are determined by moiré periodicity. Exploiting the tunneling probe to reflect the shape of charge clouds, we reveal the principal quantum number hierarchy of Rydberg series, which points to an excitonic energy-level configuration with unusually large binding energy. Our results demonstrate the feasibility of mapping out the charge clouds of excitons microscopically and pave a brand-new way to directly investigate the nanoscale order of exotic correlated phases.

One-pot solvothermal preparation of the porous NiS2//MoS2 composite catalyst with enhanced low-temperature hydrodesulfurization activity.

The simple preparation of mesoporous NiS2//MoS2 composite catalyst through a one-pot solvothermal method is presented. The improvement of the specific surface area (220 m2/g) and the construction of the porous structure are realized by this method in the case of no support. The organics acts as a microscopic binder contribute to uniform stacking of MoS2 with NiS2 clusters. The composite structure including NiS2 and MoS2 was obtained (proved by XRD, XPS, TEM, IR, UV-vis and RAMAN) and changed the microelectronic environment of the active metal surface (DFT calculation). The mesoporous NiS2//MoS2 catalyst (Ni1Mo1-200) showed an excellent hydrodesulfurization performance of dibenzothiophene (DBT conversion: 78 % at 260 °C) and a high ratio of direct desulfurization pathway (SDDS/HYD = 16.6) at a low reaction temperature. By combining the characterization and theoretical calculation results, the advantages of this NiS2//MoS2 composite structure in synergistic catalysis was further confirmed.

Mechanically induced photons from ultraviolet-C to near-infrared in Tm3+-doped MgF2.

Mechanoluminescence (ML) plays a vital role in various fields, and has gained increasing popularity over the past two decades. The widely studied materials that are capable of generating ML can be classified into two groups, self-powered and trap-controlled. Here, we demonstrate that both self-powered ML and trap-controlled ML can be achieved simultaneously in MgF2:Tm3+. Upon stimulation of external force, the 1I6→3H6 and 3H4→3H6 transitions of Tm3+ are observed, ranging from the ultraviolet-C to near-infrared. After exposure to X-rays, MgF2:Tm3+ presents a stronger ML than the uncharged sample. After cleaning up at high temperatures, the ML returns to the initial level, which is a typical characteristic of trap-controlled ML. In the end, we demonstrate the potential applications of MgF2:Tm3+ in dynamic anti-counterfeiting, and structure inspection.

Rational Design of Highly Efficient PdIn-In2O3 Interfaces by a Capture-Alloying Strategy for Benzyl Alcohol Partial Oxidation.

Well-dispersed PdIn bimetallic alloy nanoparticles (1-4 nm) were immobilized on mesostructured silica by an in situ capture-alloying strategy, and PdIn-In2O3 interfaces were rationally constructed by changing the In2O3 loading and reduction temperature. The catalytic performance for benzyl alcohol partial oxidation was evaluated, and a catalytic synergy was observed. The Pd-rich PdIn-In2O3 interface is prone to be formed on the catalyst with a low In2O3 loading after being reduced at 300 °C. It was demonstrated that the Pd-rich PdIn-In2O3 interface was more active for benzyl alcohol partial oxidation than In-rich Pd2In3 species, which was likely to be formed at a high reduction temperature (400 °C). The high catalytic activity on the Pd-rich PdIn-In2O3 interface was attributed to the exposure of more Pd-enriched active sites, and an optimized PdIn-In2O3/Pd assemble ratio enhanced the oxygen transfer during partial oxidation. The density functional theory (DFT) calculation confirmed that the Pd-rich Pd3In1(111)-In2O3 interface facilitated the activation of oxygen molecules, resulting in high catalytic activity.

Nyquist Sampling Conditions of Some Diffraction Algorithms with Adjustable Magnification.

Diffraction algorithms with adjustable magnification are dominant in holographic projection and imaging. However, the algorithms are limited by the Nyquist sampling conditions, and simulation results with inappropriate parameters sometimes appear with aliasing. At present, many diffraction algorithms have been proposed and improved, but there is a need for an overall analysis of their sampling conditions. In this paper, some classical diffraction algorithms with adjustable magnification are summarized, and their sampling conditions in the case of plane wave or spherical wave illumination are analyzed and compared, which helps to select the appropriate diffraction algorithm according to the specific parameter conditions of the simulation to avoid aliasing.

Persistent visible luminescence of SrF2:Pr3+ for ratiometric thermometry.

Luminescence-based thermometry, especially the ratiometric temperature sensing technology, has attracted considerable attention recently due to its characteristics such as non-contact operating mode and strong capacity of resisting disturbance. Differing from the conventional strategy that usually needs continuous excitation, here an optical thermometry, which we have named the persistent luminescence intensity ratio (PLIR) thermometry, is proposed. The PLIR thermometry relies on the optical material SrF2:Pr3+ that could emit luminescence for several hours and even longer after being charged by X-ray. It has been demonstrated that the PLIR is sensitive to the variation of temperature and complies with the Boltzmann distribution. More importantly, the reliability of the proposed PLIR thermometry is verified. Our work may inspire others to develop more persistent luminescence thermometry.

In-fiber Michelson interferometric sensor fabricated by single CO2 laser pulse.

An in-fiber Michelson interferometric sensor was presented by fabricating a concavity on the end face of a single mode fiber using a single CO2 laser pulse. Reflected beams from the bottom and air-cladding boundary of the concavity are coupled into the fiber core and superimpose to generate a two-beam in-fiber Michelson interferometer. Compared with other laser-machining methods where multiple scanning cycles with precise manipulation are needed, the proposed method is more straightforward because only a single laser pulse is used to construct the sensor. The concavity constructed by the CO2 laser is very smooth, and its shape could be controlled flexibly by changing the position of the single mode fiber and the parameters of the CO2 laser pulse, so the fringe visibilities of the proposed sensors could be more than 15 dB, which is higher than that of the most reported laser-machining in-fiber Michelson interferometers. The proposed sensor was demonstrated by measuring the temperature with a sensitivity of 11.13 pm/°C. Furthermore, the proposed device is compact (<100 µm), economical, and robust. These advantages make it a promising candidate in practical applications.

Visible-to-ultraviolet-C upconverted photon for multifunction via Ca2SiO4:Pr3.

The ultraviolet C (UVC) photon plays a key role in a broad spectrum of fields. With the implementation of the Minamata Convention, searching for a new way to achieve UVC light is highly desired. Here we develop a material of Ca2SiO4:Pr3+ that can emit UVC light upon excitation of a 450-nm laser or even a very cheap 450-nm LED, a fact confirmed by using a solar blind camera to capture UVC emission from Ca2SiO4:Pr3+. In addition, smart anti-counterfeiting and inactivation of Bacillus subtilis applications using Ca2SiO4:Pr3+ are also confirmed.

Direct observation of the Mottness and p-d orbital hybridization in the epitaxial monolayer α-RuCl3.

α-RuCl3, a promising material to accomplish the Kitaev honeycomb model, has attracted enormous interest recently. Mottness and p-d bonds play vital roles in generating Kitaev interactions and underpinning the potential exotic states of quantum magnets, and the van der Waals monolayer is considered to be a better platform to approach a two-dimensional Kitaev model than the bulk. Here, we worked out the growth art of an α-RuCl3 monolayer on a graphite substrate and studied its electronic structure, particularly the delicate orbital occupations, through scanning tunneling microscopy and spectroscopy. An in-plane lattice expansion of 2.67 ± 0.83% is observed and the pronounced t2g-pπ and eg-pσ hybridization are visualized. The Mott nature is unveiled by an ∼0.6 eV full gap at the Fermi level located inside the t2g-pπ manifold which is further verified by the density functional theory calculations. The monolayer phase of α-RuCl3 fulfills the a priori criteria of recent theoretical predictions of tuning the relevant properties in this material and provides a novel platform to explore the Kitaev physics.

Proteomics Insights into the Gene Network of cis9, trans11-Conjugated Linoleic Acid Biosynthesis in Bovine Mammary Gland Epithelial Cells.

The objective of the study was to elucidate the stearoyl-coenzyme A desaturase (SCD1)-dependent gene network of c9, t11-CLA biosynthesis in MAC-T cells from an energy metabolism perspective. The cells were divided into the CAY group (firstly incubated with CAY10566, a chemical inhibitor of SCD1, then incubated with trans-11-octadecenoic acid, (TVA)), the TVA group (only TVA), and the control group (without CAY, TVA). The c9, t11-CLA, and TVA contents were determined by gas chromatography. The mRNA levels of SCD1 and candidate genes were analyzed via real-time PCR. Tandem mass tag (TMT)-based quantitative proteomics, bioinformatic analysis, parallel reaction monitoring (PRM), and small RNA interference were used to explore genes involved in the SCD1-dependent c9, t11-CLA biosynthesis. The results showed that the SCD1 deficiency led by CAY10566 blocked the biosynthesis of c9, t11-CLA. In total, 60 SCD1-related proteins mainly involved in energy metabolism pathways were primarily screened by TMT-based quantitative proteomics analysis. Moreover, 17 proteins were validated using PRM analysis. Then, 11 genes were verified to have negative relationships with SCD1 after the small RNA interference analysis. Based on the above results, we concluded that genes involved in energy metabolism pathways have an impact on the SCD1-dependent molecular mechanism of c9, t11-CLA biosynthesis.

Boltzmann-distribution-dominated persistent luminescence ratiometric thermometry in NaYF4:Pr3.

A novel, to the best of our knowledge, optical temperature measurement method is proposed, i.e., persistent luminescence intensity ratio (PLIR) thermometry. The PLIR thermometry relies on the micro-sized NaYF4:Pr3+ material that can emit persistent luminescence (PersL) uninterruptedly after being charged by x ray irradiation. The 3P1→3H5 and 3P0→3H5 PersL transitions, locating separately at ∼ 522 and 538 nm, have been confirmed to follow the Boltzmann distribution. The emitting intensity ratio of this pair of PersL lines is thus found to be a good indicator of the variation of temperature. Our work is expected to enrich the optical temperature sensing family.

Compatibility between Activity and Selectivity in Catalytic Oxidation of Benzyl Alcohol with Au-Pd Nanoparticles through Redox Switching of SnOx.

A balance between catalytic activity and product selectivity remains a dilemma for the partial oxidation processes because the products are prone to be overoxidized. In this work, we report on the partial oxidation of benzyl alcohol using a modified catalyst consisting of nanosized Au-Pd particles (NPs) with tin oxide (SnOx) deposited on a mesoporous silica support. We found that the SnOx promotes the autogenous reduction of PdO to active Pd0 species on the Au-Pd NP catalyst (SnOx@AP-ox) before H2 reduction, which is due to the high oxophilicity of Sn. The presence of active Pd0 species and the enhancement of oxygen transfer by SnOx led to high catalytic activity. The benzaldehyde selectivity was enhanced with the increase of SnOx content on catalyst SnOx@AP-ox, which is ascribed to the modulated affinity of reactants and products on the catalyst surface through the redox switching of Sn species. After H2 reduction, SnOx was partially reduced and Au-Pd-Sn alloy was formed. The formation of Au-Pd-Sn alloy weakened both the catalytic synergy of Au-Pd alloy NPs and the adsorption of benzyl alcohol on the reduced catalyst, thus leading to low catalytic activity.

Prediction of air traffic delays: An agent-based model introducing refined parameter estimation methods.

We propose an agent-based model for predicting individual flight delays in an entire air traffic network. In contrast to previous work, more detailed parameter estimation methods were incorporated into the agent-based model, acting on the state transitions of agents. Specifically, a conditional probability model was proposed for modifying the expected departure time, which was used to indicate whether a flight had experienced the necessary waiting due to Ground Delay Programs (GDPs) or carrier-related reasons. Additionally, two random forest regression models were presented for estimating the turnaround time and the elapsed time of flight agents in the agent-based delay prediction model. The parameter models were trained and fitted using the flight data for 2017 in the United States. The performance of the delay prediction model was tested for thirty days with three types of delay levels (low, medium, and high), which were randomly selected from 2018. The experimental results showed that the average absolute error in the test days was 6.8 min, and the classification accuracy with a 15 min threshold for a two-hour forecast horizon was 89.5%. The performance of our model outperformed that of existing research. Additionally, the positive effect of introducing parameter models and the negative impact of increasing the prediction horizon on the prediction performance were further studied.

Microfibrous-Structured Pd/AlOOH/Al-Fiber for CO Coupling to Dimethyl Oxalate: Effect of Morphology of AlOOH Nanosheet Endogenously Grown on Al-Fiber.

We report a green, template-free, and general one-pot method of endogenous growth of free-standing boehmite (AlOOH) nanosheets on a 3D-network 60 µm-Al-fiber felt through water-only hydrothermal oxidation reaction between Al metal and H2O (2Al + 4H2O → 2AlOOH + 3H2). Content and morphology of AlOOH nanosheets can be finely tuned by adjusting the hydrothermal oxidation time length and temperature. Palladium is highly dispersed on such AlOOH endogenously formed on Al-fiber felt via incipient wetness impregnation method and as-obtained Pd/AlOOH/Al-fiber catalysts are checked in the CO coupling to dimethyl oxalate (DMO) reaction. Interestingly, Pd dispersion is very sensitive to the thickness (26-68 nm) of AlOOH nanosheet, and therefore the conversion shows strong AlOOH-nanosheet-thickness dependence whereas the intrinsic activity (TOF) is AlOOH-nanosheet-thickness independence. The most promising structured catalyst is the one using a microfibrous-structured composite with the thinnest AlOOH nanosheet (26 nm) to support a small amount of Pd of only 0.26 wt %. This catalyst, with high thermal-conductivity and satisfying structural robustness, delivers 67% CO conversion and 96% DMO selectivity at 150 °C using a feed of CH3ONO/CO/N2 (1/1.4/7.6, vol) and a gas hourly space velocity of 3000 L kg-1 h-1, and particularly, is very stable for at least 150 h without deactivation sign.

High-performance PdNi alloy structured in situ on monolithic metal foam for coalbed methane deoxygenation via catalytic combustion.

A monolithic Ni-foam@PdNi(alloy) catalyst is tailored for coalbed methane deoxygenation via galvanically depositing Pd nanoparticles on a Ni-foam surface followed by in situ activation. Experimental and theoretical studies unanimously reveal that the in situ formed PdNi alloy contributes to high activity/selectivity, good stability and oscillation elimination.

Microstructured fiber@HZSM-5 core-shell catalysts with dramatic selectivity and stability improvement for the methanol-to-propylene process.

We report a macroscopic stainless-steel-fiber@HZSM-5 core-shell catalyst by direct growth of 27 wt% HZSM-5 on a 3D microfibrous structure using 20 µm SS fibers, demonstrating dramatic selectivity and stability improvement in the MTP process. The unprecedented performance is due to the promotion of the olefin methylation/cracking cycle in methanol-to-hydrocarbon catalysis.

Preparation and characterization of bionanocomposite fiber based on cellulose and nano-SiO2 using ionic liquid.

Microcrystalline cellulose (MCC)/nano-SiO2 composite fibers were processed from solutions in 1-allyl-3-methylimidazolium chloride (AMIMCl) by the method of dry-jet wet spinning. The oscillatory shear measurements demonstrated that the gel network formed above 10 wt% nano-SiO2 and the complex viscosity increased with increasing nano-SiO2. Remarkably, the shear viscosity of the nanofluids was even lower than solutions without nano-SiO2 under high shear rates. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images revealed that well-dispersed particles exhibit strong interfacial interactions with cellulose matrix. Measurements on wide-angle X-ray diffraction (WAXD) indicated that the regenerated cellulose and nanocomposite fibers were the typical cellulose II crystalline form, which was different from the native cellulose with the polymorph of Type I. The tensile strength of the nanocomposite fibers was larger than that of pure cellulose fiber and showed a tendency to increase and then decrease with increasing nano-SiO2. Furthermore, the nanocomposite fibers exhibited improved thermal stability.

Facile preparation, characterization and photocatalytic properties of multifunctional BiFeO3 nanocrystals.

Polycrystalline BiFeO3 nanoparticles (size 30-50 nm) were prepared by a simple microwave synthesis technique. The nanoparticles were characterized by XRD, TEM and TG-DTA. The applied experiments show that they are very efficient for photo-catalytic decomposition of organic contaminants under irradiation ultraviolet frequency. The as-obtained BiFeO3 nanoparticles also demonstrate strong ferromagnetism of about 0.045 microB/Fe at room temperature, which is in good agreement with theoretical calculations.

Identification of Pns12 as the second silencing suppressor of Rice gall dwarf virus.

RNA silencing is a conserved mechanism found ubiquitously in eukaryotic organisms. It has been used to regulate gene expression and development. In addition, RNA silencing serves as an important mechanism in plants' defense against invasive nucleic acids, such as viruses, transposons, and transgenes. As a counter-defense, most plants, and some animal viruses, encode RNA silencing suppressors to interfere at one or several points of the silencing pathway. In this study, we showed that Pns12 of RGDV (Rice gall dwarf virus) exhibits silencing suppressor activity on the reporter green fluorescent protein in transgenic Nicotiana benthamiana line 16c. Pns12 of RGDV suppressed local silencing induced by sense RNA but had no effect on that induced by dsRNA. Expression of Pns12 also enhanced Potato virus X pathogenicity in N. benthamiana. Collectively, these results suggested that RGDV Pns12 functions as a virus suppressor of RNA silencing, which might target an upstream step of dsRNA formation in the RNA silencing pathway. Furthermore, we showed that Pns12 is localized mainly in the nucleus of N. benthamiana leaf cells.

Identification of Pns6, a putative movement protein of RRSV, as a silencing suppressor.

RNA silencing is a potent antiviral response in plants. As a counterdefense, most plant and some animal viruses encode RNA silencing suppressors. In this study, we showed that Pns6, a putative movement protein of Rice ragged stunt virus (RRSV), exhibited silencing suppressor activity in coinfiltration assays with the reporter green fluorescent protein (GFP) in transgenic Nicotiana benthamiana line 16c. Pns6 of RRSV suppressed local silencing induced by sense RNA but had no effect on that induced by dsRNA. Deletion of a region involved in RNA binding abolished the silencing suppressor activity of Pns6. Further, expression of Pns6 enhanced Potato virus × pathogenicity in N. benthamiana. Collectively, these results suggested that RRSV Pns6 functions as a virus suppressor of RNA silencing that targets an upstream step of the dsRNA formation in the RNA silencing pathway. This is the first silencing suppressor to be identified from the genus Oryzavirus.