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The therapeutic effects of bone marrow mesenchymal stem cells (BMSCs) on severe acute pancreatitis (SAP) and miRNAs are currently the research hotspots. This study intends to explore the potential impact of miR-141-modified BMSCs on SAP. After establishment of rat model of SAP, the animals were grouped into control group, model group, BMSCs group, miR-141 group, positive control group, and PI3K/mTOR signaling agonist group (agonist group) followed by analysis of miR-141 expression by RT-qPCR and the expression of serum amylase, IL-6, TNF-α, TAP, PI3K, mTOR, and LC3-II by Western blot and ELISA. miR-141 was significantly up-regulated in the miR-141-modified BMSCs group (p > 0.05). The contents of serum amylase, IL-6, TNF-α, and TAP was increased in SAP rats and decreased after BMSC treatment (p > 0.05). The increased autophagy flux in the rats with SAT was reduced upon treatment with BMSCs and autophagy flux was decreased in miR-141 group but increased in positive control group. The model and positive control group presented highest expression of LC3-II, p-PI3K and p-mTOR, followed by BMSCs group and miR-141 group (p < 0.05). In conclusion, miR-141-modified BMSCs decrease the phosphorylation of PI3K and mTOR to inhibit PI3K/mTOR signaling activity and downregulate LC3-II protein to inhibit autophagy, thereby ameliorating the development of SAP, indicating that miR-141 might be a therapeutic target for SAP.

The topological electronic structure plays a central role in the non-trivial physical properties in topological quantum materials. A minimal, hydrogen-atom-like topological electronic structure is desired for researches. In this work, we demonstrate an effort towards the realization of such a system in the intrinsic magnetic topological insulator MnBi2Te4, by manipulating the topological surface state (TSS) via surface modification. Using high resolution laser- and synchrotron-based angle-resolved photoemission spectroscopy (ARPES), we found the TSS in MnBi2Te4 is heavily hybridized with a trivial Rashba-type surface state (RSS), which could be efficiently removed by the in situ surface potassium (K) dosing. By employing multiple experimental methods to characterize K dosed surface, we attribute such a modification to the electrochemical reactions of K clusters on the surface. Our work not only gives a clear band assignment in MnBi2Te4, but also provides possible new routes in accentuating the topological behavior in the magnetic topological quantum materials.

α-pinene is the most abundant monoterpene that represents an important family of volatile organic compounds. Molecular identification of key transient compounds during the α-pinene ozonolysis has been proven to be a challenging experimental target because of a large number of intermediates and products involved. Here we exploit the recently developed hybrid instruments that integrate aerosol mass spectrometry with a vacuum ultraviolet free-electron laser to study the α-pinene ozonolysis. The experiments of α-pinene ozonolysis are performed in an indoor smog chamber, with reactor having a volume of 2 m3 which is made of fluorinated ethylene propylene film. Distinct mass spectral peaks provide direct experimental signatures of previously unseen compounds produced from the reaction of α-pinene with O3. With the aid of quantum chemical calculations, plausible mechanisms for the formation of these new compounds are proposed. These findings provide crucial information on fundamental understanding of the initial steps of α-pinene oxidation and the subsequent processes of new particle formation.

Much attention is drawn to polycyclic aromatic hydrocarbons (PAHs) as an air pollutant due to their toxic, mutagenic and carcinogenic properties. Therefore, to understand the levels, seasonality, sources and potential health risk of PAHs in two distinct geographical locations at Karachi and Mardan in Pakistan, total suspended particle (TSP) samples were collected for over one year period. The average total PAH concentrations were 31.5 ± 24.4 and 199 ± 229 ng/m3 in Karachi and Mardan, respectively. The significantly lower concentration in Karachi was attributed to diffusion and dilution of the PAHs by the influence of clean air mass from the Arabian sea and high temperature, enhancing the volatilization of the particle phase PAHs to the gas phase. Conversely, the higher concentration (~6 times) in Mardan was due to large influence from local and regional emission sources. A clear seasonality was observed at both the sites, with the higher values in winter and post-monsoon due to higher emissions and less scavenging, and lower values during monsoon season due to the dilution effect. Diagnostic ratios and principal component analysis indicated that PAHs in both sites originated from traffic and mixed combustion sources (fossil fuels and biomass). The average total BaP equivalent concentrations (BaPeq) in Karachi and Mardan were 3.26 and 34 ng/m3, respectively, which were much higher than the WHO guideline of 1 ng/m3. The average estimates of incremental lifetime cancer risk from exposure to airborne BaPeq via inhalation indicated a risk to human health from atmospheric PAHs at both sites.

The evolution of the physical properties of two-dimensional material from monolayer limit to the bulk reveals unique consequences from dimension confinement and provides a distinct tuning knob for applications. Monolayer 1T'-phase transition metal dichalcogenides (1T'-TMDs) with ubiquitous quantum spin Hall (QSH) states are ideal two-dimensional building blocks of various three-dimensional topological phases. However, the stacking geometry was previously limited to the bulk 1T'-WTe2 type. Here, we introduce the novel 2M-TMDs consisting of translationally stacked 1T'-monolayers as promising material platforms with tunable inverted bandgaps and interlayer coupling. By performing advanced polarization-dependent angle-resolved photoemission spectroscopy as well as first-principles calculations on the electronic structure of 2M-TMDs, we revealed a topology hierarchy: 2M-WSe2, MoS2, and MoSe2 are weak topological insulators (WTIs), whereas 2M-WS2 is a strong topological insulator (STI). Further demonstration of topological phase transitions by tunning interlayer distance indicates that band inversion amplitude and interlayer coupling jointly determine different topological states in 2M-TMDs. We propose that 2M-TMDs are parent compounds of various exotic phases including topological superconductors and promise great application potentials in quantum electronics due to their flexibility in patterning with two-dimensional materials.

Structural characterization of neutral water clusters is crucial to understanding the structures and properties of water, but it has been proven to be a challenging experimental target due to the difficulty in size selection. Here, we report the size-specific infrared spectra of confinement-free neutral water nonamer (H

This study was conducted in the Central Himalayan middle hills to understand the nature of polycyclic aromatic hydrocarbons (PAHs) embedded in aerosol particles, their sources and human health risk assessments. The level of sum of 15 particlephase PAHs was between 9 and 335 ng/m3, with an average concentration of 73±66 ng/ m3. There were strong seasonal differences in total suspended particles (TSP) and particle- bound PAH concentrations with higher concentrations in winter, followed by premonsoon and lowest in monsoon. The main contributor to the suspended particles was 5-ring PAHs (32%), followed by 4-ring (29%), 6-ring (28%), and 3-ring PAHs (11%). Conversely, the gas-phase PAHs showed that 3-ring PAHs contributed utmost to the total particles. The molecular ratios and principal component analysis indicated that both petrogenic and pyrogenic sources, particularly fossil fuel combustion, biomass combustion, and car exhausts, were the major sources of PAHs. The overall average Benzo (a)pyrene equivalent concentration of particulate PAHs was 11.71 ng/m3, which substantially exceeded the WHO guideline (1 ng/m3), and indicated the potential health risks for local residents. The average lifetime inhalation cancer risk (ILCR) estimates associated with carcinogenic PAHs was 8.78×10-6 for adults, suggesting the possible cancer risk and 2.47×10-5 for children, signifying extreme carcinogenic effects of PAHs on children’s health. Therefore, strict measures should be taken to reduce PAHs emissions in the region.

The confinement of concrete enhances its strength and ductility by restraining lateral dilation. The accuracy of a confinement model depends on how well it captures the dilation of concrete. In the current paper, a mesoscale model is established to study the dilation properties of concrete in active confinement, where the heterogeneity of concrete is considered. The stress–strain and lateral–axial strain curves of concrete in active confinement were used to demonstrate the validity of the mesoscale model. Subsequently, the distribution of lateral strain and the influences of the strength grade and confinement ratio on the dilation of concrete were investigated in a simulation. The results show that the distribution of the lateral strain along the radial or longitudinal directions is not uniform on the specimen when compressive failure occurs. The confinement ratio has a more significant influence on the concrete’s transverse dilation than the strength grade. Finally, an expression of the lateral–axial strain relationship of concrete in active confinement is proposed. The proposed formula can reflect the simulation results of the mesoscale model and is in good agreement with the prediction of existing formulas.

Spectroscopic characterization of clusters is crucial to understanding the structures and reaction mechanisms at the microscopic level, but it has been proven to be a grand challenge for neutral clusters because the absence of a charge makes it difficult for the size selection and detection. Infrared (IR) spectroscopy based on threshold photoionization using a tunable vacuum ultraviolet free electron laser (VUV-FEL) has recently been developed in the lab. The IR-VUV depletion and IR+VUV enhancement spectroscopic techniques open new avenues for size-selected IR spectroscopies of a large variety of neutral clusters without confinement (i.e., an ultraviolet chromophore, a messenger tag, or a host matrix). The spectroscopic principles have been demonstrated by investigations of some neutral water clusters and some metal carbonyls. Here, the spectroscopic principles and their applications for neutral clusters are reviewed.

The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO)n− (n = 5–8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy. During the consecutive CO adsorption, the μ2-O-bent structure initially is the most favorable for TaNiO(CO)5−, and subsequently both μ2-O-bent and μ2-O-linear structures are degenerate for TaNiO(CO)6−, then the μ2-O-linear structure is most preferential for TaNiO(CO)7−, and finally the η2-CO2-tagged structure is the most energetically competitive one for TaNiO(CO)8−, i.e., the CO oxidation occurs at n = 8. In contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir–Hinshelwood-like mechanism, complementary theoretical calculations suggest that both Langmuir–Hinshelwood-like and Eley–Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)8− complex. Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes, of which the composition be tailored to fulfill the desired chemical behaviors.

Neutral titanium-metal carbonyl complexes with the chemical formula Ti(CO)n (n = 4-7) are produced in the gas phase by the reactions of titanium atoms with carbon monoxide in a pulsed laser vaporization-supersonic expansion source. Their infrared absorption spectra in the carbonyl stretching frequency region are measured by infrared plus vacuum ultraviolet (IR+VUV) two-color ionization spectroscopy based on a tunable VUV free electron laser. Infrared spectroscopy in conjunction with quantum chemical calculations confirm that all of these complexes have unexpected titanium ketenylidene OTiCCO(CO)n-2 structures. Bonding analysis indicates that the OTiCCO core structure can be described by the bonding interactions between a TiO+ cation in the doublet ground state and a doublet ground state of CCO-. The results reveal that the C-O bond breaking and C-C bond formation proceed efficiently in the reactions between laser-vaporized titanium atoms and carbon monoxide.

Experimental characterization of microscopic events and behaviors of SO

The CO2 activation by transition metals is important in CO2 utilization but has proven to be challenging for experimental targets. Here we report first synthesis and spectroscopic characterization of transition-metal M[η2-(O,O)C] species with bidentate double oxygen metal-CO2 coordination in the [ZrO(CO2)n≥4]+ complexes. The Zr[η2-(O,O)C] species yields a CO2- radical ligand, showing a high efficiency in CO2 activation. We find that two important prerequisites are demanded for certain metals to form this intriguing M[η2-(O,O)C] species. One is that the metal center has high reduction capability, and the other is that the oxidation state of the metal center is lower than its highest one by 1. This study highlights the pivotal roles played by the M[η2-(O,O)C] species in CO2 activation and also open new avenues toward the development of related single-atom catalysts with isolated transition-metal atoms dispersed on supports.

Infrared photodissociation spectroscopy of mass-selected [MO(CO2)n]+ (M=Sc, Y, La) complexes indicates that the conversion from the solvated structure into carbonate one can be achieved by the ScO+ cation at n=5 and by the YO+ cation at n=4, while only the solvated structures are observed for the LaO+ cation. These findings suggest that both the ScO+ and YO+ cations are able to fix CO2 into carbonate. Quantum chemical calculations are performed on [MO(CO2)n]+ to identify the structures of the low-lying isomers and to assign the observed spectral features. Theoretical analyses show that the [YO(CO2)n]+ complex has the smallest barrier for the conversion from the solvated structure into carbonate one, while [LaO(CO2)n]+ exhibits the largest conversion barrier among the three metal oxide cations. The present system affords a model in clarifying the effect of different metals in catalytic CO2 transformation at the molecular level.

A series of heteronuclear group 5 metal-nickel carbonyls MNi(CO)7- (M = V, Nb, Ta) have been generated via a laser ablation ion source and studied by photoelectron velocity-map imaging spectroscopy. Quantum chemical calculations have been performed to probe the electronic and geometric structures and help to assign the spectra. The adiabatic detachment energies (ADEs) and vertical detachment energies (VDEs) are deduced from spectra to be 3.40/3.58, 3.34/3.55, 3.30/3.50 eV, which are consistent with quantum chemical computational results. The MNi(CO)7- (M = V, Nb, Ta) consists of three bridging carbonyls, one carbonyl terminally bonded to the Ni atom and three carbonyls terminally bonded to the M (M = V, Nb, Ta) atom. These geometries are different from homobinuclear Cr2(CO)7+, Ni2(CO)7+, Pd2(CO)7+, and Fe2(CO)7- and heterobinuclear CuFe(CO)7-, CoZn(CO)7+, and CO is largely activated by a bridging coordination mode. The experimental and theoretical results would provide important information to understand the chemisorbed CO molecules on alloy surfaces or interfaces, which is of great significance to elucidate CO molecule activation processes.

The structures, energetics, and infrared (IR) spectra of the cationic monomethylamine-water clusters, [(CH $_3$ NH $_2$ )(H $_2$ O) $_n$ ] $^+$ ( $n$ =1 $-$ 5), have been studied using quantum chemical calculations at the MP2/6-311+G(2d,p) level. The results reveal that the formation of proton-transferred CH $_2$ NH $_3$ $^+$ ion core structure is preferred via the intramolecular proton transfer from the methyl group to the nitrogen atom and the water molecules act as the acceptor for the O $\cdots$ HN hydrogen bonds with the positively charged NH $_3$ $^+$ moiety of CH $_2$ NH $_3$ $^+$ , whose motif is retained in the larger clusters. The CH $_3$ NH $_2$ $^+$ ion core structure is predicted to be less energetically favorable. Vibrational frequencies of CH stretches, hydrogen-bonded and free NH stretches, and hydrogen-bonded OH stretches in the calculated IR spectra of the CH $_2$ NH $_3$ $^+$ and CH $_3$ NH $_2$ $^+$ type structures are different from each other, which would afford the sensitive probes for fundamental understanding of hydrogen bonding networks generated from the radiation-induced chemical processes in the [(CH $_3$ NH $_2$ )(H $_2$ O) $_n$ ] $^+$ complexes.

Janus kinase 1 (JAK1) is a member of JAK family of non-receptor protein tyrosine kinases that plays critical roles in transducing cytokine signals via JAK-signal transducer and activator of transcription (STAT) signaling pathway. The importance of JAK1 in innate immunity has been well-studied in mammals and fish, yet in avian remains largely unknown. Here, we cloned the full-length of the duck JAK1 (duJAK1) gene for the first time. DuJAK1 encoded a protein of 1152 amino acids and possessed high amino acid identity with goose and budgerigar JAK1s. The duJAK1 was expressed in all detected tissues, especially high in the thymus and bursa of Fabricius. Overexpression of duJAK1 significantly activated ISRE promoter activity and induced duck viperin, 2', 5'-OAS, MX, PKR and ZAP expression. Knockdown of duJAK1 by small interfering RNA significantly inhibited duck Tembusu virus (DTMUV)-, duck Enteritis virus (DEV)-, poly (I:C)-, poly (dA:dT)- or Sendai virus (SeV)-induced ISRE promoter activation. Furthermore, duJAK1 exhibited antiviral activity against DTMUV infection. These results will help us understand the function of JAK family proteins in duck antiviral immunity.

A neutral boron carbonyl complex B

To elucidate the molecular composition and sources of organic aerosols in Central Asia, carbonaceous compounds, major ions, and 15 organic molecular tracers of total suspended particulates (TSP) were analyzed from September 2018 to August 2019 in Dushanbe, Tajikistan. Extremely high TSP concentrations (annual mean ± std: 211 ± 131 μg m

Porcine epidemic diarrhea virus (PEDV) is the predominant cause of an acute, highly contagious enteric disease in neonatal piglets. There are currently no approved drugs against PEDV infection. Here, we report the development of a nanoluciferase (NLuc)-based high-throughput screening (HTS) platform to identify novel anti-PEDV compounds. We constructed a full-length cDNA clone for a cell-adapted PEDV strain YN150. Using reverse genetics, we replaced the open reading frame 3 (ORF3) in the viral genome with an NLuc gene to engineer a recombinant PEDV expressing NLuc (rPEDV-NLuc). rPEDV-NLuc produced similar plaque morphology and showed similar growth kinetics compared with the wild-type PEDV in vitro. Remarkably, the level of luciferase activity could be stably detected in rPEDV-NLuc-infected cells and exhibited a strong positive correlation with the viral titers. Given that NLuc expression represents a direct readout of PEDV replication, anti-PEDV compounds could be easily identified by quantifying the NLuc activity. Using this platform, we screened for the anti-PEDV compounds from a library of 803 natural products and identified 25 compounds that could significantly inhibit PEDV replication. Interestingly, 7 of the 25 identified compounds were natural antioxidants, including Betulonic acid, Ursonic acid, esculetin, lithocholic acid, nordihydroguaiaretic acid, caffeic acid phenethyl ester, and grape seed extract. As expected, all of the antioxidants could potently reduce PEDV-induced oxygen species production, which, in turn, inhibit PEDV replication in a dose-dependent manner. Collectively, our findings provide a powerful platform for the rapid screening of promising therapeutic compounds against PEDV infection.

A special electrochemical sensor was developed based on molecularly imprinted polymer (MIP), which was formed by the dopamine (DA) self-polymerization on the surface of Pd-Cu bimetallic alloy functionalized poly (diallyldimethylammonium chloride) -dispersed graphene (PDDA-Gr). This sensor takes advantages of molecularly imprinted technique and nanocomposite to realize the application of amaranth determination with high selectivity and sensitivity. In this study, the nanocomposite PDDA-Gr-(Pd-Cu) characterized by various techniques provides large surface area and accelerates the electron transfer process. The imprinted composite deposited on the surface of PDDA-Gr-(Pd-Cu), not only provides abundant specific cavities to amaranth, but also decreases the thickness of molecularly imprinted polymer leading to high conductivity. The electrochemical behavior of amaranth on the modified electrode was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). After optimization, the anodic peak current showed a linear relationship with the concentration of amaranth in the range of 0.006–10 μM, and the limit of detection (LOD) was 2 nM. The proposed sensor distinguished amaranth from other structurally similar substances such as sunset yellow and tartrazine with good results. In addition, the molecularly imprinted sensor proposed in this study was successfully applied to determine amaranth in the soft drink with satisfactory recoveries.

The mass-selected infrared photodissociation (IRPD) spectroscopy was utilized to investigate the interactions of cationic cobalt with carbon dioxide molecules. Quantum chemical calculations were performed on the [Co(CO $_2$ ) $_n$ ]+clusters to identify the structures of the low-lying isomers and to assign the observed spectral features. All the [Co(CO $_2$ ) $_n$ ]+ ( $n$ =2 $-$ 6) clusters studied here show resonances near the CO $_2$ asymmetric stretch of free CO $_2$ molecule. Experimental and calculated results indicate that the CO $_2$ molecules are weakly bound to the Co+ cations in an end-on configuration via a charge-quadrupole electrostatic interaction. The present IRPD spectra of [Co(CO $_2$ ) $_n$ ]+ clusters have been compared to those of Ar-tagged species ([Co(CO $_2$ ) $_n$ ]+-Ar), which would provide insights into the tagging effect of rare gas on the weakly-bounded clusters.

Three novel electrochemical sensors constructed by Pd-Pt bimetallic nanocages, Pt-Cu bimetallic nanoframes and Co-Ni bimetallic nanoflowers and poly (diallyldimethylammonium chloride) (PDDA)-dispersed graphene (Gr) were applied to determine sunset yellow (SY, E110). The PDDA-Gr-(Pd-Pt), PDDA-Gr-(Pt-Cu) and PDDA-Gr-(Co-Ni) nanocomposites formed different nanostructure with unique features and were characterized by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). The special morphology of the three bimetallic nanoparticles endows the designed electrochemical sensors with large active areas and good electrical conductivity, which provides more active sites for the target analyte and improves the sensitivity of the determination of sunset yellow. The developed sensors were investigated and compared with each other on the determination of SY by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimal experimental condition, the anodic peak currents of sunset yellow on three modified electrodes was linearly correlated with the concentration of sunset yellow in the ranges of 0.02–10.0, 0.02–10.0, 0.008–10.0 μM, respectively. The limits of detection (LOD) of SY were 6.0, 4.0 and 2.0 nM, respectively. In addition, the three new proposed sensors in this study were successfully applied to determine SY in real soft drink sample. This study provides a new platform for designing sensitive electrochemical sensor based on non-noble metals with low cost.

Duck Tembusu virus (DTMUV), an emergent flavivirus, causes domestic waterfowls to suffer from severe egg-drop syndrome and fatal encephalitis, greatly threatens duck production globally. Like other mosquito-borne flaviviruses, the envelope (E) protein of all DTMUV strains was N-glycosylated at the amino acid position 154. Thus far, the biological roles of DTMUV E glycosylation have remained largely unexplored. Herein, we demonstrated the key roles of E glycosylation in the replication and pathogenicity of DTMUV in ducks by characterizing the reverse-genetics-derived DTMUV wild-type MC strain and MC bearing mutations (N154Q and N154I) that abolish the E glycosylation. Our data showed that the disruption of E glycosylation could substantially impair virus attachment, entry, and infectivity in DEFs and C6/36 cells. Notably, ducks inoculated intracerebrally with the wild-type virus exhibited severe disease onset. In contrast, those inoculated with mutant viruses were mildly affected as manifested by minimal weight loss, no mortality, lower viral loads in the various tissues, and reduced brain lesions. Attenuated phenotypes of the mutant viruses might be partly associated with lower inflammatory cytokines expression in the brains of infected ducks. Our study offers the first evidence that E glycosylation is vital for DTMUV replication, pathogenicity, and neurovirulence in vivo.

The CO